To provide a process for producing a fluoroolefin copolymer powder for powder coating material, which presents excellent stability of a fluoroolefin copolymer solution obtainable by polymerization in its production process, and which is capable of forming a cured film having an excellent appearance when used for a powder coating material. A monomer mixture comprising specific monomers is polymerized in an organic solvent in the presence of specific amounts of hydrotalcite and at least one compound (B) selected from a potassium salt, a sodium salt, a magnesium salt and a hindered amine-type light stabilizer, to obtain a suspension; an insoluble component is removed from the suspension to obtain a fluoroolefin copolymer solution having a pH of from 3.8 to 6.5 and an APHA value within a range of from 1 to 200; and the organic solvent is removed from the solution to obtain the fluoroolefin copolymer powder.

The present invention relates to a fluororesin including a residue unit represented by a following general formula (1) and having a haze value equal to or less than 2% of a heat-press molded product (thickness 1 mm) with a small haze value of a melt-molded product and a method for producing the same.

##STR00001##

In the formula (1), Rf.sub.1, Rf.sub.2, Rf.sub.3 and Rf.sub.4 each independently represent 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, and a cyclic perfluoroalkyl group having 3 to 7 carbon atoms, the perfluoroalkyl group may have an ethereal oxygen atom, Rf.sub.1, Rf.sub.2, Rf.sub.3 and Rf.sub.4 may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and the ring may include an ethereal oxygen atom. The present invention further relates to a method for producing fluororesin particles that each include a fluorine-containing aliphatic ring structure. The method comprises a precipitation step of lowering a solution temperature of a fluororesin (A) solution in which a fluororesin (A) including a fluorine-containing aliphatic ring structure is dissolved in a solvent (B), to precipitate particles of the fluororesin (A). The method is excelling in productivity and making it possible to remove foreign matter.

The present invention relates to a fluororesin including a residue unit represented by a following general formula (1) and having a haze value equal to or less than 2% of a heat-press molded product (thickness 1 mm) with a small haze value of a melt-molded product and a method for producing the same.

##STR00001##

In the formula (1), Rf.sub.1, Rf.sub.2, Rf.sub.3 and Rf.sub.4 each independently represent 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, and a cyclic perfluoroalkyl group having 3 to 7 carbon atoms, the perfluoroalkyl group may have an ethereal oxygen atom, Rf.sub.1, Rf.sub.2, Rf.sub.3 and Rf.sub.4 may be linked to each other to form a ring having 4 or more and 8 or less carbon atoms, and the ring may include an ethereal oxygen atom. The present invention further relates to a method for producing fluororesin particles that each include a fluorine-containing aliphatic ring structure. The method comprises a precipitation step of lowering a solution temperature of a fluororesin (A) solution in which a fluororesin (A) including a fluorine-containing aliphatic ring structure is dissolved in a solvent (B), to precipitate particles of the fluororesin (A). The method is excelling in productivity and making it possible to remove foreign matter.

Provided is a method for producing a latex comprising hollow resin particles each with a high void ratio and a method for producing hollow resin particles each with a higher void ratio. In the method for producing the latex: a suspension treatment of the mixture liquid which comprises a monomer, a crosslinkable monomer, an oil-soluble polymerization initiator, a fat/fatty oil, a hydrocarbon solvent, a suspension stabilizer and an aqueous medium is carried out to prepare a suspension comprising monomer drops; a polymerization reaction of the suspension is carried out to prepare a precursor composition which comprises precursor particles each having a hollow portion including the hydrocarbon solvent.

Provided is a method for producing a latex comprising hollow resin particles each with a high void ratio and a method for producing hollow resin particles each with a higher void ratio. In the method for producing the latex: a suspension treatment of the mixture liquid which comprises a monomer, a crosslinkable monomer, an oil-soluble polymerization initiator, a fat/fatty oil, a hydrocarbon solvent, a suspension stabilizer and an aqueous medium is carried out to prepare a suspension comprising monomer drops; a polymerization reaction of the suspension is carried out to prepare a precursor composition which comprises precursor particles each having a hollow portion including the hydrocarbon solvent.

