Low-haze yellowing-resistant transparent ms sealant and preparation method thereof

Abstract

The present application relates to a kind of low haze yellowing-resistant transparent MS sealant and its preparation method.The sealant includes silane end-capped polyether, basic organic sol and zinc catalytic organic sol made by the same basic surface modification sol stream, moisture scavenger, photothermal stabilizer, epoxy alkoxysilane adhesion promoter and zinc catalytic component.After colloidal silica is treated by hydroxyl polyether silane in wet state, polyether carrier replacement is carried out without solid-liquid separation and powder drying;Basic branch further introduces alkoxysilane unit, and zinc carboxylate is added according to measured equivalent after acetoacetate of catalytic branch is esterified.The preparation path can reduce large particle size scattering center, reduce the specified condition extractable proportion of zinc component, and consider transparency, yellowing resistance, storage stability and moisture curing performance.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology, specifically a low-haze, yellowing-resistant transparent MS sealant and its preparation method. Background Technology

[0002] Silane-modified polyether sealant, also known as MS sealant, typically uses polyether as the main chain and hydrolyzable alkoxysilane groups as end groups. After application, these end groups undergo hydrolysis and condensation under the influence of ambient moisture, forming a siloxane cross-linked structure. Therefore, it possesses good flexibility, adhesion, weather resistance, and paintability. When transparent MS sealant is used for glass joints, bonding of transparent components, and interior decoration, in addition to requiring high light transmittance, it is also necessary to reduce light scattering caused by internal particle aggregates, microgels, and phase separation regions. Total light transmittance and haze reflect different optical properties; even if a material has high total light transmittance, it may still appear cloudy due to numerous scattering centers. Therefore, controlling the initial haze and yellowing after photothermal aging of the sealant while obtaining the necessary reinforcing, thixotropic, and curing properties is a fundamental technical problem that transparent MS sealant needs to solve.

[0003] To address the aforementioned issues, existing technologies have proposed several effective improvement solutions. For example, CN109096974B uses liquid polyether-modified alkoxy MQ resin as a reinforcing component, leveraging its good compatibility with silane-modified polyether to reduce the impact of inorganic powder reinforcement on transparency; CN108504318B uses silica, UV absorber, light stabilizer, adhesion promoter, and catalyst to construct a transparent reinforcement and weather-resistant system; CN115362203B introduces a sterically hindered amine light stabilizer and a silicon compound containing conjugated carbon-carbon double bonds into a moisture-curing composition containing alkoxysilane to reduce yellowing after UV irradiation; CN118956318A further employs reactive plasticizers, modified silica, liquid UV absorber, and organic bismuth catalysts to balance light transmittance, adhesion, and yellowing resistance, wherein the modified silica is surface-treated, centrifuged, and vacuum-dried before being added to the sealant. The aforementioned technologies have been able to improve the overall performance of transparent MS sealants by enhancing material compatibility, light-stabilized systems, and organotin-free catalytic systems.

[0004] However, in existing technologies, the reinforcing phase, photostable system, and catalytic system are typically added as independent components. For schemes using fumed silica or modified silica that has been separated, dried, and redispersed, the material state changes mean that dried particles may leave behind aggregates that are difficult to completely depolymerize during subsequent mixing. Organobismuth or organozinc catalysts, directly dispersed in the polyether continuous phase, may also experience localized concentration differences or migration. Some existing processes require base material treatment and catalytic reactions to be completed at 80–120°C or even under staged heating conditions, increasing the thermal history of the polyether resin, stabilizer, and catalytic components. Therefore, existing technologies have not fully solved the problems of simultaneously avoiding silica powder redispersibility, maintaining stable dispersion of the nano-reinforcing phase, controlling the free distribution of the zinc catalytic component, and considering low haze, yellowing resistance, storage stability, and moisture-curing activity without relying on coloring pigments or other inorganic fillers. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a low-haze, yellowing-resistant transparent MS sealant and its preparation method. The main problem is that in existing transparent MS sealants, silica, after separation and drying, is easily redispersed to form large-diameter scattering centers, and free zinc catalytic components and long heat treatment processes can easily cause changes in storage performance and overall color. Therefore, it is difficult to simultaneously achieve low haze, yellowing resistance, storage stability, and moisture curing activity.

[0006] According to one aspect of the present invention, a low-haze, yellowing-resistant, transparent MS sealant is provided, comprising, by weight, 100 parts of silane-terminated polyether, 10-30 parts of silica-polyether organic sol, 0.8-2.5 parts of moisture scavenger, 0.3-1.2 parts of photothermal stabilizer, 0.5-1.5 parts of epoxy-alkoxysilane adhesive accelerator, and 0.005-0.030 parts of zinc catalyst; the sealant contains no other inorganic fillers except colloidal silica, and contains no coloring pigments or dyes.

[0007] The silica-polyether organosol is composed of a base organosol and a zinc-catalyzed organosol. The ratio of the base organosol to the zinc-catalyzed organosol is 70:30 to 85:15 based on the mass of silica contained in both. Both are prepared separately from the same base surface-modified sol after separation. The basic surface-modified sol is obtained by wet hydrolysis and condensation treatment of ammonium-type aqueous colloidal silica and hydroxyl polyether silane in an aqueous alcohol medium; the basic organosol is prepared by reacting one of the basic surface-modified sols after splitting with polyoxypropylene dialkyl ether to replace the aqueous alcohol medium under conditions without solid-liquid separation and powder drying, and then reacting with 3-isocyanate-propyltrialkoxysilane; the zinc-catalyzed organosol is prepared by replacing the aqueous alcohol medium with monohydroxyl polyoxypropylene ether to replace the aqueous alcohol medium under conditions without solid-liquid separation and powder drying, and then reacting with tert-butyl acetoacetate for transesterification, and then mixing with zinc carboxylate, wherein the zinc catalytic component is introduced by the zinc-catalyzed organosol.

[0008] Preferably, the hydroxyl polyether silane is prepared by hydrosilylation reaction of a linear polyoxypropylene ether having an allyl group at one end and a hydroxyl group at the other end, with a number-average molecular weight of 500-1600 calculated by hydroxyl value, with a trimethoxysilane or triethoxysilane; the molar ratio of silane-hydrogen bonds to allyl groups is 1.00:1 to 1.05:1, and the residual allyl content of the obtained hydroxyl polyether silane is not higher than 0.05 mmol / g. When preparing the base surface-modified sol, the molar amount of trialkoxysilane groups contained in the hydroxyl polyether silane, based on the BET specific surface area of ​​colloidal silica, is 0.20-0.80 μmol / m². 2 .

[0009] Preferably, the polyoxypropylene dialkyl ether is a linear polyoxypropylene ether with both ends capped by methyl ether, a number-average molecular weight of 600-1500 as determined by gel permeation chromatography, and a hydroxyl value not exceeding 3 mg KOH / g. When preparing the basic organosol, based on the measured hydroxyl value of the material after carrier replacement, the molar ratio of isocyanate groups to hydroxyl groups in 3-isocyanate-propyltrialkoxysilane is 0.45:1 to 0.75:1, and the reaction is carried out at 50-60°C until the mass fraction of isocyanate groups is not higher than 0.05%; the 3-isocyanate-propyltrialkoxysilane is 3-isocyanate-propyltrimethoxysilane or 3-isocyanate-propyltriethoxysilane.

