Inherently flame retardant silicone elastomeric foam and method of making and use thereof

Abstract

The application provides an intrinsic flame-retardant organic silicon elastic foam and a preparation method and application thereof. The intrinsic flame-retardant elastic organic silicon elastic foam is prepared from components including an A component and a B component; the A component includes end-active polysiloxane A1, side-active polysiloxane A2 and a catalyst; and the B component includes hydrogen-containing polysiloxane. The preparation method includes: firstly, mixing the A component and the B component according to the respective component dosages; and then mixing the A component and the B component to prepare the intrinsic flame-retardant heat-insulating elastic organic silicon foam. The intrinsic flame-retardant organic silicon elastic foam has more aromatic rings and more silicon-oxygen-silicon structures, does not need to add a flame retardant, has good flame-retardant performance while retaining foam elasticity, has the advantages of rapidness, lightness, halogen-free, environmental protection, non-combustibility and the like, and has a wide application prospect in closed environments such as aviation, aerospace and high-speed train carriages.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicone materials, and further relates to an intrinsic flame-retardant silicone elastic foam as well as a preparation method and application thereof. BACKGROUND

[0002] Closed environments such as spacecraft, aircraft and high-speed train carriages require the use of materials with higher flame-retardant properties. For example, the flame-retardant requirement of seat elastic foam material should meet the requirement of TB / T3237, reaching non-flammable, difficultly flammable and extremely difficultly flammable levels, and high requirements are also proposed for smoke density, smoke toxicity and flame propagation. The commonly used flame-retardant polyurethane foam cannot meet the standard requirements, and cannot guarantee the safety of astronauts and other passengers. Therefore, it is necessary to develop a new type of silicone foam with difficultly flammable, low smoke and non-toxic properties, and the material can also be used in other fields or application scenarios such as new energy vehicles and power storage stations, building line pipe plugging, and has a wide application prospect.

[0003] Conventional silicone foams are prepared from hydrogen-containing polysiloxane, vinyl polysiloxane and hydroxyl-terminated polysiloxane with a Si-O-Si skeleton with high bonding energy. The hydrogen-containing polysiloxane containing Si-H and the vinyl group undergo a silicon-hydrogen addition reaction to produce cross-linking between chains, and the Si-OH of the hydroxyl-terminated polysiloxane and the Si-H undergo a dehydrogenation condensation reaction to produce hydrogen gas, realizing internal cross-linking foaming and preparing silicone foam. The foam itself has low density, high chemical resistance, a wide range of use temperature, flexibility and heat insulation, etc., making it widely used in building materials, transportation and electrical applications. However, the side chain organic groups of linear polydimethylsiloxane (PDMS) chain are easily ignited when exposed to high temperature environment or flame attack, which seriously limits its application.

[0004] At present, most of the flame-retardant modification methods of silicone foam are to add flame retardants for flame retardation, such as adding inorganic flame retardants (aluminum hydroxide, magnesium hydroxide, calcium carbonate, etc.), carbon-based flame retardants (graphite, graphene oxide, etc.). The addition of these flame retardants in large amounts greatly affects the foam structure, resulting in a decrease in the comprehensive performance. It is also an effective flame-retardant modification method to graft flame-retardant groups to silicone foam through chemical reaction, such as phenyl-containing silicone foam. However, this method has limited effect on one hand, and the preparation method is complex and the cost is high on the other hand.

[0005] Therefore, it is necessary to develop a flame-retardant silicone elastic foam, which has both elasticity and flame retardancy without the need for additional addition of flame retardants and fillers, so as to have a wide application prospect in the fields of aerospace, aviation and high-speed train seats, plugging, sealing and filling. SUMMARY

[0006] In order to solve the technical problems existing in the prior art, the present application provides an intrinsic flame-retardant organic silicone elastic foam and a preparation method and application thereof.

[0007] The side active group of the side active polysiloxane A2 reacts with the hydrogen-containing polysiloxane Si-H to generate gas, thereby becoming a gas source for foaming; the end active polysiloxane A1 reacts with the hydrogen-containing polysiloxane Si-H to form other forms of cross-linking bonds between the main chains, thereby making the cross-linking network flexible and retaining the elasticity of the foam.

