A kind of preparation method of polypropylene water-based polyurethane heat-sealing adhesive
A technology of water-based polyurethane and heat-sealing adhesives, which is applied in the preparation of hot-melt adhesives for pharmaceutical blister packaging and in the food field. It can solve the problems of less water-based adhesives, fewer types, and inability to heat-seal polypropylene materials, etc., and achieve low viscosity and good adhesion. Good strength and coating effect
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[0020] A preparation method of water-based polyurethane heat sealant for polypropylene includes the following steps:
[0021] A. Use polyester diol, polyether diol, hydrophilic chain extender, small molecule diol, small molecule polyol and diisocyanate to react to generate -NCO end group prepolymer;
[0022] B. Neutralize -NCO end group prepolymer with organic amine to obtain -NCO end group ionomer;
[0023] C. Emulsify the above -NCO end ionomer with tap water to obtain an aqueous polyurethane emulsion;
[0024] D. Chain extension after adding ethylenediamine to obtain polypropylene water-based polyurethane heat sealant.
[0025] In this preparation method, the composition ratios of various raw materials are as follows: the molar ratio of polyester diol to polyether diol is 1:2-4; the -NCO group in the diisocyanate and polyester and polyether diol The molar ratio of -OH groups is 3-4:1; the mass fraction of the hydrophilic chain extender in the total prepolymer is 3-6%; the mass fract...
Embodiment 1
[0029] In a reactor equipped with a stirrer, a thermometer, and a reflux condenser, 10g of polyhexanediol adipate, 30g of polyoxypropylene glycol, 19g of isophorone diisocyanate, and 3.4g of dimethylolpropionic acid were added. Add 0.2g of trimethylolpropane, add 1.6g of 1,4-butanediol, increase the temperature to 80°C, react for 4 hours, reduce the temperature to 50°C, add 2.04g of triethylamine to neutralize the prepolymer into an ionomer, Then, 137 g of deionized water was added under high-speed shearing for emulsification, and 0.94 g of ethylenediamine was added to extend the chain to obtain a clear and transparent aqueous polyurethane dispersion with blue light.
[0030] The obtained polypropylene water-based polyurethane heat-sealing adhesive was coated on 0.02um hard aluminum foil and dried, and then heat-sealed with the polypropylene sheet on a heat-sealing instrument (heat-sealing conditions 0.2MPa, 170°C, 1s), and measured the heat The sealing strength reaches 7.5N / 15mm...
Embodiment 2
[0032] In a reactor equipped with a stirrer, a thermometer, and a reflux condenser, add 20 g of polyhexanediol adipate, 20 g of polytetrahydrofuran glycol, 18.5 g of isophorone diisocyanate, and 3.2 g of dimethylol propionic acid. Add 0.15g of trimethylolpropane, add 1.66g of 1,4-butanediol, increase the temperature to 80°C, react for 4 hours, reduce the temperature to 50°C, add 1.93g of triethylamine to neutralize the prepolymer into an ionomer, Then, 130 g of deionized water was added for emulsification under high-speed shearing, and 0.87 g of ethylenediamine was added to extend the chain to obtain a clear and transparent aqueous polyurethane dispersion with blue light.
[0033] The obtained polypropylene water-based polyurethane heat-sealing adhesive was coated on 0.02um hard aluminum foil and dried, and then heat-sealed with the polypropylene sheet on a heat-sealing instrument (heat-sealing conditions 0.2MPa, 170°C, 1s), and measured the heat The sealing strength reaches 8N / 1...
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