EP3283686B1 - Cigarette paper with high short-fibre fraction - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to a wrapping paper for smoking articles. In particular, it relates to a wrapping paper for smoking articles that can be produced by using a high proportion of short fiber pulp with less energy and cost than conventional papers for smoking articles, without the essential technical properties deteriorating. Furthermore, the invention relates to a smoking article, which comprises the wrapping paper according to the invention.

BACKGROUND AND PRIOR ART

A typical cigarette consists of a tobacco rod, which is wrapped in a cigarette paper. In many cases, cigarettes are also equipped with a filter, typically made of cellulose acetate, which is wrapped in a filter wrapping paper and is additionally wrapped on the outside by a mouthpiece covering paper which is somewhat longer than the filter and thus connects the filter to the tobacco rod wrapped in the cigarette paper , Such cigarettes are usually consumed by burning the tobacco and inhaling the smoke produced by the smoker.

Alternative smoking articles do not burn the tobacco but only warm it, releasing an aerosol that the smoker inhales. It is believed that the aerosol of such smoking articles contains fewer harmful substances than the smoke of conventional cigarettes. Instead of tobacco, other aerosol-producing materials can also be used. Depending on the construction of these smoking articles, a wrapping paper which wraps the tobacco or aerosol-producing material or other parts of the smoking article may also be required for such smoking articles.

There are many technical requirements for wrapping papers for smoking articles, in particular with regard to air permeability, diffusion capacity, but also with regard to optical requirements such as whiteness, color and opacity. The selection of possible raw materials for such wrapping papers is often subject to legal restrictions, which is why the manufacturer of such wrapping papers is restricted in the design of the wrapping paper.

In addition to the technical requirements for the wrapping paper, commercial considerations can also play a role in the design of the wrapping paper. The production of paper in general and of wrapping paper for smoking articles in particular requires a lot of energy and also partly expensive raw materials.

Wrapping paper wrapping papers typically contain cellulose fibers. These pulp fibers are ground in grinding units during the production of the wrapping paper. This means that mechanical stress on the cellulose fibers exposes the individual fibers or fibrils of the cellulose fiber bundles. This means that a larger surface area and more options are available for the individual pulp fibers to be connected to one another by hydrogen bonds during paper production. This gives the paper its tensile strength, but also affects the air permeability. In general, more intensive pulp fiber grinding leads to higher tensile strength of the paper but less air permeability. This grinding process is very energy-intensive and therefore also expensive.

In the case of cellulose fibers, a distinction is made between long-fiber cellulose, which is typically obtained from coniferous trees, such as spruce, pine or larch, and short-fiber cellulose, which is typically obtained from deciduous trees, such as beech, birch, eucalyptus, poplar or aspen. In general, long fiber pulp is more expensive than short fiber pulp and has to be milled with more energy than short fiber pulp. Short fiber pulp is generally used unground in wrapping papers for smoking articles.

Another important type of cellulose fibers for wrapping papers for smoking articles are cellulose fibers that are not obtained from trees, such as flax, hemp, sisal, abacá, jute or cotton. Because of their length and tensile strength, these cellulose fibers can replace the long fiber cellulose in terms of their technical effect in the wrapping paper, but are again considerably more expensive than long fiber cellulose.

Another important type of cellulose fibers for wrapping papers for smoking articles are cellulose fibers which are obtained from esparto grass. These cellulose fibers give a wrapping paper more volume and lower density and can be used in their technical effect in the wrapping paper as an alternative to short fiber pulp.

According to the teaching accepted in the prior art, wrapping papers for smoking articles must contain long-fiber pulp or cellulose fibers with a comparable technical effect so that the wrapping paper has sufficient tensile strength for the manual or mechanical production of smoking articles. According to the prior art, the proportion of long fiber pulp in the total pulp in wrapping papers for smoking articles is at least 20% and typically between 25% and 70%. This makes the manufacture of wrapping papers for smoking articles expensive.

Due to the high and generally increasing taxes and duties with which smoking articles are charged, there is an interest in the industry in manufacturing the components of smoking articles cheaper so that smoking articles can continue to be offered to consumers at a price that is acceptable to them.

Therefore, there is also an interest in the industry in producing the wrapping paper for smoking articles at a low cost for energy and raw materials.

A wrapping paper according to the preamble of claim 1 is from US 4,624,268 A known. More wrapping papers are out US 5,143,099 A . WO 2008/103792 A2 and U.S. 4,984,589 A. known.

SUMMARY OF THE INVENTION

The present invention has for its object to provide a wrapping paper for smoking articles, which can be produced in comparison to conventional wrapping papers with less cost and energy, without the technical properties, in particular the tensile strength of the wrapping paper, deteriorate significantly.

