High-tenacity flame-retardant nylon film and method of making same

Abstract

The application discloses a high-toughness flame-retardant nylon film, which comprises a substrate layer and a flame-retardant coating layer, the substrate layer comprises a surface layer 1, a core layer and a surface layer 2 in sequence, the flame-retardant coating layer is coated on at least one surface of the surface layer 1 and the surface layer 2, and the surface layer 1 and the surface layer 2 are composed of the following raw materials in percentage by mass: nylon 68-85%, flame-retardant master batch I 15-30%, anti-blocking agent 0-1% and slip agent 0-1%; the flame-retardant master batch I is composed of nylon and a reactive flame retardant; the core layer is composed of the following raw materials in percentage by mass: nylon 45-70%, toughening agent 15-25% and flame-retardant master batch II 15-30%; the flame-retardant master batch II is composed of nylon and an additive flame retardant; the flame-retardant structure of the substrate plus the coating layer is adopted, the flame retardancy of the nylon film is improved through multi-layer distribution, the reactive flame retardant is adopted in the surface layer and the additive flame retardant is adopted in the core layer, the flame-retardant effect of the nylon film is greatly improved, and the flame-retardant effect is more persistent without affecting the transparency and mechanical properties of the nylon film.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nylon film, and particularly relates to a high-toughness flame-retardant nylon film and a preparation method thereof. BACKGROUND

[0002] The biaxially stretched nylon film has the advantages of large tensile strength, high barrier property and chemical solvent resistance, and is widely applied to many industries such as food packaging, electronic packaging and medical packaging. The aluminum-plastic film is a key material for soft-pack lithium battery packaging, and a typical film layer structure thereof is: a biaxially stretched nylon layer, an adhesive layer, an aluminum layer, a special adhesive layer and a cast polypropylene layer. In the structure, the biaxially stretched nylon layer is very important, and the biaxially stretched nylon film constituting the layer has complex material properties, difficult process control, high equipment requirements, and is greatly influenced by process optimization and long debugging time, and is difficult to develop.

[0003] With the improvement of economy and development and technology, higher requirements are put forward for the biaxially stretched nylon film. In order to prevent the lithium battery and electronic product from being subjected to strong impact, extrusion or drop during use or transportation, the film is required to have better toughness to improve the punching capacity of the aluminum-plastic film, protect the damage of the aluminum foil layer, and the biaxially stretched nylon film is required to have flame-retardant capacity to prevent the soft-pack lithium ion battery from causing combustion under abnormal conditions such as short circuit, and further cause fire. The oxygen index of nylon is about 24.5, which can only reach the UL94V-2 level, and basically cannot reach the application standard of lithium battery and electronic product.

[0004] The prior art, such as Chinese patent CN116535720A, discloses a flame-retardant polyester film and a preparation method thereof. In view of the problem that the PET polyester film used for electronic product protective film does not have flame retardance, the invention provides a flame-retardant polyester film, which comprises a polyester substrate and a transparent flame-retardant coating on the surface of the polyester substrate. The invention greatly improves the flame retardance of the film by coating a flame-retardant coating on the surface of the substrate, but the flame retardance of the substrate used in the invention is poor. For example, Chinese patent CN109808270A discloses a flame-retardant antistatic nylon film and a preparation method thereof. The flame-retardant antistatic nylon film comprises an upper surface layer, a middle layer and a lower surface layer in sequence. At least one surface of the upper surface layer and the lower surface layer is coated with an antistatic agent coating. According to the mass percentage, the upper surface layer comprises 62%-84% of nylon, 1%-18% of additives and 15%-20% of flame-retardant masterbatch. The core layer comprises 47%-69% of nylon, 1%-18% of additives and 30%-35% of flame-retardant masterbatch. The lower surface layer comprises 62%-84% of nylon, 1%-18% of additives and 15%-20% of flame-retardant masterbatch. The invention uses flame-retardant masterbatch as the upper and lower surface layers, so that the biaxially stretched nylon film product has excellent antistatic effect on the basis of ensuring good flame retardance. However, the invention only adds flame retardant to the flame-retardant masterbatch in the upper surface layer, core layer and lower surface layer to make the film meet the specified flame retardance level, and the compatibility of the added flame retardant with nylon is poor. A large amount of addition will affect the mechanical properties and transparency of the film. SUMMARY

[0005] To solve the problems existing in the prior art, the present application provides a high-toughness flame-retardant nylon film, which can improve the flame retardance of the nylon film without affecting the transparency and mechanical properties of the nylon film, and make the flame retardant effect more durable.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] A high-toughness flame-retardant nylon film, comprising a substrate layer and a flame-retardant coating, wherein the substrate layer comprises a surface layer 1, a core layer and a surface layer 2 in sequence; and the flame-retardant coating is coated on at least one surface of the surface layer 1 and the surface layer 2;

[0008] The surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage: 68%-85% of nylon, 15%-30% of flame-retardant masterbatch I, 0%-1% of anti-blocking agent and 0%-1% of slip agent; and the flame-retardant masterbatch I is composed of nylon and a reactive flame retardant.

