Ketoxime-removing type matte organic silicon sealant and preparation method thereof
By designing composite crosslinking agents and fillers and controlling the crosslinking reaction rate to form a uniform network structure, the problems of insufficient matte effect and storage stability of deketoxime type silicone sealants in the prior art have been solved, achieving excellent mechanical properties and long-term stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG JINGMAO NEW MATERIAL CO LTD
- Filing Date
- 2026-04-14
- Publication Date
- 2026-05-12
AI Technical Summary
Existing deketoxime type silicone sealants have shortcomings in terms of matte finish, mechanical properties, and storage stability, and cannot simultaneously achieve a stable matte finish, excellent mechanical properties, and excellent storage stability.
A composite crosslinking agent consisting of methyltributylone oxime silane and methyltris(methylisobutylone oxime) silane is used, which combines with the reversible weak coordination bond of heptanoic acid to regulate the crosslinking reaction rate. Modified nano-calcium carbonate and barium sulfate are added as fillers to form a uniform network structure.
A silicone sealant with a stable matte finish, excellent mechanical properties and storage stability was achieved. The tensile strength is 3.76-3.91 MPa, the elongation at break is 418-431%, and the performance remains stable after 30-60 days of storage.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of sealant technology, specifically to a ketoxime-based matte silicone sealant and its preparation method. Background Technology
[0002] Ketoxime-based silicone sealants are widely used in building decoration, automotive manufacturing, and electronic component packaging due to their ability to cure at room temperature without light, excellent weather resistance, and good adhesion to various substrates. However, with the continuous expansion and increasing sophistication of applications, the market is placing more stringent demands on the overall performance of sealants, revealing many limitations of traditional formulations and technologies that urgently need to be addressed.
[0003] In existing products, the industry commonly uses single ketoxime crosslinking agents such as methyl tributanone oxime silane. The crosslinking reaction activity and rate are difficult to precisely control, affecting not only the stability of the matte finish but also causing problems such as increased viscosity and slow curing after long-term storage, severely restricting product shelf life and reliability. Existing technology CN118931481A discloses a high-performance matte silicone sealant and its preparation method. This prior art is mainly a dealcoholized system, which has slow curing speed at low temperatures and insufficient storage stability. Existing technology CN119684962A discloses a long-shelf-life two-component silicone sealant and its preparation method. While this prior art can achieve long-term storage, it is a two-component system, lacking ease of application and the design for a matte finish.
[0004] In summary, although existing technical solutions have improved certain properties of silicone sealants to some extent, they still have the following technical problems: they cannot simultaneously achieve a stable matte finish, excellent mechanical properties, and excellent storage stability. Summary of the Invention
[0005] In order to solve the above-mentioned problems in the prior art, the present invention provides a ketoxime-type matte silicone sealant and its preparation method, and achieves the following objectives: to prepare a silicone sealant with stable matte effect, good mechanical properties and excellent storage stability.
[0006] To achieve the above objectives, the following technical solution is adopted: A method for preparing a ketoxime-type matte silicone sealant includes the steps of pre-preparing functional components, dispersing basic fillers, adding crosslinking agents and additives, and obtaining the silicone sealant. The raw materials used are formulated in the following weight ratios: 55-85 parts α,ω-dihydroxypolydimethylsiloxane, 10-30 parts dimethyl silicone oil, 10-20 parts fumed silica, 80-120 parts modified nano calcium carbonate, 2-5 parts barium sulfate, 5-12 parts composite crosslinking agent, 0.3-0.8 parts dibutyltin dilaurate, 0.1-0.3 parts heptanoic acid, 1.5-4.5 parts silane coupling agent mixture, 0.3-1 part diphenyldimethoxysilane, 0.1-0.5 parts antioxidant, and 0.1-0.3 parts defoamer.
[0007] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0008] The particle size of the fumed silica is 12-20 nm.
[0009] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0010] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0011] The functional components were pre-prepared as follows: Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane were mixed and stirred until homogeneous; deionized water and acetic acid were added dropwise, and the mixture was kept at a constant temperature for reaction, followed by vacuum dehydration to obtain a composite crosslinking agent; nano-calcium carbonate and zinc stearate were mixed until homogeneous, heated, and stirred to obtain modified nano-calcium carbonate; silane coupling agent KH-560 and silane coupling agent KH-792 were mixed until homogeneous to obtain a silane coupling agent mixture.
