Corrosion-resistant silicone sealant and preparation method and application thereof

Abstract

The present application relates to a kind of corrosion-resistant organic silicon sealant and its preparation method and application, belong to organic silicon sealant technical field.The sealant is based on 107 glue polymer, abandon traditional calcium carbonate filler, adopt fumed silica and silicon powder compound as filler system, add heat-resistant filler, silane coupling agent and catalyst.Through the cooperation of component, sealant simultaneously has excellent corrosion resistance (acid resistance, alkali resistance, oil resistance, salt fog resistance) after curing, and cost controllable.Its preparation method uses step-by-step mixing process: first, 107 glue, silicon powder, heat-resistant filler are mixed vacuum dehydration, then add fumed silica, finally add silane coupling agent and catalyst;Optionally, crosslinking agent D30 is added before fumed silica is added, and additives D90 are added together with silane coupling agent and catalyst.The obtained sealant has stable surface drying time, good extrusion property and long storage period, and is suitable for bonding and sealing in electronic and electrical industries, automobile industry and the like.

Description

Technical Field

[0001] This invention relates to the field of silicone sealant technology, and in particular to a corrosion-resistant silicone sealant, its preparation method, and its application. Background Technology

[0002] Silicone sealant (also known as organosilicon sealant) is a moisture-curing elastic sealing material made by mixing α,ω-dihydroxypolydimethylsiloxane (commonly known as 107 glue) as a base polymer with fillers, crosslinking agents, coupling agents, catalysts, and other additives. It is a paste-like substance when uncured, and after curing, it exhibits excellent resistance to high and low temperatures, weather resistance, and insulation properties. It is widely used for bonding and sealing in industries such as construction, electronics, automobiles, and lighting.

[0003] Currently, nano-calcium carbonate is commonly added as a reinforcing or additive filler in common silicone sealant formulations. However, nano-calcium carbonate is chemically reactive and readily reacts with corrosive media such as acids, alkalis, oils, and salt spray. For example, calcium carbonate decomposes upon contact with acid, releasing carbon dioxide gas, which can lead to air bubbles within the sealant, interfacial adhesion failure, and even complete loss of sealing function. Therefore, in applications requiring exposure to acidic, alkaline, oily, or salt spray environments (such as chemical pipelines, outdoor electronic equipment, and marine engineering), traditional calcium carbonate-filled silicone sealants are insufficient to meet long-term usage requirements.

[0004] To improve corrosion resistance, some existing technologies have attempted to use fumed silica (FHS) instead of calcium carbonate. While FHS has good chemical inertness, its high cost means that using large quantities alone would significantly increase the manufacturing cost of the sealant. Therefore, there is an urgent need for a silicone sealant solution that offers both excellent corrosion resistance and a reasonable cost. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a corrosion-resistant silicone sealant with excellent corrosion resistance and reasonable cost, as well as its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a corrosion-resistant silicone sealant comprising α,ω-dihydroxy polydimethylsiloxane, fumed silica, silica powder, heat-resistant filler, silane coupling agent, and catalyst.

[0007] This invention, through the selection and combination of specific components, produces a corrosion-resistant silicone sealant with excellent corrosion resistance (acid resistance, oil resistance, alkali resistance, and salt spray resistance).

[0008] As a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, based on 100 parts by weight of the total weight of the α,ω-dihydroxy polydimethylsiloxane, the content of each component is as follows: 5-8 parts of fumed silica, 65-85 parts of silica powder, 15-30 parts of heat-resistant filler, 1-2 parts of silane coupling agent, and 0.02-0.06 parts of catalyst.

[0009] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the particle size D50 of the silicon micropowder is ≤2.5μm. Preferably, the particle size of the silicon micropowder is 8000 mesh (approximately 1.3μm).

[0010] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the α,ω-dihydroxypolydimethylsiloxane is any one of the following: (a) A first component with a viscosity of 4500~5500 mPa·s and a second component with a viscosity of 19500~20500 mPa·s, and the mass ratio of the two components is 1:8-1:12; (b) A single component with a viscosity of 19,500 to 20,500 mPa·s.

[0011] As a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, it further includes at least one of the following: plasticizer, crosslinking agent D30, and additive D90; Based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane: When the plasticizer is included, its content is 3.5-6.5 parts by weight; when the crosslinking agent D30 is included, its content is 7-10 parts by weight; when the additive D90 is included, its content is 0.5-1.5 parts by weight.

