Silicone sealant

Abstract

The invention relates to a silicone sealant, and belongs to the technical field of adhesives. The ceramic powder is modified by using the silane coupling agent kh-550 and the flame retardant TBC according to the characteristic that the amino group reacts with an isocyanate group, the ceramic powder is grafted with the kh-550 and then has the amino group on the surface, and the amino group can react with the isocyanate group in the flame retardant TBC to obtain the modified ceramic powder grafted with the flame retardant TBC; after the modified ceramic powder is grafted with the flame retardant, the problem of phase separation possibly caused by direct blending can be avoided, the overall components are more uniform, the synergistic flame retardant effect of an organic layer and an inorganic layer is better exerted, in addition, the modified ceramic powder can react with 107 silicone rubber to form chemical bonds, the bridging effect of a molecular layer is achieved, and the flame retardant effect is improved. The bonding force between an organic interface and an inorganic interface is enhanced, the overall crosslinking density of the sealant is improved, and the finally prepared silicone sealant has good fireproof and flame-retardant properties and mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular, relates to a silicone sealant. Background Art

[0002] As buildings develop towards high-rise and large-scale, people's requirements for building fire safety are constantly increasing. Silicone sealants are widely used in the field of building sealing materials due to their excellent bonding properties and aging resistance. However, silicone sealants themselves are flammable materials and can burn at temperatures of 200-300°C. Although flame-retardant sealants exist in the prior art, these sealants will not burn themselves, but will still cause powdering in a flame environment, thereby losing their sealing effect and causing the spread of flames. Therefore, there is an urgent need in the prior art to develop fire-retardant sealants that can maintain integrity for a long time in flames.

[0003] By adding ceramic powder to silicone sealant, the sealant can be ceramicized in a flame environment to produce a supporting ceramic shell, but the interface bonding performance between ceramic powder and silicone sealant is poor. Adding ceramic powder will lead to degradation of the mechanical properties of silicone sealant to a certain extent. When added in excessive amounts, it will also cause catalysis of silicone sealant and produce interface stratification, significantly reducing the tensile strength and elongation at break of silicone sealant. In addition, adding ceramic powder will further increase the viscosity of silicone sealant, thereby affecting the dispersion of flame retardants. The above disadvantages have limited the development of fire-retardant sealants. Based on this, the present invention provides a silicone sealant. Summary of the invention

[0004] The object of the present invention is to provide a silicone sealant to solve the problems mentioned in the above background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A silicone sealant comprises the following raw materials in parts by mass: 80 to 100 parts of 107 silicone rubber, 20 to 60 parts of nano calcium carbonate, 1 to 4 parts of vinyl tributylidene oxime silane, 6 to 16 parts of methyl tributylidene oxime silane, 0.04 to 0.12 parts of a catalyst, and 8 to 18 parts of modified ceramic powder;

[0007] Furthermore, the viscosity specification of the 107 silicone rubber is 50000-1200000 mPa·s.

[0008] Furthermore, the particle size of the nano calcium carbonate is 5 to 20 nm.

[0009] Furthermore, the catalyst is one of dibutyltin dilaurate, dimethyltin diceneodecanoate, and dibutyltin dioctoate.

[0010] Furthermore, the modified ceramic powder is prepared by the following steps:

[0011] The first step is to mix the ceramic powder, KH-550 and ethanol solution evenly, and then control the system temperature to 40-80°C for reaction. After the reaction is completed, filter out the ceramic powder, wash it with anhydrous ethanol and deionized water, and then dry it to obtain the grafted ceramic powder;

[0012] In the second step, after the grafted ceramic powder, flame retardant TBC and toluene are evenly mixed, the system temperature is controlled at 30-110°C for reaction. After the reaction is completed, the ceramic powder is filtered out, washed with anhydrous ethanol and deionized water respectively, and then dried to obtain modified ceramic powder.

[0013] Furthermore, the ethanol solution used in the first step is an ethanol aqueous solution, and the volume fraction of the ethanol solution is preferably 60-80%.

