Dealcoholized organosilicon sealant and preparation method thereof

Abstract

The invention relates to the technical field of sealants, and particularly discloses a dealcoholization type organic silicon sealant and a preparation method thereof.The dealcoholization type organic silicon sealant is prepared from, by weight, 20-60 parts of methoxy-terminated 107 glue with the viscosity being 20000-80000 mPa.s, 0.5-20 parts of methoxy-terminated 107 glue with the viscosity being 1000-5000 mPa.s, 0.2 part of black paste and 2-10 parts of methyltrimethoxysilane, and the dealcoholization type organic silicon sealant is prepared from, by weight, 20-60 parts of methoxy-terminated 107 glue with the viscosity being 20000-80000 mPa.s, 0.5-20 parts of methoxy-terminated 107 glue with the viscosity being 1000-5000 mPa.s, 0.2 part of black paste and 2-10 parts of methyltrimethoxysilane. The sealant comprises the following components in parts by weight: 10-40 parts of nano calcium carbonate, 0.2-5 parts of a simple coupling agent, 1-7 parts of a complex coupling agent, 0.2-2 parts of chelated titanate and 0.01-0.15 part of an organic tin catalyst, and the sealant provided by the invention can be physically and chemically bonded with hydroxyl of an aluminum oxide thin layer of a micro-interface on the surface of an aluminum alloy, so that the bonding force of an oil stain interface is effectively enhanced.

Description

Technical Field

[0001] This invention relates to the field of sealant technology, and more particularly to de-alcoholized silicone sealants and their preparation methods. Background Technology

[0002] There are two existing types of FIPG all-in-one electric drive sealants: First, ketoxime-free single-component silicone sealants. This type of silicone sealant features fast surface drying, fast curing, and oil resistance. However, ketoximes can corrode materials such as copper and polycarbonate, and when used in all-in-one electric drives, they can corrode PCBA boards. Especially after installation, the all-in-one electric drive essentially forms a completely sealed space, where the volatilized small molecules maintain a high concentration, continuously corroding the PCBA board. Therefore, ketoxime-free sealants are obsolete in electric drive factories. Second, methanol-free single-component silicone sealants. Traditional methanol-free single-component silicone sealants use aminosilanes / epoxysilanes / acryloyloxysilanes as tackifiers, often making it difficult to simultaneously achieve fast curing and oil resistance. Oil-resistant adhesion requires sufficient wetting time, while fast curing requires a rapid reaction. This means that the effective components in the adhesive may not have fully wetted / displaced the oil on the surface before curing, failing to form an effective bond. Summary of the Invention

[0003] To address the problems mentioned in the background art, one of the objectives of this invention is to provide a de-alcoholized silicone sealant.

[0004] The de-alcoholized silicone sealant comprises, by weight, the following components: 20-60 parts of methoxy-terminated 107 adhesive with a viscosity of 20000-80000 mPa·s, 0.5-20 parts of methoxy-terminated 107 adhesive with a viscosity of 1000-5000 mPa·s, 0.2 parts of black paste, 2-10 parts of methyltrimethoxysilane, 10-40 parts of nano-calcium carbonate, 0.2-5 parts of simple coupling agent, 1-7 parts of complex coupling agent, 0.2-2 parts of chelated titanate, and 0.01-0.15 parts of organotin catalyst. The black paste is composed of 20% carbon black and 80% methyl silicone oil with a viscosity of 500 mPa·s. The simple coupling agent contains amino and / or long-chain alkyl groups, and the complex coupling agent contains polymers with the following molecular formulas, where R1-R5 are alkoxy or hydroxyl groups:

[0005] .

[0006] Furthermore, the preparation method of the complex coupling agent is as follows:

[0007] 1) Mix 20-40 parts of anhydrous ethanol and 40-80 parts of octyltriethoxysilane to obtain mixture A;

[0008] 2) Mix 3-6 parts of deionized water and 20-70 parts of anhydrous ethanol to obtain mixture B;

[0009] 3) Heat mixture A until the temperature reaches 50°C, then slowly add 10-75 parts of the mixture to mixture A to obtain mixture C;

[0010] 4) Add KH550 to mixture C to obtain mixture D;

[0011] 5) Slowly add the remaining mixture B to mixture D, heat to 60-65℃, react for 5 hours, and then distill under reduced pressure at 60℃ until no more bubbles emerge within 2-3 minutes to obtain the complex coupling agent.

