Polyurea resin composition, nonflammable powder, and method for forming a polyurea resin layer

Abstract

To provide a polyurea resin composition which has flame resistance (semi fire resistance) without impairing characteristics inherent to a polyurea resin, and can be sprayed by a conventional method, and a method for forming a polyurea resin layer by spraying.SOLUTION: A polyurea resin composition contains 100 pts.mass of polyamine, 100-160 pts.mass of polyisocyanate, and 15-30 pts.mass of expanded graphite, and a particle diameter of the expanded graphite is equal to or smaller than 100 meshes. A polyurea spraying apparatus 100 adds the expanded graphite to at least one of polyamine and polyisocyanate. A polyurea resin produced by mixing and stirring of polyamine and polyisocyanate is heated at 60°C to 80°C, is pressurized at a pressurized pressure, and then is sprayed toward an object from a spray port 52A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polyurea resin composition, a noncombustible powder, and a method for forming a polyurea resin layer, and more particularly to a polyurea resin composition, a noncombustible powder, and a method for forming a polyurea resin layer that are useful for forming a polyurea resin layer that is excellent in corrosion resistance, abrasion resistance, waterproofness, impact resistance, stretchability, and further noncombustibility. [Background technology]

[0002] Polyurea resins have been proposed that are excellent in waterproofness, impact resistance, corrosion resistance, etc. Among these polyurea resins, particularly high-purity polyurea resins (pure polyurea resins) formed using only polyisocyanate and polyamine as organic polymer compounds, can be improved in corrosion resistance, abrasion resistance, waterproofness, impact resistance, UV protection, and elasticity by adding various fillers (the inherent properties of polyurea resins).

[0003] Polyurea resin can be used, for example, to reinforce a concrete block wall by applying it to the surface to form a resin layer (approximately 1.5 mm to 3 mm thick), or to repair / reinforce a cracked concrete wall by injecting it into the crack.

[0004] However, like other organic polymer compounds (such as polyurethane resins), polyurea resins have the drawback of easily burning in the event of a fire because they break down into smaller molecules as the temperature rises and produce flammable gases.

[0005] For this reason, when polyurethane resin is actually used to repair cracks in block walls or concrete walls installed outdoors, or even when it is tried to be laid on the roof of a house because of its waterproofing properties, its flammability prevents the building from achieving flame retardancy (quasi-fire resistance), making it unsuitable for use in these structures.

[0006] Conventionally, other organic polymer compounds (e.g., polyurethane) other than polyurea resins have been imparted with flame retardancy by using ammonium polyphosphate, borax, expandable graphite, etc. as fillers. Furthermore, with regard to polyurea resins, it has been proposed that flame retardancy can be imparted by adding the various fillers described above that are used in other organic polymer compounds, for example, in the following patent documents and non-patent documents. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-082229 [Patent Document 2] CN-A-102559022 [Non-patent literature]

[0008] [Non-Patent Document 1] "Further studies on the flame retardancy of polyurea: Effects of coatings and flame retardant additions" J-GLOBAL ID No.: 11A1320776 Summary of the Invention [Problem to be solved by the invention]

[0009] In particular, the above-mentioned Non-Patent Document 1 discloses that in order to impart flame retardancy to a polyurea resin, it is possible to include flame retardant additives (ammonium polyphosphate, expandable graphite, zinc borate, etc.) that have conventionally been used in other organic polymer compounds. However, there is no specific disclosure or suggestion as to what fillers should actually be added to the polyurea resin and in what ratio, or whether the polyurea resin to which these fillers have been added still retains its original properties (corrosion resistance, abrasion resistance, waterproofing, impact resistance, UV protection, and elasticity).

[0010] Generally, polyurethane resin is sprayed onto an object (such as a block wall or a crack in concrete) to form a layer of a desired thickness on the surface of the object (spraying method). However, none of the above patent documents or non-patent documents discloses or suggests at all whether polyurethane resin to which the above-mentioned flame retardant additive (filler) has been added can actually be sprayed using the conventional spraying method.

[0011] The present invention has been made in view of the above circumstances, and aims to provide a polyurea resin composition suitable for forming a flame-retardant and non-combustible (preferably, quasi-fire-resistant) polyurea resin layer on an object by a conventional method (spraying method) without impairing the inherent properties of the polyurea resin (corrosion resistance, abrasion resistance, waterproofness, impact resistance, stretchability, etc.), a non-combustible powder, and a method for forming a polyurea resin layer using the polyurea resin composition. [Means for solving the problem]

[0012] In the first invention, the fireproof powder to be added to the polyurea resin (mainly the base material) contains the following components (A), (B), (C), and (D). (A) Expanded graphite (B) Brominated flame retardants (C) Melamine polyphosphate (D) Silica powder In addition, the second invention is the seventh invention in which the amounts of the component (B), the component (C), and the component (D) are 80 parts by mass, 80 parts by mass, and 100 parts by mass, respectively, of the component (A).

[0013] In addition, a third invention provides a polyurethane resin composition that can be sprayed by a spraying method, which contains the following components (a), (b), (c), (d), and (e). (A) Base composition (base material) consisting of polyamine and polyisocyanate (a) Expanded graphite (c) Brominated flame retardants (d) Melamine polyphosphate (E) Silica powder

[0014] In addition, a fourth invention is the third invention, wherein the total of the components (b) to (e) is blended in an amount of 15 to 40 parts by mass per 100 parts by mass of the component (a). Furthermore, a fifth invention is the third or fourth invention, in which the total of the components (b) to (e) is blended in an amount of 25 parts by mass or more per 100 parts by mass of the component (a).

[0015] In addition, the sixth invention is the third invention, wherein 30 parts by mass of the total of the components (b) to (e) are blended with 100 parts by mass of the component (a). Furthermore, the seventh invention is the third to sixth inventions, in which the components (a), (c), (d) and (e) are blended in a ratio of 4:8:8:10.

[0016] Furthermore, an eighth invention is a method for forming a non-flammable polyurethane resin layer by adding the non-flammable powder according to the first or second invention to a polyurethane resin base material, and spraying the resulting polyurethane resin composition onto an object to form a desired film thickness. The method includes the steps of adding the non-flammable powder to at least one of a polyamine and a polyisocyanate, heating the polyamine and the polyisocyanate so that the temperature of the polyurethane resin produced by mixing and stirring the polyamine and the polyisocyanate is between 60 and 80 degrees Celsius, pressurizing the polyamine and the polyisocyanate so that the pressure of the polyurethane resin produced by mixing and stirring the polyamine and the polyisocyanate is a predetermined pressure, and spraying the polyurethane resin heated to between 60 and 80 degrees Celsius and pressurized to the predetermined pressure onto the object.