[0012] Furthermore, the mass ratio of methyltributanone oxime silane to methyltris(methylisobutyl ketone oxime) silane is (6-7):(3-4). The amount of deionized water used is 1-1.5% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The amount of acetic acid used is 0.05-0.15% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The vacuum dehydration is performed at a temperature of 80-90℃, a vacuum degree of -0.095MPa to -0.098MPa, and a dehydration time of 1-2 hours.
[0013] Furthermore, the amount of zinc stearate used is 1.5-2% of the mass of nano-calcium carbonate; the mass ratio of silane coupling agent KH-560 to silane coupling agent KH-792 is (1.8-2):1.
[0014] Further, the functional components are pre-prepared as follows: Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane are mixed and stirred until homogeneous; then, while maintaining a stirring speed of 300-400 rpm, deionized water and acetic acid are added dropwise, the temperature is raised to 50-60℃, and the reaction is maintained for 3-4 hours. After the reaction, the mixture is dehydrated under vacuum to obtain a composite crosslinking agent; nano-calcium carbonate and zinc stearate are mixed evenly, the temperature is raised to 40-60℃, and the mixture is stirred for 30-40 minutes at a speed of 1000-1500 rpm to obtain modified nano-calcium carbonate. The nano-calcium carbonate has a particle size of 80-100 nm; silane coupling agent KH-560 and silane coupling agent KH-792 are mixed evenly to obtain a silane coupling agent mixture.
[0015] The basic filler dispersion is as follows: α,ω-dihydroxypolydimethylsiloxane and dimethyl silicone oil are stirred evenly; then fumed silica is added, the temperature is raised, the stirred tank is evacuated, and the mixture is stirred; then the temperature is lowered, modified nano-calcium carbonate and barium sulfate are added, and the mixture is stirred.
[0016] Further, the basic filler dispersion is as follows: α,ω-dihydroxypolydimethylsiloxane and dimethyl silicone oil are added to a stirred tank, and stirring is started for 5-10 minutes at a speed of 300-500 rpm; then fumed silica is added, the temperature is raised to 100-120℃, the stirred tank is evacuated to a vacuum degree of -0.095MPa to -0.098MPa, the stirring speed is increased to 800-1000 rpm, and stirring is carried out for 1-2 hours; then the temperature is slowly lowered to 80-100℃, modified nano-calcium carbonate and barium sulfate are added, the stirring speed is adjusted to 1000-1200 rpm, and stirring is carried out for 1.5-2.5 hours.
[0017] The crosslinking agent and additives are added as follows: the stirred tank is kept under vacuum and cooled naturally. The composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer are added to the stirred tank in sequence and stirred.
[0018] Furthermore, the crosslinking agent and additives are added as follows: Maintain a vacuum state in the stirred tank, allow it to cool naturally to 40-50℃, adjust the stirring speed to 500-600 rpm, and sequentially add the composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer to the stirred tank. After adding each raw material, stir for 10-15 minutes before adding the next raw material. After all additives are added, maintain the vacuum and stirring speed, and continue stirring for 0.5-1 hour.
[0019] The silicone sealant was prepared by: maintaining a vacuum state in the mixing vessel and maintaining the temperature of the mixing vessel, adding dibutyltin dilaurate and stirring; then adding heptanoic acid and continuing to stir; filtering with a screen to obtain the silicone sealant.
[0020] Furthermore, the preparation of the silicone sealant involves: maintaining a vacuum state in the mixing vessel, keeping the temperature of the mixing vessel at 40-50℃, adjusting the stirring speed to 300-400 rpm, adding dibutyltin dilaurate, and stirring for 10-15 minutes; then adding heptanoic acid and continuing to stir for 20-30 minutes; after stirring, turning off the vacuum and stirring, passing the mixture through a 200-mesh filter, and loading it into a sealed container to obtain the silicone sealant.
[0021] The beneficial effects of this invention are as follows: (1) In this invention, the methyltributyl ketone oxime oxime group has small steric hindrance and high reactivity, while the methyltris(methylisobutyl ketone oxime) oxime group has large steric hindrance and medium reactivity. The methyltributyl ketone oxime oxime preferentially reacts with the terminal hydroxyl groups of α,ω-dihydroxy polydimethylsiloxane to complete the surface crosslinking. Then, the methyltris(methylisobutyl ketone oxime) oxime oxime gradually participates in the reaction to fill the local crosslinking density insufficient area.
