A flame-retardant and matting polyamide film and its preparation method

Abstract

The present invention relates to the technical field of flexible packaging, and particularly relates to a flame-retardant and matting polyamide film and a preparation method thereof. The film layer structure of the flame-retardant and matting polyamide film sequentially includes a flame-retardant and matting upper surface layer, a polyamide film substrate intermediate layer, and a flame-retardant and matting lower surface layer from top to bottom; the flame-retardant and matting upper surface layer and the flame-retardant and matting lower surface layer are formed by respectively coating a coating solution on the upper surface and the lower surface of the polyamide film substrate intermediate layer; the coating solution includes an adhesive, a first flame retardant, and a solvent; the polyamide film substrate intermediate layer includes a first surface layer, a second surface layer, and a core layer between the first surface layer and the second surface layer; by weight, the core layer includes 1 to 15 parts of a second flame retardant and 85 to 99 parts of polyamide. The flame-retardant and matting polyamide film provided by the present invention not only has outstanding flame-retardant performance, but also has low gloss and high haze, with prominent matting function and a soft visual effect; and it has excellent tensile strength and high transparency.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible packaging, and particularly relates to a flame-retardant and matting polyamide film and a preparation method thereof. Background Art

[0002] BOPA film, that is, biaxially oriented nylon film, as one of the three most popular films at present, in addition to having high tensile strength and excellent puncture resistance, also has outstanding properties in terms of gas barrier property, pinhole resistance, transparency, printability, etc., and can meet people's requirements for high barrier property, high strength, high transparency, thinness, light weight and extremely wide temperature range of use (-60°C to 150°C) of packaging materials. Therefore, it is widely used in many packaging fields such as food packaging, pharmaceutical packaging, cosmetic packaging and mechanical and electronic product packaging.

[0003] With the continuous development of social economy, the application of BOPA film in other new fields has also been developed, such as aluminum-plastic encapsulation film for lithium batteries, electronic product packaging, etc. Lithium batteries and electronic products may have the risk of spontaneous combustion or explosion during use, and even cause fires. Therefore, the nylon film used for packaging such products also needs to have good flame retardancy, while the self-flame retardant grade of nylon material is not high, only reaching UL94 V-2, and the oxygen index is about 24, which does not meet the application standards of lithium batteries and electronic products. Therefore, improving the flame retardant performance of biaxially oriented nylon film is beneficial to broaden the application of biaxially oriented nylon film in the packaging field of such products.

[0004] In addition, if the BOPA film can have excellent matting effect while having excellent flame retardant performance, it will give a more gentle visual impact, can significantly improve the appearance grade of the product, and make the product have better market competitiveness. However, the current BOPA matting films on the market generally produce the effect by adding inorganic powders and generating light diffuse reflection and refraction on the film surface after stretching. But this type of BOPA matting film has the following defects: the matting effect of this film is poor, and the addition of a large amount of inorganic powders will reduce the physical and mechanical properties of the film, which is unacceptable for lithium-ion battery encapsulation films with higher requirements than ordinary packaging.

[0005] Therefore, how to obtain a flame-retardant and matting polyamide film, which not only has excellent flame retardant effect, but also has a self-matting effect, has a gentle visual impact, and at the same time maintains good mechanical properties has become an urgent problem to be solved at present. Summary of the Invention

[0006] To solve the deficiencies of the existing BOPLA films mentioned in the background art; the present invention provides a flame-retardant and matte polyamide film, the film layer structure of which sequentially includes a flame-retardant and matte upper surface layer, a polyamide film substrate intermediate layer, and a flame-retardant and matte lower surface layer from top to bottom;

[0007] The flame-retardant and matte upper surface layer and the flame-retardant and matte lower surface layer are formed by respectively coating a coating solution on the upper surface and the lower surface of the polyamide film substrate intermediate layer; the coating solution includes an adhesive, a first flame retardant, and a solvent; the polyamide film substrate intermediate layer includes a first surface layer, a second surface layer, and a core layer between the first surface layer and the second surface layer; by weight, the core layer includes 1 to 15 parts of a second flame retardant and 85 to 99 parts of polyamide.

[0008] In one embodiment, the polyamide film substrate intermediate layer is a three-layer co-extruded biaxially oriented polyamide film composed of a first surface layer, a core layer, and a second surface layer, and the first surface layer and the second surface layer are corona-treated; by weight, the first surface layer includes 1 to 10 parts of an anti-sticking masterbatch and 90 to 99 parts of polyamide; the second surface layer includes 1 to 10 parts of an anti-sticking masterbatch and 90 to 99 parts of polyamide; the weight ratio of the adhesive, the first flame retardant, and the solvent is (10 to 50):(1 to 20):(30 to 89).

[0009] In one embodiment, the first flame retardant is an organic phosphite; the second flame retardant includes hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphonate); the weight ratio of hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphonate) is (20 to 40):(10 to 30):(30 to 70).

[0010] In one embodiment, the particle size D of the first flame retardant 50 ≤1.5 μm, its particle size D 95 ≤3.5 μm, and its phosphorus content ≥ 23%; the particle size D of the second flame retardant 50 ≤2.0 μm.

[0011] In one embodiment, the adhesive includes a main agent and a curing agent, and the weight ratio of the main agent to the curing agent is (90 to 99):(1 to 10).

[0012] In one embodiment, the main agent includes polyurethane and acrylate, and the weight ratio of polyurethane to acrylate is (40 to 80):(20 to 60); the curing agent is polymethylene polyphenyl isocyanate; the solvent includes ethyl acetate and isopropanol, and the weight ratio of ethyl acetate to isopropanol is (30 to 80):(20 to 70).

[0013] In one embodiment, the anti - sticking masterbatch is a composition of polyamide and additives. The additives are one or more combinations of lubricants, antiblocking agents, and antioxidants; the polyamide is one or more combinations of nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 1010, nylon 1212, nylon MXD6, nylon 6I, nylon 5T, nylon 6T, nylon 9T, and nylon 10T.

[0014] In one embodiment, the thickness of the intermediate layer of the polyamide film substrate is 10 - 60 μm, wherein the thickness of both the first surface layer and the second surface layer is 1 - 6 μm, and the thickness of the core layer is 8 - 48 μm.

[0015] In one embodiment, the preparation method of the coating liquid comprises the following steps:

[0016] S1. Add different raw material components of the main agent and the solvent into a container according to a certain weight ratio, and stir evenly to obtain mixture L;

[0017] S2. Add the first flame retardant into mixture L and mix evenly to obtain mixture M;

[0018] S3. Add the curing agent into mixture M and mix evenly to obtain mixture N;

[0019] S4. Carry out negative pressure filtration on mixture N obtained in S3 to obtain the coating liquid.

