Carbon Filled Wrapper For Smoking Article

Abstract

A carbon filled wrapper for smoking articles such as cigarettes, cigars and the like which significantly reduces the total particulate matter yield and organic vapor phase constituents in the mainstream smoke therefrom while simultaneously reducing the visible sidestream smoke. The carbon filled wrapper is preferably used as an inner wrapper for the tobacco column in combination with an outer wrapping of conventional cigarette paper or cigar wrap. The carbon content of the wrapper may vary over a wide range depending upon the effect desired. Various types of carbon, either activated or unactivated, may be used. Increased effects may be obtained if calcium carbonate is incorporated in the carbon filled sheet and the effects are further enhanced if the paper is treated with an oxidation catalyst such as the alkali metal hydroxides, bicarbonates and carbonates. The paper is also particularly suited as a means for introducing various flavorants to the cigarette since the carbon holds the flavor until released by the heat of the burning zone.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to smoking articles such as cigarettes, cigars and the like, and the wrapper for the tobacco column thereof, and more particularly to an improved wrapper for such smoking articles which when used either by itself or as an inner liner in combination with conventional wrappers significantly reduces particulate and vapor phase constituents in the smoke drawn through the smoking article as well as reducing the amount of visible sidestream smoke that normally emanates therefrom.

It has been the practice for a number of years to use various smoke filtering devices in cigarettes and other smoking articles to reduce the amount of certain constituents in the smoke. While some of these devices have been relatively successful, they still leave much to be desired in the way of reducing many of the materials found in cigarette smoke. Cigarette papers are conventionally modified by the addition of various burning chemicals to improve the burning rate and ash characteristics of cigarettes as disclosed in U.S. Pat. Nos. 2,580,611, 2,652,834, and 2,733,720, but such papers have little, if any, effect upon the content of the cigarette smoke. Also, it is well known to use a calcium carbonate filter in the production of cigarette paper to improve the appearance and properties of the paper as the above patents disclose. However, such conventional cigarette papers do not have a significant effect upon the reduction of undesirable constituents in the cigarette smoke.

A composite wrapper for cigarettes is disclosed in U. S. Pat. No. 3,395,714 in which the outer wrapper is conventional cigarette paper and the inner wrapper next to the tobacco column is a low-temperature melting point, heat-insulating plastic sheet material. Such a combination is stated to decrease the burning zone temperature of the cigarette resulting in a lengthening of the cigarette's low temperature distillation zone and an increase in the nicotine and flavor content of the smoke.

Various metal coated cigarette papers have also been suggested in the prior art. For example, U.S. Pat. No. 3,586,005 proposes a cigarette paper wrapper in which the paper is coated on either or both surfaces with a thin layer of a metal such as aluminum or aluminum-base alloys. The patentee asserts that cigarettes made with such wrappers have a higher peak burning temperature and form a relatively continuous and unbroken sheath or tube around the burned and burning tobacco. This tube is stated to oppose air entering the burning zone radially and acts as a lengthwise conduit for the air so that more air passes through the burning zone over its entire cross section making more oxygen available for more complete combustion and higher burning temperatures. However, the use of such metal coated paper as a wrapper for cigarettes is impractical since the long ash produced tends to pull the burning cone out of the cigarette when the ash is knocked off during smoking.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a means for reducing the particulate and gaseous ingredients in the smoke of cigarettes, cigars and the like. A specific object is to provide a means for reducing the quantity of gaseous components in cigarette and cigar smoke as well as reducing the particulate constituents thereof as the smoking article is consumed without impairing the smoking characteristics thereof. A more specific object is to provide a wrapper for the tobacco column of cigarettes, cigars and the like which accomplishes the foregoing objects.

In accordance with this invention we have found that by using a carbon filled wrapper for the tobacco column of a cigarette, cigar or similar smoking article that the mainstream smoke therefrom contains a reduced quantity of organic vapor phase components, and total particulate matter normally found in the smoke of such smoking articles made with conventional wrappers. In addition, the visible sidestream smoke from the cigarette or cigar is substantially reduced giving the appearance of a smokeless cigarette or cigar during static burning.

