Low temperature cure silicone sealant

Abstract

This invention belongs to the field of silicone sealant technology, and relates to a low-temperature curing silicone sealant, comprising: Component A: 20-50 parts vinyl silicone oil, 20-50 parts vinyl MQ resin, 5-20 parts modified hydroxyl silicone oil, 1-20 parts hydrogen-containing silicone oil, 1-10 parts silica, and 0.005-0.1 parts inhibitor; Component B: 20-80 parts vinyl silicone oil, 20-30 parts modified silicone resin, 1-10 parts silica, 1-10 parts KH570, 1-10 parts methyltrimethoxysilane, and 0.05-0.1 parts black pigment. The low-temperature curing silicone sealant of this invention uses modified hydroxyl silicone oil, which improves the heat resistance of the sealant and promotes low-temperature adhesion. The use of modified silicone resin focuses on accelerating the reaction between silicon-hydrogen bonds and vinyl groups, slowing down the reaction between hydroxyl groups and silicon-hydrogen bonds, avoiding hydrogen generation, and thus reducing the probability of bubble formation in the sealant.

Description

Technical Field

[0001] This invention belongs to the field of silicone sealant technology, and particularly relates to a low-temperature curing silicone sealant. Background Technology

[0002] Silicone sealants possess excellent weather resistance, UV resistance, high and low temperature resistance, and hydrophobicity, maintaining good physical properties even in harsh environments. Therefore, they are widely used in construction, electronics, electrical appliances, automotive, and new energy industries. As industries increasingly demand higher production efficiency and product quality stability, higher performance requirements are being placed on silicone sealants.

[0003] Because addition-cure silicone rubber can cure at room temperature and cure rapidly under heating conditions, it has broad application prospects in the rapidly developing fields of intensive electronics and new energy. Traditional addition-cure silicone sealants generally require heating to above 120°C to achieve good adhesion. However, for components already assembled with precision electronic parts, undergoing another high-temperature baking process is unacceptable. Furthermore, moisture-curing silicone has a relatively long curing time. Therefore, reducing the curing temperature of addition-cure silicone sealants is urgently needed. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a low-temperature curing silicone sealant, the specific technical solution of which is as follows:

[0005] A low-temperature curing silicone sealant, comprising the following two components in parts by weight:

[0006] Component A:

[0007] Vinyl silicone oil 20-50 parts, vinyl MQ resin 20-50 parts, modified hydroxyl silicone oil 5-20 parts, hydrogen-containing silicone oil 1-20 parts, silica 1-10 parts, and inhibitor 0.005-0.1 parts;

[0008] Component B:

[0009] Vinyl silicone oil 20-80 parts, modified silicone resin 20-30 parts, silica 1-10 parts, KH570 1-10 parts, methyltrimethoxysilane 1-10 parts, black color paste 0.05-0.1 parts;

[0010] The structure of the modified hydroxyl silicone oil is as shown in formula (Ⅰ):

[0011]

[0012] The modified silicone resin has the structure of formula (II):

[0013]

[0014] The low-temperature curing silicone sealant of this invention uses modified hydroxyl silicone oil, which improves the heat resistance of the sealant and promotes low-temperature bonding. The use of modified silicone resin focuses on accelerating the reaction between silicon hydrogen bonds and vinyl groups, slowing down the reaction between hydroxyl groups and silicon hydrogen bonds, avoiding the generation of hydrogen gas, and thus reducing the probability of bubble formation in the sealant.

[0015] Furthermore, the preparation reaction formula for the modified hydroxyl silicone oil is as follows:

[0016]

[0017] Furthermore, the preparation method of the modified hydroxyl silicone oil is as follows: the reactants hydroxyl silicone oil, boric acid, and triphenylsilane are added to a platinum catalyst, and stirred for 2 to 6 hours at 160 to 180°C under vacuum of -0.09 to -0.1 MPa to obtain the modified hydroxyl silicone oil;

[0018] The hydroxyl silicone oil has the molecular formula HOMe2SiOSiMe2OH and a viscosity of 300-5000 mPa·s. The mass ratio of the hydroxyl silicone oil, boric acid, and triphenylsilane is 100:(0.05-20):(0.05-20), and the amount of platinum catalyst added is 1-50 ppm.