This object is achieved by a wrapping paper according to claim 1 and by a smoking article according to claim 14. Advantageous further developments are specified in the dependent claims.

The wrapping paper according to the invention has a basis weight of at least 10 g / m ² and at most 70 g / m ² and comprises a mixture of cellulose fibers. The inventors have surprisingly found that the object can be achieved by a wrapping paper for smoking articles, the mixture of cellulose fibers of which is at least 90% formed by short fiber cellulose fibers with respect to the mass of the cellulose fibers in the cellulose mixture, or at least 95% based on the number of cellulose fibers by short fiber cellulose fibers is, wherein at least 10% of the short fiber pulp fibers based on the mass, or number of pulp fibers of the pulp fiber mixture are ground.

Contrary to the teaching accepted in the prior art, according to the long fiber pulp or cellulose similar technical effect to achieve the required tensile strength of the wrapping paper is absolutely necessary, the inventors have surprisingly found that a wrapping paper with properties suitable for practical applications can also be produced with a very high proportion of short fiber pulp if at least part of this short fiber pulp is ground. Apparently, the grinding of part of the short fiber pulp causes a sufficient increase in the tensile strength of the wrapping paper, so that the use of the expensive long fiber pulp can be largely or completely dispensed with. By dispensing with long-fiber pulp, the costs for the pulp itself, but also for the energy expenditure in the milling, which is customary for long-fiber pulp, can be significantly reduced.

In fact, it turns out that the wrapping paper according to the invention can have sufficient tensile strength without the need for an additional coating to increase the tensile strength. However, the cigarette paper may or may be coated in certain sections, for example in order to lower the diffusion capacity and thus impart self-extinguishing properties to a cigarette made from the wrapping paper. However, the base paper, ie the wrapping paper without such coatings, has an air permeability of at least 30 cm ³ / (cm ² · min · kPa). But even if the wrapping paper according to the invention is coated in certain areas, it has an air permeability of at least 30 cm ³ / (cm ²⁾ on more than 50% of its area, preferably at least 55% of its area, and particularly preferably at least 60% of its area Min kPa).

The wrapping paper also contains at least one fire salt. This ensures that the wrapping paper according to the invention, when used for a conventional tobacco cigarette, gives the ash a good appearance and in this respect has no disadvantages compared to conventional cigarette papers, even if the wrapping paper, as in some preferred embodiments, is comparatively small Proportion of fillers. In particular, it can be avoided that the embers cone migrates appreciably under the wrapping paper, which would produce an undesirable visual impression.

As mentioned above, the wrapping paper according to the invention can achieve sufficient tensile strengths even if it is not coated with an additional coating to increase the tensile strength. In a preferred embodiment, the wrapping paper is therefore free of an additional coating. However, in other embodiments it may have coated areas, for example those which serve for self-extinguishing, but these preferably make up less than 50%, particularly preferably less than 45% and in particular less than 40% of the total area of the wrapping paper.

The cellulose mixture in the wrapping paper is preferably designed so that its fibers have an average length of at most 2.0 mm and at least 0.1 mm.

In a particularly preferred embodiment, the average length of the fibers in the finished wrapping paper is at most 1.5 mm and very particularly preferably at most 1.2 mm and in particular at most 1.0 mm.

The proportion of the short fiber pulp must be at least 90% based on the mass of the fibers in the cellulose mixture in the wrapping paper according to the invention as described above or at least 95% based on the number of fibers in the cellulose mixture. However, as far as the requirements for the tensile strength of the wrapping paper permit, the proportion of short fiber pulp can be chosen to be as high as possible, so that it is preferably 95% based on the mass and particularly preferably 100% based on the mass or number, so that in the Essentially the entire pulp mixture is formed by short fiber pulp. The percentages relating to the mass or number of short-fiber cellulose fibers are to be interpreted taking into account typical tolerances in the purity of the cellulose and in the production of the wrapping paper.

For the wrapping paper according to the invention, as described above, at least 10% of the short fiber cellulose fibers, based on the mass or number of fibers in the cellulose mixture, must be ground. Since the grinding is associated with energy expenditure, the proportion of the ground short fiber pulp will be kept as low as possible. To increase the tensile strength, however, it can be advantageous to choose a proportion greater than 10%. In a preferred embodiment, the proportion of the ground short fiber pulp fibers, based on the mass of the total pulp fibers, is at least 20%, particularly preferably at least 30% and / or at most 100%, particularly preferably at most 80%, in particular at most 70% or based on the Number of total cellulose fibers, at least 20% lens, particularly preferably at least 35% and / or at most 100%, particularly preferably at most 85%, in particular at most 75%.

The effect of grinding on the pulp can be determined by determining the degree of grinding according to ISO 5267-1: 1999 and is given in Schopper-Riegler (° SR). In a preferred embodiment, the degree of grinding of the ground short fiber pulp according to ISO 5267-1: 1999 is at least 20 ° SR, particularly preferably at least 30 ° SR and / or at most 85 ° SR, particularly preferably at most 80 ° SR.

