Disclosed is a compound having a chemical structure (X.sub.f.sup.− is a counter anion selected from the group consisting of Cl.sup.−, NO.sub.3.sup.−, Br.sup.−, I.sup.−, CH.sub.3SO.sub.3.sup.− and OH.sup.−) of the following general formula (I). By using this compound as a polymerization initiator, the amount of the aggregation formed in emulsion polymerization can be reduced.

##STR00001##

An acrylic rubber including: a polymer composition of: 70 to 99.9% by weight of a bonding unit derived from at least one (meth) acrylic acid ester selected from (meth) acrylic acid alkyl ester and (meth) acrylic acid alkoxyalkyl ester; 0.1 to 10% by weight of a bonding unit derived from a monomer containing a reactive group; and 0 to 20% by weight of a bonding unit derived from other monomer, wherein ash content is 0.15% by weight or less, total amount of sodium and sulfur in the ash is 60% by weight or more, a ratio of sodium to sulfur by weight ratio is in the range of 0.5 to 2.5, ratio of Z-average molecular weight to weight average molecular weight is 1.3 or more, and weight average molecular weight is in the range of 1,000,000 to 5,000,000.

Methods for forming latexes are provided. In embodiments, such a method comprises adding a first portion of a monomer emulsion comprising water, a monomer, an acidic monomer, a multifunctional monomer, and a first reactive surfactant to a reactive surfactant solution comprising water and a second reactive surfactant to form a reaction mixture, wherein the reactive surfactant solution does not comprise monomers other than the second reactive surfactant; adding a first portion of an initiator solution to the reaction mixture so that monomers undergo polymerization reactions to form resin seeds in the reaction mixture; adding a second portion of the monomer emulsion to the reaction mixture comprising the resin seeds; and adding a second portion of the initiator solution to the reaction mixture to form a latex comprising resin particles.

Methods for forming latexes are provided. In embodiments, such a method comprises adding a first portion of a monomer emulsion comprising water, a monomer, an acidic monomer, a multifunctional monomer, and a first reactive surfactant to a reactive surfactant solution comprising water and a second reactive surfactant to form a reaction mixture, wherein the reactive surfactant solution does not comprise monomers other than the second reactive surfactant; adding a first portion of an initiator solution to the reaction mixture so that monomers undergo polymerization reactions to form resin seeds in the reaction mixture; adding a second portion of the monomer emulsion to the reaction mixture comprising the resin seeds; and adding a second portion of the initiator solution to the reaction mixture to form a latex comprising resin particles.

Provided is a surfactant composition that can impart good polymerization stability, that can yield an aqueous resin dispersion having good wettability, and that can improve water resistance and water-resistant adhesive strength of a resin film formed from the aqueous resin dispersion. The surfactant composition according to the present invention includes a compound C1 represented by formula (1):

##STR00001##

(in formula (1), A.sup.1 represents an alkylene group having 10 to 14 carbon atoms, A.sup.2 represents an alkylene group having 2 to 4 carbon atoms, n is an average number of moles of an oxyalkylene group A.sup.2O added and is a number of 1 to 100, and X represents a hydrogen atom, a sulfate ester or a salt thereof, a phosphate ester or a salt thereof, or methylcarboxylic acid or a salt thereof); and a compound C2 represented by formula (2):

##STR00002##

(in formula (2), A.sup.1, A.sup.2, n, and X are as defined in formula (1)). A molar ratio C1/C2 of the compound C1 to the compound C2 is 99/1 to 84/16.

Provided is a surfactant composition that can impart good polymerization stability, that can yield an aqueous resin dispersion having good wettability, and that can improve water resistance and water-resistant adhesive strength of a resin film formed from the aqueous resin dispersion. The surfactant composition according to the present invention includes a compound C1 represented by formula (1):

##STR00001##

(in formula (1), A.sup.1 represents an alkylene group having 10 to 14 carbon atoms, A.sup.2 represents an alkylene group having 2 to 4 carbon atoms, n is an average number of moles of an oxyalkylene group A.sup.2O added and is a number of 1 to 100, and X represents a hydrogen atom, a sulfate ester or a salt thereof, a phosphate ester or a salt thereof, or methylcarboxylic acid or a salt thereof); and a compound C2 represented by formula (2):

##STR00002##

(in formula (2), A.sup.1, A.sup.2, n, and X are as defined in formula (1)). A molar ratio C1/C2 of the compound C1 to the compound C2 is 99/1 to 84/16.

Aqueous polymer dispersions are produced by radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of protective colloids and/or emulsifiers in a continuously operated tubular reactor, characterized in that the direction of flow of the reactor contents is reversed along the longitudinal axis of the reactor over the course of polymerization.

Aqueous polymer dispersions are produced by radically initiated emulsion polymerization of ethylenically unsaturated monomers in the presence of protective colloids and/or emulsifiers in a continuously operated tubular reactor, characterized in that the direction of flow of the reactor contents is reversed along the longitudinal axis of the reactor over the course of polymerization.

Provided is a method for preparing a latex composition for dip forming, the method including: (a) preparing a monomer mixture including a conjugated diene-based monomer, an ethylenically unsaturated nitrile monomer and an ethylenically unsaturated acid monomer; (b) introducing starch, an emulsifier and an inorganic solvent into the monomer mixture; and (c) preparing a copolymer latex by introducing a polymerization initiator, wherein the copolymer includes the starch in a main chain thereof.

Provided is a method for preparing a latex composition for dip forming, the method including: (a) preparing a monomer mixture including a conjugated diene-based monomer, an ethylenically unsaturated nitrile monomer and an ethylenically unsaturated acid monomer; (b) introducing starch, an emulsifier and an inorganic solvent into the monomer mixture; and (c) preparing a copolymer latex by introducing a polymerization initiator, wherein the copolymer includes the starch in a main chain thereof.