Polycarbonate diol, polycarbonate diol-containing composition, polycarbonate diol production method, and polyurethane

A polycarbonate diol-containing composition, comprising a polycarbonate diol that contains a structural unit represented by the following Formula (A) and a structural unit represented by the following Formula (B):

• wherein, R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms and, in this range of the number of carbon atoms, optionally have an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, or a substituent containing these atoms;
• and R3 represents a linear aliphatic hydrocarbon having 3 or 4 carbon atoms,
• wherein
• the polycarbonate diol has a molecular weight of 500 to 5,000,
• the value of the following Formula (I) is 0.3 to 20.0:
• (Content ratio of branched-chain moiety in polymer)/(Content ratio of carbonate group in polymer)×100(%) (I), and
• wherein the polycarbonate diol-containing composition comprises a hydroxyaryl compound in an amount of 0.1% by weight or less relative to the total weight of the polycarbonate diol-containing composition.

A method of producing a polycarbonate diol, the method comprising the step of performing a polymerization reaction of at least one carbonate compound (i) selected from the group consisting of dialkyl carbonates, diaryl carbonates and alkylene carbonates, a diol (ii) represented by the following Formula (C), and a diol (iii) represented by the following formula (D) in the presence of a metal compound catalyst:

• wherein, R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms and, in this range of the number of carbon atoms, optionally have an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, or a substituent containing these atoms;
• and R3 represents a linear aliphatic hydrocarbon having 3 or 4 carbon atoms,
• wherein the polycarbonate diol has a value of the following Formula (I) of 0.3 to 20.0:
• (Content ratio of branched-chain moiety in polymer)/(Content ratio of carbonate group in polymer)×100(%) (I).