Method for preparing large-size diene-based rubber latex and acrylonitrile-butadiene-styrene graft copolymer comprising the same

A method for preparing a diene-based rubber latex comprising:

• preparing a first solution by adding 50 to 75 parts by weight of a conjugated diene-based monomer, 1 part by weight to 3 parts by weight of an emulsifier, 0.1 parts by weight to 0.4 parts by weight of a polymerization initiator, 0.1 parts by weight to 3 parts by weight of an electrolyte, 0.1 parts by weight to 0.5 parts by weight of a molecular weight control agent and 65 parts by weight to 100 parts by weight of ion exchanged water, based on 100 parts by weight of the conjugated diene-based monomer, into a reactor while stirring, adding 0.05 part by weight to 0.3 part by weight of a cross-linking agent based on 100 parts by weight of the conjugated diene-based monomer, and then subjecting the first solution to a first polymerization (Step 1);
• performing a second polymerization by further adding a balance of the conjugated diene-based monomer, 0 to 0.1 parts by weight of the emulsifier and 0 to 0.2 parts by weight of the cross-linking agent (Step 2);
• and
• terminating the second polymerization when the polymerization conversion rate of the second polymerization is 90% or higher (Step 3), wherein the cross-linking agent is (propylene glycol)n diacrylate, in which n is 7 to 13.