[0020] The present invention also provides a preparation method of the above - mentioned flame - retardant and matting polyamide film, which comprises the following steps:

[0021] S100 Prepare the anti - sticking masterbatch: According to the anti - sticking masterbatch formula, mix polyamide and additives according to a certain weight ratio, and melt - blend, extrude, draw into strips, and pelletize through a twin - screw extruder to obtain the anti - sticking masterbatch;

[0022] S200 Prepare the core layer material: According to the raw material ratio required for the core layer, mix polyamide and the second flame retardant evenly according to a certain weight ratio, and then melt - blend, extrude, draw into strips, and pelletize through a twin - screw extruder to obtain the core layer material;

[0023] S300: Put the materials for the first surface layer, the materials for the second surface layer, and the core layer material into different extruders respectively, and then melt - plasticize and extrude through their respective extruders at a temperature of 240 °C - 295 °C, and the melt flows out through a T - die head;

[0024] S400: Use an air knife to attach the melt to a cold drum to form a thick sheet;

[0025] S500: Immerse the thick sheet in water for pretreatment;

[0026] S600: Synchronously biaxially stretch the heated thick sheet to form a film;

[0027] S700: Heat-set the stretched film, and then cool the film and perform double-sided corona post-treatment to obtain the biaxially oriented polyamide film.

[0028] S800: Slit the biaxially oriented polyamide film as required to obtain the intermediate layer of the polyamide film substrate.

[0029] S900: Coat both the upper surface and the lower surface of the intermediate layer of the polyamide film substrate with a coating solution, with a coating thickness of 0.5 - 5 μm. After coating, perform drying treatment at 70°C - 120°C, and then cure at 40 - 65°C for 24h - 72h.

[0030] Compared with the prior art, a flame-retardant and matting polyamide film provided by the present invention has the following excellent effects:

[0031] The flame-retardant and matting polyamide film provided by the present invention not only has outstanding flame-retardant performance, but also has low gloss, high haze, prominent matting function, and a soft visual effect; and it has excellent tensile strength and high transparency; the flame-retardant, high-strength, and good-transparency polyamide film provided by the present invention can meet the needs of markets such as lithium-ion battery packaging and electronic product packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 use in 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.

[0033] Figure 1 It is a schematic diagram of the film layer structure of the flame-retardant and matting polyamide film in an embodiment provided by the present invention.

[0034] Reference Numerals:

[0035] 11 First surface layer 12 Core layer 13 Second surface layer

[0036] 20 Flame-retardant and matting upper surface layer 30 Flame-retardant and matting lower surface layer 10 Intermediate layer of the polyamide film substrate DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] 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 with reference to the accompanying drawings. Obviously, 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.

[0038] The present invention provides a flame-retardant and matting polyamide film, and the solution is as follows:

[0039] The film layer structure of the polyamide film sequentially includes a flame-retardant and matting upper surface layer 20, a polyamide film substrate intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are formed by coating liquids respectively coated on the upper surface and the lower surface of the polyamide film substrate intermediate layer 10; the coating liquid includes an adhesive, a first flame retardant, and a solvent; the polyamide film substrate intermediate layer 10 includes a first surface layer 11, a second surface layer 13, and a core layer 12 between the first surface layer 11 and the second surface layer 13.

[0040] Specifically, the polyamide film substrate intermediate layer 10 is a three-layer co-extruded biaxially oriented polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; its formula is as follows: by weight, the core layer 12 includes 1 to 15 parts of a second flame retardant and 85 to 99 parts of polyamide; the first surface layer 11 includes 1 to 10 parts of an anti-sticking masterbatch and 90 to 99 parts of polyamide; the second surface layer 13 includes 1 to 10 parts of an anti-sticking masterbatch and 90 to 99 parts of polyamide. And in the coating liquid, the weight ratio of the adhesive, the first flame retardant, and the solvent is (10 to 50):(1 to 20):(30 to 89).

[0041] Regarding the film layer size:

[0042] Preferably, the thickness of the polyamide film substrate intermediate layer 10 is 10 to 60 μm, wherein the thicknesses of the first surface layer 11 and the second surface layer 13 are both 1 to 6 μm, and the thickness of the core layer 12 is 8 to 48 μm. The thickness of the coating layer formed by coating the coating liquid is 0.5 to 5 μm.

[0043] Regarding the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30:

[0044] Preferably, the adhesive includes a main agent and a curing agent, and the weight ratio of the main agent to the curing agent is (90-99):(1-10). Further preferably, the main agent includes polyurethane and acrylate, and the weight ratio of the polyurethane to the acrylate is (40-80):(20-60); the curing agent is polymethylene polyphenyl isocyanate (PAPI).

[0045] Preferably, the first flame retardant is an organic phosphite; further preferably, the particle size D 50 ≤1.5 μm, and the particle size D 95 ≤3.5 μm, and its phosphorus content ≥ 23%.

[0046] Preferably, the solvent includes ethyl acetate and isopropanol, and the weight ratio of ethyl acetate to isopropanol is (30-80):(20-70).

[0047] For the polyamide film substrate intermediate layer 10:

[0048] For the core layer 12:

[0049] Preferably, the second flame retardant includes hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphonate); the weight ratio of hexachlorocyclotriphosphazene, melamine cyanurate to aluminum 3-ethylenebis(ethylphosphonate) is (20-40):(10-30):(30-70). Further preferably, the particle size D 50 ≤2.0 μm.

[0050] For the first surface layer 11 and the second surface layer 13:

[0051] Preferably, the anti-sticking masterbatch is a composition of polyamide and additives, and the additives are one or a combination of a lubricant, an antiblocking agent, and an antioxidant.

[0052] Further preferably, the lubricant is selected from one or a combination of erucamide, stearamide, oleamide, silicone powder, ethylene bisoleamide, ethylene bisstearamide, and ethylene dilaurylamide; the antioxidant is selected from one or a combination of antioxidant 1098, antioxidant 1010, antioxidant 168, antioxidant SEED, antioxidant DNP, and antioxidant phosphite; the antiblocking agent is selected from one or a combination of silica, calcium carbonate, talc, titanium dioxide, kaolin, magnesium carbonate, aluminum oxide, barium carbonate, diatomaceous earth, and silicone resin.

[0053] Among them, for the selection of polyamide in the flame-retardant and matting upper surface layer 20, the flame-retardant and matting lower surface layer 30, and the polyamide film substrate intermediate layer 10: Preferably, the polyamide is selected from one or more combinations of nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 1010, nylon 1212, nylon MXD6, nylon 6I, nylon 5T, nylon 6T, nylon 9T, and nylon 10T.

[0054] Specifically, the present invention also provides a method for preparing the flame-retardant and matting polyamide film, and the steps are as follows:

[0055] S100 Prepare the anti-sticking masterbatch: According to the anti-sticking masterbatch formula, mix the polyamide and the auxiliary agent in a certain weight ratio, melt and blend, extrude, draw into strips, and pelletize through a twin-screw extruder to obtain the anti-sticking masterbatch, and dry it for later use;

[0056] S200 Prepare the material for the core layer 12: According to the raw material ratio required for the core layer 12, mix the polyamide and the second flame retardant, and put them into a high-speed mixer for uniform mixing to make them evenly dispersed, and then melt and blend, extrude, draw into strips, and pelletize through a twin-screw extruder to obtain the material for the core layer 12;

[0057] S300: Put the materials for the first surface layer 11 (including 1 to 10 parts of the anti-sticking masterbatch and 90 to 99 parts of the polyamide), the materials for the second surface layer 13 (including 1 to 10 parts of the anti-sticking masterbatch and 90 to 99 parts of the polyamide), and the core layer 12 material into different extruders respectively, and then melt and plasticize and extrude through their respective extruders at a temperature of 240°C to 295°C, and the melt flows out through a T-shaped die head;

[0058] S400: Use an air knife to attach the melt to a cold drum to form a thick sheet; wherein, the thickness of the thick sheet is 90 to 450 μm, and the temperature of the cold drum is 10 to 40°C.