[0008] The use of the side active polysiloxane A2 alone will result in excessively high cross-linking density, and the obtained foam is a hard foam without elasticity; the end active polysiloxane A1 is a long-chain end active polysiloxane, which can reduce the cross-linking density of the foam and make the foam have elasticity, and the side group aromatic ring of A1 can also improve the flame-retardant property of the foam. By controlling the ratio of the use amount of the end active polysiloxane A1 and the side active polysiloxane A2, cross-linking is realized while foaming, and more silicon-oxygen-silicon structures are generated in the structure, thereby retaining the elasticity of the foam and improving the flame-retardant property.

[0009] One of the purposes of the present application is to provide an intrinsic flame-retardant organic silicone elastic foam.

[0010] The intrinsic flame-retardant elastic organic silicone elastic foam is prepared from components including an A component and a B component;

[0011] The A component includes an end active polysiloxane A1, a side active polysiloxane A2 and a catalyst; and the B component includes a hydrogen-containing polysiloxane.

[0012] In a preferred embodiment of the present application,

[0013] The intrinsic flame-retardant organic silicone elastic foam includes, based on 100 parts by weight of the end active polysiloxane A1:

[0014]

[0015] In a preferred embodiment of the present application,

[0016] The structure of the end active polysiloxane A1 is:

[0017]

[0018] R1 is hydrogen, a hydroxyl group, an alkoxy group, an epoxy group, a vinyl group, an allyl group or a ketoxime group;

[0019] R2 is at least one of an ethyl group, an isopropyl group, a butyl group, an octyl group, a vinyl group and an allyl group; the repeated R2 can be the same or different;

[0020] R3 is at least one of phenyl, benzyl, naphthyl; repeated R3 can be the same or different;

[0021] 1≤x+y+z≤1000, preferably 100≤x+y+z≤1000;

[0022] x / (x+y+z)=0~1, preferably 0.5~1;

[0023] y / (x+y+z)=0~1;

[0024] z / (x+y+z)=0~1, preferably 0~0.5;

[0025] Further preferably,

[0026] The number average molecular weight of the terminal active polysiloxane A1 is 5000~100000g / mol, more preferably 10000~80000g / mol.

[0027] In a preferred embodiment of the present application,

[0028] The molar percentage content of R3 groups of the terminal active polysiloxane A1 in all side groups of the terminal active polysiloxane A1 is 0~50%, preferably 20~40%; R3 is aryl, which can improve the flame retardant performance of the foam.

[0029] In a preferred embodiment of the present application,

[0030] The structure of the side active polysiloxane A2 is:

[0031]

[0032] R4 is at least one of methyl, ethyl, isopropyl, butyl, octyl, phenyl;

[0033] R5 is at least one of methoxy, ethoxy, isopropoxy, butoxy, t-butoxy; repeated R5 can be the same or different;

[0034] 1≤m≤2000, preferably 50≤m≤500; 0≤n≤200, preferably 0≤n≤100;

[0035] Further preferably,

[0036] The content of R5 groups of the side active polysiloxane A2 is 0.1~1.1mol / 100g, preferably 0.5~1.1mol / 100g.

[0037] In a preferred embodiment of the present application,

[0038] The structure of the hydrogen-containing polysiloxane in the B component is:

[0039]

[0040] R6, R7 are independently selected from one of hydrogen, methyl, ethyl, isopropyl, butyl, phenyl, benzyl, naphthyl; and at least one of R6, R7 is hydrogen, i.e. the hydrogen-containing polysiloxane is end-group hydrogen-containing or side-group hydrogen-containing, or both end-group and side-group hydrogen-containing;

[0041] R8 is at least one of methyl, ethyl, isopropyl, butyl, phenyl, benzyl, naphthyl; the repeated R8 can be the same or different;

[0042] 10≤p≤1000, preferably 50≤p≤500;

[0043] 0≤q≤1000, preferably 0≤q≤200;

[0044] Further preferably,

[0045] The hydrogen content of the hydrogen-containing polysiloxane in the B component is 0.1-1.55 mol / 100g; the hydrogen content refers to the number of moles of active hydrogen in 100g of the hydrogen-containing polysiloxane.

