Packaging has been the need to have of human kind from early time for storing, transporting, preserve foods, goods, goods...The earliest time, people made the packets from animal skins, big leaves, vegetables to preserve their food clean and fresh. In the war time, iron, steel can was invented to keep food safe for soldiers. In every day life, lots of materials were put in use: paper, glass, wood to corn, aluminum...With the dramatic innovation of technologies, the interaction among men and women from numerous places, distinctive nations raise and demand of trading rises day by day, packaging in a most convenience way is crucial and crucial. Plastic bag has been invented to meet that demand as an wonderful remedy. So how plastic bags are produced?
Plastic comes as a by-product of oil refining, and utilizes only 4% of the total world's oil production. It is a 'biogeochemical' manipulation of particular properties of oil, into polymers, that behave 'plastically.' Plastic polymers are manufactured into 5 major kinds, of which, plastic bags are made of the kind recognized as Polyethylene. From polyethylene, resins are created and come straight into plastic bag's production.
With specific sorts such as food plastic bags, shopper plastic bags, luxurious plastic bags for popular brand names as soft loop plastic deal with bags, rigid plastic handle bags, drawstring plastic handle bags, trifold plastic handle bags, wave top rated plastic handle bags, and so on 100% virgin resins are used to make the top excellent bags: strong, smooth and nice appearance. Shoppers also call for other film colours of plastic bags (blue, green, orange, yellow, red...) to make the bags look many different and impressive. That is why manufacturers will add masterbatches (colour resins) to modify from transparent to the distinct colours. If shoppers will need the bags at less costly costs, manufacturers will put handful of percent of additive supplies such as CaCO3 (calcium carbonate) or and recycle materials to cut down bag price. At this case, sometimes producers will add an additive known as impact modifier to make bags powerful. When customers demand plastic bags which can be destroyed simply in lands, suppliers ought to mix biodegradable additives as EPI or DW2 with quantity 1 or 2% when extruding.
The 1st method is blowing film or known as extruding film. All the materials will be put into extruding machine to make massive plastic film roll. In this actions, workers or technicians need to manage the bag rolls into smooth appearance.
The second step is printing method which is mainly utilised for shopping bags which a large number of organisations could customize the printing image with their logo, brand name, info about items...When obtaining orders with printing image, manufactures will make printing plates (printing cylinders) to put into printing machines. Images are analyzed into several colors each colour will be controlled by one particular worker if the bags require print countless colors or printing images are tough.
The third step is cutting and sealing approach. The plastic rolls are put into cutting workshop to make it into various shapes and several handles. There are a lot of cutting machines out there served for several handles: T-shirt, die cut, soft loop, patch manage, rigid, flat merchandise, and so on
For the special kinds such as drawstring plastic handle bags, rigid plastic deal with bags, soft loop plastic handle bags, they are generally required some manual steps which can not be implemented by automatic machine. In manual workshop, workers have to sew the handles into the bags, putting the cardboard into gussets (customized to customer's requirement), punching the hole...
