Method for producing thermosetting foam with excellent flame retardancy and thermosetting foam using the same

Abstract

To provide a method for manufacturing thermosetting expanded foam having excellent flame retardancy, and thermosetting expanded foam using the same.MEANS FOR SOLVING THE PROBLEM: There is provided a method for manufacturing thermosetting expanded foam which includes: preparing a polyol-based compound mixed with a trimerization catalyst or an isocyanurate compound; preparing a mixture containing the polyol-based compound, a foam stabilizer, a flame retardant and a catalyst; preparing a mixture solution by adding nanoclay to the mixture; applying ultrasonic waves or high pressure to the mixture solution to expand the interlayer space of the nanoclay and to allow the mixture in the mixture solution to be intercalated into the expanded interlayer space of the nanoclay; adding a foaming agent to the resultant mixture solution; adding an isocyanate-based compound to the aforementioned resultant mixture solution; subjecting the polyol-based compound and the isocyanate-based compound to a chain reaction in the expanded interlayer space of the nanoclay; and allowing exfoliation of the nanoclay to occur by further expansion of the expanded interlayer space of the nanoclay through rapid increases in molecular weight and volume due to a urethane structure, a urea structure and an isocyanurate structure, which are produced as a result of the reaction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thermosetting foam and a thermosetting foam produced using the same. More particularly, the present invention relates to a method for producing a thermosetting foam with excellent flame retardancy, in which nanoclay is mixed with a polyol compound using ultrasound, an isocyanate compound is added, and a trimerization catalyst or an isocyanurate compound is mixed with the polyol compound to form an isocyanurate structure, in order to provide a polyurethane foam for construction with excellent flame retardancy, and a thermosetting foam produced using the same. [Background technology]

[0002] The Ministry of Land, Infrastructure, and Transport of the Republic of Korea (ROK) revised the "Regulations on Standards for Evacuation / Fire Prevention Structures of Buildings" to significantly strengthen fire stability standards for building finishing materials, which came into effect in April 2016. In particular, recent large-scale fires have resulted in numerous casualties and property damage, drawing attention to insulation materials with excellent fire stability and thermal insulation properties. However, despite this demand, the manufacturing technology for flame-retardant insulation materials and the supply of products utilizing these materials are currently limited. Materials used for building insulation include expanded polystyrene (EPS) foam, glass fiber, phenolic foam, polyurethane (PU), and polyisocyanurate (PIR) foam. While EPS foam is the most commonly used insulation material, its high flammability has led to its being cited as a major cause of large-scale fires. Glass fiber has poor insulation properties and is designated as a harmful substance to the human body, limiting its use. Phenolic foam is gaining attention as an organic insulation material with excellent thermal insulation and flame retardancy, but its thermal insulation performance drops significantly when it absorbs moisture, and it generates acids that can corrode surrounding building materials. It also has poor adhesion to the surface of building materials, making installation difficult. PU and PIR foams excel in many areas, including thermal insulation, water resistance, processability, and installation, but have the problem of relatively poor flame retardancy and relatively poor ability to prevent the spread of fire in the event of a fire.

[0003] The PU and PIR foam industry has recently been actively working to address the flame-retardant performance issue. There are various methods for making materials flame-retardant. One is the application of an expanding agent, which induces expansion at high temperatures during combustion, forming a flame-blocking film. Expanding agents can be divided into organic and inorganic. Organic expanding agents have a low specific gravity and are highly compatible with organic materials such as PU and PIR, making them easy to process. However, due to their organic nature, they are easily flammable and have poor flame-retardant properties. Inorganic expanding agents have excellent flame-retardant properties. However, they have a high specific gravity and a high degree of heterogeneity with organic materials, making them prone to phase separation, such as precipitation. Furthermore, while they provide a temporary flame barrier during combustion, continued exposure to flames causes the foam to melt and collapse, resulting in a loss of flame-retardant properties. Another method for making materials flame-retardant is the addition of a flame retardant. Organic flame retardants have the disadvantage of generating gases harmful to humans during combustion. Inorganic flame retardants have the problem of deteriorating mechanical and physical properties, and the introduction of these flame retardants alone is far from satisfying the current fire stability requirements for building finishing materials.

[0004] To solve the above problems, it is important to maximize flame retardancy while maintaining mechanical and physical properties through the addition of flame retardants or flame retardant additives. Recently, nanocomposite materials containing a variety of nanoparticles have been developed, and research results have shown that the appropriate dispersion of nanoclay within these materials improves flame retardancy above a certain level. The flame retardancy of nanoclay is achieved by inserting and exfoliating nanoclay particles with a large aspect ratio, which increases the contact area with the resin, thereby blocking heat in a fire situation. Its performance is achieved by effectively preventing the diffusion of particles.

[0005] However, unless the technology to effectively disperse, insert, and exfoliate nanoclay within these materials is perfected, nanoclay will remain nothing more than a simple inorganic flame retardant, and instead of improving flame retardancy, it may have the opposite effect of reducing mechanical and physical properties. Furthermore, performance can only be maximized if the underlying material itself has a certain degree of flame retardancy. Researchers at some overseas companies and institutions have attempted to improve flame retardancy by dispersing nanoclay in the basic formulation of PU, but the benefits were significantly lower compared to the additional process costs, preventing mass production and often resulting in research being the end of the road.

[0006] The nanoclay has a basic structure of silica tetrahedrons and alumina octahedrons, which are composed of silicon, aluminum, magnesium, oxygen, etc., and is layered in a ratio of 1:1 or 1:2 by plate-like bonding between these tetrahedrons. Each layer has a thickness of 1 to 10 nm, a length of 30 to 1000 nm, and an interlayer spacing of several angstroms (1 angstrom = 10 nm). do.

