Deacetic mildew-proof silicone sealant and preparation method thereof

Abstract

The invention discloses a deacetic mildew-proof silicone sealant and a preparation method thereof, and relates to the technical field of silicone adhesives. The mildew-proof silicone sealant is prepared from the following raw materials: hydroxyl-terminated polydimethylsiloxane, fumed silica, simethicone, methyl silicone resin coated octyl isothiazolinone microcapsules, a cross-linking agent, a catalyst, a silane coupling agent, an antioxidant, iodopropynyl butyl carbamate and amino modified silicon dioxide. The preparation method of the mildew-proof silicone sealant comprises the following steps: preparing the methyl silicone resin coated octyl isothiazolinone microcapsule, preparing the base adhesive, and preparing the mildew-proof silicone sealant. The mildew-proof silicone sealant prepared by the invention is good in long-acting mildew-proof effect and excellent in mildew-proof stability.

Description

Technical Field

[0001] This invention relates to the field of silicone sealant technology, specifically to a deacetic acid-free anti-mildew silicone sealant and its preparation method. Background Technology

[0002] Acetic acid-free silicone sealants are widely used in building door and window joints, kitchen and bathroom renovations, and appliance sealing due to their excellent adhesion, weather resistance, and ease of application. Especially in humid and dark environments, their anti-mildew properties directly determine the product's lifespan and user experience, making them one of the core indicators for evaluating the quality of this type of sealant.

[0003] Currently, the industry typically achieves anti-mold functionality by adding organic antifungal agents (such as isothiazolinones and benzimidazoles) or inorganic antifungal agents (such as nano-silver and zinc oxide) to the sealant matrix. However, existing technologies have significant drawbacks: organic antifungal agents are prone to migration and volatilization, leading to a rapid decline in their anti-mold effect over time; inorganic antifungal agents are prone to uneven dispersion in silicone sealant systems, resulting in unstable anti-mold effects. Existing technology CN117089317A discloses a long-lasting antibacterial and antifungal silicone sealant and its preparation method. This technology uses β-cyclodextrin to encapsulate the antifungal agent, resulting in weak bonding with the silicone crosslinking network, and acetic acid may accelerate the degradation of the antifungal agent, leading to insufficient long-term stability. Existing technology CN119875573A discloses a transparent deacidified long-lasting antifungal silicone sealant. This technology directly adds the antifungal agent, resulting in limited long-lasting antifungal effect, and it is prone to migration and loss during long-term use, failing to meet long-term requirements.

[0004] In summary, although the existing technical solutions have improved some properties of anti-mildew silicone sealants to a certain extent, the following technical problems still exist: limited long-term anti-mildew effect and insufficient anti-mildew stability. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides an acetic acid-free anti-mildew silicone sealant and its preparation method, and achieves the following objectives: to prepare an anti-mildew silicone sealant with good long-lasting anti-mildew effect and excellent anti-mildew stability.

[0006] To achieve the above objectives, the following technical solution is adopted: An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 80-90 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of fumed silica, 10-15 parts of dimethyl silicone oil, 1.5-2 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 5-10 parts of crosslinking agent, 0.2-0.5 parts of catalyst, 1-2 parts of silane coupling agent, 0.3-0.5 parts of antioxidant, 0.2-0.4 parts of iodopropynyl urethane, and 0.3-0.5 parts of amino-modified silica.

[0007] The crosslinking agent is methyltriacetoxysilane.

[0008] The catalyst is dibutyltin dilaurate.

[0009] The amino-modified silica is silica modified with silane coupling agent KH550.

[0010] The present invention also provides a method for preparing an acetic acid-free anti-mildew silicone sealant, comprising the steps of preparing methyl silicone resin-coated octylisothiazolinone microcapsules, preparing a base adhesive, and obtaining the anti-mildew silicone sealant. The preparation of methyl silicone resin-coated octylisothiazolinone microcapsules involves mixing methyltrimethoxysilane with anhydrous ethanol, placing the mixture in an ice-water bath, adding ammonia solution dropwise, and reacting to obtain a methyltrimethoxysilane pre-hydrolyzed solution. The emulsifier was dissolved in deionized water, and octylisothiazolinone was added and stirred to obtain an octylisothiazolinone emulsion. The pH of the emulsion was adjusted, and methyltrimethoxysilane pre-hydrolyzed solution was added dropwise. The temperature was then raised to allow the reaction to proceed. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried to obtain methyl silicone resin-coated octylisothiazolinone microcapsules. The emulsifier was sodium dodecylbenzenesulfonate.

