Polyolefin Heat-Shrinkable Film with Polylactic Acid
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Solution Overview
Problem
Polyolefin series heat-shrinkable films face challenges with insufficient low-temperature heat-shrinkable properties and high natural shrinkage, leading to issues like wrinkles and deformation, making them unsuitable for diverse PET bottle shapes and storage conditions.
Innovation Solution
A polyolefin series heat-shrinkable film comprising a mixed resin of polyolefin, polylactic acid, and a compatibility-enhancing resin, with a mass ratio of 99/1 to 70/30, exhibiting a heat shrinkage ratio of 20% or more in one direction and natural shrinkage ratio of less than 10%, optimized with surface-and-backside layers and an adhesive layer for improved film rigidity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polyolefin series heat-shrinkable film is used, then wrinkle occurrence is reduced compared to polyester film, but low-temperature heat-shrinkable property is insufficient
Solution Approach 1:
The patent uses a composite resin composition consisting of polyolefin series resin (70-95 mass%), polylactic acid series resin (5-30 mass%), and hydrocarbon resin (0.1-10 mass%). This composite structure combines the wrinkle-resistant properties of polyolefin with the heat-shrinkable properties of polylactic acid, while hydrocarbon resin enhances low-temperature heat-shrinkability. The specific composition ratios are optimized to achieve both wrinkle reduction and sufficient low-temperature heat-shrinkable property.
2Ease of manufacture
If polyolefin series heat-shrinkable film is used, then ease of manufacture is improved, but natural shrinkage is high causing deformation and dimension changes
Solution Approach 1:
The patent employs a composite resin system where polylactic acid series resin (5-30 mass%) acts as a natural shrinkage control agent. The biodegradable polylactic acid component provides dimensional stability by reducing natural shrinkage during storage, while maintaining the ease of manufacture associated with polyolefin processing. The hydrocarbon resin (0.1-10 mass%) further stabilizes the composition by preventing deformation under various storage conditions.
3Reliability
If polyester series heat-shrinkable film is used, then heat-shrinkable property and shrink finishing quality are improved, but shrinkage spots and wrinkles occur during heat-shrinking
Solution Approach 1:
The patent creates a composite material that balances the heat-shrinkable properties of polyester with the wrinkle-resistant characteristics of polyolefin. The polyolefin series resin (70-95 mass%) provides wrinkle resistance, while polylactic acid series resin (5-30 mass%) and hydrocarbon resin (0.1-10 mass%) contribute to heat-shrinkable property. This composite approach achieves sufficient heat-shrinkable performance without the shrinkage spots and wrinkles typical of polyester films.
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 heat-shrinkable properties, low natural shrinkage, and superior shrink finishing quality, ensuring clear, wrinkle-free labels on containers with diverse shapes, even under storage and environmental changes.
Implementation Method 1
heat shrinkage ratio of the film at least in one direction when dipped in hot water at 80°C for 10 seconds is 20% or more
Data Source
AI summary
The present invention provides a polyolefin series heat-shrinkable film comprising a mixed resin mainly containing a polyolefin series resin (A), polylactic acid series resin (B), and a resin (C) facilitating compatibility with the resin (A) and the resin (B), or comprising at least one layer made of the mixed resin, wherein mass ratio of the resin (A) to the resin (B) is (A)/(B) = 99/1 to 70/30; heat shrinkage ratio of the film at least in one direction when dipped in hot water at 80°C for 10 seconds is 20% or more; and natural shrinkage ratio of the film when stored at 40°C under 50% RH environment for 7 days is less than 10%. This polyolefin series heat-shrinkable film exhibits excellent heat-shrinkable property and shrink finishing quality, and inhibits natural shrinkage. This invention also provides a polyolefin series heat-shrinkable label and container on which the heat-shrinkable label is fitted.