Liquid silicone sealant

Abstract

The application discloses a liquid silicone sealant, which comprises vinyl silicone oil, MQ resin solution, hydrogen-containing silicone oil, filler and platinum catalyst; the viscosity of the sealant is 8500-12000 mPa.s, the molar ratio of silicon hydrogen group to vinyl group is 1-1.4; the filler at least comprises nano calcium carbonate with an oil absorption value of 30-60 g / 100 g, and the amount of the nano calcium carbonate is 15-30% of the weight of the sealant; the MQ resin solution is a silicone oil solution of MQ resin, and the amount of the MQ resin is 5-15% of the weight of the sealant. The sealant is a liquid sealant, can be sprayed and constructed, and has good hanging property and strength performance.

Description

Technical Field

[0001] This application relates to the field of sealants, and more particularly to a liquid silicone sealant. Background Technology

[0002] In urban power supply systems, exposed electrical components such as high-voltage switches and conductors pose significant safety risks. Typically, an insulating sealant is applied to their exposed surfaces to improve electrical safety. Silicone sealants are widely used in this field due to their excellent weather resistance, insulation, and curing properties.

[0003] In existing technologies, silicone sealants have high viscosity and poor fluidity, so they are mostly applied by coating process to fix the sealant on the surface of the parts. However, coating application is inconvenient and inefficient. Summary of the Invention

[0004] To address the problems of inconvenient molding and low construction efficiency of silicone sealants on the surface of electrical components, this application provides a liquid silicone sealant that can be molded through a spraying process, making construction convenient and significantly improving work efficiency.

[0005] This application provides a liquid silicone sealant comprising vinyl silicone oil, MQ resin solution, hydrogen-containing silicone oil, filler, and platinum catalyst; the sealant has a viscosity of 8500–12000 mPa·s and a molar ratio of hydroxyl to vinyl groups of 1–1.4; the filler includes at least nano-calcium carbonate with an oil absorption value of 30–60 g / 100 g, and the amount of nano-calcium carbonate is 15–30% by weight of the sealant; the MQ resin solution is a silicone oil solution of MQ resin, and the amount of MQ resin is 5–15% by weight of the sealant.

[0006] Depending on the actual application requirements, the sealant of this application may also contain colorant and an inhibitor to control the crosslinking and curing speed. The inhibitor is preferably added at 0-20 ppm of the sealant weight, and the colorant is preferably added at 0.1-0.5% of the sealant weight.

[0007] Preferably, the inhibitor is tetramethyltetravinylcyclotetrasiloxane.

[0008] In this application, vinyl silicone oil refers to a polysiloxane containing at least two vinyl groups bonded to silicon atoms. These vinyl groups can be terminal vinyl groups or side-chain vinyl groups, more preferably two terminal vinyl groups, i.e., terminal vinyl silicone oil. Hydrogen-containing silicone oil refers to a polysiloxane containing at least two hydrogen atoms bonded to silicon atoms. These hydrogen atoms can be terminal hydrogen groups or side-chain hydrogen groups. MQ resin solution refers to a mixed solution of MQ resin and silicone oil. The end-capping groups of the M monomer in the MQ resin include, but are not limited to, at least one of vinyl, methyl, silanol, fluorinated groups, phenyl, methylphenyl, and phenylvinyl groups. The silicone oil is selected from at least one of vinyl silicone oil, phenyl silicone oil, methyl silicone oil, hydrogen-containing silicone oil, and fluorinated silicone oil according to the end-capping groups of the MQ resin.

[0009] The liquid silicone sealant of this application possesses excellent sprayability, which requires ensuring the sealant is in a liquid state and can be sprayed. It also needs a certain degree of thixotropy to form a sufficiently thick adhesive layer on the substrate surface after spraying. Therefore, the sealant should have moderate fluidity to meet the above requirements. Furthermore, the sealant must also meet product specifications such as tensile strength and elongation at break to provide good protection.

