Comparison of physical properties of POF and PE and PVC shrink film
1.What is shrink wrap made of?
Heat shrink film is widely used in the outer packaging of food and beverage, pharmaceutical industry, construction industry, etc.
Its function is to effectively protect the packaged products through strong contraction force to achieve dust-proof, moisture-proof, anti-collision, and anti-loose effects, and to improve the grade of the product.
The root of shrink film roll is plastic products. Most plastics are high molecular polymers formed by polymerization of by-products refined from fossil raw materials such as petroleum.
Thermoplastics, such as synthetic resins in polyolefin systems, are direct products of the petrochemical industry. The so-called polyolefin plastic is a general term for plastics whose monomers are olefins. The material of plastic flexible packaging is a base material processed from petroleum by-products. Such as BOPP, CPP, CPE, IPE, LDPE, PET, PP, NY, toluene, ink, glue, and other materials are all closely related to petroleum.
The common heat-shrinkable films in the market are as follows: POF.PE.PVC.PET and so on. Each type has its place in the market due to its price and performance.
2.What is PVC shrink film?
Once as the world’s largest general-purpose plastics, we have to mention PVC.
Although it was included in the list of 3 types of carcinogens in the 2017 World Health Organization’s International Agency for Research on Cancer list, PVC still has an unshakable status due to its wide range of uses and low prices.
The full name of PVC is Polyvinyl chloride, which is the product of the polymerization of polyethylene monomers by free radicals. It is an amorphous polymer with a small amount of crystalline structure that uses one chlorine atom to replace one hydrogen atom. It was first discovered in the 19th century. In 1912, Germany applied for a patent but did not develop PVC products. It was not until 1926 that the American B.F. Goodrich Company successfully synthesized PVC and obtained a wide range of commercial applications.
The color of PVC particles is yellowish translucent and shiny. The transparency is worse than that of polystyrene. According to the number of additives, it can be divided into soft and hard polyvinyl chloride. Soft products are soft and tough, and feel sticky; the hardness of hard products is higher than that of low-density polyethylene but lower than polypropylene, and whitening will occur at the inflection. Hard products are stable and not easily corroded by acid and alkali, and have good heat resistance. Polyvinyl chloride can be made by the chemical reaction after the substitution of ethylene, chlorine, and catalyst.
Because of its heat resistance and fire resistance, it is widely used in products in various industries: wire sheaths in the electrical industry, handbags, and shoes, construction and furniture industries, children’s toys, medical aids, cleaning gloves, and shrink film and preservation bags.
PVC heat shrinkable film is a kind of film made of ethylene-based PVC resin and more than ten kinds of auxiliary materials after secondary inflation. It is widely used in the packaging of food and medicine, stationery toys, basic building materials, daily necessities, and other products.
3.PVC shrink film density
The density of PVC shrink film is 1.22-1.38 g/cm3, which is calculated according to 1.4 g/cm3 in the industry.And the softness will be lower. Opaque will be higher. PVC shrink film can be made into a monolithic film, double-folded film, tube bag according to requirements.
PVC shrink film has the following advantages:
- Good transparency, uniform thickness, no impurities, smooth film surface without spots. Therefore, the appearance of the packaged product can be seen. The categories are complete, and various colors can be made according to requirements to enhance the visual effect of the product to achieve the purpose of promotion and make the product more in line with the promotion image.
- The heat shrinkage rate is higher than that of other materials. The transverse shrinkage rate is about 48%, and the longitudinal shrinkage rate is only about 12%. Therefore, in addition to the heat shrink packaging machine, you can also use the common hair dryer in family life to shrink. Thereby saving cost and energy.
- The elasticity is high, and it can be tightly packaged for any geometric shape. At the same time, it has good flexibility and will not cause damage to the product during the strapping process. After packaging, even if the product is dropped from a height of 1 meter, there will be no cracking.
- PVC film can produce products with single-sided adhesiveness, which can reduce the harsh noise emitted during the winding process.
- Low price.
PVC shrink film has the following disadvantages:
- Environmental protection: PVC is toxic and will produce unpleasant odors and toxic gases during processing. Today, when environmental protection is paramount, the proportion of PVC is greatly reduced.
- Resistance: PVC has very poor cold resistance due to its high shrinkage rate. In winter with low temperatures or after freezing, it will become brittle and fracture. In the same way, the heat resistance of PVC shrink film is also poor, and the surface is easy to crack after sun exposure.
- Safety: PVC shrink film feels brittle. After shrinking, the four corners are hard and sharp, and there is a risk of cuts.
- The PVC heat shrinkable film is easy to be broken during printing.
4.What is POF material?