The person skilled in the art can optimize the energy expenditure in order to achieve a sufficient tensile strength of the wrapping paper, for example by using short but intensively ground short fiber pulp or large but weakly ground short fiber pulp.

For the production of the wrapping paper on conventional paper machines, the degree of grinding of the pulp mixture, ie the mixture of ground short fiber pulp, unground short fiber pulp, if present, and, optionally, other pulps is of particular importance. The degree of grinding describes the speed at which an aqueous fiber suspension can be dewatered and therefore influences not only the tensile strength of the wrapping paper but also the maximum speed of the paper machine in the production of the wrapping paper and thus indirectly the cost of production. A low value for the degree of grinding means rapid drainage of the fiber suspension and vice versa. In general, therefore, one will try to choose the freeness of the pulp fiber mixture as low as possible.

In a preferred embodiment, the degree of grinding of the pulp mixture in the finished wrapping paper is at least 20 ° SR and particularly preferably at least 30 ° SR and very particularly preferably at least 40 ° SR and / or at most 70 ° SR and particularly preferably at most 60 ° SR.

The short fiber pulp for the wrapping paper according to the invention can preferably be obtained from deciduous trees, particularly preferably from birch, beech, eucalyptus, poplar or aspen and very particularly preferably from birch or eucalyptus. Mixtures of short fiber pulps from different origins can be used. The use of short fiber pulp from esparto grass, in whole or in part, is possible according to the invention, but is not preferred because of the low availability and the higher price.

The wrapping paper according to the invention can contain, in addition to short fiber pulp, other pulps, but the amount, as described above, is at most 10% and preferably at most 5% based on the mass of the pulp fibers in the pulp mixture or based on the number of pulp fibers in the pulp mixture at most 5%, preferably at most May be 2%.

Said other pulps can preferably be formed from pulps obtained from conifers, particularly preferably from spruce, pine or larch. Likewise preferred are cellulose fibers which have been obtained, for example, from flax, hemp, sisal, abaca, jute or cotton. These fibers can be used unground, but preferably ground, for example to give the wrapping material a particularly high strength.

It is also conceivable to use fibers from regenerated cellulose, such as, for example, lyocell fibers, such as Tencel®, viscose fibers or modal fibers. The use of such fibers can be useful for technical reasons, but is not preferred for the present invention because of the price of these fibers.

As described above, the wrapping paper for smoking articles according to the invention has a basis weight of at least 10 g / m ² and at most 70 g / m ² . In general, the specialist will seek a balance between tensile strength, opacity and whiteness as well as cost and taste influence when choosing the basis weight. As the basis weight increases, tensile strength, opacity and whiteness generally increase, but the influence of taste on the smoking article and the material costs also increase due to the higher mass of wrapping paper. The basis weight of the wrapping paper according to the invention is therefore preferably at least 20 g / m ² , particularly preferably at least 25 g / m ² and / or at most 60 g / m ² , particularly preferably at most 40 g / m ² . The basis weight of the wrapping paper can be determined in accordance with ISO 536: 2012.

The wrapping paper according to the invention can contain fillers. Preferred fillers are oxides, hydroxides, carbonates and silicates, particularly preferably oxides, hydroxides, carbonates and silicates of metals, very particularly preferably calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate and aluminum hydroxide. A particularly preferred filler is precipitated calcium carbonate because of its high purity.

Since fillers are generally cheaper than pulp and can additionally increase the opacity and whiteness of the wrapping paper, the person skilled in the art will try to choose the highest possible filler content in the wrapping paper. However, the fillers also reduce the tensile strength of the wrapping paper and therefore the person skilled in the art should not choose the filler content as high as desired, especially if the proportion of ground short fiber pulp is low.

In a preferred embodiment, the wrapping paper according to the invention contains at most 45% by weight of filler, particularly preferably at most 40% by weight and very particularly preferably at most 35% by weight, in each case based on the weight of the wrapping paper, as used on the smoking article becomes.

In general, the wrapping paper according to the invention can be produced without or with very little filler, but the filler content is preferably at least 10% by weight, particularly preferably at least 15% by weight and very particularly preferably at least 20% by weight.

Particularly with regard to the use on smoking articles in which the tobacco is burned, the wrapping paper according to the invention also contains at least one incineration salt, which can increase or reduce the smoldering speed of the smoking article or improve the appearance of the ashes of the burned tobacco together with the burned wrapping paper.

In a preferred embodiment, the wrapping paper therefore comprises one or more fire salts selected from the group consisting of citrates, malates, tartrates, acetates, nitrates, succinates, fumarates, gluconates, gycolates, lactates, oxalates, salicylates, α-hydroxycaprylates, phosphates and Hydrogen carbonates, preferably selected from the group consisting of trisodium citrate and tripotassium citrate.