The carbon filled wrappers of this invention may be made using an ordinary paper furnish such as pulped wood or flax fibers to which is added a sufficient quantity of pulverized carbon filler. The furnish of fiber pulp and carbon filler is then used to make a paper sheet on conventional paper-making machines. The particular fiber furnish from which the carbon filled wrapper is made is not critical and any of the cellulosic fiber pulps used in paper making can be employed. The fiber pulps customarily used to make paper wrappers for cigarettes or the tobacco materials used to make cigar wrap are preferred. Thus, in addition to wood and flax fibers, the furnish may be pulped tobacco stalks or stems to which is added the carbon filler or the carbon may be added to the furnish used in making reconstituted tobacco sheets for cigar wrap.

Ideally, the carbon filled paper is used as an inner wrap under a normal outer wrap for the tobacco column of the cigarette or cigar. Conventional cigarette paper or cigar wrap is used as the outer wrapping for the smoking article. Such a combination reduces the tobacco weight necessary to make a satisfactory product, increases the tobacco rod firmness and does not alter the appearance of the cigarette or cigar since the outer wrap of conventional cigarette paper or cigar wrap hides the grey carbon filled inner liner.

In the case of cigarettes the construction is such that the carbon filled paper inner wrap can be sealed or unsealed. If left unsealed, the sealed outer wrap holds the inner wrap around the circumference of the cigarette.

The carbon content of the wrapper may vary over a wide range depending upon the reduction of vapor phase and particulate matter desired. Carbon amounts of at least 5 percent by weight based upon the weight of the paper will give satisfactory results and amounts as high as 90 percent can be used successfully. Higher amounts of carbon filler tend to produce greater reductions in particulate and vapor phase constituents. Either activated or unactivated carbon can be used in the carbon filled wrapper, although activated carbons are preferred. Carbons ranging from pulverized coal to very high activity coconut shell charcoal have been used successfully. Other typical examples are activated wood carbons, activated mill waste carbons, activated coal and petroleum base carbons, unactivated bituminous coal, and pulverized charcoal briquettes.

From an appearance standpoint, the particle size of the carbon should be small enough so that visible lumps do not show in the paper. This is generally more important when the filled sheet is used as an inner wrap in cigarettes since larger carbon particles produce visible lumps under the cigarette paper outer wrap. With cigars such lumps would be less noticeable and therefore not objectionable. Preferably, the carbon is finely pulverized and we have found that particulate carbon that will pass through an 80 mesh screen or smaller is a desirable size range.

The carbon filled wrapper produces the desired effect without the addition of any of the commonly used cigarette paper or cigar wrap burning chemicals. However, the use of burning chemicals appears to act synergistically with the carbon to provide enhanced results in reduction of vapor phase components and total particulate matter in the smoke in addition to providing better burning rate control. The most efficient burning chemicals that we have found are the alkali metal hydroxides, bicarbonates and carbonates, although there are many other commonly known burning chemicals that can be used such as citrate, phosphate and nitrate salts. It is also possible to use burning retardants in combination with the carbon filler to modify the combustion properties of the wrapper.

As discussed above, carbon in the wrapper alone provides most of the beneficial effects in smoking articles. However, the use of an alkaline earth metal carbonate such as calcium or magnesium carbonate as an additional filler material in the wrapper stock further enhances the effects obtained over the use of carbon as the sole filler material. Total particulate matter yield and the major organic vapor phase yield are significantly reduced by the addition of calcium carbonate to the carbon filled paper even when as little as 5 percent calcium carbonate by weight of the paper is added. Maximum reductions appear to be obtained with a total filler level of approximately 50 percent to 80 percent by weight in the wrapper using carbon as the sole filler or a carbon/calcium carbonate filler mixture containing at least 5 percent calcium carbonate by weight of the finished paper. Carbon/calcium carbonate ratios may be varied as desired to produce different yields of total particulate matter, major organic vapor phase components in the mainstream smoke, or the degree of visibility of the sidestream smoke.

The porosity of the carbon filled paper can be tailored to fit the requirements of the finished cigarette or cigar such as the air dilution of the smoke desired. When the carbon filled paper is used as an inner wrap, the porosity can vary over a wide range since porosity of the total wrapper in the finished cigarette or cigar can be controlled with the regular outer wrap.

