The present invention provides a binder for a secondary battery that can reduce the initial resistance value of the secondary battery. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001## in formula (1), R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is less than 2 mol %.

The present invention provides a binder for a secondary battery that can reduce the initial resistance value of the secondary battery. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001## in formula (1), R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is less than 2 mol %.

A vinyl alcohol copolymer, wherein the vinyl alcohol copolymer includes a vinyl alcohol unit and a constituent unit derived from an unsaturated monomer (A), the unsaturated monomer (A) is at least one selected from the group consisting of an unsaturated carboxylic acid, a salt thereof, an anhydride thereof, and an alkyl ester thereof, a content of the constituent unit derived from the unsaturated monomer (A) with respect to total constituent units of the vinyl alcohol copolymer is 1.00 mol % or more and 5.00 mol % or less, and 70 mol % or more of the constituent unit derived from the unsaturated monomer (A) forms a lactone ring structure.

The present invention provides a binder for a secondary battery having excellent binding force. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001##

in formula (1). R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and

when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is 2 mol % or more and 20 mol % or less.

The present invention provides a binder for a secondary battery having excellent binding force. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):

##STR00001##

in formula (1). R.sup.1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R.sup.2 is a hydrogen atom or a methyl group; and

when a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is 2 mol % or more and 20 mol % or less.

A methacrylic resin having a cyclic structure in a main chain thereof, a shaped article, and an optical component or automotive part, in which the glass transition temperature is higher than 120° C. and 160° C. or lower, and the sign of the orientational birefringence when being oriented so as to have a degree of orientation of 0.03 is different from the sign of the orientational birefringence when being oriented so as to have a degree of orientation of 0.08.

A methacrylic resin having a cyclic structure in a main chain thereof, a shaped article, and an optical component or automotive part, in which the glass transition temperature is higher than 120° C. and 160° C. or lower, and the sign of the orientational birefringence when being oriented so as to have a degree of orientation of 0.03 is different from the sign of the orientational birefringence when being oriented so as to have a degree of orientation of 0.08.

A polymer includes: structural units A derived from at least one selected from the group consisting of ethylene and propylene; structural units B represented by a formula (1) below; and structural units C represented by a formula (2) below. In the formula (1), L.sup.16 represents —(CH.sub.2).sub.n—(R.sup.f2O).sub.p—R.sup.f1, R.sup.f1 represents a C.sub.1-15 alkyl group having one or more hydrogen atoms thereof substituted with one or more fluorine atoms, R.sup.f2 represents a C.sub.1-15 alkylene group having one or more hydrogen atoms thereof substituted with one or more fluorine atoms, p represents an integer of 0 to 15, and n represents an integer of 0 to 10. In the formula (2), L.sup.26 represents —(CH.sub.2).sub.n— (R.sup.r2O).sub.q—R.sup.r1, R.sup.r1 represents a hydrogen atom or a C.sub.1-15 alkyl group, R.sup.r2 represents a C.sub.1-15 alkylene group, q represents an integer of 0 to 1000000, and n represents an integer of 0 to 10.

##STR00001##

A polymer includes: structural units A derived from at least one selected from the group consisting of ethylene and propylene; structural units B represented by a formula (1) below; and structural units C represented by a formula (2) below. In the formula (1), L.sup.16 represents —(CH.sub.2).sub.n—(R.sup.f2O).sub.p—R.sup.f1, R.sup.f1 represents a C.sub.1-15 alkyl group having one or more hydrogen atoms thereof substituted with one or more fluorine atoms, R.sup.f2 represents a C.sub.1-15 alkylene group having one or more hydrogen atoms thereof substituted with one or more fluorine atoms, p represents an integer of 0 to 15, and n represents an integer of 0 to 10. In the formula (2), L.sup.26 represents —(CH.sub.2).sub.n— (R.sup.r2O).sub.q—R.sup.r1, R.sup.r1 represents a hydrogen atom or a C.sub.1-15 alkyl group, R.sup.r2 represents a C.sub.1-15 alkylene group, q represents an integer of 0 to 1000000, and n represents an integer of 0 to 10.

##STR00001##

A modified PVA that enables formation of a film superior in cold water solubility, mechanical strength, and chemical resistance is provided. The modified PVA comprises a monomer unit represented by formula (I), and a structural unit represented by formula (II):

##STR00001##

wherein: a content of the monomer unit (I) is from 0.05 mol % to 10 mol %, and a content of the structural unit (II) is from 0.001 mol % to 0.5 mol % with respect to the total monomer units in the modified PVA; a viscosity average degree of polymerization is from 300 to 3,000; and a degree of saponification is from 82 mol % to 99.5 mol %. In the formula (I): R.sup.1 represents a hydrogen atom, or a methyl group; and R.sup.2 represents —R.sup.3—SO.sub.3.sup.−X.sup.+, —R.sup.3—N.sup.+(R.sup.4).sub.3Cl.sup.−, or a hydrogen atom, R.sup.3 representing an alkanediyl group, X.sup.+ representing a hydrogen atom, a metal atom, or an ammonium group, and R.sup.4 representing an alkyl group.