It is difficult to imagine using labels without high quality adhesives. These are primarily responsible for the degree of adhesion between the label material and the substrate. This means that they must have a high tack and tack resistance even when exposed to moisture, chemicals, extreme temperatures, moisture and other stress factors.
Pressure Sensitive Adhesives - PSA
Its characteristic feature is that the adhesive starts working only when the paint evaporates from the composition. On the one hand this is an advantage, because when the label is applied it is possible to adjust its position until it finally adheres to the substrate.
On the other hand, it should not be forgotten that in most modern factories the labelling process is fully automated and precise. Accordingly, there is no need for a long setting time. There are, however, always certain inconveniences because of this. First of all, it is necessary to hold the finished product for some time so that the glue dries and the label is not deformed during transport or loading/unloading of goods.
At the moment such adhesives are used not only in the production of labels, but also in the production of scotch tape, books, linoleum gluing and dry lamination process. Therefore an important advantage of this formulation can be considered its versatility. It is worth pointing out that the adhesives of this type may differ in the way they work:
- Perpetual Velcro is when the label cannot be removed without damage
- Sticky is when the label material can be easily peeled off and glued back on if necessary.
This is relevant for multilayer labels which are often used in the production of various products nowadays: alcohol, cosmetics, personal care products, medicines and so on.
Despite some disadvantages, Pressure Sensitive Adhesives (PSA) have undeniable advantages.
Of particular interest for manufacturers will be the high level of adhesion even on flexible surfaces. For example,
polypropylene, which is used extremely extensively today. In addition, this adhesive composition makes it possible to securely bond the product even to metal, something that most conventional adhesives are unable to do.
While the liquid form is cloudy, the water evaporates and the glue transforms into a clear film that leaves no trace on the surface. It then loses none of its sticky properties, making PSA glue an excellent option for re-labelling. It's hard to say that this is in demand in modern production, but such a feature is definitely worth adding to the list of benefits.
PSA differ in a number of ways:
- The amount of volatile and non-volatile substances
- Viscosity
- The strength of the stickiness
On your own it is difficult to determine which adhesive is best for your product.
Therefore we urgently recommend to entrust in this question to professionals. And for a hundred percent correct choice you will need to provide reliable data on the peculiarities of production, its transportation, the nuances of the labeling process. In most cases, the most important information is the temperature and humidity at which the labeling process is carried out. Plus the professionalism m neatness of loading, shipping and delivery of the goods.
The most popular adhesives on the market
As such, there is no one-size-fits-all solution for all types of surfaces. They are most widely used for labelling glass surfaces: alcoholic and non-alcoholic drinks, canned food, medicines and so on. They are characterised by a high viscosity level and an increased setting rate. At the same time they are sufficiently resistant to high and low temperatures, high humidity.
In addition to easy application and high strength, these adhesives are very practical for reusable containers. In order to remove the label, simply treat it with a mildly alkaline aqueous solution. A 1-3% caustic soda solution is well suited for this purpose. This is an excellent option in order to save on the cost of producing new containers.
The most versatile adhesives are those based on synthetic adhesives. And their main advantage is that there is no need to use mildly alkaline solutions to remove the label. On the other hand, this means that the label itself does not hold as firmly as is sometimes necessary. And even without that, there are some complications. Removing the label is in most cases not a problem at all. However, removing the adhesive residue is a much more difficult task. You have to use a lot of water and special surface treatment equipment. Otherwise, traces will remain, and the new label will hold up much worse on such a surface.
Types of adhesives for labels
As you may have seen, there is no perfect option for all cases. Therefore, let's look at a few types of
self adhesive labels that are just as widely used in production:
Permanent adhesive
Refers for the most part to the types discussed above. The high adhesive properties and strength are an advantage for the buyer and in some ways a disadvantage for the manufacturer. It is physically impossible to remove such a label without damaging the product itself or leaving marks. Accordingly, this implies some difficulties for product manufacturers in handling the containers.
Semi-permanent adhesive
The peculiarity of this formulation is that the sticker can be removed without any problem within a day after gluing. With a longer contact with the surface, it becomes permanent and it is more difficult to remove the label. This makes it possible to quickly remove defects in the
packaging during production.
Removable adhesive
Has relatively low adhesive qualities compared to the others. It is easy to peel off, and almost no adhesive residue is left on the surface. The entire residue can easily be removed with a sponge and warm water. Nowadays there are also ultra-removable adhesives that have very low adhesive properties;
Acrylic adhesives
A distinctive feature is very high adhesion, resistance to ageing, UV radiation and other factors.
Rubber based adhesives
They have even higher adhesive properties than acrylic ones. But they are slightly inferior in a number of resistance properties. At the same time, we should not forget that it is mostly a natural product that is more environmentally friendly and safe for human health.