[0059] S500: Immerse the thick sheet in a water bath at 18°C to 98°C for pretreatment;

[0060] S600: Synchronously biaxially stretch the thick sheet after heating to form a film; wherein, the stretching temperature is 140°C to 221°C, and the stretching ratio is 2.7×2.7 to 4.1×4.1;

[0061] S700: Perform heat setting treatment on the stretched film, wherein, the setting temperature is 170 to 238°C, the setting time is 3 s to 60 s, and then cool the film and perform double-sided corona post-treatment, and the corona treatment power is 5 to 16 Wmin / m 2 , and then obtain the biaxially stretched polyamide film and wind it up.

[0062] S800: Slit the biaxially oriented polyamide film after winding as required to obtain the polyamide film substrate intermediate layer 10; wherein, the thickness of the polyamide film substrate intermediate layer 10 is 10 μm to 60 μm;

[0063] S900: Coat the upper and lower surfaces of the polyamide film substrate intermediate layer 10 with the coating liquid: Place the polyamide film substrate intermediate layer 10 on the unwinding reel of the coater, pour the coating liquid into the glue tank, adjust the coater parameters to coat on its upper surface layer and / or lower surface layer, the coating thickness is 0.5 - 5 μm, after coating, conduct drying treatment in an oven at 70°C - 120°C, and then wind and place it in a curing chamber at 40°C - 65°C for curing for 24 - 72 h to obtain the flame-retardant and matting polyamide film.

[0064] Among them, the preparation method of the coating liquid includes the following steps:

[0065] S1. Add different raw material components of the main agent of the adhesive into the mixing barrel in proportion, stir at a low speed of 50 - 200 rpm for 3 - 5 min, add different solvents in sequence and stir each for 5 - 10 min to obtain mixture L;

[0066] S2. Continue to stir mixture L at the same rotation speed, add the flame retardant required by the formula, increase the rotation speed, control the stirring speed at 300 - 800 rpm, and the stirring time is 10 - 30 min to obtain mixture M;

[0067] S3. Continue to stir mixture M, control the stirring speed at 20 - 200 rpm, add the curing agent of the adhesive, and continuously stir for 5 - 15 min to obtain mixture N;

[0068] S4. Conduct negative pressure filtration on the mixture N obtained in S3 twice to obtain the required flame-retardant and matting coating liquid;

[0069] The present invention also provides the following examples and comparative examples:

[0070] Example 1

[0071] The film layer structure of the flame-retardant and matting polyamide film: As Figure 1 shown, it sequentially includes a flame-retardant and matting upper surface layer 20, a polyamide film substrate intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the polyamide film substrate intermediate layer 10 is a three-layer coextruded biaxially oriented polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are respectively formed by coating the coating liquid on the upper and lower surfaces of the polyamide film substrate intermediate layer 10.

[0072] Among them, the thickness of the intermediate layer 10 of the polyamide film substrate is 15 μm; among them, the thicknesses of the first surface layer 11 and the second surface layer 13 are both 2 μm; the thickness of the core layer 12 is 11 μm.

[0073] The formulation and preparation method of the coating solution:

[0074] By mass, the coating solution includes 20 parts of an adhesive, 10 parts of a second flame retardant, and 70 parts of a solvent;

[0075] Among them, the adhesive is composed of a main agent and a curing agent, and the ratio of the main agent to the curing agent is 9:5 by mass; the main agent is selected from the mixture of polyurethane and acrylate, and the ratio of the two is 60:40 by mass; the curing agent is selected from polymethylene polyphenyl isocyanate (PAPI); the first flame retardant is an organic phosphite; its particle size D 50 = 1.2 μm, particle size D 95 = 3.0 μm, and its phosphorus content = 24%; the solvent is selected from the mixture of ethyl acetate and isopropyl alcohol, and the mass ratio of ethyl acetate to isopropyl alcohol is 60:40;

[0076] The preparation method of the coating solution includes the following steps:

[0077] S1. Add different components of the adhesive main agent into the mixing tank according to the proportion, stir at a low speed of 100 rpm for 3 min, add two different solvents in sequence, and stir each for 6 min to obtain a mixture L;

[0078] S2. Continue to stir the mixture L at the same rotation speed, add the flame retardant required by the formula, increase the rotation speed, and control the stirring speed at 500 rpm for 20 min to obtain a mixture M;

[0079] S3. Continue to stir the mixture M, control the stirring speed at 80 rpm, add the curing agent of the adhesive, and continuously stir for 10 min to obtain a mixture N;

[0080] S4. Filter the mixture N obtained in S3 under negative pressure twice to obtain the coating solution;

[0081] The raw material component formulation of the flame-retardant and matting polyamide film: By mass, the first surface layer 11 includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide; the core layer 12 includes 10 parts of a second flame retardant and 90 parts of polyamide; the second surface layer 13 includes 5 parts of an anti-sticking masterbatch and 95 parts of polyamide.

[0082] Among them, the second flame retardant is selected from the mixture of hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphinate), and the ratio of the three is 25:15:60 by mass, and the particle size D50 = 1.5 μm; The anti-sticking masterbatch is a mixture composed of four raw materials: polyamide, lubricant, antiblocking agent, and antioxidant. The ratio of polyamide: lubricant: antiblocking agent: antioxidant by mass is 81:6:10:3; The lubricant is selected from stearamide; The antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; The antiblocking agent is selected from silicon dioxide;

[0083] Among them, for the polyamide in the flame-retardant and matting upper surface layer 20, the flame-retardant and matting lower surface layer 30, and the polyamide film substrate intermediate layer 10, nylon 6 is selected.

[0084] The present invention also provides a method for preparing a flame-retardant and matting polyamide film, which includes the following preparation steps:

[0085] The first step: Mix polyamide, lubricant, antiblocking agent, and antioxidant in a set ratio, melt-blend, extrude, draw into strands, and pelletize through a twin-screw extruder to obtain the required anti-sticking masterbatch, and dry it for later use.

[0086] The second step: Mix polyamide and the flame retardant for the core layer 12 in a set ratio, put them into a high-speed mixer for uniform mixing to make them evenly dispersed, and then melt-blend, extrude, draw into strands, and pelletize through a twin-screw extruder to obtain the required flame-retardant core layer 12 material, and dry it for later use.

[0087] The third step: According to the above formula, put the materials for the first surface layer 11 (anti-sticking masterbatch and polyamide), the materials for the second surface layer 13 (anti-sticking masterbatch and polyamide), and the core layer 12 material into different extruders respectively, and then melt and plasticize and extrude through their respective extruders at a temperature of 265 °C, and the melt flows out through a T-die.

[0088] The fourth step: Use an air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 160 μm and the temperature of the cold drum is 15 °C.