[0017] In addition, the ninth invention is the eighth invention, wherein in the step of heating the polyamine and the polyisocyanate, when the non-flammable powder is added to the polyisocyanate, the polyisocyanate is heated to 70 to 80 degrees Celsius, and when the non-flammable powder is added to the polyamine, the polyamine is heated to 70 to 80 degrees Celsius.

[0018] A tenth aspect of the present invention provides a polyurea resin production system including a first tank for storing polyisocyanate, a second tank for storing polyamine, a first heating means for adjusting the temperature of the polyisocyanate supplied from the first tank, a second heating means for adjusting the temperature of the polyamine supplied from the second tank, a first pressurizing means for pressurizing the polyisocyanate supplied from the first tank, a second pressurizing means for pressurizing the polyamine supplied from the second tank, a compression means for compressing a gas, a production means for mixing and stirring the polyisocyanate and the polyamine to produce a polyurea resin, and a spray nozzle for spraying the produced polyurea resin from the spray nozzle. When a polyurethane resin composition obtained by adding the non-combustible powder of the seventh or eighth invention to a base composition consisting of polyamine and polyisocyanate is sprayed onto an object using a polyurethane spraying device equipped with a spraying means for spraying from the nozzle, the temperature of the polyurethane resin in the spraying means is maintained at 60 to 80 degrees Celsius by the first heating means and the second heating means, the pressure of the polyurethane resin in the spraying means is pressurized to a predetermined pressure by the first pressurizing means and the second pressurizing means, and the pressurized polyurethane resin is sprayed onto the object from the spray nozzle to form a polyurethane resin layer.

[0019] In addition, an eleventh aspect of the present invention is the tenth aspect of the present invention, wherein the diameter of the injection port is 1.5 mm, and the predetermined pressure is 23.5 MPa to 24.0 MPa. In addition, the 12th invention is the 11th invention, wherein the first heating means heats the polyisocyanate to 70 to 80 degrees Celsius when the non-flammable powder is added to the polyisocyanate, and the second heating means heats the polyamine to 70 to 80 degrees Celsius when the non-flammable powder is added to the polyamine. [Effects of the Invention]

[0020] According to the first invention, in order to provide non-combustible properties, the non-combustible powder added to the polyurea resin contains (A) expanded graphite, (B) a brominated flame retardant, (C) melamine polyphosphate, and (D) silica powder. By appropriately combining the effects of each flame retardant, it is possible to provide the desired non-combustible properties (quasi-fire resistance).

[0021] Furthermore, according to the second invention, the non-combustible powder of the seventh invention is used in an amount of 80 parts by mass of component (B), 80 parts by mass of component (C), and 100 parts by mass of component (D) relative to 40 parts by mass of component (A). This optimizes the effectiveness of each component as a flame retardant, and allows for the realization of a polyurethane resin layer with the desired non-combustibility (quasi-fire resistance) while reducing the amount of non-combustible powder added.

[0022] Furthermore, according to the third invention, the polyurea resin composition is composed of (a) a base composition consisting of polyamine and polyisocyanate, (b) expandable graphite, (c) a brominated flame retardant, (d) melamine polyphosphate, and (e) silica powder. By appropriately combining the effects of each flame retardant, it is possible to impart the desired non-flammability (quasi-fire resistance) to the polyurea resin layer.

[0023] Furthermore, according to the fourth invention, the total of components (b) to (e) is 20 to 40 parts by mass per 100 parts by mass of component (a) in the ninth invention, so that the polyurethane resin layer can be made non-flammable to the extent that flames do not spread even when burned for a certain period of time.

[0024] Furthermore, according to the fifth invention, in the third or fourth invention, the total of components (b) to (e) is 25 parts by mass or more per 100 parts by mass of component (a), so that even after burning for a certain period of time, carbonization of the polyurethane resin layer is suppressed, and non-combustibility (quasi-fire resistance) to the extent that dripping due to burning can be suppressed is achieved.

[0025] Furthermore, according to the sixth invention, in the third invention, components (b) to (e) are each 30 parts by mass per 100 parts by mass of component (a), so that even after a certain period of combustion, the polyurea resin layer hardly carbonizes (does not deform), and a level of non-combustibility (quasi-fire resistance) is achieved in which no dripping due to combustion occurs.

[0026] Furthermore, according to the seventh invention, in the third to sixth inventions, the components (i), (ii), (iii), (iv) and (v) are optimized in a ratio of 4:8:8:10, so that the total amount of non-combustible powder required to achieve non-combustible (quasi-fireproof) properties in the polyurea resin layer can be reduced, resulting in cost savings.

[0027] Furthermore, according to the eighth invention, in a method for spraying a polyurea resin containing the non-flammable powder according to the first or second invention onto an object to form a desired film thickness, the temperature of the polyurea resin produced by mixing and stirring the polyamine or polyisocyanate containing the non-flammable powder is between 60 and 80 degrees Celsius, and this is pressurized at a predetermined pressure, so that the polyurea resin sprayed onto the object is formed uniformly and can achieve excellent non-flammability (quasi-fire resistance) while maintaining the properties of the polyurea resin itself.

[0028] Furthermore, according to the ninth invention, the polyamine or polyisocyanate to which the non-flammable powder has been added is sufficiently heated, and the viscosity is reduced by this heating, making it possible to form a more stable and uniform polyurea resin layer by spraying.

[0029] Furthermore, according to the tenth invention, when a polyurea resin obtained by adding the non-flammable powder of the first or second invention to a polyurea resin base material (base material composition) consisting of polyamine and polyisocyanate, or a polyurea resin composition of the ninth to thirteenth inventions, is sprayed onto an object to form a polyurea resin layer, the temperature of the polyurea resin can be maintained at 60 to 80 degrees Celsius, and the pressure of the polyurea resin in the spraying means can be increased to a predetermined pressure, so that a polyurea resin layer with the desired non-flammable properties (quasi-fire resistance) can be uniformly formed while maintaining its original properties.

