In recent years, calcium carbonate-based filler masterbatches have been widely used in the production of plastics and non-woven fabrics, making non-woven companies across the country develop rapidly in a short period of time, with prosperous business and fierce competition.
The important reason for the rapid development of PP spunbond non-woven fabrics is that its manufacturing method is simple and fast, the product cost is low, the quality is stable, and the market competitiveness is strong. In order to reduce the amount of polypropylene and reduce carbon dioxide emissions, producers will also add calcium carbonate filler masterbatch in the production process to give it more advantages in terms of price, processing process, production cost, and physical indicators. From this point of view, the application field and sustainable development of PP spunbond non-woven fabrics have been greatly expanded. Energy saving and emission reduction is an inevitable trend in the development of the spunbond non-woven fabric industry.
Manufacturing Process of Calcium Carbonate in PP Spunbond Nonwoven
The raw material used in the production of spunbond non-woven fabrics is high melting index polypropylene, which is evenly mixed with calcium carbonate filler masterbatch, and then enters the screw extruder from the hopper to extrude and melt, and then enters the continuous pre-filter, and then enters the spinning box. .
The melt enters the spinning head through the metering pump, and is accurately metered by the metering pump, and the melt is quantitatively transported to the spinneret, and a continuous melt stream, namely the primary fiber, is formed through the spinneret hole.
The spun fibers are then cooled by quench air and drawn by air to form filament bundles. The filament bundle is oscillated back and forth by the oscillating roller, and is evenly laid on the running web forming curtain to form a fiber web.
Why choose calcium carbonate as filler masterbatch?
Calcium carbonate is an extremely important inorganic chemical product, widely used in plastics, rubber, coatings, papermaking and other industries. The characteristics of several fillers commonly used in industry are as follows:
Calcium carbonate: The purpose of adding filler masterbatch to spunbond non-woven fabrics is to reduce costs. From the experience of plastic resin modification and cost reduction, it is the most inexpensive and easy to obtain, and the appearance is white, odorless powder. The relative density is 2.71, the refractive index is 1.65, and the Mohs hardness is 3.
Aged soil: easy to disperse, more expensive than calcium carbonate, white in appearance, relative density of 2.6, and refractive index of 1.56.
Talc powder: easy to disperse, has certain lubricity to equipment during processing, and is white powder with solid crystals. I want the density to be between 2.7 and 2.8, and the price is relatively expensive.
Mica powder: The relative whiteness is lower. Since mica powder is non-toxic and can be used in food contact products, the relative density is between 2.8 and 3.0, the refractive index is 1.59, and the Mohs hardness is 3.
Wollastonite: relative density 2.9, refractive index 1.63, Mohs hardness 4.5, the biggest advantage is that it does not absorb moisture and has little effect on the color masterbatch.
Therefore, in the production process of non-woven fabrics, calcium carbonate is generally selected as the main filler, and a little advanced soil or wollastonite is appropriately added in the production process to increase dispersibility and transparency.
Generally, the mesh number of calcium carbonate is more than 1500 mesh, and it should not be too fine, because the price of too fine mesh is high, and the ultrafine powder generally cannot be dispersed.
Filling method of filler
Without changing the production equipment and production process conditions, the filler is added in the hopper of the color masterbatch, but the addition ratio will also be limited.
Some manufacturers add a larger hopper and feeder to deliberately add filler. In this way, the maximum amount of pellets added is about 20%, and the powder is about 8%.
Now some manufacturers add one or several mixers to mix the materials evenly and then manually throw them into the hopper, which is relatively uniform. The addition ratio is as high as 30%, and the powder can also reach about 15%.
Some manufacturers suck it into the hopper after stirring evenly, and the degree of uniformity is relatively poor, but it can also be added to 20% to 30%.
Since the filler masterbatch reduces the cost, the higher the filler concentration in the filler masterbatch, the lower the cost, and the user adds less. Conversely, the lower the concentration, the higher the cost, and the more users add. And the production of functional masterbatch can not be filled with masterbatch, so as not to affect its functionality.