[0010] Preferably, one end of the monohydroxy polyoxypropylene ether is a methoxy or n-butoxy terminal group, and the number-average molecular weight calculated based on the hydroxyl value is 1000-1500. When preparing the zinc-catalyzed organosol, based on the measured hydroxyl value of the material after carrier replacement, the molar ratio of tert-butyl acetoacetate to hydroxyl groups is 0.30:1 to 0.65:1. An ester exchange reaction is carried out at 90-105°C to remove tert-butanol and unreacted tert-butyl acetoacetate until the residual amount of tert-butyl acetoacetate is no higher than 0.15% and the residual amount of tert-butanol is no higher than 0.10%. Based on the acetoacetate group equivalent measured by quantitative nuclear magnetic resonance of the material before the addition of zinc carboxylate, the molar ratio of acetoacetate groups to zinc element is 2.5:1 to 4.0:1. The zinc carboxylate is one or both of zinc 2-ethylhexanoate and zinc neodecanoate. After adding the zinc carboxylate, the mixture is stirred at 65-80°C for 1.5-3 hours.

[0011] Preferably, the primary particle size of the colloidal silica is 10-25 nm; the silica solid content in both the basic organosol and the zinc-catalyzed organosol is 20-40%, the silica aggregate particle size D90 is 50-150 nm, the water content is not higher than 200 ppm, and the total residual amount of C1-C3 monohydric alcohols is not higher than 0.10%; based on 100 parts of silane-terminated polyether, the total amount of silica introduced by the two organosols is 4-8 parts.

[0012] Preferably, the silane-terminated polyether is composed of 25-45% α-silane-terminated polyether and 55-75% γ-silane-terminated polyether, the sum of which is 100%; the end structure of the α-silane-terminated polyether includes The number-average molecular weight, as determined by gel permeation chromatography, is 10,000–14,000; the end structure of the γ-silane-terminated polyether includes… The number-average molecular weights determined by gel permeation chromatography were 14,000–18,000; the average silane functionality of both was 1.7–2.0.

[0013] Preferably, the moisture scavenger is one or both of vinyltrimethoxysilane and vinyltriethoxysilane; the photothermal stabilizer is composed of a hydroxyphenyltriazine UV absorber, an N-alkoxy hindered amine light stabilizer, and a phosphite antioxidant in a mass ratio of 1:(0.3-1.0):(0.2-0.8); the epoxyalkoxysilane adhesion promoter is one or both of 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane, and neither the photothermal stabilizer nor the adhesion promoter contains free primary or secondary amines.

[0014] Another aspect of the present invention provides a method for preparing a low-haze, yellowing-resistant transparent MS sealant, comprising the following steps: S1. Adjust the pH of ammonium-type aqueous colloidal silica to 8.5-9.8, add C1-C3 monohydric alcohols, making the monohydric alcohols account for 10-25% of the mass of the aqueous alcohol medium, add hydroxyl polyether silane pre-diluted by the monohydric alcohols at 25-45°C and perform hydrolysis and condensation treatment to obtain the basic surface modified sol.

[0015] S2. The base surface modified sol is divided into a first branch and a second branch according to the mass ratio of silica content of 70:30 to 85:15. The first branch is mixed with pre-dehydrated polyoxypropylene dimethyl ether, and the second branch is mixed with pre-dehydrated monohydroxy polyoxypropylene ether. Water and monohydric alcohol are removed at 45-70℃ and 1-10kPa, respectively. Solid-liquid separation and powder drying of colloidal silica are not performed during the process.

[0016] S3. The carrier substitution material in the first branch is reacted with 3-isocyanate-propyltrialkoxysilane to obtain a basic organosol; the carrier substitution material in the second branch is subjected to transesterification with tert-butyl acetoacetate to remove tert-butanol and unreacted tert-butyl acetoacetate; the acetoacetate ester equivalent of the material before the addition of zinc carboxylate is determined, and zinc carboxylate is added accordingly to obtain a zinc-catalyzed organosol; the zinc-catalyzed organosol is then filtered.

[0017] S4. Mix the dehydrated silane-terminated polyether with the base organic sol, add a portion of the moisture remover and filter. After filtration, add the photothermal stabilizer, epoxy alkoxy silane adhesive promoter and the remaining moisture remover in sequence. Then add the zinc catalyst organic sol at a temperature not exceeding 35°C, vacuum degas and pack in a moisture-proof manner.

[0018] Preferably, in step S1, the total mass of sodium and potassium in the ammonium-type aqueous colloidal silica is no more than 0.05% of the silica mass. Ammonia is used to adjust the pH, and hydroxyl polyether silane is added in a 20-30% alcohol solution over 30-90 minutes. After addition, the reaction proceeds for 1-3 hours. In step S2, the two polyether carriers are pre-dehydrated to a water content no higher than 150 ppm. A thin-film devolatilization device with a rotor speed of 300-500 r / min is used, achieving an effective evaporation area of ​​30-80 kg / (m²). 2 The material processing load of h) removes water and monohydric alcohol. The average residence time of the material each time it passes through the membrane devolatilization equipment is 1 to 5 minutes. The material passes through 1 to 3 times until the water content of the carrier replacement material in both branches is not higher than 200 ppm and the total amount of residual monohydric alcohol is not higher than 0.10%.

[0019] Preferably, in step S3, the first branch adds 3-isocyanate-propyltrialkoxysilane at 50–60°C and reacts until the mass fraction of isocyanate groups is not higher than 0.05%; the second branch adds tert-butyl acetoacetate at 90–105°C, reacts for 3–6 hours, and removes tert-butanol and unreacted tert-butyl acetoacetate under reduced pressure until the residual amount of tert-butyl acetoacetate is not higher than 0.15% and the residual amount of tert-butanol is not higher than 0.10%. After cooling to 65–80°C, zinc is added. The measured molar ratio of acetoacetate groups to zinc element in the pre-carboxylate material is 2.5:1 to 4.0:1. Zinc carboxylate is added and mixed for 1.5 to 3 hours. The resulting zinc-catalyzed organic sol is filtered through a filter unit with a nominal precision of 2 to 10 μm. The basic mixture is filtered through a filter unit with a nominal precision of 5 to 20 μm. Each filter unit has a rejection rate of not less than 99.9% for particles not smaller than its nominal particle size. Finally, vacuum degassing is performed until the moisture content of the sealant is not higher than 500 ppm.

[0020] The beneficial effects of this invention are as follows: 1. This invention enables colloidal silica to undergo hydroxyl polyether silane treatment in a wet state, and directly replaces the water-alcohol medium with a polyether carrier without solid-liquid separation and powder drying. This reduces the formation of difficult-to-dissolve particles during the drying process and the large-diameter scattering centers generated during redispersion. While introducing a silica reinforcing phase, it is beneficial to maintain high total transmittance and low haze.

