Abstract: To provide methods for producing a wet gel and a xerogel, in which variation in gel thickness is little even without highly controlling the levelness of the mold and the gels are less likely to break at the time of gelation or demolding. The method for producing a wet gel comprises, in such a state that a second liquid layer 14 made of a second liquid containing a gel raw material, is present on a first liquid layer 12 made of a first liquid, letting the second liquid layer 14 be gelled. The method for producing a xerogel comprises drying the wet gel thereby produced or a solvent-substituted gel obtainable by subjecting said wet gel to solvent substitution.

Abstract: To provide a curable composition capable of obtaining a cured product which has a high Abbe number, is excellent in transparency and crack resistance, and is capable of suppressing a decrease in transparency over a long period of time; and such a cured product. This curable composition comprises solid silica fine particles A, of which an organic component is at most 5 mass % and the median diameter is from 5 to 20 nm, (meth)acrylate B which has an alicyclic condensed ring, and of which the glass transition temperature of the homopolymer is from 90 to 350° C., epoxy(meth)acrylate C which has no aromatic ring, and in which the amount of substance of ethylenically unsaturated groups is from 0.1 to 3.

Abstract: To provide a curable composition whereby it is possible to obtain a cured product having a high Abbe number and being excellent in transparency, crack resistance and releasability; and such a cured product. A curable composition comprises, in specific ratios, surface-modified metal oxide particles (A) having (meth)acryloyl-group-containing surface-modifying groups on the surface of the metal oxide particles, a compound (B) having a fluorine atom and at least one (meth)acryloyl group, a compound (C) having a urethane bond or —OCH2CH(OH)CH2—, having at least two (meth)acryloyl groups and having a mass-average molecular weight of at least 1,000, a compound (D) having no unsaturated bond-containing ring structure and having at least one (meth)acryloyl group, and a polymerization initiator (E).

Abstract: Surface-modified metal oxide particles, includes: a metal oxide particle having a refractive index of at least 1.9 to light having a wavelength of 589 nm; a first surface-modifying group having a group represented by formula (A1); and a second surface-modifying group having a group represented by formula (A2). R1 is a hydrogen atom or a C1-4 hydrocarbon group; n is an integer of from 1 to 20, m is an integer of at least 3 and at most (2n+1); a is an integer of from 0 to 2; R3 is a hydrogen atom or a methyl group; R4 is a hydrogen atom or a C1-4 hydrocarbon group; X is —O— or —NH—; b is an integer of from 2 to 10; and c is an integer of from 0 to 2.

Abstract: To provide a curable composition capable of obtaining a cured product which has a high Abbe number, is excellent in transparency and crack resistance, and is capable of suppressing a decrease in transparency over a long period of time; and such a cured product. This curable composition comprises solid silica fine particles A, of which an organic component is at most 5 mass % and the median diameter is from 5 to 20 nm, (meth)acrylate B which has an alicyclic condensed ring, and of which the glass transition temperature of the homopolymer is from 90 to 350° C., epoxy(meth)acrylate C which has no aromatic ring, and in which the amount of substance of ethylenically unsaturated groups is from 0.1 to 3.

Abstract: To provide a curable composition whereby it is possible to obtain a cured product having a high Abbe number and being excellent in transparency, crack resistance and releasability; and such a cured product. A curable composition comprises, in specific ratios, surface-modified metal oxide particles (A) having (meth)acryloyl-group-containing surface-modifying groups on the surface of the metal oxide particles, a compound (B) having a fluorine atom and at least one (meth)acryloyl group, a compound (C) having a urethane bond or —OCH2CH(OH)CH2—, having at least two (meth)acryloyl groups and having a mass-average molecular weight of at least 1,000, a compound (D) having no unsaturated bond-containing ring structure and having at least one (meth)acryloyl group, and a polymerization initiator (E).

Abstract: To provide methods for producing a wet gel and a xerogel, in which variation in gel thickness is little even without highly controlling the levelness of the mold and the gels are less likely to break at the time of gelation or demolding. The method for producing a wet gel comprises, in such a state that a second liquid layer 14 made of a second liquid containing a gel raw material, is present on a first liquid layer 12 made of a first liquid, letting the second liquid layer 14 be gelled. The method for producing a xerogel comprises drying the wet gel thereby produced or a solvent-substituted gel obtainable by subjecting said wet gel to solvent substitution.

Abstract: To provide a fluorinated compound capable of obtaining a cured product which is excellent in heat resistance and mold release and has a high Abbe number; a curable composition containing such a compound; and a cured product which is excellent in heat resistance and mold release and has a high Abbe number. The fluorinated compound is represented by the following formula (A): [Z—OCH2CF2CF2CF2OCFHCF2—X—]nQ??(A) where n is an integer of at least 1, Q is a n-valent organic group, X is —O—, —NH— or —S—, and Z is a group having at least one polymerizable functional group.

Abstract: To provide surface-modified metal oxide particles which are readily dispersed in a liquid fluorinated compound having a high fluorine atom content, and a method for producing them; a dispersion liquid having a high Abbe number and being excellent in transparency; and a curable composition from which a cured product having a high Abbe number and being excellent in transparency can be obtained, and its cured product. Surface-modified metal oxide particles (A) comprising metal oxide particles having a refractive index of at least 1.9 and on their surface, specific fluoroalkyl group-containing surface-modifying groups and specific (meth)acryloyl group-containing surface-modifying groups; a dispersion liquid containing the surface-modified metal oxide particles (A) and a fluorinated compound which has a fluorine atom content of at least 20 mass % and which is liquid at 25° C.

