A mold-proof silicone sealant with high curing rate and high adhesion

Abstract

A mildew-proof silicone sealant with high curing rate and high adhesive force belongs to the technical field of adhesives. The raw material composition of the mildew-proof silicone sealant with high curing rate and high adhesive force includes α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil, fumed silica, nano calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator. The mildew-proof silicone sealant with high curing rate and high adhesive force obtained by the present invention has a surface drying time of 9-13 min, a curing depth of 6.3-7.2 mm in 24 h, an adhesive strength of 3.0-3.6 MPa, a tensile strength of 5.8-6.4 MPa, a shear strength of 3.0-3.9 MPa, an elongation at break of 410-457%, and a mildew-proof grade of 0 for 30 days, 60 days, 180 days, and 360 days.

Description

Technical Field

[0001] The present invention relates to a mold-proof silicone sealant with high curing rate and high adhesion, belonging to the technical field of adhesives. Background Art

[0002] Silicone sealant is a silicone rubber based on polyfunctional siloxane crosslinking agent and terminal hydroxyl siloxane polymer, with polydimethylsiloxane as the main raw material, mixed with plasticizer, catalyst, coupling agent, etc. It has elasticity and adhesion, presents a viscous paste, and is prone to curing reaction with water in the air at room temperature. Silicone sealant is a high molecular polymer with Si-O bond as the main chain, and the bond energy is 1014 kJ / mol, which is much higher than that of organic sealants (such as acrylic sealants, polyurethane sealants, etc.) with C-C bond (344.4 kJ / mol) as the high molecular main chain. Therefore, it has good weather resistance and excellent high temperature resistance. When the temperature of ordinary organic sealants is too high, they will age rapidly, and are brittle and inelastic at low temperatures. The service temperature is usually between -20~100°C; while the service temperature range of silicone sealant is between -70~200°C. Within this temperature range, even if used outdoors for a long time, the silicone sealant is not easy to crack and harden, and its service life can reach several decades. Therefore, silicone sealant is widely used in the sealing and bonding of various synthetic materials and metals, the bonding and sealing of expansion joints in high-rise buildings, as well as decoration, waterproof engineering, etc. Currently, the largest application of silicone sealant is in the construction industry, and with the continuous expansion of the application area, the performance requirements of the construction industry for silicone sealant are also increasing day by day.

[0003] Resistance to high and low temperatures and aging resistance are the greatest advantages of silicone sealant. However, silicone sealant is an adhesive mainly composed of silicone resin, and the low polarity of silicone results in its bonding performance being generally worse than other resin systems, such as epoxy resin, polyurethane resin, and polyacrylate resin, etc. In addition to the low bonding strength, the curing rate of silicone sealant for home decoration is generally very slow at present. Especially during winter construction, when the environmental temperature is relatively low, it takes 24 hours or even longer to fully cure. When used in home decoration, in dark and humid places such as kitchens and bathrooms, the mildew problem of silicone sealant is also a key problem affecting its durable use. Therefore, there is an urgent need to develop a silicone sealant with high curing rate, high adhesion and long-lasting mildew-proof function.

[0004] Chinese Patent CN107892897A discloses a silicone sealant with strong adhesion and its preparation method. The raw materials consist of α,ω-dihydroxypolydimethylsiloxane, trimethylpolydimethylsiloxane, paraffin oil, organotin, cellulose acetate, glass fiber, polyamic acid solution, vinyltrichlorosilane, nano-calcium oxide, and pigments in specific weight ratios; through multiple experiments on the addition sequence of each raw material in the preparation process, as well as the temperature and stirring rate during the reaction, the optimal preparation method was determined. The silicone sealant obtained by this patent has a maximum bonding strength of only 1.02 MPa, and a large amount of fiber and powdery filler are added to the formula, which will have a great impact on the fluidity and curing rate of the colloid. In addition, this patent does not pay attention to the mold-proof performance of the sealant.

[0005] Chinese Patent CN117844438A discloses a silicone sealant with high strength and high adhesiveness and its preparation method. The method consists of the following components in parts by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 10 - 30 parts of dimethyl silicone oil, 150 - 250 parts of nano-calcium carbonate, 10 - 50 parts of heavy calcium, 30 - 60 parts of plasticizer, 5 - 15 parts of crosslinking agent, 3 - 5 parts of coupling agent, and 1 - 2 parts of catalyst. The silicone sealant obtained by this patent has a relatively high bonding strength, reaching 1.68 MPa, but the curing rate has not been improved, and it also has no mold-proof function.

[0006] As can be seen above, at present, silicone sealants still have problems such as low bonding strength, slow curing rate, and lack of mold-proof function. Therefore, it is a very practical research topic to develop a mold-proof silicone sealant with high curing rate and high adhesion to meet the needs of home decoration. Summary of the Invention

[0007] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides a mold-proof silicone sealant with high curing rate and high adhesion, and achieves the following invention purposes: to prepare a silicone sealant with high curing rate, high adhesion, and a long-lasting mold-proof function.

[0008] To achieve the above invention purposes, the present invention adopts the following technical solutions:

[0009] A mold-proof silicone sealant with high curing rate and high adhesion, the raw material composition of the mold-proof silicone sealant with high curing rate and high adhesion includes α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, phenoxy resin-coated nano-calcium carbonate, modified hydroxypropyl-γ-cyclodextrin loaded with mold-proof agent, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator;

[0010] The curing accelerator is one of acetohydroxamic acid (N-hydroxyacetamide), acetylhydroxylamine, O-methoxy-N-acetylhydroxylamine, O-(tert-butyldimethylsilyl)hydroxylamine, N-hydroxyacetamide, O-(trimethylsilyl)hydroxylamine, N-isopropylhydroxylamine, and N-tert-butylhydroxylamine;

[0011] The particle size of the fumed silica is 1 to 100 nm;

[0012] The raw material composition of the high-curing-rate and high-adhesion mold-proof silicone sealant has a composition ratio by weight of 170 to 290 parts of α,ω-dihydroxypolydimethylsiloxane, 20 to 50 parts of dimethyl silicone oil, 1 to 4 parts of fumed silica, 35 to 65 parts of phenoxy resin-coated nano calcium carbonate, 8 to 15 parts of modified hydroxypropyl-γ-cyclodextrin loaded with mold inhibitor, 1 to 2.5 parts of dibutyltin dilaurate, 10 to 20 parts of methyltrimethoxysilane, and 1 to 4 parts of curing accelerator;

