ORGANIC-INORGANIC HYBRID TYPE FIRE-EXTINGUISHING MICROCAPSULE HAVING DOUBLE-WALL STRUCTURE, METHOD FOR MANUFACTURING SAME, AND FIRE-EXTINGUISHING COMPOSITION COMPRISING SAME

Abstract

The present invention relates to a fire-extinguishing microcapsule, a method for manufacturing same, and a fire-extinguishing composition comprising same. The microcapsule includes a core containing a non-inflammable material; a first shell layer covering the core and containing inorganic nanoparticles and a water-soluble polymer; and a second shell layer covering the first shell layer and containing a polymer.

Claims

1. A fire-extinguishing microcapsule comprising: a core comprising a non-flammable material; a first shell layer covering the core, the first shell layer comprising an inorganic nanoparticle and a water-soluble polymer; and a second shell layer covering the first shell layer, the second shell layer comprising a polymer.

2. The microcapsule of claim 1, wherein the non-flammable material is any one or a mixture of two or more selected from among methoxynonafluorobutane, dibromomethane, and methoxyheptafluoropropane.

3. The microcapsule of claim 1, wherein the inorganic nanoparticle comprises any one or a mixture of two or more selected from among titanium dioxide (TiO.sub.2), silica (SiO.sub.2), and alumina (Al.sub.2O.sub.3).

4. The microcapsule of claim 3, wherein a surface of the inorganic nanoparticle is modified with an acrylic group.

5. The microcapsule of claim 1, wherein the water-soluble polymer is any one or a mixture of two or more selected from the group consisting of gelatin, chitosan, chitin, pectin, locust bean gum, gellan gum, alginic acid, agar, carrageenan, collagen, hyaluronic acid, guar gum, ethylcellulose, methylcellulose, carboxymethylcellulose, and polyacrylic acid.

6. The microcapsule of claim 1, wherein the second shell layer comprises a urea-formaldehyde resin or a resorcinol-formaldehyde resin.

7. A method of preparing the microcapsule of claim 1, the method comprising: (a) preparing an emulsion comprising a non-flammable material, an inorganic nanoparticle, and a water-soluble polymer; (b) preparing a microcapsule comprising a core comprising the non-flammable material and a first shell layer comprising the inorganic nanoparticle and the water-soluble polymer by adding a pH adjuster to the emulsion for pH adjustment of the emulsion, adding a cross-linking agent, and stirring the resulting emersion; and (c) forming a second shell layer comprising a polymer on the first shell layer of the microcapsule.

8. A fire-extinguishing composition comprising: the microcapsule of claim 1; and a binder.

Description

DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a cross-sectional view of an organic-inorganic composite capsule having a double-wall structure for fire suppression according to the present disclosure;

[0023] FIG. 2 is a digital camera image of an organic-inorganic composite capsule for fire suppression according to one example of the present disclosure;

[0024] FIG. 3 is a field emission scanning electron microscope (FESEM) image of an organic-inorganic composite capsule for fire suppression according to one example of the present disclosure;

[0025] FIG. 4 is a graph showing thermogravimetric analysis results of organic-inorganic composite capsules for fire suppression operable at varying temperatures according to examples of the present disclosure;

[0026] FIG. 5 is a graph showing X-ray fluorescence (XRF) analysis results of an organic-inorganic composite capsule for fire suppression according to one example of the present disclosure;

[0027] FIG. 6 is a graph showing mass loss when stored at room temperature according to examples of the present disclosure;

[0028] FIG. 7 shows images of results obtained when performing fire extinguishment according to one example of the present disclosure; and

[0029] FIGS. 8A through 8C show energy-dispersive spectroscopy (EDS) mapping images of the polymer matrix of each outer wall of microcapsules in which inorganic materials that differ from each other are dispersed according to examples of the present disclosure.

MODE FOR INVENTION

[0030] In describing the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted.

[0031] Embodiments according to the concept of the present disclosure can be applied to various changes and can have various forms, so specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit the embodiments according to the concept of the present disclosure to a specific disclosed form and should be understood to include all changes, equivalents, or substitutes included in the spirit and technical scope of the present disclosure.

[0032] Terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms a, an, and the are intended to include the plural forms as well unless the context clearly indicates otherwise. Terms such as comprise or have used herein are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, but one or more other features or numbers However, it should be understood that it does not preclude the presence or addition of steps, operations, components, parts, or combinations thereof.

[0033] Hereinafter, the present disclosure will be described in more detail through examples.

[0034] The embodiments according to the present specification may be modified in many different forms, and the scope of the present specification is not construed as being limited to the embodiments described below. The embodiments of the present disclosure described hereinbelow are provided to allow those skilled in the art to more clearly comprehend the present disclosure.

