Preparation method of flame-retardant aluminum foil composite film

Abstract

The application provides a preparation method of a flame-retardant aluminum foil composite film, comprising the following steps: A, flame retardant pretreatment: superfine pulverization treatment is performed on flame retardant masterbatch, and then the flame retardant masterbatch is mixed with a surface treatment agent in proportion and is crushed in a micro-powder device; B, the pretreated flame retardant and film raw materials are put into a double-screw extruder, and are uniformly mixed in a molten state and are extruded and granulated; C, the granules are melted in a single-screw extruder, are extruded into a film forming device, and are formed into a film; and D, the film is fixed on a coating machine, a silica gel layer is coated, and then one side coated with the silica gel is attached to an aluminum foil and is hot-pressed to prepare the aluminum foil composite film.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation materials technology, specifically relating to a method for preparing a flame-retardant aluminum foil composite film. Background Technology

[0002] Traditional halogenated flame retardants are facing restrictions due to environmental and health concerns, prompting the industry to develop environmentally friendly flame retardant materials such as halogen-free and bio-based products. In addition to its traditional applications in packaging and construction, flame-retardant aluminum foil composite films are also attracting significant attention for their use in high-end fields such as new energy vehicle battery packaging.

[0003] Current flame-retardant aluminum foil composite films are produced by blending and modifying the plastic base film with halogen-free flame-retardant masterbatch and adding flame retardants to the composite adhesive. However, the addition of large amounts of flame retardants may lead to a decrease in the adhesion between the plastic film layer and the aluminum foil; the adhesives used in traditional lamination may themselves be flammable, and uneven coating can create penetration channels, affecting barrier properties and making the adhesive a weak point; due to the hard and brittle nature of the aluminum foil, it is prone to pinholes and creases, resulting in a sharp decrease in gas barrier properties; and the plastic base film, as the support layer, may burn through the entire film and spread, affecting the overall flame-retardant effect.

[0004] Invention patent 202010205928.9 discloses a flame-retardant plastic film, mainly composed of polyethylene, with the addition of an ethylene-vinyl acetate copolymer material that has self-extinguishing properties, enabling the material to automatically extinguish after being removed from the flame source. Simultaneously, flame-retardant masterbatch is added to ensure the material's flame-retardant characteristics. However, the flame retardant in this patent is not well compatible with the copolymer material, resulting in poor flame-retardant performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a flame-retardant aluminum foil composite film.

[0006] To achieve the objectives of this invention, the technical solution adopted is as follows: A method for preparing a flame-retardant aluminum foil composite film includes the following steps: A. Flame retardant pretreatment: The flame retardant masterbatch is subjected to ultrafine pulverization treatment, and then mixed with the surface treatment agent in proportion and fed into the micro-powdering equipment for crushing; during the powder crushing process, the surface treatment agent can fully coat the flame retardant particles.

[0007] B. The pretreated flame retardant and film raw material are fed into a twin-screw extruder, thoroughly mixed in the molten state, and then extruded and granulated. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to make a film; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

[0008] In order to enable the flame retardant to be better compatible with the film material and not to precipitate out and affect the flame retardant effect, the present invention first micronizes the flame retardant to reduce the dissolution resistance caused by particle size, and then performs surface activation so that the flame retardant particles are fully coated by the surface treatment agent, thereby enabling the flame retardant to better enter the material space and achieve a miscible effect.

[0009] The flame retardant described in this invention is selected from one or more of phosphorus-nitrogen flame retardants, magnesium hydroxide, aluminum hydroxide, polyphosphoric acid flame retardants, antimony trioxide, and organosilicon flame retardants.

[0010] The surface treatment agent of this invention, by weight, comprises: 0.5-3 parts dispersant, 3-8 parts polyethylene glycol, 1-5 parts silane coupling agent, and 2-8 parts surfactant. There is a synergistic effect among the components. The interaction between the silane coupling agent and the surfactant allows the flame retardant to be better incorporated into the membrane material. The dispersant, polyethylene glycol, and surfactant are all selected from raw materials with large molecular weights and high melting points, further enhancing the compatibility between the surface treatment agents. This improves both the compatibility of the flame retardant and the membrane material, as well as processing stability and weather resistance.

[0011] Preferably, the dispersant is ethylene bis-stearamide or microcrystalline wax.

[0012] Microcrystalline wax is pure white in color, which does not affect the color adjustment during film formation. It also has a high melting point, high stability during high-temperature processing, good adhesion and ductility, and is not prone to becoming brittle under low-temperature conditions.

[0013] Preferably, the surfactant is one or more of sodium secondary alkyl sulfonate, sodium methyl stearate sulfonate, and sodium dodecylbenzene sulfonate. The selected surfactant has a large molecular weight, resulting in better stability and compatibility.

[0014] The flame retardant described in this invention has a particle size of less than 10 μm after being pulverized into ultrafine powder.

[0015] The mass ratio of the surface treatment agent and the flame retardant described in this invention is 6.5-24:100.

[0016] The film raw material of the present invention is one or more of PE resin, AS resin, ASA resin, PET resin and PC resin.

