Disposable Heating Pad Outer Bag Gas Barrier Design
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Solution Overview
Problem
Existing outer bags for disposable body warmers face challenges in maintaining optimal gas barrier properties to prevent oxygen and water vapor permeation while allowing hydrogen gas escape, leading to swelling and reduced heat generation duration.
Innovation Solution
The outer bag is designed with a layered structure comprising a low air-permeability layer and an air-impermeable layer, with specific ratios and materials such as polyvinylidene chloride and vapor-deposited metal layers, to control oxygen and water vapor permeability while allowing hydrogen gas escape, ensuring seal strength and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas barrier property of the outer bag is made higher to inhibit permeation of oxygen gas and water vapor, then the gas barrier property is improved, but the hydrogen gas permeability is decreased, causing swelling during long storage period
Solution Approach 1:
The outer bag is divided into multiple functional layers: a gas barrier layer (with high oxygen and water vapor barrier properties) and a hydrogen gas permeable layer (allowing hydrogen gas to escape). This segmentation allows each layer to perform its specific function independently, resolving the contradiction between preventing oxygen/water vapor permeation and allowing hydrogen gas permeation.
Solution Approach 2:
The outer bag uses a composite structure combining materials with different gas permeability characteristics. The gas barrier layer uses materials like aluminum foil or vapor-deposited metal films for high oxygen and water vapor barrier properties, while the hydrogen gas permeable layer uses materials that are selectively permeable to hydrogen gas. This composite material approach enables simultaneous achievement of high gas barrier property and hydrogen gas permeability.
2Duration of action of moving object
If the gas barrier property is made higher to prevent oxygen and water vapor permeation, then the duration of heat generation is improved, but the swelling during storage worsens
Solution Approach 1:
The outer bag is segmented into distinct functional layers: one layer dedicated to blocking oxygen and water vapor (preserving heat generation duration) and another layer dedicated to allowing hydrogen gas escape (preventing swelling). This functional segmentation resolves the contradiction between maintaining heat generation duration and preventing shape distortion.
Solution Approach 2:
The patent employs composite materials with selective gas permeability properties. The gas barrier layer uses materials with high oxygen and water vapor barrier properties to maintain heat generation duration, while the hydrogen gas permeable layer uses materials that selectively allow hydrogen gas to pass through, preventing bag swelling. This composite approach simultaneously achieves both desired outcomes.
3Reliability
If the vapor-deposited layer is provided on the plastic film to improve gas barrier property, then the oxygen and water vapor permeation is reduced, but the hydrogen gas permeability is further decreased
Solution Approach 1:
The packaging structure is segmented into separate functional zones: a vapor-deposited layer (such as aluminum foil or metal film) that provides high oxygen and water vapor barrier properties, and a distinct hydrogen gas permeable layer that allows hydrogen gas to escape. This segmentation enables the vapor-deposited layer to fulfill its gas barrier function without compromising hydrogen gas permeability, as the latter is handled by the dedicated permeable layer.
Solution Approach 2:
The patent uses a composite structure combining a vapor-deposited layer (providing high oxygen and water vapor barrier properties) with a hydrogen gas permeable layer (allowing hydrogen gas to pass through). The vapor-deposited layer materials (such as aluminum foil, aluminum oxide, or other metal films) are combined with materials that are selectively permeable to hydrogen gas, enabling simultaneous achievement of high gas barrier property and hydrogen gas permeability.
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 achieves a balance in gas barrier properties, preventing swelling and degradation of the exothermic composition, allowing for long-term storage and effective heat generation without compromising seal strength or weatherability.
Implementation Method 1
an outer bag for disposable body warmer packaging has been proposed which includes a plastic film and a vapor-deposited layer obtained by vapor deposition of metal such as aluminum on the plastic film
Implementation Method 2
An outer bag for disposable body warmer packaging is required to be excellent in gas barrier property for inhibiting permeation of air, in particular, oxygen gas, water vapor, and the like
Implementation Method 3
A disposable body warmer is a body warmer that utilizes heat generation caused by the oxidation action of iron powders
Implementation Method 4
Two of such air-impermeable multilayer films are stacked each other and the peripheries of the sealant layers located inward are heat-sealed to each other into the form of a bag
Data Source
Figure 1A~1B(b)
Figure 1C
Figure 2A~2B(b)
AI summary
An outer bag for disposable body warmer packaging and a disposable body warmer are provided that are excellent in a gas barrier property that inhibits permeation of oxygen gas, water vapor, and the like, which can allow swelling due to hydrogen gas generated during a storage period to be prevented. Provided is an outer bag for disposable body warmer packaging having an accommodating potion accommodating a disposable body warmer accommodated in an air-permeable inner bag and generating heat through contact with air, the outer bag comprising a low air-permeability portion having an oxygen permeability of 1.5 to 20 cc/m2·day·atm measured at 20°C and 90% RH and having a water vapor permeability of 0.05 to 10 g/m2·day measured at 40°C and 90% RH; and an air-impermeable portion having an oxygen permeability of 1.3 cc/m2·day·atm or lower measured at 20°C and 90% RH and a water vapor permeability of 2.0 g/m2·day or lower measured at 40°C and 90% RH, wherein a ratio of an area of the low air-permeability portion to a total internal area of the accommodating portion is 15 to 75%.