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LABEL PRODUCTION

Label Production

Welcome to the section about label production. Together we will focus on the most important aspects and knowledge from the field of labels. The purpose of this section is to explain the basics of label production and, at the same time, become familiar with the technical vocabulary used in this field.

 

  

 

History of labels

The first labels we know about are roughly from the year 1700 and were used to label small medical containers. During the 18th century every respected wine producer printed labels for his products. Every label was hand-printed on handmade paper using a wooden press and subsequently attached to a product using an adhesive. This method was very time-consuming, but in the year 1798 two inventions caused a dramatic increase in the speed of label production - the paper machine and the lithography.

From 1850 to 1860 colour printing was improved considerably. Up to that time coloured labels were painted by hand only for exclusive products, but now manufacturers understood that colours play an important role in selling ones product. Creativity was significant - as it is today, with the goal of catching consumers interest and giving the impression of being attractive and reliable.

In 1935 the self-adhesive label, which was the foundation of a billion dollar industry all over the world, was introduced in the USA. But only in the 60s, along with the development of new kinds of adhesives, did self-adhesive labels began to be applied on a mass scale on all kinds of surfaces (such as plastics, wood, cartons, glass and metals). The application was simple, feasible both manually and with use of machines.

In the 70s the first ‘intelligent’ labels appeared. The developments of new manufacturing technologies and the progress in electronic reading made it possible for labels to contain large amounts of information. The most famous one is of course the bar code, used in almost every shop and industry it plays an important role in logistics and storage.

Today's „smart labels“ (RFID labels) contain a semiconductor chip with an antenna, so that they can be programmed and their content remotely uploaded upon passing a reading frame. They are used in logistics, but there are future expectations of high-scale applications in many different areas, something currently not possible due to their high cost. 

 

Print techniques

Several types of print techniques are used in the production of self-adhesive labels. We in TECOM paper use three different techniques - letterpress, flexographic printing and digital printing. More information about these techniques can be found below. The fourth and fifth variations are called screen printing and offset.

 

Letterpress

Letterpress is a technique of so-called relief printing. Printing plates made from polymers are used for printing, whereby their raised areas transfer ink to the material. Based on the type of machine the printing plate is mounted either flat-wise or on a cylinder. The ink from the printing plate is transferred to the surface of the label. For each colour of the label a printing plate must be used. Printing plates used in letterpress printing are hard and the inks have high viscosity. You can find out more about this technique on Wikipedia

 

Flexographic printing

Flexography, most commonly abbreviated as ‘flexo’, is a solution for printing larger print runs. This technique makes high-speed printing possible. Similarly as with letterpress, printing plates are used to print, but are softer and longer-lasting. Flexo can be, in a more simplified sense, understood as a new version of letterpress - the technique has developed significantly since the beginning of the 90s. Print quality is now considered to be better than letterpress. Flexo is used for printing on packaging, plastic bags, corrugated cardboard and, of course, for printing of self-adhesive labels, as is the case in TECOM paper. Read more about flexography on Wikipedia.

 

Digital printing

In simplified terms, digital printing machines are enlargements of office printers. The advantage of digital printing in the field of label manufacturing is in fast printing of short runs. Where one needs to obtain and change printing plates, wash the printing units and adjust several additional factors before being able to print the next job when working with a conventional print technology, with a digital printer one doesn’t need to worry about much more than a mere change of material. With digital printing comes also a „guarantee“ that the labels will have the same colours from beginning till the end of a job. The last important advantage is the ability to print variable data, such as for example strings of bar codes, data from a database, etc.

Digital printing is represented in our company by electrophotography (transfer of dry powder toner), which in case of the digital Xeikon machines is characterised chiefly by high quality of print and smooth, glossy ink layer. The used toners are ecological and harmless (they may be used for printing on food product packagings).

We also use a UV inkjet print technology characterised by extremely long-lasting print, which enables long-term use of labels in external environments when suitable material is chosen for the application.

 

Hot/Cold Stamping

These technologies are used when the customer wishes to give the label an exclusive look. The most common use is for wine and cosmetics labels. Gold or silver foil is used, but many other interesting variations such as for example hologram or rainbow foils are available. After being applied, the foil forms a very shiny surface. In both cases a printing plate needs to be manufactured. In case of cold stamping this is a flexo printing plate, in case of hot stamping the printing plate is a metal one, mostly made of magnesium.

