A modified polysilazane, two-component silicone sealant and a method for preparing the same

Abstract

This invention discloses a modified polysilazane, a two-component silicone sealant, and a method for preparing the same. The modified polysilazane is prepared through a nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine. The two-component silicone sealant prepared using the modified polysilazane of this invention significantly improves its hardness under sealed conditions without adversely affecting its curing and performance. Furthermore, it requires a small amount and is highly practical. The two-component silicone sealant prepared using the modified polysilazane of this invention exhibits high hardness retention under sealed conditions, significantly slows down the reversion phenomenon, and maintains good mechanical properties and adhesion even after curing at 90°C under sealed conditions. It also demonstrates excellent resistance to reversion under fully sealed conditions.

Description

Technical Field

[0001] This invention relates to the field of adhesives, and in particular to a modified polysilazane, a two-component silicone sealant resistant to reversion under sealed conditions, and a method for preparing the same. Background Technology

[0002] Condensation-type two-component room temperature vulcanizing (RTV-2) silicone sealant is an elastomer made by mixing hydroxyl-terminated polydimethylsiloxane as the base adhesive with fillers and additives (component A) and a vulcanization system (component B) consisting of crosslinking agents, coupling agents, catalysts, and additives, in a specific ratio. Two-component silicone sealant offers advantages such as resistance to high and low temperatures, weathering resistance, electrical insulation, non-toxicity, and physiological inertness, and is widely used in building curtain walls, energy-saving doors and windows, and insulated glass.

[0003] Currently, traditional two-component silicone sealants, when used under long-term fully enclosed conditions, are prone to chain structure breakage and degradation under the action of residual catalysts, exhibiting a "reversion" phenomenon, especially under fully enclosed and high-temperature conditions. This "reversion" phenomenon leads to a decrease in the hardness of the cured two-component silicone sealant, and its mechanical properties and tensile adhesion are also significantly adversely affected; this limits the application of two-component silicone sealants in specific scenarios. Therefore, improving the "reversion resistance" performance of two-component silicone sealants under fully enclosed conditions has certain application value.

[0004] CN115678494A synthesized a high-temperature resistant silicone sealant using alkoxy-terminated 107 adhesive, reinforcing filler, nano-cerium oxide, iron oxide, titanium dioxide-modified polymethylsiloxane, crosslinking agent, chain extender, tackifier, and catalyst. Its main improvement in temperature resistance comes from the addition of metal oxides. However, this method is costly, and the oxides are difficult to disperse, resulting in a relatively minor improvement.

[0005] CN115926623A describes a high-temperature resistant insulating varnish prepared using polysilazane, a curing agent, inorganic fillers, solvents, and additives. This varnish exhibits high temperature resistance, moisture resistance, and good flexibility. However, it requires a large amount of polysilazane to achieve this effect, resulting in high costs, a strong ammonia odor, and a significantly reduced curing rate if added to a two-component silicone sealant system.

[0006] Therefore, in view of the shortcomings of existing two-component silicone sealants, a method is provided that, while meeting the performance requirements of existing two-component silicone sealants, significantly slows down the reversion phenomenon, thus possessing certain practicality and economic benefits. Summary of the Invention

[0007] To overcome the above problems, this invention prepares a vinyl-containing modified polysilazane with a branched structure in the polysilazane molecular chain by nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane and ethylenediamine. Adding it to a two-component silicone sealant can effectively improve the "reversion resistance" of the two-component silicone sealant.

[0008] The modified polysilazane of the present invention includes the following technical solutions.

[0009] A modified polysilazane is prepared by a nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane and ethylenediamine.

[0010] In some embodiments, the volume ratio of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine is 1-2:1:2-3.

[0011] In some embodiments, the volume ratio of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine is 1.4:1:2.4.

[0012] The present invention also provides a method for preparing the modified polysilazane, comprising the following technical solutions.

