Abstract: Provided is a polyfunctional vinyl aromatic copolymer having reactivity and solubility that can be used for manufacturing a copolymer rubber and a copolymer rubber material having processability, strength and homogeneity obtained therefrom. The polyfunctional vinyl aromatic copolymer includes: 0.5 mol % or more and 40 mol % or less of a structural unit (a) derived from a divinyl aromatic compound and 60 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound, in which at least some of the structural units (a) are a crosslinked structural unit (a2) represented by the following Formula (2) and a vinyl-group-containing structural unit (a1) represented by the following Formula (1): in the formulas, R1's independently represent an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Abstract: To provide a modified vinylaromatic copolymer which can be used in production of copolymer rubber and which has reactivity and solubility, and a copolymer rubber material obtained therefrom, which simultaneously has processability, strength, and homogeneity. The modified vinylaromatic copolymer is a copolymer containing a structural unit (a) derived from a divinylaromatic compound and a structural unit (b) derived from a monovinylaromatic compound, wherein the structural unit (a) at least partially includes the following crosslinked structural unit (a1), and a terminal is modified by a modification group having at least one functional group selected from the group consisting of an amino group, a hydroxyl group, and an alkoxysilyl group.

Abstract: Provided is a polyfunctional vinyl aromatic copolymer having reactivity and solubility that can be used for manufacturing a copolymer rubber and a copolymer rubber material having processability, strength and homogeneity obtained therefrom. The polyfunctional vinyl aromatic copolymer includes: 0.5 mol % or more and 40 mol % or less of a structural unit (a) derived from a divinyl aromatic compound and 60 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound, in which at least some of the structural units (a) are a crosslinked structural unit (a2) represented by the following Formula (2) and a vinyl-group-containing structural unit (a1) represented by the following Formula (1): in the formulas, R1's independently represent an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Abstract: A novel soluble polyfunctional vinyl aromatic copolymer capable of yielding a cured product or molded body having improved heat resistance, compatibility, dielectric properties, wet heat reliability and resistance to thermal oxidative degradation. Disclosed herein is a soluble polyfunctional vinyl aromatic copolymer containing structural units derived from a divinyl aromatic compound (a), styrene (b), and a monovinyl aromatic compound (c) other than styrene. The copolymer includes structural units made up of an unsaturated hydrocarbon group represented by Formula (a1) and derived from the divinyl aromatic compound (a); and the copolymer includes, at terminals thereof, predetermined amounts of specific terminal groups having a vinyl group or a vinylene bond derived from monomers (a), (b), and (c). Also disclosed is a method for producing the copolymer.

Abstract: A novel soluble polyfunctional vinyl aromatic copolymer capable of yielding a cured product or molded body having improved heat resistance, compatibility, dielectric properties, wet heat reliability and resistance to thermal oxidative degradation. Disclosed herein is a soluble polyfunctional vinyl aromatic copolymer containing structural units derived from a divinyl aromatic compound (a), styrene (b), and a monovinyl aromatic compound (c) other than styrene. The copolymer includes structural units made up of an unsaturated hydrocarbon group represented by Formula (a1) and derived from the divinyl aromatic compound (a); and the copolymer includes, at terminals thereof, predetermined amounts of specific terminal groups having a vinyl group or a vinylene bond derived from monomers (a), (b), and (c). Also disclosed is a method for producing the copolymer.

Abstract: Provided is a curable resin composition which: has high levels of dielectric characteristics required in an electrically insulating material application compatible with a high frequency; provides a cured article excellent in low water absorption rate and low linear expansion rate; and is excellent in wire embedding flatness and resin fluidity. Specifically, provided is an aromatic polyester obtained by condensing (a) an aromatic oxycarboxylic acid, (b) an aromatic polyvalent carboxylic acid or an aromatic polyhydric hydroxy compound, and (c) an aromatic monohydroxy compound or an aromatic monocarboxylic acid. Also provided is a curable resin composition containing the aromatic polyester (A), an epoxy resin (D) having two or more epoxy groups per molecule, and a curing accelerator (E).

Abstract: Provided is a curable resin composition which has excellent optical properties, heat resistance, transparency, low water absorbability, and mold release property in molding, and reduces the occurrence of a burr from a mold. Also provided are a cured product thereof and an optical material.

