EP1860235A1 - Coated paper with improved labelling properties - Google Patents

Abstract

Producing coated paper comprises applying an aqueous coating composition to raw paper in an amount of 10-40 g/m 2> (dry basis) and conditioning the coated paper. The raw paper has a long-fiber cellulose content of at least 25 wt.%, an absolute moisture content of at least 2.5%, a water absorption capacity of 5-20 g/m 2> and a fenchel wet expansion of no more than 0% in the machine direction and no more than 3% in the cross direction. An independent claim is also included for coated paper produced as above.

Description

The present invention relates to a coated paper having improved labeling properties, and to a method for producing such a paper.

Coated papers can be found in a variety of applications. They are often characterized by a very smooth, coated surface on which high-quality prints, especially in the offset printing process can be applied. For example, coated papers are also used for labeling and labeling of goods. One of the main applications is the labeling of bottles. In the prior art, various methods for labeling bottles are known, which among other things, the application of self-adhesive adhesive labels counts, as well as the so-called "wet labeling".

When wet labeling an adhesive layer is applied to the back of the already printed label, which is then applied immediately below to the bottle to be labeled. The adhesive usually contains a high content of water and is often built on a casein base.

The labeling machines process up to several tens of thousands of bottles per hour, so that a high reliability of the labeling process must be guaranteed. In particular, it is necessary that the labels can be accurately applied to the bottles, so that skewed positions of the label on the bottle are prevented. In addition, it is necessary that the labels adhere to the bottles immediately after application, otherwise they can slip by further mechanical contact, with, for example, brushes, which serve to press the label of the bottles tight. Since the surface to be labeled (adhesive surface) is curved in accordance with the shape of the bottle, there is also the risk that the flat label does not adapts ideally to the curvature despite the brush effect. As a result of insufficient adjustment is often observed that the corners and edges of the label with the adhesive surface underneath connect only incomplete and therefore stand out. In addition, there is a general danger that labels slip off the bottles and thus block conveyor belts or other mechanical facilities of the filling system.

There has been no lack of effort in the art to produce papers with improved wet-etch properties.

By doing U.S. Patent No. 5,209,982 For example, a method of making labeling paper for bottles is disclosed. The label paper is characterized in that on the back of the label on which the label is applied, the adhesive, a coating is present, which improves the suitability of the label for labeling. By the coating, the water absorption of the back is improved, so that the penetration of water, the rigidity of the base material is deteriorated. For this purpose, it is proposed to use a particularly active, absorbing agent.

Methods are also known in the prior art which achieve improvements in the labeling behavior on curved surfaces at the expense of the strength properties of the label paper. In the process, strain gauges are produced on the label with the aid of cutting punches, which breaks the inherent rigidity of the label and prevents it from lifting off its corners and edges from the substrate. A disadvantage is the additional process step of cutting punching, as well as the associated mechanical damage to the material.

The German patent DE 44 15 547 C2 describes a paper label for bottles which is printed and applied with the aid of a glue and whose fibers are predominantly oriented in one direction. In order to avoid the occurrence of protruding edges and corners in the labeling process on curved surfaces, an embossing of the label is proposed perpendicular to the fiber direction, which ensures that the label wraps around more quickly and easily to problem areas of high curvature. Another disadvantage is the additional process step of embossing, which also leads to a material weakening by fiber breaks in the nonwoven fabric.

The prior art also discloses numerous metallized coated papers. In the EP 00 98 368 A2 there is disclosed a cast-coated metallized paper in which, among other ingredients, a synthetic polymer pigment is contained within the cast coat layer. Due to the specific composition of the cast-coated paper, a subsequent treatment of the cast-coated layer, for example by painting, prior to metallization is thus avoided. On such a cast-coated paper, a metallization can be performed immediately on the high-gloss surface layer, which has a very good metallic luster.

Typical of all cast-coated papers (metallized or non-metallized) is their low densification in the manufacturing process - in contrast to papers whose high-gloss surface layers are obtained by calendering processes, which are accompanied by a very strong compaction in particular of the fiber structure. The low densification of cast-coated papers is associated with high integrity of the paper fiber structure, with high volume (thickness) and high (intrinsic) stiffness of the label, properties that usually worsen the labeling and make it incalculable, uncontrollable.

Thus, the technical object of the present invention is to provide a paper which has improved labeling properties, in particular in the wet labeling of bottles, from the prior art. In particular, the reliability of the labeling process is to be increased by providing an improved paper. In addition, the provided on the back with adhesive label should adhere better to the bottle after application to the bottle to be labeled, so that it no longer slips in subsequent Andrück- and drying steps, or falls off the bottle. The corners and edges of the label should not protrude but completely connect to the bottle. Another object of the present invention is to provide a process for producing a cast-coated paper having improved labeling properties.

