Abstract: An optical lens includes a lens effective portion, an inclined portion and a flange portion. The lens effective portion has, on a first side, a lens face with a small radius of curvature and also has, on a second side, a lens face with a large radius of curvature. The inclined portion has, on the first side, an inclined face inclined outwardly from the first side to the second side. The flange portion has, on the second side, a reference face protruding longer than the lens face with the large radius of curvature on the second side. Thus, it is possible to obtain an optical lens which is less susceptible to deformation or chipping and suppresses transmission eccentricity, a compound lens and a method for producing the same, as well as a cemented lens and a method for producing the same.

Abstract: In an imaging lens, one compound lens and two single lenses are arranged in a lens barrel. On the light output side of the lens barrel, a filter is arranged with a distance from lens barrel. With a further distance from the filter, an imaging element is arranged. In the compound lens, a resin lens is bonded to a base member lens, having an output surface center of the resin lens displaced by a prescribed amount relative to an output surface center of the base member lens, so that a transmission decentration amount attributed to the base member lens, not including the resin lens, and the single lenses is cancelled by a transmission decentration amount by the resin lens when taken as a whole lens system. Thus, the imaging lens capable of suppressing reduction in resolving power due to transmission decentration of the lenses is obtained.

Abstract: An optical lens includes a lens effective portion, an inclined portion and a flange portion. The lens effective portion has, on a first side, a lens face with a small radius of curvature and also has, on a second side, a lens face with a large radius of curvature. The inclined portion has, on the first side, an inclined face inclined outwardly from the first side to the second side. The flange portion has, on the second side, a reference face protruding longer than the lens face with the large radius of curvature on the second side. Thus, it is possible to obtain an optical lens which is less susceptible to deformation or chipping and suppresses transmission eccentricity, a compound lens and a method for producing the same, as well as a cemented lens and a method for producing the same.

Abstract: A process for preparing a fluorine-containing elastomeric copolymer, a vulcanizing agent and a vulcanization accelerator, said process comprising the step of coagulating the copolymer from an aqueous dispersion of the fluorine-containing elastomeric copolymer and drying the resulting coagulate of the copolymer while kneading, wherein a mixture of mutually soluble components consisting of the vulcanizing agent and the vulcanization accelerator is added to the coagulate, can give a fluororubber composition having stable vulcanization physical properties, wherein the vulcanizing agent and the vulcanization accelerator are homogeneously dispersed in the fluororubber.

Abstract: A laminate, which is in the form of an O-ring, a square ring, a rubber roll, a diaphragm, a rubber hose, a rubber tube or a vial stopper, comprising a layer of a perfluororubber, a layer of other rubber and an adhesive layer containing a polyfunctional compound which adheres the rubber layers by vulcanization is produced by coating a polyfunctional compound on a surface of at least one of the perfluororubber layer or the other rubber layer, laminating the layers with the coated surface facing the other layer, and vulcanizing the layers to adhere them. Thereby, the adhesion strength between the layer of perfluororubber and the layer of the other rubber is improved.

Abstract: A process for preparing a fluorine-containing polymer through emulsion polymerization method which enhances productivity while maintaining excellent physical properties of the fluorine-containing polymer and comprises (a) a first polymerization step for emulsion-polymerizing a fluorine-containing monomer or a mixture of a fluorine-containing monomer and a non-fluorine-containing monomer in an aqueous medium in the presence of a radical polymerization initiator and an emulsifying agent, (b) a dilution step for diluting the obtained aqueous emulsion of polymer particles with water to reduce the number of emulsified polymer particles per unit amount of aqueous medium in the emulsion and a concentration of emulsifying agent, and (c) a second polymerization step for emulsion-polymerizing a fluorine-containing monomer and/or a non-fluorine-containing monomer in the obtained diluted emulsified solution.

Abstract: A fluorine-containing triallyl isocyanurate of the formula [I]: wherein at least one of X and Y is a fluorine atom, and the other is a hydrogen atom or a fluorine atom, exhibits good curing properties even when it is used as a crosslinking aid for elastomers which are required to have good heat resistance, such as in particular, fluororubbers, and provides cured materials having good mechanical properties and heat resistance.

Abstract: A fluororubber composition comprising a fluororubber, a vulcanizing agent and 0.1 to 5 wt. parts of a fatty acid monoamide per 100 wt. parts of said fluororubber. This fluororubber composition is excellent in mold releasability, and a molded article obtained by vulcanizing and molding the composition suffers less deterioration of mechanical properties caused by the addition of an internal mold release agent.

Abstract: A magnetic head comprises a first abutting segment formed with a winding groove having an open side, and a second abutting segment opposed to the open side of the groove and joined to the first segment. The first abutting segment comprises a first core segment having the groove, and gap spacers and second ferromagnetic thin films formed on the surface thereof opposed to the second segment and positioned above and below the groove. The first core segment comprises a core segment member made of a ferromagnetic material, formed with the groove and having a first ferromagnetic thin film which is formed on the surface thereof opposed to the second abutting segment and which is positioned toward the face of the head to be opposed to recording media. The second abutting segment has a face to be opposed to the recording medium and formed by a nonmagnetic material.

Abstract: A copolymer comprising 0.005 to 1.5 mole % of repeating units derived from an iodine-containing fluorinated vinyl ether, 40 to 90 mole % of repeating units derived from vinylidene fluoride, 3 to 35 mole % of repeating units derived from perfluoro(methyl vinyl ether), optionally up to 25 mole % of repeating units derived from hexafluoropropylene and optionally up to 40 mole % of repeating units derived from tetrafluoroethylene, which is obtained by polymerizing the above monomers in the presence of a diiodide compound, contains iodine atoms introduced in the copolymer from the diiodide compound and the iodine-containing fluorinated vinyl ether in amounts of 0.01 to 1 wt. % and 0.01 to 2 wt. %, respectively, and has a Mooney viscosity of 20 to 150.

