FIELD OF THE INVENTION

The present invention relates to reconstituted tobacco and particularly to incorporation of nanofibers in reconstituted tobacco.

BACKGROUND OF THE INVENTION

In the manufacture of tobacco products, such as cigarettes, some of the tobacco is, or becomes, ill-suited for such use during its processing. Generally, tobacco stems and leaf scraps result from the stripping of leaf tobacco. In addition, tobacco dust is produced when tobacco is treated, handled and shipped. Tobacco processing steps include, among others, threshing (stems are separated from the leaves), primary (various classes of tobacco are blended, flavored and cut) and making and packing of cigarettes.

Tobacco dust, tobacco stems and leaf scraps have been used in the past to produce reconstituted tobacco sheets. However, prior art techniques for reconstituting tobacco have many drawbacks, such as loss of aroma and foil flexibility, or water excess integrated in the process, among other drawbacks, which can make the process uneconomical.

The amount of powder generated in the production process of tobacco could run between 7-15% in the threshing; 5-7% in the primary and 3-4% in the making and packing of cigarettes. To combat these losses, various technologies have been developed as follows:

1. Paper Technology: This accounts for over 50% of the total reconstitution industry. A mixture of fines, midribs and sometimes tobacco stems are broken up and mixed by high agitation force in a hopper that breaks the parts and mixes them with a high percentage of water. The insoluble residue is further macerated and the resulting material is formed into a paper-like web on a paper-making machine. The extracted water is concentrated by evaporation to create a high tobacco content solution. The web is dried and impregnated with the high concentrated extract that has been produced from the water. A high concentration of flavor is required in order to resemble the original tobacco taste. Thereafter the film is dried and cut and added to the tobacco blend. Main drawbacks of the process include:

a. High product cost due to the energy costs needed for drying the large quantity of water used (98%) in the proper formation.

b. Woody taste of the tobacco and/or lack of aroma due to the fact that the lignin that carries the aroma has been washed out. c. Large initial investment due to the need for elaborated drying process resulting in a long and costly dryer. The paper making process involves fairly complicated machinery and peripheral costly supply systems for electricity, water and steam.

2. Band cast or cast leaf: The scraps powder and fines are ground to a fine powder that is then mixed with binder and with a high percentage of water to create a slurry that is poured on a moving stainless steel conveyer, which conveys the slurry to a drier. The dried slurry is a layer or lamina of tobacco that is scraped off the conveyer cut and introduced back into the line as a lamina. It is an old technology that represents various drawbacks such as: a. High operational energy cost due to the high percentage of water that has to be dried (80-90%)

b. Brittle final products with low resistance resulting and in a high loss of reconstitution (recon) due to the generation of dust in the cutting; this could reach levels of 10-20% loss out of the recon processed.

c. Low filling power in the cigarette produced (40-45 cc/lOgr)

d. Fairly high initial investment in the line costs due to the elaborated drying process.

3. Extrusion: The ground tobacco powder is mixed with water and binders and moved into an extrusion pressure chamber where it is pushed towards a die set to form a specialty or rectangular shaped noodle. The noodles are cut to a size of 5- 15mm and dried. The technology presents the following drawbacks:

a. Loss of Aroma

b. Lack of filling power due to the geometry of the final product (only square shaped rags could be integrated in the line pneumatic system) which is high in density (35 cc/lOgr). c. Tangling with the rest of the tobacco and creating lumps when mixed with the tobacco rags.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved reconstituted tobacco, as is described more in detail hereinbelow.

The present invention overcomes the drawbacks of the prior art technologies and improves parameters, such as energy consumption, by reducing the amount of water used in the process. Filling power and resistance of the formed foil are improved, while maintaining the natural sensory impact of the tobacco.