[0019] Furthermore, the preparation reaction formula of the modified silicone resin is as follows:

[0020]

[0021] Further, the preparation method of the modified silicone resin is as follows: Tetraethyl orthosilicate is added to a reaction vessel, followed by 0.1% to 5% (by mass) of concentrated sulfuric acid, and the mixture is stirred at room temperature for 3-10 minutes; then hexamethyldisiloxane, tetramethyldivinyldisiloxane, and phenyltriethoxysilane are added, and the mixture is stirred at room temperature for another 3-10 minutes; distilled water is slowly added dropwise, with a molar mass 1 to 1.5 times that of the alkoxy group; after the addition is complete, the oil is slowly heated to 60-80°C, and the reaction is carried out for 3-5 hours to obtain the modified silicone resin; the molar mass ratio of tetraethyl orthosilicate, hexamethyldisiloxane, tetramethyldivinyldisiloxane, and phenyltriethoxysilane is 2:(0.5-2):(0.5-2):(0.5-2).

[0022] Furthermore, the vinyl silicone oil has a vinyl content of 0.025–0.25 mmol / g and a viscosity of 300–9000 mPa·s at 25°C.

[0023] Furthermore, the vinyl MQ resin has a vinyl content of 0.4–0.7 mmol / g and a viscosity of 5000–50000 mPa·s at 25°C.

[0024] Furthermore, the molecular formula of the hydrogen-containing silicone oil is (Me3SiO)2(Me2SiO). m (HMeSiO) n m = 7–30, n = 24–40, and hydrogen content is 0.24–0.91 mmol / g.

[0025] Furthermore, the silica has a specific surface area of ​​120–210 m². 2 / g of hydrophobic silica.

[0026] Further, the inhibitor is at least one selected from diethyl fumarate, dibutyl fumarate, 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, and 3-phenyl-1-butyn-3-ol.

[0027] The above-mentioned low-temperature curing silicone sealant is used as follows: Mix components A and B in a 1:1 mass ratio, then cure at 60°C for 30 minutes or at room temperature for 48 hours.

[0028] The beneficial effects of this invention are as follows:

[0029] The low-temperature curing silicone sealant provided by this invention can effectively reduce the curing temperature of addition-type silicone sealants. The use of modified hydroxyl silicone oil improves the heat resistance of the sealant and promotes low-temperature bonding. The use of modified silicone resin focuses on accelerating the reaction between silicon-hydrogen bonds and vinyl groups, slowing down the reaction between hydroxyl groups and silicon-hydrogen bonds, avoiding the generation of hydrogen gas, and thus reducing the probability of bubble formation in the sealant. Detailed Implementation

[0030] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0031] Preparation of modified hydroxyl silicone oil:

[0032] 1000g of hydroxyl silicone oil, 5g of boric acid, 5g of triphenylsilane, and 0.1g of Speier catalyst (platinum content 5000ppm) were added to a kneader. After stirring at room temperature for 5 minutes, the mixture was heated to 180℃ and stirred under vacuum of -0.091MPa for 2 hours to obtain modified hydroxyl silicone oil. The molecular formula of the hydroxyl silicone oil is (HOMe2SiO). 0.5 )2(Me2SiO) m m = 8, viscosity at 25℃ is 450 mPa·s.

[0033] Preparation of modified silicone resin:

[0034] Add 416g of tetraethyl orthosilicate and 0.83g of concentrated sulfuric acid to a three-necked flask, stir at room temperature for 5 minutes, then add 81.19g of hexamethyldisiloxane, 94g of tetramethyldivinyldisiloxane, and 120g of phenyltriethoxysilane, continue stirring at room temperature for 5 minutes, and slowly add 171g of distilled water dropwise. After the addition is complete, slowly raise the oil temperature to 70°C and react for 5 hours. As the generated alcohols are continuously distilled off, the modified resin is finally obtained.

[0035] Example 1:

[0036] A low-temperature curing silicone sealant:

[0037] Component A consists of vinyl silicone oil, vinyl MQ resin, modified hydroxyl silicone oil, hydrogen-containing silicone oil, silica, and inhibitor in a weight ratio of 23:20:10:5:10:0.05.

[0038] Component B consists of vinyl silicone oil, modified silicone resin, silica, KH570, methyltrimethoxysilane, and black color paste in a weight ratio of 30:25:10:1.5:1.5:0.05.

