Flame retardant, composite, method for manufacturing the composite

Abstract

The present invention provides a flame retardant, a composite, and a method for manufacturing the composite, which can form a flame-retardant coating when applied to the surface of wood. [Solution] A flame retardant comprising a polyborosiloxane structure represented by the following formula (1). [C1] TIFF2026067828000005.tif35170 (where R is an alkyl group with 1 to 6 carbon atoms, or an alkoxy group with 1 to 3 carbon atoms. n is between 50 and 500.)

Description

[Technical Field]

[0001] The present invention relates to flame retardants, composites, and methods for producing composites. [Background technology]

[0002] Traditionally, flame retardancy in wood has been achieved by injecting flame retardants into the wood under high temperature and pressure. This method requires injecting approximately 350g or more of flame retardant per kilogram of wood. Furthermore, after impregnating dried wood with an aqueous solution of flame retardant, the wood must be dried again. Therefore, the energy required for drying is significant, resulting in a high environmental burden. On the other hand, in Japan, wooden construction is attracting attention in order to sequester carbon dioxide in proportion to the amount of wood used, or to utilize wood that has reached its effective lifespan. In particular, mid-to-high-rise buildings of three stories or more, subject to interior finish restrictions, are being planned. For this purpose, flame retardancy of the wood used is essential, and the use of flame retardants for wood is expected to expand in the future.

[0003] For wood flame retardants, less toxic, non-halogen types are used. Among non-halogen flame retardants, phosphorus-based flame retardants and synergistic phosphorus-nitrogen-based flame retardants are widely used because they dissolve easily in water, can be impregnated in large quantities into wood, and easily provide flame retardant performance. These flame retardants are the mainstream flame retardants for commercially available flame-retardant treated wood. However, these flame retardants have durability problems, such as deliquescing or leaching when wet or placed in a humid environment, which impairs their fire-retardant performance, and efflorescence, a white stain that occurs when the deliquesced flame retardant dries.

[0004] Besides phosphorus-based and synergistic flame retardants, non-halogen flame retardants include boron-based flame retardants (see, for example, Patent Document 1) and silicon-based flame retardants (see, for example, Patent Document 2). Boron-based flame retardants are poorly soluble in water and do not easily penetrate wood, resulting in inferior flame retardancy and the problem of efflorescence, where crystals of the chemical component form on the surface. Silicon-based flame retardants provide high flame retardancy, but the solution has a short lifespan, making it undesirable to flame retard wood using conventional impregnation methods. Instead, it is preferable to flame retard wood by applying it to the surface (application method). In the application method, it is expected that a glassy film will form on the surface of the wood, blocking oxygen during heating and thus exhibiting flame retardancy. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-122612 [Patent Document 2] Japanese Patent Publication No. 2014-162807 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above circumstances, and aims to provide a flame retardant, a composite, and a method for manufacturing the composite, which can form a flame-retardant coating by being applied to the surface of wood or impregnated into wood. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A flame retardant comprising a polyborosiloxane structure represented by the following formula (1).

[0008] [ka] (However, R is an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. n is between 50 and 500.)

[0009] [2] The flame retardant according to [1], wherein the polyborosiloxane represented by formula (1) above has a ratio of boron atoms (B) to silicon atoms (Si) (B / Si) of r of 0.35 or more and 0.80 or less. [3] The weight-average molecular weight (Mw) of the polyborosiloxane represented by formula (1) above is 5.0 × 10⁻⁶ 3 The above 5.0 x 10 4 The following are flame retardants as described in [1] or [2]. [4] comprising wood and a flame-retardant film covering the surface of the wood, The flame-retardant film is a composite comprising any of the flame retardants described in [1] to [3]. [5] A step of preparing a solution containing a flame retardant by dissolving the flame retardant described in any of [1] to [3] in an organic solvent, A step of applying the solution to the surface of the wood or impregnating the wood with the solution, A method for producing a composite, comprising the steps of: drying wood to which the solution has been applied or impregnated, thereby forming a flame-retardant film containing the flame retardant on the surface of the wood. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a flame retardant, a composite, and a method for producing the composite, which can form a flame-retardant coating by being applied to the surface of wood or impregnated into wood. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view showing a composite device according to one embodiment of the present invention. [Figure 2] This figure shows the heat resistance test of test specimen 1, test specimen 2, and wood by differential thermal analysis in Example 1. [Figure 3] This figure shows the results of measuring the total heat generation (THR) of test specimens 3 and 4 in Example 2. [Figure 4] It is a diagram showing the result of measuring the total smoke emission (TSP) of the test piece 4 and wood in Example 3. [Figure 5] It is a diagram showing the result of measuring the total heat release (THR) of the test piece 5 and wood in Example 4.

