Polyester film layer with antistatic structure and preparation method thereof

Abstract

The invention relates to the technical field of polyester films, and discloses a polyester film layer with an antistatic structure and a preparation method thereof. The polyester film adopts a sandwich structure, the middle layer of the structure is dendritic conductive polyester, and the two sides of the structure are quaternary ammonium salt antistatic agent coatings. The antistatic agent is combined with water molecules in the air to form a conductive ion channel and reduce the surface resistance, the dendritic conductive polymer forms a conductive path in the material, and the antistatic agent and the dendritic conductive polymer have a synergistic effect to construct a more perfect conductive network in the material and on the surface of the material, so that static electricity can be conducted and dissipated more quickly. Meanwhile, the dendritic conductive polyester can also provide support and fixation for the antistatic agent, prevent the antistatic agent from losing or losing efficacy in the use process, enhance the stability and durability of the antistatic performance of the material in different environments, and reduce the reduction of the antistatic effect caused by prolonged service time or environmental factors.

Description

Technical Field

[0001] The invention belongs to the technical field of polyester films, and in particular relates to a polyester film layer with an antistatic structure and a preparation method thereof. Background Art

[0002] Polyester film is widely used in industry, commerce, medical treatment and daily life due to its good tensile strength, barrier properties and chemical resistance.

[0003] As the packaging requirements for electronic products and precision instruments continue to increase, the problem of static electricity in ordinary polyester films has gradually become prominent. Static electricity easily absorbs dust, which not only affects the appearance of the product, but may also damage the performance of electronic products. In the packaging process of electronic components, static electricity discharge may cause short circuits and damage to components, resulting in huge economic losses. Therefore, antistatic polyester film came into being, which can effectively reduce the accumulation of static electricity inside the packaging and protect products from the harm of static electricity.

[0004] At present, the antistatic durability of some antistatic polyester films is insufficient. Over time or under certain conditions, the antistatic performance will gradually decrease, and it is impossible to stably meet the packaging needs in the long term. In addition, the production process of antistatic polyester films also faces many challenges. On the one hand, existing antistatic additives or treatment processes may affect the original properties of polyester films, such as tensile strength and barrier properties. How to achieve the antistatic function while maintaining other excellent properties of polyester films to the greatest extent is an urgent problem to be solved. On the other hand, the production efficiency of antistatic polyester films needs to be improved, and the production cost needs to be further reduced to meet the needs of large-scale market applications. When adding antistatic ingredients, traditional production processes may increase the complexity of the production process, resulting in longer production cycles and higher costs.

[0005] Therefore, it is particularly important to provide a polyester film with an antistatic structure and a preparation method thereof. Summary of the invention

[0006] The present invention aims to provide a polyester film layer with an antistatic structure and a preparation method thereof. The film is a sandwich structure. The antistatic agent on the surface combines with water molecules in the air to form a conductive ion channel to reduce the surface resistance. The dendritic conductive polymer in the middle layer forms a conductive path inside the material. The two act synergistically to build a more complete conductive network inside and on the surface of the material, so that static electricity can be quickly conducted and dissipated. At the same time, the dendritic conductive polyester can also provide support and fixation for the antistatic agent, prevent the antistatic agent from being lost or ineffective during use, enhance the stability and durability of the antistatic performance of the material in different environments, and reduce the decline in antistatic effect caused by extended use time or environmental factors.

[0007] In order to achieve the above object, the present invention provides a polyester film layer with an antistatic structure, comprising a dendritic conductive polyester film, wherein the upper layer of the dendritic conductive polyester film is provided with a first antistatic agent coating, and the lower layer of the dendritic conductive polyester film is provided with a second antistatic agent coating; the dendritic conductive polyester film is obtained by polymerizing pentaerythritol, glycerol, terephthalic acid and aniline, and the first antistatic agent coating and the second antistatic agent coating are obtained by mixing a quaternary ammonium salt antistatic agent and anhydrous ethanol; the structural formula of the dendritic conductive polyester in the dendritic conductive polyester film is as follows:

[0008] Wherein, in the structural formula, n is an integer between 1 and 10, and m is an integer between 1 and 10.

