PVC waterproof bags are the mainstream in the market. How should we choose them? Because it's cheap or something else?
Thefull English name of PVC is the abbreviation of polyvinylchloride (PVCmolecular structure). Generally speaking, our common PVC is a kind ofplastic decorative materials. Its chemical name is polyvinyl chloride.It is composed of amorphous thermoplastic resin made of vinyl chloridemonomer through polymerization and certain additives (such asstabilizer, lubricant, filler, etc.). It has mechanical properties,strong acid and alkali resistance and low softening point. Stablechemical properties. It is often used to make thin plates, wires, cableinsulation, seals and other items.
Classification of outdoor waterproof bags:
Material upper division
Pvc/tpu/eva, mainly these.
PVCwaterproof bags are mostly PVC waterproof bags on the market, which arecheap and mainly adopt snap on type, anti splashing zipper and foldingroll opening. Generally, it is difficult to integrate with watertightand air tight zippers. Even if they are integrated, the viscosity isinsufficient.
TPU waterproof bags on the market are generallyexpensive. They are environment-friendly materials and can be easilyexported to Europe and the United States. They have all kinds ofopenings. However, if waterproof zipper openings are used, they do notmatch and are of lower grade.
EVA waterproof bags made of EVA are rare in the market. They are mainly used in some swimming bags, and the price is medium.
Snap open waterproof bag
Division on opening
Folding roll opening, zipper opening, snap type, magnetic suction type
1.the waterproof bag with folded mouth is the most early choice. If youwant to seal the roll mouth, you must ensure the long-term extrusionforce. However, in fact, the waterproof bag has both extrusion force andrebound force. The fabric difference, including the hardness andelasticity of the fabric and the tension generated after folding withthe roll mouth, will affect the durability. Generally, the ipx6/7waterproof level can be maintained within 30 minutes. It will relax for alonger time, and the waterproof ability will be lost. It is mainlyapplied to waterproof bags with low price and low waterproofrequirements.
Magnetic sealing waterproof bag
2.snap on waterproof bag is a small waterproof bag, such as mobile phonewaterproof bag and transparent waterproof bag, which are often used. Themale and female fastener combination of injection molding is adopted,and the fastener is welded on the opening of the waterproof bag toachieve the purpose of sealing through fastening. It is mainly used insmall bags such as waterproof bags for mobile phones and digitalproducts.
3. the waterproof bag with magnetic suction openingis a new opening method developed in recent years. Its practicalityneeds to be further verified. It needs to be evaluated in terms of thestrength of the magnetic force, the hardness of the contact surface, andthe impact of the magnetic force on the electronic products in thestorage. It is mainly used in mobile phone waterproof bags, digitalproduct waterproof bags and other small bags.
4. zipperopenings are more and more widely used. The technology of waterproofzippers such as air tight zippers and water tight zippers is becomingmore and more mature. Great progress has been made in process, sealing,stability, durability, smoothness and matching. Waterproof zipperopenings have been adopted in many high-end bags, greatly improving theconvenience and practicality of use. The zipper opening is consistentwith people's use habits. It is easy to operate, reduces the user'slearning cost, and saves the user's time for picking up items andsorting out. It can be applied to most bags.
Roll type waterproof bag for bicycle
Division on usage scene
Bicycle bag, swimming bag, urban leisure bag, outdoor mountaineering bag, diving bag, fishing bag, etc.
What are the names of PVC waterproof fabrics?
Waterproof oilcloth, knife scraping cloth, PVC laminating cloth, PVC mesh cloth
PVCsandwich fabric (waterproof fabric) has serious high-frequency weldingoverflow, some of which are even more than 2mm. The appearance wasseriously affected, and there was no appearance.
In addition to the irregular overflow, it is more than 3mm, shilt. I really didn't see it.
Problems encountered in PVC waterproof fabric processing
1.the material is difficult to process, so we have to choose thick glue,which increases the weight, increases the overflow, and destroys thebeauty
2. due to poor adhesion, the welding time and strength have to be increased or the voltage width has to be widened,
3.it is difficult to fuse with other materials. Even if it is fused, itsadhesion is weak, and there is a great risk of peeling in use.
Compared with TPU, PVC waterproof fabric is relatively simple and rough, not so delicate and elegant.
The effect of welding with the anti water splashing zipper can only be summarized in one word: terrible.
The waterproof and water splashing zipper is not pressed well, too hasty!
PVC is the main waterproof package in the domestic market.
Therefore,it is necessary to talk about environmental protection andresponsibility to the earth. Many inferior products are flooding themarket. Although it is said that everyone is greedy for cheap, it is notcost-effective to compare the service life of the product with theprice. In addition to the social requirements to reduce environmentalpollution, the living space of low-quality waterproof bags isincreasingly under pressure.
