Solventless-Adhesive Multilayer Films for Bubble and Winding Control
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Solution Overview
Problem
Multilayer films using solventless adhesives are prone to air bubble generation and winding misalignment due to positional misalignment during the curing process of the adhesive layer, especially in films with multiple layers or vapor deposition layers.
Innovation Solution
A multilayer film structure using a solventless adhesive composed of a polyester-based resin and an aliphatic isocyanate curing agent with a viscosity of 600 to 1400 mPa·s at 80°C, applied at 0.5 to 3.0 g/m², and a production method involving controlled lamination under pressure to suppress air bubble generation and winding misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solventless adhesive with low viscosity is used to improve ease of application, then air bubbles are generated in the adhesive layer causing appearance defects
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the solventless adhesive within the range of 300-900 mPa·s at 70°C (or 600-1400 mPa·s at 80°C). This optimized viscosity parameter enables the adhesive to flow adequately for application while maintaining sufficient body to prevent air bubble entrapment, thus resolving the contradiction between ease of application and appearance quality.
2Productivity
If the multilayer film is wound immediately after lamination to improve productivity, then winding misalignment occurs due to positional misalignment during curing
Solution Approach 1:
The patent applies preliminary action by formulating the solventless adhesive with optimized viscosity characteristics before application. This ensures that the adhesive maintains stable positioning properties during the curing period, allowing the multilayer film to be wound immediately after lamination without experiencing winding misalignment, thus enabling high productivity while maintaining precision.
3Object-affected harmful factors
If a solventless adhesive is used to reduce environmental impact, then air bubble generation and winding misalignment occur during the curing process
Solution Approach 1:
The patent resolves this contradiction by changing the viscosity parameter of the solventless adhesive to a specific range (300-900 mPa·s at 70°C or 600-1400 mPa·s at 80°C). This parameter optimization allows the adhesive to exhibit both good wetting properties for complete coverage and sufficient viscosity to prevent air bubble entrapment and positioning shifts during curing, thereby maintaining lamination quality while preserving the environmental benefits of solventless formulation.
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 effectively suppresses air bubble formation and winding misalignment in the multilayer film, ensuring a stable lamination process and improved impact resistance.
Implementation Method 1
the solventless adhesive contains a main agent made of a polyester-based resin and a curing agent made of an aliphatic isocyanate
Data Source
AI summary
Provided are a multilayer film capable of suppressing generation of air bubbles in an adhesive layer and suppressing occurrence of winding misalignment when wound immediately after lamination, a method for producing the multilayer film, and a packaging container using the multilayer film. The multilayer film of the disclosure is a multilayer film including a plurality of resin films and one or more adhesive layers, and is characterized that at least one of the adhesive layers is formed of a solventless adhesive; and the solventless adhesive contains a main agent made of a polyester-based resin and a curing agent made of an aliphatic isocyanate, and a viscosity of the solventless adhesive at 80° C. is from 650 to 1600 mPa·s.