The content of fire salts in the wrapping paper according to the invention is preferably at least 0.5% by weight, particularly preferably at least 0.7% by weight, very particularly preferably at least 1.0% by weight and / or at most 7.0% by weight. %, particularly preferably at most 5.0% by weight and very particularly preferably 3.0% by weight. The fire salt content can be used, for example, for acetates according to CORESTA Recommended Method No. 33 (January 1993) and based on anhydrous acetic acid. For citrates, the measurement according to CORESTA Recommended Method No. 34 (January 1993), the content being given in% by weight based on the monohydrate of the citric acid. For phosphates, the CORESTA Recommended Method No. 45 (January 1998) can be determined and given in relation to the phosphate ions (PO ₄ ^3- ).

Particularly important sizes for the further processing of wrapping papers for smoking articles are the tensile strength and elongation at break of the wrapping paper, in particular the tensile strength and elongation at break in the machine direction. They can be determined according to ISO 1924-2: 2008. A paper strip with a width of 15 mm is stretched to break at a constant speed and the maximum force that occurs is measured. This force is the tensile strength and is given in N / 15 mm. The elongation at break is the elongation at break and is expressed as a percentage of the length of the unloaded paper sample.

In general, machine processing of the wrapping paper into smoking articles requires a tensile strength in the machine direction of at least about 9 N / 15 mm and an elongation at break in the machine direction of at least about 1.0%. However, lower values are also acceptable for the manual or partial manual production of smoking articles from wrapping paper. This also applies to the mechanical production of smoking articles at a correspondingly lower than the maximum possible production speed.

A preferred wrapping paper according to the invention for smoking articles therefore has a tensile strength in the machine direction according to ISO 1924-2: 2008 of at least 10 N / 15 mm and particularly preferably at least 12 N / 15 mm. An upper limit for the tensile strength in the machine direction is preferably 30 N / 15 mm, particularly preferably 25 N / 15 mm and very particularly preferably 20 N / 15 mm.

A preferred wrapping paper according to the invention for smoking articles has an elongation at break in the machine direction according to ISO 1924-2: 2008 of at least 0.9% and particularly preferably at least 1.0%. The elongation at break in the machine direction according to ISO 1924-2: 2008 is preferably at most 5.0%, particularly preferably at most 3.0% and very particularly preferably at most 2.5%.

Another important property of wrapping paper for smoking articles is its air permeability. It can be determined according to ISO 2965: 2009 and is given in cm ³ / (cm ² · min · kPa). Air permeability can affect the contents of the smoke or aerosol of a smoking article by allowing air to enter the smoking article through the cigarette paper, thereby replacing part of the smoke or aerosol in the smoking article with air. In particular, air permeability can affect the levels of tar, nicotine and carbon monoxide in the smoke of a cigarette.

The air permeability of known, naturally porous wrapping papers for smoking articles is typically between 10 cm ³ / (cm ² · min · kPa) and 300 cm ³ / (cm ² · min · kPa), the air permeability being able to be increased further, for example by perforation up to 10000 cm ³ / (cm ² · min · kPa). Wrapping papers with an air permeability of less than 10 cm ³ / (cm ² · min · kPa) are also known. Such wrapping papers are mainly used for manually manufactured smoking articles (roll-your-own).

In many countries, legal regulations set upper limits for the tar, nicotine and carbon monoxide content in the smoke of a cigarette. In general, there is a trend towards wrapping papers with higher air permeability in order to replace or dilute the smoke in the smoking article with more air flowing in from outside, and thus to reduce the content of tar, nicotine and carbon monoxide in the smoke.

The use of a high proportion of short fiber pulp in the wrapping paper according to the invention makes it possible to produce wrapping papers with a particularly high air permeability.

As mentioned at the beginning, the air permeability of the wrapping paper according to the invention in untreated areas is at least 30 cm ³ / (cm ² .min.kPa), but preferably at least 50 cm ³ / (cm ² .min. KPa) and particularly preferably at least 70 cm ³ / ( cm ² · min · kPa). If the wrapping material according to the invention has a low weight per unit area and the short fiber pulp is only ground slightly, particularly high air permeability can be achieved. However, the air permeability is preferably at most 10000 cm ³ / (cm ² .min. KPa), particularly preferably at most 5000 cm ³ / (cm ² .min. KPa) and very particularly preferably at most 500 cm ³ / (cm ² .min. KPa) ) to allow a tensile strength that is advantageous for further processing and is difficult to combine with extremely air-permeable papers.

