Sealant as well as preparation method and application thereof

Abstract

The invention discloses a sealant as well as a preparation method and application thereof. The sealant is prepared from the following components: alpha, omega-dihydroxy polydimethylsiloxane, a structure regulator, filler, modified LDH (layered double hydroxides), a phosphorus flame retardant, a cross-linking agent, a silane coupling agent and a catalyst, the modified LDH comprises alkylated LDH and / or alkylated LDH coated Fe3O4. The sealant disclosed by the invention has flame-retardant and smoke-suppressing effects, the flame-retardant grade can reach V0, and the fire-resistant integrity can reach 5h.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a sealant and a preparation method and application thereof. Background Art

[0002] Silicone sealants can be cured at room temperature, have adhesion to a variety of substrates, and have excellent weather resistance, electrical insulation, and chemical stability. Therefore, they are widely used in many fields such as construction, transportation, medical care, and energy. With the development of science and technology and the improvement of people's requirements for material performance, the research and development trend of silicone sealants will pay more attention to the development of high performance and multi-functions, such as developing products with higher strength, better weather resistance, and better flame retardancy. However, silicone sealants themselves will burn when exposed to open flames. When a fire occurs, the high temperature and toxic smoke generated may pose a great threat to personal safety. Therefore, improving the smoke suppression and flame retardant properties of silicone sealants has become an important development direction.

[0003] At present, fireproof sealants often meet flame retardant standards by adding flame retardants. Flame retardants are compounds that play a role in multiple key links in the combustion process. Specifically, before combustion occurs, flame retardants can absorb a large amount of heat and effectively reduce the temperature of the material surface, thereby delaying the start of the combustion process. When combustion begins, flame retardants will capture free radicals in the combustion reaction and effectively inhibit the spread of flames. At the same time, flame retardants will decompose non-combustible gases after being heated. These substances can reduce the concentration of combustible gases and further slow down the combustion rate. In addition, flame retardants can also form a covering layer after being burned. This covering layer not only insulates heat and oxygen, but also effectively prevents gas spillage. Flame retardants effectively inhibit the combustion process through the above multiple action mechanisms. However, flame retardants often have poor compatibility with polymers. Under the premise of large-scale addition, they are very easy to agglomerate and have poor dispersibility, resulting in poor mechanical properties of the glue, and most flame retardant systems have no obvious inhibitory effect on combustion smoke. For example, the related technology uses silane coupling agent to modify brucite and mica, and mixes them with phosphorus flame retardants to prepare fireproof sealants, but the structure of nano inorganic flame retardants is not adjusted, and the smoke suppression performance is not improved. There are also related technologies that add imidazole ionic liquids, polymethyl branched trimethoxy-terminated polydimethylsiloxane and paraffin oil to the colloid, which promotes the compatibility of flame retardants with the system and improves the mechanical properties of sealants, but there is no improvement in the smoke suppression performance of the glue and the support layer after combustion. Summary of the invention

[0004] The present invention aims to solve at least one of the above technical problems existing in the prior art. To this end, the present invention aims to provide a sealant and a preparation method and application thereof, wherein the sealant has flame retardant and smoke suppression effects.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a sealant, comprising the following components: α,ω-dihydroxy polydimethylsiloxane, a structure regulator, a filler, a modified LDH, a phosphorus-based flame retardant, a crosslinking agent, a silane coupling agent, and a catalyst;

[0007] The modified LDH includes alkylated LDH and / or alkylated LDH@Fe3O4.

[0008] In the present invention, when the layered double hydroxide (LDH, i.e., hydrotalcite) is heated, the crystalline water between its layers will decompose and absorb a large amount of heat, and the released H2O and CO2 can effectively dilute and block the combustible gas. However, the layered structure of LDH is easy to agglomerate, thus affecting the colloidal properties. In the present invention, when the modified LDH is an alkylated LDH@Fe3O4, LDH is in situ grown on the nanoscale Fe3O4 surface. This growth mode forms a complex flower-like cluster structure, which effectively prevents the agglomeration of the layered hydrotalcite; the core-shell particles are then surface treated with a silane coupling agent to increase the compatibility with the system. In addition, when combustion occurs, the tortuous pathways in the core-shell particle structure can hinder the flow of smoke during combustion. The alkylated LDH@Fe3O4 cooperates with the phosphorus-based flame retardant, and the Al in the hydrotalcite layer 3+ and Mg 2+ Ions can promote the formation of carbon layer, metal oxide layer and aluminum phosphate layer in the system. On the one hand, this helps to maintain the strength of the colloid after combustion. On the other hand, the loose, porous and large-specific-surface-area alkaline solid layer formed can absorb a large amount of harmful gases, especially acidic gases, thereby effectively inhibiting the release of smoke. When the modified LDH is an alkylated LDH, it can produce a significant synergistic flame retardant and smoke suppression effect in combination with a piperazine-modified phosphorus flame retardant.

