Decals - A Simple but Flashy Use of Adhesives - Editorials - Tapes & Labels - Channels

Decals are commonly used to decorate parts. They offer significant advantages in certain applications, and new materials and processes promise to provide even more eye-catching displays in the future. Today's editorial is all about decals and how they are a vital part of everyday life.

Most products experience some kind of decorating process whether it is decorative coatings, attachment of a pricing label, electroplating, surface embossing, or surface printing of a trademark. An understanding of the selection and correct application of decorating processes is extremely important because (1) the decorating process can significantly affect the sale of the final product, (2) the decorating process can be a large component of the finished product cost, and (3) misapplied decorating can result in complete loss of the finished product including total part manufacturing costs as well as decorating costs.

There are numerous decorating processes, but the use of decals has become quite common. Most of us who have assembled plastic model planes and the like have experience with the application of water-applied decals for giving those models an accurate look. Decals, however, play an important role in everyday business.

Decals are used for attaching logos, nameplates, or operational instructions on appliances, business machines, and other everyday products. With decals, the decoration is generally placed on a decorative adhesive-backed film and then on a paper backing. The stock used to manufacture decals is generally transparent film or brightly colored and reflective foils on which the required information is printed. Some transparent decals are used to cover and protect other labels or printing.

Decals are usually applied with a pressure sensitive or remoistenable adhesive. Often remoistenable gummed papers are used. The base stock is an absorbent waterleaf paper coated on one side with a solution of adhesive then dried and calendered smooth. The adhesive is such that it activates when in contact with water. Dextrin and cellulosic gums are often used as the adhesive. To apply, the decal is moistened in water and the film is placed on the part's surface.

There are other types of decals that have become important parts of commerce. For example, temporary signs used to advertise on vehicles and products are made of more expensive backings of polyester and calendered PVC film. The feedstock is generally heavy since these products are used outdoors and are subject to abrasion and general rugged use. These products are generally applied with a removable pressure sensitive adhesive.

Permanent signs are made with pressure sensitive adhesives from high performance synthetic elastomers or acrylic resins. Acrylic adhesives are most often used because of their good adhesion to many different types of substrates and excellent resistance to outdoor weather. The adhesive should be repositionable to provide for adjustments in case the decal was not applied correctly. A typical repositionable acrylic pressure sensitive adhesive formulation is shown in Table 1.

Component	Parts by Weight
Iso-octyl acrylate	57.5
Methyl acrylate	37.0
Acrylic acid	7.5

There are distinct trends in the decal industry that point to a variety of new products in the future. Significant emphasis will remain on the cost to produce the product. Technologies that allow a reduction in weight and a decrease in the raw materials cost will be highly valued. Decal manufacturers are trying to move away from solvent technology whenever possible. Hot melt and water based systems are being developed and making inroads in applications once devoted to solvent based systems.

Key drivers to new market opportunity will be customer service, production flexibility, custom made products, greater specializing and increased demand for new and improved backings (e.g., film materials). Large volume commodity applications will continue to feed the industry. However, niche markets (e.g., temperature indicating labels, security protection, instant computer-generated advertising) promise to spur future growth.

One of the drivers for the label market is the increase in pre-packaged foods, such as freezer section food products and cold beverages. This will necessitate low temperature decals. Another major growth area is office and data processing labels. Security labels for detection of theft as well as identification will grow with innovative use of new constructions.

Another trend in the label sector is utilizing clear film and adhesive for a "no-label-look". With this type of label, graphics stand out much better. However, they also machine better as well. In this way presses can run faster for improved productivity. No-label-look decals also provide superior wraparound labeling of glass and plastic bottles. Clear hot melt pressure sensitive adhesives are generally used in this application.

Hot melt adhesives also allow "buried graphics". Instead of printing on the top surface of the label, the label is printed on the underside. The adhesive is generally coated onto a liner and laminated to the face stock. Because the adhesive does not contain any water or solvents, it does not distort or damage the ink.

Despite the many ups and downs faced by all industries, decals will continue to be an indispensable accessory, continually thriving in a changing marketplace.