Flame-retardant Composite Film, Double-layered Flame-retardant Composite Film, and Fire Protection Case Comprising the Same

Abstract

The present invention provides a flame-retardant composite film that provides excellent fire suppression and blocking effects by establishing a double fire defense system including an inner thermal insulation coating layer that reacts to heat in the event of a fire and immediately swells tens of times to form a high-strength char containing an air layer, and an outer flame-retardant coating layer that prevents the spread of fire by excellent flame retardancy and prevents the fire from growing larger by blocking the inflow of oxygen, and a double flame-retardant composite film and a fire defense case including said flame-retardant composite film.

Description

Technology Field

[0001] The present invention relates to a flame-retardant composite film, a double flame-retardant composite film, and a fire protection case method comprising the flame-retardant composite film. Background Technology

[0002] In general, non-combustible products are provided in places with a risk of fire, areas with a high concentration of electrical facilities, or places where flames can spread through walls to prevent the spread of fire and the generation of toxic gases.

[0003] Ordinary non-combustible insulation sheet products are manufactured by bonding glass fiber fabric or aluminum foil, equipped with non-combustible coating layers on both sides of a pre-foamed foam sheet, with flame-retardant adhesive, and then compressing them.

[0004] Recently, as the use of smartphones and portable batteries with lithium-ion batteries has become commonplace, accidents involving explosions and fires caused by internal short circuits or overheating of the batteries are increasing. In particular, if a smartphone or portable battery is stored in a bag or similar container in a luggage storage area while inside a means of transportation such as an airplane or train, and a fire occurs in the said smartphone or portable battery, it can result in significant casualties.

[0005] Therefore, there is a need for a method to safely store items prone to fire, such as the aforementioned smartphones and auxiliary batteries.

[0006] However, existing flame-retardant or thermal insulation materials have not been effective in suppressing and blocking explosive fires caused by smartphones, power banks, etc. Prior art literature

[0007] Republic of Korea Registered Patent Publication No. 10-2025-00345731 The problem to be solved

[0008] The present invention has been devised to resolve the above-mentioned problems of the prior art, and

[0009] The purpose is to provide a flame-retardant composite film that effectively suppresses and blocks fire by establishing a dual fire defense system, comprising an internal thermal insulation coating layer that provides an excellent heat blocking effect by reacting to heat during a fire and immediately swelling tens of times to form a high-strength char containing an air layer, and an external flame-retardant coating layer that prevents the spread of fire through excellent flame retardancy and blocks the fire from growing larger by blocking the inflow of oxygen.

[0010] In addition, the present invention aims to provide a double flame-retardant composite film that effectively suppresses and blocks fire from the outside and inside by laminating two flame-retardant composite films such that their internal thermal insulation coating layers face each other.

[0011] In addition, the present invention aims to provide a fire protection case that effectively prevents secondary fire damage by blocking the external leakage of flames and sparks even in the event of explosive combustion of a mobile phone or auxiliary battery stored inside by including the flame-retardant composite film or double flame-retardant composite film, and efficiently protects the mobile phone or auxiliary battery from external fire. means of solving the problem

[0013] To achieve the above objective, the present invention

[0014] A fabric sheet woven from one or more fibers selected from the group consisting of ceramic fiber, silica fiber, mica fiber, mineral wool, basalt fiber, carbon fiber, glass fiber, aramid fiber, polyphenylene sulfide (PPS) fiber, wool, polyester fiber, nylon, kenaf fiber, and polypropylene fiber;

[0015] Coated on the outer surface of the above fabric sheet,

[0016] An external flame-retardant coating layer comprising 30 to 40 weight% of one or more binder resins selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, 20 to 30 weight% of mica powder, 20 to 30 weight% of one or more of silica powder and alumina powder, 3 to 5 weight% of zinc borate powder, and 1 to 10 weight% of additives, or

[0017] An external flame-retardant coating layer comprising 25 to 35 weight% silicone resin, 20 to 30 weight% ammonium polyphosphate (APP), 5 to 10 weight% melamine, 5 to 10 weight% pentaerythritol, and 20 to 30 weight% of one or more inorganic fillers selected from the group consisting of mica powder, silica powder, and alumina powder; and

[0018] The present invention provides a flame-retardant composite film comprising: an inner thermal insulation coating layer coated on the inner surface of the fabric sheet, comprising 30 to 40 weight% of one or more binder resins selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, 20 to 35 weight% of ammonium polyphosphate (APP), 10 to 20 weight% of dipentaerythritol, 10 to 20 weight% of melamine cyanurate, and 1 to 10 weight% of a foaming agent.

