A flame-retardant ceramizable silicone rubber foam, its preparation method and application

Abstract

This invention provides a flame-retardant ceramizable silicone rubber foam, its preparation method, and its applications, belonging to the technical field of flame-retardant ceramizable composite materials. The flame-retardant ceramizable silicone rubber foam of this invention, by weight, comprises 100 parts of silicone rubber foam foaming component, 20-40 parts of flux, 20-50 parts of refractory filler, and 0.5-5 parts of flame-retardant and refractory synergist, wherein the flame-retardant and refractory synergist is a special anionic intercalated layered ternary metal hydroxide containing transition metals. The introduction of the flame-retardant and refractory synergist significantly improves the limiting oxygen index and the ceramic body strength after high-temperature calcination of the silicone rubber foam; therefore, the flame-retardant ceramizable silicone rubber foam material of this invention possesses excellent flame-retardant and refractory properties.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant ceramic composite materials technology, and in particular to a flame-retardant ceramicizable silicone rubber foam, its preparation method, and its application. Background Technology

[0002] Silicone rubber foam is a porous material made from organosilicon elastomer through foaming and vulcanization. It not only possesses the excellent properties of silicone rubber but also offers advantages not found in traditional foam materials, such as weather resistance and compression resilience. Therefore, it is widely used as a high-performance material in construction, chemical industry, electronics, transportation, aerospace, and defense. However, silicone rubber foam is inherently flammable, and after combustion, it forms a loose silica carbon layer, which fails to provide good fire resistance, greatly limiting its application in specialized fields. Therefore, flame-retardant and fire-resistant modification of silicone rubber foam is of great significance.

[0003] Flame-retardant ceramicization technology is an effective means to simultaneously improve the flame-retardant and fire-resistant properties of polymer materials. Flame-retardant ceramicized silicone rubber composites are also one of the most thoroughly and systematically studied polymer materials. However, research on flame-retardant ceramicized silicone rubber foam is still relatively scarce. The introduction of too many fillers can affect the foaming process of silicone rubber foam, so it is necessary to develop fillers with higher flame-retardant ceramicization efficiency. Layered bimetallic hydroxides (LDHs) are a novel inorganic two-dimensional lamellar flame retardant with a unique layered structure. They have the characteristics of adjustable cation types / valence states in the main layer and controllable anions in the interlayer, allowing for the preparation of a wide variety of layered hydroxides with diverse functions. LDHs have already shown good flame-retardant and smoke-suppressing effects in polymer plastics and foam materials. The metal oxides produced by their decomposition can also participate in the ceramicization process, enhancing the strength of the ceramic body. They have good application prospects in flame-retardant ceramicized polymer materials. However, existing LDHs still suffer from low flame-retardant ceramicization efficiency, limiting their improvement on the flame-retardant and fire-resistant properties of silicone rubber foam. Summary of the Invention

[0004] The purpose of this invention is to provide a flame-retardant ceramizable silicone rubber foam, its preparation method and application. By using a flame-retardant and fire-resistant synergist with high flame-retardant ceramization efficiency, the flame-retardant and fire-resistant properties of silicone rubber foam can be significantly improved, meeting its application needs in special fields such as fire protection.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a flame-retardant, ceramizable silicone rubber foam, comprising the following raw materials in parts by weight:

[0007] The composition includes 100 parts silicone rubber foaming component, 20-40 parts flux, 20-50 parts refractory filler, and 0.5-5 parts flame retardant and refractory synergist.

[0008] The general chemical formula of the flame retardant and fire-resistant synergist is [M 2+ 1-x-y M 3+ x M' 3+ y (OH)2] (x+y)+ [A n- (x +y) / n ]·mH2O;

[0009] Among them, M 2+ and M 3+ The corresponding metallic elements are two of the following: iron, copper, titanium, cobalt, zinc, and nickel, M' 3+ It is one of cerium and lanthanum;

[0010] The A n- It contains a transition metal element, which is one of platinum, titanium, molybdenum, iron, copper, nickel, and cobalt.

[0011] Preferably, in the flame retardant and fire-resistant synergist, M 2+ M 3+ and M' 3+ The molar ratio is 4:1:1 to 5:2:1; the M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 1:1 to 2:1.

[0012] Preferably, the preparation method of the flame retardant and fire-resistant synergist includes the following steps:

[0013] Add a mixed solution of the divalent and trivalent metal salts corresponding to M and a sodium hydroxide solution dropwise to a concentration of A. n- After co-precipitation in an anionic salt solution at pH 8-11, followed by aging, a flame retardant and fire-resistant synergist is obtained.

