A toughened high-impact deep-drawing biaxially oriented polyamide film and its preparation method

Abstract

The present invention relates to the field of thin film materials, and particularly to a toughened high-impact deep-drawing biaxially oriented polyamide film and a preparation method thereof. The film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer, and a lower surface layer from top to bottom. The upper surface layer includes an anti-sticking masterbatch, poly(ω-aminoundecanoyl), and poly(laurolactam); the intermediate layer includes poly(laurolactam), a nylon copolymer, 1 to 15 parts of N,N-dimethyl-p-toluenesulfonamide, and polyamide 6; the lower surface layer includes an anti-sticking masterbatch, poly(ω-aminoundecanoyl), and poly(laurolactam). The film prepared by the present invention realizes the expected functions of the film through reasonable formulation design, film layer structure design, and specific preparation methods, thereby providing a biaxially oriented polyamide film with excellent comprehensive performance, easy processing, good deep-drawing performance, and good toughness, which is widely used in different packaging fields and has good market application prospects.

Description

Technical Field

[0001] The present invention relates to the field of thin film packaging, and particularly to a toughened high draw - depth biaxially oriented polyamide film and a preparation method thereof. Background Art

[0002] The biaxially oriented polyamide film, also known as biaxially oriented nylon film, i.e., BOPA, has excellent mechanical properties, gas barrier properties, electrical insulation properties, optical properties. At the same time, it is easy to print, oil - resistant, chemical - solvent - resistant, and has a wide temperature range of use. It is applied to various different fields such as food packaging, daily necessities packaging, electronic product packaging, and pharmaceutical product packaging, and occupies a crucial position in the packaging field.

[0003] However, under low - temperature conditions, ordinary nylon 6 materials are insufficient in toughness. For nylon used in frozen food packaging (especially for vacuum - packed foods with sharp corners), bag - breaking phenomena are likely to occur, causing the packaged products to deteriorate and the packaging bags to lose their quality - preservation function.

[0004] Similarly, in the pharmaceutical blister packaging and lithium - ion battery industries, in order to protect the aluminum foil layer in the multi - layer composite structure, the product needs to have a certain draw - depth forming performance. Therefore, improving the toughness of the biaxially oriented polyamide film has become an urgent need.

[0005] In the modification industry, the common method to improve the toughness of products is achieved by adding polyolefin elastomers and rubber - like elastomers. However, it often has little effect on very thin film products. Since the film is extremely thin, and polyolefin elastomers and rubber - like elastomers are non - polar materials, even after grafting treatment, their compatibility with the polyamide film is still greatly lacking. Therefore, even when grafted polyolefin elastomers and rubber - like elastomers are added, due to poor compatibility with the nylon system, not only is the toughening effect not obvious, but the tensile properties will also decrease sharply. Further, the addition of polyolefin elastomers and rubber - like elastomers will also have a certain impact on the barrier properties of the film, greatly reducing the shelf life of the packaging products.

[0006] Therefore, existing BOPA films often have difficulty in simultaneously considering compatibility, barrier properties, draw - depth formability, and toughness, which greatly limits the application of BOPA films in the lithium - ion battery industry, pharmaceutical blister packaging industry, and frozen food packaging industry.

[0007] Therefore, how to obtain a toughened high draw - depth biaxially oriented polyamide film has become an urgent problem to be solved currently. Summary of the Invention

[0008] To solve the problems mentioned in the background art, the present invention provides a toughened high impact deep drawing biaxially oriented polyamide film, which consists of a three-layer structure, namely an upper surface layer, an intermediate layer and a lower surface layer from top to bottom. By mass fraction, the intermediate layer includes 1 to 30 parts of polylaurolactam, 5 to 20 parts of nylon copolymer, 1 to 15 parts of N,N-dimethyl-p-toluenesulfonamide, and 35 to 93 parts of polyamide 6;

[0009] Among them, the nylon copolymer is a nylon copolymer synthesized by the polycondensation reaction of the terminal group of block polyamide and the reactive end group of block polyalkylene ether polyol;

[0010] The upper surface layer includes 1 to 8 parts of anti-sticking masterbatch, 1 to 50 parts of poly(ω-aminoundecanoyl), and 42 to 98 parts of polylaurolactam; the lower surface layer includes 1 to 8 parts of anti-sticking masterbatch, 1 to 50 parts of poly(ω-aminoundecanoyl), and 42 to 98 parts of polylaurolactam.

[0011] Further, the block polyamide includes a first block polyamide and a second block polyamide;

[0012] The first block polyamide is prepared from caprolactam, pure water and benzoic acid according to a mass ratio of (70 to 96.5):(3 to 20):(0.5 to 10);

[0013] The second block polyamide is prepared from laurolactam, pure water and adipic acid according to a mass ratio of (72 to 97.5):(2 to 20):(0.5 to 8).

[0014] Further, the block polyalkylene ether polyol is polyhexamethylene ether glycol.

[0015] Further, the anti-sticking masterbatch, by mass fraction, includes 1 to 5 parts of lubricant, 2 to 15 parts of antiblocking agent, and 80 to 97 parts of poly(ω-aminoundecanoyl). Among them, the anti-sticking masterbatch is obtained by melt extrusion, strand drawing, cooling, pelletizing and drying through a twin-screw extruder at a temperature of 230 to 270 °C.

[0016] Further, the lubricant is selected from one or a combination of several of PE wax, oleic acid amide, erucic acid amide, ethylene bisstearamide; the antiblocking agent is selected from one or a combination of several of calcium carbonate, kaolin, diatomite, talc powder, silica.

[0017] Further, the thickness of the toughened high impact deep drawing biaxially oriented polyamide film is 10 to 30 μm; among them, the thickness of the upper surface layer and the lower surface layer is 1 to 4 μm; the thickness of the intermediate layer is 2 to 28 μm.

[0018] The present invention also provides a method for preparing a toughened high-impact deep-drawing biaxially stretched polyamide film as described above, comprising the following steps:

[0019] Dry all raw materials, and control the moisture content of the raw materials to be below 800 ppm;

[0020] Mix the raw materials of the upper surface layer, the middle layer and the lower surface layer respectively according to the formula ratio, and then melt and plasticize and extrude them through their respective extruders at a temperature of 230-290 °C, and flow out through a coat hanger die head;

[0021] Use a low-pressure air knife to attach the melt to a cold drum to form a thick sheet, wherein the thickness of the thick sheet is 100-350 μm, and the temperature of the cold drum is 6-30 °C;

[0022] Preheat the thick sheet, perform longitudinal stretching at a temperature of 45-65 °C, and then perform shaping and cooling. The stretching ratio of the longitudinal stretching is 2.5-3.5 times;

[0023] Feed the longitudinally stretched film into a transverse stretching machine, with a preheating temperature of 60-85 °C, a stretching temperature of 70-150 °C, and a stretching ratio of 3.0-4.5 times;

[0024] Perform heat setting on the stretched film, wherein the setting temperature is 190-220 °C and the setting time is 1-50 s. Then, the film is cooled and corona post-treated, and the corona treatment power is 6-15 Wmin / m 2 , and wind it up;

[0025] Slit the wound toughened high-impact deep-drawing biaxially stretched polyamide film as required to obtain the described toughened high-impact deep-drawing biaxially stretched polyamide film.