[0021] 2. In this invention, the same base surface modified sol is divided into a base branch and a zinc catalytic branch. The base branch reacts further with isocyanate-based alkoxysilanes under low moisture conditions, so that the base organic sol has both polyether compatibility and alkoxysilane units that can participate in moisture curing. This helps to maintain the surface drying speed and curing depth of the sealant while inhibiting particle aggregation.

[0022] 3. In this invention, the monohydroxy polyoxypropylene ether is first esterified with acetoacetate in the zinc catalytic branch, and then premixed with zinc carboxylate according to the measured acetoacetate ester equivalent. The zinc catalytic component is then carried into the sealant by the zinc catalytic organosol. Compared with directly adding zinc carboxylate to the polyether continuous phase, this method is beneficial to reduce the extractable proportion of zinc component under specified conditions and reduce the change in curing activity before and after storage.

[0023] 4. The present invention employs a process of separate dehydration in two branches, separate filtration of zinc catalytic organic sol, filtration after adding a portion of the moisture removal agent to the base mixture before filtration, and addition of zinc catalytic organic sol at the low temperature end. This process can control residual moisture, lower alcohols and coarse particles, and reduce the thermal history experienced by the catalytic components and photothermal stabilizing components, which is beneficial to improving the storage stability of the sealant and the haze retention after aging.

[0024] 5. This invention uses α-silane-terminated polyether and γ-silane-terminated polyether in combination, and uses photothermal stabilizers and epoxy-alkoxysilane adhesive accelerators that do not contain free primary and secondary amines. Under the condition of comprehensive hue correction without the use of coloring pigments and dyes, it is beneficial to balance moisture curing response and photothermal stability, and reduce yellowing and haze increase after xenon lamp aging and thermal aging. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the overall process for preparing the low-haze, yellowing-resistant, transparent MS sealant of the present invention. Figure 2 This invention provides the preparation route and key reaction formula for the silica-polyether organosol. Figure 3 This is a schematic diagram comparing the material state and light scattering of the route of this invention and the powder redispersibility route. Figure 4 This is a flowchart illustrating the surface modification of the sol-gel flow and the functionalization of the two branches on the same base surface in this invention. Figure 5 This is a schematic diagram illustrating the preparation, filtration, and functional component addition sequence of the transparent MS sealant of the present invention; Figure 6 This is a schematic diagram comparing the light scattering of the non-powdered organic sol system and the powder redispersible system of the present invention; Figure 7 This is a comparison of the initial transparency of the cured specimens from Example 1 and Comparative Example 1. Figure 8 This is a comparison of the appearance of Example 1 and Comparative Example 1 after UV-340 accelerated aging; Figure 9 This is a comparison of the appearance of Example 1 and Comparative Example 1 after long-term outdoor exposure. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0027] Raw material description: Unless otherwise stated, all "parts" mentioned below refer to parts by weight, and all percentages refer to percentages by weight. All raw materials should be sealed and stored before use. Polymers, polyether carriers, and silane raw materials involving moisture curing should be handled under dry nitrogen protection.

[0028] The α-silane-terminated polyether is dimethoxy(methyl)silyl methylcarbamate-terminated polyoxypropylene ether. The batch used in this embodiment, as determined by gel permeation chromatography, has a number-average molecular weight of 11800, a viscosity at 25°C of 10500 mPa·s, an average silane functionality of 1.80, a methoxy content of 0.305 mmol / g, and a silane end-group equivalent of 6.56 kg / eq. The γ-silane-terminated polyether is dimethoxy(methyl)silyl propyl-terminated polyoxypropylene ether. The batch used in this embodiment, as determined by gel permeation chromatography, has a number-average molecular weight of 15800, a viscosity at 25°C of 25000 mPa·s, an average silane functionality of 1.90, a methoxy content of 0.241 mmol / g, and a silane end-group equivalent of 8.32 kg / eq. Both polymers were dehydrated to a water content of no more than 150 ppm under dry nitrogen protection before use. Viscosity at 25℃ was measured using a rotational viscometer at a speed of 10 r / min. The value was read 60 s after the sample was kept at a constant temperature for 30 min.

[0029] Gel permeation chromatography was performed using a gel permeation chromatograph equipped with a differential refractive index detector. The chromatographic column consisted of two mixed-pore-size gel columns connected in series. The mobile phase was anhydrous tetrahydrofuran. The column temperature was 35℃, the flow rate was 1.0 mL / min, and the sample concentration was 2.0 mg / mL. The sample was filtered through a 0.45 μm polytetrafluoroethylene (PTFE) membrane before injection. Calibration was performed using narrow-distribution polystyrene standards, and the obtained molecular weight was a relative number-average molecular weight. The silane terminal equivalent and methoxy content were determined using quantitative proton nuclear magnetic resonance (NMR) and cross-checked with the number-average molecular weight and average functionality.

[0030] Ammonium-type aqueous colloidal silica uses ammonia as a stabilizing base, and the total mass of sodium and potassium is not higher than 0.05% of the mass of silica. Its solid content, primary particle size and BET specific surface area are selected according to each preparation example. The specifications of linear polyoxypropylene ethers, polyoxypropylene dialkyl ethers and monohydroxy polyoxypropylene ethers with an allyl group at one end and a hydroxyl group at the other end are shown in the corresponding preparation examples.

[0031] The purity of trimethoxysilane, triethoxysilane, 3-isocyanopropyltrimethoxysilane, 3-isocyanopropyltriethoxysilane, and tert-butyl acetoacetate is not less than 98%; zinc 2-ethylhexanoate and zinc neodecanoate are both transparent or light-colored liquid products, and their zinc content is calculated based on the measured value by inductively coupled plasma atomic emission spectrometry.

[0032] The hydroxyphenyl triazine UV absorber is a mixture of 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine and 2-[4-[(2-hydroxy-3-tetrazoloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and is prepared into a solution with an active ingredient mass fraction of 85% using 1-methoxy-2-propanol. The dosages in Table 5 are based on the active ingredient. The N-alkoxy hindered amine light stabilizer is bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate. The phosphite antioxidant is tris(2,4-di-tert-butylphenyl) phosphite. The transesterification process aid used in the preparation of zinc-catalyzed organosol is triphenyl phosphite, and its residual amount in the final sealant is included in the total amount of phosphite antioxidants. Before use, the hydroxyphenyltriazine UV absorber solution is treated at 50°C and 5 kPa for 30 min, and its water content is tested to be no higher than 200 ppm.

[0033] The water content of raw materials and intermediates was determined by the Karl Fischer coulometric method; the hydroxyl value was determined by the phthalic anhydride esterification method; the mass fraction of isocyanate groups was determined by the di-n-butylamine back titration method; the residual allyl groups and residual silane bonds were determined by the iodometric method; tert-butyl acetoacetate, tert-butanol and C1-C3 monohydric alcohols were determined by gas chromatography equipped with a flame ionization detector. The stationary phase of the chromatographic column was 6% cyanopropylphenyl-94% dimethylpolysiloxane, the injection port temperature was 220℃, the detector temperature was 250℃, the carrier gas was nitrogen, and the external standard method was used for quantification.