[0014] Preferably, the concentration of the sodium hydroxide solution is 0.05~0.5 mol / L; the coprecipitation reaction is carried out at room temperature for 2~6 h; and the aging time is 8~24 h.

[0015] Preferably, the silicone rubber foaming component includes α,ω-dihydroxy polysiloxane, vinyl-terminated polydimethylsiloxane, low molecular weight hydroxyl silicone oil, hydrogen-containing silicone oil, platinum catalyst, and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.

[0016] Preferably, the flux includes one or more of boron oxide, glass powder, zinc borate, and ammonium polyphosphate.

[0017] Preferably, the refractory filler includes one or more of the following: kaolin, montmorillonite, organically modified montmorillonite, mica powder, diatomaceous earth, calcium carbonate, talc powder, sepiolite, halloysite, vermiculite, and ceramic fiber.

[0018] Preferably, the A n- It includes one of the following: chloroplatinate ion, chloroplatinate ion, tetracyanoplatinate ion, tetranitroplatinate ion, tetrabromoplatinate ion, metatitanate ion, hydrotitanate ion, and heptatadexoacid ion.

[0019] This invention provides a method for preparing the flame-retardant ceramizable silicone rubber foam described in the above technical solution, comprising the following steps:

[0020] The foaming components of silicone rubber foam, flux, refractory filler and flame retardant synergist are mixed in proportion, and the resulting foaming precursor is foamed and heat-treated to obtain flame retardant ceramizable silicone rubber foam.

[0021] This invention provides the application of the flame-retardant ceramizable silicone rubber foam described in the above technical solution or the flame-retardant ceramizable silicone rubber foam prepared by the preparation method described in the above technical solution in the field of fire protection.

[0022] This invention provides a flame-retardant, ceramizable silicone rubber foam material. The flame-retardant and refractory synergist used is a special anionic intercalated layered ternary metal hydroxide containing transition metals. By introducing rare earth elements such as cerium and lanthanum, the agglomeration of the product can be reduced, resulting in a product with better dispersibility, thereby improving its flame-retardant ceramization efficiency. Furthermore, by introducing special anions containing transition metals, the flame-retardant ceramization efficiency of the silicone rubber foam is further improved, making the flame-retardant and refractory synergist exhibit better flame-retardant ceramization performance. Therefore, the introduction of the flame-retardant and refractory synergist in this invention significantly improves the limiting oxygen index (flame-retardant performance) and the strength of the ceramic body after high-temperature calcination (ceramization performance) of the silicone rubber foam.

[0023] Specifically, the mechanism by which the flame-retardant and fire-resistant synergist of the present invention improves the flame-retardant ceramization efficiency is as follows:

[0024] (1) Transition metal elements can catalyze the removal of organic groups on the side chains of silanes, preventing them from forming defects during the ceramicization process and affecting the strength of the ceramic body. Special anionic intercalated layered ternary metal hydroxides containing transition metals can also form metal oxides after decomposition at high temperature, participating in the ceramicization process and playing a reinforcing role. Therefore, flame retardant and fire retardant synergists can promote the ceramicization process and improve the flame retardant and fire retardant properties of silicone rubber foam.

[0025] (2) Ternary layered metal hydroxides have better structural stability and can form more regular layered structures. In particular, with the introduction of rare earth elements such as cerium and lanthanum, the layered structure of ternary layered metal hydroxides is more loose and less prone to agglomeration. This improves its dispersion performance in silicone rubber foam, increases the contact area with the silicone rubber matrix, and improves the flame retardant ceramicization efficiency.

[0026] (3) The special anions are mainly platinum and titanium anions, which can catalyze the hydrosilylation reaction of the silicone rubber matrix, thereby improving the reaction efficiency in the silicone rubber foam preparation process. At the same time, the introduction of such ions can play a good synergistic role with the lamellar metal elements, further improving the flame retardant ceramicization efficiency of the flame retardant and fire retardant synergist.

[0027] This invention enhances the flame retardant and fire-resistant properties of silicone rubber foam through fluxing agents and refractory fillers. The introduction of flame retardant and fire-resistant synergists can act as catalysts, form chars, and dilute flammable gases in the silicone rubber foam, further improving its fire safety in conjunction with fluxing agents and refractory fillers. Therefore, the flame-retardant ceramizable silicone rubber foam material of this invention possesses excellent flame retardant and fire-resistant properties. Attached Figure Description

[0028] Figure 1 CoFeCe-LDH-PtCl4 prepared in Example 2 of this invention XRD patterns;

[0029] Figure 2 CoFeCe-LDH-PtCl4 prepared in Example 2 of this invention TEM images;

[0030] Figure 3 CoFe-LDH-PtCl4 prepared for Comparative Example 3 of this invention TEM images;

[0031] Figure 4 This is a SEM image of the high-efficiency flame-retardant ceramizable silicone rubber foam prepared in Example 2 of the present invention. Detailed Implementation

[0032] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0033] This invention provides a flame-retardant, ceramizable silicone rubber foam, comprising the following raw materials in parts by weight:

[0034] The composition includes 100 parts silicone rubber foaming component, 20-40 parts flux, 20-50 parts refractory filler, and 0.5-5 parts flame retardant and refractory synergist.

