Polymeric piezoelectric material and process for producing the same

Patent metadata

Field	Value
Publication number	US-9559289-B2
Application number	US-201514819663-A
Country	US
Kind code	B2
Filing date	Aug 6, 2015
Priority date	Oct 13, 2011
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A polymeric piezoelectric material is provided that includes an aliphatic polyester (A) with a weight-average molecular weight of from 50,000 to 1,000,000 and having optical activity, and a stabilizing agent (B) with a weight-average molecular weight of from 200 to 60,000 having at least one kind of functional group selected from the group consisting of a carbodiimide group, an epoxy group and an isocyanate group, wherein the crystallinity of the material obtained by a DSC method is from 20% to 80%, a content of the stabilizing agent (B) is from 0.01 part by mass to 10 parts by mass with respect to 100 parts by mass of the aliphatic polyester (A), and internal haze with respect to visible light is 50% or less, as well as a process for producing the same.

First claim

The invention claimed is:

1. A polymeric piezoelectric material comprising:
an aliphatic polyester (A) with a weight-average molecular weight of from 50,000 to 1,000,000 and having optical activity; and
a stabilizing agent (B) with a weight-average molecular weight of from 200 to 60,000 having at least one kind of functional group selected from the group consisting of a carbodiimide group, an epoxy group and an isocyanate group,
wherein the crystallinity of the material obtained by a DSC method is from 20% to 80%, a content of the stabilizing agent (B) is from 0.01 part by mass to 10 parts by mass with respect to 100 parts by mass of the aliphatic polyester (A), and internal haze with respect to visible light is 50% or less.

2. The polymeric piezoelectric material according to claim 1 , wherein the stabilizing agent (B) comprises a stabilizing agent (B3) having, in a molecule, a functional group selected from the group consisting of a carbodiimide group, an epoxy group and an isocyanate group.

3. The polymeric piezoelectric material according to claim 1 , wherein a piezoelectric constant d 14 measured by a displacement method at 25° C. is 1 pm/V or higher.

4. The polymeric piezoelectric material according to claim 1 , wherein internal haze is 13% or less.

5. The polymeric piezoelectric material according to claim 1 , wherein a content of the stabilizing agent (B) is from 0.01 to 2.8 parts by mass with respect to 100 parts by mass of the aliphatic polyester (A).

6. The polymeric piezoelectric material according to claim 1 , wherein a product of a standardized molecular orientation MORc measured by a microwave transmission molecular orientation meter based on a reference thickness of 50 pm and the crystallinity is from 40 to 700.

7. The polymeric piezoelectric material according to claim 1 , wherein the aliphatic polyester (A) is a polylactic acid polymer having a main chain comprising a repeating unit represented by the following formula (1):

8. The polymeric piezoelectric material according to claim 1 , wherein the aliphatic polyester (A) has an optical purity of 95.00% ee or higher.

9. The polymeric piezoelectric material according to claim 1 , wherein a content of the aliphatic polyester (A) is 80 mass % or higher.

10. The polymeric piezoelectric material according to claim 1 , wherein an area of the principal plane is 5 mm 2 or higher.

11. A process for producing the polymeric piezoelectric material according to claim 1 comprising:
a first step for yielding a pre-crystallized sheet comprising the aliphatic polyester (A) and the stabilizing agent (B), and
a second step for stretching the pre-crystallized sheet mainly uniaxially.

12. The process for producing the polymeric piezoelectric material according to claim 11 , wherein an annealing treatment is conducted after the second step.

13. A process for producing the polymeric piezoelectric material according to claim 1 comprising, in the following order:
a step for stretching, mainly uniaxially, a sheet comprising the aliphatic polyester (A) and the stabilizing agent (B); and
a step for conducting an annealing treatment.

14. The polymeric piezoelectric material according to claim 1 , wherein the stabilizing agent (B) comprises a stabilizing agent (B1) with a weight-average molecular weight of from 200 to 900 having at least one kind of functional group selected from the group consisting of a carbodiimide group, an epoxy group and an isocyanate group, and a stabilizing agent (B2) with a weight-average molecular weight of from 1,000 to 60,000 having, in a molecule, 2 or more functional groups of 1 or more kinds selected from the group consisting of a carbodiimide group, an epoxy group and an isocyanate group.

Assignees

• Mitsui Chemicals Inc

Inventors

• Tanimoto Kazuhiro
• Yoshida Mitsunobu
• Nishikawa Shigeo
• Shimizu Masaki

Classifications

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• H01L41/22

  Electricity · mapped topic

• C08G63/08

  Lactones or lactides · CPC title

• B29D7/01

  Films or sheets · CPC title

• B29K2995/004

  Semi-crystalline · CPC title