[0012] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the heat-resistant filler is melamine cyanurate.

[0013] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; preferably N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0014] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the catalyst is an organotin catalyst.

[0015] Preferably, the organotin catalyst includes, but is not limited to, dialkyltin dihydroxy acid (such as dibutyltin dilaurate), dialkyldiaryloxytin, stannous dihydroxy acid, etc.

[0016] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the plasticizer is dimethyl silicone oil with a viscosity of 50-500 mPa·s. Preferably, the viscosity of the dimethyl silicone oil is 250-300 mPa·s.

[0017] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the crosslinking agent D30 is methyltributanone oxime silane.

[0018] In a preferred embodiment of the corrosion-resistant silicone sealant of the present invention, the additive D90 is vinyltributylone oxime silane.

[0019] Secondly, the present invention provides a method for preparing the above-mentioned corrosion-resistant silicone sealant, which includes the following steps: S1. Mix α,ω-dihydroxypolydimethylsiloxane, silica powder, and heat-resistant filler, stir, and dehydrate under vacuum to obtain the first mixture; S2. Add fumed silica to the first mixture, stir, and vacuum stir to obtain the second mixture; S3. Add silane coupling agent and catalyst to the second mixture, stir under vacuum, and discharge to obtain the final product.

[0020] As a preferred embodiment of the preparation method of the corrosion-resistant silicone sealant of the present invention, it further includes the following step S4: before adding fumed silica, it further includes the step of adding crosslinking agent D30 to the first mixture and stirring under vacuum; and / or, in step S3, the silane coupling agent and catalyst are added together with the auxiliary agent D90.

[0021] Thirdly, the present invention provides a sealing method comprising applying the above-mentioned corrosion-resistant silicone sealant between two substrates and curing the sealant.

[0022] Fourthly, the present invention provides a seal comprising the cured product of the above-mentioned corrosion-resistant silicone sealant.

[0023] Fifthly, the present invention provides an electronic component comprising the cured product of the aforementioned corrosion-resistant silicone sealant.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The corrosion-resistant silicone sealant of this invention uses 107 adhesive as the base polymer, abandons the traditional calcium carbonate filler, and adopts a compound of fumed silica and silica powder, with the addition of heat-resistant fillers, silane coupling agents and catalysts. Through the combination of the above components, the sealant, after curing, possesses excellent corrosion resistance (acid resistance, alkali resistance, oil resistance, and salt spray resistance).

[0025] Testing showed that the sealant of this invention exhibited stable performance in 10-hour acid, oil, alkali, and salt spray tests, with significantly better corrosion resistance than Comparative Example 1, which used calcium carbonate filler (Comparative Example 1 showed severe bubbling and complete detachment under acidic conditions). This invention uses a compound of fumed silica and silica powder, effectively controlling raw material costs while ensuring both reinforcing effect and corrosion resistance. The preparation method is simple and suitable for large-scale production.

[0026] Furthermore, by selecting appropriate plasticizers and additives D30 and D90, the sealant of this invention exhibits suitable extrudability and surface drying time, as well as good storage stability. As shown in Comparative Example 3, the process of "adding the vapor phase first and then D30" leads to poor extrudability and subsequent flow and flattening after curing; while the stepwise process of this invention (adding D30 first and then the vapor phase) yields a sealant with a surface drying time of 30-40 min, extrudability ≥650 mL / min, and a shelf life of 12 months. Attached Figure Description

[0027] Figure 1 This is a photograph of the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention before a 10-hour neutral salt spray test; Figure 2 This is a photograph of the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention after a 10-hour neutral salt spray test; Figure 3 This is a photograph of the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention before a 10-hour acid resistance test. Figure 4 The photo shows the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of this invention after a 10-hour acid resistance test. Figure 5 This is a photograph of the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention before a 10-hour oil resistance test; Figure 6 This is a photograph of the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention after a 10-hour oil resistance test. Figure 7 The photo shows the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention before a 10-hour alkali resistance test. Figure 8 The photo shows the appearance of the corrosion-resistant silicone sealant prepared in Example 1 of the present invention after a 10-hour alkali resistance test. Figure 9 Photographs showing the appearance of the sealant prepared in Comparative Example 1 before a 10-hour acid resistance test; Figure 10 The image shows the appearance of the sealant prepared in Comparative Example 1 after a 10-hour acid resistance test. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments. The embodiments described below are some, but not all, embodiments of this invention. The embodiments of this invention are used to illustrate the invention, not to limit it. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Unless otherwise specified, experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. The raw materials and reagents used are commercially available conventional products or products that conform to relevant national / industry standards and are all commercially available.

