Low Density Perforated Web Calendering for Sanitary Absorbent Articles
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Solution Overview
Problem
Existing low density perforated web materials used in absorbent sanitary articles fail to adequately balance cushioning effect, softness, and pliability, particularly under pressure, and are costly to produce, with existing calender methods not effectively enhancing thickness for improved performance.
Innovation Solution
A calender process using slipping rollers with specific protrusions and recesses maintains or slightly reduces the thickness of low density web materials to at least 0.2 mm, achieving a balance between cushioning, softness, and pliability by controlling air content and fiber compression, while allowing for better fluid diffusion and reduced rewet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If continuous polymer web materials with very low thickness are used to meet pliability requirement, then pliability is improved, but overall performance considering all requirements is not satisfactory
Solution Approach 1:
The patent applies composite materials by combining a continuous polymer web (providing pliability) with a non-woven fibrous layer (providing absorbency and structural integrity). This composite structure allows the material to meet multiple requirements simultaneously: the thin polymer layer ensures pliability while the fibrous layer contributes to overall performance in terms of fluid absorption and retention.
2Ease of operation
If low density webs are used for layers in contact with skin, then pliability is improved, but production cost increases
Solution Approach 1:
The patent applies local quality by using low density web material specifically in the regions where pliability is most needed (skin-contact layers), while using more cost-effective materials in other layers where pliability is less critical. This localized application of expensive materials optimizes the balance between performance and cost by concentrating the beneficial properties only where they provide the most value.
3Reliability
If calender process with slipping rollers is used to increase thickness, then cushioning effect is improved, but material thickness increases due to accumulation
Solution Approach 1:
The patent applies parameter changes by carefully controlling the calender process parameters (roller temperature, pressure, speed differential) to achieve the desired thickness increase for cushioning effect while preventing excessive material accumulation. By optimizing these parameters, the process achieves improved cushioning without excessive thickness gain that would compromise other performance characteristics.
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 method produces a low density web material with enhanced cushioning and pliability, maintaining or slightly reducing thickness, improving user comfort and performance, and allowing for high air content and cost-effective production with improved fluid absorption and reduced rewet.
Implementation Method 1
both a pressure on a plane comprising both axes of the rollers and an action perpendicular to said plane is applied to the web material
Implementation Method 2
The latter action, defined by the relative slipping between the rollers, causes a localised tearing of the web
Implementation Method 3
When two heads of respective projections come into contact with each other, a localised perforation is performed on the web
Data Source
AI summary
A method for producing a low density perforated web material having a thickness of at least 0.20 mm, comprising the steps of:providing a layer of low density material having a maximum overall weight per square meter of 75 g/m2 or less; andprocessing the low density material between two rollers pressing onto each other to obtain a low density perforated web material, wherein a first roller has protrusions to perforate the low density material, and a second roller rotates at a different speed from that of the first roller and has projecting parts with contact areas arranged to perforate the material with the protrusions, the contact areas being spaced by recesses to receive the material and having larger contact face dimensions than the protrusions, the recesses leaving an impression in relief on the low density polymer material.