[0026] Furthermore, the preparation method of the nylon copolymer is as follows:

[0027] Add caprolactam, pure water and benzoic acid into a high-pressure reaction kettle, evacuate for 10-120 minutes, introduce nitrogen for 5-40 minutes, and circulate 3-10 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.1-1.5 MPa;

[0028] Heat up the high-pressure reaction kettle to 220-295 °C, and at the same time start stirring, control the stirring speed at 30-150 r / min, and carry out heat preservation and pressure maintenance reaction for 2-20 hours under this condition. Release the gas to reduce the pressure to normal pressure, and at the same time lower the temperature to 30-100 °C to obtain the first block polyamide prepolymer A;

[0029] Add laurolactam, purified water and adipic acid into a high-pressure reactor, evacuate for 10 - 100 minutes, introduce nitrogen for 5 - 25 minutes, and circulate 3 - 8 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.1 - 1.0 MPa;

[0030] Heat the high-pressure reactor to 180 - 280 °C, while starting stirring, control the stirring speed at 20 - 120 r / min, and carry out heat preservation and pressure maintenance reaction for 2 - 12 hours under this condition, release the gas to reduce the pressure to atmospheric pressure, and at the same time lower the temperature to 20 - 80 °C to obtain the second block polyamide prepolymer B;

[0031] While flushing with nitrogen, add the first block polyamide prepolymer A, the second block polyamide prepolymer B and the block polyalkylene ether polyol into the high-pressure reactor, evacuate for 10 - 30 minutes, introduce nitrogen for 5 - 30 minutes, and circulate 3 - 9 times;

[0032] Raise the temperature of the high-pressure reactor to 220 - 260 °C, and stir the mixture under nitrogen to make it react for 1 - 6 hours, with the stirring speed of 20 - 60 r / min. Then add the catalyst and continue to react for 1 - 5 hours, and then let the system be under reduced pressure (<10 mbar) for 0 - 3 hours to discharge the material;

[0033] Pass the material through strand casting and pelletizing, and dry it at 80 - 120 °C to obtain the required nylon copolymer.

[0034] Furthermore, the mass ratio of the first block prepolymer A, the second block prepolymer B, the block polyalkylene ether polyol and the catalyst is (3 - 64.9):(30 - 55):(5 - 40):(0.1 - 2).

[0035] Furthermore, the catalyst is tetrabutyl titanate.

[0036] The toughened high-impact deep-drawing biaxially oriented polyamide film provided by the embodiments of the present invention has the following beneficial effects:

[0037] 1. In the nylon copolymer, the block polyamide serves as the hard segment, and the block polyalkylene ether polyol polymer serves as the soft segment. The soft segment has the elasticity of rubber, while the hydrogen bonds and crystalline microdomains formed by the block polyamide hard segments can achieve physical crosslinking, enabling it to be melt-processed at a certain temperature and exhibiting elasticity below the melting temperature.

[0038] 2. There are non-polar methylene groups in polylaurolactam and poly(ω-aminoundecanoyl), and the quantity is large, which makes the polymer molecular chain have greater flexibility and good toughness.

[0039] 3. The biggest drawback of polyamide products is their high water absorption, making it difficult to ensure dimensional stability. However, in the technical solution of the present invention, due to the increase in methylene molecules in polylaurolactam and poly(ω-aminoundecanoyl), the influence of hydrophilic groups is greatly reduced. Therefore, polylaurolactam and poly(ω-aminoundecanoyl) have the lowest water absorption rate among polyamide products, thus reducing the changes in the properties and dimensions of the products caused by water absorption. After water absorption, the tensile strength of polylaurolactam and poly(ω-aminoundecanoyl) decreases very little, while that of nylon 66 and nylon 6 in the prior art changes significantly.

[0040] 4. The chemical structure of nylon copolymers is quite related to that of polyamide 6, but the intermolecular hydrogen bond interaction is weaker than that of polyamide 6. At the same time, the crystallization rate, melting point, crystallization temperature, etc. of nylon copolymers are also lower than those of polyamide 6, and they have better toughness and processability.

[0041] 5. Since both N,N-dimethyl-p-toluenesulfonamide and polyamide contain -NH2, they have good compatibility. A small amount of plasticizer can significantly improve the impact strength of the film without much loss of tensile strength, effectively improving the comprehensive performance of the film.

[0042] 6. Polylaurolactam and poly(ω-aminoundecanoyl) themselves have outstanding barrier properties, which can ensure that the film has very excellent barrier properties.

[0043] 7. For the film prepared by the present invention, due to the low moisture absorption performance of the two surface materials, the design of the two surfaces can significantly reduce the moisture absorption performance of the film, while protecting the moisture absorption of the middle layer of polyamide 6. Through this design, the cost of the film can also be reduced.

[0044] 8. In the examples of the present invention, nylon copolymers are used to toughen polyamide films. Nylon copolymers have excellent compatibility with the nylon system, avoiding the problem of poor toughening effect of the film caused by dispersion or agglomeration between different components. Moreover, nylon copolymers themselves have the advantages of high temperature resistance, wear resistance, good dimensional stability, anti-creep stability, low moisture absorption rate, good softness, and high elastic recovery rate. In particular, in a low-temperature environment of -40.0 to 0 °C, the impact strength and flexibility remain unchanged, showing excellent low-temperature toughening effect. Under relatively low stress, nylon copolymers have better tensile stress compared with polymer products of the same hardness, so the thickness of the product can be reduced. They have good compatibility, high barrier properties, good deep drawing formability and toughness, and are especially suitable for toughening and modification of ultra-thin polyamide film products. They can be widely used in different packaging fields and have good market application prospects.

[0045] Other features and beneficial effects of the present invention will be described in the subsequent specification, and some of them will be obvious from the specification or understood by implementing the present invention. Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0047] Figure 1 It is a structural diagram of a toughened high-impact deep-drawing biaxially oriented polyamide film provided by the present invention.

[0048] Reference Signs:

[0049] 10 Lower surface layer 20 Intermediate layer 30 Upper surface layer Detailed Embodiments

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention; the technical features designed in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0051] In the description of the present invention, it should be understood that the terms "center", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. Additionally, the term "comprising" and any variations thereof mean "including at least".

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0053] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0054] The specific implementation manners of the present invention are as follows:

[0055] Embodiment 1

[0056] A toughened high-impact deep-drawing biaxially oriented polyamide film, the toughened high-impact deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which are, from top to bottom, the upper surface layer, the middle layer, and the lower surface layer. By mass, the upper surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam lauryllactam. The middle layer includes 20 parts of polycaprolactam lauryllactam, 12 parts of a nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 58 parts of polyamide 6. The lower surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam lauryllactam.

[0057] Among them, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of the first block polyamide and the second block polyamide and the reactive end groups of the block polyalkylene ether polyol; the polyalkylene ether polyol is polyhexamethylene ether glycol.