1. a) Bereitstellung eines Rohpapiers, wobei der Anteil an Langfaserzellstoff im Rohpapier mindestens 25 Gew-% ist, das Rohpapier ein Wasserabsorptionsvermögen gemäß ISO 535 bei einer Prüfzeit von 10 s (Cobb₁₀) von 5 bis 20 g/m² aufweist, und das Rohpapier eine Nassdehnung (nach Fenchel) gemessen parallel zur Maschinenrichtung von nicht größer als 0% und quer zur Maschinenrichtung von nicht größer als 3% hat,
2. b) Aufbringen von 10 bis 40 g/m² (ofentrocken) einer wässrigen Beschichtungsmasse auf mindestens eine Seite des Rohpapiers um ein beschichtetes Rohpapier zu erhalten, und
3. c) Konditionieren des in Schritt b) erhaltenen gestrichenen Papiers.

The technical problem is solved by a method for producing a coated paper, comprising the steps:

1. a) providing a base paper, wherein the proportion of long fiber pulp in the base paper is at least 25% by weight, the base paper has a water absorption capacity according to ISO 535 at a test time of 10 s (Cobb ₁₀ ) of 5 to 20 g / m ² , and the base paper has a wet stretch (after fennel) measured parallel to the machine direction of not greater than 0% and transverse to the machine direction of not greater than 3%,
2. b) applying 10 to 40 g / m ² (oven dry) of an aqueous coating composition on at least one side of the base paper to obtain a coated base paper, and
3. c) conditioning the coated paper obtained in step b).

Preferably, the coated paper of the present invention is a cast-coated paper. For the purposes of this invention, the terms coated paper and coated paper are used interchangeably.

For the purposes of the present invention, the term "long-fiber pulp" is understood as meaning a pulp which has a longer fiber length than e.g. Short-fiber pulp. An example of a long fiber pulp is a needle sulfate or needled sulfide pulp. Preferably, the base paper contains at least 30 weight percent, more preferably at least 35 weight percent, and most preferably at least 40 weight percent of long fiber pulp.

The water absorption capacity is determined in accordance with ISO 535. ISO 535 defines the so-called "Cobb process". This determines the water absorption of a paper after it has been exposed to water. In the present case the test test time is 10 seconds. In this case, the paper to be tested is exposed to an excess of water for 8 seconds and after a total of 10 seconds, the excess water is removed by means of a blotter.

The base paper of the present invention preferably has a Cobb ₁₀ of 5 to 15 g / m ² , more preferably 5 to 13 g / m ^2, and most preferably 6 to 10 g / m ² .

The wet stretch after fennel was measured with an apparatus as described by Siebel in " Handbuch der Werkstoffprüfung ", 2nd edition, 4th volume (1953, Springer-Verlag), page 241 ff described, determined. Here, a 15 mm wide test strip from the paper or cardboard to be tested is cut to test the expansion or shrinkage behavior of papers or cardboard boxes with water. The test strip is conditioned in a climate of 23 ° C and 50% relative humidity prior to measuring wet stretch. The strip is clamped in the test device, with an additional weight being applied depending on the basis weight of the sample. The additional weights to be used can be found in Table 1. After the test strip has been clamped, the water container filled with water at 23 ° C (± 2 ° C) is pulled up and screwed down so that the strip is completely submerged in water. After one minute, the water reservoir is removed and after a further 3 minutes (a total of 4 minutes after wetting the test strip with water) the strain is read in millimeters. The elongation then results from the measured strain (in millimeters) divided by the clamped length of the test strip (eg 200 mm) multiplied by 100. <b> Table 1 </ b> Basis weight [g / m ² ] Additional weight [g] to - 125 25 126 - 150 30 151 - 175 35 176 - 200 40 201 - 225 45 226-250 50

The wet stretch parallel to the machine direction is determined by pointing the longitudinal side of the test sample in the machine direction. Accordingly, the machine-direction wet stretch is measured by having the longitudinal side of the sample to be measured transverse to the machine direction. When taking samples, make sure that the long side of the sample to be measured points exactly in the machine direction or exactly crosswise to the machine direction, otherwise the corresponding wet expansions in the transverse direction or longitudinal direction will be averaged according to the angular deviation of the sampling. It is therefore important to ensure that sampling does not take place diagonally to the machine direction. Negative wet stretch means that the test strip has shrunk in the measuring direction during the measurement.