[0022] By adding heptanoic acid, the carboxyl group of heptanoic acid forms a reversible weak coordination bond with the tin ion in dibutyltin dilaurate, which temporarily "dormant" dibutyltin dilaurate, thus preventing the adhesive from thickening and gelling. The reversible weak coordination of heptanoic acid not only avoids the storage failure of the inhibitor-free system, but also avoids the decrease in curing efficiency caused by strong inhibitors.
[0023] In addition, the slow cross-linking properties of methyltris(methylisobutyl ketone oxime)silane provide a buffer time for the dormant effect of heptanoic acid, avoiding local cross-linking concentration; the presence of heptanoic acid can ensure that the cross-linking agent participates in the reaction in stages, forming a uniform network and ensuring excellent mechanical properties.
[0024] (2) The ketoxime-type matte silicone sealant of the present invention has excellent mechanical properties and a stable matte effect. The prepared silicone sealant has a tensile strength of 3.76-3.91 MPa, an elongation at break of 418-431%, a surface drying time of 25-28 min, and a gloss of 6.5-7.2 GU.
[0025] (3) The ketoxime-type matte silicone sealant of the present invention has excellent storage stability. After 30 days of storage, the prepared silicone sealant has a surface drying time of 28-31 min and a tensile strength of 3.67-3.77 MPa; after 60 days of storage, the surface drying time is 30-33 min and the tensile strength is 3.55-3.68 MPa. Detailed Implementation
[0026] 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.
[0027] Example 1: A ketoxime-based matte silicone sealant and its preparation method A ketoxime-type matte silicone sealant, by weight, comprises the following raw materials: 55 parts α,ω-dihydroxypolydimethylsiloxane, 10 parts dimethyl silicone oil, 20 parts fumed silica, 120 parts modified nano-calcium carbonate, 5 parts barium sulfate, 5 parts composite crosslinking agent, 0.8 parts dibutyltin dilaurate, 0.1 parts heptanoic acid, 4.5 parts silane coupling agent mixture, 0.3 parts diphenyldimethoxysilane, 0.5 parts antioxidant, and 0.1 parts defoamer.
[0028] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0029] The particle size of the fumed silica is 12-20 nm.
[0030] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0031] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0032] A method for preparing a ketoxime-based matte silicone sealant includes the following steps: Step 1: Pre-preparation of functional components Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane were mixed and stirred until homogeneous. Then, while maintaining a stirring speed of 300 rpm, deionized water and acetic acid were added dropwise, and the temperature was raised to 50°C and maintained for 4 hours. After the reaction was completed, the mixture was dehydrated under vacuum to obtain the composite crosslinking agent.
[0033] The mass ratio of methyltributanone oxime silane to methyltris(methylisobutyl ketone oxime) silane is 6:3. The amount of deionized water used is 1% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The amount of acetic acid used is 0.05% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The vacuum dehydration is performed at a temperature of 80°C, a vacuum degree of -0.095 MPa, and a dehydration time of 2 hours.
[0034] Nano-calcium carbonate and zinc stearate were mixed evenly, with the amount of zinc stearate being 1.5% of the mass of nano-calcium carbonate. The mixture was heated to 40°C and stirred for 30 minutes at a speed of 1500 rpm to obtain modified nano-calcium carbonate. The nano-calcium carbonate had a particle size of 80-100 nm.
[0035] Silane coupling agent KH-560 and silane coupling agent KH-792 were mixed evenly to obtain a silane coupling agent mixture. The mass ratio of silane coupling agent KH-560 to silane coupling agent KH-792 was 1.8:1.
[0036] Step 2: Dispersion of basic filler Add α,ω-dihydroxypolydimethylsiloxane and dimethyl silicone oil to a stirred tank, start stirring, and stir for 5 minutes at a speed of 500 rpm. Then add fumed silica, heat to 100°C, evacuate the stirred tank to a vacuum of -0.095 MPa, increase the stirring speed to 800 rpm, and stir for 2 hours. Then slowly cool to 80°C, add modified nano-calcium carbonate and barium sulfate, adjust the stirring speed to 1000 rpm, and stir for 2.5 hours.