Hot foil is suitable for both coated and uncoated paper labels. Cold foil cannot be used on uncoated paper without expecting some difficulties (the adhesive, which attaches the foil to the surface, is partly absorbed by paper, and the result does not have to be of high quality), but is suitable for coated papers, or labels manufactured from synthetic materials such as foil.

 

 

Colours

 

CMYK

If the labels shall include an image, there is a high probability that it will have to be printed using all four CMYK colours. Thus using the Cyan, Magenta, Yellow and Key (black) inks. For each ink a printing plate containing a ‘halftone’ (also called ‘raster’ or ‘screen’), made up of many tiny points, is produced. The printing plates are mounted onto the printing cylinders and the inks are printed one over the other on the substrate. This is how a fully coloured image arises. In case of digital printing the halftone does not exist in form of a physical printing plate, but either as a ‘temporary printing plate’ in form of discharged areas on an electrically charged cylinder (electrophotography), or as a ‘virtual printing plate’ in a fully software form (Inkjet).

The CMYK base colour is white, since one prints on white paper or white foil. Combining same amounts of cyan, magenta and yellow (on white background) gives rise to black, but not quite in practice, and therefore we also use black ink. Another reason to use black ink is to reduce the use of CMY inks.

In comparison to this involve digital systems the RGB colour model (Red, Green, Blue), which is used to produce colours in a monitor. The combination of RGB colours gives rise to white, and the base colour is black.

You can find out more about the CMYK colour model in the corresponding Wikipedia article.

 

Spot colours

If the label shall contain a specific colour with a guaranteed colour consistency across all the orders it is necessary to use a so-called ‘spot colour’. In case of letterpress, flexo or offset one can directly use the PMS (Pantone Matching System), whereby the chosen colour is obtained by mixing certain base inks in specific ratio, which gives rise to the right ink that is then put into one of the print station's fountain in the press. PMS contains more than 1200 colours. Information on how to prepare each colour by mixing different ratios of base inks is provided. A strict observance of the ratios always results in the same (desired) colour.

In case of digital printing this mixing process is absent and the spot colour is printed by laying CMYK halftones over each other in the press. Some PMS colour shades can therefore not be accurately printed. Here we thus use a colour scale that has been printed on one of our digital machines, in order to allow the customer choose a certain spot colour which we are able to reproduce.

A label can contain several spot colours (for example in a company logo) and, in addition to that, an image in CMYK.

 

 

Materials in label production

Label material is made up of three layers:

  1. Top material – (this layer is printed on) exists in many different variations with various properties, which are briefly described below.
  2. The second layer is an adhesive, to which an individual chapter called Adhesives is devoted
  3. The third layer is called liner - this is a bottom material (most commonly a yellow-coloured paper) that supports the label and has a thin silicone layer on the side adjoining the adhesive. Thanks to this layer the label can easily be peeled off of the liner.

 

There are many combinations of these layers. More than 500 kinds of the top material, about 150 kinds of adhesives, and roughly 50 kinds of the bottom material exist. Besides that the surface of a label can be varnished or laminated after the label is printed.

 

 

Paper

Coated paper

Coated paper is a designation of any paper whose surface is coated. The aim is to obtain a more smooth surface of the paper - for example a glossy one.

It is rather difficult to write on this paper with a ballpen or a pencil, but the print itself is stronger and shiny, mainly because the ink does not get absorbed and remains on the closed surface of the paper. If a paper label shall be varnished after the print process, it is necessary to use coated paper (the varnish is absorbed by the surface of an uncoated paper and its effect is minimised). 

Uncoated paper - Vellum

The surface of Vellum paper is not coated and is thus matt. If the label shall be written on or stamped it is important to choose uncoated paper. This material is however not suitable for additional coating (as has been outlined above - the varnish gets absorbed into the surface). Uncoated materials are also cheaper than the coated ones.

 

Thermal paper

Many customers, primarily in the field of logistics, use a so-called thermal printer in order to additionally print certain data on labels manufactured by us. The print head of a thermal printer is made up of heat elements. In the width of 1 inch (25,4 mm) there are 200 (printers for logistics, scales), 300 (printing of simple graphics), but also 600 (printing of additional data using a very fine font - for example labels for goldsmith’s wares) of these miniature heaters. The dots of the print heads create heat in short impulses as the thermal label is in motion, passing over them, and this gives rise to printing of alphanumeric, but also graphic, data.

