EP2761087A1

EP2761087A1 - Cigarette paper with homogeneous visual impression

Info

Publication number: EP2761087A1
Application number: EP13742164.0A
Authority: EP
Inventors: Roland Zitturi; Irene Rohregger; Maria GLEINSER
Original assignee: Delfortgroup AG
Current assignee: Delfortgroup AG
Priority date: 2012-09-05
Filing date: 2013-07-29
Publication date: 2014-08-06
Anticipated expiration: 2033-07-29
Also published as: PH12015500426B1; CN104603360A; DE102012108255B4; BR112015004659B1; WO2014037073A8; WO2014037073A1; PH12015500426A1; US9427021B2; MY171915A; BR112015004659A2; EP2761087B1; DE102012108255A1; ES2536095T3; CN104603360B; PL2761087T3; US20150173416A1

Abstract

The invention relates to a cigarette paper onto which a composition is applied in the form of a pattern which has a Tamura coarseness which is at most 0.22 mm, preferably at most 0.20 mm. According to ISO 2470-1 the absolute difference in whiteness between an area of the cigarette paper over the whole of which the composition is applied and an area of the cigarette paper onto which the composition is not applied is at least 25% in the dry state, preferably at least 35% and particularly preferably at least 40% and at most 60%, preferably at most 55 %. Furthermore, the opacity according to ISO 2471 of an area of the cigarette paper over the whole of which this composition is applied is higher, when the composition is in the dry state, than the opacity of an area onto which this composition is not applied.

Description

Cigarette paper with a homogeneous visual impression

FIELD OF THE INVENTION

The present invention relates to a cigarette paper and an associated manufacturing method. In particular, it relates to a cigarette paper in which the visibility of inhomogeneities in the whiteness and the opacity of the paper is reduced to the human eye, so that the tobacco rod of a cigarette made from this paper gives a homogeneous visual impression.

BACKGROUND AND PRIOR ART

A cigarette usually consists of a cylindrical tobacco rod wrapped in a cigarette paper and optionally further includes a filter plug enveloped by a filter wrap paper which is connected to the tobacco rod by a mouthpiece wrapping paper.

It is well known that the smoker judges a cigarette not only according to their taste when smoking but also by the optical qualities. In particular, an optically homogeneous tobacco rod is regarded as a mark of a high-quality cigarette brand, a so-called "premium brand." This can generally mean that the tobacco rod wrapped in cigarette paper is visually homogeneous, opaque and white when viewed from the outside, so that the tobacco particles of the tobacco rod are not penetrated by the tobacco rod Paper can be seen as a variation of whiteness.

To produce such an optically homogeneous cigarette paper, the paper manufacturer from the prior art, various tools are available. For example, it is known that by increasing the basis weight of the paper, by increasing the content of fillers, by selecting the filler or other means, the paper's homogeneity can be improved. Although all these measures can increase the opacity according to ISO 2471 or whiteness according to ISO 2470-1 of the cigarette paper, but eliminate the inhomogeneities only insufficient. It is in the nature of Papermaking process that the visual impression of a white paper in the backlight, for example, from that of a white plastic film by inhomogeneities in the opacity significantly different. This inhomogeneous overall visual impression, which a paper sheet transmits in transmitted light, is called "formation" or "cloudiness". The skilled artisan usually judges the formation of the paper subjectively, speaking of a good formation when the paper sheet is optically homogeneous.

In some cases, such inhomogeneities are even desirable to a lesser extent to give the paper a natural look and make it distinguishable, for example, from plastic films. In other applications, such as on the cigarette, but put on a high optical homogeneity worth. It is, for example, especially in Asia, undesirable that the smoker can recognize the tobacco in some places by the cigarette paper in the form of brightness variations. This effect is all the more the thinner and lighter the cigarette paper, and the less filler it contains.

An important visual feature of the cigarette paper is its opacity, ie the opacity of the cigarette paper. It is determined to ISO 2471 and expressed as a percentage from 0% (clear) to 100% (completely opaque).

Common cigarette papers are light gray to white, although black cigarette papers and colored cigarette papers are also available on the market. The whiteness of the cigarette paper is therefore also an important visual feature and is determined according to ISO 2470-1. It is also quantified as a percentage compared to a white standard with a value of 0% (black) to 100% (white). Fluorescence also allows values over 100% to be achieved, which, however, are only just over 100% and are usually only achieved in conjunction with optical brighteners.

