Abstract: A broad band cholesteric liquid crystal film of the present invention is a cholesteric liquid crystal film obtained by coating a liquid crystal mixture containing a polymerizable mesogen compound (a), a polymerizable chiral agent (b) and a photoisomerizable material (c) on a substrate to ultraviolet polymerize a coat of the liquid crystal mixture, and has a reflection bandwidth of 200 nm or more. A broad band cholesteric liquid crystal film of the present invention has a broad reflection band, is of a thin type and can be manufactured in less of manufacturing steps.

Abstract: A broad band cholesteric liquid crystal film of the present invention comprises a cholesteric liquid crystal film obtained by polymerizing a liquid crystal mixture containing a polymerizable mesogen compound (a), a polymerizable chiral agent (b) and a photopolymerization initiator (c) between two substrates with ultraviolet light, and has a reflection bandwidth of 200 nm or more. The broad band cholesteric liquid crystal film of the present invention has a broad reflection band and is excellent in durability.

Abstract: An optical element of the invention comprises at least three laminated circular-polarization-type-reflection polarizers (a) whose wavelength bands for selective reflection of polarized light overlap one another; a layer (b1) which is placed between at least a pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at least ?/8 with respect to incident light inclined by at least 30° relative to the normal direction; and a layer (b2) which is placed between at least another pair of the circular-polarization-type-reflection polarizers (a) and has a front retardation of substantially zero (in the normal direction) and a retardation of at most ?/2 with respect to incident light inclined by 60° relative to the normal direction.

Abstract: The present photosensitive resin composition 2 comprises a polyamic acid resin 4, a photosensitive agent, a dispersible compound 3 dispersible in the polyamic acid resin 4, and a solvent. The porous resin is obtained by removing the solvent from the photosensitive resin composition 2 to form a composition in which the dispersible compound 3 is dispersed in the polyamic acid resin 4, removing the dispersible compound to make the composition porous, and curing the porous photosensitive resin composition. The porous resin enables forming a fine circuit pattern and has a low dielectric constant and, when used as an insulating layer of a circuit board, brings about improved high frequency characteristics.

Abstract: A cholesteric liquid crystal film of the invention consist of a single layer, which is a cholesteric liquid crystal film, formed by applying a liquid crystal mixture containing a polymerizable mesogen compound (A) and a polymerizable chiral agent (B) to an alignment substrate, and applying ultraviolet irradiation to the mixture, wherein a cholesteric liquid crystal film has at least two independent selective reflection wavelength bands. The cholesteric liquid crystal film can be prepared by a simple and easy procedure.

Abstract: To provide a semi-conducting resin composition capable of forming a semi-conducting layer which exhibits a less variable surface resistivity even when subjected to ultrasonic cleaning and effectively discharges static electricity and also provide a wired circuit board comprising the semi-conducting layer composed of the semi-conducting resin composition, an imide resin or a precursor of an imide resin and conducting particles are mixed in a solvent so that the semi-conducting resin composition containing the imide resin or imide resin precursor dissolved therein and the conducting particles dispersed therein is prepared. Then, the semi-conducting resin composition is coated on a surface of an insulating cover layer (5) including the terminal portion (6) of a suspension board with circuit (1) and dried to form a semi-conducting layer (7). Thereafter, the semi-conducting layer 7 formed in the terminal portion (6) is removed by etching.

Abstract: A broad band cholesteric liquid crystal film of the present invention is a cholesteric liquid crystal film obtained by coating a liquid crystal mixture containing a polymerizable mesogen compound (a), a polymerizable chiral agent (b) and a photoisomerizable material (c) on a substrate to ultraviolet polymerize a coat of the liquid crystal mixture, and has a reflection bandwidth of 200 nm or more. A broad band cholesteric liquid crystal film of the present invention has a broad reflection band, is of a thin type and can be manufactured in less of manufacturing steps.

Abstract: A broad band cholesteric liquid crystal film of the present invention comprises a cholesteric liquid crystal film obtained by polymerizing a liquid crystal mixture containing a polymerizable mesogen compound (a), a polymerizable chiral agent (b) and a photopolymerization initiator (c) between two substrates with ultraviolet light, and has a reflection bandwidth of 200 nm or more. The broad band cholesteric liquid crystal film of the present invention has a broad reflection band and is excellent in durability.