[0011] Furthermore, the mass ratio of methyltrimethoxysilane to anhydrous ethanol is 1:(1-2); the mass ratio of ammonia solution to methyltrimethoxysilane is (0.25-3):1.

[0012] Furthermore, the mass ratio of the emulsifier to deionized water is (0.2-0.5):100; the mass ratio of the octylisothiazolinone to the emulsifier is 20:(1-2); and the mass ratio of the methyltrimethoxysilane pre-hydrolyzed solution to the octylisothiazolinone emulsion is 1:(1.8-2).

[0013] Further, methyltrimethoxysilane was mixed with anhydrous ethanol and placed in an ice-water bath. Stirring was started at 100-200 rpm, and an ammonia solution was added dropwise. After the addition was complete, the reaction was allowed to proceed for 1-2 hours to obtain a pre-hydrolyzed methyltrimethoxysilane solution. The ammonia solution had a mass fraction of 10%.

[0014] The emulsifier was dissolved in deionized water, and octylisothiazolinone was added at a mass ratio of 20:(1-2) to the emulsifier. The mixture was stirred for 15-20 minutes at a speed of 1000-1500 rpm to obtain an octylisothiazolinone emulsion. Ammonia was added to adjust the pH of the emulsion to 9-10, and the stirring speed was adjusted to 500-600 rpm. Methyltrimethoxysilane pre-hydrolyzed solution was added dropwise at a rate of 1-2 drops / s. After the addition was complete, the temperature was slowly raised to 40-50℃, and the reaction was allowed to proceed for 12-16 hours. After the reaction was completed, the mixture was cooled to room temperature, and the solid was collected by vacuum filtration. The solid was washed 3-5 times alternately with deionized water and ethanol, and then vacuum dried at 40-50℃ for 22-24 hours to obtain methyl silicone resin-coated octylisothiazolinone microcapsules. The emulsifier was sodium dodecylbenzenesulfonate.

[0015] Preparation of the base colloid: Hydroxyl-terminated polydimethylsiloxane is added to a mixer, followed by fumed silica and dimethyl silicone oil. The mixture is heated, vacuumed, and stirred. Vacuum is maintained, the mixture is cooled, and antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl butyl carbamate are added. The mixture is stirred to obtain the base colloid.

[0016] Further, hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer, and stirring was started at a speed of 50-100 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 100-120℃, the speed was increased to 300-500 rpm, and the vacuum degree was -0.09MPa to -0.095MPa. The mixture was stirred for 2-3 hours. The vacuum was maintained, the speed was reduced to 100-200 rpm, and the temperature was reduced to below 50℃. Then, antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl urethane were added in sequence, and the mixture was stirred for 1-1.5 hours to obtain the basic colloid.

[0017] The anti-mildew silicone sealant was prepared by: purging the mixer with nitrogen gas and setting the speed to 80-120 rpm; adding a crosslinking agent, a catalyst, and a silane coupling agent to the base colloid and stirring; and then degassing to obtain the anti-mildew silicone sealant.

[0018] Furthermore, under nitrogen protection in the planetary mixer, the speed is set to 80-120 rpm. A crosslinking agent is added to the base colloid, and the mixture is stirred for 30-40 minutes. Then, a catalyst is added, and stirring continues for 40-60 minutes. A silane coupling agent is added, and stirring continues for another 30-40 minutes. Then, a vacuum is applied again to a vacuum level of -0.09 MPa to -0.095 MPa, and degassing is performed for 20-30 minutes. Finally, under nitrogen protection, the mixture is passed through an 80-120 mesh filter and pressed into a sealing hose or aluminum tube to obtain an anti-mildew silicone sealant.

