Alkali-Dispersible Hot Melt PSA for CO2-Resistant Bottle Labels
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Solution Overview
Problem
Existing hot melt pressure-sensitive adhesives (PSAs) used for beverage containers face issues with label lifting due to carbon dioxide expansion, inadequate adhesive strength, stringiness during application, and poor performance in alkaline solutions, leading to residue and reduced recyclability.
Innovation Solution
A hot melt PSA comprising a thermoplastic block copolymer, metallocene olefin polymer, tackifying resin, and fatty acids or derivatives, optimized for high alkali dispersibility, strong label-holding strength, reduced stringiness, and improved adhesive strength at film overlaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hot melt PSA is used to ensure strong label holding, then label adhesion is improved, but label lifting occurs due to carbon dioxide expansion in carbonated beverages
Solution Approach 1:
The patent modifies the chemical composition parameters of the hot melt PSA by incorporating specific ratios of styrene-based block copolymer (30-70 parts), metallocene olefin polymer (10-30 parts), and modified rosin (10-30 parts). This compositional parameter change enables the adhesive to maintain strong holding strength while achieving alkali dispersibility that prevents label lifting when exposed to carbon dioxide expansion and alkaline cleaning solutions.
Solution Approach 2:
The patent creates a composite hot melt PSA formulation by combining multiple polymer components with complementary properties: styrene-based block copolymer provides adhesive strength, metallocene olefin polymer enhances mechanical stability, and modified rosin contributes to alkali dispersibility. This composite material structure resolves the contradiction between strong holding and resistance to CO2-induced lifting.
2Strength
If hot melt PSA is heated to 120-190°C for application, then adhesion is improved, but stringiness is generated during coating
Solution Approach 1:
The patent adjusts the thermal and rheological parameters of the hot melt PSA by controlling the molecular weight and composition of the polymer components. The specific formulation with metallocene olefin polymer and modified rosin modifies the melt viscosity and surface tension at application temperatures (120-190°C), enabling smooth coating without stringiness while maintaining bonding strength.
3Ease of operation
If alkali-dispersible hot melt PSA is used for easy label removal, then re-peelability is improved, but adhesive strength is reduced
Solution Approach 1:
The patent optimizes the chemical composition parameters to achieve a balance between adhesion and dispersibility. By controlling the ratios of styrene-based block copolymer (30-70 parts), metallocene olefin polymer (10-30 parts), and modified rosin (10-30 parts), the formulation achieves sufficient holding strength for label application while maintaining alkali dispersibility for easy removal during recycling.
Solution Approach 2:
The patent applies different functional properties to different components of the adhesive system: the styrene-based block copolymer provides strong adhesion to the container, while the metallocene olefin polymer and modified rosin components provide alkali dispersibility for easy label removal. This local functional differentiation resolves the contradiction between strong adhesion and easy removal.
4Area of stationary object
If body-wrapping label is used for beverage containers, then labeling coverage is improved, but adhesive strength at film overlapping portions is insufficient during transportation
Solution Approach 1:
The patent modifies the adhesive formulation parameters by incorporating metallocene olefin polymer (10-30 parts) and modified rosin (10-30 parts) in addition to the styrene-based block copolymer. This compositional change enhances the adhesive strength specifically at overlapping portions of body-wrapping labels, preventing delamination during transportation while maintaining full label coverage.
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 PSA effectively prevents label lifting and residue, maintains adhesive strength during transportation, and ensures clean peeling in alkaline solutions, enhancing recyclability and reducing stringiness during application.
Implementation Method 1
a hot melt PSA which has high alkali dispersibility, and has excellent label-holding strength
Implementation Method 2
The hot melt PSA is heated to about 120 to 190° C. and applied to a label
Implementation Method 3
the labels to peel off from the containers in a short time by swelling, softening, dispersing, or being solubilized in the aqueous alkaline solution
Implementation Method 4
the labels to peel off from the containers in a short time by swelling, softening, dispersing, or being solubilized in the aqueous alkaline solution
Implementation Method 5
The hot melt PSA is heated to about 120 to 190° C. and applied to a label
Implementation Method 6
The hot melt PSA is heated to about 120 to 190° C. and applied to a label
Data Source
AI summary
There is provided an alkali dispersible-type hot melt pressure-sensitive adhesive, comprising:(A) a thermoplastic block copolymer that is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds,(B) a metallocene olefin polymer,(C) a tackifying resin, and(D) at least one selected from the group consisting of fatty acids and derivatives thereof.