[0046] In a preferred embodiment of the present application,

[0047] The catalyst is at least two of chloroplatinic acid, platinum-containing complex, organic acid, organic base, boron-containing compound, organotin, organoguanidine; preferably at least two of chloroplatinic acid, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, tetramethylguanidine, dibutyltin dilaurate, boron trifluoride, bis(pentafluorophenyl)borane, tris(pentafluorophenyl)borane, triethylborane, pentamethylcyclopentadienylsilicon cation (Me5CpSi + ).

[0048] In a preferred embodiment of the present application,

[0049] The active functional group molar amount of the hydrogen-containing polysiloxane in the B component is greater than the sum of the active functional group molar amount in A1 and the active functional group molar amount in A2 in the A component.

[0050] The second object of the present application is to provide a preparation method of an intrinsically flame-retardant silicone elastomer foam, characterized in that the method comprises:

[0051] The A component and the B component are mixed according to the respective component usage, and then the A component and the B component are mixed to prepare the intrinsically flame-retardant thermal-insulation elastomer silicone foam;

[0052] Preferably, the foaming temperature is 30-70 DEG C; and / or, the foaming time is 0.5-30 min, preferably 1-10 min.

[0053] The foaming can be carried out at room temperature, preferably between 30-70 DEG C, the higher the temperature, the faster the foaming speed, the foaming time can be adjusted by controlling the foaming temperature and the concentration of the catalyst according to the actual application.

[0054] The mixed material can be filled into the desired space and foamed at room temperature, or placed in a mold and foamed in a 30-70 DEG C oven.

[0055] The foaming is followed by curing, preferably at a temperature of 100-140 DEG C for 20-60 min.

[0056] The third object of the present application is to provide an intrinsic flame-retardant silicone elastomer foam for use in the fields of aviation, aerospace and electronics.

[0057] Compared with the prior art, the present application has the following beneficial effects:

[0058] The silicone foam of the prior art is prepared from hydrogen-containing polysiloxane, vinyl polysiloxane and hydroxyl-terminated polysiloxane having a Si-O-Si skeleton with high bonding energy, wherein the hydrogen-containing polysiloxane containing Si-H undergoes a silicon-hydrogen addition reaction with the vinyl group to produce cross-linking between chains, and the Si-OH of the hydroxyl-terminated polysiloxane undergoes a dehydrogenation condensation reaction with Si-H to produce hydrogen gas, realizing internal cross-linking foaming and preparing the silicone foam. The foam itself has low density, high chemical resistance, a wide use temperature range, flexibility and heat insulation, etc., making it widely used in building materials, transportation and electrical applications. However, the side chain organic groups of the linear polydimethylsiloxane (PDMS) chain are easily ignited when exposed to high temperature environments or flame attacks, which severely limits its application.

[0059] The intrinsic flame-retardant silicone elastomer foam of the present application has more aromatic rings and more siloxysilicon structures, does not need to add a flame retardant, has good flame-retardant properties while retaining the foam elasticity, and has the advantages of fast, light, halogen-free, environmentally friendly, non-combustible, etc. It has a broad application prospect in closed environments such as aviation, aerospace and high-speed train carriages.

[0060] The system of the present application is energy-saving and environmentally friendly, the raw materials are cheap and easy to obtain, does not need to add organic solvents, the preparation process is simple and convenient, and does not need complex equipment and harsh experimental conditions. DETAILED DESCRIPTION

[0061] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0062] All raw materials used in the examples are commercially available.

[0063] Sources of some of the main raw materials:

[0064] Vinyl-terminated silicone oil: Shandong Dayi Chemical Co., Ltd., DY-V401, number average molecular weight is approximately 50,000 g / mol;

[0065] Methylphenyl-terminated vinyl silicone oil with 40% phenyl content: Guangdong Houxin High-Tech Materials Co., Ltd., AM-3050;

[0066] Methyl hydrogen-containing silicone oil with a hydrogen content of 1.55 mol / 100g: Shin-Etsu Chemical Industry Co., Ltd., KF-99;

[0067] Phenyl hydrogen-containing silicone oil with a hydrogen content of 0.25 mol / 100g: Shenzhen Kejunchi Technology Co., Ltd., G616;