[0009] The present invention also provides a method for preparing a polyester film layer with an antistatic structure, comprising: Step S1, dissolving pentaerythritol in a first solvent, adding potassium carbonate and benzyl chloride, reacting to obtain a crude benzyl-substituted pentaerythritol product, and extracting and drying to obtain the benzyl-substituted pentaerythritol; Step S2, diluting acetyl chloride with a second solvent to obtain a solution A, dissolving benzyl-substituted pentaerythritol with the second solvent to obtain a solution B, mixing solution A and solution B under ice bath conditions, adding acid to catalyze, reacting to obtain a crude functionalized pentaerythritol product, and extracting and drying to obtain a functionalized pentaerythritol; Step S3, adding functionalized pentaerythritol, glycerol and p-toluenesulfonic acid to a third solvent, heating to reflux, adding a base to terminate the reaction, obtaining a crude dendritic polyol product, and performing a first recrystallization and drying to obtain a dendritic polyol; Step S4, dissolving terephthalic acid and dendritic polyol in a first solvent, adding a catalyst, reacting in a reactor to obtain a dendritic polyester crude product, and performing a second recrystallization and drying to obtain a dendritic polyester; Step S5, adding the dendritic polyester to the first solvent to dissolve, adding phosphorus oxychloride, performing a first reaction, adding aniline and an initiator, performing a second reaction to obtain a crude dendritic conductive polyester product, and washing and drying to obtain the dendritic conductive polyester; Step S6, the dendritic conductive polyester is added into a twin-screw extruder, filtered through a filter screen, and extruded into a thick film through a die head. The thick film enters a longitudinal heating and stretching unit and a transverse heating and stretching unit in sequence to obtain a film for heat setting and cooling to obtain a dendritic conductive polyester film; Step S7, dissolving a quaternary ammonium salt antistatic agent in anhydrous ethanol, using a coating machine to apply a first antistatic agent coating and a second antistatic agent coating on both sides of the dendritic conductive polyester film, and drying with hot air to obtain an antistatic polyester film layer.

[0010] Preferably, the first solvent is any one or more of N, N'-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0011] Preferably, the second solvent is any one or more of tetrahydrofuran, dichloromethane, methanol and acetonitrile.

[0012] Preferably, the third solvent is any one or more of benzene, toluene, xylene and acetone.

[0013] Preferably, the washing solvent is deionized water.

[0014] Preferably, the extraction solvent is ethyl acetate.

[0015] Preferably, in step S1, the reaction temperature is 40-60° C., and the reaction time is 4-6 h.

[0016] Preferably, in step S1, the drying temperature is 40-60° C., and the drying time is 12-20 h.

[0017] Preferably, in step S1, the mass ratio of pentaerythritol, benzyl chloride, potassium carbonate and the first solvent is 1:(2-2.8):(2.3-3.7):(20-30).

[0018] Preferably, in step S2, the acid is any one or more of hydrochloric acid, sulfuric acid, formic acid, and acetic acid, with a concentration of 2 mol / L and an amount of 5 to 10 mL.

[0019] Preferably, in step S2, the reaction temperature is 25-40° C., and the reaction time is 7-8 h.

[0020] Preferably, in step S2, the drying temperature is 50-80° C., and the drying time is 8-10 h.

[0021] Preferably, in step S2, the mass ratio of acetyl chloride to the second solvent is 1:(1.4-1.7).

[0022] Preferably, in step S2, the mass ratio of the benzyl-substituted pentaerythritol to the second solvent is 1:(4-6).

[0023] Preferably, in step S3, the heating reflux temperature is 100-150° C., and the heating reflux time is 12-20 h.

[0024] Preferably, in step S3, the drying temperature is 50-60° C., and the drying time is 8-10 h.

[0025] Preferably, in step S3, the base is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate, with a concentration of 0.5-1.2 mol / L and an amount of 3-5 mL.

[0026] Preferably, in step S3, the mass ratio of the functionalized pentaerythritol, glycerol, p-toluenesulfonic acid and the third solvent is 1: (0.7-0.8): (0.008-0.01): (3-6).

[0027] Preferably, in step S3, the solvent for the first recrystallization is ethyl acetate.

[0028] Preferably, in step S4, the catalyst is any one or more of tetrabutyl titanate, stannous octoate, and butyltin laurate.

[0029] Preferably, in step S4, the reaction temperature in the reactor is 150-200° C., and the reaction time is 8-10 h.

