An object of the present disclosure is to provide, for example, a fluoropolymer electret material with hardness. The present disclosure relates to an electret material comprising a fluoropolymer, wherein the fluoropolymer comprises, as a main component, a monomer unit represented by formula (1):

##STR00001##

wherein R.sup.1 to R.sup.4 are each independently a fluorine atom, a fluoroalkyl group, or a fluoroalkoxy group; and the fluoropolymer has a mass average molecular weight of 1 million or more and 5 million or less, or 5000 or more and less than 20000.

An object of the present disclosure is to provide an encapsulation resin in which the occurrence of cracks is suppressed when the resin is used for encapsulation of ultraviolet light-emitting elements. Another object of the present disclosure is to provide an encapsulation resin composition for supplying the encapsulation resin. The present disclosure relates to an encapsulation resin for light-emitting elements, comprising a fluoropolymer, wherein the fluoropolymer comprises, as a main component, a monomer unit represented by formula (1):

##STR00001##

wherein R.sup.1 to R.sup.4 are each independently a fluorine atom, a fluoroalkyl group, or a fluoroalkoxy group.

An object of the present disclosure is to provide a protective display film famed from a fluoropolymer with hardness. The present disclosure relates to a protective display film comprising a fluoropolymer, wherein the fluoropolymer comprises, as a main component, a monomer unit represented by formula (1):

##STR00001##

wherein R.sup.1 to R.sup.4 are each independently a fluorine atom, a fluoroalkyl group, or a fluoroalkoxy group.

An object of the present disclosure is to provide a method for producing a fluorine-containing polymer and a composition containing the fluorine-containing polymer.

The present disclosure provides a composition comprising (A) a fluorine-containing polymer comprising as a main component a structural unit containing a fluorine-containing aliphatic ring, and (B) an aprotic solvent, wherein the fluorine-containing aliphatic ring of the fluorine-containing polymer (A) contains one, two, or three etheric oxygen atoms as a ring-constituting atom; when the fluorine-containing aliphatic ring contains a plurality of etheric oxygen atoms, the etheric oxygen atoms are not adjacent to each other; and the fluorine-containing polymer (A) is present in an amount of 20 mass % or more based on the mass of the composition.

The present invention aims to provide a composition for a secondary battery electrode which is excellent in dispersibility of an active material and adhesiveness, capable of preventing battery deterioration and failure due to moisture absorption, and capable of providing a high-capacity secondary battery. Provided is a composition for a secondary battery electrode, containing: an active material; a binder; and an organic solvent, the binder containing a polyvinyl acetal resin, the polyvinyl acetal resin having an electron-donating group that has an acid dissociation constant in water of less than 16 and an electron-withdrawing group, the polyvinyl acetal resin having a degree of polymerization of 250 to 800 and a hydroxy group content of 35 to 70 mol %.

The present invention aims to provide a composition for a secondary battery electrode which is excellent in dispersibility of an active material and adhesiveness, capable of preventing battery deterioration and failure due to moisture absorption, and capable of providing a high-capacity secondary battery. Provided is a composition for a secondary battery electrode, containing: an active material; a binder; and an organic solvent, the binder containing a polyvinyl acetal resin, the polyvinyl acetal resin having an electron-donating group that has an acid dissociation constant in water of less than 16 and an electron-withdrawing group, the polyvinyl acetal resin having a degree of polymerization of 250 to 800 and a hydroxy group content of 35 to 70 mol %.

The present invention aims to provide a polyvinyl acetal resin composition that is moldable by an extrusion method and capable of exhibiting excellent heat resistance after molding, an adhesive sheet containing the polyvinyl acetal resin composition, and a method for producing the adhesive sheet. The present invention relates to a polyvinyl acetal resin composition including: a polyvinyl acetal; a reactive diluent; and a photopolymerization initiator, the polyvinyl acetal resin composition having a storage modulus G′ at 200° C. before irradiation with light of 8×10.sup.4 Pa or lower and a storage modulus G′ at 200° C. after irradiation with light of 8×10.sup.3 Pa or higher, with the storage modulus G′ at 200° C. after irradiation with light being higher than the storage modulus G′ at 200° C. before irradiation with light.

The present invention aims to provide a polyvinyl acetal resin composition that is moldable by an extrusion method and capable of exhibiting excellent heat resistance after molding, an adhesive sheet containing the polyvinyl acetal resin composition, and a method for producing the adhesive sheet. The present invention relates to a polyvinyl acetal resin composition including: a polyvinyl acetal; a reactive diluent; and a photopolymerization initiator, the polyvinyl acetal resin composition having a storage modulus G′ at 200° C. before irradiation with light of 8×10.sup.4 Pa or lower and a storage modulus G′ at 200° C. after irradiation with light of 8×10.sup.3 Pa or higher, with the storage modulus G′ at 200° C. after irradiation with light being higher than the storage modulus G′ at 200° C. before irradiation with light.

The present invention relates to resin particles including a residue unit represented by the following general formula (1) and having a volume average particle diameter equal to or more than 5 μm and equal to or less than 2000 μm, and a method for producing thereof. Furthermore the present invention relates to a fluororesin comprising a residue unit represented by a general formula (1) and having a weight average molecular weight Mw in a range of 5×10.sup.4 to 3×10.sup.5, and a yellow index of a heat-melted molded product (thickness 3 mm) after 24 h at 280° C. of equal to or less than 6, and a method for producing thereof.

##STR00001##

In the formula (1), Rf.sub.1, Rf.sub.2, Rf.sub.3, and Rf.sub.4 are each independently one of the groups consisting of a fluorine atom, a linear perfluoroalkyl group having 1 to 7 carbon atoms, a branched perfluoroalkyl group having 3 to 7 carbon atoms, or a cyclic perfluoroalkyl group having 3 to 7 carbon atoms. The perfluoroalkyl group may have an ethereal oxygen atom. Further, Rf.sub.1, Rf.sub.2, Rf.sub.3, and Rf.sub.4 may be linked to one another to form a ring having 4 or more and 8 or less carbon atoms, and the ring may include an ethereal oxygen atom.

Provided is an interlayer film for laminated glass which is excellent in sound insulation property and has improved sound insulation performance not only in a coincidence region but also in a mass-dominated region. The interlayer film for laminated glass includes a sound insulating layer which is formed from a composition (A) containing at least one resin (a1) selected from a thermoplastic resin and a thermosetting resin, wherein a tan δ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the composition (A) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T.sub.A (° C.), T.sub.A (° C.) is in a range of −50 to 50° C., and the tan δ at T.sub.A (° C.) is 2.5 or more.