Flame-retardant fireproof silicone sealant and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber, in particular to a flame-retardant fireproof silicone sealant and a preparation method of the flame-retardant fireproof silicone sealant. The coating is prepared from the following components in parts by weight: 40-60 parts of alpha, omega-hydroxyl-terminated polydimethylsiloxane, 10-30 parts of halloysite powder, 15-20 parts of hectorite powder, 2-3 parts of calcium borate, 1-3 parts of magnesium borate, 1-3 parts of aluminum powder, 1-2 parts of boron carbide powder, 3-5 parts of modified nano zirconium phosphate, 0.1-1 part of a catalyst and 1-3 parts of organic bentonite. The halloysite powder and the hectorite powder are added as fireproof flame-retardant fillers, the calcium borate and the magnesium borate are added as fluxing agents, the aluminum powder and the boron carbide powder are added as sintering aids, and the organic bentonite is added as an anti-collapse agent, so that a prepared silicone adhesive sample can keep good physical and chemical properties; moreover, the thermal stability and fire resistance are also remarkably improved, and the flame-retardant and fireproof performance of the silicone sealant can be enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of silicone rubber, and in particular to a flame retardant and fireproof silicone sealant and a preparation method thereof. Background Art

[0002] Fires can cause great harm to people's lives, especially when the glass curtain wall of a building is broken or the gaps between the floor slabs are not tight, which may cause flames and smoke to spread to the surrounding rooms. Toxic smoke can also spread everywhere through cable holes, elevator shafts, etc. In order to prevent the spread of fire sources, the prior art proposes to use silicone sealants as sealing materials to control the spread of fire sources, but traditional silicone sealants themselves have poor flame retardant and fire resistance. Under fire conditions, it is very easy to burn and cause the fire to spread, limiting the safety and practicality of their use. The prior art further proposes silicone materials, which are inherently flammable. The pore structure inside the silicone foam will make the material easier to decompose and burn when it encounters fire, and release smoke and toxic gases. Therefore, it is very important to modify them to be flame retardant to improve fire safety.

[0003] In the process of modifying organosilicon materials, magnesium hydroxide, aluminum hydroxide, diatomaceous earth / aluminum hydroxide, ammonium polyphosphate, melamine / expanded graphite, hexaphenoxy cyclotriphosphazene / expanded graphite, aluminum hypophosphite / zinc borate, and dimethyl methylphosphonate microcapsules are usually added as flame retardants, but the addition of these flame retardants will reduce the thermal stability of the material, especially the initial thermal decomposition temperature. In response to this problem, ceramic polymers represented by ceramic silicone adhesives have been further proposed as flame retardant and fireproof materials. However, in order to achieve high-temperature ceramicization of silicone adhesives, it is necessary to add a high content of mica, kaolin, aluminum silicate and other ceramic powders to the ceramic polymers. Such additives have low flame retardant efficiency and will also lead to the problem of low flame retardant performance of ceramic silicone adhesives. In addition, in order to improve the flame retardant effect, the addition of aluminum hydroxide or phosphorus / nitrogen-containing composite flame retardants during the modification process will also lead to a decrease in the physical and chemical properties of silicone rubber materials and the decomposition and expansion of the flame retardant or the generation of H2O, thereby damaging the high-temperature ceramicization performance of silicone adhesives. Summary of the invention

[0004] The purpose of the present invention is to address the problem in the prior art that the addition of ceramic powder in ceramic silicone adhesive affects the flame retardant efficiency, and the addition of aluminum hydroxide or phosphorus / nitrogen-containing composite flame retardant during the modification process causes the physical and chemical properties of the silicone rubber material to decrease and the flame retardant to chemically decompose, thereby damaging the high-temperature ceramic performance of the silicone adhesive and resulting in poor flame retardant performance. A flame retardant and fireproof silicone sealant and a preparation method thereof are proposed. In a flame retardant and fireproof silicone sealant, halloysite powder and hectorite powder are added as fireproof and flame retardant fillers, calcium borate and magnesium borate are added as fluxing agents, aluminum powder and boron carbide powder are added as sintering aids, and organic bentonite is added as an anti-slump agent. The silicone adhesive sample prepared based on the components such as the added fluxing agent, sintering aid and anti-slump agent can maintain good physical and chemical properties, and the thermal stability and fire resistance are also significantly improved, which is more conducive to enhancing the flame retardant and fireproof properties of the silicone sealant.