Example

[0035] Like in the related art, an outer wall based on polymers, such as gelatin, has disadvantages in that the mechanical strength is poor compared to that of microcapsules having an outer wall based on inorganic materials, the loss of internal substances is significant, and the thermal conductivity is poor. Low thermal conductivity functions as a factor that delays heat transfer occurring in the event of a fire and hinders the rapid fire-extinguishing process, which thus must be improved. Additionally, low mechanical stability necessitates additional support materials, such as polymeric sheets, so there is a disadvantage in that the existing microcapsules cannot be used alone. Furthermore, considering that the ignition point and temperature are not always the same in places where an actual fire occurs, traditional operation allowing internal substances to be released at a constant temperature has difficulty in preventing fire in various environments.

[0036] In the present disclosure, to solve these problems, capsules are prepared by adding inorganic nanomaterials that differ in thermal conductivity. The inorganic nanomaterial contains 0.1 to 10 wt % of a halogen-based flame retardant as internal substances, and a level of the size thereof ranges from tens of nanometers to several micrometers. A process of preparing the composite capsule is divided into the following steps: preparing a water-soluble solution based on a polymer, such as stable gelatin, containing inorganic materials; forming an organic-inorganic composite shell by electrostatic attraction between polymers through pH adjustment; forming a secondary wall using polymers and copolymers; and lastly filtering and drying the resulting composite capsule.

Example 1: Preparation of Gelatin-Titanium Dioxide-Hexametaphosphate Microcapsules

[0037] To 100 ml of anhydrous ethanol, 2.0 to 20 g of titanium dioxide powder was added. Then, the resulting product was sonicated for 1 hour for dispersion. Next, 0.3 g of trimethoxylpropylmethacrylate (hereinafter referred to as A174) was added to 20 ml of anhydrous ethanol and heated to the temperature of 40? C. to 50? C. for stirring. The prepared solution of A174 was added to the highly dispersed suspension of titanium dioxide particles, heated to the temperature of 70? C. to 80? C., and then stirred for 3 hours. Through centrifugation and washing, a partially hydrophobic inorganic material to be used in preparing microcapsules was prepared.

[0038] Depending on the purpose of use, 0.02 to 2.0 g of the prepared inorganic material was dispersed in 100 mL of distilled water. Then, 4.5 g of gelatin treated with base was added to the titanium dioxide suspension and heated to the temperature of 50? C. to 60? C., thereby obtaining a homogeneous suspension. Next, 15 mL of a halogen-based non-flammable material (methoxynonafluorobutane) was added to the obtained suspension and then stirred at a rate of 500 to 800 rpm, thereby obtaining an emulsion. After slowly adding 50 mL of 0.6 wt % of an aqueous hexametaphosphate solution to the emulsion solution and stirring the resulting solution for 10 minutes, the pH was reduced to 4.6 to 4.7 using a 10% acetic acid solution. Afterward, the temperature was reduced to 5? C. using a cooling circulating water bath to cool this solution, and 2.5 mL of 50 wt % of glutaric aldehyde was then slowly added at a rate of 0.05 mL per minute with stirring. After raising the temperature to 35? C., 0.2 g of polyvinylpyrrolidone was added, followed by stirring the resulting product for 10 minutes. Next, after adding 1 g of urea and 2.44 g of a formaldehyde solution, a 35% to 37% hydrochloric acid solution was added to adjust the pH to 1.5 to 2.0, and then a reaction occurred for 3 hours. The resulting suspension was filtered and dried at room temperature, thereby obtaining microcapsule powder.

Example 2: Preparation of Gelatin-Silica-Hexametaphosphate Microcapsules

[0039] To 150 ml of a solution in which distilled water and anhydrous ethanol were mixed in a ratio of 1:1, 0.1 to 10 g of silica powder was added. Then, the resulting product was sonicated for 1 hour for dispersion. Next, 0.5 g of trimethoxylpropylmethacrylate (hereinafter referred to as A174) was added to the 50 ml of the solution in which distilled water and anhydrous ethanol were mixed in a ratio of 1:1 and heated to the temperature of 40? C. to 50? C. for stirring. The prepared solution of A174 was added to the highly dispersed suspension of dry silica particles, heated to the temperature of 70? C. to 80? C., and then stirred for 3 hours. Through centrifugation and washing, a partially hydrophobic inorganic material to be used in preparing microcapsules was prepared.