[0007] Dispersion methods for inserting and exfoliating resin between the nanoclay layers include solution dispersion, melting, and ultrasonic methods. The solution dispersion method is a method in which the nanoclay expands between layers as it swells in liquid form, and then the resin is stirred to induce interlayer insertion. The problem with this method is that the nanoclay is aggregated by the Van der Waals attractive force acting between the layers, so the intercalation efficiency is very low and exfoliation is even more difficult. The melting method has the restriction that a thermoplastic resin that can be melted at a processing temperature of 200°C or less must be used. However, it is difficult to apply this method to thermosetting foams. The ultrasonic method involves applying ultrasound above a certain level to maximize the expansion of the nanoclay layers, allowing the resin to be inserted between them and exfoliated. The efficiency of nanoclay interlayer insertion and exfoliation changes depending on the intensity of the ultrasound, so control is essential. The resin must be liquid, and if the viscosity exceeds a certain level, it will not be effective. Even if nanoclay is organically treated, it contains a minimum amount of water. Therefore, the resin must not be reactive with water, otherwise it may induce irreversible changes over time and impair physical properties.

[0008] In Korean Patent Applications Nos. 10-2017-0085232, 10-2011-0031592, 10-2010-0082116, 10-2007-0122780, 10-2002-0083028, and 10-2002-0083066, a solution dispersion method was used to intercalate resin between nanoclay layers. As mentioned above, nanoclay aggregates due to interlayer van der Waals forces, resulting in low resin intercalation efficiency and even more difficult exfoliation, resulting in insufficient effectiveness. In Korean Patent Applications Nos. 10-2007-0140846, 10-2005-0012348, and 10-2005-0000687, nanoclay was mixed with an isocyanate-based resin and ultrasonic waves were applied to induce the intercalation of the resin. However, isocyanate resins react irreversibly with even very small amounts of moisture contained in nanoclay, resulting in changes over time. Even if the nanoclay is dried, moisture cannot be completely removed, and even if it is completely dried, nanoclay aggregation makes it difficult to insert the nanoclay using ultrasound alone. Furthermore, this is different from the objective of the present invention, which is to maximize flame retardancy using nanoclay.

[0009] Patent Document 1 (Korea Patent Publication No. 10-2015-0063990) proposes a thermosetting foam with improved flame retardancy containing an isocyanurate structure using a trimerization catalyst. Although this is an excellent base material for the thermosetting foam, the nanoclay was applied using a dispersion method involving solution stirring, which resulted in a decrease in effectiveness rather than a full realization. On the other hand, flame retardant technology for organic insulation is very important when considering the trend of fire safety and stricter regulations. There is no insulation material found anywhere that is made up of a single material and weighs less than 0.5 g. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Republic of Korea Patent Publication No. 10-2015-0063990 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve the above problems, and aims to provide a method for producing a thermosetting foam having excellent flame retardancy, in which nanoclay is mixed with a polyol compound using ultrasound, an isocyanate compound is added, and the polyol compound and the isocyanate compound react with each other between the layers of dispersed nanoclay, and the resulting structure further expands the spaces between the layers of dispersed nanoclay, resulting in complete exfoliation, and a thermosetting foam produced using the same method. [Means for solving the problem]

[0012] As a means to solve the above-mentioned problems, The method for producing a thermosetting foam having excellent flame retardancy of the present invention includes the steps of: (1) preparing a polyol-based compound mixed with a trimerization catalyst or an isocyanurate compound; (2) preparing a mixture containing the polyol compound, a foam stabilizer, a flame retardant, and a catalyst; (3) mixing nanoclays to prepare a mixed solution; (4) applying ultrasonic waves or high pressure to disperse the nanoclay between its layers, and the mixture is inserted between the dispersed nanoclay layers; (5) adding a blowing agent; (6) adding an isocyanate compound; (7) A step of in-situ chain reaction of a polyol-based compound and an isocyanate-based compound between the dispersed layers of the nanoclay; (8) A step in which the molecular weight and volume rapidly increase due to the urethane structure, urea structure, and isocyanurate structure generated as a result of the step (7), and the dispersed layers of the nanoclay are further expanded, causing exfoliation; The present invention is characterized by comprising:

[0013] The polyol compound is characterized in that it is a polyether polyol or a polyester polyol. The trimerization catalyst includes a tertiary amine, a triazine, and a metal salt trimerization catalyst, and the metal salt trimerization catalyst is an alkali metal salt of an organic carboxylic acid, wherein the organic carboxylic acid is acetic acid or 2-ethylhexanoic acid, and the alkali metal is potassium or sodium.

[0014] The isocyanurate compound is characterized in that it is at least one selected from triallyl isocyanurate, tris(2,3-epoxypropyl) isocyanurate, tris(hydroxyethyl) isocyanurate, tris(2-carboxyethyl) isocyanurate, tris[3-(trimethoxy)propyl] isocyanurate, and tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate.

[0015] Nanoclay has a water content of 0.5 to 10% and a true density of 1.5 to 3 g / cm 3 and an average particle size (d50) of 30 μm or less. The nanoclay is contained in an amount of 1 to 10% by weight relative to the total weight of the mixed solution (100% by weight). The nanoclay is characterized by being at least one selected from the group consisting of montmorillonite, bentonite, hectorite, saponite, beidellite, nontronite, mica, vermiculite, kanemite, magadite, Kenyaite, kaolinite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, sepiolite, imogolite, sovocite, nacrite, anauxite, sericite, ledikite, and combinations thereof.

