Preparation of amphoteric water-in-oil self-inverting polymer emulsion

A method of preparing an amphoteric water-in-oil self-inverting polymer emulsion comprising

• (A) forming a water-in-oil emulsion of
• (1) from about 10 to about 50 parts by weight of a monomer mixture selected from the group consisting of
• (a) from about 30 to about 99 parts by weight of a water soluble nonionic vinyl monomer and from about 1 to about 70 parts by weight of a water soluble amphoteric vinyl monomer to form an amphoteric copolymer, and
• (b) from about 30 to 98 parts by weight of a water soluble nonionic vinyl monomer, from about 1 to about 35 parts by weight of a water soluble anionic vinyl monomer and from about 1 to about 35 parts by weight of a water soluble cationic vinyl monomer to form an amphoteric terpolymer,
• (2) from about 10 to about 50 parts by weight of water,
• (3) from about 5 to about 50 parts by weight of a hydrophobic liquid,
• (4) from about 2 to about 25 parts by weight of a water-in-oil emulsifying agent, and
• (5) an effective amount of a free radical yielding initiator to polymerize the monomer mixture,
• (B) polymerizing the monomer mixture under free radical polymerizing conditions to form a water-in-oil emulsion which contains finely dispersed particles of the amphoteric polymer, and
• (C) adding to the water in oil emulsion from about 1 to about 15 parts by weight of an inverting surfactant.