[0037] Step 3: Addition of crosslinking agents and auxiliaries Maintain a vacuum in the stirred tank and allow it to cool naturally to 40°C. Adjust the stirring speed to 500 rpm and add the composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer to the stirred tank in sequence. After adding each raw material, stir for 15 minutes before adding the next raw material. After all the additives have been added, maintain the vacuum and stirring speed and continue stirring for 1 hour.
[0038] Step 4: Prepare silicone sealant Maintain a vacuum in the mixing vessel and keep the temperature of the mixing vessel at 40°C. Adjust the stirring speed to 300 rpm, add dibutyltin dilaurate, and stir for 15 minutes. Then add heptanoic acid and continue stirring for 30 minutes. After stirring, turn off the vacuum and the stirring. Pass the mixture through a 200-mesh filter and put it into a sealed container to obtain the silicone sealant.
[0039] Example 2: A ketoxime-based matte silicone sealant and its preparation method A ketoxime-type matte silicone sealant, by weight, comprises the following raw materials: 70 parts α,ω-dihydroxypolydimethylsiloxane, 20 parts dimethyl silicone oil, 15 parts fumed silica, 100 parts modified nano-calcium carbonate, 4 parts barium sulfate, 10 parts composite crosslinking agent, 0.6 parts dibutyltin dilaurate, 0.2 parts heptanoic acid, 3 parts silane coupling agent mixture, 0.8 parts diphenyldimethoxysilane, 0.4 parts antioxidant, and 0.2 parts defoamer.
[0040] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0041] The particle size of the fumed silica is 12-20 nm.
[0042] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0043] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0044] A method for preparing a ketoxime-based matte silicone sealant includes the following steps: Step 1: Pre-preparation of functional components Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane were mixed and stirred until homogeneous. Then, while maintaining a stirring speed of 400 rpm, deionized water and acetic acid were added dropwise, and the temperature was raised to 55°C and maintained for 3.5 h. After the reaction was completed, the mixture was dehydrated under vacuum to obtain the composite crosslinking agent.
[0045] The mass ratio of methyltributanone oxime silane to methyltris(methylisobutyl ketone oxime) silane is 6:4. The amount of deionized water used is 1% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The amount of acetic acid used is 0.1% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The vacuum dehydration is performed at a temperature of 90°C, a vacuum degree of -0.098 MPa, and a dehydration time of 2 hours.
[0046] Nano-calcium carbonate and zinc stearate were mixed evenly, with the amount of zinc stearate being 2% of the mass of the nano-calcium carbonate. The mixture was heated to 50°C and stirred for 40 minutes at a speed of 1200 rpm to obtain modified nano-calcium carbonate. The nano-calcium carbonate had a particle size of 80-100 nm.
[0047] Silane coupling agent KH-560 and silane coupling agent KH-792 were mixed evenly to obtain a silane coupling agent mixture. The mass ratio of silane coupling agent KH-560 to silane coupling agent KH-792 was 2:1.
[0048] Step 2: Dispersion of basic filler Add α,ω-dihydroxypolydimethylsiloxane and dimethyl silicone oil to a stirred tank, start stirring, and stir for 8 minutes at a speed of 400 rpm. Then add fumed silica, heat to 110°C, evacuate the stirred tank to a vacuum of -0.098 MPa, increase the stirring speed to 900 rpm, and stir for 1.5 hours. Then slowly cool to 90°C, add modified nano-calcium carbonate and barium sulfate, adjust the stirring speed to 1100 rpm, and stir for 2 hours.
[0049] Step 3: Addition of crosslinking agents and auxiliaries Maintain a vacuum in the stirred tank and allow it to cool naturally to 45°C. Adjust the stirring speed to 550 rpm and add the composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer to the stirred tank in sequence. After adding each raw material, stir for 13 minutes before adding the next raw material. After all the additives have been added, maintain the vacuum and stirring speed and continue stirring for 1 hour.
[0050] Step 4: Prepare silicone sealant Maintain a vacuum in the mixing vessel and keep the temperature of the mixing vessel at 45°C. Adjust the stirring speed to 400 rpm, add dibutyltin dilaurate, and stir for 15 minutes. Then add heptanoic acid and continue stirring for 25 minutes. After stirring, turn off the vacuum and the stirring. Pass the mixture through a 200-mesh filter and put it into a sealed container to obtain the silicone sealant.
