COEX Mailing Bags

What are multi-layer mailing bags?

The most essential feature of a Coex mailing bag is reflected in its name. "Coex" stands for coextrusion, a process in which liquefied plastic granulate is combined by at least two extruders to form a unified tube or film. The coextruded film or tubular film has distinct properties on both sides, as detailed in the section 'Types of Coextruded Mailing Bags'.

The granulate used is typically made from LDPE (Low-Density Polyethylene) or LDPE bzw. PE (Polyethylene). A standard film mailing bag is made from a single multi-layered film, sometimes referred to as "duplex". However, in theory, many more layers can be used. Coex mailing bags are predominantly employed in textile shipping. These multi-layer films are highly tear-resistant and also opaque. In essence, a Coex mailing bag is a flat, opaque bag with an adhesive seal and a security closure. These bags are especially suitable as an alternative to cardboard boxes.

What does Coex mean?

Coex is short for coextruded, meaning the Coex film consists of multiple layers, each with different properties. These layers are combined using multiple extruder heads to form a composite film. For instance, the outer layer of the film may be white, while the inner layer is black.

Why use film bags?

For many years, cardboard boxes were the standard outer packaging used in the wholesale trade, particularly for shipping clothing. However, it became clear that, unlike shipping bags, cardboard boxes occupy a relatively large proportion of the total volume of a consignment, which negatively impacts transport costs.

In contrast to conventional cardboard boxes, film bags are highly space-efficient, tear-resistant, and lightweight. As a result, using Coex shipping bags can lead to a significant reduction in weight, which in turn reduces the freight costs associated with transport. Additionally, savings are made on the use of adhesive tape or packing tape.

If the only consideration were whether to use a shipping bag or a cardboard box, a middle ground might be to opt for a cardboard shipping bag. However, this is complicated by the fact that cardboard packaging is far more environmentally harmful than plastic. Despite this, there remains a widespread misconception that plastic is inherently bad for the environment and more harmful than paper, as paper is biodegradable.

From an ecological perspective, however, producing packaging material from plastic is actually more environmentally friendly. This is because cardboard production requires more resources due to the instability of wood fibres, and the manufacturing process for paper packaging consumes significantly more energy. Moreover, toxic chemicals are used to extract wood fibres.

In Germany, strict legal requirements govern the recycling of plastic packaging and films. As a result, German companies do not simply discard their plastic into the sea. Nearly 100% of plastic packaging is recycled after disposal, processed, and reintegrated into the economic cycle as regenerated goods.

Therefore, the issue of 'too much plastic in the world's oceans' should be reconsidered—it's actually more accurate to say 'too much waste plastic in the oceans', as plastic is a broad term and, in the case of packaging, it is a highly recyclable material.

Another advantage of film mailing bags is that they provide much safer transport than conventional cardboard boxes. A film bag is water-resistant and exceptionally tear-resistant. Furthermore, the adhesive seal—also known as an adhesive strip or closure—prevents tampering with the contents, as any attempts to open the bag will leave visible damage to the outer packaging. This is more difficult to achieve with cardboard boxes, which can be resealed with adhesive tape after being opened. For this reason, Coex mailing bags are also ideal for use as security mailing bags.

Additionally, there’s no need to worry about returning items such as textiles. A film envelope can be designed to serve as a return shipping bag or reusable shipping bag. This is achieved with a double flap, where the two flaps are separated by tear-off perforations.

In conclusion, Coex mailing bags are cost-effective and environmentally friendly, making them an excellent alternative to cardboard boxes.

Types of shipping bags

As a wholesaler and importer, we are able to offer any design from a certain quantity upwards. From combinations of different colours and sizes, to special dimensions or bespoke requests such as a bottom fold, bubble-lined bag (bubble-wrap bag), extra strong UV resistance, or an angled flap, the variety is limitless. Simple prints, such as a recycling symbol, or even custom prints, can be easily incorporated on these shipping bags.

If you require a customised flat bag, simply contact us via our contact form, by email, or by phone, and let us know your desired dimensions and other specifications. However, if you're transitioning from cardboard boxes to film bags and are unsure of the exact type of Coex envelope you need, you will find some helpful guidance below.

Dimensions of bags

Below is a brief overview of possible dimensions and special sizes, including details of the DIN formats

In addition to the dimensions listed above and our standard stock items, virtually any custom size can be produced upon request.

Thickness

Our shipping bags are generally available in thicknesses ranging from 50 microns to 70 microns or 75 microns. These thicknesses provide sturdy film bags that are still extremely tear-resistant, despite not using excessive material.

While film mailing bags can also be produced in other thicknesses, lower thickness options may not offer the desired level of stability and resilience. However, the material is inherently robust and weatherproof. Coex mailing bags are UV-stable or UV-resistant for several months.

Colour options

A bag made from co-extruded tubular film is opaque, typically two-coloured, with the most common colour combination being black/white—black on the inside and white (or sometimes grey) on the outside. The black side ensures opacity, while the white side is moisture-repellent and dirt-resistant.