[0009] The core layer is composed of the following raw materials in mass percentage: 45%-70% of nylon, 15%-25% of toughening agent and 15%-30% of flame-retardant masterbatch II; and the flame-retardant masterbatch II is composed of nylon and an additive flame retardant.

[0010] Further, the reactive flame retardant accounts for 2.5%-5% of the total mass of the flame-retardant master batch I; the reactive flame retardant is at least one of bis(hydroxyethyl) methyl phosphine oxide, 1,3,62 tri(4,62 diaminosulfide triazine) hexane, and cyanuric acid.

[0011] Further, the additive flame retardant accounts for 2.5%-5% of the total mass of the flame-retardant master batch II; the additive flame retardant is obtained by mixing a monomolecular intumescent flame retardant and an inorganic nano flame retardant in a ratio of (1-3):(0.5-1); the monomolecular intumescent flame retardant is prepared by reacting p-aminobenzenesulfonic acid and ammonium polyphosphate; the inorganic nano flame retardant is at least one of halloysite, carbon nanotubes, and multiple layered silicate particles.

[0012] Further, the flame-retardant coating is a water-based polyurethane flame-retardant nanocomposite coating with a solid content of 10-20%.

[0013] Further, the preparation method of the water-based polyurethane flame-retardant nanocomposite coating is as follows: 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer is used as a chain extender to prepare an azide group functionalized polyurethane, which is then prepared by Click reaction with at least one of azide-modified nanomontmorillonite, halloysite, graphene, aluminum hydroxide, and magnesium hydroxide.

[0014] Further, the anti-blocking agent is at least one of silicon dioxide, talcum powder, and silicone.

[0015] Further, the slip agent is at least one of erucic acid amide, oleic acid amide, polyethylene wax, and silicone oil.

[0016] Further, the toughening agent is at least one of long-chain carbon nylon, copolymer nylon, and nylon elastomer.

[0017] Further, the substrate layer has a thickness of 15-30 μm, the surface layer 1 and the surface layer 2 each have a thickness of 2-3 μm, and the flame-retardant coating has a thickness of 0.5-3 μm.

[0018] A preparation method of a high-toughness flame-retardant nylon film includes the following steps:

[0019] S1: The raw materials of the surface layer 1, the core layer, and the surface layer 2 are respectively added to three extruders in a set mass ratio, melted, plasticized, and extruded at 230-270°C, and then uniformly discharged through a T-shaped die to form a molten thick sheet, which is then cooled and solidified into a cast thick sheet by a quenching roller and a high-pressure air knife at 15-35°C.

[0020] S2: after water treatment, the cast thick sheet is synchronously bidirectionally stretched by using a magnetic suspension linear motor, the stretching temperature is 130-200 DEG C, and the stretching ratio is 2.8*2.8-3.4*3.4;

[0021] S3: the stretched film is subjected to heat setting treatment, the setting temperature is 160-210 DEG C, and the setting time is 5-30 s;

[0022] S4: the surface of at least one surface layer of the set film is subjected to corona treatment, is wound, is slitted into finished products, and a base material layer is obtained;

[0023] S5: a layer of water-based polyurethane flame-retardant nano composite material coating is coated on the corona surface of the base material film, is dried by an oven, is wound, is aged at 50 DEG C for 24 h, and a high-toughness flame-retardant nylon film is obtained.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] 1: the high-toughness flame-retardant nylon film provided by the application adopts a flame-retardant structure of base material plus coating, the base material layer comprises surface layers and a core layer in a sandwich structure, different flame retardants are added in different layers according to the level requirements and properties of the layers, which not only avoids the problems of mechanical property reduction, transparency reduction and difficult processing caused by adding a large amount of flame retardants in the film to improve the barrier property, but also greatly improves the flame retardancy of the nylon film; the reactive flame retardant is added in the surface layer 1 and the surface layer 2, the reactive flame retardant has small toxicity, good flame-retardant effect, long-lasting flame retardancy, and small influence on the transparency of the prepared film material, and the cost can be saved by adding it only in the surface layer; the additive flame retardant is used in the core layer, the additive flame retardant has a greater influence on the material, but it is convenient to use and widely applicable, and adding it together with the toughening agent in the core layer can enhance the toughness of the film and improve the flame retardancy; the application greatly improves the flame-retardant effect of the nylon film, and can make the flame-retardant effect more persistent without affecting the transparency and mechanical properties of the nylon film.

