Multilayer Nonwoven Fabric Low Melting Endotherm Bonding
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Solution Overview
Problem
Conventional multilayer nonwoven fabrics with spunbonded and meltblown layers face challenges in achieving high water pressure resistance without piercing the meltblown layer, due to issues with denier values and bonding strength between layers.
Innovation Solution
Regulating the melting endotherm of the resin for the spunbonded nonwoven fabric layer to 90 J/g or less, using a polypropylene-based resin composition with low-crystalline and high-crystalline polypropylene, and heat treating at 130°C or lower to ensure strong layer-to-layer bonding without piercing the meltblown layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fusion temperature is increased to improve bonding force between layers, then the bonding force between spunbonded nonwoven fabric layers is improved, but the meltblown nonwoven fabric layer is pierced and water pressure resistance is lowered
Solution Approach 1:
The patent changes the melting point parameter of the resin forming the spunbonded nonwoven fabric layer from conventional high melting points to a specific range of 100°C to 120°C. This parameter change allows the resin to melt and bond layers at lower temperatures (100°C to 130°C), sufficient for bonding but below the piercing temperature of the meltblown layer, thus resolving the contradiction between bonding force and water pressure resistance
Solution Approach 2:
The patent applies preliminary action by pre-heating the multilayer nonwoven fabric to a specific temperature range (100°C to 130°C) before pressing. This pre-heating activates the low melting point resin in the spunbonded layers, enabling it to flow and bond the layers together at a temperature that does not pierce the meltblown layer, thus achieving strong bonding without compromising water pressure resistance
2Reliability
If the fusion temperature is decreased to prevent piercing of the meltblown nonwoven fabric layer, then the integrity of the meltblown layer is maintained, but the bonding force between layers is lowered
Solution Approach 1:
The patent changes the melting point parameter of the resin to a specific range of 100°C to 120°C, which is lower than conventional resins. This allows effective layer bonding to occur at temperatures below 130°C, a temperature range that is sufficient for bonding but remains below the piercing threshold of the meltblown layer, thus maintaining both integrity and bonding force
Solution Approach 2:
The low melting point resin acts as an intermediary substance that facilitates bonding between layers at low temperatures. This intermediary resin melts and flows at 100°C to 120°C, creating strong bonds between spunbonded layers and the meltblown layer without transmitting excessive heat that would pierce the meltblown layer, thus resolving the contradiction between bonding force and layer integrity
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
This approach results in a multilayer nonwoven fabric with high strength and water pressure resistance, effectively addressing the limitations of previous methods by maintaining the integrity of the meltblown layer while enhancing bonding and water resistance.
Implementation Method 1
a resin that forms the spunbonded nonwoven fabric layer has a melting endotherm ΔH, as measured from a melting endothermic curve which is obtained by holding the resin at -10°C for 5 minutes under a nitrogen atmosphere and then increasing the temperature at a rate of 10°C/min with a differential scanning calorimeter (DSC), of 90 J/g or less
Implementation Method 2
heat treating at 130°C or lower to ensure strong layer-to-layer bonding without piercing the meltblown layer
Data Source
AI summary
Provided are a multilayer nonwoven fabric having a meltblown nonwoven fabric layer and a spunbonded nonwoven fabric layer, the multilayer nonwoven fabric having high strength and high water pressure resistance, and a method for producing the same. The multilayer nonwoven fabric includes three or more layers, wherein two outermost layers are spunbonded nonwoven fabric layers, at least one inner layer is a meltblown nonwoven fabric layer, and a resin that forms the spunbonded nonwoven fabric layer has a melting endotherm ΔH, as measured from a melting endothermic curve which is obtained by holding the resin at -10°C for 5 minutes under a nitrogen atmosphere and then increasing the temperature at a rate of 10°C/min with a differential scanning calorimeter (DSC), of 90 J/g or less.