Composition for forming flame-retardant coating layer on steel sheet, steel sheet, and method for manufacturing steel sheet

Abstract

A composition for forming a flame-retardant coating layer on a steel sheet, according to an embodiment of the present invention, comprises 100 parts by weight of a metal phosphate, 50-250 parts by weight of silica, and 1-200 parts by weight of an inorganic flame retardant.

Description

Composition for forming a flame-retardant coating layer on a steel plate, steel plate and method for manufacturing a steel plate

[0001] One embodiment of the present invention relates to a composition for forming a flame-retardant coating layer on a steel plate, a steel plate, and a method for manufacturing a steel plate. More specifically, one embodiment of the present invention relates to a composition for forming a flame-retardant coating layer on a steel plate substrate for cans used as a cylindrical battery case for electric vehicles, which forms a flame-retardant coating layer to provide a flame-retardant effect in the event of high-temperature ignition caused by an abnormal increase in temperature within a battery cell, as well as to delay the transition to explosion due to thermal runaway.

[0002] With the recent rise in interest in eco-friendly energy, hybrid and electric vehicles utilizing batteries are garnering attention. In these cases, the battery is typically mounted in a battery pack, and the vehicle is driven by power derived from the battery pack. A battery pack consists of a battery module composed of multiple battery cells and a battery case that houses the battery module. Multiple battery cells within the pack are arranged in a stacked state to achieve high output. In various types of batteries, such as lithium batteries, phenomena of thermal runaway and ignition occur due to internal short circuits, overcharging, over-discharging, high-temperature environments, mechanical damage, and defects during the manufacturing process. Particularly in the field of electric vehicles utilizing high-output lithium-ion batteries, the need for measures to prevent battery thermal runaway is increasing as cases of fires caused by thermal runaway escalating into material losses and human casualties are occurring frequently. Therefore, fire resistance of battery cells or battery packs, as well as heat resistance that prevents generated heat from dissipating externally, can be considered extremely important factors affecting safety. Inside a lithium-ion battery, a thin membrane called a separator is installed to prevent contact between the positive and negative electrodes. However, mechanical damage, high-temperature manufacturing defects in lithium plating, or other factors can damage this separator, potentially causing an internal short circuit. Thermal runaway is a phenomenon where a chain reaction occurs between the components within the battery cell; when the temperature rises abnormally, it forms a chain reaction in which chemical reactions occur sequentially inside. This chain reaction creates a cycle of temperature increase within the battery, and this cycle continues at extremely high temperatures until the battery is depleted.

[0003] To mitigate the risk of thermal runaway in such battery cans, a battery cell is disclosed in which at least a portion of the outer surface of the battery can is covered with a fire-resistant coating. Technology is known in which the fire-resistant coating is an ablative coating, an expansive coating, or an endothermic coating, or a polyurethane-based coating. However, when used in batteries, fire-resistant coatings fail to maintain their shape if ignition occurs, and they cannot be expected to exhibit sufficient fire resistance and thermal insulation for automotive applications.

[0004] One embodiment of the present invention provides a composition for forming a flame-retardant coating layer on a steel plate, a steel plate, and a method for manufacturing a steel plate. More specifically, one embodiment of the present invention provides a composition for forming a flame-retardant coating layer on a steel plate substrate for cans used as a cylindrical battery case for electric vehicles, which forms a flame-retardant coating layer on the substrate to provide a flame-retardant effect in the event of high-temperature ignition caused by an abnormal increase in temperature within a battery cell, as well as a steel plate for cans and a method for manufacturing a steel plate for cans.

[0005] A composition for forming a flame-retardant coating layer on a steel plate according to one embodiment of the present invention comprises 100 parts by weight of a metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant.

[0006] A composition for forming a flame-retardant coating layer on a steel plate according to one embodiment of the present invention may further include 30 to 200 parts by weight of resin.

[0007] A composition for forming a flame-retardant coating layer on a steel plate according to one embodiment of the present invention may further include 0.1 to 20 parts by weight of chromium oxide.

[0008] Metal phosphates may include one or more of Al, Mg, Co, Ca, Sr, Ba, Zn, and Mn.

[0009] The average particle size of the silica can be 7 to 20 nm.