[0016] In addition, nanoclay has Na between the layers. + ions, Ca ++ The nanoclay is characterized by being at least one selected from the group consisting of hydrophilic nanoclays that have been treated with alkyl ammonium or alkyl phosphonium organic agent ions or that have hydroxyl groups (-OH) at their terminals, hydrophobic nanoclays that have been treated with hydrophobic alkyl ammonium or alkyl phosphonium organic agent ions, and combinations of the hydrophilic nanoclays and the hydrophobic nanoclays.

[0017] Nanoclay is also characterized by its use in combination with CNTs. The nanoclay composition is also characterized in that it contains one selected from the group consisting of a silane coupling agent or a combination thereof between the layers of the nanoclay. The silane coupling agent is at least one selected from aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, (3-trimethoxysilylpropyl)diethyleneamine, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, and bis(trimethoxysilyl)ethane.

[0018] The viscosity of the mixed solution does not exceed 5000 cps. In addition, the ultrasonic waves in the step (4) are applied at 200 to 3000 W based on 20 kHz. It is characterized by: The high pressure in the step (4) is 1000 to 3000 b It is characterized by a pressure of ar.

[0019] The step (5) is characterized in that it is carried out at a temperature equal to or lower than the boiling point of the foaming agent. In addition, isocyanate compounds are m-MDI (monomer- Diphenylmethane diisocyanate , p-MDI (polymer- Diphenylmethane diisocyanate ), TDI (toluene distillate) stomach socyanate), their derivatives or mixtures thereof. Furthermore, the mixing ratio of the isocyanate compound in step (6) is 0.65 to 3.0 by weight based on the resultant product after step (5). The thermosetting foam has a density of 40 kg / m 3 and characterized as being rigid, flexible or semi-rigid foams.

[0020] Furthermore, the thermosetting foam is characterized in that after 5 minutes of burning according to the ISO 5660-1 test method, the height of the test specimen increases by 3 mm or more due to the foaming and expansion of the char, and the foamed state of the char that has increased in height is maintained as it is, while the total weight loss does not exceed 6.5 g. The flame-retardant thermosetting foam of the present invention is characterized by being produced by any one of the above-mentioned methods for producing a flame-retardant thermosetting foam. [Effects of the Invention]

[0021] The thermosetting foam with excellent flame retardancy according to the present invention was used as a test piece and subjected to a 5-minute combustion test according to ISO 5660-1. After that, the test piece increased in height by 3 mm or more due to the expansion and foaming of the char, and the expanded state of the char remained as it was, while the total weight The weight loss does not exceed 6.5 g, providing excellent flame retardancy. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram showing the mechanism by which a trimerization catalyst and a polyol are inserted between layers of nanoclay and exfoliated therefrom in the present invention. [Figure 2] 1 is a graph showing the X-ray diffraction pattern of a thermosetting expanded foam of the present invention. [Figure 3] FIG. 1 illustrates an in-situ chain reaction mechanism for the thermosetting expanded foam of the present invention. [Figure 4] FIG. 1 shows the increase in height due to expansion after combustion of a thermosetting expanded foam of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The flame-retardant thermosetting foam and the method for producing the same of the present invention will be described in more detail below with reference to the drawings. The present invention provides a method for producing a polyol-based compound by mixing a trimerization catalyst or an isocyanurate compound, comprising the steps of: (1) preparing a polyol-based compound mixed with a trimerization catalyst or an isocyanurate compound; (2) preparing a mixture containing the polyol compound, a foam stabilizer, a flame retardant, and a catalyst; (3) mixing nanoclays to prepare a mixed solution; (4) applying ultrasonic waves or high pressure to disperse the nanoclay between its layers, and the mixture is inserted between the dispersed nanoclay layers; (5) adding a blowing agent; (6) adding an isocyanate compound; (7) A step of in-situ chain reaction of a polyol-based compound and an isocyanate-based compound between the dispersed layers of the nanoclay; (8) A step in which the molecular weight and volume rapidly increase due to the urethane structure, urea structure, and isocyanurate structure produced as a result of step (7), and the spaces between the dispersed nanoclay layers are further expanded, causing exfoliation.

[0024] More specifically, the method for producing a thermosetting foam having excellent flame retardancy according to the present invention will be described with reference to FIG. First, in step (1), a polyol compound mixed with a trimerization catalyst or an isocyanurate compound is prepared. The polyol-based compound may be a polyether polyol or a polyester polyol.

[0025] The polyether polyol may be produced by reacting at least one selected from the group consisting of ethylene glycol, 1,2-propane glycol, 1,3-propylene glycol, butylene glycol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, 1,2,3-hexanetriol, 1,2,4-butanetriol, trimethylolmethane, pentaerythritol, diethylene glycol, triethylene glycol, polyethylene glycol, tripropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, sorbitol, sucrose, hydroquinone, resorcinol, catechol, and bisphenol with ethylene oxide, propylene oxide, or a mixture thereof to polymerize the reaction.

[0026] The polyester polyol is a polyol obtained by dissolving phthalic anhydride or adipic acid in ethylene oxide. , propylene oxide, or mixtures thereof. In order to form an isocyanurate structure using the polyol compound of the present invention, a trimerization catalyst is mixed with the polyol compound, or an isocyanurate compound is mixed with the polyol compound.

[0027] The trimerization catalyst mixed with the polyol compound is characterized by comprising a tertiary amine, triazine, and a metal salt trimerization catalyst, in which a metal salt acts as an activator to induce a spontaneous isocyanurate reaction of an isocyanate compound. The metal salt trimerization catalyst is characterized by being an alkali metal salt of an organic carboxylic acid, in which the organic carboxylic acid in the alkali metal salt of an organic carboxylic acid is acetic acid or 2-ethylhexanoic acid, and the alkali metal is potassium or sodium.