[0029] Example 1 This embodiment provides a corrosion-resistant silicone sealant, the composition and dosage of which (based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane) are as follows: α,ω-Dihydroxypolydimethylsiloxane: Total 100 parts, of which 9.1 parts are of a viscosity of 5000 mPa·s and 90.9 parts are of a viscosity of 20000 mPa·s; 6.82 parts are fumed silica; 79.55 parts are silica powder (912 silica powder, particle size 8000 mesh); 27.27 parts are heat-resistant filler (melamine cyanurate); 1.36 parts are silane coupling agent (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, grade KH792); 0.045 parts are catalyst (dibutyltin dilaurate); 4.55 parts are plasticizer (dimethyl silicone oil, viscosity 280 mPa·s); 9.09 parts are crosslinking agent D30 (methyl tributanone oxime silane); and 1.14 parts are additive D90 (vinyl tributanone oxime silane).

[0030] This embodiment provides a method for preparing a corrosion-resistant silicone sealant, the specific steps of which are as follows: (1) α,ω-dihydroxypolydimethylsiloxane (107 glue), silica powder, heat-resistant filler, and plasticizer were added to a high-speed disperser at once and stirred for 1 hour. The edges were scraped off, and vacuum stirring was continued for dehydration. Dehydration conditions: temperature 130℃, vacuum degree ≥0.09 MPa, time approximately 12 hours. In the early stage, the material was heated and dehydrated by stirring at high speed (25Hz, i.e., 1500rpm), and in the later stage, cooling water was introduced to cool down the material to obtain the first mixture; (2) Add crosslinking agent D30 to the first mixture and continue vacuum stirring for 15 minutes under a vacuum degree ≥0.09 MPa at a stirring speed of 25 Hz; (3) Add fumed silica to the mixture obtained in step (2), stir for 10 minutes (stirring speed is 25 Hz), scrape the edge, and then vacuum stir for 30 minutes under vacuum degree ≥0.09 MPa (stirring speed is 25 Hz) to obtain the second mixture; (4) Add additive D90, silane coupling agent and catalyst to the second mixture, and stir under vacuum at a vacuum degree ≥0.09 MPa for 20 minutes (stirring speed 25Hz), discharge, and package to obtain the corrosion-resistant silicone sealant of this embodiment.

[0031] Example 2 This embodiment provides a corrosion-resistant silicone sealant, the composition and dosage of which (based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane) are as follows: α,ω-Dihydroxypolydimethylsiloxane: Total 100 parts, a single component with a viscosity of 20000 mPa·s; 5.97 parts fumed silica, 70 parts silica powder (912 silica powder, particle size 8000 mesh), 20 parts heat-resistant filler (melamine cyanurate), 1.19 parts silane coupling agent (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, grade KH792), 0.04 parts catalyst (dibutyltin dilaurate); 5.97 parts plasticizer (dimethyl silicone oil, viscosity 280 mPa·s), 8.06 parts crosslinking agent D30 (methyl tributanone oxime silane), and 1.01 parts additive D90 (vinyl tributanone oxime silane).

[0032] The preparation method in this embodiment is the same as in Embodiment 1.

[0033] Example 3 This embodiment provides a corrosion-resistant silicone sealant, the composition and dosage of which (based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane) are as follows: α,ω-Dihydroxypolydimethylsiloxane: Total 100 parts, of which 9.1 parts are of a viscosity of 5000 mPa·s and 90.9 parts are of a viscosity of 20000 mPa·s; 5 parts are fumed silica; 65 parts are silica powder (912 silica powder, particle size 8000 mesh); 15 parts are heat-resistant filler (melamine cyanurate); 1 part is silane coupling agent (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, grade KH792); 0.02 parts are catalyst (dibutyltin dilaurate); 3.5 parts are plasticizer (dimethyl silicone oil, viscosity 250 mPa·s); 7 parts are crosslinking agent D30 (methyl tributanone oxime silane); and 0.5 parts are additive D90 (vinyl tributanone oxime silane).