[0005] In a first aspect, the present invention provides a flame retardant and fireproof silicone sealant, which is made of the following components in parts by weight: 40-60 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 10-30 parts of halloysite powder, 15-20 parts of laponite powder, 2-3 parts of calcium borate, 1-3 parts of magnesium borate, 1-3 parts of aluminum powder, 1-2 parts of boron carbide powder, 3-5 parts of modified nano zirconium phosphate, 0.1-1 parts of catalyst and 1-3 parts of organic bentonite.

[0006] Furthermore, the weight proportion of the α,ω-hydroxy-terminated polydimethylsiloxane is 45-60 parts.

[0007] Furthermore, the weight proportion of the halloysite powder is 10-25 parts.

[0008] Furthermore, the weight proportion of the boron carbide powder is 1-1.5 parts.

[0009] Furthermore, the weight proportion of the modified nano zirconium phosphate is 3-4 parts.

[0010] Furthermore, the weight portion of the catalyst is 0.5-0.7 parts.

[0011] Furthermore, the catalyst is at least one of dibutyltin dilaurate or stannous octoate.

[0012] In a second aspect, the present invention provides a method for preparing a flame retardant and fireproof silicone sealant, which is used to prepare a flame retardant and fireproof silicone sealant described in any embodiment, comprising the following steps: Add α,ω-hydroxy-terminated polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into a kneader, mix them uniformly at a mixing temperature of 120 to 160° C. and a pressure of 0.05 to 0.10 MPa, and cool them to 20 to 30° C. after uniform mixing to obtain a base material; The base material is added into a grinder for grinding, and the catalyst and the ground material are added into a stirrer for mixing and stirring for 0.5 to 1.5 hours to obtain a silicone sealant.

[0013] Furthermore, before adding α,ω-terminated hydroxyl-polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into the kneader, the method also includes: mixing the aluminum powder and the boron carbide evenly, placing them in a muffle furnace at 1000°C for ablation for 1 hour, and grinding the ablation product.

[0014] Furthermore, before adding α,ω-hydroxy-terminated polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into the kneader, the method further comprises: mixing 4-piperidinic acid and dichloromethane to generate 4-piperidinic acid chloride; The 4-piperidinyl chloride and the silane coupling agent KH-550 are added to toluene for heating, and the α-zirconium phosphate is added to another portion of toluene for ultrasonic stripping; The two products obtained by heating and ultrasonic stripping are reacted at a temperature of 15 to 35° C. for 4 to 6 hours, and the products after the reaction are filtered and dried to obtain the modified nano zirconium phosphate.

[0015] The beneficial effects achieved by the present invention are as follows: In a flame retardant and fireproof silicone sealant provided by an embodiment of the present invention, by adding halloysite powder and hectorite powder as fireproof and flame retardant fillers, adding calcium borate and magnesium borate as fluxing agents, adding aluminum powder and boron carbide powder as sintering aids, and adding organic bentonite as an anti-slump agent, the silicone sealant sample prepared based on the added fluxing agent, sintering aid and anti-slump agent and other components can maintain good physical and chemical properties, and the thermal stability and fire resistance are also significantly improved, which is more conducive to enhancing the flame retardant and fireproof properties of the silicone sealant.