In a further preferred embodiment, the base paper contracts when measuring the wet elongation, so that a negative wet stretch is achieved. This negative wet stretch parallel to the machine direction is preferably in the range of 0% to -1.0%, more preferably -0.1% to -1.0%, and most preferably in the range of -0.25% to -1, 0%. In particular, the wet stretch is preferably in the range of -0.5% to -1.0%.

The wet elongation of the base paper as measured in the cross-machine direction is preferably not greater than 2.5%, more preferably not greater than 2.0%, in a further preferred embodiment not greater than 1.5%, and most preferably not greater than one %. In a further preferred embodiment the wet elongation measured transversely to the machine direction is not greater than 0.8%, more preferably not greater than 0.3% and in a preferred embodiment not greater than 0%.

The coating applied in step b) has no significant influence on the wet elongation of the base paper. Thus, after step c), the coated paper preferably has essentially the same wet elongation as the base paper used for its production. In particular, in this preferred embodiment, the wet strains specified for the base paper can be transferred to the coated paper after step c).

In a preferred embodiment, the wet stretch of the coated paper after step c), measured parallel to the machine direction, is 0%. In a further preferred embodiment, the coated paper contracts when measuring the wet elongation, so that a negative wet elongation is achieved. This negative wet stretch parallel to the machine direction is preferably in the range of 0% to -1.0%, more preferably -0.1% to -1.0%, and most preferably in the range of -0.25% to -1, 0%. In particular, the wet stretch is preferably in the range of -0.5% to -1.0%.

The wet stretch of the coated base paper measured after step c), transverse to the machine direction, is preferably not greater than 2.5%, more preferably not greater than 2.0%, in a further preferred embodiment not greater than 1.5% and most preferably not greater than 1%. In a further preferred embodiment, the wet elongation measured transversely to the machine direction is not greater than 0.8%, more preferably not greater than 0.3% and in a preferred embodiment not greater than 0%.

In a preferred embodiment, the base paper gem. ISO 287 an absolute humidity of not less than 2.5%. More preferably, the base paper in step a) has an absolute humidity of not less than 3.0%, more preferably not less than 3.5%, and most preferably less than 4.0%.

The weight per unit area of the base paper in step a), measured according to EN ISO 536, can be between 20 and 150 g / m ² . Preferably, the basis weight is between 20 and 100 g / m ² , more preferably between 30 and 90 g / m ^2, and most preferably between 40 and 80 g / m ² .

Preferably, in step b) after application of the coating composition, the coated base paper is treated with a high gloss press to obtain a cast-coated paper, wherein the coated base paper gem before entering the high-gloss press an absolute humidity. ISO 287 of greater than 1.5%.

In step b) of the process, preferably 18 to 30 g / m ² (oven dry) of the aqueous coating composition are applied to the base paper. More preferably, between 20 and 25 g / m ² (oven-dry) of the aqueous coating composition in step b) are applied.

The coating preferably contains one or more pigments. Examples of suitable pigments are kaolin, clay, aluminum hydroxide, white luster, barium sulfate, calcium carbonate, talc, calcined kaolin and titanium dioxide, which pigments can be used individually or in mixtures. An organic pigment, such as e.g. a plastic pigment may also be included in the coating. At least 50% by weight of the pigments used preferably have a particle size of less than 2 μm.

The coating preferably contains a binder which is conventional in the field of the present invention. The binder may be a synthetic or natural binder. Suitable binders are e.g. a styrene-butadiene latex, methyl methacrylate-butadiene latex, styrene-vinyl acetate latex, vinyl acetate-acrylate latex, styrene-acrylate-acrylonitrile latex. However, it is also possible to use casein, soybean protein and / or polyvinyl alcohol as a binder.

Common additives may be present in the coating, such as thickeners, surfactants, optical brighteners and dyes.

The solids content of the aqueous coating composition before application to the paper web in step b) is preferably 5 to 68% by weight, more preferably 10 to 65% by weight, and most preferably 15 to 65% by weight.

The glossy press in step b) of the method may preferably have a backside moistening unit. With this Rückseitenbefeuchtungsaggregat can then the back of the coated base paper with a preparation containing water, are treated. The structure of this backside moistening unit may correspond to what is known to a person skilled in the art. In particular, the Rückseitenbefeuchtungsaggregat may be a water press, in which over 2 rollers, the water-containing preparation is applied to the back of the coated base paper. The backside moistening unit is located in the glossy press in front of the cylinder with the mirror-finished surface. The coated base paper is thus moistened on the backside before it is brought into contact with the mirror-finished surface of the cast-coated cylinder. By the backside moistening unit tensions in the base paper are solved, so that the labeling behavior of the finished cast-coated paper is further improved. In particular, in this preferred embodiment, the label in wet labeling nestles even better around the bottles to be labeled.