Abstract: A sheet with anti-counterfeit functions for making counterfeiting highly difficult in the case where authentication information is recorded using the properties of cholesteric liquid crystal is provided. A cholesteric liquid crystal layer 110 having a selective reflected wavelength band in at least the visible light region is provided in such a manner that this cholesteric liquid crystal layer 110 is a single layer of which thickness is approximately uniform, and an authentication region 112 of which selective reflected wavelength band is different is provided in at least one place. Preferably, an adhesive layer 130 is provided on one side of the cholesteric liquid crystal layer 110. Preferably, a base 120 is provided between the cholesteric liquid crystal layer 110 and the adhesive layer 130. Preferably, a light absorbing layer 140 is provided on adhesive layer 130 of the cholesteric liquid crystal layer 110.

Abstract: A photosensitive polyimide resin precursor composition capable of providing a polyimide resin that is not substantially colored, is transparent and has heat resistance, an optical polyimide resin obtained from the composition, and an optical waveguide using the polyimide resin. The photosensitive polyimide resin precursor composition contains (a) 100 parts by weight of a polyamic acid obtained from a tetracarboxylic acid dianhydride and a diamine, (b) 0.01 parts by weight or more and less than 5 parts by weight of a 1,4-dihydropyridine derivative, (c) 5–50 parts by weight of a glycol (ether). The optical polyimide resin is obtained by irradiating the photosensitive resin precursor composition with UV light, followed by exposure, heating, development, and then heating. The optical waveguide comprises a core layer comprising the optical polyimide resin, and a cladding layer thereof.

Abstract: A method of producing porous polyimide resin that enables pores to be formed in a precursor of polyimide resin, with its form of microphase-separated structure wherein a dispersive compound is dispersed in the precursor of polyimide resin being kept unchanged, so as to provide significantly reduced dielectric constant and also provide improvement in mechanical strength and heat resistance, and the porous polyimide resin produced in the same producing method. A coating comprising porous polyimide resin is formed by applying resin solution comprising a precursor of polyimide resin and a dispersive compound and then drying a solvent, to form a coating in which the dispersive compound is dispersed in the precursor of polyimide resin; extracting the dispersive compound from the coating for removal to make the precursor of the polyimide resin porous; and imidizing the coating after preheated in a temperature range of 190–250° C.

Abstract: A process of producing a polymer optical waveguide, including (a) a step of forming an undercladding layer on a substrate; (b) a step of forming a photosensitive resin composition layer containing a 1,4-dihydropyridine derivative and a resin on the undercladding layer; (c) a step of irradiating a region of the photosensitive resin composition layer corresponding to a core pattern with UV light through a mask to form UV light-exposed areas and UV light-unexposed areas on the photosensitive resin composition layer; (d) a step of heating the UV light-exposed areas and UV light-unexposed areas of the photosensitive resin composition layer; and (e) a step of forming an overcladding layer on the photosensitive resin composition layer after heating.

Abstract: The present photosensitive resin composition 2 comprises a polyamic acid resin 4, a photosensitive agent, a dispersible compound 3 dispersible in the polyamic acid resin 4, and a solvent. The porous resin is obtained by removing the solvent from the photosensitive resin composition 2 to form a composition in which the dispersible compound 3 is dispersed in the polyamic acid resin 4, removing the dispersible compound to make the composition porous, and curing the porous photosensitive resin composition. The porous resin enables forming a fine circuit pattern and has a low dielectric constant and, when used as an insulating layer of a circuit board, brings about improved high frequency characteristics.

Abstract: A method of producing porous polyimide resin that enables pores to be formed in a precursor of polyimide resin, with its form of microphase-separated structure wherein a dispersive compound is dispersed in the precursor of polyimide resin being kept unchanged, so as to provide significantly reduced dielectric constant and also provide improvement in mechanical strength and heat resistance, and the porous polyimide resin produced in the same producing method. A coating comprising porous polyimide resin is formed by applying resin solution comprising a precursor of polyimide resin and a dispersive compound and then drying a solvent, to form a coating in which the dispersive compound is dispersed in the precursor of polyimide resin; extracting the dispersive compound from the coating for removal to make the precursor of the polyimide resin porous; and imidizing the coating after preheated in a temperature range of 190-250° C.