POF shrink film (Polyolefin oriented film), also called BOPE shrink film (bi-oriented polyethylene film), is a kind of shrink film obtained by bi-directional stretching of polyolefin by the double bubble method. Compared with traditional polyethylene blown film shrink film, POF shrink film has excellent mechanical properties, good transparency, and uniform shrinkage in vertical and horizontal directions. Generally, POF shrink films are divided into two categories, ordinary POF and cross-linked POF.
Due to the poor tensile properties of PP in the melt state, the traditional blow molding process cannot be used. Instead, the double-film bubble process is used, also known as the Pulandi process in the world, which melts and extrudes the raw materials through different extruders. The designed co-extrusion die head is quenched after the initial film is formed, and then heated and expanded twice to make the product.
POF film is a new type of environmentally friendly shrink film produced in response to market requirements. It has developed rapidly and is almost the most widely used packaging material on the market. The compatibility of the packaging is very strong, and almost all regular and irregular products can be packaged.
5.Polyolefin shrink film properties
The density of POF is 0.92, and the thinnest thickness can reach 0.012mm. POF shrink film can be manufactured into monolithic film, double-folded film, tube bag according to requirements.
POF shrink film has the following advantages:
- Environmental protection: POF is non-toxic and will not produce toxic gas after processing. All are made of environmentally friendly raw materials, in line with the US FDA and USDA standards, suitable for the food industry and the pharmaceutical industry, and can be recycled and reused.
- Physical properties: POF shrink film is not only thin but also tough, 15 micron POF film can reach about 450 toughness; soft texture but high tensile strength, 15 micron POF film tensile strength is about 100-110; The tear strength is large, so the moisture resistance is good. At the same time, because of the existence of LLDPE, its rub resistance is much higher than other shrink films.
- The density is lower than that of 1.4 specific gravity PE and PVC films, which can reduce packaging costs and save expenses for enterprises.
- With high gloss and transparency, POF’s high-end series also have cross-linked films. For companies pursuing high-quality, POF shrink films are more beautiful and generous and enhance corporate image.
- Excellent cold and heat resistance. It can remain unbreakable at a low temperature of minus 50 degrees, suitable for packaging of frozen products. At the same time, the POF shrink film can be treated with anti-fogging, even if it is stored for a long time at low temperature, it will not pollute dust and keep the product bright and tidy.
- It is more suitable for packaging lines. This is because POF does not produce moisture during processing, so it has good smoothness and is suitable for automatic packaging on high-speed production lines.
- Safety: The four corners of the POF are still soft after shrink packaging, and there will be no cuts.
If the shortcomings of POF, then I think it is because POF has a low specific gravity, so the film is very thin, which is not suitable for heavy products.
6.POF vs PVC shrink film
1. Different definitions: this can be concluded from the article
2. Different uses:
The price of PVC is very cheap and the output is very high. It has the characteristics of rainproof, fireproof, antistatic and easy to shape, and is widely used in the building materials industry and packaging industry.
POF is a tear-resistant heat-shrinkable film. It is currently widely used internationally and is an environmentally friendly heat-shrinkable packaging material recognized by the European and American markets. It complies with the US FDA and USDA standards, and is made of environmentally friendly materials. It is an environmentally friendly packaging material that can be recycled and reused. Especially suitable for the pharmaceutical industry and the food industry. The product meets the requirements of “GMP”. It has a soft texture. It has high tensile strength, high tear resistance, and adjustable shrinkage. It is suitable for automatic high-speed packaging machines. It is widely used in plastic beverage supplies, office supplies, books, electronic products, photo frames, washing supplies, Cosmetics, dairy products, video tapes and other products.
3. Adapt to different temperatures:
PVC is poor in cold resistance and may break during transportation, and embrittlement in cold weather. The packaging is easy to deform after a long time. It has poor antistatic ability and is easy to contaminate dust, which makes the product contaminated. POF has excellent cold resistance. , -50℃ is not hard, not brittle, not easy to break.
4. Environmental protection is different:
Compared with PVC film, it is environmentally friendly, non-toxic, degradable, and does not produce toxic gas during heat sealing.
5. Different security:
Compared with PVC film, the four corners of POF shrink film are softer and will not cut the skin after shrinking.
7.What is PE material?
Let’s first understand the raw material of PE film, that is, polyethylene, which is a thermoplastic resin made by polymerization of ethylene. Polyethylene appears as a colorless liquid in the state of low molecular weight, and appears as colorless or milky white waxy particles or powder in the state of high molecular weight. It is non-toxic and has good low temperature resistance. Excellent electrical insulation and low water absorption.
