Polyester-Based Shrink Film for Impact Resistance and Uniform Shrinkage
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Solution Overview
Problem
Conventional polyester-based and polyolefin-based shrink films suffer from issues such as low impact resistance, high production costs, large variations in shrinkage ratios near the shrinking temperature, and insufficient transparency, which affect their suitability for high-speed automatic packaging and printing applications.
Innovation Solution
A polyester-based shrink film with specific impact resistance strength (A1) and shrinkage ratio (B1/B2) ranges, controlled by limiting A2/A1×100 and B1/B2×100 within predetermined values, ensuring stable and uniform shrinkage near the shrinking temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin-based shrink film is used for low cost and easy disposal, then production cost is reduced, but impact resistance and transparency are insufficient
Solution Approach 1:
The patent uses a multilayer composite structure combining polyolefin layers (for cost-effectiveness and disposal ease) with polyester layers (for impact resistance and transparency). Specifically, it employs a structure with outer polyolefin layers and inner polyester layers, creating a composite material that integrates the advantages of both resin types to achieve both low cost and high impact resistance.
2Adaptability or versatility
If polyester-based shrink film with lactic acid structural units is used for biodegradability, then environmental friendliness is improved, but production cost increases and shrinkage ratio varies significantly
Solution Approach 1:
The patent applies local quality by incorporating biodegradable polyester layers only in specific positions (inner layers) where biodegradability is needed, while outer layers use cost-effective polyolefin materials. This localized application of biodegradable material achieves environmental friendliness without requiring the entire film to be made from expensive biodegradable resin, thus controlling production costs.
3Productivity
If shrinkage ratio near shrinking temperature is increased for labeling effect, then labeling effectiveness is improved, but shrinkage ratio variation increases causing instability
Solution Approach 1:
The patent controls the shrinkage characteristics by adjusting the molecular weight and composition of the polyester resin, and by optimizing the stretching conditions during manufacturing. Specifically, it uses polyester resin with weight average molecular weight of 50,000-200,000 and controls the stretch ratio to 3-6 times in the machine direction and 2-4 times in the transverse direction, achieving a shrinkage ratio of 40-80% at 90-110°C with minimal variation.
4Device complexity
If polyolefin-based multilayer shrink film is used for basic shrinkage function, then manufacturing simplicity is maintained, but tear strength decreases causing ripping at air vent pinholes
Solution Approach 1:
The patent enhances tear strength by incorporating polyester layers within the multilayer polyolefin structure. The polyester layers, positioned internally, provide reinforcement that prevents ripping at stress concentration points such as air vent pinholes, while the overall multilayer structure remains relatively simple and manufacturable.
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 film achieves excellent impact resistance and uniform shrinkage ratios, enhancing high-speed packaging suitability and reducing the likelihood of ripping, while maintaining transparency and mechanical strength.
Implementation Method 1
a 1% shrinkage initiation temperature of 35° C. to 80° C., an impact resistance strength of 6 kgf·cm or greater as measured in a film impact test of the film, and a maximum shrinkage ratio in the stretching direction of 35% to 90%
Data Source
AI summary
Provided is a polyester-based shrink film having excellent predetermined impact resistance and having a uniform shrinkage ratio near the shrinking temperature.