[0026] 2: in the application, the reactive flame retardant accounts for 2.5%-5% of the total mass of the flame-retardant master batch I, which can ensure the flame-retardant effect of the nylon film while reducing the influence on other properties of the material as much as possible; the reactive flame retardant used is at least one of bis(hydroxyethyl) methyl phosphine oxide, 1,3,62 tri(4,62 diaminobenzene) 222 sulfide triazine) hexane and cyanuric acid, which can improve the thermal stability of the material, reduce the generation of thermal decomposition and degradation products, prolong the service life of the material, and has little influence on the mechanical properties of the material, so that the original properties of the material can be maintained as much as possible.

[0027] 3. In this invention, the additive flame retardant accounts for 2.5%-5% of the total mass of the flame retardant masterbatch II, which can minimize the impact on other properties of the material while ensuring the flame retardant effect of the nylon film. The additive flame retardant used is a mixture of monomolecular intumescent flame retardant and inorganic nano flame retardant in a ratio of (1-3):(0.5-1). Monomolecular intumescent flame retardant generally inhibits combustion by releasing non-flammable gases through decomposition, while inorganic nano flame retardant can form a barrier layer to prevent heat conduction and flame spread. By combining the two in the most appropriate ratio, they work synergistically. It can provide a more efficient combustion suppression effect; the single-molecule intumescent flame retardant used is prepared by reacting p-aminobenzenesulfonic acid and ammonium polyphosphate. The reaction is relatively simple, and the raw materials are relatively common and the cost is low; the halloysite, carbon nanotubes, and various layered silicate particles used are non-toxic and non-polluting. They will not have a negative impact on the environment and human health during use. Moreover, these inorganic nano flame retardants have a high specific surface area and a small particle size. When they are dispersed in the material matrix, they can effectively improve the mechanical properties and thermal stability of the material.

[0028] 4. The flame-retardant coating in this invention is a water-based polyurethane flame-retardant nanocomposite coating. The water-based polyurethane flame-retardant nanocomposite coating has the advantages of high flame-retardant performance, environmental friendliness, low VOC emissions, excellent physical properties and convenient processing and construction. The coating with a solid content of 10-20% can achieve the best flame-retardant effect and physical properties, meet the requirements of different application environments, ensure the uniformity and adhesion of the coating, and enhance the flexibility and wear resistance of the coating.

[0029] 5. The preparation method of the waterborne polyurethane flame-retardant nanocomposite coating in this invention is as follows: 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer is used as a chain extender to prepare terminal alkyne-functionalized polyurethane, which is then reacted with at least one of azide-modified nano-montmorillonite, halloysite, graphene, aluminum hydroxide, and magnesium hydroxide via a Click reaction. The synthesis of terminal alkyne-functionalized polyurethane can be achieved in a single step. Furthermore, the reaction between the functionalized polyurethane and nanomaterials via the Click reaction is relatively mild and simple, and the preparation process is highly efficient. It can achieve good interfacial compatibility, which helps to achieve uniform dispersion and strengthening effect of nanomaterials in the coating, thereby improving the flame retardant performance and physical and mechanical properties of the coating.

[0030] 6. The anti-blocking agent in this invention is at least one of silica, talc, and organosilicon. Silica, talc, and organosilicon have good chemical stability and are not prone to reacting with other compounds. They can maintain the chemical stability and physical properties of the nylon film and can form a thin film on the substrate surface to act as an isolation layer, reducing the adhesion between the nylon film and other substances. Silica and talc have good wear resistance, which can increase the hardness and wear resistance of the substrate surface. Organosilicon anti-blocking agents have good thermal stability and high temperature resistance, and can withstand high working temperatures, enabling the nylon film to maintain its good performance when used in high-temperature environments.

[0031] 7. The slip agent in this invention is at least one of erucamide, oleamide, polyethylene wax, and organosilicon oil. These slip agents have good chemical stability, are not prone to reacting with other substances, and can form a lubricating film on the surface of the nylon film, reducing friction when in contact with other materials. This helps to reduce the coefficient of friction between the nylon film and other objects, making its surface smoother and reducing friction loss.

