Polyethylene Terephthalate (PET): Production, Price, Market and its Properties

 

What is Polyethylene Terephthalate (PET)?

Polyethylene Terephthalate commonly known as PET or PETE is the mostly used polymer in the world. It is naturally transparent and semi-crystalline plastic used widely for products used in our day to day life. PET polymer is better termed as “Polyester” in the textile industry. It is widely used as a fiber for clothing as it is an excellent moisture barrier and also used for bottling and packaging on large scale. The major share of PET plastic produced comprises of synthetic fiber (up to 60%) and remaining 30% is for bottle production of the total global demand.

PET material consists of polymerized units of monomer ethylene terephthalate and when these PET materials are combined with other materials such as glass fiber or carbon nanotubes their strength increases. As a raw material, PET is regarded as a safe, strong, lightweight, flexible and non-toxic material which can be easily recycled.

PET plastic has become the world’s choice in the packaging sector. It is prominently used for packaging of many food and beverages as it is hygienic, strong, lightweight, retains the freshness of the products and does not shatter. It is most commonly used for packaging of water and carbonated soft drinks. PET containers can be easily identified through the triangular resin identification code found on the PET containers (Bottles or Jars).

 

PET Resin Price And Trends

 

History of PET Resin

Today Polyethylene Terephthalate (PET) has become one of the most widely used, versatile and trusted plastic material in the world. More than half of world’ synthetic fiber and bottles demand is fulfilled by PETplastics. PET was first prepared in The United States by the mid of the 1940s when the researchers were searching for the polymer that could be used to make new textile polymers. Later, these polyesters were branded as “Dacron” by DuPont.

Further, in late 1950s researchers found a way to stretch the thin extruded sheet of PET to create films which are now extensively used as X-ray or photographic films. Till the 1970s, a new technology was built to mold PET into strong and lightweight bottles and in 1977 PET bottles produced were now also recycled.

 

Production of PET Resin

Polyethylene Terephthalate (PET) is basically produced by polymerization of ethylene glycol and terephthalic acid. Ethylene glycol and terephthalic acid are regarded as building blocks for PET resin. Further, these resins are heated to a molten liquid which can be easily molded into items of any shape. The presence of large benzene rings in the process of adds stiffness and strength to PET polymer, especially when polymer chains align with each other.

To be more specific, when the two raw materials of PET- ethylene glycol and terephthalic acid are combined with low vacuum pressure and high temperatures long chains of the polymer are formed. As mixture thickens, longer chains are formed and the process is stopped when the appropriate chain is achieved. Further, when PET polymer is held in starched form at different temperatures it starts to crystallize and become opaque and more rigid. This crystallized form of PET is used to prepare further products such as containers and trays which can also be reheated.

 

World PET Resin Production and Market

 

World PET Resin Production

The world PET resin production capacity was 30.3 million tons in 2017. The global production was dominated by China which accounted for 30.8% of the total PET polymer production. The Asian region excluding China accounted for 21% of the production share.

The North American region had a share of 16.9% with the United States leading producing country. The new PET plant by MG Chemical of Corpus Christi, Texas US is of world scale with the production capacity of 1.1 million tons per year.

The European region accounted for 14.7% of the total PET production capacity followed by Middle East (10.2%), South America (4.1%) and Africa (2.3%)

Polyethylene Terephthalate Production

The production of PET polymer is dominated by few companies. Indorama Ventures was the largest producer of PET polymer globally with an installed production capacity of 4.2 million tons in 2017. The other leading companies are MG Chemical with an installed capacity of 2.7 million tons, Zhejiang Yisheng Petrochemical Co. (2.5 million tons), Sang Fang Xiang (2.1 million tons) and DAK America (1.8 million tons).

 

Market of PET Resin

China is not only the world’s biggest producer of PET resin but the biggest consumer also. The PET resin market is driven by bottled beverages sector and films and sheets. The market for PET resin including rPET was 23.5 million tons in 2016.

The market by end-segment was dominated by Bottled Water which cornered a share of 26.3%. It just surpassed Carbonated Soft Drink (CSD) bottles which occupied a share of 26.1% of PET resin. The shift in consuming more bottled water than carbonated soft drink is because the consumer is becoming more health conscious and reducing the sugar consumption.