[0009] In some embodiments of the present invention, the sealant includes the following components, by weight: 100 parts of α,ω-dihydroxy polydimethylsiloxane, 5 to 30 parts of structural regulator, 70 to 120 parts of filler, 15 to 50 parts of modified LDH, 15 to 50 parts of phosphorus flame retardant, 10 to 20 parts of crosslinking agent, 1.5 to 5 parts of silane coupling agent, 0.1 to 0.5 parts of catalyst

[0010] In some embodiments of the present invention, the sealant includes the following components, measured in parts by weight: 100 parts of α, ω-dihydroxypolydimethylsiloxane, 10 to 20 parts of a structural regulator, 80 to 120 parts of a filler, 30 to 50 parts of a modified LDH, 30 to 50 parts of a phosphorus-based flame retardant, 10 to 20 parts of a cross-linking agent, 2 to 5 parts of a silane coupling agent, and 0.1 to 0.5 parts of a catalyst.

[0011] In some embodiments of the present invention, the viscosity of the α,ω-dihydroxypolydimethylsiloxane is 20,000 to 50,000 cps, such as 25,000 cps, 30,000 cps, 35,000 cps, 40,000 cps, or 45,000 cps.

[0012] The viscosity of the present invention is measured at 25°C.

[0013] In some embodiments of the present invention, the structure regulator includes hydroxy silicone oil, and the viscosity of the hydroxy silicone oil is 100 to 1000 cps.

[0014] In some embodiments of the present invention, the filler includes at least one of calcium carbonate and silicon dioxide; such as nano calcium carbonate, hydrophobic silicon dioxide or a mixture of the two, with a mixing ratio of 12 to 50:1.

[0015] In some embodiments of the present invention, the method for preparing the alkylated LDH comprises the following steps: subjecting the modified coupling agent to an alkylation reaction with LDH to obtain the alkylated LDH.

[0016] In some embodiments of the present invention, the LDH@Fe3O4 can be obtained commercially, or can be prepared according to the preparation method disclosed in the prior art; or can be obtained according to the following method. The alkylated LDH@Fe3O4 preparation method comprises the following steps: reacting the Fe3O4 dispersion with a magnesium salt-aluminum salt mixed solution to obtain LDH@Fe3O4, and then alkylating with a modified coupling agent to obtain the alkylated LDH@Fe3O4. The alkylation reaction comprises adding the modified coupling agent to the stirred LDH@Fe3O4, dispersing at 50-80°C for 20-60 minutes, and the dispersion rate is 200-500rpm; the solvent of the alkylation reaction comprises at least one of ethanol and ethanol aqueous solution.

[0017] In some embodiments of the present invention, the mass ratio of the modified coupling agent to LDH@Fe3O4 is 1:100 to 1:120.

[0018] In some embodiments of the present invention, the modified coupling agent includes at least one of KH550, KH560, KH570, and KH590.

[0019] In some embodiments of the present invention, the Fe3O4 dispersion contains Fe 3+ The concentration is 3~6mM.

[0020] In some embodiments of the present invention, Al in the magnesium salt-aluminum salt mixed solution 3+ The concentration is 0.2~0.4M, Mg 2+The concentration is 0.1~0.3M.

[0021] In some embodiments of the present invention, the volume ratio of the magnesium salt-aluminum salt mixed solution to the Fe3O4 dispersion is 1:4 to 1:6.

[0022] In some embodiments of the present invention, the magnesium salt includes at least one of magnesium nitrate, magnesium chloride, and magnesium sulfate.

