Fluid Activatable Adhesive for Liner-Free Labels
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Solution Overview
Problem
Existing liner-free label technologies face challenges with adhesion to polymeric substrates, requiring non-stick coatings that increase costs and generate waste, and often result in 'swimming' issues due to lack of rapid bond formation.
Innovation Solution
Development of fluid activatable adhesive compositions comprising hydrophilic and hydrophobic polymers with hygroscopic particulate fillers, which transition from a non-tacky to tacky state upon solvent exposure, enabling strong adhesion to various substrates including polymeric ones without the need for non-stick coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymeric adhesive compositions with pressure-sensitive adhesives are used in liner-free label constructions, then the adhesive provides constant tackiness, but the adhesive causes machine problems by gumming up label application systems and creates cleanup issues
Solution Approach 1:
The adhesive composition transitions from a non-tacky state to a tacky state dynamically. The adhesive layer is initially non-tacky to prevent gumming of equipment, then becomes tacky upon contact with moisture from the substrate or environment, enabling bonding without requiring constant tackiness that causes machine problems
Solution Approach 2:
The adhesive properties change based on moisture content. The composition includes polymers and plasticizers that modify the adhesive's tackiness parameter in response to environmental moisture, allowing it to be non-tacky during handling and tacky during application
2Object-affected harmful factors
If a non-stick liner layer is used over the adhesive composition layer, then the adhesive is protected from contacting equipment components, but the liner layer creates waste disposal issues and increases costs
Solution Approach 1:
The invention extracts and eliminates the non-stick liner layer from the label construction. By making the adhesive itself non-tacky when dry and tacky only when activated, the protective liner becomes unnecessary, eliminating waste disposal issues and reducing material costs
Solution Approach 2:
The adhesive composition provides its own protection service by being non-tacky in its dormant state, eliminating the need for an external liner layer to protect the adhesive from equipment contact
3Ease of operation
If conventional water or solvent activated adhesives are used, then the adhesive can be activated prior to application, but these adhesives lack strong adhesion on polymeric substrates and are prone to swimming
Solution Approach 1:
The adhesive composition uses a composite system combining specific polymers (styrene-acrylic copolymer, carboxylated styrene-butadiene copolymer) with plasticizers and hygroscopic fillers. This composite formulation provides both rapid activation upon moisture contact and strong adhesion to polymeric substrates, preventing swimming while maintaining ease of operation
Solution Approach 2:
The inclusion of hygroscopic fillers creates a porous structure that rapidly absorbs moisture from the environment or substrate, enabling quick activation of the adhesive without causing excessive water migration that would lead to swimming
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 provides quick tack and strong adhesion to a wide range of substrates, reducing waste and energy consumption, and preventing 'swimming' issues, while maintaining label quality and efficiency in labeling processes.
Implementation Method 1
The more hydrophilic polymer provides quick tack upon contact with water or other aqueous solvent
Implementation Method 2
The more hydrophilic polymer provides quick tack upon contact with water or other aqueous solvent
Implementation Method 3
The less hydrophilic polymer provides strong adhesion to paper or polymeric substrate
Implementation Method 4
The adhesive composition may contain hygroscopic particulate fillers which enable fast exhaustion of the activation fluid out of the adhesive when applied to a substrate
Data Source
AI summary
Fluid activatable adhesive compositions and activating fluid(s) for activating the adhesive composition are described herein. The adhesive compositions contain at least two polymers with different hydrophilicities. The hydrophilic polymer has quick tack when exposed to a hydrophilic solvent, such as water or other aqueous solvent, while the hydrophobic polymer provides strong adhesion to a paper or polymeric substrate. The adhesive composition may contain particulate fillers which enable fast exhaustion of the activation fluid out of the adhesive when applied to a substrate, thereby allowing the hydrophobic polymers of the adhesive composition to achieve strong adhesion of the liner-free label to the paper or polymeric substrate. The particulate fillers may also function as anti-blocking agents when liner-free label media are tightly wound in a roll. The adhesive compositions described herein may be used not only on paper, cardboard, and metal, but also on glass and plastics commonly used in commercial applications.