US 3141462 A
Description (OCR text may contain errors)
July 21, 1964 M s. BLOCK ETAL 3,141,462
PROCESSING TOBACCO Filed Sept. 22, 1961 H2O PLUS ADDITIVES FIG.I.
SOAKING AND MIXING TANK AIR F'NES SUPPLY LIQUID TANK RE'ruRN NO 'a's l3 20 P -3|' v HOMOGENIZER 2| 1 mxmc TANK' I 2'2 20 RECYCLE 23' EXCESS v HOMOGENIZER LAYER RETURN RELIEF STORAGE TANK vA| vE C 24 7 RECIRCULATING J 25 LINE 33 PUMP 26 a P 6!] INVENTORS:
JOSEPH J. LUBUS MELVIN D.SIDBURY M SABEL BLOCK CLIFFORD O.JENSEN SEPARATOR VACUUM PUMP THEIR ATTORNEYS United States Patent 3,141,462 PROCESSING TOBACCO M Sahel Block, Bloomfield, N.J., and Joseph J. Lubus, Melvin D. Sidbury, and Clifiord 0. Jensen, Greensboro, N.C., assignors to P. Lorillard Company, New York, N.Y., a corporation of New Jersey Filed Sept. 22, 1961, Ser. No. 139,928 14 Claims. (Cl. 131-140) This invention relates to the manufacture of tobacco products and it relates particularly to the manufacture of sheet tobacco from tobacco waste products, such as, for example, tobacco leaf stems, slivers, leaf fragments, tobacco dust and the like.
In recent years, so-called reconstituted tobacco has been manufactured from the waste products of tobacco generally by either of two processes. One such process is essentially the same as that which is used in the manufacture of paper, wherein the tobacco particles in the form of slivers, stern fragments, leaf fragments and tobacco dust are beaten into or disintegrated into a pulp in the presence of 40 to 50 parts of water to about one part by weight of the waste tobacco products. The resulting highly fluid pulp'is discharged on to a paper-making wire where a large proportion of the moisture is removed and then the resulting sheet is dried with heat to provide a self-sustaining sheet of tobacco. Because a large amount of water is necessary in the paper-making process, its removal is costly and renders this process uneconomical in current use.
The other process, while not requiring large quantities of water, is entirely dependent on binding materials to unit the finely-divided tobacco particles into a sheet, since they are incapable of uniting and forming, by themselves, a continuous self-supporting sheet. For that reason it has been necessary to admix with the fine tobacco particles substantial proportions of binders, for example, up to of suitable binders such as, for example, carboxymethyl cellulose, vegetable gums and the like, to render the resulting sheet self-sustaining. Although considerable research for non-toxic, tasteless and odorless binders has been conducted, the known binders still impair the flavor of the tobacco when burned in a cigarette, cigar or pipe, and render it brittle and dark in color, so that only a small portion may be used in blends with the natural leaf. Furthermore, the cost of the binders in the relatively large proportion required is relatively high, so that as in the case of reconstituted tobacco made according to the paper-making process, the cost is higher than desirable for economical use of either process.
In accordance with the present invention an economical process is provided for reforming tobacco Wastes into a generally useful tobacco product, whereby the disadvantages of the prior processes are overcome and a greatly improved tobacco product more nearly approaching the natural leaf is obtained.
More particularly, the present invention provides a process wherein tobacco waste particles such as stems and slivers are broken down or separated into fibers of substantial length capable of forming a self-sustaining mat or felt, in which other tobacco fines, such as particles broken from tobacco leaves during processing, may be intermingled and wetted with a relatively small quantity of water to form a thick slurry, which, after drying,
is self-sustaining even when completely devoid of binder. For example, the tobacco stem particles and tobacco slivers are mixed with water in the proportion of about one part of stem fragments and slivers to 6 to 13 parts by weight of water and this mixture is subjected to intensive. abrasion, vibration and impact which defibers the stems and slivers (separates the fibers in the stems and slivers) without breaking the fibers into short lengths.