Whenthe sun shines directly on PVC fabric, it may release unpleasant smell,which will bring obvious discomfort to sensitive people.
Problems in the use experience of PVC waterproof bag, private
Feeling:the weight increases the burden, the hand feels sticky, there is aplastic or irritating smell, and it is easy to get dirty and difficultto clean.
Service life: the service life is short. Some smallbags have a one-time service life. For example, PVC mobile phonewaterproof bags have small cracks after pulling at the seams, so thereis a huge risk of reuse; Large bags, such as PVC rock climbing bags,mountaineering bags, double shoulder waterproof backpacks and bicyclebackpacks, have been torn at the seams for about a year, more or less.The reverse tearing of PVC fabric is easy to occur, mainly due to itsinsufficient adhesion and elasticity. This physical property makes itmuch weaker than TPU waterproof fabric.
Damage to the earth caused by the scrapping of PVC waterproof package, Yu Gong
"PVC is a fighter among toxic plastics. Fromproduction, consumption and use to final disposal, it is endangeringthe environment and human health." Stabilizers (such as lead andcadmium) and plasticizers (phthalates, such as DEHP) that need to beadded when PVC is made into various products after synthesis.
Aswell as the hydrochloric acid and the century's toxic dioxin producedby the combustion after waste, they are all harmful substances with alarge origin.
Jia Mingxing, vice president and SecretaryGeneral of China Nonferrous Metals Industry Association, said, "theproduction of PVC with an annual output of tens of millions of tons inChina is inseparable from mercury catalyst".
Due to the lackof oil resources in China, PVC is mostly produced by calcium carbidemethod. The mercury catalyst in the production process of vinyl chlorideby calcium carbide method is the main source of mercury pollution andflows to the environment in various ways .
According tostatistics, China consumes 20% of the world's Mercury, of which about60% is used for PVC production by calcium carbide process. 
Onthe other hand, PVC production is a high energy consuming industry andinvolves a variety of toxic chemicals, including dichloroethane, vinylchloride, mercury pollution, etc. once an explosion or leakage occurs,it will pose a great threat to the health of workers in the vinylchloride plant and the nearby people.
PVC use - health hazard
Inthe process of PVC production and processing, some processing aids needto be added, such as fillers, stabilizers, lubricants, plasticizers,colorants and flame retardants. Among them, the use of stabilizer andplasticizer is very high. 
Before PVC is made into variousfinished products, plasticizers of different contents shall be addedaccording to the softness required by the products. Generally speaking,10-30% plasticizer shall be added to semi-rigid PVC and 30-70%plasticizer shall be added to soft PVC.
For example, theaverage plasticizer content of medical supplies is 20%-40%. If it islike fresh-keeping film, drip tube or drip bag, the plasticizer contentcan reach more than 70%, which is equivalent to PVC immersed inplasticizer.
There are many kinds of PVC plasticizers, but the most common one is a class of chemicals called phthalates.
"Phthalatesand their metabolites and degradation products have negative effects onhuman health, such as endocrine disrupting effects, feminization of usein boys and precocious puberty in girls."
On the other hand,PVC is not resistant to light and heat. Under the influence of lightand heat, it will release chlorine free radicals, resulting in materialdeterioration. In order to improve the thermal stability of PVC, anappropriate amount of stabilizer is often added to prevent or slow downthe degradation of PVC during processing.
The pollution caused by stabilizers is mainly heavy metal pollution.
Commonlyused stabilizers include metal salts such as lead, cadmium, zinc,barium and tin, which will seep out from PVC products and endanger humanhealth.
"Lead, a commonly used stabilizer, can damagechildren's nervous system and hinder their IQ development; it can damagethe female reproductive system and may cause cancer. Cadmium can affectrenal function."
The third item is the physicochemical properties and common use of PVC
Waste disposal - Deadly relics
Non environmentally friendly materials
PVCwastes are difficult to handle. As they often contain plasticizers andheavy metals, if they are mixed with recycled plastics, they willpollute the recycled plastics and turn the circular economy into a toxiccycle.
At the same time, as PVC contains chlorine, ifburned, it will not only release pungent and toxic hydrogen chloridegas, but also produce strong carcinogen - dioxin.
There arealso environmental problems in the process of PVC waste landfilling. Forexample, a large number of untreated PVC piled up may cause combustion.In case of occasional fire in the landfill, the PVC waste in thelandfill will burn to produce dioxins; Containers containing severalplastic mixtures may leak lead containing stabilizers.
"The waste treatment of PVC seriously hinders the benign operation of waste classification and recycling system in China."