Q: What is the best film for use as a pressure-sensitive facestock?

Skip Heintzelman, Consulting Technical Editor 704/366-5204 -- Converting Magazine, 4/1/2001

A: Unfortunately there is not a single answer to this question. Just as every person has a unique appearance and personality, every label application has unique and distinctive requirements.

In order to select the best film, you will have to identify the performance and appearance criteria for each pressure-sensitive label application.

Performance criteria will include the following:

• Substrate (shape, size, and type of material)

• Conditions of use

• Environmental considerations

• Packing/distribution factors

• Method of application

Appearance factors include color (white, metallic, opaque, clear or frosty clear), surface of the substrate (gloss or matte), and whether or not there is a desire to achieve the "no-label look."

The most frequently used films are:

• Acetate

• Polyethylene (PE)

• Polystyrene (PS)

• Polypropylene (PP)

• Vinyl (PVC)

• Polyester (PET)

• Custom coextrusions

Each of these films has its own properties that can be either a benefit or a disadvantage in a particular application (see "Properties of film face stocks").

Selection scenarios

Today we are seeing the use of copolymer resins and coextrusions as the approach to tailor-making the properties of films. This trend will continue to gain popularity and provide labelmakers with an increasing number of film options.

Which criterion is most important-performance or appearance? Again, there is no clear-cut answer. The priority will vary from one application to the next. Here are a few selection scenarios that might help in your decision:

• Security seals made of acetate work well.

• If cost is the primary consideration, PS is the choice.

• In a squeeze application, choose PE.

• For labeling glass, PP is the first choice.

• When wrapping a small diameter, use PVC or PE.

• PET is often used in autoclave and extreme environmental requirements.

• Coextrusions will meet the requirements of many applications.

Once you have matched up the label criteria with the film properties, you may find that you have several satisfactory options. In these situations, let material cost become the deciding factor.

Label users have been known to specify facestocks that are doomed to failure, or at best that are marginal for the application. Suppliers who understand the films and their properties can assist their customers by tactfully questioning the material specified. The customer avoids an unsatisfactory experience. As a knowledgeable supplier, your image and value will go up.

As everyone knows, the face sheet is just one of the three components of the pressure-sensitive stock. The face material is the component that should be selected first, with the adhesive then matched up to the facestock and the performance and appearance criteria of the label application. The last element, the liner, should be selected based upon the method of application, as well as the film facestock and adhesive being used.

In all sports, picking the proper players and building on their strengths is the way a winning team is built. This approach can also be applied to material selection and labelmaking.

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