[0014] Furthermore, the mass ratio of the ceramic powder and kh-550 used in the first step is 8-18:2-8.

[0015] Furthermore, in terms of mass fractions, the mass fraction ratio of the grafted ceramic powder, flame retardant TBC, and toluene used in the second step is 8-18:6-24:200-500.

[0016] Furthermore, the kh-550 is γ-aminopropyltriethoxysilane.

[0017] Furthermore, the flame retardant TBC is tris(2,3-dibromopropyl)isocyanurate.

[0018] Furthermore, the preparation method of the silicone sealant comprises the following steps:

[0019] Put 107 silicone rubber, nano calcium carbonate and modified ceramic powder into a vacuum kneader, stir and dehydrate for 2 to 4 hours at a vacuum degree of 0.08 to 0.09 MPa and a temperature of 110 to 150°C, cool to room temperature after the treatment, transfer the base material to a planetary mixer, add vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane into the planetary mixer, and then stir for 20 to 60 minutes at a vacuum degree of 0.08 to 0.09 MPa, then introduce nitrogen to release the vacuum, add a catalyst into the planetary mixer, and continue stirring for 20 to 60 minutes at a vacuum degree of 0.08 to 0.09 MPa to obtain a silicone sealant.

[0020] Beneficial effects of the present invention:

[0021] 1) The present invention utilizes the characteristics of the reaction between amino groups and isocyanate groups, and uses silane coupling agent KH-550 and flame retardant TBC to modify ceramic powder. After the ceramic powder is grafted with KH-550, the surface has amino groups, which can react with the isocyanate groups in the flame retardant TBC to obtain modified ceramic powder grafted with flame retardant TBC. After the modified ceramic powder is grafted with the flame retardant, the phase separation problem that may be caused by direct blending can be avoided, so that the overall components are more uniform, and the synergistic flame retardant effect of the organic and inorganic levels can be better exerted. The flame retardant TBC mainly responds quickly at the initial stage of the flame, while the thermal insulation effect of the ceramic powder can delay the rise of the internal temperature of the sealant to a certain extent, and ceramicize at extremely high temperatures, which has a supporting effect on the sealant as a whole, so that the sealant does not ash or collapse in a continuous flame combustion environment. The synergistic effect of the two can achieve a better flame retardant effect.

[0022] 2) The surface of the modified ceramic powder of the present invention is loaded with flame retardant TBC. The flame retardant TBC contains isocyanate groups that are easily reactive with hydroxyl groups and can react with hydroxyl groups in 107 silicone rubber (α, ω-dihydroxypolysiloxane), thereby playing a bridging role at the molecular level, enhancing the bonding force between the organic interface and the inorganic interface, and increasing the overall crosslinking density of the sealant, thereby reducing the effect of inorganic filler doping on the overall tensile properties of the sealant and improving the overall mechanical properties of the sealant. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] A silicone sealant comprises the following raw materials in parts by mass: 80 parts of 107 silicone rubber, 20 parts of nano calcium carbonate, 1 part of vinyl tributylidene oxime silane, 6 parts of methyl tributylidene oxime silane, 0.04 parts of dibutyltin dilaurate and 8 parts of modified ceramic powder.

[0026] The viscosity of the 107 silicone rubber used in this embodiment is 50000 mPa·s, the particle size of the nano calcium carbonate used is 5-20 nm, and the modified ceramic powder used in this embodiment is prepared by the following steps:

[0027] The first step is to mix 8 parts of ceramic powder, 2 parts of KH-550, and 200 parts of 60% ethanol aqueous solution by volume, and control the system temperature to 40°C for 12 hours. After the reaction is completed, filter out the ceramic powder, wash it with anhydrous ethanol and deionized water, and then dry it to obtain the grafted ceramic powder;

[0028] In the second step, 8 parts of grafted ceramic powder, 6 parts of flame retardant TBC and 200 parts of toluene were mixed evenly, and the system temperature was controlled at 30°C to react for 24 hours. After the reaction was completed, the ceramic powder was filtered out, washed with anhydrous ethanol and deionized water respectively, and then dried to obtain modified ceramic powder.