[0035] The general chemical formula of the flame retardant and fire-resistant synergist is [M 2+ 1-x-y M 3+ x M' 3+ y (OH)2] (x+y)+ [A n- (x +y) / n ]·mH2O;

[0036] Among them, M 2+ and M 3+ The corresponding metallic elements are two of the following: iron, copper, titanium, cobalt, zinc, and nickel, M' 3+ It is one of cerium and lanthanum;

[0037] The A n- It contains a transition metal element, which is one of platinum, titanium, molybdenum, iron, copper, nickel, and cobalt.

[0038] The raw materials for preparing the flame-retardant, ceramizable silicone rubber foam provided by this invention, by weight, include 100 parts of a silicone rubber foaming component. The silicone rubber foaming component preferably includes α,ω-dihydroxy polysiloxane (viscosity 500~100000 mPa·s), vinyl-terminated polydimethylsiloxane (viscosity 1000~100000 mPa·s), low molecular weight hydroxyl silicone oil, hydrogen-containing silicone oil (hydrogen content 1.6%), platinum catalyst (1000~5000 ppm), and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane. This invention does not impose any special limitations on the proportions of the components in the silicone rubber foaming component; adjustments can be made according to actual needs.

[0039] In the silicone rubber foaming component of this invention, α,ω-dihydroxy polysiloxane and vinyl-terminated polydimethylsiloxane serve as the skeleton materials for room temperature vulcanizing silicone foam. Low molecular weight hydroxyl silicone oil mainly plays the role of foaming aid, hydrogen-containing silicone oil plays the role of crosslinking agent, platinum catalyst plays the role of catalysis, and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane plays the role of slowing down the foaming speed and facilitating operation.

[0040] The present invention does not impose any special limitations on the specific types and sources of the α,ω-dihydroxy polysiloxane, vinyl-terminated polydimethylsiloxane, and platinum catalyst; any conventional commercially available products well known in the art are acceptable.

[0041] Based on the mass fraction of the silicone rubber foam foaming components, the raw materials for preparing the flame-retardant, ceramizable silicone rubber foam provided by this invention include 20-40 parts of flux, more preferably 25-35 parts, and even more preferably 30 parts. The flux preferably includes one or more of boron oxide, glass powder, zinc borate, and ammonium polyphosphate. In this invention, the fluxes are all low-melting-point compounds, primarily functioning to lower the ceramization temperature. This invention does not impose specific limitations on the specific specifications and source of the flux; commercially available products well-known in the art are acceptable.

[0042] Based on the mass fraction of the silicone rubber foam foaming components, the raw materials for preparing the flame-retardant, ceramizable silicone rubber foam provided by this invention include 20-50 parts of refractory filler, more preferably 25-45 parts, and even more preferably 30-40 parts; the refractory filler preferably includes one or more of kaolin, montmorillonite, organically modified montmorillonite, mica powder, diatomaceous earth, calcium carbonate, talc powder, sepiolite, halloysite, vermiculite, and ceramic fiber. In this invention, the refractory filler can improve the fire resistance integrity of the silicone rubber foam at high temperatures. This invention does not impose any special limitations on the specific specifications and source of the refractory filler; commercially available products well-known in the art are acceptable.

[0043] Based on the mass fraction of the silicone rubber foam foaming component, the raw materials for preparing the flame-retardant ceramizable silicone rubber foam provided by the present invention include 0.5 to 5 parts of flame-retardant and fire-resistant synergist, more preferably 1 to 4 parts, and even more preferably 2 to 3 parts.

[0044] In this invention, the general chemical formula of the flame retardant and fire-resistant synergist is [M 2+ 1-x-y M 3+ x M' 3+ y (OH)2] (x+y)+ [A n- (x +y) / n ]·mH2O; where M 2+ and M 3+ The corresponding metallic elements are two of the following: iron, copper, titanium, cobalt, zinc, and nickel, M' 3+ It is one of cerium and lanthanum; the A n- It contains a transition metal element, which is one of platinum, titanium, molybdenum, iron, copper, nickel, and cobalt.

[0045] This invention does not impose any special limitations on the range of values ​​for x, y, m, and n in the flame-retardant and fire-resistant synergist, according to the above M 2 + M 3+ and M' 3+ Metal elements and A n- The types of transition metal elements and their valence states can be determined.