[0068] Hydroxyl-terminated methylphenyl silicone oil: Guangdong Wengjiang Chemical Reagent Co., Ltd., CAS: 63148-59-4;

[0069] Terminal epoxy methyl phenyl silicone oil: Anhui Aiyota Silicone Oil Co., Ltd., IOTA105;

[0070] Phenyl hydrogen-containing silicone oil with a hydrogen content of 0.1 mol / 100g: Shenzhen Kejunchi Technology Co., Ltd., HD60

[0071] Methylphenyl-terminated vinyl silicone oil with 30% phenyl content: Guangdong Houxin High-Tech Materials Co., Ltd., AM-3015;

[0072] Methyl hydrogen-containing silicone oil with a hydrogen content of 1.0 mol / 100g: Shin-Etsu Chemical Industry Co., Ltd., KF-99;

[0073] Methyl ethyl phenyl vinyl silicone oil: homemade;

[0074] Di(pentafluorophenyl)borane: Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 165612-94-2; Tri(pentafluorophenyl)borane: Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 1109-15-5;

[0075] Tetramethylammonium hydroxide: Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 75-59-2;

[0076] Triethylborane: Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 97-94-9;

[0077] Tetramethylguanidine: Shanghai Maclean Biochemical Technology Co., Ltd., CAS: 80-70-6.

[0078] The methyl methoxy silicone oil with a methoxy content of 1.07 mol / 100g, the methyl methoxy silicone oil with a methoxy content of 0.5 mol / 100g, the ethoxy silicone oil with a methoxy content of 0.5 mol / 100g, and the methyl methoxy silicone oil with a methoxy content of 1.1 mol / 100g were all prepared in-house. The preparation method was based on Chinese invention patent CN101153076A (invention title: "A polysiloxane resin with alkoxy side groups and its preparation method and uses").

[0079] The specific synthesis method of methyl methoxy silicone oil is as follows: Weigh 10g of methyl hydrogen silicone oil with a hydrogen content of 1.6% and 10g of anhydrous methanol into a three-necked flask. Stir at 50℃ for 30min, and slowly add 0.1g of 10% tetramethylammonium hydroxide methanol solution. After reacting for 6h, add 0.1g of NKC-9 acidic ion exchange resin (washed three times with methanol) to the three-necked flask. Pour the reaction solution into a pear-shaped flask and rotary evaporate at 55℃ for 30min to obtain methyl methoxy silicone oil. Different methoxyl content can be achieved by changing the hydrogen content of the raw material methyl hydrogen silicone oil.

[0080] The synthesis method for methylethoxy silicone oil is the same as that for methylmethoxy silicone oil, except that anhydrous methanol is replaced with anhydrous ethanol. Different ethoxy content can be achieved by changing the hydrogen content of the raw material, methyl hydrogen silicone oil.

[0081] Methyl ethyl phenyl vinyl silicone oil: homemade;

[0082] The specific synthesis steps of methyl ethyl phenyl vinyl silicone oil are as follows: Octamethylcyclotetrasiloxane, octaethylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane are added to a three-necked flask in a molar ratio of 8:2:1. The mixture is heated to 60°C under a vacuum of -0.09 MPa for 1 hour to remove water. Then, 0.5 wt% tetramethylammonium hydroxide is added, and the temperature is raised to 110°C. After observing an increase in the viscosity of the system, tetramethyldivinylsiloxane (molar ratio with octaphenylcyclotetrasiloxane is 0.1:1) is added. The mixture is reacted at 110°C for 8 hours, and then the temperature is raised to 150°C and held for 30 minutes to remove the catalyst, yielding the product, end-vinyl methyl ethyl phenyl polysiloxane.

[0083] Test method:

[0084] Density: The test standard is GB / T6343-2009.

[0085] Porosity: The calculation method is as follows: Where Ψ is porosity, ρ f ρ is the apparent density of the foam. s This is the density of the solid rubber compound.

[0086] LOI (%): The test standard is GB / T2406.2-2009.

[0087] UL-94: The testing standard is GB / T 8333-2022.

