About Paper Coated

About Paper

Coated products

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About Paper Coated products

www.torraspapel.com 1

Table of contents

1. Definition of coated products 2. Coated paper

2.1. Art paper 2.2. Triple-layer paper 2.3. Double-layer paper 2.4. 1/s coated paper

3. Cast coated products 3.1. Types of cast coated products

4. Carbonless products 4.1. Types of carbonless coated products 4.2. Uses of carbonless paper

A. Self-separating glue B. De-sensitizing ink C. Revealing sprays or felt-tipped markers

5. Thermal paper 5.1. Types of thermal paper

6. Metallized paper 6.1. Types of metallized paper

7. Solid bleached board (SBB) 7.1. Types of solid bleached board

8. Folding boxboard 9. Boxboard 10. Self-adhesive products

10.1.Types of self-adhesive products A. Types of face material B. Types of release liner C. Types of adhesive

Summary

2 2 3 4 6 7 10 11 14 16 17 17 18 18 19 20 21 22 24 25 27 29 31 33 33 34 34 36



1. Definition of coated products

A coated product is one that has a covering consisting of a mix (or layer of coating) of mineral and organic components, which is sometimes produced in its basic form, and sometimes with added plastic or aluminium elements. The main aim of the coating is to make the product more suitable for being printed on.

Coated products can have different numbers of layers of coating depending on the quality required, and also different structural characteristics according to whether they are going to be printed on in the form of sheets or reel.

Coated products are essentially intended for the publishing and advertising sectors, although if we look at the market for cardboard and folding boxboard varieties, we are entering into the heart of the packaging products sector.

Below is a list of the different types of coated products which we will talk about during the course of this unit.

Coated paper

Cast coated paper

Carbonless paper.

Thermal paper.

Metallized paper

Solid Bleached Board

Folding boxboard

Boxboard

Self-adhesive products

2. Varieties of coated paper

The varieties of coated paper which we produce can basically be differentiated in terms of the concepts listed below:

The number of layers of coating applied to the paper (determining whether the paper will be art paper, triple-layer paper, etc.).

The printing system to be used with the paper (rotogravure, offset, etc).



The type of machine used for printing (for sheets or for reels).

In terms of the concepts mentioned above, the four varieties of coated paper described below will be produced:

Art paper.

Triple-layer paper.

Double-layer paper.

1/s coated paper.

2.1. Art paper

Art paper is defined as paper having three layers of coating on both sides of the sheet. The amount of coating is usually quite large, coming to as much as 40 g/m2 on each side of the sheet in the case of substances higher than 200 g/m2.

It should be borne in mind that the amount of coating to be applied to paper can vary according to its substance, since the layers of coating reduce the stiffness of the paper, which for its part always requires a minimum amount of fibre.

Given its high level of coating, this type of paper gives a very high quality of printing, so that it is important that it should be used for catalogues of products that demand a high level of accuracy in the reproduction of the colours of the original product (catalogues for furniture, catalogues for the sale of prestige products, etc.). These varieties usually have a gloss, semi-matt or embossed finish and are printed on exclusively with the sheet offset system.

The basic uses of art paper varieties are to be found almost exclusively in the advertising sector. They can also, exceptionally, be used for publishing, but the books concerned need to be of a very high quality, and their use for this purpose is not very common.

In Figure no.1 can be seen an example of work completed on art coated paper.



Fig. 1: Printing on art coated paper.

2.2. Triple-layer paper

Triple-layer paper is similar to art paper, but with a thinner layer of coating, which makes its quality of printing slightly inferior. This is the variety which currently has the highest sales within the coated paper range.

The layer substance for this type of paper can vary between 25 and 30 g/m2 on each side of the sheet. It is found with a gloss, semi-matt or embossed finish, and is mainly printed in sheet offset, although it can occasionally be printed using the rotogravure system (normally for low substances) or using flexography (when used as part of self-adhesive product face material).

The main uses of triple-layer paper are especially in the advertising sector, although this type of paper can also be found in the high-quality publishing sector.

In Figure no.2 are shown some products printed using this type of paper:



Fig. 2: Printing on triple-layer paper.

In the following table is a list of the basic uses both of art paper and of triple-layer coated paper:

MAIN USES OF ART AND TRIPLE-LAYER COATED PAPER

Luxury publishing

Prestige advertising

Catalogues and brochures

Memoirs

Calendars

Book covers

Post-cards

Posters

Files



2.3. Double-layer paper

A characteristic of double-layer paper is that the substance of the layer of coating is about 20 g/m2 on both sides of the sheet. This type of paper can have a gloss, semi-matt, matt and even thick matt finish. The difference between the last two types of finish is in the release liner, which in the case of the thick matt finish will have a lower level of mineral composition (or load) so as to try to achieve a higher caliper.

Double-layer paper, also known as "industrial or modern coated paper", is used in the publishing sector, for colour supplements, magazines, catalogues, etc.

In the following illustration can be seen some examples of printing on double-layer paper:

Fig. 3: Printing on double-layer paper.

Double-layer paper can be printed on in sheets, but printing on reels is also quite frequent. In the case of our paper varieties, printing both in sheets and in reels is essentially carried out using the offset system. When printing on sheets, the action of this variety in the paper machine is similar to that of the previous varieties (art and triple-layer paper), although the profile of the print is less marked due to its thinner layer of coating. In the case of printing on reels, the paper passes through the rotary drying device known as the heat set, in which the temperature of the paper web can rise as high as about 130 ºC.