[0046] In this invention, in the flame retardant and fire-resistant synergist, M 2+ M 3+ and M' 3+ The molar ratio is 4:1:1 to 5:2:1, more preferably 9:3:2; the M 2+ M 3+ and M' 3+ Total number of moles and A n- The molar ratio of the components is 1:1 to 2:1, more preferably 1.5 to 2:1. At this ratio, products with better microstructure and morphology can be obtained.

[0047] In this invention, A n- This includes one of the following: chloroplatinate ion, chloroplatinate ion, tetracyanoplate ion, tetranitroplatinate ion, tetrabromoplatinate ion, metatitanate ion, hydrotitanate ion, and heptatadexoacid ion. The present invention relates to the A... n- There are no special restrictions on the type of metal salt; any conventional metal salt containing the aforementioned anions is acceptable.

[0048] In this invention, the preparation method of the flame retardant and fire-resistant synergist preferably includes the following steps:

[0049] Add a mixed solution of the divalent and trivalent metal salts corresponding to M and a sodium hydroxide solution dropwise to a concentration of A. n- After co-precipitation in an anionic salt solution at pH 8-11, followed by aging, a flame retardant and fire-resistant synergist is obtained.

[0050] The present invention does not specifically limit the types of divalent and trivalent metal salts, and any metal salt containing metal element M that is well known in the art is acceptable.

[0051] This invention relates to the concentration of metal salts and the content of A in the mixed solution of divalent and trivalent metal salts. n- There is no specific limit to the concentration of anionic salt solutions, as long as complete dissolution and the required molar ratio are met.

[0052] In this invention, the concentration of the sodium hydroxide solution is preferably 0.05~0.5 mol / L, more preferably 0.1~0.2 mol / L; both the mixed solution and the sodium hydroxide solution are aqueous solutions.

[0053] In this invention, the pH value of the coprecipitation reaction is preferably 8-11, more preferably 9-10; the amount of sodium hydroxide solution used in this invention is sufficient to reach the required pH value.

[0054] The present invention preferably involves adding a mixed solution of divalent and trivalent metal salts and a sodium hydroxide solution dropwise to a concentration of A under stirring conditions at room temperature. n- In the anionic salt solution, the pH value is monitored in real time to keep the pH value of the mixed solution constant until the addition is completed. Stirring is continued to carry out co-precipitation, stirring is stopped and the solution is aged. The aged solution is filtered, washed until neutral, dried, ground and sieved to obtain a special anionic intercalated layered metal hydroxide containing transition metal with a fixed particle size.

[0055] In this invention, the temperature of the co-precipitation reaction is preferably room temperature, and the time is preferably 2-6 h, more preferably 4-5 h; the aging time is 8-24 h, more preferably 12-16 h; the mesh size of the sieve used for sieving is preferably 100-800 mesh, and the particle size of this product ensures its dispersibility and flame-retardant ceramicization efficiency in silicone rubber foam.

[0056] The flame retardant and fire-resistant synergist of this invention is a special anionic intercalated layered ternary metal hydroxide containing a transition metal (the special anion is A). n- It can catalyze the ceramization process and improve the flame retardant and fire-resistant properties of silicone rubber foam; the flame retardant and fire-resistant synergist contains rare earth elements such as cerium and lanthanum, which can reduce its agglomeration and improve its dispersibility in silicone rubber foam; rare earth elements and special anions can further improve the flame retardant and fire-resistant synergist's flame retardant ceramization efficiency.

[0057] This invention provides a method for preparing the flame-retardant ceramizable silicone rubber foam described in the above technical solution, comprising the following steps:

[0058] The foaming components of silicone rubber foam, flux, refractory filler and flame retardant synergist are mixed in proportion, and the resulting foaming precursor is foamed and heat-treated to obtain flame retardant ceramizable silicone rubber foam.

[0059] In this invention, the mixing is preferably carried out at a stirring speed of 500~1200 r / min (more preferably 1000 r / min) for 15~30 min, more preferably 20 min.

[0060] The present invention preferably involves allowing the foaming precursor obtained by mixing to foam at room temperature, and after foaming, placing it in a forced-air drying oven for heat treatment to obtain flame-retardant ceramizable silicone rubber foam.

[0061] The present invention does not have a special limitation on the foaming time. Foaming is considered complete when the foaming height remains unchanged and the foamed product is no longer sticky, according to methods well known in the art.

[0062] In this invention, the heat treatment temperature is preferably 150°C and the time is preferably 2 hours.

