In recent years, calcium carbonate-based filler masterbatch has been widely used in the production of needle-punched non-woven fabrics.
PP spunbond non-woven fabrics are developing rapidly in all walks of life. The main reasons are that the non-woven fabrics have simple manufacturing methods, low production costs and stable product quality. In order to reduce polypropylene and carbon dioxide emissions, factories can add calcium carbonate filler masterbatch during the production process according to customer requirements, giving it more advantages in terms of price, processing technology, production cost, physical indicators, etc.
Manufacturing technology of 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 melt index, which is evenly mixed with calcium carbonate filler masterbatch. After being extruded through the hopper and melted in the screw extruder, it enters a continuous pre-filter and then into 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 sudden cooling and airflow to form tows. The filament bundles are swung back and forth by the pendulum roller and evenly placed on the running mesh curtain 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.
The characteristics of several commonly used fillers in industry are as follows:
Calcium Carbonate: The purpose of adding additive masterbatch to spunbond nonwovens is to reduce costs. From experience in changing the functionality of plastic resins and reducing costs, it is the cheapest and most easily available, with a white, odorless powder appearance. Relative density 2.71, refractive index 1.65, Mohs hardness 3.
Kaolin: easy to disperse, relatively higher price 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 solid crystals. I want a density between 2.7 and 2.8, and the price is more expensive.
Mica powder: The whiteness is relatively low because 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, 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 process of manufacturing non-woven fabrics. During the production process, a small amount of kaolin or wollastonite is added to increase dispersion and transparency. Needle punched nonwoven fabric
Generally, a calcium carbonate mesh number of more than 1500 mesh is selected, and it cannot be too fine, because the price of a mesh that is too fine is high, and it is generally not possible to add ultra-fine powder.
Filling method of filling material
Without changing the production equipment and production process, fillers are added to the masterbatch hopper, but the addition ratio is limited.
Some manufacturers also add a larger hopper and feeder to intentionally add filler. This gives a maximum dose of about 20% for granules and 8% for powders.
Now some manufacturers add one or several mixers to evenly mix these materials into 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 being sucked into the hopper, and the uniformity is relatively poor, but 20% to 30% can also be added.
Since filling the masterbatch reduces the cost, the higher the concentration of filler in the masterbatch, the lower the cost and the less the user needs to add. On the contrary, the lower the concentration, the higher the cost and the higher the proportion of users.
