Polycarbonate-polyorganosiloxane copolymer and method for producing same

1. A method of producing a polycarbonate-polyorganosiloxane copolymer, comprising:

(i) continuously or intermittently supplying a polycarbonate oligomer comprising a repeating unit represented by formula (I) and a water-insoluble organic solvent, and a polyorganosiloxane represented by formula (2) and the water-insoluble organic solvent, followed by mixing in the absence of a polymerization catalyst and in the absence of an alkaline compound excluding a tertiary amine and a quaternary ammonium salt, thereby obtaining a first mixed liquid;

(ii) continuously or intermittently supplying and mixing the polymerization catalyst into the first mixed liquid in the absence of the alkaline compound excluding a tertiary amine and a quaternary ammonium salt, thereby obtaining a second mixed liquid;

(iii) continuously or intermittently supplying and mixing an alkaline compound aqueous solution into the second mixed liquid to perform preliminary polymerization while setting a concentration of the alkaline compound aqueous solution to be supplied to 2 to 15 mass %, thereby obtaining a preliminary polymerization liquid; and

(iv) cooling the preliminary polymerization liquid to a temperature of 25° C. or less, followed by continuous or intermittent supply and mixing of the polymerization catalyst, an alkaline compound aqueous solution of a dihydric phenol compound represented by formula (1), and a molecular weight modifier into the preliminary polymerization liquid to perform main polymerization to obtain a polymerization reaction liquid, followed by continuous or intermittent extraction of the polymerization reaction liquid from a reactor,

wherein the polycarbonate-polyorganosiloxane copolymer comprises:

a main chain comprising a repeating unit represented by formula (I) and a constituent unit represented by formula (II):

wherein:

R 1 and R 2 each independently represent a halogen atom, an alkyl group comprising 1 to 6 carbon atoms, or an alkoxy group comprising 1 to 6 carbon atoms;

X represents a single bond, an alkylene group comprising 1 to 8 carbon atoms, an alkylidene group comprising 2 to 8 carbon atoms, a cycloalkylene group comprising 5 to 15 carbon atoms, a cycloalkylidene group comprising 5 to 15 carbon atoms, —S—, —SO—, —SO 2 —, —O—, or —CO—;

a and b each independently represent an integer of from 0 to 4;

R 3 to R 6 each independently represent a hydrogen atom, a halogen atom, an alkyl group comprising 1 to 6 carbon atoms, an alkoxy group comprising 1 to 6 carbon atoms, or an aryl group comprising 6 to 12 carbon atoms;

Y represents a single bond, or an organic residue comprising an aliphatic or aromatic moiety; and

n represents an average repetition number of from 25 to 50,

the polycarbonate-polyorganosiloxane copolymer satisfies the following conditions (a) and (b):

(a) a molded article having a thickness of 2 mm made of the copolymer has a total light transmittance measured based on ISO 13468 of 88% or more and a haze measured based on ISO 14782 of 0.7% or less; and

(b) a molded article having a thickness of 3 mm made of the copolymer has a total light transmittance measured based on ISO 13468 of 88% or more and a haze measured based on ISO 14782 of 1.0% or less,

wherein:

R 3 to R 6 each independently represent a hydrogen atom, a halogen atom, an alkyl group comprising 1 to 6 carbon atoms, an alkoxy group comprising 1 to 6 carbon atoms, or an aryl group comprising 6 to 12 carbon atoms;

Y represents a single bond, or an organic residue comprising an aliphatic or aromatic moiety;

n represents an average repetition number;

Z represents a halogen atom, —R 7 OH, —R 7 —Z′—R 8 —OH, —R 7 COOH, —R 7 NH 2 , —COOH, or —SH, where R 7 represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group, R 8 represents an arylene group comprising 6 to 12 ring-forming carbon atoms, and Z′ represents an alkylene group comprising 1 to 8 carbon atoms, an alkylidene group comprising 2 to 8 carbon atoms, a cycloalkylene group comprising 5 to 10 carbon atoms, or a cycloalkylidene group comprising 5 to 10 carbon atoms; and

m represents 0 or 1, and

wherein:

R 1 and R 2 each independently represent a halogen atom, an alkyl group comprising 1 to 6 carbon atoms, or an alkoxy group comprising 1 to 6 carbon atoms;

X represents a single bond, an alkylene group comprising 1 to 8 carbon atoms, an alkylidene group comprising 2 to 8 carbon atoms, a cycloalkylene group comprising 5 to 15 carbon atoms, a cycloalkylidene group comprising 5 to 15 carbon atoms, —S—, —SO—, —SO 2 —, —O—, or —CO—; and

a and b each independently represent an integer of from 0 to 4.

2. The method according to claim 1 , wherein a terminal of the polycarbonate oligomer used in said supplying (i) comprises a chloroformate group.

3. The method according to claim 1 , wherein the polymerization catalyst used in said supplying (ii) comprises a tertiary amine or a quaternary ammonium salt, or a methylene chloride solution thereof.

4. The method according to claim 1 , wherein the water-insoluble organic solvent comprises methylene chloride.

5. The method according to claim 1 , wherein, in the constituent unit represented by formula (II), Y represents an organic residue derived from allylphenol or eugenol.

6. The method according to claim 1 , wherein, in the repeating unit represented by formula (I), X represents an isopropylidene group, and a=b=0.

7. The method according to claim 1 , wherein, in the constituent unit represented by formula (II), each of R 3 to R 6 represents a methyl group.