[0058] Among them, the anti-sticking masterbatch, by mass, includes 2 parts of a lubricant, 10 parts of an antiblocking agent, and 88 parts of poly(ω-aminoundecanoyl), and is obtained by melt-extruding, strand-drawing, cooling, pelletizing, and drying through a twin-screw extruder at a temperature of 230°C. Among them, the lubricant is selected from ethylene bisstearamide, and the antiblocking agent is selected from silicon dioxide.

[0059] Among them, the preparation method of the nylon copolymer is as follows:

[0060] Step 1: Add caprolactam, pure water, and benzoic acid into a high-pressure reactor in a mass ratio of 87:10:3. Vacuumize for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection. Control the pressure in the high-pressure reactor to be maintained at 0.9 MPa.

[0061] Step 2: Heat the high-pressure reactor to 250 °C. Meanwhile, start stirring and control the stirring speed at 80 r / min. Keep the temperature and pressure constant and react for 10 hours. Release the gas to reduce the pressure to atmospheric pressure, and at the same time, lower the temperature to 60 °C to obtain the first block polyamide prepolymer A.

[0062] Step 3: Add laurolactam, pure water, and adipic acid into a high-pressure reactor in a mass ratio of 85:13:2. Vacuumize for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection. Control the pressure in the high-pressure reactor to be maintained at 0.6 MPa.

[0063] Step 4: Heat the high-pressure reactor to 230 °C. Meanwhile, start stirring and control the stirring speed at 60 r / min. Keep the temperature and pressure constant and react for 8 hours. Release the gas to reduce the pressure to atmospheric pressure, and at the same time, lower the temperature to 50 °C to obtain the second block polyamide prepolymer B.

[0064] Step 5: While flushing with nitrogen, add the first block polyamide prepolymer A, the second block polyamide prepolymer B, and the block polyalkylene ether polyol into the high-pressure reactor. Vacuumize for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times. Among them, the mass ratio of the first block polyamide prepolymer A, the second block polyamide prepolymer B, the block polyalkylene ether polyol, and the catalyst is 40:29.8:30:0.2.

[0065] Step 6: Raise the temperature of the high-pressure reactor to 240 °C and stir the mixture under nitrogen to react for 4 hours at a stirring speed of 30 r / min. Then add tetrabutyl titanate catalyst and continue to react for 2 hours. Then keep the system under reduced pressure (<10 mbar) for 1.5 hours and discharge the material.

[0066] Step 7: Pass the material through casting and pelletizing, and dry it at 90 °C to obtain the required nylon copolymer.

[0067] The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film in this example includes the following steps:

[0068] S1: Dry all the raw materials and control the moisture content of the raw materials to be below 800 ppm.

[0069] S2: Mix the raw materials of the upper surface layer, the middle layer and the lower surface layer respectively according to the formula ratio, then melt and plasticize and extrude them through their respective extruders at a temperature of 250°C, and flow out through a coat hanger die head;

[0070] S3: Use a low-pressure air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 260 μm and the temperature of the cold drum is 10°C;

[0071] S4: Preheat the thick sheet, perform longitudinal stretching at a temperature of 55°C, and then perform shaping and cooling. The stretching ratio of the longitudinal stretching is 2.8 times;

[0072] S5: Feed the longitudinally stretched film into a transverse stretching machine. The preheating temperature is 70°C, the stretching temperature is 100°C, and the stretching ratio is 3.5;

[0073] S6: Perform heat setting on the stretched film, where the setting temperature is 205°C and the setting time is 8 s. Then the film is cooled and corona post-treated, and the corona treatment power is 10 Wmin / m 2 , and wind it up;

[0074] S7: Slit the wound toughened high impact deep drawing biaxially oriented polyamide film as required, and finally obtain the said toughened high impact deep drawing biaxially oriented polyamide film.

[0075] The thickness of the toughened high impact deep drawing biaxially oriented polyamide film prepared in this example is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the middle layer is 21 μm.

[0076] Example 2

[0077] A toughened high impact deep drawing biaxially oriented polyamide film, the said toughened high impact deep drawing biaxially oriented polyamide film is composed of a three-layer structure, which are the upper surface layer, the middle layer and the lower surface layer from top to bottom. By mass, the upper surface layer includes 3 parts of anti-sticking masterbatch, 18 parts of poly(ω-aminoundecanoyl), and 79 parts of polycaprolactam lauryllactam. The middle layer includes 25 parts of polycaprolactam lauryllactam, 15 parts of nylon copolymer, 12 parts of N,N-dimethyl-p-toluenesulfonamide, and 48 parts of polyamide 6. The lower surface layer includes 3 parts of anti-sticking masterbatch, 18 parts of poly(ω-aminoundecanoyl), and 79 parts of polycaprolactam lauryllactam.

[0078] Among them, the nylon copolymer is a nylon copolymer synthesized by the polycondensation reaction of the end groups of the first block polyamide and the second block polyamide with the reactive end groups of the block polyalkylene ether polyol; the polyalkylene ether polyol is polyhexamethylene ether diol.

[0079] Among them, the anti-sticking masterbatch, by mass parts, includes 3 parts of lubricant, 9 parts of antiblocking agent, and 88 parts of poly(ω-aminoundecanoyl), which is obtained after melt extrusion, strand drawing, cooling, pelletizing, and drying at a temperature of 225°C. Among them, the lubricant is selected from ethylene bisstearamide, and the antiblocking agent is selected from silicon dioxide.

[0080] Among them, the preparation method of the nylon copolymer is as follows:

[0081] The first step: Caprolactam, pure water, and benzoic acid are added to a high-pressure reactor according to a mass ratio of 85:12:3. Vacuum is pumped for 40 minutes, nitrogen is introduced for 25 minutes, and the cycle is repeated 8 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 1 MPa.

[0082] The second step: The temperature of the high-pressure reactor is raised to 245°C, and at the same time, stirring is started, and the stirring speed is controlled at 90 r / min. Under this condition, heat preservation and pressure maintenance reaction are carried out for 12 hours, the pressure is released to normal pressure, and at the same time, the temperature is lowered to 70°C to obtain the first block polyamide prepolymer A.

[0083] The third step: Dodecanolactam, pure water, and adipic acid are added to a high-pressure reactor according to a mass ratio of 87:10:3. Vacuum is pumped for 30 minutes, nitrogen is introduced for 20 minutes, and the cycle is repeated 6 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 0.8 MPa.

[0084] The fourth step: The temperature of the high-pressure reactor is raised to 225°C, and at the same time, stirring is started, and the stirring speed is controlled at 80 r / min. Under this condition, heat preservation and pressure maintenance reaction are carried out for 10 hours, the pressure is released to normal pressure, and at the same time, the temperature is lowered to 60°C to obtain the second block polyamide prepolymer B.

