US-12624170-B2 - Polylactate stereocomplex and preparation method thereof

Abstract

Provided are a polylactate stereocomplex exhibiting excellent heat resistance and remarkably improved elongation characteristics while maintaining biodegradability, and a preparation method thereof.

Inventors

• Jung Yun CHOI
• Banseok CHOI
• Chul Woong KIM

Assignees

• LG CHEM, LTD.

Dates

Publication Date

20260512

Application Date

20210907

Priority Date

20200907

Claims (10)

1. 1 . A polylactate stereocomplex, comprising: 70 parts by weight to 90 parts by weigh of a poly(L-lactate-3-hydroxypropionate) block copolymer including 10 parts by weight to 40 parts by weight of a poly(3-hydroxypropionate) repeating unit with respect to 100 parts by weight of a poly(L-lactate) repeating unit; and 10 parts by weight to 30 parts by weight of a poly(D-lactate) having a weight average molecular weight of 10,000 g/mol or more to 50,000 g/mol or less, wherein the polylactate stereocomplex has an elongation of 30% to 150%, as measured in accordance with IPC-TM-650 using a tensile strength tester after preparing a dogbone-shaped test specimen of ASTM D638 Type V.
2. 2 . The polylactate stereocomplex of claim 1 , wherein the poly(L-lactate-3-hydroxypropionate) block copolymer has a weight average molecular weight of 10,000 g/mol to 400,000 g/mol.
3. 3 . The polylactate stereocomplex of claim 1 , wherein the poly(D-lactate) has a weight average molecular weight of 15,000 g/mol to 50,000 g/mol.
4. 4 . The polylactate stereocomplex of claim 1 , wherein a melting temperature of the polylactate stereocomplex is 200° C. or higher.
5. 5 . The polylactate stereocomplex of claim 1 , wherein a melting enthalpy of the polylactate stereocomplex is 11 J/g or more.
6. 6 . The polylactate stereocomplex of claim 1 , wherein the polylactate stereocomplex has an elongation of 45% or more to 110% or less, as measured in accordance with IPC-TM-650 using a tensile strength tester after preparing a dogbone-shaped test specimen of ASTM D638 Type V.
7. 7 . A method of preparing a polylactate stereocomplex, the method comprising: mixing (a) 70 parts by weight to 90 parts by weigh of a poly(L-lactate-3-hydroxypropionate) block copolymer including 10 parts by weight to 40 parts by weight of a poly(3-hydroxypropionate) repeating unit with respect to 100 parts by weight of a poly(L-lactate) repeating unit and (b) 10 parts by weight to 30 parts by weight of a poly(D-lactate) having a weight average molecular weight of 10,000 g/mol or more to 50,000 g/mol or less, wherein the polylactate stereocomplex has an elongation of 30% to 150%, as measured in accordance with IPC-TM-650 using a tensile strength tester after preparing a dogbone-shaped test specimen of ASTM D638 Type V.
8. 8 . The method of claim 7 , wherein the poly(L-lactate-3-hydroxypropionate) block copolymer is prepared by a ring-opening polymerization of a lactide monomer in the presence of a poly(3-hydroxypropionate) initiator.
9. 9 . The method of claim 8 , wherein the poly(3-hydroxypropionate) initiator has a weight average molecular weight of 1,500 g/mol to 50,000 g/mol.
10. 10 . The method of claim 8 , wherein the content of the poly(3-hydroxypropionate) initiator is 10 parts by weight or more with respect to 100 parts by weight of the lactide monomer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS s This application is a National Stage Application of International Application No. PCT/KR2021/012104 filed on Sep. 7, 2021, which claims priority to and the benefits of Korean Patent Application No. 10-2020-0113936, filed Sep. 7, 2020, and Korean Patent Application No. 10-2021-0118336, filed on Sep. 6, 2021, the disclosures of which are hereby incorporated by reference herein in their entirety. TECHNICAL FIELD The present invention relates to a polylactate stereocomplex including a poly(L-lactate-3-hydroxypropionate) block copolymer, and a preparation method thereof. BACKGROUND Polylactate (polylactide or polylactic acid) resin is a plant-derived resin obtained from plants such as corn, etc., and is attracting attention as an environment-friendly material having excellent tensile strength and elastic modulus while having biodegradable properties. Specifically, unlike petroleum-based resins such as polystyrene resin, polyvinyl chloride (PVC) resin, polyethylene, etc., which are currently used, polylactate resin has effects of preventing the depletion of petroleum resources, suppressing carbon dioxide emissions, etc., and thus it can reduce environmental pollution, which is a drawback of petroleum-based plastic products. Therefore, as the problem of environmental pollution caused by waste plastic, etc. has emerged as a social problem, it has been attempted to expand the scope of application to the fields of the products where general plastics (petroleum-based resins) were used, such as food packaging materials and containers, electronic product cases, etc. However, the polylactate resin has low impact resistance and heat resistance, as compared with existing petroleum-based resins, and thus its application range is limited. Further, the polylactate resin has poor elongation characteristics and easily exhibits brittleness, which limits its use as a general-purpose resin. Accordingly, to enhance the elongation characteristics of the polylactate resin, a method of compounding an additive or forming a copolymer with a functional monomer, or to enhance heat resistance, a method of adding a nucleating agent or an inorganic additive, etc. has been proposed. However, the additives used in these methods have a problem in that most of them are not biodegradable. Accordingly, it is required to develop a material exhibiting improved heat resistance and elongation characteristics while maintaining biodegradability. BRIEF DESCRIPTION Technical Problem Provided are a polylactate stereocomplex having improved heat resistance and elongation characteristics while maintaining biodegradability, and a preparation method thereof. Technical Solution According to one aspect of the present invention, provided is a polylactate stereocomplex including: a poly(L-lactate-3-hydroxypropionate) block copolymer including 10 parts by weight to 50 parts by weight of a poly(3-hydroxypropionate) repeating unit with respect to 100 parts by weight of a poly(L-lactate) repeating unit; anda poly(D-lactate) having a weight average molecular weight of 5,000 g/mol or more to less than 100,000 g/mol. According to another aspect of the present invention, provided is a method of preparing a polylactate stereocomplex, the method including the step of mixing a poly(L-lactate-3-hydroxypropionate) block copolymer including 10 parts by weight to 50 parts by weight of a poly(3-hydroxypropionate) repeating unit with respect to 100 parts by weight of a poly(L-lactate) repeating unit, and a poly(D-lactate) having a weight average molecular weight of 5,000 g/mol or more to less than 100,000 g/mol. Effect of the Invention A polylactate stereocomplex of the present invention can have excellent physical properties such as heat resistance, elongation characteristics, etc. while maintaining biodegradability, thereby being suitably used as an eco-friendly general-purpose resin. DETAILED DESCRIPTION The terms used in this description are just for explaining exemplary embodiments and it is not intended to restrict the present invention. The singular expression can include the plural expression unless it is differently expressed contextually. It must be understood that the term “include”, “equip”, or “have” in the present description is only used for designating the existence of characteristics taken effect, steps, components, or combinations thereof, and do not exclude the existence or the possibility of addition of one or more different characteristics, steps, components or combinations thereof beforehand. The present invention can be variously modified and have various forms, and specific examples will be illustrated and explained in detail below. However, it is not intended to limit the present invention to the specific examples and it must be understood that the present invention includes every modifications, equivalents, or replacements included in the spirit and technical scope of the present invention. As used herein, the “po