Composite Film Sealing via PET Inner Layer Penetration
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Solution Overview
Problem
Existing composite films for tubular bag packs rely on polyethylene as the inner sealing layer, which is not suitable for packaging sensitive foods due to high migration capacity and limited weld seam strength, and cannot economically use polymers with higher melting points like polyamide or polyethylene terephthalate (PET) as inner layers.
Innovation Solution
A composite film design where polyethylene terephthalate (PET) is used as the inner layer with through openings, covered by a lower-melting-point polyethylene sealing layer, allowing the sealing layer to penetrate and form a strong connection, and optionally including a barrier layer to prevent UV entry, with specific layer thicknesses and opening arrangements for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyethylene (PE) is used as the inner sealing layer, then welding can be performed economically with sufficient weld seam strength, but the migration capacity is too high for packaging sensitive foodstuffs
Solution Approach 1:
The sealing system is divided into two separate layers: an inner layer (13) made of PET that contacts the foodstuff, and an outer sealing layer (12) made of PE that performs the welding function. This segmentation allows each layer to fulfill its specific function optimally - the PET layer provides low migration capacity while the PE layer provides economical and strong welding
Solution Approach 2:
The patent introduces a barrier layer (15) as an intermediary between the inner PET layer and the outer PE sealing layer. This barrier layer prevents direct contact between the PE and foodstuff, eliminating migration concerns while allowing the PE to perform its sealing function effectively
2Object-affected harmful factors
If polymers with higher melting point like polyamide (PA) or polyethylene terephthalate (PET) are used as the inner layer, then migration capacity is reduced for sensitive foodstuffs, but welding cannot be performed economically and weld seam strength is insufficient
Solution Approach 1:
The sealing system is divided into two separate layers: an inner layer (13) made of PET that contacts the foodstuff, and an outer sealing layer (12) made of PE that performs the welding function. This segmentation allows each layer to fulfill its specific function optimally - the PET layer provides low migration capacity while the PE layer provides economical and strong welding
Solution Approach 2:
The patent creates a composite film structure consisting of multiple layers with different material properties: the PET inner layer (13) provides chemical resistance and low migration, the PE sealing layer (12) provides weldability and strength, and optionally a barrier layer (15) provides additional protection. This composite structure combines the advantages of different materials to achieve overall performance that neither material could provide alone
3Adaptability or versatility
If a single layer with perforations is used for pressure equalization, then microwave heating is enabled, but the arrangement and number of perforations is insufficient to ensure tight sealing and prevent liquid or pasty content escape
Solution Approach 1:
The perforation system is segmented into two separate rows (17a, 17b) positioned at different locations within the sealing structure. This segmentation allows the perforations to serve dual functions: enabling pressure equalization during microwave heating while maintaining sealing integrity through the specific arrangement and overlap of the two rows
Solution Approach 2:
The patent applies different properties to different regions of the sealing structure: the first row of perforations (17a) is positioned to facilitate pressure equalization, while the second row of perforations (17b) is positioned to ensure sealing tightness. The strip-shaped zone without through openings provides localized reinforcement for maintaining seal integrity
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
Enables the use of PET as an inner layer for sensitive foods with low migration capacity and strong, reliable sealing, preventing liquid or pasty content escape and extending food shelf life.
Implementation Method 1
the sealing layer is melted, the material of the sealing layer penetrates through the passage opening in the PET inner layer and comes into operative connection with the sealing layer on the opposite side
Implementation Method 2
heat and pressure welding the edge areas on the sealing layers of the composite film that are placed against one another
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a composite film (10), in particular for packaging (1) in the food industry, having at least one sealing layer (12), which consists of sealable material and is connected, at least indirectly, to a first layer (11) which acts as an outer layer, wherein the sealing layer (12) has a lower melting point than the first layer (11). According to the invention, it is provided that, on that side of the sealing layer (12) which is directed away from the first layer (11), a second layer (13), which acts as an inner layer, is arranged in operative connection with the sealing layer (12), that the second layer (13) has a higher melting point than the sealing layer (12), and that the second layer (13) has at least one through-opening (17; 17a to 17c), which is covered over by the sealing layer (12).