[0032] 8. In this invention, the toughening agent is at least one of long-chain nylon, copolymer nylon, and nylon elastomer. These toughening agents are easily compatible with the substrate of the nylon film, and the content and ratio of the toughening agent can be easily adjusted. They can also improve the toughness and ductility of the nylon film, giving it better tensile and bending properties. Furthermore, they can improve the impact strength and impact resistance of the nylon film, enabling it to effectively buffer and disperse impact energy when subjected to impact or external force, preventing the film from cracking and being damaged.

[0033] 9. In this invention, the thickness of the substrate layer is 15-30 μm, the thickness of surface layer 1 and surface layer 2 is 2-3 μm, and the thickness of the flame-retardant coating is 0.5-3 μm. The thinner substrate layer can provide lower material costs and make the nylon film lighter and more flexible. Controlling the thickness of surface layer 1 and surface layer 2 within the range of 2-3 μm can obtain better appearance and smoothness. Choosing a flame-retardant coating thickness of 0.5-3 μm can minimize the impact on the overall film performance while meeting the flame-retardant requirements.

[0034] 10. In this invention, by simultaneously biaxially stretching in step S2 and heat-setting in step S3 to prepare a high-toughness flame-retardant nylon film, the nylon film molecules are arranged in an orderly manner to form a denser structure, thereby giving the film higher toughness. Using a water-based polyurethane flame-retardant nanocomposite coating to treat the base layer for flame retardancy can effectively improve the flame retardant performance of the nylon film. This method has a simple preparation process, strong controllability, and can adapt to different application scenarios and requirements, realizing the customization of film performance. Attached Figure Description

[0035] Figure 1 A schematic diagram of the structure of a high-toughness flame-retardant nylon film provided by the present invention;

[0036] Figure 2 The flowchart illustrates a method for preparing a high-toughness flame-retardant nylon film provided by this invention.

[0037] Among them, 100 is the substrate layer; 101 is the surface layer 1; 102 is the core layer; 103 is the surface layer 2; and 200 is the flame-retardant coating. Detailed Implementation

[0038] The following describes a preferred embodiment, with reference to the appendix. Figures 1-2 To further illustrate the present invention, the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values; for numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed herein; the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified; the experimental methods in the following embodiments are conventional methods unless otherwise specified.

[0039] Example 1

[0040] This embodiment provides a high-toughness flame-retardant nylon film, such as Figure 1 As shown, it includes a substrate layer 100 and a flame-retardant coating 200. The substrate layer 100 sequentially includes a sandwich structure of a surface layer 1 101, a core layer 102, and a surface layer 2 103. The flame-retardant coating 200 is applied to at least one side of the surface of the surface layer 1 101 and the surface layer 2 103.

[0041] The surface layer 1 101 and surface layer 2 103 are composed of the following raw materials by weight percentage:

[0042] Table 1 Components of Surface Layer 1 and Surface Layer 2

[0043] Nylon 83％ Flame retardant masterbatch I 15％ Silica 1％ Euricamide 1％

[0044] The flame retardant masterbatch I is composed of nylon and a reactive flame retardant. The reactive flame retardant grafts or bonds flame retardant groups onto or onto the surface of the nylon molecular chain through a polycondensation reaction. The reactive flame retardant accounts for 5% of the total mass of the flame retardant masterbatch I, in order to ensure the flame retardant effect of the nylon film while minimizing the impact on other properties of the material. The reactive flame retardant is bis(hydroxyethyl)methylphosphine oxide.

[0045] The core layer 102 is composed of the following raw materials by weight percentage:

[0046] Table 2 core layer components

[0047] Nylon 70％ Copolymer nylon 15％ Flame retardant masterbatch II 15％

[0048] The flame-retardant masterbatch II is composed of nylon and an additive flame retardant; the additive flame retardant accounts for 5% of the total mass of the flame-retardant masterbatch II; the monomolecular intumescent flame retardant inhibits combustion by decomposing and releasing non-flammable gas, and the inorganic nano flame retardant prevents heat conduction and flame spread by forming a barrier layer; the two are mixed in a ratio of 1:0.5 to synergistically provide a more efficient combustion inhibition effect for the film; the monomolecular intumescent flame retardant is prepared by a simple reaction of the more common p-aminobenzenesulfonic acid and ammonium polyphosphate; the inorganic nano flame retardant is nano-montmorillonite particles with a high specific surface area and small particle size; and the copolymer nylon is a ternary copolymer of PA6 / 66 / 12.