In addition to the optical properties of a cigarette paper play especially those technical properties of the cigarette paper a role that can influence the ingredients of the smoke of a cigarette made from it. These ingredients are determined, for example, by a method described in ISO 4387 and include, but are not limited to, the nicotine-free dry condensate ("tar"), the nicotine content, and the carbon monoxide content in the smoke of a cigarette. An important such technical property of the cigarette paper is its air permeability. The air permeability is determined according to ISO 2965 and indicates which air volume per unit time, per unit area and per pressure difference flows through the cigarette paper and therefore has the unit cm ³ / (min cm ² ka). It is often referred to as CORESTA unit (CU, CORESTA unit) (1 CU = 1 cm ³ / (min cm ² kPa)). Among other things, the air permeability determines how much the smoke is diluted during a draft by the air flowing through the cigarette paper into the tobacco rod. Another important technical property is the diffusion capacity. It denotes the gas volume passing through the paper per unit of time, per unit area and per concentration difference and therefore has the unit cm ³ / (s cm ² ) = cm / s. The diffusion capacity of a cigarette paper for C0 ₂ can be determined, for example, with the C0 ₂ Diffusivity Meter from Sodim. Among other things, the diffusion capacity determines the gas exchange by the cigarette paper between the tobacco rod and the environment by diffusion while the cigarette is glowing.

It is also known from the prior art to treat the cigarette paper in some areas with fire retardant materials and thus to give the cigarette self-extinguishing properties. A test for determining the self-extinguishing properties is described in ISO 12863. These or very similar tests are also subject to legal regulations in the US, Canada, Australia and the European Union. In a common embodiment, the treated portions are designed as 5 mm to 7 mm wide bands which are applied to the inside of the cigarette paper and extend on the cigarette in the circumferential direction. The bands hinder the access of oxygen to the glow cone of the smoldering cigarette and thus cause self-extinction. The imprint of these bands is usually done on the less suitable for the print itself screen side of the cigarette paper instead of the top so that the printed side on the cigarette faces the tobacco rod and the bands are less visible from the outside. Nevertheless, on closer examination, the bands on the cigarette are often still visible to the naked eye. Together with the unavoidable optical inhomogeneities of the paper, such bands of fire-retardant materials also impair the optical properties. It has proven difficult to eliminate the aforementioned inhomogeneities in the visual appearance. The increase in the basis weight of the cigarette paper are limited by the acceptance of the smoker of a cigarette made therefrom, since the smoker wants to smoke primarily tobacco and not paper. Overall, there is therefore more of a desire to reduce the basis weight of the cigarette paper than to increase. When increasing the filler content, one has also encountered limits, since the tensile strength of the paper is reduced too much and the paper tends to dust during further processing. Likewise, there are restrictions of legal and toxicological nature in the choice of filler. For example, the titanium dioxide particularly useful in increasing the whiteness and opacity in cigarette paper can not be used because of these limitations. The use of optical brighteners, although technically perhaps obvious, is excluded for cigarette paper for legal and toxicological reasons.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a cigarette paper which improves the optical properties of a cigarette made from this cigarette paper and, in particular, makes the optical inhomogeneities of the cigarette paper less noticeable to the human eye, without substantially impairing the technical properties of the cigarette paper.

This object is achieved by a cigarette paper according to claim 1 and an associated manufacturing method according to claim 18. Advantageous developments are specified in the dependent claims.

According to the invention, a composition in the form of a pattern is applied to the cigarette paper, which has a Coaseness Tamura, which is at most 0.22 mm, preferably at most 0.20 mm. The absolute difference in whiteness according to ISO 2470-1 between an area of the cigarette paper to which the composition is applied over the entire surface and an area of the cigarette paper to which the composition is not applied is at least 25%, preferably at least 35% especially preferably at least 40%. However, it should not exceed 60%, preferably 55%. Finally, the opacity according to ISO 2471 of a surface of the cigarette paper to which the composition is applied over the entire surface is higher than that Opacity of an area to which this composition is not applied. The values of whiteness according to ISO 2470-1 and opacity according to ISO 2471 always refer to the composition in the dried state. The inventors have surprisingly found that contrary to expectation, for example, for white cigarette paper, the optical quality can be improved by the application of less white compositions.