Another important property of wrapping paper for smoking articles is its diffusion capacity. The diffusion capacity determines the transport of gases through the wrapping paper due to a concentration difference. Especially in the phases of the consumption of a smoking article, in which there is no pressure difference between the two sides of the wrapping paper, gases such as carbon monoxide can diffuse through the wrapping paper. This can influence, for example, the carbon monoxide content in the smoke or aerosol of a smoking article.

The diffusion capacity of a wrapping paper for carbon dioxide in nitrogen can be determined according to CORESTA Recommended Method No. 77 (April 2014) can be measured and is given in cm / s. For naturally porous wrapping papers, there is a certain connection between the air permeability and the diffusion capacity, since both sizes are determined by the porous structure of the wrapping paper. For this reason, air permeability and diffusion capacity cannot be chosen completely independently of one another.

Since a high diffusion capacity can particularly reduce the content of carbon monoxide in the smoke or aerosol of a smoking article and carbon monoxide is toxic and nothing contributes to the taste or smell of the smoking article, there is generally a desire to select the diffusion capacity as high as possible, but considering the close relationship mentioned above with the air permeability must take into account.

In a preferred embodiment of the wrapping paper for smoking articles according to the invention, the diffusion capacity in untreated areas is therefore at least 0.1 cm / s, particularly preferably at least 1.0 cm / s and / or at most 5.0 cm / s, particularly preferably at most 4.0 cm / s.

The wrapping paper can have patterns that result from compression of the wrapping paper. These can be the so-called verge lines, for example. In the area of these lines, the paper is compressed and therefore more transparent. Vergellinien can be applied in the machine direction of the wrapping paper, in the transverse direction of the wrapping paper or in any other direction. In addition to a line pattern, any other pattern can also be applied.

The wrapping paper can contain watermarks in any form.

The wrapping paper can comprise further substances which are known from the prior art for the production of wrapping papers for smoking articles. This can include, for example, inorganic pigments, for example iron oxides, or organic dyes that give the coating material a specific color. It can also include flavorings that affect the smell or taste of the smoke or aerosol of the smoking article. This can be both the smoke or aerosol inhaled by the consumer of the smoking article and the smoke or aerosol released by the smoking article without being inhaled by the consumer of the smoking article, in particular the sidestream smoke of a cigarette. Such flavorings can also be associated with physical carriers, such as by encapsulation, for example in cyclodextrin or polymers. The flavorings can also be chemically bound, for example in ethylvanillin glucoside.

The wrapping paper can also have additional areas of reduced diffusion capacity, which can serve the self-extinguishing of the smoking article, for example to meet legal requirements regarding self-extinguishing. Such areas of reduced diffusion capacity can be produced according to the prior art by applying film-forming substances, but also by other methods such as embossing.

The wrapping paper can be perforated to increase air permeability and in particular to increase air permeability without significantly affecting the diffusion capacity. The methods known from the prior art, such as mechanical perforation, electrostatic perforation, laser perforation and plasma perforation, can be used.

The wrapping paper can be printed, for example in order to give it an attractive external appearance or to achieve other special effects, for example temperature-dependent color changes. Printing processes such as gravure printing, Flexographic printing, offset printing or screen printing but also spraying are used. There are no restrictions on the printed pattern.

Since, as shown in the following exemplary embodiments, the technical properties relevant for further processing, in particular the tensile strength and elongation at break, do not differ from conventional wrapping papers for smoking articles, any additional process steps known from the current or future state of the art can also be carried out using the Wrapping paper according to the invention are carried out, provided that they can also be carried out with conventional wrapping papers for smoking articles.

The wrapping paper according to the invention can be produced per se according to the paper production processes known from the prior art. In particular, the pulp mixture can first be suspended in water in one or more containers and then all or part of the pulp mixture can be ground in grinding units. After grinding, further substances, for example fillers, pigments, dyes or processing aids, for example retention aids, can be added. The wrapping paper can then be produced on a conventional paper machine, for example a Fourdrinier paper machine. An aqueous suspension of cellulose fibers and optionally fillers and other substances flows from a headbox onto the sieve of the paper machine and can be dewatered there by gravity or vacuum, a wrapping paper web being formed from the suspension. The wrapping paper web then passes through, for example, a press section in which the wrapping paper web is further dewatered by mechanical pressure between rollers and a press felt. Finally, the wrapping paper web can pass through a drying section, in which remaining water is removed by contact with heated drying cylinders, hot air, infrared radiation or microwaves, so that the wrapping paper web has its equilibrium moisture content of about 4-8% by weight, based on the weight of the finished wrapping paper. At the end of the paper machine, the wrapping paper web can be rolled up.

A film press or size press can be located in the drying section, in which substances for influencing the surface of the wrapping paper are applied to one or both sides of the wrapping paper. These substances can be, for example, pigments, such as iron oxides, dyes, binders, such as starch or carboxymethyl cellulose, or fillers, such as calcium carbonate.