The fibers resulting from such a defibering operation may be as much as a quarter to a half an inch long and thus are capable of forming a matrix or felt of excellent strength and handling properties. To the aqueous mixture of fibers may be added other tobacco particles, such as No. 8s, i.e., tobacco leaf fragments which pass through a No. 8 screen (8 meshes per square inch), including tobacco dust and the like, and this material is subjected to further disintegration to form a mixture of the long fibers and tiny particles in which the moisture content is about six to eight times by weight of that of its solid content. Such a mixture is in the form of a thick slurry which cannot flow or be poured on to a paper-making wire or other surface in the form of a uniform thin layer. In accordance with the invention, the slurry is deposited by spraying to produce a layer of a thickness corresponding approximately to the thickness of leaf tobacco. The layer may then be subjected to a squeezing operation which, aided by suction, removes excess water and may then be dried in any suitable way, such as, for example, by means of infrared radiation, hot air or the like to produce a finished sheet which is highly flexible and has a good bulking density and handling properties so that it may be readily intermixed with cut cigarette tobacco or the like for producing cigarettes and other tobacco products.
A cigarette blend of high quality made of leaf tobacco has a specific volume of 200 on an arbitrary scale used as a standard in the cigarette industry. The new material has a specific volume of 210 on that scale, showing that more cigarettes can be obtained from the same weight of the new tobacco sheet than with an equal weight of cut leaf tobacco because of its lower density. By contrast, tobacco stems have a specific volume of and reconstituted tobacco made by the paper-making process has a specific volume of on the aforementioned standard scale.
The new product resulting from this invention has the light color characteristic of natural tobacco leaf, a good flavor when smoked since it contains no added binder, and a self-sustaining burning power, even in sheet form. It has about twice the sugar content of ordinary reconstituted tobacco manufactured by paper-making process and it has handling properties superior to natural leaf tobacco in cigarette-making operations where the material is subjected to cutting and processing in machinery which has the tendency to break down the tobacco shreds.
For a better understanding of the present invention, reference may be had to the accompanying drawings in which:
FIGURE 1 is a schematic flow sheet illustrating a typimal method embodying the present invention; and
FIGURE 2 is a schematic view in longitudinal section of a device for processing and disintegrating or defibering the tobacco products.
Referring now to FIGURE 1 of the drawing, tobacco stems and fragments thereof which may range in length up to several inches are fed into a hammer mill 10 where they are broken into relatively shorter lengths, e.g., about one-eighth to one-half inch, but not ground to powder. The shorter stern particles, together with tobacco slivers, are transferred to a soaking and mixing tank 11 where water is added in the proportion of about 6 to 13 parts of Water to one part of slivers and stems by weight. Desirable flavoring materials also may be added at this point. The mixture is allowed to stand in tank 11 for about one hour or longer to impregnate the stem particles and slivers with water. Thereafter, the soaked particles are discharged into a supply tank 12 which serves to feed the particles to defibering device 13 referred to hereinafter as homogenizer which separates the fibers making up the stems and slivers without breaking them up into materially shorter lengths. A suitable homogenizer 13 is manufactured by Sonic Engineering Company of Stamford, Connecticut, and includes a screw-type or high pressure pump by means of which the aqueous suspension of stem and sliver particles is forced at high velocity through a conduit 14 shown in FIGURE 2, and through a nozzle 15 having a slit 16 therein against the edge of a resilient blade 17, somewhat similar to a razor blade which is mounted at its rear edge in a support 18 spanning a conduit 19. The aqueous suspension flowing through the nozzle 15 impinges on the edge of the blade 17 setting it into high frequency vibration with the result that the particles are subjected to impact and high intensity vibrations that separate the stem particles and the slivers into their component fibers. By repeatedly recirculating the suspension through the nozzle by means of a bypass line 20 connected to the conduit and the supply tank 12 or by forcing it through a plurality of similar homogenizers connected in series, an aqueous suspension of tobacco fibers is produced. This material is discharged into a mixing tank 21 where tobacco fines and No. 8s may be added and mixed therewith in any suitable way, such as, for example, paddle-type or propeller-type mixers (not shown). The mixture at this stage has an increased solids content and is considerably less fluid. It is recirculated through another homogenizer 22 similar to homogenizer 13 by means of a recirculating line 23 or through a series of homogenizers. When the tobacco fines have been disintegrated sufiiciently to form with the fibers a semi-fluid slurry, it is delivered to a storage tank 24.