[0030] Preferably, in step S4, the drying temperature is 60-80° C., and the drying time is 7-8 h.

[0031] Preferably, in step S4, the mass ratio of the dendritic polyol, terephthalic acid, catalyst and first solvent is 1: (2.3-2.5): (0.05-0.12): (5-6).

[0032] Preferably, in step S4, the solvent for the second recrystallization is chloroform.

[0033] Preferably, in step S5, the initiator is any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate.

[0034] Preferably, in step S5, the temperature of the first reaction is 0-5° C., and the time of the first reaction is 8-10 h.

[0035] Preferably, in step S5, the temperature of the second reaction is 70-100° C., and the time of the second reaction is 8-10 h.

[0036] Preferably, in step S5, the drying temperature is 70-80° C., and the drying time is 10-12 h.

[0037] Preferably, in step S5, the mass ratio of the dendritic polyester, aniline, initiator, phosphorus oxychloride and the first solvent is 1: (10-20): (0.05-0.1): (0.01-0.03): (30-40).

[0038] Preferably, in step S6, the preset temperature of the twin-screw extruder is 260-290° C., and the preset screw speed is 60-100 rpm, so that the polyester is melted quickly through heating and the shearing effect of the screw.

[0039] Preferably, in step S6, the mesh size of the filter is 200-300 meshes, so as to remove impurities and particles in the raw materials and ensure the purity of the melt.

[0040] Preferably, in step S6, the thickness of the thick film is 1-2 mm.

[0041] Preferably, in step S6, the heating temperature of the longitudinal heating and stretching unit is 80-120° C., and the stretching ratio is 3-5 times, so as to improve the longitudinal strength and orientation degree of the film.

[0042] Preferably, in step S6, the heating temperature of the transverse heating and stretching unit is 100-150° C., the stretching ratio is 3-5 times, and the molecular chains of the film after biaxial stretching are oriented in both the longitudinal and transverse directions, which greatly improves the physical properties of the film.

[0043] Preferably, in step S6, the heat setting temperature is 200-250° C. and the time is 10-15 s to eliminate the stress inside the film and increase the crystallinity of the polyester molecules, thereby improving the heat resistance, dimensional stability and other properties of the film.

[0044] Preferably, in step S6, the cooling temperature is 30-50° C., so that the film is cooled and solidified quickly.

[0045] Preferably, in step S7, the antistatic agent is a quaternary ammonium salt antistatic agent, including any one or more of didodecyl dimethyl ammonium chloride, dioctadecyl dimethyl ammonium chloride, and didecyl dimethyl ammonium chloride.

[0046] Preferably, in step S7, the mass ratio of the antistatic agent to anhydrous ethanol is (1-2):20.

[0047] Preferably, in step S7, the preset speed of the coating roller of the coating machine is 3-6 m / min, and the gap between the scraper and the coating roller is 0.3-0.6 mm.

[0048] Preferably, in step S7, the hot air drying has a drying temperature of 50-70° C., a hot air flow rate of 1-5 m / s, and a drying time of 5-10 min.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts pentaerythritol, glycerol, terephthalic acid and aniline to polymerize to obtain a dendritic conductive polyester with a highly branched and stable three-dimensional structure. Compared with traditional linear conductive polymers, the branched molecular form of the dendritic conductive polyester can provide multiple channels for electron conduction, and the conjugated structure and electron delocalization system in the molecule enable electrons to move efficiently on the polymer chain, increase the number of conductive paths, and reduce the resistance of electron conduction; the three-dimensional structure helps to maintain the stability of charge transmission, and even when it is locally disturbed by external factors, electrons can still be transmitted through other branch paths.

[0050] In the present invention, the polyester film layer adopts a "sandwich" multilayer composite structure, the middle layer is a dendritic conductive polyester film, and the upper and lower layers are quaternary ammonium salt antistatic agent coatings, which produce a synergistic antistatic effect with the dendritic conductive polyester in the middle layer while maintaining high transparency and glossiness. The antistatic agent forms a conductive layer on the surface of the material by absorbing moisture in the environment, reduces the resistance of the material surface, and provides more conductive sites. The conductive polymer forms a continuous conductive path inside the material. The two cooperate to build a more complete conductive network, so that static electricity can be conducted and dissipated more quickly. At the same time, the dendritic conductive polyester can provide better support and fixation for the antistatic agent, preventing it from being lost or failing during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the preparation process of the antistatic structural polyester film layer.

