The present invention provides a perfluoroether fluororubber and a preparation method therefor and use thereof. The perfluoroether fluororubber is prepared by a stepwise polymerization method, wherein polymerization monomers in each step of polymerization comprise tetrafluoroethylene and a perfluoroalkyl vinyl ether. The preparation method for the perfluoroether fluororubber provided in the present invention can shorten polymerization time and improve production efficiency, and the finally obtained perfluoroether fluororubber is good in processability, high in strength, low in hardness and compression deformation and good in medium resistance.

A process for producing a crosslinked polymer involves contacting an epoxidized unsaturated isoolefin copolymer with a catalytic amount of an acid in an absence of a solvent. A process for producing a hydroxylated unsaturated isoolefin copolymer involves contacting an epoxidized unsaturated isoolefin copolymer with a catalytic amount of an acid in an absence of a solvent. A hydroxylated unsaturated isoolefin copolymer having hydroxyl groups in endo configurations may be produced thereby.

A process for producing a crosslinked polymer involves contacting an epoxidized unsaturated isoolefin copolymer with a catalytic amount of an acid in an absence of a solvent. A process for producing a hydroxylated unsaturated isoolefin copolymer involves contacting an epoxidized unsaturated isoolefin copolymer with a catalytic amount of an acid in an absence of a solvent. A hydroxylated unsaturated isoolefin copolymer having hydroxyl groups in endo configurations may be produced thereby.

This disclosure relates to methods and compositions for treating a wafer having a pattern disposed on a surface of the wafer.

This disclosure relates to methods and compositions for treating a wafer having a pattern disposed on a surface of the wafer.

This disclosure relates to methods and compositions for treating a wafer having a pattern disposed on a surface of the wafer.

A method for producing a purified fluoropolymer aqueous dispersion, which includes: (A) bringing a fluoropolymer aqueous dispersion obtained using a hydrocarbon surfactant into contact with an anion exchange resin A or a synthetic adsorbent. The anion exchange resin A has an ion-exchange group represented by the following general formula (A1):

—N+R.sup.1R.sup.2R.sup.3X—

wherein each of R1, R2, and R3 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.1, R.sup.2, and R.sup.3 is an organic group having 3 or more carbon atoms; and X is a counter ion; or an ion-exchange group represented by the following general formula (A2):

—NR.sup.4R.sup.5

wherein each of R.sup.4 and R.sup.5 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.4 and R.sup.5 is an organic group having 2 or more carbon atoms.

A method for producing a purified fluoropolymer aqueous dispersion, which includes: (A) bringing a fluoropolymer aqueous dispersion obtained using a hydrocarbon surfactant into contact with an anion exchange resin A or a synthetic adsorbent. The anion exchange resin A has an ion-exchange group represented by the following general formula (A1):

—N+R.sup.1R.sup.2R.sup.3X—

wherein each of R1, R2, and R3 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.1, R.sup.2, and R.sup.3 is an organic group having 3 or more carbon atoms; and X is a counter ion; or an ion-exchange group represented by the following general formula (A2):

—NR.sup.4R.sup.5

wherein each of R.sup.4 and R.sup.5 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.4 and R.sup.5 is an organic group having 2 or more carbon atoms.

A method for producing a prepolymer for the production of an integral polyurethane foam is provided. The prepolymer is or can be obtained by reaction of a composition that contains the following components: component A containing a polyoxymethylene-polyoxyalkylene block copolymer having a hydroxyl number of 20 mg KOH/g to 200 mg KOH/g as component Al, component B containing di- and/or polyisocyanates with an NCO content of 15 to 45 wt.-% relative to component B, 0.04 to 1.0 wt.-%, relative to the composition, a proton acid as component C, and optionally a component D that contains auxiliary agents, at a characteristic number of 450 to 850. The invention further relates to the prepolymer obtained by the method, to an integral polyurethane foam based on the prepolymer, and to the use thereof.

A method for producing a prepolymer for the production of an integral polyurethane foam is provided. The prepolymer is or can be obtained by reaction of a composition that contains the following components: component A containing a polyoxymethylene-polyoxyalkylene block copolymer having a hydroxyl number of 20 mg KOH/g to 200 mg KOH/g as component Al, component B containing di- and/or polyisocyanates with an NCO content of 15 to 45 wt.-% relative to component B, 0.04 to 1.0 wt.-%, relative to the composition, a proton acid as component C, and optionally a component D that contains auxiliary agents, at a characteristic number of 450 to 850. The invention further relates to the prepolymer obtained by the method, to an integral polyurethane foam based on the prepolymer, and to the use thereof.