At this stage of the operation, the moisture content is about 6 to 8 parts of water and one part of tobacco solids. Due to the thick semi-fluid condition of the suspension, it is pumped by means of a suitable high pressure pump 25 or one or more booster pumps 26 to one or more spray nozzles 27 which discharge the material downwardly through a tower 28 onto an endless moving screen 29 similar to a paper-making screen thereby forming a thin layer L of wet tobacco particles on the screen 29.
The upper surface of the layer L, due to the spray deposit of the tobacco fibers and particles, is somewhat rough. In order-to improve its surface texture, the layer on the screen is passed below a smooth surface sizing roller 30 which reduces the thickness of the layer L and smoothes its upper surface. Inasmuch as the moist tobacco tends to cling to the surface of the roller 36, a suction box 31 actuated by vacuum pump 29 is positioned below the screen belt 29 to draw the tobacco away from the roller 3t; and thus prevents sticking to the roller. The suction box 31 also removes about 50% of the water in the lawer L and this liquid is returned from separator 30' to tank 11, with any tiny tobacco particles that passed through the screen belt 29 remaining in separator 30.
The screen belt 29 carries the particles forming layer L through a drying tunnel 32 which may be equipped with infrared heaters (not shown), or through which hot air may be circulated to reduce the moisture content of the tobacco layer L at the discharge end of the tunnel 32 to about 4 to 25% moisture, or to a point at which the layer or sheet L is self-sustaining and can be peeled as a continuous sheet from the surface of the screen belt 29. The lower degree of such residual moisture in the 4 to 25% range depends on whether or not the belt 29 is pretreated with a non-sticking agent such as lecithin.
As illustrated in FIGURE 1, a recirculation line 33 having a relief valve 34 may be provided to return excess slurry from the pump 25 to the storage tank 24.
In the operation described, no waste of tobacco products occurs. Any tobacco particles which are oversprayed in the tower 28, or sheet fragments which are produced when the production cycle is started, can be returned to the mixing or supply tanks 11, 12 or 24 by respective return lines 31', 20 or 28' and can be reprocessed and re-used.
In a typical example of the process, moistened tobacco stems and slivers are mixed with and soaked in about 12 parts of water for each part of stems and slivers by Weight. The solid tobacco particles are allowed to soak for at least one hour and then are delivered to the supply tank 12 from which the water-tobacco suspension is discharged into the homogenizer 13 and is recirculated therethrough about 10 to 12 times until the stems and slivers are defibered and separated into the component fibers. The resulting material is discharged into the mixing tank 21 where tobacco fines and No. 8 screen size particles are added. The tobacco fragments supplied to the system, in a typical operation, consist of about 60% stems and slivers, 20% factory by-products (tobacco fines) and 20% leaf fragments (No. 8s) by weight.
By adding the indicated proportion of fines and leaf fragments, the proportion of the solids to water in the suspension in the supply tank 21 is about one part of solids to 8 parts of water by weight. This thick slurry is then homogenized or further defibered and subdivided by passing it through the second homogenizer 22 about four to six times and is discharged into the storage tank 24 for supply by the pumps 25 and 26 to the spray nozzle or nozzles 27. The material discharged through the spray nozzles 27 is an aqueous suspension having the ratio of solids to water indicated above.
The movement of the screen belt 29 is so related to the temperature in the drying tunnel 32 that the issuing sheet L has at least 6% moisture.
The dried tobacco sheet L is light tan in color and has sufiicient strength that it can be peeled readily from the belt 29 and can even be folded and creased sharply due to the presence of the matrix of interlaced fibers.