[0052] Figure 2 Schematic diagram of the synthesis route of dendritic conductive polyester.

[0053] Figure 3 Schematic diagram of the structure of the antistatic polyester film layer.

[0054] Meaning of the reference numerals: 1. first antistatic agent coating, 2. dendritic conductive polyester film, 3. second antistatic agent coating. DETAILED DESCRIPTION

[0055] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the protection scope of the present invention.

[0056] The main compounds used in the examples and comparative examples are all commercially available products without any further purification.

[0057] Example 1 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer comprises the following steps: Step S1, accurately weigh 5 g of pentaerythritol and dissolve it in 50 g of N, N'-dimethylformamide, add 10 g of benzyl chloride and 11.5 g of potassium carbonate in sequence, and react at 40°C for 6 h to obtain a crude benzyl-substituted pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the mixture is placed in a drying oven at 40°C for 20 h to obtain a benzyl-substituted pentaerythritol.

[0058] Step S2: accurately weigh 22.5 g of acetyl chloride, dilute with 45 g of tetrahydrofuran to obtain solution A, accurately weigh 5 g of benzyl-substituted pentaerythritol, dissolve with 25 g of tetrahydrofuran to obtain solution B, dropwise add all of solution A to solution B under ice bath conditions, add 10 mL of 2 mol / L hydrochloric acid solution, react at 25°C for 8 h, and obtain a crude functionalized pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the product is placed in a drying oven at 50°C for 10 h to obtain a crude functionalized pentaerythritol product.

[0059] Step S3, accurately weigh 5 g of functionalized pentaerythritol, 3.5 g of glycerol, and 0.04 g of p-toluenesulfonic acid, add them to 20 g of toluene, heat and reflux at 100°C for 20 h, add 5 mL of 1 mol / L sodium hydroxide solution to terminate the reaction, and obtain a crude dendritic polyol. The crude product is recrystallized from ethyl acetate, filtered, and dried in a drying oven at 50°C for 10 h to obtain a dendritic polyol.

[0060] Step S4, accurately weigh 11.5 g of terephthalic acid and 5 g of dendritic polyol, dissolve them in 30 g of N, N'-dimethylformamide, add 0.25 g of tetrabutyl titanate, react in a reactor at 150°C for 10 h, after the reaction is completed, dissolve all the crude dendritic polyester in chloroform, filter out the insoluble matter, filter, wash, and dry in a drying oven at 60°C for 8 h to obtain the dendritic polyester.

[0061] Step S5, accurately weigh 1 g of dendritic polyester and dissolve it in 30 g of N, N'-dimethylformamide, add 0.01 g of phosphorus oxychloride, react 10 g at 0°C, then add 10 g of aniline and 0.05 g of azobisisobutyronitrile, react at 70°C for 10 h to obtain a crude dendritic conductive polyester, wash with deionized water, and dry at 70°C for 12 h to obtain a dendritic conductive polyester, such as Figure 2 shown.

[0062] Step S6, add 10 g of dendritic conductive polyester to a twin-screw extruder, melt at 260°C at a speed of 60 rpm, filter impurities and unmelted particles through a 200-mesh filter, and extrude through a die to obtain a thick film with a thickness of 1 to 2 mm. The thick film enters a longitudinal heating stretching unit at a temperature of 80°C to stretch the film to 3 times its original length; then, the film enters a transverse heating stretching unit at a temperature of 100°C to stretch the film to 3 times its original width. The obtained film is heat-set at 200°C for 15 s, and sent to a cooling roller at 30°C for cooling and solidification to obtain a dendritic conductive polyester film 2.

[0063] Step S7, accurately weigh 5 g of didodecyl dimethyl ammonium chloride, dissolve it in 100 g of anhydrous ethanol, use a coating machine to apply the first antistatic agent coating 1 and the second antistatic agent coating 3 on both sides of the dendritic conductive polyester film 2, and dry it in a hot air drying oven at 50° C. with a hot air flow rate of 1 m / s for 10 min to obtain an antistatic polyester film layer, such as Figure 3 shown.