[0016] The above invention content is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0018] Figure 1 This is a thermogravimetric test curve of a flame retardant and fireproof silicone sealant provided in Example 1 of the present invention; Figure 2 This is a thermogravimetric test curve of a flame retardant and fireproof silicone sealant provided in Example 2 of the present invention; Figure 3 This is a thermogravimetric test curve of a flame retardant and fireproof silicone sealant provided in Example 3 of the present invention; Figure 4 This is a thermogravimetric test curve of a flame retardant and fireproof silicone sealant provided in the fourth embodiment of the present invention; Figure 5 This is a thermogravimetric test curve of a flame retardant and fireproof silicone sealant provided in Example 5 of the present invention; Figure 6 This is a tensile performance test curve of a flame retardant and fireproof silicone sealant provided in Example 1 of the present invention; Figure 7 This is a tensile performance test curve of a flame retardant and fireproof silicone sealant provided in Example 2 of the present invention; Figure 8 This is a tensile performance test curve of a flame retardant and fireproof silicone sealant provided in Example 3 of the present invention; Fig. 9 This is a tensile performance test curve of a flame retardant and fireproof silicone sealant provided in Example 4 of the present invention; Fig.10 This is a tensile performance test curve of a flame retardant and fireproof silicone sealant provided in Example 5 of the present invention; Fig.11 This is a compression performance test curve of a flame retardant and fireproof silicone sealant provided in Example 1 of the present invention; Fig.12 This is a compression performance test curve of a flame retardant and fireproof silicone sealant provided in Example 2 of the present invention; Fig.13 This is a compression performance test curve of a flame retardant and fireproof silicone sealant provided in Example 3 of the present invention; Fig.14 This is a compression performance test curve of a flame retardant and fireproof silicone sealant provided in the fourth embodiment of the present invention; Fig.15 This is a compression performance test curve of a flame retardant and fireproof silicone sealant provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0022] In this article, when referring to the units of the data range, if there is a unit only after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 0.4~1.0μm means that the units of the left endpoint "0.4" and the right endpoint "1.0" are both μm (micrometers).

[0023] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0024] The temperature parameters in the present invention, if not specifically limited, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. In the description of the invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0025] If there is no special description, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution. If there is no special description, all steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0026] Embodiment 1 The present embodiment provides a flame retardant and fireproof silicone sealant, which is made of the following components in parts by weight: 40-60 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 10-30 parts of halloysite powder, 15-20 parts of laponite powder, 2-3 parts of calcium borate, 1-3 parts of magnesium borate, 1-3 parts of aluminum powder, 1-2 parts of boron carbide powder, 3-5 parts of modified nano zirconium phosphate, 0.1-1 parts of catalyst and 1-3 parts of organic bentonite.

[0027] Among them, α, ω-terminated hydroxyl polydimethylsiloxane is 107 glue, halloysite powder and hectorite powder are used as fire retardant fillers, calcium borate and magnesium borate are used as fluxes, aluminum powder and carbonized shed powder are used as sintering aids, aluminum powder is metallic aluminum powder, organic bentonite is used as an anti-slump agent, and the catalyst is dibutyltin dilaurate or stannous octoate.

[0028] Specifically, the preparation process of flame retardant and fireproof silicone sealant includes: taking metal aluminum powder and boron carbide and mixing them evenly, ablating them in a muffle furnace at 1000℃ for 1h, grinding the ablation product to break it. In addition, a self-made high-efficiency flame retardant is a modified nano zirconium phosphate, which is prepared by reacting 4-piperidinic acid and dichloromethane to generate 4-piperidinic acid chloride; then adding 4-piperidinic acid chloride and silane coupling agent KH-550 to toluene and heating them to react to generate products; in addition, α-zirconium phosphate is added to another portion of toluene for ultrasonic stripping and then added to the product generated by the previous reaction, reacting in an environment of 15-35℃ for 4-6 hours, and filtering the final product, washing it with ethanol, and then drying it in an oven to obtain modified nano zirconium phosphate.

[0029] Further, the product of mixed ablation and grinding of α,ω-terminated hydroxyl polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder and boron carbide powder, modified nano zirconium phosphate and organic bentonite are added to a kneader, uniformly mixed at a mixing temperature of 120-160° C. and a pressure of 0.05-0.10 MPa, and cooled to 20-30° C. after uniform mixing to obtain a base material. That is, α,ω-terminated hydroxyl polydimethylsiloxane, fire-retardant filler, flux, sintering aid and anti-slump agent are added to a kneader for kneading, so that the prepared base material has flame retardant, fireproof and physical and mechanical performance requirements. Furthermore, after the base material is prepared, the base material is added to a three-roll grinder for sufficient grinding, and finally the catalyst and the ground material are added to a mixer for mixing and stirring for 0.5 to 1.5 hours, and vacuum-packed to obtain a high-temperature ablation-resistant and high-fire-resistant elastic sealing material, that is, a silicone sealant.