[0063] This invention provides the application of the flame-retardant ceramizable silicone rubber foam described in the above-described technical solutions, or the flame-retardant ceramizable silicone rubber foam prepared by the preparation method described in the above-described technical solutions, in the field of fire protection. This invention does not specifically limit the method of application; any method well-known in the art can be used.

[0064] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0065] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.

[0066] In the following examples, the foaming components of the silicone rubber foam are: 75 g α,ω-dihydroxy polysiloxane (viscosity 5000 mPa·s, Shandong Dayi Chemical Co., Ltd.), 25 g vinyl-terminated polydimethylsiloxane (viscosity 10000 mPa·s, Shandong Dayi Chemical Co., Ltd.), 6 g low molecular weight hydroxyl silicone oil, 15 g hydrogen-containing silicone oil (hydrogen content 1.6%), 5 g platinum catalyst (5000 ppm, Dongguan Zhongxin Organosilicon Materials Co., Ltd.), and 0.2 g 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.

[0067] Example 1

[0068] The flame-retardant ceramizable silicone rubber foam provided in this embodiment has the following components by mass: 100 parts silicone rubber foam foaming component, 20 parts boron oxide, 20 parts kaolin, and 1 part flame-retardant and fire-resistant synergist.

[0069] The flame retardant and fire-resistant synergist is CuFeCe-LDH-PtCl6 That is, the metallic element (M) is copper, iron, or cerium, and the special anion (i.e., A) is... n- ) is the chloroplatinate ion, M 2+ M 3+ and M' 3+ The molar ratio is 4:1:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 2:1;

[0070] The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0071] (1) Weigh 0.04 mol copper nitrate, 0.01 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh 0.03 mol potassium chloroplatinate (K2PtCl6) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0072] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0073] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0074] The preparation method of flame-retardant ceramizable silicone rubber foam is as follows:

[0075] The foaming components of silicone rubber foam, flux, refractory filler and flame retardant synergist are mixed in proportion and stirred at 1000 r / min for 20 min. The mixed foaming precursor is placed in a mold and allowed to stand at room temperature for foaming. After foaming, it is placed in a forced-air oven and heat-treated at 150℃ for 2 h to obtain flame retardant ceramizable silicone rubber foam.

[0076] Example 2

[0077] The flame-retardant ceramizable silicone rubber foam provided in this embodiment consists of the following components by mass: 100 parts silicone rubber foam foaming component, 30 parts glass powder, 30 parts montmorillonite, and 1 part flame-retardant and fire-resistant synergist.

[0078] Among them, the metallic elements (M) of the flame retardant and fire-resistant synergist are cobalt, iron, and cerium, and the special anions (i.e., A) n- ) is the chloroplatinate ion (the salt used is potassium chloroplatinate), M 2+ M 3+ and M' 3+ The molar ratio is 9:3:2, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 1:1.

[0079] The flame retardant and fire-resistant synergist is CoFeCe-LDH-PtCl4 The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0080] (1) Weigh out 0.045 mol cobalt nitrate hexahydrate, 0.015 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh out 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh out 0.07 mol potassium chloroplatinate (K2PtCl4) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0081] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0082] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0083] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0084] Example 3

[0085] The flame-retardant ceramizable silicone rubber foam provided in this embodiment consists of the following components by mass: 100 parts silicone rubber foaming component, 40 parts zinc borate, 50 parts vermiculite, and 1 part flame-retardant and fire-resistant synergist.

[0086] Among them, the metallic elements (M) of the flame retardant and fire-resistant synergist are copper, iron, and cerium, and the special anion (i.e., A) n- ) is the tetracyanoplate ion (the salt used is potassium tetracyanoplate trihydrate), M 2+ M 3+ and M' 3+ The molar ratio is 5:2:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 3:2.

[0087] The general chemical formula of the flame retardant and fire-resistant synergist is CuFeCe-LDH-Pt(CN) The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0088] (1) Weigh 0.05 mol copper nitrate, 0.02 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh 0.053 mol potassium tetracyanoplatate trihydrate (K2Pt(CN)4·3H2O) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0089] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0090] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0091] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0092] Example 4

[0093] The flame-retardant ceramizable silicone rubber foam provided in this embodiment, by weight, consists of: 100 parts silicone rubber foam foaming component, 30 parts ammonium polyphosphate, 30 parts mica powder, and 0.5 parts flame-retardant and fire-resistant synergist.

[0094] Among them, the metallic elements (M) of the flame retardant and fire-resistant synergist are zinc, iron, and cerium, and the special anion (i.e., A) n- ) is the tetranitroplatinate ion (the salt used is potassium tetranitroplatinate), M 2+ M 3+ and M' 3+ The molar ratio is 5:2:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 2:1.