[0013] A method for preparing modified polysilazane includes the following steps:

[0014] The dimethyldichlorosilane and vinyltrichlorosilane are dissolved in a solvent, and an ethylenediamine solution is added dropwise at a temperature of -20°C to -30°C. After the addition is complete, the mixture is stirred at a temperature of -5°C to 5°C for 8-10 hours to remove the precipitate and solvent, thereby obtaining the modified polysilazane.

[0015] In some of these embodiments, the solvent is tetrahydrofuran.

[0016] In some embodiments, vinyltrichlorosilane is dissolved in the solvent at a volume ratio of 1:18-22.

[0017] In some embodiments, the solvent in the ethylenediamine solution is tetrahydrofuran.

[0018] In some embodiments, the volume ratio of ethylenediamine to solvent in the ethylenediamine solution is 1:3-5.

[0019] The present invention also provides a two-component silicone sealant, the raw materials of which contain the modified polysilazane.

[0020] In some embodiments, the two-component silicone sealant comprises component A and component B;

[0021] Component A, by weight, is prepared from raw materials comprising the following components:

[0022] 100 parts of α,ω-dihydroxypolydimethylsiloxane

[0023] 60-150 parts of filler

[0024] 5-25 parts of dimethyl silicone oil;

[0025] Component B, by weight, is prepared from raw materials comprising the following components:

[0026]

[0027] In some embodiments, the modified polysilazane is present in 0.5-6 parts by weight of component A.

[0028] In some embodiments, the modified polysilazane is present in 1-5 parts by weight of component A.

[0029] In some embodiments, the modified polysilazane is present in 3-5 parts by weight of component A.

[0030] In some embodiments, component A is prepared from raw materials comprising the following components, in parts by weight:

[0031] 100 parts of α,ω-dihydroxypolydimethylsiloxane

[0032] 90-110 parts of filler

[0033] 8-12 parts of dimethyl silicone oil;

[0034] Component B, by weight, is prepared from raw materials comprising the following components:

[0035]

[0036] In some embodiments, when used, the mass ratio of component A to component B is 8-12:1.

[0037] In some embodiments, the filler is nano-activated calcium carbonate.

[0038] In some embodiments, the particle size of the nano-activated calcium carbonate is 20 nm to 200 nm.

[0039] In some embodiments, the particle size of the nano-activated calcium carbonate is 50 nm to 80 nm.

[0040] In some embodiments, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 5000 mPa·s to 80000 mPa·s.

[0041] In some embodiments, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 15000 mPa·s to 25000 mPa·s.

[0042] In some embodiments, the viscosity of the dimethyl silicone oil in component A at 25°C is 300 mPa·s to 1000 mPa·s.

[0043] In some embodiments, the viscosity of the dimethyl silicone oil in component A at 25°C is 350 mPa·s to 450 mPa·s.

[0044] In some embodiments, the viscosity of the dimethyl silicone oil in component B at 25°C is 5000 mPa·s to 15000 mPa·s.

[0045] In some embodiments, the viscosity of the dimethyl silicone oil in component B at 25°C is 8000 mPa·s to 12000 mPa·s.

[0046] In some embodiments, the crosslinking agent is selected from one or more combinations of propyltrimethoxysilane, tetraethyl orthosilicate, propyl orthosilicate, polyethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, polymethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane.

[0047] In some embodiments, the crosslinking agent is selected from a combination of polymethyltriethoxysilane and methyltrimethoxysilane in a mass ratio of 1-2:1.

[0048] In some embodiments, the coupling agent is selected from γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, epoxycyclohexylmethyldimethoxysilane, epoxycyclohexylmethyldiethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, and γ-aminopropylmethyldiethoxysilane. One or more combinations of the following: oxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, phenylaminomethyltrimethoxysilane, phenylaminomethyltriethoxysilane, γ-isocyanate-propyltrimethoxysilane, glycidyltrimethoxysilane, divinyltriaminopropyltrimethoxysilane.