[0010] Inorganic flame retardants include aluminum hydroxide (Al(OH)3), antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), tin oxide (SnO2), zircon (ZrO2·SiO2), zirconia (ZrO2), boric acid (H3BO3), boron oxide (B2O3), zinc borate (2ZnO·2B2O3·3.5H2O), and ammonium polyphosphate ((NH4PO3) n It may include one or more of (OH2)), molybdenum trioxide (MoO3), ammonium molybdenum oxide ((NH)4·2Mo2O7), zinc molybdate (MoO4Zn), and calcium-zinc molybdate (Ca-Zinc Molybdate, Ca-MoO4Zn).

[0011] The resin may include one or more of epoxy resins, ester resins, melamine resins, siloxane resins, acrylic resins, phenolic resins, styrene resins, vinyl resins, ethylene resins, and urethane resins.

[0012] A steel plate according to one embodiment of the present invention comprises a steel plate substrate and a flame-retardant coating layer located on the surface of the steel plate substrate, wherein the flame-retardant coating layer comprises 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant.

[0013] The flame-retardant coating layer may further include 30 to 200 parts by weight of resin.

[0014] The flame-retardant coating layer may further include 0.1 to 20 parts by weight of chromium oxide.

[0015] A Ni plating layer may be interposed between the steel plate substrate and the flame-retardant coating layer.

[0016] A method for manufacturing a steel plate according to one embodiment of the present invention may include the steps of: preparing a steel plate substrate; applying a flame-retardant coating layer forming composition comprising 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant to the surface of the steel plate substrate; and heat treating.

[0017] It may further include a plating step of forming a Ni plating layer on a steel plate substrate.

[0018] The application step involves applying a composition for forming a flame-retardant coating layer at a concentration of 0.1 to 50.0 g / m² 2 It can be applied with an application amount of .

[0019] The heat treatment step can be performed at a temperature of 200 to 550°C for 10 to 200 seconds.

[0020] A composition for forming a flame-retardant coating layer according to one embodiment of the present invention improves flame-retardant properties and simultaneously possesses the characteristic of hindering combustion in the event of high-temperature ignition caused by abnormal phenomena of the electrolyte in the battery cell.

[0021] Therefore, it can significantly delay the thermal runaway phenomenon caused by abnormal temperature rise within the battery cell and significantly reduce the time for a rapid fire in the battery cell to spread to the main body.

[0022] FIG. 1 is a schematic diagram of a cross-section of a steel plate according to one embodiment of the present invention.

[0023] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0024] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0025] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0026] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0027] In one embodiment of the present invention, the meaning of including additional elements is that the remainder of iron (Fe) is replaced by an amount of the additional element.

[0028] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0029] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0030]

[0031] A composition for forming a flame-retardant coating layer on a steel plate according to one embodiment of the present invention comprises 100 parts by weight of a metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant.

[0032] Each component is described in detail below. In one embodiment of the present invention, the weight part refers to a relative weight ratio based on 100 weight parts of metal phosphate, and is based on the solid content of each component. Solid content refers to the weight when each component is dried in a state free of volatile substances such as solvents. Specifically, assuming a heat treatment process when forming a flame-retardant coating layer, it refers to the weight remaining after heat treatment.

[0033]

[0034] Metal phosphates act as binders in the composition for forming a flame-retardant coating layer. If an appropriate amount of metal phosphate is not included, the adhesion of the flame-retardant coating layer may be compromised.

[0035] Metal phosphates can be produced by a manufacturing process in which a metal oxide is added to pure phosphoric acid (H3PO4) and reacted. To improve the adhesion of the metal phosphate, a condensation reaction between the metal phosphate and boric acid can be induced by additionally adding boric acid during the reaction process and maintaining it for at least 3 hours, and it is also possible to use this condensation product instead of the metal phosphate. In one embodiment of the present invention, the metal phosphate includes not only the metal phosphate but also the condensation product of the metal phosphate and boric acid. The produced metal phosphate is strongly acidic.

[0036] Metal phosphates can be added to the composition using a solution having a solid content of 50 to 70 weight%. At this time, if the solid content in the solution is too low, the amount of free phosphoric acid in the metal phosphate increases, which may cause surface moisture absorption after the production of the metal phosphate; if the solid content is too high, the excess of solid content relative to pure phosphoric acid may result in poor reaction and precipitation.