[0029] The silicone sealant in this embodiment is prepared by the following steps:

[0030] 107 silicone rubber, nano-calcium carbonate and modified ceramic powder were put into a vacuum kneader, stirred and dehydrated for 4 hours at a vacuum degree of 0.08 MPa and a temperature of 110°C. After the treatment, the base material was cooled to room temperature and transferred to a planetary mixer. Vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane were added to the planetary mixer, and then stirred for 20 minutes at a vacuum degree of 0.08 MPa. Then, nitrogen was introduced to release the vacuum, and dibutyl tin dilaurate was added to the planetary mixer. Stirring was continued for 20 minutes at a vacuum degree of 0.08 MPa to obtain a silicone sealant.

[0031] Example 2

[0032] A silicone sealant comprises the following raw materials in parts by mass: 90 parts of 107 silicone rubber, 40 parts of nano calcium carbonate, 2.5 parts of vinyl tributylidene oxime silane, 11 parts of methyl tributylidene oxime silane, 0.08 parts of dimethyltin dineodecanoate, and 13 parts of modified ceramic powder.

[0033] The viscosity of the 107 silicone rubber used in this embodiment is 800000 mPa·s, the particle size of the nano calcium carbonate used is 5 to 20 nm, and the modified ceramic powder used in this embodiment is prepared by the following steps:

[0034] The first step is to mix 13 parts of ceramic powder, 5 parts of KH-550, and 350 parts of 70% ethanol aqueous solution by volume, and control the system temperature to 60°C for 8 hours. After the reaction is completed, filter out the ceramic powder, wash it with anhydrous ethanol and deionized water, and then dry it to obtain the grafted ceramic powder;

[0035] In the second step, 13 parts of grafted ceramic powder, 15 parts of flame retardant TBC and 350 parts of toluene were mixed evenly, and the system temperature was controlled to 70°C for reaction for 12 hours. After the reaction was completed, the ceramic powder was filtered out, washed with anhydrous ethanol and deionized water respectively, and then dried to obtain modified ceramic powder.

[0036] The silicone sealant in this embodiment is prepared by the following steps:

[0037] 107 silicone rubber, nano-calcium carbonate and modified ceramic powder were put into a vacuum kneader and stirred for dehydration at a vacuum degree of 0.085 MPa and a temperature of 130°C for 3 hours. After the treatment, the base material was cooled to room temperature and transferred to a planetary mixer. Vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane were added to the planetary mixer, and then stirred for 40 minutes at a vacuum degree of 0.085 MPa. Then, nitrogen was introduced to release the vacuum, and dimethyltin dineodecanoate was added to the planetary mixer. Stirring was continued for 40 minutes at a vacuum degree of 0.085 MPa to obtain a silicone sealant.

[0038] Example 3

[0039] A silicone sealant comprises the following raw materials in parts by mass: 100 parts of 107 silicone rubber, 60 parts of nano calcium carbonate, 4 parts of vinyl tributylidene oxime silane, 16 parts of methyl tributylidene oxime silane, 0.12 parts of dibutyltin dioctoate and 18 parts of modified ceramic powder.

[0040] The viscosity specification of the 107 silicone rubber used in this embodiment is 1200000 mPa·s, the particle size specification of the nano calcium carbonate used is 5-20 nm, and the modified ceramic powder used in this embodiment is prepared by the following steps:

[0041] The first step is to mix 18 parts of ceramic powder, 8 parts of KH-550, and 500 parts of ethanol aqueous solution with a volume fraction of 80%, and control the system temperature to 80°C for 4 hours. After the reaction is completed, filter out the ceramic powder, wash it with anhydrous ethanol and deionized water, and then dry it to obtain the grafted ceramic powder;

[0042] In the second step, 18 parts of grafted ceramic powder, 24 parts of flame retardant TBC and 500 parts of toluene were mixed evenly, and the system temperature was controlled to be 110°C for reaction for 6 hours. After the reaction was completed, the ceramic powder was filtered out, washed with anhydrous ethanol and deionized water respectively, and then dried to obtain modified ceramic powder.

