Stick to It - Adhesives Primer

Part 1: Label Chemistry

A label is not a label without some way to attach it. While we do have some labels that “adhere” courtesy of physics rather than chemistry (hang tags, magnetic vinyl, static cling), for the most part, our labels stick because of chemistry, in the form of pressure-sensitive adhesives.

A pressure-sensitive adhesive (PSA) is one that holds two surfaces together solely by surface contact. This is achieved by slight initial external pressure (in other words, they stick because you push or rub them onto the surface where you want them to stick). You don’t need to use anything else– solvents, heat, etc.– for a pressure-sensitive adhesive to stick. They can be used on a variety of materials and surfaces, like plastic, paper, metal, glass, and wood.

The surface texture, porosity, flexibility, and shape of an item all affect the adhesive strength needed to keep a label attached – or make it easily removable. Other aspects of a product’s surface that affect whether a label will stick include cleanliness (just a hint, clean is better) and whether the surface is coated or not. It can be complicated. We hope to make things a bit clearer in our new series, Stick to It.

Advantages of Pressure-Sensitive Adhesives

• Label application can be easily automated and usually doesn’t require elaborate equipment.
• Labels don’t require long curing times (although some will adhere better to rough or difficult surfaces if left alone for a few hours).
• Different adhesives can make your label permanent or easily removable.
• Because they don’t require heat or solvents, the labels can be used on a wider variety of surfaces, from very delicate to rough and rugged.

Anatomy of a Label

Labels typically include a release liner (the part you peel away when you're ready to apply the label), adhesive, and the face material, which can be paper, vinyl, polyester, foil film, etc. Artwork is printed onto the face material. Optional laminates can be applied over the printed artwork for design effect and protection.

In this series, we’ll talk about the different types of adhesives available, and which is best for what purpose.

Types of Label Adhesives

Label adhesives can be broken down into two main categories, permanent or removable.

Permanent

The majority of our labels fall into the permanent-adhesive category. Permanent labels are designed to be hard to remove – removal tears or damages the label, requires the use of solvents, and may leave residue on the surface. Permanent adhesive strength and speed may be variable; full adhesion may be nearly instant or may develop over minutes or hours. Some are built specifically to leave evidence of removal, to show signs of product tampering, for instance.

In addition to plain permanent adhesive, there are some specialty permanent adhesives.

Low Surface Energy (LSE):

• Designed for permanent placement on polyethylene, silicone, polypropylene, and other low surface energy plastics or oily metals with slick surfaces.
• Removal will damage the label and possibly the item.
• We’ll talk more about LSE adhesives in part 2 of the series.

Cold Temperature:

• Used in the packaging of frozen food products and industrial settings
• Label may subjected to temperatures as low as -65º Fahrenheit.
• Generally, you should apply labels with cold temperature adhesives at normal room temperatures.
• Removal will damage the label and possibly the item.

Ultra-Aggressive:

• Meant to be applied to curved and/or very rough surfaces (tires, for instance), or
• With metal plates or labels that should never be removed from specific equipment.
• Also good on powder-coated metals.
• The adhesive grabs quickly.
• The label is destroyed and residue is left behind when removed.

3M 467/468:

• A thick adhesive (2-mil for 467 and 5-mil for 468)
• Formulated to bond securely to rough (468) or smooth (467) curved surfaces.
• Often used with asset tags, industrial equipment labels, and control panels.
• Removal will damage the label and the item.

Removable

You may remove these labels without damage to either the label or the item, and they leave little to no adhesive residue. (The longer they are in place, the more chance of residue.) You may apply them to a wide variety of surfaces. These low-tack labels are great for limited-term items, like sales window decals, bumper stickers for cars, product information labels that should be removed prior to the product being used, etc.

Repositionable:

• You can remove repositionable labels without damage to either the label or the items.
• They leave little to no adhesive residue behind.
• Labels may be reapplied in a different location or on a different item.
• If you leave them on for a long period of time, they may be slightly more difficult to remove than if they are in place for less time.

Ultra-Removable:

• You can remove these labels at any time without damage to the label or the item.
• They leave no adhesive residue behind.
• Once removed, the label is not reusable.
• Unlike static cling materials, this type may be applied to a wide variety of surfaces and used in cold environments.

Static Cling:

• This material doesn't need a chemical adhesive to stick to glass.
• There is no residue when removed.
• The vinyl material bonds to smooth, clean, and dry surfaces with a little pressure.
• Labels may be reused for a limited number of times – once they get a bit dirty, they lose their cling.
• Not recommended for cold environments, or if the label is large (weight can overcome the static charge). Use ultra-removable in these cases.

Tags:

• • We have two different kinds of removable tags.
  • Plastic hang tags are probably most familiar to you as parking permits, hanging from a rear-view mirror.
    • Hang tags are easily transferable and very durable, standing up well to extreme temperatures.
  • Our other removable tags are heavy-duty card stock with reinforced eyelets.
    • These can be pre-strung with twine or wire for easy connection to your products.

Magnetic:

• Magnetic materials are great for marketing uses like temporary or moveable signage.
• They come in two thicknesses, both flexible white magnetic vinyl that accepts all our printing colors and foils.
• The 19-mil magnetic vinyl is great for smaller “refrigerator-style” magnets, with 12 magnetic poles per inch.
• The 24-mil magnetic vinyl has 18 magnetic poles per inch and works well for signs for cars or other, larger moveable signage use.

See which of our labels use these different adhesive types at https://www.mavericklabel.com/products/label-types/adhesive-labels.html.

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Part 2: Adhesives for LSE Plastics