The preferred casting method is not limited in itself. In particular, the casting method can be the direct method, rewet method (Rewet method) or the gel method. Preference is given to the Rewet process, in which the coating composition is first applied to the base paper and then dried. Subsequently, the coating is moistened again when entering the high-gloss cylinder, so that after leaving the glossy press, the mirror-smooth surface of the cast-coated cylinder was transferred to the paper.

In a preferred embodiment, in step b) the absolute moisture content of the coated base paper prior to entry into the high-gloss press is 2% to 7%. If, in a preferred embodiment, the so-called "rewet process" (Rewet process) is used, is under entry into the high gloss press the time understood before the already coated and dried paper is moistened again. If the glossy press has a backside wetting unit, the absolute humidity of the coated base paper before entering the backside wetting unit is within the specified range.

In a preferred embodiment, the absolute moisture content of the coated base paper prior to entry into the high gloss press is 2% to 6%, more preferably 2.5% to 4%, and most preferably 2.5% to 3.5%.

In step c) of the method described here, the coated paper is conditioned. Here, conditioning is understood as the setting of a predetermined equilibrium moisture content of the coated paper. The predetermined equilibrium wetness of the coated paper is preferably 50% relative humidity. The conditioning can be carried out with any aggregate known to those skilled in the art, in particular with a chamber having a preselected relative humidity. The paper web is then passed through such a chamber until the paper web has the desired equilibrium moisture content. Here, the preselected in the chamber climate of the desired equilibrium moisture content of the paper is adjusted. In a preferred embodiment, the cast-coated paper is conditioned in an atmosphere having a relative humidity of at least 90%.

Preferably, the conditioning is carried out so that the coated paper after conditioning to an equilibrium moisture content of 50% relative humidity (standard climate) a deviation from the flat, measured parallel to the machine direction, of less than 10 mm in the direction of the coated side (elongation at break) and transverse to the machine direction of less than 10 mm in the direction of the coated side (swelling strain).

The flatness is preferably determined by the cross-cut method. Here, a 20 x 20 cm square piece is cut out of the paper web. It must be ensured that the direction of travel is indicated on the test paper and that the edges of the test piece are arranged parallel or transversely to the direction of travel are. A cross-shaped cut of about 18 cm in length is then made diagonally to the corners of the square within the square. The flatness is then checked at the triangular tips of the cuts made. It is determined from the distance of the tips of the support of the test paper, so that the yield strain in millimeters, the distance of the upper and lower tip of the bearing surface of the paper. The swelling strain is accordingly the distance of the tips of the left and right truncated triangle from the point of support of the paper.

In this context, it is also referred to in terms of the swelling strain of the Moisture plant, since the occurring swell can be adjusted within certain limits by a moistening of the paper. Accordingly, the elongation at yield is referred to as a mechanical flatness, as it is caused by e.g. a crusher blade can be influenced. Here, the paper web is deformed under train so that sets the desired yield strain.

The elongation at break is preferably less than 8 mm in the direction of the coated side, more preferably less than 5 mm in the direction of the coated side, and most preferably less than 3 mm in the direction of the coated side. In another preferred embodiment, the yield stretch is 0 mm, which means that the paper does not have stretch elongation.

In another preferred embodiment, the swelling strain is less than 8 mm to the coated side, more preferably less than 5 mm in the direction of the painted side, and most preferably less than 3 mm in the direction of the painted side. In a particularly preferred embodiment, the swelling strain is 0 mm, which means that the paper has no swelling and rests flat on a base.

After being conditioned in step c), the coated paper preferably has an absolute moisture content. ISO 287 from 2% to 10%, more preferably from 2% to 8%, and most preferably from 2% to 7%.

In a preferred embodiment, after step b) and before step c), a metal layer can be applied to the coated side of the coated paper. This metal layer can preferably be applied by vapor deposition in a vacuum. The metal layer preferably contains aluminum. More preferably, the metal layer is an aluminum layer.

In a preferred embodiment, prior to applying the metal layer to the coated side of the coated paper, the coated side is painted. In this case, it is possible that all coatings which are familiar to the person skilled in the art can be used in order to further smooth the surface of the cast-coated paper. This coating can be applied with any application unit known to those skilled in the art. Preferably, the coating is applied by a flexographic printing process, wherein the ink may be solvent-based or water-based.