One particularity of the "heat set" printing system is that both sides of the sheet are printed simultaneously, and the drying process is carried out at the end. Due to the high temperature attained by the paper, any water it contains evaporates, making it come off the surface. This evaporation of the water may cause a problem of blistering, given that



the paper contains ink on both sides and usually in large quantities. Obviously, the problem will be less important if the quantities of ink concerned are small, and by the same token will be more critical in the case of gloss paper varieties, because they are more calendered and thus more closed in and less porous.

In order to avoid the problem of blistering, the release liner paper will be produced with a lower level of coating (so that it is more porous and will allow the water to emerge more easily). In such cases, the level of substance of the paper is not usually higher than 150 g/m2, due to the fact that when the substance increases, the porousness of the paper diminishes and the chances of blistering occurring increase. Paper on reels is also produced with a lower degree of humidity, so as to avoid problems both of blistering and of register.

In the case of double-layer paper, there is currently a variety with a quality of 80 g/m2 which is used as wrapping paper for cigarette packets and which replaces the old wrapping paper for cartons of ten packets. This type of product is printed using the rotogravure system.

In the following table the main uses of double-layer coated paper are listed:

MAIN USES OF DOUBLE-LAYER/ THICK COATED PAPER

School books

Direct Marketing

Diccionaries

Correspondence

Encyclopaedias

Magazines

Catalogues and brochures

Advertising

Memoirs

2.4. 1/s Coated Paper

1/s coated paper (with the coating on one side only) represents a speciality product within the range of double-layer coated paper varieties. It nearly always has a gloss finish, although it sometimes also has an embossed finish.

This type of paper always has a special treatment on the reverse side so as to avoid curling up of the edges, which is a very complicated problem that appears during printing, and is more frequent in this type of paper than in those with coatings on both sides due precisely to the fact of having a difference between the two sides of the sheet.



The market for 1/s coated paper is basically centred on labels, although the product also has a significant share in other markets, such as cigarettes (in terms of the soft packet sector), chocolate wrappers, book covers, etc.

1/s coated paper is considered a special paper, due not so much to the printing systems used with it (which are normally the conventional ones) as to the multiple treatments to which it is subsequently subjected, such as guillotining, die-cutting, or being used in "labelling devices". Depending on the end uses to which it is put, 1/s coated paper has numerous specialized varieties, such as the following:

Standard 1/s coated paper. This is a product which is used for labels that do not need any additional treatment, such as those used for wine or spirit bottles that are non-returnable (fig. 4).

Fig. 4: Label for non-returnable bottle.

WS 1/s coated paper. This is the paper which is used for labels for products sold in returnable bottles. Its treatment gives the paper a high level of resistance to humidity, so that when the bottles are washed before being re-filled and re-labelled, the old labels can be removed from the bottles without getting torn during the "washing" process. If this were not the case, they would cause dirtiness and make it necessary to change the washing water, which would greatly increase costs.

The designation WS (wet strength, or resistance to humidity) is also used for other products intended for the returnable bottle market, which we shall talk about later.

RH 1/s coated paper. This product is suitable for rotogravure printing and is essentially intended for yoghurt labels. This variety's main characteristic is that it needs a high degree of smoothness and compressibility in order to be able to be



printed on satisfactorily, in addition to a reverse side that can accept the attachment of heat-sealable glue so that the label can be attached to the plastic container of the yoghurt through the effects of heat.

Fig. 5: Yoghurt labels.

Fungicidal 1/s coated paper. This variety contains a bactericidal ingredient in order to be able to maintain suitable conditions for the product of which it forms the packaging (usually soap or other types of detergent). As far as printing is concerned, its characteristics are the same as those of a standard paper variety.

1/s coated paper for cigarette packets. This is normally used specifically for so-called "soft" packets, since "hard" packets are made with coated cardboard, which we will discuss below. Its basic characteristics are a high degree of smoothness and compressibility, since it is printed on using the rotogravure process. Its percentage of stress is lower than that of a standard 1/s coated paper variety, since it requires a high degree of stiffness in order to be able to withstand adequately its final stage of preparation, bearing in mind the high speed at which cigarette-packing machines operate.

1/s coated paper for self-adhesive products. The basic difference between this variety intended for self-adhesive products and other standard 1/s coated paper varieties is that it must have a higher degree of tensile strength so as to be able to withstand matrix stripping when the self-adhesive product is handled in reels. The printing systems used for this product are flexography, when printing takes place in reels, and offset, when printing is onto sheets.

In order to understand the matrix stripping process we can see the following illustration, in which a machine for printing self-adhesive paper can be observed, with a view of a blank reel and of a printed reel, as well as of the remaining part of the web. The web is usually fairly thin in order to make the most of the product, and thus if it is not strong enough it can break, and this will make it necessary to stop the machine.



Fig. 6: Matrix stripping in a machine for printing self-adhesive paper.

In the following table the main uses of 1/s coated paper are listed:

MAIN USES OF 1/s COATED PAPER

Labels

Wrappings (chocolate, soaps, etc.)

Book covers

Cigarette packets (soft packets)

Various compound products

3. Cast coated products

The characteristic feature of cast-coated paper varieties is that in their case the gloss is produced through heat rather than through friction, which to some extent conditions both the purposes for which they are used and the printing system to be applied. This type of paper is used basically when coated on one side only, although very occasionally it can be coated on both sides.

The consumption of this product has evolved over time, and if it was formerly common to find it in the high-quality packaging market, its consumption today is centred on the market for labels, especially of the self-adhesive variety. Nevertheless, it continues to be manufactured in high substances for packaging, files, menus, etc., although in some



of these markets it is being substituted by other products which we will discuss later. The reason for its abandonment in the packaging market may be its low level of resistance to rubbing, which makes it necessary to plasticize it in order to give it greater resistance. Logically carrying out this operation reduces the need for the product to be cast-coated, since the high gloss effect can be achieved through the use of the plastic.