[0028] The isocyanurate compound to be mixed with the polyol-based compound may be at least one selected from triallyl isocyanurate, tris(2,3-epoxypropyl) isocyanurate, tris(hydroxyethyl) isocyanurate, tris(2-carboxyethyl) isocyanurate, tris[3-(trimethoxy)propyl] isocyanurate, and tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate.

[0029] In step (2), a mixture is produced by mixing a foam stabilizer, a flame retardant, a catalyst, water, etc. with the polyol-based compound mixed with the trimerization catalyst or isocyanurate compound prepared in step (1). The foam stabilizer stabilizes the formation of foam cells by controlling the surface tension during the formation of foam cells, thereby preventing the foam cells from becoming excessively large. Foam stabilizers are divided into silicone-based foam stabilizers and non-silicone-based foam stabilizers. The silicone-based foam stabilizer is a silicon-based copolymer, and any of its components or combinations can be used. The non-silicone-based foam stabilizers are dinonylphenol, methyl glucoside, methyl propanediol, vinyl ether maleic acid, vegetable oil, etc., and any of its components or combinations can be used.

[0030] The flame retardant may be at least one selected from the group consisting of a phosphorus-based flame retardant, a metal hydrate-based flame retardant, a halogen-based flame retardant, an inorganic flame retardant, a flame retardant synergist, and a mixture thereof. The phosphorus-based flame retardant includes at least one selected from the group consisting of triphenyl phosphate, cresyl diphenyl phosphate, isopropyl phenyl diphenyl phosphate, and a mixture thereof. The halogen-based flame retardant includes decabromodiphenyl oxide or octabromodiphenyl oxide, and the flame retardant synergist includes antimony trioxide.

[0031] The catalyst is used to adjust the reaction time and may be at least one selected from the group consisting of dimethylethanolamine (DMEA), dimethylcyclohexylamine (DMCHA), pentamethylenediethylenetriamine (PMETA), tetramethylenehexyldiamine (TMHDA), and mixtures thereof.

[0032] In step (3), the mixture from step (2) is mixed with nanoclay to prepare a mixed solution (FIG. 1a). The nanoclay may be mixed with an isocyanate compound. Because cyanate-based compounds react irreversibly even with very small amounts of water, mixing them with hydrophilic nanoclays is undesirable because it can cause the solution to degrade and change over time, resulting in a deterioration in the properties of the final product. Furthermore, even if the nanoclay is completely dried, moisture can cause interparticle aggregation during the drying process, reducing dispersion efficiency during subsequent ultrasonic or high-pressure application. In fact, even if hydrophilic nanoclays are organically modified, their inherent hydrophilic components cannot be completely removed. Therefore, it is preferable to mix nanoclays with a mixture containing a polyol-based compound in step (2).

[0033] The nanoclay preferably maintains a water content of 0.5 to 10%. Nanoclays that swell with water tend to aggregate with each other and become difficult to disperse if the water content is less than 0.5%. However, if the water content exceeds 10%, the polyol-based compound to be mixed tends to disperse. The water content of the mixture increases, and the physical properties change after reaction with the isocyanate compound. The nanoclay has a true density of 1.5 to 3 g / cm 3 It is preferable that the true density is maintained at 1.5 g / cm. 3 If it is less than 3 g / cm 3 If the load exceeds this value, the load will be too high, and precipitation will occur even after dispersion with the polyol compound, resulting in changes in physical properties.

[0034] The average particle size (d50) of the nanoclay is preferably 30 μm or less. If the average particle size exceeds 30 μm, the density becomes high and there is a risk of sedimentation due to load. The nanoclay is contained in an amount of 1 to 10 wt % based on the total weight of the mixture and the mixed solution containing the nanoclay. When the amount is less than 1%, the effect of improving physical properties can be obtained. If the content exceeds 10%, the dispersion efficiency decreases and the physical properties deteriorate.

[0035] The nanoclay is at least one selected from the group consisting of montmorillonite, bentonite, hectorite, saponite, beidellite, nontronite, mica, vermiculite, kanemite, magadite, kenyaite, kaolinite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, sepiolite, imogolite, sovocite, nacrite, anauxite, sericite, ledikite, and combinations thereof.

[0036] The nanoclay can be used after being subjected to an organo-treatment. This is achieved by ion-exchanging the cations between the nanoclay layers with alkylammonium or alkylphosphonium ions, and the nanoclay can be made hydrophobic or hydrophilic depending on the properties of the ions. The nanoclay used in the present invention has Na between the layers. + ions, Ca ++ At least one nanoclay selected from the group consisting of hydrophilic nanoclays that have been treated with ions or acids, or that have been substituted with alkylammonium or alkylphosphonium organic modifier ions having a hydroxyl group (-OH) at the end, hydrophobic nanoclays that have been substituted with hydrophobic alkylammonium or alkylphosphonium organic modifier ions, or a combination of the hydrophilic nanoclays and the hydrophobic nanoclays can be used.

[0037] The nanoclay can be used in combination with CNTs (carbon nanotubes). Combining the nanoclay with CNTs increases their dispersibility in the polyol resin, uniforming the cells during foaming and improving the heat insulating performance. However, there are no particular limitations on the type and content of the CNTs. The mixing of the nanoclay and the mixture is not limited, but may be carried out at 20 to 40°C for 30 minutes to 3 hours. It is preferable to carry out the process under conditions of a speed of 50 to 700 rpm for a short time. The viscosity of the mixed solution in the step (3) is preferably 5000 cps or less. If it exceeds 5000 cps, the viscosity will be too high in the next dispersion step using ultrasound or high pressure. There is a problem that dispersion efficiency decreases.