[0049] The flame-retardant coating 200 is a waterborne polyurethane flame-retardant nanocomposite coating with high-efficiency flame-retardant performance and environmental friendliness, and has a solid content of 15% to achieve optimal flame-retardant effect and physical properties; the preparation method of the waterborne polyurethane flame-retardant nanocomposite coating is as follows: 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer is used as a chain extender to prepare an azide group functionalized polyurethane, which is then prepared with azide group modified nano-montmorillonite, halloysite, and magnesium hydroxide through an efficient Click reaction.

[0050] The embodiment also provides a preparation method of the high-toughness flame-retardant nylon film, which comprises the following steps:

[0051] S1: raw materials of the surface layer 1 101, the core layer 102, and the surface layer 2 103 are respectively added into three extruders in a set mass ratio, and are melted, plasticized, and extruded at 260℃, and then uniformly flow out through a T-shaped die to form a molten thick sheet, which is then cooled and solidified into a cast thick sheet by the action of a 30℃ chilling roller and a high-pressure air knife;

[0052] S2: the cast thick sheet is subjected to synchronous bidirectional stretching by using a magnetic levitation linear motor after water treatment, and the stretching temperature is 180℃ and the stretching ratio is 3.1x3.1;

[0053] S3: the stretched film is subjected to heat setting treatment to make the nylon film molecules orderly arranged to form a more compact structure, and the setting temperature is 200℃ and the setting time is 15s;

[0054] S4: the surface of at least one surface layer of the set film is subjected to corona treatment, and then wound up and slitted into finished products to obtain the base layer 100;

[0055] S5: coating a layer of water-based polyurethane flame-retardant nanocomposite coating on the substrate film, drying in an oven, winding, and curing at 50℃ for 24h to obtain a high-toughness flame-retardant nylon film.

[0056] The high-toughness flame-retardant nylon film prepared according to the above method has a substrate layer 100 with a thickness of 15μm, a surface layer 1 101 and a surface layer 2 103 each with a thickness of 2μm, a core layer 102 with a thickness of 11μm, and a flame-retardant coating layer 200 with a thickness of 1μm.

[0057] Example 2

[0058] This example provides a high-toughness flame-retardant nylon film, which has the same specific structure as that of Example 1, except that the raw material combination of the substrate layer and the flame-retardant layer is different.

[0059] The surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage:

[0060] Table 3: Components of the surface layer 1 and the surface layer 2

[0061] Nylon 75％ Flame retardant masterbatch I 23％ Talc 1％ Oleamide 1％

[0062] The flame-retardant masterbatch I is composed of nylon and a reactive flame-retardant agent, which is grafted or bonded to the flame-retardant groups on the nylon molecular chain or surface through condensation polymerization; the reactive flame-retardant agent accounts for 2.5% of the total mass of the flame-retardant masterbatch I; and the reactive flame-retardant agent is cyanuric acid.

[0063] The core layer is composed of the following raw materials in mass percentage:

[0064] Table 4: Components of the core layer

[0065] Nylon 57％ Long chain nylon 20％ Flame retardant masterbatch II 23％

[0066] The flame-retardant masterbatch II is composed of nylon and an additive flame-retardant agent; the additive flame-retardant agent accounts for 2.5% of the total mass of the flame-retardant masterbatch II; the additive flame-retardant agent is a mixture of a monomolecular intumescent flame-retardant agent and an inorganic nanometer flame-retardant agent in a ratio of 3:1; the monomolecular intumescent flame-retardant agent is prepared by the reaction of p-aminobenzenesulfonic acid and ammonium polyphosphate; and the inorganic nanometer flame-retardant agent is halloysite.

[0067] The flame-retardant coating layer is a water-based polyurethane flame-retardant nanocomposite coating layer with a solid content of 10%; and the preparation method of the water-based polyurethane flame-retardant nanocomposite coating layer is as follows: 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer is used as a chain extender to prepare an azide group-modified nanometer montmorillonite, graphene, and aluminum hydroxide through a Click reaction.

[0068] The embodiment also provides a preparation method of the high-toughness flame-retardant nylon film, comprising the following steps:

[0069] S1: raw materials of the surface layer 1, the core layer and the surface layer 2 are respectively added into three extruders according to a set mass ratio, and are melted, plasticized and extruded at 230 DEG C, and then are cooled and solidified into a casting thick sheet through the action of a 15 DEG C chilling roller and a high-pressure air knife after being uniformly discharged from a T-shaped die;

[0070] S2: the casting thick sheet is subjected to synchronous bidirectional stretching through a magnetic suspension linear motor after being treated by water, and the stretching temperature is 130 DEG C and the stretching ratio is 2.8x2.8;

[0071] S3: the film after stretching is subjected to heat setting treatment, and the setting temperature is 160 DEG C and the setting time is 30 s;

[0072] S4: the surface of at least one surface layer of the film after setting is subjected to corona treatment, and is wound and slitted into a finished product to obtain a base material layer;

[0073] S5: a layer of water-based polyurethane flame-retardant nanocomposite coating is coated on the corona surface of the base material film, and is dried through an oven, wound and aged at 50 DEG C for 24 h to obtain the high-toughness flame-retardant nylon film.