Cast-coated paper can be white or, alternatively have coloured finishes. The printing system most used with it is usually offset, although in the case of coloured products it is necessary to know how the colour has been applied in terms of the use of the different inks.

In the case of certain products, the colour comes from the coating mix itself. In this case, the product can be printed on with the same inks as if it were white. In other cases, the colour is applied through a printing system that totally closes up the pores of the paper, and for this reason it is necessary to use inks with completely oxidative drying processes.

3.1. Types of cast coated products

Within the market for cast coated paper there are various different products, as described below:

Standard cast coated paper. This is used in the markets for labels (with low substances) and for packaging (for high substances). Printing is usually by the offset process.

Fig. 7: Applications of cast coated paper.



WS cast coated paper. As has already been noted, products classified by the designation "WS" are used for the labelling of "returnable bottles". In this market, this product is less frequently found than "1/s WS cast coated paper" due to its high price, although it is also used, especially for bottling high-quality products.

Fig. 8: Applications of WS cast coated paper.

Cast coated paper for self-adhesive products. This product is intended for manufacturers of self-adhesive products, including Adestor. As has already been noted with reference to 1/s cast coated paper, the product needs to have a greater tensile strength than standard paper types in order to be able to withstand the matrix stripping that takes place in reel printing machines. It can also be used in the same way as the "WS" paper type if it is intended to be used for the labels of returnable bottles.

Cast coated board. This product takes the form of folding boxboard or folding carboard (the product type will be defined later in this unit) with cast coating. It is used for packaging, but is found less and less frequently.



Fig. 9: Applications of cast coated cardboard.

Cast coated coloured paper. This variety is manufactured exclusively with a substance of 250 g/m2, and is used for packaging, menus, invitations, etc. As has been already noted, it is important to know the colour is added, so as to use the right ink for the printing process.

Fig. 10: Applications of cast coated coloured paper.

2/s cast coated paper. This product is not very frequently found, but it is sometimes used purely for advertising purposes, and thus its final uses are a little different from the most common applications of 1/s cast coated products. In some cases, the production process simply consists of sticking together the reverse sides of two 1/s cast coated products; in other cases, the product is cast-coated separately on each of its sides.



Fig. 11: Application of 2/s cast coated paper.

In the following table there is a summary of the end uses of cast coated products, with coating on one side and also on both sides.

PRINCIPAL APPLICATIONS OF CAST COATED PAPER

1/s cast coated 2/s cast coated

Labels for spirits, wine, champagne, etc.

Gift wrapping-paper

Bags

Decorative packaging

High-quality advertising

Displays

Boxes for luxury gifts

Brochures

Files

4. Carbonless coated paper

Carbonless paper is defined as paper that is capable of producing copies without the need to use carbon paper. In some markets it is also sometimes known as chemical paper, since copies are produced as a consequence of a chemical reaction between a layer of "transmitting" coating and another layer of "reactive" (or "receiving") coating.



The transmitting layer is formed by microcapsules containing the colour former, which is given this name (rather than that of colouring) because the colour is produced in the copy as soon as the colour former reacts with the coating of the receiving sheet.

The copy is usually black, although in some countries, a blue copy is produced, even if this is becoming less and less common. The only difference is in the colour former used.

Although carbonless paper also belongs to the sector of coated products, with this type of paper the aim of the layer of coating is not to obtain a higher quality of printing, but simply to produce copies.

According to the paper's intended use, we have the following types of carbonless coated paper:

CB (coated back) paper. In the market this is also sometimes known as "first-sheet paper", and represents the original of which the copy is required. On the reverse side it carries the layer of microcapsules that contains the colour former of the transmitting layer. It is produced in 56, 60, 70, 80 and 90 g/m2.

CF (coated front) paper. It is also sometimes known as "third-sheet paper", and is the paper that carries the reactive (or receiving) layer that reacts with the colour former in the microcapsules. It is produced in 57, 70, 80, 90 and 173 g/m2.

CFB (coated front and back) paper. Is also called "second sheet paper" and is used when more than one copy is to be made. All the remaining copies will be formed by this sheet, which carries the reactive layer on the front side, and the transmitting layer on the reverse side. It is usually produced in 45, 53, 60 and 70 g/m2. Normally, the lower the substance of the paper, the larger the number of copies that it will be possible to make, although it is unusual to use more than five copies, with rare exceptions.

When the original and one copy are required, a CB and a CF sheet are used, respectively. If more than one copy is required, a CFB sheet is used for each of the intermediate sheets.

Torraspapel's commercial brand name for carbonless paper is Eurocalco. In the following illustration the operating system for these products is shown.

Fig. 12: Use of carbonless paper.



4.1. Types of carbonless coated paper

We shall now look at some specialized types of carbonless products:

CB Plus paper. This is a sheet of CB paper which on the front side is coated with "conventional coating". What is the purpose of this type of product? The answer is simple: when the user of the end product uses CB paper to issue an invoice, the front side of the sheet is uncoated, which reduces the quality of the print. If a sheet is used which is coated on the front side, it is guaranteed that the final recipient will receive a document with a higher quality of print.

ORC (Optical Character Recognition) CB paper. This is a product of a quality especially designed for optical character recognition, and in which use is not made of fluorescent whitening agent, which could interfere with the reading due to the machines used in these processes.

Self-contained coated paper. This product has the two layers of coating, i.e., the transmitting and receiving layers, on the front side of the sheet. This enables it to be used as a "third sheet", with a first sheet made out of ordinary paper, i.e., paper which is not carbonless.

Torraspapel's commercial brand name for its self-contained carbonless paper is UNIT (fig. 13).

Fig. 13: The use of self-contained coated paper (Eurocalco UNIT).