[0010] Specifically, the nano-calcium carbonate used in this application has an oil absorption value of 30-60 g / 100 g. It is a modified filler that has been modified with lipophilic substances such as fatty acids, long-chain alkyl groups, and silane compounds, maintaining a certain degree of thixotropy. This allows the sealant to adhere to the substrate surface after spraying, forming a sufficiently thick insulating layer. Simultaneously, it avoids excessive thickening due to strong thixotropy, which would reduce fluidity and affect its spraying performance. However, it should be noted that even with lipophilic modification, nano-calcium carbonate, when its content exceeds 10% of the total weight of the sealant, will still produce a significant thickening and tackifying effect, causing the sealant to become semi-solid, and its fluidity will be insufficient for spraying.

[0011] However, by adding an appropriate amount of MQ resin to the silicone oil solution, the sealant can remain liquid even with 15-30% nano-calcium carbonate content, resulting in an organosilicon sealant with high strength, high fluidity, and moderate thixotropic properties. The reason for this phenomenon may be twofold: firstly, the double-layered, tightly packed spherical structure of MQ resin provides excellent lubrication and reduces viscosity; secondly, MQ resin can create steric hindrance on the surface of nano-calcium carbonate, inhibiting its aggregation and the formation of its spatial network, thus reducing its thickening effect.

[0012] Finally, it should be noted that, under the conditions specified above, the sealant of this application can be produced in single-component or two-component form. Single-component sealant is less convenient to use and store, so in most cases a two-component form is used. That is, a portion of the amount of vinyl-terminated silicone oil, inhibitors, and other raw materials is component A, and the remainder of the amount of platinum catalyst and other raw materials is component B. Before use, components A and B are mixed evenly for spraying application.

[0013] Preferably, the platinum catalyst is selected from one or more of the following: an alcoholic solution of chloroplatinic acid, a platinum catalyst coordinated with tetrahydrofuran, and a platinum catalyst coordinated with divinyltetramethylsiloxane.

[0014] Preferably, the amount of platinum catalyst added is 5 ppm to 10 ppm of the total amount.

[0015] Preferably, the filler further includes 20-35% by weight of a reinforcing agent, wherein the reinforcing agent is selected from one or more of silica fume, alumina, titanium dioxide, aluminum hydroxide, and talc.

[0016] The aforementioned reinforcing agents have extremely low thixotropy and typically only serve a reinforcing function, which is beneficial for improving the tensile strength and other strength properties of the sealant protective layer.

[0017] Preferably, the viscosity of the MQ resin solution is less than or equal to 20000 mPa·s.

[0018] Preferably, the hydrogen-containing silicone oil includes cross-linked silicone oil and chain-extended silicone oil, wherein the molar ratio of silanol groups in the cross-linked silicone oil to vinyl groups in the sealant is 0.2 to 0.5, and the molar ratio of silanol groups in the chain-extended silicone oil to vinyl groups in the sealant is 0.7 to 1.

[0019] Preferably, the chain-extended hydrosilicone oil has a viscosity of 10-100 mPa·s and a hydrogen content of 0.03%-0.2%.

[0020] Preferably, the crosslinked hydrosilicone oil has a viscosity of 20–500 mPa·s and a hydrogen content of 0.1%–0.5%.

[0021] Crosslinked hydrosilicone oil is a polysiloxane with three hydrogen atoms bonded to silicon atoms. Its main function is crosslinking and curing, which helps ensure the tensile strength of the cured silicone sealant. Chain-extended hydrosilicone oil is a polysiloxane with two hydrogen atoms bonded to silicon atoms. These hydrogen atoms are terminal chain hydrogen atoms. Its main function is chain extension, which helps improve the toughness and elongation at break of the sealant.

[0022] Preferably, the M / Q value of the MQ resin is 0.8 to 1.

[0023] Preferably, the MQ resin is a phenyl-containing MQ resin.

[0024] The M / Q ratio of MQ resin affects its dispersibility in sealant systems. Experiments show that MQ resins within the aforementioned ratio range exhibit better dispersibility, promoting superior flowability of the sealant even with high nano-calcium carbonate content, thus improving spray performance. Furthermore, phenyl-containing MQ resins, such as methylphenyl MQ resins or phenyl vinyl MQ resins, exhibit more pronounced steric hindrance in the aforementioned MQ resins, which is beneficial for improving the flowability of the sealant.

[0025] Preferably, the D50 particle size of the nano-calcium carbonate is 10–50 nm.