[0030] Furthermore, according to the 11th invention, by simply setting the diameter of the injection nozzle of the 16th invention to 1.5 mm and the specified pressure to 23.5 MPa to 24.0 MPa, a non-flammable (semi-fireproof) polyurethane resin layer can be formed by a spraying method. Furthermore, according to the 12th invention, even when a non-combustible powder is added by the first and second heating means of the 11th invention, the viscosity of the polyurethane resin composition can be reduced, thereby enabling the uniform formation of a non-combustible (quasi-fireproof) polyurethane resin layer, and a polyurethane resin layer with excellent non-combustible (quasi-fireproof) properties can be formed while maintaining the inherent properties of the polyurethane resin. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a polyurethane spraying device (spraying device) 100. As shown in FIG. [Figure 2] FIG. 2 is a photograph showing a combustion experiment in which the noncombustible powder of the second embodiment is not added to the polyurea resin. [Figure 3] FIG. 3 is a photograph showing a combustion experiment in which 15 parts by mass of non-combustible powder was added to 100 parts by mass of a base material of a polyurea resin. [Figure 4] FIG. 4 is a photograph showing a combustion experiment in which 20 parts by mass of non-combustible powder was added to 100 parts by mass of a base material of a polyurea resin. [Figure 5] FIG. 2 is a photograph showing a combustion experiment in which 25 parts by mass of non-combustible powder was added to 100 parts by mass of a base material of a polyurea resin. [Figure 6] FIG. 2 is a photograph showing a combustion experiment in which 30 parts by mass of non-combustible powder was added to 100 parts by mass of a base material of a polyurea resin. [Figure 7] FIG. 2 is a photograph showing a combustion experiment in which 40 parts by mass of non-combustible powder was added to 100 parts by mass of a base material of a polyurea resin. DETAILED DESCRIPTION OF THE INVENTION

[0032] (First embodiment) Hereinafter, a description will be given of a polyurea resin having excellent flame retardancy (preferably having quasi-fire resistance) according to the first embodiment, and a method for forming a polyurea resin layer using the same. The base material of the polyurea resin used in the first embodiment is made of only polyisocyanate and polyamine as organic polymer compounds (pure polyurea resin). Pure polyurea resin, which uses only polyisocyanate and polyamine as organic polymer compounds, can exhibit excellent corrosion resistance, abrasion resistance, waterproofing, impact resistance, and elasticity by adding various fillers.

[0033] First, the "intrinsic properties" of pure polyurea resin will be explained. The following "Table 1" shows the properties of the polyurea resin "Qtech-406" provided by Qingdao Shamu New Materials Co., Ltd. This "Qtech-406" has particularly high "waterproof" properties due to the use of specially designed fillers. [Table 1]

[0034] The following "Table 2" shows the properties of the polyurea resin "Qtech-417" provided by Qingdao Shamu New Materials Co., Ltd. This "Qtech-417" has particularly high "elasticity" due to the use of specially designed fillers. [Table 2]

[0035] The following "Table 3" shows the properties of the polyurea resin "Qtech-420" provided by Qingdao Shamu New Materials Co., Ltd. This "Qtech-420" has particularly high "impact resistance" due to the use of ingenious fillers. [Table 3]

[0036] However, like other organic polymer compounds, these polyurea resins undergo thermal decomposition with increasing temperature, resulting in lower molecular weights and the generation of flammable gaseous products, making them susceptible to combustion in the event of a fire, etc. Therefore, they are not particularly suitable for use in places where there is fire.

[0037] In order to impart flame retardancy to a polyurea resin, it is conceivable to use as a filler a flame retardant (e.g., ammonium polyphosphate, borax, expandable graphite, etc.) that has conventionally been used in other organic polymer compounds (e.g., polyurethane) (e.g., Non-Patent Document 1), but it is necessary to specifically consider what kind of filler should be added and how it should be added in order to achieve flame retardancy without impairing the inherent properties of the polyurea resin.

[0038] Furthermore, since it is planned that polyurethane resin will be applied to cracks in block walls and concrete walls, and to waterproof sheets on the roofs of buildings, it is necessary to specifically consider whether a flame-retardant (semi-fireproof) polyurethane resin layer of the desired thickness (1.5 to 3 mm) can be formed on these block walls and other objects using a simple method (spraying method) that uses a conventional polyurethane spraying device.

[0039] In this embodiment, the polyurea resin composition to which flame retardancy (preferably quasi-fire resistance) is added is a pure polyurea resin that uses only polyisocyanate (A-ingredient) and polyamine (B-ingredient) as organic polymer compounds, with 100 to 160 parts by mass of polyisocyanate per 100 parts by mass of polyamine. It will be obvious to those skilled in the art that the optimum ratio of polyurea resin is 110 parts by mass of polyisocyanate to 100 parts by mass of polyamine.

[0040] The present inventors have confirmed that the inherent properties expected of polyurea resins (determined by the presence or absence of elasticity, a representative property) can be exhibited when polyisocyanate is used in a range of 100 to 160 parts by mass per 100 parts by mass of polyamine. [Table 4] If the ratio is 90 parts by mass of polyisocyanate to 100 parts by mass of polyamine, the desired elasticity cannot be obtained, and the inherent properties of the polyurea resin cannot be expected. Furthermore, even when 170 parts by mass of polyisocyanate is used relative to 100 parts by mass of polyamine, the desired stretchability is not obtained, and the inherent properties of the polyurea resin cannot be expected.

[0041] The required elasticity of polyurethane resin (such as the elongation at break in Tables 1 to 3) varies depending on the intended use. In other words, the allowable elasticity varies depending on the intended use (such as sprayed concrete block walls, cracks in poured concrete, or building rooftops) and the specifications required by the customer.

[0042] For this reason, the present inventors considered that, in light of common technical knowledge, sufficient elasticity, etc. would be obtained for the above-mentioned applications, etc., if the polyurea resin (base material) is 100 to 160 parts by mass of polyisocyanate per 100 parts by mass of polyamine, as described above. Regarding waterproofing, no problems occurred with any of No. 1 to No. 5 in "Table 4."

[0043] In order to study how to impart flame retardancy (quasi-fire resistance) to this polyurea resin, the inventor prepared conventional fillers (ammonium polyphosphate, borax, expanded graphite (80 mesh: 175 to 177 microns)) that have been proposed in the past, and added them to a composition with an optimal mixture ratio of 100 parts by mass of polyamine and 110 parts by mass of polyisocyanate. (1) Whether or not a polyurea resin layer can be easily formed on the target object using conventional methods (2) Whether the formed polyurea resin layer exhibits flame retardancy (quasi-fire resistance) We considered the following.

[0044] The results are shown in Table 5 below. [Table 5]

[0045] As is clear from Table 5 above, a polyurea resin composition containing 20 parts by mass of ammonium polyphosphate as a filler can be made more flame-retardant than a non-containing composition, but it quickly dissolves when burned, and the flame-retardant (quasi-fireproof) effect is quickly lost. However, it is possible to form a polyurea resin layer using a conventional spraying method using a polyurethane spraying device.

[0046] Although a polyurea resin composition containing 20 parts by mass of borax (powder) as a filler can provide flame retardancy compared to a non-additive composition, it dissolves quickly when burned, and the flame retardancy (quasi-fire resistance) effect is quickly lost. However, it is possible to form a polyurea resin layer using a conventional spraying method using a polyurea spraying device. A polyurea resin composition containing 15 parts by mass of conventionally widely used expanded graphite (equivalent to 175-177 microns in 80 mesh) as a filler achieved extremely superior flame retardancy (semi-flame retardancy) compared to a composition without the addition of the graphite (confirmed here by hand application).