[0020] In addition, the present invention

[0021] A double flame-retardant composite film is provided by laminating two of the above flame-retardant composite films with internal thermal insulation coating layers facing each other.

[0022] In addition, the present invention

[0023] A fire protection case comprising the above flame-retardant composite film or double flame-retardant composite film is provided. Effects of the invention

[0025] The flame-retardant composite film of the present invention provides an excellent fire suppression and blocking effect by establishing a dual fire defense system comprising an inner thermal insulation coating layer that provides an excellent heat blocking effect by immediately swelling tens of times in response to heat during a fire to form a high-strength char containing an air layer, and an outer flame-retardant coating layer that prevents the spread of fire through excellent flame retardancy and prevents the fire from growing larger by blocking the inflow of oxygen.

[0026] In addition, the double flame-retardant composite film of the present invention provides the effect of effectively suppressing and blocking fire from the outside and the inside by laminating two flame-retardant composite films such that the internal thermal insulation coating layers face each other.

[0027] In addition, the fire protection case including the flame-retardant composite film or double flame-retardant composite film effectively prevents secondary fire damage by blocking the outward leakage of flames and sparks even in the event of explosive combustion of mobile phones or auxiliary batteries stored inside, and provides the effect of efficiently protecting said mobile phones or auxiliary batteries from external fire. Brief explanation of the drawing

[0029] FIGS. 1 to 3 are cross-sectional views schematically illustrating one embodiment of the flame-retardant composite film of the present invention. Specific details for implementing the invention

[0030] The present invention will be described in detail below.

[0031] The flame-retardant composite film of the present invention is,

[0032] A fabric sheet woven from one or more fibers selected from the group consisting of ceramic fiber, silica fiber, mica fiber, mineral wool, basalt fiber, carbon fiber, glass fiber, aramid fiber, polyphenylene sulfide (PPS) fiber, wool, polyester fiber, nylon, kenaf fiber, and polypropylene fiber;

[0033] Coated on the outer surface of the above fabric sheet,

[0034] An external flame-retardant coating layer comprising 30 to 40 weight% of one or more binder resins selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, 20 to 30 weight% of mica powder, 20 to 30 weight% of one or more of silica powder and alumina powder, 3 to 5 weight% of zinc borate powder, and 1 to 10 weight% of additives, or

[0035] An external flame-retardant coating layer comprising 25 to 35 weight% silicone resin, 20 to 30 weight% ammonium polyphosphate (APP), 5 to 10 weight% melamine, 5 to 10 weight% pentaerythritol, and 20 to 30 weight% of one or more inorganic fillers selected from the group consisting of mica powder, silica powder, and alumina powder; and

[0036] The fabric sheet has the characteristic of comprising an inner thermal insulation coating layer coated on the inner surface of the fabric sheet, comprising 30 to 40 weight% of one or more binder resins selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, 20 to 35 weight% of ammonium polyphosphate (APP), 10 to 20 weight% of dipentaerythritol, 10 to 20 weight% of melamine cyanurate, and 1 to 10 weight% of a foaming agent.

[0037] The above fabric may be woven by various methods known in the art. For example, it may be in the form of plain weave, twill weave, or nonwoven fabric, but is not limited thereto.

[0038] The fabric sheet may have a tensile strength of, for example, 200 N / 5 cm or more. In addition, it may have a tearing strength of 10 N or more.

[0039] The fabric sheet may have a thickness of 0.2 mm to 5 mm. The outer flame-retardant coating layer may be laminated on the surface of the fabric with a thickness of 0.005 mm to 0.1 mm. The inner thermal insulation coating layer may be laminated on the surface of the fabric with a thickness of 0.05 mm to 2 mm.

[0040] The binder resin included in the outer flame-retardant coating layer or the inner thermal insulation coating layer may have a weight-average molecular weight of 50,000 to 350,000 g / mol, preferably 50,000 to 150,000 g / mol. The molecular weight of the silicone resin used in another embodiment of the outer flame-retardant coating layer may also be within the above range.

