The invention includes a method of bonding a perfluoroelastomer material to first surface that includes: (a) contacting a first surface with a bonding agent comprising a curable perfluoropolymer and a curing agent; (b) curing the bonding agent to form a perfluoroelastomer material that is bonded to the first surface. In the practice of such method, the bonding agent may be a solution prepared by dissolving the curable perfluoroelastomer and the curing agent in a solvent. In an embodiment of the invention, the perfluoroelastomer material formed in step (b) is a coating layer or, alternatively, the first surface is a surface of a perfluoroelastomer member and the perfluoroelastomer material formed is a perfluoroelastomer weld.

The ultraviolet light-emitting device includes a base, a nitride semiconductor ultraviolet light-emitting element flip-chip mounted on the base, and a lens for sealing a nitride semiconductor ultraviolet light-emitting element to focus or diffuse light emitted from the nitride semiconductor ultraviolet light-emitting device. The lens is composed of an amorphous fluororesin in which a structural unit of a polymer or copolymer has a fluorine-containing aliphatic cyclic structure and a terminal functional group is a perfluoroalkyl group, and a density of the amorphous fluororesin is higher than 2.11 g/cm.sup.3.

To provide a fluorinated copolymer capable of obtaining an article excellent in water and oil repellency, and friction durability of water and oil repellency. A fluorinated copolymer having units based on the following monomer a and units based on the following monomer b, wherein the proportion of the units based on the monomer a is from 20 to 50 mol % based on the total number of moles of units constituting the fluorinated copolymer, the mass average molecular weight is from 20,000 to 100,000, and the ratio of the half-width W.sub.1 of the peak of the fluorinated copolymer to the peak width W.sub.2 in a chromatogram obtainable by high performance liquid chromatography measurement is from 0.35 to 0.55: Monomer a: a compound represented by CH.sub.2═CH—R.sup.f (R.sup.f: a C.sub.1-8 perfluoroalkyl group; Monomer b: a monomer copolymerizable with the monomer a.

To provide a fluorinated copolymer capable of obtaining an article excellent in water and oil repellency, and friction durability of water and oil repellency. A fluorinated copolymer having units based on the following monomer a and units based on the following monomer b, wherein the proportion of the units based on the monomer a is from 20 to 50 mol % based on the total number of moles of units constituting the fluorinated copolymer, the mass average molecular weight is from 20,000 to 100,000, and the ratio of the half-width W.sub.1 of the peak of the fluorinated copolymer to the peak width W.sub.2 in a chromatogram obtainable by high performance liquid chromatography measurement is from 0.35 to 0.55: Monomer a: a compound represented by CH.sub.2═CH—R.sup.f (R.sup.f: a C.sub.1-8 perfluoroalkyl group; Monomer b: a monomer copolymerizable with the monomer a.

A method for producing a fluoropolymer of the invention which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2a—CO—R.sup.3a-A.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-A.sup.b.

A method for producing a fluoropolymer of the invention which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2a—CO—R.sup.3a-A.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-A.sup.b.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2 a—CO—R.sup.3a—OSO.sub.3X.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-OSO.sub.3X.sup.b.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2 a—CO—R.sup.3a—OSO.sub.3X.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-OSO.sub.3X.sup.b.

The instant disclosure relates to ethylene vinyl alcohol copolymer resin composition and/or pellets thereof including one or more fluorine-containing micro-particles. The ethylene vinyl alcohol copolymer resin compositions and/or pellets thereof may have a melting pressure of 1.7 to 7.0 MPa at a shear rate of 20 s.sup.1 and a melting point temperature of 190 C. EVOH films formed from the EVOH may have a Charpy impact strength of at least 2.3 KJ/m.sup.2 according to ISO 179-1 at 23 C. and an elongation at break of at least 17.8% according to ISO 527-2 at 23 C.

The instant disclosure relates to ethylene vinyl alcohol copolymer resin composition and/or pellets thereof including one or more fluorine-containing micro-particles. The ethylene vinyl alcohol copolymer resin compositions and/or pellets thereof may have a melting pressure of 1.7 to 7.0 MPa at a shear rate of 20 s.sup.1 and a melting point temperature of 190 C. EVOH films formed from the EVOH may have a Charpy impact strength of at least 2.3 KJ/m.sup.2 according to ISO 179-1 at 23 C. and an elongation at break of at least 17.8% according to ISO 527-2 at 23 C.