An insulating fire-retardant plugging material with self-leveling function

Abstract

The present application relates to a kind of insulating fire-retardant plugging material with self-leveling function, belong to coating technical field.The plugging material's weight parts component is: room temperature vulcanizing silicone rubber 100 parts, dimethyl silicone oil 12-18 parts, white carbon black 10-15 parts, nano calcium 5-8 parts, active calcium 15-22 parts, DOPO-MPEG derivative 6-8.5 parts, catalyst 0.5-0.7 parts and curing agent 1.3-1.7 parts;DOPO-MPEG derivative is substituted by vinyltrichlorosilane and polyethylene glycol monomethyl ether, forms the intermediate with branched polyether chain, then with DOPO addition and become, it occurs multiple points, weak interaction with silicone rubber macromolecular chain, form numerous low interaction force micro unit, avoid with silicone rubber macromolecule form excessive entanglement, while improve the dispersibility of filler component, significantly improve the leveling property, flame retardancy and insulation.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically, it relates to an insulating and flame-retardant sealing material with self-leveling function. Background Technology

[0002] During the installation and operation of power equipment, sealing the equipment base, cable conduit openings, and the bottom of the cabinet is a crucial step. Effective sealing prevents moisture, dampness, and corrosive chemicals from entering the equipment, thereby avoiding serious safety hazards such as electrical short circuits, equipment corrosion, and decreased insulation performance, and ensuring the long-term stable operation of the power system. Therefore, the performance requirements for sealing materials are extremely high, requiring excellent sealing properties, durability, insulation, flame retardancy, and ease of construction.

[0003] Currently, common sealing materials for power equipment on the market mainly include cement mortar, epoxy resin, and silicone rubber. Cement mortar is inexpensive, but it has poor flexibility, is prone to cracking, has a short-lasting sealing effect, and generally poor insulation performance. Epoxy resin has high hardness and good sealing performance, but it has high internal stress after curing, is prone to brittleness, and is difficult to excavate again, which is not conducive to equipment maintenance. Room temperature vulcanizing silicone rubber, on the other hand, has become the first choice for high-performance sealing materials due to its excellent flexibility, resistance to high and low temperatures, aging resistance, good insulation, and inherent flame retardancy.

[0004] However, traditional silicone rubber-based sealing materials still have significant drawbacks: they are inherently thixotropic and have poor flowability. To impart higher flame-retardant, insulating, and reinforcing properties, large amounts of fillers such as silica and nano-calcium, as well as flame retardants, are required. The addition of these fillers further deteriorates the system's leveling properties, making it difficult for the material to automatically level and fill gaps under its own weight during application, resulting in an uneven surface that affects the final sealing effect and aesthetics.

[0005] In existing technologies, this problem is typically addressed by adding leveling agents. However, traditional leveling agents have limited compatibility with silicone rubber systems and are mostly linear in structure. While improving leveling properties, they may migrate to the surface, causing stickiness, or have weak interaction with fillers, failing to fundamentally solve the problem of filler dispersion and flow in highly filled systems. Their improvement effect is often insignificant, or they perform poorly in reducing dynamic surface tension, failing to simultaneously achieve high leveling during application and comprehensive performance after curing. Therefore, developing a novel additive and sealing material that can significantly improve the leveling properties of highly filled silicone rubber systems without compromising their core properties such as insulation and flame retardancy has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide an insulating and flame-retardant sealing material with self-leveling function.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] An insulating and flame-retardant sealing material with self-leveling function comprises, by weight: 100 parts room temperature vulcanizing silicone rubber, 12-18 parts dimethyl silicone oil, 10-15 parts silica, 5-8 parts nano-calcium, 15-22 parts active calcium, 6-8.5 parts DOPO-MPEG derivative, 0.5-0.7 parts catalyst, and 1.3-1.7 parts curing agent.

