| 摘要 |
PURPOSE: A core/shell emulsion polymer for a nonwoven binder and its preparation method are provided, to improve the sheer stress of a film, to allow a glass transition temperature to be controlled easily compared with a copolymer having the same composition, and to enhance tensile strength by reducing the amount of an emulsifier used in the polymerization of a core/shell polymer. CONSTITUTION: The method comprises the steps of (a) adding 0.007-0.015 wt% of an emulsifier to a core monomer comprising methyl methacrylate to prepare a pre-emulsion, (b) adding 0.5-1.0 wt% of an initiator to prepare an initiator solution, (c) injecting an ion exchange water to additional reactor to remove dissolved oxygen, (d) injecting 50 wt% of the pre-emulsion of (a) to the reactor of (c), adding 50 wt% of the initiator solution of (b) at 85 deg.C and maintaining it for 40 min to produce seed, and (e) adding the remaining pre-emulsion and the remaining initiator solution to proceed polymerization and maturing it at the same temperature for 60 min to polymerize a core, wherein the ratio of the core monomer and the ion exchange water is 3-10 : 90-97 by weight; diluting the obtained core polymer with an ion exchange water and increasing the temperature to 85 deg.C, and injecting a shell monomer comprising styrene and an initiator aqueous solution lasting 5 hours to polymerize them, wherein the ratio of the core solution, the shell monomer and the ion exchange water is 30-55 : 15-25 : 30-55 by weight, and the content of an initiator is 0.8-1.2 wt% of the content of the shell monomer; and maturing the obtained core/shell polymer for 1 hour after polymerization to remove remaining monomers, and filtering it.
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