[0039] Among them, the vinyl silicone oil has a vinyl content of 0.09 mmol / g and a viscosity of 2000 mPa·s at 25℃; the vinyl MQ resin has a vinyl content of 0.42 mmol / g and a viscosity of 10000 mPa·s at 25℃; and the hydrogen-containing silicone oil has the molecular formula (Me3SiO)2(Me2SiO). m (HMeSiO) n The silica has m=30, n=25, hydrogen content of 8.9 mmol / g, and viscosity of 20 mPa·s at 25℃; the silica has a specific surface area of ​​140–200 m² / g. 2 / g of hydrophobic silica; the inhibitor is 3-methyl-1-butyn-3-ol.

[0040] When using, mix components A and B at a mass ratio of 1:1 and cure at 60℃ for 30 minutes. The performance of the sample is shown in Table 1.

[0041] Comparative Example 1:

[0042] An organosilicon sealant:

[0043] Component A consists of vinyl silicone oil, vinyl MQ resin, hydrogen-containing silicone oil, silica, and inhibitor in a weight ratio of 33:20:5:10:0.05.

[0044] Component B consists of vinyl silicone oil, modified silicone resin, silica, KH570, methyltrimethoxysilane, and black color paste in a weight ratio of 30:25:10:1.5:1.5:0.05.

[0045] Among them, the vinyl silicone oil has a vinyl content of 0.09 mmol / g and a viscosity of 2000 mPa·s at 25℃; the vinyl MQ resin has a vinyl content of 0.42 mmol / g and a viscosity of 10000 mPa·s at 25℃; the hydrogen-containing silicone oil has the molecular formula (Me3SiO)2(Me2SiO)m(HMeSiO)n, m=30, n=25, a hydrogen content of 8.9 mmol / g, and a viscosity of 20 mPa·s at 25℃; the silica is a hydrophobic silica with a specific surface area of ​​140-200 m2 / g; and the inhibitor is 3-methyl-1-butyn-3-ol.

[0046] When using, mix components A and B at a mass ratio of 1:1 and cure at 60℃ for 30 minutes. The performance of the sample is shown in Table 1.

[0047] Comparative Example 2:

[0048] An organosilicon sealant:

[0049] Component A consists of vinyl silicone oil, vinyl MQ resin, hydroxyl silicone oil, hydrogen-containing silicone oil, silica, and inhibitors in a weight ratio of 23:20:10; 5:10:0.05.

[0050] Component B consists of vinyl silicone oil, modified silicone resin, silica, KH570, methyltrimethoxysilane, and black color paste in a weight ratio of 30:25:10:1.5:1.5:0.05.

[0051] Among them, the vinyl silicone oil has a vinyl content of 0.09 mmol / g and a viscosity of 2000 mPa·s at 25℃; the vinyl MQ resin has a vinyl content of 0.42 mmol / g and a viscosity of 10000 mPa·s at 25℃; the hydroxyl silicone oil has the molecular formula (HOMe2SiO). 0.5 )2(Me2SiO) m The viscosity of the hydrogen-containing silicone oil is 450 mPa·s at 25℃, with m = 8. m (HMeSiO) n The silica has m=30, n=25, hydrogen content of 8.9 mmol / g, and viscosity of 20 mPa·s at 25℃; the silica has a specific surface area of ​​140–200 m² / g. 2 / g of hydrophobic silica; the inhibitor is 3-methyl-1-butyn-3-ol.

[0052] When using, mix components A and B at a mass ratio of 1:1 and cure at 60℃ for 30 minutes. The performance of the sample is shown in Table 1.

[0053] Comparative Example 3:

[0054] An organosilicon sealant:

[0055] Component A consists of vinyl silicone oil, vinyl MQ resin, hydroxyl silicone oil, hydrogen-containing silicone oil, silica, and inhibitors in a weight ratio of 23:20:10; 5:10:0.05.

[0056] Component B consists of vinyl silicone oil, vinyl MQ resin, silica, KH570, methyltrimethoxysilane, black pigment, and caster catalyst (vinyl chloroplatinate complex 5000 ppm) in a weight ratio of 30:25:10:1.5:1.5:0.05:0.136.