[0019] The beneficial effects of this invention are as follows: (1) The acetic acid-free anti-mildew silicone sealant of the present invention has excellent long-lasting anti-mildew effect. After 15 days, 30 days and 60 days of curing, the anti-mildew silicone sealant prepared still has an anti-mildew level of 0.

[0020] (2) The acetic acid-free anti-mildew silicone sealant of the present invention has excellent anti-mildew stability. After heat aging for 14 days, the anti-mildew level of the prepared anti-mildew silicone sealant is 0. After humid heat aging for 14 days, the anti-mildew level is 0-1. Attached Figure Description

[0021] Appendix Figure 1 This is a scanning electron microscope image of the methyl silicone resin-coated octylisothiazolinone microcapsules prepared in this invention.

[0022] Appendix Figure 2 This is a particle size distribution diagram of the methyl silicone resin-coated octylisothiazolinone microcapsules prepared in this invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] Example 1: An acetic acid-free antifungal silicone sealant and its preparation method An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 80 parts of hydroxyl-terminated polydimethylsiloxane, 20 parts of fumed silica, 10 parts of dimethyl silicone oil, 1.5 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 5 parts of crosslinking agent, 0.2 parts of catalyst, 1 part of silane coupling agent, 0.3 parts of antioxidant, 0.4 parts of iodopropynyl urethane, and 0.3 parts of amino-modified silica.

[0025] The crosslinking agent is methyltriacetoxysilane.

[0026] The catalyst is dibutyltin dilaurate.

[0027] The silane coupling agent selected is silane coupling agent KH550.

[0028] The antioxidant used is antioxidant 1010.

[0029] The amino-modified silica is silica modified with silane coupling agent KH550.

[0030] A method for preparing an acetic acid-free, mildew-resistant silicone sealant includes the following steps: Step 1: Preparation of methyl silicone resin-coated octylisothiazolinone microcapsules Methyltrimethoxysilane was mixed with anhydrous ethanol and placed in an ice-water bath at a mass ratio of 1:1. Stirring was started at 100 rpm, and an ammonia solution was added dropwise at a mass ratio of 0.25:1 to methyltrimethoxysilane. After the addition was complete, the reaction was allowed to proceed for 2 hours to obtain a pre-hydrolyzed methyltrimethoxysilane solution. The ammonia solution had a mass fraction of 10%.

[0031] The emulsifier was dissolved in deionized water at a mass ratio of 0.2:100, and stirred until the emulsifier was completely dissolved. Octylisothiazolinone was slowly added at a mass ratio of 20:1 to the emulsifier, and stirred for 15 minutes at 1500 rpm to obtain an octylisothiazolinone emulsion. Ammonia was added to adjust the pH of the emulsion to 9, and the stirring speed was adjusted to 500 rpm. Methyltrimethoxysilane pre-hydrolyzed solution was added dropwise at a rate of 1 drop / s, with a mass ratio of methyltrimethoxysilane pre-hydrolyzed solution to octylisothiazolinone emulsion of 1:1.8. After the addition was complete, the temperature was slowly raised to 40°C, and the reaction was carried out for 16 hours. After the reaction was completed, the mixture was cooled to room temperature, and the solid was collected by vacuum filtration. The solid was washed three times alternately with deionized water and ethanol, and then vacuum dried at 40°C for 24 hours to obtain methyl silicone resin-coated octylisothiazolinone microcapsules. The emulsifier was sodium dodecylbenzenesulfonate.

[0032] Step 2: Preparation of Base Gel Hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer and stirred at 50 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 100°C, the stirring speed was increased to 300 rpm, the vacuum degree was -0.09 MPa, and the mixture was stirred for 3 hours. While maintaining the vacuum, the stirring speed was reduced to 100 rpm and the temperature was lowered to below 50°C. Then, antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl urethane were added in sequence and stirred for 1.5 hours to obtain the basic colloid.