CB self-contained carbonless coated paper. In this case, the self-contained carbonless product could act as a second sheet in a set of three sheets, in which the first sheet would be ordinary paper and the third sheet a normal CF product, as shown in figure 14.



Fig. 14: The use of self-contained carbonless paper (Eurocalco UNIT CB).

4.2. Uses of carbonless paper

The most frequent applications of carbonless paper are included in the following table:

PRINCIPAL APPLICATIONS OF CARBONLESS PAPER

Forms

Delivery-notes and invoices

Chequebooks

Carbonless paper normally involves the use of a certain number of special products:

Self-separating glue

De-sensitizing ink

Sprays or felt-tipped markers

The organizations that supply carbonless paper also sell these products. We shall now briefly look at their methods of use.

A. Self-separating glue

When chequebooks are produced using carbonless paper, this glue is used to facilitate the separation between the different sets. Imagine that the finished product is a set of three sheets, i.e., one original and two copies. The printer will therefore buy the same quantity of each of the three sheets, will print them and will subsequently carry out the gathering, i.e., will insert each type of sheet in the correct order to make up successive sets.

In figure no.15 we can see a set of three sheets: CB, CFB and CF. Before this set a CF sheet from the previous set will have been placed, and after it, a CB from the following set. Once the gathering has taken place, the sheets will be guillotined along the side on which they will need to be glued together so that they are all well aligned, and the glue will then subsequently be applied by brush.



Fig. 15: Separation of sets of sheets by means of self-separating glue.

If we look at Figure No. 15 again, we can see that, just where one set of sheets ends and the next one begins there is an uncoated area. At this point the glue will penetrate very little, whilst in the coated areas the glue will penetrate much more, with the result that the sheets will be strongly glued together within the same set, but only slightly with the previous and following sheets. It is precisely for this reason that this type of glue is known as self-separating glue, because it sticks together the sets of sheets and makes it easy to separate each set from the others.

B. De-sensitizing ink

This is a colourless type of ink that is used when we require that some of the receiving sheets have areas in which we do not want the copy to be seen, which occasionally occurs.

Let us imagine an order form where we do not want the price to be visible on the sheet sent to the factory. The printer will then apply de-sensitizing ink to this area of the form, and in this way will prevent it from being copied.

C. Revealing sprays or felt-tipped markers

Since the de-sensitizing ink is colourless, sprays or markers are used to check that the ink has been properly applied. Thus, once the ink has been applied, if we spray the area to which the ink has been applied or we pass the marker pen over it, this will show any areas to which the ink has not been applied, which will turn black or blue, according to the colour former which has been used.

If in the area where the ink has been applied black or blue stains appear, this will indicate that we are applying insufficient ink. On the other hand, if in areas where the de-sensitizing product has not been applied small colourless areas appear, this means that an excessive quantity is being applied, and therefore that de-sensitizing ink is being applied to areas where it is not required.



5. Thermal paper

Thermal paper is another type of coated paper that has undergone a process of constant evolution in the last few years. This is a type of paper on which printing takes place through the effects of heat.

Thermal paper also has two layers of coating (see fig. 16) on the same side of the paper, although the two layers do not react between each other.

The undercoating (or "U.C."). This is the lower layer that guarantees a uniform, smooth surface on which the thermal coating (or thermal layer) is applied. It also helps provide high resolution and a high quality of image, and prevents the heat reaching the paper.

The thermal coating. This is the top layer, which is made up of a large number of chemical compounds that, when subjected to heat, react among themselves and develop the image without interacting at all with the U.C. layer. The main components of this layer are: a colouring, a sensitizer (or coreactant) and a colour former.

Fig. 16: The composition of thermal paper.

The activation of the thermal layer will be triggered by a thermal header (fig. 17) that will liquefy the layer by making the colouring react with the colour former, thus forming the final image.

Fig. 17: Printing on thermal paper.



5.1. Types of thermal paper

Apart from layers of coating, the various types of thermal paper sometimes may have special protective treatment, whether it be against heat, grease, plasticizers, etc., depending on their final use, as well as types of treatment to allow printing.

Furthermore, these types of paper can be classified into non top coated, semi-topcoated and top coated varieties.

The following table lists the range of thermal papers sold under Torraspapel's Termax brand-name, according to the substance in which they are manufactured and the use to which they are put. In this case all the varieties can be classified as "non top coated", except the last one (Termax TRO), which is "semi-top coated".

TYPES OF THERMAL PAPER (TORRASPAPEL)

Characteristics and applications Substance

Termax SF1 Thermal paper for faxes and standard applications. Colour: white.

55 g/m2

Termax SF1C

Thermal paper for receipts and standard applications. Colours: yellow, pink, green and blue.

55 g/m2

Termax LNC (Label Non Coated)

Non-protected thermal paper for labels and self-adhesive applications.

74 and 105 g/m2

Termax ONC (Offset Non Coated)

Thermal paper that is guaranteed for offset printing on the thermal side of the sheet, suitable for receipts, bank statements and labels.

57 and 77 g/m2

Termax PRN (PRinter Non Coated)

Non-protected high- sensitivity thermal paper. Suitable for receipts and tickets.

80 g/m2

Termax PHR Heat-resistant thermal paper 55 and 75 g/m2



(Printer Heat Resistant) used for parking metres and other applications which require heat-resistance.

Termax TRO (Ticket Resistant Offset)

Semi-protected thermal paper that is resistant to heat, light and plasticizers, and which is guaranteed for offset printing on the thermal side of the sheet. Its principal applications are for tickets for entertainment and labels.

105 g/m2

All varieties of thermal paper are suitable for printing on, but for certain types of printing some kind of special protection is required.