The advantage of this method of printing is the simplicity of the printers hardware, which is related to high reliability rate. No additional consumable material is needed as is the case with other methods of printing (dot matrix printer uses an ink-soaked cloth ribbon, inkjet printer containers with ink…). The colouring is contained in the thermally sensitive layer, which is coated on the surface of the paper. Another advantage is the high speed of printing and its low noisiness in comparison to, for example, a dot matrix printer.

The thermal layer of a label turns black when exposed to the heat of a thermal head, but there are also such thermal papers that produce blue print. A special variation of thermal papers are those that produce two-coloured print (black + red, or black + green). The idea is that exposure to lower temperatures produces red (or green) colour, while higher temperatures result in black. This kind of thermal paper is however not so widely used, because of its high price and the need for a special thermal printer.

The disadvantage of recording data on thermal paper is its low resistance to external factors, primarily UV light, oils and volatile chemicals (exposure results in fast fading of the recorded data, alternatively in its loss). Resistance of the thermal print can be increased considerably by a special protective coating of thermal layer (topcoat), but the price of such modified paper is noticeably higher. For this reason, thermal labels without a protective layer are most often used, and the areas of application are those that do not require long-lasting print (for example thermal labels for scales used in grocery shops, where the lifetime of print spans from the moment the label is printed to the moment the customer reaches the checkout counter). 

Thermal transfer print

In order to avoid misconceptions the process of thermal transfer printing (TTR) shall be briefly discussed. The nature of the process is practically the same as that of thermal printing, but ordinary paper labels without a thermal layer (possibly foil-based labels) are used. A very thin thermal transfer ribbon is inserted between the label and the thermal head. This is a foil coated with a layer of a colouring and a fixing substance (for example a wax-based substance in case of uncoated paper labels). The heat produced by a thermal head melts the wax layer with the colouring and both are fixed onto the surface of the paper.

Thermal transfer ribbons are produced from wax (suitable mainly for uncoated paper surfaces), but also from the mix of both wax and resin (suitable for coated papers), or only from resin (for printing on labels made from various kinds of foils).

We supply our customers with many different kinds of TTR ribbons and it is highly recommended to test the best combination of ribbon and label material. This is most preferably done together with the type of printer the labels and ribbons are meant to be used in. The quality of TTR print is influenced by the speed and temperature of the print process, which can both be adjusted for each type of printer using its software driver.

 

Foils

Besides paper, labels are produced from a whole range of synthetic materials, which differ significantly in their properties (resistance to external factors, strength, stiffness, etc.).

PE - Polyethylene

Polyethylene, aka PE foil, is a flexible, soft and ecological material. In other words, it is suitable for labels which will be subject to bending (for example labels applied on cosmetic tubes), or those that one ought to be able to dispose of ecologically. A good example would be labels used on apples. This material is not harmful to human body, even when it is accidentally swallowed (not that we recommend this in any way).

Since polyethylene is soft, the label can shape itself according to the shape (mild or lesser curvature) of the object it is applied on.

Resistance to external factors is not high and the material is not recommended for long-term (several months) outside use.

 

PP - Polypropylene

Polypropylene has many of the same properties as polyethylene, but is also stiffer. Therefore it is easier to apply the label on a product using an automatic label applicator. It’s stiffness also makes the label production easier.

Resistance to outside factors is not high and the material is not recommended for long-term (several years) outer use.

 

PET - Polyester

This is a very stiff and strong material with good and long-term resistance to outside factors. Very good print results are achieved when printed on by UV inkjet (the print is extremely resistant), which gives rise to a label that can be used under extreme conditions (for example product plates for equipment used in construction field). Another advantage of polyester is its very good resistance to temperature (for low as well as high temperatures), which makes it more than possible to print on the labels with a laser printer.

To put is shortly, the labels can also be used in harsh environments. But given these properties the price of this material is also several times higher than that of a PE or PP foil.

 

PVC  Polyvinyl chloride

PVC is slightly stiffer than polyethylene, but a bit more yielding than polyester. It is characterised by its very good resistance to outside factors, but is relatively expensive. The use of PVC has gradually dropped in the last years, primarily because of its low eco-friendliness related to its manufacturing process, where chloride is used. On the other hand there are cases where PVC is the best and most secure solution, certainly if the label shall be resistant enough to be suitable for outer application.