[0009] The DOPO-MPEG derivative is prepared by the following method:

[0010] Step A1: Mix MPEG, triethylamine and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, slowly add vinyltrichlorosilane at room temperature and stir for 1.5-2 h, then heat to reflux for 0.5-1 h. After the reaction is complete, filter to remove salts, then remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0011] Furthermore, the ratio of vinyltrichlorosilane, the hydroxyl content of MPEG, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.3 mol: 25-35 mL: 180-260 mL. MPEG undergoes a substitution reaction with vinyltrichlorosilane to form a compound with branched short polyether chains.

[0012] Preferably, the average molecular weight of MPEG is not higher than 300. The branched structure formed under the short polyether chain has less entanglement with the silicone rubber macromolecular chain, resulting in better leveling promotion performance.

[0013] Step A2: Mix DOPO, azobisisobutyronitrile and dioxane, then add the intermediate and mix well. Control the reaction temperature in a water bath at 60-70℃ and stir for 4.5-6 hours. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the DOPO-MPEG derivative.

[0014] Furthermore, the ratio of intermediate, DOPO, azobisisobutyronitrile and dioxane is 100g: 0.15-0.22mol: 0.3-0.4g: 220-300mL, and DOPO undergoes an addition reaction with the vinyl group in the intermediate molecule.

[0015] Preferably, the nano-calcium is nano-calcium carbonate treated with surface stearic acid. The nano-scale filler improves the sealing density, and the surface stearic acid treatment reduces agglomeration, resulting in good dispersibility in the silicone rubber matrix.

[0016] Preferably, the catalyst is dibutyltin dilaurate, which has a highly efficient catalytic effect on the room temperature curing of silicone rubber.

[0017] Preferably, the curing agent is methyl tributanone oxime silane, which has good crosslinking activity with silicone rubber at room temperature and a moderate curing time, which is beneficial for the curing of the sealing material.

[0018] A method for preparing an insulating and flame-retardant sealing material with self-leveling function is as follows: dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent are premixed in a dry nitrogen atmosphere, then room temperature vulcanized silicone rubber is added and mixed, and finally silica, nano-calcium and active calcium are added and mixed evenly to obtain the insulating and flame-retardant sealing material.

[0019] The beneficial effects of this invention are:

[0020] The sealing material and special additive DOPO-MPEG derivative provided by this invention, compared with the prior art, has short branched polyether chains. Unlike existing linear leveling agents, the branched polyether short chains provide multiple anchor points, enabling multi-point, weak interactions with silicone rubber macromolecular chains. This interaction effectively disrupts the strong interaction network between silicone rubber molecular chains, forming numerous micro-units with low interaction forces, thus avoiding excessive entanglement with silicone rubber macromolecules. This results in excellent leveling promotion on a macroscopic scale. Simultaneously, its multiple polyether segments can fully encapsulate and wet filler particles such as silica and nano-calcium, preventing filler agglomeration through steric hindrance, greatly improving the dispersibility and flowability of fillers in high-viscosity matrices. Thanks to the improved filler dispersibility, a dense and uniform cured network structure is formed, effectively eliminating electrical weaknesses and flame retardant defects caused by filler agglomeration and bubbles. This improves both insulation and flame retardancy after sealing, achieving a highly efficient and stable sealing effect. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: Preparation of an insulating and flame-retardant sealing material with self-leveling function. The specific implementation method is as follows:

[0023] (1) Preparation of DOPO-MPEG derivatives

[0024] Step A1: Mix MPEG (polyethylene glycol monomethyl ether), triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, slowly add vinyltrichlorosilane at room temperature and stir for 2 hours, then reflux for 1 hour. The ratio of vinyltrichlorosilane, hydroxyl content of MPEG, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.3 mol: 25 mL: 260 mL. MPEG-200 is used. After the reaction is complete, filter to remove salts, then remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0025] Step A2: Mix DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), azobisisobutyronitrile, and dioxane, then add the intermediate and mix well. Stir the reaction system at 70℃ in a water bath for 6 hours. The ratio of intermediate, DOPO, azobisisobutyronitrile, and dioxane is 100g:0.22mol:0.3g:300mL. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the DOPO-MPEG derivative.