[0049] In some embodiments, the coupling agent is selected from a combination of γ-aminopropyltrimethoxysilane and γ-isocyanate-propyltrimethoxysilane in a mass ratio of 1-2:1.

[0050] In some embodiments, the catalyst is selected from one or more combinations of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctanoate, dibutyltin dioctanoate, isopropyl titanate, and n-butyl titanate.

[0051] The present invention also provides a method for preparing the two-component silicone sealant, comprising the following technical solutions:

[0052] A method for preparing the two-component silicone sealant includes the following steps:

[0053] Preparation of component A: The α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler are stirred and mixed at a temperature of 60℃~120℃ for 10min~200min to obtain component A;

[0054] Preparation of Component B: The dimethyl silicone oil and carbon black are stirred and mixed at 80℃~120℃ for 10min~60min, cooled to 30℃~50℃, and then the crosslinking agent, coupling agent, modified polysilazane and catalyst are added. The mixture is stirred under nitrogen protection for 5min~100min to obtain Component B.

[0055] In some embodiments, the method for preparing the two-component silicone sealant includes the following steps:

[0056] Preparation of component A: The α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler are stirred and mixed at a temperature of 80℃~100℃ for 40min~80min to obtain component A;

[0057] Preparation of component B: The dimethyl silicone oil and carbon black are stirred and mixed at a temperature of 80℃~120℃ and under vacuum for 10min~60min. After cooling to 30℃~50℃, the crosslinking agent, coupling agent, modified polysilazane and catalyst are added. The mixture is stirred for 5min~100min under inert gas protection to obtain component B.

[0058] The purpose of this invention is to develop a high-performance two-component silicone sealant suitable for applications in sealed environments, including specialized buildings, automobiles, and electronics. Based on this objective, this invention utilizes a nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine to prepare a vinyl-containing modified polysilazane with branched structures introduced into the polysilazane molecular chain. This polymer removes residual silanol groups and adsorbed water from the two-component silicone sealant, thereby eliminating the main chain degradation they induce and resulting in excellent heat resistance and resistance to sealed degradation. Therefore, adding it to a two-component silicone sealant can effectively improve its reversion resistance. Based on this, the modified polysilazane, two-component silicone sealant, and their preparation method provided by this invention have the following beneficial effects:

[0059] 1. The two-component silicone sealant prepared using the vinyl-containing modified polysilazane of the present invention can significantly improve the hardness of the two-component silicone sealant under sealed conditions, without adversely affecting its curing performance and performance, and requires a small amount to be added, making it highly practical.

[0060] 2. The two-component silicone sealant prepared using the vinyl-containing modified polysilazane of the present invention has a high hardness retention rate under sealed conditions, which can significantly slow down the "reversion" phenomenon of vulcanization. After curing, it can still maintain good mechanical properties and good adhesion properties when placed at a high temperature of 90°C under sealed conditions, and has excellent "reversion resistance" under fully sealed conditions.

[0061] 3. The two-component silicone sealant of the present invention can meet the application requirements of sealants in sealed conditions in many fields such as special buildings, automobiles, and electronic appliances.

[0062] 4. The preparation process of the vinyl-containing modified polysilazane and its two-component silicone sealant of the present invention is simple and highly practical. Detailed Implementation

[0063] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be construed as limiting the invention.

[0064] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0065] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0066] In this invention, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0067] The self-made modified polysilazane used in the following examples was prepared by introducing a branched structure into the polysilazane molecular chain through a nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine. The specific preparation method is as follows:

[0068] 70 mL of dimethyldichlorosilane and 50 mL of vinyltrichlorosilane were dissolved in 1 L of tetrahydrofuran solvent. The mixture was stirred magnetically at medium speed for 10 min to ensure homogeneity. The temperature of the reaction system was lowered to -25 °C using a liquid nitrogen-ethanol system. Separately, 120 mL of ethylenediamine was dissolved in 0.5 L of tetrahydrofuran solvent. The ethylenediamine solution was slowly added dropwise to the reaction system using a constant pressure dropping funnel, maintaining continuous magnetic stirring and the -25 °C temperature. After the ethylenediamine solution was completely added, the reaction was continued at 0 °C for 9 hours with magnetic stirring. After centrifugation and filtration, a colorless and transparent liquid was obtained. The tetrahydrofuran solvent was then removed from the product using a rotary evaporator and a vacuum pump to obtain the modified polysilazane, which was a colorless and transparent liquid with a yield of 75%. The synthesis principle is as follows:

[0069]

[0070] Infrared spectroscopy analysis of the synthesized product revealed a value of 3390 cm⁻¹. -1 There is a stretching vibration peak of NH bond at 2957 cm⁻¹. -1 2896cm -1 A stretching vibration peak of CH3 is present at 1255 cm⁻¹. -1 There is a stretching vibration peak of Si-CH3 at 1150 cm⁻¹. -1 An absorption peak for Si-N-Si is present at 775 cm⁻¹. -1 and 902cm -1 The presence of Si-N stretching vibration peaks indicates the successful synthesis of the modified polysilazane. The presence of both Si-N-Si and NH structures confirms the successful synthesis of the modified polysilazane.

[0071] The following are specific embodiments. In the following embodiments, unless otherwise specified, "parts" refers to parts by weight; unless otherwise specified, "viscosity" refers to viscosity at 25°C.

[0072] Example 1

[0073] This embodiment provides a two-component silicone sealant that is resistant to reversion under sealed conditions, consisting of component A and component B.

[0074] The preparation method of component A is as follows:

[0075] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0076] The preparation method of component B is as follows:

[0077] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 minutes to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane, 0.5 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 minutes under nitrogen protection to obtain component B.

[0078] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0079] Example 2

[0080] This embodiment provides a two-component silicone sealant that is resistant to reversion under sealed conditions, consisting of component A and component B.

[0081] The preparation method of component A is as follows:

[0082] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0083] The preparation method of component B is as follows:

[0084] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane, 3 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0085] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0086] Example 3:

[0087] This embodiment provides a two-component silicone sealant that is resistant to reversion under sealed conditions, consisting of component A and component B.

[0088] The preparation method of component A is as follows:

[0089] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0090] The preparation method of component B is as follows:

[0091] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane, 5 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0092] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0093] Example 4

[0094] This embodiment provides a two-component silicone sealant that is resistant to reversion under sealed conditions, consisting of component A and component B.

[0095] The preparation method of component A is as follows:

[0096] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0097] The preparation method of component B is as follows:

[0098] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane, 30 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0099] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0100] Example 5

[0101] This comparative example provides a two-component silicone sealant, consisting of component A and component B.

[0102] The preparation method of component A is as follows:

[0103] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0104] The preparation method of component B is as follows:

[0105] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 minutes to obtain the color paste for component B. After the temperature was cooled to 40℃, 50 parts of propyltrimethoxysilane, 50 parts of 3-isocyanate-propyltrimethoxysilane, 3 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 minutes under nitrogen protection to obtain component B.

[0106] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0107] Example 6:

[0108] This comparative example provides a two-component silicone sealant, consisting of component A and component B.

[0109] The preparation method of component A is as follows:

[0110] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 5000 mPa·s and 8 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 60 parts of nano-active calcium carbonate with a particle size of 20 nm during the stirring process so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0111] Component B (weight fraction):

[0112] The preparation method of component B is as follows:

[0113] 100 parts of dimethyl silicone oil with a viscosity of 5000 mPa·s and 50 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 10 parts of polymethyltriethoxysilane, 5 parts of methyltrimethoxysilane, 10 parts of γ-aminopropyltrimethoxysilane, 5 parts of γ-isocyanate-propyltrimethoxysilane, 3 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0114] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0115] Example 7:

[0116] This comparative example provides a two-component silicone sealant, consisting of component A and component B.