[0089] The fifth step: Immerse the thick sheet in a water bath at 50 °C for pretreatment.

[0090] The sixth step: Heat the thick sheet and then perform synchronous biaxial stretching using a Brückner magnetic levitation synchronous biaxial stretching device, where the stretching temperature is 190 °C and the stretching ratio is 3.15 × 3.45.

[0091] The seventh step: Perform heat setting on the stretched film, where the setting temperature is 210 °C and the setting time is 5 s, and then the film is cooled and subjected to double-sided corona post-treatment, and the corona treatment power is 8 Wmin / m 2 , and wind it up.

[0092] Step 8: Slit the wound biaxially oriented polyamide film as required, and finally obtain the polyamide film substrate intermediate layer 10 with a film thickness of 15 μm.

[0093] Step 9: Place the film of the substrate layer on the unwinding reel of the coater, pour the coating liquid into the glue tank, adjust the parameters of the coater to coat on the surfaces of the upper surface layer and the lower surface layer, with the thickness of the coating layer being 2 μm. After coating, send the film into an oven at 80 °C for drying, and then wind it up and put it into a curing chamber at 45 °C for curing for 48 h to obtain the flame-retardant and matting polyamide film.

[0094] Example 2

[0095] Film layer structure of the flame-retardant and matting polyamide film: As Figure 1 shown, it sequentially includes a flame-retardant and matting upper surface layer 20, a polyamide film substrate intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the polyamide film substrate intermediate layer 10 is a three-layer coextruded biaxially oriented polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are respectively formed by coating the coating liquid on the upper surface and the lower surface of the polyamide film substrate intermediate layer 10.

[0096] Among them, the thickness of the polyamide film substrate intermediate layer 10 is 15 μm; among them, the thicknesses of both the polyamide first surface layer 11 and the polyamide second surface layer 13 are 1.5 μm; the thickness of the core layer 12 is 12 μm.

[0097] Formulation and preparation method of the coating liquid:

[0098] The coating liquid, by mass, includes 15 parts of an adhesive, 5 parts of a first flame retardant, and 80 parts of a solvent;

[0099] Among them, the adhesive is composed of a main agent and a curing agent, and the ratio of the main agent to the curing agent is 91:9 by mass; the main agent is selected from a mixture of polyurethane and acrylate, and the ratio of the two is 50:50 by mass; the curing agent is selected from polymethylene polyphenyl isocyanate (PAPI); the first flame retardant is an organic phosphite, with its particle size D 50 = 1.2 μm, particle size D 95 = 3.0 μm, and its phosphorus content = 24%; the solvent is selected from a mixture of ethyl acetate and isopropyl alcohol, and the mass ratio of ethyl acetate to isopropyl alcohol is 40:60.

[0100] The preparation method of the coating liquid includes the following steps:

[0101] S1. Add different components of the main agent of the adhesive into the mixing barrel according to the proportion, stir at a low speed of 80 rpm for 3 min, add two different solvents in sequence, and stir for 5 min each to obtain mixture L;

[0102] S2. Continue to stir mixture L at the same rotation speed, add the flame retardant required by the formula, increase the rotation speed, control the stirring speed at 450 rpm, and stir for 15 min to obtain mixture M;

[0103] S3. Continue to stir mixture M, control the stirring speed at 60 rpm, add the curing agent of the adhesive, and continuously stir for 8 min to obtain mixture N;

[0104] S4. Filter the mixture N obtained in S3 twice under negative pressure to obtain the required flame retardant and matting coating liquid;

[0105] The raw material composition formula of the flame retardant and matting polyamide film: by mass, the first surface layer 11 includes 4 parts of anti-sticking masterbatch and 96 parts of polyamide; the core layer 12 includes 5 parts of the second flame retardant and 95 parts of polyamide; the second surface layer 13 includes 4 parts of anti-sticking masterbatch and 96 parts of polyamide.

[0106] Among them, the second flame retardant is selected from the mixture of hexachlorocyclotriphosphazene, melamine cyanurate and aluminum 3-ethylenebis(ethylphosphinate), and the mass ratio of the three is 20:30:50; the particle size D of the second flame retardant 50 = 1.5 μm; the anti-sticking masterbatch is a mixture of four of polyamide, lubricant, opening agent and antioxidant, and the polyamide: lubricant: opening agent: antioxidant is 81:6:10:3 by mass; the lubricant is selected from stearamide; the antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; the opening agent is selected from silicon dioxide;

[0107] Among them, the polyamide selected for the flame retardant and matting upper surface layer 20, the flame retardant and matting lower surface layer 30 and the polyamide film substrate intermediate layer 10 is all selected from nylon 6.

[0108] The present invention also provides a preparation method of a flame retardant and matting polyamide film, which includes the following preparation steps:

[0109] The first step: Mix polyamide, lubricant, opening agent and antioxidant in a set proportion, melt-blend, extrude, draw and pelletize through a twin-screw extruder to obtain the required anti-sticking masterbatch, and dry it for standby.

[0110] Step 2: Mix the polyamide and the flame retardant for the core layer 12 in a set ratio, put them into a high-speed mixer for uniform mixing to make them evenly dispersed, and then melt blend, extrude, draw into strands, and pelletize through a twin-screw extruder to obtain the required flame-retardant core layer 12 material, which is dried for later use.

[0111] Step 3: According to the above formula, put the materials for the first surface layer 11 (anti-sticking masterbatch and polyamide), the materials for the second surface layer 13 (anti-sticking masterbatch and polyamide), and the core layer 12 material into different extruders respectively, and then melt and plasticize and extrude through their respective extruders at a temperature of 260 °C, and the melt flows out through a T-shaped die head.

[0112] Step 4: Use an air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 160 μm and the temperature of the cold drum is 15 °C.

[0113] Step 5: Immerse the thick sheet in a water bath at 45 °C for pretreatment.

[0114] Step 6: Heat the thick sheet and then perform synchronous biaxial stretching using a Bruckner magnetic levitation synchronous biaxial stretching device, where the stretching temperature is 195 °C and the stretching ratio is 3.25×3.55.

[0115] Step 7: Perform heat setting on the stretched film, where the setting temperature is 212 °C and the setting time is 6 s, and then the film is cooled and subjected to double-sided corona post-treatment, and the corona treatment power is 8 Wmin / m 2 , and then wind it up.

[0116] Step 8: Slit the wound biaxially stretched polyamide film as required, and finally obtain the middle layer 10 of the polyamide film substrate, and the film thickness is 15 μm.

[0117] Step 9: Place the substrate layer film on the unwind reel of a coater, pour the coating liquid into the glue tank, adjust the coater parameters to coat on the surfaces of the upper surface layer and the lower surface layer, the thickness of the coating is 1.8 μm, after coating, send the film into an oven at 80 °C for drying, and then wind it up and put it into a curing chamber at 45 °C for curing for 48 h to obtain the flame-retardant and matte polyamide film.

[0118] Example 3

[0119] The film layer structure of the flame-retardant and matte polyamide film: As Figure 1As shown in the figure, it successively includes a flame-retardant and matting upper surface layer 20, a polyamide film substrate intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the polyamide film substrate intermediate layer 10 is a three-layer co-extruded biaxially stretched polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are respectively formed by coating a coating liquid on the upper surface and the lower surface of the polyamide film substrate intermediate layer 10.