The further processing steps usually include cutting a wide roll of the wrapping paper into narrower bobbins, the width of which corresponds approximately to the circumference of the smoking article to be produced therefrom, or an integral multiple thereof.

A smoking article according to the invention comprises a strand of tobacco or another material that forms smoke or an aerosol when burned or heated. According to the invention, this strand is covered by the wrapping material according to the invention in order to form a smoking article therefrom. Optionally, the smoking article can also contain a filter, which is connected to the wrapped strand, for example, by a tip paper.

The smoking article is preferably a cigarette and particularly preferably a filter cigarette.

The smoking article can be produced manually, partly mechanically or completely mechanically according to the methods known from the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following exemplary embodiments are intended to demonstrate the effect according to the invention. Birch pulp and eucalyptus pulp were selected as short fiber pulps for the wrapping paper according to the invention. Precipitated calcium carbonate was used as the filler. Table 1 cellulose Lime filler freeness birch Eucalyptus unground Ground birch mixture ground unground No. % % % % ° SR ° SR 1 40 60 0 0 30 22 2 40 60 0 0 40 25 3 20 80 0 0 40 21 4 80 0 20 36.5 36 33 5 80 0 20 39.3 52 46 6 80 0 20 43.0 71 60 7 80 0 20 0 36 33 8th 80 0 20 0 52 46 9 80 0 20 0 71 60 10 80 0 20 30.5 79 57 11 80 0 20 0 79 57

Table 1 shows 11 different fiber / filler compositions from which exemplary wrapping papers were made. The fiber / filler composition is characterized by the proportions of ground birch pulp ("Birch ground" column), unground birch pulp ("Birch unground" column), unground eucalyptus pulp ("Eucalyptus unground" column) and filler ("Filler column") Percentages for the ground and unground birch and eucalyptus pulp refer to the mass of the entire pulp mixture, whereas the filler percentage refers to the mass of the finished wrapping paper. In the columns titled "freeness" the freeness is according to ISO 5267 -1: 1999 in Schopper-Riegler (° SR), where the column "Birch ground" contains the values for the ground birch pulp alone and the column "Mixture" contains the values for the entire cellulose mixture without filler.

As can be seen from Table 1, compositions of 1-3 ground and unmilled birch pulp were used for compositions, while compositions 4-11 of milled birch pulp and unground eucalyptus pulp were used in compositions. Compositions 4-6 and 10 additionally contained precipitated calcium carbonate ("lime") as a filler. The ground birch pulp was ground to grades between 30 ° SR and 79 ° SR. This shows an essential advantage of the invention, since only about half the grinding energy of conventional long-fiber pulp was always used for grinding the birch pulp in relation to the mass. This leads to a substantial saving in grinding energy.

The compositions in Table 1 represent extreme points for the design of a wrapping paper with regard to the degree of grinding, the filler content and the proportions of ground and unground short fiber pulp, so that the person skilled in the art will choose values between these extreme points when designing a wrapping paper for smoking articles according to the invention.

The fiber length distribution of the ground birch pulp was measured several times using a fiber tester code 912, type 987666, from Lorentzen & Wettre in accordance with the specifications of the measuring device manufacturer, and an average fiber length between 0.8 and 1.0 mm was obtained.

The ground birch pulp was mixed together with the unground birch pulp or the unground eucalyptus pulp according to the mixing ratios according to Table 1 in an aqueous suspension. The filler was in the appropriate amount the suspension was added, and leaves were formed from the suspension on a laboratory sheet former and dried. A total of 14 wrapping papers were produced, the data of which are given in Table 2.

Table 2 shows 14 exemplary embodiments A-N according to the invention (column "Example"), one of the fiber / filler suspensions from Table 1 being used for each exemplary embodiment. The assignment is made via the column "Composition No." from Table 2. The numbers entered correspond to the numbers from the column "No." from Table 1.

After conditioning the leaves according to ISO 187 at 23 ° C and 50% relative humidity, various measurements were carried out on the leaves, the results of which are given in Table 2. Table 2 Composition No. grammage tensile strenght elongation Air permeability diffusing capacity example g / m ² N / 15 mm % cm ³ / (cm ² · min.kPa) cm / s A 1 25 10 7200 3.7 B 2 25 12 4900 3.2 C 3 25 9 7500 3.8 D 1 60 148 0.6 e 2 60 90 0.5 F 3 60 175 0.7 G 4 35 5 0.9 580 3.6 H 5 34 6 1.1 308 3.0 I 6 37 8th 1.4 147 2.4 J 7 23 20 2.5 1240 2.3 K 8th 23 21 2.5 272 1.1 L 9 23 24 2.4 75 0.4 M 10 37 10 1.5 203 2.0 N 11 25 25 2.8 142 0.6

The basis weight was measured according to ISO 536: 2012, the results are given in the column "basis weight". The tensile strength and elongation at break were determined in accordance with ISO 1924-2: 2008 measured and are given in the columns "tensile strength" and "elongation at break". The air permeability was measured according to ISO 2965: 2009 and is given in the "Air permeability" column. Finally, the diffusion capacity according to CORESTA Recommended Method No. 77 (April 2014) and the values are given in the "Diffusion capacity" column.

