A kind of silicone sealant for electronic products and preparation method thereof
A technology of electronic products and sealants, applied in the field of sealants, can solve problems such as easy oil leakage, aging, easy cracking, unstable adhesives, etc., and achieve the effects of good storage stability, convenient use, and good room temperature vulcanization
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[0041] To further illustrate, the preparation method of the polyalkoxy-terminated polydimethylsiloxane comprises the following steps:
[0042] Step 1. Mix α,ω-dihydroxypolydimethylsiloxane and end-capping agent evenly at 20-30°C, then add basic catalyst, mix, and carry out end-capping reaction;
[0043] After Step 2 and Step 1 are completed, acid is added for neutralization, and polydimethylsiloxane is polyalkoxy terminated.
[0044] To further illustrate, in the first step: the capping reaction is carried out in a reactor at a temperature of 20-30°C, the vacuum degree in the reactor is ≤ -0.08MPa, the stirring speed is 500-1000rpm, and the α, ω- After stirring and mixing dihydroxy polydimethylsiloxane and end-capping agent for 5-15 minutes, add the basic catalyst and stir for 20-40 minutes;
[0045] In the second step: add an acid, control the pH to 6-8, and stir at the same temperature for 40-70 minutes to obtain the polydimethylsiloxane terminated by polyalkoxy groups.
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Embodiment A
[0058] Add polydimethylsiloxane, polyethylene glycol and crosslinking agent to the planetary mixer, vacuumize and stir for 20min, rotate at 1000rpm, add BET with a specific surface area of 150m 2 / g filler, vacuumize and stir at high speed for 20 minutes at a speed of 1200rpm, then add tackifier and tin catalyst in turn, and stir at 1000rpm for 30min under vacuum to obtain the product. The ratio of the above components is shown in Table 1.
[0059] The polydimethylsiloxane is α,ω-dihydroxypolydimethylsiloxane; the filler is hydrophilic fumed silica; the tackifier is γ-aminopropyltriethoxysilane and N-β- A combination of (aminoethyl)-γ-aminopropyltrimethoxysilane; the tin catalyst is dibutyltin dilaurate; the crosslinking agent is methyltrimethoxysilane; the molecular weight range of polyethylene glycol is 300-400;
[0060] Among them, the preparation of polyalkoxy-terminated polydimethylsiloxane: 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 8000mPa·s, ...
Embodiment B
[0072] Add 100 parts of polyalkoxy-terminated polydimethylsiloxane, 10 parts of polyethylene glycol and 6 parts of cross-linking agent to a planetary mixer, vacuumize and stir for 20 minutes at a speed of 1000 rpm, and add 10 parts of BET ratio Surface area 150m 2 / g filler, vacuumize and stir at high speed for 20 minutes at a speed of 1200rpm, then add 2 parts of tackifier and 0.2 parts of tin catalyst in turn, and stir at 1000rpm for 30 minutes under vacuum to obtain the product.
[0073] The filler is hydrophilic fumed silica; the tackifier is a combination of γ-aminopropyltriethoxysilane and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; the tin catalyst is di Dibutyltin laurate; Cross-linking agent is methyltrimethoxysilane; The molecular weight range of polyethylene glycol is as described in table 3;
[0074] Among them, the preparation of polyalkoxy-terminated polydimethylsiloxane: put 100 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 8000mPa·s and 4 ...
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