[0088] Thermal conductivity: The thermal conductivity of silicone foam was tested using a thermal conductivity meter. The sample size was 3mm × 4.5mm, the thickness was unlimited, and the surface in contact with the test electrode was flat.

[0089] Compressive strength: The test standard is GB / T 18942.2-2003.

[0090] All quantities mentioned in the examples are by weight.

[0091] Example 1

[0092] An intrinsically flame-retardant silicone foam comprises component A and component B, wherein component A mainly comprises the following components in parts by weight:

[0093] The composition consists of: 100 parts vinyl-terminated silicone oil (number average molecular weight approximately 50,000 g / mol, R3 group content 0%), 1.5 parts methyl methoxy silicone oil with a methoxy content of 1.07 mol / 100 g (degree of polymerization approximately 100), 0.2 parts chloroplatinic acid, and 0.05 parts tris(pentafluorophenyl)borane; Component B mainly consists of the following components in parts by weight: 25 parts methyl hydrogen silicone oil with a hydrogen content of 1.55 mol / 100 g (degree of polymerization approximately 50).

[0094] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0095] (1) Preparation of component A: Weigh out the terminal vinyl silicone oil, methyl methoxy silicone oil, chloroplatinic acid and tris(pentafluorophenyl)borane according to the formula, and mix them thoroughly.

[0096] (2) Preparation of component B: Weigh out methyl hydrogen silicone oil according to the formula.

[0097] (3) Mix component A and component B evenly and place them in a mold. Foam at 60°C for 1 minute and then cure at 120°C for 30 minutes. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0098] Example 2

[0099] An intrinsically flame-retardant silicone foam comprises component A and component B. Component A mainly consists of the following components in parts by weight: 100 parts of methylphenyl-terminated vinyl silicone oil with a phenyl content of 40% of all side groups (number average molecular weight approximately 30,000 g / mol), 10 parts of methyl methoxy silicone oil with a methoxy content of 0.5 mol / 100 g (degree of polymerization approximately 500), 0.6 parts of platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane complex, and 0.05 parts of di(pentafluorophenyl)borane. Component B mainly consists of the following components in parts by weight: 25 parts of phenyl hydrogen-containing silicone oil with a hydrogen content of 0.25 mol / 100 g (p approximately 50, q approximately 10).

[0100] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0101] (1) Preparation of component A: Weigh out methylphenyl-terminated vinyl silicone oil, methyl methoxy silicone oil, caster catalyst and di(pentafluorophenyl)borane according to the formula, and mix them thoroughly.

[0102] (2) Preparation of component B: Weigh out methyl hydrogen silicone oil according to the formula.

[0103] (3) Mix component A and component B evenly and place them in a mold. Foam at 60°C for 1 minute and then cure at 120°C for 30 minutes. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0104] Example 3

[0105] An intrinsically flame-retardant silicone foam comprises component A and component B. Component A mainly comprises the following components in parts by weight: 100 parts of terminal hydroxyl methylphenyl silicone oil (number average molecular weight approximately 50,000 g / mol) with a phenyl content of 30% of all side groups, 0.5 parts of methyl methoxy silicone oil (same as Example 1) with a methoxy content of 1.07 mol / 100g, 0.5 parts of tetramethylammonium hydroxide, and 0.5 parts of triethylborane. Component B mainly comprises the following components in parts by weight: 50 parts of methyl hydrogen silicone oil (same as Example 1) with a hydrogen content of 1.55 mol / 100g.

[0106] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0107] (1) Preparation of component A: Weigh out terminal hydroxyl methyl phenyl silicone oil, methyl methoxy silicone oil, tetramethyl ammonium hydroxide and triethyl borane according to the formula, and mix them thoroughly.

[0108] (2) Preparation of component B: Weigh out methyl hydrogen silicone oil according to the formula.