[0041] The additives included in the above-mentioned external flame-retardant coating layer may include dispersants, curing agents, etc. Examples of the dispersants may include fatty acid-based dispersants (stearic acid series), phosphate ester-based dispersants (phosphate ester), organosilane-based dispersants (organosilane / silane coupling agents), etc. Examples of the curing agents may include organic peroxide-based curing agents (benzoyl peroxide), platinum catalysts (platinum complex solution), tin catalysts (dibutyltin dilaurate), etc. The above-mentioned additives may be applied equally to both types of external flame-retardant coating layers described above. At this time, the external flame-retardant coating layer containing 25 to 35 weight% of the silicone resin may also further include 1 to 10 weight% of the additives.

[0042] As the above foaming agent, foaming agents known in this field may be used without limitation.

[0043] In the present invention, the 'weight %' of the components constituting each coating layer is a value calculated based on 100 weight % of the total weight of the final solid content remaining after the solvent contained in the coating liquid has evaporated during the drying process, unless otherwise noted.

[0045] The fabric sheet serving as the substrate for the flame-retardant composite film is woven from inorganic fibers such as silica fibers, ceramic fibers, and glass fibers, which have a heat resistance temperature of 600°C to 1,200°C. This serves as a framework to maintain the overall shape of the film in the event of a fire, and silica fibers, in particular, can be preferably used as they exhibit minimal shrinkage or melting even at extremely high temperatures.

[0046] The outer flame-retardant coating layer of the above flame-retardant composite film is formed on the outer surface of the fabric sheet and performs the function of preventing the penetration of external flames and providing physical strength. The binder resin of the outer flame-retardant coating layer performs the function of simultaneously securing heat resistance and flexibility, and inorganic fillers such as mica / alumina powder are densely filled with plate-like mica and granular alumina to block the movement of oxygen and heat. The zinc borate powder forms a glass-like film upon combustion to suppress the carbonization of the fabric fibers.

[0047] The internal thermal insulation coating layer of the flame-retardant composite film is formed on the inner surface of the fabric sheet and reacts at a specific temperature (about 200°C or higher) to form a thermal insulation layer. The binder resin captures the gas generated during expansion and provides viscoelasticity to maintain the carbonized structure. The ammonium polyphosphate (APP) acts as an acid catalyst, dipentaerythritol (DPER) acts as a carbon source to form a solid carbonized layer, and melamine cyanurate generates gas to expand it.

[0049] The double flame-retardant composite film (first embodiment) of the present invention is characterized by having two flame-retardant composite films of the present invention laminated so that their internal thermal insulation coating layers face each other.

[0050] In one embodiment of the present invention, the double flame-retardant composite film (second form) may further have an aerogel sheet, an aramid fiber sheet, a ceramic fiber sheet, a glass fiber sheet, a polyimide (PI) sheet, a polyimide (PI) and aerogel composite sheet, a SiC (silicon carbide) sheet, a carbon fiber felt sheet, or a ceramic and aramid composite nonwoven sheet laminated between the thermal insulation coating layers laminated facing each other as a cushion-type filler sheet.

[0051] The above cushion-type filler sheet can be laminated with a thickness of 0.5mm to 5mm.

[0052] In one embodiment of the present invention, the double flame-retardant composite film (third form) may further have a rigid filler sheet, such as a melamine foam sheet, a PIR expanded foam (Polyisocyanurate Foam) sheet, a phenolic foam sheet, a polyimide foam sheet, a silicone foam sheet, a ceramic foam sheet, a calcium silicate sheet, a perlite sheet, or a vermiculite board sheet, laminated between the thermal insulation coating layers facing each other.

[0053] The above rigid filler sheet can be laminated with a thickness of 0.5 mm to 200 mm.

[0054] The above double flame-retardant composite film laminate structure has a structure in which two films are arranged with their inner insulation coating layers facing each other to maximize the thermal insulation effect. In the event of a fire, the space between the inner insulation coating layers expands to form a strong thermal insulation wall. Additionally, a cushion-type filler sheet or a rigid filler sheet may be added between them.

[0055] The above double flame-retardant composite film provides ultra-insulating performance that can efficiently suppress and block explosive fires caused by smartphones, auxiliary batteries, secondary battery storage boxes, secondary battery transport boxes, etc.