[0030] As a specific embodiment, 40 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 30 parts of halloysite powder, 20 parts of laponite powder, 3 parts of calcium borate, 3 parts of magnesium borate, 3 parts of aluminum powder, 2 parts of boron carbide powder, 5 parts of modified nano zirconium phosphate, 0.5 parts of catalyst and 1 part of organic bentonite are taken respectively. 40 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 30 parts of halloysite powder, 20 parts of laponite powder, 3 parts of calcium borate, 3 parts of magnesium borate, 3 parts of aluminum powder, 2 parts of boron carbide powder, 5 parts of modified nano zirconium phosphate and 1 part of organic bentonite are added into a kneader, kneaded fully, the temperature is controlled to be 120-160°C, the pressure is 0.05-0.10MPa, mechanically mixed and stirred, the mixture is dehydrated, and cooled to 20-30°C to obtain a base material. The base material is added to a three-roll mill for full grinding, and finally the material enters a planetary mixer, 0.5 parts of a catalyst is added and reacted for 0.5 to 1.5 hours to obtain a silicone sealant.

[0031] In an embodiment of the present invention, by adding halloysite powder and laponite powder as fire-retardant fillers, adding calcium borate and magnesium borate as fluxes, adding aluminum powder and boron carbide powder as sintering aids, and adding organic bentonite as an anti-slump agent, the silicone sealant sample prepared based on the added flux, sintering aid and anti-slump agent components can maintain good physical and chemical properties, and the thermal stability and fire resistance are also significantly improved, which is more conducive to enhancing the flame retardant and fireproof properties of silicone sealant, and realizing the flame retardant / fireproof integration of silicone sealant.

[0032] Embodiment 2 In this embodiment, a flame retardant and fireproof silicone sealant is made of the following components in parts by weight: 45 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 25 parts of halloysite powder, 19 parts of laponite powder, 2.5 parts of calcium borate, 2 parts of magnesium borate, 2 parts of aluminum powder, 1 part of boron carbide powder, 4 parts of modified nano zirconium phosphate, 0.1 parts of catalyst, and 2 parts of organic bentonite.

[0033] Add 45 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 25 parts of halloysite powder, 19 parts of laponite powder, 2.5 parts of calcium borate, 2 parts of magnesium borate, 2 parts of aluminum powder, 1 part of boron carbide powder, 5 parts of modified nano zirconium phosphate and 2 parts of organic bentonite into a kneader, knead thoroughly, control the temperature to 120-160°C, the pressure to 0.05-0.10MPa, mechanically mix and stir, dehydrate the mixture, cool to 20-30°C, and obtain a base material. Add the base material to a three-roll mill and grind it thoroughly. Finally, the material enters a planetary mixer, adds 0.1 parts of a catalyst and reacts for 0.5-1.5h to obtain a silicone sealant.

[0034] Embodiment 3 In this embodiment, a flame retardant and fireproof silicone sealant is made of the following components in parts by weight: 50 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 20 parts of halloysite powder, 18 parts of laponite powder, 4 parts of calcium borate, 2.5 parts of magnesium borate, 1 part of aluminum powder, 1.5 parts of boron carbide powder, 3 parts of modified nano zirconium phosphate, 0.3 parts of catalyst, and 3 parts of organic bentonite.

[0035] Add 50 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 20 parts of halloysite powder, 18 parts of laponite powder, 4 parts of calcium borate, 2.5 parts of magnesium borate, 1 part of aluminum powder, 1.5 parts of boron carbide powder, 3 parts of modified nano zirconium phosphate and 3 parts of organic bentonite into a kneader, knead thoroughly, control the temperature to 120-160°C, the pressure to 0.05-0.10MPa, mechanically mix and stir, dehydrate the mixture, cool to 20-30°C, and obtain a base material. Add the base material to a three-roll mill and grind it thoroughly. Finally, the material enters a planetary mixer, adds 0.3 parts of a catalyst and reacts for 0.5-1.5h to obtain a silicone sealant.

[0036] Embodiment 4 In this embodiment, a flame retardant and fireproof silicone sealant is made of the following components in parts by weight: 55 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 18 parts of halloysite powder, 30 parts of laponite powder, 2 parts of calcium borate, 1.5 parts of magnesium borate, 2.5 parts of aluminum powder, 1 part of boron carbide powder, 4.5 parts of modified nano zirconium phosphate, 0.7 parts of catalyst, and 1 part of organic bentonite.