Abstract: To provide a curable composition whereby it is possible to obtain a cured product having a high Abbe number and being excellent in transparency, crack resistance and releasability; and such a cured product. A curable composition comprises, in specific ratios, surface-modified metal oxide particles (A) having (meth)acryloyl-group-containing surface-modifying groups on the surface of the metal oxide particles, a compound (B) having a fluorine atom and at least one (meth)acryloyl group, a compound (C) having a urethane bond or —OCH2CH(OH)CH2—, having at least two (meth)acryloyl groups and having a mass-average molecular weight of at least 1,000, a compound (D) having no unsaturated bond-containing ring structure and having at least one (meth)acryloyl group, and a polymerization initiator (E).

Abstract: A laminated glass includes, in the following order, a first glass plate, a first transparent adhesive layer, a transparent heat-insulating layer having interconnected pores, a second transparent adhesive layer, and a second glass plate. The laminated glass has a value of A in the expression (1) of 7.0×105 or smaller and a value of B in the expression (2) of 35 or larger. In the expressions, D is a pore diameter (nm) of the interconnected pores of the transparent heat-insulating layer, P is a porosity of the transparent heat-insulating layer, di is a thickness (mm) of the transparent heat-insulating layer, dg is a sum (mm) of a thickness of the first glass plate and a thickness of the second glass plate, and da is a sum (mm) of a thickness of the first transparent adhesive layer and a thickness of the second transparent adhesive layer; [ Math . ? 1 ] A = D 3 ? Pd i ( 1 ) B = d g + 3.3 ? d e + 0.75 ? d i ? ( D + 260.8 0.

Abstract: To provide a fluorinated compound capable of obtaining a cured product which is excellent in heat resistance and mold release and has a high Abbe number; a curable composition containing such a compound; and a cured product which is excellent in heat resistance and mold release and has a high Abbe number. The fluorinated compound is represented by the following formula (A): [Z—OCH2CF2CF2CF2OCFHCF2—X-]nQ??(A) where n is an integer of at least 1, Q is a n-valent organic group, X is —O—, —NH— or —S—, and Z is a group having at least one polymerizable functional group.

Abstract: The invention provides a process for producing a fluorine-containing compound from an inexpensive material. Namely, Compound I such as RACH2OH is reacted with Compound II such as XCORB to form Compound III such as RACH2OCORB, followed by fluorination in a liquid phase to form Compound IV such as RAFCF2OCORBF, which is converted to Compound V such as RAFCOF and/or Compound VI such as RBFCOF. RA is an alkyl group or the like, RB is a perhalogenoalkyl group or the like, RAF and RBF are fluorinated RA and RB, and X is halogen.

Abstract: The present invention provides a method for preparing a compound of CF3CF2CF2OCF?CF2 by pyrolyzing a compound expressed by CF3CF2CF2OCF(CF3)COOCF2CF(CF3)OCF2CF2CF3 in a gas phase at a temperature of from 200° C. to 500° C.

Abstract: A plastic optical fiber low in attenuation in a high order mode and small in mode dispersion, is presented. The plastic optical fiber comprises at least a core and a clad surrounding the core, characterized in that the core has a refractive index which gradually decreases from the core center towards the outside in the radial direction of the plastic optical fiber, and the refractive index of the clad is lower than the refractive index of the core center and higher than the refractive index of the core periphery.

Abstract: A process for producing a fluorinated ester through a small number of steps, is presented. The process for producing a fluorinated ester, comprises a transesterification step in which RAF—COOCF2—RAF and RA—CH2OH are subjected to a transesterification reaction to obtain RAF—COOCH2—RA, and a fluorination step in which the obtained compound is fluorinated to obtain a reaction product containing RAF—COOCF2—RAF. Here, in the formulae, RA is a monovalent organic group, and RAF is the same group as RA or a monovalent organic group obtained by fluorination of RA.

Abstract: A process for producing a fluorinated ester through a small number of steps, is presented. The process for producing a fluorinated ester, comprises a transesterification step in which RAF—COOCF2—RAF and RA—CH2OH are subjected to a transesterification reaction to obtain RAF—COOCH2—RA, and a fluorination step in which the obtained compound is fluorinated to obtain a reaction product containing RAF—COOCF2—RAF. Here, in the formulae, RA is a monovalent organic group, and RAF is the same group as RA or a monovalent organic group obtained by fluorination of RA.

Abstract: To provide a novel porous plastic optical transmission article which is easy to produce and excellent in heat resistance, flame retardancy, chemical resistance and solvent resistance and exhibits a low attenuation and a high bandwidth, and a process for its production. A porous plastic optical transmission article which is an optical transmission article made of an amorphous fluoropolymer containing substantially no C—H bond and which has a plurality of pores at least in a hollow tubular portion provided so as to surround the axial core portion of the optical transmission article. For example, an optical fiber, etc.

Abstract: The invention provides a process for producing a fluorine-containing compound from an inexpensive material. Namely, Compound I such as RACH2OH is reacted with Compound II such as XCORB to form Compound III such as RACH2OCORB, followed by fluorination in a liquid phase to form Compound IV such as RAFCF2OCORBF, which is converted to Compound V such as RAFCOF and/or Compound VI such as RBFCOF. RA is an alkyl group or the like, RB is a perhalogenoalkyl group or the like, RAF and RBF are fluorinated RA and RB, and X is halogen.

Abstract: A plastic optical fiber low in attenuation in a high order mode and small in mode dispersion, is presented. The plastic optical fiber comprises at least a core and a clad surrounding the core, characterized in that the core has a refractive index which gradually decreases from the core center towards the outside in the radial direction of the plastic optical fiber, and the refractive index of the clad is lower than the refractive index of the core center and higher than the refractive index of the core periphery.