[0013] Step 1: Preparation of phenoxy resin-coated nano calcium carbonate

[0014] After the nano calcium carbonate is thoroughly dried, it is added together with an oleate dispersant and a ketone solvent into a dispersion reaction kettle, strongly stirred and dispersed until the average particle size of the nano calcium carbonate particles is below 500 nm, then heated and kept at the reaction temperature, stirred evenly and maintained in a state of condensation reflux. An isocyanate group-containing silane coupling agent is added. After the silane coupling agent reacts completely, a ketone solution of phenoxy resin is then added, and the stirring reaction is continued until the phenoxy resin reacts completely, then cooled to room temperature, and centrifuged. The separated solid is washed with absolute ethanol and dried to obtain phenoxy resin-coated nano calcium carbonate;

[0015] The particle size of the nano calcium carbonate is 1 to 100 nm;

[0016] The oleate dispersant is one of oleyl linoleate, decyl oleate, and polyethylene glycol dioleate;

[0017] The ketone solvent is one of acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

[0018] The isocyanate group-containing silane coupling agent is one of 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane;

[0019] For the ketone solution of phenoxy resin, the mass fraction of phenoxy resin is 5 to 13 wt%, and the ketone solvent in the ketone solution is one of acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone;

[0020] The number-average molecular weight of the phenoxy resin is 25,000 to 35,000 g / mol;

[0021] The mass ratio of the input of the nano calcium carbonate, oleate dispersant, ketone solvent, isocyanate group-containing silane coupling agent, and ketone solution of phenoxy resin is 13~35:0.5~2:150~360:3~11:50~140;

[0022] Thorough drying is carried out at a drying temperature of 90~120 °C for a drying time of 5~9 hours;

[0023] Powerful stirring and dispersion are carried out at a dispersion rate of 9000~15000 revolutions per minute;

[0024] The reaction temperature is 70~95 °C;

[0025] Uniform stirring is carried out at a stirring rate of 900~1600 revolutions per minute;

[0026] After the silane coupling agent reacts completely, the reaction time is 2~5 hours;

[0027] After the reaction proceeds until the phenoxy resin reacts completely, the reaction time is 4~8 hours;

[0028] Washing and drying with absolute ethanol are carried out. The number of washing times is 3~4 times. The mass of absolute ethanol used for each washing is equal to the mass of the solid. The drying temperature is 60~90 °C, and the drying time is 4~7 hours.

[0029] Step 2. Preparation of modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent

[0030] First, dissolve the mildew-proof agent into a saturated solution with acetone to obtain an acetone solution of the mildew-proof agent. Then, dissolve hydroxypropyl-γ-cyclodextrin into a saturated solution with deionized water to obtain an aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant stirring, drop the acetone solution of the mildew-proof agent into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After the dropping is completed, continue stirring and reacting until the loading is complete. Then, cool to room temperature. Next, refrigerate, crystallize, filter, and vacuum dry the reacted liquid to obtain hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent. Then, add the hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent and absolute ethanol into the reaction kettle, stir and dissolve them. After heating to the reaction temperature at a constant temperature, add an amino group-containing silane coupling agent. After stirring and reacting completely, cool to room temperature. After refrigerating, crystallizing, filtering, and vacuum drying, obtain the modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent;

[0031] The mildew-proof agent is one of oxycarboxin, benzothiazole cyanide, and didodecyldimethylammonium chloride, a mixture composed of any two in any mass ratio, or a mixture composed of all three in any mass ratio;

[0032] The amino group-containing silane coupling agent is one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane;

[0033] The acetone solution of the mildew-proof agent is added dropwise into the aqueous solution of hydroxypropyl-γ-cyclodextrin at a dropping rate of 10-40 g / min;

[0034] The mass ratio of the acetone solution of the mildew-proof agent to the aqueous solution of hydroxypropyl-γ-cyclodextrin is 25-50:73;

[0035] The mass ratio of the hydroxypropyl-γ-cyclodextrin-loaded mildew-proof agent, absolute ethanol, and the amino group-containing silane coupling agent is 15-40:160-550:3-13;

[0036] For the heating and constant-temperature stirring, the constant temperature is 40-55 °C and the stirring rate is 500-950 revolutions per minute;

[0037] Continue stirring and reacting until the loading is complete, and the reaction time is 2-4 hours;

[0038] For the refrigeration, the refrigeration temperature is 0-3 °C and the refrigeration time is 12-20 hours;

[0039] Heat up and keep at a constant temperature to the reaction temperature, and the reaction temperature is 45-55 °C;

[0040] Stir and react completely, the reaction time is 5-8 hours, and the stirring rate is 300-600 revolutions per minute;

[0041] For the vacuum drying, the drying temperature is 35-45 °C and the drying time is 7-12 hours.

[0042] Step 3. Preparation of the mildew-proof silicone sealant with high curing rate and high adhesion

[0043] According to the composition ratio of the mildew-proof silicone sealant with high curing rate and high adhesion by weight, put α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, nano-calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin-loaded mildew-proof agent, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator into a dry double planetary mixer. Keep the vacuum negative pressure in the double planetary mixer at -0.1 to -0.095 MPa. Under the conditions of controlling the stirring rate at 100-150 revolutions per minute and the dispersion rate at 10,000-15,000 revolutions per minute, stir and disperse for 12-16 hours to obtain a viscous jelly-like substance. After continuous vacuum defoaming, discharge it. Pour the bubble-free jelly-like substance into a dry packaging container, fill it with nitrogen for protection and seal it, and it is the mildew-proof silicone sealant with high curing rate and high adhesion.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The present invention adds nano calcium carbonate as a reinforcing filler to improve the mechanical properties of the cured colloid. In order to ensure that nano calcium carbonate can be dispersed into the silicone sealant matrix resin at the nanoscale, the present invention coats the nano calcium carbonate particles with phenoxy resin to overcome the problem that nano calcium carbonate is prone to agglomeration itself. The specific method is to first disperse nano calcium carbonate into a ketone solvent. To promote the uniform dispersion of nano calcium carbonate at the nanoscale in the ketone solvent, the present invention uses an oleate dispersant and disperses it by strong stirring, so that nano calcium carbonate reaches the nanoscale dispersion degree in the ketone solvent. Then, the surface is modified with a silane coupling agent containing an isocyanate group, so that the surface of nano calcium carbonate is covered with isocyanate groups. Then, phenoxy resin is added, and the reaction between the active hydroxyl groups carried by the phenoxy resin and the isocyanate groups is used to coat the surface of nano calcium carbonate with phenoxy resin. The nano calcium carbonate coated with phenoxy resin has very good compatibility with the resin matrix of the silicone sealant, and can ensure that nano calcium carbonate is dispersed at the nanoscale in α,ω-dihydroxypolydimethylsiloxane. Most importantly, the large number of hydroxyl functional groups contained in the phenoxy resin itself play a very important role in improving the adhesion between the silicone sealant and the substrate. These hydroxyl groups with relatively large polarity can play a role similar to the epoxy functional groups and hydroxyl functional groups in epoxy resin, effectively improving the wetting ability and adhesion of the silicone sealant to the substrate. Moreover, the specific surface area of nano calcium carbonate is huge, and the phenoxy resin coated on it will also have a very large surface area. This will undoubtedly greatly increase the contact area between the hydroxyl groups on the phenoxy resin and the substrate surface during the curing process of the colloid, maximize the wetting area of the silicone sealant and the substrate, and improve the adhesion. In addition, the large number of hydroxyl groups contained in the phenoxy resin coated on nano calcium carbonate have a strong hydrogen bond adsorption effect with the hydroxypropyl-γ-cyclodextrin loaded with a mildew inhibitor modified by an amino-containing silane coupling agent, which will increase the cohesive energy of the colloid after the silicone sealant is cured and further enhance the mechanical properties of the colloid;

