Plastic labeling

Labeling solutions for the plastics industry

Hardly any other material can be processed as versatilely as plastic due to its numerous properties. Because of their specific behavior, thermoplastics, duroplastics and elastomers are processed into technical components in the electronics and automotive industries, into construction supplies, semi-finished products, consumer goods or packaging. The plastics processing industry, like the other sectors, also labels its products for reasons of traceability, quality assurance or consumer information. Various marking technologies are available for this. The decision essentially depends on the following factors:

What are the requirements for product labeling? Does it need to be durable or tamper evident? Or is it only for internal purposes and shouldn't be visible later?
What are the properties of the material to be marked? Plastic is not just plastic: the surface of the finished plastic product can be rigid, flexible, smooth or porous.
How high are the investment and operating costs of the marking system?

On this page we will explain to you how plastic labeling works. We would also be happy to advise you personally at your location - simply arrange a free appointment!

1. How to label plastic

Labeling plastic products is a challenge that starts with choosing the right label. Both the label adhesive and the label material must be precisely matched to the respective application. This is because the products, their material properties and the areas of application of the labels may vary considerably.

Type plate labels, for example, are stuck to electronic devices. Nameplates must adhere very well and must not be easy to remove again. However, the surface tension of the respective plastic plays a role. Labels adhere better to materials with high surface tension such as polyester, PVC or polycarbonate. The adhesion values are lower for plastics with low surface tension such as polyethylene (PE) or polypropylene (PP). There are two groups of adhesives: caoutchouc adhesive and acrylic adhesive. Rubber adhesive labels adhere better to low surface tension plastics than many acrylic adhesives. But it's not as simple as it seems. The subsequent areas of application must also be taken into account. For example, will the labels be exposed to strong UV light? Or do they have to be chemical-resistant or seawater-proof labels? Film labels made from PE film are more durable than paper labels and are suitable for use in outdoor areas or environments with extreme temperatures. As a result, they are often used for drum marking in the chemical industry.

Product labels or barcode labels are often found on plastic household goods or furniture parts. Here it is also important that the labels stick well. In some cases, however, they should also be easy to remove without leaving any residue and without damaging the plastic surface in any way. As a manufacturer of labels, we tailor them precisely to the respective application. We can draw on numerous label qualities and adhesives for this purpose. Our focus is also on ensuring that the labels can be easily processed further.

Label dispensers and label printers and dispensers are available for attaching the labels to the products. While label dispensers apply pre-printed labels to the products, the label printers and dispensers print variable data on them before they are applied. Numerous pressure modules, applicators and donation stamps are available to cover every application.

Sacks and bags made of plastic can be labeled wrinkle-free using the so-called wipe-on method. The label is taken along by the passing product and fixed by a pressure roller or brush. If angular, conical, oval or cylindrical products such as detergent or cleaning agent bottles have to be labeled all around or on the side, Weber Marking Systems offers suitable solutions with various labeling machines. These can also be combined with printers.

2. Marking plastic with ink

Inkjet printers are ideal for direct and non-contact marking of plastic products and components. Two different technologies can be used for this: continuous inkjet printing or drop-on-demand inkjet printing.

For durable, very legible and high-contrast prints, there is a wide range of inks to choose from, including many pigmented and quick-drying inks. In this way, non- and semi-absorbent plastics as well as porous plastics or foams such as styrofoam and sponges can be reliably marked. Inkjet printers are typically used in the food industry, for example to mark film packaging with batch and best-before dates.

Cable labeling

Cable and pipe extrusions are mostly made of polyethylene (PE) and polyvinyl chloride (PVC). These products often have different colors and the product surfaces are smooth. Our Linx inkjet printers meet the requirements of the cable industry and are suitable for cable marking. They print information on cables quickly, precisely and legibly, which is why they are often used for meter marking. With print heights from 1.1 mm, you can also label narrow cables. Special inks are available for cable marking that dry quickly and are highly adhesive. Pigmented inks also ensure excellent printing results on different colored substrates.

3. Marking plastic with direct thermal transfer printing

Kunststoffbeutel mit Thermotransfer-Direktdruck — Plastic bags with thermal transfer direct printing

In the packaging sector, flat and tubular bags made of film are one of the common types of packaging. Bulk goods such as gravel, road salt, coffee or sweets such as confectionery and wine gums are filled into them. Our Linx thermal transfer printers can print information directly and permanently on plastic sacks and bags. This technique is particularly cost-effective, since no labels are usually required.

4. Marking plastic with laser

Some semi-finished or finished products made of plastic are installed in cars or technical devices. For reasons of protection against counterfeiting, manufacturer liability and product traceability, a permanent and tamper-proof marking is required. Laser inscription is suitable for this because it is permanently abrasion-resistant.

Various types of marking are possible with lasers. Depending on the plastic and laser type, the material is engraved or removed. However, it can also be discolored - this is referred to as a color change - or foamed up. Various laser systems are available to mark plastic. A pulsed fiber laser is suitable for hard plastics such as ABS. For fine plastic films (e.g. beverage sleeves, thin film packaging for chocolate bars), a continuous wave fiber laser is a better solution as it gently marks the foil without perforating it.

Printing PET bottles

Laserbeschriftung PET-Flasche — Laser marking on a PET bottle

Inkjet-Druck PET-Flasche — Inkjet printing on a PET bottle

In the beverage industry, beverages are often filled in PET (polyethylene terephthalate) bottles. These must be marked with a best-before date, production date and batch number. For the direct application of such data, inkjet printing or laser inscription are the most suitable.

Our inkjet printers are suitable for the requirements of the beverage industry. They are robust and have protection class IP 65. Condensation often forms on the bottles, especially when bottling beverages, and conventional inks then do not stick. Special adhesive inks penetrate the condensation water and enable adhesive and durable prints.

However, PET bottles can also be marked with laser marking systems. We offer a special PET laser for this. During the marking process, the laser achieves whitening on the transparent PET material. This makes the label stand out well, even with transparent liquids. Thanks to our specially developed fonts, there is no unwanted vector crossing and the associated perforation of the PET packaging.

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