[0037] Metal phosphates may include various metals without limitation. Specifically, the metals of the metal phosphate may include one or more of Al, Mg, Co, Ca, Sr, Ba, Zn, and Mn. More specifically, the metal phosphate may include one or more of magnesium dihydrogen phosphate (Mg(H2PO4)2) and aluminum dihydrogen phosphate (Al(H2PO4)3). More specifically, it may include magnesium dihydrogen phosphate (Mg(H2PO4)2) and aluminum dihydrogen phosphate (Al(H2PO4)3). In this case, the metal phosphate may include 10 to 50 parts by weight of aluminum dihydrogen phosphate and 50 to 90 parts by weight of magnesium dihydrogen phosphate, based on solid content, per 100 parts by weight of the total. If too little aluminum dihydrogen phosphate is included, the effect of improving heat resistance by adding aluminum dihydrogen phosphate may not be sufficient. If too much aluminum phosphate is added, the Al component may increase the crystallization of silica, causing cracks in the flame-retardant coating layer. Specifically, the metal phosphate may comprise 15 to 35 parts by weight of aluminum phosphate and 65 to 85 parts by weight of magnesium phosphate based on solid content, with respect to 100 parts by weight of the total, and more specifically, may comprise 20 to 30 parts by weight of aluminum phosphate and 70 to 80 parts by weight of magnesium phosphate.

[0038] A composition for forming a flame-retardant coating layer according to one embodiment of the present invention comprises 50 to 250 parts by weight of silica per 100 parts by weight of metal phosphate. The silica increases the strength and hardness of the flame-retardant coating layer itself through intramolecular network reactions during film drying after coating, thereby improving flame retardancy. Various types of silica can be used without limitation, and commercially available colloidal silica can also be used. More specifically, basic colloidal silica can be used.

[0039] Silica may be included in an amount of 50 to 250 parts by weight per 100 parts by weight of metal phosphate. If too little silica is added, the heat resistance improvement effect resulting from the addition of silica cannot be sufficiently obtained. If too much silica is added, the relative amount of metal phosphate decreases, which may lead to a decline in the adhesion of the flame-retardant coating layer. Specifically, silica may be included in an amount of 100 to 200 parts by weight per 100 parts by weight of metal phosphate, and more specifically, in an amount of 125 to 175 parts by weight per 100 parts by weight of metal phosphate. In this case, "parts by weight" refers to the relative weight based on the metal phosphate.

[0040] During the drying process of the film, silica undergoes a condensation reaction through a chain reaction of silica as shown in Reaction Scheme 1 below, forming a network structure such as -(HO-Si-O-Si)-n.

[0041] [Reaction Equation 1]

[0042] -(HO-Si-OH-) n + -(HO-Si-OH-) n = -(HO-Si-O-Si-) n + H2O (1)

[0043] However, using only such silica results in an overly uniform network structure, which limits the density of the flame-retardant coating layer. Consequently, there are limitations in imparting adhesion or flame retardancy between the steel substrate and the flame-retardant coating layer; to compensate for these insufficient physical properties, metal phosphates and complex oxides may be added.

[0044] The silica may be colloidal silica with an average particle size in the range of 7 to 20 nm. The composition may be prepared using a solution of silica with a solid fraction of 25 to 35 wt%. If the solid fraction is too small, a problem of reduced strength of the flame-retardant coating layer may occur. If the solid fraction is too large, a problem of reduced compatibility after manufacturing the coating agent may occur. More specifically, the solid fraction may be 28 to 32 wt%.

[0045] Silica is Na + The content may be 0.1 to 1.0 wt%. Na + If the content is too low, a problem may arise where the density of the film is reduced. Na + If the content is too high, an increase in cations within the coating agent may cause problems that impede the compatibility between components. More specifically, Na + The content may be 0.3 to 0.7 wt%.

[0046] A silica solution containing silica may have a pH of 9.5 to 10.5. If the pH is too low or too high, the pH difference of components other than silica in the coating composition may be extreme, and phase separation may occur. More specifically, the pH may be 9.5 to 10.0.