[0034] The acetoacetate equivalent was determined using quantitative proton NMR before the addition of zinc carboxylate: approximately 100 mg of the devolatilized second-branch precursor was weighed, dissolved in deuterated chloroform, and calibrated 1,3,5-trimethoxybenzene was added as an internal standard. The sample was tested on a 400 MHz NMR spectrometer with a 10 s delay and 64 scans. The molar number and equivalent of the acetoacetate group were calculated using the integral of the methylene group of the acetoacetate at δ 3.35–3.55 and the integral of the aromatic hydrogen of the internal standard at δ 6.05–6.15. The calculated results were verified against the difference in hydroxyl values ​​before and after the reaction, combined with the residual amounts of tert-butyl acetoacetate and tert-butanol determined by gas chromatography. The relative deviation between the two methods was no higher than 5%.

[0035]

[0036]

[0037] In the formula, n AA The amount of acetoacetate groups in the sample is expressed in mol. IAA The integral area of ​​the acetoacetate methylene hydrogen at δ 3.35–3.55 is dimensionless; I IS The integral area of ​​the internal standard 1,3,5-trimethoxybenzene aromatic hydrogens at δ 6.05–6.15 is dimensionless; m IS The mass of the internal standard 1,3,5-trimethoxybenzene is expressed in grams. M IS The molar mass of 1,3,5-trimethoxybenzene is expressed in g / mol. m s The mass of the precursor material in the second branch tested is expressed in kg. E AA It represents the acetoacetate ester equivalent, expressed in kg / eq.

[0038] The BET specific surface area of ​​colloidal silica was determined by nitrogen adsorption at 77K, with a silica density of 2.20 g / cm³. 3 Calculate the equivalent primary particle size for spherical shapes using the following formula:

[0039] In the formula, d is the spherical equivalent primary particle size, in meters (m), and the calculated result is converted to nm; ρ is the density of silica, in kg / m³. 3 When substituting into the calculation, use 2.20 g / cm³. 3 Converted to 2.20 × 10 3 kg / m 3 SBET is the specific surface area of ​​BET, in m². 2 / kg, measured values ​​are expressed in m 2 When / g is used, its value is multiplied by 10. 3 Convert to m 2 / kg substitute.

[0040] Zinc content was determined by inductively coupled plasma atomic emission spectrometry; particle size of both organosol and sealant was determined by dynamic light scattering instrument with laser wavelength of 633 nm, backscattering angle of 173°, and measurement temperature of 25.0 ± 0.1 ℃; samples were diluted with anhydrous polyoxypropylene dimethyl ether at a mass ratio of 1:100, allowed to stand for 12 h without ultrasonic treatment, and the apparent intensity distribution D90 obtained according to the prescribed dilution procedure was reported.

[0041] I. Preparation of Hydroxyhydroxy polyether silanes Preparation Example 1: Preparation of Hydroxyhydroxy polyether silane HPS-1 1000g of a linear polyoxypropylene ether having an allyl group at one end and a hydroxyl group at the other end is added to a reactor equipped with a mechanical stirrer, thermometer, nitrogen inlet, condenser, and constant-pressure dropping funnel. The linear polyoxypropylene ether has a number-average molecular weight of 1000 calculated based on the hydroxyl value and an initial water content of 120ppm.

[0042] The mixture was dehydrated at 80℃ and 2kPa for 1 h, and then dry nitrogen was introduced to restore atmospheric pressure. A platinum-divinyltetramethyldisiloxane complex solution with a platinum mass fraction of 2.0% (using xylene as solvent) was added to make the platinum relative to the total mass of the reactants 20 ppm. The system temperature was maintained at 80℃, and 124.6 g of trimethoxysilane was added dropwise over 60 min. The molar ratio of silane-hydrogen bonds in the trimethoxysilane to allyl groups in the linear polyoxypropylene ether was 1.02:1.

[0043] After the addition was complete, the reaction was continued at 80℃ for 3 hours, then cooled to 60℃, and unreacted trimethoxysilane was removed under 2 kPa. 0.10% (by weight) of activated carbon was added, and the mixture was stirred at 60℃ for 30 minutes, then filtered through a 1 μm polytetrafluoroethylene membrane to obtain hydroxyl polyether silane HPS-1. HPS-1 had a residual allyl content of 0.023 mmol / g, a residual silane-hydrogen bond content of 0.006 mmol / g, a hydroxyl value of 49.7 mg KOH / g, a hydroxyl value retention rate of 98.2%, a water content of 93 ppm, and residual platinum as determined by ICP-OES was no higher than 2 mg / kg.

[0044] Preparation Examples 2-3: Preparation of hydroxyl polyether silanes HPS-2 and HPS-3 The operation steps for preparation examples 2 and 3 are the same as those for preparation example 1, except that the specifications of the raw materials and the reaction conditions are set according to Table 1.

[0045] Table 1. Preparation conditions of hydroxyl polyether silanes

[0046] II. Preparation of Silica-Polyether Organosol Preparation routes and key reactions of silica-polyether organosols are as follows: Figure 2 As shown, the process of surface modification of the homologous base, sol-gel diversion, and functionalization of the two branches is as follows: Figure 4 As shown.

[0047] Preparation Example 4: Preparation of Organosol Group M1 1. Preparation of base surface modified sol 1000g of ammonium-type aqueous colloidal silica was added to a reactor equipped with a mechanical stirrer, thermometer, and dropping device. The colloidal silica had a silica solid content of 30.0%, a primary particle size of 15nm, and a BET specific surface area of ​​180m². 2 / g; the total mass fraction of sodium and potassium, based on the mass of silicon dioxide, is 0.018%.

[0048] The pH of the colloidal silica was adjusted to 9.2 using 5% ammonia solution. Surface treatment was performed using a four-bladed 45° angled impeller with a diameter 0.34 times the reactor's inner diameter, and a stirring speed of 350 ± 20 r / min. 81.9 g of 123.5 g of isopropanol was mixed with 27.3 g of HPS-1 obtained in Preparation Example 1 to prepare a 25% solution. The remaining 41.6 g of isopropanol was added to the colloidal silica, making isopropanol 15% of the water-alcohol medium mass. The system temperature was adjusted to 35°C, and the HPS-1 solution was added dropwise over 60 min. After the addition was complete, the reaction continued for 2 h to obtain the basic surface-modified sol. The molar amount of trimethoxysilane groups in HPS-1 was 0.45 μmol / m³. 2 BET specific surface area of ​​colloidal silica.

[0049] 2. Preparation of basic organosol B1 Based on the silica mass ratio of 80:20 in the two materials, the base surface modified sol is divided into the first branch and the second branch.

[0050] Add 534.5g of pre-dehydrated polyoxypropylene dimethyl ether (POD), with a water content of 90ppm, to the first branch. The POD has a number-average molecular weight of 800 and a hydroxyl value of 1.0 mgKOH / g. Feed the resulting material into an evaporation channel with an effective evaporation area of ​​0.10m². 2 A thin-film devolatilization device was used to continuously process the material twice under the conditions of rotor speed 400 r / min, feed rate 6.0 kg / h, 60℃ and 5 kPa, with an average residence time of 3.2 min each time, to remove water and isopropanol. The hydroxyl value of the resulting first branch carrier replacement was 2.4 mg KOH / g.