[0040] Depending on the purpose of use, 0.02 to 2.0 g of the prepared inorganic material was dispersed in 100 mL of distilled water. Then, 4.5 g of gelatin treated with base was added to the silica suspension and heated to the temperature of 50? C. to 60? C., thereby obtaining a homogeneous suspension. Next, 15 mL of a halogen-based non-flammable material (methoxynonafluorobutane) was added to the obtained suspension and then stirred at a rate of 500 to 8000 rpm, thereby obtaining an emulsion. After slowly adding 50 mL of 0.6 wt % of an aqueous hexametaphosphate solution to the emulsion solution and stirring the resulting solution for 10 minutes, the pH was reduced to 4.3 using a 10% acetic acid solution. Afterward, the temperature was reduced to 5? C. using a cooling circulating water bath to cool this solution, and 5 mL of 25 wt % glutaric aldehyde was then slowly added at a rate of 0.1 mL per minute with stirring. After raising the temperature to 40? C., 0.1 g of cetrimonium bromide was added, followed by stirring the resulting product for 10 minutes. Next, after adding 0.5 g of resorcinol and 2.44 g of a formaldehyde solution, a 35% to 37% hydrochloric acid solution was added to adjust the pH to 1.5 to 2.0, and then a reaction occurred for 3 hours. The resulting suspension was filtered and dried at room temperature, thereby obtaining microcapsule powder.

Example 3: Preparation of Gelatin-Alumina-Hexametaphosphate Microcapsules

[0041] In 100 mL of distilled water, 0.02 to 2.0 g of hydrophilic alumina powder was dispersed. Then, 4.5 g of gelatin treated with base was added to a silica suspension and heated to the temperature of 50? C. to 60? C., thereby obtaining a homogeneous suspension. Next, mL of a halogen-based non-flammable material (methoxynonafluorobutane) was added to the obtained suspension and then stirred at a rate of 500 to 8000 rpm, thereby obtaining an emulsion. After injecting 50 mL of 0.6 wt % of an aqueous hexametaphosphate solution into the emulsion solution at a rate of 5 mL per minute and stirring the resulting solution for 10 minutes, the pH was reduced to 4.3 using a 0.1 M acetic acid solution. Afterward, the temperature was reduced to 5? C. using a cooling circulating water bath to cool this solution, and 5 mL of 25 wt % of glutaric aldehyde was then slowly added at a rate of 0.1 mL per minute with stirring. After raising the temperature to 40? C., 0.5 g of polyvinylpyrrolidone was added, and then the resulting product was stirred for 10 minutes. Next, after adding 1.875 g of urea and 4.16 mL of a formaldehyde solution, a 1.0 M hydrochloric acid solution was added to adjust the pH to 1.5 to 2.0, and then a reaction occurred for 3 hours. The resulting suspension was filtered and dried at room temperature, thereby obtaining microcapsule powder.

[0042] FIG. 3 is a scanning electron microscope (SEM) image of the microcapsule prepared in Example 1 herein.

[0043] FIG. 4 shows thermogravimetric analysis results of the microcapsules each independently prepared in Examples 1 to 3 herein, demonstrating that the microcapsules of examples herein are operable at varying temperatures depending on the types of inorganic materials contained in the microcapsules according to examples herein.

[0044] FIG. 5 shows X-ray fluorescence (XRF) analysis results of the outer wall of the microcapsule prepared in Example 1 herein.

[0045] FIG. 6 shows results of changes in the weight of the microcapsules each independently prepared in Examples 1 to 3 herein for 45 days.

[0046] These results demonstrate the stability of the outer wall of the microcapsule and show that the internal substance is kept from being lost even after long-term storage.

[0047] FIG. 7 shows results of laboratory-scale fire suppression experiments performed on the microcapsule prepared in Example 1 herein.

[0048] FIGS. 8A to 8C show energy-dispersive spectroscopy (EDS) mapping images of the outer walls of the microcapsules each independently prepared in Examples 1 to 3 herein.

[0049] The left images are SEM images of each polymer matrix of the outer wall of the capsules, and the middle images show each polymer matrix through the positions of carbon atoms. The right images show that the inorganic (TiO.sub.2, SiO.sub.2, or Al.sub.2O.sub.3) particles and the polymer do not constitute the respective outer wall layers, but that the inorganic particles are evenly dispersed in the polymer matrix.

[0050] The present disclosure is not limited to the example described above, but can be manufactured in a variety of different forms. Those skilled in the art to which the present disclosure pertains will understand that other specific forms can be implemented without changing the technical spirit or essential features of the present disclosure. Therefore, preferred embodiments of the present disclosure have been described for illustrative purposes and should not be construed as being restrictive.

EXPLANATION OF REFERENCE NUMERALS

[0051] 1: Liquid non-flammable material (core) [0052] 2: Polymer-based organic-inorganic composite outer wall containing inorganic nanoparticles (first shell layer) [0053] 3: Polymeric material-based outer wall (second shell layer)

INDUSTRIAL APPLICABILITY

[0054] In a fire-extinguishing microcapsule according to the present disclosure, provided is an outer wall (first shell) made of an organic polymer and an inorganic material, the outer wall surrounding a liquid non-flammable fire-extinguishing agent serving as a core for encapsulation. Therefore, a fire-extinguishing microcapsule capable of rapidly reacting to external temperature rise and adjusting the operating temperature range is implementable.