The main raw material of plastic woven bags is PP (polypropylene), and its auxiliary raw materials usually include modifiers, lubricants, and optical brighteners. Generally speaking, polypropylene has abundant sources and low price. Woven bags made of it are almost the same as those made of high-density polyethylene.
The damage rate of plastic woven bags is very high, so a large number of discarded woven bags are discarded every year. However, the recycling rate of PP plastic woven bags is extremely strong. They can be recycled and extruded into plastic pellets, which can be drawn into again. Woven bag. In order to ensure the quality of the flat wire disorderly processed parts, some additives are usually added to improve the appearance quality of the product, such as fluorescent brightening agent.
The function principle of fluorescent brightening agent in recycled material woven bag.
We have seen that woven bags made from recycled materials have a bad appearance, mainly because recycled materials contain colored impurities, which absorb blue or blue-violet visible light with a wavelength of about 450nm.
The reason why the fluorescent brightening agent can improve the appearance of the recycled material woven bag can make it brighter and brighter, because the fluorescent brightening agent can absorb ultraviolet light with a wavelength of about 350nm after being adsorbed on the recycled material, and can emit wavelengths of about 450nm. Visible light of blue or blue-violet.
The light emitted by it compensates for the light absorbed by the recycled material. It is known from the physical principle that the two complementary colors of light are superimposed to form a white light. Therefore, when we look at the woven bag made of recycled materials, it will be white and bright.
How to use fluorescent brightener in recycled material woven bags.
The first step is to combine various additives such as recycled materials, fluorescent brighteners, and activated calcium carbonate according to a certain ratio (the amount of brightener is about two-fifths, that is, 200g brightener is added to each ton of material). Pour into the high mixer one after another for mixing. After the barrel and screw are melted and plasticized, the material is continuously extruded. The material is cooled and shaped by water and then enters the pelletizer for pelletizing.
In the second step, the cut particles are placed in the wire drawing machine for wire drawing, and the temperature is between 30°C and 40°C to ensure the toughness of the woven bag. Then, the drawn wire is fed to the winding machine for wire separation.
In the third step, the flat yarn is interlaced with warp and weft on a circular loom to form a cloth, and then coated, followed by bag making. The bag making includes printing, cutting, sewing, and packaging. The flat yarn is further processed. For circular weaving, we can finally roll up the circularly woven woven bag and put it in the warehouse. At this time, we can see that the recycled material woven bag with optical brighteners will be white and bright.
Although woven bags made from recycled materials are inferior in physical properties and quality to woven bags made from new materials, they can reach the prescribed standards as long as they are selected reasonably.