How to make PLA meltblown material?
Polylactic acid (PLA) is currently the most widely studied and applied new polymer material with both bio-based and biodegradable properties. Its research, processing and application of meltblown nonwovens have gradually attracted the attention of researchers and industries. .
Processing and forming of PLA-based melt-blown materials The processing of PLA-based melt-blown non-woven materials is to dry the PLA-based masterbatch, heat and melt the screw (extrusion temperature 210~240 ° C), transport, filter, and measure from the melt-blown die head. The spinneret hole (diameter 0.15~0.3mm) is quantitatively extruded, and then subjected to the high temperature (230~280℃) and high speed (200~400m/s) airflow drafting measured by the die head, and then directly in the open field at room temperature. The non-woven material is obtained by further drawing in a limited field of cooling or heating, self-bonding and entanglement by the waste heat of the melt-blown fibers to the receiving device, and finally winding.
Meltblown process research shows that extrusion speed and temperature, hot air temperature and pressure (speed), slit distance, receiving distance, screen curtain winding rate, negative pressure suction strength, etc. Density, linear density, thickness, breathability and filtration properties have a significant effect.
The design of PLA-based meltblown raw materials and the processing of modified PLA-based meltblown nonwovens have high requirements on the physical properties of raw materials, mainly including thermal stability, relative molecular mass and distribution, melting point, viscosity/melt flow rate, viscoelasticity and Ash content, etc. Polymer feedstocks for meltblown tend to require relatively high melt index (MI). It is different from meltblown PP. At present, the commercially available and mature meltblown PLA grades include IngeoTM6 series grades from NatureWorks Company, and its MI is only about 80 g/(10 min) (temperature 190 °C) .
Modification of PLA-based meltblown materials Due to the inherent defects of PLA itself, such as insufficient toughness and poor heat resistance, there are still many limitations in the application of a single PLA meltblown material. In addition, based on the differentiated needs of the application field, the modification of PLA meltblown materials is imperative. The modification of PLA-based meltblown materials mainly includes in-situ modification of masterbatch (block, copolymerization, blending, etc.) and post-finishing (impregnation, plasma, magnetron sputtering, etc.). Among them, PLA melt-blown masterbatch melt blending modification (grafting, strengthening and toughening, functional modification) is relatively efficient in production, economical, less polluting, and easy to industrialize; post-finishing modification of PLA melt-blown materials (electrostatic electret) , antibacterial, hydrophilic, catalytic adsorption) is easier to exert the functional characteristics of the loaded material itself, and the function is more efficient.
Application of PLA-based melt-blown materials Melt-blown non-woven materials have the characteristics of fine fibers, large specific surface area, high porosity, and small pores. Effective barrier; at the same time, it is soft and skin-friendly, naturally antibacterial, and highly comfortable. Based on the above characteristics, PLA-based meltblown nonwovens can be widely used in air filtration, medical protection, health care, cleaning and wiping, sound insulation and sound absorption, agriculture and other fields.