[0064] Example 2 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer comprises the following steps: Step S1, accurately weigh 5 g of pentaerythritol and dissolve it in 50 g of N, N'-dimethylformamide, add 12 g of benzyl chloride and 15.5 g of potassium carbonate in sequence, and react at 50°C for 5 h to obtain a crude benzyl-substituted pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the mixture is placed in a drying oven at 50°C for 16 h to obtain pure benzyl-substituted pentaerythritol.

[0065] Step S2: accurately weigh 25.5 g of acetyl chloride, dilute with 45 g of tetrahydrofuran to obtain solution A, accurately weigh 5 g of benzyl-substituted pentaerythritol, dissolve with 25 g of tetrahydrofuran to obtain solution B, dropwise add all of solution A to solution B under ice bath conditions, add 10 mL of 2 mol / L hydrochloric acid solution, react at 30°C for 8 h, and obtain a crude functionalized pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the product is placed in a drying oven at 65°C for 9 h to obtain a functionalized pentaerythritol.

[0066] Step S3, accurately weigh 5 g of functionalized pentaerythritol, 4 g of glycerol, and 0.05 g of p-toluenesulfonic acid, mix them, add them to 20 g of toluene, heat and reflux at 120°C for 16 h, add 5 mL of 1 mol / L sodium hydroxide solution to terminate the reaction, and obtain a crude dendritic polyol. The crude product is recrystallized from ethyl acetate, filtered, and dried in a drying oven at 55°C for 9 h to obtain a dendritic polyol.

[0067] Step S4, accurately weigh 12 g of terephthalic acid and 5 g of dendritic polyol, dissolve them in 30 g of N, N'-dimethylformamide, add 0.4 g of tetrabutyl titanate, react in a reactor at 180°C for 9 h, after the reaction is completed, dissolve all the crude dendritic polyester in chloroform, filter out the insoluble matter, filter, wash, and dry in a drying oven at 70°C for 8 h to obtain the dendritic polyester.

[0068] Step S5, accurately weigh 1 g of dendritic polyester and dissolve it in 35 g of N, N'-dimethylformamide, add 0.02 g of phosphorus oxychloride, react at 3°C ​​for 9 h, then add 15 g of aniline and 0.1 g of azobisisobutyronitrile, react at 85°C for 9 h to obtain a crude dendritic conductive polyester, wash with deionized water, and dry at 75°C for 11 h to obtain a dendritic conductive polyester, such as Figure 2 shown.

[0069] Step S6, adding 10 g of dendritic conductive polyester to a twin-screw extruder, melting at 280°C at a speed of 80 rpm, filtering impurities and unmelted particles through a 300-mesh filter, and extruding through a die to obtain a thick film with a thickness of 1 to 2 mm; the thick film enters a longitudinal heating and stretching unit at a temperature of 100°C to stretch the film to 4 times its original length; then, the film enters a transverse heating and stretching unit at a temperature of 120°C to stretch the film to 4 times its original width, and the obtained film is heat-set at 220°C for 12 s, and sent to a cooling roller at 40°C for cooling and solidification to obtain a dendritic conductive polyester film 2.

[0070] Step S7, accurately weigh 5 g of dioctadecyl dimethyl ammonium chloride, dissolve it in 100 g of anhydrous ethanol, use a coating machine to apply the first antistatic agent coating 1 and the second antistatic agent coating 3 on both sides of the dendritic conductive polyester film 2, and dry it in a hot air drying oven at 60° C. with a hot air flow rate of 3 m / s for 7 min to obtain an antistatic polyester film layer, such as Figure 3 shown.

[0071] Example 3 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer comprises the following steps: Step S1, accurately weigh 5 g of pentaerythritol and dissolve it in 50 g of N, N'-dimethylformamide, add 14 g of benzyl chloride and 18.5 g of potassium carbonate in sequence, and react at 60°C for 4 h to obtain a crude benzyl-substituted pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the mixture is placed in a drying oven at 60°C for 12 h to obtain a benzyl-substituted pentaerythritol.