[0047] However, when attempting to form a layer of polyurea resin containing added expanded graphite (80 mesh) by spraying it onto an object using a conventional polyurethane spraying device, the polyurethane resin generated inside the polyurethane spraying device becomes highly pressurized, causing the large particle size of expanded graphite to adhere to the inside of the spray gun and the nozzle (approximately 1.5 mm) of the polyurethane spraying device, resulting in clogging. This is because the particle size of the expanded graphite itself is large (80 mesh) and the viscosity of the polyurea resin increases due to the addition of expanded graphite.

[0048] Based on the above results ("Table 5"), the present inventors have determined that expanded graphite is the most preferable filler for imparting flame retardancy (quasi-fire resistance) to polyurea resin. The inventors then investigated how to prevent the problem that occurs when using expanded graphite, namely, clogging that can occur inside the polyurethane spraying device (particularly the spray gun part), and to develop a polyurethane resin composition that allows spraying work to be performed using conventional polyurethane spraying devices as is.

[0049] Here, a polyurea spraying device that has been conventionally used to form a polyurea resin layer will be described. A known example of a conventional polyurea spraying device is the "Polyurea Sprayer" manufactured by Sham. The following "Table 6" shows the performance of the polyurea spraying equipment listed in the specifications for the Siamese Polyurea Spray Machine (PHX-3). [Table 6]

[0050] FIG. 1 is a diagram showing a schematic configuration of a general polyurethane spraying device 100 that has been used conventionally. The polyurea spraying device 100 includes a first tank 10 for storing polyisocyanate (agent A), a second tank 20 for storing polyamine (agent B), a compressor 40, and a spray gun device 50 for spraying a polyurea resin (polyurea resin composition) produced by mixing and stirring the polyisocyanate and polyamine onto an object.

[0051] The first tank 10 is connected to the spray gun device 50 by a first pipe 11 , and the second tank 20 is connected to the interior of the spray gun device 50 by a second pipe 21 .

[0052] A first pump 12 is provided in the first piping 11 between the first tank 10 and the spray gun device 50. In addition, a second pump 22 is provided in the second piping 21 between the second tank 20 and the spray gun device 50. The first pump 12 adjusts the pressure of the polyisocyanate supplied from the first tank 10 to the spray gun device 50 in response to a control signal from the compression adjustment mechanism 30. The second pump 22 adjusts the pressure of the polyamine supplied from the second tank 20 to the spray gun device 50 in response to a control signal from the compression adjustment mechanism 30. The compression adjustment mechanism 30 receives a command from the control unit 60 and outputs the control signal to the first pump 12 and the second pump 22, respectively. By using the first pump 12 and the second pump 22, the maximum pressure inside the spray gun device 50 can be adjusted to approximately 24 MPa (see "Table 6").

[0053] The polyisocyanate and polyamine pressurized by the first pump 12 and the second pump 22, respectively, are mixed and stirred inside the spray gun device 50, and a polyurea resin is produced. The compressor 40 is connected to the inside of the spray gun device 50 by a third pipe 41. Air compressed by the compressor 40 is supplied to the inside of the spray gun device 50.

[0054] A first heater 13 is disposed in the first pipe 11, and the temperature of the polyisocyanate supplied from the first tank 10 to the inside of the spray gun device 50 can be adjusted to a desired temperature (at least 60 to 80 degrees Celsius). The temperature of the polyisocyanate heated by the first heater 13 is maintained by a hose heater 14 (maximum heating value is 88 degrees Celsius: see Table 6).

[0055] Further, a second heater 23 is disposed in the second pipe 21, and the temperature of the polyamine supplied from the second tank 20 to the inside of the spray gun device 50 can be adjusted to a desired temperature (60 to 80 degrees Celsius). The polyamine heated by the second heater 23 is maintained at that temperature by a hose heater 24 (maximum heating value is 88 degrees Celsius: see Table 6).

[0056] Based on the switching state of the switch SW, the control unit 60 recognizes whether or not expanded graphite has been added to the isocyanate (agent A), whether or not expanded graphite has been added to the polyamine (agent B), the amount of expanded graphite added, etc., and based on this information, appropriately controls the pressure of the polyurea resin by the first pump 12 and the second pump 22 and the temperature of the polyurea resin by the first heater 13 and the second heater 23.

[0057] In this embodiment, expanded graphite (filler) with a particle size of 100 mesh is added to polyisocyanate (Part A). For this reason, the temperature of the polyisocyanate is adjusted to 70 to 80 degrees Celsius by the first heater 13. The polyamine to which no expanded graphite is added is adjusted to a lower temperature (60 to 70 degrees Celsius) than the polyisocyanate by the second heater 23.

[0058] The reason for adjusting the temperature of the polyisocyanate containing expanded graphite to be higher than that of the polyamine containing no expanded graphite is to suppress the increase in viscosity caused by the addition of expanded graphite by increasing the temperature. At this time, the polyurea resin produced inside the spray gun device 50 is generally between 60°C and 80°C.

[0059] If expanded graphite with a particle size of 100 mesh is added only to polyamine, the temperature of the polyamine should be set to 70 to 80 degrees Celsius, and the temperature of the polyisocyanate should be set to 60 to 70 degrees Celsius. In this case, the temperature of the polyurea resin produced inside the spray gun device 50 will be generally between 60 and 80 degrees Celsius. In this way, by increasing only the temperature of the solvent (agent A in this case), whose viscosity increases due to the addition of expanded graphite with a particle size of 100 mesh, it is possible to reduce the amount of electricity required for heating.

[0060] Furthermore, if expanded graphite is added to both the polyisocyanate (agent A) and the polyamine (agent B), the viscosity of both can be kept low by setting the temperatures of both the polyisocyanate and the polyamine to 70 to 80 degrees Celsius. In this case, the temperature of the polyurea resin produced inside the spray gun device 50 will be approximately 70 to 80 degrees Celsius.

[0061] The polyisocyanate (agent A) pressurized by the first pump 12 and heated by the first heater 13, and the polyamine (agent B) pressurized by the second pump 22 and heated by the second heater 23 are both fed into the spray gun device 50, where they are mixed and stirred (impingement mixing), and a polyurea resin is produced by a chemical reaction.

[0062] The polyurethane resin produced by mixing and stirring inside the spray gun device 50 is mixed with compressed air supplied from the compressor 40, and when the trigger 52B of the gun part 52 is pulled, it is released from the nozzle 52A and sprayed in the form of a mist.