[0012] This preparation method includes at least the following six reactions, where R1-R5 may have 0-5 -OH groups, with an example where all R1-R5 are -OH groups:

[0013]

[0014] The first reaction is the hydrolysis of octyltriethoxysilane, where the ethoxy group hydrolyzes to a silanol. The second reaction is the hydrolysis of KH550, where the ethoxy group hydrolyzes to a silanol. The third reaction is the condensation polymerization of the octyltriethoxysilane hydrolysate and the KH550 hydrolysate, resulting in a dimer, chemically named 1-octyl-3-(3-aminopropyl)tetrahydroxydisiloxane. The fourth reaction is the self-polymerization of the KH550 hydrolysate, resulting in a dimer, chemically named 1,3-bis(3-aminopropyl)tetrahydroxydisiloxane. The fifth reaction is the self-polymerization of the octyltriethoxysilane hydrolysate, resulting in a dimer, chemically named 1,3-bis(n-octyl)tetrahydroxydisiloxane. The sixth reaction is the condensation polymerization of the product of the third reaction with the octylsilane hydrolysate, resulting in a trimer, chemically named 3-(3-aminopropyl)-1,5-dioctyltrisiloxane-1,1,3,5,5-pentaol. Among them, the product of the sixth reaction serves as an effective component of the complex coupling agent.

[0015] Furthermore, in the preparation of the complex coupling agent, the mass ratio of octyltriethoxysilane to KH550 is 2.5-3.9:1.

[0016] Furthermore, the chelated titanate is TCA-AA75 or Tyzor 726.

[0017] Furthermore, the organotin catalyst is dibutyltin dilaurate.

[0018] Furthermore, the simple coupling agent is octyltrimethoxysilane.

[0019] This invention also provides a method for preparing the de-alcoholized silicone sealant, the method comprising the following steps:

[0020] S1: Add methoxy-terminated 107 glue, black paste, and nano calcium carbonate to a power mixer and stir and disperse for 30 minutes;

[0021] S2: Turn on heating and vacuuming, set the material temperature to 120℃, start timing after reaching the temperature, remove water for 120 minutes;

[0022] S3: After cooling to 20-30℃, add complex coupling agent and simple coupling agent, and stir for 5 minutes;

[0023] S4: Add methyltrimethoxysilane and stir under vacuum for 15 minutes;

[0024] S5: After adding the chelated titanate component and stirring for 5 minutes, add the organotin catalyst and stir for 25 minutes to obtain the de-alcoholized organosilicon sealant.

[0025] The beneficial effects of this invention are as follows: 1. This invention targets oily interfaces by adding a complex coupling agent to the sealant. The complex coupling agent contains a condensation polymer of octyltriethoxysilane hydrolysate and KH550 hydrolysate, with a degree of polymerization between 2 and 6 and a molecular weight between 500 and 2000. It has good migration properties in silicone sealants. The long-chain alkyl groups in the complex coupling agent can replace the oily molecules on the aluminum alloy surface to be bonded. The amino groups in the complex coupling agent can physically and chemically bond with the hydroxyl groups of the alumina thin layer on the micro-interface of the aluminum alloy surface, effectively enhancing the adhesion of the oily interface.

[0026] 2. Because complex coupling agents have long-chain alkyl structures, they have good compatibility in organosilicon matrices. Moreover, the large proportion of long-chain alkyl groups can effectively shield the activity of amino groups and reduce the reactivity of amino groups with chelated titanates, thereby avoiding the problem of decreased storage stability caused by excessive reaction between amino groups and titanates.

[0027] 3. This invention addresses the need for rapid curing in the sealing process of electric drive modules by employing a combination of chelated titanium and organotin. Through a synergistic catalytic system of a large amount of chelated titanate and a small amount of organotin, rapid surface drying and deep curing are achieved. Detailed Implementation

[0028] The technical solution 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 skilled in the art are within the protection scope of the present invention.

[0029] The formulations of complex coupling agents are shown in Table 1:

[0030] Table 1

[0031]

[0032] The synthesis process is as follows:

[0033] Complex coupling agent 1

[0034] 1. In a four-necked flask equipped with a reflux condenser, stirrer and thermometer, add 45g of anhydrous ethanol and 70g of OTES and start stirring.

[0035] 2. Mix 5.8g of deionized water and 5g of anhydrous ethanol;

[0036] 3. Turn on the heating. After the material temperature rises to 50℃, add the mixture from step 2 dropwise into the four-necked flask through a dropping funnel. Control the dropping rate and add 5g of the mixture from the dropping funnel within 10 minutes.

[0037] 4. Add KH550 to the four-necked flask;

[0038] 5. Add the remaining mixture in the dropping funnel from step 3, completing the addition within 20-30 minutes;

[0039] 6. Increase the temperature to 60-65℃ and react for 5 hours;

[0040] 7. Distill the synthesized product under reduced pressure at 60℃ until no more bubbles emerge within 2-3 minutes;

[0041] 8. After cooling to room temperature, seal and store in a plastic bottle.