[0047] The silica may have a viscosity of 3.5 to 6.5 cp. If the viscosity is too low, problems may arise regarding the applicability of the coating composition. If the viscosity is too high, it may thicken during prolonged use, leading to aging problems. More specifically, the viscosity may be 4 to 6 cp. The viscosity can be measured using a Brookfield viscometer at a temperature of 20°C based on a 30% by weight silica solution.

[0048] The silica may have a specific gravity of 1.1 to 1.3. If the specific gravity is too low, it may be difficult to control the amount of coating composition applied. If the specific gravity is too high, sedimentation problems may occur after the coating agent is manufactured. More specifically, the specific gravity may be 1.15 to 1.25.

[0049] A composition for forming a flame-retardant coating layer according to one embodiment of the present invention may include 1 to 200 parts by weight of an inorganic flame retardant per 100 parts by weight of a metal phosphate. By adding an inorganic flame retardant that simultaneously possesses heat resistance and flame retardancy, combustion caused by chemical reactions between battery components can be hindered, thereby preventing the spread of fire or, even if a fire occurs, significantly slowing down its speed.

[0050] Inorganic flame retardants include aluminum hydroxide (Al(OH)3), antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), tin oxide (SnO2), zircon (ZrO2·SiO2), zirconia (ZrO2), boric acid (H3BO3), boron oxide (B2O3), zinc borate (2ZnO·2B2O3·3.5H2O), and ammonium polyphosphate ((NH4PO3) n It may include one or more of (OH2)), molybdenum trioxide (MoO3), ammonium molybdenum oxide ((NH)4·2Mo2O7), zinc molybdate (MoO4Zn), and calcium-zinc molybdate (Ca-Zinc Molybdate, Ca-MoO4Zn). More specifically, it may include one or more of aluminum hydroxide, antimony trioxide, and zinc borate.

[0051] Aluminum hydroxide, a representative inorganic flame retardant, exhibits flame retardancy through a physical flame retardant mechanism that acts as an endothermic reaction in which dehydration occurs at temperatures above 200°C, thereby cooling the solid phase and blocking flammable gases and fuel dilution through the generation of water vapor.

[0052] [Reaction Equation 2]

[0053] 2Al(OH)3→ Al2O3+ 3H2O (180 ~ 300 ℃, -1075 KJ / kg)

[0054] 2AlOOH → Al2O3+ H2O (400~450 ℃, -700 KJ / kg)

[0055] In addition, the antimony-based compound introduced in the present invention exhibits a flame-retardant effect through the following chemical reaction.

[0056] [Reaction Equation 3]

[0057] Sb2O3+ 2HCl → 2SbOCl + H2O (250℃)

[0058] 5SbOCl → Sb4O5Cl2+ SbCl3↑ (245~280 ℃)

[0059] 4Sb4O5Cl2→ 5Sb3O4Cl + SbCl3↑ (410~475 ℃)

[0060] 3Sb3O4Cl → 4Sb2O3+ SbCl3↑ (475~565 ℃)

[0061] In the above reaction equation 3, the reaction between Sb2O3 and HCl is an endothermic reaction, so it provides a cooling effect, and the reactant SbCl3 acts as a radical interceptor. In addition, SbOCl and SbCl3 keep the halogen in the gaseous phase longer, thereby enhancing the reaction with H or OH radicals generated during a battery fire, which can significantly delay the thermal runaway phenomenon.

[0062] In addition, zinc borate (2ZnO·2B2O3·3.5H2O) can exhibit excellent flame retardant effects when introduced together with aluminum hydroxide as a halogen-free flame retardant (Reaction Formula 4), having characteristics such as suppressing smoke generation during battery fires and rapidly charring the burned resin.

[0063] [Reaction Equation 4]

[0064] Halogen-containing reaction

[0065] 2ZnO·2B2O3·3.5H2O + HCl → ZnCl2+ B2O3+ H2O

[0066] Halogen-free reaction

[0067] 2ZnO·2B2O3·3.5H2O + Al(OH)3→ xAl2O3·yB2O3·zZnO + H2O

[0068] If too little inorganic flame retardant is included, it is difficult to obtain a sufficient combustion inhibition effect on oxide substances in the battery. If too much inorganic flame retardant is included, it may impede the battery charging and discharging effect. More specifically, 50 to 150 parts by weight of inorganic flame retardant may be included.

