Polylactic Acid Resin Block Copolymer for Flexible Packaging
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Solution Overview
Problem
Conventional polylactic acid resins used for packaging materials suffer from poor flexibility, heat resistance, and mechanical properties, leading to limitations in their application as packaging films due to issues like plasticizer bleed-out, haze, and decreased transparency.
Innovation Solution
A polylactic acid resin is developed with a hard segment comprising polylactic acid repeating units and a soft segment of polyurethane polyol repeating units linked via a urethane bond, achieving a glass transition temperature of 22 to 55°C, which enhances flexibility and mechanical properties while maintaining heat resistance and transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional polylactic acid resins are used for packaging films, then biodegradability is achieved, but flexibility and mechanical properties are poor
Solution Approach 1:
The patent creates a block copolymer composite material consisting of polylactic acid hard segments and polyurethane polyol soft segments. This composite structure combines the biodegradability of PLA with the flexibility and mechanical properties of polyurethane, resolving the contradiction between environmental friendliness and performance
2Ease of operation
If plasticizers are added to improve flexibility, then flexibility increases, but plasticizer bleed-out occurs over time
Solution Approach 1:
The patent merges the plasticizer function directly into the polymer chain by incorporating polyurethane polyol soft segments as part of the block copolymer structure. This eliminates the need for separate plasticizer additives, preventing bleed-out while maintaining flexibility and improving long-term stability
3Ease of operation
If plasticizers are added to improve flexibility, then flexibility increases, but haze increases and transparency decreases
Solution Approach 1:
By integrating the flexible polyurethane polyol segments into the block copolymer structure rather than adding them as separate plasticizer additives, the patent achieves flexibility enhancement without the haze and transparency degradation that occurs with conventional plasticizer addition
Solution Approach 2:
The block copolymer structure ensures homogeneous distribution of the flexible polyurethane segments within the polylactic acid matrix, preventing phase separation and haze formation that would reduce transparency, while still achieving the desired flexibility
4Ease of manufacture
If polylactic acid resins are exposed to high temperature, then processing is enabled, but degradation by depolymerization occurs
Solution Approach 1:
The block copolymer structure with polyurethane polyol soft segments provides thermal stability that protects the polylactic acid hard segments from depolymerization at high temperatures, enabling processing while maintaining heat resistance and preventing degradation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified polylactic acid resin exhibits optimized flexibility, mechanical properties, heat resistance, and transparency, making it suitable for various packaging applications and reducing environmental impact by being biodegradable.
Implementation Method 1
a soft segment comprising a polyurethane polyol repeating unit in which polyether polyol repeating units of the following Chemical Formula 2 are linearly linked via a urethane bond
Data Source
AI summary
The present invention relates to a polylactic acid resin and a packaging film comprising the same, wherein the polylactic acid resin is useful as a packaging material due to excellent properties including heat resistance as well as optimized flexibility. The polylactic acid resin comprises: a hard segment including a predetermined polylactic acid repeating unit; and a soft segment including a polyurethane polyol repeating unit in which certain polyether-based polyol repeating units are linearly connected in a medium of a urethane bond. In addition, the polylactic acid resin has a glass transition temperature (Tg) of 25-55°C.