Abstract: Provided is a material suitable for an optical element, which can be applied by inkjet, has an ultraviolet curable characteristic, and yields a cured product excellent in transparency and hardness and having a refractive index of more than 1.5. Specifically, an optical element excellent in transparency and hardness and having a refractive index of more than 1.5 is obtained by preparing a resin composition including at least: (A) 5 to 45 mass % of a vinyl group-containing copolymer obtained by copolymerization of a divinyl aromatic compound; (B) 55 to 94 mass % of a liquid photocurable polyfunctional (meth)acrylate having two or more (meth)acryloyl groups; (C) 0.97 to 20 mass % of a photopolymerization initiator; and (D) 0.03 to 1 mass % of a surfactant, and applying the resin composition onto a support substrate by inkjet, followed by photocuring.

Abstract: An end-modified soluble polyfunctional vinyl aromatic copolymer, which is improved in heat resistance, thermal stability, solvent solubility, and compatibility with acrylate compounds, and a curable resin composition using the same are disclosed. The end-modified soluble polyfunctional vinyl aromatic copolymer is obtained by allowing a divinyl aromatic compound (a), a monovinyl aromatic compound (b), and an aromatic ether compound (c) to react with each other, and has, at an end, an end group derived from the aromatic ether compound and having an acrylate bond. The copolymer has a number average molecular weight Mn of 500 to 100,000, an introduction amount (c1) of the end group derived from the aromatic ether compound satisfies (c1)?1.0 (group/molecule), a molar fraction a? of a structural unit derived from the divinyl aromatic compound and a molar fraction b? of a structural unit derived from the monovinyl aromatic compound in the copolymer satisfy 0.05?a?/(a?+b?)?0.95.

Abstract: Provided is a material suitable for an optical element, which can be applied by inkjet, has an ultraviolet curable characteristic, and yields a cured product excellent in transparency and hardness and having a refractive index of more than 1.5. Specifically, an optical element excellent in transparency and hardness and having a refractive index of more than 1.5 is obtained by preparing a resin composition including at least: (A) 5 to 45 mass % of a vinyl group-containing copolymer obtained by copolymerization of a divinyl aromatic compound; (B) 55 to 94 mass % of a liquid photocurable polyfunctional (meth)acrylate having two or more (meth)acryloyl groups; (C) 0.97 to 20 mass % of a photopolymerization initiator; and (D) 0.03 to 1 mass % of a surfactant, and applying the resin composition onto a support substrate by inkjet, followed by photocuring.

Abstract: Provided is a curable resin composition which has excellent optical properties, heat resistance, transparency, low water absorbability, and mold release property in molding, and reduces the occurrence of a burr from a mold. Also provided are a cured product thereof and an optical material.

Abstract: The present invention relates to a volume phase hologram recording material excellent in transparency, sensitivity, low curing shrinkage, and transparency, a volume phase hologram recording medium, and a volume phase hologram. A photosensitive resin composition for volume phase hologram recording contains a low-molecular-weight solvent-soluble aromatic copolymer (A) having a structural unit of a divinyl aromatic compound and a structural unit of a monovinyl aromatic compound, a photoradical polymerizable compound (B) which is copolymerizable with the soluble aromatic copolymer (A), and a photopolymerization initiator (C) as essential components. The photosensitive resin composition further contains, one kind or more of a polymer binder (D) and a plasticizer (E), and the soluble aromatic copolymer (A) is incorporated in an amount of 5 to 60% by weight.

Abstract: An end-modified soluble polyfunctional vinyl aromatic copolymer, which is improved in heat resistance, thermal stability, solvent solubility, and compatibility with acrylate compounds, and a curable resin composition using the same are disclosed. The end-modified soluble polyfunctional vinyl aromatic copolymer is obtained by allowing a divinyl aromatic compound (a), a monovinyl aromatic compound (b), and an aromatic ether compound (c) to react with each other, and has, at an end, an end group derived from the aromatic ether compound and having an acrylate bond. The copolymer has a number average molecular weight Mn of 500 to 100,000, an introduction amount (c1) of the end group derived from the aromatic ether compound satisfies (c1)?1.0 (group/molecule), a molar fraction a? of a structural unit derived from the divinyl aromatic compound and a molar fraction b? of a structural unit derived from the monovinyl aromatic compound in the copolymer satisfy 0.05?a?/(a?+b?)?0.95.

Abstract: Provided is curable resin composition which gives a cured article excellent in chemical resistance, dielectric properties, low water-absorption, heat resistance, flame retardance, and mechanical properties and which is usable in applications such as dielectric materials, insulating materials, heat-resistant materials, and structural materials. The curable resin composition includes a component (A) which is a polyphenylene ether oligomer having a number-average molecular weight of 700 to 4,000 and having a vinyl group at both end and a component (B) which is a solvent-soluble polyfunctional vinylaromatic copolymer which has structural units derived from monomers including a divinylaromatic compound (a) and an ethylvinylaromatic compound (b) and in which the content of repeating units derived from the divinylaromatic compound (a) is 20 mol % or higher, the ratio of the amount (wt. %) of the component (A) to that (wt. %) of the component (B) being (20 to 98):(2 to 80).

