Reclosable Laminate Adhesive Application Process
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Solution Overview
Problem
Existing methods for producing reclosable laminates are time-consuming and costly due to the need for drying water-based adhesives and require additional processing steps, leading to material limitations and increased production time, as well as issues with delamination and cracking.
Innovation Solution
The method involves applying a hot melt pressure-sensitive adhesive directly to a base layer using a heated applicator nozzle or roller, followed by coextrusion of a welding layer, allowing for a single-step process that reduces drying time and material limitations, while ensuring proper adhesion and preventing cracking through precise adhesive distribution and a suitable shear rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-based adhesive is used and drying is required before next process, then adhesive application is achieved, but production time increases and process becomes cumbersome
Solution Approach 1:
The patent changes the physical state parameter of the adhesive from water-based (requiring drying) to hot melt adhesive (applied in molten state and cooled). This parameter change eliminates the drying step entirely, as the adhesive sets upon cooling, enabling continuous production without time-consuming drying periods between adhesive application and subsequent lamination steps.
2Ease of manufacture
If blowing extrusion method is used with multilayer extruder, then laminate production is achieved, but production speed decreases due to additional working processes
Solution Approach 1:
The patent merges multiple separate manufacturing steps into a single integrated process. Instead of extruding the base film, then separately extruding the reclosure layer with adhesive, and finally laminating them, the invention uses a single extrusion process that simultaneously produces the base film, applies the hot melt adhesive, and forms the reclosure layer in one continuous operation, thereby dramatically increasing production speed.
3Adaptability or versatility
If polyethylene is used in sealant layer instead of polypropylene, then material selection flexibility increases, but delamination and cracking occur between PSA layer and sealant layer
Solution Approach 1:
The patent changes the temperature parameter during adhesive application and bonding. By using hot melt adhesive applied at elevated temperatures and controlling the cooling process, the invention ensures proper adhesion between the adhesive layer and the polyethylene sealant layer. The thermal parameters enable the adhesive to properly bond to polyethylene without causing delamination or cracking, thus maintaining reliability while allowing material versatility.
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 approach simplifies the production of reclosable laminates, reducing costs and time by enabling quick cooling and reactivation of the adhesive, allowing for uniform application and improved adhesion, thus eliminating cracking and delamination issues, and enabling the laminate to be used with a wider range of packaging materials.
Implementation Method 1
applying a hot melt pressure-sensitive adhesive directly to a base layer using a heated applicator nozzle or roller
Implementation Method 2
the adhesive is cooled more quickly and sufficiently for a cover layer to be applied
Implementation Method 3
applying a hot melt pressure-sensitive adhesive directly to a base layer using a heated applicator nozzle or roller
Data Source
Figure 1~3
Figure 4
AI summary
A laminate for use in packages comprising a base layer (3), a welding layer (1), and an adhesive layer (2) sandwiched there between. The adhesive layer (2) is a hot melt or a pressure sensitive adhesive (PSA) having a shear rate of 10-150 minutes at 40 °C using a load of 1000 g at 40 °C in a test area of 12.5 mm x 25 mm. The welding layer (1) comprises a layer of a polyethylene (PE) copolymer, and optionally an additional layer of PET, PE, such as low density polyethylene (LDPE) and/or PP. By the method of making a laminate, it is possible to apply to a base layer (3), an adhesive layer (2) of hot melt/PSA and subsequently a welding layer (1) in one and the same working process in order to form a reclosable laminate (9). This laminate (9) may serve as a reclosable lid on e.g. a package tray (4, 5). The laminate exhibits a reduced risk of formation of cracks or so-called piping in the laminate. Use of the laminate is also disclosed.