The examples AC show that a tensile strength of at least 9 N / 15 mm can be achieved with a basis weight of 25 g / m ² , so that the wrapping paper can be machine-processed into a smoking article without any problems. The air permeabilities of Examples AC are very high at 4900 cm ³ / (cm ² .min.kPa) to 7500 cm ³ / (cm ² .min on ground birch pulp or by selecting another short fiber pulp, the air permeability can be reduced if necessary. The diffusion capacities of the wrapping papers from examples AC are also high, which can reduce the content of carbon monoxide in the smoke of a smoking article made therefrom.

Examples DF use the same fiber / filler suspensions 1-3 as examples AC, but have a considerably higher basis weight of 60 g / m ² . As a result, the air permeability with values of 90 cm ³ / (cm ² .min. KPa) to 175 cm ³ / (cm ² .min. KPa) is significantly lower than in the examples AC. The diffusion capacities of the wrapping papers of Examples DF are 0.5 cm / s to 0.7 cm / s in the usual range for wrapping papers for smoking articles. The tensile strength was not measured because the composition of the wrapping papers of Examples DF is the same as for Examples AC and because of the higher basis weight, a significant increase in tensile strength is to be expected, so that the values are in any case well above 12 N / 15 mm, the highest Value of the examples AC, will be.

The wrapping papers of examples GN contain ground birch pulp and unground eucalyptus pulp and in examples G, H, I and M also filler. The basis weights are in a range from 23 g / m ² to 37 g / m ^2, which is customary for conventional wrapping papers for smoking articles. Examples G and H are just within an acceptable range for the tensile strength of 5 N / 15 mm and 6 N / 15 mm, respectively. These examples show that the birch pulp is ground slightly and the filler content is high at 36.5% (Example G) and 39.3% (Example H) to reduce the tensile strength of the wrapping paper. In Example I, on the other hand, the filler content is even higher at 43%, but the birch pulp is also ground to a higher freeness of 71 ° SR. This achieves a tensile strength of 8 N / 15mm, which is for a machine Further processing of the wrapping paper may be sufficient, but in any case is sufficient for wrapping paper for manually manufactured smoking articles.

The elongation at break was also measured for examples G-N. Values of 0.9% to 2.8% are shown, which is sufficient for further processing of the wrapping papers.

The air permeability of the wrapping papers from Examples GN is in the range from 75 cm ³ / (cm ² .min. KPa) to 1240 cm ³ / (cm ² .min. KPa), and thus covers the usual range for wrapping papers of smoking articles well , The same applies to the diffusion capacities of the examples GN, which range between 0.4 cm / s and 3.6 cm / s.

The wrapping papers described can be used to make a smoking article, for example by using the wrapping papers to wrap a tobacco rod or other material that releases an aerosol when heated or burned. Because all the essential properties of the wrapping papers of Examples A-N are in a range typical for wrapping papers for smoking articles, the manufacturing processes for producing the smoking article do not differ from those as are known from the prior art. For this reason, an illustration of methods for producing corresponding smoking articles is omitted in the present description.

Overall, it can be seen from the exemplary embodiments A-N that, contrary to expectations, the predominant or exclusive use of short fiber cellulose makes it possible to produce wrapping papers for smoking articles with the properties typical of such wrapping papers. In contrast to the prior art, this is possible with considerable savings in energy and raw material costs.

Claims (15)

1. Wrapping paper for smoking articles with a basis weight of at least 10 g/m² and at most 70 g/m², comprising a mixture of pulp fibers, wherein more than 50% of the surface area of the wrapping paper, preferably at least 55% of its surface area and particularly preferably at least 60% of its surface area has an air permeability of at least 30 cm³/(cm²·min·kPa), and wherein the wrapping paper contains at least one burn additive, characterized in that the mixture of pulp fibers is formed by at least 90% of short-fiber pulp fibers with respect to the mass of the pulp fibers in the pulp mixture, or by at least 95% short-fiber pulp fibers with respect to the number of pulp fibers, and wherein at least 10% of the short-fiber pulp fibers, with respect to the mass or number of the pulp fibers of the pulp mixture, are refined.
2. Wrapping paper according to claim 1, wherein the wrapping paper is free from an additional coating, or has coated areas which make up less than 50%, preferably less than 45% and particularly preferably less than 40% of the total area of the wrapping paper.
3. Wrapping paper according to claim 1 or 2, wherein the fibers of the pulp mixture have a mean length of at least 0.1 mm and at most 2.0 mm, preferably at most 1.5 mm, particularly preferably at most 1.2 mm and in particular at most 1.0 mm.
4. Wrapping paper according to one of the preceding claims, wherein the fraction of the short-fiber pulp with respect to the mass of the pulp fibers in the pulp mixture is at least 95% and with respect to the mass or the number is preferably 100%.
5. Wrapping paper according to one of the preceding claims, wherein the fraction of refined short-fiber pulp fibers,