[0046] 2. The present invention uses hydroxypropyl - γ - cyclodextrin to load and encapsulate the mildew - proof agent, so as to slow down the migration loss of the mildew - proof agent from the inside of the silicone sealant to the surface, achieving the purpose of long - term mildew prevention. Moreover, in order to further enhance the long - term effectiveness of the mildew - proof function, taking advantage of the property that hydroxypropyl - γ - cyclodextrin is rich in hydroxyl functional groups, the hydroxypropyl - γ - cyclodextrin loaded with the mildew - proof agent is modified with an amino - containing silane coupling agent. After such modification, the hydroxypropyl - γ - cyclodextrin loaded with the mildew - proof agent is more easily dissolved in α,ω - dihydroxypolydimethylsiloxane, and forms a certain hydrogen - bond adsorption effect with the hydroxyl groups on the surface of the phenoxy resin - coated nano - calcium carbonate, enhancing the cohesive energy of the colloid, improving the density of the colloid, and further delaying the migration of the mildew - proof agent from the inside of the colloid to the outside, making the mildew - proof effect of the mildew - proof agent more persistent;

[0047] 3. The present invention adds a curing accelerator containing a hydroxylamine or hydroxyamide group. Such substances can cooperate with dibutyltin dilaurate, and utilize the negative - charge induction and electron complexation effects of the lone pair electrons on the nitrogen atom of the amine to accelerate the condensation reaction rate of α,ω - dihydroxypolydimethylsiloxane itself and with other active - hydrogen functional groups, thereby greatly improving the curing rate of the silicone sealant, shortening the surface - drying time and also increasing the curing depth at 24 hours;

[0048] 4. The mildew - proof type silicone sealant with high curing rate and high adhesion force obtained by the present invention has a surface - drying time of 9 - 13 min, a curing depth of 6.3 - 7.2 mm at 24 h, an adhesion strength of 3.0 - 3.6 MPa, a tensile strength of 5.8 - 6.4 MPa, a shear strength of 3.0 - 3.9 MPa, an elongation at break of 410 - 457%, and a mildew - proof grade of 0 at 30 days, 60 days, 180 days, and 360 days. Detailed implementation manners

[0049] The following are descriptions of the preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0050] Example 1: A mildew - proof type silicone sealant with high curing rate and high adhesion force

[0051] Step 1: Preparation of phenoxy resin - coated nano - calcium carbonate

[0052] After the nano calcium carbonate is thoroughly dried, it is added into a dispersion reaction kettle together with an oleate dispersant and a ketone solvent, and strongly stirred and dispersed until the average particle size of the nano calcium carbonate particles is below 500 nm. Then, the temperature is raised and kept constant at the reaction temperature. Under the conditions of uniform stirring and maintaining the condensing reflux state, a silane coupling agent containing an isocyanate group is added. After the silane coupling agent reacts completely, a ketone solution of phenoxy resin is added, and the stirring reaction is continued until the phenoxy resin reacts completely. Then, the temperature is lowered to room temperature, and centrifugal separation is carried out. The separated solid is washed with absolute ethanol and dried to obtain phenoxy resin-coated nano calcium carbonate;

[0053] The particle size of the nano calcium carbonate is 40 nm;

[0054] The oleate dispersant is oleyl linoleate;

[0055] The ketone solvent is acetone;

[0056] The silane coupling agent containing an isocyanate group is 3-isocyanatopropyltrimethoxysilane;

[0057] For the ketone solution of phenoxy resin, the mass fraction of phenoxy resin is 11 wt%, and the ketone solvent in the ketone solution is acetone;

[0058] The number average molecular weight of the phenoxy resin is 30000;

[0059] For the nano calcium carbonate, oleate dispersant, ketone solvent, silane coupling agent containing an isocyanate group, and ketone solution of phenoxy resin, the feeding mass ratio of the above substances is 20:1:260:8:110;

[0060] For the thorough drying, the drying temperature is 110 °C and the drying time is 8 hours;

[0061] For the strong stirring and dispersion, the dispersion rate is 13000 revolutions per minute;

[0062] The reaction temperature is 90 °C;

[0063] For the uniform stirring, the stirring rate is 1200 revolutions per minute;

[0064] After the silane coupling agent reacts completely, the reaction time is 4 hours;

[0065] After the reaction until the phenoxy resin reacts completely, the reaction time is 7 hours;

[0066] For the washing with absolute ethanol and drying, the number of washing times is 3 times, the mass of absolute ethanol used for each washing is equal to the mass of the solid, the drying temperature is 80 °C, and the drying time is 6 hours.

[0067] Step 2: Preparation of modified hydroxypropyl-γ-cyclodextrin loaded with mold inhibitor

[0068] First, dissolve the mildew preventive in acetone to form a saturated solution to obtain an acetone solution of the mildew preventive. Then, dissolve hydroxypropyl-γ-cyclodextrin in deionized water to form a saturated solution to obtain an aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant stirring, drop the acetone solution of the mildew preventive into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After the dropping is completed, continue stirring and reacting until the loading is complete. Then, cool to room temperature. Next, refrigerate, crystallize, filter, and vacuum dry the reacted liquid to obtain hydroxypropyl-γ-cyclodextrin loaded with the mildew preventive. Then, add the hydroxypropyl-γ-cyclodextrin loaded with the mildew preventive and absolute ethanol to a reaction kettle. After stirring and dissolving, raise the temperature to a constant temperature to the reaction temperature, and then add an amino-containing silane coupling agent. After stirring and reacting completely, cool to room temperature. After refrigerating, crystallizing, filtering, and vacuum drying, a modified hydroxypropyl-γ-cyclodextrin loaded with the mildew preventive is obtained;

[0069] The mildew preventive is bitertanol;

[0070] The amino-containing silane coupling agent is γ-aminopropyltriethoxysilane;

[0071] The acetone solution of the mildew preventive is dropped into the aqueous solution of hydroxypropyl-γ-cyclodextrin at a dropping rate of 30 g / min;

