Label Laminate Drying via Metal Belt Segmentation
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Solution Overview
Problem
Plastic films used in label laminates tend to shrink or stretch during the manufacturing process due to temperature increases, making it difficult to use water-based adhesives with heat-sensitive plastics like polypropylene or polyethylene, as the drying process can cause dimensional changes exceeding 3% in the machine direction and 1% in the cross direction.
Innovation Solution
A metal belt with a release coating layer is used to dry the water-based adhesive layer separately before attaching it to the plastic film, utilizing induction heating, infrared heating, or microwave heating to prevent dimensional changes, and air jets to remove moisture, ensuring the adhesive is applied without causing shrinkage or stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water-based adhesive layer is dried using conventional heating methods during label laminate manufacturing, then the adhesive layer can be properly dried and activated, but the plastic film layer undergoes shrinkage and stretching causing dimensional changes exceeding 3% in machine direction and 1% in cross direction
Solution Approach 1:
The patent divides the drying process into two separate stages: first drying the adhesive layer on a belt before lamination, then activating it after lamination. This segmentation prevents the plastic film from being exposed to high temperatures during the drying process, thus avoiding dimensional changes while still achieving proper adhesive activation.
Solution Approach 2:
The adhesive layer is dried in advance on the belt before the lamination step. This preliminary drying action removes moisture from the adhesive without requiring the plastic film to be heated, since the adhesive is dried on the belt rather than being heated while still on the plastic film.
2Reliability
If temperature is increased during manufacturing process to dry water-based adhesive, then adhesive drying is achieved, but plastic film shrinkage and stretching occur
Solution Approach 1:
The process is segmented into separate steps: adhesive application on belt, adhesive drying on belt (without plastic film), lamination of adhesive to plastic film, and final activation. This segmentation allows adhesive drying at controlled temperatures without subjecting the plastic film to thermal stress that would cause shrinkage or stretching.
Solution Approach 2:
The belt serves as an intermediary carrier that allows the adhesive layer to be dried independently from the plastic film. The belt absorbs and distributes heat uniformly, enabling adhesive drying without direct thermal contact with the temperature-sensitive plastic film, thus maintaining dimensional stability.
3Productivity
If conventional drying methods are used for water-based adhesive on plastic film, then adhesive can be dried, but the process causes dimensional changes in the label laminate
Solution Approach 1:
The adhesive layer is dried in advance on the belt before lamination to the plastic film. This preliminary drying removes moisture efficiently without requiring the plastic film to be heated during the drying process, thus preventing dimensional changes while maintaining manufacturing efficiency through continuous belt processing.
Solution Approach 2:
The patent replaces conventional thermal drying methods with a belt-based drying system that uses controlled heat transfer through the belt. This substitution allows moisture removal from the adhesive layer without the mechanical stress and thermal shock that would cause dimensional changes in the plastic film, achieving both productivity and precision.
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
This method allows for the successful application of water-based adhesives to heat-sensitive plastics without significant dimensional changes, enabling the production of label laminates with improved stability and environmental friendliness, making them suitable for recyclable and reusable products like injection-molded plastic articles.
Implementation Method 1
heating the metal belt from the first side of the metal belt (i.e. underneath/from the belt side) by induction energy
Implementation Method 2
heating the metal belt, in addition to or instead of the above mentioned ways, from the second side of the metal belt (i.e. from the side where said at least one water based adhesion layer is placed), for example by infrared energy
Implementation Method 3
at least one microwave heating device may be used to heat said at least one water based adhesive layer
Implementation Method 4
air jets may be used to remove moisture from said at least one water based adhesive layer
Data Source
AI summary
The invention relates to a method for manufacturing a label laminate. The method includes forming at least one water based adhesive layer on a belt, drying said at least one water based adhesive layer on the belt, unwinding a first material layer, unwinding a second material layer, attaching said at least one dried water based adhesive layer to the surface of the first material layer, and laminating the first material layer comprising at least one water based adhesive layer together with the second material layer in order to form the label laminate. The invention also relates to a label laminate and to a system for manufacturing a label laminate.