[0051] Example 3: A ketoxime-based matte silicone sealant and its preparation method A ketoxime-type matte silicone sealant, by weight, comprises the following raw materials: 85 parts α,ω-dihydroxypolydimethylsiloxane, 30 parts dimethyl silicone oil, 10 parts fumed silica, 80 parts modified nano-calcium carbonate, 2 parts barium sulfate, 12 parts composite crosslinking agent, 0.3 parts dibutyltin dilaurate, 0.3 parts heptanoic acid, 1.5 parts silane coupling agent mixture, 1 part diphenyldimethoxysilane, 0.1 parts antioxidant, and 0.3 parts defoamer.
[0052] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0053] The particle size of the fumed silica is 12-20 nm.
[0054] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0055] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0056] A method for preparing a ketoxime-based matte silicone sealant includes the following steps: Step 1: Pre-preparation of functional components Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane were mixed and stirred until homogeneous. Then, while maintaining a stirring speed of 400 rpm, deionized water and acetic acid were added dropwise, and the temperature was raised to 60°C and maintained for 3 hours. After the reaction was completed, the mixture was dehydrated under vacuum to obtain the composite crosslinking agent.
[0057] The mass ratio of methyltributanone oxime silane to methyltris(methylisobutyl ketone oxime) silane is 7:4. The amount of deionized water used is 1.5% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The amount of acetic acid used is 0.15% of the total mass of methyltributanone oxime silane and methyltris(methylisobutyl ketone oxime) silane. The vacuum dehydration is performed at a temperature of 90°C, a vacuum degree of -0.098 MPa, and a dehydration time of 1 hour.
[0058] Nano-calcium carbonate and zinc stearate were mixed evenly, with the amount of zinc stearate being 2% of the mass of the nano-calcium carbonate. The mixture was heated to 60°C and stirred for 40 minutes at a speed of 1000 rpm to obtain modified nano-calcium carbonate. The nano-calcium carbonate had a particle size of 80-100 nm.
[0059] Silane coupling agent KH-560 and silane coupling agent KH-792 were mixed evenly to obtain a silane coupling agent mixture. The mass ratio of silane coupling agent KH-560 to silane coupling agent KH-792 was 2:1.
[0060] Step 2: Dispersion of basic filler Add α,ω-dihydroxypolydimethylsiloxane and dimethyl silicone oil to a stirred tank, start stirring, and stir for 10 minutes at a speed of 300 rpm; then add fumed silica, heat to 120°C, evacuate the stirred tank to a vacuum of -0.098 MPa, increase the stirring speed to 1000 rpm, and stir for 1 hour; then slowly cool to 100°C, add modified nano-calcium carbonate and barium sulfate, adjust the stirring speed to 1200 rpm, and stir for 1.5 hours.
[0061] Step 3: Addition of crosslinking agents and auxiliaries Maintain a vacuum in the stirred tank and allow it to cool naturally to 50°C. Adjust the stirring speed to 600 rpm and add the composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer to the stirred tank in sequence. After adding each raw material, stir for 10 minutes before adding the next raw material. After all the additives have been added, maintain the vacuum and stirring speed and continue stirring for 0.5 hours.
[0062] Step 4: Prepare silicone sealant Maintain a vacuum in the mixing vessel and keep the temperature of the mixing vessel at 50°C. Adjust the stirring speed to 400 rpm, add dibutyltin dilaurate, and stir for 10 minutes. Then add heptanoic acid and continue stirring for 20 minutes. After stirring, turn off the vacuum and the stirring. Pass the mixture through a 200-mesh filter and put it into a sealed container to obtain the silicone sealant.
[0063] Comparative Example 1 An organosilicon sealant, by weight, comprises the following raw materials: 70 parts α,ω-dihydroxypolydimethylsiloxane, 20 parts dimethyl silicone oil, 15 parts fumed silica, 100 parts modified nano-calcium carbonate, 4 parts barium sulfate, 10 parts methyl tributanone oxime silane, 0.6 parts dibutyltin dilaurate, 0.2 parts heptanoic acid, 3 parts silane coupling agent mixture, 0.8 parts diphenyldimethoxysilane, 0.4 parts antioxidant, and 0.2 parts defoamer.