Embodiments for Carrying Out the Invention

[0012] Embodiments of the flame retardant, composite, and method for producing the composite of the present invention will be described. Note that this embodiment is specifically described to better understand the gist of the invention, and does not limit the present invention unless otherwise specified.

[0013] [Flame Retardant] The flame retardant according to an embodiment of the present invention contains a polyborosiloxane structure represented by the following formula (1).

[0014]

Chemical Formula

[0015] The polyborosiloxane represented by the above formula (1) is a copolymer of alkoxysilane and boric acid.

[0016] In the polyborosiloxane represented by the above formula (1), R is preferably a methyl group or an ethoxy group.

[0017] In the polyborosiloxane represented by the above formula (1), n is 50 or more and 500 or less, and preferably 50 or more and 100 or less. When n is less than the lower limit value, it becomes a solid with low solubility. When n exceeds the upper limit value, it becomes difficult to solidify after being applied or impregnated into wood, and a flame retardant film is not formed.

[0018] In the polyborosiloxane represented by formula (1) above, the ratio of boron atoms (B) to silicon atoms (Si) (B / Si), r, is preferably 0.35 or more and 0.80 or less, and more preferably 0.5 or more and 0.75 or less. If r is less than the lower limit, no coating film will be formed. If r exceeds the upper limit, the adhesion of the coating film will be low, and a flame-retardant film will not be formed.

[0019] The weight-average molecular weight (Mw) of the polyborosiloxane represented by the above formula (1) is 5.0 × 10⁻⁶. 3 The above 5.0 x 10 4 The following is preferable: If the weight-average molecular weight (Mw) is less than the lower limit, it will be difficult to solidify after application to or impregnation of wood, and a flame-retardant film will not be formed. If the weight-average molecular weight (Mw) exceeds the upper limit, it will become a solid with low solubility.

[0020] The number-average molecular weight (Mn) of the polyborosiloxane represented by the above formula (1) is 5.0 × 10⁻⁶. 2 The above 5.0 x 10 3 The following is preferable: If the number average molecular weight (Mn) is less than the lower limit, it will be difficult to solidify after application to or impregnation of wood, and a flame-retardant film will not be formed. If the number average molecular weight (Mn) exceeds the upper limit, it will become a solid with low solubility.

[0021] It is preferable that the ratio (Mw / Mn) of the weight-average molecular weight (Mw) of the polyborosiloxane represented by formula (1) to the number-average molecular weight (Mn) of the polyborosiloxane represented by formula (1) above is 1.5 or more and 5.0 or less. If the ratio (Mw / Mn) is less than the lower limit, it will be difficult to solidify after application to or impregnation of wood, and a flame-retardant film will not be formed. If the ratio (Mw / Mn) exceeds the upper limit, a coating film will not be formed.

[0022] According to the flame retardant of this embodiment, a flame-retardant coating can be formed by applying it to the surface of wood or by impregnating the wood with it.

[0023] [Method for producing polyborosiloxane] The method for producing polyborosiloxane represented by the above formula (1) will be explained. The method for producing polyborosiloxane is based on the following chemical reaction equation (2).

[0024] [ka]

[0025] (Manufacturing method 1) Add a predetermined amount of boric acid to ethanol, stir and mix at 85°C for 5 minutes to obtain an ethanol solution containing boric acid. Next, a predetermined amount of alkoxysilane is added to the ethanol solution and stirred and mixed at 95°C for 3 hours. As the alkoxysilane (R-Si-(OEt)3), R can be an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. Next, the ethanol solution is distilled at 95°C. Next, the ethanol solution after distillation is stirred and mixed at 95°C for 12 hours. Next, the mixture is vacuum-dried to obtain the polyborosiloxane represented by formula (1) above.

[0026] (Manufacturing method 2) Add a predetermined amount of boric acid to ethanol, stir and mix at 85°C for 5 minutes to obtain an ethanol solution containing boric acid. Next, a predetermined amount of alkoxysilane is added to the ethanol solution and distilled at 95°C. As the alkoxysilane (R-Si-(OEt)3), R can be an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. Next, the ethanol solution after distillation is stirred and mixed at 95°C for 5 hours to obtain the polyborosiloxane represented by formula (1) above.

