April 24, 2023
Various materials and manufacturing processes are used to produce squeeze tubes optimized for different industries. The most common types used today include aluminum tubes, laminate tubes, extruded plastic tubes, and more recently, in-mold label (IML) tubes.
Aluminum tubes are popular in the pharmaceutical industry and food industry due to the exceptional barrier properties of aluminum. No light, moisture, or air can permeate the tube, and any sensitive or volatile product inside cannot leak out or become ineffective. Part of this air-tight quality comes from the manufacturing process. Aluminum tubes are produced with impact or hammer extrusion.
The process begins with an aluminum slug of a predetermined diameter. The slug is pushed through a die and extruded into the rough tube shape. From here, the tube is trimmed at both ends and then threaded for the tube cap. Heat is applied to the aluminum tube to make it malleable again after becoming hardened from extrusion. The final steps are to apply coatings. For pharmaceutical tubes or other products sensitive to aluminum, an internal lining is applied. An external base coat is also applied and cured to prepare the tube for offset printing or other decoration. Most aluminum tubes will also have a fold sealant applied inside to prevent product from leaking out when squeezed.
Laminate tubes can most commonly be found in the toothpaste industry, but also have a place in the food industry and pharmaceutical industry due to some of the same reasons as aluminum tubes. Laminate tubes are made from rolls of laminate stock or web stock, and typically consist of five layers or more. The outer two layers are plastic, usually polyurethane (PE), and the middle layer is the insulating layer. Insulating layers can be aluminum, ceramic, or plastic. In between the outer layers and insulating layer is a copolymer that ensures the tube bonds and seals properly.
Before any shaping happens, the web stock is printed with the tube decoration. The first step in manufacturing the tube itself is the feeding of the web stock through forming rolls. These rolls shape the material into one long cylinder of the required diameter. The cylinder is then cut into smaller lengths corresponding to the tube body length. The tube shoulder then must be applied with one of three common methods. Compression and injection molding are two options for creating the shoulder in-line, or a preformed shoulder can be applied using a mandrel and heat.
Extruded Plastic Tubes
Extruded plastic tubes are commonly used across the cosmetic industry due to the many options for high quality decorations that do not degrade with use. Plastic tubes can be monolayer or multilayer depending on what properties are needed. Five-layer co-extruded tubes are one of the most common types of extruded plastic tubes. They have a similar composition to laminate tubes with PE outer layers, adhesive layers, and an EVOH insulating layer.
Producing plastic tubes begins with the mixing of resins and color concentrates to be extruded. This mixture is extruded through sizing dies to ensure a consistent diameter. Water cooling takes place before the long sleeve is cut to multiple uniform lengths. The tube shoulder is then applied to the body using either injection molding or two styles of compression molding. The threads for the cap are formed simultaneously during this step. Finally, the outer surface of the tube is treated to prepare for decoration.
In-Mold Label Tubes
IML tubes are a more recent entry into the world of squeeze tubes. One of the main advantages of IML tubes is their vastly improved sustainability over traditional plastic or laminate tubes. This is due to their 100% polypropylene (PP) construction, making them fully recyclable.
Manufacturing an IML tube starts with the already decorated label being placed into a mold. The mold is then injected with a PP resin which surrounds the label. In a very short time, a fully decorated tube body with a shoulder and threads is formed. Since the label is encased in the PP resin, there is no risk of damage to the label during transportation or use.
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