Process for producing polyester-polycarbonate type thermoplastic polyester elastomer and polyester-polycarbonate type thermoplastic polyester elastomer
The present invention is a process for producing a polyester-polycarbonate type thermoplastic polyester elastomer in which a hard segment consisting of a polyester constructed of aromatic dicarboxylic acid, and an aliphatic or alicyclic diol, and a soft segment consisting mainly of aliphatic polycarbonate are connected, comprising at least a step of increasing the molecular weight of an aliphatic polycarbonate diol by a reaction of an aliphatic polycarbonate diol and a chain extender, and a step of reacting aliphatic polycarbonate and a polyester constructed of aromatic dicarboxylic acid and an aliphatic or alicyclic diol in the molten state.
1. A process for producing a polyester-polycarbonate type thermoplastic polyester elastomer in which a hard segment consisting of a polyester constructed of aromatic dicarboxylic acid, and an aliphatic or alicyclic diol, and a soft segment consisting mainly of aliphatic polycarbonate are connected, comprising at least the following steps:
Step 1: a step of obtaining the aliphatic polycarbonate with the increased molecular weight by a reaction of aliphatic polycarbonate diol and a chain extender,
Step 2: a step of reacting the aliphatic polycarbonate and the polyester in the molten state, wherein the number average molecular weight of the aliphatic polycarbonate is 7000 to 70000.
2. The process for producing the polyester-polycarbonate type thermoplastic polyester elastomer according to claim 1 , wherein the step 1 and the step 2 are performed in different reaction tanks.
3. A polyester-polycarbonate type thermoplastic polyester elastomer obtained by the process as defined in any one of claim 1 or 2 , characterized in that when a cycle of raising the temperature of a polyester-polycarbonate type thermoplastic polyester elastomer from room temperature to 300° C. at the temperature raising rate of 20° C./min using a differential scanning calorimeter, retaining the temperature at 300° C. for 3 minutes, and lowering the temperature to room temperature at the temperature lowering rate of 100° C./min is repeated three times, the melting point difference (Tm1-Tm3) between the melting point (Tm1) obtained by first measurement and the melting point (Tm3) obtained by third measurement is 0 to 50° C.
4. The polyester-polycarbonate type thermoplastic polyester elastomer according to claim 3 , wherein the hard segment consists of a polybutylene terephthalate unit, and the melting point of the resulting polyester-polycarbonate type thermoplastic polyester elastomer is 200 to 225° C.
5. The polyester-polycarbonate type thermoplastic polyester elastomer according to claim 3 , wherein the hard segment consists of a polybutylene naphthalene unit, and the melting point of the resulting polyester-polycarbonate type thermoplastic polyester elastomer is 215 to 240° C.
6. The polyester-polycarbonate type thermoplastic polyester elastomer according to claim 3 , wherein letting the average chain length of the hard segment to be x, and letting the average chain length of the soft segment to be y, calculated using nuclear magnetic resonance (NMR method), the average chain length (x) of the hard segment is 5 to 20, and blocking property B calculated by the following equation (1) is 0.11 to 0.45,
B= 1 /x +1 /y (1).
7. The polyester-polycarbonate type thermoplastic polyester elastomer according to claim 6 , wherein the hard segment consists of a polybutylene terephthalate unit, and the melting point of the resulting polyester-polycarbonate type thermoplastic polyester elastomer is 200 to 225° C.
8. The polyester-polycarbonate type thermoplastic polyester elastomer according to claim 6 , wherein the hard segment consists of a polybutylene naphthalene unit, and the melting point of the resulting polyester-polycarbonate type thermoplastic polyester elastomer is 215 to 240° C.