[0057] In the present invention, the bonding between the layers constituting the flame-retardant composite film or the double flame-retardant composite film may be formed using an adhesive known in the art, or by heat pressing or sewing using a sewing thread. Examples of such adhesives may be used, but are not limited to acrylic adhesives, urethane adhesives, silane adhesives, etc.

[0058] The above sewing thread may use high heat resistance aramid fibers, ceramic fibers, polyimide (PI) fibers, SiC (silicon carbide), carbon fibers, glass fibers, basalt fibers, etc., but is not limited thereto.

[0060] The fire protection case of the present invention is characterized by including the flame-retardant composite film of the present invention. The fire protection case is characterized by forming a storage space from a material including the flame-retardant composite film.

[0061] The fire protection case of the present invention is characterized by including the double flame-retardant composite film of the present invention. The fire protection case is characterized by forming a storage space from a material including the double flame-retardant composite film.

[0062] The above fire-resistant case is manufactured using the above composite film, so that when a battery stored in the case undergoes thermal runaway, the insulating coating layer on the inside of the pouch reacts immediately to encase the battery with a thick carbonized layer, and the flame-retardant coating layer on the outside blocks the spread of fire. This prevents the external temperature of the pouch from rising rapidly and prevents sparks from flying outward, thereby ensuring the safety of the user.

[0063] The above case may be a pouch or a pack, but is not limited thereto; any form that is capable of suppressing a fire in an object contained therein to prevent it from spreading to the outside, or that is capable of protecting an object contained therein from external fire, is included in the case of the present invention.

[0064] The above case may be used for storing, for example, a mobile phone or a mobile phone power bank, but the use is not limited thereto.

[0065] The above case may have an opening and closing structure formed of one or more of a zipper, Velcro, and a resealable heat seal, but is not limited thereto.

[0067] The present invention will be explained in more detail below through examples. However, the following examples are intended to explain the invention more specifically and do not limit the scope of the invention. The following examples may be appropriately modified or changed by those skilled in the art within the scope of the invention.

[0069] Example 1: Preparation of flame-retardant composite film (First form)

[0070] (1) Preparation of fabric sheets

[0071] A fabric sheet with a thickness of 0.5 mm and a basis weight of 600 g / m² was prepared, woven from silica fibers which have the best heat resistance and dimensional stability. To remove impurities from the surface of the fabric sheet, it was prepared by hot air drying at 100°C for 10 minutes.

[0072] (2) Preparation of external flame-retardant coating solution

[0073] Silicone resin was used as a binder resin to ensure heat resistance and flexibility of the surface exposed to the external environment. 3.0 wt% of 3-aminopropyltriethoxysilane as a dispersant was first mixed with 35 wt% of silicone resin (Mw: approximately 100,000 g / mol), followed by the addition of 25 wt% of mica powder and 25 wt% of alumina powder. Subsequently, 5 wt% of zinc borate powder and 0.5 wt% of a curing retardant were added and stirred at high speed. Finally, 1.5 wt% of a platinum catalyst and 5.0 wt% of a solvent for viscosity control were added to complete the external flame-retardant coating solution.

[0074] (3) Formation of an external flame-retardant coating layer

[0075] The external flame-retardant coating solution prepared above was applied to one side (outer side) of a prepared silica fiber fabric sheet using a comma coater to a thickness of 80 μm. After application, the solvent was evaporated and the resin was cured by drying in an oven at 160°C for 5 minutes to form an external flame-retardant coating layer.

[0076] (4) Preparation of internal thermal insulation coating solution (expandable flame retardant system)

[0077] Acrylic resin was used as a binder resin to implement an intumescent system that foams upon heat to form a charcoal-type insulation layer. As the acrylic resin, an emulsion-type acrylic resin with a weight-average molecular weight (Mw) of 200,000 g / mol and a glass transition temperature (Tg) of -10°C was selected. 35 wt% of acrylic resin, 30 wt% of ammonium polyphosphate (APP) as an acid catalyst, 15 wt% of dipentaerythritol as a carbonizing agent, 15 wt% of melamine cyanurate as a foaming agent, and 5 wt% of a physical foaming agent (expanded graphite) were added to a stirrer. An internal insulation coating solution was prepared by fine dispersion stirring at 1,500 rpm for 40 minutes to prevent the components from clumping.