[0026] (2) Preparation of sealing materials

[0027] Raw materials are prepared in parts by weight as follows: 100 parts room temperature vulcanizing silicone rubber, using commercially available 107 rubber; 12 parts dimethyl silicone oil, using commercially available 201 type silicone oil; 10 parts silica, using commercially available HL-300 type fumed silica; 8 parts nano calcium, using commercially available CCS-18 type raw material with a surface treated with stearic acid; 19 parts activated calcium, using commercially available D-1250A type raw material; 6 parts DOPO-MPEG derivative, prepared in this embodiment; 0.5 parts catalyst, using commercially available industrial grade dibutyltin dilaurate; and 1.3 parts curing agent, using commercially available industrial grade methyl tributanone oxime silane.

[0028] Dry nitrogen gas was introduced into the mixer for protection. Dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent were added in sequence and quickly stirred for premixing. Then room temperature vulcanized silicone rubber was added and stirred at low speed. Finally, silica, nano calcium and active calcium were added and mixed evenly to obtain an insulating and flame-retardant sealing material.

[0029] Example 2: Preparation of an insulating and flame-retardant sealing material with self-leveling function. The specific implementation method is as follows:

[0030] (1) Preparation of DOPO-MPEG derivatives

[0031] Step A1: Mix MPEG, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, slowly add vinyltrichlorosilane at room temperature and stir for 1.8 h, then reflux for 0.9 h. The ratio of vinyltrichlorosilane, MPEG hydroxyl content, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.3 mol: 28 mL: 260 mL. MPEG-200 is used. After the reaction is complete, filter to remove salts, then remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0032] Step A2: Mix DOPO, azobisisobutyronitrile, and dioxane, then add the intermediate and mix well. Stir the reaction system at 70℃ in a water bath for 5.5 h. The ratio of intermediate, DOPO, azobisisobutyronitrile, and dioxane is 100 g: 0.22 mol: 0.3 g: 280 mL. After the reaction is complete, remove dioxane by rotary evaporation under reduced pressure to obtain the DOPO-MPEG derivative.

[0033] (2) Preparation of sealing materials

[0034] Raw materials are prepared in parts by weight as follows: 100 parts room temperature vulcanizing silicone rubber, using commercially available 107 rubber; 14 parts dimethyl silicone oil, using commercially available 201 type silicone oil; 15 parts silica, using commercially available HL-300 type fumed silica; 5 parts nano calcium, using commercially available CCS-18 type raw material with a surface treated with stearic acid; 15 parts activated calcium, using commercially available D-1250A type raw material; 6.8 parts DOPO-MPEG derivative, prepared in this embodiment; 0.6 parts catalyst, using commercially available industrial grade dibutyltin dilaurate; and 1.5 parts curing agent, using commercially available industrial grade methyl tributanone oxime silane.

[0035] Dry nitrogen gas was introduced into the mixer for protection. Dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent were added in sequence and quickly stirred for premixing. Then room temperature vulcanized silicone rubber was added and stirred at low speed. Finally, silica, nano calcium and active calcium were added and mixed evenly to obtain an insulating and flame-retardant sealing material.

[0036] Example 3: Preparation of an insulating and flame-retardant sealing material with self-leveling function. The specific implementation method is as follows:

[0037] (1) Preparation of DOPO-MPEG derivatives

[0038] Step A1: Mix MPEG, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, slowly add vinyltrichlorosilane at room temperature and stir for 1.5 h, then reflux for 0.5 h. The ratio of vinyltrichlorosilane, hydroxyl content of MPEG, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.3 mol: 35 mL: 220 mL. MPEG-100 is used. After the reaction is complete, filter to remove salts, then remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0039] Step A2: Mix DOPO, azobisisobutyronitrile, and dioxane, then add the intermediate and mix well. Stir the reaction system at 60℃ in a water bath for 4.5 h. The ratio of intermediate, DOPO, azobisisobutyronitrile, and dioxane is 100 g: 0.15 mol: 0.4 g: 250 mL. After the reaction is complete, remove dioxane by rotary evaporation under reduced pressure to obtain the DOPO-MPEG derivative.

