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Material classification of shopping bags
Jul 19, 2018

Plastic shopping bags are packaging materials made of polyolefin as main raw material and appropriately added other substances. Polyolefin is mainly used as polyethylene (PE), commonly known as soft glue, and the main products include low density polyethylene or high pressure polyethylene (LDPE), high density polyethylene or low pressure polyethylene (HDPE), linear low density polyethylene (LLDPE) and metallocene polyethylene (mLLDPE). In order to reduce its cost, most companies add about 30% calcium carbonate to fill plastic shopping bags, which do not release toxic gases when they are burned in the garbage dump. The newly issued national plastic shopping bag standard divides plastic shopping bags into three categories:

Ordinary plastic shopping bags -- using polyolefin and fillers as raw materials, such plastic shopping bags do not have degradation properties, and they will not be degraded in the wild. This plastic shopping bag has excellent recyclability and can be recycled several times. The properties of recycled materials are reduced to varying degrees, but they can be used for shopping bags or garbage bags with low performance requirements and strict color requirements. The key question is whether it can be recovered.

Starch based plastic shopping bags -- modified starch as the main raw material and suitable addition of a small amount of other degradable materials to improve its performance. The plastic shopping bag can be naturally degraded after being abandoned in the field.

Degradable plastic shopping bags - this shopping bag is made of completely degradable plastics as raw material and has complete degradation performance. Products abandoned in the wild can be completely degraded into small molecular microbes, without any environmental pollution, and abroad are promoting such plastic shopping bags. According to the specific composition of the completely degradable plastics, it can be divided into three categories:

(1) PLA and PHA biodegradable plastics synthesized by natural starches through biological fermentation process need to consume a large amount of grain, so the development space is limited.

(2) the aliphatic polycarbonate (APC) degradable plastics, synthesized from carbon dioxide, use carbon dioxide, which is being called by everyone, as raw materials. It does not consume food, reduces the emission of carbides, eliminates the global warming caused by greenhouse gases, and raises two birds with one stone, so the market prospects are wide. Broad.

(3) the addition of non starch degradation products to ordinary plastics is in the stage of industrialization. If the degradation performance is reliable, it will have a bright future. Nonwoven shopping bags are non-woven fabrics made of plastic. Many people think that cloth is natural material, which is actually a misunderstanding. The common raw materials are polypropylene (PP, commonly called polypropylene) or polyethylene terephthalate (PET, commonly called polyester), especially the PE of PP and plastic shopping bag, which belong to five general-purpose plastic varieties, and belong to plastic varieties that can not be degraded for 50 years. For example, the ordinary nonwoven shopping bag, which we all call the environmental shopping bag, is made of polypropylene fiber through special process. In essence, polypropylene (PP) is a typical plastic and plastic bag. Therefore, the environmental protection and the ordinary plastic shopping bag can not be completely degraded.

In terms of specific cost performance, the strength of non-woven fabric bags under the same conditions is not as good as that of plastic bags, and it is not waterproof, and its price is several times higher than that of plastic bags. What we need to mention is the non-woven shopping bags made of more than 2 kinds of materials, which are more difficult to recycle than ordinary plastic shopping bags. 1, for general dry goods, it is recommended to use the whole American waste or European waste, and control the production of base paper according to the technical indicators of A or B grade kraft liner board. The noodles can be dried noodles or noodles, depending on whether or not to print complex patterns and advertisements. The quantity of paper can be at 135~150 gram /m2. The weight of 25 x 20 x 15cm paper bags is up to 8~15 kg.

2, for all goods that need to be subjected to certain moisture, all waste paper can also be used. Only on the basis of the above criteria, adding a certain wet strength agent 0.5~1.0%, the wet strength can reach 10~15% dry strength.

3. For meat or other wet goods, the entire waste paper can also be used to make shopping bags. This needs to be added or coated with environmentally-friendly oil proofing agent in the process of paper making. Water soluble or degradable resins can be sprayed two times on the surface of the kraft liner board with good surface strength.

4, many manufacturers in mainland China have developed all waste paper reinforced paper. That is, when the paper is copied, the two layers of slurry are combined with the principle of textile to add water soluble yarn. The paper can reach the strength of four layers of kraft paper on one layer, and can completely replace the ordinary cement bag paper. Similarly, single paper can be used on a shopping bag.

5, these products are safe and environmentally friendly.

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