[0023] In some embodiments of the present invention, the aluminum salt includes at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0024] In some embodiments of the present invention, a nano-Fe3O4 dispersion is reacted with a magnesium salt-aluminum salt mixed solution at 30-60°C to obtain LDH@Fe3O4; the reaction is carried out at a pH of 10-11; a mixed alkali can be used to maintain the pH of the reaction system, such as dissolving NaOH and Na2CO3 together in a methanol aqueous solution, wherein OH - The concentration is 0.2~0.3M, CO3 2- The concentration is 0.6-0.9M; the reaction time is 24-48h, such as 24-36h.

[0025] In some embodiments of the present invention, the phosphorus-based flame retardant includes at least one of ammonium phosphate, ammonium polyphosphate, ammonium pyrophosphate, melamine, melamine borate, melamine phosphate, melamine polyphosphate, melamine cyanurate, and dimelamine pyrophosphate.

[0026] In some embodiments of the present invention, the phosphorus-based flame retardant includes a phosphorus-based flame retardant modified with piperazine, such as piperazine-modified ammonium polyphosphate. The modified phosphorus-based flame retardant is a comprehensive flame retardant system comprising a gas source, an acid source and a carbon source. When used together with alkylated LDH or alkylated LDH@Fe3O4, it will produce a significant synergistic flame retardant and smoke suppression effect.

[0027] In some embodiments of the present invention, the preparation method of the piperazine-modified ammonium polyphosphate comprises the following steps: adding ammonium polyphosphate to a piperazine solution, heating the reaction, and obtaining the piperazine-modified ammonium polyphosphate; the reaction is carried out at 70 to 110°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the piperazine solution is a piperazine ethanol solution; and its concentration is 0.5 to 0.7 mol / L.

[0028] In some embodiments of the present invention, the crosslinking agent includes at least one of methyl tributylacetoximosilane, vinyl tributylacetoximosilane, propyl tributylacetoximosilane, phenyl tributylacetoximosilane and tetrabutyl tributylacetoximosilane.

[0029] In some embodiments of the present invention, the silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0030] In some embodiments of the present invention, the catalyst includes at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, and dibutyltin acetylacetonate.

[0031] The second aspect of the present invention provides a method for preparing the sealant, comprising the following steps: mixing and reacting the components to obtain the sealant.

[0032] In some embodiments of the present invention, the preparation method of the sealant includes the following steps: mixing α, ω-dihydroxy polydimethylsiloxane, a structure regulator, a filler, an alkylated LDH@Fe3O4, and a phosphorus-based flame retardant for 150 to 200 minutes, at a temperature of 110 to 130°C and a vacuum degree of -0.09 to 0.1 MPa, and cooling to room temperature to obtain a base material; adding a cross-linking agent to the base material, stirring, and then adding a silane coupling agent and a catalyst to obtain the sealant after reaction; the reaction is carried out at a vacuum degree of -0.08 to -0.09 MPa.

[0033] The third aspect of the present invention provides the use of the sealant in building sealing.

[0034] The beneficial effects of the present invention are:

[0035] The sealant of the present invention has flame retardant and smoke suppression effects, the flame retardant grade can reach V0, and the fire resistance integrity can reach 5h. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a transmission electron microscope image of LDH@Fe3O4 of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0038] In the following examples, unless otherwise specified, the material information is as follows:

[0039] α,ω-dihydroxy polydimethylsiloxane has a viscosity of 45000cps;

[0040] The viscosity of hydroxy silicone oil is 350cps;

[0041] The filler is a mixture of hydrophobic silicon dioxide and nano calcium carbonate in a mass ratio of 1:30;

[0042] The crosslinking agent is a mixture of methyl tributylacetoximate silane and vinyl tributylacetoximate silane in a mass ratio of 1:1;

[0043] The catalyst is dibutyltin dilaurate;

[0044] The mixed alkaline solution is a methanol and water solution of NaOH and Na2CO3, in which the volume ratio of methanol to water is 1:1, OH - The concentration is 0.3M, CO3 2- The concentration is 0.9M;

[0045] The magnesium salt-aluminum salt mixed solution is aluminum nitrate nonahydrate and magnesium nitrate hexahydrate dissolved in methanol aqueous solution, in which Al 3+ The concentration is 0.2M, Mg 2+ The concentration was 0.1 M, and the volume ratio of methanol to water was 1:1.

