Modified molecular sieve activation powder, silicone sealant and preparation method thereof

Abstract

The invention discloses modified molecular sieve activated powder, a silicone sealant and a preparation method of the modified molecular sieve activated powder and the silicone sealant. The modified molecular sieve activated powder is prepared by modifying molecular sieve activated powder through gamma-aminopropyltrialkoxysilane. The molecular sieve activated powder is prepared by carrying out hydrothermal crystallization on a synthetic liquid containing dimethylamine, pseudo-boehmite, phosphoric acid and water and then roasting. The modified molecular sieve activation powder is added into the alpha, omega-dihydroxy polysiloxane and the auxiliaries, so that the mechanical strength of the prepared silicone sealant is obviously improved, the high-temperature resistance is also obviously enhanced, the silicone sealant can still keep higher mechanical property in a high-temperature environment for a long time, especially the shear strength is obviously improved, and the silicone sealant has a good application prospect. The problems that the mechanical strength of the silicone sealant is reduced in a high-temperature environment and the sealant body is easy to lose efficacy are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and more specifically, relates to a modified molecular sieve activation powder, a high-shear-strength, high-temperature-resistant silicone sealant and a preparation method thereof. Background Art

[0002] Silicone sealant is made of linear polysiloxane as the main raw material, supplemented by cross-linking agents, fillers, plasticizers, coupling agents, catalysts and other additives mixed in a vacuum state. It is also called silicone sealant and forms elastic silicone rubber after curing. Silicone sealant has good weather resistance and high and low temperature resistance, and has many advantages such as good adhesion to various substrates such as glass, metal, plastic, ceramic, stone, etc. Therefore, it is widely used in electronic appliances, construction industry, and transportation. With the rapid development of modern industry, various original parts of electronic devices have put forward higher requirements on the high temperature resistance and mechanical strength of sealants.

[0003] Patent CN201710077333.8 provides a high temperature resistant silicone sealant formula. Although the high temperature resistance of the sealant is improved, the tensile properties of the silicone sealant are significantly reduced due to the addition of too much metal oxide. Patent CN201810177897.3 also provides a high temperature resistant silicone sealant formula. By modifying nano-kaolin and silicone oil, the high temperature resistance of the product is improved after compounding with a silane coupling agent. This method has a complicated process, significantly increases the production cost of the sealant, and the product stability is poor.

[0004] At present, silicone sealants are generally only suitable for use under high temperature conditions of 180℃ to 200℃. Using them at higher temperatures or for a long time will damage the siloxane main chain, resulting in strength deterioration or even powdering, brittleness, interface damage and other colloid failure phenomena.

[0005] Therefore, it is extremely necessary to develop a silicone sealant that can maintain high mechanical strength under high temperature conditions. Summary of the invention

[0006] Based on this, the purpose of the present invention is to provide a modified molecular sieve activation powder, a silicone sealant and a preparation method thereof. The modified molecular sieve activation powder has high reaction activity, and the silicone sealant prepared using the modified molecular sieve activation powder has good mechanical properties and can still maintain a high mechanical strength under high temperature and long-term conditions.

[0007] The specific technical solutions for achieving the above-mentioned invention objectives include the following.

[0008] The first aspect of the present invention provides a modified molecular sieve activation powder, which is obtained by modifying the molecular sieve activation powder with γ-aminopropyltrialkoxysilane, and the molecular sieve activation powder is obtained by hydrothermal crystallization of a synthetic liquid containing dimethylamine, pseudoboehmite, phosphoric acid and water and then calcining it; the weight ratio of the molecular sieve activation powder to γ-aminopropyltrialkoxysilane is 1:1.5~2.0, and the molar ratio of dimethylamine, pseudoboehmite, phosphoric acid and water in the synthetic liquid is 1.5~5.5:0.2~1.2:1:50~150.

