Abstract: The present invention is envisaged to provide an apparatus and a process for synthesizing lactide, according to which the water content in the produced lactide can be reduced. In operation of the system, lactic acid oligomer discharge valve 10 is closed, allowing transfer of lactic acid to its polycondensing apparatus 2, and concentration and polycondensation of lactic acid are advanced by heating and evacuation, with the produced water being evaporated. Lactic acid, lactic acid oligomer and lactide are removed from the produced gaseous body by condenser 11 and refluxed to the polycondensing apparatus, and then water content in the gaseous body is measured by pressure gauge 12. After confirming that the water content is below a specified value, lactic acid oligomer discharge valve 10 is opened to allow transfer of the lactic acid oligomer, said oligomer being depolymerized to produce gaseous lactide, which is condensed and recovered.

Abstract: According to the present invention, a process for consistently producing lactide from ammonium lactate obtained by lactic fermentation, and a process for consistently producing polylactic acid from ammonium lactate obtained by lactic fermentation, are provided. A process for producing lactide, which comprises the steps of: (1) synthesizing lactate ester from ammonium lactate obtained by lactic fermentation; (2) polycondensing the lactate ester in the presence of a catalyst other than monobutyltin, whereby polylactic acid with a weight-average molecular weight of less than 15,000 (lactic acid prepolymer) is synthesized; and (3) depolymerizing the polylactic, whereby lactide is produced. A process for producing polylactic acid, which comprises the additional step of (4) ring-opening polymerizing said lactide, whereby polylactic acid is obtained. A process for producing lactate ester from ammonium lactate obtained by lactic fermentation.

Abstract: According to the present invention, a process for consistently producing lactide from ammonium lactate obtained by lactic fermentation, and a process for consistently producing polylactic acid from ammonium lactate obtained by lactic fermentation, are provided. A process for producing lactide, which comprises the steps of: (1) synthesizing lactate ester from ammonium lactate obtained by lactic fermentation; (2) polycondensing the lactate ester in the presence of a catalyst other than monobutyltin, whereby polylactic acid with a weight-average molecular weight of less than 15,000 (lactic acid prepolymer) is synthesized; and (3) depolymerizing the polylactic, whereby lactide is produced. A process for producing polylactic acid, which comprises the additional step of (4) ring-opening polymerizing said lactide, whereby polylactic acid is obtained. A process for producing lactate ester from ammonium lactate obtained by lactic fermentation.

Abstract: A method for producing a polylactic acid includes the steps of (a) crystallizing polylactic acid pellets obtainable by direct polymerization of lactic acid or ring-opening polymerization of lactide; and (b) removing low-molecular components having a weight-average molecular weight of 1,000 or less in the resulting crystallized, solid polylactic acid pellets by gasifying the low-molecular components to obtain polylactic acids with substantially no low-molecular components. In this method, an apparatus for removing low-molecular components in polylactic acid pellets includes a crystallizing means for maintaining a temperature between equal to or higher than a glass transition temperature of polylactic acid pellets and equal to or lower than the melting point thereof, while fluidizing the polylactic acid pellets; and a reactor for allowing a heated inert gas and/or heated air to pass through the resulting crystallized, solid polylactic acid pellets obtained by the crystallizing means.

Abstract: A method and system for producing poly(lactic acid) enable trapping and recovering of lactide vapor discharged from a reaction vessel without requiring a solvent or the like. In the method and system, lactide vapor is discharged from a polymerization reaction vessel in which poly(lactic acid) is produced by ring-opening polymerization, and trapped by solidification. The solidified lactide is liquefied by heat. Lactide can be recovered more easily and assuredly.

Abstract: A method for producing a polylactic acid, comprising the steps of carrying out a ring-opening polymerization of lactide to give polylactic acid, adding a compound capable of inactivating a catalyst for ring-opening polymerization of the lactide at the completion of the reaction, and removing unchanged lactide from the polylactic acid product by reducing pressure and/or allowing an inert gas to pass; and a method for forming fiber or film directly from the polylactic acid produced by the invention.

Abstract: A method for producing a polylactic acid of the present invention includes the steps of (a) polymerizing a lactide used as a main starting material in a molten state to give a polylactic acid; and (b) further polymerizing the polylactic acid obtained in step (a) in a solid phase by heating at a temperature lower than a melting point of a final polymer product.

Abstract: The apparatus and method for measuring the intraocular pressure of an eyeball is constructed so that the image of the fluorescent ring around the flattened surface of the eyeball is formed to measure the area of the flattened surface, and that the intraocular pressure of the eyeball is calculated in accordance with the pressure against the eyeball and the area of the flattened surface corresponding thereto.

Abstract: An eye fundus oximeter adapted to measure spectrally the oxygen saturation of the blood in the fundus of the human eye. The oximeter includes an illuminating optical system (8, 21, 10) for first illuminating the fundus of the patient's eye (11) with light of a wide wavelength range and then illuminating the same with light of four different spectra, a photoelectric element (13) for receiving the four kinds of light directly and not via the patient's eye and a photoelectric element (16) for receiving the four kinds of light impringing on the fundus of the eye and then reflected therefrom. The outputs of these photoelectric elements (13, 16) are compared at each of the same spectra, the results of such comparison being subject to given arithmetic operations to evaluate the oxygen saturation.

Abstract: An improved eye fundus camera for photographing the fundus of a patient's eye is disclosed. Three separate energy sources are provided which include a first source of a visible light wave length for illuminating the fundus during photography, a second source including at least a first infrared wavelength band for illuminating the cornea of the patient's eye for alignment of the pupil on the optical axis, and a third source including at least a second infrared wavelength band for illuminating the fundus of the patient's eye for focusing the camera on the fundus. A wavelength selective filter is provided on the optical axis having a predetermined aperature. At least one of the infrared light source wavelengths can be transmitted through the filter to provide a full image of the cornea of the patient's eye for alignment purposes.

Abstract: In a light measuring optical system for use in measurement of pulse waves in the artery at the eye fundus or oxygen saturation in the artery blood at the eye fundus, light for illuminating the eye fundus is converged on the surface of the cornea of the eye to be measured and enters the interior of the eye through a small area within the pupil. Light reflected at the surface of the cornea is converged and blocked at its converging position while the light reflected from the eye fundus is allowed to pass by the light blocking member and reach a photocell. Coupled with the photocell is an electric circuit which transmits AC component of photocell output when DC component of the same assumes its minimum value.