Woven bags are usually made of cross-woven silk, with tiny seams at the cross of the knitted silk. Therefore, polyethylene resin is usually used to coat the surface of woven bags. The manufacturing method of this kind of woven bag is that fibre cylinder is woven on a circular loom, then coated resin is added to the extruder, hot melt film is extruded by the extruder and coated on the outer surface of the woven cylinder to become a product. This process needs more production equipment and consumes more energy. At the same time, the coating is prone to aging and peeling off, and it has poor wear resistance and short service life.
This paper introduces an environmental protection inner coating process for plastic woven bags, in order to solve the problems raised in the above background technology.
1. Specific implementation steps:
1) The finished flat yarn is woven into a woven bag fabric by a knitting machine, which is used as a backup for coating;
2) Preparation of environmentally friendly coatings for coating;
3) Preheat the coated substrates in step 1, and add the environmentally friendly coatings to the coating equipment. The coated substrates are coated by the coating equipment;
4) Cool, dry and remove the static electricity of the coated base cloth, then make the finished woven bag by slitting.
2. Formula of environmentally friendly coatings:
Polypropylene 60-80, linear polyethylene 40-60, initiator 5-10, rare earth stabilizer 6-8, antioxidant 7-12, corrosion inhibitor 8-15, flame retardant 6-11, ultraviolet absorbent 4-9.
1) Formula 1: polypropylene 60, linear polyethylene 40, initiator 5, rare earth stabilizer 6, antioxidant 7, corrosion inhibitor 8, flame retardant 6, ultraviolet absorbent 4.
2) Formula 2: polypropylene 70, linear polyethylene 55, initiator 8, rare earth stabilizer 7, antioxidant 9, corrosion inhibitor 12, flame retardant 8, ultraviolet absorbent 6.
3) Formula 3: polypropylene 80, linear polyethylene 60, initiator 10, rare earth stabilizer 8, antioxidant 12, corrosion inhibitor 15, flame retardant 11, ultraviolet absorbent 9.
3. The preparation method of the environmental protection coating is as follows:
1) Take the raw materials of the above quality parts for reserve;
2) Polypropylene, linear polyethylene and initiator are first mixed in a mixer, and then stirred at a uniform speed for 10-15 minutes.
3) Add rare earth stabilizer, antioxidant, corrosion inhibitor, flame retardant and ultraviolet light absorbent into the mixer, then continue mixing to make the mixing uniform.
4) The mixed materials were granulated by extrusion equipment to produce environmentally friendly coatings.
The ultraviolet absorbent adopts UV-531.
The antioxidant uses methyl silicone.
The flame retardant adopts polyvinyl chloride or phosphorus-containing resin.
The initiator uses organic peroxide or bicarbonate.
4. The beneficial effects are as follows:
1) The process uses environmentally friendly raw materials as coating formulation, which makes the woven bags have good fluidity, corrosion resistance, high temperature resistance, good processing performance and environmental protection performance, as well as fire protection, ultraviolet absorption and oxidation resistance.
2) This process is an internal coating process based on spraying, which can reduce the demand for production equipment, improve production efficiency and save costs.