[0009] The second aspect of the present invention provides a method for preparing the modified molecular sieve activation powder, comprising the following steps:

[0010] (1) adding phosphoric acid to water, adding pseudo-boehmite while stirring, and then adding dimethylamine, and mixing to obtain a synthetic liquid; subjecting the synthetic liquid to hydrothermal crystallization to obtain a molecular sieve;

[0011] (2) calcining the molecular sieve to obtain molecular sieve activation powder;

[0012] (3) Add ethanol to the molecular sieve activation powder, stir at a material temperature of 40°C to 55°C for 1h to 5h, then add γ-aminopropyltrialkoxysilane, stir for 6h to 10h to obtain the product.

[0013] The third aspect of the present invention provides a silicone sealant comprising the following raw materials in parts by weight:

[0014]

[0015]

[0016] A fourth aspect of the present invention provides a method for preparing the above silicone sealant, comprising the following steps:

[0017] (1) Add α,ω-dihydroxy polysiloxane, dimethyl silicone oil, inorganic filler and modified molecular sieve activation powder into a reaction kettle, stir evenly, set the material temperature at 60°C to 110°C, rotate at 400rpm to 1000rpm, and set the vacuum degree at -0.08MPa to -0.099MPa, and stir for 20min to 200min;

[0018] (2) Cool the material to a temperature not exceeding 40°C, add a cross-linking agent, a coupling agent, and a catalyst, maintain the material temperature below 40°C, rotate at 200 rpm to 400 rpm, and keep the vacuum degree at -0.08 MPa to -0.099 MPa. Stir for 40 min to 120 min, and degas and discharge the material.

[0019] The silicone sealant of the present invention is prepared by adding molecular sieve activation powder modified by γ-aminopropyltrialkoxysilane to α,ω-dihydroxypolysiloxane and an auxiliary agent. The modified molecular sieve activation powder has high reactivity and can effectively participate in the cross-linking reaction of the sealant system, greatly improving the compatibility and dispersibility of the molecular sieve activation powder and silicone rubber. Therefore, the silicone sealant of the present invention not only has significantly improved mechanical strength, but also has significantly enhanced high temperature resistance, and can still maintain high mechanical properties for a long time in a high temperature environment, especially maintaining high shear strength, thereby effectively solving the problem of poor mechanical strength of silicone sealant in a high temperature environment and easy failure of the sealant. DETAILED DESCRIPTION

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

[0021] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0022] Unless otherwise specified, the examples were performed according to conventional experimental conditions or the conditions recommended by the manufacturer's instructions.

[0023] In some embodiments of the present invention, a modified molecular sieve activation powder is disclosed, which is obtained by modifying the molecular sieve activation powder with γ-aminopropyltrialkoxysilane. The molecular sieve activation powder is obtained by hydrothermal crystallization of a synthetic liquid containing dimethylamine, pseudoboehmite, phosphoric acid and water and then calcining it; the weight ratio of the molecular sieve activation powder to γ-aminopropyltrialkoxysilane is 1:1.5~2.0, and the molar ratio of dimethylamine, pseudoboehmite, phosphoric acid and water in the synthetic liquid is 1.5~5.5:0.2~1.2:1:50~150.

[0024] In some of the embodiments, the molar ratio of dimethylamine, pseudo-boehmite, phosphoric acid and water in the synthetic liquid is 1.5-3.5:0.5-0.9:1:70-90.

[0025] In some of the embodiments, the molar ratio of dimethylamine, pseudo-boehmite, phosphoric acid and water in the synthetic liquid is 2.4-2.6:0.6-0.8:1:75-85.

[0026] In some of the embodiments, the weight ratio of the molecular sieve activation powder to γ-aminopropyltrialkoxysilane is 1:1.7-1.8.

[0027] In some embodiments, the hydrothermal crystallization temperature is 120° C. to 200° C., and the hydrothermal crystallization time is 30 h to 60 h.

[0028] In some embodiments, the hydrothermal crystallization temperature is 140° C. to 160° C., and the hydrothermal crystallization time is 45 h to 50 h.