[0042] Complex coupling agent 2

[0043] 1. In a four-necked flask equipped with a reflux condenser, stirrer and thermometer, add 45g of anhydrous ethanol and 70g of OTES and start stirring.

[0044] 2. Mix 3g of deionized water and 5g of anhydrous ethanol;

[0045] 3. Turn on the heating. After the material temperature rises to 50℃, add the mixture from step 2 dropwise into the four-necked flask through a dropping funnel. Control the dropping rate and add 5g of the mixture from the dropping funnel within 10 minutes.

[0046] 4. Add KH550 to the four-necked flask;

[0047] 5. Add the remaining mixture in the dropping funnel from step 3, completing the addition within 20-30 minutes;

[0048] 6. Increase the temperature to 60-65℃ and react for 5 hours;

[0049] 7. Distill the synthesized product under reduced pressure at 60℃ until no more bubbles emerge within 2-3 minutes;

[0050] 8. After cooling to room temperature, seal and store in a plastic bottle.

[0051] Complex coupling agent 3

[0052] 1. In a four-necked flask equipped with a reflux condenser, stirrer and thermometer, add 45g of anhydrous ethanol and 80g of OTES and start stirring.

[0053] 2. Mix 5.8g of deionized water and 5g of anhydrous ethanol;

[0054] 3. Turn on the heating. After the material temperature rises to 50℃, add the mixture from step 2 dropwise into the four-necked flask through a dropping funnel. Control the dropping rate and add 5g of the mixture from the dropping funnel within 10 minutes.

[0055] 4. Add KH550 to the four-necked flask;

[0056] 5. Add the remaining mixture in the dropping funnel from step 3, completing the addition within 20-30 minutes;

[0057] 6. Increase the temperature to 60-65℃ and react for 5 hours;

[0058] 7. Distill the synthesized product under reduced pressure at 60℃ until no more bubbles emerge within 2-3 minutes;

[0059] 8. After cooling to room temperature, seal and store in a plastic bottle.

[0060] The dealcohol-based silicone sealant, by weight, comprises the following components:

[0061] 20-60 parts of methoxy-terminated 107 adhesive with a viscosity of 20000-80000 mPa·s, 0.5-20 parts of methoxy-terminated 107 adhesive with a viscosity of 1000-5000 mPa·s, 0.2 parts of black paste, 2-10 parts of methyltrimethoxysilane, 10-40 parts of nano-calcium carbonate, 1-7 parts of complex coupling agent, 0.2-5 parts of simple coupling agent, 0.2-2 parts of chelated titanate, and 0.01-0.15 parts of organotin catalyst.

[0062] The preparation process is as follows:

[0063] S1: Add methoxy-terminated 107 glue, black paste, and nano calcium carbonate to a power mixer and stir and disperse for 30 minutes;

[0064] S2: Turn on heating and vacuuming, set the material temperature to 120℃, start timing after reaching the temperature, remove water for 120 minutes;

[0065] S3: After cooling to 20-30℃, add complex coupling agent and simple coupling agent, and stir for 5 minutes;

[0066] S4: Add methyltrimethoxysilane and stir under vacuum for 15 minutes;

[0067] S5: After adding the chelated titanate component and stirring for 5 minutes, add the organotin catalyst and stir for 25 minutes to obtain the de-alcoholized organosilicon sealant.

[0068] The black paste consists of 20% carbon black and 80% methyl silicone oil with a viscosity of 500 mPa·s.

[0069] For high-viscosity methoxy-terminated 107 adhesive, choose Guangdong Chengtian New Materials' trimethoxy-terminated 107, O-FT200 (20000 mPa·s). For low-viscosity methoxy-terminated 107 adhesive, choose Guangdong Chengtian New Materials' trimethoxy-terminated 107, O-FT15 (2000 mPa·s).

[0070] The complex coupling agent is selected from one of the following: complex coupling agent 1, complex coupling agent 2, or complex coupling agent 3.

[0071] Octyltrimethoxysilane (C8) is selected as the simple coupling agent.

[0072] The chelated titanate is selected from bis(acetylacetone) diisopropyl titanate of Nanjing Nengde New Materials, with the grade TCA-AA75.

[0073] The organotin catalyst selected is dibutyltin dilaurate (DBTDL).

[0074] Examples and comparative examples are shown in Table 2:

[0075] Table 2

[0076]

[0077] The performance test results of the examples and comparative examples are shown in Table 3:

[0078] Table 3

[0079]

[0080] For the above performance tests, the surface drying time test standard was GB / T 13477.5-2017, the shear strength test standard was GB / T 7124-2008, the adhesive failure test standard was GB / T 16997-1997, and the curing depth test standard was GB / T32369-2015. All samples were tested at a temperature of 23±2℃ and a relative humidity of 50±5%.

