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In recent years, calcium carbonate-based filler masterbatch has been widely used in the production of needle-punched nonwoven fabrics. PP spunbond non-woven fabrics are developing rapidly in all fields of life. The main reason is the simple production method of non-woven fabric, low production cost, and stable product quality. To reduce polypropylene and carbon dioxide emissions, factories can add calcium carbonate filler masterbatch during the production process according to customer requirements, which gives more advantages in terms of price, processing technology, production cost, physical index, etc.
Technology of making calcium carbonate in PP spunbond non-woven fabric
The raw material used for the production of spunbond needle-punched non-woven fabrics is polypropylene with a high melting index, which is uniformly mixed with the calcium carbonate filler masterbatch. After being extracted through the hopper and melted in the screw extruder, it enters a continuous pre-filter and then enters the spinning box. The melt enters the spinneret through the metering pump, and the melt is quantitatively transported to the spinneret through the precise metering of the metering pump, and forms a continuous melt trickle through the spinneret hole, that is, the main fiber. The primary fibers are then cooled by flash cooling and airflow to form tow. The filament bundles are swung back and forth by the pendulum roller and placed evenly on the moving mesh screen to form a fiber web.
Why Choose Calcium Carbonate as Filler Masterbatch?
Calcium carbonate is a very important inorganic chemical product, widely used in plastics, rubber, coatings, papermaking and other industries.
Following are the properties of several fillers commonly used in the industry:
Calcium Carbonate: Additive masterbatch addition to spunbond nonwovens is intended to reduce costs. From the experience of changing the performance and cost reduction of plastic resins, it is the cheapest and most readily available with a white, odorless powder appearance. Relative density 2.71, refractive index 1.65, Mohs hardness 3.
Kaolin: easy to disperse, relatively more expensive than calcium carbonate, white in appearance, relative density 2.6, refractive index 1.56.
Talc powder: easy to disperse, and the equipment is lubricated to a certain extent during processing. It is a white powder with hard crystals. I want a density between 2.7 and 2.8, and the price is more expensive.
Mica Powder: Whiteness is relatively low as mica powder is non-toxic and can be used in food contact products. The relative density is between 2.8 and 3.{4}}, the refractive index is 1.59, and the Mohs hardness is 3.
Wollastonite: Relative density 2.9, refractive index 1.63, Mohr hardness 4.5. The biggest advantage is that it does not absorb moisture and has little effect on the masterbatch.
Therefore, generally speaking, calcium carbonate is the main filler in the non-woven fabric manufacturing process. During the manufacturing process, small amounts of kaolin or wollastonite are added to increase dispersion and clarity. Needle punched nonwoven fabric
Generally, a calcium carbonate mesh of more than 1500 mesh is selected, and it cannot be too fine, because too fine mesh is expensive, and it is usually not possible to add ultra-fine powder.
Method of filling material filling
Without changing the production equipment and production process, fillers are added to the masterbatch hopper, but the addition ratio is limited.
Some manufacturers intentionally add a large hopper and feeder to add filler. This gives a maximum dose of 20% for granules and 8% for powders.
Now some manufacturers add one or more mixers to mix these materials evenly in the hopper after manual labor, relatively evenly. The addition ratio is as high as 30%, and the powder can reach about 15%.
Some manufacturers stir evenly after suction in the hopper and the uniformity is relatively poor, but 20% to 30% can be added.
Since filling the masterbatch reduces cost, the higher the concentration of filler in the masterbatch, the lower the cost and the less the user has to add. Conversely, the lower the density, the higher the cost and the higher the user ratio.
Source: Online/NAN
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