[0120] Among them, the thickness of the polyamide film substrate intermediate layer 10 is 15 μm; among them, the thicknesses of the polyamide first surface layer 11 and the polyamide second surface layer 13 are both 1.5 μm; the thickness of the core layer 12 is 12 μm.

[0121] The formula and preparation method of the coating liquid:

[0122] The coating liquid, by mass, includes 30 parts of an adhesive, 15 parts of a first flame retardant, and 55 parts of a solvent;

[0123] Among them, the adhesive is composed of a main agent and a curing agent, and the ratio of the main agent to the curing agent is 96:4 by mass; the main agent is selected from the mixture of polyurethane and acrylate, and the ratio of the two is 70:30 by mass; the curing agent is selected from polymethylene polyphenyl isocyanate (PAPI); the first flame retardant is an organic phosphite, and its particle size D 50 = 1.1 μm, particle size D 95 = 2.6 μm, and its phosphorus content = 25%; the solvent is selected from the mixture of ethyl acetate and isopropyl alcohol, and the mass ratio of ethyl acetate to isopropyl alcohol is 70:30.

[0124] The preparation method of the coating liquid includes the following steps:

[0125] S1. Add different components of the adhesive main agent into a mixing tank in proportion, stir at a low speed of 120 rpm for 5 min, successively add two different solvents, and stir each for 8 min to obtain a mixture L;

[0126] S2. Continue to stir the mixture L at the same rotation speed, add the flame retardant required by the formula, increase the rotation speed, control the stirring speed at 600 rpm, and stir for 25 min to obtain a mixture M;

[0127] S3. Continue to stir the mixture M, control the stirring speed at 60 rpm, add the curing agent of the adhesive, and continuously stir for 12 min to obtain a mixture N;

[0128] S4. Filter the mixture N obtained in S3 under negative pressure twice to obtain the required flame-retardant and matting coating liquid;

[0129] The raw material formulation of the flame-retardant and matting polyamide film: By mass fraction, the first surface layer 11 includes 5 parts of anti-sticking masterbatch and 95 parts of polyamide; the core layer 12 includes 15 parts of flame retardant and 85 parts of polyamide; the second surface layer 13 includes 5 parts of anti-sticking masterbatch and 95 parts of polyamide.

[0130] Among them, the second flame retardant is selected from the mixture of hexachlorocyclotriphosphazene, melamine cyanurate and aluminum 3-ethylenebis(ethylphosphinate), and the mass ratio of the three is 15:15:70, and its particle size D 50 = 1.2 μm; the anti-sticking masterbatch is a mixture of four components including polyamide, lubricant, opening agent and antioxidant; the polyamide: lubricant: opening agent: antioxidant is 85:5:8:3 by mass fraction; the lubricant is selected from stearamide; the antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; the opening agent is selected from silicon dioxide;

[0131] Among them, for the polyamide in the flame-retardant and matting upper surface layer 20, the flame-retardant and matting lower surface layer 30 and the polyamide film substrate intermediate layer 10, nylon 6 is selected.

[0132] The present invention also provides a preparation method of the flame-retardant and matting polyamide film, which includes the following preparation steps:

[0133] The first step: Mix polyamide, lubricant, opening agent and antioxidant in a set ratio, and melt-blend, extrude, draw into strips and pelletize through a twin-screw extruder to obtain the required anti-sticking masterbatch, and dry it for later use.

[0134] The second step: Mix polyamide and the flame retardant for the core layer 12 in a set ratio, put them into a high-speed mixer for uniform mixing to make them evenly dispersed, and then melt-blend, extrude, draw into strips and pelletize through a twin-screw extruder to obtain the required flame-retardant core layer 12 material, and dry it for later use.

[0135] The third step: According to the above formula, put the materials for the first surface layer 11 (anti-sticking masterbatch and polyamide), the materials for the second surface layer 13 (anti-sticking masterbatch and polyamide) and the core layer 12 material into different extruders respectively, and then melt and plasticize and extrude through their respective extruders at a temperature of 265 °C, and the melt flows out through a T-shaped die head.

[0136] The fourth step: Use an air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 160 μm and the temperature of the cold drum is 18 °C.

[0137] The fifth step: Immerse the thick sheet in a water bath at 55 °C for pretreatment.

[0138] Step 6: Heat the thick sheet and then perform synchronous biaxial stretching using a Brückner magnetic levitation synchronous biaxial stretching device, where the stretching temperature is 196 °C and the stretching ratio is 3.20 × 3.55.

[0139] Step 7: Perform heat setting on the stretched film, where the setting temperature is 212 °C and the setting time is 6 s. Then, cool the film and perform post-treatment of double-sided corona. The corona treatment power is 9 Wmin / m 2 , and wind it up.

[0140] Step 8: Slit the wound biaxially stretched polyamide film as required, and finally obtain the polyamide film substrate intermediate layer 10 with a film thickness of 15 μm.

[0141] Step 9: Place the film of the substrate layer on the unwind reel of the coater, pour the coating liquid into the glue tank, adjust the coater parameters to coat on the surfaces of the upper surface layer and the lower surface layer. The thickness of the coating is 2.5 μm. After coating, send the film into an oven at 85 °C for drying, and then wind it up and put it into a curing chamber at 48 °C for curing for 48 h to obtain the flame-retardant and matting polyamide film.

[0142] Example 4

[0143] Film layer structure of the flame-retardant and matting polyamide film: As Figure 1 shown, it successively includes a flame-retardant and matting upper surface layer 20, a polyamide film substrate intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the polyamide film substrate intermediate layer 10 is a three-layer co-extruded biaxially stretched polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are respectively formed by coating the coating liquid on the upper surface and the lower surface of the polyamide film substrate intermediate layer 10.

[0144] Among them, the thickness of the polyamide film substrate intermediate layer 10 is 15 μm; among them, the thicknesses of both the polyamide first surface layer 11 and the polyamide second surface layer 13 are 2 μm; the thickness of the core layer 12 is 11 μm.

[0145] Formulation and preparation method of the coating liquid:

[0146] The coating liquid, by mass, includes 40 parts of adhesive, 20 parts of flame retardant, and 60 parts of solvent;

[0147] Among them, the adhesive is composed of a main agent and a curing agent, and the mass ratio of the main agent to the curing agent is 98:2; the main agent is selected from the mixture of polyurethane and acrylate, and the mass ratio of the two is 80:20; the curing agent is selected from polymethylene polyphenyl isocyanate (PAPI); the first flame retardant is an organic phosphite, and its particle size D 50 = 1.0 μm, particle size D 95 = 2.5 μm, and its phosphorus content = 24%; the solvent is selected from the mixture of ethyl acetate and isopropyl alcohol, and the mass ratio of ethyl acetate to isopropyl alcohol is 30:70.