[0085] The fifth step: While flushing with nitrogen, the first block polyamide prepolymer A, the second block polyamide prepolymer B, and the block polyalkylene ether polyol are added to the high-pressure reactor, and vacuum is pumped for 25 minutes, nitrogen is introduced for 20 minutes, and the cycle is repeated 6 times; among them, the mass ratio of the first block polyamide prepolymer A, the second block polyamide prepolymer B, the block polyalkylene ether polyol, and the catalyst is 38:29.7:32:0.3.

[0086] The sixth step: The temperature of the high-pressure reactor is raised to 235°C, and the mixture is stirred under nitrogen to react for 5 hours, and the stirring speed is 50 r / min. Then tetrabutyl titanate catalyst is added and the reaction is continued for 3 hours, and then the system is under reduced pressure (<10 mbar) for 2 hours to discharge the material.

[0087] The seventh step: The material is cast into strips and pelletized, and dried at 85°C to obtain the required nylon copolymer.

[0088] The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film in this embodiment includes the following steps:

[0089] S1: Dry all raw materials and control the moisture content of the raw materials below 800 ppm;

[0090] S2: Mix the raw materials of the upper surface layer, the middle layer and the lower surface layer respectively according to the formula ratio, then melt and plasticize and extrude through their respective extruders at a temperature of 245 °C, and flow out through a coat hanger die head;

[0091] S3: Use a low-pressure air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 265 μm and the temperature of the cold drum is 12 °C;

[0092] S4: Preheat the thick sheet, conduct longitudinal stretching at a temperature of 53 °C, and then conduct shaping and cooling. The stretching ratio of the longitudinal stretching is 2.9 times;

[0093] S5: Feed the longitudinally stretched film into a transverse stretching machine, with a preheating temperature of 75 °C, a stretching temperature of 105 °C, and a stretching ratio of 3.4;

[0094] S6: Conduct heat setting treatment on the stretched film, where the setting temperature is 206 °C and the setting time is 10 s. Then, the film is cooled and corona post-treated, and the corona treatment power is 9 Wmin / m 2 , and wind it up;

[0095] S7: Slit the wound toughened high-impact deep-drawing biaxially oriented polyamide film as required, and finally obtain the toughened high-impact deep-drawing biaxially oriented polyamide film, with the film thickness of 25 μm.

[0096] The thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film prepared in this embodiment is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 1.75 μm; the thickness of the middle layer is 21.5 μm.

[0097] Example 3

[0098] A toughened high-impact deep-drawing biaxially oriented polyamide film, the toughened high-impact deep-drawing biaxially oriented polyamide film is composed of a three-layer structure, which are the upper surface layer, the middle layer and the lower surface layer from top to bottom. By mass, the upper surface layer includes 4 parts of anti-sticking masterbatch, 16 parts of poly(ω-aminoundecanoyl), and 80 parts of polycaprolactam laurolactam. The middle layer includes 26 parts of polycaprolactam laurolactam, 18 parts of nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 46 parts of polyamide 6. The lower surface layer includes 4 parts of anti-sticking masterbatch, 16 parts of poly(ω-aminoundecanoyl), and 80 parts of polycaprolactam laurolactam.

[0099] Among them, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of the first block polyamide and the second block polyamide and the reactive end groups of the block polyalkylene ether polyol; the polyalkylene ether polyol is polyhexamethylene ether glycol.

[0100] Among them, the anti-sticking masterbatch, by mass, includes 4 parts of lubricant, 8 parts of antiblocking agent, and 88 parts of poly(ω-aminoundecanoyl), which is obtained by melt extrusion, strand drawing, cooling, pelletizing, and drying with a twin-screw extruder at a temperature of 225°C. Among them, the lubricant is selected from ethylene bisstearamide, and the antiblocking agent is selected from silicon dioxide.

[0101] Among them, the preparation method of the nylon copolymer is as follows:

[0102] First step: Caprolactam, pure water, and benzoic acid are added to a high-pressure reactor according to a mass ratio of 86:12:2; vacuum is pumped for 45 minutes, nitrogen is introduced for 30 minutes, and the cycle is repeated 6 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 0.8 MPa;

[0103] Second step: The high-pressure reactor is heated to 255°C, and at the same time, stirring is started, and the stirring speed is controlled at 100 r / min, and the reaction is carried out under isothermal and isobaric conditions for 15 hours, and the pressure is reduced to atmospheric pressure by releasing gas, and at the same time, the temperature is reduced to 75°C to obtain the first block polyamide prepolymer A;

[0104] Third step: Dodecanolactam, pure water, and adipic acid are added to a high-pressure reactor according to a mass ratio of 88:10:2; vacuum is pumped for 35 minutes, nitrogen is introduced for 20 minutes, and the cycle is repeated 5 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 0.8 MPa;

[0105] Fourth step: The high-pressure reactor is heated to 230°C, and at the same time, stirring is started, and the stirring speed is controlled at 70 r / min, and the reaction is carried out under isothermal and isobaric conditions for 9 hours, and the pressure is reduced to atmospheric pressure by releasing gas, and at the same time, the temperature is reduced to 55°C to obtain the second block polyamide prepolymer B;

[0106] Fifth step: While flushing with nitrogen, the first block polyamide prepolymer A, the second block polyamide prepolymer B, and the block polyalkylene ether polyol are added to the high-pressure reactor, and vacuum is pumped for 22 minutes, nitrogen is introduced for 25 minutes, and the cycle is repeated 5 times; among them, the mass ratio of the first block polyamide prepolymer A, the second block polyamide prepolymer B, the block polyalkylene ether polyol, and the catalyst is 32:32.8:35:0.2.

[0107] Step 6: Raise the temperature of the high-pressure reactor to 240 °C, stir the mixture under nitrogen for 4 hours at a stirring speed of 40 r / min. Then add tetrabutyl titanate catalyst and continue the reaction for 4 hours, and then discharge the system under reduced pressure (<10 mbar) for 2.5 hours.

[0108] Step 7: Granulate the material through casting and cutting, and dry it at 88 °C to obtain the required nylon copolymer.

[0109] The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film obtained in this example includes the following steps:

[0110] S1: Dry all raw materials and control the moisture content of the raw materials below 800 ppm;

[0111] S2: Mix the raw materials of the upper surface layer, the middle layer and the lower surface layer according to the formula ratio respectively, and then melt and plasticize and extrude them through their respective extruders at a temperature of 250 °C, and flow out through a coat-hanger die head;

[0112] S3: Adhere the melt to the cold drum by using a low-pressure air knife to form a thick sheet, where the thickness of the thick sheet is 265 μm and the temperature of the cold drum is 15 °C;

[0113] S4: Preheat the thick sheet, perform longitudinal stretching at a temperature of 52 °C, and then perform shaping and cooling. The stretching ratio of the longitudinal stretching is 3 times;

[0114] S5: Feed the longitudinally stretched film into a transverse stretching machine, with a preheating temperature of 78 °C, a stretching temperature of 110 °C, and a stretching ratio of 3.3;

[0115] S6: Perform heat setting on the stretched film, where the setting temperature is 208 °C and the setting time is 12 s, and then the film is cooled and corona post-treated. The corona treatment power is 9 Wmin / m 2 , and wind it up;

[0116] S7: Slit the wound toughened high-impact deep-drawing biaxially oriented polyamide film as required to finally obtain the toughened high-impact deep-drawing biaxially oriented polyamide film.