[0063] At this time, the polyurethane resin produced by mixing and stirring inside the spray gun device 50 is kept at a predetermined temperature (60 to 80 degrees Celsius) and has low viscosity, so when the nozzle 52A (diameter 1.5 mm) is opened, it is sprayed at the desired flow rate (10 L / min in the first embodiment) (the polyurethane resin is at 23.5 to 24.0 MPa inside the spray gun device 50). The expanded graphite added at this time has a small particle size, and the viscosity of the polyurea resin is also low, so clogging does not occur inside the spray gun device 50 (especially the injection port 52A).

[0064] In this way, in the polyurea spraying device 100, the polyisocyanate (component A) and polyamine (component B) can be heated and adjusted to the desired temperature inside the spray gun device 50, making it possible to stabilize the reaction conditions (resin reaction) between the polyisocyanate (component A) and polyamine (component B).Furthermore, by adjusting the temperature of the polyisocyanate (component A) or polyamine (component B) to which expanded graphite has been added to a high temperature, it is possible to prevent the viscosity from increasing due to the addition of expanded graphite.

[0065] Incidentally, if the ratio of expanded graphite added to polyisocyanate is the same, it is thought that the flame retardancy will decrease in proportion to the decrease in particle size (100 mesh or smaller). Therefore, in order to achieve the same flame retardancy (quasi-fire resistance) as when conventional expanded graphite with a relatively large particle size (particle size of 80 mesh or larger) is added (15 parts by mass of expanded graphite for 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate = "Table 5"), it is necessary to increase the amount of expanded graphite added to compensate for the smaller particle size (30 parts by mass of expanded graphite for 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate).

[0066] Increasing the amount of expanded graphite added in this way increases the viscosity of the polyurethane resin produced by mixing and stirring, but in this embodiment, the polyurethane resin produced by mixing and stirring is adjusted to a high temperature (60 to 80 degrees Celsius), so the viscosity can be kept low and it can be sprayed from the spray gun device 50 of the polyurethane spraying device 100.

[0067] Furthermore, if it is acceptable to weaken the flame retardant (quasi-fireproof) effect of the expanded graphite somewhat, the amount of expanded graphite added can be the same as when conventional expanded graphite with a large particle size is used (15 parts by mass of expanded graphite per 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate).

[0068] If 15 parts by mass of conventionally used 80-mesh particle size expanded graphite is added to 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate, the time until the polyurea resin carbonizes without generating a flame will be 60 seconds (see Table 5), but if the same amount (15 parts by mass) of 100-mesh expanded graphite is used, the time until the polyurea resin carbonizes without generating a flame will be slightly shorter, at around 30 seconds (see Table 7 below).

[0069] As explained above, in this first embodiment, in order to be able to use conventional polyurea spray equipment (nozzle diameter 1.5 mm, pressure capacity 23.5 to 24.0 MPa, temperature adjustment possible up to 88 degrees Celsius = "Table 6") as is, the particle size of the expanded graphite added to the polyurea resin is made small (particle size 100 mesh), and the amount added is set to 15 to 30 parts by mass per 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate. The polyurea resin produced by mixing and stirring the polyisocyanate and polyamine is then heated and maintained at 60 to 80 degrees Celsius inside the spray gun device, whereby the polyurea resin can be sprayed onto an object to form a polyurea resin layer of a desired thickness. This process does not cause clogging in the polyurea spray device 100 (particularly inside the spray gun device 50).

[0070] The inventors have confirmed the flame retardancy (quasi-fire resistance) of a polyurea resin layer having a predetermined thickness (here, 2 mm) formed on an object using a polyurea resin (polyurea resin composition) to which expanded graphite with a particle size of 100 mesh has been added (combustion experiment). The experimental results are shown in Table 7 below.

[0071] As mentioned above, the ratio of polyamine to polyisocyanate that fully exhibits the inherent properties (elasticity) of polyurea is 100 parts by mass of polyamine to 100 to 160 parts by mass of polyisocyanate, so a polyurea resin composition with the following ratio was prepared. (1) 100 parts by mass of polyamine, 100 parts by mass of polyisocyanate, 15 parts by mass of expanded graphite = (Sample 1) (2) 100 parts by mass of polyamine, 100 parts by mass of polyisocyanate, 30 parts by mass of expanded graphite = (Sample 2) (3) 100 parts by mass of polyamine, 160 parts by mass of polyisocyanate, 15 parts by mass of expanded graphite = (Sample 3) (4) 100 parts by mass of polyamine, 160 parts by mass of polyisocyanate, 30 parts by mass of expanded graphite = (Sample 4)

[0072] Each of the above polyurea resin compositions (samples 1 to 4) was formed on a target object (a 20 cm x 20 cm concrete plate) to a film thickness of approximately 2 mm, and this was left at room temperature (approximately 20°C) for 6 hours to allow it to dry thoroughly. In this combustion experiment, it was sufficient to confirm the flame retardancy (quasi-fire resistance) of the polyurea resin when expanded graphite with a particle size of 100 mesh was added at a certain ratio (15 to 30 parts by mass of expanded graphite to 100 parts by mass of polyamine and 10 to 160 parts by mass of polyisocyanate), so for convenience, a polyurea resin layer was formed by so-called "hand painting" and its flame retardancy (quasi-fire resistance) was confirmed.

[0073] Concrete plates 1 to 4, each with a 2 mm thick polyurea resin layer of different composition (Sample 1 to Sample 4), were placed vertically, and their surfaces were burned with a commercially available torch burner. The tip of the torch burner's flame was positioned so that it was in contact with the concrete plate. The combustion time elapsed and the combustion results for each of the concrete panels 1 to 4 are shown in Table 7 below.

[0074] In order to confirm the flame retardancy (quasi-fire resistance) obtained in the first embodiment, a 20 cm x 20 cm concrete plate 5 was prepared, on the surface of which a 2 mm thick layer of polyurethane resin (sample 5) containing 80 mesh expanded graphite was formed. [Table 7]

[0075] As is clear from the experimental results in Table 7, in both cases where the polyurea resin layer was formed using Sample 1 and Sample 2, in which 15 parts by mass and 30 parts by mass of expanded graphite (100 mesh) were added to a polyurea resin base material consisting of 100 parts by mass of polyamine and 100 parts by mass of polyisocyanate, respectively, no fire occurred until 30 to 60 seconds had elapsed. This was almost the same result as the experimental result (60 seconds) of Sample 5, in which 30 parts by mass of 80 mesh expanded graphite was used as a filler.