[0148] The preparation method of the coating liquid includes the following steps:

[0149] S1. Add different components of the main agent of the adhesive into the mixing tank in proportion, stir at a low speed of 80 rpm for 4 min, add two different solvents in sequence, and stir each for 7 min to obtain mixture L;

[0150] S2. Continue to stir mixture L at the same rotation speed, add the flame retardant required by the formula, increase the rotation speed, control the stirring speed at 700 rpm, and the stirring time is 28 min to obtain mixture M;

[0151] S3. Continue to stir mixture M, control the stirring speed at 50 rpm, add the curing agent of the adhesive, and continuously stir for 12 min to obtain mixture N;

[0152] S4. Filter the mixture N obtained in S3 under negative pressure twice to obtain the required flame retardant and matting coating liquid.

[0153] The raw material component formula of the flame retardant and matting polyamide film: calculated by mass parts, the first surface layer 11 includes 6 parts of anti-sticking masterbatch and 94 parts of polyamide; the core layer 12 includes 12 parts of flame retardant and 88 parts of polyamide; the second surface layer 13 includes 6 parts of anti-sticking masterbatch and 94 parts of polyamide.

[0154] Among them, the second flame retardant is selected from the mixture of hexachlorocyclotriphosphazene, melamine cyanurate and aluminum 3-ethylenebis(ethylphosphonate), and the mass ratio of the three is 10:20:70, and its particle size D 50 = 1.0 μm; the anti-sticking masterbatch is a mixture of four of polyamide, lubricant, opening agent and antioxidant, and the polyamide:lubricant:opening agent:antioxidant is 77:8:12:3 by mass parts; the lubricant is selected from stearamide; the antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 2:1; the opening agent is selected from silicon dioxide;

[0155] Among them, for the selection of polyamide in the flame-retardant and matting upper surface layer 20, the flame-retardant and matting lower surface layer 30, and the polyamide film substrate intermediate layer 10, nylon 6 is selected.

[0156] The present invention also provides a method for preparing a flame-retardant and matting polyamide film, which includes the following preparation steps:

[0157] The first step: Mix polyamide, lubricant, antiblocking agent, and antioxidant in a set ratio, melt-blend, extrude, strand, and pelletize through a twin-screw extruder to obtain the required anti-sticking masterbatch, and dry it for later use.

[0158] The second step: Mix polyamide and the flame retardant for the core layer 12 in a set ratio, put them into a high-speed mixer for uniform mixing to make them evenly dispersed, and then melt-blend, extrude, strand, and pelletize through a twin-screw extruder to obtain the required flame-retardant core layer 12 material, and dry it for later use.

[0159] The third step: According to the above formula, put the materials for the first surface layer 11 (anti-sticking masterbatch and polyamide), the materials for the second surface layer 13 (anti-sticking masterbatch and polyamide), and the core layer 12 material into different extruders respectively, and then melt and plasticize and extrude through their respective extruders at a temperature of 260 °C, and the melt flows out through a T-die head.

[0160] The fourth step: Use an air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 165 μm and the temperature of the cold drum is 12 °C.

[0161] The fifth step: Immerse the thick sheet in a water bath at 58 °C for pretreatment.

[0162] The sixth step: Heat the thick sheet and then perform synchronous biaxial stretching using a Bruckner magnetic levitation synchronous biaxial stretching device, where the stretching temperature is 192 °C and the stretching ratio is 3.25×3.45.

[0163] The seventh step: Perform heat setting treatment on the stretched film, where the setting temperature is 208 °C and the setting time is 10 s, and then the film is cooled and subjected to double-sided corona post-treatment, and the corona treatment power is 10 Wmin / m 2 and wind it up.

[0164] The eighth step: Slit the wound biaxially stretched polyamide film as required, and finally obtain the polyamide film substrate intermediate layer 10, and the film thickness is 15 μm.

[0165] Step 9: Place the base layer film on the unwinding reel of the coater, pour the coating liquid into the glue tank, adjust the coater parameters to coat on the surfaces of the upper surface layer and the lower surface layer, with the thickness of the coating being 2.3 μm. After coating, send the film into an oven at 82 °C for drying, and then wind it up and place it in a curing chamber at 46 °C for curing for 60 h to obtain the flame-retardant and matting polyamide film.

[0166] Example 5

[0167] The film layer structure of the flame-retardant and matting polyamide film: As Figure 1 shown, it sequentially includes a flame-retardant and matting upper surface layer 20, a polyamide film base intermediate layer 10, and a flame-retardant and matting lower surface layer 30 from top to bottom; the polyamide film base intermediate layer 10 is a three-layer co-extruded biaxially oriented polyamide film composed of a first surface layer 11, a core layer 12, and a second surface layer 13, and the first surface layer 11 and the second surface layer 13 are corona-treated; the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting lower surface layer 30 are respectively formed by coating the coating liquid on the upper surface and the lower surface of the polyamide film base intermediate layer 10.

[0168] Among them, the thickness of the polyamide film base intermediate layer 10 is 15 μm; among them, the thicknesses of the polyamide first surface layer 11 and the polyamide second surface layer 13 are both 1.75 μm; the thickness of the core layer 12 is 11.5 μm.

[0169] The formula and preparation method of the coating liquid: The coating liquid, by mass, includes 45 parts of an adhesive, 20 parts of a flame retardant, and 30 parts of a solvent;

[0170] Among them, the adhesive is composed of a main agent and a curing agent, and the ratio of the main agent to the curing agent is 97:3 by mass; the main agent is selected from a mixture of polyurethane and acrylate, and the ratio of the two is 75:25 by mass; the curing agent is selected from polymethylene polyphenyl isocyanate (PAPI); the first flame retardant is an organic secondary phosphonate, with its particle size D 50 = 1.0 μm, particle size D 95 = 2.5 μm, and its phosphorus content = 23%; the solvent is selected from a mixture of ethyl acetate and isopropyl alcohol, and the mass ratio of ethyl acetate to isopropyl alcohol is 50:50.

[0171] The preparation method of the coating liquid includes the following steps:

[0172] S1. Add different components of the adhesive main agent into the mixing tank in proportion, stir at a low speed of 150 rpm for 3 min, sequentially add two different solvents, and stir each for 8 min to obtain a mixture L;

[0173] S2. Continue to stir the mixture L at the same rotational speed, add the flame retardant required by the formula, increase the rotational speed, control the stirring speed at 750 rpm, and stir for 26 minutes to obtain mixture M;

[0174] S3. Continue to stir the mixture M, control the stirring speed at 40 rpm, add the curing agent of the adhesive, and continuously stir for 14 minutes to obtain mixture N;

[0175] S4. Filter the mixture N obtained in S3 under negative pressure twice to obtain the required flame-retardant and matting coating liquid;

[0176] The raw material composition formula of the flame-retardant and matting polyamide film:

[0177] By mass, the first surface layer 11 includes 4 parts of anti-sticking masterbatch and 96 parts of polyamide; the core layer 12 includes 13 parts of flame retardant and 87 parts of polyamide; the second surface layer 13 includes 4 parts of anti-sticking masterbatch and 96 parts of polyamide.