[0051] 4.2 g of 3-isocyanate-propyltrimethoxysilane was added at a molar ratio of isocyanate groups to hydroxyl groups in the carrier replacement material of 0.60:1, and the mixture was reacted at 55 °C under nitrogen protection for 2 h to obtain the basic organosol B1. The mass fraction of isocyanate groups in B1 was 0.028%.

[0052] 3. Preparation of Zinc-Catalyzed Organosol Z1 134.5 g of a linear polyoxypropylene ether, pre-dehydrated to a water content of 88 ppm with a methoxy ether end group and a hydroxyl group at the other end, was added to the second branch. The linear polyoxypropylene ether had a number-average molecular weight of 1000 based on its hydroxyl value. Water and isopropanol were removed using the same membrane devolatilization conditions as the first branch. The resulting second branch carrier replacement had a hydroxyl value of 39.4 mg KOH / g.

[0053] 7.10 g of tert-butyl acetoacetate was added at a molar ratio of 0.32:1 to the measured hydroxyl groups, and 0.060 g of triphenyl phosphite was added as an aid in the transesterification process.

[0054] The system was heated to 100℃ under nitrogen protection and reacted for 6 hours, while the generated tert-butanol was removed under reduced pressure. Subsequently, the reaction was continued at 100℃ and 2 kPa for 30 minutes to reduce the residual tert-butyl acetoacetate to 0.080% and the residual tert-butanol to 0.040%. The acetoacetate ester equivalent determined by quantitative proton NMR was 4.63 kg / eq, with a relative deviation of 2.4% from the hydroxyl value difference and the gas chromatography material balance result.

[0055] The system was cooled to 70℃, and 3.95g of zinc 2-ethylhexanoate with a measured zinc content of 18.5% was added within 20 minutes. After the addition was complete, mixing continued for 2 hours. Based on the measured acetoacetate group equivalent, the molar ratio of acetoacetate groups to zinc was 4.0:1. The resulting material was passed through a filtration unit with a nominal precision of 5μm and a rejection rate of not less than 99.9% for particles with a diameter not less than 5μm to obtain zinc-catalyzed organosol Z1.

[0056] Preparation Examples 5-7: Preparation of Organosol Groups M2-M4 Preparation Examples 5-7 prepared organosol groups M2-M4, using the same reactor, feeding sequence, and branch processing logic as Preparation Example 4. The surface treatment stage used a four-bladed 45° angled impeller with a diameter 0.34 times the reactor's inner diameter and a stirring speed of 350±20 r / min. The monohydric alcohol amounts listed in Table 2 are total amounts, a portion of which was used to prepare a 25% solution of hydroxyl polyether silane, and the remaining portion was pre-added with colloidal silica before being added dropwise to the solution. The complete feed amounts, reaction conditions, carrier replacement endpoint, and zinc addition criteria for M2-M4 are shown in Table 2 and do not require further deduction by those skilled in the art.

[0057] Thin-film devolatilization was performed using an effective evaporation area of ​​0.10 m². 2 An experimental scraped-film evaporator was used. The rotor speeds of M2, M3, and M4 were 350 r / min, 450 r / min, and 400 r / min, respectively, and the feed rates were 3.0 kg / h, 8.0 kg / h, and 5.0 kg / h, respectively. M2 was treated three times with an average residence time of 4.8 min each time, M3 was treated once with an average residence time of 1.6 min, and M4 was treated twice with an average residence time of 3.8 min each time. For each branch, the devolatilization endpoint was defined as the simultaneous attainment of the effluent moisture content, residual lower alcohol content, and D90 within the ranges listed in Tables 3 and 4.

[0058] Table 2 Preparation parameters of organosol groups M1 to M4

[0059] Table 3. Detection results of basic organic sols

[0060] Table 4. Detection results of zinc-catalyzed organosols

[0061] III. Preparation of Low-Haze, Yellowing-Resistant, Transparent MS Sealant The filtration and functional component addition sequence of transparent MS sealant are as follows: Figure 5 As shown.

[0062] Example 1: Weigh each component according to the formula shown in Table 5.

[0063] 35 parts of α-silane-terminated polyether and 65 parts of γ-silane-terminated polyether were added to a vacuum planetary mixer and dehydrated at 60°C and 3 kPa for 2 hours to reduce the water content of the mixed polymer to 120 ppm.

[0064] Cool the system to 45°C, add 16.00 parts of basic organosol B1, and mix at 300 r / min for 30 min; add 0.75 parts of vinyltrimethoxysilane, and continue mixing for 15 min. Pass the resulting mixture through a filter unit with a nominal precision of 10 μm and a rejection rate of not less than 99.9% for particles with a diameter of not less than 10 μm.

[0065] 0.412 parts of the hydroxyphenyl triazine UV absorber solution (equivalent to 0.35 parts of active ingredient), 0.21 parts of bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and 0.139 parts of tris(2,4-di-tert-butylphenyl) phosphite were pre-dispersed in 5 parts of polymer reserved from the 65 parts of γ-silane-terminated polyether. The mixture was mixed at 60°C until transparent, cooled, and then added to the filtered base mixture. The amount of triphenyl phosphite introduced by Z1 was 0.001 parts, so the total amount of phosphite antioxidant in Example 1 was 0.14 parts.

[0066] Then add 1.00 part of 3-glycidyl etheroxypropyltrimethoxysilane and the remaining 0.75 part of vinyltrimethoxysilane, and mix at 35°C for 20 min.

[0067] The system was cooled to 30°C, and 4.15 parts of zinc-catalyzed organic sol Z1 were added. The mixture was stirred at 300 r / min for 20 min and then vacuum degassed at no more than 3 kPa for 10 min to reduce the moisture content of the sealant to 260 ppm. The sealant was then packed into a moisture-proof packaging tube under dry nitrogen protection.

[0068] In Example 1, the total amount of silicon dioxide introduced by B1 and Z1 was 6.00 parts, and the mass ratio of silicon dioxide introduced by the two was 80:20. The amount of zinc element introduced by Z1 was 0.0146 parts.

[0069] Examples 2-4: Examples 2-4 were prepared according to the method of Example 1, except that the amount of each component and the process parameters were set according to Tables 5 and 6.

[0070] Table 5. Sealant formulations for Examples 1-4

[0071] Table 5 shows the dosage of hydroxyphenyl triazine UV absorbers, calculated by active ingredient, with actual addition amounts of 0.412 parts, 0.235 parts, 0.506 parts, and 0.459 parts for 85% solutions, respectively. Example 2 used 3-glycidyl etheroxypropyltriethoxysilane, Example 3 used both 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane, each at 0.75 parts, and the remaining examples used 3-glycidyl etheroxypropyltrimethoxysilane. The phosphite antioxidants in Table 5 are the sum of the directly added amount of tris(2,4-di-tert-butylphenyl) phosphite and the triphenyl phosphite introduced by the zinc-catalyzed organosol; the actual directly added amounts of tris(2,4-di-tert-butylphenyl) phosphite in Examples 1-4 were 0.139 parts, 0.039 parts, 0.339 parts, and 0.198 parts, respectively.