[0029] In some embodiments, the calcination temperature is 450° C. to 650° C., and the calcination time is 4 h to 8 h.

[0030] In other embodiments of the present invention, a method for preparing the modified molecular sieve activation powder is disclosed, comprising the following steps:

[0031] (1) adding phosphoric acid to water, adding pseudo-boehmite while stirring, and then adding dimethylamine, and mixing to obtain a synthetic liquid; performing hydrothermal crystallization on the synthetic liquid to obtain a molecular sieve;

[0032] (2) calcining the molecular sieve to obtain molecular sieve activation powder;

[0033] (3) Add ethanol to the molecular sieve activation powder, stir at a material temperature of 40°C to 55°C for 1h to 5h, then add γ-aminopropyltrialkoxysilane, stir for 6h to 10h to obtain the product.

[0034] In some embodiments, the weight ratio of the molecular sieve activation powder to ethanol in step (3) is 1:5-7, preferably 1:5.5-6.5.

[0035] In some embodiments, the hydrothermal crystallization temperature in step (1) is 120° C. to 200° C., and the hydrothermal crystallization time is 30 h to 60 h.

[0036] In some embodiments, the calcination temperature in step (2) is 450° C. to 650° C., and the calcination time is 4 h to 8 h.

[0037] In some embodiments, the preparation method of the modified molecular sieve activation powder comprises the following steps: adding phosphoric acid to deionized water, adding pseudo-boehmite while stirring, stirring for 6h to 12h, adding dimethylamine, and fully mixing to obtain a synthetic solution, hydrothermally crystallizing the synthetic solution at 140°C to 160°C for 45h to 50h to obtain a molecular sieve; then calcining at 450°C to 650°C for 4h to 8h to obtain a molecular sieve activation powder; adding ethanol to the molecular sieve activation powder, and heating at a material temperature of 40°C to 55°C. The mixture is stirred for 1 h to 5 h, and then γ-aminopropyltrialkoxysilane is added. After stirring for 6 h to 10 h, the mixture is washed and dried to obtain a modified molecular sieve activation powder. The molar ratio of dimethylamine, pseudo-boehmite, phosphoric acid and deionized water in the synthetic liquid is 2.4 to 2.6: 0.6 to 0.8: 1: 75 to 85. The weight ratio of the molecular sieve activation powder to ethanol is 1: 5.5 to 6.5. The weight ratio of the molecular sieve activation powder to γ-aminopropyltrialkoxysilane is 1: 1.7 to 1.8.

[0038] In some other embodiments of the present invention, a silicone sealant is disclosed, which includes the following raw materials in parts by weight:

[0039]

[0040] In some embodiments, the silicone sealant comprises the following raw materials in parts by weight:

[0041]

[0042] In some embodiments, the silicone sealant comprises the following raw materials in parts by weight:

[0043]

[0044] In some embodiments, the viscosity of the α,ω-dihydroxy polysiloxane at 25° C. is 5000 mPa·s to 50000 mPa·s.

[0045] In some embodiments, the viscosity of the dimethyl silicone oil at 25° C. is 100 mPa·s to 2000 mPa·s.

[0046] In some embodiments, the inorganic filler is one or more of active nano calcium carbonate, heavy calcium carbonate, carbon black, and white carbon black.

[0047] In some embodiments, the crosslinking agent is one or more of methyltrimethoxysilane, propyltrimethoxysilane, octyltrimethoxysilane, phenyltrimethoxysilane, and vinyltrimethoxysilane.

[0048] In some of the embodiments, the coupling agent is one or more of isocyanate trialkoxy silane, γ-aminopropyl trialkoxy silane, N-(β-aminoethyl)-γ-aminopropyl trialkoxy silane, and γ-glycidyl ether alkyl trialkoxy silane.

[0049] In some embodiments, the catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate and tin octoate.