Abstract: A fluororubber-containing powder coating composition comprising a fluororubber, an adhesion-preventing material and optionally a cross-linking agent, which composition has an particle size of 10 to 2,000 .mu.m and an apparent density of at least 0.2 g/cc, which provides a homogeneous smooth coated film having no or only a small amount of bubbles.

Abstract: A vulcanizable fluororubber composition which contains(a) an iodine- and/or bromine-containing fluororubber,(b) a vulcanizing agent which is an organic peroxide, and(c) a compound of the formula: ##STR1## wherein R.sup.1 and R.sup.2 each is an alkyl group having 1 to 3 carbon atoms, in an amount of 0.05 to 5 ppm based on the fluororubber (a) gives a transparent colorless vulcanized material.

Abstract: A fluororubber-containing powder coating composition comprising a fluororubber, an adhesion-preventing material and optionally a cross-linking agent, which composition has an particle size of 10 to 2,000 .mu.m and an apparent density of at least 0.2 g/cc, which provides a homogeneous smooth coated film having no or only a small amount of bubbles.

Abstract: A floating type composite magnetic head includes a head core fixed to a slider formed of nonmagnetic material. In the head core, a pair of magnetic core halves are abutted against each other with nonmagnetic material such as SiO.sub.2 or the like interposed therebetween. The first and second magnetic core half members have first and second gap forming surfaces to be abutted against each other to define a magnetic gap (g), respectively. A first groove is formed on the second gap forming surface. A glass layer is formed in the first groove. A first thin film including a ferromagnetic metal thin film is selectively formed on the first gap forming surface. A second thin film including a ferromagnetic metal thin film is selectively formed on the second gap forming surface so that at least a portion except the surface of the glass layer in the second gap forming surface is exposed. A second groove is formed on the exposed second gap forming surface adjacent to the first groove.

Abstract: A fluoroelastomer composition comprising a fluoroelastomer, a fluorine-containing surfactant and optionally a vulcanizing agent which has improved processability, particularly mold releasability and mold contamination proofness.

Abstract: A floating-type magnetic head comprising a slider and a core chip secured thereto. The core chip comprises a pair of core segments joined together with a gap spacer and a thin ferromagnetic metal film which are formed at the joint only over a portion of the entire area of the joint which portion terminates at the face of the core chip to be opposed to magnetic recording media. The two core segments area bonded to each other with glass present over the remaining portion of the joint area. In producing the magnetic head, the core chip is prepared by fabricating a core block comprising a pair of base plates joined together and strips of thin ferromagnetic metal film and gap spacer provided at the joint, and machining the core block.

Abstract: A copolymer comprising repeating units derived from tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene in a molar ratio within an area defined on a tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene ternary composition diagram by a hexagon with its first vertex A at 34.0% by weight of tetrafluoroethylene, 8.5% by weight of vinylidene fluoride and 57.5% by weight of hexafluoropropylene; its second vertex B at 26.5% by weight of tetrafluoroethylene, 14.5% by weight of vinylidene fluoride and 59.0% by weight of hexafluoropropylene; its third vertex C at 31.0% by weight of tetrafluoroethylene, 24.0% by weight of vinylidene fluoride and 45.0% by weight of hexafluoropropylene; its fourth vertex D at 49.0% by weight of tetrafluoroethylene, 26.5% by weight of vinylidene fluoride and 24.5% by weight of hexafluoropropylene; its fifth vertex E at 49.0% by weight of tetrafluoroethylene, 11.0% by weight of vinylidene fluoride and 40.

Abstract: An impregnated material comprising an organic or inorganic material selected from the group consisting of a woven fabric, a non-woven fabric and an open cell porous material which is impregnated with a copolymer which comprises 50 to 95% by mole of repeating units derived from tetrafluoroethylene and 5 to 50% by mole of repeating units derived from perfluoroalkyl vinyl ether of the formula:CF.sub.2 .dbd.CFOR.sub.f (I)wherein R.sub.f is a C.sub.1 -C.sub.6 perfluoroalkyl group or a group of the formula:--(CF.sub.2 CFXO).sub.n --R.sub.f (II)wherein R.sub.f is the same as defined above, X is a fluorine atom or a trifluoromethyl group and n is an integer of 1 to 10, which has good chemical, corrosion, solvent and oil resistance as well as water- and oil-repellence.

Abstract: An easily cross linkable fluorine-containing polymer comprising: (1) a polymeric chain comprising one or more polymer segments, at least one polymer segment of which consists of units of at least one fluorine-containing ethylenically unsaturated compound having 2 to 8 carbon atoms, or units of said fluorine-containing ethylenically unsaturated compound and at least one other monomer selected from the group consisting a fluorine-free ethylenically unsaturated compound having 2 to 4 carbon atoms and a fluorine-containing diene having 4 to 8 carbon atoms, (2) at least one bromine atom liberated from a brominated compound of the formula: RBr.sub.x (wherein R is a saturated hydrocarbon residue and x is a number corresponding to the bonding valency of the residue R) in an amount of 0.

Abstract: A fluoroelastomer composition comprising a fluoroelastomer and a thermoplastic fluoroelastomer, which has good roll retention and roll processability and a mixed compound of which has little self-adhesiveness.