[0072] The mass ratio of the acetone solution of the mildew preventive to the aqueous solution of hydroxypropyl-γ-cyclodextrin is 40:73;

[0073] The mass ratio of the hydroxypropyl-γ-cyclodextrin loaded with the mildew preventive, absolute ethanol, and the amino-containing silane coupling agent is 30:400:8;

[0074] For the heating and constant stirring, the constant temperature is 50 °C and the stirring rate is 800 revolutions per minute;

[0075] For the continued stirring and reacting until the loading is complete, the reaction time is 3 hours;

[0076] For the refrigerating, the refrigerating temperature is 1 °C and the refrigerating time is 15 hours;

[0077] For the raising the temperature to a constant temperature to the reaction temperature, the reaction temperature is 53 °C;

[0078] For the stirring and reacting completely, the reaction time is 7 hours and the stirring rate is 500 revolutions per minute;

[0079] For the vacuum drying, the drying temperature is 40 °C and the drying time is 9 hours.

[0080] Step 3: Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion

[0081] The raw material composition of the mold-proof silicone sealant with high curing rate and high adhesion force has a composition ratio by weight of 230 parts of α,ω-dihydroxypolydimethylsiloxane, 30 parts of dimethyl silicone oil, 2 parts of fumed silica, 50 parts of nano calcium carbonate coated with phenoxy resin, 11 parts of modified hydroxypropyl-γ-cyclodextrin loaded with mold inhibitor, 2 parts of dibutyltin dilaurate, 16 parts of methyltrimethoxysilane, and 3 parts of curing accelerator;

[0082] The curing accelerator is acetohydroxamic acid (N-hydroxyacetamide);

[0083] The particle size of the fumed silica is 10 nm;

[0084] According to the composition ratio by weight of the mold-proof silicone sealant with high curing rate and high adhesion force, put α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, nano calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin loaded with mold inhibitor, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator into a dry double planetary mixer. Keep the vacuum negative pressure in the double planetary mixer at -0.096 MPa. Under the conditions of controlling the stirring rate at 120 revolutions per minute and the dispersion rate at 13,000 revolutions per minute, stir and disperse for 15 hours to obtain a viscous jelly-like substance. After continuously evacuating and degassing, discharge the material. Fill the bubble-free jelly-like substance into a dry packaging container, fill it with nitrogen for protection and seal it, and it is the mold-proof silicone sealant with high curing rate and high adhesion force.

[0085] Example 2: A mold-proof silicone sealant with high curing rate and high adhesion force

[0086] Step 1: Preparation of nano calcium carbonate coated with phenoxy resin

[0087] After the nano calcium carbonate is thoroughly dried, add it together with an oleate dispersant and a ketone solvent into a dispersion reaction kettle. Stir strongly to disperse until the average particle size of the nano calcium carbonate particles is below 500 nm. Then heat up and keep the temperature constant at the reaction temperature. Under the conditions of stirring evenly and maintaining the condensation reflux state, add a silane coupling agent containing an isocyanate group. After the silane coupling agent reacts completely, then add the ketone solution of phenoxy resin, and continue to stir and react until the phenoxy resin reacts completely. Then cool down to room temperature and centrifuge. The separated solid is washed with absolute ethanol and dried to obtain nano calcium carbonate coated with phenoxy resin;

[0088] The particle size of the nano calcium carbonate is 1 nm;

[0089] The oleate dispersant is decyl oleate;

[0090] The ketone solvent is methyl ethyl ketone;

[0091] The isocyanate group-containing silane coupling agent is 3-isocyanatopropyltriethoxysilane;

[0092] The ketone solution of the phenoxy resin, the mass fraction of the phenoxy resin is 5 wt%, and the ketone solvent in the ketone solution is methyl ethyl ketone;

[0093] The number-average molecular weight of the phenoxy resin is 25000 g / mol;

[0094] The feeding mass ratio of the nano calcium carbonate, the oleate dispersant, the ketone solvent, the isocyanate group-containing silane coupling agent, and the ketone solution of the phenoxy resin is 13:0.5:150:3:50;

[0095] The thorough drying is carried out at a drying temperature of 90 °C and a drying time of 5 hours;

[0096] The strong stirring and dispersion are carried out at a dispersion rate of 9000 revolutions per minute;

[0097] The reaction temperature is 70 °C;

[0098] The uniform stirring is carried out at a stirring rate of 900 revolutions per minute;

[0099] After the silane coupling agent reacts completely, the reaction time is 2 hours;

[0100] After the reaction until the phenoxy resin reacts completely, the reaction time is 4 hours;

[0101] The washing and drying with absolute ethanol are carried out. The number of washing times is 3 times. The mass of absolute ethanol used for each washing is equal to the mass of the solid. The drying temperature is 60 °C and the drying time is 4 hours.

[0102] Step 2. Preparation of modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent

[0103] First, dissolve the mildew-proof agent in acetone to form a saturated solution to obtain the acetone solution of the mildew-proof agent. Then, dissolve hydroxypropyl-γ-cyclodextrin in deionized water to form a saturated solution to obtain the aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant stirring, drop the acetone solution of the mildew-proof agent into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After the dropping is completed, continue stirring and reacting until the loading is complete. Then, cool to room temperature. Then, refrigerate, crystallize, filter, and vacuum dry the reacted liquid to obtain hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent. Then, add hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent and absolute ethanol into the reaction kettle, stir and dissolve, heat to the reaction temperature at a constant temperature, add the amino group-containing silane coupling agent, stir and react completely, then cool to room temperature, and obtain the modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent through refrigeration, crystallization, filtration, and vacuum drying;

[0104] The mildew-proof agent is benzisothiazolinone;

[0105] The amino-group-containing silane coupling agent is N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane;

[0106] The acetone solution of the mildew-proof agent is dropped into the aqueous solution of hydroxypropyl-γ-cyclodextrin at a dropping rate of 10 g / min;

[0107] The mass ratio of the acetone solution of the mildew-proof agent to the aqueous solution of hydroxypropyl-γ-cyclodextrin is 25:73;

[0108] The mass ratio of the hydroxypropyl-γ-cyclodextrin-loaded mildew-proof agent, absolute ethanol, and the amino-group-containing silane coupling agent is 15:160:3;

[0109] For the heating and constant-temperature stirring, the constant temperature is 40 °C and the stirring rate is 500 revolutions per minute;

[0110] Continue stirring and reacting until the loading is complete, and the reaction time is 2 hours;

[0111] For the refrigeration, the refrigeration temperature is 0 °C and the refrigeration time is 12 hours;

[0112] Heat up and keep the temperature constant to the reaction temperature, and the reaction temperature is 45 °C;

[0113] Stir and react completely, the reaction time is 5 hours, and the stirring rate is 300 revolutions per minute;

[0114] For the vacuum drying, the drying temperature is 35 °C and the drying time is 7 hours.