[0076] Furthermore, in both cases where the polyurea resin layer was formed using Sample 3 and Sample 4, in which 15 parts by mass and 30 parts by mass of expanded graphite (100 mesh) were added to a polyurea resin base material consisting of 100 parts by mass of polyamine and 160 parts by mass of polyisocyanate, respectively, no fire occurred until 30 to 60 seconds had elapsed. This was almost the same result as the experimental result (60 seconds) of Sample 5, in which 30 parts by mass of 80 mesh expanded graphite was used as a filler.

[0077] Furthermore, there was no apparent difference in the state of the sample surface after a certain period of combustion between Samples 1 to 4 and Sample 5. From these findings, it was found that even if the particle size of the expanded graphite was changed from the conventional 80 mesh (175 to 177 microns) to 100 mesh (147 to 149 microns), a polyurea resin layer with a thickness of approximately 2 mm could adequately withstand combustion for 30 to 60 seconds.

[0078] As described above, even when 15 to 30 parts by mass of 100-mesh expanded graphite as a filler was added to a polyurea resin base material in which 100 to 160 parts by mass of polyisocyanate was mixed with 100 parts by mass of polyamine (polyurea resin composition), and this was sprayed to form a polyurea resin layer, excellent flame retardancy (quasi-fire resistance) equivalent to that obtained when expanded graphite with a large particle size (80 mesh or larger particle size) was used as a filler was obtained.

[0079] A polyurea resin (base material) containing 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate to which 15 to 30 parts by mass of expanded graphite is added is produced by mixing and stirring in a conventionally used polyurea spraying device 100. The produced polyurethane resin is heated and adjusted to 60 to 80 degrees Celsius within the spray gun device 50 of the polyurethane spraying device 100, thereby keeping its viscosity low and enabling it to be sprayed sufficiently onto the target object from the nozzle (diameter 1.5 mm). At this time, by adjusting the pressure of the polyurethane resin inside the spray gun device 50 to 23.5 to 24.0 MPa, the amount of the resin sprayed from the nozzle 52A can be set to 10 L / min.

[0080] The smaller the amount of expanded graphite added, the less likely it is that the inherent properties of the formed polyurea resin layer will be impaired, and the less expanded graphite required, the lower the production costs. Therefore, depending on the intended use, by using 15 parts by mass of expanded graphite for 100 parts by mass of polyamine and 100 to 160 parts by mass of polyisocyanate, it is possible to impart non-combustibility (quasi-fire resistance) to the formed polyurea resin layer while reducing production costs.

[0081] In the first embodiment, the particle size of the expanded graphite is described as 100 mesh, but even if the particle size is smaller than 100 mesh, it is still possible to spray the polyurethane resin using the conventional polyurethane spraying device 100. This is because if the particle size becomes even smaller, there is no risk of clogging in the polyurea spraying device 100 (particularly inside the spray gun device 50). If the viscosity increases due to the addition of expanded graphite, the temperature of the solution (A or B) to which the expanded graphite has been added can be adjusted even higher (for example, to nearly 88°C in the case of the polyurea spraying device in Table 6).

[0082] When the particle size of the expanded graphite is made smaller in this way, it is possible to increase the amount added to achieve sufficient flame retardancy (quasi-fire resistance). In this case, however, by further increasing the adjustment temperature of the polyurethane resin produced by mixing and stirring, it becomes possible to spray the resin from the spray gun device 50 while keeping the viscosity low.

[0083] In the above-described embodiment, an example in which expanded graphite having a particle size of 100 mesh is added to isocyanate has been mainly described, but it goes without saying that expanded graphite may be added only to polyamine, or may be added to both polyisocyanate and polyamine.

[0084] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In this second embodiment, the non-combustible powder added to the base material consisting of polyamine and polyisocyanate (the same high purity base material as in the first embodiment is used in this second embodiment) contains at least the following: (A) Expanded graphite (particle size 100 mesh) (B) Brominated flame retardants (C) Melamine polyphosphate (D) Silica powder

[0085] The particle size of the expanded graphite was set to be smaller than 100 mesh so that a polyurethane resin layer could be formed using the polyurethane spraying device 100 of the first embodiment. Incidentally, by appropriately modifying the design of the polyurethane spraying device 100 in terms of the spraying pressure, temperature adjustment, and size of the opening, it is also possible to make the particle size of the expanded graphite approximately 80 mesh.

[0086] The optimum ratios of the components (A) to (D) in the noncombustible powder are as follows: (A) Expanded graphite: 40 parts by mass (B) Brominated flame retardant: 80 parts by mass (C) Melamine polyphosphate: 80 parts by mass (D) Silica powder: 100 parts by mass

[0087] The amount (percentage) of such a "non-flammable powder" to be added to the base material (base material composition) of a polyurea resin consisting of polyamine and polyisocyanate depends on the level of "non-flammability (quasi-fire resistance)" that is to be achieved in the polyurea resin layer that is actually formed by the spraying method.

[0088] Therefore, the inventors changed the ratio of the "non-combustible powder" added to the base material (polyamine and polyisocyanate) of the polyurea resin as shown in (2) to (6) below, and conducted combustion experiments to confirm the degree to which "non-combustible (quasi-fireproof)" could be achieved at each ratio. In conducting the following combustion experiments, (A) the expanded graphite used was "9510045 (-100mesh)" from Ito Graphite Industries, (B) the brominated flame retardant was "Fireguard (FG8500)" from Teijin Limited ("Fireguard" is a registered trademark of Teijin Limited), and (C) the melamine polyphosphate used was "EXOLIT AP462" from Clariant Chemicals Co., Ltd. ("EXOLIT" is a registered trademark of Clariant Produkte (Deutschland) Gesellschaft mit Beschlenkter Haftung). As for (D) silica powder, commercially available general silica powder (fine silicon dioxide, low melting point glass powder) was used. (1) 0% (Figure 2) (2) 15% (Figure 3) (3) 20% (Figure 4) (4) 25% (Figure 5) (5) 30% (Figure 6) (6) 40% (Figure 7)

[0089] For the combustion experiments, samples were prepared by forming a polyurethane resin layer of approximately 3 mm thickness on the surface of a 300 mm x 300 mm, 9 mm thick plywood board using a polyurethane resin (1) without added flame retardant powder and polyurethane resins (2) to (6) with added flame retardant powder (Figs. 2 to 7). For the combustion experiments, samples were prepared by so-called "hand painting," but the polyurethane resin layer formed by the "spraying method" using the polyurethane spraying device 100 has better film uniformity than the polyurethane resin layer formed by "hand painting," which can cause unevenness, and is superior in terms of the essential properties of the polyurethane resin layer and the non-combustibility (quasi-fire resistance) of the present invention.