More specifically, the inventors have found that patterns that meet certain requirements in terms of shape and color can reduce the perceivability of the inhomogeneities of the paper by the human eye. According to the invention, this pattern is produced by applying a composition to the cigarette paper. By applying such a pattern, the areas in which the composition was applied differ from the untreated areas of the cigarette paper in terms of whiteness and opacity. An improvement in the optical properties of the cigarette paper in the context of this invention is achieved if the above relationships exist between the whiteness, the opacity and the structure size of the pattern applied to the cigarette paper. Simply put, the effect according to the invention is achieved by applying a pattern to the cigarette paper which slightly deviates from the cigarette paper in the white and is so finely structured that the smoker, from the distance from which he usually looks at a cigarette, has the structure of the cigarette Pattern can not perceive in detail. Instead of perceiving this pattern, he sees only a slightly less white surface than with conventional cigarette paper, but - surprisingly - optically much more homogeneous.

For this technical effect it is necessary as already stated that the coarseness according to Tamura is sufficiently small. A lower limit of the Coarseness results essentially for practical considerations, because can print with the preferred printing methods no arbitrarily small structures. Therefore, in the preferred embodiments, it will be at least 0.01 mm, preferably at least 0.05 mm

To simplify the further illustration, the following terms are defined. The printed area is defined as the area of the cigarette paper to which a composition according to the invention has been applied. It does not matter whether the composition was actually applied by a printing process, but only that it was applied by any method. Also, for example, the spraying of the composition should be covered by it.

The treated area is defined as the printed area supplemented by an imaginary border around the printed area with a width of 1.5 mm. More precisely, the treated area is the union of all circular areas with a radius of 1, 5 mm, whose centers lie in the printed area.

The unprinted area is defined as that part of the treated area that does not belong to the printed area. The untreated area is defined as the area of the cigarette paper that does not belong to the treated area.

The visible cigarette paper surface is defined as the area of the cigarette paper that is visible on the cigarette from the outside. Thus, for example, it does not include the area which is overlapped by the tipping paper nor the area of the cigarette paper which is covered in the formation of a glue seam of a cigarette paper tube.

To describe the feature size of a pattern, various parameters can be used that are determined by numerical calculations from a digital image of the pattern. A commonly used parameter that correlates well with human perception is the so-called coarseness according to Tamura, described in H. Tamura, et al .: Texture features corresponding to visual perception. IEEE Transactions on Systems, Man, and Cybernetics, vol. SMC-8, no. 6, 1978, 460-473. Based on this, the algorithm for determining coarseness according to Tamura is described in more detail below.

The input data is a digital image of the print pattern, in which each pixel is assigned a gray level. The gray levels are described in monotonic increasing, for example, by integer values from 0 (black) to 255 (white). The picture is in one Resolution of 0.01 x 0.01 mm per pixel. For repeating patterns with a rectangular repeating unit, the image will show at least one repeating unit, otherwise it will show the visible cigarette paper surface. In the following illustration, it is assumed that the image has an extension of w pixels in the x direction and h pixels in the orthogonal y direction. The x-direction corresponds to the circumferential direction on the cigarette and the y-direction is parallel to the longitudinal axis of the tobacco rod. The Coarseness according to Tamura depends little on the choice of directions and in particular not on a permutation of x-direction and y-direction. Likewise, it does not depend on the concrete numerical values that characterize the gray scale, but only on the relationships to each other within the image.

The position of a pixel is described by integer coordinates x and y with 0 <x <w and 0 <y <h. Each pixel with the coordinates (x, y) is assigned a gray level g (x, y). For values of x or y outside the specified intervals, g (x, y) = g (x modulo w, y modulo h), so the image is considered to be endlessly repeating in each direction.

1. For each pixel (x, y) _{we compute} 101 values G _avg (k ^, y), which are the mean gray value of a square of side length 2 £ + l, where k = 0, 1, 2, ..., 100 , in whose center the pixel (x, y) lies, ie

2. For each pixel (x, y) and for each λ = 0,1, 2, ..., 100, the absolute difference AG _S (k, x, y), s = 1, 2,3,4 , determined in the middle gray value to the four adjacent non-overlapping squares:

AG, (k, x, y) = | G _ovg (k, x, y) - G _avg (k, x - 2k - 1, y) \

AG ₂ (k, x, y) =

AG, (k, x, y) =

AG, (k, x, y) = 3. For each pixel (x, y) and for each k = Q, 1, 2, ... 100, the maximum AG _m3x (k, x, y) of these values is determined:

AG _max (k, x, y) = max AG _S (Je, x, y)

-1, 2.3,4

4. For each pixel (x, y), that k is determined for which the value AG _m3x (k, x, y) assumes its maximum. This value is referred to as K _max (x, y) = k, that is:

«= 0,1, 2 ...., 100

If AG _max (k, x, y) assumes the maximum value for several k, then K _mm (x, y) is the largest k for which the maximum is assumed.