[0115] Step 3. Preparation of the mildew-proof silicone sealant with high curing rate and high adhesion

[0116] The raw material composition of the mildew-proof silicone sealant with high curing rate and high adhesion, the composition ratio in parts by weight is 170 parts of α,ω-dihydroxypolydimethylsiloxane, 20 parts of dimethyl silicone oil, 1 part of fumed silica, 35 parts of nano-calcium carbonate coated with phenoxy resin, 8 parts of modified hydroxypropyl-γ-cyclodextrin-loaded mildew-proof agent, 1 part of dibutyltin dilaurate, 10 parts of methyltrimethoxysilane, and 1 part of curing accelerator;

[0117] The curing accelerator is acetylhydroxylamine;

[0118] The particle size of the fumed silica is 1 nm;

[0119] According to the composition ratio by weight of the mold-proof silicone sealant with high curing rate and high adhesion force, put α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, nano calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin loaded with mold inhibitor, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator into a dry double planetary mixer. Keep the vacuum negative pressure in the double planetary mixer at -0.1 MPa, control the stirring rate at 100 revolutions per minute and the dispersion rate at 10,000 revolutions per minute. After stirring and dispersing for 12 hours, a viscous jelly-like substance is obtained. After continuously evacuating and degassing, discharge the material, pour the bubble-free jelly-like substance into a dry packaging container, fill it with nitrogen for protection and seal it, and it is the mold-proof silicone sealant with high curing rate and high adhesion force.

[0120] Example 3: A mold-proof silicone sealant with high curing rate and high adhesion force

[0121] Step 1: Preparation of nano calcium carbonate coated with phenoxy resin

[0122] After the nano calcium carbonate is thoroughly dried, add it together with an oleate dispersant and a ketone solvent into a dispersion reaction kettle, and strongly stir and disperse until the average particle size of the nano calcium carbonate particles is below 500 nm. Then raise the temperature and keep it at the reaction temperature. Under the condition of uniform stirring and maintaining the condensation reflux state, add a silane coupling agent containing an isocyanate group. After the silane coupling agent reacts completely, then add the ketone solution of phenoxy resin, and continue to stir and react until the phenoxy resin reacts completely. Then cool to room temperature and centrifuge. The separated solid is washed with absolute ethanol and dried to obtain nano calcium carbonate coated with phenoxy resin;

[0123] The particle size of the nano calcium carbonate is 100 nm;

[0124] The oleate dispersant is polyethylene glycol dioleate;

[0125] The ketone solvent is methyl isobutyl ketone;

[0126] The silane coupling agent containing an isocyanate group is 3-isocyanatopropyltrimethoxysilane;

[0127] For the ketone solution of phenoxy resin, the mass fraction of phenoxy resin is 5 - 13 wt%, and the ketone solvent in the ketone solution is methyl isobutyl ketone;

[0128] The number average molecular weight of the phenoxy resin is 35,000 g / mol;

[0129] The feeding mass ratio of the nano calcium carbonate, oleate dispersant, ketone solvent, silane coupling agent containing an isocyanate group, and ketone solution of phenoxy resin is 35: 2:360:11140;

[0130] The thorough drying is carried out at a drying temperature of 120 °C for 9 hours;

[0131] For the strong stirring and dispersion, the dispersion rate is 15,000 revolutions per minute;

[0132] The reaction temperature is 95 °C;

[0133] For the uniform stirring, the stirring rate is 1,600 revolutions per minute;

[0134] After the silane coupling agent reacts completely, the reaction time is 5 hours;

[0135] After the reaction proceeds until the phenoxy resin reacts completely, the reaction time is 8 hours;

[0136] For the washing and drying with absolute ethanol, the number of washing times is 4 times. The mass of absolute ethanol used for each washing is equal to the mass of the solid. The drying temperature is 90 °C and the drying time is 7 hours.

[0137] Step 2: Preparation of modified hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor

[0138] First, dissolve the mildew inhibitor in acetone to form a saturated solution to obtain the acetone solution of the mildew inhibitor. Then, dissolve hydroxypropyl-γ-cyclodextrin in deionized water to form a saturated solution to obtain the aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant stirring, drop the acetone solution of the mildew inhibitor into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After the dropping is completed, continue stirring and reacting until the loading is complete. Then, cool to room temperature. After that, refrigerate, crystallize, filter, and vacuum dry the reacted liquid to obtain hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor. Then, add hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor and absolute ethanol into the reaction kettle, stir and dissolve them. After heating to the reaction temperature at a constant temperature, add the amino-containing silane coupling agent. After stirring and reacting completely, cool to room temperature. After refrigerating, crystallizing, filtering, and vacuum drying, obtain the modified hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor;

[0139] The mildew inhibitor is dioctyldimethylammonium chloride;

[0140] The amino-containing silane coupling agent is N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane;

[0141] When the acetone solution of the mildew inhibitor is dropped into the aqueous solution of hydroxypropyl-γ-cyclodextrin, the dropping rate is 40 g / min;

[0142] The mass ratio of the acetone solution of the mildew inhibitor to the aqueous solution of hydroxypropyl-γ-cyclodextrin is 50:73;

[0143] The mass ratio of hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor, absolute ethanol, and the amino-containing silane coupling agent is 40:550:13;

[0144] For the heating and constant-temperature stirring, the constant temperature is 55°C and the stirring rate is 950 revolutions per minute;

[0145] Continue stirring and reacting until the loading is complete, and the reaction time is 4 hours;

[0146] For the refrigeration, the refrigeration temperature is 3°C and the refrigeration time is 20 hours;

[0147] Heat up and keep at a constant temperature to the reaction temperature, and the reaction temperature is 55°C;

[0148] Stir and react completely, the reaction time is 8 hours, and the stirring rate is 600 revolutions per minute;

[0149] For the vacuum drying, the drying temperature is 45°C and the drying time is 12 hours.

[0150] Step 3: Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion

[0151] The raw material composition of the mildew-proof silicone sealant with high curing rate and high adhesion, the composition ratio in parts by weight is 290 parts of α,ω-dihydroxypolydimethylsiloxane, 50 parts of dimethyl silicone oil, 4 parts of fumed silica, 65 parts of nano calcium carbonate coated with phenoxy resin, 15 parts of modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent, 2.5 parts of dibutyltin dilaurate, 20 parts of methyltrimethoxysilane, and 4 parts of curing accelerator;

[0152] The curing accelerator is O-methoxy-N-acetylhydroxylamine;

[0153] The particle size of the fumed silica is 100 nm;

[0154] According to the composition ratio of the mildew-proof silicone sealant with high curing rate and high adhesion in parts by weight, put α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, nano calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator into a dry double planetary mixer. Keep the vacuum negative pressure in the double planetary mixer at -0.095 MPa. Under the conditions of controlling the stirring rate at 150 revolutions per minute and the dispersion rate at 15,000 revolutions per minute, stir and disperse for 16 hours to obtain a viscous jelly-like substance. After continuously evacuating and degassing, discharge the material, and pour the bubble-free jelly-like substance into a dry packaging container, fill it with nitrogen for protection and seal it, which is the mildew-proof silicone sealant with high curing rate and high adhesion.