[0072] Table 6. Sealant preparation parameters for Examples 1-4

[0073] IV. Comparative Example Comparative Example 1: Redispersion of silica powder The difference from Example 1 is that after completing the wet treatment of colloidal silica with HPS-1 according to the method of Preparation Example 4, the polyether carrier replacement was not performed directly. Instead, the surface-treated colloidal silica was centrifuged at 8000 r / min for 20 min, washed twice with isopropanol, dried at 80 °C and 2 kPa for 12 h, and pulverized to obtain modified silica powder. The modified silica powder was divided into two parts according to a silica mass ratio of 80:20, and added to polyoxypropylene dimethyl ether and monohydroxy polyoxypropylene ether respectively. The powders were dispersed at 2000 r / min for 60 min, and then subjected to isocyanate-based silane treatment, acetoacetic acid esterification, and zinc carboxylate mixing according to the conditions of Preparation Example 4. The total amount of silica and zinc element introduced into the two dispersions were the same as in Example 1.

[0074] Comparative Example 2: Zinc carboxylate was directly added to the sealant. The difference from Example 1 is that: the basic organosol B1 and the acetoacetic acid esterified organosol Z1-0 without the addition of zinc 2-ethylhexanoate were prepared according to the method of Preparation Example 4. Based on the measured silica content in Z1-0, 4.07 parts of Z1-0 were added to bring in the same 1.20 parts of silica and the same mass of acetoacetic acid esterified carrier as in Example 1; in the final mixing stage, 0.080 parts of zinc 2-ethylhexanoate were directly added to make the zinc element content 0.0146 parts, and the total mass of Z1-0 and zinc carboxylate was 4.15 parts. Other components and processes were the same as in Example 1.

[0075] Comparative Example 3: Zinc-catalyzed organosol subjected to high-temperature treatment The difference from Example 1 is that Z1 obtained in Preparation Example 4 was placed in a reactor with a reflux condenser and treated at 100°C for 2 hours under dry nitrogen protection, so that the condensate was returned to the reactor and the mass change before and after treatment was controlled within 0.10%; after cooling, it was filtered through a filter unit with a nominal precision of 5 μm. B1, the dehydration method of silane-terminated polyether, the amount of each component, the order of feeding, and the final mixing temperature were all kept the same as in Example 1.

[0076] Comparative Example 4: The basic branch circuit does not undergo isocyanate-based silane post-treatment. The difference from Example 1 is that when preparing the basic organosol according to the method of Preparation Example 4, 3-isocyanate-propyltrimethoxysilane is not added to the first branch carrier replacement material, but is made up with an equal mass of polyoxypropylene dimethyl ether. Other operations are the same as in Example 1.

[0077] V. Test Examples Test Example 1: Particle Dispersion State and Initial Optical Properties The sealant to be tested was diluted with anhydrous polyoxypropylene dimethyl ether at a mass ratio of 1:100, and allowed to stand at 25.0±0.1℃ for 12 hours without ultrasonic treatment. The apparent intensity distribution D90 was measured using a dynamic light scattering instrument, and each sample was measured in triplicate. The number of particles with a diameter of not less than 5μm in the diluted solution was measured using a liquid particle counter, with a sample volume of 10mL and a flow rate of 20mL / min. Each sample was measured in triplicate.

[0078] The sealant was placed between two polished PTFE plates, with the thickness controlled by a PTFE gasket of 1.00±0.05mm. It was cured for 7 days at 23±2℃ and 50±5% relative humidity. A 50mm×50mm bubble-free transparent sheet was then cut. Total transmittance and haze were measured using an integrating sphere transmittance and haze meter according to GB / T2410—2008. Five samples were used in each group, and the results are expressed as mean ± standard deviation. The test results are shown in Table 7.

[0079] For direct visual observation, Example 1 and Comparative Example 1 were respectively applied to and smoothed on transparent test substrates with a 2.0±0.1mm thick limiting frame, and cured for 7 days at 23±2℃ and 50±5% relative humidity. The samples were then photographed under a uniform white background, the same light source, and a direct overhead view. The initial transparency appearance was compared. Figure 7 As shown.

[0080] The material state differences between the route of this invention and the powder redispersibility route are as follows: Figure 3 As shown, the effects of the two systems on light scattering are as follows: Figure 6 As shown.

[0081] Table 7 Particle dispersion state and initial optical properties

[0082] As shown in Table 7, the apparent D90 and the number of particles not less than 5 μm in Examples 1-4 were significantly lower than those in Comparative Example 1, while maintaining high total transmittance and low haze. This indicates that direct replacement of the polyether carrier after wet modification can reduce the coarse scattering centers formed by powder drying and redispersement. Although Example 3 had a lower D90, its silica content was 8 parts, resulting in a higher total volume content of scattering particles. Therefore, its haze was higher than that of Examples 1 and 4. This result is consistent with the principle that particle size and particle volume fraction jointly affect light scattering. Comparative Example 2 only changed the addition state of zinc carboxylate, and the initial optical properties were close to those of Example 1. Comparative Example 3 only required Z1 to undergo an additional thermal history, resulting in an increase in the number of particles and haze, but the change was less than the effect caused by silica powdering.

[0083] Test Example 2: Storage stability, curing performance and extractable zinc ratio The sealant was sealed in an aluminum-plastic composite packaging tube and stored at 50±1℃ for 30 days. Before and after storage, the samples were placed at 25.0±0.2℃ for 24 hours each, and the viscosity was measured using a rotational viscometer at 10 r / min. After the sample was kept at a constant temperature for 30 minutes, the measurement was started, and the value was read at 60 seconds. Each sample was measured in triplicate, and the viscosity change rate was calculated using the following formula:

[0084] Surface drying time was determined according to GB / T13477.5—2002: Under the conditions of 23±2℃ and relative humidity of 50±5%, the sealant was scraped into a layer with a thickness of 2.0±0.1mm. Every 2 minutes, a polyethylene film sheet with a mass of 20g and an area of ​​25mm×25mm was pressed into contact with the adhesive surface for 5s. The surface drying time was recorded when the film no longer adhered to the sealant. Three samples were tested in each group.

[0085] The method for testing the curing depth is as follows: the sealant is filled into a 20mm×20mm×10mm polytetrafluoroethylene mold and cured for 24 hours at 23±2℃ and 50±5% relative humidity. The uncured part is cut along the thickness direction and removed. The distance from the surface of the sealant to the uncured area is measured at three locations and the minimum value is taken. Three samples are tested in each group.

