Cavitated Polymeric Films with Microporous Core and Skin Layers
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Solution Overview
Problem
Existing polymeric films lack efficient methods for creating multi-layer structures with a microporous breathable core layer and non-breathable skin layers, which are essential for various applications, including personal hygiene products, where breathability and barrier properties are crucial.
Innovation Solution
A manufacturing process involving the extrusion of a molten web, followed by casting and stretching to form a multi-layer film with a cavitated core layer and non-cavitated skin layers, utilizing thermoplastic polymers and solid fillers to create a microporous structure that allows water vapor passage while blocking liquid water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer structure with microporous core layer and non-breathable skin layers is created, then breathability and barrier properties are improved, but manufacturing complexity increases
Solution Approach 1:
The film is divided into multiple layers with distinct functions: microporous core layers for breathability and non-breathable skin layers for barrier properties. Each layer can be independently optimized and manufactured, then combined into the final multi-layer structure, resolving the contradiction by making complexity manageable through modular design
Solution Approach 2:
The invention uses composite material structures combining different polymer layers with distinct properties (microporous vs. non-breathable) to achieve both breathability and barrier functionality simultaneously. The composite structure allows each material to contribute its specialized properties without requiring the entire film to have uniform characteristics
2Reliability
If solid fillers are used to create microporous structure, then breathability is improved, but manufacturing precision requirements increase
Solution Approach 1:
Solid fillers are incorporated into the polymer matrix to create controlled microporous structures. The fillers act as pore-forming agents that, when removed or distributed throughout the matrix, create channels for vapor transmission. This approach achieves breathability through material selection rather than complex processing precision
Solution Approach 2:
The invention controls micropore characteristics by adjusting processing parameters such as filler concentration, extrusion temperature, and stretching ratios. By changing these parameters, the micropore size, distribution, and connectivity can be optimized for breathability without requiring extreme manufacturing precision
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
The process results in films with improved tensile strength, reduced basis weight, and enhanced breathability, making them suitable for applications requiring both moisture barrier and vapor transmission properties.
Implementation Method 1
casting the molten web to form a quenched film by casting the molten web against a surface of a chill roll using a vacuum box and/or blowing air
Implementation Method 2
casting the molten web to form a quenched film by casting the molten web against a surface of a chill roll
Implementation Method 3
stretching the quenched film to form the microporous breathable film
Implementation Method 4
a microporous core layer formed from polymeric material and filler
Data Source
AI summary
Multi-layer films include at least one cavitated core layer that is microporous and breathable, and at least one skin layer. The cavitated core layer includes a polyolefin and an inorganic filler dispersed in the polyolefin. Methods for forming polymeric films and articles of manufacture prepared therefrom are described.