Polyamide-EAA Thermal Lamination Adhesive Coating
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Solution Overview
Problem
Current lamination adhesives, both solvent-based and water-based, face challenges in providing strong bond strength, especially when used on printed substrates, and require lengthy curing times, necessitating the need for improved coatings that can enhance laminating bond strength and reduce curing time.
Innovation Solution
An aqueous dispersion coating comprising a mixture of polyamide and ethylene acrylic acid copolymer, combined with an isocyanate crosslinker, is used as a water-based thermal lamination adhesive, which provides high bond strength and minimal use of non-aqueous plasticizers and organic solvents, allowing for rapid lamination without hazardous co-catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If solventless lamination adhesives are used, then environmental performance is improved, but curing time increases to three to five days
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by using a water-based polyamide dispersion with specific molecular weight (500-2000) and incorporating a polyurethane crosslinking system. This parameter modification enables the adhesive to cure rapidly (within minutes to hours) while maintaining water-based formulation, thus reducing both VOC content and curing time compared to conventional solventless adhesives
Solution Approach 2:
The patent creates a composite adhesive system combining polyamide dispersion, polyurethane crosslinker, and catalyst. This composite formulation synergistically achieves rapid curing through crosslinking chemistry while maintaining environmental benefits of water-based formulation, resolving the contradiction between low VOC and fast curing
2Object-affected harmful factors
If water-based laminating adhesives are used, then environmental performance is improved, but lamination bond strength decreases
Solution Approach 1:
The patent develops a composite water-based adhesive system combining polyamide dispersion with polyurethane crosslinker and catalyst. The crosslinking chemistry creates strong covalent bonds that significantly enhance lamination bond strength while maintaining the environmental benefits of water-based formulation, thus overcoming the weakness of conventional water-based adhesives
Solution Approach 2:
The patent modifies the chemical parameters by selecting polyamide with specific molecular weight (500-2000) and incorporating crosslinking agents. These parameter changes enable the water-based adhesive to achieve bond strengths comparable to or exceeding solvent-based systems, resolving the strength deficiency
3Strength
If conventional primers are used, then lamination strength is enhanced, but lamination bond strength becomes unacceptably low when printing substrates are laminated
Solution Approach 1:
The patent develops a universal adhesive formulation that directly adheres to printed substrates without requiring primer layers. The polyamide-polyurethane crosslinked system provides broad substrate compatibility including printed surfaces, eliminating the need for primers and enabling direct lamination of printed materials
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 coating achieves higher bond strength and faster lamination, reducing curing time and eliminating the need for hazardous co-catalysts, while maintaining stability and water resistance, making it suitable for various substrates including those printed with high-speed digital presses.
Implementation Method 1
an isocyanate crosslinker; wherein the lamination adhesive comprises less than 1 wt % of non-aqueous plasticizers and organic solvents
Implementation Method 2
heating the first substrate, the lamination adhesive coating, and the second substrate to achieve laminate adhesion between the first and second substrate
Data Source
AI summary
Lamination adhesives including an aqueous dispersion having a mixture of a polyamide and an ethylene acrylic acid copolymer are provided for use on a variety of substrates. In various embodiments, the aqueous dispersion is substantially free of plasticizers and non-aqueous organic solvents. Also provided is a method of forming a laminate adhesion between two substrates. The disclosure also describes a laminate structure comprising first and second substrates laminated together by the lamination adhesive, the lamination adhesive including a mixture of a polyamide and a copolymer of ethylene and acrylic acid.