[0086] The extractable zinc ratio was used to characterize the extractability of the zinc component under specified conditions. A 7-day cured sealant sheet was cut into 2mm samples. 1.0000g of the sample was weighed and added to 50.0mL of ethyl acetate. Extraction was carried out in a sealed PTFE-lined container at 50±1℃ and 120r / min for 24h with shaking. The extract was filtered through a 0.45μm PTFE membrane and then acidified with nitric acid. Separately, 0.2000g of the cured sealant was digested in microwave with 6mL of nitric acid and 2mL of hydrogen peroxide. The extracted zinc content and total zinc content were determined by ICP-OES. The standard curve range was 0.05–5.00 mg / L, and the blank recovery rate was 95%–105%. Each sample was tested in triplicate, and the results are expressed as mean ± standard deviation. The test results are shown in Table 8.

[0087] Table 8 Storage stability, curing performance and extractable zinc ratio

[0088] As shown in Table 8, the viscosity change rate, surface drying time change, and curing depth of Examples 1-4 remained within a narrow range after storage at 50°C for 30 days. Comparative Example 2, while maintaining consistent amounts of silica, acetoacetic acid esterification carrier, zinc, and total feed, replaced the zinc carboxylate with direct addition during the final formulation. Under specified conditions, the extractable zinc ratio and storage viscosity change rate significantly increased, indicating that premixing in the catalytic branch can reduce the extractability of the zinc component and minimize changes in catalytic activity during storage. Comparative Example 3 only subjected Z1 to additional high-temperature treatment; its extractable zinc ratio and storage change were higher than in Example 1, but lower than the trend obtained from the original multivariate process. Comparative Example 4 did not undergo post-treatment with isocyanate-based silane in the basic branch, resulting in a prolonged surface drying time and a reduced 24-hour curing depth.

[0089] Test Example 3: Resistance to yellowing and haze retention after aging The sealant was prepared into a curing film with a thickness of 1.00±0.05 mm and cured for 7 days at 23±2℃ and 50±5% relative humidity. The yellow coordinate b* was determined using a spectrophotometer under D65 light source, 10° observation angle, d / 8° geometry, and conditions including specular reflection. The sample backing was the same calibration white plate, and 5 samples were tested in each group.

[0090] Xenon lamp aging was conducted in accordance with GB / T16422.2—2022, using a daylight filter, with an irradiance of 0.51 W / m at 340 nm. 2 The black standard temperature was 63±3℃; each cycle included 102 minutes of light exposure and 18 minutes of light exposure followed by water spraying. During the light exposure phase, the relative humidity inside the chamber was 50±10%. Deionized water with a conductivity not exceeding 5 μS / cm was used for spraying. The cumulative aging time was 500 hours. After aging, b* and haze were measured. Another identical sample was heat-aged in a forced-air oven at 80±2℃ for 168 hours, then placed at 23±2℃ for 24 hours before b* was measured again. Results are expressed as mean ± standard deviation. Δb* and haze increment were calculated using the following formula: As a supplementary visual observation, a cured sample with a thickness of 2.0±0.1mm was placed in a UV-340 fluorescent ultraviolet aging device and aged for 1000 hours at an irradiation temperature of 60±2℃. The sample was then photographed against a uniform white background, using the same light source and from a directly overhead angle. Visual comparisons were then conducted. Figure 8 As shown.

[0091] In addition, Example 1 and Comparative Example 1 were extruded into adhesive strips with a width of 10±1 mm, a height of 3±0.5 mm, and a length of 80±5 mm. These strips were applied to test plates of the same material and cured for 7 days at 23±2℃ and 50±5% relative humidity. The plates were then fixed to an unobstructed exposure rack facing south at 45° and exposed naturally for 12 months. Both groups of samples used the same substrate, orientation, and exposure conditions, and their appearances were compared. Figure 9 As shown. Figure 8 and Figure 9 For supplementary visual observations, they are not included in the quantitative statistics in Table 9.

[0092]

[0093]

[0094] Table 9 Resistance to yellowing and haze retention after aging

[0095] As shown in Table 9, the Δb* and haze increment of Examples 1-4 after xenon lamp aging and thermal aging were relatively low. Comparative Example 1 mainly showed increased haze initially and after aging due to the coarse particles formed after powdering; since high scattering affects the overall hue measurement of transparent samples, its Δb* was only used as an auxiliary result and not solely to prove chemical yellowing. In Comparative Example 2, the direct addition of zinc carboxylate resulted in a higher extractable proportion under specified conditions, accompanied by a greater overall hue change; in Comparative Example 3, only the thermal history of Z1 was increased, and the initial b* and aging increment were higher than in Example 1, indicating that avoiding prolonged high-temperature treatment before final gel preparation of the catalytic organic sol is beneficial for controlling the overall hue.

[0096] Based on comprehensive test examples 1-3, it is evident that performing polyether silane treatment on colloidal silica in a wet state, and replacing the polyether carrier without forming silica powder intermediates, can reduce coarse scattering centers in the sealant. Dividing the modified sol on the same base surface into a base branch and a zinc catalytic branch, performing low-moisture post-treatment separately, and adding zinc carboxylate according to the measured acetoacetate equivalent is beneficial in maintaining the curing speed while reducing the extractable proportion of zinc components under specified conditions and the change in curing activity during storage. In combination with photothermal stabilizers and epoxy-alkoxysilane adhesive promoters that do not contain free primary and secondary amines, yellowing and haze increase after photothermal aging can be reduced.

[0097] The embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A low-haze, yellowing-resistant, transparent MS sealant, characterized in that, By weight, it includes 100 parts of silane-terminated polyether, 10-30 parts of silica-polyether organosol, 0.8-2.5 parts of moisture scavenger, 0.3-1.2 parts of photothermal stabilizer, 0.5-1.5 parts of epoxy-alkoxysilane adhesive promoter, and 0.005-0.030 parts of zinc catalyst (calculated as zinc element). The silica-polyether organosol is composed of a base organosol and a zinc-catalyzed organosol. The ratio of the base organosol to the zinc-catalyzed organosol is 70:30 to 85:15 based on the mass of silica contained in the two. The two are prepared separately after being split from the same base surface-modified sol. The basic surface-modified sol is obtained by wet hydrolysis and condensation treatment of ammonium-type aqueous colloidal silica and hydroxyl polyether silane in an aqueous alcohol medium; The basic organosol is prepared by reacting a split-stream surface-modified sol with a polyoxypropylene dialkyl ether to replace the aqueous alcohol medium, without solid-liquid separation or powder drying, and then reacting with 3-isocyanate-propyltrialkoxysilane. The zinc-catalyzed organosol is prepared by replacing a split-stream surface-modified sol with a monohydroxy polyoxypropylene ether to replace the aqueous alcohol medium, without solid-liquid separation or powder drying, and then reacting with tert-butyl acetoacetate via transesterification, and then mixing with zinc carboxylate. The zinc catalytic component is introduced by the zinc-catalyzed organosol. The sealant contains no other inorganic fillers besides the colloidal silica, and also contains no coloring pigments or dyes.

2. The sealant according to claim 1, characterized in that, The hydroxyl polyether silane is prepared by hydrosilylation reaction of a linear polyoxypropylene ether with an allyl group at one end and a hydroxyl group at the other end, and a number-average molecular weight of 500-1600 calculated by hydroxyl value, with a trimethoxysilane or triethoxysilane. The molar ratio of silane-hydrogen bonds to allyl groups is 1.00:1 to 1.05:1, and the residual allyl content of the obtained hydroxyl polyether silane is not higher than 0.05 mmol / g. When preparing the basic surface-modified sol, the molar amount of trialkoxysilane contained in the hydroxyl polyether silane is 0.20-0.80 μmol / m², based on the BET specific surface area of ​​colloidal silica. 2 .