[0038] In step (4), ultrasonic waves or high pressure are applied to disperse the nanoclay between its layers, so that the mixture is inserted between the dispersed nanoclay layers (FIG. 1b). In this case, a silane coupling agent or a combination thereof may be added. The silane coupling agent is an organic-inorganic intermediate that acts to eliminate the heterogeneity between the organic mixture and the inorganic nanoclay, facilitating the intercalation of the mixture between the dispersed nanoclay layers. The silane coupling agent may also be mixed in advance in step (3). However, the present invention does not limit the amount of the silane coupling agent.

[0039] The silane coupling agent can be at least one selected from aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropylmethyldimethoxysilane, (3-trimethoxysilylpropyl)diethyleneamine, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, glycidoxypropyltrimethoxysilane, and bis(trimethoxysilyl)ethane. Once the mixed solution is prepared, ultrasonic waves or high pressure is applied.

[0040] The ultrasonic intensity for dispersing the mixture between the nanoclay layers is 20 kHZ. It is preferable to apply 0 to 3000 W. When using less than 200 W, the dispersion efficiency decreases, and when exceeding 3000 W, there is a problem that the physical properties decrease due to damage to the nanoclay. The volume that can be added is not limited, but may be 100 ml to 20 L per minute. The dispersion strength of the ultrasonic waves can be adjusted. When ultrasonic waves are applied, the temperature of the nanoclay and the polyol-based compound may rise due to vibration and friction. Therefore, it is better to control the temperature at a level of 15 to 80°C. If the temperature is less than 15°C, the dispersion efficiency may decrease, and if it exceeds 80°C, some of the components may evaporate, which is not preferable. .

[0041] High pressure for dispersing the mixture between the layers of the nanoclay is applied by a high-pressure disperser. The high-pressure disperser is a device that places fluid in a chamber of a certain size and applies high pressure to induce dispersion of the fluid. In the present invention, high pressure of 1000 to 3000 bar is applied by the high-pressure disperser. If it is less than 1000 bar, the dispersion decreases and the physical properties deteriorate. If it exceeds 3000 bar, the physical properties deteriorate due to damage to the nanoclay. Smooth insertion of the components of the mixture into the interlayer of the nanoclay can be confirmed by measuring the physical properties.

[0042] If the interlayer distance of the natural or organically treated nanoclay is d, during the application of ultrasonic waves or high pressure, the interlayer expansion of the nanoclay occurs due to vibration and impact or pressure. At this time, the components of the mixture are inserted into the expanded interlayer. When the insertion of the compound into the interlayer of the nanoclay is completed, aggregation does not occur in the interlayer of the nanoclay even without further application of ultrasonic waves. If the interlayer distance of the nanoclay after such application of ultrasonic waves or high pressure is d', then d < d', and it can be confirmed that the interlayer of the nanoclay has expanded.

[0043] (5) As a step, a foaming agent is added. If the foaming agent is mixed before ultrasonic or high-pressure dispersion, there is a problem that it vaporizes due to heat generated by vibration and friction or pressure. The step of adding the foaming agent is preferably performed at a temperature below the boiling point temperature of the foaming agent. If the temperature exceeds the boiling point temperature of the foaming agent, there may also be a problem that the foaming agent vaporizes. The foaming agent is preferably a substance with low thermal conductivity and high stability. The foaming agent is at least any one selected from the group consisting of cyclopentane, chlorofluorocarbon, isopentane, normal pentane, hydrochlorofluorocarbon, hydrofluorocarbon, and water may be.

[0044] In step (6), an isocyanate compound is added. The isocyanate compound is mixed and then injected into a mold of a certain size using a high-pressure or low-pressure foaming machine, or it can be sprayed onto the surface to be applied using a mixing gun. Various foaming devices, such as Graco, Gusmer, and Gras-craft, can be used. While maintaining a discharge pressure of 50 to 200 bar and a temperature of 30 to 70°C, chemical activation occurs through the collision and mixing of the polyol compound and the isocyanate compound, resulting in spraying.

[0045] The isocyanate compound is not particularly limited, and may be m-MDI (monomer- Diphenylmethane diisocyanate , p-MDI (polymer- Diphenylmethane diisocyanate , TDI (toluene di stomach Socyanates, derivatives thereof or mixtures thereof can be used. When the isocyanate-based compound flows into the polyol-based compound inserted between the nanoclay layers, an in-situ chain reaction occurs (Fig. 1c) in which a urethane reaction, a urea reaction, and an isocyanurate reaction caused by a trimerization catalyst occur simultaneously, as shown in Fig. 3. This is step (7) of the present invention. After step (5), the isocyanate compound is mixed in step (6) at a weight ratio of 0.65 to 3.0 based on the resultant product. If the mixing ratio is less than 0.65 or more than 3.0, there is a problem that physical properties such as strength and flame retardancy are rapidly reduced.

[0046] In step (8), the generated urethane, urea, and isocyanurate structures rapidly increase in molecular weight and volume, further expanding the interlayer distance of the dispersed nanoclay and contributing to complete exfoliation (Figure 1(d)). The thermosetting foam produced in this way has excellent flame retardancy and a density of 40 kg / m 3For thermosetting foams containing the following, after 5 minutes of burning according to the ISO 5660-1 test method, the test specimens shall increase in height by 3 mm or more due to the expansion of the char, and the increase in height shall be The foaming state of the added char remains the same, but the total weight loss does not exceed 6.5 g. While typical foams generally decrease in volume after combustion, the thermosetting foam of the present invention expands in volume upon combustion, allowing it to maintain airtightness and exhibit superior flame retardancy. Furthermore, the fact that no additional flame retardant materials such as iron plate or silver foil are attached to the outer surface of the polyurethane foam itself provides excellent flame retardancy and quasi-nonflammable properties.