[0109] (3) Mix component A and component B evenly and place them in a mold. Foam at 60°C for 1 minute and then cure at 120°C for 30 minutes. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0110] Example 4

[0111] An intrinsically flame-retardant silicone foam comprises component A and component B. Component A mainly consists of the following components in parts by weight: 100 parts of terminal epoxy methyl phenyl silicone oil (the structure differs from the terminal vinyl methyl phenyl silicone oil of Example 1 in that the terminal group is epoxy group, and the number average molecular weight is approximately 70,000 g / mol), 10 parts of ethoxy silicone oil with an ethoxy content of 0.5 mol / 100 g (m is approximately 250, n is approximately 300), 0.5 parts of tetramethylguanidine catalyst, and 0.05 parts of boron trifluoride. Component B mainly consists of the following components in parts by weight: 50 parts of phenyl hydrogen-containing silicone oil with a hydrogen content of 0.1 mol / 100 g (the structural formula is the same as in Example 2, p is approximately 200, q is approximately 50).

[0112] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0113] (1) Preparation of component A: Weigh out terminal epoxy methyl phenyl silicone oil, ethoxy silicone oil, tetramethyl guanidine catalyst and boron trifluoride according to the formula, and mix them thoroughly.

[0114] (2) Preparation of component B: Weigh out phenyl hydrogen silicone oil according to the formula.

[0115] (3) Mix component A and component B evenly and place them in a mold. Foam at 60°C for 1 minute and then cure at 120°C for 30 minutes. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0116] Example 5

[0117] An intrinsically flame-retardant silicone foam comprises component A and component B. Component A mainly comprises the following components in parts by weight: 100 parts of methylphenyl-terminated vinyl silicone oil (structural formula same as in Example 2, number average molecular weight approximately 40,000 g / mol) with a phenyl molar percentage of 30% of all side groups; 0.5 parts of methyl methoxy silicone oil (structural formula same as in Example 1, m approximately 200, n 0) with a methoxy content of 1.1 mol / 100g; 0.5 parts of dibutyltin dilaurate; and 0.5 parts of triethylborane. Component B mainly comprises the following components in parts by weight: 50 parts of methyl hydrogen silicone oil (structural formula same as in Example 1, p approximately 500, q approximately 200) with a hydrogen content of 1.0 mol / 100g.

[0118] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0119] (1) Preparation of component A: Weigh out methyl phenyl-terminated vinyl silicone oil, methyl methoxy silicone oil, dibutyltin dilaurate, and triethylborane according to the formula, and mix them thoroughly.

[0120] (2) Preparation of component B: Weigh out methyl hydrogen silicone oil according to the formula.

[0121] (3) Mix component A and component B evenly and place them in a mold. Foam at 60°C for 1 minute and then cure at 120°C for 30 minutes. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0122] Example 6

[0123] An intrinsically flame-retardant silicone foam comprises component A and component B. Component A mainly comprises the following components in parts by weight: 30% phenyl content of all side groups, 100 parts of methyl ethyl phenyl vinyl silicone oil with a number average molecular weight of approximately 30,000 g / mol (x approximately 200, y approximately 50, z approximately 30), 0.5 parts of methyl methoxy silicone oil with a methoxy content of 1.07 mol / 100 g (same as Example 1), 0.3 parts of platinum (O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane complex, and 0.3 parts of boron trifluoride. Component B mainly comprises the following components in parts by weight: 50 parts of methyl hydrogen silicone oil with a hydrogen content of 1.55 mol / 100 g (same as Example 1).

[0124] The preparation method of the intrinsically flame-retardant elastic silicone foam includes the following steps:

[0125] (1) Preparation of component A: Weigh out methyl phenyl-terminated vinyl silicone oil, methyl methoxy silicone oil, platinum (0)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane complex and boron trifluoride according to the formula, and mix them thoroughly.

[0126] (2) Preparation of component B: Weigh out methyl hydrogen silicone oil according to the formula.

[0127] (3) Mix component A and component B evenly and place them in a mold. Foam at 30°C for 10 min and then cure at 120°C for 30 min. The intrinsic flame-retardant elastic silicone foam can be obtained. The performance test results are shown in Table 1.

[0128] Comparative Example 1

[0129] References: Zhang Xianzheng. Preparation and performance study of flame-retardant organosilicon foam materials [D]. Hunan University of Technology, 2021.