5. The average value of 2 · K _max (x, y) + 1 is determined over the entire image. This mean is the coarseness after Tamura, which is called C _Tamura :

C _Tamura = 1 + Σ Σ (* »y) The coarseness has the unit pixels and can be converted into mm by multiplying it by the pixel size, in this case 0.01 mm per pixel. It is a measure of the average structure size of the digital image. A size of 0.01 mm per pixel is sufficiently small for the characterization of the samples of the present invention, because smaller structures can be produced with the preferred application methods, in particular in the gravure printing method, and are not required for the effect according to the invention.

In the case where the image shows not only a rectangular repeating unit but the visible cigarette paper surface, only those pixels belonging to the treated area are to be used for averaging in step 5 of the above algorithm.

In the invention, the coarseness of the applied Tamura pattern as mentioned above is at most 0.22 mm, preferably at most 0.20 mm. The inventors were able to determine that patterns whose coarseness assumes such low values achieve the desired effect. Investigations by the inventors have shown that this effect with a correspondingly chosen coarseness for a variety of different patterns some of which are shown below. Coarseness accordingly has a significant meaning for the effect according to the invention, ie independent of the specific design of the sample. According to the invention, the whiteness of the printed area should be less than the whiteness of the unprinted area. The absolute difference in whiteness according to ISO 2470-1 between the printed and the unprinted area is at least 25%, preferably at least 35% and particularly preferably at least 40%. At the same time, however, the difference should be at most 60%, preferably at most 55%, in order to avoid clearly discernible differences.

The inventors have found that the effect according to the invention can be achieved over a comparatively large range of whiteness according to ISO 2470-1 and the opacity according to ISO 2471 of the untreated cigarette paper. However, the effect is less pronounced if both the whiteness and the opacity of the untreated cigarette paper are already very high, ie the optical quality of the untreated paper is already very good. Thus, in preferred embodiments, at least one area of the cigarette paper to which the composition is not applied should have an ISO 2470-1 whiteness of less than 95% or an ISO 2471 opacity of less than 90%.

In practice, direct measurement of whiteness according to ISO 2470-1 or ISO 2471 opacity of the printed or unprinted area will often be difficult. For reliable determination of these values, therefore, sufficiently large test areas can be formed at another location of the cigarette paper and used for the measurement, for example sufficiently large surfaces printed over the whole area. The same applies to sufficiently large completely untreated areas, which may optionally be left separately for this purpose on the cigarette paper. In both cases, it can be assumed that these surfaces printed over the entire surface or surfaces which are completely untreated are representative of the whiteness or opacity of the printed or unprinted areas of the actual pattern.

Preferably, the opacity according to ISO 2471 of the cigarette paper without application of the composition is at most 90%, preferably at most 80%. For opacities below By applying the patterns according to the invention, these limits result in a particularly good effect, since in these the optical inhomogeneity due to the translucent tobacco strand is particularly pronounced. At the same time, however, the opacity of the untreated cigarette paper should be at least 50%, because at lower opacities even by application of the inventive pattern a satisfactory appearance can be achieved only with difficulty.

Preferably, the ISO 2471 opacity of an area of the cigarette paper to which the composition is applied over the entire area is at least 80%, preferably at least 85% and particularly preferably at least 90%. The greater the opacity of the printed area, the better the effect according to the invention.

In an advantageous embodiment, the whiteness according to ISO 2470-1 of the cigarette paper without application of the composition is at least 80% and in particular between 80% and 95%. For these values of whiteness, particularly good results can also be achieved.

In an advantageous embodiment, the proportion of the printed area on the treated area according to the above definition is less than 80%, preferably less than 70% and particularly preferably less than 50%. Note that this ratio is an additional property of the pattern, which has independent meaning in addition to coarseness. In many cases it is advantageous, given coarseness, to favor those patterns in which the proportion of the printed area on the treated area is small in order to minimize the effect on the air permeability and the diffusion capacity of the paper.