[0090] The results of a combustion experiment conducted for 120 seconds (2 minutes) using each of the samples (1) to (6) prepared above are shown in FIGS. 2 to 7. In the combustion experiment, each sample (1) to (6) was placed vertically and a flame from a torch burner was applied vertically from a position 150 mm away from the combustion surface for 2 minutes (the temperature of the burner was approximately 1200 degrees).

[0091] In the case of (1) (0%) where the "non-combustible powder" according to the second embodiment is not added, as shown in FIG. 2, discoloration begins at the point where the burner flame hits after 15 seconds, and after 30 seconds, smoke begins to rise and dripping also begins. After 60 seconds, the dripping becomes more pronounced and smoke increases. After 1 minute 30 seconds, the dripping becomes more intense, and the base of the plywood becomes visible, and after 1 minute 50 seconds, the fire begins to spread.

[0092] In the case of (2), where 15% "non-combustible powder" was added, as shown in Figure 3, 10 seconds after the start of combustion, the area where the burner flame hit began to swell, and at 30 seconds, the swelling increased, carbonization progressed, and dripping began due to the melting of the resin (a flame appeared briefly during this time, but it quickly disappeared and did not spread). At 60 seconds, the dripping became more pronounced and the flame grew larger (also did not spread). At 1 minute 20 seconds, the dripping became even more intense, and the base of the plywood began to become visible, and at 1 minute 30 seconds, the resin where the burner flame hit melted off, burning part of the plywood, but the polyurethane resin layer itself did not spread to the fire.

[0093] In the case of (3), which contained 20% "non-combustible powder," as shown in Figure 4, 10 seconds after the start of combustion, carbonization began at the point where the burner flame hit, and at 20 seconds, carbonization progressed and swelling increased around that point (a flame briefly appeared at this point, but quickly went out). Dripping began at 30 seconds, and at 60 seconds, the dripping became noticeable. At 1 minute 30 seconds, the dripping became even more noticeable, and occasional flames became noticeable (even in this case, the flame did not spread to the polyurethane resin). At 2 minutes, the dripping intensified, and the expansion due to carbonization of the burning surface also became severe (the flame still did not spread). Sufficient non-combustibility (quasi-fire resistance) was achieved throughout.

[0094] In the case of (4), which contained 25% "non-combustible powder," as shown in Figure 5, 10 seconds after the start of combustion, the area where the burner flame hit changed color (carbonization barely began), and 30 seconds later, carbonization became noticeable (a flame appeared for a moment, but quickly disappeared, and there was no dripping). The condition remained almost unchanged from 30 to 60 seconds. Although dripping became noticeable at 1 minute 30 seconds, there was no significant change in the burning surface (the area where the burner flame hit). There was no significant change from 1 minute 30 seconds to 2 minutes after the start of combustion, and the burning surface merely expanded. Although dripping of the resin occurred throughout the entire test, sufficient non-combustibility (quasi-fire resistance) was achieved, even compared to the case of (3).

[0095] In the case of (5), in which 30% "non-combustible powder" was added, as shown in Figure 6, 10 seconds after the start of combustion, there was a slight discoloration, mainly in the area where the burner flame hit (carbonization barely began). Up until 30 seconds, there was almost no change, and carbonization only progressed slightly. At 60 seconds, carbonization became noticeable (a flame appeared for a moment, but quickly disappeared, and no dripping occurred). At 1 minute 30 seconds, a large flame appeared for a moment, but quickly disappeared and did not spread. After 1 minute 30 seconds, even after 2 minutes, there was no dripping, and there was almost no change in the burning surface (the area where the burner flame hit).

[0096] In the case of (6), where 40% of the "non-combustible powder" was added, the results were almost the same as when the 30% was added as mentioned above, except that the discoloration of the burning surface and the extent of the carbonization were slightly narrower than when the 30% was added. In this way, whether the non-flammable powder was 30% or 40% of the base material (base material composition) of a polyurea resin made from polyisocyanate and polyamine, no noticeable flames or smoke were generated during the at least two-minute combustion test, and extremely excellent non-flammability (quasi-fire resistance) was achieved. Moreover, the discoloration and carbonization caused by the burner flame did not spread over time, and no resin dripping occurred.

[0097] Based on the above, if the purpose is simply to prevent the combustion of the polyurethane resin itself during combustion, the amount of "non-combustible powder" added may be approximately 15 parts by mass (15%) per 100 parts by mass of the polyurethane resin base material. Furthermore, if you want to achieve non-combustibility (quasi-fire resistance) that is sufficient to prevent the spread of flames in the polyurethane resin layer for a certain period of time or longer, it is clear that the amount of "non-combustible powder" added should be approximately 20 parts by mass (20%) per 100 parts by mass of the polyurethane resin base material. Furthermore, if you want to achieve non-combustibility (semi-fire resistance) that not only prevents the "spread of flames" but also suppresses carbonization and expansion of the burning surface and also suppresses dripping, the amount of "non-combustible powder" to be added should be approximately 25 parts by mass (25%) per 100 parts by mass of the polyurea resin (base material).

[0098] Furthermore, to achieve a level of non-combustibility (quasi-fire resistance) that prevents the spread of flames, suppresses carbonization and expansion of the burning surface, and prevents dripping, the amount of "non-combustible powder" added should be 30 parts by mass (30%) per 100 parts by mass of polyurea resin (base material). In this case, throughout a two-minute combustion test, the polyurea resin layer showed almost no deformation during combustion. Furthermore, adding 40% non-combustible powder does not differ in non-combustibility (quasi-fire resistance) from adding 30%. Therefore, to maintain the inherent properties of polyurea resin, impurities should be kept as low as possible, and further, considering the cost of forming the polyurea resin layer, adding 30% non-combustible powder is sufficient.

[0099] When the non-flammable (semi-fireproof) polyurethane resin described above is actually sprayed onto an object, the polyurethane spraying device 100 of the first embodiment can be used (FIG. 1). This is because the "expanded graphite" added to the "non-combustible powder" in this second embodiment is 100 mesh.

[0100] The following method is used to spray a polyurea resin (polyurea resin composition) containing "non-combustible powder" onto an object using the polyurea spraying device (spraying device) 100. Note that the configuration and operation of the polyurea spraying device 100 have been explained in the first embodiment, and therefore detailed explanations thereof will be omitted in this second embodiment. (1) First, a desired amount of non-combustible powder (15% to 40% in this embodiment) is added to at least one of polyamine and polyisocyanate. (2) The polyamine and polyisocyanate are mixed and stirred to produce a polyurea resin, which is then heated to a temperature between 60 and 80 degrees Celsius. (3) The polyamine and polyisocyanate are mixed and stirred to produce a polyurea resin, which is then pressurized to a predetermined pressure. (4) The polyurethane resin, which has been heated to 60 to 80 degrees Celsius and pressurized to a predetermined pressure, is sprayed onto the object.

