The present disclosure relates to a polycarbonate and a preparation method thereof, which has a novel structure with an improvement in weather resistance and refractive index, while having excellent mechanical properties.

The present disclosure relates to a polycarbonate and a preparation method thereof, which has a novel structure with an improvement in weather resistance and refractive index, while having excellent mechanical properties.

A sheet formed from a carbon fiber reinforced thermoplastic resin with a simplified production process and excellent mechanical characteristics, and a production method of said sheet is provided. This sheet is formed from a carbon fiber reinforced thermoplastic resin that contains carbon fibers, dichloromethane, and a thermoplastic resin containing at least one of a polycarbonate resin and a polyarylate resin, and the content of the dichloromethane contained in the sheet is 10-10,000 ppm by mass.

A sheet formed from a carbon fiber reinforced thermoplastic resin with a simplified production process and excellent mechanical characteristics, and a production method of said sheet is provided. This sheet is formed from a carbon fiber reinforced thermoplastic resin that contains carbon fibers, dichloromethane, and a thermoplastic resin containing at least one of a polycarbonate resin and a polyarylate resin, and the content of the dichloromethane contained in the sheet is 10-10,000 ppm by mass.

Provided is a polycarbonate of Chemical Formula 1: ##STR00001## wherein in Chemical Formula 1: Ar is C.sub.6-60 arylene unsubstituted or substituted with C.sub.1-10 alkyl; and n and m are each independently an integer from 1 to 50, provided that n+m is 2 or more, and a preparation method thereof.

A copolycarbonate includes 0.005-0.1 mole percent of sulfur-containing carbonate units derived from a sulfur-containing bisphenol monomer, 2-95 mole percent of high heat carbonate units derived from a high heat aromatic dihydroxy monomer, and 5-98 mole percent of a low heat carbonate units derived from a low heat aromatic monomer, each based on the sum of the moles of the carbonate units; and optionally, thioether carbonyl endcaps of the formula —C(═O)-L-S—R, wherein L is a C.sub.1-12 aliphatic or aromatic linking group and R is a C.sub.1-20 alkyl, C.sub.6-18 aryl, or C.sub.7-24 arylalkylene; wherein the sulfur content of the high heat copolycarbonate in the absence of the thioether endcaps is from 5-20 parts per million by weight.

A copolycarbonate includes 0.005-0.1 mole percent of sulfur-containing carbonate units derived from a sulfur-containing bisphenol monomer, 2-95 mole percent of high heat carbonate units derived from a high heat aromatic dihydroxy monomer, and 5-98 mole percent of a low heat carbonate units derived from a low heat aromatic monomer, each based on the sum of the moles of the carbonate units; and optionally, thioether carbonyl endcaps of the formula —C(═O)-L-S—R, wherein L is a C.sub.1-12 aliphatic or aromatic linking group and R is a C.sub.1-20 alkyl, C.sub.6-18 aryl, or C.sub.7-24 arylalkylene; wherein the sulfur content of the high heat copolycarbonate in the absence of the thioether endcaps is from 5-20 parts per million by weight.

The present invention relates to a method for operating a phosgene generator for producing phosgene by reacting carbon monoxide with chlorine in the gas phase on an activated carbon catalyst arranged in a reaction chamber, in which method, after a predefinable operating period, the phosgene production is at least temporarily interrupted by shutting down the phosgene generator over a shutdown period and, after a predefinable downtime, is resumed by starting up the phosgene generator over a start-up period, wherein the method is characterized in that the activated carbon catalyst, before the phosgene generator is started up, is freed of chlorine by adding carbon monoxide so that, during the start-up period, a maximum concentration of chlorine in the gas stream immediately downstream of the reaction chamber of 1000 ppmv is not exceeded. The invention also relates to the use of the phosgene thus obtained in the production of polycarbonate and isocyanates.

The present invention relates to a method for operating a phosgene generator for producing phosgene by reacting carbon monoxide with chlorine in the gas phase on an activated carbon catalyst arranged in a reaction chamber, in which method, after a predefinable operating period, the phosgene production is at least temporarily interrupted by shutting down the phosgene generator over a shutdown period and, after a predefinable downtime, is resumed by starting up the phosgene generator over a start-up period, wherein the method is characterized in that the activated carbon catalyst, before the phosgene generator is started up, is freed of chlorine by adding carbon monoxide so that, during the start-up period, a maximum concentration of chlorine in the gas stream immediately downstream of the reaction chamber of 1000 ppmv is not exceeded. The invention also relates to the use of the phosgene thus obtained in the production of polycarbonate and isocyanates.

The present invention provides a stretched film exhibiting excellent reverse wavelength dispersibility, a circularly polarizing plate, and a display device. The stretched film of an embodiment of the present invention is a stretched film having a slow axis in an in-plane direction, in which the stretched film satisfies a relationship of Formula (A) Re(450)/Re(550)<1.00, and an absorption at a wavelength of 700 to 900 nm in a fast axis direction of the stretched film is larger than an absorption at a wavelength of 700 to 900 nm in a slow axis direction of the stretched film. In Formula (A) Re(450) represents an in-plane retardation of the stretched film at a wavelength of 450 nm and Re(550) represents an in-plane retardation of the stretched film at a wavelength of 550 nm.