Thermally stabilized thermoplastic cycloolefin in resin compositions

A cycloolefin resin composition comprising a thermoplastic resin and stabilizer, wherein said thermoplastic resin comprises

• a cycloolefin random copolymer containing an olefin component and a cycloolefin component represented by the formula (I), (II) or (II-a):
• ##STR33## wherein n is an integer of at least 0, each of R.sup.1 -R.sup.12 independently represents a hydrogen atom, a halogen atom or a hydrocarbon group, R.sup.9 to R.sup.12 may be bonded together to form a monocyclic group or a polycyclic group, the monocyclic group or the polycyclic group may have a crosslinking structure and may further have a double bond, and R.sup.9 to R.sup.12 may form a group containing these rings in combination;
• ##STR34## wherein n.sup.1 is 0 or 1, m is an integer of at least 0, R.sub.2.sup.1 to R.sub.2.sup.18 each, independently, represents an atom or a group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group, R.sub.2 15 to R.sup.2 18 may be bonded together to form a monocyclic group or a polycyclic group, the monocyclic group or the polycyclic group may have a double bond, and R.sup.15 and R.sup.16, or R.sup.17 and R.sup.18 may form an alkyldene group;
• ##STR35## wherein p is an integer of at least 0, q and r are each 0, 1 or 2 , each of R.sub.3.sup.1 to R.sub.3.sup.15, independently, represents an atom or a group selected form the group consisting of a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an aromatic hydrogen group and an alkoxy group, and R.sub.3.sup.5 and R.sub.3.sup.9, or R.sub.3.sup.6 and R.sub.3.sup.7 may be bonded together directly or through an intermediate alkyl group having 1 to 3 carbon atoms, and
• said stabilizer is selected from the group consisting of
• (I) (a) 0.01 to 5 parts by weight of a compound having a molecular weight of not more than 600 and being represented by the formula (A):
• ##STR36## wherein each of R.sup.a and R.sup.b, independently, represents a hydrogen atom or an alkyl group having 1-6 carbon atoms, and R.sup.c represents a group selected from the group consisting of an alkyl group having 1-22 carbon atoms, an alkoxy group having 1-6 carbon atoms and an alkylamino group having 1-6 carbon atoms;
• and
• (b) 0.01 to 5 parts by weight of a compound having a molecular weight of not:more than 600 and being represented by the formula (B):
• ##STR37## wherein each of R.sup.d and R.sup.f, independently, represents an alkyl group having 1-6 carbon atoms, R.sup.e represents an alkyl group having 1-6 carbon atoms or an alkoxy group having 1-6 carbon atoms, and X represents a member selected from the group consisting of an alkylene group, an oxygen atom and a sulfur atom;
• (II) (a), (b) and (c) 0.01 to 1 part by weight of a higher aliphatic acid metal salt;
• (III) (b) and (d) 0.01 to 5 parts by weight of a compound of formula (C):
• ##STR38## wherein R.sup.d and R.sup.f are as defined above;
• wherein the amount of said stabilizers are based on 100 parts by weight of the thermoplastic resin.