[0155] Example 4: A mildew-proof silicone sealant with high curing rate and high adhesion

[0156] Step 1: Preparation of nano calcium carbonate coated with phenoxy resin

[0157] The ketone solvent is cyclohexanone;

[0158] For the ketone solution of phenoxy resin, the mass fraction of phenoxy resin is 11 wt%, the ketone solvent in the ketone solution is cyclohexanone, and other operations are the same as in Example 1;

[0159] The operation of Step 2 is the same as in Example 1;

[0160] Step 3. Preparation of a mold-proof silicone sealant with high curing rate and high adhesion

[0161] The curing accelerator is O-(tert-butyldimethylsilyl)hydroxylamine, and other operations are the same as in Example 1.

[0162] Example 5: A mold-proof silicone sealant with high curing rate and high adhesion

[0163] The operations of Steps 1 and 2 are the same as in Example 1;

[0164] Step 3. Preparation of a mold-proof silicone sealant with high curing rate and high adhesion

[0165] The curing accelerator is N-hydroxyacetamide, and other operations are the same as in Example 1.

[0166] Example 6: A mold-proof silicone sealant with high curing rate and high adhesion

[0167] The operations of Steps 1 and 2 are the same as in Example 1;

[0168] Step 3. Preparation of a mold-proof silicone sealant with high curing rate and high adhesion

[0169] The curing accelerator is O-(trimethylsilyl)hydroxylamine, and other operations are the same as in Example 1.

[0170] Example 7: A mold-proof silicone sealant with high curing rate and high adhesion

[0171] The operations of Steps 1 and 2 are the same as in Example 1;

[0172] Step 3. Preparation of a mold-proof silicone sealant with high curing rate and high adhesion

[0173] The curing accelerator is N-isopropylhydroxylamine, and other operations are the same as in Example 1.

[0174] Example 8: A mold-proof silicone sealant with high curing rate and high adhesion

[0175] The operations of Steps 1 and 2 are the same as in Example 1;

[0176] Step 3. Preparation of a mold-proof silicone sealant with high curing rate and high adhesion

[0177] The curing accelerator is N-tert-butylhydroxylamine, and other operations are the same as in Example 1.

[0178] Comparative Example 1: A mildew-proof silicone sealant with high curing rate and high adhesion

[0179] Based on Example 1, in Step 1, the preparation of phenoxy resin-coated nano-calcium carbonate is not carried out. In Step 3, in the preparation of the mildew-proof silicone sealant with high curing rate and high adhesion, 50 parts of phenoxy resin-coated nano-calcium carbonate are replaced with 50 parts of nano-calcium carbonate in equal amount. The specific operations are as follows:

[0180] Do not carry out Step 1, the preparation of phenoxy resin-coated nano-calcium carbonate;

[0181] The operation of Step 2 is the same as in Example 1;

[0182] Step 3, Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion

[0183] Replace 50 parts of phenoxy resin-coated nano-calcium carbonate with 50 parts of nano-calcium carbonate in equal amount, and other operations are the same as in Example 1.

[0184] Comparative Example 2: A mildew-proof silicone sealant with high curing rate and high adhesion

[0185] Based on Example 1, in Step 1, for the preparation of phenoxy resin-coated nano-calcium carbonate, only methyltrimethoxysilane is used for surface treatment of nano-calcium carbonate. In Step 3, in the preparation of the mildew-proof silicone sealant with high curing rate and high adhesion, 50 parts of phenoxy resin-coated nano-calcium carbonate are replaced with 50 parts of modified nano-calcium carbonate in equal amount. The specific operations are as follows:

[0186] Step 1, Preparation of modified nano-calcium carbonate

[0187] After the nano-calcium carbonate is thoroughly dried, it is added into a dispersion reaction kettle together with an oleate dispersant and a ketone solvent, and strongly stirred and dispersed until the average particle size of the nano-calcium carbonate particles is below 500 nm. Then, the temperature is raised and kept constant at the reaction temperature, and under the conditions of uniform stirring and maintaining the condensation reflux state, methyltrimethoxysilane is added. After the methyltrimethoxysilane reaction is complete, the temperature is lowered to room temperature, and centrifugal separation is carried out. The separated solid is washed with absolute ethanol and dried to obtain modified nano-calcium carbonate;

[0188] The particle size of the nano-calcium carbonate is 40 nm;

[0189] The oleate dispersant is oleyl linoleate;

[0190] The ketone solvent is acetone;

[0191] The mass ratio of the input of the nano calcium carbonate, oleate dispersant, ketone solvent, and methyltrimethoxysilane is 20:1:260:8;

[0192] For the thorough drying, the drying temperature is 110 °C and the drying time is 8 hours;

[0193] For the strong stirring and dispersion, the dispersion rate is 13,000 revolutions per minute;

[0194] The reaction temperature is 90 °C;

[0195] For the uniform stirring, the stirring rate is 1,200 revolutions per minute;

[0196] After the reaction of the methyltrimethoxysilane is complete, the reaction time is 4 hours;

[0197] For the washing and drying with absolute ethanol, the number of washing times is 3 times. The mass of absolute ethanol used for each washing is equal to the mass of the solid. The drying temperature is 80 °C and the drying time is 6 hours.

[0198] The operation of Step 2 is the same as that of Example 1;

[0199] Step 3. Preparation of a high-curing-rate and high-adhesion mold-proof silicone sealant

[0200] Replace 50 parts of phenoxy resin-coated nano calcium carbonate with 50 parts of modified nano calcium carbonate, and other operations are the same as those in Example 1.

[0201] Comparative Example 3: A high-curing-rate and high-adhesion mold-proof silicone sealant

[0202] Based on Example 1, in Step 2, the preparation of the modified hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor, do not prepare the modified hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor, only prepare the hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor. In Step 3, the preparation of a high-curing-rate and high-adhesion mold-proof silicone sealant, replace 11 parts of the modified hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor with 11 parts of the hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor. The specific operation is as follows:

[0203] The operation of Step 1 is the same as that of Example 1;

[0204] Step 2. Preparation of the hydroxypropyl-γ-cyclodextrin loaded with a mold inhibitor

[0205] First, dissolve the mildew-proof agent in acetone to form a saturated solution to obtain an acetone solution of the mildew-proof agent. Then, dissolve hydroxypropyl-γ-cyclodextrin in deionized water to form a saturated solution to obtain an aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant stirring, drop the acetone solution of the mildew-proof agent into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After the dropping is complete, continue stirring and reacting until the loading is complete. Then, cool to room temperature, and then refrigerate, crystallize, filter, and vacuum dry the reacted liquid to obtain hydroxypropyl-γ-cyclodextrin loaded with the mildew-proof agent.