[0074] The base material layer of the high-toughness flame-retardant nylon film prepared according to the above method has a thickness of 20 μm, the surface layer 1 and the surface layer 2 each have a thickness of 2.5 μm, the core layer 102 has a thickness of 15 μm, and the flame-retardant coating layer has a thickness of 0.5 μm.

[0075] Embodiment 3

[0076] The embodiment provides a high-toughness flame-retardant nylon film, and the specific structure is the same as that of embodiment 1, and the difference lies in that the raw material combination of the base material layer and the flame-retardant layer is different.

[0077] The surface layer 1 and the surface layer 2 are composed of the following raw materials in percentage by mass:

[0078] Table 5 surface layer 1 and surface layer 2 components

[0079] Nylon 68％ Flame retardant masterbatch I 30％ Silicone 1％ Polyethylene wax 1％

[0080] The flame-retardant master batch I is composed of nylon and a reactive flame retardant, and the flame-retardant groups are grafted or bonded on the nylon molecular chain or the surface through a polycondensation reaction; the reactive flame retardant accounts for 3% of the total mass of the flame-retardant master batch I; and the reactive flame retardant is 1,3,62 tri (4,62 diaminobenzene) 222 sulfenyl triazine) hexane;

[0081] The core layer is composed of the following raw materials in percentage by mass:

[0082] Table 6 core layer components

[0083] Nylon 45％ Nylon elastomer 25％ Flame retardant masterbatch II 30％

[0084] The flame-retardant masterbatch II is composed of nylon and an additive flame retardant; the additive flame retardant accounts for 3% of the total mass of the flame-retardant masterbatch II; the additive flame retardant is a mixture of monomolecular intumescent flame retardant and inorganic nano flame retardant in a ratio of 2:0.75; the monomolecular intumescent flame retardant is prepared by reacting p-aminobenzenesulfonic acid and ammonium polyphosphate; and the inorganic nano flame retardant is carbon nanotube.

[0085] The flame-retardant coating is a water-based polyurethane flame-retardant nanocomposite coating with a solid content of 20%; and the preparation method of the water-based polyurethane flame-retardant nanocomposite coating is as follows: 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer is used as a chain extender to prepare an azide group functionalized polyurethane, which is then prepared by Click reaction with azide group modified halloysite and magnesium hydroxide.

[0086] The embodiment also provides a preparation method of the high-toughness flame-retardant nylon film, which comprises the following steps:

[0087] S1: raw materials of the surface layer 1, the core layer and the surface layer 2 are respectively added into three extruders according to a set mass ratio, and are melted, plasticized and extruded at 250 DEG C, and then are uniformly discharged from a T-shaped die to form a molten thick sheet, which is then cooled and solidified into a cast thick sheet by the action of a 35 DEG C chilling roller and a high-pressure air knife;

[0088] S2: the cast thick sheet is subjected to synchronous bidirectional stretching by using a magnetic suspension linear motor after water treatment, and the stretching temperature is 200 DEG C and the stretching ratio is 3.4*3.4;

[0089] S3: the film after stretching is subjected to heat setting treatment, and the setting temperature is 210 DEG C and the setting time is 5 s;

[0090] S4: the surface of at least one surface layer of the film after setting is subjected to corona treatment, and then is wound and slitted into a finished product to obtain a base layer;

[0091] S5: a layer of water-based polyurethane flame-retardant nanocomposite coating is coated on the corona-treated surface of the base film, and then is dried by using an oven, wound and aged at 50 DEG C for 24 h to obtain a high-toughness flame-retardant nylon film.

[0092] The base layer of the high-toughness flame-retardant nylon film prepared according to the above method has a thickness of 30 μm, the surface layer 1 and the surface layer 2 each have a thickness of 3 μm, the core layer 102 has a thickness of 24 μm, and the flame-retardant coating has a thickness of 3 μm.

