The world of labels has so many terms and technical jargon that may make it difficult to understand. Our jargon buster aims to make these terms easy to understand to help you in choosing the right label material for your application.
Print quality can be affected by four surface characteristics of the substrate.
This is the ability of ink to penetrate the paper substrates. Inks which dry by absorption must quickly be drawn into the substrate to avoid smearing and offsetting. The substrate must also have sufficient hold out so that the ink does not penetrate too deeply, resulting in a washed out appearance.
Paper substrates must have a sufficient degree of moisture resistance so that they do not weaken or dimensionally change when printed upon using water based ink. Problems that could arise if the paper substrates are not moisture resistance include registration issues or curling of the finished label.
This refers to the ability of a material to reflect light, and is a critical property in bar code application, where the background must reflect a given percentage of the light energy emitted by a scanner. Different wavelengths of light can respond differently to the same substrate.
Paper substrates need to possess sufficient internal strength to overcome ink tack attraction to the printing plate and to be able to pull the ink itself without splitting.
Film dies require a sharper edge than paper dies due to the conformability of the film. The cutting edge must cut the elastic film as compared to the bursting operation when cutting paper. Improper tooling will stretch the film, bursting the paper or liner before the film is cut. In some cases, the film will cut easier if a larger wrap is made on the anvil roll.
This is the process of removing the waste facestock from around die cut labels. The waste is removed as a continuous web or ladder and rewound on scrap or cabbage roll. Since most of the facestock remains on the liner as part of the finished labels, the strength of the matrix is greatly reduced, making controlling a number of variables critical to the success of the operation.
The strength of the facestock, described as the vertical and horizontal matrix, can be measured in tensile and tear strength. Although a film may have high tensile strength, at the same time, films like PET or polystyrene may not be sensitive. These films can tear very easily if they are notched or nicked.
Machine Direction (MD) tensile is important in holding the vertical matrix (upright portions of the ladder) together. Cross Machine (CD) tensile affects the ability to remove the cross matrix (rungs of the ladder). The increased speed of the cross matrix results from pulling the strip of facestock from the outer edges, causing the material to be snapped from the release liner.
Liner release refers to the force required to remove the face paper and adhesive from the release liner. As the release value increases, the force required to remove the facestock increases, which in turn applies more force on the matrix to be removed. Increasing the width of this matrix will not necessarily aid in stripping. The wider the waste, the more bonds the adhesive has to the silicone and the higher the stress on the matrix.
Liner release can also be an issue if the force required to remove the facestock is too low for the label design. If the release is too low to overcome the adhesion between the die cut labels and the matrix, the labels will follow the matrix and predispense. Predispensing results as a combination of low release, soft flowing adhesive, poorly cut adhesive, label design and stiff facestock. Thus, it is very important that all factors be in balance.
The design or shape of the label can have a positive or negative effect on the ability to strip the material without predispensing the labels.
The purpose of any antistatic device is to neutralise the ions on a given material. There are numerous methods that can be used to control static; some are quick fixes, while most are permanent installations.
The first method to control static involved installation of a good earth ground, which provides an avenue to drain off the static, and works much in the same way that a lightning rod works on a building.
The first method to control static involved installation of a good earth ground, which provides an avenue to drain off the static, and works much in the same way that a lightning rod works on a building.
The brush is made up of very fine brass wires threaded around a copper wire, mounted in a wooden bar. The bar is installed at a convenient spot at the machine, and grounded through the machine through the copper wire.
Electric antistatic bars emit an electrical charge that neutralises the air around the given materials by ionising it. These bars can generally be mounted at a point on the machine where they will be most effective.
Another method used to control static involves the usage of carbon fibre brushes. These fibres are mounted in brush form in metal bars, and fastened to the machine with good grounding.
These consist of electronic controllers with vacuum systems, often accompanied by some type of brush to neutralise static and remove dust and dirt that has been attracted to the materials.
Problems arise due to the fact that frequently, people don’t press the label down firmly in all areas. Pressure sensitive adhesive labels require moderate pressure across the entire label surface to ensure proper contact. Not using proper pressure in the right areas is commonly the reason that labels curl or fall off, as most people tend to only apply pressure to the center of the label, which leaves the edges unbounded and free to lift. It is wise to recommend that pressure be applied to the full area of the label.