Resin composition
A resin composition including an aromatic polyester resin and having high levels of hydrolysis resistance and moldability is provided. The resin composition includes an aromatic polyester resin having a terminal carboxyl group content of not more than 30 eq/ton (component A), a cyclic carbodiimide compound having at least two carbodiimide rings, each having only one carbodiimide group (component B), and a polyvalent hydroxyl group-containing compound having a hydroxyl value of not less than 200 (component C).
1. A resin composition comprising:
(A) an aromatic polyester resin having a terminal carboxyl group content of not more than 30 eq/ton (component A),
(B) a cyclic carbodiimide compound having at least two carbodiimide rings, each having only one carbodiimide group (component B), and
(C) a polyvalent hydroxyl group-containing compound which is at least one selected from the group consisting of a glycerin fatty acid ester and an ether obtained by addition polymerizing alkylene oxide with diglycerin, and having a hydroxyl value of not less than 200 mg KOH/g (component C),
wherein the content of the component B is 0.5 to 1.5 parts by mass based on 100 parts by mass of the component A,
wherein the content of the component C is 0.5 to 1.0 part by mass based on 100 parts by mass of the component A, and
wherein the component C has a hydroxyl value of not more than 600 mg KOH/g.
2. The resin composition according to claim 1 , wherein the component A contains polybutylene terephthalate in an amount of not less than 50 mass %.
3. The resin composition according to claim 1 , wherein the component B is a cyclic carbodiimide compound having a plurality of carbodiimide rings bonded thereto through a spiro bond or a bond group.
4. The resin composition according to claim 1 , wherein the component B is a cyclic carbodiimide compound represented by the following formula:
wherein in the above formula, X is a tetravalent group represented by the following formula (i-1), and Ar 1 to Ar 4 are each independently an orthophenylene group or 1,2-naphthalene-diyl group which may be substituted by a substituent;
5. The resin composition according to claim 1 which has a terminal carboxyl group content of not more than 5 eq/ton.
6. The resin composition according to claim 1 which has a melt viscosity at 280° C. of not more than 300 Pa·s and a reduced viscosity retention of not less than 50% after it is kept for 100 hours in a 121° C., 100% RH (0.2 MPa) pressure cooker test.
7. The resin composition according to claim 2 which has a melt viscosity at 260° C. of not more than 300 Pa·s and a reduced viscosity retention of not less than 80% after it is kept for 100 hours in a 121° C., 100% RH (0.2 MPa) pressure cooker test.
8. A method of producing a resin composition which comprises:
(A) an aromatic polyester resin having a terminal carboxyl group content of not more than 30 eq/ton (component A),
(B) a cyclic carbodiimide compound having at least two rings, each having only one carbodiimide group (component B), and
(C) a polyvalent hydroxyl group-containing compound which is at least one selected from the group consisting of a glycerin fatty acid ester and an ether obtained by addition polymerizing alkylene oxide with diglycerin, and having a hydroxyl value of not less than 200 mg KOH/g (component C),
wherein the content of the component B is 0.5 to 1.5 parts by mass based on 100 parts by mass of the component A,
wherein the content of the component C is 0.5 to 1.0 part by mass based on 100 parts by mass of the component A, and
wherein the component C has a hydroxyl value of not more than 600 mg KOH/g, comprising the step of:
(i) melt kneading together the aromatic polyester resin (component A) and the polyvalent hydroxyl group-containing compound (component C) and then adding and melt kneading the cyclic carbodiimide compound (component B) with the obtained mixture; or
(ii) adding the cyclic carbodiimide compound (component B) and the polyvalent hydroxyl group-containing compound (component C) to the aromatic polyester resin (component A) at the same time and melt kneading them together.
9. A molded article formed from the resin composition of claim 1 .