The present invention pertains to: a fluororesin that includes a residue unit represented by formula (1), and a terminal group represented by formula (2); and a fluororesin that includes a residue unit represented by formula (1) and has a transmittance of 50% or more measured at an optical path length of 10 mm and a wavelength of 275 nm when dissolved in perfluorohexane to produce a 10 wt % perfluorohexane solution.

##STR00001##

In formula (1): Rf.sub.1, Rf.sub.2, Rf.sub.3, and Rf.sub.4 each independently represent one selected from the group consisting of fluorine atoms, C1-7 linear perfluoroalkyl groups, C3-7 branched perfluoroalkyl groups, or C3-7 cyclic perfluoroalkyl groups; the perfluoroalkyl groups may have an etheric oxygen atom; Rf.sub.1, Rf.sub.2, Rf.sub.3, and Rf.sub.4 may bond to each other to form a ring having 4 to 8 carbon atoms; and the ring may include an etheric oxygen atom.

##STR00002##

In formula (2), i is an integer of 3-20. The present invention provides: a fluororesin that includes an oxolane ring, has suppressed yellowing after heating and melting, and especially has reduced discoloration, even in molding of thick products; and a method for producing said fluororesin.

The present invention provides a method for manufacturing an optical resin composition that is less colored and that has a sufficiently low water absorbability. The optical resin composition manufacturing method according to the present invention includes performing a heat treatment of a fluorine-containing polymer under an atmosphere having a water vapor concentration of 100 volppm or less, the fluorine-containing polymer being obtained by polymerization of a monomer group including a fluorine-containing compound having a carbon-carbon double bond using an organic peroxide. In the optical resin composition manufacturing method, for example, the heat treatment causes thermal decomposition of a terminal group of the fluorine-containing polymer and volatilization of a low-molecular compound generated by the thermal decomposition.

The present disclosure relates to a polymer for photoresist and a photoresist composition including the same. The polymer for photoresist may include a polymerization unit comprising a sensitizer, and a protection group. The polymerization unit may include a structure of chemical formula 1:

##STR00001##

wherein R.sub.1 is hydrogen, a halogen element, a methyl group, a trifluoromethyl group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, or a substituted or unsubstituted arylalkyl group having 6 to 18 carbon atoms, and n is an integer of 1 to 100,000.

The present disclosure relates to a polymer for photoresist and a photoresist composition including the same. The polymer for photoresist may include a polymerization unit comprising a sensitizer, and a protection group. The polymerization unit may include a structure of chemical formula 1:

##STR00001##

wherein R.sub.1 is hydrogen, a halogen element, a methyl group, a trifluoromethyl group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, or a substituted or unsubstituted arylalkyl group having 6 to 18 carbon atoms, and n is an integer of 1 to 100,000.

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.

The invention relates to a composition comprising at least one electroactive fluorinated terpolymer, and at least one second polymer compatible with the electroactive fluorinated terpolymer and having a glass transition temperature lower than that of the electroactive fluorinated terpolymer. The invention also relates to a method for producing said composition, and to a device such as an actuator comprising a substrate and a film of the above-mentioned composition.

The invention relates to a composition comprising at least one electroactive fluorinated terpolymer, and at least one second polymer compatible with the electroactive fluorinated terpolymer and having a glass transition temperature lower than that of the electroactive fluorinated terpolymer. The invention also relates to a method for producing said composition, and to a device such as an actuator comprising a substrate and a film of the above-mentioned composition.

The present invention provides 1,3,3,3-tetrafluoropropene (HFO-1234ze) copolymers comprising 1,3,3,3-tetrafluoropropene and one or more comonomers selected from the group consisting of vinyl fluoride (VF), vinylidene fluoride (VF.sub.2), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE), wherein said alkyl contains 1 to 5 carbon atoms, the copolymers being a fluoroplastic or a fluoroelastomer, depending upon monomer content.

The present invention relates to a composition for manufacturing a passivation layer, and specifically, to a composition for manufacturing a passivation layer and a passivation layer formed using the composition, which simultaneously exhibit effects such as a low dielectric constant, a low water absorption rate, excellent pattern formability, and excellent adhesion to an adherend surface.

To provide a method for producing an aqueous liquid containing a vinyl polymer, of which the production efficiency is high, without lowering the yield of the vinyl polymer.

When removing a hydrophilic organic solvent from a mixed liquid comprising a vinyl polymer, the hydrophilic organic solvent and water to produce an aqueous liquid containing the vinyl polymer, a liquid phase and a gas phase are formed in a closed container, a part of the liquid of the liquid phase is formed into small droplets and brought into contact with the gas phase to vaporize the hydrophilic organic solvent, and the vaporized hydrophilic organic solvent is removed from the closed container. Specifically, for example, a closed container 10 having a liquid inlet 22, a gas outlet 30, a liquid outlet 21, a liquid inlet 22 and a liquid outlet 21 which are connected and having an external circulating system provided with means to control the temperature and the pressure of liquid, is filled with a mixed liquid 40 to form a liquid phase 50 and a gas phase 51, the mixed liquid 40 of the liquid phase 50 is circulated from the liquid outlet 21 to the external circulating system 20, and the temperature and the pressure of the mixed liquid 41 in the external circulating system 20 are controlled to conditions such that the hydrophilic organic solvent is easily vaporized in liquid droplets in the gas phase 51, followed by discharging the mixed liquid 41 in the form of the small droplets from the liquid inlet 22 to the gas phase 51 and draining the gas in the gas phase 51 from the gas outlet 30.