[0034] The preparation method in this embodiment is the same as in Embodiment 1.

[0035] Example 4 This embodiment provides a corrosion-resistant silicone sealant, the composition and dosage of which (based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane) are as follows: α,ω-Dihydroxypolydimethylsiloxane: Total 100 parts, including 9.1 parts of the component with a viscosity of 5000 mPa·s and 90.9 parts of the component with a viscosity of 20000 mPa·s; 8 parts of fumed silica, 85 parts of silica powder (912 silica powder, particle size 8000 mesh), 30 parts of heat-resistant filler (melamine cyanurate), 2 parts of silane coupling agent (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, grade KH792), 0.06 parts of catalyst (dibutyltin dilaurate); 6.5 parts of plasticizer (dimethyl silicone oil, viscosity 300 mPa·s), 10 parts of crosslinking agent D30 (methyl tributanone oxime silane), and 1.5 parts of additive D90 (vinyl tributanone oxime silane).

[0036] The preparation method in this embodiment is the same as in Embodiment 1.

[0037] Comparative Example 1 The only difference between this comparative example and Example 1 is that silica powder and fumed silica are not used; instead, an equal mass of nano-calcium carbonate (i.e., 86.37 parts of calcium carbonate) is added. The remaining components and amounts are the same as in Example 1. The preparation method is the same as in Example 1.

[0038] Comparative Example 2 The only difference between this comparative example and Example 1 is that heat-resistant filler is not used; the remaining components and amounts are the same as in Example 1. The preparation method is the same as in Example 1.

[0039] Comparative Example 3 The only difference between this comparative example and Example 1 is the preparation method: in step (2), fumed silica is added first and stirred for 15-20 minutes, and then crosslinking agent D30 is added (i.e., the order of "adding D30 first and then adding fumed silica" is not followed). The remaining components and amounts are the same as in Example 1, and the same mixing, dehydration, and discharge steps are used as in Example 1.

[0040] Testing revealed that the thixotropic properties of the colloid were impaired because the fumed silica was not added before the crosslinking agent D30. After curing, the colloid flattened and failed to maintain its shape. The resulting sealant exhibited poor extrudability and could not retain its applied shape after curing, thus failing to meet the requirements of conventional sealing applications (this process is only suitable for specific coating scenarios requiring self-leveling flow).

[0041] Performance testing 1. Resistance to media 1.1. Sample preparation and curing The silicone sealants prepared in the above Examples 1-4 and Comparative Examples 1-2 were made into test pieces according to the standard method respectively. After curing for 7 days under standard conditions (temperature 23±2°C, relative humidity 50±5%), performance tests were carried out. The obtained test pieces were numbered as Sample A (Example 1), Sample B (Example 2), Sample C (Example 3), Sample D (Example 4), Sample E (Comparative Example 1), Sample F (Comparative Example 2) and Sample G (Comparative Example 3) respectively. The performance test methods are shown in Table 1 below.

[0042] Table 1 ,

[0043] 1.2. Test results Samples A-G were respectively subjected to neutral salt spray, acid resistance, oil resistance, alkali resistance and other tests, and the obtained test results are shown in Table 2-1 below. ,

[0044] Table 2-1

[0045] 1.3 Result analysis From Table 2-1 and Figures 1-8 it can be seen that Examples 1-4 all showed excellent resistance to media performance, and there was no blistering or discoloration in the neutral salt spray, acid resistance, oil resistance and alkali resistance (saturated calcium hydroxide) tests, and all passed. As Figure 9 and Figure 10 shown, due to the presence of calcium carbonate filler in Comparative Example 1, severe blistering and complete peeling occurred in the acid resistance test; but it passed in the remaining tests, indicating that the main defect of the calcium carbonate filler is its poor acid resistance. And the present invention effectively solved this problem by abandoning calcium carbonate and using a compound of fumed silica and silica powder, while maintaining other resistance to media performance. Although Comparative Example 2 does not contain heat-resistant filler, its filler system (fumed silica + silica powder) is the same as that of the Examples, so the resistance to media performance is still qualified. The resistance to media performance of Comparative Example 3 is comparable to that of the Examples.