[0037] Add 55 parts of α,ω-terminated hydroxyl polydimethylsiloxane, 18 parts of halloysite powder, 30 parts of laponite powder, 2 parts of calcium borate, 1.5 parts of magnesium borate, 2.5 parts of aluminum powder, 1 part of boron carbide powder, 4.5 parts of modified nano zirconium phosphate and 1 part of organic bentonite into a kneader, knead thoroughly, control the temperature to 120-160°C, the pressure to 0.05-0.10MPa, mechanically mix and stir, dehydrate the mixture, cool to 20-30°C, and obtain a base material. Add the base material to a three-roll mill and grind it thoroughly. Finally, the material enters a planetary mixer, adds 0.7 parts of a catalyst and reacts for 0.5-1.5h to obtain a silicone sealant.

[0038] Embodiment 5 In this embodiment, a flame retardant and fireproof silicone sealant is made of the following components in parts by weight: 60 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 10 parts of halloysite powder, 15 parts of laponite powder, 2 parts of calcium borate, 1 part of magnesium borate, 1.5 parts of aluminum powder, 1 part of boron carbide powder, 3.5 parts of modified nano zirconium phosphate, 1 part of catalyst, and 3 parts of organic bentonite.

[0039] 60 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 10 parts of halloysite powder, 15 parts of laponite powder, 2 parts of calcium borate, 1 part of magnesium borate, 1.5 parts of aluminum powder, 1 part of boron carbide powder, 3.5 parts of modified nano zirconium phosphate and 3 parts of organic bentonite are added into a kneader, kneaded fully, the temperature is controlled at 120-160°C, the pressure is 0.05-0.10MPa, mechanically mixed and stirred, the mixture is dehydrated, cooled to 20-30°C, and a base material is obtained. The base material is added into a three-roll mill and fully ground, and finally the material enters a planetary mixer, 1 part of a catalyst is added and reacted for 0.5-1.5h to obtain a silicone sealant.

[0040] For the above-mentioned embodiments 1 to 5, the basic properties of the silicone sealants prepared are shown in the following Table 1: Table 1 Basic properties of silicone sealant Based on the analysis in Table 1, the silicone sealants prepared in Examples 1 to 5 show a fine, uniform paste appearance, no bubbles, no lumps, no crusts, no gels, and no difficulty in dispersion. At the same time, they show good indexes in terms of sag, surface drying time, extrudability, elastic recovery rate, tensile modulus at different temperatures, fixed stretch adhesion, adhesion after cold drawing and hot pressing, and fixed stretch adhesion after immersion in water.

[0041] For the above-mentioned Examples 1 to 5, the flame retardant and fire resistant properties of the silicone sealants prepared respectively are shown in Table 2 below: Table 2 Flame retardant and fire resistance properties of silicone sealant Among them, the fire protection level refers to the GB / T23864 test, and the flame retardant level refers to the GB / T24267 test. Based on the analysis of Table 2, the flame retardant and fire-resistant performance analysis based on the three indicators of mass loss, fire protection level and flame retardant level found that the fire protection level can reach or even exceed level 2, and the fire resistance limit is ≥2.0h; the flame retardant level reaches FV-0, and the mass loss is also low. It can be seen that the silicone sealant provided in Implementations 1 to 5 of this application has good performance in both fire protection and flame retardancy.

[0042] For the above-mentioned Examples 1 to 5, the performance of the corresponding TG data of the thermal stability of the silicone sealants prepared respectively is shown in Table 3 below: Table 3 TG data of silicone sealant sample T5％(℃) Residual weight rate (%) Embodiment 1 379.5 76.1 Embodiment 2 393.1 69.0 Embodiment 3 405.5 69.4 Embodiment 4 418.7 62.8 Embodiment 5 428.5 58.6 Among them, T5% refers to the temperature corresponding to the material weight loss rate of 5%. The higher the T5% temperature, the stronger the ability of the material to maintain its original quality in a high temperature environment, that is, the better the thermal stability. A higher residual weight rate means that the material can maintain a higher mass retention rate during the heating process, that is, it has a stronger resistance to thermal decomposition, and thus better thermal stability. It can be seen from Table 3 that the silicone sealant prepared based on the above-mentioned Examples 1 to 5 performs well in T5% and residual weight rate, with an average T5% of 400°C and an average residual weight rate of 66.8%. Among them, the thermal stability is tested using a STA6000 thermogravimetric analyzer. The test is carried out in a nitrogen atmosphere, with a heating rate of 20°C / min and a test range of 40-800°C.