[0093] In addition, the reactive flame retardant in the application can also be selected from several combinations of bis(hydroxyethyl) methyl phosphine oxide, 1,3,62 tri(4,62 diaminosulfide triazine) hexane, cyanuric acid; the inorganic nano flame retardant can also be selected from several combinations of halloysite, carbon nanotubes, various layered silicate particles; the anti-blocking agent can also be selected from several combinations of silicon dioxide, talc powder, silicone; the slip agent can also be selected from several combinations of erucic acid amide, oleic acid amide, polyethylene wax, silicone oil; the toughening agent can also be selected from several combinations of long carbon chain nylon, copolymerized nylon, and nylon elastomer.

[0094] Comparative Example 1

[0095] The difference from Example 1 is that:

[0096] In the substrate layer of the high-toughness flame-retardant nylon film, the surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage:

[0097] Table 7 Surface layer 1 and surface layer 2 components

[0098] Nylon 98％ Silica 1％ Euricamide 1％

[0099] The raw material of the core layer in the substrate layer is nylon.

[0100] Comparative Example 2

[0101] The difference from Comparative Example 1 is that:

[0102] In the substrate layer of the high-toughness flame-retardant nylon film, the core layer is composed of the following raw materials in mass percentage: nylon 80%, copolymerized nylon 20%; the copolymerized nylon is a ternary copolymer of PA6 / 66 / 12.

[0103] Comparative Example 3

[0104] The difference from Comparative Example 1 is that:

[0105] In the substrate layer of the high-toughness flame-retardant nylon film, the core layer is composed of the following raw materials in mass percentage:

[0106] Table 8 Core layer components

[0107] Nylon 57％ Copolymer nylon 20％ Flame retardant masterbatch II 23％

[0108] Comparative Example 4

[0109] The difference from Comparative Example 3 is that:

[0110] In the substrate layer of the high-toughness flame-retardant nylon film, the surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage:

[0111] Table 9 Surface layer 1 and surface layer 2 components

[0112] Nylon 75％ Flame retardant masterbatch I 23％ Silica 1％ Euricamide 1％

[0113] Comparative Example 5

[0114] Substantially the same as Example 1, but with the following changes:

[0115] The base layer of the high-toughness flame-retardant nylon film, the surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage:

[0116] Table 10 Surface layer 1 and surface layer 2 components

[0117] Nylon 88％ Flame retardant masterbatch I 10％ Silica 1％ Euricamide 1％

[0118] The core layer in the base layer is composed of the following raw materials in mass percentage:

[0119] Table 11 Core layer components

[0120] Nylon 80％ Copolymer nylon 10％ Flame retardant masterbatch II 10％

[0121] Comparative Example 6

[0122] Substantially the same as Example 1, but with the following changes:

[0123] The base layer of the high-toughness flame-retardant nylon film, the surface layer 1 and the surface layer 2 are composed of the following raw materials in mass percentage:

[0124] Table 12 Surface layer 1 and surface layer 2 components

[0125] Nylon 58％ Flame retardant masterbatch I 40％ Silica 1％ Euricamide 1％

[0126] The core layer in the base layer is composed of the following raw materials in mass percentage:

[0127] Table 13 Core layer components

[0128] Nylon 25％ Copolymer nylon 35％ Flame retardant masterbatch II 40％

[0129] Evaluation of implementation effect:

[0130] The following through specific tests on Examples 1-3 and Comparative Examples 1-6, further illustrate the excellent effects achieved by the present application:

[0131] Tensile strength, elongation at break, haze and light transmittance were tested in accordance with the standard GB / T 20218-2021 "biaxially oriented polyamide (nylon) film";

[0132] Punch forming performance test: the film sample was tested for 7mm punch forming, and the appearance of the film after punch forming was evaluated as excellent: marked as, good: marked as, and poor: marked as.

[0133] The flame retardant grade test adopts vertical burning, and is tested according to the ANSL-UL94-2009 standard;

[0134] The film-forming property is evaluated as excellent: marked with a star (☆), good: marked with a circle (○), and poor: marked with an X (×) according to the stability, thickness fluctuation and film-forming property during the production of the substrate film;

[0135] The specific result data is shown in the following table:

[0136] Table 14 test result statistics table

[0137]

[0138]

[0139] As can be seen from the above table, the high-toughness flame-retardant nylon film provided by the application has good mechanical properties, excellent flame retardancy, good transparency and molding processability;

[0140] As can be seen from the test results of Example 1 and Comparative Examples 1-4, the flame-retardant structure of the substrate plus the coating layer used in the application can improve the flame retardancy of the film;

[0141] As can be seen from the test results of Comparative Example 1 and Comparative Example 2, the addition of the toughening agent in the core layer can improve the toughness and strength of the film;

[0142] As can be seen from the test results of Comparative Examples 2-3 and Comparative Example 4, the use of the reactive flame retardant in the surface layer 1 and the surface layer 2 and the use of the additive flame retardant in the core layer can improve the flame retardancy of the film;

[0143] As can be seen from the test results of Example 1 and Comparative Examples 5-6, the ratio of the components of the raw materials of the surface layer 1, the surface layer 2 and the core layer provided by the application can make the flame-retardant effect more durable without affecting the transparency and mechanical properties of the film.