[0043] The silicone sealant in this embodiment is prepared by the following steps:

[0044] 107 silicone rubber, nano calcium carbonate and modified ceramic powder were put into a vacuum kneader, stirred and dehydrated for 4 hours at a vacuum degree of 0.09 MPa and a temperature of 150°C. After the treatment, the base material was cooled to room temperature and transferred to a planetary mixer. Vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane were added to the planetary mixer, and then stirred for 60 minutes at a vacuum degree of 0.09 MPa. Then, nitrogen was introduced to release the vacuum, and dibutyl tin dioctoate was added to the planetary mixer. Stirring was continued for 60 minutes at a vacuum degree of 0.09 MPa to obtain a silicone sealant.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 2 is that the ceramic powder is not modified, and the flame retardant TBC is added by direct blending;

[0047] A silicone sealant comprises the following raw materials in parts by mass: 90 parts of 107 silicone rubber, 40 parts of nano calcium carbonate, 2.5 parts of vinyl tributylidene oxime silane, 11 parts of methyl tributylidene oxime silane, 0.08 parts of dimethyltin dineodecanoate, 10 parts of ceramic powder, and 3 parts of flame retardant TBC.

[0048] Among them, the viscosity specification of the 107 silicone rubber used in this comparative example is 800000 mPa·s, and the particle size specification of the nano calcium carbonate used is 5 to 20 nm:

[0049] The silicone sealant in this comparative example is prepared by the following steps:

[0050] 107 silicone rubber, nano calcium carbonate, ceramic powder and flame retardant TBC were put into a vacuum kneader and stirred for dehydration at a vacuum degree of 0.085 MPa and a temperature of 130°C for 3 hours. After the treatment, the base material was cooled to room temperature and transferred to a planetary mixer. Vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane were added to the planetary mixer, and then stirred for 40 minutes at a vacuum degree of 0.085 MPa. Then, nitrogen was introduced to release the vacuum, and dimethyl tin dineodecanoate was added to the planetary mixer. Stirring was continued for 40 minutes at a vacuum degree of 0.085 MPa to obtain a silicone sealant.

[0051] Comparative Example 2

[0052] A silicone sealant comprises the following raw materials in parts by mass: 90 parts of 107 silicone rubber, 40 parts of nano calcium carbonate, 2.5 parts of vinyl tributylidene oxime silane, 11 parts of methyl tributylidene oxime silane, 0.08 parts of dimethyltin dineodecanoate, 10 parts of grafted ceramic powder, and 3 parts of flame retardant TBC.

[0053] The viscosity of the 107 silicone rubber used in this comparative example is 800000 mPa·s, the particle size of the nano calcium carbonate used is 5 to 20 nm, and the grafted ceramic powder used in this comparative example is prepared by the following steps:

[0054] In the first step, 13 parts of ceramic powder, 5 parts of KH-550, and 350 parts of 70% ethanol aqueous solution were mixed, and the system temperature was controlled to 60°C for 8 hours. After the reaction, the ceramic powder was filtered out, washed with anhydrous ethanol and deionized water, and then dried to obtain grafted ceramic powder.

[0055] The silicone sealant in this comparative example is prepared by the following steps:

[0056] 107 silicone rubber, nano calcium carbonate, grafted ceramic powder and flame retardant TBC were put into a vacuum kneader and stirred for dehydration at a vacuum degree of 0.085 MPa and a temperature of 130°C for 3 hours. After the treatment, the base material was cooled to room temperature and transferred to a planetary mixer. Vinyl trisbutyl ketoxime silane and methyl trisbutyl ketoxime silane were added to the planetary mixer, and then stirred for 40 minutes at a vacuum degree of 0.085 MPa. Then, nitrogen was introduced to release the vacuum, and dimethyltin dineodecanoate was added to the planetary mixer. Stirring was continued for 40 minutes at a vacuum degree of 0.085 MPa to obtain a silicone sealant.

