Spunbonded Laminate Density Control via Layer Stacking

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Solution Overview

Problem

Existing spunbonded nonwoven laminates face challenges in achieving high thickness with low surface density while maintaining softness, strength, and dimensional stability, particularly in multibeam systems, where crimping often results in inhomogeneous deposition and increased material usage.

Innovation Solution

A method involving a laminate with at least two spunbonded nonwoven layers, one comprising crimped continuous bicomponent filaments with a polypropylene-based core-sheath configuration, where the sheath component has a lower melting temperature and higher melt-flow rate than the core, allowing for sufficient crimping and stable network formation, and the laminate is compacted using hot rollers and calender rollers to achieve a specific density below a defined limit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If crimped continuous filaments are used to achieve high thickness, then thickness is improved, but surface density increases and deposition homogeneity deteriorates

Engineering Contradiction:

ImprovethicknessVSAvoidsurface density

Core Design Contradiction:

Length of stationary objectVSQuantity of substance

Solution Approach 1:

The nonwoven laminate is divided into multiple individual layers (first and second spunbonded nonwoven layers) that are deposited separately in a multibeam system. Each layer is formed from individual filaments that are not strongly crimped, allowing thin layers to be stacked to achieve overall thickness without the surface density problems of strongly crimped filaments

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the crimping parameter from strong crimping (which causes inhomogeneous deposition) to little or no crimping. The filaments are deposited in a relaxed state and then compacted during consolidation, achieving thickness through layer stacking rather than filament crimping

Inventive Principle:

Principle #35Parameter changes

2Productivity

If multiple layers are produced in multibeam systems, then productivity is improved, but thickness is reduced due to compaction requirements

Engineering Contradiction:

Improveproduction speedVSAvoidthickness

Core Design Contradiction:

ProductivityVSLength of stationary object

Solution Approach 1:

The individual layers are deposited with minimal crimping and compacted only slightly during the deposition process. The full thickness is achieved by stacking multiple such layers, eliminating the need for strong intermediate compaction that would reduce thickness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of achieving thickness through vertical compression of crimped filaments, the invention builds thickness in the vertical dimension by stacking multiple thin layers, each contributing to the overall thickness without requiring strong compaction

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If finer filaments are used to improve deposition quality, then deposition homogeneity is improved, but thickness is reduced

Engineering Contradiction:

Improvedeposition homogeneityVSAvoidthickness

Core Design Contradiction:

Manufacturing precisionVSLength of stationary object

Solution Approach 1:

The nonwoven is segmented into multiple layers, each formed from finer filaments that deposit homogeneously. The overall thickness is achieved by stacking these homogeneous thin layers rather than using fewer layers with thicker, more crimped filaments

Inventive Principle:

Principle #1Segmentation

4Strength

If strong compaction is applied to consolidate layers, then strength is improved, but thickness is reduced

Engineering Contradiction:

Improvedimensional stabilityVSAvoidthickness

Core Design Contradiction:

StrengthVSLength of stationary object

Solution Approach 1:

Layers are pre-consolidated with minimal compaction during deposition to provide initial stability. Final consolidation is performed after all layers are deposited, achieving the required strength and dimensional stability without intermediate thickness reduction

Inventive Principle:

Principle #10Preliminary 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 approach enables a high thickness with optimal softness, strength, and dimensional stability, while reducing material usage and costs, and ensures a homogeneous deposition quality.

Implementation Method 1

the sheath component has a lower melting temperature and higher melt-flow rate than the core

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

the laminate is compacted using hot rollers and calender rollers to achieve a specific density below a defined limit

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

the laminate is compacted using hot rollers and calender rollers

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS20240336030A1Method of making a spunbonded laminate

Publication Date: 2024.10.10 WAGNER TOBIAS

AI summary

A laminate is made of a spunbonded nonwoven laminate, by first making first and second spunbonded nonwoven layers of which at least one has crimped bicomponent filaments having a first component based on polypropylene and a second component based on polypropylene. Then at least one spunbonded nonwoven layer is preconsolidated, and finally the first and second spunbonded nonwoven layers are finally consolidated into the spunbonded nonwoven laminate by at least one calender roller such that the laminate has a specific density dependent on its surface density and below a density limit ρG according to the equationρG=9⁢ cm-1⁢H⁢ surface⁢ density⁢ g/cm2+0.0393 g/cm3.