3. The sealant according to claim 2, characterized in that, The polyoxypropylene dialkyl ether is a linear polyoxypropylene dimethyl ether with a number average molecular weight of 600-1500 and a hydroxyl value not exceeding 3 mg KOH / g, as determined by gel permeation chromatography; based on the measured hydroxyl value of the carrier substitution material, the molar ratio of isocyanate groups to hydroxyl groups in 3-isocyanate-propyltrialkoxysilane is 0.45:1-0.75:1, the reaction temperature is 50-60℃, and the endpoint is an isocyanate group mass fraction not exceeding 0.05%; the 3-isocyanate-propyltrialkoxysilane is 3-isocyanate-propyltrimethoxysilane or 3-isocyanate-propyltriethoxysilane.

4. The sealant according to claim 3, characterized in that, The monohydroxy polyoxypropylene ether is a linear polyoxypropylene ether with methoxy or n-butoxy end-capsulation and a number-average molecular weight of 1000-1500 calculated by hydroxyl value; the molar ratio of tert-butyl acetoacetate to hydroxyl groups is 0.30:1-0.65:1 based on the measured hydroxyl value of the carrier replacement material, and transesterification is performed at 90-105℃ to remove tert-butanol and unreacted tert-butyl acetoacetate until the residual amounts of the two are not higher than 0.10% and 0.15%, respectively; based on the quantitative nuclear magnetic resonance equivalent of acetoacetate groups in the material before zinc addition, the molar ratio of acetoacetate groups to zinc elements is 2.5:1-4.0:1, and the zinc carboxylate is one or both of zinc 2-ethylhexanoate and zinc neodecanoate, and the mixture is mixed at 65-80℃ for 1.5-3 hours.

5. The sealant according to claim 4, characterized in that, The primary particle size of the colloidal silica is 10–25 nm; the silica solid content in both the basic organosol and the zinc-catalyzed organosol is 20–40%, the silica aggregate particle size D90 is 50–150 nm, the water content is not higher than 200 ppm, and the total residual amount of C1–C3 monohydric alcohols is not higher than 0.10%; based on 100 parts of silane-terminated polyether, the total amount of silica introduced by the two organosols is 4–8 parts.

6. The sealant according to claim 5, characterized in that, The silane-terminated polyether is composed of 25-45% α-silane-terminated polyether and 55-75% γ-silane-terminated polyether; the end structure of the α-silane-terminated polyether includes The end structure of the γ-silane-terminated polyether includes The number-average molecular weights of the two, as determined by gel permeation chromatography, were 10,000–14,000 and 14,000–18,000, respectively, and their average silane functionality was 1.7–2.

0.

7. The sealant according to claim 6, characterized in that, The moisture scavenger is one or both of vinyltrimethoxysilane and vinyltriethoxysilane; the photothermal stabilizer is composed of a hydroxyphenyltriazine UV absorber, an N-alkoxy hindered amine light stabilizer, and a phosphite antioxidant in a mass ratio of 1:(0.3-1.0):(0.2-0.8); the epoxyalkoxysilane adhesion promoter is one or both of 3-glycidyl etheroxypropyltrimethoxysilane and 3-glycidyl etheroxypropyltriethoxysilane, and neither the photothermal stabilizer nor the adhesion promoter contains free primary or secondary amines.

8. A method for preparing the sealant according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Adjust the pH of ammonium-type aqueous colloidal silica to 8.5-9.8, add C1-C3 monohydric alcohol to 10-25% of the mass of the water-alcohol medium, and add hydroxyl polyether silane pre-diluted with the monohydric alcohol at 25-45°C for hydrolysis and condensation to obtain the basic surface modified sol. S2. The base surface modified sol is divided into two branches according to the mass ratio of silica content of 70:30 to 85:

15. The first branch is mixed with pre-dehydrated polyoxypropylene dimethyl ether, and the second branch is mixed with pre-dehydrated monohydroxy polyoxypropylene ether. Water and monohydric alcohol are removed at 45-70℃ and 1-10kPa respectively, without solid-liquid separation of colloidal silica and powder drying. S3. The first branch carrier substitution reacts with 3-isocyanate-propyltrialkoxysilane to obtain the basic organosol; the second branch carrier substitution is transesterified with tert-butyl acetoacetate to remove tert-butanol and unreacted tert-butyl acetoacetate, the acetoacetate ester equivalent of the material before zinc addition is determined, and zinc carboxylate is added accordingly to obtain and filter the zinc-catalyzed organosol. S4. Mix the dehydrated silane-terminated polyether with the base organic sol, add some moisture remover and filter, then add photothermal stabilizer, epoxy alkoxy silane adhesive promoter and remaining moisture remover in sequence, and then add zinc catalyzed organic sol at no higher than 35°C, vacuum degas and pack in moisture-proof packaging.

9. The method according to claim 8, characterized in that, In step S1, the total mass of sodium and potassium in the ammonium-type aqueous colloidal silica is no more than 0.05% of the silica mass. Ammonia is used to adjust the pH. Hydroxy-hydroxyl polyether silane is added in a 20-30% alcohol solution over 30-90 minutes, followed by a reaction time of 1-3 hours. In step S2, both polyether carriers are pre-dehydrated to a water content no higher than 150 ppm. A rotor speed of 300-500 r / min and a treatment load of 30-80 kg / (m²) of effective evaporation area are used. 2 The membrane devolatilization equipment (·h) removes water and monohydric alcohol, with an average residence time of 1-5 minutes per pass, passing through 1-3 times, until the water content of the carrier replacement material in both branches is not higher than 200 ppm and the total residual monohydric alcohol is not higher than 0.10%.

10. The method according to claim 9, characterized in that, In step S3, 3-isocyanate-propyltrialkoxysilane is added in the first branch at 50–60°C and reacted until the mass fraction of isocyanate groups is no higher than 0.05%. In the second branch, tert-butyl acetoacetate is added at 90–105°C and reacted for 3–6 hours. Tert-butanol and unreacted tert-butyl acetoacetate are removed under reduced pressure until the residual amounts of the two are no higher than 0.10% and 0.15%, respectively. After cooling to 65–80°C, the reaction is carried out according to the measured molar ratio of acetoacetate groups to zinc element in the material before zinc addition. Add zinc carboxylate at a ratio of 2.5:1 to 4.0:1 and mix for 1.5 to 3 hours. Filter the zinc-catalyzed organic sol through a filter unit with a nominal precision of 2 to 10 μm. In step S4, first add 30 to 60% of the total amount of moisture scavenging agent. Filter the resulting mixture through a filter unit with a nominal precision of 5 to 20 μm. The filter unit has a rejection rate of no less than 99.9% for particles no smaller than the nominal particle size. Then add the remaining components and vacuum degas until the moisture content of the sealant is no higher than 500 ppm.

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