The proportion of the treated area on the total visible cigarette paper surface of the cigarette paper is preferably at least 20%, preferably at least 50% and particularly preferably at least 70%. In particularly preferred embodiments, however, the treated area will extend over the entire visible cigarette paper surface in order to achieve the desired effect on this.

The composition comprises at least water as a solvent and a dye. Furthermore, the composition should be water-based, which means that it is in any case less than 10% by weight, preferably less than 5% by weight, of organic solvents on the weight of the composition. In this case, the composition may preferably be formed by a solution, a suspension or an emulsion. The term "solvent" is therefore not intended to indicate that the composition is a "solution" in the strict sense. In fact, even a suspension of the dye as a composition is preferred. The consequence of using a water-based composition is that after drying, no or at most very small amounts of organic solvent remain on the printed surface, preferably less than 0.5 mg / m ² , particularly preferably less than 0.1 mg / m ² , in each case based on the printed area.

Preferably, the solvent is alone formed by water. Although the advantage of organic solvents is that after application of the composition by heat usually with less energy expenditure can be removed than water, but remain on the cigarette paper small residual amounts of organic solvent, the aroma of the cigarette, especially directly after opening the Cigarette package, can affect. There are also toxicological concerns about the use of organic solvents in cigarette paper. Therefore, water is the preferred solvent. As the dye, it is possible to use all dyes which are suitable for producing in small quantities the desired white difference between printed and unprinted area. Above all, toxicological and legal aspects have to be considered. The lightfastness and possible bleeding of the dye in the presence of moisture may also be included in the selection. For white cigarette paper, carbon particles of a medicinal coal are a particularly preferred dye, and equally preferred are black, water-soluble food dyes, which usually meet the legal requirements and are easier to disperse than medicinal carbon. An alternative for white cigarette paper are also organic dyes, for example Blue El 32, or inorganic pigment dyes.

With colored cigarette papers there is often less need to use the invention, but in principle it can also be used there. In this case, appropriate dyes are then used in the color on the cigarette paper, such as, for example, inorganic pigment dyes, for example iron oxides (El 72), organic dyes such as Blue El 32, Red El 23 or Red El 24 or mixtures thereof.

In an advantageous development, the composition further comprises at least one binder, in particular one or more binders, which is selected from the group consisting of: cellulose derivatives; Starch and starch derivatives, in particular dextrins and maltodextrins; modified starch, especially oxidized starch, acetylated starch, or cationic starch; phosphated starch; guar; Gum arabic; Agar Agar; Sugar, in particular fructose; Mannoses, maltoses or molasses; Sugar alcohols, especially sorbitol or mannitol; polyvinyl alcohol; polyvinyl acetate; Gelatin; Carboxymethyl starch.

Preferably, at least 0.1% by weight, more preferably at least 0.3% by weight and / or at most 7.0% by weight, preferably at most 5.0% by weight of the composition is formed by the dye.

Furthermore, preferably at most 25.0% by weight of the composition, particularly preferably 1.0% by weight to 20.0% by weight, are formed by the binder. The binder and its amount can be used to adjust the viscosity of the composition required for the application process.

The application amount of the composition is preferably at least 0.1 g / m,

2 2 particularly preferably at least 0.3 g / m. However, it should be at most 2.0 g / m, preferably at most 1.5 g / m ² , in each case based on the mass of dried composition and per square meter of printed area. Such application rates are sufficient in practice to achieve the desired whiteness and opacity in the printed area, but at the same time avoid too much change in the other technical properties, in particular the air permeability and the diffusion capacity of the cigarette paper. Preferably, the basis weight of the cigarette paper is in the untreated state

2 2 2 at least 10 g / m, and / or at most 60 g / m, preferably at most 35 g / m and particularly preferably at most 28 g / m ² . The invention shows particularly good effects in cigarette papers with comparatively low basis weights between 20 g / m ² and 28 g / m ² , in which the opacity in the untreated state is comparatively low and make the inhomogeneities in the opacity particularly noticeable. In an advantageous embodiment, the cigarette paper further contains at least one inorganic, mineral filler, the paper to a mass fraction of at least 10 wt .-%, preferably at least 15 wt .-% and / or at most 45 wt .-%, preferably at most 35 wt .-% and particularly preferably at most 25 wt .-%, each based on the cigarette paper without application of the composition is added. Again, particularly good effects can be achieved with a comparatively low filler content of, for example, 15% by weight to 25% by weight, in which the whiteness and opacity of the untreated cigarette paper are generally comparatively low, so that these cigarette papers become optical inhomogeneities in the tend initially described manner.

