Guide To In-Mold Labeling (IML): Everything You Need To Know

In-mold labeling is a unique process for decorating molded plastic parts.

In-mold labeling primarily provides rubber plastic products with high quality and colorful labels. IML is cost-effective and enhances the quality of plastic molded products.

In this article, I will help you to fully understand everything about in-mold labeling.

What is In-mold Labeling (IML)?

In-mold labeling was first developed by Owens-Illinois in cooperation with Procter & Gamble, and was first applied to pre-labeled bottles. Now, it is becoming more and more popular and used by many molding factories in various industries.

When using in-mold labeling technology, the pre-printed paper label or plastic film label is placed in the mold, and the label is seamlessly fused to the thermoplastic material during the molding process, thus integrating the production and labeling process, no need for post-labeling. After curing, the container and label will become a single waterproof and scratch-resistant piece.

Why In-Mold Labeling Is Important and Popular?

Product labels are very critical to the success of rubber plastic products. High-quality labels add a lot of value to products. Quality label or design makes a rubber product durable and increases its lifespan.

The design of a plastic product has the power to attract people and even entice them to buy.

Modern psychology has proven that most people primarily buy based on their emotions. Most people buy based on how they feel about a product before even thinking about the benefits they will get.

How people feel about a product is linked to how they see a product. If the label is quality and beautiful, people mostly feel good about it. This good feeling ultimately drives potential customers to buy a product even when they have no idea of the product’s quality.

Sadly, a high-quality product with a poor and unattractive appearance is likely to fail on the market. A low-quality product with a highly attractive label or design can easily attract more people to buy.

This is why manufacturers need to pay massive attention to their product design and appearance.

In-mold labeling is one of the most cost-effective processes that help brands to get high-quality designs for their products.

The Principle of In-mold Labeling

The main principle of in-mold labeling is to coat a product with a layer of label or design.

The in-mold labeling process begins with selecting a unique material for labeling. Some of the materials used as labels include paper, polypropylene, and polystyrene. A material similar to the molded part can also be used as a label.

A cavitated material can be also used as a label. A cavitated label material is a spongy layer that is bonded between two thin solid layers. A laminated film is used as a label when high resistance to wear is of great importance.

The selected label is directed into an open mold. It is firmly placed into the mold cavity by either a clamp, vacuum, compressed air, or static electricity.

The selected plastic material is melted and injected into the mold. The injected plastic material binds with the label after cooling to form a single product. This produces a beautiful design on the molded product.

Advantages of In-mold Labeling

It Provides Various Decorating Options

This method of decorating plastics has quick design changeovers and it makes use of multiple color printing and lithography printing to produce products with higher quality which does not get abraded during use.

It Improves Appearance

In-mold labeling greatly enhances the appearance or beauty of products. It provides products with virtually impressive designs and eye catchy pictures. This easily draws the attention of potential customers. Product information is printed on the labels. The product is made even more beautiful because the corners of the label do not appear on the product.

Also, the structure of the product is improved because both the label and the product are formed together, they naturally touch together and this improves the structure of the product. The label is permanently fused with the product. The label remains intact throughout the product’s lifespan.

It Increases Production Efficiency

IML has a shorter production time and its production cost is very low since containers can be produced and decorated at the same time. This makes the storage of blank containers unnecessary and eliminates the cost of storage and transport.

It Prevents Counterfeit Products

In-mold labeling requires the use of uniquely designed molds. Manufacturing molds for in-mold labeling requires a lot of expertise and high capital. The expertise and high cost involved in manufacturing molds greatly reduce the tendency of fraud. The variations in mold design, film printing, and label formation processes make it almost impossible to copy. This helps to preserve brands.

Disadvantages of In-mold Labeling

• The tooling and robot systems used for in-mold labeling are expensive. This increases the production cost of in-mold labeling.
• The time used for in-mold labeling is too long. In-mold labeling requires longer runs since the production for shorter runs is very expensive and it also has a longer set-up time.
• There is a decrease in the economical advantage due to the frequent changes in tooling during the mold labeling process.
• It has a high product defect rate. The defect rate is the measure of the portion of defective elements about all the items produced. It checks the quality of the production. The defect rate is high when the products are manufactured improperly and depart from its intended design.

Forming Methods For In-Mold Labeling

There are numerous ways through which in-mold labeling can be done. In this article, we will look at the top three  IML forming methods. They are injection molding, blow molding, and thermoforming. All these three methods are effective. The only difference is the way the labeling is done.

Injection molding

Injection molding is the most popular in-mold labeling method. It involves heating plastic material and injecting it into a mold for it to cool. The molded plastic part fuses with a printed label placed inside the mold cavity. The results in a single decorated plastic part. The injection in-mold labeling method begins by printing a uniquely designed label.

This printed label is placed into an open injection mold cavity through a polymer carrier. The printed label is held in place by air pressure or mechanical means in the mold cavity.

Selected plastic material is heated and injected into the mold cavity for molding. The mold has a small opening that the melted plastic passes through. The injected plastic is allowed to cool in the mold. Upon cooling, it takes the shape of the mold and binds with the inserted label.
The molded plastic part is permanently bonded to the printed label to form a permanent decoration on the plastic part.

Injection in-mold labeling is cost-effective and provides great design flexibility. It provides long-lasting product labeling solutions and increases productivity.

Because the labeling of the plastic mold is done during the molding cycle, post labeling and other secondary processes are eliminated.

Many plastic containers use the injection molding method. A typical example of a product that uses injection molding labeling is ice cream tubs. Other products that utilize injection molding labeling are computer keyboards, cell phone keypads, smaller plastic paint buckets.

Blow molding

Blow molding is the second popular in-molding labeling method. This process involves heating plastic material and stretching it into a tube. The plastic tube is placed into a mold. Air is then blown into the plastic tube. This makes the plastic tube to fill the mold cavity. The plastic tube takes the shape or form of the mold.

Just like in-mold injection, the label for decoration is first fixed into the cavity wall of the mold. As the molded plastic cools, it fuses with the label inside the mold cavity. The fusion is made possible because the glue on the label’s surface is activated by the heat from the heated plastic. The blow molding in-mold decoration process results in high durable labeled plastic products.

This process is mostly used for manufacturing hollow plastic parts. This process was used to produce glass bottles. Today, this method is used for producing plastic bottles. This manufacturing process is used to produce liquid containers like containers for shampoos, dishwashing detergents, liquid soap, ketchup, sauces, etc.