[0206] The mildew-proof agent is bitertanol.

[0207] When dropping the acetone solution of the mildew-proof agent into the aqueous solution of hydroxypropyl-γ-cyclodextrin, the dropping rate is 10 - 40 g / min.

[0208] The mass ratio of the acetone solution of the mildew-proof agent to the aqueous solution of hydroxypropyl-γ-cyclodextrin is 40:73.

[0209] For the heating and constant stirring, the constant temperature is 50 °C and the stirring rate is 800 revolutions per minute.

[0210] When continuing to stir and react until the loading is complete, the reaction time is 3 hours.

[0211] For the refrigeration, the refrigeration temperature is 1 °C and the refrigeration time is 15 hours.

[0212] For the vacuum drying, the drying temperature is 40 °C and the drying time is 9 hours.

[0213] Step 3: Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion

[0214] Replace 11 parts of the modified hydroxypropyl-γ-cyclodextrin loaded with the mildew-proof agent with 11 parts of hydroxypropyl-γ-cyclodextrin loaded with the mildew-proof agent, and other operations are the same as in Example 1.

[0215] Comparative Example 4: A mildew-proof silicone sealant with high curing rate and high adhesion

[0216] On the basis of Example 1, in Step 3: Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion, do not add a curing accelerator, and replace 3 parts of the curing accelerator with 3 parts of α,ω-dihydroxypolydimethylsiloxane. The specific operations are as follows:

[0217] The operations in Steps 1 and 2 are the same as in Example 1.

[0218] Step 3: Preparation of a mildew-proof silicone sealant with high curing rate and high adhesion

[0219] Replace 3 parts of the curing accelerator with 3 parts of α,ω-dihydroxypolydimethylsiloxane, and other operations are the same as in Example 1.

[0220] Performance test:

[0221] For the mildew-proof silicone sealants with high curing rate and high adhesion force obtained in Examples 1, 2, 3, 4, 5, 6, 7, 8 and Comparative Examples 1, 2, 3, 4, tests on indexes such as surface drying time, 24h curing depth, bonding strength, tensile strength, shear strength, elongation at break, etc. were carried out according to standards such as GB / T13477.3-2017, GB / T11211-2009, GB / T528-2009, GB / T531.1-2008; the mildew-proof grade was tested under the conditions of 30°C and relative humidity of 60% with reference to JC / T885-2016 and GB / T 1741-2020;

[0222] The test results are shown in Table 1:

[0223] Table 1

[0224] As can be seen from the test results in Table 1, the skin-drying times of Examples 1-8 are all within 15 minutes, the curing depths after 24 hours are all above 6 mm, the bonding strengths are above 3 MPa, and the mechanical property indexes such as tensile strength, shear strength, and elongation at break are also very excellent. The mildew-proof grade can be maintained at the highest good level of 0 within the range from 30 days to 360 days. This shows that the silicone sealant obtained by the present invention has a very high curing rate and high adhesion, the cured colloid has very good mechanical properties and has a long-term mildew-proof function; in Comparative Example 1, phenoxy resin-coated nano-calcium carbonate is not prepared, and the phenoxy resin-coated nano-calcium carbonate is directly replaced with nano-calcium carbonate in equal amounts. The skin-drying time of Comparative Example 1 is extended to 25 minutes, the curing depth after 24 hours is reduced to 4.8 mm, and the mechanical property indexes such as bonding strength, tensile strength, shear strength, and elongation at break are all drastically reduced, and the mildew-proof grade has no change. This shows that when directly adding nano-calcium carbonate, due to the relatively large surface polarity of nano-calcium carbonate, it is difficult to be well dispersed in the silicone rubber matrix without surface modification, and the various properties of the silicone sealant will be greatly reduced due to agglomeration; in Comparative Example 2, the nano-calcium carbonate is only surface-treated with methyltrimethoxysilane and not coated with phenoxy resin. Compared with Comparative Example 1, the skin-drying time of Comparative Example 2 is slightly shortened, the curing depth after 24 hours is also increased, and the mechanical properties such as bonding strength, tensile strength, shear strength, and elongation at break are slightly better than those of Comparative Example 1, but the above-mentioned indexes of Comparative Example 2 are far worse than those of Example 1. This shows that the nano-calcium carbonate only surface-treated with methyltrimethoxysilane can improve the dispersion uniformity of the nano-calcium carbonate in the matrix resin of the silicone sealant, but it is still difficult to greatly improve the mechanical properties of the silicone sealant, especially the bonding strength, and there is no particularly large improvement. For the nano-calcium carbonate coated with phenoxy resin, its mechanical property indexes such as bonding strength are greatly improved, and the curing rate and skin-drying time are also significantly improved. This shows that the coating of phenoxy resin can promote the bonding of the colloid to the substrate surface and also improve the cohesion of the cured colloid, so it can greatly improve the various mechanical properties of the silicone sealant;In Comparative Example 3, the modified hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor was replaced with an equal amount of hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor, that is, after the hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor, it was not modified with an amino-containing silane coupling agent. The surface drying time of Comparative Example 3 increased significantly, and the curing depth at 24 hours also decreased significantly. The mechanical properties such as bonding strength, tensile strength, shear strength, and elongation at break also decreased significantly. This shows that after the hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor is modified with an amino-containing silane coupling agent, it can significantly improve the curing speed of the silicone sealant to a certain extent, and also has a very obvious positive improvement effect on the mechanical properties of the cured colloid. This may be because the amino group at the end of the amino-containing silane coupling agent has a certain catalytic and accelerating effect on the curing of the colloid. In addition, it may also form a hydrogen bond adsorption effect with the nano-calcium carbonate coated with phenoxy resin in the colloid (because the phenoxy resin has a large number of hydroxyl groups), which can increase the cohesive energy of the colloid, and then improve the density of the cured colloid, and thus significantly improve the mechanical properties of the colloid. In addition, the mildew-proof grade of Comparative Example 3 decreased significantly compared with that of Example 1. This may be because the hydroxypropyl-γ-cyclodextrin modified with an amino-containing silane coupling agent is more tightly combined with the inside of the cured colloid, that is, the strong hydrogen bond between the hydroxypropyl-γ-cyclodextrin containing an amino group at the end and the surface of the nano-calcium carbonate particles inside the colloid makes its combination with the colloid more tight, thus slowing down the precipitation rate of the mildew inhibitor, and then making the mildew-proof effect have long-term persistence; in Comparative Example 4, no curing accelerator was added, the surface drying time of Comparative Example 4 increased to the maximum, the curing depth at 24 hours decreased to the lowest value, and the mechanical properties such as bonding strength, tensile strength, shear strength, and elongation at break after curing also decreased slightly. This shows that the curing accelerator has an extremely significant promoting effect on the curing reaction speed of the silicone sealant, and at the same time has a certain positive improvement effect on the mechanical strength of the cured colloid.

