EP0069467B1

EP0069467B1 - A process for utilizing tobacco dust

Info

Publication number: EP0069467B1
Application number: EP19820302905
Authority: EP
Inventors: Grant Gellatly
Original assignee: Philip Morris Products Inc; Philip Morris USA Inc
Current assignee: Philip Morris Products Inc
Priority date: 1981-06-04
Filing date: 1982-06-04
Publication date: 1987-11-19
Also published as: EP0069467A2; AU8443682A; AU553427B2; FI821980A0; FI70777C; FI70777B; AR241571A1; DE3277680D1; CA1182024A; EG16267A; BR8203288A; EP0069467A3; PH21985A

Description

This invention pertains to the field of smoking materials. More particularly, the present invention concerns a method for preparing a smoking material with reconstituted tobacco having tobacco dust incorporated therein.
As a result of treating, handling and shipping tobacco in its various forms, notably cigar wrappers or fillers, cigarettes, and smoking tobacco, tobacco fines and dust are generally formed. This material, generally less than about one centimeter in size, is recovered from air filters, tobacco screens and other separating systems.
These tobacco fines or dust have commonly been discarded or employed in conjunction with other tobacco by-products, such as stems, stalks and leaf scraps resulting from the stripping of leaf tobacco, in the preparation of reconstituted tobacco material.
A method of utilizing tobacco dust, in which tobacco component feed stock is slurried in an aqueous medium and formed into sheets, and the dust is applied as a coating to the formed sheet before it is dry, is described in US―A―3 141 462. In that patent, tobacco waste particles such as stems or slivers are broken down or separated into fibres and mixed with tobacco fines or dust and a relatively small quantity of water to form a thick slurry, which cannot flow or be poured onto a paper-making wire. Instead it is deposited by spraying to form a layer, which is subjected to a squeezing operation, aided by suction, to remove excess water, and is then dried to produce a flexible sheet. Tobacco dust may also be handled separately and sprayed or sifted onto the wet layer prior to drying.
It is not, however, possible to include tobacco dust in the slurry employed in a paper-making type process for the preparation of reconstituted tobacco, in which case the tobacco dust must generally be discarded or employed elsewhere. This is due to the fact that in the paper-making process, the slurry of refined tobacco by-products is cast from a head box onto a wire screen for forming the desired sheet. If the screen mesh size is too large, the dust particles simply pass through the wire screen and do not, as a result, become incorporated in the resulting sheet. Conversely, when the screen mesh size is reduced so as to prevent the tobacco dust particles from passing therethrough, the dust considerably slows the drainage of the water through the screen and correspondingly slows the rate of sheet formation by actually plugging and/or clogging the wire screen openings.
Accordingly, although the paper-making type process for making reconstituted tobacco material has many advantages over the alternative belt method, and is consequently the preferred method, it nevertheless does suffer from the disadvantage of not being able to efficiently and conveniently employ tobacco dust by-products.
This invention now provides a method for economically utilizing tobacco dust by-products in a paper-making type process for making reconstituted tobacco. This method not only reduces the loss of the dust through the wire screen when the screen openings are too large and further more reduces clogging and/or plugging of the screen openings when these openings are too small, but additionally, the method of the present invention actually increases the rate of drainage through the wire screen correspondingly increasing the rate of production of-the reconstituted tobacco sheet and improving its quality by allowing better refining of the remaining tobacco stem feedstock.
The method of this invention is characterised in that, in the method identified above for utilizing tobacco dust, the sheet is formed by a paper making process, and the tobacco dust is dispersed uniformly in a second aqueous medium and applied to the sheet as an aqueous dispersion.
In the preferred practice of this invention tobacco dust is admixed with the extract liquor which has been concentrated in steam evaporators after recovery from extraction presses. The mixture is then passed through a homogenizer or mixer to refine and uniformly disperse the particles in the concentrated extract. The viscous product is applied to the reconstituted tobacco web which has been removed from the Fourdrinier wire, and the coated web is then dried in the usual fashion. Final cutting, shredding, and blending into cigarette filler or the like is conventional.
The method for utilizing tobacco dust in the preparation of reconstituted tobacco employing a paper-making process calls for certain modifications in the usual process.
Tobacco dust by-product material is first collected. It may be used totally apart from the Fourdrinier feedstock, or a portion may be sent with the stems while the remainder is kept for the coating preparation. This separated fines fraction is blended with concentrated extract as will be described below.
Meanwhile, the said feedstock, according to the usual process, is diluted with 500 to 600 parts of water per 100 parts of solids and is passed into refiners which beat the stems to form a smooth, well-blended fiber slurry. This is concentrated in an extraction press by removal of about five-sixths of the liquid extract which is sent to the concentrators. Here steam heating vaporizes a portion of the water.
The stock from the press is diluted with white-water from the Fourdrinier to a consistency which is suitable for application to the wire at the headbox of the Fourdrinier. That part of the process is conventional in the extract-recombine papermaking reconstitution process.
The concentrated extract, according to the present invention, is blended with the separated dust fraction in preparation of a coating for reapplication, by any of the following alternatives:

1. The blend of concentrate and fines is homogenized wetmilled in the tobacco extract liquor, as for example in a Gaulin homogenizer or the like; orthe dry dust is dry dust is dry milled prior to dispersing with the extract and dispersed into a slurry. High shear rate dispersion is preferable such that the dust and liquid combination is placed in turbulence during mixing;
2. The dust, before blending, is treated with a pectin release agent such as aqueous diammonium phosphate to release the tobacco pectins and the resulting dispersion is blended with the extract (in a more concentrated form to allow for the dilution which results); or
3. The dust is moistened with water and treated with steam to soften and loosen the particles, resulting in a thick paste which is then blended with concentrated extract, and optionally homogenized as under (1) for preparation of a coating composition.