In this case, the filler is preferably formed by calcium carbonate (lime) or other carbonates or oxides, in particular magnesium oxide, magnesium hydroxide or aluminum hydroxide or mixtures thereof.

Further, the cigarette paper preferably comprises substances which increase or decrease the simmering speed of the paper, in particular trisodium citrate, tripotassium citrate or mixtures thereof, but the proportion of these substances preferably does not exceed 5% by weight of the paper pulp.

In an advantageous development, the air permeability of the treated area is at least 10 CU, preferably at least 20 CU and / or at most 150 CU, preferably at most 130 CU. Such air permeabilities are also common in conventional cigarette papers. However, an essential advantage of the invention is that such air permeabilities can be achieved even in the treated area, that is, despite order of the composition.

In an advantageous embodiment, the diffusion capacity of the treated area for C0 _{2 is} at least 0.01 cm / s and / or at most 3.5 cm / s, preferably at most 3.0 cm / s. Again, these are conventional diffusion capacities, but they can also be achieved within the scope of the invention in the treated area.

According to a further aspect, the invention relates to a method for producing a cigarette paper according to one of the embodiments described above. In the process a water-based composition for forming said pattern is printed, preferably by gravure printing, offset or flexographic printing, or sprayed. Particularly preferred is the imprint in the gravure printing process, which is particularly well suited in terms of flexibility, speed and quality for the application of the composition in the process of the invention.

The invention further relates to a cigarette comprising a tobacco rod and a cigarette paper according to one of the embodiments described above, which surrounds the tobacco rod. The proportion of the treated area on the visible cigarette paper surface is at least 20%, preferably at least 50% and particularly preferably at least 70%. However, in preferred embodiments, the entire visible cigarette paper surface may be formed by a treated surface.

Additionally or alternatively, the pattern is preferably repeated, and the circumference of the cigarette is an integer multiple of the repetition rate of the pattern in the circumferential direction. This ensures that the pattern also continues to be suitable in the region of the glue seam on which the cigarette paper overlaps itself, as a result of which the effect according to the invention is also achieved in the area of the glue seam of the cigarette paper.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1-6 show different patterns, which at a certain choice of geometric

Sizes a, b and c can realize the effect according to the invention. Fig. 7 shows a table summarizing the characteristic parameters a, b and optionally c, coarseness and coverage of 27 (inventive and noninventive examples) based on six different pattern types according to Figs. 1-6.

DESCRIPTION OF PREFERRED EMBODIMENTS

The inventors have tested the invention with reference to six different patterns shown in Figs. 1-6. In FIGS. 1 to 6, parameters a, b and optionally c, which represent the characteristic dimensions of the respective pattern. Depending on these parameters, the coarseness can be calculated according to Tamura, as explained in the summary of the invention. It is also possible to calculate the "overlap" of the pattern, which is the percentage of printed area on the treated area, and is therefore expressed as a percentage Note that both coarseness and coverage are independent of whiteness ISO 2470-1 of the printed and unprinted area.

Table 1 of FIG. 7 shows the coarseness and the coverage for different parameter values a, b and possibly c for the different patterns of FIGS. 1 to 6. Corresponding cigarette papers were produced in which the whiteness of the cigarette paper conforms to ISO 2470-1 between 80 and 90% and the opacity was between 70 and 80%. The whiteness of the fully printed area was about 40% less than that of the untreated area. The opacity of the printed area measured according to ISO 247-1 was always higher than the opacity of the untreated area.

