Why do non-woven fabrics choose calcium carbonate as filler masterbatch?

Why do non-woven fabrics choose calcium carbonate as filler masterbatch?

The important reason for the rapid development of PP spunbond nonwovens is that its manufacturing method is simple and fast, the product cost is low, the quality is stable, and it is highly competitive in the market. In order to reduce the amount of polypropylene used 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.

Manufacturing process of calcium carbonate in PP spunbonded nonwoven fabric

The raw material used in the production of spunbonded non-woven fabrics is high melting index polypropylene, which is evenly mixed with calcium carbonate filler masterbatch, and enters the screw extruder from the hopper to extrude and melt, 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 forms a continuous stream of melt through the spinneret hole, that is, the primary fiber. The as-spun fibers are then cooled by quenching air and drawn by airflow to form filament bundles. The filament bundle is reciprocated by the swing roller, and evenly laid on the running web forming curtain to form a fiber web.

Why choose calcium carbonate as filler masterbatch

As a commonly used inorganic powder filling material for plastics, calcium carbonate can reduce product production costs, improve the dimensional stability, heat resistance, and tensile strength of plastic products, play the role of astigmatism and extinction, and improve the processing and formability of plastics, etc. It has many advantages that other powder materials do not have. Therefore, it is widely used in the plastic industry. The characteristics of several fillers commonly used in the industry are as follows:

• Calcium carbonate: The purpose of adding filler masterbatch to spunbonded non-woven fabric is to reduce cost. From the experience of plastic resin modification and cost reduction, it is the cheapest and easy to obtain. It looks like a white, odorless powder. The relative density is 2.71, the refractive index is 1.65, and the Mohs hardness is 3.

• Kaolin: easy to disperse, relatively higher price 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 a white powder with solid crystals. The relative density is between 2.7 and 2.8, and the price is relatively expensive.

• Mica powder: The relative whiteness is lower, because the 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: The relative density is 2.9, the refractive index is 1.63, and the Mohs hardness is 4.5. The biggest advantage is that it does not absorb moisture and has little effect on the color masterbatch.

Precautions for the application of calcium carbonate in non-woven fabrics

Due to the particularity of the fiber and non-woven fabric industries, the requirements for the selection of calcium carbonate are also very strict. When using calcium carbonate to fill modified fibers and non-woven fabrics, the following requirements should be paid attention to.

(1) The particle size and distribution of calcium carbonate should be appropriate. In the process of melt spinning or spinning, if the particle size of the calcium carbonate filler selected is too large, it will cause the blockage of the spinneret holes, which will seriously affect the production and performance of the product; if the particle size is too fine, it is easy to agglomerate, At the same time, the cost is increased, so the particle size of calcium carbonate should be strictly screened.

(2) Dispersion is better. Since calcium carbonate is difficult to disperse evenly during the filling application process, calcium carbonate is usually pre-dispersed before use (that is, calcium carbonate filling masterbatch is prepared) to achieve a better filling effect.

(3) The higher the whiteness, the better.

(4) In some special products (such as medical and sanitary products), the purity of calcium carbonate should be high, the compounds of silicon, iron and other elements should be as low as possible, and the content of harmful heavy metal elements should be strictly required.