Preparation method of redispersible waterborne polyurethane powder
A water-based polyurethane and redispersion technology, applied in polyurea/polyurethane adhesives, adhesive types, adhesives, etc., can solve the problems of easy hydrolysis of polyurethane resins, achieve extended storage life, good flexibility, and improve adhesion The effect of intensity
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[0014] The invention provides a kind of preparation method of redispersible waterborne polyurethane powder, comprises the following steps:
[0015] Step 1, preparation of the soft core layer: after mixing 1-2 parts by weight of glycol, 64-90 parts by weight of polyether polyol, and 0-16 parts by weight of polyester polyol, add 8-12 parts by weight of Polyisocyanate, after the reaction, the isocyanate prepolymer of the soft core layer is obtained;
[0016] Step 2, after mixing the 1-methylimidazole of 82 parts by weight and the paraformaldehyde of 55-78 parts by weight, heat and react, add the solvent of 500 parts by weight after cooling, remove unreacted solid paraformaldehyde by filtration, then reduce Pressure distillation removes solvent, obtains 2-hydroxymethyl-1-methylimidazole;
[0017] After heating 2-hydroxymethyl-1-methylimidazole, feed 176-308 parts by weight of ethylene oxide, cool down after the reaction, and obtain the first viscous liquid;
[0018] Step 3, take...
Embodiment 1
[0038] A preparation method of redispersible water-based polyurethane powder, specifically comprising the following steps:
[0039] Step 1. After mixing 10g of ethylene glycol and 900g of polytetrahydrofuran glycol PTMEG-3000, add 80g of hexamethylene diisocyanate HDI, heat up to 76°C and react for 5 hours to obtain the isocyanate prepolymer of the soft core layer;
[0040] Step 2. Mix 82g of 1-methylimidazole and 78g of paraformaldehyde and heat to 140°C for reaction. After 6 hours of reaction, cool down, add 500g of acetone, filter to remove unreacted solid paraformaldehyde, and depressurize the clear liquid Solvent acetone was distilled off to obtain white solid 2-hydroxymethyl-1-methylimidazole;
[0041] After heating 2-hydroxymethyl-1-methylimidazole to 120°C, pour 176g of ethylene oxide into it, react for 0.5h and then cool down to 35°C to obtain the first colorless and transparent viscous liquid;
[0042] Step 3. Take 288g of the first viscous liquid obtained in step 2...
Embodiment 2
[0046] A preparation method of redispersible water-based polyurethane powder, specifically comprising the following steps:
[0047] Step 1. After mixing 5g of 1,6-hexanediol, 320g of PEG-2000 and 90g of PEA-2000, add 120g of HMDI, heat up to 82°C and react for 2 hours to obtain the isocyanate prepolymer of the soft core layer;
[0048] Step 2. Mix 82g of 1-methylimidazole and 70g of paraformaldehyde and heat to 160°C for reaction. After 3 hours of reaction, cool down, add 500g of acetone, filter to remove unreacted solid paraformaldehyde, and then reduce the clear liquid to Pressure distillation removes solvent acetone, obtains white solid 2-hydroxymethyl-1-methylimidazole;
[0049] After heating 2-hydroxymethyl-1-methylimidazole to 140°C, add 308g of ethylene oxide, react for 3 hours and then cool down to 40°C to obtain the first colorless and transparent viscous liquid;
[0050] Step 3. Take 420g of the first viscous liquid obtained in step 2, add 143g of thionyl chloride d...
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