METHOD FOR FORMING A CAST SHEET MATERIAL

Abstract

The present invention relates to a method for forming a cast sheet material, comprising introducing a slurry in a casting apparatus, casting the slurry onto a movable support by means of a casting means to form a layer and drying the layer for obtaining the cast sheet material.

Claims

1. A method for forming a cast sheet material (64), comprising: introducing a slurry (60,61) in a casting apparatus (6,7), casting the slurry onto a movable support (63) by means of a casting means to form a layer and drying the layer for obtaining the cast sheet material, characterized in that the slurry comprises at least two different types of slurries that are inhomogeneously blended with each other, such that in the cast sheet material the at least two different types of slurries are distinguishable as different types of sheet.

2. The method according to claim 1, characterized in that the cast sheet material obtained after drying is a single layer.

3. The method according to claim 1, characterized in that the at least two different types of slurries are different from each other in the composition thereof, wherein components of the composition are chosen from the group of fragrances, flavours, colouring agents, plant based materials, binding agents, humectants and fibers, or a combination thereof.

4. The method according to claim 3, characterized in that the at least two different types of slurries are different from each other in the amounts of some or all of the components of the composition.

5. The method according to claim 1, characterized in that the at least two different types of slurries are mixed in the same ratio or in different ratios.

6. The method according to claim 1, characterized in that between the step of casting and the step of drying an intermediate step is carried out, the intermediate step comprising disturbing the layer on the moveable support for changing the pattern of the layer formed by the casting step.

7. The method according to claim 1, comprising the following steps: a) preparing a base slurry; b) diverting the base slurry into two or more different slurry streams; c) adding to at least one of the slurry streams one or more components for creating a slurry stream having a composition that is different from the other slurry stream(s); d) casting the slurry streams thus obtained onto the movable support.

8. The method according to claim 7, characterized in that before step d) an intermediate step is carried out, the intermediate step comprises inhomogeneously blending of the slurry streams.

9. A cast sheet material consisting of a layer, in which layer at least two different types of slurries are distinguishable as different types of sheet material.

10. The cast sheet material according to claim 9, characterized in that the cast sheet material is a single layer.

11. The cast sheet material according to claim 9, characterized in that the at least two different types of slurries are different from each other in the composition thereof, wherein components of the composition are chosen from the group of fragrances, flavours, colouring agents, plant based materials, binding agents, humectants and fibers, or a combination thereof.

12. The cast sheet material according to claim 9, characterized in that the at least two different types of slurries are different from each other in the amount of the components of the composition.

13. The use of a cast sheet material obtained according to the method according to claim 1 as a wrapper for a smoking article.

14. The use of a cast sheet material according to claim 13, characterized in that the wrapper is a heat-not-burn article.

Description

[0043] The present invention will be illustrated by specific embodiments, by way of example only.

[0044] FIG. 1 shows a batch based slurry mixing process according to the present invention.

[0045] FIG. 2 shows a slurry mixing process according to the present invention.

[0046] FIG. 3 shows a slurry divider.

[0047] FIG. 4 shows another example of a slurry divider.

[0048] FIG. 5 shows another example of a slurry divider.

[0049] FIG. 6 shows a slurry mixing process according to the present invention.

EXAMPLES

[0050] An aqueous slurry is prepared, comprising the components as shown here. The weight percentage is based on the weight of the final product excluding moisture)

TABLE-US-00001 Example 1 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Powdered cellulose 70% Glycerol 10%

[0051] The mixture of Example 1 is split into two parts of equal weight. One part is mixed with a water soluble colorant, thereby creating two different slurries, i.e. slurry A (provided with 1 wt. % of a red colour) and slurry B.

[0052] For preparing the laboratory sheet, a sheet making set up is used consisting of a glass plate, acting as a carrier material, a casting knife, or film applicator to apply a thin layer of slurry on the carrier material. The film applicator having a small receptacle over the width of the applicator, just before the feed side of the applicator, and a water bath on which the glass plate can rest during the drying stage. In a next step, the film applicator is placed on the glass plate, and slurry A and B are placed in the receptacle. When the film applicator is drawn over the glass plate, slurry A and B are slightly mixed in the receptacle, forming a macroscopically inhomogeneous blend of the two slurries, and the slurry layer deposited by the applicator therefore shows areas of different colour and upon drying, a sheet with a colour pattern is obtained.

[0053] The organoleptically distinguishable pattern of the slurries may be influenced by any or more of the following methods:

TABLE-US-00002 Example 2 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Tobacco powder 70% Glycerol 10%

TABLE-US-00003 Example 3 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Hemp leaf powder 70% Glycerol 10%

[0054] When slurries with the compositions of Example 2 and Example 3 are processed according to the method of the present invention, a cast sheet will result having distinct macroscopic areas with either a clear tobacco character or a clear hemp character. Upon consumption as a wrapper for a smoking article, this will lead to the taste subtly alternating between tobacco taste and hemp taste. Materials other than hemp leaf powder and tobacco powder can be used as well, for instance various herbs, taro leaf, various types of tea, or any combination of materials suitable for cast sheet manufacturing. In an embodiment where components are used that have a similar colour, the macroscopic pattern may not be visible, but will be detectable via other senses, like smell or taste.

[0055] Furthermore, the ratio between the different components may be varied, for example a composition having a more hemp like character with hints of tobacco, or a composition where the amount of tobacco is increased.

