A polylactic acid stereocomplex composition, its molded product, a process for its manufacture and its application

Patent metadata

Field	Value
Publication number	US-2016272811-A1
Application number	US-201414778375-A
Country	US
Kind code	A1
Filing date	Mar 19, 2014
Priority date	Mar 20, 2013
Publication date	Sep 22, 2016
Grant date	—

Abstract

The instant invention discloses a polylactic acid stereocomplex composition containing pure stereocomplex crystals and a process for its manufacture. The composition according to this invention comprising (a) 30-70 wt % poly (L-lactic acid) (PLLA). (b) 70-30 wt % poly (D-lactic acid) (PDLA) and (c) 0.01-10 wt % nucleating agent, which can be obtained by solution and melt blending. Stereocomplex crystals are preferentially formed according to the invention, and the homocrystals (a crystal form) for the PLLA or PDLA homopolymer can't be observed. The melting temperature of the composition according to the invention is at least 200° C., which is about 30-50° C. higher than the PLLA or PDLA homopolymer.

First claim

1 . A polylactic acid stereocomplex composition comprising a polylactide blend containing poly (D-lactic acid), and poly (L-lactic acid); and a nucleating agent, wherein the nucleating agent is an aryl amide derivative having the general formula (I);

wherein R 1 is a cycloaliphatic group having 3-8 carbon atoms, and m is an integer which ranges between and includes the values 1-6.

2 . The polylactic acid stereocomplex composition according to claim 1 comprising 0.01-10 wt % of the nucleating agent and 90-99.99 wt % of the polylactide blend, and wherein the polylactic acid stereocomplex composition contains pure stereocomplex crystals.

3 . The polylactic acid stereocomplex composition according to claim 2 , wherein the polylactide blend comprises 30-70 wt % poly (L-lactic acid) and 70-30 wt % poly (D-lactic acid).

4 . The polylactic acid stereocomplex composition according to claim 1 , wherein R 1 represents a naphthenic group with 5 or 6 carbon atoms, and m is an integer which ranges between and includes the values 2-4.

5 . The polylactic acid stereocomplex composition according to claim 1 wherein the nucleating agent is at least one of N,N′-dicyclohexylterephthalamide, and N,N′,N″-tricyclohexyl-1,3,5-benzenetricarboxylamide.

6 . The polylactic acid stereocomplex composition according to claim 1 comprising 0.2-5 wt % of the nucleating agent.

7 . The polylactic acid stereocomplex composition according to claim 1 , wherein the weight-average molecular weight of at least one of the components poly (L-lactic acid) and poly (D-lactic acid) is 10-500 kg/mol, and the optical purity of at least one of the components poly (L-lactic acid) and poly (D-lactic acid is above 90%.

8 . The polylactic acid stereocomplex composition according to claim 1 , wherein the melting point of the composition is above 200° C.

9 . The polylactic acid stereocomplex composition according to claim 1 , wherein the relative content of the stereocomplex crystals in the crystal phase is above 95%, whereby the crystallization is isothermal at a temperature above 120° C.

10 . A molded product comprising polylactic acid stereocomplex composition as claimed in claim 1 .

11 . The molded product according to claim 10 , wherein the melting point of the composition during a second heating process is 200-230° C., and a melting enthalpy ΔH m range is between 45 and 60 J/g.

12 . The molded product according to claim 10 , wherein the storage modulus is between 20 MPa and 60 MPa at 180° C. in curves generated using a dynamic mechanical analyzer.

13 . A process for manufacturing the polylactic acid stereocomplex composition according to claim 1 , comprising a step selected from solution and melt blending.

14 . The process for manufacturing according to claim 13 , wherein poly (L-lactic acid) and poly (D-lactic acid) resins are mixed in trichloromethane at a weight ratio of poly (L-lactic acid)/poly (D-lactic acid) ranging from 30/70 to 70/30, to which mixture 0.01-10 wt % of the nucleating agent, based on a gross weight of the poly (L-lactic acid) and poly (D-lactic acid), is added, to form a mixture and the mixture being subsequently stirred for 1-60 min, after which the stirred mixture is cast on a surface and dried in vacuo, whereby the polylactide stereocomplex composition is obtained.

15 . A polylactic acid stereocomplex composition according to any of claims 1 - 9 or a molded product according to any of claims 10 - 12 for application in garment material, food packaging, medical cloth and heat-resistant end-uses.

16 . The polylactic acid stereocomplex composition according to claim 2 , wherein the polylactide blend comprises 50 wt % poly (L-lactic acid) and 50 wt % poly (D-lactic acid).

17 . The polylactic acid stereocomplex composition according to claim 1 comprising 0.5-3 wt % of the nucleating agent.

18 . The polylactic acid stereocomplex composition according to claim 1 , wherein the weight-average molecular weight of at least one of the components poly (L-lactic acid) and poly (D-lactic acid) is 10-500 kg/mol, and the optical purity of at least one of the components poly (L-lactic acid) and poly (D-lactic acid) is above 98%.

19 . The polylactic acid stereocomplex composition according to claim 1 , wherein the melting point of the composition is between 200 and 230° C.

20 . The polylactic acid stereocomplex composition according to claim 1 , wherein the relative content of the stereocomplex crystals in the crystal phase is substantially 100%, whereby the crystallization is isothermal at a temperature between 120° C. and 140° C.

Assignees

• Inst Of Chemistry Acad Of Sciences
• Purac Biochem Bv

Inventors

• Zhang Xiuqin
• Xiong Zujiang
• Liu Guoming
• Dong Xia
• Wen Tao
• Wang Rui
• Wang Dujin

Classifications

• C08L2205/24

  Crystallisation aids · CPC title

• C08J3/21

  the polymer being premixed with a liquid phase · CPC title

• C08J2467/04

  Polyesters derived from hydroxy carboxylic acids, e.g. lactones (C08J2467/06 takes precedence) · CPC title

• C08L67/04 Primary

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C08L67/06 takes precedence) · CPC title

• C08J2367/04

  Polyesters derived from hydroxy carboxylic acids, e.g. lactones (C08J2367/06 takes precedence) · CPC title