[0027] [complex] A composite according to one embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a perspective view showing the composite of this embodiment. As shown in Figure 1, the composite 1 of this embodiment comprises wood 2 and a flame-retardant film 3 that covers the surface of the wood 2.

[0028] Wood 2 is not particularly limited as long as it is used for building purposes, furniture making, etc., but examples include wood made from trees such as cedar, cypress, Japanese cypress, pine, chestnut, zelkova, hemlock, and paulownia.

[0029] The flame-retardant film 3 consists of the flame retardant according to the embodiment described above.

[0030] The thickness of the flame-retardant film 3 is preferably 10 nm or more and 100 μm or less, and more preferably 100 nm or more and 50 μm or less. If the thickness of the flame-retardant film 3 is less than the lower limit, no flame-retardant film will be formed. If the thickness of the flame-retardant film 3 exceeds the upper limit, no coating film will be formed.

[0031] The composite 1 of this embodiment comprises wood 2 and a flame-retardant film 3 that covers the surface of the wood 2. Since the flame-retardant film 3 is made of the flame retardant of the above-described embodiment, it has excellent flame retardancy. In addition, the flame retardant constituting the flame-retardant film 3 of the composite 1 of this embodiment may be impregnated deeper than the surface of the wood 2.

[0032] The amount of the flame-retardant film 3, in other words, the mass of the flame-retardant film 3 relative to the total mass (100% by mass) of the composite 1, is preferably 0.01% by mass or more and 300% by mass or less, more preferably 0.1% by mass or more and 100% by mass or less, and even more preferably 1% by mass or more and 50% by mass or less. If the mass of the flame-retardant film 3 is less than the lower limit, the effect of the flame retardant is low. If the mass of the flame-retardant film 3 exceeds the upper limit, it is not possible to form a flame retardant coating.

[0033] [Method for producing the composite] A method for producing a composite according to one embodiment of the present invention comprises the steps of: dissolving the flame retardant of the above embodiment in an organic solvent to prepare a solution containing the flame retardant (hereinafter referred to as the "first step"); applying the solution to the surface of wood or impregnating the wood with the solution (hereinafter referred to as the "second step"); and drying the wood to which the solution has been applied or impregnated to form a flame-retardant film containing the flame retardant on the surface of the wood (hereinafter referred to as the "third step").

[0034] "First step" In the first step, a flame retardant is dissolved in an organic solvent to prepare a solution containing the flame retardant (hereinafter referred to as the "flame retardant solution").

[0035] The organic solvent is not particularly limited as long as it can dissolve the flame retardant of the above embodiment, but examples include methanol, ethanol, isopropyl alcohol, etc.

[0036] The flame retardant content relative to the total mass (100% by mass) of the flame retardant solution is preferably 10% by mass or more and 100% by mass or less, and more preferably 10% by mass or more and 90% by mass or less.

[0037] "The second step" In the second step, a flame retardant solution is applied to the surface of the wood, or the wood is impregnated with the flame retardant solution. From this second step, a coating film consisting of the flame retardant solution is formed on the surface of the wood. Even when the wood is impregnated with the flame retardant solution, the flame retardant solution remains on the surface of the wood, thus forming a coating film.

[0038] Methods for applying a flame retardant solution to the surface of wood include, for example, brush application, roller application, spray application, drip application, and immersion application. Methods for impregnating wood with a flame retardant solution include immersing the wood in the flame retardant solution at room temperature and atmospheric pressure, and injecting the flame retardant solution into the wood under high temperature and high vacuum conditions.

[0039] The amount of flame retardant solution applied to the surface of the wood is 0.01 g / cm².2 More than 0.1g / cm 2 The following conditions are preferable: If the amount of flame retardant solution applied is less than the lower limit, a flame retardant film will not be formed. If the amount of flame retardant solution applied exceeds the upper limit, a coating film will not be formed.

[0040] "The third step" In the third step, the wood coated with the flame retardant solution is dried to form a flame retardant film containing the flame retardant of the above embodiment on the surface of the wood.

[0041] The method for drying wood coated with a flame retardant solution is not particularly limited, but can be natural drying, heat drying, vacuum drying, etc.