[0095] The general chemical formula of the flame retardant and fire-resistant synergist is ZnFeCe-LDH-Pt(N The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0096] (1) Weigh 0.05 mol zinc nitrate, 0.02 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh 0.04 mol potassium tetranitroplatate (K2Pt(NO2)4) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0097] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0098] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0099] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0100] Example 5

[0101] The flame-retardant ceramizable silicone rubber foam provided in this embodiment consists of the following components by mass: 100 parts silicone rubber foaming component, 30 parts zinc borate, 30 parts diatomaceous earth, and 2 parts flame-retardant and fire-resistant synergist.

[0102] Among them, the metallic elements (M) of the flame retardant and fire-resistant synergist are nickel, iron, and cerium, and the special anion (i.e., A) n- ) is the tetrabromoplatinate ion (the salt used is potassium tetrabromoplatinate), M 2+ M 3+ and M' 3+ The molar ratio is 5:2:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 2:1.

[0103] The general chemical formula of the flame retardant and fire-resistant synergist is NiFeCe-LDH-PtB. The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0104] (1) Weigh 0.05 mol nickel nitrate hexahydrate, 0.02 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh 0.04 mol potassium tetrabromoplatinate (K2PtBr4) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0105] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0106] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0107] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0108] Example 6

[0109] The flame-retardant ceramizable silicone rubber foam provided in this embodiment consists of the following components by mass: 100 parts silicone rubber foaming component, 30 parts zinc borate, 30 parts calcium carbonate, and 3 parts flame-retardant and fire-resistant synergist.

[0110] Among them, the metal elements (M) of the flame retardant and fire-resistant synergist are cobalt, iron, and lanthanum, and the special anion (i.e., A) n- ) is the metatitanate ion (the salt used is potassium metatitanate), M 2+ M 3+ and M' 3+ The molar ratio is 5:2:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 2:1.

[0111] The flame retardant and fire-resistant synergist is CoFeLa-LDH-Ti The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0112] (1) Weigh out 0.05 mol of cobalt nitrate hexahydrate, 0.02 mol of ferric nitrate nonahydrate and 0.01 mol of lanthanum nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh out 0.1 mol of sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh out 0.04 mol of potassium metatitanate (K2Ti Dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0113] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0114] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0115] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0116] Example 7

[0117] The flame-retardant ceramizable silicone rubber foam provided in this embodiment consists of the following components by mass: 100 parts silicone rubber foam foaming component, 30 parts zinc borate, 30 parts sepiolite, and 5 parts flame-retardant and fire-resistant synergist.

[0118] Among them, the metallic elements (M) of the flame retardant and fire-resistant synergist are copper, titanium, and cerium, and the special anion (i.e., A) n- ) is the hydrotitanate ion (the salt used is potassium hydrotitanate), M 2+ M 3+ and M' 3+ The molar ratio is 5:2:1, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 2:1.

[0119] The flame retardant and fire-resistant synergist is CuTiCe-LDH-HTi The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0120] (1) Weigh out 0.05 mol copper nitrate, 0.02 mol titanium nitrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh out 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh out 0.04 mol potassium hydrotitanate (KHTi) Dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0121] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0122] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0123] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0124] Comparative Example 1

[0125] The silicone rubber foam provided in this comparative example consists of 100 parts by weight of silicone rubber foam foaming component.

[0126] The composition and preparation method of the silicone rubber foam are the same as in Example 1.

[0127] Comparative Example 2

[0128] The flame-retardant ceramizable silicone rubber foam provided in this comparative example consists of the following components by mass: 100 parts silicone rubber foam foaming component, 30 parts glass powder, and 30 parts montmorillonite.

[0129] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0130] Comparative Example 3

[0131] The flame-retardant ceramizable silicone rubber foam provided in this comparative example consists of the following components by mass: 100 parts silicone rubber foam foaming component, 30 parts glass powder, 30 parts montmorillonite, and 1 part flame-retardant and fire-resistant synergist.

[0132] Among them, the flame retardant and fire-resistant synergist is CoFe-LDH-PtCl4 The metallic element (M) is cobalt or iron, and the special anion (i.e., A) n- ) is the chloroplatinate ion (the salt used is potassium chloroplatinate), M 2+and M 3+ The molar ratio is 3:1, M 2+ and M 3+ Total number of moles and A n- The ratio of the number of moles is 1:1.

[0133] The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0134] (1) Weigh 0.045 mol of cobalt nitrate hexahydrate and 0.015 mol of ferric nitrate nonahydrate, respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh 0.1 mol of sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh 0.06 mol of potassium chloroplatinate (K2PtCl4) and dissolve it in 500 mL of deionized water to prepare a special anionic salt solution containing transition metals;

[0135] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the special anionic salt solution containing transition metals. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the mixture was aged for 12 hours.