[0033] Step 3: Prepare anti-mildew silicone sealant Under nitrogen protection, the planetary mixer was set to 80 rpm. A crosslinking agent was added to the base colloid and stirred for 40 minutes. Then, a catalyst was added and stirring continued for 60 minutes. A silane coupling agent was added and stirring continued for 40 minutes. The vacuum was then turned on again to -0.09 MPa for degassing for 30 minutes. Then, under nitrogen protection, the mixture was passed through an 80-120 mesh filter and pressed into a sealing hose or aluminum tube to obtain an anti-mildew silicone sealant.

[0034] Example 2: An acetic acid-free antifungal silicone sealant and its preparation method An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 85 parts of hydroxyl-terminated polydimethylsiloxane, 15 parts of fumed silica, 13 parts of dimethyl silicone oil, 2 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 8 parts of crosslinking agent, 0.4 parts of catalyst, 1.5 parts of silane coupling agent, 0.4 parts of antioxidant, 0.3 parts of iodopropynyl urethane, and 0.5 parts of amino-modified silica.

[0035] The crosslinking agent is methyltriacetoxysilane.

[0036] The catalyst is dibutyltin dilaurate.

[0037] The silane coupling agent selected is silane coupling agent KH550.

[0038] The antioxidant used is antioxidant 1010.

[0039] The amino-modified silica is silica modified with silane coupling agent KH550.

[0040] A method for preparing an acetic acid-free, mildew-resistant silicone sealant includes the following steps: Step 1: Preparation of methyl silicone resin-coated octylisothiazolinone microcapsules Methyltrimethoxysilane was mixed with anhydrous ethanol and placed in an ice-water bath at a mass ratio of 1:2. Stirring was started at 200 rpm, and an ammonia solution was added dropwise at a mass ratio of 0.25:1 to methyltrimethoxysilane. After the addition was complete, the reaction was allowed to proceed for 2 hours to obtain a pre-hydrolyzed methyltrimethoxysilane solution. The ammonia solution had a mass fraction of 10%.

[0041] The emulsifier was dissolved in deionized water at a mass ratio of 0.4:100, and stirred until completely dissolved. Octylisothiazolinone was slowly added at a mass ratio of 20:2 to the emulsifier, and stirred for 20 minutes at 1500 rpm to obtain an octylisothiazolinone emulsion. Ammonia was added to adjust the pH of the emulsion to 10, and the stirring speed was adjusted to 600 rpm. Methyltrimethoxysilane pre-hydrolyzed solution was added dropwise at a rate of 2 drops / s, with a mass ratio of methyltrimethoxysilane pre-hydrolyzed solution to octylisothiazolinone emulsion of 1:2. After the addition was complete, the temperature was slowly raised to 50°C, and the reaction was allowed to proceed for 14 hours. After the reaction was completed, the mixture was cooled to room temperature, and the solid was collected by vacuum filtration. The solid was washed five times alternately with deionized water and ethanol, and then vacuum dried at 50°C for 24 hours to obtain methylsilicone resin-coated octylisothiazolinone microcapsules. The emulsifier was sodium dodecylbenzenesulfonate.

[0042] Step 2: Preparation of Base Gel Hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer and stirred at 100 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 110°C, the stirring speed was increased to 400 rpm, the vacuum degree was -0.095 MPa, and the mixture was stirred for 3 hours. The vacuum was maintained, the stirring speed was reduced to 100 rpm, and the temperature was reduced to below 50°C. Then, antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl urethane were added in sequence, and the mixture was stirred for 1.5 hours to obtain the basic colloid.

[0043] Step 3: Prepare anti-mildew silicone sealant Under nitrogen protection, the planetary mixer was set to 100 rpm. A crosslinking agent was added to the base colloid and stirred for 40 minutes. Then, a catalyst was added and stirring continued for 60 minutes. A silane coupling agent was added and stirring continued for 40 minutes. The vacuum was then turned on again to -0.095 MPa for degassing for 30 minutes. Finally, under nitrogen protection, the mixture was passed through an 80-120 mesh filter and pressed into a sealing hose or aluminum tube to obtain an anti-mildew silicone sealant.