In a further preferred embodiment, a coating is applied to the metal layer after application of the metal layer. As a coating, any paint can be used, which is familiar to the expert. In particular, the coating can be applied with any application unit known to the person skilled in the art, wherein the coating is preferably applied by a flexographic printing process. As printing ink both solvent-based inks and water-based inks can be used.

In a preferred embodiment, the coated paper according to the application of the metal layer has an absolute humidity gem. ISO 287 from 0.5% to 10%. In a further preferred embodiment, the coated paper has an absolute humidity of from 0.5% to 8%, more preferably from 1% to 7%, more preferably from 1.5% to 6% and most preferably from 2% before applying the metal layer. until 5 %.

Another object of the present invention is a coated paper containing a base paper and a coating which is applied to the base paper, wherein the proportion of long fiber pulp in the base paper at least 25% by weight, the base paper has a water absorption capacity according to ISO 535 at a Test time of 10 s (Cobb ₁₀ ) of 5 to 20 g / m ² , and the base paper has a wet stretch (after fennel) measured parallel to the machine direction of not greater than 0% and transverse to the machine direction of not greater than 3%, and the coating has a coating weight of 10 g / m ² to 40 g / m ² (oven-dry).

The coated paper is preferably a cast-coated paper.

The coated paper has a flatness parallel to the machine direction of less than 10 mm in the direction of the coated side (elongation at break) and transversely to the machine direction of less than 10 mm in the direction of the coated side (swelling elongation), measured by the cross-cut method (as described above).

In a preferred embodiment, the coated paper is characterized by a flatness behavior in a cycle of conditioning at different relative humidities. For this purpose, the paper, which preferably has a size of 10 × 7 cm (rectangular) is conditioned at different relative humidities. When producing such a test paper, it must be ensured that the edges of the rectangle are aligned exactly parallel to the machine direction or transverse direction of the paper web. The longer side of the cut-out rectangle is preferably oriented parallel to the machine direction, so that the machine direction (longer side of the rectangle) is not confused with the transverse direction. Swelling Elongation is the distance of the edges from a flat surface of the rectangular test paper measured at the edges aligned parallel to the machine direction. Accordingly, stretch elongation is the removal of the edges from a flat backing which are oriented transversely to the machine direction. Since the present invention is preferably a one-side coated paper, the swelling elongation as well as the stretch elongation may point to either the coated or uncoated side of the paper.

When carrying out the cycle, it must be ensured that the paper is preferably conditioned to the equilibrium moisture content for the specified moisture content.

1. a) bei einer relativen Feuchte von 50% das Papier eine Quelldehnung zwischen 5 mm zur unbeschichteten Seite des Papiers und 5 mm zur beschichteten Seite des Papiers aufweist,
2. b) das Papier nach anschließender Konditionierung auf eine relative Feuchte von 80% eine Quelldehnung zur beschichteten Seite des Papiers von 0 bis 30 mm aufweist,
3. c) das Papier nach anschließender Konditionierung auf eine relative Feuchte von 45% eine Quelldehnung zur unbeschichteten Seite des Papiers von 0 bis 10 mm aufweist,
4. d) das Papier nach anschließender Konditionierung auf eine relative Feuchte von 80% eine Quelldehnung zur beschichteten Seite des Papiers von 0 bis 30 mm aufweist, und
5. e) das Papier nach anschließender Konditionierung auf eine relative Feuchte von 45% eine Quelldehnung zur unbeschichteten Seite des Papiers von 0 bis 10 mm aufweist.

The paper according to the invention shows a flatness behavior in which

1. a) at a relative humidity of 50%, the paper has an expansion between 5 mm to the uncoated side of the paper and 5 mm to the coated side of the paper,
2. b) the paper after subsequent conditioning to a relative humidity of 80% has a swell to the coated side of the paper from 0 to 30 mm,
3. c) after conditioning to a relative humidity of 45%, the paper has a swell to the uncoated side of the paper of 0 to 10 mm,
4. d) the paper after subsequent conditioning to a relative humidity of 80% has a swelling elongation to the coated side of the paper from 0 to 30 mm, and
5. e) the paper after subsequent conditioning to a relative humidity of 45% has a swell to uncoated side of the paper from 0 to 10 mm.

In addition, the coated paper preferably has a so-called "work capacity". For the purposes of this invention, the working capacity is the mean of the difference in the swelling expansions of step b) and c) and the difference in the swelling expansions of steps d) and e), the mean value preferably being 2 mm to 40 mm.