[0057] Among them, the vinyl silicone oil has a vinyl content of 0.09 mmol / g and a viscosity of 2000 mPa·s at 25℃; the vinyl MQ resin has a vinyl content of 0.42 mmol / g and a viscosity of 10000 mPa·s at 25℃; the hydroxyl silicone oil has the molecular formula (HOMe2SiO). 0.5 )2(Me2SiO) m The viscosity of the hydrogen-containing silicone oil is 450 mPa·s at 25℃, with m = 8. m (HMeSiO) n The silica has m=30, n=25, hydrogen content of 8.9 mmol / g, and viscosity of 20 mPa·s at 25℃; the silica has a specific surface area of ​​140–200 m² / g. 2 / g of hydrophobic silica; the inhibitor is 3-methyl-1-butyn-3-ol.

[0058] When using, mix components A and B at a mass ratio of 1:1 and cure at 60℃ for 30 minutes. The performance of the sample is shown in Table 1.

[0059] Table 1: Performance Test Results

[0060] Adhesion at material interfaces OK NG OK OK Are there air bubbles? none none none have Thermal decomposition temperature 313 297 298 298

[0061] The experimental results show that, compared with Comparative Example 1, the introduction of modified hydroxyl silicone oil lowered the curing and bonding temperature of addition-type silicone; compared with Comparative Examples 1-3, the introduction of modified hydroxyl silicone oil increased the thermal decomposition temperature of the colloid; compared with Comparative Example 3, the introduction of modified silicone resin reduced the generation of bubbles.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature curing silicone sealant, characterized in that, The two components comprise the following parts by weight: Component A: Vinyl silicone oil 20-50 parts, vinyl MQ resin 20-50 parts, modified hydroxyl silicone oil 5-20 parts, hydrogen-containing silicone oil 1-20 parts, silica 1-10 parts, inhibitor 0.005-0.1 parts; Component B: Vinyl silicone oil 20-80 parts, modified silicone resin 20-30 parts, silica 1-10 parts, KH570 1-10 parts, methyltrimethoxysilane 1-10 parts, black color paste 0.05-0.1 parts; The modified hydroxyl silicone oil is prepared by adding the reactants hydroxyl silicone oil, boric acid, and triphenylsilane to a platinum catalyst and stirring for 2 to 6 hours at 160–180°C under a vacuum of -0.09 to -0.1 MPa to obtain the modified hydroxyl silicone oil. The molecular formula of the hydroxyl silicone oil is (HOMe2SiO) 0.5 )2(Me2SiO) m The viscosity at 25°C is 450 mPa·s, m=8, and the mass ratio of the hydroxyl silicone oil, boric acid, and triphenylsilane is 100:(0.05~20):(0.05~20). The amount of platinum catalyst added is 1~50 ppm. The modified silicone resin is prepared as follows: Tetraethyl orthosilicate is added to a reaction vessel, followed by 0.1%–5% (by mass) of concentrated sulfuric acid. The mixture is stirred at room temperature for 3–10 minutes. Hexamethyldisiloxane, tetramethyldivinyldisiloxane, and phenyltriethoxysilane are then added, and the mixture is stirred at room temperature for another 3–10 minutes. Distilled water is slowly added dropwise, with a molar mass 1–1.5 times that of the alkoxy group. After the addition is complete, the oil is slowly heated to 60–80°C, and the reaction is carried out for 3–5 hours to obtain the modified silicone resin. The molar mass ratio of tetraethyl orthosilicate, hexamethyldisiloxane, tetramethyldivinyldisiloxane, and phenyltriethoxysilane is 2:(0.5–2):(0.5–2):(0.5–2).

2. The low-temperature curing silicone sealant according to claim 1, characterized in that, The vinyl silicone oil has a vinyl content of 0.025–0.25 mmol / g and a viscosity of 300–9000 mPa·s at 25°C.

3. The low-temperature curing silicone sealant according to claim 1, characterized in that, The vinyl MQ resin has a vinyl content of 0.4–0.7 mmol / g and a viscosity of 5000–50000 mPa·s at 25°C.

4. The low-temperature curing silicone sealant according to claim 1, characterized in that, The molecular formula of the hydrogen-containing silicone oil is (Me3SiO)2(Me2SiO). m (HMeSiO) n m=7~30, n=24~40, hydrogen content is 0.24~0.91mmol / g.

5. The low-temperature curing silicone sealant according to claim 1, characterized in that, The silica mentioned is a silica with a specific surface area of ​​120-210 m². 2 / g of hydrophobic silica.

6. The low-temperature curing silicone sealant according to claim 1, characterized in that, The inhibitor is at least one of diethyl fumarate, dibutyl fumarate, 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, and 3-phenyl-1-butyn-3-ol.

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