[0069] A composition for forming a flame-retardant coating layer according to one embodiment of the present invention may further include 30 to 200 parts by weight of resin per 100 parts by weight of metal phosphate. Resin refers to a polymer compound and is a concept contrasted with monomer. The resin acts as a binder together with the metal phosphate. When additional resin is added, it can partially replace the phosphate, thereby suppressing surface stickiness and powder precipitation phenomena. If too little resin is added, the fraction of metal phosphate increases, posing a risk of surface stickiness and powder precipitation. If too much resin is included, not only is the compatibility between the composition components reduced, but harmful gases may also be generated in the event of battery ignition. More specifically, the composition may further include 40 to 100 parts by weight of resin per 100 parts by weight of metal phosphate.

[0070] The resin may include one or more of epoxy resins, ester resins, melamine resins, siloxane resins, acrylic resins, phenolic resins, styrene resins, vinyl resins, ethylene resins, and urethane resins. More specifically, it may be an ester resin. The resin may be in an emulsion state with a number average molecular weight of 20,000 to 50,000, a Tg of 40 to 90 °C, and a solid fraction of 10 to 50%.

[0071] Chromium oxide may be additionally added to enhance the corrosion resistance of the flame-retardant coating layer and to neutralize silica. When chromium oxide is additionally included, it may be included in an amount of 0.1 to 20 parts by weight per 100 parts by weight of metal phosphate. If too little chromium oxide is included, the effect of enhancing corrosion resistance may not be sufficient, and it may also be difficult to properly perform the role of neutralizing silica. If too much chromium oxide is included, a problem may arise where the viscosity of the composition increases rapidly. Specifically, chromium oxide may be included in an amount of 2 to 8 parts by weight per 100 parts by weight of metal phosphate, and more specifically, chromium oxide may be included in an amount of 4 to 6 parts by weight per 100 parts by weight of metal phosphate.

[0072] In addition to the aforementioned components, the composition for forming a flame-retardant coating layer may further include a solvent, and the addition of additional components is not limited. The solvent serves to facilitate the application of the composition and to uniformly disperse the components. The amount of solvent is not particularly limited, but may be included in an amount of 100 to 1,000 parts by weight per 100 parts by weight of metal phosphate.

[0073] The method for manufacturing the composition for forming a flame-retardant coating layer is not particularly limited, but the following methods may be used.

[0074] The method may include the step of simultaneously adding a metal oxide, an inorganic flame retardant, and a resin, if necessary, to phosphoric acid (H3PO4), and then heating and mixing to produce a first composition comprising a metal phosphate, an inorganic flame retardant, and a resin; and the step of mixing silica and, if necessary, chromium oxide into the first composition. At this time, since the ratio can be mixed according to the aforementioned solid content ratio, redundant descriptions are omitted.

[0075] Below, each step is explained in detail.

[0076] In cases where the reaction of phosphoric acid and metal oxide proceeds first and then the inorganic flame retardant and resin are added, the viscosity of the metal phosphate increases rapidly after the metal phosphate is produced. Therefore, even if the inorganic flame retardant and resin are introduced to induce mixing, the inorganic flame retardant and resin are not evenly dispersed within the metal phosphate, and the particles clump together.

[0077] In one embodiment of the present invention, a metal oxide, an inorganic flame retardant, and a resin are simultaneously added to phosphoric acid to proceed with the reaction of the phosphoric acid and the metal oxide into a metal phosphate. Since the inorganic flame retardant and the resin are added while the phosphoric acid is in a low viscosity state as the reaction has not yet proceeded, a very uniform mixed phase is formed according to the flow induced by stirring, and as it progresses to a uniform mixed phase with gradually higher viscosity, the dispersibility of the inorganic flame retardant and the resin within the coating composition can be improved.

[0078] In the step of preparing the first composition, the heating temperature may be 80°C or higher. If the heating temperature is too low, even if stirring is performed, the inorganic flame retardant and resin within the metal phosphate may not form a uniform mixture, and the particles may clump together.

[0079] Next, silica and, if necessary, chromium oxide can be added to the first composition and mixed.

[0080] Since the descriptions regarding silica and chromium oxide and their contents have been explained in relation to the aforementioned composition for forming a flame-retardant coating layer, redundant descriptions are omitted.