Several embodiments are proposed in current invention. One embodiment is a creation of a semi- wet mixture of tobacco and other components and the creation of a film by passing through lamination rolls. Another embodiment is the application of the semi-wet mixture on a mat that is inserted into the lamination rolls and the semi-wet powder is attached the mat surface. In both embodiments the incorporation of nanogels either in the semi- wet mixture or in the mat proved to improve substantially the characteristics of the end product. The nanofibers, e.g., NCF (nanofibrillated cellulose), may be made from wood fibers from which the lignin has been removed by sulfuric acid treatment or alkaline and later bleached. Alternatively, the nanofibers may be made from non-treated tobacco-based nanofibers. The nanofibers improve the characteristics of the end product.

BRIEF DESCRIPTION OF THE DRAWINGS

These and additional constructional features and advantages of the invention will be more readily understood in the light of the ensuing description of embodiments thereof, given by way of example only, with reference to the accompanying drawings wherein:

Fig. 1 is a simplified illustration of a block diagram of the reconstitution process, in accordance with a non-limiting embodiment of the present invention;

Fig. 2 is a simplified illustration of the production line, in accordance with a non- limiting embodiment of the present invention.

Fig. 3 is a simplified illustration of filling power and tensile stress results, in accordance with another non-limiting embodiment of the present invention.

Fig. 4 is a simplified illustration of, in accordance with another non-limiting embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to Fig. 1, which illustration of a block diagram of the reconstitution process, in accordance with a non-limiting embodiment of the present invention.

The current invention is based on two parallel processes that converge in the final lamination process: lamination process with tobacco mixture only, and lamination with mat support. A. Lamination process with tobacco mixture only

1. Scraps and fibers are screened large agglomerations of powder are vibrated and removed. Metal parts are removed with a magnet traps. (101-105)

2. The scrap and fibers are dried to 8% in order to facilitate the grinding the drying is done with a double sleeve tube where the incoming solids are dried with steam running in the external tube (106), grinding grain size of 60-120 mesh creating a homogeneous powder is done with the high impact mill (107). The material is transported by means of various transport devices, such as but not limited to, pneumatic transport device (108), inclined screw conveyor (109), and reversible screw conveyor (110).

3. Mixing of solids with natural binders in a solid powder form like gums of Guar and or Xanthan or CMC (Carboxymethyl cellulose) and others, is done with a ribbon blender (111-112).

4. Mixing liquids and or nanogel with propylene glycol and glycerin to obtain flexibility and humidity retention in the final product is done with a wet mixer (117).

5. Both components, solid and liquid, are mixed with high-speed turbines; the humidity level is set at 20% to 50% in order to maintain lower drying cost (116).

6. A film is formed with a thickness of 0.15-0.3 mm through 1-3 stages of lamination (120) (passing through sets of rolls with forming high pressure).

7. The film is passed through a dryer reducing the humidity to 12-14%, which is the common humidity used in the tobacco industry (121).

8. The film is then cut to foil or shredded (121) to cut rag depending on the preference of the end user.

B. Lamination with mat support:

1. Production of a mat based on either cellulose fibers and/or tobacco fibers forming a low gramature paper 5-35 GSM the mat is in the form of bobbin (124).

2. The semi- wet powder described above is produced following steps 1-5 in the above-described lamination process (A). 3. The mat described above is introduced in to the lamination process through the rolls (120) together with the semi-wet powder resulting in a coating of the powder on one side of the paper mat.

4. The paper mat coated on one side is dried and returned for a second side coating.

5. The double side coated mat is passed to the dryer to reduce the humidity to 12- 14%, then cut to foils or shredded (123) to cut rag depending on the preference of the end user.

The content and type of binders may change from one method to another. It has been proved through our tests that certain binders like CMC will not function in a paper coating process while other types of gums like Arabic xanthan and or guar function better.