[0046] The preparation method of alkylated LDH@Fe3O4 is as follows:

[0047] S1: Sodium acetate trihydrate and ferric chloride hexahydrate are dissolved in ethylene glycol solution to obtain a mixed ethylene glycol solution, wherein Na + The concentration is 20mM, Fe 3+ The concentration is 5mM. Put the mixed ethylene glycol solution into a polytetrafluoroethylene hydrothermal reactor, seal it and react it at 200℃ for 8 hours, separate the solid and liquid after cooling, wash, dry and grind to obtain black or brown powder, which is nano-Fe3O4;

[0048] S2: Fe3O4 was placed in a methanol aqueous solution (methanol to water volume ratio of 1:1), with a solid mass percentage of 0.3%, and ultrasonically dispersed for 30 minutes to obtain a Fe3O4 dispersion. Then, at 40°C, a mixed alkali solution was added dropwise to the Fe3O4 dispersion until the pH of the dispersion was between 10 and 11, and then a mixed alkali solution and a magnesium salt-aluminum salt mixed solution with a volume ratio of 2:1 were added dropwise together, and the volume ratio of the magnesium salt-aluminum salt mixed solution to the Fe3O4 dispersion was controlled to be 1:4, and the addition time was 30 to 60 minutes. During this period, the pH of the solution system was maintained unchanged, and the reaction was carried out for 24 hours after the addition was completed. After the reaction is completed, the solid and liquid are separated, and LDH@Fe3O4 is obtained after washing, drying and grinding. According to the mass ratio of the modified coupling agent to LDH@Fe3O4 being 1:100, an ethanol solution of the modified coupling agent KH570 with a mass fraction of 30% and a pH of 10 is evenly sprayed into the high-speed stirred LDH@Fe3O4 for multiple times, and dispersed at high speed at 60°C for 30 minutes, and then centrifuged for solid-liquid separation, washed with ethanol, dried, and ground to obtain alkylated LDH@Fe3O4.

[0049] The transmission electron microscopy image of the prepared LDH@Fe3O4 is shown in Figure 1 shown.

[0050] Example 1

[0051] This embodiment prepares a sealant, and the specific process is as follows:

[0052] The composition of the sealant of this embodiment is shown in Table 1, wherein the phosphorus-based flame retardant is ammonium polyphosphate modified with a 0.7 mol / L piperazine ethanol aqueous solution (ethanol to water volume ratio is 20:1); the silane coupling agent is γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a weight ratio of 1:1.

[0053] The preparation method of the sealant is as follows:

[0054] (1) putting the α,ω-dihydroxy polydimethylsiloxane, structure regulator, filler, modified LDH@Fe3O4 and phosphorus flame retardant into a planetary mixer and dispersing and mixing for 180 minutes at a temperature of 130° C. and a vacuum degree of -0.09 to 0.1 MPa, and cooling to room temperature to obtain a base material mortar;

[0055] (2) adding a crosslinking agent to the base material and stirring for 20 minutes, then adding a silane coupling agent and a catalyst and stirring for 15 minutes, with a vacuum degree of -0.08 to -0.09 MPa during stirring, and discharging the material to obtain the fireproof sealant.

[0056] Example 2

[0057] This embodiment prepares a sealant, and the specific process is as follows:

[0058] The composition of the sealant of this embodiment is shown in Table 1; wherein the silane coupling agent is γ-aminopropyltrimethoxysilane;

[0059] The preparation method of the sealant is as described in Example 1.

[0060] Example 3

[0061] This embodiment prepares a sealant, and the specific process is as follows:

[0062] The composition of the sealant of this embodiment is shown in Table 1; wherein the silane coupling agent is γ-aminopropyltriethoxysilane;

[0063] The preparation method of the sealant is as described in Example 1.

[0064] Example 4

[0065] This embodiment prepares a sealant, and the specific process is as follows:

[0066] The composition of the sealant of this embodiment is shown in Table 1, wherein the phosphorus-based flame retardant is ammonium polyphosphate; and the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0067] The preparation method of the sealant is as described in Example 1.

[0068] Example 5

[0069] This embodiment prepares a sealant, and the specific process is as follows:

[0070] The composition of the sealant of this embodiment is shown in Table 1, wherein the preparation method of the modified LDH is as follows: 1.8 g of magnesium nitrate hexahydrate and 1.3 g of aluminum nitrate nonahydrate are dissolved in 70 mL of deionized water by ultrasonic treatment, and then 3.2 g of urea is added, and after dissolution, it is placed in a polytetrafluoroethylene hydrothermal reactor, sealed and placed in a 100° C. oven for reaction for 24 hours, cooled to room temperature and then taken out, solid-liquid separation, washing, drying and grinding to obtain LDH; according to the mass ratio of the modified coupling agent to LDH being 1:100, an ethanol solution of the modified coupling agent KH570 with a mass fraction of 30% and a pH of 10 is sprayed evenly on the high-speed stirred LDH for multiple times, dispersed at high speed at 60° C. for 30 minutes, then centrifuged for solid-liquid separation, washed with ethanol, dried, and ground to obtain the modified LDH.