The process and the equipment for practicing it are susceptible to considerable modification. Thus, for example, additives such as flavors, humectants, wetting agents, and the like, may be introduced into the soaking tank 11 With the water supplied thereto. Other types of high frequency (supersonic) homogenizers or their equivalents may be used to disintegrate the stems and slivers into the component fibers. Moreover, instead of recirculating the suspensions and slurries through the homogenizers l3 and 22, they may be forced successively through a series of homogenizers to obtain continuous production of the product.
While only one spray nozzle 27 is illustrated, it will be understood that a plurality of spray nozzles may be provided in the spray column 28 when a sheet of substantial width is to be produced.
Drying of the sprayed layer can be accomplished in any number of different ways as, for example, by spraying the material on a continuous imperforate belt, or on a drying drum which may be heated in order to remove the moisture from the tobacco layer. The tobacco slurry may be sprayed by a series of spray nozzles arranged along the length of a belt with drying means interposed between the spray nozzles so that a first thin layer is sprayed on the drying surface, partially dried; another layer is sprayed on the partially dried layer and dried, and still other layers may be deposited and dried to build up the layer to a desired thickness. Successive spraying and drying operations are especially useful with an imperforate belt or a drum drier.
Inasmuch as tobacco dust is finely divided, it need not be added to the suspension in the mixing tank 24 but may be handled separately. Thus, the mixture of stem and sliver fibers and finely-divided tobacco by-products can be sprayed on a drying surface and the tobacco dust may be then sprayed or sifted onto the wet layer prior to drying so that the fines will adhere to the layer. Likewise, the stems, the tobacco by-products and fines may be homogenized separately and the slurry of stems may be sprayed first to form a felt or mat onto which the finelydivided by-products and the tobacco dust are sprayed.
While binders are not required for the production of a self-sustaining tobacco sheet, a very small proportion of binder may be added if. the sheet is to be subjected to extremely severe processing or handling. Thus, suflicient propylene glycol alginate can be added to the material in any of the soaking or mixing tanks as may be desired, so that the finished sheet will contain at least 1% of propylene glycol alginate. Also, as indicated above, humectants and flavoring materials can be added in the usual ratio and they may be of any of the usual types.
Due to the low moisture content of the material undergoing treatment, drying of the sheet is greatly simplified and waste or loss of water in the process is very substantially reduced as compared with prior processes. The less severe drying conditions and the lower content or complete absence of binders provides a tobacco sheet of a light brown or tan color similar to high quality cigarette tobacco which can be shredded and mixed in high proportion with other cigarette tobacco without altering the filling and burning properties, flavor or general handling characteristics of the tobacco.
From the foregoing description of the process and the specific example thereof, it will be understood that the process is susceptible to considerable modification and, accordingly, the invention is not limited save by the terms of the following claims.
1. A method of producing tobacco sheets from tobacco fragments including stem material and tobacco fines comprising the steps of separating at least partially the fibers of fiber bundles of said tobacco stem material by disintegrating pieces of said tobacco stem material while suspended in a liquid without substantial reduction of the length of said fibers to form a thick semi-fluid mixture thereof, spraying said mixture and said tobacco fines onto a surface to form a layer of said fibers and fines thereon, and drying said layer to form a self-sustaining sheet in which said fibers are interlaced to impart strength to said sheet.
2. The method set forth in claim 1 in which said tobacco fines are present in said fluid mixture and are sprayed with said fibers onto said surface.
3. The method set forth in claim 1 in which said slurry and said tobacco fines are sprayed successively onto said surface.
4. A method of producing tobacco sheets from tobacco fragments, comprising forming a mixture of about one part of tobacco stem pieces and about 6 to 13 pants of water, subjecting said mixture to high frequency vibrations to separate, at least partially, the fibers of the fiber bundles of the tobacco stem pieces Without substantial reduction of their length which fibers interlace and form a self-sustaining matrix, adding tobacco fines in a finelydivided state to said mixture, spraying said mixture onto a surface to form a layer thereon containing said fibers in an interlaced condition and forming a matrix containing said finely-divided particles, and heating said layer to evaporate moisture from said layer to form a self-sustaining sheet.