[0081] In Comparative Example 3, although the initial surface drying time was short and the shear strength before aging was good, after 7 days of storage at 70℃, the surface drying time significantly increased to 23 minutes, the shear strength decreased to 0.05 MPa, and the curing depth also shrank to 1.5 mm, indicating poor stability of the material under storage conditions. This is because the amino group of KH550 has too high activity, causing the catalyst to react with the titanate coupling agent and lose some of its catalytic function. Although an octylsilane coupling agent was added, it was only a physical mixture at this point and could not effectively suppress the side reactions between the amino group and the titanate.

[0082] In Examples 1-6, the octylsilane coupling agent and KH550 were pre-reacted to form a sterically hindered structure, effectively shielding the high reactivity of the amino group in KH550 and preventing side reactions with the titanate coupling agent, thereby maintaining the stability of the catalytic system. It can be seen that before and after high-temperature aging, the surface drying time, curing depth, 2-hour shear strength, and adhesion failure mode remained stable, and the performance degradation rate was within a controllable range, demonstrating good storage stability. Furthermore, the use of a very small amount of organotin catalyst to replace part of the titanate further optimized the balance between surface drying time and curing depth. After aging, the surface drying time remained below 10 minutes, and the curing depth remained above 2 mm, demonstrating excellent deep curing ability and storage stability. Simultaneously, it showed good adhesion to the aluminum and electric drive platform interfaces, exhibiting cohesive failure. This is the best overall performance.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A de-alcoholized silicone sealant, characterized in that, The product comprises, by weight, the following components: 20-60 parts of methoxy-terminated 107 adhesive with a viscosity of 20,000-80,000 mPa·s; 0.5-20 parts of methoxy-terminated 107 adhesive with a viscosity of 1,000-5,000 mPa·s; 0.2 parts of black paste; 2-10 parts of methyltrimethoxysilane; 10-40 parts of nano-calcium carbonate; 0.2-5 parts of simple coupling agent; 1-7 parts of complex coupling agent; 0.2-2 parts of chelated titanate; and 0.01-0.15 parts of organotin catalyst. The black paste is composed of 20% carbon black and 80% methyl silicone oil with a viscosity of 500 mPa·s. The simple coupling agent contains amino and / or long-chain alkyl groups. The complex coupling agent comprises a polymer with the following molecular formula, where R1-R5 are alkoxy or hydroxyl groups: 。 2. The de-alcoholized silicone sealant according to claim 1, characterized in that, The preparation method of the complex coupling agent is as follows: 1) Mix 5-40 parts of anhydrous ethanol and 30-80 parts of octyltriethoxysilane to obtain mixture A; 2) Mix 1-9 parts of deionized water and 5-80 parts of anhydrous ethanol to obtain mixture B; 3) Heat mixture A until the temperature reaches 50°C, then slowly add 4-80 parts of mixture B to mixture A to obtain mixture C; 4) Add KH550 to mixture C to obtain mixture D; 5) Slowly add the remaining mixture B to mixture D, heat to 60-65℃, react for 5 hours, and then distill under reduced pressure at 60℃ until no more bubbles emerge within 2-3 minutes to obtain the complex coupling agent.

3. The de-alcoholized silicone sealant according to claim 2, characterized in that, In the preparation of the complex coupling agent, the mass ratio of octyltriethoxysilane to KH550 is 2.3-3.9:

1.

4. The de-alcoholized silicone sealant according to claim 1, characterized in that, The chelated titanate is either TCA-AA75 or Tyzor 726.

5. The de-alcoholized silicone sealant according to claim 1, characterized in that, The organotin catalyst is dibutyltin dilaurate.

6. The de-alcoholized silicone sealant according to claim 1, characterized in that, The simple coupling agent is octyltrimethoxysilane.

7. The method for preparing the dealcohol-type organosilicon sealant according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Add methoxy-terminated 107 glue, black paste, and nano calcium carbonate to a power mixer and stir and disperse for 30 minutes; S2: Turn on heating and vacuuming, set the material temperature to 120℃, start timing after reaching the temperature, remove water for 120 minutes; S3: After cooling to 20-30℃, add complex coupling agent and simple coupling agent, and stir for 5 minutes; S4: Add methyltrimethoxysilane and stir under vacuum for 15 minutes; S5: After adding the chelated titanate component and stirring for 5 minutes, add the organotin catalyst and stir for 25 minutes to obtain the de-alcoholized organosilicon sealant.

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