From the printed papers, cigarettes were made whose visual appearance was compared with that of a cigarette with an identical but untreated cigarette paper. It was found that, at least approximately independently of the actual execution of the pattern, a considerable improvement in the optical homogeneity can be achieved if its coarseness is chosen to be low enough. Good results were obtained for a coarseness that was below 0.22 mm, with the visual impression still improving with an even smaller coarseness of 0.20 mm. This effect stands out in the eye of a skilled person skilled in the paper formation test, but can hardly be documented differently in terms of metrology since it is based on human sensory perception. In fact, the optical homogeneity, if one wanted to quantify them, is in reality not increased, but in some way even artificially reduced by the finely structured pattern. Surprisingly, however, the visual impression that results for the human observer and to which it depends exclusively for the purposes of the invention is that the paper is more homogeneous for a large number of different patterns whose coarseness is less than 0.22 mm. Specifically, it has been shown that the desired effect in the samples of Examples 1, 2, 3, 8, 9, 10, 15, 19, 22, 24 and 27 according to the table of Fig. 7 occurs particularly intense, while the inventive Effect with the patterns of Examples 4, 5, 6, 7, 1 1, 12, 13, 14, 17, 18, 20, 21, 23, 25 and 26 could hardly achieve. The reason for this is that the structures were too large and thus the unwanted inhomogeneities remained visible. The pattern 16 showed at least satisfactory results. Although the results can be expected to be further improved by the choice of a very low coarseness, in the production of samples with a coarseness below about 0.01-0.05 mm, the technological limits of some printing processes are encountered.

Furthermore, it could be confirmed that the inventive samples could be applied without substantially affecting the technical properties of the paper. For example, reference was made to a cigarette paper having a basis weight of 27 g / m ² , a lime content of 28% by weight, a whiteness of 87%, an opacity of 75%, an air permeability of 72 CU and a diffusion capacity of 2.73 cm / s printed in a gravure printing an aqueous printing solution with 1, 5 wt .-% of sodium carboxymethylcellulose Blanose® MCF-7 and 1.40 wt .-% medicinal coal. The print pattern was selected from Table 1 according to Example 27. The pattern corresponds to the pattern of FIG. 1.

The white of the printed area, measured according to ISO 2470-1 on a separate, sufficiently large, fully printed area was 44.6%, ie 42.4% less than that of the untreated area. The opacity of the printed area, measured according to ISO 2471 on the same area as for the whiteness, was 93.5% and was thus 18.5% higher than the opacity of the untreated area. Although a comparison of the visual impression of the printed and unprinted cigarette paper by a person skilled in the paper formation test showed a reduction in the whiteness, a considerable improvement in the optical homogeneity. The measurement of the air permeability according to ISO 2965 with a measuring head with an opening of 10x20 mm, which was completely on the treated area, gave a value of 67.5 CU and thus only a slight decrease of 4.5 CU compared to the untreated area.

The measurement of the diffusion capacity with a Meter from Sodim, after conditioning the paper according to ISO 187 and with a measuring head with an opening of 4x20 mm, which was completely on the treated area, gave a value of 2.60 cm / s and thus only a slight decrease of 0.13 cm / s compared to the untreated area. Thus, the invention can be implemented as far as possible without affecting the essential technical properties of the cigarette paper.

Claims

claims

1. Rolling paper coated with a composition in the form of a sample having a Tamura Coarseness of not more than 0,22 mm, preferably not more than 0,20 mm,

wherein the absolute difference in whiteness according to ISO 2470-1 between an area of the cigarette paper to which the composition is applied over the entire surface and an area of the cigarette paper to which the composition is not applied, in the dried state of the composition, at least 25%, preferably at least 35% and more preferably at least 40%, and at most 60%, preferably at most 55%, and

wherein the opacity according to ISO 2471 an area of the cigarette paper, to which this composition is applied over the entire surface, in the dried state of

Composition is higher than the opacity of an area to which this

Composition is not applied.

2. The cigarette paper according to claim 1, wherein the coarseness according to Tamura of the sample is at least 0.01 mm, preferably at least 0.05 mm.

A cigarette paper according to claim 1 or 2, wherein an area of the cigarette paper to which the composition is not applied has an ISO 2470-1 whiteness of less than 95% or an ISO 2471 opacity of less than 90%.

4. A cigarette paper according to any one of the preceding claims, wherein the opacity according to ISO 2471 of the cigarette paper without application of the composition is at most 90%, preferably at most 80% and / or at least 50%.

5. A cigarette paper according to any one of the preceding claims, wherein the opacity according to ISO 2471 an area of the cigarette paper, to which the composition is applied over the entire surface, in the dried state of the composition at least 80%, preferably at least 85% and particularly preferably at least 90%.

6. A cigarette paper according to any one of the preceding claims, wherein the whiteness according to ISO 2470-1 of the cigarette paper without application of the composition is at least 80%, and in particular between 80% and 95%.

A cigarette paper according to any one of the preceding claims, wherein the proportion of the printed area on the treated area is less than 80%, preferably less than 70%, and most preferably less than 50%, the "printed area" being that area of the cigarette paper will, on which the composition - regardless of the actually used

Application method - was applied, and the "treated area" is defined as the printed area supplemented by an imaginary edge around the printed area with a width of 1, 5 mm.