The other major sectors which consumed PET resin was film and sheet (13.8%), Food (9.1%) and Non-Food (6.1%)

PET packaging is expected to grow in coming years as it is increasingly being used as replacement of glass and metal containers.  The driving factor for use of PET containers in developing countries is growing disposable income and changing lifestyle. The trend shift of PET bottles is as young generation is demanding more on the go packaging which is lightweight, easy to use and of a smaller portion.

 

Properties of PET Resin

PET plastics are the engineering plastics which possess high strength and rigidity for a wide range of applications. PET plastic is the commonly used thermoplastics, especially in packaging and textile industry. These polymers are given preference over others due to their differentiation properties, those are:

  • Good heat resistance and low creep even at elevated temperatures.
  • Good stability due to the low water absorption
  • Low water absorption (except in case of Nylons)
  • Excellent resistance towards chemicals (Dilute acids and alkalis, oil and greases, hydrocarbons and alcohols)
  • Good color stability and wear properties

Basic Physical properties of PET materials-

Tensile Strength 2.5 N/mm and Impact strength 1.5 – 3.5 KJ/m

Thermal Coefficient of expansion 70* 10.6

Density 1.37g/cm

PETE is a naturally transparent plastic. The outstanding properties of PET resin are that they do not react with water or food that makes them suitable for consumable packaging. It can be semi-rigid to rigid and is very lightweight. They are shatterproof that means they will not break or fracture. Thus prove to be a good replacement for gas containers.

 

PET Resin Uses

PET Resins are performance polymers. They offer a wide range of applications in the end segment markets. PET plastic are prominent in markets such as Transportation, Automotive, Electrical/Electronics, Household Appliances, Packaging, and Textile.

As PET material is an excellent water and moisture barrier it used extensively in packaging industry especially for consumable packaging (water bottles, soft drinks, packed foods). The high mechanical strength of polymer makes PET films to be used in tape applications such as a carrier for magnetic tape or backing up for adhesive tapes which are pressure sensitive. Crystallized PET plastics are used to make trays which can withstand both freezing and oven baking temperatures.

PET resins are heated to a molten liquid and then easily extruded to the desired shape. PET resins made by the combination of glass particles or fibers prove more durable and strong. These resins are used in different sectors according to their properties, which is the requirement of the product. Some of the prominent and large-scale applications of PET plastic are:

 

3D Printing

Polyethylene terephthalate is a strong and flexible polymer which is highly suitable for 3D printing. 3D printing requires a combination of flexibility and toughness which can be easily attained by PET resins. PET is commonly known for emitting less odor than any other material such as Acrylonitrile Butadiene Styrene (ABS) or Polylactic Acid (PLA) used for 3D Printing.

 

Injection Molding

Polyethylene terephthalate is widely used in plastic injection molding technique in form of pellets for producing products of complex shapes. Properties of PET material make it suitable for injection molding process. Certain precautions are also required while using PET materials for this process- As PET is hygroscopic so it must be dried before using in the molding machine. Shrinkage in PET plastic is low but also depends on a number of factors such as temperature, holding time, mold wall thickness, mold temperatures and type of additives used.

 

CNC Machining

PET material is extensively used as sheet stocks for CNC machines. CNC machine is used to manufacture multiple numbers of products where PET material is used as a basic material in the production process.

 

PET Film and Sheet

Polyethylene terephthalate is primarily used to produce sheets and films which are further used in the production of plastic items. PET film and sheet are commonly used thermoplastic sheets because they offer several benefits such as:

  • PET Films along with sheets provide high barrier properties and excellent chemical properties along with tensile strength.
  • They are easy to modify in shapes of bottles or other plastic consumables.
  • They offer more steadiness and shatter resistance to the product.
  • These films are lightweight and less expensive.

PET films are used on a very large scale globally but still, there are certain limitations available with these films which effect according to their usage. PET films can be toxic as they might release phthalates in some cases which can affect consumable food products. Gas permeability is also another problem faced in the usage of PET films and sheets. Gas permeability often results in the problem for packaging of carbonated soft drinks.

 

PET Bottle

The major share of PET resins produced is used for making PET bottles. These bottles or containers are used for wide range of consumable products such as soft drinks, alcoholic beverages, detergents, medicines, and cosmetics. PET plastic bottles made can be classified into two broad categories: Bottled water bottle and Carbonated soft drinks. Bottles made of PET resins can easily be recycled and again used to produce a new product. PET bottles are the maximum used plastic product in end segment plastic market. The excess production of PET plastic bottles in recent years has started affecting our environment (landfills and oceans or other water bodies). For maintaining balance in the usage of PET bottles, recycling has become a necessity. Recycled PET can be further used to produce lower grade products such as carpets, containers or lower grade PET bottles

Benefits of PET Bottles:

  • They are lightweight, easy to transport and safe in usage.
  • They can be easily Re-sealed or recycled to produce new products.
  • PET bottles can be easily molded into different complex shapes.
  • Production of PET bottles through PET resins offer a high level of flexibility to producers.
  • They are inexpensive and readily available.