[0047] However, unlike the present invention, if the nanoclay is not fully dispersed in the mixture, the density will be less than 40 kg / m 3 In addition, the ISO 5660-1 test method After 5 minutes of burning, the specimens did not increase in height by more than 3 mm and the total weight loss was 6.5 It will exceed g. The thermosetting foam produced by the present invention has a density of 40 kg / m 3 It may be a rigid, flexible or semi-rigid foam within the following ranges:

[0048] The exfoliated state of the nanoclay by expanding the interlayer distance of the prepared thermosetting foam was confirmed using an X-ray diffraction analyzer, and is shown in Figure 2. The interlayer distance of the nanoclay was calculated using Bragg's law, and the nanoclay without interlayer expansion was used as the reference. The foam prepared by the solution dispersion method is shown as 1) in the figure, and the foam prepared by the ultrasonic dispersion method is shown as 2) in the figure. 2dsinθ=nλ(Bragg's law), d: distance between crystal planes (nanoclay), θ: angle between incident X-ray and crystal plane, λ: wavelength of X-ray

[0049] Generally, the 2θ value of an X-ray diffraction peak indicates the interlayer distance of nanoclay. As the 2θ value decreases, the interlayer distance increases, and the peak disappears when complete exfoliation occurs. Therefore, it can be seen from Figure 2 that the thermosetting foam of the present invention undergoes primary intercalation of the components of the mixture between the nanoclay layers using the ultrasonic dispersion method, and complete exfoliation occurs during the in-situ chain reaction with the trimerization catalyst and isocyanate compound.

[0050] The combustion mechanism is shown in Figure 4. Nanoclay is dispersed in a plate-like form and acts as a barrier to block flames and heat during combustion. When combustion begins, char forms on the surface. At this time, the gas and water generated are trapped by the nanoclay, and as time passes, more gas and water are generated, but eventually the char cannot withstand the pressure and foams. The flame goes out, and the foamed char increases in height by more than 3 mm, maximizing the thermal effect of the char. Finally, the flame retardancy is further increased, and the final weight loss is 6.5 g or less according to the test method. [Example]

[0051] The present invention will be described in detail below through specific examples and comparative examples. However, these examples are merely for illustrative purposes and should not be construed as limiting the scope of the present invention. Table 1 below shows the compounding ratios and dispersion methods of the examples, and Tables 2 and 3 below show the compounding ratios and dispersion methods of the comparative examples. Example 1 To prepare a polyol-based compound containing nanoclay, 80% by weight of polyester polyol and 20% by weight of polyether polyol were added to 1.5% by weight of water, 0.7% by weight of foam stabilizer, 20% by weight of phosphorus-based flame retardant, 0.15% by weight of catalyst, 2.3% by weight of trimerization catalyst, and 3% by weight of nanoclay. The mixture was then heated at 25°C for 1 hour. The solution was stirred at 50 RPM for 30 minutes. After the stirring was completed, the solution was dispersed using a continuous ultrasonic device at a flow rate of 6 L per minute at 20 kHz and 1500 W, and then discharged. The polyol compound in which the nanoclay was dispersed was mixed with 15% by weight of a foaming agent (HCFC-141B), stirred at 100 RPM for 10 minutes, and then placed in the foaming machine B container. An isocyanate compound was placed in container A of the foaming machine. The solution was discharged into a mold using a foaming machine at a ratio of 120:100 (A:B) to produce a thermosetting foam. The solution temperatures in containers A and B were 50°C, and the discharge pressure was 100 bar.

[0052] Example 2. A thermosetting foam was prepared using the method of Example 1, and the amount of nanoclay was 5 wt.%. Ta. Example 3. A thermosetting foam was prepared by the method of Example 2, except that the trimerization catalyst was omitted and 3 wt% of an isocyanurate compound was added in the formulation of Example 2. The ratio of solution A to solution B in the foaming machine vessel was 100:100. Example 4. A thermosetting foam was produced by the method of Example 2, except that 3 wt % of an isocyanurate compound was added to the formulation of Example 2. Example 5. A thermosetting foam was prepared using the method of Example 1, and the polyol-based compound containing nanoclay was dispersed under high pressure of 1500 bar using a high-pressure disperser, not by ultrasonication. Example 6 A thermosetting foam was prepared according to the method of Example 2, and the polyol-based compound containing nanoclay was dispersed under high pressure of 1500 bar using a high-pressure disperser, not by ultrasonication.

[0053] Example 7 To manufacture polyol-based compounds containing nanoclay, polyester polyol 80%, polyether polyol 20% by weight, water 1, foam stabilizer 1.2, phosphorus-based flame retardant 20% of the agent, 0.7% of the catalyst, 3.8% of the trimerization catalyst, and 3% of the nanoclay were added and stirred at 25°C and 150 RPM for 30 minutes. The nanoclay was dispersed in an ultrasonic device at a flow rate of 6 L / min at 20 kHz and 1500 W, and then discharged. The polyol-based compound in which the nanoclay had been dispersed was mixed with 23% by weight of a blowing agent (HCFC-141B), and stirred at 100 RPM for 10 minutes. The solution was placed in a foaming machine A container. An isocyanate compound was placed in foaming machine A container. The solution was discharged into a mold using a foaming machine at a ratio of 200:100 (A:B) to produce a thermosetting foam. The temperature of solutions A and B was 50°C, and the discharge pressure was 100 bar. Example 8 A thermosetting foam was prepared using the same method as in Example 7, and nanoclay was added in an amount of 5 wt %. .