[0026] Preferably, the D50 particle size of the reinforcing agent is 3–10 μm.

[0027] Preferably, the vinyl silicone oil has a viscosity of 200–2000 mPa·s and a vinyl content of 0.08–0.25 mmol / g.

[0028] Preferably, the sealant has a tensile strength greater than 1.5 MPa and an elongation at break greater than 150%.

[0029] In summary, this application has the following beneficial effects:

[0030] 1. This application uses nano-calcium carbonate and MQ resin solution together, which can effectively improve the strength of the adhesive layer after curing while ensuring the spraying performance of the sealant, thus achieving a good insulation protection effect.

[0031] 2. By using a phenyl-containing MQ resin solution and selecting an MQ resin with an appropriate M / Q value, this application can further improve the flowability of the sealant and enhance its spraying performance under high nano-calcium carbonate dosage. Detailed Implementation

[0032] Example

[0033] Example 1

[0034] The single-component liquid silicone sealant is prepared by mixing vinyl silicone oil, MQ resin solution, hydrogen-containing silicone oil, filler, platinum catalyst, and inhibitor under vacuum conditions of -0.08 to -0.1 MPa. The specific formulation is shown in Table 1.

[0035] Table 1. Raw material ratio of the single-component silicone sealant in Example 1

[0036]

[0037]

[0038] In Table 1, MQ resin solution is a mixture of vinyl MQ resin and vinyl silicone oil. Chain extender hydrogen refers to the hydroxyl content of the chain extender hydrogen silicone oil in the sealant; crosslinking hydrogen refers to the hydroxyl content of the crosslinking hydrogen silicone oil in the sealant; hydroxyl group refers to the total hydroxyl content of the silicone sealant; vinyl group refers to the total vinyl content of the silicone sealant.

[0039] Example 2

[0040] A two-component liquid silicone sealant is prepared by mixing component A and component B in a 1:1 mass ratio under a vacuum of -0.08 to -0.1 MPa. Component A is prepared by mixing vinyl silicone oil, MQ resin solution, crosslinked hydrosilicone oil, chain-extended hydrosilicone oil, nano-calcium carbonate, reinforcing agent, and inhibitor under a vacuum of -0.08 to -0.1 MPa. Specific formulations are shown in Table 2.

[0041] Table 2, Raw material ratio of two-component silicone sealant in Example 2

[0042]

[0043]

[0044]

[0045] In Table 1, MQ resin solution is a mixture of vinyl MQ resin and vinyl silicone oil. Chain extender hydrogen refers to the hydroxyl content of the chain extender hydrogen silicone oil in the sealant; crosslinking hydrogen refers to the hydroxyl content of the crosslinking hydrogen silicone oil in the sealant; and hydroxyl-based sealant contains all hydroxyl groups. Vinyl refers to the total vinyl content of the sealant.

[0046] Examples 2-5

[0047] The two-component liquid silicone sealant differs from Example 2-1 in that an equal amount of phenyl vinyl MQ resin solution is used instead of vinyl MQ resin solution, with a viscosity of 8500 mPa·s. This phenyl vinyl MQ resin solution is a mixture of phenyl vinyl MQ resin (Delta DT6301) and vinyl silicone oil, with a resin content of 50 wt%.

[0048] Examples 2-6

[0049] The two-component liquid silicone sealant differs from that in Example 2-1 in that the M / Q value of the vinyl MQ resin is 0.6.

[0050] Examples 2-7

[0051] The two-component liquid silicone sealant differs from that in Example 2-1 in that the M / Q value of the vinyl MQ resin is 1.5.

[0052] Comparative Example

[0053] Comparative Example 1

[0054] The two-component liquid silicone sealant differs from that in Example 2-1 in that an equal amount of vinyl silicone oil (500 mPa·s, vinyl content 0.15 mmol / g) is used to replace the MQ resin solution in both components A and B.

[0055] Comparative Example 2

[0056] The two-component liquid silicone sealant differs from that in Example 2-1 in that, in both component A and component B, 10% by weight of nano-calcium carbonate is used instead of 10% by weight of reinforcing agent.

