Prepolymers Exhibiting Rapid Formation Physical Properties
A technology of prepolymers and polysulfides, applied in other chemical processes, organic chemistry, chemical instruments and methods, etc., can solve problems such as damage to the performance of sealants
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Embodiment 1
[0564] Synthesis of Bis(alkenyl) Ethers Containing Hydroxyl
[0565] Sodium hydroxide (108.06 g, 2.70 mol) was added to the flask containing deionized water (360 mL). 1,8-Dimercapto-3,6-dioxaoctane (DMDO) (224.36 g, 1.23 mol) was added to the solution and the resulting mixture was stirred at 60°C for 1-2 hours. Allyl glycidyl ether (280.33 g, 2.46 mol) was added. The mixture was stirred for 2-3 hours. After cooling to room temperature, the mixture was poured into a separatory funnel. The top layer was collected and diluted with ethyl acetate. The solution was dried over anhydrous sodium sulfate, then concentrated under reduced pressure to yield 500 g of 4,11,14,21-tetraoxa-8,17-dithiatetracoca-1,23-diene -6,19-diol which is a bright yellow oil.
Embodiment 2
[0567] Synthesis of Bis(alkenyl)ether Polysulfide Prepolymer Containing Hydroxyl
[0568] 1,8-Dimercapto-3,6-dioxaoctane (DMDO) (167.47 g, 1.83 mol) and triallyl cyanurate (TAC) (4.75 g, 0.057 mol) were added to the flask and Heat to 60°C. The hydroxyl-containing bis(alkenyl) ether (52.13g, 0.25mol; 50% by weight vs DEG-DVE) of Example 1, diethylene glycol divinyl ether (DEG-DVE) (104.25g, 1.32mol) and (0.16 g) was added dropwise to the flask. After the catalyst addition, the temperature was raised to 70 °C and the mixture was stirred for several hours until the mercaptan equivalent weight stopped increasing and no vinyl or allyl peaks were observed in the Fourier transform infrared spectrum (vinyl: ~1618 cm -1 , 1638cm -1 ; Allyl: ~1644cm -1 ). The mixture was then stirred at 95°C for 2 hours and then evacuated at a pressure of less than 10 Torr at a temperature of 85°C to 90°C. The thiol equivalent weight of 300 g of the polythioether prepolymer formed was 1511.
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Embodiment 3
[0571] Hardness of the sealant during curing
[0572] The polythioether prepolymer (70.59g, 0.047mol) of Example 2 and the accelerator composition S-5304 (19.00g, 0.049mol) (see Table 1) were used in a mixer (Hauschild high-speed mixer, 2300rpm, 30s ) for mixing. DABCO33-LV (0.71 g; obtained from Air Products & Chemicals, Allentown, PA, USA) was added to the mixture and mixed well with a mixer. The mixture was poured into curing trays in a controlled temperature and humidity chamber (25°C, 50RH%). Hardness increase during curing was monitored using a Type A durometer according to ASTM D2240. figure 1 The Shore A hardness of the sealant after mixing is shown as a function of time.
[0573] Table 1. Accelerator compositions.
[0574]
[0575] *Adhesion promoters, such as T-1601, available from PRC-DeSoto International, Inc.
[0576] The above ingredients were mixed thoroughly and the mixture was kept at room temperature for 24 hours before being mixed with the prepolymer...
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