Abstract: The present photosensitive resin composition 2 comprises a polyamic acid resin 4, a photosensitive agent, a dispersible compound 3 dispersible in the polyamic acid resin 4, and a solvent. The porous resin is obtained by removing the solvent from the photosensitive resin composition 2 to form a composition in which the dispersible compound 3 is dispersed in the polyamic acid resin 4, removing the dispersible compound to make the composition porous, and curing the porous photosensitive resin composition. The porous resin enables forming a fine circuit pattern and has a low dielectric constant and, when used as an insulating layer of a circuit board, brings about improved high frequency characteristics.

Abstract: A process of producing a polymer optical waveguide, including (a) a step of forming an undercladding layer on a substrate; (b) a step of forming a photosensitive resin composition layer containing a 1,4-dihydropyridine derivative and a resin on the undercladding layer; (c) a step of irradiating a region of the photosensitive resin composition layer corresponding to a core pattern with UV light through a mask to form UV light-exposed areas and UV light-unexposed areas on the photosensitive resin composition layer; (d) a step of heating the UV light-exposed areas and UV light-unexposed areas of the photosensitive resin composition layer; and (e) a step of forming an overcladding layer on the photosensitive resin composition layer after heating.

Abstract: A photosensitive polyimide resin precursor composition capable of providing a polyimide resin that is not substantially colored, is transparent and has heat resistance, an optical polyimide resin obtained from the composition, and an optical waveguide using the polyimide resin. The photosensitive polyimide resin precursor composition contains (a) 100 parts by weight of a polyamic acid obtained from a tetracarboxylic acid dianhydride and a diamine, (b) 0.01 parts by weight or more and less than 5 parts by weight of a 1,4-dihydropyridine derivative, (c) 5-50 parts by weight of a glycol (ether). The optical polyimide resin is obtained by irradiating the photosensitive resin precursor composition with UV light, followed by exposure, heating, development, and then heating. The optical waveguide comprises a core layer comprising the optical polyimide resin, and a cladding layer thereof.

Abstract: The polyamic acid of the invention can be obtained by the reaction of an acid anhydride component comprising pyromellitic anhydride and 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane with 2,2′-di-substituted-4,4′-diaminobiphenyls as a first aromatic diamine and any aromatic diamine component, as a second aromatic diamine, of 2,2-bis(4-aminophenoxyphenyl)propanes, 1,1-bis(4-(4-aminophenoxy)-3-t-butyl-6-methylphenyl)butane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane and &agr;,&agr;′-bis(4-aminophenyl)diisopropylbenzenes in an organic solvent. The polyimide resin of the invention can be obtained by heating such a polyamic acid solution. In the production of a circuit board, by using a photosensitive polyamic acid having a sensitizer incorporated in such a polyamic acid solution, a patterned polyimide resin layer can be provided as an insulation layer on a metal foil.

Abstract: A method of efficiently removing a low molecular weight substance from a polyimide precursor or polyimide in which the low molecular weight substance is dispersed as micro-domains, without using a large amount of an organic solvent. The method of removing a low molecular weight substance comprises subjecting either a polymer composition having a micro-domain structure made up of a continuous phase comprising a polyimide precursor and, dispersed therein, a discontinuous phase comprising a low molecular weight substance or a polyimide composition obtained from the polymer composition by converting the polyimide precursor into a polyimide to extraction with a combination of supercritical carbon dioxide and a co-solvent to thereby remove the low molecular weight substance. The co-solvent is preferably an aprotic polar solvent, more preferably a nitrogen compound solvent or a sulfur compound solvent.

Abstract: A curable re-release adhesive which, when subjected to a curing reaction caused by irradiation with radiation, shows a sufficient drop of adhesion and causes the adherend to be warped to a minimized extent as developed by the shrinkage force caused by the curing reaction. The re-release adhesive contains a radiation-reactive polymer including a main chain and a plurality of intramolecular side chains, each such side chain having a terminal carbon-carbon double bond, a chain length of 6 or more in terms of number of atoms, and the same or a different number of atoms as each other side chain in the polymer. The release adhesive shows a shrinkage force of 30 MPa or less as developed by a curing reaction upon irradiation. A re-release adhesive sheet is also disclosed, including a substrate film and an adhesive layer containing the re-release adhesive, provided on one surface thereof.