The coating is applied to the formed moving tobacco web ahead of the dryers, at or near the point where the sizing press is located in the basic process. The application may be by a roll coater, reverse roll coater, blade coater, high-pressure spray, or any similar means for applying viscous liquid to a running web. When dry, the reconstituted tobacco sheet is not sticky and does not shed dust before, during, or after cutting, to any greater degree than the conventional reconstituted product.
The maximum acceptable particle size in the coating depends on both adherence of the particle to the web and aesthetics of the coated web. Particles of 1000 microns and larger will adhere. However, particles this large give the coated web a sandpaper like texture and appearance. A smaller particle size gives a corresponding smoother appearance closer to that of leaf.
When the paper-making process does not involve a separate reapplication if the tobacco solubles as discussed above, for example, the process of US―A―3,415,253, the dust may be dispersed in water in place of extract and applied for one of the three alternative treatments described. The addition of a gum to the water is optional.
The invention will be described in greater detail by reference to a number of examples of its practical application. In these examples, reference is made to several measurements or parameters of significance in the manufacture of tobacco smoking materials.
The term "cylinder volume" is a measure of the relative filling power of tobacco or reconstituted tobacco for making smoking products. Higher cylinder volume means higher filling power, or capacity to make more satisfactory cigarettes with a given unit weight. The term "oven volatiles" describes a measure of the approximate moisture content (or percentage of moisture) in tobacco or reconstituted tobacco. As used throughout this specification, the values employed to characterize tobacco or reconstituted tobacco, in connection with these terms, are determined as follows:

Cylinder volume (CV)

Tobacco or reconstituted tobacco filler weighing 10.000 g is placed in a 3.358-cm diameter cylinder and compressed by a 1875-g piston 3.335 cm in diameter for five minutes. The resulting volume of filler is reported as cylinder volume. This test is carried out at standard environmental conditions of 24°C and 60% RH; conventionally unless otherwise stated, the sample is preconditioned in this environment for 18 hours.

Oven-volatiles content (OV)

The sample of tobacco or reconstituted tobacco is weighed before and after exposure for 3 hours in a circulating air oven controlled at 100°C (212°F). The weight loss as percentage of initial weight is the oven-volatiles content.

Equilibrium OV and equilibration

The OV after equilibration has significance in comparing properties of smoking materials at the same conditions. Materials are, generally, equilibrated (reordered) at conditions which are well known in the trade. Equilibrating is preferably done at standard conditions, which generally involve maintaining the tobacco at a temperature of 24°C (75°F) and 60% RH (relative humidity) for at least 18 hours.

Hot-water solubles (HWS)

This is a straightforward measurement of the weight loss from a sample boiled in water for an hour and filtered.

Particle screen sizes

"Longs" are defined as filler particles held back by 1.91 mm (0.075-inch) screen openings. "Mediums" are particles which are held back by 0.86 mm (0.034-inch) screen openings. "Shorts" are held back by 0.51 mm (0.020-inch) openings. "Smalls" are held back by 0.28 mm (0.011-inch) openings. "Fines" pass through that screen.

Standard smoking procedure

Test smoking by machine was done according to the FTC method as described by Pillsbury et al., J. Assoc. Offic. Anal. Chemists 52: 458―462 (1969).

Example 1

Reconstituted tobacco was made by an extract-recombine paper-making process from a stem and fines feedstock containing approximately 37% by weight of fines. This will be considered the control. In a similar operation approximately 54% of the fines including dust, was withdrawn from the feedstock and the web was prepared while the extract liquor was diverted from the sizing press. The fines which had been withdrawn were combined with the extract liquor which had first been concentrated to approximately 45% solubles, and the combination was passed through a Gaulin homogenizer. The product was applied by a blade coater at various loadings to one side of the reconstituted sheet which was then passed through the drying system and shredded as filler. It was observed that the coating did not appreciably impregnate the web, but remained essentially on the surface where applied. Test results and OV and solubles analysis are given in Table I. Some web was also coated on both sides.

Example 2

With a papermaking process all fines including dust, were withdrawn from feedstock. They were blended into concentrated extract liquor together with diammonium phosphate to release the pectins from the tobacco material. After thorough blending, the product was coated with the combined material by blade coater on one side of the web and the product dried in the usual way. The reconstituted filler from this process did not show a loss in filling power in spite of the build-up of solids on the sheet.

Claims

1. A method of utilising tobacco dust in which tobacco component feed stock is slurried in an aqueous medium, and formed into sheets, and the dust is applied as a coating to the formed sheet before it is dry, characterised in that the sheet is formed by a paper making process, and that the tobacco dust is dispersed uniformly in a second aqueous medium and applied to the sheet as an aqueous dispersion.

2. A method according to claim 1, characterised in that the dust is separated from the feed stock before the remaining feed stock is slurried in an aqueous medium.

3. A method according to claim 1 or 2, characterised in that liquid phase removed from the refined slurry prior to sheet formation is concentrated and used to provide the second aqueous medium.

4. A method according to any of claims 1 to 3, characterised in that the dust and the second aqueous medium are homogenised to reduce the dimensions of undissolved fines to less than 50 microns.

5. A method according to any of claims 1 to 3, characterised in that the dispersion of the dust is brought about by introducing diammonium phosphate with stirring.

6. A method according to any of claims 1 to 5, characterised in that the dispersion is applied with a coating roll or a coating blade.

7. A method according to any of claims 1 to 6, characterised in that the feedstock is slurried with water.

8. A method according to any of claims 1 to 7, characterised in that the sheet is formed on a paper making machine, from which white-water is recovered, and wherein the greater part of the liquid phase is removed from the refined slurry and at least a part of the removed liquid phase is replaced with the white water.