Hydroentangled Cotton Top Sheet With Density Channels

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Solution Overview

Problem

Sanitary towels made of cotton exhibit high surface expansion of absorbed liquids due to capillarity, leading to widening of liquid stains and soiling of adhesive wings, which is not effectively addressed by existing technologies.

Innovation Solution

A sanitary towel with a topsheet made of hydroentangled cotton or natural fibers, featuring alternating longitudinal lines of higher and lower fiber density, achieved through a two-step hydroentangling process with varying water pressure and nozzle arrangements, to control capillarity and absorbency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a thin porous surface layer of cotton is used as topsheet, then breathability and comfort are improved, but liquid surface expansion increases causing stain widening

Engineering Contradiction:

ImprovebreathabilityVSAvoidliquid surface expansion

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The topsheet is created with local variations in fiber density, forming alternating longitudinal lines of high and low density. The high density lines act as capillary channels that guide liquid flow, while the low density lines reduce transverse expansion. This local quality differentiation allows the material to maintain breathability while controlling liquid spread.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The topsheet structure is segmented into alternating longitudinal lines of different fiber densities. This segmentation creates distinct functional zones: high density lines for liquid channeling and low density lines for limiting transverse spread. The segmentation is achieved through controlled hydroentangling processes that apply water pressure at specific intervals.

Inventive Principle:

Principle #1Segmentation

2Strength

If high pressure water jets are used in hydroentangling, then fiber binding strength is improved, but liquid capillarity and surface expansion increase

Engineering Contradiction:

Improvefiber binding strengthVSAvoidliquid capillarity

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The hydroentangling process uses periodic application of high and low water pressure in alternating zones. High pressure is applied periodically to create bound fiber lines, while low pressure zones allow for reduced capillarity. This periodic action pattern creates the alternating density lines that control liquid flow while maintaining sufficient fiber binding.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The process changes the water pressure parameter dynamically during hydroentangling, switching between high pressure (for strong binding) and low pressure (for reduced capillarity). This parameter change is applied spatially to create alternating zones of different fiber density, balancing binding strength with liquid control properties.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional hydroentangling is used, then manufacturing simplicity is maintained, but liquid stain expansion to wings occurs

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidliquid stain expansion

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The conventional hydroentangling process is segmented into multiple passes with alternating high and low pressure zones. This segmentation can be achieved using multiple nozzle rows or by varying jet strip positioning, creating the alternating density lines needed to prevent liquid spread while maintaining ease of manufacture through standard hydroentangling equipment.

Inventive Principle:

Principle #1Segmentation

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 significantly reduces transverse liquid expansion, maintaining high absorbency while preventing liquid from spreading to the wings, thus minimizing stain size and improving hygiene.

Implementation Method 1

Since cotton is notoriously an absorbent material with high capillarity, this type of sanitary towel suffers the disadvantage of exhibiting a high expansion of the liquid which traverses it

Methodology Applied

Scientific EffectCapillarity: Capillary Action

Data Source

PatentEP2692922B1Channelled nonwoven with reduced surface expansion of liquid for the production of sanitary towels and relative process of manufacture

Publication Date: 2018.04.04 FA MA JERSEY

Figure 1a~1b
Figure 2a
Figure 2b

AI summary

A description is given of a sanitary towel for physiological liquids comprising as topsheet layer a layer of nonwoven cotton (10) having density which varies transversely and provided with a first plurality of longitudinal lines (1) along which said textile has a higher density of fibres with respect to the rest of the textile, each of said longitudinal lines (1) of said first plurality of lines being alternated with a respective longitudinal line (2) of a second plurality of longitudinal lines (2) along which said textile has a lower density of fibres with respect to the longitudinal lines (1).