[0117] The thickness of the prepared toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2.5 μm; the thickness of the middle layer is 20 μm.

[0118] Comparative Example 1

[0119] This comparative example provides a toughened high deep-drawing biaxially oriented polyamide film. The toughened high deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer, and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide 6. The intermediate layer includes 100 parts of polyamide 6. The lower surface layer includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide 6.

[0120] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of a lubricant, 10 parts of an antiblocking agent, and 88 parts of polyamide 6.

[0121] The lubricant is selected from ethylene bisstearamide.

[0122] The antiblocking agent is selected from silicon dioxide.

[0123] The anti-sticking masterbatch is obtained by melt-extruding, strand-drawing, cooling, pelletizing, and drying through a twin-screw extruder at a temperature of 230°C.

[0124] Specifically, the thickness of the toughened high deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the intermediate layer is 21 μm.

[0125] The preparation method of the film in this comparative example is the same as that of Example 1.

[0126] Comparative Example 2

[0127] This comparative example provides a toughened high deep-drawing biaxially oriented polyamide film. The toughened high deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer, and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide 6. The intermediate layer includes 20 parts of polycaprolactam laurylamide, 12 parts of a nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 58 parts of polyamide 6. The lower surface layer includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide 6.

[0128] Specifically, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of a first block polyamide and a second block polyamide and the reactive end groups of a block polyalkylene ether polyol.

[0129] Specifically, the preparation method of the nylon copolymer is as follows:

[0130] First step: Add caprolactam, pure water, and benzoic acid into a high-pressure reaction kettle, evacuate for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.9 MPa;

[0131] Step 2: Heat the high-pressure reactor to 250 °C, and at the same time, start stirring with the stirring speed controlled at 80 r / min. Maintain the temperature and pressure for reaction for 10 hours under this condition, then release the gas to reduce the pressure to atmospheric pressure, and at the same time, lower the temperature to 60 °C to obtain prepolymer A;

[0132] Step 3: Add laurolactam, pure water, and adipic acid into the high-pressure reactor, evacuate for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.6 MPa;

[0133] Step 4: Heat the high-pressure reactor to 230 °C, and at the same time, start stirring with the stirring speed controlled at 60 r / min. Maintain the temperature and pressure for reaction for 8 hours under this condition, then release the gas to reduce the pressure to atmospheric pressure, and at the same time, lower the temperature to 50 °C to obtain prepolymer B;

[0134] Step 5: While flushing with nitrogen, add prepolymer A, prepolymer B, and block polyalkylene ether polyol into the high-pressure reactor, evacuate for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times.

[0135] Step 6: Raise the temperature of the high-pressure reactor to 240 °C, and stir the mixture under nitrogen for reaction for 4 hours with the stirring speed of 30 r / min. Then add the catalyst and continue the reaction for 2 hours, and then keep the system under reduced pressure (<10 mbar) for 1.5 hours to discharge the material.

[0136] Step 7: Pass the material through strand casting and pelletizing, and dry it at 90 °C to obtain the required nylon copolymer.

[0137] Specifically, the polyalkylene ether polyol is polyhexamethylene ether glycol.

[0138] Specifically, the mass ratio of caprolactam, pure water, and benzoic acid is 87:10:3, and the mass ratio of laurolactam, pure water, and adipic acid is 85:13:2.

[0139] Specifically, the mass ratio of prepolymer A, prepolymer B, block polyalkylene ether polyol, and catalyst is 40:29.8:30:0.2.

[0140] Specifically, the catalyst is tetrabutyl titanate.

[0141] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent, and 88 parts of polyamide 6.

[0142] The lubricant is selected from ethylene bisstearamide.

[0143] The antiblocking agent is selected from silicon dioxide.

[0144] The anti-sticking masterbatch is obtained by melting and extruding, strand drawing, cooling, pelletizing and drying through a twin-screw extruder at a temperature of 230°C.

[0145] Furthermore, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thicknesses of the upper surface layer and the lower surface layer are 2 μm; the thickness of the intermediate layer is 21 μm.

[0146] The present invention also provides a preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film, and its preparation method is the same as that of Example 1.

[0147] Comparative Example 3

[0148] This comparative example provides a toughened high-impact deep-drawing biaxially oriented polyamide film, and the described toughened high-impact deep-drawing biaxially oriented polyamide film is composed of a three-layer structure, which are the upper surface layer, the intermediate layer and the lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of polyamide 6, and 75 parts of polycaprolactam lauryl. The intermediate layer includes 20 parts of polycaprolactam lauryl, 12 parts of nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 58 parts of polyamide 6. The lower surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of polyamide 6, and 75 parts of polycaprolactam lauryl.

[0149] Specifically, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of the first block polyamide and the second block polyamide and the reactive end groups of the block polyalkylene ether polyol.

[0150] Specifically, the preparation method of the nylon copolymer is as follows:

[0151] The first step: Add caprolactam, pure water and benzoic acid into a high-pressure reaction kettle, evacuate for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.9 MPa;

[0152] The second step: Heat the high-pressure reaction kettle to 250°C, and at the same time start stirring, and control the stirring speed at 80 r / min, and carry out heat preservation and pressure maintenance reaction for 10 hours under this condition, release the gas to reduce the pressure to normal pressure, and at the same time lower the temperature to 60°C to obtain prepolymer A;

[0153] The third step: Add laurolactam, pure water and adipic acid into a high-pressure reaction kettle, evacuate for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.6 MPa;

[0154] Step 4: Heat the high-pressure reactor to 230 °C, and at the same time start stirring, with the stirring speed controlled at 60 r / min, and keep the temperature and pressure constant for reaction for 8 hours, then release the gas to reduce the pressure to atmospheric pressure, and at the same time reduce the temperature to 50 °C to obtain prepolymer B;

[0155] Step 5: While flushing with nitrogen, add prepolymer A, prepolymer B and block polyalkylene ether polyol into the high-pressure reactor, evacuate for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times.

[0156] Step 6: Raise the temperature of the high-pressure reactor to 240 °C, and stir the mixture under nitrogen for reaction for 4 hours, with the stirring speed being 30 r / min. Then add the catalyst and continue the reaction for 2 hours, and then keep the system under reduced pressure (<10 mbar) for 1.5 hours and discharge the material.

[0157] Step 7: Pass the material through casting, granulation, and drying at 90 °C to obtain the required nylon copolymer.

[0158] Specifically, the polyalkylene ether polyol is polyhexamethylene ether glycol.

[0159] Specifically, the mass ratio of caprolactam, pure water and benzoic acid is 87:10:3, and the mass ratio of laurolactam, pure water and adipic acid is 85:13:2.

[0160] Specifically, the mass ratio of prepolymer A, prepolymer B, block polyalkylene ether polyol and catalyst is 40:29.8:30:0.2.