 

Transparent foil

As the name indicates, this is a see-through material. The print is thus the only visible thing the label contains. Transparent foil may not be a material in and of itself, but it comes in variations such as PE, PP, PET and PVC. An example of this are labels used on plastic bottles. A special example are labels made from very transparent material also containing an extremely transparent adhesive. Transparency of the adhesive is achieved, among other, by using a thin PP or PET siliconised foil, instead of siliconised paper, as liner. If paper liner is used, the structure of paper fibers becomes visible in the surface of the adhesive (the adhesive becomes slightly milky) and hinders transparency upon application - for example on a glass bottle. Such labels are designated by the term NO LABEL LOOK. They are used for example on glass bottles containing alcoholic beverages. The label material perfectly visually merges with the surface of the bottle, such that only the print itself is visible. This gives the impression that the print is applied directly on the surface of the glass bottle.

 

Silk

This is actually an artificial material. Its surface gives a fabric impression, especially to the touch. If you want to for example label textile goods, whether in relation to sale, or simply to having a label with one's name and post on one's chest, silk is a very suitable material.

 

 

Adhesives

Since a wide range of adhesives that differ in their properties is available, it is necessary to devote appropriate care to choosing the right adhesive. In order to fully achieve the required functionality of the label with regard to its adhesiveness, the customer should inform us about the intended application of the label, the surface the label shall be applied on, and factors it will be exposed to during its lifetime. Our staff will then suggest a suitable adhesive and provide the customer with free samples in order to test the label on the desired surface.

Below you can find basic partitions of adhesives, which shall give you some understanding of what adhesives are manufactured from and how they work.

 

By adhesiveness - Permanent and Non-permanent

There are of course many levels of adhesiveness, some adhesives can be regarded as extremely adhesive, cheap non-permanent adhesives do not resist UV radiation and harden with time, expensive non-permanent adhesives fulfill their intended functionality even after long-term exposure to UV light - the label can still be easily peeled off without any adhesive remaining on the application surface...

One should be also aware of the terms ‘initial tack’ (immediately after applying the label) and ‘final tack’ (adhesiveness acquired after the label gets fixed on the surface - preferably after 24 hours). One should therefore not immediately test how ‘’unpeelable’’ the label is, but should first wait several hours (preferably 24), and then start drawing conclusions.

 

By material of the adhesive - Rubber (Hotmelt) and Acrylic

Rubber adhesive is coated to the substrate when it is molten, and is thus also called Hotmelt. Its advantage is a very good initial tack, also in case of more problematic surfaces (for example cartons made from recycled corrugated cardboard). Its disadvantage is a more difficult die-cutting during the production of the labels, primarily during summer months (the adhesive is soft). This is the reason why, sometimes, rolls of self-adhesive material used in production of the labels are put in a cooling box for 24 hours - the adhesive becomes stiffer and die-cutting easier.

Acrylic adhesive is easier to die-cut, also at higher speeds. It shows good adherence to smooth surfaces, but some fixing difficulties on problematic surfaces. Labels can even be found to have fallen off of cartons placed in an unheated warehouse, especially during autumn and springtime when high humidity causes the label to crimp, which results in a force larger than the fixing force of the acrylic adhesive to the surface of the carton. Only labels containing rubber adhesive are suitable for such applications.

 

By temperature - Frost-resistant, Regular (Room temperature) and High temperature

With adhesives, information about temperature resistance is conveyed by stating the service temperature, which is the final temperature the product is stored or used at.

This is not the application temperature. It is common to apply labels at room temperature (application temperature) and the product is then possibly stored frozen. It is difficult to apply a label on a frozen product since it quickly becomes wet with dew after being taken out of the cooling box and the water layer then prevents the adhesive from getting fixed onto the surface of such an object. Nevertheless there is an adhesive developed for such a case - it is more expensive, but capable of fixing the label despite the presence of a thin water layer.

Adhesives which resist high service temperature are typically used in labels applied on engine components in cars.

 

Surface treatment

The most common means of surface treatment are coating and lamination, both of which are described below.

Hot foil is sometimes considered to be surface treatment, but is more likely to be regarded as print.

 

Coating

Coating guarantees a shiny and elegant look of a printed label. At the same time the colouring of the print is set off - the colours become deeper and more brighter. The coating also protects the label from external factors, something that significantly prolongs its lifetime. Coating itself is done by spreading a defined amount of varnish on a rotary print cylinder, which in turn applies a thin layer of varnish on the label. The varnish is subsequently polymerised by a UV lamp.

Water-solvent varnishes that get dried by drying with IR lamps also exist, but in practice it is the high-quality UV varnish that dominates.

It is most common to varnish the whole label, but in some cases spot varnish is also used, whereby only certain areas of the label are coated. This method is used to set off only certain parts of the print (in case of graphical labels). Another example of spot varnish is the customers requirement to be able to additionally inscribe information in the non-coated part of the label by writing or stamping (for example a use-by date). This is the case primarily with paper labels. Spot varnish is done using a photopolymer printing plate, which must be tailor-made.

