Hot Melt Adhesive Composition for Plastic Container Bonding
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Solution Overview
Problem
Existing hot melt adhesive compositions face challenges in simultaneously providing a reliable bond between plastic containers while ensuring easy separation, especially for PET bottles, and must be removable without leaving residue for recycling.
Innovation Solution
A hot melt adhesive composition comprising more than 25 weight percent of a block copolymer, 20 to 50 weight percent of a plasticizer, 18 to 55 weight percent of a combination of two different resins, and optionally up to 10 weight percent of wax, specifically designed to balance cohesive strength and ease of separation, with a preferred composition of styrene-ethylene-butylene-styrene (SEBS) block copolymer, paraffinic mineral oil, aromatic and aliphatic hydrocarbon resins, and a wax.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a higher adhesive force is used to provide a reliable bond between containers, then bond strength is improved, but ease of separation deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the composition ratios of block copolymer (25-50 wt%), plasticizer (20-50 wt%), and resins (18-55 wt%) to achieve optimal balance between bond strength and ease of separation. The specific parameter ranges were determined through experimentation to provide both reliable bonding and consumer-friendly separation without requiring excessive force
Solution Approach 2:
The patent uses composite materials by combining multiple components with complementary functions: block copolymer provides cohesive strength and elasticity, plasticizer ensures flexibility and low-temperature performance, and resins enhance adhesion to plastic substrates. This composite formulation achieves both strong bonding and easy separation properties that individual materials cannot provide alone
2Reliability
If a stronger bond is applied to ensure reliable bonding of containers, then bond reliability is improved, but residue left after separation increases
Solution Approach 1:
The patent applies parameter changes by optimizing the plasticizer content (20-50 wt%) and resin composition to ensure the adhesive remains flexible and does not degrade or leave residue upon separation. The specific compositional parameters were tuned to maintain bond reliability while enabling clean separation suitable for recycling processes
Solution Approach 2:
The patent applies this principle by designing an adhesive that fulfills its bonding function temporarily during packaging and distribution, then allows easy removal without residue for the disposable/recyclable container. The adhesive is formulated to be effective during its service life but easily removable when no longer needed
3Ease of operation
If the adhesive composition is optimized for easy separation, then ease of separation is improved, but bond strength deteriorates
Solution Approach 1:
The patent resolves this contradiction through precise parameter optimization of the compositional ratios. The block copolymer content (25-50 wt%) provides sufficient cohesive strength, while the plasticizer (20-50 wt%) and resin (18-55 wt%) content are balanced to enable easy separation. This specific parameter range achieves both strong bonding and consumer-friendly separation
4Reliability
If shrink wrap with LDPE films is used to bond packs, then packaging integrity is improved, but energy consumption and waste increase
Solution Approach 1:
The patent applies this principle by extracting and eliminating the energy-intensive shrink wrapping process entirely. Instead of using LDPE films that require heating tunnels for application, the invention uses hot melt adhesive that can be applied and set quickly without extensive heating, thereby removing the harmful energy consumption associated with traditional shrink wrapping
Solution Approach 2:
The patent replaces the thermal-mechanical shrink wrapping system with a simpler adhesive bonding system. Instead of using heat and mechanical compression through shrink films, the invention uses controlled application of hot melt adhesive that bonds containers through a simpler, less energy-intensive process
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 adhesive composition achieves excellent viscosity and color stability, high cohesive strength, low surface tack, improved adhesion to plastic substrates, and easy separation, maintaining bond integrity at various temperatures and during consumer use, while avoiding residue and energy consumption associated with shrink wrapping.
Implementation Method 1
The polymer provides the formulation with its strength and adhesive characteristics. Typically, a thermoplastic polymer is used. The thermoplastic polymer may be selected from homopolymers, copolymers (e.g. interpolymers) or block copolymers.
Implementation Method 2
The plasticizer also helps to lower viscosity and can additionally be used to impart permanent tack properties to the hot melt adhesive.
Implementation Method 3
The resin allows the thermoplastic polymer to be more adhesive by improving wetting during the application. Resins are added to give tack to the adhesive and also to lower viscosity.
Implementation Method 4
One function of the wax component is to lower the viscosity of the hot melt adhesive. Furthermore, due to the presence of the wax component, the hot melt adhesive crystallizes quickly which helps the material to harden or set quickly. Thus, the wax component also controls the open time and set speed of the system.
Data Source
AI summary
The present invention relates to a hot melt adhesive composition, comprising based on the total weight of the hot melt adhesive composition: (a) more than 25 weight percent of at least one block copolymer, (b) from about 27 to about 45 weight percent of at least one plasticizer, (c) from about 18 to less than about 55 weight percent of a combination of at least two different resins; and (d) optionally up to 10% weight percent of at least one wax. The hot melt adhesive composition of the invention can be used for bonding bundles of plastic containers such as bottles into packs.