[0078] (5) Formation of internal insulating coating layer and completion of film

[0079] The internal thermal insulation coating solution prepared above was applied to the back side (inner side) of the fabric sheet having the external flame-retardant coating layer formed above using a knife coater to a thickness of 100 μm. After application, the internal thermal insulation coating layer was formed by hot air drying at 100°C for 15 minutes, thereby finally manufacturing a flame-retardant composite film.

[0081] Example 2: Preparation of flame-retardant composite film (second form)

[0082] A flame-retardant composite film was prepared in the same manner as in Example 1, except that an external flame-retardant coating solution prepared by the following method was used as the external flame-retardant coating solution in Example 1.

[0083] <Manufacture of External Flame Retardant Coating Liquid (Expandable Silicone)>

[0084] To impart direct expansion performance to the outer layer, a coating solution was prepared in the following steps. 30 wt% of silicone resin with a weight-average molecular weight (Mw) of approximately 120,000 g / mol was added to a stirrer. 25 wt% of ammonium polyphosphate (APP), 8 wt% of melamine, and 7 wt% of pentaerythritol were sequentially added to the silicone resin. 25 wt% of a powder mixture of mica powder and alumina powder in a 1:1 ratio was added as an inorganic filler, and 5 wt% of a silane coupling agent was added to improve dispersibility.

[0085] An external flame-retardant coating solution in which inorganic particles were completely dispersed within a silicone binder was prepared by stirring at a speed of 2,000 rpm for 1 hour using a homo-mixer.

[0087] Example 3: Preparation of a double flame-retardant composite film (Type 1)

[0088] Two sheets of flame-retardant composite film (Type 1) manufactured through Example 1 above were prepared. The two prepared flame-retardant composite films were arranged so that their 'internal thermal insulation coating layers' faced each other. After spraying a flame-retardant acrylic adhesive between the internal thermal insulation coating layers that were in contact with each other, the two films were laminated together by passing them through a hot roll press heated to 80°C at a pressure of 2 kgf / cm². Through this process, a double flame-retardant composite film was manufactured in which, upon the occurrence of a flame, the internal coating layer expands to fill the empty space between the two films with a thick carbonized layer, thereby maximizing thermal insulation performance.

[0090] Example 4: Preparation of a double flame-retardant composite film with an interposed thermal insulation (Type 2)

[0091] Two flame-retardant composite films manufactured through Example 1 above and one aerogel sheet with a thickness of 3 mm having ultra-insulating performance were prepared.

[0092] After spraying a flame-retardant acrylic adhesive onto the 'internal thermal insulation coating layer' of the first flame-retardant composite film, the aerogel sheet was laminated, and then a flame-retardant acrylic adhesive was sprayed onto it again. After that, the second flame-retardant composite film was placed so that the 'internal thermal insulation coating layer' faced the direction of the aerogel sheet (i.e., facing downward) to form a sandwich structure. Subsequently, the three film sheets were laminated as a single unit by passing them through a hot roll press heated to 80°C at a pressure of 2 kgf / cm².

[0093] By the above method, a double flame-retardant composite film having a structure of external flame blocking (external coating layer) - silica fiber fabric sheet - foam insulation (inner coating layer) - ultra-insulation (aerogel sheet) - foam insulation (inner coating layer) - silica fiber fabric sheet - back heat transfer blocking (external coating layer) was manufactured.

[0094] Manufacture of Aerogel Sheets

[0095] 150 parts by weight of ethanol and 30 parts by weight of distilled water were mixed with 100 parts by weight of tetraethyl orthosilicate (TEOS) as a solvent. 1.5 parts by weight of an aqueous solution of 0.1 M hydrochloric acid (HCl) as an acid catalyst were slowly added to this, and a hydrolysis reaction was induced by stirring at 500 rpm for about 1 hour at room temperature (25°C) to obtain a transparent silica sol.

[0096] With the silica sol prepared in the first step cooled to 10°C or lower, 5 parts by weight of 0.5 M ammonia water (NH4OH), a base catalyst, were added to initiate a gelation reaction. The mixed solution, in which viscosity began to rise, was uniformly applied and impregnated onto a glass fiber mat substrate with a thickness of 5 mm and a density of 130 kg / m³. The impregnated substrate was left at room temperature for 30 minutes to induce the silica sol to transition into a silica wet gel with a three-dimensional network structure inside the fiber substrate.