[0178] Among them, the second flame retardant is selected from a mixture of three kinds of hexachlorocyclotriphosphazene, melamine cyanurate and aluminum 3-ethylenebis(ethylphosphinate), and the mass ratio of the three is 25:10:65, and its particle size D 50 = 1.3 μm; the anti-sticking masterbatch is a mixture of four kinds of polyamide, lubricant, opening agent and antioxidant, and the polyamide:lubricant:opening agent:antioxidant is 79:8:10:3 by mass; the lubricant is selected from a 1:1 mixture of stearamide and ethylene bisstearamide; the antioxidant is obtained by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 3:1; the opening agent is selected from silicon dioxide;

[0179] Among them, for the polyamide selection in the flame-retardant and matting upper surface layer 20, the flame-retardant and matting lower surface layer 30 and the polyamide film substrate intermediate layer 10, nylon 6 is selected;

[0180] The present invention also provides a preparation method of a flame-retardant and matting polyamide film, which includes the following preparation steps:

[0181] The first step: Mix polyamide, lubricant, opening agent and antioxidant in a set ratio, and melt-blend, extrude, draw and pelletize through a twin-screw extruder to obtain the required anti-sticking masterbatch, and dry it for later use.

[0182] The second step: Mix polyamide and the flame retardant for the core layer 12 in a set ratio, put them into a high-speed mixer for uniform mixing and dispersion, and then melt-blend, extrude, draw and pelletize through a twin-screw extruder to obtain the required flame-retardant core layer 12 material, and dry it for later use.

[0183] Step 3: According to the above formula, put the materials for the first surface layer 11 (anti-sticking masterbatch and polyamide), the materials for the second surface layer 13 (anti-sticking masterbatch and polyamide), and the materials for the core layer 12 into different extruders respectively, and then melt and plasticize and extrude them through their respective extruders at a temperature of 265 °C, and the melt flows out through a T-shaped die head.

[0184] Step 4: Use an air knife to attach the melt to a cold drum to form a thick sheet, where the thickness of the thick sheet is 170 μm and the temperature of the cold drum is 18 °C.

[0185] Step 5: Immerse the thick sheet in a water bath at 60 °C for pretreatment.

[0186] Step 6: Heat the thick sheet and then perform synchronous biaxial stretching using a Bruckner magnetic levitation synchronous biaxial stretching device, where the stretching temperature is 195 °C and the stretching ratio is 3.25×3.65.

[0187] Step 7: Perform heat setting on the stretched film, where the setting temperature is 216 °C and the setting time is 8 s, and then the film is cooled and subjected to double-sided corona post-treatment, and the corona treatment power is 9 Wmin / m 2 , and then wind it up.

[0188] Step 8: Slit the wound biaxially stretched polyamide film as required, and finally obtain the polyamide film substrate intermediate layer 10 with a film thickness of 15 μm.

[0189] Step 9: Place the substrate layer film on the unwind reel of a coater, pour the coating liquid into the glue tank, adjust the coater parameters to coat on the surfaces of the upper surface layer and the lower surface layer, the thickness of the coating is 2.5 μm, after coating, send the film into an oven at 78 °C for drying, and then wind it up and put it into a curing chamber at 47 °C for curing for 60 h to obtain the flame-retardant and matte polyamide film.

[0190] Comparative Example 1

[0191] Commercially available 15-μm BOPA film, ONT brand produced by Cangzhou Donghong Company.

[0192] Comparative Example 2

[0193] Commercially available 15-μm matte BOPA, ONHZ brand produced by Cangzhou Donghong Company.

[0194] Comparative Example 3

[0195] The difference between Comparative Example 3 and Example 1 is only that: the core layer 12 of Comparative Example 3 only includes 100 parts of polyamide and does not contain the second flame retardant, and the others are the same as in Example 1.

[0196] Comparative Example 4

[0197] The difference between Comparative Example 4 and Example 1 is only that: the flame-retardant and matting upper surface layer 20 and the flame-retardant and matting upper surface layer 20 are not prepared in the film layer of Comparative Example 4, that is, it only has the polyamide film substrate intermediate layer 10

[0198] Comparative Example 5

[0199] The difference between this comparative example and Example 1 is only that: tris(2-chloroethyl) phosphate is used as the first flame retardant in Comparative Example 5, and the others are the same as in Example 1.

[0200] Comparative Example 6

[0201] The difference between this comparative example and Example 1 is only that: the second flame retardant in Comparative Example 6 is selected from aluminum hydroxide, and the others are the same as in Example 1.

[0202] Comparative Example 7

[0203] The difference between this comparative example and Example 1 is only that: the second flame retardant in this comparative example is selected from a mixture of melamine cyanurate and aluminum 3-ethylenebis(ethylphosphinate), and the mass ratio of the two is 15:60 (the total addition amount of the second flame retardant remains unchanged), and the others are the same as in Example 1.

[0204] Comparative Example 8

[0205] The difference between this comparative example and Example 1 is only that: the second flame retardant in this comparative example is selected from a mixture of hexachlorocyclotriphosphazene and aluminum 3-ethylenebis(ethylphosphinate), and the mass ratio of the two is 25:60 (the total addition amount of the second flame retardant remains unchanged), and the others are the same as in Example 1.

[0206] Comparative Example 9

[0207] The difference between this comparative example and Example 1 is only that: the second flame retardant in this comparative example is selected from a mixture of hexachlorocyclotriphosphazene and melamine cyanurate, and the mass ratio of the two is 25:15 (the total addition amount of the second flame retardant remains unchanged), and the others are the same as in Example 1.

[0208] The flame-retardant and matting polyamide films prepared in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1 below:

[0209] Table 1 Performance test table of examples and comparative examples

[0210]

[0211]

[0212] Among them, the test items in Table 1 are specifically:

[0213] (1) Flame retardancy test: The test was carried out in accordance with the requirements of the standard ISO 9773 "Plastics - Determination of burning behavior of thin flexible vertical specimens in contact with a small - flame ignition source". The flame retardancy grades are represented by VTM - 0, VTM - 1, and VTM - 2 from high to low, while × indicates that it cannot even reach the VTM - 2 grade.

[0214] (2) Glossiness performance test: The test was carried out in accordance with the requirements of the standard ASTM D 2457 "Standard Test Method for Specular Gloss of Plastic Films and Solid Plastics".

[0215] (3) Transmittance and haze: The test was carried out in accordance with the standard requirements of GB / T 2410 - 2008 "Determination of light transmittance and haze of transparent plastics".

[0216] (4) Tensile strength performance test: The test was carried out in accordance with the standard requirements of GB / T 1040.3 "Determination of tensile properties of plastics (Part 3: Test conditions for films and sheets)".

[0217] (5) Product appearance performance test: Visual inspection method.

[0218] It can be concluded from the test results in Table 1:

[0219] It can be seen that compared with the biaxially oriented polyamide film produced by the traditional method, the flame - retardant and matting polyamide film provided by the present invention not only has outstanding flame - retardant performance, but also has low glossiness, high transparency, large haze, and excellent matting function; and it has excellent tensile strength and can meet the needs of the markets such as lithium - ion battery packaging and electronic product packaging.