[0050] In other embodiments of the present invention, a method for preparing the above silicone sealant is disclosed, comprising the following steps:

[0051] (1) Add α,ω-dihydroxy polysiloxane, dimethyl silicone oil, inorganic filler and modified molecular sieve activation powder into a reaction kettle, stir evenly, set the material temperature at 60°C to 110°C, rotate at 400rpm to 1000rpm, and set the vacuum degree at -0.08MPa to -0.099MPa, and stir for 20min to 200min;

[0052] (2) Cool the material to a temperature not exceeding 40°C, add a cross-linking agent, a coupling agent, and a catalyst, maintain the material temperature below 40°C, rotate at 200 rpm to 400 rpm, and keep the vacuum degree at -0.08 MPa to -0.099 MPa. Stir for 40 min to 120 min, and degas and discharge the material.

[0053] The present invention is described in detail below with reference to specific embodiments.

[0054] Example 1 Preparation of modified molecular sieve activation powder and silicone sealant

[0055] The following steps are involved:

[0056] 1. Preparation of modified molecular sieve activation powder

[0057] (1) Add deionized water to a certain amount of phosphoric acid, add pseudo-boehmite while stirring, stir vigorously for 8 hours, slowly add the template agent dimethylamine, stir for 24 hours to fully mix, and obtain a synthetic solution. The molar ratio of each substance in the synthetic solution is 2.5 (CH3)2NH4: 0.7Al2O3: 1P2O5: 80H2O;

[0058] (2) pouring the synthetic liquid into a stainless steel reactor containing a polytetrafluoroethylene liner, and hydrothermally crystallizing it in an oven at 150° C. for 48 h to obtain a molecular sieve;

[0059] (3) washing the obtained molecular sieve with deionized water and centrifuging until it is nearly neutral, drying at 100° C. for 10 h, and then calcining in a muffle furnace at 550° C. for 6 h to remove the template, and the obtained product is the molecular sieve activation powder;

[0060] (4) 20 g of molecular sieve activation powder was placed in a flask, 120 g of ethanol was added, and the mixture was stirred at 50°C for 1.5 h. Then 35 g of γ-aminopropyltrialkoxysilane was added, and the mixture was stirred for 8 h. The mixture was washed with deionized water and dried completely. The obtained product was the modified molecular sieve activation powder.

[0061] 2. Preparation of silicone sealant

[0062] (1) 100 parts of α,ω-dihydroxy polysiloxane with a viscosity of 50000 mPa·s, 50 parts of dimethyl silicone oil with a viscosity of 200 mPa·s, 30 parts of active nano calcium carbonate, 60 parts of heavy calcium carbonate and 50 parts of modified molecular sieve activation powder were added to a reactor, stirred and mixed, and the material temperature was set to 80° C., the rotation speed was 600 rpm, the vacuum degree was -0.085 MPa, and the mixture was stirred and dehydrated for 60 minutes;

[0063] (2) Cooling water was passed through the mixture to cool the material to 35° C., and 4 parts of methyltrimethoxysilane, 1.5 parts of N-(β-aminoethyl)-γ-aminopropyltrialkoxysilane, and 0.6 parts of dibutyltin dilaurate were added. The material temperature was maintained at 35° C., the rotation speed was 240 rpm, and the vacuum degree was -0.095 MPa. After stirring for 50 minutes, the material was degassed and discharged to obtain a silicone sealant.