[0044] Example 3: An acetic acid-free antifungal silicone sealant and its preparation method An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 90 parts of hydroxyl-terminated polydimethylsiloxane, 10 parts of fumed silica, 15 parts of dimethyl silicone oil, 2 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 10 parts of crosslinking agent, 0.5 parts of catalyst, 2 parts of silane coupling agent, 0.5 parts of antioxidant, 0.2 parts of iodopropynyl urethane, and 0.5 parts of amino-modified silica.

[0045] The crosslinking agent is methyltriacetoxysilane.

[0046] The catalyst is dibutyltin dilaurate.

[0047] The silane coupling agent selected is silane coupling agent KH550.

[0048] The antioxidant used is antioxidant 1010.

[0049] The amino-modified silica is silica modified with silane coupling agent KH550.

[0050] A method for preparing an acetic acid-free, mildew-resistant silicone sealant includes the following steps: Step 1: Preparation of methyl silicone resin-coated octylisothiazolinone microcapsules Methyltrimethoxysilane was mixed with anhydrous ethanol and placed in an ice-water bath at a mass ratio of 1:2. Stirring was started at 200 rpm, and an ammonia solution was added dropwise at a mass ratio of 3:1 to methyltrimethoxysilane. After the addition was complete, the reaction proceeded for 1 hour to obtain a pre-hydrolyzed methyltrimethoxysilane solution. The ammonia solution had a mass fraction of 10%.

[0051] The emulsifier was dissolved in deionized water at a mass ratio of 0.5:100, and stirred until completely dissolved. Octylisothiazolinone was slowly added at a mass ratio of 20:2 to the emulsifier, and stirred for 20 minutes at 1000 rpm to obtain an octylisothiazolinone emulsion. Ammonia was added to adjust the pH of the emulsion to 10, and the stirring speed was adjusted to 600 rpm. Methyltrimethoxysilane pre-hydrolyzed solution was added dropwise at a rate of 2 drops / s, with a mass ratio of methyltrimethoxysilane pre-hydrolyzed solution to the octylisothiazolinone emulsion of 1:2. After the addition was complete, the temperature was slowly raised to 50°C, and the reaction was allowed to proceed for 12 hours. After the reaction, the mixture was cooled to room temperature, and the solid was collected by filtration. The solid was washed five times alternately with deionized water and ethanol, and then vacuum dried at 50°C for 22 hours to obtain methyl silicone resin-coated octylisothiazolinone microcapsules. The emulsifier was sodium dodecylbenzenesulfonate.

[0052] Step 2: Preparation of Base Gel Hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer and stirred at 100 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 120°C, the stirring speed was increased to 500 rpm, the vacuum degree was -0.095 MPa, and the mixture was stirred for 2 hours. The vacuum was maintained, the stirring speed was reduced to 200 rpm, and the temperature was reduced to below 50°C. Then, antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl urethane were added in sequence, and the mixture was stirred for 1 hour to obtain the basic colloid.

[0053] Step 3: Prepare anti-mildew silicone sealant Under nitrogen protection, the planetary mixer was set to 120 rpm. A crosslinking agent was added to the base colloid and stirred for 30 minutes. Then, a catalyst was added and stirring continued for 40 minutes. A silane coupling agent was added and stirring continued for 30 minutes. The vacuum was then turned on again to -0.095 MPa for degassing for 20 minutes. Then, under nitrogen protection, the mixture was passed through an 80-120 mesh filter and pressed into a sealing hose or aluminum tube to obtain an anti-mildew silicone sealant.

[0054] Comparative Example 1 An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 85 parts of hydroxyl-terminated polydimethylsiloxane, 15 parts of fumed silica, 13 parts of dimethyl silicone oil, 8 parts of crosslinking agent, 0.4 parts of catalyst, 1.5 parts of silane coupling agent, 0.4 parts of antioxidant, 0.3 parts of iodopropynyl urethane, and 0.5 parts of amino-modified silica.

[0055] The crosslinking agent is methyltriacetoxysilane.

[0056] The catalyst is dibutyltin dilaurate.