[0101] In this case, when heating the polyamine and polyisocyanate, if a non-flammable powder is added to the polyisocyanate, the polyisocyanate is heated to 70 to 80 degrees Celsius. On the other hand, when non-combustible powder is added to the polyamine, the polyamine is heated to 70 to 80 degrees Celsius. This heating is performed by heaters 13 and 23 provided in the polyurea spraying device 100.

[0102] As mentioned above, this polyurethane spraying device 100 has a nozzle diameter of 1.5 mm and the specified pressure is 23.5 MPa to 24.0 MPa, so even if a non-combustible powder containing expanded graphite with a particle size of 100 mesh (or smaller) is added to the polyurethane resin base material (base material composition), the polyurethane spraying device 100 can be used to form a uniform polyurethane resin layer on the target object.

[0103] Furthermore, with the polyurea spraying device 100, when a non-flammable powder is added to a polyisocyanate, the viscosity can be reduced by heating the polyisocyanate to 70 to 80 degrees Celsius. Similarly, when a non-flammable powder is added to a polyamine, the viscosity can be reduced by heating the polyamine to 70 to 80 degrees Celsius. This reduces the overall viscosity of the polyurea resin (polyurea resin composition). Even when a non-flammable powder containing expanded graphite with a particle size of 100 mesh (or smaller) is added to the polyurea resin matrix, the polyurea resin (polyurea resin composition) can be uniformly sprayed onto an object. The polyurea resin layer formed by uniform spraying achieves excellent non-flammability (quasi-fire resistance) without impairing the inherent properties of the polyurea resin.

[0104] Furthermore, the spraying method using this polyurethane spraying device 100 can efficiently form a polyurethane resin layer as needed at the work site where the object is located, dramatically improving the efficiency of the work of forming / installing a non-flammable (semi-fireproof) polyurethane resin layer. [Explanation of symbols]

[0105] 10 First Tank 11 First Pipe 12 First pump (first pressurizing means) 13 First heater (first heating means) 14,24 Hose heater 20 Second Tank 21 Second Pipe 22 Second pump (second pressurizing means) 23 Second heater (second heating means) 30 Compression adjustment mechanism 40 Compressor (compression means) 41 Third Pipe 50 Spray gun device (generation means, injection means) 52 Gun Club 52A injection port 52B Trigger 60 Control Unit SW switch

Claims

1. A non-flammable powder to be added to a base composition consisting of a polyamine and a polyisocyanate, characterized in that the non-flammable powder contains the following components (A), (B), (C), and (D). (A) Expanded graphite (B) Brominated flame retardants (C) Melamine polyphosphate (D) Silica powder

2. The noncombustible powder according to claim 1, characterized in that the component (A) is 40 parts by mass, the component (B) is 80 parts by mass, the component (C) is 80 parts by mass, and the component (D) is 100 parts by mass.

3. A polyurea resin composition comprising the following components (a), (b), (c), (d), and (e). (A) A base composition comprising a polyamine and a polyisocyanate (a) Expanded graphite (c) Brominated flame retardants (d) Melamine polyphosphate (E) Silica powder

4. The polyurethane resin composition according to claim 3, characterized in that the total amount of the components (b) to (e) is 15 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the component (a).

5. 5. The polyurethane resin composition according to claim 3, wherein the total amount of the components (b) to (e) is 25 parts by mass or more per 100 parts by mass of the component (a).

6. 4. The polyurethane resin composition according to claim 3, wherein the total amount of the components (b) to (e) is 30 parts by mass per 100 parts by mass of the component (a).

7. 7. The polyurea resin composition according to claim 3, wherein the components (a), (b), (c), (d), and (e) are blended in a ratio of 4:8:8:

10.

8. A method for forming a polyurea resin layer, comprising spraying a polyurea resin composition obtained by adding the noncombustible powder according to claim 1 or 2 to a base composition comprising a polyamine and a polyisocyanate onto an object to form a polyurea resin layer having a desired thickness, adding the fire-retardant powder to at least one of polyamine and polyisocyanate; a step of heating the polyamine and the polyisocyanate so that the temperature of the polyurea resin produced by mixing and stirring the polyamine and the polyisocyanate is between 60°C and 80°C; a step of pressurizing the polyamine and the polyisocyanate so that the pressure of the polyurea resin produced by mixing and stirring the polyamine and the polyisocyanate reaches a predetermined pressure; A method for forming a polyurea resin layer, comprising the steps of: heating the polyurea resin to 60 to 80 degrees Celsius and pressurizing it to the predetermined pressure; and spraying the polyurea resin onto an object.

9. 9. The method for forming a polyurea resin layer according to claim 8, wherein in the step of heating the polyamine and the polyisocyanate, when the non-flammable powder is added to the polyisocyanate, the polyisocyanate is heated to 70 to 80 degrees Celsius, and when the non-flammable powder is added to the polyamine, the polyamine is heated to 70 to 80 degrees Celsius.

10. a first tank for accommodating a polyisocyanate, a second tank for accommodating a polyamine, a first heating means for adjusting the temperature of the polyisocyanate supplied from the first tank, a second heating means for adjusting the temperature of the polyamine supplied from the second tank, a first pressurizing means for pressurizing the polyisocyanate supplied from the first tank, a second pressurizing means for pressurizing the polyamine supplied from the second tank, a compression means for compressing a gas, a generation means for mixing and stirring the polyisocyanate and the polyamine to generate a polyurea resin, and a spray means having a spray nozzle and spraying the generated polyurea resin from the spray nozzle, When a polyurea resin composition obtained by adding the noncombustible powder according to claim 1 or 2 to a base composition comprising a polyamine and a polyisocyanate is sprayed onto an object to form a polyurea resin layer, maintaining the temperature of the polyurethane resin in the injection means at 60 to 80 degrees Celsius by the first heating means and the second heating means; pressurizing the polyurethane resin in the injection means to a predetermined pressure by the first pressurizing means and the second pressurizing means; The method for forming a polyurea resin layer comprises spraying the pressurized polyurea resin from the nozzle onto an object to form a polyurea resin layer.

11. 11. The method for forming a polyurea resin layer according to claim 10, wherein the diameter of the injection nozzle is 1.5 mm, and the predetermined pressure is 23.5 MPa to 24.0 MPa.

12. the first heating means heats the polyisocyanate to 70 to 80 degrees Celsius when the nonflammable powder is added to the polyisocyanate; 12. The method for forming a polyurea resin layer according to claim 10, wherein the second heating means heats the polyamine to 70 to 80 degrees Celsius when the non-flammable powder is added to the polyamine.

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