[0017] The thickness of the film described in this invention is 50-200 μm.

[0018] The flame retardant after pretreatment in step B of this invention accounts for 3-25% of the total mass of the raw materials.

[0019] The beneficial effects of this invention are as follows: 1. Due to the poor compatibility between flame retardants and plastics, they cannot fully integrate with plastics, resulting in poor dispersion and affecting the flame retardant effect. This is especially true when flame retardants are added during film production, as they are prone to precipitation, ultimately causing the flame retardant function to fail. The plastic base film prepared by the method of this invention has good compatibility between the flame retardant and the base film components, does not form a barrier layer, and ensures a firm adhesion between the aluminum foil and the base film plastic layer. The base film layer also forms a good protective layer for the aluminum foil, effectively blocking external mechanical damage without affecting the gas barrier properties of the aluminum foil.

[0020] 2. This invention uses a flame-retardant modified base film, coated with flame-retardant silicone instead of hot melt adhesive, and then composited with aluminum foil, which effectively blocks the combustion of flames, thereby achieving a certain flame-retardant effect. Detailed Implementation

[0021] To more clearly and in detail illustrate the objective and technical solution of this invention, the invention will be further described below through relevant embodiments. These embodiments are merely illustrative of the implementation methods of this invention and do not limit the scope of protection of this invention.

[0022] Preparation of plastic film: Phosphorus and nitrogen flame retardant and PET chips are fed into a twin-screw extruder at a mass ratio of 1:10, and mixed thoroughly and evenly in the molten state. The mixture is then extruded and granulated. The granules are then melted in a single-screw extruder and extruded into a film forming device to form a film.

[0023] The experiment was conducted in multiple groups. In control group 1, no flame retardant was added to the film preparation. In control group 2, phosphorus and nitrogen flame retardant masterbatch was directly melt-mixed with PET chips according to the above method.

[0024] The other experimental groups pretreated the flame retardant: the flame retardant masterbatch was subjected to ultrafine pulverization, and then mixed with the surface treatment agent at a ratio of 100:10 and fed into the micro-powdering equipment for crushing.

[0025] The surface treatment agent, by weight, comprises: 1 part dispersant, 5 parts polyethylene glycol, 2 parts silane coupling agent, and 5 parts surfactant. To select suitable components, the dispersant and surfactant are different in each group. The compatibility of the flame retardant with the plastic is visually observed, and the properties of the plastic film are graded as follows: A+: The film is flat and uniform; A: The film has almost no white spots, but the surface is not smooth and has an uneven feel; B: The film has no obvious particles, but a few white spots are visible; C: Partially compatible, the film contains a small number of particles; D: Almost immiscible, with obvious particles, and even large particles.

[0026] The specific composition and dispersion compatibility classification results are shown in Table 1 (polyethylene glycol and silane coupling agents are not listed in the table). Further, the films with dispersion compatibility of grade A or higher, and the control group, were used to prepare aluminum foil composite films. The films were fixed on a coating machine, coated with a silicone layer, and then the silicone-coated side was hot-pressed onto the aluminum foil to prepare the aluminum foil composite film. The limiting oxygen index of the materials was tested according to the room temperature oxygen index method specified in GB / T 2406.2—2021.

[0027] Table 1. Dispersion compatibility results of different surface treatment agents

[0028] The results showed that when the dispersant was ethylene bis-stearamide or microcrystalline wax, and the surfactant was sodium secondary alkyl sulfonate, sodium methyl stearate sulfonate or sodium dodecylbenzene sulfonate, the compatibility between the flame retardant and the plastic reached Grade A or above, and the limiting oxygen index of the aluminum foil composite film obtained reached 27 or above. The flame retardant performance was better than that of the control group 2 without flame retardant pretreatment. In particular, groups 10 and 11 had a limiting oxygen index of 31 or above, which is a high flame retardant level.

[0029] Using magnesium hydroxide as a flame retardant, microcrystalline wax as a dispersant, and sodium methyl stearate sulfonate as a surfactant, the proportion of the flame retardant in the raw materials was adjusted, and the type of film substrate was changed. Table 2 shows the limiting oxygen index test results of aluminum foil composite films prepared with different proportions and substrates: Table 2. Limiting oxygen index test results for materials with different flame retardant proportions.

[0030] Note: The above flame retardant percentage refers to the percentage of pretreated flame retardant in the raw materials for preparing plastic film.

[0031] As shown in Table 2, when the flame retardant accounts for 3% of the total mass of the raw materials, the limiting oxygen index is above 22%, indicating flame retardant properties. The flame retardant performance improves with increasing flame retardant content. However, when the flame retardant content exceeds 25%, it negatively impacts the plastic's properties and prevents film formation. Therefore, the recommended flame retardant content is 3-25%. Example 1

[0032] A method for preparing a flame-retardant aluminum foil composite film includes the following steps: A. Flame retardant pretreatment: The aluminum hydroxide flame retardant masterbatch is subjected to ultrafine pulverization to a particle size of less than 10μm, and then mixed with the surface treatment agent in a certain proportion and fed into the micro-powdering equipment for crushing; the mass ratio of the surface treatment agent to the flame retardant is 6.5:100.

