Polyester polyol and process for producing the same

Abstract

A cyclic ester (e.g., a lactone such as ε-caprolactone) is ring-opening addition polymerized with a dihydroxycarboxylic acid in the presence of a basic compound (e.g., an amine). In a polyester polyol obtained by such a process, at least part of a carboxyl group of the polyester polyol forms a carboxylate with the basic compound, and the content of the dihydroxycarboxylic acid in a free form can be remarkably reduced (for example, reduced to not more than 5% by weight relative to the total polyester polyol). According to the present invention, a polyester polyol having a reduced content of a free or unreacted dihydroxycarboxylic acid is provided even in the case of using a dihydroxycarboxylic acid (e.g., a dimethylolalkanoic acid such as dimethylolpropionic acid) as an initiator.

Description

Claims

1. A polyester polyol in which a cyclic ester is ring-opening addition polymerized with a dihydroxycarboxylic acid as an initiator, wherein at least part of a carboxyl group of the polyester polyol forms a carboxylate with a basic compound.

2. A polyester polyol according to claim 1, wherein the dihydroxycarboxylic acid comprises a dihydroxyalkanoic acid.

3. A polyester polyol according to claim 1, wherein the dihydroxycarboxylic acid comprises a dimethylolalkanoic acid.

4. A polyester polyol according to claim 1, wherein the cyclic ester comprises a lactone.

5. A polyester polyol according to claim 1, wherein the cyclic ester comprises a caprolactone.

6. A polyester polyol according to claim 1, wherein the basic compound comprises an amine.

7. A polyester polyol according to claim 1, wherein the basic compound comprises a tertiary amine.

8. A polyester polyol according to claim 1, which has a number average molecular weight of 250 to 10000.

9. A polyester polyol according to claim 1, wherein the dihydroxycarboxylic acid in a free form is present in a proportion of not more than 5% by weight relative to the total polyester polyol.

10. A polyester polyol according to claim 1, wherein (i) the dihydroxycarboxylic acid comprises a 2,2-dimethylol-C3-6monoalkanecarboxylic acid, (ii) the cyclic ester comprises a C4-10lactone, (iii) the basic compound comprises at least one member selected from the group consisting of a tertiary alkylamine, a tertiary cycloalkylamine and a tertiary alkanolamine, (iv) the number average molecular weight of the polyester polyol is 300 to 5000, and (v) the dihydroxycarboxylic acid in a free form is present in a proportion of not more than 3% by weight relative to the total polyester polyol.

11. A polyester polyol according to claim 1, which constitutes a polyol component of a polyurethane-series resin.

12. A process for producing a polyester polyol recited in claim 1, which comprises ring-opening addition polymerizing a cyclic ester with a dihydroxycarboxylic acid in the presence of a basic compound.

13. A process according to claim 12, which comprises ring-opening addition polymerizing the cyclic ester with a salt of the dihydroxycarboxylic acid with the basic compound.

14. A polyurethane-series resin comprising at least the following components: a polyol component comprising a polyester polyol recited in claim 1 anda polyisocyanate component.