[0043] At the same time, combined Figure 1-5 As shown, Figure 1-5 The thermogravimetric test curves of a flame retardant and fireproof silicone sealant corresponding to Examples 1 to 5 are shown in order. The thermogravimetric test curve is used to analyze the thermal stability of the material. Figure 1-5 Analysis shows that the weight percentage of the sample decreases as the temperature increases. After the initial stage, the downward trend of the curve becomes more gentle, and the weight loss is less. Therefore, the sample maintains a high weight stability during the heating process, which also indicates that the sample has strong thermal stability. And from the perspective of weight loss temperature, there is no obvious weight loss in the initial stable stage of the curve within a certain temperature range, for example: Figure 5 The weight is kept relatively stable between 100℃ and 300℃. The temperature range during this stage is relatively wide, which also shows that the sample starts to lose weight at a higher temperature. Therefore, it also reflects that the silicone sealant sample has strong thermal stability. In addition, from the perspective of weight change rate, in the DTG curve, the peak value represents the point with the fastest weight change rate. The weight change of the DTG curve during heating is relatively gentle, and there is no drastic weight loss process. From this aspect, it also reflects that the silicone sealant sample has good thermal stability.

[0044] Combination Figure 6-10 As shown, Figure 6-10 The following are the tensile performance test curves of the flame retardant and fireproof silicone sealants corresponding to Examples 1 to 5. Figure 6-10 According to the analysis, the stress and strain maintain an approximately linear relationship within a certain range, and the slope is stable, and the elastic modulus remains stable until it reaches a peak and then falls, for example: Figure 1 The fall occurred when the medium strain reached 55% and the tensile stress reached about 05.2MPa. The tensile strength and elongation at break corresponding to each embodiment when testing the tensile properties are shown in Table 4 below: Table 4 Tensile test data of silicone sealant Among them, the tensile properties are tested using a mechanical properties tester in accordance with GB / T13477. The tensile properties are analyzed based on tensile strength and elongation at break. The higher the tensile strength, the greater the stress that the material can withstand without breaking when stretched, and the better the tensile properties. The higher the elongation at break, the greater the deformation that the material can produce without breaking during the stretching process, which also reflects the good tensile properties of the material. From Table 4 and Figure 6-Figure 10 Analysis shows that the silicone sealant prepared based on the above embodiments 1 to 5 has a maximum tensile strength of 0.52 MPa and a maximum elongation at break of 60%. While enhancing the fire retardant properties, it can still maintain a certain stability in tensile strength and elongation at break.

[0045] Combination Figure 11-15 As shown, Figure 11-15 The following are compression performance test curves of a flame retardant and fireproof silicone sealant corresponding to Examples 1 to 5. In the compression test, as the compression force increases, the compressive stress of the material increases, and the material undergoes compressive strain. When the compressive stress reaches a certain critical value, the material is damaged. The compressive stress at this time is the compressive strength. For the above Examples 1 to 5, the compression performance of the silicone sealants prepared respectively is shown in Table 5 below: Table 5 Compression test data of silicone sealant sample Compression strength(MPa) Embodiment 1 3.97 Embodiment 2 2.56 Embodiment 3 1.94 Embodiment 4 1.56 Embodiment 5 0.32 The compression performance is tested by a mechanical properties tester in accordance with GB / T13477. Compression strength is a property that characterizes the material's ability to resist failure when subjected to pressure, as well as the material's stability during compression. Figure 10-15Analysis shows that the compressive strength of the silicone sealant prepared based on Examples 1 to 5 is between 0.32-3.97 MPa, with an average of 2.07 MPa. Under the GB / T13477 standard, the compressive strength of silicone sealant reaches 2 MPa, which is a relatively high value. Therefore, the silicone sealant prepared in the present invention has a high compression performance.