Nano and Micro Cellulose addition

Tests have been conducted in order to measure the impact of addition of nano and micro cellulose to the semi-wet mixture described in the two previous embodiments. The nano cellulose has been produced from bleached cellulose made from eucalyptus (but not limited to this) and may apply to any source of vegetal fiber including tobacco fibers. The cellulose was treated with the following stages in order to produce nano cellulose:

a. The cellulose was broken and mixed with water in a pooper blender for 5 minutes. b. The emulsion was processed with Nano Collider built with special grinding wheels with adjustable space between the wheels. One wheel is static while the other is moving in a rotation of 1,000-5,000 RPM. The amount of fibers in the water was at the range of 1-10%. c. The process b has been repeated from 20 to 50 times until the mixture has turned in to nano gel a viscous paste generated due the increase in surface area of the nanofibers.

d. The mixture was added to the above emblements as a water substitute, the resistance and the filling power of the dried reconstituted tobacco have been measured.

The parameters that are commonly used in the industry are filling power, which measures the volume in CC that 10 grams of tobacco mixture is obtaining, the resistance is the measurement of force in KG applied until the rupture of the mat and multiply to an equivalent of KG per linear meter. It is noted that for tobacco applications that require low grammage paper, such as cigar binders, various regulatory bodies require the percentage of tobacco in the blend of the binder to be at least 75%. The binder for cigars is made of 2-3 layers; one layer is the mat and the other layers (one or two sides) are coated with a semi-wet mixture. Adding tobacco in the mat during the paper production can weaken the resistance strength. In the present invention, this problem is solved by adding nanogel to the semi -wet mixture (e.g., made of tobacco only, or nanogel made of cellulose only, or nanogel that includes other materials, or a combination of all of them in various consistencies) which increases the resistance.

The results shown in Fig. 3 are measured on the first embodiment only. The coating on the paper increases the resistance to rupture and the filling power.

The nanofibers generated are shown in an Electronic Microscope photo (Fig. 4). As can be seen, the diameter of the fiber is 5-10 nanos and the creation of a web could be seen in the cross links between the fibers which explain the increase in resistance to tensile and compression force (which is being expressed in the filling power result).

In accordance with a non-limiting embodiment of the invention, a layer or mat may be constructed of cellulose (e.g., cellulose only or combined with other materials), tobacco stems (e.g., tobacco stems only or combined with other materials), and nanogel (e.g., made of tobacco only, or nanogel made of cellulose only, or nanogel that includes other materials, or a combination of all of them in various consistencies). In addition, these materials may be combined with air cured tobacco, such as for cigars.

In accordance with a non-limiting embodiment of the invention, a layer or mat may be constructed of tobacco leaf powder (e.g., tobacco leaf powder only or combined with other materials), tobacco stems (e.g., tobacco stems only or combined with other materials), and nanogel (e.g., made of tobacco only, or nanogel made of cellulose only, or nanogel that includes other materials, or a combination of all of them in various consistencies). In addition, these materials may be combined with air cured tobacco, such as for cigars.

In accordance with a non-limiting embodiment of the invention, the mixture of tobacco is adhered to an adhesive layer applied on the rolls. The layer includes organic glue mixed with water or any other binding layer of adhesive, which can be made, for example, from starch, natural gum like Arabian, Xantana, Guar, CMC and/or a layer of nanogel. In order to create the layer, rolls can be dipped in a bath of adhesive mixture or the adhesive may by sprayed or applied by any other means that creates a fine adhesive layer on the mat on which the powder will later be coated. The mat with the wet adhesive layer is passed through an application chamber where dry tobacco powder is applied over the mat with the adhesive layer. The application may be accomplished by several methods, such as but not limited to, high pressure jet spraying, natural gravity fall, plunging in a container that consist of powder, or by applying an electrostatic charge to the mat and opposing charge to the powder so the powder will be appealed to the mat. The scope of the invention includes any technology or method by which the powder can be applied and adhered to the mat. If required, the mat with the powder may pass through a scraper and pair of rolls that establishes the final thickness of the dry powder applied. Any other technology may be used to control the thickness of the coating layer and is within the scope of this invention. Accordingly, in an embodiment of the invention, the method includes making reconstituted tobacco sheet on a paper mat to be organic. Humid powder may be applied over a paper mat, wherein the mat is organic paper. In addition, the tobacco and all the components are also organic, with or without nanogel.