[0161] Specifically, the catalyst is tetrabutyl titanate.

[0162] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent and 88 parts of poly(ω-aminoundecanoyl).

[0163] The lubricant is selected from ethylene bisstearamide.

[0164] The antiblocking agent is selected from silicon dioxide.

[0165] The anti-sticking masterbatch is obtained by melt extrusion, strand drawing, cooling, granulation and drying through a twin-screw extruder at a temperature of 230 °C.

[0166] Specifically, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the middle layer is 21 μm.

[0167] The preparation method of the film provided in this comparative example is the same as that of Example 1.

[0168] Comparative Example 4

[0169] This comparative example provides a toughened high deep-drawing biaxially oriented polyamide film. The toughened high deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer, and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polyamide 6. The intermediate layer includes 20 parts of polylaurolactam, 12 parts of a nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 58 parts of polyamide 6. The lower surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polyamide 6.

[0170] Specifically, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of a first block polyamide and a second block polyamide and the reactive end groups of a block polyalkylene ether polyol.

[0171] Specifically, the preparation method of the nylon copolymer is as follows:

[0172] First step: Add caprolactam, pure water, and benzoic acid into a high-pressure reactor, evacuate for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.9 MPa.

[0173] Second step: Heat the high-pressure reactor to 250 °C, and at the same time start stirring, control the stirring speed at 80 r / min, and carry out an isothermal and isobaric reaction for 10 hours under this condition, release the gas and reduce the pressure to atmospheric pressure, and at the same time lower the temperature to 60 °C to obtain a first block polyamide prepolymer A.

[0174] Third step: Add laurolactam, pure water, and adipic acid into a high-pressure reactor, evacuate for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.6 MPa.

[0175] Fourth step: Heat the high-pressure reactor to 230 °C, and at the same time start stirring, control the stirring speed at 60 r / min, and carry out an isothermal and isobaric reaction for 8 hours under this condition, release the gas and reduce the pressure to atmospheric pressure, and at the same time lower the temperature to 50 °C to obtain a second block polyamide prepolymer B.

[0176] Fifth step: While flushing with nitrogen, add prepolymer A, prepolymer B, and block polyalkylene ether polyol into the high-pressure reactor, evacuate for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times.

[0177] Step 6: Raise the temperature of the high-pressure reactor to 240 °C, and stir the mixture under nitrogen for 4 hours at a stirring speed of 30 r / min. Then add the catalyst and continue the reaction for 2 hours, and then discharge the material under reduced pressure (<10 mbar) for 1.5 hours.

[0178] Step 7: Granulate the material through belt casting and dry it at 90 °C to obtain the required nylon copolymer.

[0179] Specifically, the polyalkylene ether polyol is polyhexamethylene ether diol.

[0180] Specifically, the mass ratio of caprolactam, pure water and benzoic acid is 87:10:3, and the mass ratio of laurolactam, pure water and adipic acid is 85:13:2.

[0181] Specifically, the mass ratio of prepolymer A, prepolymer B, block polyalkylene ether polyol and catalyst is 40:29.8:30:0.2.

[0182] Specifically, the catalyst is tetrabutyl titanate.

[0183] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent and 88 parts of poly(ω-aminoundecanoyl).

[0184] The lubricant is selected from ethylene bisstearamide.

[0185] The antiblocking agent is selected from silicon dioxide.

[0186] The anti-sticking masterbatch is obtained by melt extrusion, strand drawing, cooling, granulation and drying through a twin-screw extruder at a temperature of 230 °C.

[0187] Specifically, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the intermediate layer is 21 μm.

[0188] This comparative example also provides a method for preparing a film, and its preparation method is the same as that of Example 1.

[0189] Comparative Example 5

[0190] This comparative example provides a toughened high impact deep drawing biaxially oriented polyamide film. The toughened high impact deep drawing biaxially oriented polyamide film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam lauryllactam. The intermediate layer includes 12 parts of nylon copolymer, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 78 parts of polyamide 6. The lower surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam lauryllactam.

[0191] Specifically, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction between the end groups of a first block polyamide and a second block polyamide and the reactive end groups of a block polyalkylene ether polyol.

[0192] Specifically, the preparation method of the nylon copolymer is as follows:

[0193] First step: Add caprolactam, pure water and benzoic acid into a high-pressure reactor, evacuate for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.9 MPa;

[0194] Second step: Heat the high-pressure reactor to 250 °C, start stirring at the same time, control the stirring speed at 80 r / min, and carry out heat preservation and pressure maintenance reaction for 10 hours under this condition, release the gas and reduce the pressure to normal pressure, and at the same time reduce the temperature to 60 °C to obtain a first block polyamide prepolymer A;

[0195] Third step: Add laurolactam, pure water and adipic acid into a high-pressure reactor, evacuate for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reactor to be maintained at 0.6 MPa;

[0196] Fourth step: Heat the high-pressure reactor to 230 °C, start stirring at the same time, control the stirring speed at 60 r / min, and carry out heat preservation and pressure maintenance reaction for 8 hours under this condition, release the gas and reduce the pressure to normal pressure, and at the same time reduce the temperature to 50 °C to obtain a second block polyamide prepolymer B;

[0197] Fifth step: While flushing with nitrogen, add prepolymer A, prepolymer B and block polyalkylene ether polyol into the high-pressure reactor, evacuate for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times.

[0198] Sixth step: Raise the temperature of the high-pressure reactor to 240 °C, and stir the mixture under nitrogen to make it react for 4 hours, with a stirring speed of 30 r / min. Then add a catalyst and continue to react for 2 hours, and then keep the system under reduced pressure (<10 mbar) for 1.5 hours and discharge the material.

[0199] Step 7: Granulate the material through casting and pelletizing, and dry it at 90 °C to obtain the required nylon copolymer.

[0200] Specifically, the polyalkylene ether polyol is polyhexamethylene ether diol.

[0201] Specifically, the mass ratio of caprolactam, purified water and benzoic acid is 87:10:3, and the mass ratio of laurolactam, purified water and adipic acid is 85:13:2.

[0202] Specifically, the mass ratio of prepolymer A, prepolymer B, block polyalkylene ether polyol and catalyst is 40:29.8:30:0.2.

[0203] Specifically, the catalyst is tetrabutyl titanate.

[0204] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent and 88 parts of poly(ω-aminoundecanoyl).

[0205] The lubricant is selected from ethylene bisstearamide.

[0206] The antiblocking agent is selected from silicon dioxide.

[0207] The anti-sticking masterbatch is obtained by melting extrusion, strand pelletizing, cooling, granulating and drying through a twin-screw extruder at a temperature of 230 °C.

[0208] Specifically, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the intermediate layer is 21 μm.

[0209] This comparative example provides a method for preparing a film, and its preparation method is the same as that of Example 1.

[0210] Comparative Example 6

[0211] This comparative example provides a toughened high-impact deep-drawing biaxially oriented polyamide film, and the described toughened high-impact deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which are, from top to bottom, an upper surface layer, an intermediate layer and a lower surface layer. By mass, the upper surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polylaurolactam. The intermediate layer includes 20 parts of polylaurolactam, 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 70 parts of polyamide 6. The lower surface layer includes 5 parts of anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polylaurolactam.