The excess production of PET bottles in recent years has started affecting our environment (landfills and oceans or other water bodies). For maintaining balance in the usage of PET bottles, recycling has become a necessity. Recycled PET can be further used to produce lower grade products such as carpets, containers or lower grade PET bottles

 

PET G

PETG is an abbreviation for Polyethylene terephthalate (having glycol modification). PETG is a kind of modified version of PET resin which is one of the most commonly used polymers. The “G” used in PETG stands for “glycol-modified” which is added to the PET material composition in the process of polymerization.  PETG is more clear, less brittle and easier to use than the basic PET material. It is used widely to manufacture water bottles, packaging of consumables and variety of other plastic products. PETG is commonly used as a 3D printing filament as it is more durable and easier to use.

Benefits of using PETG

  • It is more durable and easy to use.
  • PETG is clearer and less brittle. The added glycol to PET prevents it from crystallizing and breaking.
  • It is highly resistant and sealable
  • It can be easily sterilized.

Advantages and Disadvantages of PET resins

Polyethylene terephthalate offers a wide range of applications, especially in the packaging sector. PET resins are commonly used in manufacturing bottles, containers and packaging tapes. It proves to be an excellent barrier material, preventing the transfer of chemicals which makes it most suitable for food and cosmetics industry. PET resin is commonly used thermoplastics as it offers many benefits such as:

  • The polymers are easily available and inexpensive
  • PET polymers are highly resistant to moisture and chemical resistant to organic material and water.
  • It has a high strength to weight ratio.
  • It is highly transparent and shatterproof (it will not break like glass packaging).
  • PET materials come in a variety of shapes and colors which offer o good choice in producing attractive products.
  • Polyethylene terephthalate can be easily recycled. PET plastic is one of the most recycled plastics and they are reused to make products such as containers, sleeping bag insulation, polyester fabrics and carpets etc.

Though Polyethylene terephthalate is the maximum used thermoplastic and is used almost in every plastic products which are used in our daily lives, these polymers still have certain limitations such as:

  • As compared to other polymers PET polymer has lower heat resistance.
  • PET resins are even susceptible to oxidation. As for example, they are not used for storing beer or wine as the shelf life of these beverages is long such that some kind of taste degradation may occur.
  • PET plastics are not biodegradable which might be good or bad depending on their usage.

 

Recycling of PET resins

Recycling of thermoplastic products has been common in past years. The thermoplastics such as PET resins are relatively easy to recycle as their polymer chain break down easily at low temperatures. PET plastics are being recycled on a very large scale globally. Recycled polyethylene terephthalate is termed as RPET (Recycled polyethylene terephthalate). According to PETRA, the PET Resin Association, the U.S recycling rate of PET is about 30%, and it is almost 52% in the European Union. Almost 1.8 billion of total PET was recycled globally in 2015 which was used to make a variety of end products.

Recycling Process of PET may be different for different plants but general steps followed in this process are as follows:

  • Bottles are segregated individually and unwanted materials are removed manually or by an automated system.
  • To prevent any kind of contamination bottles are cleaned inside and out thoroughly to remove all kind of dirt.
  • After cleaning bottles are sorted using infrared radiation technique, to determine the type of polymers present in bottles. Bottles are also sorted by their color (blue, natural green or mixed).
  • Further bottles are shredded into flakes which have to be washed again. Even this step can be missed and bottles can be directly melted to produce different shapes.
  • At last shredded PET, plastics are melted to further produce plastic pellets.

RPET produced after recycling of PET resin is used to produce a number of end segment products such as automotive parts, PET containers, sheet and films, industrial strapping, luggage, polyester carpet fibers and in clothing (T-shirts, sports clothing, athletic shoes etc).

Environmental Benefits of recycling PET plastic

PET recycling can be very helpful for sustainable development. It can help to achieve balance in the ecosystem which is strongly disturbed by an excess of plastic production. PET recycling can help to reduce dependency on oil and gas, reduce ocean and landfill waste and emission of greenhouse gases in the atmosphere.