8. A cigarette paper according to any one of the preceding claims, wherein the proportion of the treated area on the entire visible surface of the cigarette paper is at least 20%, preferably at least 50% and most preferably at least 70%.

9. cigarette paper, according to any one of the preceding claims, wherein the

Composition comprises at least water and a dye, wherein the

Composition preferably by an aqueous solution, suspension or

Emulsion is formed.

10. cigarette paper according to claim 9, wherein the dye at least partially by coal particles, in particular medicinal coal, a black, water-soluble

Food dye, an inorganic pigment, an organic dye, or a mixture of at least two of these dyes is formed.

A cigarette paper according to any one of claims 9 or 10, wherein the composition further contains at least one binder, in particular one or more binders selected from the group consisting of:

Cellulose derivatives; Starch and starch derivatives, in particular dextrins and maltodextrins; modified starch, in particular oxidized starch, acetylated starch or cationic Strength; phosphated starch; guar; Gum arabic; Agar Agar; Sugar, in particular fructose; Mannoses, maltoses or molasses; Sugar alcohols, especially sorbitol or mannitol; polyvinyl alcohol; polyvinyl acetate; Gelatin; Carboxymethyl starch.

12. A cigarette paper according to any one of claims 9 to 1 1, wherein at least 0.1 wt .-%, preferably at least 0.3 wt .-% and / or at most 7.0 wt .-%, preferably at most 5.0 wt .-% of the composition are formed by the dye, and / or

wherein at most 25.0 wt .-%, preferably 1, 0 wt .-% to 20.0 wt .-% of the composition are formed by the binder.

13. A cigarette paper according to any one of the preceding claims, wherein the

2

Application amount of the composition at least 0.1 g / m, preferably at least

2 2

0.3 g / m and / or at most 2.0 g / m, preferably at most 1.5 g / m based on the mass of dried composition and per square meter of printed area.

14. Cigarette paper according to one of the preceding claims, whose basis weight in

2

untreated state is at least 10 g / m, preferably at least 20 g / m and / or at most 60 g / m, preferably at most 35 g / m and particularly preferably at most 28 g / m ² .

15. A cigarette paper according to any one of the preceding claims, further comprising at least one inorganic, mineral filler, the paper to a

Mass fraction of at least 10%, preferably at least 15% and / or at most 45%, preferably at most 35% and particularly preferably at most 25%, in each case based on the cigarette paper without application of the composition added,

wherein the filler is preferably formed by calcium carbonate or other carbonates or oxides, in particular magnesium oxide, magnesium hydroxide or aluminum hydroxide or mixtures thereof.

16. A cigarette paper according to any one of the preceding claims, wherein the air permeability of the treated area is at least 10 CU, preferably at least 20 CU and / or at most 150 CU, preferably at most 130 CU.

17. A cigarette paper according to any one of the preceding claims, wherein the

Diffusion capacity of the treated area for C0 _{2 is} at least 0.01 cm / s and / or at most 3.5 cm s, preferably at most 3.0 cm / s.

A process for producing a cigarette paper according to any one of claims 1 to 17, wherein a water-based composition is applied to form a pattern having a Tamura Coarseness of at most 0.22 mm, preferably at most 0.20 mm,

wherein the printing on the aqueous composition increases the opacity according to ISO 2471 and the whiteness according to ISO 2470-1 is reduced so that the absolute difference in whiteness according to ISO 2470-1 is between one surface of the surface

Cigarette paper, on which the composition is applied over the entire surface, and a surface of the cigarette paper to which the composition is not applied, in the dried state of the composition at least 25%, preferably at least 35% and particularly preferably at least 40%, and at most 60%, preferably not more than 55%.

19. The method of claim 18, wherein the composition is printed,

especially in the gravure printing process, in the offset or in the flexographic printing process, or sprayed on.

20. Cigarette comprising a tobacco rod and a cigarette paper according to one of claims 1 to 17, which surrounds the tobacco rod, wherein the proportion of the treated area on the visible surface on the cigarette at least 20%, preferably at least 50% and particularly preferably at least 70% is and / or in which the pattern repeats periodically and the circumference of the cigarette is an integer multiple of the repetition rate of the pattern in the circumferential direction.