Polyethylene was synthesized by the British ICI company in 1922, and in the following years, it was successively obtained by the United Kingdom and Germany through high-pressure and low-pressure methods. Until 1977, Union Carbide and The Dow Chemical Company used low-pressure methods to make low-density polyethylene, called linear low-density polyethylene, of which Union Carbide’s gas phase method was the most important. Linear low-density polyethylene has similar properties to low-density polyethylene, but also has several characteristics of high-density polyethylene. In addition, it has low energy consumption in production, so it has developed extremely rapidly and has become one of the most eye-catching new synthetic resins.
Polyethylene can be divided into HDPE, LDPE and LLDPE because of its polymerization method, chain structure and molecular weight. Commonly used in industrial packaging films, building materials, wires and cables, large and small pipes, etc.
According to the polymerization pressure, polyethylene can be divided into low pressure method, medium pressure method and high pressure method. The low-pressure method is divided into three types: slurry method, solution method and gas-phase method. The main applications are injection-molded products and hollow products; the medium-pressure method uses a chromium-based catalyst supported on silica gel in a loop reactor. Polymerize ethylene under medium pressure to produce high density polyethylene. The high-pressure method uses oxygen or peroxide as an initiator to polymerize ethylene into low-density polyethylene. Among them, more than half of high-pressure polyethylene is used for film products, followed by pipes, injection molded products, and wire wraps.
Because of its strong adhesion, PE shrink film is often used for manual winding or machine winding, and becomes a stretch film in the industry. It is common in winding protection before the machine is shipped and winding of some large industrial products.
8.Features of PE film
The main component of PE film is polyethylene, followed by silica, pigments, anti-ultraviolet agents and antistatic agents, etc. It is a surface protective film, commonly used for manual stretch film, machine stretch film and some heavyweight The packaging of products is mostly used for collective packaging, such as: beverages, cloth, ceramic tiles, building materials, etc.
Polyethylene shrink film has the following advantages:
- With good self-adhesiveness and winding power, the packaged product can be compactly fixed as a strapping unit, and it will not loosen easily even under adverse conditions. In addition, the shrinkage and tightness of the PE film is good, and the product will become stronger and stronger during the packaging process.
- Reduce costs: The traditional packaging methods are mostly carton packaging. The use of stretch film for packaging can effectively reduce the cost of use and reduce the labor intensity of workers.
- Good tensile strength and tear resistance, good sealing and shrinkage. Therefore, when used in heavy packaging, it has good impact resistance and makes the product difficult to damage. With high impact strength and firm sealing, it has the indispensable characteristics of heavy-duty packaging, so it is mostly used for transportation and packaging of large items, and at the same time plays a role of moisture and dust prevention.
- Good water resistance and low temperature resistance, which can meet the needs of cold storage. Excellent cold resistance. After winter or freezing, it will not harden or become brittle, so it is not easy to break during transportation. It has static elimination treatment, which is not easy to stain and can keep the product clean.
PE packaging film has the following shortcomings:
- Poor gloss and transparency: Due to the large overall thickness of the PE film and its own material composition, its appearance is poor in visibility, which is not conducive to the packaging of some high-end products.
- Low melting point and poor high temperature resistance.
- Poor oil resistance.
9.PE shrink film vs POF shrink film
1. Different application areas:
PE heat shrinkable film is widely used in the entire assembly packaging of beverages, various dairy products and other products. The product has good flexibility, impact resistance, strong tear resistance, is not easy to break, is not afraid of moisture, and has a large shrinkage rate.
The application potential in the POF field is quite huge.
1) Cultural and educational supplies-books, photo albums, pens and inkstones, etc.
2) Handicrafts-plaster statues, vases, stone carvings, etc.; 3) Electrical appliances-dry batteries, batteries, meters, switches, electronic components, etc.; 4) Hardware-such as mechanical parts, small machinery, tools, etc.; 5) Communication equipment-such as Telephone, fax machine, etc.; 6) Other products such as medicine, food, tobacco and alcohol, ceramics, paper, glass products, etc.
2. The shrinkage rate is different
The shrinkage rate of POF heat shrinkable film is large, up to 75%, and it has good flexibility and can be used for packaging any shape of goods. Moreover, the shrinkage rate of the five-layer co-extruded POF heat shrinkable film treated by a special process is controllable to meet different products. Packaging requirements for shrinkage; good welding performance, high strength, suitable for manual, semi-automatic and high-speed automatic packaging, shrinking temperature: 130-150 degrees
The shrinkage rate of PE heat-shrinkable film is 10%-30% horizontally and 30%-50% vertically. It is widely used in the whole assembly packaging of wine, cans, mineral water, various beverages, cloth and other products. The product is flexible Good performance, strong impact resistance, tear resistance, not easy to break, not afraid of moisture, shrinkage temperature is about 200 degrees