In the first segment of the documentary Addicted to Plastic (Chinese translation of "Plastic Addiction"), you may notice that during the series of actions from getting up to brushing your teeth, the actor was exposed to polyvinyl chloride, polyester, Polyurethane foam, low-density polyethylene, high-density polyethylene and polypropylene plastics for about two minutes. When you read this article, you can raise your head and look around. I dare say 95% of the readers will find at least five different plastics, such as ABS shell for computers, PVA polarizer on LCD screen, PVC insulation layer on wires, PF phenolic resin used in patch panels, PMMA gel pen at hand, and PP coffee cup held up consciously at present. Perhaps the lid is PS, ringtones from the PC shell phone ring in the ear......

Gosh, how many different kinds of plastic are we exposed to in a day? It's a big question, maybe a little boring, but it does affect every aspect of our lives. So our article is to meet the core members of the plastic family.

The plastic numbers.

In today's era of highly developed information, most housewives know that microwave heating uses No. 5 plastic. Many people subconsciously find a triangle when they get a plastic container, and then carefully identify the number. However, there are not many people who really understand these numbers, so many questions arise, such as whether No. 5 plastic is the safest. Therefore, to really make better use of plastic numbers to improve the quality of life, the first problem is to understand the meaning of plastic numbers.

The triangle on the plastic container can be found if you pay attention to it. It is actually a sign of recycling. The number in it is the mark of entering different recycling channels. In other words, for the recycling personnel, when he sees the number 1 marked on the plastic bottle, he knows that it should be recycled through channel 1, and the size of the number is not directly related to the nature of the plastic itself. Many "experts" on websites or TVs have suggested that plastic numbers represent the safety of plastics. The larger the number, the safer it is. They even say that it cannot be used below the 5th. This is a false thing-the number is not a plastic at all. Rating. Sometimes when I see such programs, I also find that if the experts are asked a lot by the host, they are obviously incoherent, so the untenable statement is untenable. One more word, although this rumor is very low in technology, it is very confusing. Many people who have read this statement will firmly remember this concept, because people will think that the size of this number must represent something, and safety It is obviously the most convincing, but unfortunately it backfires. The content of security is quite complex and cannot be summarized by a single number. We will talk about this topic in the next article.

At present, there are about 140 kinds of commercial varieties of plastics, and there are about 30 kinds of plastics for daily use, which can be described as a prosperous mending. Think of plastic relatives rubber and fiber, four glue (cis-butyl rubber, isoprene rubber, styrene-butadiene rubber, ethylene-propylene rubber) and four fiber (polyester, acrylic, nylon, vinylon) have already explained the regular members of the industry, the rest are generally marked with "special", compared with the number of regular plastic varieties is simply weak. However, among the many plastic varieties, there are usually seven kinds with large enough yield and unified recycling direction, which is why there are only seven numbers 1-7 in the triangle. Each number corresponds to a different plastic variety, followed by PET, HDPE, PVC, LDPE, PP, PS, PC. Each abbreviation has a "P", which means "Poly-" in English.

No.1

Soft transparent bottles and jars are almost the world of PET, beautiful and generous, low price

No. 1 plastic PET, scientific name polyethylene terephthalate, is also referred to as polyester plastic, very common in life, the current beverage bottles, edible oil bottles are almost all used in this plastic. If the molecular weight of PET is large enough, it can be used in the fiber industry, that is, polyester fiber, which is also the polyester fiber more commonly used now (shopping guides obviously know that it is too low-end to say that thousands of dollars of suits are polyester products). The use of silk also determines the recycling method of PET, and the vast majority of recycled beverage bottles enter the plastic rope industry. The outstanding characteristics of PET are high transparency, water resistance and oil resistance, but it is not very heat resistant. Many people should have a deep understanding of this. When the mineral water bottle is used to receive hot water from the water dispenser, the bottle begins to deform, and the temperature is about 85 degrees. However, PET can usually be carried below 80 degrees Celsius, so it is not surprising that No. 1 plastic is widely used in life. When it comes to PET, there is one more thing to add, that is, p-xylene PX, a chemical that has caused trouble in many cities. It is an important raw material for the production of PET, and it is also a raw material for many other important consumer goods. Its status in modern industry is similar to that of ethylene and propylene. Some interest groups do not want China to achieve self-sufficiency in p-xylene, so we should keep strengthening all kinds of alarmist talk about PX, and we should keep our eyes open.