If, for example, in step b) a swell to the coated side of the paper of 28 mm is measured, in step c) a swell of 8 mm to the uncoated side, in step d) again a swelling to the coated side of the paper of 27 mm and in step e) a swelling elongation of 9 mm to the uncoated side of the paper is measured, so is the working capacity in mm equals (((28 mm - (-8 mm)) + (27 mm - (-9 mm))) / 2. Thus, the cast-coated paper in this example would have a working capacity of 36 mm.

Preferably, the coated paper of the present invention has no elongation at break when passing the flatness cycle described above. Rather, the paper will preferably always show a swell to the coated or uncoated side of the paper with different conditioning.

Surprisingly, the cast coated paper of the present invention has improved labeling performance over prior art papers. In particular, in the case of wet labeling, the paper of the present invention lays around the bottle when it is applied to the bottle to be labeled, so that a kind of wrapping of the bottle through the label takes place. This ensures that the label does not slip due to subsequent brushing. In addition, the labels adhere more firmly to the bottles due to this wrapping behavior, so that the labels in the automatic labeling machine are prevented from falling off. Therefore, the paper of the present invention enhances the reliability of the labeling process. The downtime of the labeling is reduced because the number of cleaning cycles, which would otherwise be necessary to clean the labeling of fallen labels, reduced.

In addition, in the label of the present invention, after application to e.g. Do not bottle corners and edges. As already stated, the coated paper of the present invention lays around the bottle to be labeled. This also prevents the formation of wrinkles on the label. Even in the event that wrinkles form on the bottle when the label is applied, these wrinkles are smoothed again by the wrapping of the label. The label is thus flat on e.g. a bottle on.

Another advantage is the so-called "neck labels" available. "Neck labels" are labels applied to the bottle neck of a bottle. Because the bottleneck is generally a very large deviation from the cylindrical basic shape of the bottle, it is particularly time consuming to attach a precisely fitting label at this point. Surprisingly, the coated paper of the present invention exhibits an improved labeling behavior even at this geometrically very demanding location of a bottle. The coated paper of the present invention conforms exactly to the shape z. B. a bottleneck. Thus, improved machine running occurs during labeling and the applied label does not wrinkle.

As a further advantage of the present invention, in wet-labeling using the coated paper of the present invention, when the glued-on label is applied to a bottle, it is preferable for the label to be stretched to stretch-stretched toward the uncoated, ie glued side of the label. As a result, the wrap of the e.g. Bottle promoted by the label. Without wishing to be bound by theory, it is believed that this effect is also due to the wet stretch (after fennel) of the coated paper of the present invention.

On the coated paper of the present invention may also be applied a metal layer on the coating of the coated paper. As already stated, further layers may be present below the metal layer and / or above the metal layer, which are preferably coatings. The metal layer preferably contains aluminum, which is more preferably vapor-deposited.

Examples: Inventive Example 1:

One-side coated paper is made as follows:

In the paper machine, a fiber mixture with the following composition is processed (Table 2): Table 2: Fiber composition % By weight long fiber 50 short fiber 50 filler 12 excipients 1.5

The base paper thus produced has a basis weight of 50 g / m ² (atro) and an absolute humidity of 3%.
The wet stretch after fennel is parallel to the machine direction - 0, 1%, transverse to the machine direction 2.4%.

The base paper is coated on one side with a pigmented coating composition and subsequently conditioned in a conditioner. Table 3 Coating compound according to order 23 g / m ² (oven-dry) Rückseitenbefeuchtung with water Intake moisture high gloss press 8th% Relative humidity in the conditioner 90% Temperature in the conditioner 45 ° C

The thus prepared coated paper (finished paper) has an absolute humidity of 6%.

The finished paper has a water absorption capacity of the uncoated side according to ISO 535 at a test time of _{10 s} (Cobb ₁₀ ) of 12 g / m ² .
The finished paper has a flatness, measured parallel and cross machine direction from 0 mm to the coated side, and the wet stretch after fennel measured parallel to the machine direction is - 0.1% and transverse to the machine direction 2.4%.

If the flatness behavior of this finished paper is determined under different relative humidities, the following behavior is shown (Table 4). Table 4: Flatness cycle 50% rel. Moist output system 0 mm 80% rel. Humidity step 1 25 mm to the painted side 45% rel. Humidity step 2 0 mm 80% rel. Humidity step 3 27 mm to the painted side 45% rel. Damp step 4 0 mm Working capacity (calculated) 26 mm

This coated paper shows very good behavior during the labeling process (gluing of the label, removal of glue scale). Only when transferring from the gripper fingers of the labeling on the container "jumps" the label of a swelling strain in a yield strain to the back and "clasped" thus the container. Labels that show the behavior described above can be easily labeled on different containers, without this wrinkling, protruding corners o.ä. Mistakes comes. In addition, favored by the above behavior, up to 10% of the usual amount of glue can be saved.