[0046] The above results show that the filler system of the present invention that abandons calcium carbonate and uses a compound of fumed silica and silica powder is the key to endowing the sealant with excellent corrosion resistance.

[0047] , 2. Construction and storage performance The sealants obtained from Examples 1-2 and Comparative Example 3 were respectively tested for surface drying time, extrudability and storage period, and the results are shown in Table 2-2.

[0048] Table 2-2

[0049] Note: Test method for surface drying time: GB / T 13477.5-2003.

[0050] Extrudability test method: GB / T 13477.3-2002.

[0051] Storage period test method: Store the sealant in a sealed container at 23°C and periodically check its extrudability and curing performance until its performance significantly decreases.

[0052] The surface drying time, extrudability, and shelf life of Examples 3-4 are basically equivalent to those of Example 1. The surface drying time and shelf life of Comparative Example 3 (adding the vapor phase first, then D30) are basically equivalent to those of the examples, but its extrudability is significantly worse, and its impaired thixotropy leads to flow and flattening after curing, failing to meet construction requirements. This indicates that the order of "adding D30 first, then adding the vapor phase" in this invention is crucial to ensuring good extrudability and thixotropy of the sealant.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A corrosion-resistant silicone sealant, characterized in that, It includes α,ω-dihydroxypolydimethylsiloxane, fumed silica, silica powder, heat-resistant filler, silane coupling agent and catalyst.

2. The corrosion-resistant silicone sealant as described in claim 1, characterized in that, Based on 100 parts by weight of the total weight of the α,ω-dihydroxy polydimethylsiloxane, the content of each component is as follows: 5-8 parts of fumed silica, 65-85 parts of silica powder, 15-30 parts of heat-resistant filler, 1-2 parts of silane coupling agent, and 0.02-0.06 parts of catalyst.

3. The corrosion-resistant silicone sealant as described in claim 1 or 2, characterized in that, The α,ω-dihydroxypolydimethylsiloxane is any one of the following: (a) A first component with a viscosity of 4500~5500 mPa·s and a second component with a viscosity of 19500~20500 mPa·s, and the mass ratio of the two components is 1:8~1:12; (b) A single component with a viscosity of 19,500 to 20,500 mPa·s.

4. The corrosion-resistant silicone sealant as described in claim 1 or 2, characterized in that, It also includes at least one of the following: plasticizer, crosslinking agent D30, and additive D90; Based on 100 parts by weight of α,ω-dihydroxypolydimethylsiloxane: When the plasticizer is included, its content is 3.5-6.5 parts by weight; when the crosslinking agent D30 is included, its content is 7-10 parts by weight; when the additive D90 is included, its content is 0.5-1.5 parts by weight.

5. The corrosion-resistant silicone sealant as described in claim 4, characterized in that, The heat-resistant filler is melamine cyanurate; and / or, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; and / or, the catalyst is an organotin catalyst; and / or, the plasticizer is dimethyl silicone oil with a viscosity of 50-500 mPa·s; and / or, the crosslinking agent D30 is methyltributanone oxime silane; and / or, the auxiliary agent D90 is vinyltributanone oxime silane.

6. A method for preparing a corrosion-resistant silicone sealant according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Mix α,ω-dihydroxypolydimethylsiloxane, silica powder, and heat-resistant filler, stir, and dehydrate under vacuum to obtain the first mixture; S2. Add fumed silica to the first mixture, stir, and vacuum stir to obtain the second mixture; S3. Add silane coupling agent and catalyst to the second mixture, stir under vacuum, and discharge to obtain the final product.

7. The method for preparing the corrosion-resistant silicone sealant as described in claim 6, characterized in that, It also includes the following step S4: before adding fumed silica, it further includes the step of adding crosslinking agent D30 to the first mixture and stirring under vacuum; and / or, in step S3, the silane coupling agent and catalyst are added together with the auxiliary agent D90.

8. A sealing method, characterized in that, It includes applying the corrosion-resistant silicone sealant of any one of claims 1 to 5 between two substrates and allowing the sealant to cure.

9. A sealing element, characterized in that, It comprises the cured product of the corrosion-resistant silicone sealant according to any one of claims 1 to 5.

10. An electronic component, characterized in that, It comprises the cured product of the corrosion-resistant silicone sealant according to any one of claims 1 to 5.

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