[0081] FIG. 1 shows a schematic cross-sectional view of a steel plate (100) for a can according to one embodiment of the present invention. As shown in FIG. 1, the steel plate (100) for a can according to one embodiment of the present invention includes a steel plate substrate (10) and a flame-retardant coating layer (20) located on the steel plate substrate (10).

[0082] The steel plate substrate (10) can be any steel plate substrate (10) used in general can steel plates (100) without limitation. In one embodiment of the present invention, since the main configuration is to form a flame-retardant coating layer (20) of a special component on the steel plate substrate (10), a detailed description of the steel plate substrate (10) is omitted.

[0083] Additionally, the composition of the steel plate substrate (10) is described as follows.

[0084] The steel sheet substrate may contain, in weight percent, C: 0.02 to 0.07%, Si: 0.05% or less, Mn: 0.1 to 0.4%, Al: 0.01 to 0.06%, P: 0.02% or less, S: 0.015% or less, N: 0.006% or less, Mo: 0.02 to 0.15%, and the remainder being Fe and other unavoidable impurities. Since the description of each component of the steel sheet substrate (10) is the same as generally known, a detailed description is omitted.

[0085] A Ni plating layer (11) may be present on the steel plate substrate (10) to help secure corrosion resistance against the battery electrolyte and the atmosphere. That is, a Ni plating layer (11) may be interposed between the steel plate substrate (10) and the flame-retardant coating layer (20).

[0086] The thickness of the flame-retardant coating layer (20) can be 0.1 to 20 μm. If the thickness of the flame-retardant coating layer (20) is too thin, it is difficult to secure appropriate flame retardancy and heat resistance. If the thickness of the flame-retardant coating layer (20) is too thick, the total volume and weight of the can may increase. In one embodiment of the present invention, appropriate flame retardancy and heat resistance can be secured even if a thin flame-retardant coating layer (20) is formed. More specifically, the thickness of the flame-retardant coating layer (20) can be 2 to 5 μm.

[0087] The flame-retardant coating layer (20) may maintain the solid component and content ratio within the composition for forming the flame-retardant coating layer described above. Specifically, the flame-retardant coating layer (20) comprises 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 2 to 200 parts by weight of inorganic flame retardant. Since the reasons for limiting each component and its content are the same as those explained in the composition described above, redundant explanations are omitted.

[0088] In addition, the flame-retardant coating layer (20) may further include 30 to 200 parts by weight of resin.

[0089] In addition, the flame-retardant coating layer (20) may further include 0.1 to 20 parts by weight of chromium oxide.

[0090]

[0091] A method for manufacturing a steel plate for a can according to one embodiment of the present invention may include the steps of: preparing a steel plate substrate; applying a flame-retardant coating layer forming composition comprising 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 2 to 200 parts by weight of an inorganic flame retardant to the surface of the steel plate substrate; and heat treating.

[0092] It may further include a plating step of forming a Ni plating layer on a steel plate substrate.

[0093] First, a composition for forming a flame-retardant coating layer is applied onto a steel plate substrate. If a plating step is further included, the composition for forming a flame-retardant coating layer can be applied onto a Ni plating layer.

[0094] As the steel plate substrate and the composition for forming the flame-retardant coating layer are the same as those previously described, a repetitive explanation is omitted.

[0095] The composition for forming a flame-retardant coating layer before application can be maintained at a temperature of 10 to 30°C. If the temperature is lower than the aforementioned range, the viscosity increases, making it difficult to manage a uniform application amount. If the temperature is too high, the gelation phenomenon of the composition for forming a flame-retardant coating layer is accelerated, which may degrade the surface quality. More specifically, the composition for forming a flame-retardant coating layer before application can be maintained at a temperature of 15 to 25°C.

[0096] When applying a composition for forming a flame-retardant coating layer, the application amount is 1.0 to 50.0 g / m² 2 It can be applied within the specified range. If the application amount is too high, the flame-retardant coating layer becomes too thick, which may increase adhesion to the steel substrate and the overall weight and volume of the can. If the application amount is too low, the heat resistance and flame retardancy imparted by the flame-retardant coating layer may be weakened. More specifically, the application amount is 5.0 to 25.0 g / m² 2 It may be. The composition may be applied only to the inner surface of the can.

