Linerless Heat-Sealable Label Preventing Blocking
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Solution Overview
Problem
Conventional self-adhering labels with silicone-covered release liners face issues such as high weight, environmental complications, and complex handling processes, while linerless labels with silicone layers restrict printing possibilities and are prone to blocking due to the silicone layer's tackiness.
Innovation Solution
A linerless label with a heat-sealable adhesive layer composed of a dried dispersion of polymeric particles, where at least 10% of the particles have an average diameter of 0.5 µm and a coalescence temperature above 50°C, eliminating the need for an anti-adhesive silicone layer and spacer particles, allowing for a thinner label and more versatile printing options.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a silicone-covered release liner is used in self-adhering labels, then the label can be easily applied and removed, but the weight increases and environmental disposal becomes problematic
Solution Approach 1:
The invention extracts and removes the silicone release liner from the label structure, transitioning from traditional self-adhering labels with liners to linerless heat-sealable labels. This elimination of the liner component directly reduces label weight while maintaining functionality through alternative application methods.
Solution Approach 2:
The invention changes the adhesive activation parameter from pressure-sensitive (room temperature) to heat-sealable (elevated temperature). This parameter change enables the adhesive to function without requiring a release liner, as the heat-activated adhesive remains stable during storage and handling but bonds effectively when heated during application.
2Reliability
If a silicone layer is added to linerless labels to prevent blocking, then blocking during storage is reduced, but printing possibilities are restricted and the label becomes more prone to mirror effects
Solution Approach 1:
The invention changes the adhesive formulation parameters by using a heat-sealable adhesive with a defined coalescence temperature above 50°C. This parameter change allows the adhesive to maintain stability at room temperature without requiring a silicone layer, thereby preventing blocking while preserving printing versatility on the carrier layer surface.
Solution Approach 2:
The invention uses a composite adhesive system consisting of polymeric particles dispersed in a solvent or water, where the polymeric particles have specific coalescence properties. This composite material approach provides blocking prevention through controlled coalescence behavior without requiring an additional silicone layer that would restrict printing.
3Reliability
If spacer particles are incorporated in the adhesive layer to reduce blocking, then blocking and wrinkling are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The invention changes the adhesive formulation by using polymeric particles with controlled size distribution and coalescence temperature. This parameter change eliminates the need for additional spacer particles, as the polymeric particle system itself provides the necessary spacing and blocking prevention properties through its coalescence behavior during heat sealing.
Solution Approach 2:
The invention merges the functions of adhesive bonding and blocking prevention into a single polymeric particle-based adhesive layer. By combining these functions, the invention eliminates the need for separate spacer particles, thereby simplifying the manufacturing process while maintaining reliability.
4Strength
If the coalescence temperature of polymeric particles is lowered to improve adhesion, then bonding strength increases, but blocking during storage and handling increases
Solution Approach 1:
The invention optimizes the coalescence temperature parameter to a specific range above 50°C. This parameter optimization creates a temperature window where the adhesive remains stable and non-tacky during storage and handling (preventing blocking) but achieves effective bonding when heated during the labeling process (providing sufficient strength).
Solution Approach 2:
The invention creates a dynamic adhesive system where the adhesive properties change with temperature. At room temperature, the polymeric particles remain discrete and non-coalesced, providing stability and preventing blocking. During heat sealing, the particles coalesce to form a strong bond, demonstrating dynamic behavior that resolves the contradiction between strength and blocking prevention.
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 during storage and handling, enables advanced printing techniques, reduces material consumption, and provides a label that is less prone to mirror effects and electrostatic detachment, while maintaining adhesion properties without the need for additional anti-adhesive layers.
Implementation Method 1
said polymeric particles having a coalescence temperature at or above 50°C
Implementation Method 2
The dried dispersion provides a porous layer, in which the individual particles are connected with each other in such a way that voids are present between the particles
Data Source
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AI summary
The present invention relates to a heat-sealable label comprising a carrier layer, a print, and a heat- sealable adhesive layer, wherein the heat-sealable adhesive layer is a dried dispersion comprising polymeric particles having a coalescence temperature at or above 500C and at least 10 % (w/w) of the total mass of said polymeric particles are constituted by particles having an average particle diameter of at least about 0.5 µm. This particular adhesive layer results in absence of a tendency of the labels to block when winded up in a roll. Thus, a release layer may be omitted, which allows for a label with more versatile surface properties.