Nonwoven fabrics are broadly defined as sheet or web structures bonded together by entangling fiber or filaments (and by perforating films) mechanically, thermally, or chemically. They are flat, porous sheets that are made directly from separate fibers or from molten plastic or plastic film. They are not made by weaving or knitting and do not require converting the fibers to yarn.
These engineered fabrics open up a world of innovative possibilities for all types of industries.
Nonwovens may be a limited-life, single-use fabric or a very durable fabric. Nonwoven fabrics provide specific functions such as absorbency, liquid repellency, resilience, stretch, softness, strength, flame retardancy, washability, cushioning, filtering, bacterial barriers and sterility. These properties are often combined to create fabrics suited for specific jobs while achieving a good balance between product use-life and cost. They can mimic the appearance, texture and strength of a woven fabric, and can be as bulky as the thickest paddings.
oday, innovations in nonwoven fabrics are growing as rapidly as the demand for them, with almost unlimited possibilities for a wide variety of industries, including:
2.1 Different types of non-woven fabrics
According to different manufacturing processes, the non-woven fabrics can be divided into 8 types: Spunlace nonwovens, Heat-bonded nonwoven fabrics, Pulp air-laid nonwovens, Wet-laid non-woven, Spunbond nonwovens, Meltblown nonwovens, Acupuncture nonwovens, Stitch nonwovens.
2.2 Manufacturing process of non woven fabric for packaging industry by spunbond method
In this article, we will specify the method of producing non woven fabric for packaging industry by spunbond method.
Spunbond-type of nonwoven fabric is processed as follows: extrude and stretch the polymer to form a continuous filament, laid the filament into web, then process the web into nonwoven fabric through their own bonding, thermal bonding, chemical bonding or mechanical reinforcement methods.
Here are the steps of manufacturing process:
Source: Unitika, 2021
Step 1: Melt polymer resin (raw material).
Step 2: Form filaments by spinning the molten polymer and stretching the molten filaments.
Step 3: Separate and spread fiber bundles of many filaments, and lay down the fibers on a net to form a web.
Step 4: Bind the fibers in the form of a sheet through thermal bonding and perform embossing.
Step 5: Perform special in-line processing such as calendar processing.
Step 6: Wind up the sheet.
2.3 Useful tips to use CaCO3 Filler Masterbatch in non woven fabric production
Nonwoven fabric in packaging which is made in to shopping bag, carry bag is called Non-woven or spun-bond, made by Polypropylene. The machinery is mainly made in China or Taiwan; the machine body is basically the same as other applications are single-axis extruders but the die-head is completely different which is divided into many small hole to produce yarn.
The processing temperature of nonwovens fabric is usually between 210 ° C- 240 ° C. The unit of measuring this product is the thickness of the product in Gram / square meter, for thin fibers, from 20 – 30 g / m2, for the average fibers, from 40 to 80 g / m2, for thick fibers, the thickness is over 80 g / cm2.
The dosage of using filler for different thicknesses is also different, with thin fibers it is recommended from 5- 20%, with medium fibers it is from 20-35%, for thick fibers it can be added from 30- 60%. On the other hand, nonwoven fabric requires filler masterbatch with extremely good dispersion and stability, with the Calcium Carbonate content from 78- 80% is best and melt flow index from 20 – 40 g / 10 min.
The Melt Flow Index of filler masterbatch for nonwoven fabric also varies, with thick yarns the lower MFI index can be chosen, and conversely the thinner the yarn, the higher the MFI is required.
Finally, when changing the dosage rate of CaCO3 filler masterbatch in non woven fabric production, it should be changed slowly. During the process of changing the machine parameters, observation and adjustment the machine parameters shoule be reasonabl, to avoid clumping and tearing the belt.
2.4 Popular problem during manufacturing of non woven fabrics
Yarn drop (lump falling)
Causes and solutions:
The solution is to clean the extruder die head to continue running, monitoring how long the same problem reappears, the time of arrival.
The solution is to clean the filter net, determine the cause of the mesh and find solutions to overcome.
Causes and solutions:
In the composition of the filler masterbatch contains groups of soften ingredients, this amount is redundant => need to improve the formula to be more suitable for customers.
The thread is too hard
Cause and solution:
It is recommended to improve the filler formula by adding more additive groups to make the final product softer, you can improve the formula from the filler to solve this problem.
The physical properties of the fiber are weak
Causes and solutions