[0225] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A mildew-proof silicone sealant with high curing rate and high adhesion, characterized in that: The raw material composition of the mildew-proof silicone sealant with high curing rate and high adhesion includes α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, phenoxy resin-coated nano calcium carbonate, modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent, dibutyltin dilaurate, methyltrimethoxysilane, and a curing accelerator; The curing accelerator is one of acetohydroxamic acid (N-hydroxyacetamide), acetylhydroxylamine, O-methoxy-N-acetylhydroxylamine, O-(tert-butyldimethylsilyl)hydroxylamine, N-hydroxyacetamide, O-(trimethylsilyl)hydroxylamine, N-isopropylhydroxylamine, N-tert-butylhydroxylamine; The preparation method of the phenoxy resin-coated nano calcium carbonate is as follows: After the nano calcium carbonate is thoroughly dried, it is added to a dispersion reaction kettle together with an oleate dispersant and a ketone solvent, and strongly stirred and dispersed until the average particle size of the nano calcium carbonate particles is below 500 nm. Then, the temperature is raised and kept at the reaction temperature, and under the condition of uniform stirring and maintaining the condensation reflux state, a silane coupling agent containing an isocyanate group is added. After the silane coupling agent reacts completely, a ketone solution of phenoxy resin is added, and the stirring reaction continues until the phenoxy resin reacts completely. Then, the temperature is lowered to room temperature, and centrifuged. The separated solid is washed with absolute ethanol and dried to obtain phenoxy resin-coated nano calcium carbonate; The preparation method of the modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent is as follows: First, the mildew-proof agent is dissolved in acetone to form a saturated solution to obtain an acetone solution of the mildew-proof agent. Then, hydroxypropyl-γ-cyclodextrin is dissolved in deionized water to form a saturated solution to obtain an aqueous solution of hydroxypropyl-γ-cyclodextrin. Under heating and constant temperature stirring, the acetone solution of the mildew-proof agent is dropped into the aqueous solution of hydroxypropyl-γ-cyclodextrin. After dropping, the stirring reaction continues until the loading is complete. Then, the temperature is lowered to room temperature, and the reaction liquid is refrigerated, crystallized, filtered, and vacuum dried to obtain hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent. Then, the hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent and absolute ethanol are added to a reaction kettle, stirred and dissolved, and the temperature is raised and kept at the reaction temperature. Then, a silane coupling agent containing an amino group is added. After the stirring reaction is complete, the temperature is lowered to room temperature, and after refrigeration, crystallization, filtration, and vacuum drying, the modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent is obtained.

2. The mildew-proof silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: The raw material composition of the mildew-proof silicone sealant with high curing rate and high adhesion, in parts by weight, is composed of 170 - 290 parts of α,ω-dihydroxypolydimethylsiloxane, 20 - 50 parts of dimethyl silicone oil, 1 - 4 parts of fumed silica, 35 - 65 parts of phenoxy resin-coated nano calcium carbonate, 8 - 15 parts of modified hydroxypropyl-γ-cyclodextrin loaded with mildew-proof agent, 1 - 2.5 parts of dibutyltin dilaurate, 10 - 20 parts of methyltrimethoxysilane, and 1 - 4 parts of curing accelerator.

3. The mildew-proof silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: The particle size of the fumed silica is 1 to 100 nm; The particle size of the nano calcium carbonate is 1 to 100 nm; The oleate dispersant is one of oleyl linoleate, decyl oleate, and polyethylene glycol dioleate; The ketone solvent is one of acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; The isocyanate group-containing silane coupling agent is one of 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane; For the ketone solution of phenoxy resin, the mass fraction of phenoxy resin is 5 to 13 wt%, and the ketone solvent in the ketone solution is one of acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; The number average molecular weight of the phenoxy resin is 25,000 to 35,000 g / mol.

4. The anti-mold silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: For the nano calcium carbonate, oleate dispersant, ketone solvent, isocyanate group-containing silane coupling agent, and ketone solution of phenoxy resin, the feeding mass ratio of the above substances is 13 to 35: 0.5 to 2: 150 to 360: 3 to 11: 50 to 140.

5. The anti-mold silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: The anti-mold agent is one of bitertanol, benzothiazole cyanide, and didodecyldimethylammonium chloride, a mixture composed of any two in any mass ratio, and a mixture composed of any three in any mass ratio; The amino group-containing silane coupling agent is one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; The acetone solution of the anti-mold agent is dropped into the aqueous solution of hydroxypropyl-γ-cyclodextrin at a dropping rate of 10 to 40 g / min; For the acetone solution of the anti-mold agent and the aqueous solution of hydroxypropyl-γ-cyclodextrin, the mass ratio of the two is 25 to 50:

73.

6. The anti-mold silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: For the hydroxypropyl-γ-cyclodextrin loaded with anti-mold agent, absolute ethanol, and amino group-containing silane coupling agent, the mass ratio of the three is 15 to 40: 160 to 550: 3 to 13.

7. The anti-mold silicone sealant with high curing rate and high adhesion according to claim 1, characterized in that: The preparation method of the anti-mildew silicone sealant with high curing rate and high adhesion is as follows: According to the composition ratio of the anti-mildew silicone sealant with high curing rate and high adhesion by weight, put α,ω-dihydroxypolydimethylsiloxane, dimethyl silicone oil, fumed silica, nano calcium carbonate coated with phenoxy resin, modified hydroxypropyl-γ-cyclodextrin loaded with mildew inhibitor, dibutyltin dilaurate, methyltrimethoxysilane, and curing accelerator into a dry double planetary mixer. Keep the vacuum negative pressure in the double planetary mixer at -0.1~-0.095 MPa, control the stirring rate at 100~150 revolutions per minute and the dispersion rate at 10,000~15,000 revolutions per minute. After stirring and dispersing for 12~16 hours, a viscous gel is obtained. After continuous vacuum degassing, discharge the material, fill the bubble-free gel into a dry packaging container, fill it with nitrogen for protection and seal it, and it is the anti-mildew silicone sealant with high curing rate and high adhesion.

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