Inventive Example 2:

An aluminum-coated finished paper is produced as follows:

In the paper machine, a fiber mixture with the following composition is processed (Table 5): Table 5: Fiber composition % By weight long fiber 50 short fiber 50 filler 12 excipients 1.5

The produced base paper has a surface weight of 51 g / m ² (atro) and an absolute humidity of 3%.
The wet stretch after fennel parallel to the machine direction is -0.12% and cross-machine direction 2.4%.

The base paper is coated on one side with a pigment-containing coating composition under the following conditions (Table 6). Table 6 coating 26 g / m ² (oven-dry) Rückseitenbefeuchtung with water Intake moisture high gloss press 4% conditioning out temperature out

The coated paper produced in this way has an absolute humidity of 2%.

In a Aluminiumbedampfungsanlage is applied under high vacuum, a thin layer of aluminum on the coated side of the aforementioned coated paper.
Subsequently, the aluminum-coated paper is conditioned with a separate conditioner.
The coated, coated paper (finished paper) produced in this way has an absolute moisture content of 6%.
The water absorption capacity of the uncoated side according to ISO 535 at a test time of _{10 s} (Cobb ₁₀ ) is 11 g / m ² .
In addition, the manufactured finished paper has a flatness, measured parallel and transversely to the machine direction of 0 mm.
The finished paper thus prepared has a wet elongation to fennel measured parallel to the machine direction is -0.12% and transverse to the machine direction 2.4%.

If the flatness behavior of this finished paper is determined under different relative humidities, the following behavior is shown (Table 7). Table 7: Flatness cycle 50% rel. Moist output system 0 mm 80% rel. Humidity step 1 23 mm to the painted side 45% rel. Humidity step 2 0 mm 80% rel. Humidity step 3 25 mm to the painted side 45% rel. Damp step 4 0 mm Working capacity (calculated) 24 mm

This finished paper shows a very good behavior during the labeling process (gluing the label, removal of glue scale). Only when transferring from the gripper fingers of the labeling on the container "jumps" the label of a swelling strain in a yield strain to the back and "clasped" thus the container. Labels that show the behavior described above can be easily labeled on different containers, without this wrinkling, protruding corners o.ä. Mistakes comes. In addition, caused by the above behavior, up to 10% of the usual amount of glue can be saved.

Comparative Example 3

This example is a one-side coated, aluminum-coated label paper with a basis weight of 80g / m ² .

The competition material has an absolute humidity of 5.5% and a water absorption capacity according to ISO 535 with a test time of _{10 s} (Cobb ₁₀ ) of 8 g / m ² .
The flatness, measured parallel and transverse to the machine direction, is 0 mm to the coated side.
The wet elongation after fennel measured parallel to the machine direction is 0.25% and transverse to the machine direction 2.5%.

From this material, the flatness behavior was analyzed according to the procedure described in the application (Table 8). Table 8: Flatness cycle 50% rel. Moist output system 0 mm 80% rel. Humidity step 1 20 mm to the painted side 45% rel. Humidity step 2 0 mm 80% rel. Humidity step 3 24 mm to the painted side 45% rel. Damp step 4 4 mm to the painted side Working capacity (calculated) 20 mm

This finished paper (competition material) shows a normal behavior during the labeling process (gluing the label, removal of glue pallet).
When transferring from the gripper fingers to the container, however, the label does not "jump" from a swelling strain into a stretch stretch to the back. This label must also be pressed against the surface of the container with the brushes or pressure rollers present in the labeling station. Through tensions Label paper or label positioning errors often cause errors such as protruding corners, wrinkles, mispositioning and the like. In addition, it is due to the higher amount of glue required to contamination of the containers or the labeling, which requires shorter cleaning cycles of the labeling.