[0033] B. The pretreated flame retardant and PET resin raw material are fed into a twin-screw extruder, and thoroughly mixed in the molten state before extrusion and granulation. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to produce a film with a thickness of 50μm; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

[0034] The surface treatment agent comprises: 0.5 parts microcrystalline wax, 3 parts polyethylene glycol, 1 part silane coupling agent, and 2 parts sodium methyl stearate sulfonate. Example 2

[0035] A method for preparing a flame-retardant aluminum foil composite film includes the following steps: A. Flame retardant pretreatment: The polyphosphoric acid flame retardant masterbatch is subjected to ultrafine pulverization to a particle size of less than 10μm, and then mixed with the surface treatment agent in a certain proportion and fed into the micro-powdering equipment for crushing; the mass ratio of the surface treatment agent to the flame retardant is 24:100.

[0036] B. The pretreated flame retardant and PET resin raw material are fed into a twin-screw extruder, and thoroughly mixed in the molten state before extrusion and granulation. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to produce a film with a thickness of 200μm; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

[0037] The surface treatment agent comprises: 3 parts microcrystalline wax, 8 parts polyethylene glycol, 5 parts silane coupling agent, and 8 parts sodium methyl stearate sulfonate. Example 3

[0038] A method for preparing a flame-retardant aluminum foil composite film includes the following steps: A. Flame retardant pretreatment: The antimony trioxide flame retardant masterbatch is subjected to ultrafine pulverization to a particle size of less than 10μm, and then mixed with the surface treatment agent in a certain proportion and fed into the micro-powdering equipment for crushing; the mass ratio of the surface treatment agent to the flame retardant is 15:100.

[0039] B. The pretreated flame retardant and PET resin raw material are fed into a twin-screw extruder, and thoroughly mixed in the molten state before extrusion and granulation. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to produce a film with a thickness of 100μm; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

[0040] The surface treatment agent comprises: 1 part microcrystalline wax, 5 parts polyethylene glycol, 2 parts silane coupling agent, and 5 parts sodium secondary alkyl sulfonate. Example 4

[0041] A method for preparing a flame-retardant aluminum foil composite film includes the following steps: A. Flame retardant pretreatment: The organosilicon flame retardant masterbatch is subjected to ultrafine pulverization to a particle size of less than 10μm, and then mixed with the surface treatment agent in a certain proportion and fed into the micro-powdering equipment for crushing; the mass ratio of the surface treatment agent to the flame retardant is 20:100.

[0042] B. The pretreated flame retardant and PET resin raw material are fed into a twin-screw extruder, and thoroughly mixed in the molten state before extrusion and granulation. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to produce a film with a thickness of 150μm; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

[0043] The surface treatment agent comprises: 2 parts microcrystalline wax, 6 parts polyethylene glycol, 3 parts silane coupling agent, and 3 parts sodium secondary alkyl sulfonate.

[0044] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a flame-retardant aluminum foil composite film, characterized in that... This includes the following steps: A. Flame retardant pretreatment: The flame retardant masterbatch is subjected to ultrafine pulverization treatment, and then mixed with the surface treatment agent in proportion and fed into the micro-powdering equipment for crushing. B. The pretreated flame retardant and film raw material are fed into a twin-screw extruder, mixed thoroughly and evenly in the molten state, and then extruded and granulated. C. Melt the granules in a single-screw extruder and extrude them into a film forming device to make a film; D. Fix the film on a coating machine, coat it with a silicone layer, and then bond the silicone-coated side to the aluminum foil and perform hot pressing to prepare an aluminum foil composite film.

2. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... The flame retardant is selected from one or more of phosphorus-nitrogen flame retardants, magnesium hydroxide, aluminum hydroxide, polyphosphoric acid flame retardants, antimony trioxide, and organosilicon flame retardants.

3. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... By weight, the surface treatment agent comprises: 0.5-3 parts dispersant, 3-8 parts polyethylene glycol, 1-5 parts silane coupling agent, and 2-8 parts surfactant.

4. The method for preparing the flame-retardant aluminum foil composite film according to claim 3, characterized in that... The dispersant is ethylene bis-stearamide or microcrystalline wax.

5. The method for preparing the flame-retardant aluminum foil composite film according to claim 3, characterized in that... The surfactant is selected from one or more of sodium secondary alkyl sulfonate, sodium methyl stearate sulfonate, and sodium dodecylbenzene sulfonate.

6. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... The particle size of the flame retardant after ultrafine pulverization is less than 10 μm.

7. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that, The mass ratio of the surface treatment agent to the flame retardant is 6.5-24:

100.

8. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... The film raw material is one or more of PE resin, AS resin, ASA resin, PET resin and PC resin.

9. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... The thickness of the film is 50-200 μm.

10. The method for preparing the flame-retardant aluminum foil composite film according to claim 1, characterized in that... The pretreated flame retardant in step B accounts for 3-25% of the total mass of the raw materials.

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