5. A method set forth in claim 4 comprising subjecting said mixture of stem fibers and tobacco fines to high frequency vibrations and agitation to mix them thoroughly and reduce the size of said fines.
6. The method set forth in claim 4 in which said surface is porous and said layer and surface are subjected to pressure and suction to compress and partially dry said layer.
7. The method set forth in claim 4 in which said mixture is a thick slurry containing about one part of fibers and particles by weight and about 6 and 8 parts by weight of water.
8. A method of making tobacco sheets from tobacco fragments comprising passing a rapidly flowing mass of tobacco stern fragments into contact with a thin blade vibrating at supersonic frequency and leaf fragments to disintegrate said fragments and form an aqueous slurry of fine particles of leaf tobacco and stem fibers of substantial length capable of matting together to form a selfsustaining matrix, when dry, said slurry containing about one part of stem fibers and leaf particles to about 6 to 8 parts of water by weight, spraying said slurry onto a surface to form a thin layer of interlaced stem fibers and leaf particles thereon, rolling said layer and subjecting it to suction to reduce the layer to a predetermined thickness and to remove water therefrom with the resulting liquid returned for reuse, and drying the layer to form a selfsupporting sheet.
9. The method set forth in claim 8 in which said stem fragments are at least partially disintegrated into stem fibers prior to mixing them with tobacco particles.
10. A method of making sheet tobacco from tobacco fragments, comprising breaking tobacco stems and tobacco slivers into pieces not exceeding about one-half inch long, soaking the pieces in Water in the proportion of about one part of the pieces to between about 6 and 13 parts of water, by weight, to form an initial thick slurry, subjecting said slurry to abrasion and impact at supersonic frequency to at least partially separate the fibers of said pieces, adding leaf fragments to the slurry to reduce the ratio of solids to liquid to between about 1 to 6 and 1 to 8 by weight, subjecting the slurry to abrasion and impact at supersonic frequency to further separate the fibers of said stems and slivers and reduce the leaf fragments to a finely-divided state, spraying said slurry onto a surface to form a thin layer of interlaced fibers and leaf particles intermingled with said fibers, and drying said layer.
11. The method set forth in claim 10 in which said layer is partially dried by subjecting it to suction to withdraw water, the water is returned for admixture with said tobacco fragments, and said layer is heated to evaporate water therefrom.
12. The method set forth in claim 6 in which the liquid removed from said layer is returned to said initial mixture of tobacco stem pieces and water.
13. The method set forth in claim 8 in which the water removed from said layer by rolling and suction is returned to said aqueous slurry.
14. The method set forth in claim 11 in which the water withdrawn by suction from said layer is returned to said initial slurry of tobacco and water.
References Cited in the file of this patent UNITED STATES PATENTS 86,368 Consuegra et al. Feb. 2, 1869 267,784 Wood Nov. 21, 1882 346,887 Bennett Aug. 10, 1886 1,907,046 Darrah May 2, 1933 2,034,784 Wallny Mar. 24, 1936 2,265,455 Serpas Dec. 9, 1941 2,377,252 Lehrecke May 29, 1945 2,433,877 Wells et al. Jan. 6, 1948 2,584,053 Seavey Jan. 29, 1952 3,020,179 Hess Feb. 6, 1962 3,043,723 Cleverdon July 10, 1962 FOREIGN PATENTS 229,817 Australia Aug. 9, 1960 988,509 France May 9, 1951 570,265 Great Britain June 29, 1945 796,932 Great Britain June 25, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION July 21 1964 Patent N00 3 14l 462 M Sabel Block et all,
It is hereby certifiedv that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column l line 33 for "unit" read unite column 6 line 55 for "26%784" read 267 764 Signed and sealed this 24th day of November 1964,
EDWARD J. BRENNER I ERNEST W SWIDER' Commissioner of Patents Attesting Officer