[0097] The above-mentioned gelled wet gel composite was placed in a sealed container and aged at 50°C for 12 hours to strengthen the bonding strength of the gel network. Subsequently, to prevent pore shrinkage occurring during the drying of the aerogel and to impart hydrophobicity, the aged composite was completely immersed in a surface modification solution prepared by mixing hexamethyldisilazane (HMDS) with ethanol in a volume ratio of 1:9. The mixture was then reacted in this state at 60°C for 24 hours to convert the hydrophilic silanol groups (-OH) on the silica surface into hydrophobic trimethylsilyl groups (-Si(CH₃). It was replaced with )₃).

[0098] The surface-modified composite was mounted in a high-pressure supercritical extractor. Liquid carbon dioxide (CO2) was injected into the extractor to replace the internal solvent (ethanol) with carbon dioxide, and then the temperature and pressure were increased to 60°C and 100 bar to induce a phase transition of the carbon dioxide to a supercritical state. Extraction was carried out for 4 hours under these supercritical conditions to completely remove the solvent inside the pores without pore collapse due to surface tension, and then the pressure was gradually reduced to produce a final silica aerogel sheet.

[0100] Example 5: Preparation of a double flame-retardant composite film with an interposed thermal insulation (Third form)

[0101] Two flame-retardant composite films manufactured through Example 2 above and one melamine foam sheet with a thickness of 3 mm manufactured as follows were prepared.

[0102] After spraying a flame-retardant acrylic adhesive onto the 'internal thermal insulation coating layer' of the first flame-retardant composite film, the melamine foam sheet was laminated, and then spraying a flame-retardant acrylic adhesive onto it again. After that, the second flame-retardant composite film was placed so that the 'internal thermal insulation coating layer' faced the direction of the melamine foam sheet (i.e., facing downward) to form a sandwich structure. Subsequently, the three film sheets were laminated as a single unit by passing them through a hot roll press heated to 80°C at a pressure of 2 kgf / cm².

[0103] By the above method, a double flame-retardant composite film having a structure of external flame blocking (external coating layer) - silica fiber fabric sheet - foam insulation (inner coating layer) - melamine foam sheet - foam insulation (inner coating layer) - silica fiber fabric sheet - back heat transfer blocking (external coating layer) was manufactured.

[0104] Manufacture of Melamine Foam Sheets

[0105] Preparation of a foaming melamine resin composition: For 100 parts by weight of a melamine-formaldehyde initial condensate (molar ratio of formaldehyde to melamine = about 1:3), 3 parts by weight of sodium dodecylbenzenesulfonate as an emulsifier, 15 parts by weight of pentane as a blowing agent, and 2.5 parts by weight of an 85% aqueous formic acid solution as a curing catalyst were introduced into a reactor. Subsequently, the mixture was uniformly mixed using a stirrer at room temperature (25°C) at a speed of 2,000 rpm for about 3 minutes to obtain a foaming melamine resin composition.

[0106] Microwave Foaming and Crosslinking Curing: The resin composition prepared in the first step was injected into a foaming mold (width 1,000 mm × length 1,000 mm × height 500 mm) coated with polytetrafluoroethylene (PTFE). After placing the mold into a microwave oven, microwaves were irradiated for about 5 minutes under conditions of a frequency of 2.45 GHz and an output of 15 kW. This vaporized the foaming agent inside the composition and simultaneously induced a crosslinking reaction of the melamine resin to form a block-shaped primary melamine foam.

[0107] After the foaming was completed, the block-shaped melamine foam was transferred to a hot air dryer and heat treatment (annealing) was performed at a temperature of 210°C for 30 minutes. Through this process, the three-dimensional open-cell structure of the foam was stabilized, and unreacted formaldehyde, moisture, and excess blowing agent remaining inside the foam were completely volatilized and removed.

[0108] The melamine foam block, after heat treatment for slicing and sheet shaping, was slowly cooled to room temperature. The cooled melamine foam block was mounted on a horizontal slicing machine dedicated to foam, and the final melamine foam sheet was manufactured by cutting it parallel to a thickness of 3 mm by adjusting the blade spacing.