[0046] According to the above experimental test results, a flame retardant and fireproof silicone sealant provided in an embodiment of the present invention, by adding halloysite powder and hectorite powder as fire retardant fillers, adding calcium borate and magnesium borate as fluxing agents, adding aluminum powder and boron carbide powder as sintering aids and adding organic bentonite as an anti-slump agent, the silicone sealant sample prepared based on the added fluxing agent, sintering aid and anti-slump agent and other components can maintain good physical and chemical properties, and the thermal stability and fire resistance are also significantly improved, which is more conducive to enhancing the flame retardant and fireproof properties of the silicone sealant, and realizing the flame retardant / fireproof integration of the silicone sealant.

[0047] The above specific implementation is a preferred implementation of a flame retardant and fireproof silicone sealant of the present invention, and is not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to this specific implementation. All equivalent changes made in accordance with the shape and structure of the present invention are within the protection scope of the present invention.

Claims

1. A flame retardant and fireproof silicone sealant, characterized in that: The invention is prepared from the following components in parts by weight: 40-60 parts of α, ω-terminated hydroxyl polydimethylsiloxane, 10-30 parts of halloysite powder, 15-20 parts of laponite powder, 2-3 parts of calcium borate, 1-3 parts of magnesium borate, 1-3 parts of aluminum powder, 1-2 parts of boron carbide powder, 3-5 parts of modified nano zirconium phosphate, 0.1-1 parts of catalyst and 1-3 parts of organic bentonite.

2. The flame retardant and fireproof silicone sealant according to claim 1, characterized in that: The weight proportion of the α,ω-terminated hydroxyl polydimethylsiloxane is 45-60 parts.

3. The flame retardant and fireproof silicone sealant according to claim 1, characterized in that: The weight proportion of the halloysite powder is 10-25 parts.

4. The flame retardant and fireproof silicone sealant according to claim 1, characterized in that: The weight proportion of the boron carbide powder is 1-1.5 parts.

5. The flame retardant and fireproof silicone sealant according to claim 1, characterized in that: The weight proportion of the modified nano zirconium phosphate is 3-4 parts.

6. The flame retardant and fireproof silicone sealant according to claim 1, characterized in that: The weight proportion of the catalyst is 0.5-0.7 parts.

7. The flame retardant and fireproof silicone sealant according to claim 6, characterized in that: The catalyst is at least one of dibutyltin dilaurate or stannous octoate.

8. A method for preparing a flame retardant and fireproof silicone sealant, for preparing a flame retardant and fireproof silicone sealant as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: Add α,ω-hydroxy-terminated polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into a kneader, mix them uniformly at a mixing temperature of 120 to 160° C. and a pressure of 0.05 to 0.10 MPa, and cool them to 20 to 30° C. after uniform mixing to obtain a base material; The base material is added into a grinder for grinding, and the catalyst and the ground material are added into a stirrer for mixing and stirring for 0.5 to 1.5 hours to obtain a silicone sealant.

9. The method for preparing a flame retardant and fireproof silicone sealant according to claim 8, characterized in that: Before adding α,ω-terminated hydroxyl-polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into the kneader, the method further comprises: The aluminum powder and the boron carbide are mixed evenly, placed in a muffle furnace at 1000° C. for ablation for 1 h, and the ablation product is ground.

10. The method for preparing a flame retardant and fireproof silicone sealant according to claim 8, characterized in that: Before adding α,ω-terminated hydroxyl-polydimethylsiloxane, halloysite powder, laponite powder, calcium borate, magnesium borate, aluminum powder, boron carbide powder, modified nano zirconium phosphate and organic bentonite into the kneader, the method further comprises: 4-piperidinic acid and dichloromethane are mixed to react to generate 4-piperidinic acid chloride; The 4-piperidinyl chloride and the silane coupling agent KH-550 are added to toluene for heating, and the α-zirconium phosphate is added to another portion of toluene for ultrasonic stripping; The two products obtained by heating and ultrasonic stripping are reacted at a temperature of 15 to 35° C. for 4 to 6 hours, and the products after the reaction are filtered and dried to obtain the modified nano zirconium phosphate.

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