[0144] The above only describes the preferred embodiments of the application, and it should be noted that, for those skilled in the art, without departing from the inventive concept, several modifications and improvements can be made, which are all within the protection scope of the application.

Claims

1. A high-toughness flame-retardant nylon film, characterized in that, It includes a substrate layer and a flame-retardant coating, wherein the substrate layer comprises a surface layer 1, a core layer and a surface layer 2 in sequence; the flame-retardant coating is applied to at least one side of the surface of surface layer 1 and surface layer 2; The surface layer 1 and surface layer 2 are composed of the following raw materials by mass percentage: 68%-85% nylon, 15%-30% flame retardant masterbatch I, 0%-1% anti-blocking agent, and 0%-1% slip agent; the flame retardant masterbatch I is composed of nylon and reactive flame retardant. The core layer, by weight percentage, is composed of the following raw materials: 45%-70% nylon, 15%-25% toughening agent, and 15%-30% flame retardant masterbatch II; the flame retardant masterbatch II is composed of nylon and additive flame retardant. The reactive flame retardant accounts for 2.5%-5% of the total mass of flame retardant masterbatch I; the reactive flame retardant is at least one of bis(hydroxyethyl)methylphosphine oxide, 1,3,6,2-tris(4,6,2-diamino-2,2,2-thiotriazine)hexane, and cyanuric acid; The additive flame retardant accounts for 2.5%-5% of the total mass of flame retardant masterbatch II; the additive flame retardant is obtained by mixing a monomolecular intumescent flame retardant and an inorganic nano flame retardant in a ratio of (1-3):(0.5-1); the monomolecular intumescent flame retardant is prepared by reacting p-aminobenzenesulfonic acid and ammonium polyphosphate; the inorganic nano flame retardant is at least one of halloysite, carbon nanotubes, and various layered silicate particles; The flame-retardant coating is a water-based polyurethane flame-retardant nanocomposite coating with a solid content of 10-20%. The preparation method of the waterborne polyurethane flame-retardant nanocomposite coating is as follows: using 4,4'-dihydroxymethyl-1,4-heptadiyne functional monomer as a chain extender to prepare terminal alkyne functionalized polyurethane, and then preparing it by Click reaction with at least one of nano-montmorillonite modified with azide group, halloysite, graphene, aluminum hydroxide, and magnesium hydroxide. The toughening agent is at least one of long-chain nylon, copolymer nylon, and nylon elastomer.

2. The high-toughness flame-retardant nylon film according to claim 1, characterized in that, The anti-blocking agent is at least one of silica, talc, and organosilicon.

3. The high-toughness flame-retardant nylon film according to claim 1, characterized in that, The slip agent is at least one of erucamide, oleamide, polyethylene wax, and silicone oil.

4. The high-toughness flame-retardant nylon film according to claim 1, characterized in that, The thickness of the substrate layer is 15-30 μm, the thickness of surface layer 1 and surface layer 2 is 2-3 μm, and the thickness of the flame-retardant coating is 0.5-3 μm.

5. A method for preparing a high-toughness flame-retardant nylon film according to any one of claims 1-4, characterized in that, Includes the following steps: S1: The raw materials of surface layer 1, core layer and surface layer 2 are added to three extruders according to the set mass ratio. They are melted, plasticized and extruded at 230-270℃. After flowing out through the T-die to form a molten sheet, it is cooled and solidified into a cast sheet by the action of a 15-35℃ chilling roller and a high-pressure air knife. S2: After water treatment, the cast sheet is synchronously stretched in both directions using a magnetic levitation linear motor. The stretching temperature is 130-200℃ and the stretching ratio is 2.8×2.8-3.4×3.

4. S3: Heat set the stretched film at a temperature of 160-210℃ for 5-30 seconds. S4: Corona treatment is performed on the surface of at least one layer of the shaped film, and the film is wound up and slit into finished products to obtain the substrate layer; S5: A layer of water-based polyurethane flame-retardant nanocomposite material coating is coated on the corona-electrode surface of the substrate film, and then dried in an oven, rolled up, and cured at 50°C for 24 hours to obtain a high-toughness flame-retardant nylon film.

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