[0117] The preparation method of component A is as follows:

[0118] 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 80000 mPa·s and 12 parts of dimethyl silicone oil with a viscosity of 400 mPa·s were added to a kneader and stirred and dispersed. After 5 minutes of stirring, 100 parts of nano-active calcium carbonate with a particle size of 200 nm were added to completely cover the powder to form a self-leveling base material. The reaction temperature was controlled at 90℃ and stirred and mixed for 1 hour to obtain component A, which was then ground and set aside for later use.

[0119] The preparation method of component B is as follows:

[0120] 100 parts of dimethyl silicone oil with a viscosity of 15000 mPa·s and 150 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 30 parts of polymethyltriethoxysilane, 30 parts of methyltrimethoxysilane, 30 parts of γ-aminopropyltrimethoxysilane, 30 parts of γ-isocyanate-propyltrimethoxysilane, 3 parts of self-made modified polysilazane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0121] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0122] Comparative Example 1

[0123] This comparative example provides a two-component silicone sealant, consisting of component A and component B.

[0124] The preparation method of component A is as follows:

[0125] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0126] The preparation method of component B is as follows:

[0127] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane, 3 parts of polysilazane (methylpolysilazane TC-PO5) and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0128] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0129] Comparative Example 2

[0130] This comparative example provides a two-component silicone sealant, consisting of component A and component B.

[0131] The preparation method of component A is as follows:

[0132] Take 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 20000 mPa·s and 10 parts of dimethyl silicone oil with a viscosity of 400 mPa·s, add them to a kneader, stir and disperse. After 5 minutes, add 100 parts of nano-active calcium carbonate with a particle size of 60 nm during stirring so that the adhesive completely covers the powder to form a self-leveling base material. Control the reaction temperature at 90℃ and stir and mix for 1 hour to obtain component A, which is then ground and set aside.

[0133] The preparation method of component B is as follows:

[0134] 100 parts of dimethyl silicone oil with a viscosity of 10000 mPa·s and 100 parts of carbon black were added to a planetary mixer and stirred under vacuum at -0.09 MPa. The mixture was kept at 100℃ for 30 min to obtain the color paste for component B. After the temperature was cooled to 40℃, 25 parts of polymethyltriethoxysilane, 25 parts of methyltrimethoxysilane, 25 parts of γ-aminopropyltrimethoxysilane, 25 parts of γ-isocyanate-propyltrimethoxysilane and 1 part of dibutyltin dilaurate were added. The mixture was stirred for 10 min under nitrogen protection to obtain component B.

[0135] Next, mix components A and B in a planetary mixer under vacuum at a volume ratio of 10:1, and then prepare and test the samples as required.

[0136] The following performance tests were conducted on the two-component silicone sealants prepared in Examples 1-7 and Comparative Examples 1-2:

[0137] Tensile strength: The specimens were tested using a universal tensile testing machine. The prepared specimens were first cured for 28 days at (23±2)℃ and (50±5)% relative humidity. Tensile adhesion was tested according to GB / T13477.8-2017, and the average tensile strength was recorded and reported. Tensile adhesion test after 90℃ sealed treatment: The cured specimens were treated under sealed conditions at 90℃ for 24 hours, and then tested at 90℃ according to 6.8.5 of GB16776-2005.

[0138] Sealing Hardness Test: Under standard test conditions, take 60-80 ml of the mixed two-component silicone sealant and fill it into 100 ml bottles, ensuring they are completely filled and free of air bubbles. Seal the bottles with the bottom caps to ensure a tight seal and prevent air contact. Cure the samples under standard conditions for the required number of days. After curing, cut circular pieces of 6-10 mm thick sealant from both the top and bottom of the bottles. Test the hardness of the middle portion using a Shore A hardness tester according to GB / T 531.1-2008, and record the hardness range.

[0139] Tensile breaking time determination: Tested in accordance with Appendix D.5 of GB16776-2005.

[0140] Surface drying time: Tested according to GB / T 13477.5-2003.

[0141] During the user's construction process, the tensile strength and surface drying time can represent the workability of the two-component silicone sealant. A reasonable workability time is helpful for its construction.