   - with respect to the mass of the entire pulp fibers, is at least 20%, preferably at least 30% and/or at most 100%, preferably at most 80%, in particular at most 70%, or

   - with respect to the total number of pulp fibers, is at least 20%, particularly preferably at least 35% and/or at most 100%, particularly preferably at most 85%, in particular at most 75%.
6. Wrapping paper according to one of the preceding claims, wherein the degree of refining of the refined short-fiber pulp in accordance with ISO 5267-1:1999 is at least 20 °SR, preferably at least 30 °SR and/or at most 85 °SR, preferably at most 80 °SR.
7. Wrapping paper according to one of the preceding claims, wherein the degree of refining of the pulp mixture in the finished wrapping paper is at least 20 °SR, preferably at least 30 °SR and particularly preferably at least 40 °SR and/or at most 70 °SR, preferably at most 60 °SR.
8. Wrapping paper according to one of the preceding claims, wherein the short-fiber pulp is at least primarily sourced from deciduous trees, preferably from one or more of the following trees: birch, beech, eucalyptus, poplar or aspen.
9. Wrapping paper according to one of the preceding claims, with a basis weight of at least 20 g/m², preferably at least 25 g/m² and/or at most 60 g/m², preferably at most 40 g/m².
10. Wrapping paper according to one of the preceding claims, which further contains one or more filler materials, wherein at least a fraction of the one or more filler materials is selected from a group which consists of oxides, hydroxides, carbonates and silicates, in particular oxides, hydroxides, carbonates and silicates of metals, particularly preferably from calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate and aluminum hydroxide,
    and/or wherein the wrapping paper has a filler content of at most 45% by weight, preferably at most 40% by weight and particularly preferably at most 35% by weight and/or of at least 10% by weight, preferably at least 15% by weight and particularly preferably at least 20% by weight, each referred to the weight of the wrapping paper.
11. Wrapping paper according to one of the preceding claims, which further contains at least a burn additive selected from the group consisting of citrates, malates, tartrates, acetates, succinates, fumarates, gluconates, glycolates, lactates, oxalates, salicylates, α-hydroxy caprylates, phosphates and hydrogen carbonates, preferably selected from the group consisting of trisodium citrate and tripotassium citrate, wherein
    the burn additive content preferably is at least 0.5% by weight, preferably at least 0.7% by weight and particularly preferably at least 1.0% by weight and/or at most 7.0% by weight, preferably at most 5.0% by weight and particularly preferably at most 3.0% by weight, and/or
    with a tensile strength in the machine direction in accordance with ISO 1924-2:2008 of at least 10 N/15 mm, preferably at least 12 N/15 mm and/or at most 30 N/15 mm, preferably at most 25 N/15 mm and in particular at most 20 N/15 mm.
12. Wrapping paper according to one of the preceding claims, with an elongation at break in the machine direction in accordance with ISO 1924-2:2008 of at least 0.9%, preferably at least 1.0% and/or at most 5.0%, preferably at most 3.0% and particularly preferably at most 2.5%, and/or
    with an air permeability in untreated areas that is at least 50 cm³/(cm²·min·kPa), preferably at least 70 cm³/(cm²·min·kPa) and/or at most 10000 cm³/(cm²·min·kPa), preferably at most 5000 cm³/(cm²·min·kPa) and particularly preferably at most 500 cm³/(cm²·min·kPa).
13. Wrapping paper according to one of the preceding claims, with a diffusion capacity in untreated areas that is at least 0.1 cm/s, preferably at least 1.0 cm/s and/or at most 5.0 cm/s, preferably at most 4.0 cm/s, and/or
    which further has areas of reduced diffusion capacity which serve to self-extinguish a smoking article manufactured therefrom, in particular areas onto which a film-forming substance is applied, or areas where the diffusion capacity has been reduced by embossing, and/or
    which further is artificially perforated at least in sections.
14. Smoking article comprising a rod of tobacco or a different material, which forms smoke or an aerosol upon combustion or heating, wherein this rod is wrapped with a wrapping paper according to one of the preceding claims.
15. Smoking article according to claim 14, which comprises a filter which in particular is connected with the wrapped rod via a tipping paper.