No.2

Opaque hard bottles and jars are mostly HDPE, which is naturally suitable for daily chemical products with strong tolerance.

No. 2 plastic HDPE, scientific name high-density polyethylene, is the easiest to find their daily chemical containers in the bathroom, and many large beverage bottles also use this plastic. The obvious difference with PET is that because this plastic is highly crystalline, it also appears opaque in appearance (polymer materials are different from diamonds, and high crystallinity tends to reduce transparency), and the hardness is also higher, even a little brittle. It is precisely because of high strength, not afraid of falling and opaque, dairy products often prefer No. 2 plastic. This plastic water and oil resistance are very good, so the adaptability is very wide. Similar to PET, No. 2 plastic is not very heat-resistant, but slightly stronger than PET, generally more than 100 degrees Celsius will be easily deformed. This kind of plastic is also especially acid, alkali and corrosion resistant. If fluoroplastic, a Boss-grade super corrosion-resistant plastic, is not invited out, it can basically kill other materials. Therefore, it is also widely used in industry. Therefore, polyethylene industry is an industry that cannot be ignored in any industrial country.

No.3

Everyone does not like PVC for food, in fact, the most valuable use of PVC is not the food industry, PVC artificial leather, although not breathable, but cheap

No. 3 plastic PVC, the scientific name polyvinyl chloride, is also the only plastic in the seven major plastics that does not recommend contact with food because it contains chlorine. But in fact, under normal conditions of use, the chlorine in the material is not easy to free up, although No. 3 plastic is rarely seen in food containers. PVC is also the only material in the seven major plastics that must use plasticizers, which makes it possible to change its state from soft and elastic to hard and brittle. The plasticizer is the "plasticizer" in the media report. It is a material that has been criticized in the food industry, but we will explain the facts in the future. Since PVC can present a soft and elastic side, it can also simulate some uses of rubber or leather, such as artificial leather, disposable inspection gloves, floors, tablecloths, and plastic shoes used in the interiors of Japanese cars, because the price of PVC is much lower than that of natural rubber and polyurethane artificial leather. However, the PVC industry usually uses acetylene, so as a high energy-consuming industry, it still faces many crises, which means that in the future we may only face PVC with good price and low price.

No.4

LDPE's preservation ability is not strong, but it is still one of the most ideal materials for plastic wrap

No. 4 plastic LDPE, and No. 2 plastic are brothers, scientific name low density polyethylene. However, in essence, the structures of Nos. 2 and 4 are not the same, except that ethylene is used as the monomer. No. 4 plastic rarely appears in the container, because it is very soft and somewhat sticky, and because the crystallinity is very low, the transparency of LDPE is relatively high, so we can see it mainly in plastic wrap, plastic bags and so on in our daily life. However, this kind of plastic has relatively low oil resistance, and there are many such examples in life. For example, when eating sheep scorpions, PE gloves are worn. Although the gloves do not have pores, they still feel greasy. Or bought red oil pig ears and packed them in plastic bags, threw them into bed and started playing with the computer. A few hours later, it was found that the sheets should be changed. Therefore, the use of such plastics in food products is relatively limited. However, No. 4 plastic in industry is still very awe-inspiring, and it is a well-deserved overlord in the film industry.

No.5

PP is a kind of plastic that is very pleasing to people. Its combination with microwave oven can solve the diet problem of otaku and otaku with non-instant noodles and ham sausage.

No. 5 plastic PP is our star plastic polypropylene, the most common is the lock. At present, the vast majority of plastic containers for microwave ovens on the market are PP plastic, because of its high heat resistance and chemical stability. This kind of plastic is actually very close to No. 2 plastic in essence, and the crystallinity is slightly lower than No. 2, so it is generally translucent, and the hardness is not much different from No. 2. The application of No. 5 plastic in food is more than any other plastic. In addition to containers, there are also BOPP films in flexible packaging. The outermost film of cigarette boxes is this plastic. In addition, the current household water pipes commonly used in new residential areas are recommend or forced to use PPR pipes, which are also polypropylene materials. In addition to safety considerations, they are also easy to process because of their hot melt characteristics. The polypropylene industry is also a standard to measure the level of a country's industry.

