Polymeric piezoelectric material and method of producing the same

Patent metadata

Field	Value
Publication number	US-2016284977-A1
Application number	US-201415037524-A
Country	US
Kind code	A1
Filing date	Nov 10, 2014
Priority date	Nov 26, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

There is provided a polymeric piezoelectric material including a helical chiral polymer (A) having a weight-average molecular weight of from 50,000 to 1,000,000 and an optical purity of more than 97.0% ee but less than 99.8% ee as calculated by the following formula, in which a piezoelectric constant d 14 measured at 25° C. by a stress-charge method is 1 pC/N or more:
optical purity(% ee )=100×| L -form amount− D -form amount|/( L -form amount+ D -form amount),   Formula:

[in which an amount of L-form (% by mass) and an amount of D-form of an optically active polymer (% by mass) are values obtained by a method using high-performance liquid chromatography (HPLC)].

First claim

1 . A polymeric piezoelectric material comprising a helical chiral polymer (A) having a weight-average molecular weight of from 50,000 to 1,000,000 and an optical purity of more than 97.0% ee but less than 99.8% ee as calculated by the following formula, wherein a piezoelectric constant d 14 measured at 25° C. by a stress-charge method is 1 pC/N or more:
optical purity(% ee )=100 ×|L -form amount− D -form amount|/( L -form amount+ D -form amount),   formula:

wherein, in the formula, an amount of L-form (% by mass) and an amount of D-form of an optically active polymer (% by mass), are values obtained by a method using a high-performance liquid chromatography (HPLC).

2 . The polymeric piezoelectric material according to claim 1 , wherein the optical purity is from 98.0% ee to 99.6% ee.

3 . The polymeric piezoelectric material according to claim 1 , wherein the optical purity is more than 98.5% ee but less than 99.6% ee.

4 . The polymeric piezoelectric material according to claim 1 , wherein:
an internal haze with respect to visible light is 40% or less, a crystallinity obtained by a DSC method is from 20% to 80%, and a product of the crystallinity and a standardized molecular orientation MORc measured by a microwave transmission type molecular orientation meter based on a reference thickness of 50 μm is from 40 to 700.

5 . The polymeric piezoelectric material according to claim 1 , wherein:
an internal haze with respect to visible light is from 0.05% to 5%, and a standardized molecular orientation MORc measured by a microwave transmission type molecular orientation meter based on a reference thickness of 50 μm is from 2.0 to 10.0.

6 . The polymeric piezoelectric material according to claim 1 , wherein the helical chiral polymer (A) is a polylactic acid-type polymer having a main chain comprising a repeating unit represented by the following formula (1):

7 . The polymeric piezoelectric material according to claim 1 , wherein a content of the helical chiral polymer (A) is 80% by mass or more.

8 . A method of producing the polymeric piezoelectric material according to claim 1 , the method comprising:
heating a film, which is in an amorphous state and comprises the helical chiral polymer (A), to obtain a pre-crystallized film; and stretching the pre-crystallized film principally in a uniaxial direction.

9 . The method of producing the polymeric piezoelectric material according to claim 8 , wherein the heating comprises heating the amorphous-state film at a temperature T, which satisfies the following formula (2) until the crystallinity becomes from 3% to 70%, to obtain the pre-crystallized film:
Tg− 40° C.≦ T≦Tg+ 40° C.,   Formula (2):
wherein in formula (2), Tg represents a glass-transition temperature (° C.) of the helical chiral polymer (A).

10 . The method of producing the polymeric piezoelectric material according to claim 8 , wherein the heating comprises heating the film, which is in an amorphous state and comprises polylactic acid as the helical chiral polymer (A), at from 60° C. to 170° C. for from 5 seconds to 60 minutes, to obtain the pre-crystallized film.

11 . The method of producing the polymeric piezoelectric material according to claim 8 , further comprising conducting an annealing treatment after the stretching.

12 . The polymeric piezoelectric material according to claim 2 , wherein:
an internal haze with respect to visible light is 40% or less, a crystallinity obtained by a DSC method is from 20% to 80%, and a product of the crystallinity and a standardized molecular orientation MORc measured by a microwave transmission type molecular orientation meter based on a reference thickness of 50 μm is from 40 to 700.

13 . The polymeric piezoelectric material according to claim 2 , wherein:
an internal haze with respect to visible light is from 0.05% to 5%, and a standardized molecular orientation MORc measured by a microwave transmission type molecular orientation meter based on a reference thickness of 50 μm is from 2.0 to 10.0.

14 . The polymeric piezoelectric material according to claim 2 , wherein the helical chiral polymer (A) is a polylactic acid-type polymer having a main chain comprising a repeating unit represented by the following formula (1):

15 . The polymeric piezoelectric material according to claim 2 , wherein a content of the helical chiral polymer (A) is 80% by mass or more.

16 . A method of producing the polymeric piezoelectric material according to claim 2 , the method comprising:
heating a film, which is in an amorphous state and comprises the helical chiral polymer (A), to obtain a pre-crystallized film; and stretching the pre-crystallized film principally in a uniaxial direction.

Assignees

• Mitsui Chemicals Inc

Inventors

• Tanimoto Kazuhiro
• Yoshida Mitsunobu
• Nishikawa Shigeo

Classifications

• C08G63/06 Primary

  derived from hydroxycarboxylic acids · CPC title

• H01L41/45

  Electricity · mapped topic

• H01L41/333

  Electricity · mapped topic

• H01L41/193 Primary

  Electricity · mapped topic

• C08L2203/20

  use in electrical or conductive gadgets · CPC title