Meltblowing Die with Liquid Spray for Beta Crystallization
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Solution Overview
Problem
Current meltblown processes for producing polypropylene fibrous materials struggle to achieve high beta crystalline content, which is essential for desired properties such as impact strength and toughness, due to limitations in adaptability and effectiveness of existing methods.
Innovation Solution
A system and process involving a meltblowing die with a longitudinally extending die tip and liquid spray nozzles that spray a substantial amount of liquid at specific angles and flow rates to axially attenuate the polymer, enhancing beta crystallization, including the use of water spray to induce alpha to beta phase transition during filament formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional meltblown processes are used to produce polypropylene fibrous materials, then the process is simple and adaptable to current manufacturing, but the beta crystalline content remains low
Solution Approach 1:
The patent applies parameter changes by modifying the crystallization conditions during meltblown processing. Specifically, it controls the cooling rate and temperature profile to promote beta crystal formation over alpha crystals. The process parameters including die temperature, air flow rate, and collection temperature are optimized to achieve high beta crystalline content (greater than 80%) in the resulting fibrous material.
Solution Approach 2:
The patent utilizes phase transitions by controlling the crystallization process from molten polymer to solid fiber. It employs specific cooling rates and temperature gradients to induce preferential formation of beta crystals during the phase transition from liquid polymer melt to solid crystalline structure. This phase transition control is achieved through optimized die design and processing conditions.
2Manufacturing precision
If directional crystallization under temperature gradient is used to increase beta crystals, then beta crystalline content increases, but the process is not easily adaptable to current meltblown processes
Solution Approach 1:
The patent achieves universality by integrating beta crystal formation capabilities into the standard meltblown process framework. The methodology uses conventional meltblown equipment and operating principles while incorporating specific parameter optimizations that enable beta crystallization. This makes the process universally applicable to existing meltblown manufacturing lines without requiring fundamental process changes or specialized equipment modifications.
Solution Approach 2:
The patent applies parameter changes by modifying the crystallization conditions during meltblown processing. Specifically, it controls the cooling rate and temperature profile to promote beta crystal formation over alpha crystals. The process parameters including die temperature, air flow rate, and collection temperature are optimized to achieve high beta crystalline content (greater than 80%) in the resulting fibrous material.
3Ease of manufacture
If isotactic polypropylene is processed under standard conditions, then the polymer is easy to process and crystallizes rapidly, but it forms mostly alpha crystals with very low beta content
Solution Approach 1:
The patent applies parameter changes by modifying the crystallization conditions during meltblown processing. Specifically, it controls the cooling rate and temperature profile to promote beta crystal formation over alpha crystals. The process parameters including die temperature, air flow rate, and collection temperature are optimized to achieve high beta crystalline content (greater than 80%) in the resulting fibrous material.
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 process significantly increases beta crystalline content in the fibrous material, improving tensile stresses, percent elongation to break, and heat deflection temperature, resulting in enhanced mechanical properties like impact strength and toughness.
Implementation Method 1
spraying a liquid into the fibrous melted polymer attenuated from the die tip... use of water spray to induce alpha to beta phase transition during filament formation
Implementation Method 2
enhancing beta crystallization... significantly increases beta crystalline content in the fibrous material
Implementation Method 3
flowing hot gas through longitudinal fluid material flow through passages... axially attenuate the melted polymer
Data Source
AI summary
A system and process for making a polymeric fibrous material having increased beta content is provided herein. The system is configured for meltblowing polymer into a fibrous material having high beta crystalline content and has an extruder for melting and moving a polymer to a meltblowing die. The meltblowing die has a longitudinally extending die tip with a plurality of spinnerets substantially equidistantly spaced from each other and a longitudinal fluid material flow through passage disposed along each longitudinal side of the die tip configured to axially attenuate the melted polymer from the die tip in fibrous form. A plurality of liquid spray nozzles are configured and disposed to spray a liquid into the fibrous melted polymer attenuated from the die tip.