[0136] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0137] The preparation method of high-efficiency flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0138] Comparative Example 4

[0139] The flame-retardant ceramizable silicone rubber foam provided in this comparative example consists of the following components by mass: 100 parts silicone rubber foam foaming component, 30 parts glass powder, 30 parts montmorillonite, and 1 part flame-retardant and fire-resistant synergist.

[0140] Among them, the metal element (M) of the flame retardant and fire-resistant synergist is cobalt, iron, or cerium, and the anion is carbonate ion (the salt used is sodium carbonate). 2+ M 3+ and M' 3+ The molar ratio is 9:3:2, M 2+ M 3+ and M' 3+ Total number of moles and A n- The ratio of the number of moles is 1:1.

[0141] The flame retardant and fire-resistant synergist is CoFeCe-LDH-CO3 2- The preparation method of the flame retardant and fire-resistant synergist is as follows:

[0142] (1) Weigh out 0.045 mol cobalt nitrate hexahydrate, 0.015 mol ferric nitrate nonahydrate and 0.01 mol cerium nitrate hexahydrate respectively, and dissolve them in 500 mL of deionized water to prepare a mixed solution of divalent / trivalent metal salts; weigh out 0.1 mol sodium hydroxide and dissolve it in 1 L of deionized water to prepare a sodium hydroxide solution; weigh out 0.07 mol sodium carbonate (Na2CO3) and dissolve it in 500 mL of deionized water to prepare a solution containing anionic salts;

[0143] (2) Under room temperature stirring conditions, the divalent / trivalent metal salt mixed solution and sodium hydroxide solution were added dropwise to the anion salt solution. The pH value was monitored in real time and the pH value of the mixed solution was kept constant at 10 until the divalent / trivalent metal salt mixed solution was completely added. After stirring for 4 hours, stirring was stopped and the solution was aged for 12 hours.

[0144] (3) After aging, the solution is filtered, washed until neutral, dried and ground, and then sieved through a 100-800 mesh sieve to obtain the flame retardant and fire retardant synergist.

[0145] The preparation method of flame-retardant ceramizable silicone rubber foam is the same as in Example 1.

[0146] Characterization and performance testing

[0147] 1) Figure 1 CoFeCe-LDH-PtCl4 prepared in Example 2 of this invention XRD patterns; by Figure 1 The narrow and sharp peaks of the XRD diffraction pattern indicate good crystallinity, and the high correspondence between the peak positions and crystal planes confirm that CoFeCe-LDH-PtCl4 has good crystallinity. Successfully prepared.

[0148] 2) Figure 2 CoFeCe-LDH-PtCl4 prepared in Example 2 of this invention TEM images; by Figure 2 It can be seen that the ternary LDH formed by the introduction of rare earth elements has good overall dispersion and no serious aggregation phenomenon has occurred.

[0149] 3) Figure 3 CoFe-LDH-PtCl4 prepared for Comparative Example 3 of this invention TEM images; by Figure 3 It can be seen that, compared with the ternary LDH prepared in Example 2, its aggregation phenomenon is more serious and its overall dispersibility is poor.

[0150] 4) Figure 4 This is a SEM image of the high-efficiency flame-retardant ceramizable silicone rubber foam prepared in Example 2 of the present invention; (The image is from...) Figure 4It can be seen that the present invention has successfully prepared a porous silicone rubber foam material with relatively uniform filler dispersion and no obvious large agglomerates.

[0151] 5) The silicone rubber foams prepared in Comparative Examples 1-4 and Examples 1-7 were subjected to performance tests, including limiting oxygen index, total heat release, and ceramic compressive strength.

[0152] The limiting oxygen index was tested according to GB / T 10707-2008, the total heat release was tested according to ISO 5660-1, and the ceramic body was prepared by cutting silicone rubber foam into 40 mm pieces. 40 mm A 10 mm diameter piece was placed in a muffle furnace and heated from room temperature to 1000℃, holding for 30 min. The compressive strength of the ceramic body was determined according to GB / T 18942.2. In the 2003 test, the sample was compressed to 50% of its original height, and the maximum strength was recorded. The results are shown in Table 1.

[0153] Table 1. Performance data of different silicone rubber foams in Examples 1-7 and Comparative Examples 1-4.

