Laminated Wrap Film Preventing Blocking and Adhesion Loss
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Solution Overview
Problem
Conventional wrap films using lactic acid-based polymers face issues such as blocking, reduction in molecular weight due to hydrolysis, and poor adhesion to containers, especially under low-temperature conditions, and struggle to maintain transparency and cutting suitability.
Innovation Solution
A laminated film structure with surface layers and an intermediate layer comprising plant-derived polyethylene resin, aliphatic polyamide polymer, ethylene-vinyl alcohol copolymer, or polypropylene, which enhances adhesion, anti-fogging properties, and maintains elastic recovery and softness, while utilizing additives like anti-fogging agents and adhesives to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a plasticizer is compounded in the lactic acid-based polymer to reduce glass transition temperature, then the material becomes softer and more flexible, but the elastic modulus decreases and blocking occurs during rolling
Solution Approach 1:
The patent uses a laminated structure combining multiple materials: lactic acid-based polymer layers (for flexibility and biodegradability) with polyolefin layers (for strength and blocking prevention). This composite approach allows each layer to contribute its advantageous properties while compensating for the weaknesses of individual materials.
Solution Approach 2:
The patent controls the glass transition temperature of the lactic acid-based polymer within a specific range (-50°C to 0°C) and adjusts the thickness ratio between lactic acid and polyolefin layers to achieve the optimal balance between flexibility and elastic modulus, preventing blocking while maintaining ease of operation.
2Illumination intensity
If the lactic acid-based polymer is exposed to front and rear surfaces of the wrap film, then transparency is improved, but molecular weight reduces due to hydrolysis over time
Solution Approach 1:
The polyolefin layers serve as protective intermediary barriers between the lactic acid-based polymer and the external environment. These layers prevent moisture and catalysts from reaching the lactic acid polymer surfaces, thereby preventing hydrolysis and molecular weight reduction while allowing the lactic acid layers to maintain transparency.
Solution Approach 2:
The laminated composite structure with polyolefin outer layers protects the inner lactic acid-based polymer layers from environmental degradation, enabling the film to maintain both transparency and molecular weight stability over time.
3Reliability
If a laminated film structure is used to improve adhesion and prevent blocking, then manufacturing complexity increases
Solution Approach 1:
The patent applies different materials to different locations/layers of the film structure: polyolefin layers are placed at the outer surfaces (where adhesion and blocking resistance are critical) while lactic acid-based polymer layers are positioned internally (where transparency and biodegradability are prioritized). This localized material assignment optimizes performance while managing complexity.
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 prevents blocking and molecular weight reduction, maintains adhesion to containers under low-temperature conditions, and effectively utilizes renewable resources, enhancing the industrial value and environmental sustainability of the wrap film.
Implementation Method 1
a plant-derived polyethylene-based resin component (A), and which has a storage elastic modulus (E') at 20°C of 100 MPa to 4 GPa and an average loss tangent (tanδ) at -40 to 0°C of not less than 0.08
Implementation Method 2
an intermediate layer (B) comprising at least one type of polymer selected from an aliphatic polyamide polymer, an ethylene-vinyl alcohol copolymer and polypropylene
Data Source
AI summary
There is provided a packaging film that is free from occurrence of blocking upon storage, and deterioration in adhesion to containers even when used under low-temperature conditions, notwithstanding the film is produced while effectively utilizing exhaustible resources. A wrap film of the present invention comprises a laminated film constituted of at least three layers including opposite surface layers comprising a plant-derived polyethylene resin, in which the wrap film has a storage elastic modulus (E') at 20°C of 100 MPa to 4 GPa and an average loss tangent (tanδ) at -40 to 0°C of not less than 0.08 as measured at an oscillation frequency of 10 Hz and a distortion of 0.1% by a dynamic viscoelasticity measuring method described in the Method A of JIS K 7198.