[0097] The heat treatment step can be performed at a temperature of 200 to 550°C for 10 to 200 seconds.

[0098]

[0099] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0100]

[0101] Experimental Example: Confirmation of properties according to metal type

[0102] A steel plate for cans plated with Ni on one side was prepared as a test material.

[0103] A composition for forming a flame-retardant coating layer was prepared containing the components summarized in Table 1 below and 100g of water. For the preparation of the phosphate, a metal oxide inorganic flame retardant and a resin were simultaneously added to phosphoric acid and stirred under a heating state of 80°C or higher to produce a metal phosphate, after which colloidal silica was added and mixed to prepare the composition. The prepared composition for forming a flame-retardant coating layer was applied to the test material at a rate of 10g / m² 2 After coating, specimens were prepared by drying at 450°C for 30 seconds. Silica with an average particle size of 12 nm was used as the silica, and an ester-based emulsion resin (number average molecular weight 25,000, Tg 78°C, solid fraction 35%) was used as the resin.

[0104] Evaluation Method for Heat Resistance and Flame Retardancy: A battery shape was completed by laminating materials such as a positive electrode, negative electrode, and separator inside a battery can coated with the aforementioned coating agent on its inner surface, and then injecting an electrolyte. Thermal runaway was induced by connecting a heating plate to the outer surface of the battery can to heat it. The heating plate, used as an external heat source, was set to heat at a temperature rise rate of approximately 6°C / min. A 70 Ah capacity battery can was placed on top of the heating plate, and K-Type thermocouples were attached to the outer and inner surfaces of the battery to record temperature changes. A Yokogawa MV1000 was used as the data collector for temperature measurement, and the effect of the flame-retardant coating agent was verified by measuring the rapid temperature change inside the battery and the ignition time (min). The battery temperature was measured at the point 20 minutes after heating the battery can at a temperature rise rate of 6°C / min using an external heat source. The ignition time was measured at the point when the internal temperature reached 270°C or higher.

[0105] Specimen Metal Phosphate (100 parts by weight) Silica Inorganic Flame Retardant Resin Chromium Oxide Type Content (parts by weight) Type Content (parts by weight) Content (parts by weight) Content (parts by weight) 1 Al:Mg (5:5) 150 Aluminum Hydroxide 755052 Al:Mg (5:5) 150 Aluminum Hydroxide 1255053 Al:Mg (5:5) 150 Antimony Trioxide 755054 Al:Mg (5:5) 150 Antimony Trioxide 1255055 Al:Mg (5:5) 150 Zinc Borate 755056 Al:Mg (5:5) 150 Zinc Borate 1255057 Al:Mg (5:5) 150 Aluminum Hydroxide + Zinc Borate 50 + 255058 Al:Mg (5:5) 150 Aluminum Hydroxide + Zinc Borate 50 + 755059 Al:Mg (5:5)300 Aluminum Hydroxide 50 50 510 Al:Mg (5:5)300 Aluminum Hydroxide + Zinc Borate 50 + 75 50 511 Al:Mg (5:5)150 No Added 50 512 Al:Mg (5:5)150 No Added 50 513 Al:Mg (5:5)150 No Added 50 514 Al:Mg (5:5)150 Antimony Pentoxide 35 7 55 15 Al:Mg (5:5)150 Antimony Pentoxide 70 10 0 516 Al:Mg (5:5)150 Aluminum Hydroxide + Antimony Pentoxide 35 + 35 50 7.5 17 Al:Mg (5:5)150 Aluminum Hydroxide + Antimony Pentoxide 35 + 75 50 10

[0106] Specimen Battery Temperature (°C / 20 min) Ignition Time (mm / s) 11 25 27 min 15 sec Example 2 1 23 28 min 19 sec Example 3 1 33 26 min 30 sec Example 4 1 29 27 min 49 sec Example 5 1 28 27 min 1 sec Example 6 1 24 27 min 59 sec Example 7 1 22 29 min 33 sec Example 8 1 20 30 min 02 sec Example 9 1 90 23 min 30 sec Comparative Example 10 18 0 23 min 55 sec Comparative Example 1 1 22 0 20 min 30 sec Comparative Example 1 2 22 5 19 min 17 sec Comparative Example 1 3 24 8 18 min 52 sec Comparative Example 1 4 1 23 29 min 12 sec Example 15 1 33 30 min 41 sec Example 16 1 18 33 min 09 seconds Example 1712828 minutes 55 seconds Example

[0107] As can be seen in Tables 1 and 2, in the case of the examples in which each component in the composition for forming the flame-retardant coating layer is appropriately included, it can be seen that heat resistance and flame retardancy are improved.