No.6

Don't think PS lunch boxes are low-grade, at least they can keep some small restaurants serving the bottom alive.

No. 6 plastic PS, scientific name polystyrene, is a legendary plastic. Once upon a time, No. 6 plastic was all over the world, especially on both sides of China's railways, but nearly 20 years have passed, and many people have forgotten the "white pollution" at that time ". Today, the important use of No. 6 plastic is still foamed plastic. Polystyrene board in home decoration refers to this kind of plastic, but its position in food has been reduced a lot. Generally, it is still widely used in the outer packaging of instant noodles and family barrels. Of course, foam lunch boxes are also used, but many people refuse to use them. It should be noted that No.6 plastic itself is transparent. If you are bored to study disposable beverage cups on the plane, you can find that No.6 plastic is mostly used. Of course, if you drink hot drinks such as coffee or tea, you will only observe paper cups or No.5 plastic.

No.7

PC is a very beautiful plastic, and it is quite strong. Mom doesn't have to worry about the cup being broken when she uses it again.

No. 7 plastic PC does not refer to personal computers, but polycarbonate, but it is related to personal computers. Many computer shells are PC plastic. Some places say that No. 7 represents "other plastics", which is actually true, but because of the widespread use of PC, No. 7 plastic is now basically equivalent to polycarbonate plastic. Different from the above plastics, PC is born "noble". It is not a general plastic, but an engineering plastic. You can know that this guy has excellent physical properties by name. In terms of electrical housings, PC and another engineering plastic ABS occupy the mainstream market. In the food industry, the most common ones are space cups, drinking water machine barrels and milk bottles. Its outstanding feature is high strength, not to mention that it can't be broken. A better PC shell can't be stepped on. The famous walnut shell-opening brand Nokia should have felt it for a long time, while the appearance of iPhone5C makes this plastic show its face again.

Plastic without a number.

The output of some plastics is relatively low or the recycling channels are not uniform, so there is no definite number. Although there is no account, some of them also deeply affect our lives. Let's feel it together--

No.8

Acrylic is the artist in plastics. It has a unique interpretation of light, but it is not as aggressive as glass.

PMMA, scientific name polymethyl methacrylate, it has a resounding name called plexiglass. There is a large category of plastics called "acrylic", which is a transliteration of acrylic resin (Acrylics), and PMMA is the most representative material in acrylic resin. PMMA is a great revolution in the material industry, because the excellent refractive index and strength of glass are similar to those of crystal, so in the more than 1,000 years since its birth, no material has ever challenged glass, only PMMA. Moreover, this plastic is light in weight, good in strength, high in refractive index, no sharp objects after being broken, and good in heat and cold resistance. Apart from poor solvent resistance and easy scratching on the surface, it can be described as perfect. Therefore, the development of acrylic (not specifically a PMMA) now not only in the industrial materials to replace the glass, including food packaging, including many uses, in the arts and crafts also has a prominent application, curtain and chandeliers on the common artificial gems, oil painting in the "propylene" are acrylic materials.

No.9

To commemorate the forgotten 1115 Shanghai fire, they say the culprit is PU, isn't it themselves

PU, the scientific name polyurethane, is another material that many people have become familiar with in recent years, especially after the Shanghai fire, many people attribute the reason to polyurethane insulation materials. Although we, as fans of polyurethane, feel aggrieved and think that fire is a man-made disaster, flame retardant polyurethane has long been available. Polyurethane is also a large class of materials, according to the raw material can adjust the structure, can be very soft, no different from rubber, but also very hard, similar to stone. Thermal insulation material is a major use of polyurethane, which also needs to be treated by foaming process, not only for houses, but also for the inner layer of refrigerators. Another major use is artificial leather. So far, PU leather is the material closest to real leather. Therefore, polyurethane is widely used in the interior decoration of most German cars. Who makes the largest manufacturer Bayer of Germany. However, in food, polyurethane is not very commonly used. It is not very resistant to water and oil, which is a major shortcoming.