[0057] The silane coupling agent selected is silane coupling agent KH550.

[0058] The antioxidant used is antioxidant 1010.

[0059] The amino-modified silica is silica modified with silane coupling agent KH550.

[0060] A method for preparing an acetic acid-free, mildew-resistant silicone sealant includes the following steps: Step 1: Preparation of Base Gel Hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer and stirred at 100 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 110°C, the stirring speed was increased to 400 rpm, the vacuum degree was -0.095 MPa, and the mixture was stirred for 3 hours. The vacuum was maintained, the stirring speed was reduced to 100 rpm, and the temperature was lowered to below 50°C. Then, antioxidants, amino-modified silica, and iodopropynyl urethane were added in sequence, and the mixture was stirred for 1.5 hours to obtain the basic colloid.

[0061] Step 2: Prepare anti-mildew silicone sealant This step is the same as the "preparation of anti-mildew silicone sealant" step in Example 2.

[0062] Comparative Example 2 An acetic acid-free antifungal silicone sealant, by weight, comprises the following raw materials: 85 parts of hydroxyl-terminated polydimethylsiloxane, 15 parts of fumed silica, 13 parts of dimethyl silicone oil, 2 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 8 parts of crosslinking agent, 0.4 parts of catalyst, 1.5 parts of silane coupling agent, 0.4 parts of antioxidant, and 0.5 parts of amino-modified silica.

[0063] The crosslinking agent is methyltriacetoxysilane.

[0064] The catalyst is dibutyltin dilaurate.

[0065] The silane coupling agent selected is silane coupling agent KH550.

[0066] The antioxidant used is antioxidant 1010.

[0067] The amino-modified silica is silica modified with silane coupling agent KH550.

[0068] A method for preparing an acetic acid-free, mildew-resistant silicone sealant includes the following steps: Step 1: Preparation of methyl silicone resin-coated octylisothiazolinone microcapsules This step is the same as the step in Example 2, "Preparation of methyl silicone resin-coated octylisothiazolinone microcapsules".

[0069] Step 2: Preparation of Base Gel Hydroxyl-terminated polydimethylsiloxane was added to a planetary mixer and stirred at 100 rpm. Then, fumed silica and dimethyl silicone oil were added, the temperature was raised to 110°C, the stirring speed was increased to 400 rpm, the vacuum degree was -0.095 MPa, and the mixture was stirred for 3 hours. The vacuum was maintained, the stirring speed was reduced to 100 rpm, and the temperature was reduced to below 50°C. Then, antioxidants, amino-modified silica, and octylisothiazolinone microcapsules coated with methyl silicone resin were added in sequence, and the mixture was stirred for 1.5 hours to obtain the basic colloid.

[0070] Step 3: Prepare anti-mildew silicone sealant This step is the same as the "preparation of anti-mildew silicone sealant" step in Example 2.

[0071] Example 4 Performance Testing (a) In accordance with GB / T 1741 The anti-mold effect of the anti-mold silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 was tested according to the test methods specified in 2020. Typical molds such as Aspergillus niger, Aspergillus flavus, and Trichoderma were selected. The curing time was 15 days, 30 days, and 60 days, the temperature was 30°C, and the relative humidity was 60%. The anti-mold effect of the antibacterial and anti-mold silicone sealants prepared in this application was tested. The specific test results are shown in Table 1.

[0072] Table 1 As shown in Table 1, the anti-mold silicone sealants prepared in Examples 1-3 maintained an anti-mold rating of 0 after 15, 30, and 60 days of curing, demonstrating a significantly enhanced anti-mold effect compared to the comparative examples. This proves that the anti-mold silicone sealant prepared in this invention has excellent long-lasting anti-mold properties.

[0073] (II) After the anti-mildew silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 are subjected to heat aging and damp heat aging, they are then processed according to GB / T 1741. The test method specified in 2020 was used to test the anti-mildew effect of the sealant after initial, thermal aging, and damp heat aging. Thermal aging conditions: temperature 70℃, time 14 days; damp heat aging conditions: temperature 50℃, humidity 95%RH, time 14 days. Specific test results are shown in Table 2.