[0072] Step S2: accurately weigh 27.5 g of acetyl chloride, dilute with 45 g of tetrahydrofuran to obtain solution A, accurately weigh 5 g of benzyl-substituted pentaerythritol, dissolve with 25 g of tetrahydrofuran to obtain solution B, dropwise add all of solution A to solution B under ice bath conditions, add 10 mL of 2 mol / L hydrochloric acid solution, react at 40°C for 7 h, and obtain a crude functionalized pentaerythritol product. The crude product is extracted with ethyl acetate, the ethyl acetate layer is collected, the ethyl acetate is removed by rotary evaporation, and the product is placed in a drying oven at 80°C for 8 h to obtain a crude functionalized pentaerythritol product.

[0073] Step S3, accurately weigh 5 g of functionalized pentaerythritol, 4 g of glycerol, and 0.05 g of p-toluenesulfonic acid, mix them, add them to 20 g of toluene, heat and reflux at 100°C for 12 h, add 5 mL of 1 mol / L sodium hydroxide solution to terminate the reaction, and obtain a crude dendritic polyol product. The crude product is recrystallized from ethyl acetate, filtered, and dried in a drying oven at 60°C for 8 h to obtain a dendritic polyol.

[0074] Step S4, accurately weigh 12.5 g of terephthalic acid and 5 g of dendritic polyol, dissolve them in 30 g of N, N'-dimethylformamide, add 0.6 g of tetrabutyl titanate, react in a reactor at 150°C for 8 h, after the reaction is completed, dissolve all the crude dendritic polyester in chloroform, filter out the insoluble matter, filter, wash, and dry in a drying oven at 80°C for 7 h to obtain the dendritic polyester.

[0075] Step S5, accurately weigh 1 g of dendritic polyester and dissolve it in 40 g of N, N'-dimethylformamide, add 0.03 g of phosphorus oxychloride, react at 5°C for 10 h, continue to add 20 g of aniline and 0.1 g of azobisisobutyronitrile, react at 100°C for 8 h to obtain a crude dendritic conductive polyester product, wash with deionized water, and dry at 80°C for 10 h to obtain a dendritic conductive polyester, such as Figure 2 shown.

[0076] Step S6, add 10 g of dendritic conductive polyester to a twin-screw extruder, heat and melt at 290°C, filter impurities and unmelted particles through a 300-mesh filter, and extrude through a die to obtain a thick film with a thickness of 1 to 2 mm. The thick film enters a longitudinal heating stretching unit at a temperature of 120°C to stretch the film to 5 times its original length; then, the film enters a transverse heating stretching unit at a temperature of 150°C to stretch the film to 5 times its original width. The obtained film is heat-set at 250°C for 10 seconds, and sent to a cooling roller at 50°C for cooling and solidification to obtain a dendritic conductive polyester film 2.

[0077] Step S7, accurately weigh 5 g of didecyldimethylammonium chloride, dissolve it in 100 g of anhydrous ethanol, use a coating machine to apply the first antistatic agent coating 1 and the second antistatic agent coating 3 on both sides of the dendritic conductive polyester film 2, and dry it in a hot air drying oven at 70° C. with a hot air flow rate of 5 m / s for 5 min to obtain an antistatic polyester film layer, such as Figure 3 shown.

[0078] Comparative Example 1 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer is provided, which is different from Example 3 in that in step (7), no antistatic agent is coated on both sides of the dendritic conductive polyester film.

[0079] Comparative Example 2 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer is provided, which is different from Example 3 in that glycerol is not added in step (3).

[0080] Comparative Example 3 like Figure 1 As shown, a method for preparing an antistatic structure polyester film layer is shown, which is different from Example 3 in that pentaerythritol is not added.

[0081] Comparative Example 4 like Figure 1 As shown, a method for preparing an antistatic structured polyester film layer is provided, which is different from Example 3 in that aniline is not added in step (5).

[0082] Performance Testing: The haze and light transmittance (GB / T 2410), tensile strength and breaking strength (ASTM D-882) of the antistatic polyester film layers prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested.

[0083] Testing the surface resistance of the antistatic polyester film layers prepared in Examples 1 to 3 and Comparative Examples 1 to 4: The antistatic polyester film layers prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were cut into a size of 10*10 mm, respectively, and the surface resistance of the film layers was tested on a high resistance meter (model: SME-8360).