Claims (26)

A process for producing a coated paper comprising the steps of: a) providing a base paper, wherein the proportion of long fiber pulp in the base paper at least 25% by weight, the base paper has a water absorption capacity according to ISO 535 at a test time of 10 s (Cobb ₁₀ ) of 5 to 20 g / m ² , and the base paper a Wet stretch (after fennel) measured parallel to the machine direction of not greater than 0% and transverse to the machine direction of not greater than 3%, b) applying 10 to 40 g / m ² (oven dry) of an aqueous coating composition on at least one side of the base paper to obtain a coated base paper, and c) conditioning the coated paper obtained in step b). The method of claim 1, wherein the coated paper is a cast-coated paper. The method of claim 1 or 2, wherein the base paper in step a) an absolute humidity acc. ISO 287 of less than 4%. The method according to at least one of claims 1 to 3, characterized in that the base paper in step a) has a basis weight measured according to EN ISO 536 of 20 to 150 g / m ² . The method according to at least one of claims 1 to 4, characterized in that the base paper in step a) has a wet stretch (after fennel) parallel to the machine direction of 0% to -1.0% and transverse to the machine direction of less than 2.5%. having. The method according to at least one of claims 1 to 5, characterized in that in step b) after application of the coating composition, the coated base paper is treated with a high gloss press to obtain a cast coated paper, wherein the coated base paper before entering the high gloss press an absolute humidity gem. ISO 287 of greater than 1.5%. The method according to any one of claims 1 to 6, characterized in that in step b) 18 to 30 g / m ² (oven-dry) of the aqueous coating composition are applied to the base paper. The method according to at least one of claims 1 to 7, characterized in that the high-gloss press in step b) has a backside moistening unit and the back side of the coated base paper is treated with the backside moistening unit with a preparation containing water. The method according to at least one of claims 1 to 8, characterized in that in step b) the absolute humidity of the coated base paper prior to entry into the high gloss press is 2% to 7%. The method according to any one of claims 1 to 9, characterized in that in step c) the cast-coated paper is conditioned in an atmosphere having a relative humidity of at least 90%. The method according to any one of claims 1 to 10, characterized in that in step c) the coated paper after conditioning a flatness measured parallel to the machine direction of less than 10 mm in the direction of the coated side (elongation at break) and transverse to the machine direction of less than 10 mm in the direction of the painted side (swelling strain). The method according to at least one of claims 1 to 11, characterized in that in step c) the coated paper according to conditioning an absolute humidity acc. ISO 287 from 2% to 10%. The method according to at least one of claims 1 to 12, characterized in that after step b) and before step c) a metal layer is applied to the coated side of the cast-coated paper. The method according to claim 13, characterized in that the metal layer is applied by vapor deposition in a vacuum. The method according to claim 13 or 14, characterized in that the metal layer contains aluminum. The method according to at least one of claims 13 to 15, characterized in that the coated paper before application of the metal layer according to an absolute humidity. ISO 287 from 0.5% to 10% Coated paper obtainable according to at least one of claims 1 to 16. Coated paper containing a base paper and a coating which is applied to the base paper, wherein the proportion of long fiber pulp in the base paper at least 25% by weight, the base paper has a water absorption capacity according to ISO 535 at a test time of 10 s (Cobb ₁₀ ) of 5 to 20 g / m ² and the base paper has a wet stretch (after fennel) measured parallel to the machine direction of not greater than 0% and transverse to the machine direction of not greater than 3%, and the coating has a coating weight of 10 g / m ² to 40 g / m ² (oven-dry). The coated article of claim 18, wherein the coated paper is a cast-coated paper. The coated paper according to claim 18 or 19, wherein the coated paper has a deviation from the flatness parallel to the machine direction of less than 10 mm in the direction of the coated side (elongation at break) and transverse to the machine direction of less than 10 mm in the direction of the coated side (swelling elongation ) having. The coated paper according to at least one of claims 18 to 20, characterized in that a) at a relative humidity of 50%, the paper has an expansion between 5 mm to the uncoated side of the paper and 5 mm to the coated side, b) the paper after subsequent conditioning to a relative humidity of 80% has a swell to the coated side of the paper from 0 to 30 mm, c) after conditioning to a relative humidity of 45%, the paper has a swell to the uncoated side of the paper of 0 to 10 mm, d) the paper after subsequent conditioning to a relative humidity of 80% has a swelling elongation to the coated side of the paper from 0 to 30 mm, and e) the paper after subsequent conditioning to a relative humidity of 45% has a swell to uncoated side of the paper from 0 to 10 mm The coated paper according to claim 21, characterized in that the mean value of the difference of the swelling expansions of step b) and c) and the difference in the swelling strains of step d) and e) is 2 mm to 40 mm. The coated paper of claim 21 or 22, characterized in that the paper in steps b) to e) has no stretch to the coated or uncoated side. The coated paper according to any one of claims 21 to 23, characterized in that a metal layer is applied to the coating of the coated paper. The coated paper according to claim 24, characterized in that the metal layer contains aluminum. Use of the coated paper according to at least one of claims 17 to 25 for the labeling of goods.