[0108] On the other hand, it can be confirmed that the comparative example, which does not contain the appropriate components, has inferior heat resistance and flame retardancy.

[0109]

[0110] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0111] [Explanation of the symbol]

[0112] 100: Steel sheet for cans, 10: Steel sheet material,

[0113] 11: Ni plating layer, 20: Flame retardant coating layer

Claims

1. 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica and A composition for forming a flame-retardant coating layer on a steel plate comprising 1 to 200 parts by weight of an inorganic flame retardant.

2. In Paragraph 1, A composition for forming a flame-retardant coating layer on a steel plate, further comprising 30 to 200 parts by weight of resin.

3. In Paragraph 1, A composition for forming a flame-retardant coating layer on a steel plate, further comprising 0.1 to 20 parts by weight of chromium oxide.

4. In Paragraph 1, The above metal phosphate is a composition for forming a flame-retardant coating layer on a steel sheet comprising one or more of Al, Mg, Co, Ca, Sr, Ba, Zn, and Mn.

5. In Paragraph 1, A composition for forming a flame-retardant coating layer on a steel plate, wherein the average particle size of the silica is 7 to 20 nm.

6. In Paragraph 1, The above-mentioned inorganic flame retardants are aluminum hydroxide (Al(OH)3), antimony trioxide (Sb2O3), antimony pentoxide (Sb2O5), tin oxide (SnO2), zircon (ZrO2·SiO2), zirconia (ZrO2), boric acid (H3BO3), boron oxide (B2O3), zinc borate (2ZnO·2B2O3·3.5H2O), and ammonium polyphosphate ((NH4PO3) n A composition for forming a flame-retardant coating layer on a steel sheet comprising one or more of (OH2)), molybdenum trioxide (MoO3), ammonium molybdenum oxide ((NH)4·2Mo2O7), zinc molybdate (MoO4Zn), and calcium-zinc molybdate (Ca-Zinc Molybdate, Ca-MoO4Zn).

7. In Paragraph 2, The above resin is a composition for forming a flame-retardant coating layer on a steel plate comprising one or more of epoxy resin, ester resin, melamine resin, siloxane resin, acrylic resin, phenolic resin, styrene resin, vinyl resin, ethylene resin, and urethane resin.

8. Steel plate substrate and It includes a flame-retardant coating layer located on the surface of the above-mentioned steel plate substrate, and The above flame-retardant coating layer comprises 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant, for a steel plate.

9. In Paragraph 8, The above flame-retardant coating layer is a steel plate further comprising 30 to 200 parts by weight of resin.

10. In Paragraph 8, The above flame-retardant coating layer is a steel plate further comprising 0.1 to 20 parts by weight of chromium oxide.

11. In Paragraph 8, A steel plate having a Ni plating layer interposed between the above steel plate substrate and the above flame-retardant coating layer.

12. Step of preparing the steel plate substrate; A step of applying a composition for forming a flame-retardant coating layer comprising 100 parts by weight of metal phosphate, 50 to 250 parts by weight of silica, and 1 to 200 parts by weight of an inorganic flame retardant to the surface of the above steel plate substrate, and A method for manufacturing a steel plate including a heat treatment step.

13. In Paragraph 12, A method for manufacturing a steel plate, further comprising a plating step of forming a Ni plating layer on the above-mentioned steel plate substrate.

14. In Paragraph 12, The above-mentioned application step involves applying a composition for forming a flame-retardant coating layer at a concentration of 0.1 to 50.0 g / m² 2 A method for manufacturing a steel plate by applying a coating amount.

15. In Paragraph 12, A method for manufacturing a steel plate in which the heat treatment step is performed at a temperature of 200 to 550℃ for 10 to 200 seconds.

Images