[0212] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent and 88 parts of poly(ω-aminoundecanoyl).

[0213] The lubricant is selected from ethylene bisstearamide.

[0214] The antiblocking agent is selected from silicon dioxide.

[0215] The antiblocking masterbatch is obtained by melt extrusion, strand drawing, cooling, pelletizing and drying through a twin-screw extruder at a temperature of 230 °C.

[0216] Specifically, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the intermediate layer is 21 μm.

[0217] This comparative example also provides a method for preparing a film, and its preparation method is the same as that of Example 1.

[0218] Comparative Example 7

[0219] This comparative example provides a toughened high-impact deep-drawing biaxially oriented polyamide film. The toughened high-impact deep-drawing biaxially oriented polyamide film consists of a three-layer structure, which is successively an upper surface layer, an intermediate layer and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of antiblocking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of poly(lauryl lactam). The intermediate layer includes 20 parts of poly(lauryl lactam), 12 parts of nylon copolymer, and 68 parts of polyamide 6. The lower surface layer includes 5 parts of antiblocking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of poly(lauryl lactam).

[0220] Specifically, the nylon copolymer is a nylon copolymer synthesized by a polycondensation reaction of the end groups of the first block polyamide and the second block polyamide with the reactive end groups of the block polyalkylene ether polyol.

[0221] Specifically, the preparation method of the nylon copolymer is as follows:

[0222] First step: Add caprolactam, pure water and benzoic acid into a high-pressure reaction kettle, evacuate for 30 minutes, introduce nitrogen for 20 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.9 MPa;

[0223] Second step: Heat the high-pressure reaction kettle to 250 °C, and at the same time start stirring, and control the stirring speed at 80 r / min, and carry out heat preservation and pressure maintenance reaction for 10 hours under this condition, release the gas to reduce the pressure to normal pressure, and at the same time lower the temperature to 60 °C to obtain prepolymer A;

[0224] Third step: Add laurolactam, pure water and adipic acid into a high-pressure reaction kettle, evacuate for 25 minutes, introduce nitrogen for 15 minutes, and circulate 5 times to ensure that each component is under nitrogen protection, and control the pressure in the high-pressure reaction kettle to be maintained at 0.6 MPa;

[0225] Step 4: Heat the high-pressure reactor to 230 °C, and at the same time start stirring, control the stirring speed at 60 r / min, and keep the temperature and pressure constant for 8 hours under this condition. Then release the gas and reduce the pressure to atmospheric pressure, and at the same time reduce the temperature to 50 °C to obtain prepolymer B;

[0226] Step 5: While flushing with nitrogen, add prepolymer A, prepolymer B and block polyalkylene ether polyol into the high-pressure reactor, evacuate for 20 minutes, introduce nitrogen for 15 minutes, and circulate 5 times.

[0227] Step 6: Raise the temperature of the high-pressure reactor to 240 °C, and stir the mixture under nitrogen for 4 hours, with a stirring speed of 30 r / min. Then add the catalyst and continue to react for 2 hours, and then discharge the system under reduced pressure (<10 mbar) for 1.5 hours.

[0228] Step 7: Granulate the material through casting and cutting, and dry it at 90 °C to obtain the required nylon copolymer.

[0229] Specifically, the polyalkylene ether polyol is polyhexamethylene ether diol.

[0230] Specifically, the mass ratio of caprolactam, pure water and benzoic acid is 87:10:3, and the mass ratio of laurolactam, pure water and adipic acid is 85:13:2.

[0231] Specifically, the mass ratio of prepolymer A, prepolymer B, block polyalkylene ether polyol and catalyst is 40:29.8:30:0.2.

[0232] Specifically, the catalyst is tetrabutyl titanate.

[0233] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of lubricant, 10 parts of antiblocking agent and 88 parts of poly(ω-aminoundecanoyl).

[0234] The lubricant is selected from ethylene bisstearamide.

[0235] The antiblocking agent is selected from silicon dioxide.

[0236] The anti-sticking masterbatch is obtained by melt extrusion, strand drawing, cooling, granulation and drying through a twin-screw extruder at a temperature of 230 °C.

[0237] Specifically, the thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the intermediate layer is 21 μm.

[0238] This comparative ethics also provides a method for preparing a film, and its preparation method is the same as that of Example 1.

[0239] Comparative Example 8

[0240] This comparative example provides a toughened high deep-drawing biaxially stretched polyamide film. The toughened high deep-drawing biaxially stretched polyamide film consists of a three-layer structure, which is successively an upper surface layer, a middle layer and a lower surface layer from top to bottom. By mass, the upper surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam laurolactam. The middle layer includes 20 parts of polycaprolactam laurolactam, 12 parts of POE-g-MAH (CMG5805-L of Jia Yirong Co., Ltd.), 10 parts of N,N-dimethyl-p-toluenesulfonamide, and 58 parts of polyamide 6. The lower surface layer includes 5 parts of an anti-sticking masterbatch, 20 parts of poly(ω-aminoundecanoyl), and 75 parts of polycaprolactam laurolactam.

[0241] Specifically, the anti-sticking masterbatch, by mass, includes 2 parts of a lubricant, 10 parts of an antiblocking agent, and 88 parts of poly(ω-aminoundecanoyl).

[0242] The lubricant is selected from ethylene bisstearamide.

[0243] The antiblocking agent is selected from silicon dioxide.

[0244] The anti-sticking masterbatch is obtained by melt extrusion, strand drawing, cooling, pelletizing and drying through a twin-screw extruder at a temperature of 230 °C.

[0245] Specifically, the thickness of the toughened high deep-drawing biaxially stretched polyamide film is 25 μm; among them, the thickness of the upper surface layer and the lower surface layer is 2 μm; the thickness of the middle layer is 21 μm.

[0246] This comparative example also provides a method for preparing a film, and its preparation method is the same as that of Example 1.

[0247] The present invention tests the relevant properties of the above-mentioned examples and comparative examples, and the specific result data are shown in the following table:

[0248] Table 1

[0249]

[0250] Note:

[0251] (1) Tensile strength performance test: The test is carried out according to the standard requirements of GB / T 1040.3 "Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets".

[0252] (2) Oxygen transmission rate performance test: The test is carried out in accordance with the requirements of ASTM D3985 《Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor》.

[0253] (3) Deep drawing performance test: 40 film samples are subjected to deep drawing test, and the maximum deep drawing value until no crack appears on the film is the test value.

[0254] (4) Puncture force performance test: The test is carried out in accordance with the requirements of ASTM D4833-2007 《Index Puncture Resistance of Geomembranes and Related Products》.

[0255] (5) Moisture absorption dimensional elongation: The film is first dried in a vacuum drying oven at 85 °C for 24 hours, then taken out and the length L0 at the center is measured. Then the sample is placed in an environment of 60% RH / 25 °C for 24 hours, and its length L1 is measured again. The moisture absorption elongation is S = (L1 - L0) / L0 * 100%.