[0154]

[0155] The results in Table 1 show that the pure silicone rubber foam in Comparative Example 1 has poor fire safety, a low limiting oxygen index, high total heat release, and low ceramic compressive strength after high-temperature calcination. The results from Examples 2, 4-7, and Comparative Example 2 show that the introduction of flame-retardant and refractory synergists can significantly improve the flame-retardant and ceramic properties of flame-retardant ceramicized silicone rubber foam. In Comparative Example 3, the introduction of flux, refractory filler, and carbonate-intercalated flame-retardant and refractory synergists can improve the limiting oxygen index and ceramic compressive strength of silicone rubber foam, and reduce the total heat release. When a special anionic intercalated layered ternary metal hydroxide containing transition metals is used as a flame-retardant and refractory synergist, the limiting oxygen index of the silicone rubber foam... The index and compressive strength of the ceramic body were further improved, and the total heat release was further reduced. This is mainly because the higher content of transition metals (including rare earth elements) can play a role in catalysis, char formation, and dilution of combustible gases, and together with flux and refractory filler, further improve the fire safety of silicone rubber foam. The comparison results of Example 2 and Comparative Example 3 show that ternary layered metal hydroxides have higher flame retardant ceramicization efficiency than binary layered metal hydroxides, and the silicone rubber foam prepared by them has better flame retardant performance and ceramic body strength. The special anions containing transition metals further improve the flame retardant ceramicization efficiency of flame retardant and refractory synergists compared with carbonate ions.

[0156] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flame retardant ceramifiable silicone rubber foam, characterized in that, The preparation raw materials include the following mass fractions: 100 parts of a silicone rubber foam foaming component, 20-40 parts of a fluxing agent, 20-50 parts of a refractory filler, and 0.5-5 parts of a flame-retardant refractory synergist; The chemical general formula of the flame-retardant fire-resistant synergist is [M 2+ 1-x-y M 3+ x M’ 3+ y (OH)2] (x+y)+ [A n- (x +y) / n ]·mH2O; Wherein, M 2+ and M 3+ The corresponding metal elements are two of iron, copper, titanium, cobalt, zinc, nickel, M' 3+ is one of cerium and lanthanum; The A n- contains a transition metal element, the transition metal element being one of platinum, titanium, molybdenum, iron, copper, nickel, cobalt; The flame-retardant fire-resistant synergist, wherein the molar ratio of M 2+ , M 3+ , and M' 3+ is 4:1:1 to 5:2:1; and the ratio of the total moles of M 2+ , M 3+ , and M' 3+ to the moles of A n- is 1:1 to 2:

1. The preparation method of the flame-retardant refractory synergist includes the following steps: The divalent metal salt corresponding to M is mixed with the trivalent metal salt and the sodium hydroxide solution and added dropwise to the solution containing A n- The flame-retardant and fire-resistant synergist is obtained by co-precipitation reaction at pH 8-11, aging in the anion salt solution.

2. The flame retardant ceramifiable silicone rubber foam according to claim 1, characterized in that, The concentration of the sodium hydroxide solution is 0.05-0.5 mol / L; the temperature of the coprecipitation reaction is room temperature, and the time is 2-6 h; and the aging time is 8-24 h.

3. The flame retardant ceramifiable silicone rubber foam of claim 1, wherein, The silicone rubber foam foaming component includes α, ω-dihydroxypolydimethylsiloxane, end-vinyl polydimethylsiloxane, low-molecular-weight hydroxyl silicone oil, hydrogen-containing silicone oil, a platinum catalyst, and 2, 4, 6, 8-tetramethyl-2, 4, 6, 8-tetravinylcyclotetrasiloxane.

4. The flame retardant ceramifiable silicone rubber foam of claim 1, wherein, The fluxing agent includes one or more of boron oxide, glass powder, zinc borate, and ammonium polyphosphate.

5. The flame retardant ceramicizable silicone rubber foam of claim 1, wherein, The refractory filler includes one or more of kaolin, montmorillonite, organically modified montmorillonite, mica powder, diatomite, calcium carbonate, talc powder, sepiolite, halloysite, vermiculite, and ceramic fiber.

6. The flame retardant ceramicizable silicone rubber foam of claim 1, wherein, The A n- one of chloroplatinate ions, chloroplatous ions, tetracyanoplatinate ions, tetranitroplatinate ions, tetrabromoplatinate ions, metatitanate ions, hydrogen metatitanate ions, heptatitaniumtrioxitrioxide ions.

7. A process for the preparation of the flame retardant ceramifiable silicone rubber foam according to any one of claims 1 to 6, characterized in that, The method includes the following steps: The silicone rubber foam foaming component, the fluxing agent, the refractory filler, and the flame-retardant refractory synergist are mixed in proportion, and the obtained foaming precursor is foamed and heat-treated to obtain the flame-retardant ceramifiable silicone rubber foam.

8. Application of the flame-retardant ceramifiable silicone rubber foam according to any one of claims 1-6 or prepared by the preparation method of claim 7 in the field of fire prevention.

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