[0064] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0065] The particle size of the fumed silica is 12-20 nm.
[0066] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0067] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0068] A method for preparing an organosilicon sealant includes the following steps: Step 1: Pre-preparation of functional components Nano-calcium carbonate and zinc stearate were mixed evenly, with the amount of zinc stearate being 2% of the mass of the nano-calcium carbonate. The mixture was heated to 50°C and stirred for 40 minutes at a speed of 1200 rpm to obtain modified nano-calcium carbonate. The nano-calcium carbonate had a particle size of 80-100 nm.
[0069] Silane coupling agent KH-560 and silane coupling agent KH-792 were mixed evenly to obtain a silane coupling agent mixture. The mass ratio of silane coupling agent KH-560 to silane coupling agent KH-792 was 2:1.
[0070] Step 2: Dispersion of basic filler This step is the same as the "basic filler dispersion" step in Example 2.
[0071] Step 3: Addition of crosslinking agents and auxiliaries Maintain a vacuum in the stirred tank and allow it to cool naturally to 45°C. Adjust the stirring speed to 550 rpm and add methyl tributanone oxime silane, silane coupling agent mixture, diphenyl dimethoxysilane, antioxidant, and defoamer to the stirred tank in sequence. After adding each raw material, stir for 13 minutes before adding the next raw material. After all the additives have been added, maintain the vacuum and stirring speed and continue stirring for 1 hour.
[0072] Step 4: Prepare silicone sealant This step is the same as the "Preparation of Organosilicon Sealant" step in Example 2.
[0073] Comparative Example 2 An organosilicon sealant, by weight, comprises the following raw materials: 70 parts α,ω-dihydroxypolydimethylsiloxane, 20 parts dimethyl silicone oil, 15 parts fumed silica, 100 parts modified nano-calcium carbonate, 4 parts barium sulfate, 10 parts composite crosslinking agent, 0.6 parts dibutyltin dilaurate, 3 parts silane coupling agent mixture, 0.8 parts diphenyldimethoxysilane, 0.4 parts antioxidant, and 0.2 parts defoamer.
[0074] The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 50,000-100,000 mPa·s.
[0075] The particle size of the fumed silica is 12-20 nm.
[0076] The defoamer is an organosilicon defoamer, specifically BYK-066N.
[0077] The antioxidant is a hindered phenolic antioxidant, specifically Irganox 1010.
[0078] A method for preparing an organosilicon sealant includes the following steps: Step 1: Pre-preparation of functional components This step is the same as the "pre-preparation of functional components" step in Example 2.
[0079] Step 2: Dispersion of basic filler This step is the same as the "basic filler dispersion" step in Example 2.
[0080] Step 3: Addition of crosslinking agents and auxiliaries This step is the same as the "addition of crosslinking agent and auxiliary agent" step in Example 2.
[0081] Step 4: Prepare silicone sealant Maintain a vacuum in the mixing vessel and keep the temperature of the mixing vessel at 45°C. Adjust the stirring speed to 400 rpm, add dibutyltin dilaurate, and stir for 15 minutes. After stirring, turn off the vacuum and the stirring, pass the mixture through a 200-mesh filter, and put it into a sealed container to obtain the silicone sealant.
[0082] Example 4 Performance Testing (a) The tensile strength of the silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2 was determined according to the test method provided in GB / T 528-2009. The surface drying time was determined according to the test method provided in GB / T 13477.5-2002. The matte effect was tested according to the test method specified in GB / T 9754-2007, and the gloss at 60° was measured. The specific test results are shown in Table 1.
[0083] Table 1 As shown in Table 1, the silicone sealants prepared in Examples 1-3 have a tensile strength of 3.76-3.91 MPa, an elongation at break of 418-431%, a surface drying time of 25-28 min, and a gloss of 6.5-7.2 GU. This demonstrates that the ketoxime-type matte silicone sealant prepared in this invention has excellent mechanical properties and a stable matte effect.
[0084] (ii) Storage stability tests were conducted on the silicone sealants prepared in Examples 1-3 and Comparative Examples 1-2. The sealants were stored in an oven at 50°C for 30 and 60 days, respectively, and then removed and allowed to return to room temperature. The surface drying time and tensile strength were then tested. The specific test results are shown in Table 2.