[0130] 100 parts of α,ω-dihydroxypolysiloxane (number average molecular weight approximately 50,000 g / mol), 20 parts of vinyl-terminated silicone oil (number average molecular weight approximately 50,000 g / mol), and 0.3 parts of platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane complex were thoroughly mixed in a high-power electric mixer for 15 min. 20 parts of methyl hydrogen-containing silicone oil with a hydrogen content of 1.55% were added to the mixed base adhesive, and the mixture was quickly stirred in a high-power electric mixer for 2 min. The mixture was then poured into a mold. After reacting at 30℃ for 15 min, the mold was placed in a 120℃ vacuum drying oven for 3 h for a two-stage treatment. After the reaction, the silicone foam material was obtained, and the performance test results are shown in Table 1.

[0131] Table 1. Performance test results of the foam materials prepared in Examples 1-6 and Comparative Example 1.

[0132]

[0133] The silicone foam of Comparative Example 1 was prepared from hydrogen-containing polysiloxane, vinyl polysiloxane, and hydroxyl-terminated polysiloxane with a Si-O-Si backbone having high binding energy. The hydrogen-containing polysiloxane containing Si-H undergoes a hydrosilylation reaction with vinyl polysiloxane to produce crosslinks between chains. At the same time, the Si-OH of the hydroxyl-terminated polysiloxane undergoes a dehydrogenation condensation reaction with Si-H to produce hydrogen gas, thus achieving internal crosslinking foaming and preparing silicone foam.

[0134] As shown in Table 1, compared with Examples 1-6, Comparative Example 1 has a lower LOI, a lower vertical flammability rating, and a higher thermal conductivity. This is because the side-chain organic groups of the linear polydimethylsiloxane (PDMS) chain of the foam are easily ignited when exposed to high temperatures or flame attacks, which severely limits its application.

[0135] The intrinsically flame-retardant silicone elastic foams prepared in Examples 1-6 utilize the reaction between the side-active groups of the side-active polysiloxane and the hydrogen-containing polysiloxane Si-H to generate gas, which serves as the gas source for foaming. The end-active polysiloxane reacts with the hydrogen-containing polysiloxane Si-H to form other forms of cross-linking bonds between the main chains, thereby making the cross-linking network flexible and retaining the elasticity of the foam. This intrinsically flame-retardant silicone elastic foam has more aromatic rings and more siloxane-silicon structures, and does not require the addition of flame retardants. While retaining the elasticity of the foam, it has good flame-retardant properties and has the advantages of being fast, lightweight, halogen-free, environmentally friendly, and non-flammable. It has broad application prospects in enclosed environments such as aviation, aerospace, and high-speed rail carriages.

Claims

1. An intrinsically flame-retardant organosilicon elastic foam, characterized in that: The intrinsic flame-retardant elastic silicone foam is prepared from components including component A and component B; Component A includes terminal active polysiloxane A1, side active polysiloxane A2, and a catalyst; Component B includes hydrogen-containing polysiloxane; Based on 100 parts by weight of end-active polysiloxane A1, the intrinsically flame-retardant silicone elastic foam comprises: The structure of the terminal active polysiloxane A1 is as follows: R1 is hydrogen, hydroxyl, alkoxy, epoxy, vinyl, allyl, or ketoxime; R2 is at least one of ethyl, isopropyl, butyl, octyl, vinyl, and allyl; repeated R2s may be the same or different; R3 is at least one of phenyl, benzyl, and naphthyl; repeated R3s may be the same or different; 1≤x+y+z≤1000; x / (x+y+z)=0~1; y / (x+y+z)=0~1; z / (x+y+z)=0~1; x, y, and z cannot all be 0 at the same time; The structure of the side-active polysiloxane A2 is as follows: R4 is at least one of methyl, ethyl, isopropyl, butyl, octyl, and phenyl. R5 is at least one of methoxy, ethoxy, isopropoxy, butoxy, and tert-butoxy; repeated R5s may be the same or different; 1≤m≤2000; 0≤n≤200.

2. The intrinsically flame-retardant organosilicon elastic foam as described in claim 1, characterized in that: Based on 100 parts by weight of end-active polysiloxane A1, the intrinsically flame-retardant silicone elastic foam comprises:

3. The intrinsically flame-retardant organosilicon elastic foam as described in claim 1, characterized in that: 100≤x+y+z≤1000; x / (x+y+z) is between 0.5 and 1; z / (x+y+z) is between 0 and 0.5; x is not 0 or both x and z are not 0.

