Oriented Polylactic Acid Film Reducing Noise and Plasticizer Migration
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Solution Overview
Problem
Existing polylactic acid (PLA) films face challenges with noise due to high dielectric loss tangent, plasticizer migration, and limited thermal stability, which affect their mechanical and optical properties.
Innovation Solution
The development of oriented films comprising a mixture of semicrystalline polylactic acid polymer, polyvinyl acetate polymer with a glass transition temperature of at least 25°C, and a plasticizer, which are processed to exhibit a single midpoint glass transition temperature ranging from 40°C to 65°C, reducing noise and improving thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PLA films are made with conventional compositions, then they are easy to manufacture, but they exhibit high noise due to high dielectric loss tangent
Solution Approach 1:
The patent uses a composite material system consisting of semicrystalline PLA polymer blended with amorphous PLA polymer. This composite structure allows the semicrystalline component to provide mechanical strength while the amorphous component suppresses dielectric loss tangent and reduces noise, resolving the contradiction between ease of manufacture and noise reduction.
Solution Approach 2:
The patent changes the compositional parameters by controlling the ratio of semicrystalline to amorphous PLA polymer, adjusting glass transition temperature through plasticizer content, and optimizing molecular weight parameters. These parameter changes enable simultaneous achievement of low noise and ease of manufacture.
2Strength
If plasticizers are added to improve flexibility, then mechanical properties are enhanced, but plasticizer migration occurs
Solution Approach 1:
The patent optimizes plasticizer content within specific ranges (1-20 wt% of total composition) and selects plasticizers with appropriate molecular weights and chemical structures. This parameter optimization ensures sufficient flexibility enhancement while minimizing plasticizer migration by maintaining proper plasticizer-polymer interactions.
Solution Approach 2:
The patent uses small amounts of plasticizer as a temporary additive that performs its function during processing and initial use, then gradually degrades or becomes immobilized in the matrix, preventing long-term migration issues.
3Illumination intensity
If film thickness is reduced to improve optical clarity, then haze decreases, but mechanical strength is compromised
Solution Approach 1:
The patent employs a composite of semicrystalline and amorphous PLA polymers where the semicrystalline phase provides mechanical reinforcement at thin film thicknesses while the amorphous phase maintains optical clarity. This composite structure allows thin films to achieve both low haze and adequate mechanical strength.
Solution Approach 2:
The patent creates local structural differences through the semicrystalline/amorphous blend, where crystalline regions provide localized mechanical strength and amorphous regions provide localized optical transparency, allowing the film as a whole to achieve both low haze and sufficient strength at reduced thickness.
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 solution results in films with reduced noise, enhanced thermal stability, and improved mechanical properties, such as increased tensile strength and elongation, while maintaining low haze and preventing plasticizer migration.
Implementation Method 1
polymer having a midpoint Tg as measured by differential scanning calorimetry of at least 25° C., and plasticizer; wherein the mixture exhibits a single midpoint Tg and the single midpoint Tg ranges from 40° C. to 65° C.
Implementation Method 2
wherein the film is oriented and the oriented film exhibits a higher midpoint Tg ranging from 40° C. to 65° C. and a lower midpoint Tg ranging from 5 to 25° C.
Data Source
AI summary
In one embodiment, a film is described comprising a mixture of semicrystalline polylactic acid polymer; polyvinyl acetate polymer having a glass transition temperature (Tg) midpoint as measured by differential scanning calorimetry of at least 25° C.; and plasticizer; wherein the film is oriented. In another embodiment, a film is described comprising a mixture comprising semicrystalline polylactic acid polymer, polymer having a midpoint Tg as measured by differential scanning calorimetry of at least 25° C., and plasticizer; wherein the mixture exhibits a single midpoint Tg and the single midpoint Tg ranges from 40° C. to 65° C.; and wherein the film is oriented and the oriented film exhibits a higher midpoint Tg ranging from 40° C. to 65° C. and a lower midpoint Tg ranging from 5 to 25° C.