[0040] (2) Preparation of sealing materials

[0041] Raw materials are prepared in parts by weight as follows: 100 parts of room temperature vulcanizing silicone rubber, using commercially available 107 rubber; 16 parts of dimethyl silicone oil, using commercially available 201 type silicone oil; 11 parts of silica, using commercially available HL-300 type fumed silica; 6 parts of nano calcium, using commercially available CCS-18 type raw material with a surface treated with stearic acid; 22 parts of active calcium, using commercially available D-1250A type raw material; 7.9 parts of DOPO-MPEG derivative, prepared in this embodiment; 0.7 parts of catalyst, using commercially available industrial grade dibutyltin dilaurate; and 1.6 parts of curing agent, using commercially available industrial grade methyl tributanone oxime silane.

[0042] Dry nitrogen gas was introduced into the mixer for protection. Dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent were added in sequence and quickly stirred for premixing. Then room temperature vulcanized silicone rubber was added and stirred at low speed. Finally, silica, nano calcium and active calcium were added and mixed evenly to obtain an insulating and flame-retardant sealing material.

[0043] Example 4: Preparation of an insulating and flame-retardant sealing material with self-leveling function. The specific implementation method is as follows:

[0044] (1) Preparation of DOPO-MPEG derivatives

[0045] Step A1: Mix MPEG, triethylamine, and anhydrous tetrahydrofuran, purge with dry nitrogen for protection, slowly add vinyltrichlorosilane at room temperature and stir for 1.8 h, then reflux for 0.6 h. The ratio of vinyltrichlorosilane, hydroxyl content of MPEG, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 0.3 mol: 32 mL: 180 mL. MPEG-100 is used. After the reaction is complete, filter to remove salts, then remove tetrahydrofuran by rotary evaporation to obtain the intermediate.

[0046] Step A2: Mix DOPO, azobisisobutyronitrile, and dioxane, then add the intermediate and mix well. Stir the reaction system at 65℃ in a water bath for 5 hours. The ratio of intermediate, DOPO, azobisisobutyronitrile, and dioxane is 100g:0.17mol:0.35g:220mL. After the reaction is completed, remove dioxane by rotary evaporation under reduced pressure to obtain the DOPO-MPEG derivative.

[0047] (2) Preparation of sealing materials

[0048] Raw materials are prepared in parts by weight as follows: 100 parts room temperature vulcanizing silicone rubber, using commercially available 107 rubber; 18 parts dimethyl silicone oil, using commercially available 201 type silicone oil; 13 parts silica, using commercially available HL-300 type fumed silica; 7 parts nano calcium, using commercially available CCS-18 type raw material with a surface treated with stearic acid; 20 parts activated calcium, using commercially available D-1250A type raw material; 8.5 parts DOPO-MPEG derivative, prepared in this embodiment; 0.7 parts catalyst, using commercially available industrial grade dibutyltin dilaurate; and 1.7 parts curing agent, using commercially available industrial grade methyl tributanone oxime silane.

[0049] Dry nitrogen gas was introduced into the mixer for protection. Dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent were added in sequence and quickly stirred for premixing. Then room temperature vulcanized silicone rubber was added and stirred at low speed. Finally, silica, nano calcium and active calcium were added and mixed evenly to obtain an insulating and flame-retardant sealing material.

[0050] Comparative Example 1, referring to Example 3, replaced DOPO-MPEG derivative with 1.8 parts DOPO and 6.1 parts leveling agent BYK-333, with the rest of the implementation process being exactly the same.

[0051] Comparative Example 2, referring to Example 3, replaces the DOPO-MPEG derivative with 1.8 copies of DOPO and 6.1 copies of MPEG-200, and the rest of the implementation process is exactly the same.