6. Metallized paper

Metallized paper has a layer of aluminium on top of the layer of coating. In the following illustration the structure of metallized paper is shown in schematic form.

Fig. 18: The structure of metallized paper.

The quantity of aluminium used depends on whether we are dealing with metallized paper with face material or with high-vacuum metallized paper. We shall talk about the latter case because this is the variety that we produce, although we use both types as release liners for self-adhesive products.

In the case of high-vacuum metallized paper, the quantity of aluminium that it contains varies between approximately 0.08 and 0.1 g/m2. Our product has the brand-name Metalvac, and may be either smooth or embossed. Smooth varieties can have a mirror or matt finish, and in colour are usually either silver (aluminium’s normal colour) or gold (dyed using a special colouring).



The end uses of this product are varied, although the most important ones are listed below:

MAIN USES OF METALLIZED PAPER (METALVAC)

Labels

Cigarettes and tobacco


Gifts

Packaging

Foodstuffs

6.1. Types of metallized paper

Within the range of Metalvac metallized products there are several different varieties, which we shall describe below:

Metalvac E. This product is used for non-returnable bottles, for example, for spirits, wines, etc. It is produced in substances of 75, 85 and 95 g/m2, and can be printed on using any printing system.

Metalvac E UV grade is used when printing takes place using UV curing inks.

Metalvac E WS. The initials "WS" ("Wet Strength") indicate that the paper is resistant when wet. Given that aluminium tends to form a closed-in layer, and that together with the inks used can make it difficult to remove labels or, on the other hand, can cause excessive dirtying of the washing basins, there exists a series of special products that we list below:

Metalvac E WS QR Plus. This product is designed for labels of returnable containers requiring conventional offset printing. The initials "QR" stand for "quick removal", i.e., this product is specially designed to allow for rapid removal of labels in bottle-washing machines without dirtying the basin. In this case printing on paper with an embossed finish is recommended.

Metalvac E WS IR. This product is specially designed for rotogravure printing. Embossing after printing facilitates the removal of labels. The initials "IR" ("ink retention") indicate that the product has high resistance to



the loss of ink, which makes it possible to minimize the dirtying of basins during the washing process.

Metalvac E WS UV. This product grade is suitable for labels that need to be resistant to humidity and are going to be printed on with UV-curing inks. It is not appropriate for labels intended for returnable bottles.

The Metalvac E WS grade is produced in 60, 65, 70 and 75 g/m2. Substances of 60 and 65 g/m2 are normally used for bottle neck-labels, whilst 70 and 75 g/m2 substances are used for bottles' main front-labels.

Metalvac A. This product is intended for self-adhesive labels. As in other cases, the product needs to have special tensile strength to withstand the matrix stripping that takes place during printing of the reels. It is produced in 85 g/m2.

Metalvac A WS. This is similar to the previous product, but with a special treatment to enable it to be used with returnable bottles. Like the previous product, it is produced in 85 g/m2.

Metalvac T. A product which is used as the inside wrapping in cigarette packets. Its main characteristic is that it must not give off metal dust during the process of forming the packet, thus avoiding contamination from small particles of aluminium. It is likewise produced using water-based glaze so as to avoid the transmission of any type of odour or flavour. It is produced in 50 and 60 g/m2, and is not printed on.

Metalvac R. Is used for gift wrapping, bags and linings for gift boxes, as well as for decoration. It has a high level of mechanical resistance and a very glossy finish, and it is compatible with all printing systems. It is produced in 50, 55, 60, 65 and 70 g/m2.

Metalvac F. This is used for the production of wrapping for chocolate and for food products in general. Its main difference in relation to other products in the range is its special treatment which guarantees the non-diffusion of odours or flavours that could have a detrimentary effect on the foodstuffs. It can be printed using any system of printing, including ultraviolet-cured inks. It is produced in grammages of 85 and 95 g/m2.

Metalvac B. This type of paper is specially designed for tablecloths, trimmings and trays for pastry and confectionery. In addition to not passing odours or flavours to foodstuffs, it also has special treatment to avoid deterioration when in contact with alcohol. It is not recommended for printing, and it is produced in 55, 60, 65 and 70 g/m2.

Metalvac CS. This is a metallized cardboard specially designed for luxury packaging for products such as perfumes, cosmetics, champagnes, wines, etc. It can be printed on using any printing system and it is produced in 300 g/m2.



In the following illustration are shown some of the uses of metallized paper of which we have already spoken.

Fig. 19: Different uses of metallized paper.

7. Solid Bleached Board (SBB)

The word cardboard is, without any doubt, a word that can cause an enormous amount of confusion, especially for anybody who does not work in the commercial department, and the fact is that printers tend to use this name for any product with a substance higher than 160 or 180 g/m2. Given that at the same time there exist other products, both coated and non-coated, that are known specifically by the term "cardboard", this causes the confusion of which we have spoken above.

In this section, however, we shall deal exclusively with the types of cardboard known internationally as SBB (Solid Bleached Board) and which are produced from bleached chemical pulp.

The first thing to note about this type of product is that the material of which the cardboard is made is not one single layer as in the case of paper, but is made up of several layers (it can consist of between 3 and 5 layers of fibre), of which the top layer is named the "face", the bottom layer is called the "reverse", and the middle layers the "belly".

Fig. 20: The basic layers of SBB cardboard.



This multi-layer material of which SBB cardboard is made is produced in a machine with a humid section that is somewhat different from the conventional paper machine. In Figure no. 21 is shown a diagram of this type of machine, which is made up of three entry boxes (C1, C2 and C3) and three webs (T1, T2 and T3). With the left-hand box (C1) the "face" is produced on the web T1; with box C2, the "belly" on web T2; and with box C3, the "reverse" on web T3. In some machines the belly is produced with three entry boxes and three webs, but there will always be a minimum of at least three layers.