[0142] Table 1. Test results of tensile time and surface drying time of two-component silicone sealant under standard conditions.

[0143]

[0144]

[0145] Comparing the experimental results in Table 1, the following conclusions can be drawn: Adding modified polysilazane slightly increases the tensile strength and surface drying time of the resulting two-component silicone sealant. Adding excessive amounts of modified polysilazane significantly increases both the tensile strength and surface drying time, which is detrimental to customer use. When a higher viscosity α,ω-dihydroxypolydimethylsiloxane is selected as the base adhesive, its tensile strength and surface drying time are shortened.

[0146] Table 2. Tensile adhesion test results of two-component silicone sealant

[0147]

[0148] *CF represents cohesive failure, AF represents bond failure.

[0149] Comparing the experimental results in Table 2, the following conclusions can be drawn: Comparing Example 2 with Examples 1-3 shows that adding modified polysilazane can improve the high-temperature mechanical properties of the resulting silicone sealant. Comparing Examples 2 with Examples 5-7 shows that the combination of various crosslinking agents and coupling agents can improve adhesion to the substrate; however, when α,ω-dihydroxypolydimethylsiloxane with excessively high viscosity is selected as the base adhesive, its adhesion will be affected to some extent. Comparing Examples 1-4 shows that the modified polysilazane prepared in this invention achieves optimal results when used in the current system at a dosage of 3 parts. Comparing Examples 1 and 4 shows that although the mechanical properties remain good after adding excessive amounts of modified polysilazane, it will negatively impact the adhesion of the silicone sealant to the substrate.

[0150] Table 3. Sealing hardness test results of two-component silicone sealant after different storage days under standard conditions.

[0151] Example 3 days 14 days 30 days 180 days Example 1 26 23 20 15 Example 2 27 25 23 19 Example 3 27 26 23 20 Example 4 26 25 24 22 Example 5 26 23 21 18 Example 6 23 19 17 15 Example 7 28 23 19 15 Comparative Example 1 25 19 14 9 Comparative Example 2 24 19 11 5

[0152] Table 4. Results of airtightness test of two-component silicone sealant after storage in a 90℃ oven for different numbers of days.

[0153]

[0154]

[0155] Comparing the experimental results in Table 4, the following conclusions can be drawn: Comparing Examples 2 and 5, it can be seen that the compound crosslinking agent and coupling agent have less impact on the hardness of the two-component silicone sealant compared to the single crosslinking agent and coupling agent. Comparing Comparative Examples 6 and 7, it can be seen that the two-component silicone sealant with a higher filler content has higher hardness. By comparing Comparative Examples 2 and Examples 1-4, it can be seen that adding modified polysilazane can slow down the "reversion" phenomenon of vulcanization. When the amount added exceeds 3 parts, the change in sealing hardness is not significant.

[0156] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0157] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A two-component silicone sealant, characterized in that, The two-component silicone sealant includes component A and component B; Component A, by weight, is prepared from raw materials comprising the following components: 100 parts of α,ω-dihydroxypolydimethylsiloxane 60-150 parts of filler 5-25 parts of dimethyl silicone oil; Component B, by weight, is prepared from raw materials comprising the following components: 100 parts of dimethyl silicone oil 50-150 parts carbon black 15-60 parts of crosslinking agent 15-60 parts of coupling agent Modified polysilazane 0.5~20 parts Catalyst 0.1~1.5 parts; The modified polysilazane is prepared by a nucleophilic substitution reaction of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine; the volume ratio of dimethyldichlorosilane, vinyltrichlorosilane, and ethylenediamine is 1-2:1:2-3; the preparation method of the modified polysilazane includes the following steps: The dimethyldichlorosilane and vinyltrichlorosilane are dissolved in a solvent, and an ethylenediamine solution is added dropwise at a temperature of -20°C to -30°C. After the addition is complete, the mixture is stirred at a temperature of -5°C to 5°C for 8-10 hours to remove the precipitate and solvent, thereby obtaining the modified polysilazane.

