what is preform | rotapack

What is a preform?

The word preform means prefabricated. The Preform is an intermediate product that Preform can convert into a variety of bottles. Many of the bottles are made from PET preform.

Different types of materials are used to make plastic bottles. Some of these materials are polyvinyl chloride or PVC, polyethylene or PE, polyethylene terephthalate or PET, etc.

Among these materials, PET has its characteristics. Some of these features are transparency, lightness, high strength, optimal creep properties, low flavor absorption, high chemical resistance, beautiful appearance, more accessible access, and low price. PET is a type of polyester. These are the favorable properties of PET that have led to using this material as a suitable material in the plastics industry.

Another unique feature of PET is that this material in the molten state, unlike other raw materials for plastic production, lacks sufficient strength. Therefore it is not possible to produce containers and plastic bottles of PET preform by extrusion of melt and blowing polymer in the mold.

Therefore, the production of plastic bottles with PET raw material is done in two stages:

  • In the first stage, the PET becomes a long tube similar to a laboratory tube. This long tube is the same as the PET preform. The size of the mouth of the PET preform produced at this stage will not change after the production of the bottle, and its size is the same as the final size of the mouth of the bottle.
  • In the second stage, the PET preform hollow tubes are placed in a unique mold and turned into different containers and bottles.
what is preform | rotapack

Advantages of Preform:

One of the advantages of Preform is its small volume. Although the preform volume depends on the shape of the final bottle, there is a volume difference of about 1/5 to 1/10 between the Preform and the final product. It is possible to carry 300,000 to 400,000 preforms with a 10-ton truck. This small volume contributes a lot to environmental measures and reduces costs.

Another advantage of Preform is that it can be used to produce bottles and containers with various designs. It is enough to heat the Preform’s body to about 100 degrees Celsius and put it in the mold. It will then be shaped as desired with high-pressure air.

Multilayer containers and bottles can also be made using preforms. These containers can prevent oxygen from entering and keep the food unchanged for a more extended period. Also, the flavor and aroma of the substance which is inside them don’t be lost.

Also, PET preforms are recyclable and have high flexibility, and this feature makes it possible to use them to produce a variety of plastic doors that can be closed quickly.

The benefits of PET preform:

  • It has excellent transparency.
  • It is water-resistant and impermeable.
  • It has good electrical insulation.
  • It does not produce toxic gas when burned.

Types of PET preforms:

PET material is usually used to make preforms, and they are called PET preforms. In general, PET preforms can be grouped according to their opening size.

PET preforms can be classified as follows:

  • Jar preforms: This group of preforms have larger openings and are usually used to produce a variety of containers for spices, pickles, honey, etc.
  •    Opening preforms:This group of preforms have smaller mouths and are usually used to store liquids such as mineral water, soft drinks, milk, beer, herbal essences, liquid oils, various types of liquid toxins, etc. In this group of preforms, the opening also has multiple sizes; For example, the preform 20 is used as a standard preform for mineral water. The Preform 28 is used to store carbonated substances such as soft drinks.

Another noteworthy point here is that each of these types of preforms is also divided into subgroups, and this grouping is based on other features of the Preform. Some of these features are:

Weight, preform body diameter, wall thickness, and overall diameter.

Preforms are also available in different colors. Using colored preforms, all kinds of colored bottles and containers are produced.

Rota Pack Company is one of the PET preform manufacturers which produces various types of PET preforms. This manufacture can prepare all kinds of PET preforms you need for use in the packaging of food, cosmetics, chemicals, edible oils, and all sorts of beverages.

PET preforms are divided into the following general types:

  • Heat resistant:

In making bottles with this type of PET preforms, crystallization is done that improves hardness and heat resistance. To increase the heat resistance, the bottom of the bottle is usually petal-shaped and concave in shape.

These bottles can keep liquid with the high temperature in them and then cooled by a cooling shower. These bottles usually have depressions. After cooling, the container sinks in, the internal volume decreases, and the liquid level inside rises. When the lid is opened, the depressions are recovered, and the fluid level is lowered.

  • Sterile bottles:

Using PET preforms, you can make sterile containers or fill the container with a pure liquid. Aseptic fillers are used to make this type of container. Compared to high-temperature filling, the aseptic filling does minor damage to the liquid temperature and can be done while maintaining the original packaging quality of the material. This group of containers is suitable for storing beverages containing milk and nutrients containing vitamins that may be lost because of high temperatures.

  • Pressure resistant:

These types of PET preforms are designed to make containers resistant to the internal pressure of carbon dioxide and are suitable for storing carbonated beverages. Usually, the bottom of these bottles is five petals that can better withstand the pressure.

Uses of preforms:

The use of PET preforms is extensive. PET preform can be used to produce a variety of plastic containers and bottles. PET preforms are environmentally friendly and do not contain substances harmful to human health, and do not release harmful and toxic substances. The use of the containers made of PET preform is approved by the US food and pharmaceutical industry.

Perhaps one of the reasons for the popularity of PET preforms is that products made with them are highly durable and resistant to impact and fall. Unlike glass products, PET preform bottles do not break easily and create more security for users, and their price is lower than glass.

Bottles and containers produced using PET preforms are used to store various liquids and foodstuffs, hygiene, and so on. Some of these ingredients include milk, juice, sodas, sauces, shampoos, dishwashing liquid, and more.

How to make a PET preform bottle:

In general, the following two steps are taken to make a PET preform bottle:

  1. Preform molding step:

Resin converts to a test tube, and there are two methods of preform molding: injection molding and PCM molding.

Injection molding method:

In this method, by heating and melting the resin, injecting and filling it in a pre-sealed mold at high temperature and high pressure, and then cooling and freezing, preform molding is done. The steps are:

  1. Close the template.
  2. Inject the molten resin into the mold and select a specific cooling period.
  3. The mold is kept closed for a while.
  4. The template opens.
  5. The Preformis taken out.
  1. Two-stage tensile impact molding stage:

In short, the Preform is heated in this stage, and the air is blown into the mold to inflate it and blow it into the molded bottle.

A more detailed description of this method is as follows:

In this method, molding is done inside the bottle mold, and a heated preform is placed inside the mold. It is then pulled vertically with a rod called a traction rod while the compressed air is blown to inflate in the circumferential direction.

Here are the steps:

  1. After heating the Preform, put it in the mold.
Put heated preform in the mold | rotapack

Put heated Preform in the mold

2. Close the mold and stretch it vertically with a pull bar.

 | rotapack

Stretch the Preform

3. The air explodes and flows (transverse tension)

4. Open the mold and take out the bottle.

Final step preform product | Rotapack

Final step

How to price a preform:

The price of a preform depends on several factors. The raw material of Preform is PET. Petrochemical companies produce PET material or polyethylene terephthalate. Therefore, petrochemical companies’ price is determined, and the price of the dollar also affects it. The price of this item is variable and is determined daily.

The final price of the preform bottle, in addition to the PET preform price, depends on other factors such as the weight and size of the bottle, the number of layers, the technology used in its production, and shipping costs.