[0054] Comparative Example 1 To prepare a polyol-based compound containing nanoclay, 80% by weight of polyester polyol and 20% by weight of polyether polyol were added to 1.5% by weight of water, 0.7% by weight of foam stabilizer, 20% by weight of phosphorus-based flame retardant, 0.15% by weight of catalyst, 2.3% by weight of trimerization catalyst, and 3% by weight of nanoclay. The mixture was then heated at 25°C for 1 hour. The mixture was stirred at 50 RPM for 30 minutes. After the stirring was completed, the solution was stirred at 500 RPM for 10 minutes using a high-speed stirrer and then discharged. The polyol-based compound in which the nanoclay was dispersed was mixed with 15% by weight of a foaming agent (HCFC-141B), stirred at 100 RPM for 10 minutes, and then placed in the foaming machine B container. The foaming machine A container contained an isocyanate-based compound. The solutions were then discharged into a mold using a foaming machine at a ratio of 120:100 (A:B) to produce a thermosetting foam. The temperatures of solutions A and B were 50°C, and the discharge pressure was The force is 100 bar.

[0055] Comparative Example 2 A thermosetting foam was prepared according to the method of Comparative Example 1, and the polyol-based compound containing nanoclay was dispersed in the foam using a high-speed mixer at 5000 RPM for 10 minutes. Comparative Example 3 A thermosetting foam was prepared according to the method of Comparative Example 1, and the polyol-based compound containing nanoclay was dispersed in the foam using a high-speed mixer at 5000 RPM for 30 minutes. Comparative Example 4 A thermosetting foam was prepared according to the method of Comparative Example 1, and the polyol-based compound containing nanoclay was dispersed in the foam using a high-speed mixer at 8000 RPM for 30 minutes. Comparative Example 5 A thermosetting foam was prepared by the method of Comparative Example 1, except that the nanoclay was omitted from the polyol compound blending of Comparative Example 1 to prepare a solution. Since the nanoclay was not included, no separate dispersion was performed.

[0056] Comparative Example 6 To produce the polyol compound, 80% by weight of polyester polyol and 20% by weight of polyether polyol were used, with 1% by weight of water, 1.2% by weight of foam stabilizer, 20% by weight of phosphorus-based flame retardant, 0.7% by weight of catalyst, 3.8 wt% of a trimerization catalyst was added and stirred at 25°C and 150 RPM for 30 minutes. Then, 23 wt% of a blowing agent (HCFC-141B) was added to the polyol compound. The above ingredients were mixed and stirred at 100 RPM for 10 minutes, and then placed in the foaming machine B container. An isocyanate compound was added to the foaming machine A container. The solution was discharged into a mold using a foaming machine at a ratio of 200:100 (A:B) to produce a thermosetting foam. The temperature of solutions A and B was 50°C, and the discharge pressure was 100 bar.

[0057] Comparative Example 7 To produce the polyol compound, 80% by weight of polyester polyol and 20% by weight of polyether polyol were used, with 1% by weight of water, 1.2% by weight of foam stabilizer, 20% by weight of phosphorus-based flame retardant, 0.7% by weight of catalyst, 3.8g of a trimerization catalyst was added and stirred at 25°C and 150 RPM for 30 minutes. Then, 23% by weight of a blowing agent (HCFC-141B) was mixed with the polyol compound. The mixture was stirred at 100 RPM for 10 minutes and then placed in the foaming machine B container. The foaming machine A container was charged with an isocyanate compound. However, the isocyanate compound was a compound in which the nanoclay was five times as thick as the nanoclay. The mixture was mixed at 5000 RPM for 10 minutes using a high-speed mixer. The solution was then extruded into a mold using a foaming machine at a ratio of 200:100 (A:B) to produce a thermosetting foam. The temperature of solutions A and B was 50°C, and the extrusion pressure was 100. The force is 100 bar.

[0058] Comparative Example 8 A thermosetting foam was prepared using the method of Comparative Example 7. The isocyanate compound of Comparative Example 7 contained 5 wt% of nanoclay, and the mixture was stirred for 30 minutes using a high-speed stirrer at 5000 RPM. Comparative Example 9 A thermosetting foam was prepared using the method of Comparative Example 7. The isocyanate compound of Comparative Example 7 contained 5 wt% of nanoclay, and the mixture was stirred for 30 minutes using a high-speed stirrer at 10,000 RPM.

[0059] Comparative Example 10 A thermosetting foam was prepared using the method of Comparative Example 7. The isocyanate-based compound of Comparative Example 7 contained 5 wt% nanoclay, and the mixture was dispersed using a continuous ultrasonic device at a flow rate of 6 L per minute and 1500 W at 20 kHz. Comparative Example 11 A thermosetting foam was prepared using the method of Comparative Example 7. The polyol-based compound and the isocyanate-based compound of Comparative Example 7 each contained 2.5 wt% nanoclay, and the mixture was dispersed using a continuous ultrasonic device at a flow rate of 6 L per minute and 1500 W at 20 kHz.

[0060] Comparative Example 12 A thermosetting foam was produced by the method of Comparative Example 1, except that the trimerization catalyst was omitted from the polyol compound blend of Comparative Example 1. Comparative Example 13 A thermosetting foam was prepared by the method of Comparative Example 1, except that 3 wt % of an inorganic expanding agent was added instead of nanoclay in the polyol compound formulation of Comparative Example 1.