TABLE-US-00004 Example 4 Component Amount (wt. %) Cellulose fibers 5% Carboxymethylcellulose 15% Tobacco powder 70% Glycerol 10%

TABLE-US-00005 Example 5 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Tobacco powder 70% Glycerol 10%

[0056] When slurries with the compositions of Example 4 and Example 5 are processed according to the method of the present invention, as a result of the different ratios of binding agents and fibers, areas with different tensile strength and elasticity will result. This may for instance be used for manufacturing products that will tear at predetermined zones when a force is exercised. This may also be used for partitioning of the product. For instance, when thin streams of the weaker material are fed into the coater, thin tear lines appear in the finished product. It is clear that the width and the number of streams influence the ratio between the slurries.

TABLE-US-00006 Example 6 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Tobacco powder 70% Glycerol 10%

TABLE-US-00007 Example 7 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Tobacco powder 69.5%.sup. Vanillin 0.5% Glycerol 10%

[0057] In the above embodiment, one of two slurries (the slurry according to Example 6) is provided with a flavouring agent with a low vapour pressure. As with the combination of the slurries of Example 2 and Example 3 this will result in a product whereby consumption will lead to a variation in taste during consumption. In this case, the macroscopical inhomogeneities of the product will not be directly visible but will be organoleptically (smell) detectable. It will be clear that various flavouring agents, aromas, and taste enhancing components can be used in this fashion. It will also be clear that a component with a high vapour pressure (e.g. menthol) will eventually distribute homogeneously over the total product.

TABLE-US-00008 Example 8 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Fine Tobacco powder (D50 = 60 m) 70% Glycerol 10%

TABLE-US-00009 Example 9 Component Amount (wt. %) Cellulose fibers 10% Carboxymethylcellulose 10% Coarse Tobacco powder (D50 = 140 m) 70% Glycerol 10%

[0058] In the above embodiment, the slurries prepared on basis of the composition of Example 8 and Example 9 are identical in composition from a chemical point of view, and both contain tobacco. However, because in one of the slurries, i.e. the slurry according to Example 9, a coarser ground tobacco is used, the final cast sheet material will show areas with a fine structure, interspersed with areas with a tactile noticeable coarser structure.

[0059] Although the present Examples shown here are a combination of only two slurries, it will be clear that combinations of more than two slurries, for example three, four or even five, are equally possible, and also that different applications may be combined into one product. For instance, a cast sheet material with areas of tobacco character, interspersed with areas of hemp character, may have as a third feature that the final product is provided with lines where the product may tear easily. Likewise, a cast sheet material may be produced with two optically remarkably similar materials (for instance hemp and taro leaf). In order to create a noticeable difference between the cast sheet materials, the hemp slurry may for instance be made with finely ground hemp powder, whereas the taro slurry may be made with a coarse ground taro powder. The difference in texture of the final cast sheet material will then indicate a difference in smoking properties to the consumer.

[0060] FIG. 1 shows a batch based slurry mixing process according to the present invention. In such a batch based slurry mixing process two slurry batches, i.e. a slurry A and a slurry B with a different composition are prepared separately and stored in separate buffer tanks 1, 2. Slurry A is transported via pump 8, slurry B is transported via pump 9 and both slurries 3, 4 are mixed in mixer 5, such as an in-line static or dynamic mixer. The slurry thus obtained is cast onto a movable support (not shown) by means of a slurry divider 6 and a coating device 7 to form a layer.

[0061] FIG. 2 shows a slurry mixing process according to the present invention. From a slurry tank 20 a slurry is transported via pump 8 and split into two separate lines. An amount of an additional ingredient stored in tank 21 is fed via pump 9 into the main slurry flow. After this action, the slurry passes through an in line static or dynamic mixer 25 to form a modified homogeneous slurry 26 of that additional component. Thus, the composition of slurry 24 differs from the composition of slurry 26. Slurry 24 originating from tank 20 is mixed with slurry 26 in mixer 27. Such a mixing step results in a slurry comprising two different types of slurries that are inhomogeneously blended with each other. The slurry thus obtained is cast onto a movable support (not shown) by means of a slurry divider 6 and a coating device 7 to form a layer.

[0062] FIG. 3 shows a slurry divider. In a situation where a slurry divider 6 is used that starts a small width, and may spread out over a wider area, i.e. up until the total cast width, ridges, needles, baffles, or similar obstructions may be used to redirect the flow and promote intermixing of the slurries 30, 31.

[0063] FIG. 4 shows another example of a slurry divider. According to slurry divider 6 of FIG. 4 nozzles 42 are used to feed a flow of slurry 41 into a slurry 40 that already flows inside divider 6.

[0064] FIG. 5 shows another example of a slurry divider. Slurry feed pipes may each have one or more separate nozzles 52 with which slurry 51 is deposited in coating device 7. According to FIG. 5, a slurry divider 6 for slurry 50 is used, and a nozzle system for slurry 51 is used, and both slurries are simultaneously deposited in the coating device.

[0065] FIG. 6 shows a slurry mixing process according to the present invention. An intermediate step is carried out between the step of casting and the step of drying, the intermediate step comprises disturbing layer 64 on moveable support 63 for changing the pattern of the layer formed by the casting step. Such an intermediate step enables the formation of different patterns of the layer. According to FIG. 6 slurry 60 and slurry 61 are fed to mixing means 62 and the thus obtained inhomogeneous blend of slurries 60, 61 is transported to slurry divider 6 and coating device 7. Bar 65 rod provided with pins that are in contact with layer 64 on moveable support 63 can be moved in a plane parallel to the moveable support 63, or even perpendicular to the movement direction of the moveable support 63 (left to right), and these movements may be carried out in a continuous or discontinuous mode, or a combination thereof. The perpendicular movement may be combined with an alternating movement parallel to the direction of movement of the moveable support 63. In specific cases, it may be advantageous to have no movement of bar 65. The function of bar 65 is to change the pattern of layer 64 formed by the casting step.