[0085] Table 2 As shown in Table 2, the silicone sealants prepared in Examples 1-3 had a surface drying time of 28-31 min and a tensile strength of 3.67-3.77 MPa after 30 days of storage; after 60 days of storage, the surface drying time was 30-33 min and the tensile strength was 3.55-3.68 MPa. It can be seen that, through the addition of the composite crosslinking agent and heptanoic acid, the surface drying time and tensile strength of the silicone sealants prepared in Examples 1-3 did not show significant deterioration after 60 days of storage. In contrast, the silicone sealant prepared in Comparative Example 1 had a significantly shorter surface drying time and a substantial decrease in strength, while the silicone sealant prepared in Comparative Example 2 completely gelled and failed after 60 days, demonstrating that the deketoxime type matte silicone sealant prepared in this invention has excellent storage stability.
[0086] 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 a ketoxime-type matte silicone sealant, characterized in that: The process includes steps such as pre-preparation of functional components, dispersion of basic fillers, addition of crosslinking agents and additives, and preparation of silicone sealant. The functional components were pre-prepared as follows: Under nitrogen protection, methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane were mixed and stirred until homogeneous; deionized water and acetic acid were added dropwise, the reaction was kept at a constant temperature, and then dehydrated under vacuum to obtain a composite crosslinking agent; nano-calcium carbonate and zinc stearate were mixed until homogeneous, heated, and stirred to obtain modified nano-calcium carbonate; silane coupling agent KH-560 and silane coupling agent KH-792 were mixed until homogeneous to obtain a silane coupling agent mixture. The basic filler dispersion is as follows: α,ω-dihydroxy polydimethylsiloxane and dimethyl silicone oil are stirred evenly; then fumed silica is added, the temperature is raised, the stirred tank is evacuated, and the mixture is stirred; then the temperature is lowered, modified nano-calcium carbonate and barium sulfate are added, and the mixture is stirred. The crosslinking agent and additives are added as follows: the stirred tank is kept under vacuum and cooled naturally. The composite crosslinking agent, silane coupling agent mixture, diphenyldimethoxysilane, antioxidant, and defoamer are added to the stirred tank in sequence and stirred. The silicone sealant was prepared by: maintaining a vacuum state in the mixing vessel and maintaining the temperature of the mixing vessel, adding dibutyltin dilaurate and stirring; then adding heptanoic acid and continuing to stir; filtering with a screen to obtain the silicone sealant.
2. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: The raw materials used are formulated in the following weight ratios: 55-85 parts α,ω-dihydroxypolydimethylsiloxane, 10-30 parts dimethyl silicone oil, 10-20 parts fumed silica, 80-120 parts modified nano calcium carbonate, 2-5 parts barium sulfate, 5-12 parts composite crosslinking agent, 0.3-0.8 parts dibutyltin dilaurate, 0.1-0.3 parts heptanoic acid, 1.5-4.5 parts silane coupling agent mixture, 0.3-1 part diphenyldimethoxysilane, 0.1-0.5 parts antioxidant, and 0.1-0.3 parts defoamer.
3. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: The mass ratio of the methyltributylone oxime silane to the methyltris(methylisobutylone oxime) silane is (6-7):(3-4).
4. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: In the pre-preparation step of the functional component, the amount of deionized water used is 1-1.5% of the total mass of methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane.
5. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: In the pre-preparation step of the functional component, the amount of acetic acid used is 0.05-0.15% of the total mass of methyltributanone oxime silane and methyltris(methylisobutylone oxime) silane.
6. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: In the pre-preparation step of the functional components, vacuum dehydration is performed at a temperature of 80-90℃, a vacuum degree of -0.095MPa to -0.098MPa, and a dehydration time of 1-2 hours.
7. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: The amount of zinc stearate used is 1.5-2% of the mass of nano-calcium carbonate.
8. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: The mass ratio of the silane coupling agent KH-560 to the silane coupling agent KH-792 is (1.8-2):
1.
9. The method for preparing a ketoxime-type matte silicone sealant according to claim 1, characterized in that: In the basic filler dispersion step, the stirred tank is evacuated to a vacuum level of -0.095 MPa to -0.098 MPa.