[0057] Comparative Example 3

[0058] The two-component liquid silicone sealant differs from that in Example 2-1 in that, in both component A and component B, 15% of the sealant weight of reinforcing agent is used instead of 15% of the sealant weight of nano-calcium carbonate.

[0059] Comparative Example 4

[0060] The two-component liquid silicone sealant differs from that in Example 2-1 in that, in both component A and component B, an equal amount of nano-calcium carbonate with an oil absorption value of 20g / 100g is used instead of nano-calcium carbonate with an oil absorption value of 30g / 100g.

[0061] Comparative Example 5

[0062] The two-component liquid silicone sealant differs from that in Example 2-1 in that, in both component A and component B, an equal amount of nano-calcium carbonate with an oil absorption value of 70g / 100g is used instead of nano-calcium carbonate with an oil absorption value of 30g / 100g.

[0063] Performance testing

[0064] 1. Viscosity: The dynamic viscosity (mPa·s) of the sealant was measured according to GB / T 10247-2008 "Viscosity Measurement Method - Rotation Method".

[0065] 2. Flowability: Pour 3-5g of silicone sealant (mixed components A and B) onto one end of a glass slide that is 120mm long and 25mm wide. Then quickly invert the slide and wait for the sealant to cure. Peel the sealant off the glass slide and test its thickness. The thickness should be no less than 0.5mm.

[0066] 3. Tensile strength and elongation at break of sealant: determined in accordance with GB / T 528-2009.

[0067] 4. Breakdown voltage: Measured in accordance with GB / T 1695-2005.

[0068] Table 3. Performance Test Results

[0069]

[0070] As can be seen from Examples 1, 2, and Comparative Examples 1 to 5, and Table 3, this application, by using nano-calcium carbonate with an oil absorption value of 30-60 g / 100 g in combination with MQ resin solution, can maintain the sealant in a liquid state even with a high amount of nano-calcium carbonate, ensuring the sealant's fluidity and thixotropic properties, and completing the spraying and adhesion of the sealant to the substrate surface.

[0071] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A liquid silicone sealant, characterized in that, The sealant comprises vinyl silicone oil, MQ resin solution, hydrogen-containing silicone oil, filler, and platinum catalyst; the viscosity of the sealant is 8500–12000 mPa·s, and the molar ratio of hydroxyl to vinyl groups is 1–1.4; the filler includes at least nano-calcium carbonate with an oil absorption value of 30–60 g / 100 g, and the amount of nano-calcium carbonate is 15–30% of the sealant weight%. The MQ resin solution is a silicone oil solution of MQ resin, and the amount of MQ resin used is 5 to 15 times the weight of the sealant.

2. The liquid silicone sealant according to claim 1, characterized in that, The filler also includes 20-35% by weight of a reinforcing agent, wherein the reinforcing agent is selected from one or more of silica powder, alumina, titanium dioxide, aluminum hydroxide, and talc.

3. The liquid silicone sealant according to claim 1, characterized in that, The viscosity of the MQ resin solution is less than or equal to 20000 mPa·s.

4. The liquid silicone sealant according to claim 1, characterized in that, The hydrogen-containing silicone oil includes cross-linked silicone oil and chain-extended silicone oil. The molar ratio of silanol groups in the cross-linked silicone oil to vinyl groups in the sealant is 0.2 to 0.5, and the molar ratio of silanol groups in the chain-extended silicone oil to vinyl groups in the sealant is 0.7 to 1.

5. The liquid silicone sealant according to claim 1, characterized in that, The M / Q value of the MQ resin is 0.8 to 1.

6. The liquid silicone sealant according to claim 1, characterized in that, The MQ resin is a phenyl-containing MQ resin.

7. The liquid silicone sealant according to claim 1, characterized in that, The D50 particle size of nano-calcium carbonate is 10–50 nm.

8. The liquid silicone sealant according to claim 2, characterized in that, The D50 particle size of the reinforcing agent is 3–10 μm.

9. The liquid silicone sealant according to claim 1, characterized in that, The vinyl silicone oil has a viscosity of 200–2000 mPa·s and a vinyl content of 0.08–0.25 mmol / g.

10. A liquid silicone sealant according to claim 1, characterized in that, The sealant has a tensile strength greater than 1.5 MPa and an elongation at break greater than 150%.

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