4. The intrinsically flame-retardant silicone elastic foam as described in claim 3, characterized in that: The number-average molecular weight of the terminally active polysiloxane A1 is 5000–100000 g / mol.

5. The intrinsically flame-retardant silicone elastic foam as described in claim 4, characterized in that: The terminally active polysiloxane A1 has a number-average molecular weight of 10,000–80,000 g / mol.

6. The intrinsically flame-retardant silicone elastic foam as described in claim 1, characterized in that: The R3 group of the terminal active polysiloxane A1 accounts for 0 to 50% of the total molar percentage of all side groups of the terminal active polysiloxane A1.

7. The intrinsically flame-retardant organosilicon elastic foam as described in claim 6, characterized in that: The R3 group of the terminal active polysiloxane A1 accounts for 20-40% of the total molar percentage of all side groups of the terminal active polysiloxane A1.

8. The intrinsically flame-retardant silicone elastic foam as described in claim 1, characterized in that: 50≤m≤500; 0≤n≤100.

9. The intrinsically flame-retardant organosilicon elastic foam as described in claim 1, characterized in that: The R5 group content of the side-active polysiloxane A2 is 0.1–1.1 mol / 100g.

10. The intrinsically flame-retardant organosilicon elastic foam as described in claim 9, characterized in that: The R5 group content of the side-active polysiloxane A2 is 0.5–1.1 mol / 100g.

11. The intrinsically flame-retardant organosilicon elastic foam as described in claim 1, characterized in that: The structure of the hydrogen-containing polysiloxane in component B is as follows: R6 and R7 are each independently selected from one or more of hydrogen, methyl, ethyl, isopropyl, butyl, phenyl, benzyl, and naphthyl; and at least one of R6 and R7 is hydrogen. R8 is at least one of methyl, ethyl, isopropyl, butyl, phenyl, benzyl, and naphthyl; repeated R8s may be the same or different; 10≤p≤1000； 0≤q≤1000。 12. The intrinsically flame-retardant organosilicon elastic foam as described in claim 11, characterized in that: 50≤p≤500； 0≤q≤200。 13. The intrinsically flame-retardant organosilicon elastic foam as described in claim 12, characterized in that: The hydrogen content of the hydrogen-containing polysiloxane in component B is 0.1–1.55 mol / 100g.

14. The intrinsically flame-retardant organosilicon elastic foam as described in claim 1, characterized in that: The catalyst is at least two of the following: chloroplatinic acid, platinum-containing complex, organic acid, organic base, boron-containing compound, organotin, and organoguanidine.

15. The intrinsically flame-retardant silicone elastic foam as described in claim 14, characterized in that: The catalyst is at least two of the following: chloroplatinic acid, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane complex, tetramethylguanidine, dibutyltin dilaurate, boron trifluoride, di(pentafluorophenyl)borane, tri(pentafluorophenyl)borane, triethylborane, and pentamethylcyclopentadienylsilane cation.

16. The intrinsically flame-retardant organosilicon elastic foam according to claim 1, characterized in that: The molar amount of hydrogen-containing polysiloxane active functional groups in component B is greater than the sum of the molar amounts of active functional groups in A1 and A2 in component A.

17. A method for preparing an intrinsically flame-retardant organosilicon elastic foam as described in any one of claims 1 to 16, characterized in that... The method includes: First, mix components A and B according to their respective amounts. Then, mix components A and B together to obtain the intrinsic flame-retardant and heat-insulating elastic silicone foam.

18. A method for preparing an intrinsically flame-retardant organosilicon elastic foam as described in claim 17, characterized in that: The foaming temperature is 30–70℃; and / or the foaming time is 0.5–30 min.

19. A method for preparing an intrinsically flame-retardant organosilicon elastic foam as described in claim 18, characterized in that: The foaming time is 1 to 10 minutes.

20. The application of an intrinsically flame-retardant silicone elastic foam as described in any one of claims 1 to 16, or an intrinsically flame-retardant silicone elastic foam obtained by the preparation method as described in any one of claims 17 to 19, in the fields of aviation, aerospace, and electronics.

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