A resin comprising a unit of Chemical Formula 1, a method for preparing the same, a resin composition comprising the same, and a molded article comprising the resin composition are described:

##STR00001##

wherein all variables are described herein.

A polycarbonate resin composition or a copolymer, comprising, as main repeating units, a carbonate unit (a-1) having a fluorene ring in a side chain, a carbonate unit (a-2) represented by the following formula (a-2): ##STR00001##
(wherein W represents an alkylene group having 1 to 20 carbon atoms or a cycloalkylene group having 6 to 20 carbon atoms, R represents a branched or linear-chain alkyl group having 1 to 20 carbon atoms or a cycloalkyl group having 6 to 20 carbon atoms optionally having a substituent, and u represents an integer of 0 to 3), and a carbonate unit (a-3) derived from 2,2-bis(4-hydroxyphenyl)propane, wherein 1) a molar ratio of the carbonate unit (a-1) to the carbonate unit (a-2) is from 50/50 to 80/20, and 2) a molar ratio of the total of the carbonate unit (a-1) and the carbonate unit (a-2) to the carbonate unit (a-3) is from 1:99 to 70:30. This polycarbonate resin composition or copolymer has excellent heat resistance, transparency, and bending resistance and has low retardation.

The objective of the present invention is to provide a method for producing a polycarbonate safely and efficiently. A method for producing a polycarbonate is characterized in comprising the step of irradiating a light to a composition comprising a C.sub.1-4 halogenated hydrocarbon, the specific diol compound and the specific base in the presence of oxygen.

The object of the present invention is to provide a polycarbonate resin which is excellent in various properties, such as heat resistance, optical properties, melt processability, etc., and an optical film composed of the same and the present invention relates to a polycarbonate resin containing at least a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2):

##STR00001##

wherein in the formula (1), R.sup.1 to R.sup.6 each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an alkoxy group having 1 to 12 carbon atoms, or a halogen atom.

##STR00002##

Provided is a method of producing a polycarbonate that enables efficient drying of a polycarbonate powder and has no risk of deteriorating the quality of a polycarbonate molded article to be obtained. The method of producing a polycarbonate includes: a step of causing an alkali aqueous solution of a dihydric phenol and phosgene to react with each other in the presence of an organic solvent to produce an organic solvent solution containing a polycarbonate; a powdering step of powdering the organic solvent solution containing the polycarbonate to provide a polycarbonate powder; and a pre-drying step of drying the polycarbonate powder to remove the remaining organic solvent, in which a drying temperature in the pre-drying step is set to a temperature lower than the glass transition temperature of the polycarbonate containing 1.5 mass % of the organic solvent by from 5 C. to 15 C.

The present inventions provide a novel polycarbonate copolymer having high fluidity and high molecular weight which is formed of a structural unit derived from an aliphatic diol compound and a structural unit derived from an aromatic dihydroxy compound, having a structure represented by the formula (III):

##STR00001##

having the content of the structural unit derived from the aliphatic diol compound of 1-30 mol %, having the Q-value (280 C., 160 kg load) in the range from 0.02 to 1.0 ml/s, and having the weight average molecular weight (Mw) of 30,000 to 100,000, and an aromatic polycarbonate compound which is formed of a structural unit derived from an aromatic dihydroxy compound which is suitable for a prepolymer for producing a high fluidity polycarbonate copolymer.

The objective of the present invention is to provide a method for producing a polycarbonate safely and efficiently. A method for producing a polycarbonate is characterized in comprising the step of irradiating a light to a composition comprising a C.sub.1-4 halogenated hydrocarbon, the specific diol compound and the specific base in the presence of oxygen.

According to the present invention, it is possible to provide a polycarbonate resin composition which includes a structural unit (A) derived from a monomer represented by general formula (i) and a structural unit (B) derived from a monomer represented by general formula (ii), and in which the structural unit (A) and the structural unit (B) are contained at a mass ratio of structural unit (A): structural unit (B)=91:9 to 99:1.

##STR00001##

(In general formula (i), R represents a hydrogen atom or an alkyl group having 1-4 carbon atoms.)

##STR00002##

(In general formula (ii), R.sup.1, R.sup.2, R.sup.3, and R.sup.4 each independently represent a hydrogen atom or the like, and Y.sub.1 and Y.sub.2 each independently represent an alkylene group having 1-4 carbon atoms.)

An optical film having a desired wavelength dispersion characteristic, a low photoelastic coefficient and a desired Nz coefficient. The optical film is formed from a copolymer and meets the following conditions (i) to (v): (i) the thickness (d) is 20 to 80 m; (ii) the following formulas (1) and (2) are satisfied:
0.6<R(450)/R(550)<1(1)
1.01<R(650)/R(550)<1.40(2)
(R(450), R(550) and R(650) are retardations within the plane of the film at respective wavelengths); (iii) R(550) is 120 to 160 nm; (iv) the birefringence (n) is not less than 1.510.sup.3; and (v) the Nz coefficient represented by the following formula (4) is 1.18 to 2.40:
Nz=(n.sub.xn.sub.z)/(n.sub.xn.sub.y)(4)
(n.sub.x, n.sub.y and n.sub.z are 3-dimensional birefringences of the film).

Provided is a compound represented by General Formula (1) ##STR00001## in General Formula (1), Ar.sub.1 and Ar.sub.2 independently represent a group selected from the following Formulae, ##STR00002##