[0071] The phosphorus-based flame retardant is ammonium polyphosphate modified with 0.7 mol / L piperazine in ethanol aqueous solution (ethanol to water volume ratio is 20:1);

[0072] The silane coupling agent is γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a weight ratio of 1:1;

[0073] The preparation method of the sealant is similar to that of Example 1, except that the modified LDH@Fe3O4 is replaced by modified LDH.

[0074] Comparative Example 1

[0075] A sealant was prepared in this comparative example, and the specific process was as follows: the composition of the sealant in this comparative example is shown in Table 1, wherein the modified LDH is the same as that in Example 5; the phosphorus-based flame retardant is ammonium polyphosphate; and the silane coupling agent is γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a weight ratio of 1:1.

[0076] The preparation method of the sealant is as described in Example 5.

[0077] Table 1 Sealant composition (unit: weight parts)

[0078]

[0079]

[0080] Test example

[0081] This test example performs a performance test on the sealant prepared in the embodiment, and the specific process is as follows:

[0082] Maximum tensile strength test method / standard: GB / T 13477.8-2017;

[0083] Flame retardant grade test method / standard: GB / T 24267-2009;

[0084] The fire resistance integrity test method / standard is: GB 23864-2009;

[0085] The results are shown in Table 2.

[0086] Table 2

[0087] Group Bond strength (MPa) Flame retardant grade Fire resistance integrity (h) Example 1 1.45 V0 5 Example 2 1.41 V0 3 Example 3 1.40 V1 4 Example 4 1.32 V0 3 Example 5 1.1 V0 4 Comparative Example 1 1.05 V1 3

[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A sealant, characterized in that: The invention comprises the following components: α,ω-dihydroxy polydimethylsiloxane, a structure regulator, a filler, a modified LDH, a phosphorus-based flame retardant, a crosslinking agent, a silane coupling agent, and a catalyst; The modified LDH includes alkylated LDH and / or alkylated LDH@Fe3O4.

2. The sealant according to claim 1, characterized in that: The sealant comprises the following components in parts by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5 to 30 parts of a structural regulator, 70 to 120 parts of a filler, 15 to 50 parts of a modified LDH, 15 to 50 parts of a phosphorus-based flame retardant, 10 to 20 parts of a crosslinking agent, 1.5 to 5 parts of a silane coupling agent, and 0.1 to 0.5 parts of a catalyst.

3. The sealant according to claim 1, characterized in that: The viscosity of the α,ω-dihydroxy polydimethylsiloxane is 20,000 to 50,000 cps.

4. The sealant according to claim 1, characterized in that: The method for preparing alkylated LDH@Fe3O4 comprises the following steps: reacting a Fe3O4 dispersion with a magnesium salt-aluminum salt mixed solution to obtain LDH@Fe3O4, and then reacting the dispersion with a modified coupling agent to obtain the alkylated LDH@Fe3O4.

5. The sealant according to claim 1, characterized in that: The phosphorus-based flame retardant includes at least one of ammonium phosphate, ammonium polyphosphate, ammonium pyrophosphate, melamine, melamine borate, melamine phosphate, melamine polyphosphate, melamine cyanurate, and dimelamine pyrophosphate.

6. The sealant according to claim 5, characterized in that: The phosphorus-based flame retardant includes a phosphorus-based flame retardant modified with piperazine.

7. The sealant according to claim 6, characterized in that: The preparation method of piperazine-modified ammonium polyphosphate comprises the following steps: adding ammonium polyphosphate into piperazine solution, heating for reaction, and obtaining the piperazine-modified ammonium polyphosphate.

8. The sealant according to claim 1, characterized in that: The silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

9. A method for preparing the sealant according to any one of claims 1 to 8, comprising the following steps: The components are mixed and reacted to obtain the sealant.

10. Use of the sealant according to any one of claims 1 to 8 in building sealing.

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