Fibrillated Polyolefin Foam Morphology for Absorbent Articles
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Solution Overview
Problem
Existing absorbent foams for personal care products face challenges such as low fluid absorption rates, inconsistent foam collapse during drying, and retention of fluid due to capillary forces, which affect their performance in absorbency and stability.
Innovation Solution
A method for generating thermoplastic foams with a non-cellular fibrillated morphology from aqueous dispersions containing polyolefin particles and fibers, which involves adding a froth stabilizing surfactant and fibers to the dispersion, followed by frothing and drying to create a foam with a density of 0.02-0.07 g/cm³, enhancing absorption rates and reducing capillary retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional frothing process is used to create open cellular foam, then foam structure is formed with interconnected pores, but fluid absorption speed is limited due to capillary pressure retention
Solution Approach 1:
The patent changes the fundamental morphological parameter of the foam from cellular to fibrillated. By creating a non-cellular structure with random fibrils and macropores instead of interconnected cells, the capillary pressure that retains fluid in traditional foams is eliminated, allowing faster fluid absorption while maintaining high void volume
Solution Approach 2:
The patent utilizes a porous fibrillated structure with macropores created by removing liquid phase during drying. This porous morphology provides high void volume for fluid storage while the larger pore sizes reduce capillary retention forces, enabling both high absorption speed and high absorption capacity
2Stability of the object's composition
If fiber-laden foams are used to reduce foam collapse during drying, then structural stability is improved, but foam morphology becomes difficult to control
Solution Approach 1:
The patent changes the foam morphology parameter from cellular to fibrillated, which inherently provides structural stability during drying. The fibrillated structure with random fibrils and macropores maintains its form better during the drying process while the morphology is controlled by the frothing process parameters rather than fiber content
Solution Approach 2:
The patent uses a surfactant as an intermediary to control foam formation and stability. The surfactant mediates the frothing process to create a stable fibrillated structure during drying, providing both morphological control and structural stability without requiring high fiber content
3Quantity of substance
If high void volume is achieved in absorbent materials, then fluid absorption capacity is improved, but wet resiliency and structural stability deteriorate
Solution Approach 1:
The patent changes the structural parameter from cellular to fibrillated morphology. This fibrillated structure with random fibrils maintains high void volume for fluid absorption while providing structural integrity and wet resiliency, as the fibrillar network can maintain its form when wetted unlike traditional cellular foams
Solution Approach 2:
The patent creates a composite structure combining polymer matrix with fibrillated morphology. This composite structure provides both the high void volume needed for fluid absorption and the structural strength for wet resiliency, as the fibrillar network reinforces the material while maintaining porosity
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a~4b
AI summary
A method for generating a thermoplastic foam from an aqueous dispersion, the aqueous dispersion comprising a thermoplastic resin, water, and a dispersion stabilizing agent, the method including: adding at least one froth stabilizing surfactant to the aqueous dispersion to form a mixture; adding a fiber to the mixture; and frothing the mixture to create a froth, removing at least a portion of the water in the froth to create a foam, wherein the foam generated has a non-cellular fibrillated morphology. In another aspect, embodiments disclosed herein relate to a foam having a thermoplastic-based, fibrillated, non-cellular structure, wherein the foam has an average density of about 0.02 g/cm3 to about 0.07 g/cm3. In certain embodiments, the foam may be used in an absorbent article.