[0256] Note: In the table, the symbol "◎" represents excellent, the symbol "○" represents good, the symbol "□" represents fair, the symbol "△" represents medium, the symbol "☆" represents poor, the symbol "×" represents extremely poor, and the symbol "-" represents not tested or not required to be tested, no relevant data.

[0257] It can be seen from the table that compared with the traditional film and the film provided by the comparative example, the toughened high deep-drawing biaxially oriented polyamide film provided by the present invention, through a specific material combination and preparation method, makes the prepared biaxially oriented polyamide film have better toughness and processing performance, and at the same time also maintains excellent tensile strength, moisture absorption elongation, etc., has good compatibility, high barrier property, good deep-drawing formability and toughness, and can meet the needs of different high-end market fields.

[0258] Although terms such as substrate layer, upper surface layer, intermediate layer, etc. are used more in this article, the possibility of using other terms is not excluded. These terms are only used to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A toughened high-impact deep-drawing biaxially oriented polyamide film, characterized in that, It consists of a three-layer structure, which is successively the upper surface layer, the middle layer and the lower surface layer from top to bottom; By mass parts, the upper surface layer includes 1-8 parts of anti-sticking masterbatch, 1-50 parts of poly(ω-aminoundecanoyl), and 42-98 parts of polylaurolactam; the middle layer includes 1-30 parts of polylaurolactam, 5-20 parts of nylon copolymer, 1-15 parts of N,N-dimethyl-p-toluenesulfonamide, and 35-93 parts of polyamide 6; the lower surface layer includes 1-8 parts of anti-sticking masterbatch, 1-50 parts of poly(ω-aminoundecanoyl), and 42-98 parts of polylaurolactam; Among them, the nylon copolymer is a nylon copolymer synthesized by polycondensation reaction of the terminal group of block polyamide and the reactive end group of block polyalkylene ether polyol; the block polyamide includes a first block polyamide and a second block polyamide; The first block polyamide is prepared from caprolactam, pure water and benzoic acid according to the mass ratio of (70-96.5):(3-20):(0.5-10); The second block polyamide is prepared from laurolactam, pure water and adipic acid according to the mass ratio of (72-97.5):(2-20):(0.5-8).

2. The toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 1, wherein: The block polyalkylene ether polyol is polyhexamethylene ether diol.

3. The toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 1, wherein: The anti-sticking masterbatch, by mass parts, includes 1-5 parts of lubricant, 2-15 parts of opening agent and 80-97 parts of poly(ω-aminoundecanoyl).

4. The toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 3, wherein: The lubricant is selected from one or a combination of several of PE wax, oleic acid amide, erucic acid amide, ethylene bisstearamide; the opening agent is selected from one or a combination of several of calcium carbonate, kaolin, diatomite, talc powder, silica.

5. The toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 1, characterized in that: The thickness of the toughened high-impact deep-drawing biaxially oriented polyamide film is 10-30 μm; among them, the thickness of the upper surface layer and the lower surface layer is 1-4 μm; the thickness of the middle layer is 2-28 μm.

6. The preparation method of the toughened high impact deep drawing biaxially oriented polyamide film according to any one of claims 1-5, characterized in that, It includes the following steps: Dry the raw materials and control the moisture content of the raw materials below 800 ppm; Mix the raw materials of the upper surface layer, the middle layer and the lower surface layer respectively according to the formula ratio, and then melt and plasticize and extrude them through their respective extruders at a temperature of 230-290 °C, and flow out through a coat hanger die head; Use a low-pressure air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 100-350 μm and the temperature of the cold drum is 6-30 °C; Preheat the thick sheet, perform longitudinal stretching at a temperature of 45-65 °C, and then perform shaping and cooling. The stretching ratio of the longitudinal stretching is 2.5-3.5 times; Send the longitudinally stretched film into a transverse stretching machine, the preheating temperature is 60-85 °C, the stretching temperature is 70-150 °C, and the stretching ratio is 3.0-4.5 times; Perform heat setting on the stretched film, where the setting temperature is 190-220 °C and the setting time is 1-50 s, and then the film is cooled and corona post-treated. The corona treatment power is 6-15 Wmin / m², and it is wound up; Slit the wound-up toughened high-impact deep-drawing biaxially oriented polyamide film as required, and the toughened high-impact deep-drawing biaxially oriented polyamide film is obtained.

7. The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 6, wherein The preparation method of the nylon copolymer is as follows: Caprolactam, pure water and benzoic acid are added into a high-pressure reactor. Vacuum is pumped for 10 - 120 minutes, nitrogen is introduced for 5 - 40 minutes, and this is circulated 3 - 10 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 0.1 - 1.5 MPa; The high-pressure reactor is heated to 220 - 295 °C, and at the same time, stirring is started. The stirring speed is controlled at 30 - 150 r / min, and the reaction is carried out under isothermal and isobaric conditions for 2 - 20 hours. Then, the pressure is reduced to atmospheric pressure by releasing gas, and at the same time, the temperature is reduced to 30 - 100 °C to obtain the first block polyamide prepolymer A; Dodecanolactam, pure water and adipic acid are added into the high-pressure reactor. Vacuum is pumped for 10 - 100 minutes, nitrogen is introduced for 5 - 25 minutes, and this is circulated 3 - 8 times to ensure that each component is under nitrogen protection, and the pressure in the high-pressure reactor is controlled to be maintained at 0.1 - 1.0 MPa; The high-pressure reactor is heated to 180 - 280 °C, and at the same time, stirring is started. The stirring speed is controlled at 20 - 120 r / min, and the reaction is carried out under isothermal and isobaric conditions for 2 - 12 hours. Then, the pressure is reduced to atmospheric pressure by releasing gas, and at the same time, the temperature is reduced to 20 - 80 °C to obtain the second block polyamide prepolymer B; While flushing with nitrogen, the first block polyamide prepolymer A, the second block polyamide prepolymer B and the block polyalkylene ether polyol are added into the high-pressure reactor, and vacuum is pumped for 10 - 30 minutes, nitrogen is introduced for 5 - 30 minutes, and this is circulated 3 - 9 times; The temperature of the high-pressure reactor is raised to 220 - 260 °C, and the mixture is stirred under nitrogen for 1 - 6 hours, and the stirring speed is 20 - 60 r / min; A catalyst is added and the reaction continues for 1 - 5 hours, and then the system is discharged under reduced pressure for 0 - 3 hours, and the reduced pressure environment < 10 mbar; The material is subjected to strand casting and pelletizing, and dried at 80 - 120 °C to obtain the required nylon copolymer.

8. The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 7, characterized in that: The mass ratio of the first block polyamide prepolymer A, the second block polyamide prepolymer B, the block polyalkylene ether polyol and the catalyst is (3 - 64.9) : (30 - 55) : (5 - 40) : (0.1 - 2).

9. The preparation method of the toughened high-impact deep-drawing biaxially oriented polyamide film according to claim 8, wherein: The catalyst is tetrabutyl titanate.

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