Fig. 21: Flat table for the production of cardboard.

This method of production is essentially due to the following reasons:

With high-substance products, as is the case here, it is difficult to obtain a smooth finish. By using three layers, the grammage of the material is divided among them, which makes it possible to produce three thinner layers that therefore have a higher degree of smoothness, leading to a better product when it is coated.

The stiffness of the final product is increased.

It is possible to combine layers with different types of fibres: e.g., with all the layers made of chemical pulp; or with some of chemical and others of mechanically-produced pulp; or even with layers made from recycled paper.

7.1. Types of SBB cardboard

SBB cardboard can be coated on one side or on both, although the basic market requirement is for one side only. Cardboard coated on one side can occasionally have a small layer of coating on the reverse side, designed to improve the printing quality on that side if it has to be printed on, but they are nevertheless two different layers of coating, so that such a product is still considered as coated on one side only. SBB cardboard is occasionally also sold uncoated.

In the following example some of these types of cardboard are listed.



EXAMPLES OF TYPES OF SBB CARDBOARD

GZ, 1/s, SBB cardboard (coated on one side)

GZ, 2/s, SBB cardboard (coated on both sides)

UZ cardboard (uncoated)

The initials GZ indicate that the finish is cast coated, a subject to which we have already referred above, although this type is used less and less frequently as a form of packaging. Nevertheless, we also include it here because this type of product still competes in some markets, although less and less frequently.

There is also another variety of this type of cardboard that is plasticized on one or both sides with different coats of film (polyethylene, polypropylene, polyester, etc.) and which is intended for the packaging of frozen or pre-cooked products. It also plays an important part in the cigarette market as far as hard packets are concerned.

Types of cardboard that are plasticized are not normally coated. The plasticization of these products is usually carried out before printing; it is occasionally carried out after printing, but only with the aim of protecting or embellishing, as in the case for example of postcards.

If plasticization is to be carried out before printing, the product will be treated in the factory, and, as we have noted above, this will be the case especially for products designed for use with foodstuffs. They can also have metallized treatment suitable for high-quality packaging. Plasticization on site in a factory can be carried out on both sides of the product, in which case the coating on the upper side is usually of higher quality so as to enhance the quality of the printing, whilst the coating on the reverse side is applied only through the need for protection (to act as a barrier against too much light, hot air, grease, etc.).

The plastics most used are polyethylene, polypropylene and polyester. The choice of using one or the other, or the quantity to be used, depends on the needs of the product that is to be packaged, as well as the possible uses to be made of the product by the final customer (for example, the same plastic will not be used for a tray that is going to be heated in a conventional oven as for one that is going to be heated in a micro-wave, where the temperatures are lower). Likewise, the degree of resistance to grease required by a type of cardboard will decide which type of plastic is to be used.

The main uses of SBB cardboard are listed in the following table:



THE MAIN USES OF SBB CARDBOARD

Book covers

Catalogues

Postcards and greetings cards

Advertising material

Cigarettes (hard packets)

Pacaging for perfumes and cosmetics

Files

Index cards

Food products

Glasses, plates

Pre-frozen foods

Pharmaceutical products

8. Folding boxboard

Folding boxboard is a product with the same production system as the various types of cardboard, but is distinguished from the latter by the fact that the middle layer (belly) is made from mechanically-produced pulp, which results in greater caliper for the same grammage, which therefore gives greater stiffness.

Since folding boxboard is a product with a high degree of stiffness it is used essentially for packaging of products for which a high level of productivity is required, such as pharmaceutical products, some types of foodstuffs, etc.

One characteristic of folding boxboard is that the reverse side can be either white or wood-coloured, giving two different products with the following international designations:

GC1 (white backed folding boxboard). This product can, in certain market conditions, replace cardboard. It should nevertheless be borne in mind that the core of this product is yellow due to the mechanically-produced pulp, and for certain uses, such as for postcards, a yellowing effect can be produced through contact with sunlight when the product is placed on public view. As can be seen in Figure no.22, white backed folding boxboard can be coated on the reverse side with a thin layer of coating in case it needs to be printed on. It



does not however always have this coating; this will depend on the individual manufacturer.

Fig. 22: The structure of white backed folding boxboard.

GC2 (wood backed folding boxboard). This product is used essentially for packaging. It can sometimes be cast coated, as was mentioned in the section dealing with this product. The "wood" colour is obtained by reducing the thickness of the reverse side, thus showing the "belly", which already has the yellowish colour typical of mechanically-produced pulp.

Fig. 23: The structure of wood backed folding boxboard.

Folding boxboard can also be plasticized at point of manufacture so as to be used for food packaging requiring this type of protection. In the same way, when both sides are plasticized, the same criteria are followed as with cardboard varieties.

The two products mentioned above are the types of folding boxboard sold by our different distributors. Nevertheless, there are also other products existing on the market with different structures, and which are listed in the box below:

EXAMPLES OF FOLDING BOXBOARD

Kraft floating boxboard, SUS

Non-coated white backed folding boxboard, UC1



Non-coated wood backed folding boxboard, UC2

AZ folding boxboard (identical to Eurokote CS)

Finally, in the following box is a list of the main end uses of folding boxboard.

MAIN USES OF FOLDING BOXBOARD

Packaging for pharmaceutical products

Cosmetics

Sweets and confectionery

Cigarettes

Wines and liqueurs

Refrigerated products

Pre-cooked foods

9. Boxboard

Boxboard is a product that is produced with the same structure as folding boxboard, except that instead of using virgin fibres, use is made of a large amount of recycled fibres (and sometimes up to 100%). They are essentially used for the packaging of cleaning products.