[0042] According to the method for manufacturing the composite of this embodiment, the composite of the above-described embodiment can be obtained. [Examples]

[0043] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0044] [Synthesis of Polyborosiloxane 1] 37.9 g of ethanol and 7.41 g of boric acid were placed in a three-necked flask and stirred and mixed at 85°C for 5 minutes to obtain an ethanol solution containing boric acid. Next, 35.7 g of triethoxy(methyl)silane (MTES) was added to the ethanol solution and stirred and mixed at 95°C for 3 hours. Next, the ethanol solution was distilled at 95°C. Next, the ethanol solution after distillation was stirred and mixed at 95°C for 12 hours. Next, the material was vacuum-dried to obtain polyborosiloxane (PBS) 1 containing MTES.

[0045] [Synthesis of Polyborosiloxane 2] 47.0 g of ethanol and 9.87 g of boric acid were placed in a three-necked flask and stirred and mixed at 85°C for 5 minutes to obtain an ethanol solution containing boric acid. Next, 35.7 g of tetraethoxysilane (TEOS) was added to the ethanol solution and distilled at 95°C. Next, the ethanol solution after distillation was stirred and mixed at 95°C for 5 hours to obtain polyborosiloxane (PBS) 2 containing TEOS.

[0046] [Synthesis of Polyborosiloxane 3] 23.5 g of ethanol and 6.20 g of boric acid were placed in a three-necked flask and stirred and mixed at 85°C for 5 minutes to obtain an ethanol solution containing boric acid. Next, 17.8 g of triethoxy(methyl)silane (MTES) was added to the ethanol solution and stirred and mixed at 95°C for 3 hours. Next, the ethanol solution was distilled at 95°C. Next, the ethanol solution after distillation was stirred and mixed at 95°C for 12 hours. Next, the material was vacuum-dried to obtain polyborosiloxane (PBS) 3 containing MTES.

[0047] [Preparation of Test Specimen 1 and Test Specimen 2] Polyborosiloxane 1 was applied directly to a piece of wood (cypress, a cube with sides of approximately 2 mm). Afterward, it was allowed to air dry for 24 hours to obtain test specimen 1. Similarly, test specimen 2 was prepared using polyborosiloxane 2 instead of polyborosiloxane 1.

[0048] [Preparation of test specimens 3 and 4] A solution of polyborosiloxane 1 in ethanol (hereinafter referred to as "ethanol solution 1") was prepared by dissolving 50.8 g of polyborosiloxane 1 in 10 g of ethanol. The wood (cedar, boards measuring 100mm high x 100mm wide x approximately 10mm thick) was dried in an oven at 50°C for 3 days (Process A1). Next, the wood was immersed in ethanol solution 2 for 12 hours (step B1). Next, the wood was removed from ethanol solution 2 and air-dried for 6 hours (step C1). Next, the wood was vacuum-dried for 18 hours (Process D1). Steps A1 through D1 described above were repeated three times. Subsequently, the specimen was vacuum-dried for two days to obtain specimen 3. Similarly, test specimen 4 was prepared using polyborosiloxane 2 instead of polyborosiloxane 1.

[0049] [Preparation of Test Specimen 5] A tetrahydrofuran solution of polyborosiloxane 3 (hereinafter referred to as "tetrahydrofuran solution 1") was prepared by dissolving 20.0 g of polyborosiloxane 3 in 80.0 g of tetrahydrofuran. The wood (cedar, boards measuring 100mm high x 100mm wide x approximately 10mm thick) was dried in an oven at 23°C under 50% RH humidity for 7 days (Process A2). Next, the wood was immersed in tetrahydrofuran solution 1 and pressure-impregnated under a pressure of 0.8 MPa for 1 hour at room temperature (25°C) (Step B2). Next, the wood was removed from tetrahydrofuran solution 1 and dried at room temperature (25°C) for 24 hours, followed by drying at 60°C for 24 hours, and then further dried at 23°C under 50% RH humidity for 7 days to obtain test specimen 5 (step C2).

[0050] [Example 1] The heat generation behavior of test specimens 1 and 2 was observed. For comparison, the heat generation behavior of the wood used in test specimens 1 and 2 alone was also observed. To observe the exothermic behavior, a heat resistance test was performed using differential thermal analysis (DTA). For differential thermal analysis, a differential thermal and thermogravimetric simultaneous measurement device (TG-DTA) (model name: TG-DTA2020SE, manufactured by Netch Japan Co., Ltd.) was used. The analysis conditions involved heating from 20°C to 800°C at a rate of 10°C per minute under an air atmosphere. The results are shown in Figure 2. Figure 2 shows the heat resistance test using differential thermal analysis. As shown in Figure 2, the calorific value of the 1st peak (cellulose combustion peak) appearing in wood alone was confirmed to be suppressed in test specimens 1 and 2, which had polyborosiloxane applied to the surface of the wood. Furthermore, the calorific value of the 2nd peak (lignin combustion peak) appearing in wood alone was confirmed to be shifted to the high-temperature side in test specimens 1 and 2, which had polyborosiloxane applied to the surface of the wood.