2. The two-component silicone sealant according to claim 1, characterized in that, The solvent is tetrahydrofuran; and / or, It is dissolved in the solvent at a volume ratio of vinyltrichlorosilane to solvent of 1:18-22; and / or, The solvent in the ethylenediamine solution is tetrahydrofuran; and / or, The volume ratio of ethylenediamine to solvent in the ethylenediamine solution is 1:3-5.

3. The two-component silicone sealant according to claim 1, characterized in that, The modified polysilazane is present in 0.5-6 parts by weight in component B.

4. The two-component silicone sealant according to claim 3, characterized in that, The modified polysilazane is present in 1-5 parts by weight in component B.

5. The two-component silicone sealant according to claim 4, characterized in that, The modified polysilazane is present in 3-5 parts by weight in component B.

6. The two-component silicone sealant according to claim 1, characterized in that, Component A is prepared from raw materials comprising the following components: 100 parts of α,ω-dihydroxypolydimethylsiloxane 90-110 parts of filler 8-12 parts of dimethyl silicone oil; Component B, by weight, is prepared from raw materials comprising the following components: 100 parts of dimethyl silicone oil 90-110 parts carbon black 45-55 parts of crosslinking agent 45-55 parts of coupling agent 1-5 parts of the modified polysilazane Catalyst 0.8~1.2 parts.

7. The two-component silicone sealant according to any one of claims 1-6, characterized in that, When used, the mixing mass ratio of component A and component B is 8-12:1; and / or, The filler is nano-activated calcium carbonate; and / or, The α,ω-dihydroxypolydimethylsiloxane has a viscosity of 5000 mPa·s to 80000 mPa·s at 25°C; and / or, The dimethyl silicone oil in component A has a viscosity of 300 mPa·s to 1000 mPa·s at 25°C; and / or, The dimethyl silicone oil in component B has a viscosity of 5000 mPa·s to 15000 mPa·s at 25°C; and / or, The crosslinking agent is selected from one or more combinations of propyltrimethoxysilane, tetraethyl orthosilicate, propyl orthosilicate, polyethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, polymethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane; and / or, The coupling agent is selected from γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, epoxycyclohexylmethyldimethoxysilane, epoxycyclohexylmethyldiethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N- One or more combinations of (2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, phenylaminomethyltrimethoxysilane, phenylaminomethyltriethoxysilane, γ-isocyanate-propyltrimethoxysilane, glycidyltrimethoxysilane, and divinyltriaminopropyltrimethoxysilane; and / or, The catalyst is selected from one or more combinations of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctanoate, isopropyl titanate, and n-butyl titanate.

8. The two-component silicone sealant according to claim 7, characterized in that, The particle size of the nano-active calcium carbonate is 20nm~200nm.

9. The two-component silicone sealant according to claim 7, characterized in that, The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 15000 mPa·s to 25000 mPa·s.

10. The two-component silicone sealant according to claim 7, characterized in that, The crosslinking agent is selected from a combination of polymethyltriethoxysilane and methyltrimethoxysilane in a mass ratio of 1-2:

1.

11. The two-component silicone sealant according to claim 7, characterized in that, The coupling agent is selected from a combination of γ-aminopropyltrimethoxysilane and γ-isocyanate-propyltrimethoxysilane in a mass ratio of 1-2:

1.

12. A method for preparing a two-component silicone sealant according to any one of claims 1-11, characterized in that, Includes the following steps: Preparation of component A: The α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil and filler are stirred and mixed at a temperature of 60℃~120℃ for 10min~200min to obtain component A; Preparation of component B: The dimethyl silicone oil and carbon black are stirred and mixed at a temperature of 80℃~120℃ and under vacuum for 10min~60min. After cooling to 30℃~50℃, the crosslinking agent, coupling agent, modified polysilazane and catalyst are added. The mixture is stirred for 5min~100min under inert gas protection to obtain component B.

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