[0061] Comparative Example 14 A thermosetting foam was prepared by the method of Comparative Example 5, except that 3 wt % of an inorganic expanding agent was added instead of nanoclay in the polyol compound formulation of Comparative Example 5. Comparative Example 15 A thermosetting foam was prepared by the method of Comparative Example 5, except that 3 wt % of an organic expanding agent was added instead of nanoclay in the polyol compound formulation of Comparative Example 5.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] Test 1. The densities of the comparative thermosetting foams compared to the examples prepared according to the present invention were measured according to ISO 845. Test 2. The self-extinguishing time and weight loss of the thermosetting foams of the comparative examples compared to the examples prepared according to the present invention were tested according to the ISO 5660-1 combustion test, and the weight loss was measured by measuring the weight loss of the test specimen after burning for 5 minutes compared to the weight before the test. The size is 100*100*50T and is made of a single material that does not contain cotton.

[0066] Test 3. The thermal conductivity of the thermosetting foams of the examples prepared according to the present invention and the comparative examples was measured according to ASTM C 518. Test 4. The height increase after combustion of the thermosetting foams of the comparative examples compared to the examples prepared according to the present invention was measured as follows, and the shape can be seen in Figure 4 and Tables 4 to 9. Height increase after combustion (mm) = Height of test piece after combustion (mm) - Height of test piece before combustion (mm) Tables 4 and 5 below show the thermal curing foams of Examples 1 to 8 before and after combustion. The photographs show the change in height due to expansion, and Tables 6 to 9 below are photographs showing the change in height of the thermosetting expandable foams of Comparative Examples 1 to 15 before and after combustion.

[0067] [Table 4]

[0068] [Table 5]

[0069] [Table 6]

[0070] [Table 7]

[0071] [Table 8]

[0072] [Table 9]

[0073] Table 10 below shows the test results for Examples 1 to 8, and Tables 11 and 12 show the test results for Comparative Examples 1 to 15.

[0074] [Table 10]

[0075] [Table 11]

[0076] [Table 12]

[0077] In the present embodiment, even if nanoclay is added, the nanoclay to be compared is removed. The density did not increase compared to the comparative example. However, the weight loss after combustion did not exceed 6.5 g, showing a significant improvement in flame retardancy, which represents the complete dispersion of the nanoclay and the complete intercalation and exfoliation of the components that make up the thermosetting foam within the nanoclay. Another evidence of this is the increase in height after combustion. Well-dispersed nanoclay is layered multiple times between the materials that make up the thermosetting foam, acting as a barrier. When combustion begins, char forms on the surface of the material, and the generated gas and water are trapped by the nanoclay layers. Over time, more gas and water are generated, but eventually the material cannot withstand the heat and the char begins to foam. The flames are extinguished, and the foamed char increases in height by more than 3 mm while maximizing the heat-shielding effect, and this phenomenon continues. The resulting flame retardancy is significantly improved. However, unless an isocyanurate structure, realized by a trimerization catalyst or an isocyanurate compound, is formed in the structure constituting the thermosetting foam, the above-mentioned flame retardancy cannot be achieved by dispersing nanoclay alone. Finally, when a thermosetting foam was manufactured using the nanoclay as a blowing agent and tested, the foam initially expanded temporarily during the combustion test, but was unable to withstand sustained flames and instead shrunk or melted, resulting in a decrease in flame retardancy.

Claims

1. A thermosetting foam having excellent flame retardancy, which is obtained by curing a foaming solution with an isocyanate compound as a curing agent, The foaming solution comprises: one or more polyol compounds selected from polyester polyols and polyether polyols; a mixture containing at least one of a trimerization catalyst and an isocyanurate compound, water, a foam stabilizer, a flame retardant, and a catalyst other than the trimerization catalyst; a mixed solution comprising the polyol compound, the mixture, and nanoclay, the mixed solution being obtained by subjecting a nanoclay-polyol intercalation compound containing nanoclay in an amount of 1 to 10 wt % relative to 100 wt % of the mixed solution to ultrasonic treatment or high pressure treatment at 100 to 300 MPa; a blowing agent, the blowing agent is at least one selected from the group consisting of cyclopentane, chlorofluorocarbons, isopentane, normal pentane, hydrochlorofluorocarbons, and hydrofluorocarbons; The polyol compound and the mixture are inserted between the layers of the dispersed nanoclay, and the molecular weight and volume of the nanoclay-polyol intercalation compound having one or more structures of a urethane structure, a urea structure, or an isocyanurate structure are increased, and the spaces between the nanoclay layers are further expanded, causing exfoliation; The thermosetting foam has excellent flame retardancy, and the total weight loss after 5 minutes of burning according to the ISO 5660-1 test method does not exceed 6.5 g compared to before the test.

2. 2. The flame-retardant thermosetting foam according to claim 1, wherein the isocyanate compound is m-MDI (monomer diphenylmethane diisocyanate), p-MDI (polymer diphenylmethane diisocyanate), TDI (toluene diisocyanate), a derivative thereof, or a mixture thereof.

3. 3. The flame-retardant thermosetting foam according to claim 1, wherein the mixing ratio of the isocyanate compound is 0.65 to 3.0 weight percent (%) based on the thermosetting foam.

4. The density of the thermosetting foam is 40 kg / m ３ 3. The thermosetting foam having excellent flame retardancy according to claim 1, wherein the thermosetting foam has a viscosity of 0.050 to 0.100 psi or less and a thermal conductivity of 0.022 W / mK or less.

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