This invention relates to a binder for an anode of a secondary battery, an anode of a secondary battery, and a secondary battery. Specifically, this invention provides a binder for an anode of a secondary battery that can not only improve anode adhesion, but also minimize resistance in a secondary battery, and ultimately, improve the life of a secondary battery.

This invention relates to a binder for an anode of a secondary battery, an anode of a secondary battery, and a secondary battery. Specifically, this invention provides a binder for an anode of a secondary battery that can not only improve anode adhesion, but also minimize resistance in a secondary battery, and ultimately, improve the life of a secondary battery.

A latex of an acid-modified conjugated diene polymer including the acid-modified conjugated diene polymer obtained by modifying a conjugated diene polymer with an acid group-containing compound, in which a content of a structural unit derived from the acid group-containing compound is 0.2 to 0.7 parts by weight with respect to 100 parts by weight of the acid-modified conjugated diene polymer; a content of a water-soluble polymer in the latex is 2 parts by weight or less with respect to 100 parts by weight of the acid-modified conjugated diene polymer; when a solids content of the latex is adjusted to 60 wt %, a viscosity at 25° C. is 800 mPa.Math.s or less; and when the solids content of the latex is adjusted to 50 wt %, the viscosity at 25° C. is 300 mPa.Math.s or less.

Provided is a (meth)acrylic ester copolymer (B) having a reactive silicon group represented by the following formula (1): —SiR.sup.5.sub.cX.sub.3-c (1). R.sup.5 is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is a hydroxy group or a hydrolyzable group, and c is 0 or 1. A monomer component of the copolymer includes a (meth)acrylic ester (b1), a (meth)acrylic ester polymer (b2) having more than one (meth)acryloyl groups per molecule, and a chain transfer agent (b3) having a mercapto group. The monomer component further includes a monomer (b4) having a reactive silicon group and a polymerizable unsaturated group, and/or the chain transfer agent (b3) having a mercapto group further has a reactive silicon group.

Provided is a (meth)acrylic ester copolymer (B) having a reactive silicon group represented by the following formula (1): —SiR.sup.5.sub.cX.sub.3-c (1). R.sup.5 is a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, X is a hydroxy group or a hydrolyzable group, and c is 0 or 1. A monomer component of the copolymer includes a (meth)acrylic ester (b1), a (meth)acrylic ester polymer (b2) having more than one (meth)acryloyl groups per molecule, and a chain transfer agent (b3) having a mercapto group. The monomer component further includes a monomer (b4) having a reactive silicon group and a polymerizable unsaturated group, and/or the chain transfer agent (b3) having a mercapto group further has a reactive silicon group.

First embodiment of a (meth)acrylic copolymer in the present invention includes following: a (meth)acrylic copolymer having at least one kind of constitutional unit selected from the group consisting of a constitutional unit (A1) having at least one kind of structure (I) selected from the group consisting of structures represented by the following formula (1), formula (2), or formula (3) and a constitutional unit (A2) having a triorganosilyloxycarbonyl group and a constitutional unit (B) derived from a macromonomer (b): ##STR00001## (where, X represents —O—, —S—, or —NR.sup.14—, R.sup.14 represents a hydrogen atom or an alkyl group, R.sup.1 and R.sup.2 each represent a hydrogen atom or an alkyl group having from 1 to 10 carbon atoms, R.sup.3 and R.sup.5 each represent an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group, or an aryl group, and R.sup.4 and R.sup.6 each represent an alkylene group having from 1 to 10 carbon atoms).

First embodiment of a (meth)acrylic copolymer in the present invention includes following: a (meth)acrylic copolymer having at least one kind of constitutional unit selected from the group consisting of a constitutional unit (A1) having at least one kind of structure (I) selected from the group consisting of structures represented by the following formula (1), formula (2), or formula (3) and a constitutional unit (A2) having a triorganosilyloxycarbonyl group and a constitutional unit (B) derived from a macromonomer (b): ##STR00001## (where, X represents —O—, —S—, or —NR.sup.14—, R.sup.14 represents a hydrogen atom or an alkyl group, R.sup.1 and R.sup.2 each represent a hydrogen atom or an alkyl group having from 1 to 10 carbon atoms, R.sup.3 and R.sup.5 each represent an alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group, or an aryl group, and R.sup.4 and R.sup.6 each represent an alkylene group having from 1 to 10 carbon atoms).

A monomer composition containing an unsaturated polyalkylene glycol ether-based monomer is provided having excellent stability. The monomer composition contains an unsaturated polyalkylene glycol ether-based monomer represented by the following chemical formula (1):
YO(R.sup.1O).sub.nR.sup.2  (1)
[in the formula, Y represents an alkenyl group having 2 to 7 carbon atoms; R.sup.1O represents one or two or more types of oxyalkylene groups having 2 to 18 carbon atoms; n represents an average addition mole number of oxyalkylene groups and is a number of 5 to 500; and R.sup.2 represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms], an organic acid, and water, and having a pH of 4 to 13.

A monomer composition containing an unsaturated polyalkylene glycol ether-based monomer is provided having excellent stability. The monomer composition contains an unsaturated polyalkylene glycol ether-based monomer represented by the following chemical formula (1):
YO(R.sup.1O).sub.nR.sup.2  (1)
[in the formula, Y represents an alkenyl group having 2 to 7 carbon atoms; R.sup.1O represents one or two or more types of oxyalkylene groups having 2 to 18 carbon atoms; n represents an average addition mole number of oxyalkylene groups and is a number of 5 to 500; and R.sup.2 represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms], an organic acid, and water, and having a pH of 4 to 13.

Methods for forming latexes are provided. In an embodiment, such a method comprises adding a monomer emulsion comprising water, a monomer, an acidic monomer, a hydrophilic monomer, a difunctional monomer, a first reactive surfactant, and a chain transfer agent, to a reactive surfactant solution comprising water, a second reactive surfactant, and an initiator, at a feed rate over a period of time so that monomers of the monomer emulsion undergo polymerization reactions to form resin particles in a latex. The reactive surfactant solution does not comprise monomers other than the second reactive surfactant, the reactive surfactant solution does not comprise a resin seed, and the monomer emulsion does not comprise the resin seed. The latex is characterized by a viscosity in a range of from about 10 cP to about 100 cP as measured at a solid content of about 30% and at room temperature. The latexes are also provided.