It shall be also mentioned that there are two kinds of varnish: transparent and matt. Transparent varnish gives the label a more distinct look, matt varnish provides better readability of the print and is also used on some more luxurious labels. UV varnishes contain silicon, which means a coated, stiffened surface can no longer be printed on. Matt varnish can however come in a silicon-free version, so that the coated surface of a label can additionally be printed on, for example in form of individual data printed by a thermal transfer printer (TTR printable varnish).

 

Lamination

Lamination is performed by applying a thin, protective foil over the whole area after the print but before the label is die-cut. The label is then provided with an additional, highly resistant layer, which protects it from external factors. Lamination foils are most often made from polypropylene (a cheaper version), or from polyester (more expensive, but more resistant). The foil can also contain a UV filter.

One of many examples are labels used on electric hand tools (for example chainsaws or hand drill), where it is necessary that the label can also withstand more demanding use in an outer environment.

There are many kinds of lamination foils with specific properties. Lamination foils can be shiny or matt, and come also in different thicknesses. A thick lamination foil gives the impression that the label is protruding out of the surface of the object it is applied on.

 

Postpress

As soon as your labels are printed they get wound up on a large and heavy roll on the end of the printing press. Such roll is then turned into smaller, more convenient rolls using a slitter rewinder.

 

Rolls and rewinding

Most customers want their labels delivered on rolls. This means determining how many labels each roll should preferably contain. Either a certain amount of labels, or the maximal diameter of the roll, is required. It is equally necessary to determine the inner diameter of the core on which the labels will be wound.

Most common are cores with inner diameters of 40 or 76 mm, but other diameters are also possible. We at TECOM paper are able to deliver rolls of labels also on cores of inner diameter 12, 17, 25, 38, 40, 50, 70 or 76 mm. As stated above, 40 and 76 mm cores are the most used and we always have them on stock. This is therefore the cheapest solution.

Cores are made of paper, but we can also deliver our products on plastic cores. Some customers prefer this option in the case that the labels shall be used in a dust-free environment.

Last, but not least, is determining the winding number. If the label will be applied by label applicator the right winding must be ordered. In other words - the direction in which the label will come out of the machine is decisive. There are eight possibilities and probably only one of them is the right one for you (or rather for your label applicator). Please do take note of the winding number from the picture below and do not omit stating it in your order.

  

 Navíjení schéma naležato Tecom.jpg

 


Sheets
 

Instead of on rolls your labels can be delivered on sheets. Either individually (one label = one sheet) or with several labels on each sheet - for example in order to be used in an office printer. Cut sheets get packaged into packs containing a specific, previously determined amount.

 

Folded labels (Fanfold)

Labels get manufactured in a web which is perforated in definite intervals, folded and inserted into a carton. In this case the labels are therefore delivered in a stack. Folded labels are used in dot matrix printers or thermal transfer printers.

When compared to labels on rolls, the advantage of folded labels is that the printer can hardly manage to pull a large and heavy roll, and if the roll does get pulled enough and starts to rotate, its inertia prevents it from stopping after the label (or ticket) has been printed on, and the labels keep unwinding uncontrollably for some time.

Folded labels are pulled (not too forcefully) by the printer out of the carton (where there is a larger amount of them than what would be found on a roll), and if printing is stopped the label web also immediately stops.

On the other hand, as labels are primary produced on rolls and then folded on additional machine, they are expensive compared to those delivered on rolls.

 

  

How to provide data to our repro and design department?

If the order is to smoothly go through our system it is necessary to meet certain criteria:

We prefer PDF file formats. Images may be in JPG, or TIFF, but make sure they have a large enough resolution. If the labels should be printed in several variations with the same format, then we would like to receive from you a multipage PDF file, where each page contains one label. 

It is also necessary to have all of text converted into CURVES. If we shall also edit the text, then a file containing plain text also needs to be sent. In such case it is also important to send fonts, or otf-fonts (open type fonts that work on both Mac and a PC).

Image resolution should be 120 pixels per cm (300 pixels per inch).

Get in touch if you have questions about variable data / personalisation.

Your original can also be scanned at our company, if it is only in physical form.

We can also provide you with the design of your label in co-operation with a creative graphic designer.

 

© TECOM paper s.r.o. 2016  ALL RIGHTS RESERVED

 

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