Multilayer Dissolvable Sheet Composition for Stable Open-Cell Porosity

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Solution Overview

Problem

Existing manufacturing processes for flexible, porous, dissolvable solid sheets, particularly those containing alkyl alkoxy sulfates (AAS) and alkyl sulfates (AS), face challenges in achieving a desirable porous structure with uniform pore size and thickness, and are prone to issues like collapse, over-puffing, and delamination, especially in multilayer articles.

Innovation Solution

A flexible, porous, dissolvable solid sheet article comprising a stack of water-soluble sheets with specific ratios of C6-C20 linear or branched alkylalkoxy sulfates and alkyl sulfates, along with a water-soluble polymer, optimized for a continuous manufacturing process, ensuring a Percent Open Cell Content of 80% to 100% and Overall Average Pore Size of 100 μm to 2000 μm, and a weight ratio of AAS to AS from 0.4 to 3.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional drying processes are used for multilayer solid sheets, then manufacturing can be achieved, but the porous structure is compromised with high collapse percentage and poor pore uniformity

Engineering Contradiction:

Improveporous structure qualityVSAvoidstructural stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing the drying process parameters including temperature profile (from 60-80°C to 90-120°C), humidity levels, and drying time. It also modifies the formulation parameters such as the ratio of water-soluble polymer to surfactant, and the type of plasticizer used, to achieve a porous structure with 70-90% open cell content and uniform pore distribution while preventing collapse during drying.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining multiple water-soluble polymers (such as PVA, starch, cellulose derivatives) with specific surfactants (AAS and AS in controlled ratios) and plasticizers to create a multilayer solid sheet formulation that maintains structural integrity during drying and forms a stable porous structure. The composite formulation prevents collapse by balancing the mechanical strength from polymers with the porosity from surfactant-containing regions.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If multilayer solid sheet formulation is optimized for porosity, then open cell content increases, but delamination occurs during manufacturing

Engineering Contradiction:

Improveporosity uniformityVSAvoidlayer adhesion

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by adjusting the formulation parameters including the type and amount of water-soluble polymer, the ratio of surfactants (AAS to AS), and the plasticizer concentration. It optimizes the drying parameters such as temperature and humidity to form strong interlayer bonds while maintaining intra-layer porosity. The controlled evaporation rate and bonding conditions prevent delamination between layers while preserving the desired porous structure within each layer.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If continuous manufacturing process is implemented, then productivity increases, but manufacturing precision for porous structure becomes more difficult to control

Engineering Contradiction:

Improvemanufacturing rateVSAvoidpore size uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies continuity of useful action by implementing a continuous belt-drying process where the solid sheet undergoes consistent heating and drying conditions along the entire belt length. This continuous process maintains uniform temperature and humidity conditions, ensuring consistent pore formation throughout the sheet. The continuous operation eliminates batch-to-batch variations and maintains manufacturing precision for porous structure while achieving high productivity.

Inventive Principle:

Principle #20Continuity of useful action

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 solution provides a desirable porous structure compatible with continuous manufacturing, enhancing performance by preventing delamination and maintaining structural integrity while ensuring efficient dissolution in water.

Implementation Method 1

Flexible dissolvable solid sheets comprising surfactant(s) and/or other active ingredients in a water-soluble polymeric carrier or matrix are well known. Such sheets are particularly useful for delivering surfactants and/or other active ingredients upon dissolution in water.

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

a drying step is included in these manufacturing processes of such flexible dissolvable sheets to form a wet pre-mixture into the solid sheets. Such drying step is usually through heating under an appropriate condition.

Methodology Applied

Scientific EffectEvaporation: Evaporation