If you prefer a different colour, Coex mailing bags can also be produced in various colours and can even be printed in multiple colours if required. Please note that Coex mailing bags are not available in transparent form and are always opaque.

The closure

A Coex envelope typically features either a straight flap or an angled flap, both of which are self-adhesive. As Coex mailing bags are also designed for security purposes, the adhesive strength of the seal must be strong.

To achieve this, a permanent adhesive is used, ensuring that once the bag is sealed, it cannot be opened without visibly damaging the bag. This is referred to as a security seal or a security bag.

If you require a permanently adhesive self-seal but still wish to use the mailing bag as a reusable option, your film bag can also be produced with a double flap. The second adhesive flap is separated from the first by a tear-off perforation, allowing for easy reuse while maintaining the security features of the bag.

Is printing available on mailing bags?

Adhesive seal bags can, of course, be printed. To achieve this, a printing plate is produced based on your chosen design. This flexible plate is mounted onto a printing cylinder, which is then used during the manufacturing process to print directly onto the plastic mailers or adhesive seal bags.

Custom printing presents no issue for us. Your bespoke design can include your company logo, as well as additional elements such as warning texts—e.g. child safety warnings—or symbols like the recycling logo. These are printed onto the co-extruded (Coex) film used to manufacture your mailing bags.

We are pleased to offer Coex shipping bags with custom printing. Please note that printing plate costs may vary depending on the size and number of colours in your design.

Intended use

Whilst Coex mailing bags are primarily used for shipping clothing—such as T-shirts, socks, hosiery, lingerie, underwear, shirts, jumpers, and shoes—double-layer flat bags are equally well-suited for a wide variety of other items. These include valuables, jewellery, product samples (e.g. laboratory samples), office supplies, small goods, folders, catalogues, calendars, customs documentation, or promotional materials.

Multi-layer plastic bags may also serve as protective film envelopes for posting photographs or artwork.

You’ve probably already received items delivered in Coex film shipping bags—such as the flat bag used by couriers like DHL or UPS. Amazon likewise ships an increasing number of products in polyethylene mailing bags. Coex bags are particularly suitable for securely dispatching documents. However, please note that these mailing bags do not feature a transparent address window, so they must be clearly labelled or addressed prior to posting.

Coex mailing bags are easy to label, stamp, or handwrite on using a permanent marker (e.g. Edding) or another suitable pen. In many cases, postage costs can be reduced by using a Coex mailing bag, as they are considerably lighter than cardboard or paper alternatives.

How secure are Coex shipping bags?

Coex mailing bags offer significantly greater durability than standard LDPE bags. However, they do not allow for covert access. Due to the strength of the adhesive seal, the bag must be torn or destroyed to access its contents, making any unauthorised opening immediately evident. This feature makes them ideal for secure shipping.

How sustainable are Coex mailing bags?

Like all LDPE products, Coex mailing bags are fully recyclable and can be reprocessed multiple times. They are, therefore, a highly sustainable option—arguably more so than cardboard packaging, which often requires more resources to produce.

Coex mailing bags can also be manufactured using recycled materials—labelled as PCR (Post-Consumer Recycled)—with up to 80% recycled content. Crucially, this does not compromise the quality or strength of the finished bag; its performance characteristics remain fully intact.

DHL friction coefficient

The coefficient of friction (COF) indicates the resistance a film encounters when sliding across a surface. A lower COF means that a film bag will glide more easily. DHL specifies an optimal COF range of 0.15 to 0.2, which is precisely where our Coex film bags fall.

Enquiries and orders

You can purchase our Coex shipping bags at competitive prices directly from our online shop. If you cannot find the specific type or size you're looking for, there’s no need to worry—simply contact our sales team via email, telephone, or by using our enquiry form. We’ll be happy to confirm availability, pricing, and lead times before you place an order.

Would you like tiered pricing? No problem. We’re happy to provide a graduated offer, allowing you to see how prices develop with larger order quantities.

If you’re ready to place an order, our sales team is on hand to assist—not only with processing your order, but also with offering detailed advice and excellent service.

Shipping and delivery times

Our Coex stock items are available for immediate dispatch from our warehouse. You are welcome to collect your goods directly from us free of charge, or you can arrange a collection through your preferred logistics partner. Directions and our address can be found on our website.

Of course, we can also ship your order via courier or freight forwarder at attractive rates. We deliver to Austria, Switzerland, Eastern Europe, the rest of the EU, and also serve international customers worldwide.

Payment methods

If you’ve selected an item in our online shop, we prefer payment in advance. You may choose between a traditional bank transfer, PayPal, or even Amazon Pay if you have an Amazon account. For our business partners, we also offer the option of payment on account.

Customs tariff number

The customs tariff number for Coex mailing bags is 39232100.

Translation of ‘Coex shipping bag’

• German: Coex Versandtasche
• French: Enveloppe de coex

Related products

We also offer the following packaging materials at highly competitive rates:

• Packing tape & adhesive tape
• Tubular film
• Flat bags & gusseted bags
• Film and paper carrier bags
• Bubble wrap
• Bubble film bags