[0064] Example 2 Preparation of modified molecular sieve activation powder and silicone sealant

[0065] The following steps are involved:

[0066] 1. Preparation of modified molecular sieve activation powder

[0067] (1) Deionized water was added to a certain amount of phosphoric acid, and pseudo-boehmite was added while stirring. After vigorous stirring for 9 hours, the template agent dimethylamine was slowly added, and stirred for 22 hours to fully mix to obtain a synthetic solution. The molar ratio of each substance in the synthetic solution was 2.1 (CH3)2NH4: 0.9Al2O3: 1P2O5: 70H2O;

[0068] (2) pouring the synthetic liquid into a stainless steel reactor containing a polytetrafluoroethylene liner, and hydrothermally crystallizing it in an oven at 150° C. for 48 h to obtain a molecular sieve;

[0069] (3) washing the obtained molecular sieve with deionized water and centrifuging until it is nearly neutral, drying at 100° C. for 10 h, and then calcining in a muffle furnace at 590° C. for 5.5 h to remove the template, and the obtained product is the molecular sieve activation powder;

[0070] (4) 20 g of molecular sieve activation powder was placed in a flask, 120 g of ethanol was added, and the mixture was stirred at 50°C for 1.5 h. Then 35 g of γ-aminopropyltrialkoxysilane was added, and the mixture was stirred for 8 h. The mixture was washed with deionized water and dried completely. The obtained product was the modified molecular sieve activation powder.

[0071] 2. Preparation of silicone sealant

[0072] (1) 100 parts of α,ω-dihydroxy polysiloxane with a viscosity of 50000 mPa·s, 85 parts of dimethyl silicone oil with a viscosity of 100 mPa·s, 40 parts of fumed silica and 60 parts of modified molecular sieve activation powder were added to a reactor, stirred and mixed, and the material temperature was set to 80°C, the rotation speed was 600 rpm, the vacuum degree was -0.085 MPa, and the mixture was stirred and dehydrated for 60 minutes;

[0073] (2) Cooling water was passed through the mixture to cool the material to 35° C., and 3 parts of propyltrimethoxysilane, 1.5 parts of γ-aminopropyltrialkoxysilane, and 0.45 parts of dibutyltin dilaurate were added. The material temperature was maintained at 35° C., the rotation speed was 240 rpm, and the vacuum degree was -0.095 MPa. After stirring for 50 minutes, the material was degassed and discharged to obtain a silicone sealant.

[0074] Example 3 Preparation of modified molecular sieve activation powder and silicone sealant

[0075] The following steps are involved:

[0076] 1. Preparation of modified molecular sieve activation powder

[0077] (1) Add deionized water to a certain amount of phosphoric acid, add pseudo-boehmite while stirring, stir vigorously for 8 hours, slowly add the template agent dimethylamine, stir for 24 hours to fully mix, and obtain a synthetic solution. The molar ratio of each substance in the synthetic solution is 2.5 (CH3)2NH4: 0.7Al2O3: 1P2O5: 80H2O;

[0078] (2) pouring the synthetic liquid into a stainless steel reactor containing a polytetrafluoroethylene liner, and hydrothermally crystallizing it in an oven at 150° C. for 48 h to obtain a molecular sieve;

[0079] (3) washing the obtained molecular sieve with deionized water and centrifuging until it is nearly neutral, drying at 100° C. for 10 h, and then calcining in a muffle furnace at 550° C. for 6 h to remove the template, and the obtained product is the molecular sieve activation powder;

[0080] (4) 20 g of molecular sieve activation powder was placed in a flask, 120 g of ethanol was added, and the mixture was stirred at 50°C for 1.5 h. Then 35 g of γ-aminopropyltrialkoxysilane was added, and the mixture was stirred for 8 h. The mixture was washed with deionized water and dried completely. The obtained product was the modified molecular sieve activation powder.

[0081] 2. Preparation of silicone sealant

[0082] (1) 100 parts of α,ω-dihydroxy polysiloxane with a viscosity of 50000 mPa·s, 60 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, 80 parts of active nano-calcium carbonate and 35 parts of modified molecular sieve activation powder were added to a reaction kettle, stirred and mixed, and the material temperature was set to 80° C., the rotation speed was 600 rpm, the vacuum degree was -0.085 MPa, and the mixture was stirred and dehydrated for 60 minutes;

[0083] (2) Cooling water was passed through the material to cool down to 35° C., and 4 parts of vinyl trimethoxysilane, 1 part of γ-glycidyl ether alkyl trialkoxysilane, and 0.6 parts of dibutyl tin diacetate were added. The material temperature was maintained at 35° C., the rotation speed was 240 rpm, and the vacuum degree was -0.095 MPa. After stirring for 50 minutes, the material was degassed and discharged to obtain a silicone sealant.