Abstract: The present invention relates to a volume phase hologram recording material excellent in transparency, sensitivity, low curing shrinkage, and transparency, a volume phase hologram recording medium, and a volume phase hologram. A photosensitive resin composition for volume phase hologram recording contains a low-molecular-weight solvent-soluble aromatic copolymer (A) having a structural unit of a divinyl aromatic compound and a structural unit of a monovinyl aromatic compound, a photoradical polymerizable compound (B) which is copolymerizable with the soluble aromatic copolymer (A), and a photopolymerization initiator (C) as essential components. The photosensitive resin composition further contains, one kind or more of a polymer binder (D) and a plasticizer (E), and the soluble aromatic copolymer (A) is incorporated in an amount of 5 to 60% by weight.

Abstract: The present invention relates to a soluble polyfunctional vinylaromatic copolymer improved in heat resistance, resistance to thermal decomposition, solvent solubility, and processability. The soluble polyfunctional vinylaromatic polymer is obtained by cationically polymerizing, at a temperature of 20 to 120° C., one or more monomer ingredients including 20 to 100 mol % divinylaromatic compound (a) in the presence of a donor ingredient, e.g., a quaternary ammonium salt, with the aid of a Lewis acid catalyst and an initiator represented by the following general formula (1) wherein R1 represents hydrogen or a monovalent C1-6 hydrocarbon group; R2 represents an aromatic or aliphatic hydrocarbon group having a valence of p; Z represents halogen or C1-6 alkoxy or acyloxy; and p is an integer of 1 to 6; provided that when two or more R1's and Z's are present per molecule, they may be identical to different from each other.

Abstract: The present invention relates to a soluble polyfunctional vinylaromatic copolymer improved in heat resistance, resistance to thermal decomposition, solvent solubility, and processability. The soluble polyfunctional vinylaromatic polymer is obtained by cationically polymerizing, at a temperature of 20 to 120° C., one or more monomer ingredients including 20 to 100 mol % divinylaromatic compound (a) in the presence of a donor ingredient, e.g., a quaternary ammonium salt, with the aid of a Lewis acid catalyst and an initiator represented by the following general formula (1) wherein R1 represents hydrogen or a monovalent C1-6 hydrocarbon group; R2 represents an aromatic or aliphatic hydrocarbon group having a valence of p; Z represents halogen or C1-6 alkoxy or acyloxy; and p is an integer of 1 to 6; provided that when two or more R1's and Z's are present per molecule, they may be identical to different from each other.

Abstract: Provided is curable resin composition which gives a cured article excellent in chemical resistance, dielectric properties, low water-absorption, heat resistance, flame retardance, and mechanical properties and which is usable in applications such as dielectric materials, insulating materials, heat-resistant materials, and structural materials. The curable resin composition includes a component (A) which is a polyphenylene ether oligomer having a number-average molecular weight of 700 to 4,000 and having a vinyl group at both end and a component (B) which is a solvent-soluble polyfunctional vinylaromatic copolymer which has structural units derived from monomers including a divinylaromatic compound (a) and an ethylvinylaromatic compound (b) and in which the content of repeating units derived from the divinylaromatic compound (a) is 20 mol % or higher, the ratio of the amount (wt. %) of the component (A) to that (wt. %) of the component (B) being (20 to 98):(2 to 80).

Abstract: This invention relates to a curable resin composition which shows excellent chemical resistance, dielectric characteristics, heat resistance, flame retardancy and mechanical properties and low water absorption and is suitable for dielectric materials, insulating materials, heat-resistant materials, structural materials and the like.

Abstract: A syndiotactic styrenic polymer having a narrow molecular weight distribution which is a (co)polymer comprising at least one structural unit represented by the following Formula (1): wherein C1 of a phenyl group thereof has a tacticity of 30% or more in terms of a racemic pentad determined by 13C-NMR, and Ra and m are as defined in the specification. The disclosure is also directed to a block copolymer comprising the above polymer as one segment, to a block graft polymer prepared by modifying one block of the above polymer with a nitrogen-containing aromatic polymer, and to a process for preparing a syndiotactic styrenic polymer in which a styrenic monomer is polymerized in the presence of a catalyst comprising a reaction product of a transition metal compound and at least one co-catalyst selected from organic aluminunoxy compounds.