In the past there also used to be recycled folding boxboard and cardboard varieties, although it should be added that since this type of product always needs to be produced using primary fibres, sales are becoming less and less frequent, although they still continue.

For identifying varieties of cardboard, folding boxboard and boxboard a special naming system is used which makes it possible to find out what type of product it is and what treatment it has received.



Boxboards can be of two types:

Coated boxboards. Within this category the following are worthy of note:

GT boxboard: this group can be sub-divided into GT1, GT2 and GT3.

GD boxboard: can be subdivided into GD1, GD2 and GD3.

In the following box are listed the characteristics which differentiate each of these types of coated boxboard.

TYPES OF BOXBOARD

Coated GT Coated GD

GT1 GT2 GT3 GD1 GD2 GD3

Specific volume (cm3/g)

1.45 1.45 - 1.30 1.30 1.45 1.45 - 1.30 1.30

Whiteness (%) 82 80 - 81 78 - 80

Elrepho 82 80 - 81 78-80 Elrepho

Reverse colour

White/Wood

Wood/ kraft Wood Grey Grey Grey

Non-coated boxboard. The main products in this group are:

UT boxboard

UD boxboard.

In the following box the end uses of the various types of boxboard are indicated:

MAIN USES OF BOXBOARD VARIETIES

Cleaning products

Detergents



In some cases a layer of 200 or 220 g/m2 boxboard is combined with micro-channel board. Although the market for corrugated board is different, in some cases this combination is used, since in view of the fact that the boxboard is coated, the quality of the printing is much better. It is very common to find this type of product in packaging for biscuits.

The reason for this combination is that the final product is cheaper, but nevertheless gives greater stiffness. Its structure can be seen in the following illustration. The microchannel board is nearly always made from recycled paper, whilst the basic paper may be made from recycled or virgin fibre, according to the stiffness required for the end product.

Fig. 24: The structure of boxboard combined with microchannel board.

10. Self-adhesive products

During the course of this unit we have talked about labels and we have seen that many types of coated paper (1/s, cast coated types, thermal and metallized paper, etc.) can also be used in self-adhesive form for the production of self-adhesive labels. Nevertheless, it should be noted that in these cases it is the end users of the products who have to put the glue on the paper before attaching it to the relevant release-liner.

In the case of self-adhesive products, the glue is already on the product. Obviously, this will involve using different types of machines to apply the products (see Fig. 25), as well as a different variety of release liner.

Fig. 25: Machine for applying self-adhesive labels.



A self-adhesive product is made up of three component parts (see Fig. 26): the face material, the adhesive and the release liner. The face material is the product that finishes up as the label, whilst the release liner, which needs to be silicon-coated so that the self-adhesive adheres to the face product only, will be disposed of after the label has been stuck to the relevant surface.

Fig. 26: The structure of a self-adhesive product.

Self-adhesive products can be produced in sheets or in reels. In the case of production in sheets, printing is normally carried out in offset, although it can also sometimes take place using the silkscreen printing technique, especially when plastic or metallized release liners are used. In the case of production in reels, the most important printing system used is flexography, although some letterpress, rotogravure and silkscreen printing are also used. There are now machines on the market for printing self-adhesives in reels in which different printing systems are combined.

The main end uses of self-adhesive products are listed in the following table:

MAIN USES OF SELF- ADHESIVE PRODUCTS

Labels for publicity campaigns

Computer labels

Price-labels

Children's stickers and games

Labels for perfumes, cleaningproducts, etc.

It should also be noted that there are products in which basic labels co-exist with self-adhesive labels, just as there are markets where one of the two products is more important than the other. Let us give an example.

If we look at the market for "cava" (Spanish champagne-style wine), we can see that the two types of label co-exist. Thus when talking of the production



of large quantities of bottles, the labels will be normal; on the other hand, if we are talking of shorter production lines, the normal practice is to use self-adhesive labels which, although they are more expensive, are also cleaner and easier to apply. If we turn to the market for pharmaceutical products, for cleaning products or for fruit, etc., the type of label most frequently used is the self-adhesive variety, whilst in the case of beer or soft drinks, normal labels are the type most commonly found.

10. 1. Types of self-adhesive product

The different types of self-adhesive product which are produced vary according to the type of face material, adhesive and release liner used. We list the different types of product below.

A. Types of face material

Face material for self-adhesives can be obtained from the following types of paper:

FACE MATERIAL USED IN SELF-ADHESIVE PRODUCTS

Uncoated

Double-layer matt coated

Double-layer gloss coated

Triple-layer gloss coated

WS (Wet Strength) coated

High gloss

Colour coated

Fluorescent coated

Matt and gloss laminates

Matt and gloss metallized coated

Polypropylenese

Opaque polyethylene

Transparent polyethylene

Acetates

CF carbonless

Coated cardboard

Parchment-style paper

Thermal paper



B. Types of release liner

In the case of release liners we need to distinguish between those used for sheets and those used for reels, and the different varieties are shown in the following table:

TYPES OF RELEASE LINER FOR SELF-ADHESIVE PRODUCTS

Sheets

Kraft 80 g/m2. Kraft 87 g/m2 (yellow). Kraft 90 g/m2. Kraft 130 g/m2 for plastic

release liners.

Reels

Glassine 62 g/m2 (yellow, white or blue).

Glassine 80 g/m2 (white). Kraft 55, 74, 80, 90 and 130

g/m2.

The use of the various different release liners depends on the type of face material used, the system used for applying the label, etc.

C. Types of adhesive

The adhesives used can vary according to the system of application used, the surface concerned, the end uses, etc. We list the most frequently used adhesives below:

Removable adhesives. Those that can be removed after they have been applied.