[0084] Comparative Example 1

[0085] The silicone sealant of this comparative example is the same as that of Example 1 except that the modified molecular sieve activation powder is replaced by an equal amount of nano calcium carbonate. Other components, dosages and preparation methods are the same as those of Example 1.

[0086] Comparative Example 2

[0087] The silicone sealant of this comparative example is the same as that of Example 1, except that the modified molecular sieve activation powder is replaced by an equal amount of unmodified molecular sieve activation powder (the preparation method is the same as that of step 1 (1) to (3) of Example 1). Other components, amounts and preparation method are the same as those of Example 1.

[0088] Comparative Example 3

[0089] The silicone sealant of this comparative example is the same as that of Example 1 in terms of components, dosage and preparation method, except that 4A molecular sieve activation powder (Zhengzhou Chaorong Nanomaterial Co., Ltd.) is used in an equal amount to replace the modified molecular sieve activation powder.

[0090] After the silicone sealant specimens prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were fully cured under standard conditions, they were stored under different temperature conditions for a certain period of time and then subjected to performance tests. The test method is as follows:

[0091] 1. Tensile strength: measured in accordance with GB / T 528-2009.

[0092] 2. Elongation: Measured in accordance with the provisions of GB / T 528-2009.

[0093] 3. Shear strength: measured in accordance with the provisions of GB / T 7124-2008.

[0094] Product performance indicators are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] As can be seen from Table 1, the silicone sealant (Examples 1 to 3) prepared using the modified molecular sieve activation powder independently synthesized by the present invention has high tensile strength, large elongation, high shear strength, and still has high mechanical properties under high temperature and long time (250°C 14d, 320°C 14d) conditions, indicating that the silicone sealant of the present invention has good high temperature resistance.

[0099] In Comparative Example 1, no modified molecular sieve activation powder was added to the sealant raw material, and its mechanical properties were significantly reduced compared with the silicone sealant in Example 1, and the mechanical strength of the test piece decreased rapidly after high-temperature curing.

[0100] In Comparative Example 2, unmodified molecular sieve activation powder was used to prepare the sealant, and its mechanical properties were worse than those in Example 1. This was because the modified molecular sieve activation powder could effectively combine with γ-aminopropyltrialkoxysilane, making the modified molecular sieve activation powder more active, and could produce effective cross-linking reactions with each component during the cross-linking process of the silicone sealant, with better dispersibility and compatibility. Moreover, under high temperature and long-term conditions, the siloxane main chain was not easily damaged, and a relatively high shear strength could still be maintained.

[0101] In Comparative Example 3, conventional 4A molecular sieve activation powder was used in an equal amount to replace the modified molecular sieve activation powder. The mechanical strength and high temperature resistance of the silicone sealant prepared by it were not as good as those in Example 1; and were not as good as the mechanical strength and high temperature resistance of the silicone sealant prepared using the homemade molecular sieve activation powder of the present invention (Comparative Example 2).

[0102] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A modified molecular sieve activation powder, characterized in that: The invention discloses a novel molecular sieve activation powder which is prepared by modifying molecular sieve activation powder with γ-aminopropyltrialkoxysilane. The molecular sieve activation powder is prepared by hydrothermally crystallizing a synthetic liquid containing dimethylamine, pseudoboehmite, phosphoric acid and water and then calcining the liquid. The weight ratio of the molecular sieve activation powder to γ-aminopropyltrialkoxysilane is 1:1.5-2.0, and the molar ratio of dimethylamine, pseudoboehmite, phosphoric acid and water in the synthetic liquid is 1.5-5.5:0.2-1.2:1:50-150.

