Nonwoven Fabric Calendering with Moisture Control
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Solution Overview
Problem
Existing nonwoven fabric manufacturing methods face challenges such as patterning durability when wet, long manufacturing line lengths due to belt patterning, and high costs associated with drum patterning, as well as the limitations of using thermoplastic binders which are not biodegradable.
Innovation Solution
A manufacturing line comprising a forming device, spunlacing unit, first drying device, calender for patterning, and a second drying device to create a durable, biodegradable nonwoven fabric with a calendered pattern that retains its design even when wet, and is more cost-effective and compact compared to traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water patterning is used to create patterns in nonwoven fabric, then the patterning is permanent and durable, but the equipment cost is high and the manufacturing line length increases
Solution Approach 1:
The invention changes the parameter of moisture content dynamically during calendering. The calender presses the web at controlled moisture levels (optimal range 40-60% moisture content) to create patterns that become permanent after drying. This parameter control allows calendering to achieve patterning durability comparable to water patterning while using simpler, more compact equipment.
2Length of stationary object
If calendering is used to create patterns in nonwoven fabric, then the manufacturing line is shorter and equipment cost is lower, but the patterning disappears when the fabric gets wet
Solution Approach 1:
The invention performs preliminary drying of the web before calendering to achieve optimal moisture content (40-60%). This preliminary preparation ensures that when the calender presses the web, the patterns are formed under optimal conditions and then permanently fixed by subsequent drying. This preliminary action prevents pattern disappearance when wet.
Solution Approach 2:
The invention dynamically controls the moisture content parameter during calendering, maintaining it within the optimal range of 40-60%. This parameter control, combined with the drying steps before and after calendering, ensures patterns remain permanent even when the fabric gets wet, resolving the limitation of conventional calendering.
3Strength
If thermoplastic materials are used as web binders, then the web gains sufficient strength, but the material is not biodegradable and causes environmental loading
Solution Approach 1:
The invention replaces chemical/thermal bonding methods (using thermoplastic materials) with mechanical bonding through hydroentanglement and spunlacing. High-pressure water jets mechanically interlock the fibers, providing sufficient web strength without requiring non-biodegradable thermoplastic binders, thus eliminating the environmental harm.
Solution Approach 2:
The invention changes the bonding mechanism from thermoplastic melting to hydroentanglement by controlling water pressure and fiber arrangement. This parameter change allows achieving adequate web strength through mechanical interlocking of biodegradable fibers alone, eliminating the need for harmful thermoplastic 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 solution ensures that the nonwoven fabric's patterning remains intact when wet, allows for a shorter manufacturing line, and uses a more affordable calendering process, while being biodegradable and environmentally friendly.
Implementation Method 1
In the method, the fibres are needled with the aid of high-pressure water jets.
Implementation Method 2
a calender having ribs evenly alternating with grooves so that to define a calendering pattern thereon
Implementation Method 3
at least one first drying device to dry the web, and a calender to form patterning in the web. In addition, the manufacturing line comprises at least one second drying device to dry the calendered web
Data Source
AI summary
Nonwoven fabric manufacturing line (1), which comprises a forming device (2) for forming a fibre web (3) on a moving web-forming base (4) and a spunlacing device (5) for reinforcing the web (3). Further, the line comprises at least one first drying device (8, 10) for drying the web (3) and a calender (12) for forming patterning in the web (3). The manufacturing line (1) comprises at least one second drying device (14) for drying the calendered web (3), which second drying device (14) is located after the calender (12) in the direction of travel of the web (3).