Dual-Density Wet Wipe Structure for Bulk and Shape Stability

Solution Overview

Problem

Existing wet wipes made by applying patterns to fiber sheets using steam pressure often lose shape during rewinding or slitting, require additional strength agents, and have reduced contact area due to concavities and convexities, affecting their wiping efficiency.

Innovation Solution

A nonwoven fabric with different apparent densities on its surfaces, where one surface has fibers raised by steam disentanglement and the other by water stream entanglement, creating distinct ridges and grooves for enhanced wiping capabilities without the need for strength agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a fiber sheet is pressed with steam pressure to apply a pattern, then the fiber sheet becomes bulky with concavities and convexities, but the shape is easily destroyed during rewinding or slitting and the bulk is difficult to maintain

Engineering Contradiction:

ImprovebulkVSAvoidshape stability

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The fiber sheet is divided into multiple layers with different functions: a first nonwoven fabric layer providing bulk and softness, and a second nonwoven fabric layer providing strength and shape stability. This segmentation allows each layer to specialize in its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure of two different nonwoven fabric layers bonded together. The first layer (bulk layer) has lower apparent density (0.03-0.10 g/cm³) for softness, while the second layer (strength layer) has higher apparent density (0.12-0.20 g/cm³) for strength, creating a composite material that combines both properties.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If thermoplastic fiber is used to maintain shape in wet state through embossment, then shape stability is improved, but the fiber density increases and wiping properties deteriorate

Engineering Contradiction:

Improveshape stabilityVSAvoidfiber density

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The fiber sheet is divided into multiple layers with different functions: a first nonwoven fabric layer providing bulk and softness, and a second nonwoven fabric layer providing strength and shape stability. This segmentation allows each layer to specialize in its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

3Volume of moving object

If the fiber sheet is pressed to apply concavities and convexities, then bulk is increased, but the contact area is reduced and wiping-off properties deteriorate

Engineering Contradiction:

ImprovebulkVSAvoidwiping-off properties

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The first nonwoven fabric layer is designed with locally varied properties: it has high bulk and low apparent density (0.03-0.10 g/cm³) to provide softness and absorbency, while maintaining sufficient contact area through controlled fiber arrangement rather than deep embossment patterns.

Inventive Principle:

Principle #3Local quality

4Shape

If the fiber sheet is pressed to apply patterns, then the shape is defined, but strength agents are required to maintain strength

Engineering Contradiction:

Improvepattern shapeVSAvoidstrength agent requirement

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

The invention uses a composite structure of two different nonwoven fabric layers bonded together. The first layer (bulk layer) has lower apparent density (0.03-0.10 g/cm³) for softness, while the second layer (strength layer) has higher apparent density (0.12-0.20 g/cm³) for strength, creating a composite material that combines both properties.

Inventive Principle:

Principle #40Composite materials

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 fabric provides effective fouling removal and finishing wiping with one sheet, maintaining softness and reducing water retentivity for a comfortable skin feel, while maintaining bulkiness and strength.

Implementation Method 1

spraying steam to raise the fibers

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

spraying steam to raise the fibers

Methodology Applied

Scientific EffectSteam explosion: Steam Explosion

Implementation Method 3

spraying a water stream onto the web from water stream nozzles to entangle the fibers

Methodology Applied

Scientific EffectHydraulic force: Hydraulic Press

Data Source

PatentUS9074323B2Wet wipe and method for manufacturing the same

Publication Date: 2015.07.07 UNI CHARM CORP

AI summary

A wet wipe includes a nonwoven fabric impregnated with a liquid. A surface layer in a first surface of the nonwoven fabric has an apparent density of 0.030-0.10 g/cm3 in a dry state. A surface layer in a second surface of the nonwoven fabric has an apparent density of 0.12-0.20 g/cm3 in a dry state. Fibers constituting the nonwoven fabric are raised on at least the first surface.