The present disclosure provides a process for removing fluoroorganic acidic compounds from a dispersion of fluoroorganic polymer particles in at least one protic solvent, the process comprising the following steps: (i) forming a mixture of a. a dispersion having a pH-value of less than 6 and comprising fluoroorganic polymer particles, at least one protic solvent and at least one fluoroorganic acidic compound with b. an extraction composition comprising at least one alkylamine; (ii) reacting the fluoroorganic acidic compound with the alkylamine to form a hydrophobic ionic compound comprising the anion of the fluoroorganic acidic compound and the cation of the alkyl amine; (iii) separating the mixture into a first phase comprising the at least one protic solvent, the fluoroorganic polymer particles and no greater than 50% by weight of the total amount of the at least one fluoroorganic acidic compound initially present in the dispersion in step (i); and a second phase comprising the hydrophobic ionic compound; and (iv) removing the first phase from the second phase.

The present disclosure provides a process for removing fluoroorganic acidic compounds from a dispersion of fluoroorganic polymer particles in at least one protic solvent, the process comprising the following steps: (i) forming a mixture of a. a dispersion having a pH-value of less than 6 and comprising fluoroorganic polymer particles, at least one protic solvent and at least one fluoroorganic acidic compound with b. an extraction composition comprising at least one alkylamine; (ii) reacting the fluoroorganic acidic compound with the alkylamine to form a hydrophobic ionic compound comprising the anion of the fluoroorganic acidic compound and the cation of the alkyl amine; (iii) separating the mixture into a first phase comprising the at least one protic solvent, the fluoroorganic polymer particles and no greater than 50% by weight of the total amount of the at least one fluoroorganic acidic compound initially present in the dispersion in step (i); and a second phase comprising the hydrophobic ionic compound; and (iv) removing the first phase from the second phase.

The present disclosure provides a process for removing fluoroorganic acidic compounds from a dispersion of fluoroorganic polymer particles in at least one protic solvent, the process comprising the following steps: (i) forming a mixture of a. a dispersion having a pH-value of less than 6 and comprising fluoroorganic polymer particles, at least one protic solvent and at least one fluoroorganic acidic compound with b. an extraction composition comprising at least one alkylamine; (ii) reacting the fluoroorganic acidic compound with the alkylamine to form a hydrophobic ionic compound comprising the anion of the fluoroorganic acidic compound and the cation of the alkyl amine; (iii) separating the mixture into a first phase comprising the at least one protic solvent, the fluoroorganic polymer particles and no greater than 50% by weight of the total amount of the at least one fluoroorganic acidic compound initially present in the dispersion in step (i); and a second phase comprising the hydrophobic ionic compound; and (iv) removing the first phase from the second phase.

The method produces hollow resin particles. The method comprising steps of: preparing a mixture liquid comprising (A) a monomer comprising at least one monomer selected from the group consisting of a monovinyl monomer and a hydrophilic monomer excluding acrylonitrile and methacrylonitrile, (B) a crosslinkable monomer, (C) an oil-soluble polymerization initiator, (E) a hydrocarbon solvent, (F) a suspension stabilizer and (G) an aqueous medium; carrying out a suspension treatment of the mixture liquid to prepare a suspension; carrying out a polymerization reaction of the suspension to prepare a precursor composition; carrying out a solid-liquid separation of the precursor composition to obtain the precursor particles; and removing the hydrocarbon solvent (E) included in the precursor particles.

The method produces hollow resin particles. The method comprising steps of: preparing a mixture liquid comprising (A) a monomer comprising at least one monomer selected from the group consisting of a monovinyl monomer and a hydrophilic monomer excluding acrylonitrile and methacrylonitrile, (B) a crosslinkable monomer, (C) an oil-soluble polymerization initiator, (E) a hydrocarbon solvent, (F) a suspension stabilizer and (G) an aqueous medium; carrying out a suspension treatment of the mixture liquid to prepare a suspension; carrying out a polymerization reaction of the suspension to prepare a precursor composition; carrying out a solid-liquid separation of the precursor composition to obtain the precursor particles; and removing the hydrocarbon solvent (E) included in the precursor particles.