2. The modified molecular sieve activation powder according to claim 1, characterized in that: The molar ratio of dimethylamine, pseudo-boehmite, phosphoric acid and water in the synthetic liquid is 1.5-3.5:0.5-0.9:1:70-90, preferably 2.4-2.6:0.6-0.8:1:75-85.

3. The modified molecular sieve activation powder according to claim 1, characterized in that: The weight ratio of the molecular sieve activation powder to gamma-aminopropyltrialkoxysilane is 1:1.7-1.

8.

4. The modified molecular sieve activation powder according to claim 1, characterized in that: The hydrothermal crystallization temperature is 120°C to 200°C, and the hydrothermal crystallization time is 30h to 60h. Preferably, the hydrothermal crystallization temperature is 140°C to 160°C, and the hydrothermal crystallization time is 45h to 50h; and / or, the calcination temperature is 450°C to 650°C, and the calcination time is 4h to 8h.

5. A method for preparing the modified molecular sieve activation powder according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) adding phosphoric acid to water, adding pseudo-boehmite while stirring, and then adding dimethylamine, and mixing to obtain a synthetic liquid; subjecting the synthetic liquid to hydrothermal crystallization to obtain a molecular sieve; (2) calcining the molecular sieve to obtain molecular sieve activation powder; (3) Add ethanol to the molecular sieve activation powder, stir at a material temperature of 40°C to 55°C for 1h to 5h, then add γ-aminopropyltrialkoxysilane, stir for 6h to 10h to obtain the product.

6. The method for preparing the modified molecular sieve activation powder according to claim 5, characterized in that: The weight ratio of the molecular sieve activation powder to ethanol in step (3) is 1:5-7, preferably 1:5.5-6.5; and / or the temperature of the hydrothermal crystallization in step (1) is 120°C-200°C, and the time of the hydrothermal crystallization is 30h-60h; and / or the temperature of the roasting in step (2) is 450°C-650°C, and the time of the roasting is 4h-8h.

7. A silicone sealant, characterized in that: It includes the following raw materials in parts by weight:

8. The silicone sealant according to claim 7, characterized in that: It includes the following raw materials in parts by weight: More preferably, it comprises the following raw materials in parts by weight:

9. The silicone sealant according to claim 7 or 8, characterized in that: The viscosity of the α,ω-dihydroxy polysiloxane at 25° C. is 5000 mPa·s to 50000 mPa·s; And / or, the viscosity of the dimethyl silicone oil at 25° C. is 100 mPa·s to 2000 mPa·s; And / or, the inorganic filler is one or more of active nano calcium carbonate, heavy calcium carbonate, carbon black, and white carbon black; And / or, the crosslinking agent is one or more of methyltrimethoxysilane, propyltrimethoxysilane, octyltrimethoxysilane, phenyltrimethoxysilane, and vinyltrimethoxysilane; And / or, the coupling agent is one or more of isocyanate trialkoxysilane, γ-aminopropyl trialkoxysilane, N-(β-aminoethyl)-γ-aminopropyl trialkoxysilane, and γ-glycidyl ether alkyl trialkoxysilane; And / or, the catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate and tin octoate.

10. The method for preparing the silicone sealant according to any one of claims 7 to 9, characterized in that: The following steps are involved: (1) Add α,ω-dihydroxy polysiloxane, dimethyl silicone oil, inorganic filler and modified molecular sieve activation powder into a reaction kettle, stir evenly, set the material temperature at 60°C to 110°C, rotate at 400rpm to 1000rpm, and set the vacuum degree at -0.08MPa to -0.099MPa, and stir for 20min to 200min; (2) Cool the material to a temperature not exceeding 40°C, add a cross-linking agent, a coupling agent, and a catalyst, maintain the material temperature below 40°C, rotate at 200 rpm to 400 rpm, and keep the vacuum degree at -0.08 MPa to -0.099 MPa. Stir for 40 min to 120 min, and degas and discharge the material.

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