[0051] [Example 2] The total heat generation (THR) of test specimens 3 and 4 was measured. A cone calorimeter (model name: Cone-mini, manufactured by Fire Testing Technology) was used to measure the total calorific value. The total calorific value was evaluated by the oxygen consumption method when test specimen 3 or test specimen 4 was heated. The results are shown in Figure 3. Figure 3 shows the results of measuring the total heat generation of test specimens 3 and 4. As shown in Figure 3, it was confirmed that in the first half of combustion, test specimen 3 had a high total calorific value due to the combustion-supporting effect of ethanol that was not completely dried. Subsequently, in combustion after a flame-retardant film had formed on the surface of the wood, it was confirmed that the increase in total calorific value had slowed down. As shown in Figure 3, it was confirmed that in test specimen 4, the initial combustion was exothermic due to the combustion of polyborosiloxane. Subsequently, in combustion after the formation of a flame-retardant film on the surface of the wood, it was confirmed that the increase in total calorific value was gradual. Furthermore, it was confirmed that in test specimen 2, there was no sharp increase originating from the main peak of heat generation.

[0052] [Example 3] The total smoke output (TSP) of test specimen 3 and the wood was measured. A cone calorimeter (manufactured by Fire Testing Technology) was used to measure the total amount of smoke emitted. The total amount of smoke emitted was evaluated by the oxygen consumption method when test specimen 3 was heated. The results are shown in Figure 4. Figure 4 shows the results of measuring the total smoke output (TSP) of test specimen 3 and the wood. From the results shown in Fig. 4, it was confirmed that in Specimen 3, the total smoke emission was suppressed by 31% compared to the single wood.

[0053] [Example 4] The total heat release (THR) of Specimen 5 and wood was measured. For the measurement of the total heat release, a cone calorimeter (model name: Cone - mini, manufactured by Fire Testing Technology) was used. The total heat release was evaluated by the oxygen consumption method when heating Specimen 5. The results are shown in Fig. 5. Fig. 5 is a diagram showing the results of measuring the total heat release (THR) of Specimen 5 and wood. From the results shown in Fig. 5, the total heat release within 5 minutes after the start of heating of Specimen 5 was 18.4 MJ / m 2 and the total heat release within 5 minutes after the start of heating of untreated wood was 27.3 MJ / m 2 Also, the total heat release within 20 minutes after the start of heating of Specimen 5 was 46.2 MJ / m 2 and the total heat release within 20 minutes after the start of heating of untreated wood was 79.8 MJ / m 2 From these results, it was confirmed that Specimen 5 had a reduced total heat release compared to untreated wood. In addition, the content of the flame retardant in Specimen 5 was 18% by weight.

Explanation of symbols

[0054] 1 Composite 2 Wood 3 Flame - retardant film

Claims

1. A flame retardant containing a polyborosiloxane structure represented by the following formula (1). 【Chemistry 1】 (However, R is an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms. n is between 50 and 500.)

2. The flame retardant according to claim 1, wherein in the polyborosiloxane represented by formula (1) above, r, which represents the ratio of boron atoms (B) to silicon atoms (Si) (B / Si), is 0.35 or more and 0.80 or less.

3. The weight-average molecular weight (Mw) of the polyborosiloxane represented by the above formula (1) is 5.0 × 10⁻⁶. ３ The above 5.0 x 10 ４ The flame retardant according to claim 1, which is as follows:

4. The invention comprises wood and a flame-retardant film covering the surface of the wood, The flame-retardant film is a composite comprising the flame retardant described in any one of claims 1 to 3.

5. A step of preparing a solution containing a flame retardant by dissolving the flame retardant described in any one of claims 1 to 3 in an organic solvent, A step of applying the solution to the surface of the wood or impregnating the wood with the solution, A method for producing a composite, comprising the steps of: drying wood to which the solution has been applied or impregnated, thereby forming a flame-retardant film containing the flame retardant on the surface of the wood.

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