Multi-layer Valve Bag with Offset Venting Perforations
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Solution Overview
Problem
Existing sacks with plastic and paper walls struggle to maintain a reliable moisture barrier while allowing ventilation during and after filling, especially when filled with sensitive materials, as previous solutions either compromise moisture protection or fail to adequately vent air.
Innovation Solution
The use of two plastic layers with offset ventilation perforations that adhere to each other at normal pressure, allowing air to escape under overpressure conditions, creating an airtight seal during rest and enabling ventilation by separating under pressure, with specific materials like low-density polyethylene providing enhanced adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a closed plastic wall is used to protect against moisture ingress, then moisture protection is improved, but air becomes enclosed during filling causing bloating and preventing compacting of filling material
Solution Approach 1:
The plastic wall is divided into multiple layers (first plastic layer and second plastic layer) with offset ventilation perforations in each layer. The perforations are arranged such that they do not align between layers, creating a segmented ventilation system that allows air escape while maintaining moisture barrier functionality.
Solution Approach 2:
The ventilation system is nested within the multi-layer plastic wall structure. The first and second plastic layers are attached to each other with their perforations offset, creating a nested configuration where ventilation channels are formed between the layers while the outer surface maintains moisture protection.
2Object-generated harmful factors
If ventilation perforations are provided in the plastic wall to allow air escape, then bloating is prevented, but the moisture barrier protection is compromised
Solution Approach 1:
The ventilation function is moved to a different dimension by creating offset perforations in multiple layers. Instead of having perforations in a single plane, the perforations are distributed across multiple layers at different positions, allowing air to escape through the thickness dimension while maintaining the barrier function in the lateral dimensions.
Solution Approach 2:
The plastic wall is constructed as a composite structure with multiple plastic layers, each having ventilation perforations. The combination of layers with offset perforations creates a composite material system that simultaneously provides both ventilation and moisture barrier properties that neither layer could achieve alone.
3Object-generated harmful factors
If previous ventilation solutions with interrupted seams or plastic strips are used, then air can escape, but the seal against moisture effects is not complete allowing long-term moisture damage
Solution Approach 1:
Different regions of the plastic wall have different properties: the outer surface maintains a continuous moisture barrier, while the internal multi-layer structure with offset perforations provides localized ventilation channels. This local differentiation allows simultaneous achievement of both functions.
Solution Approach 2:
The offset ventilation perforations act as an intermediary mechanism between the interior and exterior of the sack. They provide a controlled pathway for air escape that does not compromise the overall moisture barrier, serving as a mediator that reconciles the conflicting requirements of ventilation and moisture protection.
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 configuration ensures a reliable moisture barrier while allowing for compacting of filling materials by venting the sack, preventing bloating and ensuring the integrity of the filling material, even when filled with sensitive products.
Implementation Method 1
the layers are in contact with one another with surface adhesion, so that the plastic wall hermetically encloses the interior of the sack at normal pressure
Implementation Method 2
the layers are fixed to one another in such a way that they are in the area of the Perforations lift off from each other due to overprinting. Due to overpressure, especially inside the sack, the two layers of plastic can separate, allowing air to escape from the sack via the vent perforations
Data Source
Figure 1~2
Figure 3
AI summary
The bag has an outer wall, which is closed from a flat material into a tubular shape by a longitudinal seam, where the outer wall comprises a plastic wall (1) and a paper wall (8), and a bottom is folded at one end of the outer wall. The plastic wall is partially double-layered with two adjacent layers. The two layers have mutually displaced venting perforations and are fixed to each other such that the layers are lifted from each other in the area of perforations due to overpressure.