[0084] Table 1 Surface resistance, optical and mechanical properties of antistatic polyester film layer

[0085] According to the data in Table 1, the surface resistance of the polyester film layer prepared in Examples 1 to 3 is lower than that of the film layer prepared in Comparative Examples 1 to 4. The low surface resistance means good antistatic performance. When the resistance of the material surface is low, the charge is easier to flow, so that static electricity can be discharged to the outside through the material surface, effectively preventing static electricity from being retained on the material surface. Experiments have shown that the polyester film layer prepared in Examples 1 to 3 has good antistatic performance. The polyester film layer prepared in Comparative Example 1 is not coated with an antistatic agent on both sides, and the antistatic effect is weakened. The polyester film layer prepared in Comparative Example 4 is not grafted with aniline, which is a key monomer for synthesizing conductive polymers. This proves that the dendritic conductive polyester film layer works synergistically with the upper and lower antistatic agent coatings to produce a better antistatic effect.

[0086] The optical performance test results show that the sandwich structure does not affect the light transmittance and haze of the polyester film layer. The light transmittance of the polyester film layer prepared in Examples 1 to 3 and Comparative Examples 1 to 4 is all above 85%, and the haze is all below 3%, which meets the requirements of the light transmittance of the polyester film layer ≥ 85% and the haze ≤ 3% specified in the GB / T 16958 national standard document.

[0087] The mechanical property test results show that the tensile strength of the polyester film layer prepared in Examples 1 to 3 is significantly higher than that of the polyester film layer prepared in Comparative Examples 2 to 4. The polyester film layer prepared in Comparative Example 2 does not add glycerol, and the polyester film layer prepared in Comparative Example 3 does not add pentaerythritol. Glycerol and pentaerythritol are polyhydroxy structures, which are the key to obtaining dendritic polyester. The polyesters prepared in Comparative Examples 2 and 3 have a lower degree of branching and a lower crosslinking density, and the tensile strength and elongation at break of the obtained polyester film layer are also reduced accordingly.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polyester film layer with an antistatic structure, characterized in that: The invention comprises a dendritic conductive polyester film (2), wherein the upper layer of the dendritic conductive polyester film (2) is provided with a first antistatic agent coating (1), and the lower layer of the dendritic conductive polyester film (2) is provided with a second antistatic agent coating (3); the dendritic conductive polyester film (2) is obtained by polymerizing pentaerythritol, glycerol, terephthalic acid and aniline, and the first antistatic agent coating (1) and the second antistatic agent coating (3) are obtained by mixing a quaternary ammonium salt antistatic agent and anhydrous ethanol; the structural formula of the dendritic conductive polyester in the dendritic conductive polyester film (2) is as follows: ； Wherein, in the structure, n is an integer between 1 and 10, and m is an integer between 1 and 10.

2. The method for preparing a polyester film layer with an antistatic structure according to claim 1, characterized in that: include: Step S1, dissolving pentaerythritol in a first solvent, adding potassium carbonate and benzyl chloride, reacting to obtain a crude benzyl-substituted pentaerythritol product, and extracting and drying to obtain the benzyl-substituted pentaerythritol; Step S2, diluting acetyl chloride with a second solvent to obtain a solution A, dissolving benzyl-substituted pentaerythritol with the second solvent to obtain a solution B, mixing solution A and solution B under ice bath conditions, adding acid to catalyze, reacting to obtain a crude functionalized pentaerythritol product, and extracting and drying to obtain a functionalized pentaerythritol; Step S3, adding functionalized pentaerythritol, glycerol and p-toluenesulfonic acid to a third solvent, heating to reflux, adding a base to terminate the reaction, obtaining a crude dendritic polyol product, and performing a first recrystallization and drying to obtain a dendritic polyol; Step S4, dissolving terephthalic acid and dendritic polyol in a first solvent, adding a catalyst, reacting in a reactor to obtain a dendritic polyester crude product, and performing a second recrystallization and drying to obtain a dendritic polyester; Step S5, adding the dendritic polyester to the first solvent to dissolve, adding phosphorus oxychloride, performing a first reaction, adding aniline and an initiator, performing a second reaction to obtain a crude dendritic conductive polyester product, and washing and drying to obtain the dendritic conductive polyester; Step S6, the dendritic conductive polyester is added to a twin-screw extruder, filtered through a filter screen, and extruded through a die head to form a thick film, and the thick film enters a longitudinal heating and stretching unit and a transverse heating and stretching unit in sequence to obtain a film that is heat-set and cooled to obtain a dendritic conductive polyester film (2); Step S7: dissolving a quaternary ammonium salt antistatic agent in anhydrous ethanol, using a coating machine to coat a first antistatic agent coating (1) and a second antistatic agent coating (3) on both sides of the dendritic conductive polyester film (2), and drying with hot air to obtain an antistatic polyester film layer.

3. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: The first solvent is any one or more of N, N'-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; the second solvent is any one or more of tetrahydrofuran, dichloromethane, methanol, and acetonitrile; the third solvent is any one or more of benzene, toluene, xylene, and acetone; the washing solvent is deionized water; and the extraction solvent is ethyl acetate.

4. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In the step S1, the reaction temperature is 40-60°C, and the reaction time is 4-6 h; the drying temperature is 40-60°C, and the drying time is 12-20 h; the mass ratio of pentaerythritol, benzyl chloride, potassium carbonate and the first solvent is 1: (2-2.8): (2.3-3.7): (20-30).

5. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In the step S2, the acid is any one or more of hydrochloric acid, sulfuric acid, formic acid, and acetic acid, with a concentration of 2 mol / L and an amount of 5 to 10 mL; the reaction temperature is 25 to 40° C., and the reaction time is 7 to 8 h; the drying temperature is 50 to 80° C., and the drying time is 8 to 10 h; the mass ratio of acetyl chloride to the second solvent is 1:(1.4 to 1.7); the mass ratio of benzyl-substituted pentaerythritol to the second solvent is 1:(4 to 6).

6. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In the step S3, the heating reflux temperature is 100-150° C., and the heating reflux time is 12-20 h. In the step S3, the drying temperature is 50-60° C., and the drying time is 8-10 h. The base is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate, with a concentration of 0.5-1.2 mol / L and an amount of 3-5 mL. The mass ratio of the functionalized pentaerythritol, glycerol, p-toluenesulfonic acid, and the third solvent is 1: (0.7-0.8): (0.008-0.01): (3-6); and the solvent for the first recrystallization is ethyl acetate.

7. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In the step S4, the catalyst is any one or more of tetrabutyl titanate, stannous octoate, and butyltin laurate; the reaction temperature in the reactor is 150-200° C., and the reaction time is 8-10 h; the drying temperature is 60-80° C., and the drying time is 7-8 h; the mass ratio of the dendritic polyol, terephthalic acid, catalyst, and the first solvent is 1: (2.3-2.5): (0.05-0.12): (5-6); and the solvent for the second recrystallization is chloroform.

8. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In the step S5, the initiator is any one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate; the temperature of the first reaction is 0-5°C, and the time of the first reaction is 8-10 h; the temperature of the second reaction is 70-100°C, and the time of the second reaction is 8-10 h; the temperature of the drying is 70-80°C, and the time of the drying is 10-12 h; the mass ratio of the dendritic polyester, aniline, initiator, phosphorus oxychloride and the first solvent is 1: (10-20): (0.05-0.1): (0.01-0.03): (30-40).

9. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In step S6, the preset temperature of the twin-screw extruder is 260-290°C, and the preset screw speed is 60-100 rpm; the mesh size of the filter is 200-300 mesh; the thickness of the thick film is 1-2 mm; the heating temperature of the longitudinal heating and stretching unit is 80-120°C, and the stretching ratio is 3-5 times; the heating temperature of the transverse heating and stretching unit is 100-150°C, and the stretching ratio is 3-5 times; the heat setting temperature is 200-250°C, and the time is 10-15 s; the cooling temperature is 30-50°C.

10. The method for preparing a polyester film layer with an antistatic structure according to claim 2, characterized in that: In step S7, the antistatic agent is a quaternary ammonium salt antistatic agent, including any one or more of didodecyl dimethyl ammonium chloride, didecyl dimethyl ammonium chloride, and didecyl dimethyl ammonium chloride; the mass ratio of the antistatic agent to anhydrous ethanol is (1-2):20; the preset speed of the coating roller of the coating machine is 3-6 m / min, and the gap between the scraper and the coating roller is 0.3-0.6 mm; the drying temperature of the hot air drying is 50-70°C, the hot air flow rate is 1-5 m / s, and the drying time is 5-10 min.

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