[0057] Comparative Example 3

[0058] This comparative example is a commercially available flame retardant silicone sealant.

[0059] Experimental Example 1

[0060] The silicone sealants in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to the following performance tests together with the commercially available flame-retardant silicone sealant in Comparative Example 3:

[0061] Tensile performance test: Tested in accordance with the national standard GB 13477.8-2017 "Test methods for building sealing materials Part 8: Determination of tensile adhesion";

[0062] Fire resistance test: Tested in accordance with the national standard GB 23864-2023 "Fireproof blocking materials";

[0063] Flame retardant performance test: The test was carried out in accordance with the national standard GB / T 24267-2009 "Flame retardant sealant for construction". The test results are shown in Table 1:

[0064] Table 1

[0065]

[0066]

[0067] It can be seen from Table 1 that the silicone sealant obtained in Examples 1 to 3 has better overall strength and flame retardant properties than commercially available flame retardant silicone sealants, and can last longer in flames. Comparative Examples 1 to 2 are control experiments of Example 2, in which equal amounts of flame retardants are added in proportion and added to the flame retardant sealant in different ways. It can be seen that the method of directly blending and adding flame retardants cannot achieve the expected flame retardant effect. The reason is that the viscosity of the silicone sealant itself is relatively large, and the flame retardant is difficult to be evenly dispersed in the sealant as a whole, resulting in uneven overall components. In addition, it can be seen that the grafted flame retardant TBC effectively improves the tensile strength and elongation at break of the sealant. The reason is that the bridging effect between molecules effectively improves the bonding force between the organic phase and the inorganic phase inside the sealant.

[0068] A silicone sealant provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be used in combination with each other in any way. The fact that these combinations are not exhaustively described in this specification is only for the purpose of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A silicone sealant, characterized in that: The invention comprises the following raw materials in parts by weight: 80 to 100 parts of 107 silicone rubber, 20 to 60 parts of nano calcium carbonate, 1 to 4 parts of vinyl tributylacetoximate silane, 6 to 16 parts of methyl tributylacetoximate silane, 0.04 to 0.12 parts of catalyst, and 8 to 18 parts of modified ceramic powder; Wherein, the modified ceramic powder is prepared by the following steps: The ceramic powder is modified with kh-550 to obtain grafted ceramic powder, and then the grafted ceramic powder, flame retardant TBC and toluene are mixed and the system temperature is controlled to be 30-110° C. to react to obtain modified ceramic powder.

2. A silicone sealant according to claim 1, characterized in that: The viscosity specification of the 107 silicone rubber is 50000-1200000 mPa·s.

3. The silicone sealant according to claim 1, characterized in that: The particle size specification of the nano calcium carbonate is 5 to 20 nm.

4. The silicone sealant according to claim 1, characterized in that: The catalyst is one of dibutyltin dilaurate, dimethyltin diceneodecanoate and dibutyltin dioctoate.

5. The silicone sealant according to claim 1, characterized in that: Calculated by mass, the mass ratio of the ceramic powder to kh-550 is 8-18:2-8.

6. The silicone sealant according to claim 1, characterized in that: Calculated by mass, the mass ratio of the grafted ceramic powder, the flame retardant TBC, and toluene is 8-18:6-24:200-500.

7. The silicone sealant according to claim 1, characterized in that: The preparation method of the silicone sealant comprises the following steps: 107 silicone rubber, nano calcium carbonate and modified ceramic powder are subjected to vacuum dehydration treatment, and then vinyl trisbutyl ketoxime silane, methyl trisbutyl ketoxime silane and a catalyst are sequentially added to the base material and mixed by vacuum stirring to obtain a silicone sealant.

8. The silicone sealant according to claim 7, characterized in that: The vacuum degree condition for vacuum dehydration is 0.08~0.08MPa.

9. The silicone sealant according to claim 7, characterized in that: The temperature condition for vacuum dehydration is 110-150°C.

10. The silicone sealant according to claim 7, characterized in that: The time condition for vacuum dehydration is 2 to 4 hours.

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