[0074] Table 2 As shown in Table 2, the anti-mold silicone sealants prepared in Examples 1-3 have an anti-mold rating of 0 after 14 days of heat aging, and an anti-mold rating of 0-1 after 14 days of humid heat aging. This demonstrates that the anti-mold silicone sealant prepared in this invention has excellent anti-mold stability.

[0075] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A method for preparing an acetic acid-free antifungal silicone sealant, characterized in that: The steps include preparing methyl silicone resin-coated octylisothiazolinone microcapsules, preparing the base adhesive, and obtaining the anti-mildew silicone sealant. The raw materials used include: hydroxyl-terminated polydimethylsiloxane, fumed silica, dimethyl silicone oil, methyl silicone resin-coated octylisothiazolinone microcapsules, crosslinking agent, catalyst, silane coupling agent, antioxidant, iodopropynylcarbamate, and amino-modified silica; the crosslinking agent is methyltriacetoxysilane; the catalyst is dibutyltin dilaurate. The preparation of methyl silicone resin-coated octylisothiazolinone microcapsules involves mixing methyltrimethoxysilane with anhydrous ethanol, placing the mixture in an ice-water bath, adding ammonia solution dropwise, and reacting for 1-2 hours to obtain a methyltrimethoxysilane pre-hydrolyzed solution. Dissolve the emulsifier in deionized water, add octylisothiazolinone, stir to obtain octylisothiazolinone emulsion; adjust the pH of the emulsion and add methyltrimethoxysilane prehydrolysate dropwise. Then the temperature is raised to 40-50℃ and the reaction is carried out for 12-16 hours. After the reaction is completed, the mixture is cooled to room temperature, the solid is collected by filtration, and after washing and drying, methyl silicone resin-coated octylisothiazolinone microcapsules are obtained. The emulsifier is sodium dodecylbenzenesulfonate.

2. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The raw materials used are composed of the following components by weight: 80-90 parts of hydroxyl-terminated polydimethylsiloxane, 10-20 parts of fumed silica, 10-15 parts of dimethyl silicone oil, 1.5-2 parts of methyl silicone resin-coated octylisothiazolinone microcapsules, 5-10 parts of crosslinking agent, 0.2-0.5 parts of catalyst, 1-2 parts of silane coupling agent, 0.3-0.5 parts of antioxidant, 0.2-0.4 parts of iodopropynyl urethane, and 0.3-0.5 parts of amino-modified silica.

3. The preparation method of the acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The mass ratio of methyltrimethoxysilane to anhydrous ethanol is 1:(1-2); the mass ratio of ammonia solution to methyltrimethoxysilane is (0.25-3):

1.

4. The preparation method of the acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The mass ratio of the emulsifier to deionized water is (0.2-0.5):

100.

5. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The mass ratio of octylisothiazolinone to emulsifier is 20:(1-2).

6. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: Adjusting the pH of the emulsion: Add ammonia to adjust the pH of the emulsion to 9-10.

7. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The mass ratio of the methyltrimethoxysilane prehydrolysate to the octylisothiazolinone emulsion is 1:(1.8-2).

8. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The washing process involves washing the solid with deionized water and ethanol alternately 3-5 times.

9. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: Preparation of the base colloid: Hydroxyl-terminated polydimethylsiloxane is added to a mixer, followed by fumed silica and dimethyl silicone oil. The mixture is heated, vacuumed, and stirred. Vacuum is maintained, the mixture is cooled, and antioxidants, amino-modified silica, methyl silicone resin-coated octylisothiazolinone microcapsules, and iodopropynyl butyl carbamate are added. The mixture is stirred to obtain the base colloid.

10. The method for preparing an acetic acid-free antifungal silicone sealant according to claim 1, characterized in that: The anti-mildew silicone sealant was prepared by: purging the mixer with nitrogen gas and setting the speed to 80-120 rpm; adding a crosslinking agent, a catalyst, and a silane coupling agent to the base colloid and stirring; and then degassing to obtain the anti-mildew silicone sealant.

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