78results about How to "High Abbe number" patented technology

A subject for the invention relates to processes for producing a polycarbonate containing a plant-derived starting material and to molded articles thereof, the polycarbonate having excellent mechanical strength, heat resistance, a low refractive index, a large Abbe number, low birefringence, and excellent transparency. The invention relates to a process for producing a polycarbonate which includes a step in which one or more dihydroxy compounds including a dihydroxy compound having at least one linking group —CH₂—O— in the molecule thereof are reacted with a carbonic acid diester in the presence of a polymerization catalyst, wherein the dihydroxy compound having at least one linking group —CH₂—O— in the molecule thereof has a formic acid content lower than 20 ppm. The invention further relates to a molded article constituted of a polycarbonate or a composition of the polycarbonate, the polycarbonate being a polycarbonate which contains constituent units derived from a dihydroxy compound having at least one linking group —CH₂—O— in the molecule thereof and has an Abbe number of 50 or larger and a 5% weight loss temperature of 340° C. or higher.

An optical material of the present invention includes: a phosphor which has an excitation wavelength in a range from 220 nm to 500 nm, a fluorescence wavelength in a range from 380 nm to 650 nm, a maximum excitation wavelength in a range from 350 nm to 400 nm, and a maximum fluorescence wavelength in a range from 400 nm to 500 nm; and an ultraviolet light absorber, and the light transmittance thereof measured at a thickness of 2 mm satisfies the following features (1) to (3):

• • (1) The light transmittance at a wavelength of 440 nm is 80% or higher.
  • (2) The light transmittance at a wavelength of 420 nm is 70% or lower.
  • (3) The light transmittance at a wavelength of 410 nm is 5% or lower.

A material for the lens with gradient refractivity is prepared from thallium oxide 30-45 wt%, sodium (or potassium) oxide 5-12%, zinc oxide 6-12%, SiO2 34-50%, calcium oxide 0-5%, Al2O3 1-6%, zirconium oxide 0-2%, La2O5 0-5% and B2O3 0-10% through compounding, smelting, drawing into filament, ion exchange, surface treating and examining. Its advantages are less color difference, less volatilization in smelting, high Abbe number and high consistence.

The polymerizable composition for optical materials of the present invention includes: (A) a compound having a carbon-carbon double bond and at least one group selected from an isocyanate group and an isothiocyanate group in a molecule; and (B) a polythiol compound.

A method for preparing optical film includes mixing PMMA mixture with solvent uniformly to form a wet film, heating said wet film to form an optical dried film, enabling to mix PMMA mixture in any ratio as per required property with solvent to form a mixed solution then carrying out heat treatment on mixed solution to obtain optical film.

The invention discloses a large wide-angle video lens with a focal length of 8mm, and the lens sequentially comprises a first lens group, a second lens group, a third lens group, a fourth lens group and a fifth lens group from an object side to an image side, the first lens group has positive focal power and is fixed in position, the second lens group has positive focal power and can move along the direction of the optical axis; the first lens group comprises a first negative lens group and a second negative lens group. The first negative lens group comprises at least three negative lenses; the second negative lens group comprises a positive-negative cemented lens with negative focal power and a negative-positive cemented lens with positive focal power, the first lens group is provided with three negative lenses, so that the lens has a large wide angle, the light transmission amount and the resolution of the edge part of the lens can be increased, and the chromatic aberration and the distortion can be corrected due to the arrangement of the two cemented lenses which are matched with each other.

A thermoplastic polyester including: at least one 1,4:3,6-dianhydrohexitol unit (A); at least one cyclic diol unit (B) other than cyclohexanedimethanol units and 1,4:3,6-dianhydrohexitol units (A); and at least one aromatic carboxylic diacid unit (C), the polyester being free from ethylene glycol units. It also relates to the production method and use of same.