[0052] Samples were taken from the sealing material prepared above and tested as follows:

[0053] Static flow diameter test: Place 50g of uncured sealing adhesive sample in the center of a horizontally placed glass plate (standard environment 23±2℃, 50±5%RH) and allow it to flow naturally. After standing for 30 minutes, measure its flow diameter.

[0054] Dynamic surface tension test: Refer to GB / T27842-2011 standard, use a dynamic surface tension meter to measure the dynamic surface tension when the surface lifetime is 1000ms.

[0055] Limiting oxygen index test: In accordance with GB / T2406.2-2009 standard, a sample with a specification of 80mm×10mm×4mm was prepared by curing in a mold for 24 hours, and its limiting oxygen index was measured using an oxygen index meter.

[0056] Insulation test: In accordance with GB / T1408.1-2016 standard, a sample with a specification of Φ100mm×1mm was prepared by curing in a mold for 24 hours, and its breakdown voltage was tested using a withstand voltage tester.

[0057] The specific test results are shown in Table 1:

[0058] Table 1

[0059]

[0060] As can be seen from the test data in Table 1, the addition of DOPO-MPEG derivatives significantly reduced the dynamic surface tension of the sealing material and significantly increased the leveling diameter, fully meeting the requirements of self-leveling construction. Furthermore, with the introduction of similar organophosphorus content, the limiting oxygen index increased, and with the same filler addition, the breakdown voltage was noticeably improved. This indicates that DOPO-MPEG derivatives promoted the dispersion of the overall components and reduced the formation of local defects.

[0061] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. An insulating fire-retardant sealing material with self-leveling function, characterized in that, According to parts by weight, including: 100 parts of room temperature vulcanizing silicone rubber, 12-18 parts of dimethyl silicone oil, 10-15 parts of white carbon black, 5-8 parts of nano calcium, 15-22 parts of active calcium, 6-8.5 parts of DOPO-MPEG derivative, 0.5-0.7 parts of catalyst and 1.3-1.7 parts of curing agent; Wherein, the DOPO-MPEG derivative is prepared by the following method: Step A1: mixing MPEG, triethylamine and anhydrous tetrahydrofuran, protecting with dry nitrogen, slowly adding vinyltrichlorosilane at room temperature, stirring for 1.5-2h, then heating to reflux for 0.5-1h to prepare an intermediate; Step A2: mixing DOPO, azobisisobutyronitrile and dioxane, then adding the intermediate and stirring, controlling the reaction system temperature at 60-70 DEG C in water bath for 4.5-6h to prepare the DOPO-MPEG derivative.

2. The self-leveling insulating fire-stopping material according to claim 1, wherein, The amount ratio of vinyltrichlorosilane, the hydroxyl content of MPEG, triethylamine and anhydrous tetrahydrofuran is 0.1mol:0.3mol:25-35mL:180-260mL.

3. The self-leveling insulating fire-stopping material according to claim 2, wherein, The average molecular weight of MPEG is not higher than 300.

4. The self-leveling insulating fire-stopping material of claim 2, wherein, The amount ratio of the intermediate, DOPO, azobisisobutyronitrile and dioxane is 100g:0.15-0.22mol:0.3-0.4g:220-300mL.

5. The self-leveling insulating fire-stopping material of claim 1, wherein, The nano calcium is surface stearic acid treated nano calcium carbonate.

6. The self-leveling insulating fire-stopping material of claim 1, wherein, The catalyst is dibutyltin dilaurate.

7. The self-leveling insulating fire-stopping material of claim 1, wherein, The curing agent is methyltributylketoximosilane.

8. The self-leveling insulating fire-stopping material of claim 1, wherein, The specific preparation method is: mixing dimethyl silicone oil, DOPO-MPEG derivative, catalyst and curing agent under dry nitrogen atmosphere, then adding room temperature vulcanizing silicone rubber, finally adding white carbon black, nano calcium and active calcium and mixing to obtain the insulating flame-retardant sealing material.

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