No.10

People do not know ABS, look at plastic is also in vain, three kinds of raw materials, but also to retain their respective advantages is not easy

ABS, the scientific name acrylonitrile-butadiene-styrene resin, is the same as the abbreviation of the anti-lock brake system. This is also a small number of plastics without "P" in the abbreviation. Of course, this does not hinder the fact that it is a polymer. It is made by copolymerizing several different monomers-acrylonitrile (A), butadiene (B) and styrene (S). Acrylonitrile is the main raw material for the production of acrylic fiber, butadiene is the main raw material for the production of butadiene rubber, and styrene is the main raw material of No. 6 plastic PS, so ABS is like genetically modified plastic, implanted with some of the characteristics of rubber genes and fiber genes. Such a structure makes ABS have the comprehensive properties of the three major materials, high strength, good toughness, and it is not surprising that it is used in engineering plastics. Some of the fields that are seen daily are mainly household plastic appliances, electrical appliances and toys.

No.11

PA is also an evergreen tree in the plastics and fiber industry, playing a strong and dead image for decades.

PA, the scientific name polyamide, also has a domineering name called nylon. If silk stockings are made again, it will be enough to make most men's blood boil, but in fact the name of silk stockings has little intersection with delicate silk. Nylon across the plastic and fiber two industries, in the fiber it also has a name called nylon. The most powerful feature of this material is its ultra-high strength, so it can be competent for many metal jobs. For example, the lightweight of modern auto (not for showing English, but for not specifically referring to a certain car brand) is largely due to PA. At the current rate of development, aluminum alloys will be replaced by PA in major areas in the coming decades, including aircraft manufacturing. It should be noted that PAM and polyacrylamide are also easily confused with PA, which are far from each other, although the names and abbreviations are very close.

No.12

If you want to introduce PI, what is the most appropriate than rocket missiles?

PI, the scientific name polyimide, is not a large amount of plastic, but it is a plastic that must not be ignored. This plastic is not afraid of heat and can hold up to 600 degrees Celsius, so it can be used for components in rockets or missiles. This plastic is not afraid of cold and has toughness in liquid helium. This plastic is extremely strong and stronger than nylon. This plastic has excellent insulation, so people majoring in electronics should be familiar with films made of this material. All of these are due to its special trapezoidal molecular structure. The only drawback is that it is expensive. It is conceivable how this material will cross the material world if the cost is reduced one day. Because it also has the characteristics of extreme inertness and high strength, some microwave cutlery also uses it as a raw material.

No.13

The non-stick pan is just a trick played by the plastic king. The industry has long been very mature in using PTFE to make non-stick kettle and non-stick pipe.

The king is always used for the finale, so the last one to appear should be PTFE, scientific name polytetrafluoroethylene, trade name Teflon, in daily life, non-stick pan has its figure. Teflon is one of the fluorine plastics, but also the most important one, in the industry has a "plastic king" reputation. Frankly speaking, the strength of Teflon is not high, compared with nylon or something, it is simply slag, but in addition, Teflon shows outstanding performance in heat resistance and cold resistance, and in terms of corrosion resistance, it is a well-deserved king. The general acid and alkali are pediatrics for it, and even aqua regia can do nothing for it. In addition, it repels both oil and water, so when using a non-stick pan, it can be seen that both oil and water will exist in the form of liquid beads. People familiar with physics understand that this is caused by surface tension. Therefore, Teflon is also widely used in industry, especially for pipelines and reaction equipment in chemical industry, equipment made of Teflon will not corrode and is easy to clean, naturally, it is very popular, but the price is still relatively high.

In addition to the above, there are many plastics used in daily life. The more important ones are PLA polylactic acid, EVA ethylene-vinyl acetate copolymer, POM polyoxymethylene, PF phenolic resin, EP epoxy resin (P in PF and EP are not abbreviations of Poly-), MF melamine resin (imitation porcelain tableware), etc. In addition, from the structure, carbon fiber is also a polymer material, can also be regarded as plastic. Each kind of plastic has its own wonderful story, but for non-professionals, it is enough to use it. Professional knowledge is too boring.