Multilayer Label Facestock Stiffness and Gloss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pressure-sensitive adhesive labelstocks face challenges with dispensability due to insufficient stiffness, leading to label failure during application, and exhibit poor optical properties and print aesthetics, particularly with polypropylene-based films that are not conformable or easily printable with UV inks.
Innovation Solution
A machine-direction oriented multilayer film structure with a core layer and two skin layers, where the skin layers have low surface roughness and comprise a blend of polypropylene and polyethylene, achieving high gloss and clarity without the need for top-coatings, and ensuring sufficient stiffness for high-speed dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polypropylene-based films are used for label facestock, then stiffness is improved for dispensing, but conformability deteriorates for contoured substrates
Solution Approach 1:
The film is segmented into multiple layers with different functions: a polypropylene core layer provides stiffness for dispensing, while outer skin layers provide conformability for application to contoured substrates. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The invention uses a composite multilayer structure combining polypropylene (for stiffness) with other polymer materials (for conformability). This composite approach integrates the advantageous properties of different materials to simultaneously achieve both stiffness and conformability.
2Strength
If polypropylene-based films are used, then stiffness is improved, but printability with UV inks deteriorates
Solution Approach 1:
Different layers of the film have different surface qualities optimized for their specific functions. The outer skin layers possess surface properties that are highly receptive to UV ink printing, while the inner polypropylene core maintains stiffness. This local differentiation of properties solves the printability problem without sacrificing structural integrity.
3Quantity of substance
If films are down-gauged to reduce cost, then cost performance is improved, but stiffness deteriorates for dispensing
Solution Approach 1:
The multilayer composite structure allows the use of thinner overall film gauge while maintaining adequate stiffness through the polypropylene core layer. The optimized layer composition and thickness distribution provide sufficient mechanical strength for high-speed dispensing even at reduced overall film thickness.
Solution Approach 2:
The invention changes the material composition parameters and layer structure parameters to achieve the desired stiffness-to-thickness ratio. By selecting appropriate polymer combinations and layer thicknesses, the film achieves adequate stiffness at lower overall gauge for cost performance.
4Strength
If PP-PE blended films are stretched for orientation, then stiffness is improved, but surface roughness increases reducing optical properties
Solution Approach 1:
The film structure segments the stiffness-providing function (achieved through stretching of the polypropylene core layer) from the optical appearance function (maintained by the unstretched or less-stretched skin layers). This segmentation allows the stretched core to provide stiffness while the outer layers maintain smooth surfaces for good optical properties.
Solution Approach 2:
Different regions of the film have different degrees of stretching and surface roughness. The core layer is stretched to provide stiffness, while the outer skin layers are formulated or processed to maintain low surface roughness and high optical clarity, creating local quality differentiation.
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 multilayer film structure enhances dispensability, optical clarity, and print aesthetics, providing high gloss and transmittance while maintaining stiffness for conformable application on contoured substrates without additional coatings.
Implementation Method 1
the skin layers have low surface roughness, which increases gloss and transmittance of the film structure
Implementation Method 2
increases gloss and transmittance of the film structure
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
Machine direction oriented coextruded multilayer film structures for use as labelstock and die cut adhesive labels are described. The labelstocks comprise extruded machine direction oriented multilayer films and an adhesive layer. The multilayer film structures include skin layers made from a mixture of 70% to about 99.9% by weight of at least one propylene polymer, and from about 0.1% to about 20% by weight of at least one ethylene polymer, or from about 0.1% to about 25% by weight of at least one propylene polymer, and from about 75% to about 99.9% by weight of at least one ethylene polymer. The coextruded multilayer films are stretch oriented in the machine direction at a temperature at about or above the melting temperature of the polyethylenes and optionally include an adhesive layer and release liner.