Nonwoven Laminate Shrinkage for 3D Structure
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Solution Overview
Problem
Existing nonwoven laminates with 3D structures achieved through embossing lack stability and sufficient thickness, especially when made with lower basis weight materials, and have inadequate restoring capacity under compression.
Innovation Solution
A laminate is created by juxtaposing two nonwoven layers with different shrinkage potentials, where one layer is shrunk to raise the other layer transversely, resulting in a robust structure with bonded and unbonded regions distributed over the surface, using a closed system with a diffuser and stretcher to control filament stretching and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If embossing is used to create a 3D structure in nonwoven, then the nonwoven gains structural orientation and volume, but the thickness is reduced in compressed areas and the restoring capacity is inadequate
Solution Approach 1:
The patent applies parameter changes by utilizing the shrinkage behavior of thermoplastic filaments through temperature and tension control. The filaments are stretched during formation to create internal stress, then heated to activate shrinkage that generates the 3D structure. This thermal-mechanical parameter transformation enables volume increase without the thickness reduction associated with conventional embossing, while maintaining structural stability through controlled filament contraction.
Solution Approach 2:
The invention exploits phase transitions of thermoplastic materials during heating and cooling cycles. The filaments undergo transitions between amorphous and crystalline states, enabling reversible shape changes. When heated above the glass transition or melting point, the filaments soften and shrink to predetermined shapes, creating the 3D structure. Upon cooling, they stabilize in the new configuration, providing both volume and compressive stability.
2Shape
If embossing is used to create a 3D structure, then structural orientation is achieved, but the achievable thickness and volume are not satisfactory for lower basis weight materials
Solution Approach 1:
The patent implements preliminary action by pre-stretching the thermoplastic filaments during the nonwoven formation process. This pre-applied mechanical deformation stores elastic energy in the filament structure, which is later released during thermal processing to generate the 3D shape. By preparing the filaments in advance with predetermined orientation and stress, the method achieves greater thickness and volume control, particularly beneficial for lower basis weight materials that cannot support heavy post-processing.
3Ease of manufacture
If conventional embossing is used, then production speed and product width are limited, but the method is simple
Solution Approach 1:
The invention replaces the conventional mechanical embossing system with a thermal-mechanical system. Instead of using physical embossing rollers to force 3D structure formation, the method uses controlled heating to activate filament shrinkage. This substitution eliminates the speed and width limitations of mechanical embossing equipment, as thermal processing can be applied continuously across the entire nonwoven width at higher production rates while maintaining structural simplicity.
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 laminate with high volume and thickness, excellent compressive stability, and good restoring capacity, while maintaining simplicity and flexibility in production, allowing for continuous production with adjustable parameters.
Implementation Method 1
only the first nonwoven layer is shrunk so that the second layer bunches in the unbonded regions and is there raised transverse to a plane of the bonded-together layers
Implementation Method 2
The filaments are advantageously cooled with a fluid medium in particular with cooling air in the cooler. It is within the scope of the invention that the filaments emerging from the cooler are then guided through a stretcher that elongates the filaments. In particular by adjusting the stretching parameters, it is possible to impart to the first layer of nonwoven formed from the filaments a higher shrinkage potential
Data Source
AI summary
A laminate is made by first making by melt-blowing or spunbonding of multicomponent, thermoplastic, and endless filaments a first nonwoven layer lying generally in a plane and having a predetermined shrinkage capacity or potential parallel to the plane and making of thermoplastic and endless filaments a second nonwoven layer also lying generally in a respective plane and having a shrinkage capacity or potential that is smaller than that of the first nonwoven layer. The two layers are directly juxtaposed flatly on each other, and the directly juxtaposed first and second layer are bonded together only at bonded regions while leaving an array of unbonded regions distributed over a surface of the two bonded-together nonwoven layers. Then only the first nonwoven layer is shrunk so that the second layer bunches in the unbonded regions and is there raised transverse to a plane of the bonded-together layers.