Permanent adhesives. Those that cannot be removed once they have been applied. Their most frequent uses are:

Stickers. Fruit. Returnable bottles. Non-returnable bottles. Frozen foods. Solubles in water.



Depending on the end use, and on the system used to apply the adhesive, certain characteristics can be varied. For example, we need to be able to remove a sticker if we make a mistake when attaching it, and so for this reason it will have a low rate of "tack" (or initial adhesiveness). On the other hand, in the case of an orange, where the label is applied automatically, it is important for the label to remain attached to the orange when it touches it, since otherwise the orange will have no label. This will require a high rate of "tack". In both cases the adhesives are permanent, but with different characteristics.

Super-permanent adhesives. These are used when the surface to which we attach the label presents problems of adhesiveness.



Summary

Coated products

Those products which have a surface coating (or "coating mix") made up of a series of mineral and organic components, and which is applied in order to improve their printing characteristics.

Coated paper Depending on the number of layers of coating, the method of presentation and the type of printing system used, the following types of product can be distinguished:

Art paper. This type of paper has three layers of coating on each side, which gives a very high quality of printing. There is usually a choice between gloss, semi-matt or embossed finishes, and it is printed in sheets with the offset system. It is mainly used for advertising purposes and, exceptionally, for very high quality books.

Triple layer. This type is available with a gloss, semi-matt or embossed finish, and is mainly printed in sheets with the offset system, although on occasions rotogravure or flexography may also be used. It is mainly used for advertising and, occasionally, for high quality book publishing.

Double layer. Can be found with a gloss, semi-matt, matt, and even thick matt finish. Is used for publishing, magazines, colour supplements, catalogues, etc. Can be printed in sheets or reels, mainly in offset printing.

1/s. Usually has a gloss or (occasionally) embossed finish, as well as a special treatment on the reverse side to avoid curling at the edges. Is used mainly for labels, but also for cigarette packets, chocolate wrappers, book covers, etc.

Cast coated products

With this product type, coating is carried out mainly on one side only of the sheet (rarely on both sides), and the gloss finish is obtained through a heat treatment. It can be printed in colour and the printing system most frequently used is offset. There are various different types: standard, WS, self-adhesive, cardboard, colour, 2/s.



Its use is mainly for labels (especially self-adhesives), although it is also still frequently used in high grammages for packaging, files, menus, etc.

Carbonless products

These are used to copy original documents by means of a chemical reaction between a ¨transmitting¨ layer of coating (made up of micro-capsules that contain the colour former) and another ¨reactive¨ layer of coating (which reacts with the colour former).

There are basically three varieties of this product: The CB or "first sheet" (the original that has the transmitting layer on its reverse side), the CF or "third sheet" (which has the reactive layer on the upper face), and the CFB or "second sheet" (used when there is more than one copy, with a reactive layer on the top side and a transmitting layer on the bottom side.

Some varieties of carbonless paper are: CB plus, CB ORC, self-contained, self-copying self-contained CB. Its basic uses are for forms, delivery-notes, invoices and cheque-books.

Thermal paper This product has two layers of coating on the same side of the sheet: a layer of undercoating (UC) and a thermal layer that contains the components that will react to implement the printing process. Printing takes place through the effect of heat by means of a thermal header that activates the thermal layer. This product sometimes includes special types of treatment for protection and for printing.

The different types of thermal paper are: Termax SF1, Termax SF1C, Termax LNC, Termax ONC, Termax PRN, Termax PHR, and Termax TRO. They are mainly used for faxes, receipts, labels, etc.

Metallized paper

This product has a layer of aluminium on top of a layer of coating, and can be divided into metallized paper with face material, or high-vacuum metallized paper. The latter varieties can be smooth or embossed.

The most important uses of metallized paper include: labels, cigarettes, self-adhesive products, gifts, packaging and other uses connected with foodstuffs.

Solid Bleached Board (SBB)

Types of cardboard with high grammages produced from bleached chemical pulp and characterized by a high level of



stiffness. They are made up of various layers of fibre: the face (top layer), the reverse side (bottom layer) and the belly (the central layer).

This type of cardboard is usually coated, although it can sometimes be sold without coating. It can also be plasticized, in which case it is not usually coated. Its uses are highly varied: book covers, catalogues, postcards and greetings cards, advertising material, cigarettes (in hard packets), packaging for perfumes and cosmetics, files, index-cards, food products, glasses and plates, frozen food, and pharmaceutical products.

Folding boxboard

This is a product that is similar to SBB, but with the difference that the central layer (belly) is made up of mechanically-made pulp, which gives a greater calibre for the same level of grammage, and thus a higher degree of stiffness. The reverse side may be white (GC1) or wood-coloured (GC2).

Its main uses are: packaging for pharmaceutical products, cosmetics, sweets and confectionery, cigarettes, wines and spirits, and for refrigerated and pre-cooked foods. Folding boxboard can also be plasticized at the point of production for use in food packaging.

Boxboard This product is produced with the same structure as folding boxboard, but using a large amount of recycled fibres. Boxboard can be of two types: coated (GT and GD) and non-coated (UT and UD). It is basically used for packaging for cleaning products and detergents.


These are products to which glue is applied during their production. They are made up of three parts: the face material (uncoated, double-layer coated, metallized, cast coated, etc.), the release liner (for sheets or reels) and the adhesive (removable, permanent or super-permanent).

Their main uses are: promotional labels, computer labels, price labels, stickers and children's games, labels for perfumes, cleaning materials, etc.

TORRASPAPEL, S.A. - Llull, 331 - 08019 Barcelona © 2008 TORRASPAPEL, S.A. Complete or partial reproduction of this document, without express previous and written authorisation, is strictly prohibited.

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