Plastics are widely used for packaging because they are lightweight and require a small amount of energy to manufacture. In making beverages bottles, plastics can conveniently replace steel, glass, aluminium as a cost-effective alternative with little or no side effects. However, did you know all plastic packaging begins as tiny resins?
So what are resins? Resins are small materials used to form polymers. They have “molecular structures”. Plastic resins come in many different forms and colours to meet a variety of marketplace demands. In this article, we will discuss various types of plastic resins that are commonly used in packaging applications.
1. High-Density Polyethylene (HDPE)
HDPE is the predominantly used type of plastic material for making bottles and containers because of its high strength and durability. It is commonly used in every industry, from food containers to cosmetics and cleaning supplies (e.g. bleach and detergents) because of its good chemical and solvent resistance.
They can also be used in making t-shirt bags, bakery bags, grocery sacks, carton and box liners, shipping sacks, construction film, industrial liners, as well as many other products and packages. HDPE can be manufactured with or without a pigment.
Unpigmented bottles leave the container transparent for excellent clarity; they also have stiffness and barrier properties. Pigmented bottles have better crack and stress resistance but are ideal for packaging products with a shorter life span such as milk.
2. Low-Density Polyethylene (LDPE)
LDPE is widely used for creating plastic stretch films. It comes with numerous advantages including high flexibility, toughness, transparency or clarity, and durability. Moreover, it offers strong resistance to acids, bases, and some oils or greases.
As a result of its relatively high transparency, LDPE is used for product presentation and creating cleaning bags and stretch wraps. Thanks to its toughness and flexibility, LDPE is applicable where heat sealing is necessary.
It is also used in wire and cable applications in the manufacturing of flexible lids and bottles.
3. Polystyrene (PS)
Polystyrene has several unique properties that make it applicable to various types of packaging. For a start, polystyrene has the unique ability to be foamed or rigid. In its rigid state, PS serves as a moisture barrier for short-term storage.
It also provides durability and toughness mostly needed in protective food packaging for long-distance travel. As a versatile plastic, PS is often combined with rubber to make HIPS (High Impact Polystyrene) which is used for packaging that requires durability and toughness, but not clarity.
Because of its high melting point which allows it to accommodate heat, polystyrene is used to make coffee cups and containers.
4. Polyvinyl Chloride (PVC, Vinyl)
Also known as Vinyl, Polyvinyl is another type of plastic resin used for packaging supplies and equipment. This type of plastic is renowned for its stable physical properties such as resistance to chemicals and solvents, high stability, flow characteristics, and durable weathering capabilities.
As a result, Vinyl is used for packaging electronic products and equipment. They are also used in building and construction projects.
5. Polyethylene Terephthalate (PET, PETE)
Polyethylene terephthalate is clear and tough, and it provides excellent moisture and gas barrier properties. This is why it is commonly used to manufacture carbonated drinks and diverse types of beverages.
Chances are you must have picked one at the grocery store. It has high impact resistance and durability making it useful in producing geotextiles and fiberfill.
In addition to its mechanical properties (toughness and stiffness), PETE has good thermal properties, which allows it to withstand higher processing temperatures than other resins.
6. Polypropylene (PP)
PP has a high melting point, excellent clarity, good chemical resistance, and strong vapour barrier properties. As a result, it is commonly used for hot-fill liquids, making deli bags, and in food packaging to preserve the taste and freshness of the food.
Polypropylene can be found in fibres, rigid or flexible packaging, and large moulded parts for automotive products.
The Bottom Line
You can use these six types of plastic resins to create all types of packaging materials, from poly bags to grocery bags, stretch film or stretch wrap, pallet stretch film, and plastic sheeting.
They may have different unique qualities that make them suitable for different packaging manufacturing; however, what is common among these different plastic resins is that they are flexible in nature.