[0110] Example 6: Manufacture of a pouch for storing an auxiliary battery and / or a mobile phone using a double flame-retardant composite film

[0111] A double flame-retardant composite film manufactured in Example 3 was prepared. Considering the dimensions of the mobile phone and auxiliary battery to be stored (typically 170mm x 80mm for a large smartphone), two sheets of film were cut into a rectangular shape measuring 200mm x 120mm, including the seam allowance. At this time, flame resistance was ensured by positioning the outer surface of the film (silicone coating layer) to face the outermost and innermost (storage surface) of the pouch.

[0112] The three sides (left, right, and bottom) of the two cut films were double-stitched using high-heat-resistant aramid sewing thread. To prevent flames or gases from leaking through the seams, a heat-resistant silicone sealant was applied to the inside of the seams and then heat-pressed at 150°C to form a completely sealed structure.

[0113] A cover was formed at the opening at the top of the pouch to prevent the contents from leaking out. High-temperature Velcro (Hook and Loop), with verified heat resistance, was attached as a fastening means for the cover. Explanation of the symbols

[0114] 10: Fabric sheet 20: External flame-retardant coating 30: Internal insulation coating layer 40: Aerogel sheet or melamine foam sheet 100, 200, 300: Flame-retardant composite film

Claims

Claim 1 A fabric sheet woven from one or more fibers selected from the group consisting of ceramic fiber, silica fiber, mica fiber, mineral wool, basalt fiber, carbon fiber, glass fiber, aramid fiber, polyphenylene sulfide (PPS) fiber, wool, polyester fiber, nylon, kenaf fiber, and polypropylene fiber; and a material selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, coated on the outer surface of the fabric sheet. An external flame-retardant coating layer comprising 30 to 40 weight% of one or more binder resins, 20 to 30 weight% of mica powder, 20 to 30 weight% of one or more of silica powder and alumina powder, 3 to 5 weight% of zinc borate powder, and 1 to 10 weight% of additives, or an external flame-retardant coating layer comprising 25 to 35 weight% of silicone resin, 20 to 30 weight% of ammonium polyphosphate (APP), 5 to 10 weight% of melamine, 5 to 10 weight% of pentaerythritol, and 20 to 30 weight% of one or more inorganic fillers selected from the group consisting of mica powder, silica powder, and alumina powder;and an inner thermal insulation coating layer coated on the inner surface of the fabric sheet, comprising 30 to 40 weight% of one or more binder resins selected from the group consisting of acrylic resin, polyurethane resin, polyethylene terephthalate (PET) resin, silicone resin, inorganic sol, rubber resin, nylon resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polyvinyl chloride (PVC) resin, and epoxy resin, 20 to 35 weight% of ammonium polyphosphate (APP), 10 to 20 weight% of dipentaerythritol, 10 to 20 weight% of melamine cyanurate, and 1 to 10 weight% of a foaming agent; a flame-retardant composite film comprising; Claim 2 A double flame-retardant composite film formed by laminating two flame-retardant composite films of claim 1 with internal thermal insulation coating layers facing each other. Claim 3 A double flame-retardant composite film according to claim 2, characterized in that an aerogel sheet, an aramid fiber sheet, a ceramic fiber sheet, a glass fiber sheet, a polyimide (PI) sheet, a polyimide (PI) and aerogel composite sheet, a SiC (silicon carbide) sheet, a carbon fiber felt sheet, or a ceramic and aramid composite nonwoven fabric sheet is further laminated as a cushion-type filler sheet between the thermal insulation coating layers laminated facing each other. Claim 4 A double flame-retardant composite film according to claim 2, characterized in that a rigid filler sheet, such as a melamine foam sheet, a PIR expanded foam (Polyisocyanurate Foam) sheet, a phenolic foam sheet, a polyimide foam sheet, a silicone foam sheet, a ceramic foam sheet, a calcium silicate sheet, a perlite sheet, or a vermiculite board sheet, is further laminated between the thermal insulation coating layers laminated facing each other. Claim 5 A fire-resistant case comprising the flame-retardant composite film of claim 1. Claim 6 A fire-protective case comprising a double flame-retardant composite film according to any one of paragraphs 2 to 4. Claim 7 A fire-protective case according to claim 5, characterized in that the case is a pouch or a pack. Claim 8 In claim 5, the above case is a fire-protective case characterized by being used for storing electrical or electronic products containing a secondary battery.

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