[0220] Based on the above, the flame - retardant and matting polyamide film provided by the present invention has the following technical effects:

[0221] (1) The flame - retardant and matting polyamide film provided by the present invention has wide uses, strong applicability, and its production process is simple, easy to process, has high production efficiency, and is easy to realize industrial production;

[0222] (2) The product appearance of the flame - retardant and matting polyamide film provided by the present invention is delicate, without particle feeling, and does not affect transparency;

[0223] (3) In the flame-retardant and matting polyamide film provided by the present invention, the first flame retardant added to the coating solution has a matting function by itself and an excellent matting function. Therefore, the secondary addition of a matting agent can be avoided, effectively reducing the preparation cost of the film;

[0224] (4) The flame-retardant and matting polyamide film provided by the present invention adopts a multi-layer flame-retardant design structure, has outstanding flame-retardant performance, and constructs three flame-retardant defense lines for the film; and the second flame retardant in the middle layer 10 of the polyamide film substrate is selected from the compounding of different types of flame retardants, having a multi-component synergistic effect and avoiding the flame-retardant defects of a single material;

[0225] (5) The flame-retardant and matting polyamide film provided by the present invention uses polyamide as the matrix, and other raw material components and additives are easy to obtain and have a small addition amount, giving the product a competitive advantage;

[0226] In summary, through the special film layer structure design, formula combination and their synergistic effects, the present invention obtains a flame-retardant and matting polyamide film with excellent flame retardancy, high strength and good transparency. The flame-retardant and matting polyamide film not only has excellent flame-retardant performance and outstanding matting performance, with a soft visual effect, but also has characteristics such as high transparency and large tensile strength. The functional layers of the film cooperate with each other and coordinate to form an inseparable organic whole, providing a biaxially stretched polyamide film with flame retardancy, high strength and good transparency, which can be widely used in various fields such as the packaging of lithium-ion batteries and electronic products, and has strong market competitiveness.

[0227] It should be noted that the specific parameters or some common reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of the present invention, rather than limitations thereto; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0228] In addition, unless otherwise specified, the raw materials used can also be conventional commercially available products in the art or prepared by conventional methods in the art.

[0229] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved only in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation to the claim.

[0230] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flame-retardant and matting polyamide film, characterized in that: Its film structure from top to bottom successively includes a flame-retardant and matting upper surface layer, a polyamide film substrate intermediate layer, and a flame-retardant and matting lower surface layer; The flame-retardant and matting upper surface layer and the flame-retardant and matting lower surface layer are formed by respectively coating a coating solution on the upper surface and the lower surface of the polyamide film substrate intermediate layer; the coating solution includes an adhesive, a first flame retardant, and a solvent; in the coating solution, the weight ratio of the adhesive, the first flame retardant, and the solvent is (10-50):(1-20):(30-89); The polyamide film substrate intermediate layer includes a first surface layer, a second surface layer, and a core layer between the first surface layer and the second surface layer; By weight, the core layer includes 1-15 parts of a second flame retardant and 85-99 parts of polyamide; the first surface layer includes 1-10 parts of an anti-sticking masterbatch and 90-99 parts of polyamide; the second surface layer includes 1-10 parts of an anti-sticking masterbatch and 90-99 parts of polyamide; The first flame retardant is an organic phosphite; the second flame retardant includes hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphonate); the weight ratio of hexachlorocyclotriphosphazene, melamine cyanurate, and aluminum 3-ethylenebis(ethylphosphonate) is (20-40):(10-30):(30-70).

2. The flame-retardant and matting polyamide film according to claim 1, wherein: The polyamide film substrate intermediate layer is a three-layer co-extruded biaxially oriented polyamide film composed of a first surface layer, a core layer, and a second surface layer, and the first surface layer and the second surface layer are corona-treated.

3. The flame-retardant and matting polyamide film according to claim 1, wherein: The particle size D of the first flame retardant 50 ≤ 1.5 μm, and its particle size D 95 ≤ 3.5 μm, and its phosphorus content ≥ 23%; The particle size D of the second flame retardant 50 ≤ 2.0 μm.

4. The flame-retardant and matting polyamide film according to claim 1, wherein: The adhesive includes a main agent and a curing agent, and the weight ratio of the main agent to the curing agent is (90-99):(1-10).

5. The flame-retardant and matting polyamide film according to claim 4, wherein: The main agent includes polyurethane and acrylate, and the weight ratio of polyurethane to acrylate is (40-80):(20-60); the curing agent is polymethylene polyphenyl isocyanate; The solvent includes ethyl acetate and isopropyl alcohol, and the weight ratio of ethyl acetate to isopropyl alcohol is (30-80):(20-70).

6. The flame-retardant and matting polyamide film according to claim 2, wherein: The anti-sticking masterbatch is a composition of polyamide and additives, and the additives are one or more combinations of a lubricant, an antiblocking agent, and an antioxidant; The polyamide is one or more combinations of nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 1010, nylon 1212, nylon MXD6, nylon 6I, nylon 5T, nylon 6T, nylon 9T, nylon 10T; 7. The flame-retardant and matting polyamide film according to claim 1, wherein: The thickness of the polyamide film substrate intermediate layer is 10-60 μm, wherein the thicknesses of the first surface layer and the second surface layer are both 1-6 μm, and the thickness of the core layer is 8-48 μm.

8. The flame-retardant and dull polyamide film according to claim 5, wherein: The preparation method of the coating solution includes the following steps: S1. Add different raw material components of the main agent and the solvent into a container according to a certain weight ratio and stir evenly to obtain a mixture L; S2. Add the first flame retardant into the mixture L and mix evenly to obtain a mixture M; S3. Add the curing agent into the mixture M and mix evenly to obtain a mixture N; S4. Perform negative pressure filtration on the mixture N obtained in S3 to obtain the coating solution.

9. A method for preparing a flame-retardant and dull polyamide film according to any one of claims 1-8, characterized in that, Include the following steps: S100 Preparation of anti-sticking masterbatch: According to the anti-sticking masterbatch formula, polyamide and additives are mixed in a certain weight ratio, and then melt-blended, extruded, pelletized and cut into anti-sticking masterbatch through a twin-screw extruder; S200 Preparation of core layer material: According to the raw material ratio required for the core layer, polyamide and the second flame retardant are mixed evenly in a certain weight ratio, and then melt-blended, extruded, pelletized and cut into core layer material through a twin-screw extruder; S300: The materials for the first surface layer, the materials for the second surface layer and the core layer material are respectively put into different extruders, and then melt-plasticized and extruded through their respective extruders at a temperature of 240°C to 295°C, and the melt flows out through a T-shaped die head; S400: Use an air knife to attach the melt to a cold drum to form a thick sheet; S500: Immerse the thick sheet in water for pretreatment; S600: After heating the thick sheet, perform synchronous biaxial stretching to form a film; S700: Perform heat setting treatment on the stretched film, and then perform cooling and double-sided corona post-treatment on the film to obtain a biaxially stretched polyamide film; S800: Cut the biaxially stretched polyamide film as required to obtain the intermediate layer of the polyamide film substrate; S900: The upper surface and the lower surface of the intermediate layer of the polyamide film substrate are both coated with the coating liquid, the coating thickness is 0.5 - 5μm, after drying at 70°C - 120°C, and cured at 40 - 65°C for 24h - 72h.

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