This invention also provides an excellent method for the addition of flavorants to a cigarette or cigar since they are easily added to the carbon filled paper. The carbon holds the flavorant until it is released by the heat of the burning zone to go into the sidestream or mainstream smoke. Menthol, vanillin, and glycyrrhiza are examples of common flavorings for cigarettes and cigars that have been added to the carbon filled paper and used with very satisfactory results.

Greater than 50 percent reductions in the total particulate matter yield and major organic vapor phase yield in cigarette smoke have been achieved in cigarettes made with carbon filled paper wrappers in accordance with this invention. Similar dramatic effects are obtained in reducing the visible sidestream smoke. While we do not know with certainty why such reductions occur, it has been determined that the carbon filled wrapper normally increases the burning temperature of the smoking article. It is believed that this increase in burning temperature, particularly at the skin of the cigarette or cigar, is important in reducing yields in the smoke from cigarettes or cigars employing carbon filled paper wrappers, also the carbon in the wrapper downstream from the burning zone may tend to adsorb certain constituents in the smoke.

PREFERRED EMBODIMENTS

Typical results demonstrating the effects obtained in accordance with this invention are described in the following examples which are illustrative of the invention only and are not in limitation thereof.

EXAMPLE I

Sample cigarettes were prepared using a carbon filled paper inner wrap for the tobacco column and a regular cigarette paper outer wrap. All samples were 70mm in length and approximately 8mm in diameter. The carbon filled paper inner wrap was made conventionally from flax fiber pulp using an activated wood pulp carbon filler. The particle size of the carbon was such that it would all pass through an 80 mesh screen and approximately 25 to 50 percent would pass through a 325 mesh screen. The final carbon filled sheet had a basis weight of 60 g/M.sup.2 and contained about 70 percent by weight carbon. In half the samples prepared, the carbon filled paper for the inner wrap was further treated with an oxidation catalyst consisting of 5 percent solution of sodium carbonate. For control purposes, identical cigarette samples were prepared without a carbon filled paper inner wrap using the same tobacco and cigarette paper. The following table sets forth the results obtained given as a per cent of the property measured as compared with the control cigarette having no carbon filled paper inner wrap, measuring the smoke obtained from burning 60mm of the tobacco column of each cigarette. ##SPC1##

As the results in the above table clearly show, the total particulate matter yield and major organic vapor phase yield in the mainstream smoke from cigarettes with the carbon filled inner wrap are substantially reduced when compared with the control cigarettes having a conventional cigarette paper wrapper. Very substantial reductions were also obtained in the visible sidestream smoke.

EXAMPLE II

A number of carbon filled papers were prepared with different activities, types and amounts of carbon filler, both with and without additional calcium carbonate filler. Some of the papers were also additionally treated with oxidation catalysts. The particle size of each of the carbons tested was such that they would pass through an 80 mesh screen or smaller. The carbon filled papers were made by conventional papermaking techniques using flax pulp as the basic fiber and the weight of each of the finished sheets was approximately 60 g/M.sup.2. Each of the carbon filled sheets was then used in making a cigarette 70mm long and approximately 8mm in diameter with the carbon filled sheet as the inner wrap for the tobacco column under a conventional cigarette paper outer wrap. Identical control cigarettes were prepared from the same tobacco and using the same cigarette paper wrapping but without any carbon filled paper inner wrap. In the following table the results are given as a per cent of the property measured compared with the control cigarettes having no carbon filled paper inner wrap. All results are based on the smoke obtained from burning 60mm of each cigarette with approximately 10 standard 35cc puffs per cigarette.

TABLE 2 --------------------------------------------------------------------------- Comparison of Activated and Unactivated Carbons

Vapor Phase Side- Description T.P.M. Acrolein stream Carbon filled paper inner wrap Yield Yield T.P.M. containing 70% carbon by weight Main- Main- Yield stream stream __________________________________________________________________________ High Activity Wood Carbon; 72 mg Carbon per Cigarette 73% 61% 64% Medium Activity Mill Waste Carbon; 72 mg Carbon per cigarette 77% 54% 55% Unactivated Bituminous Coal; 72 mg Carbon per Cigarette 89% 98% 78% Unactivated Pulverized Charcoal Briquettes; 72 mg Carbon per Cigarette 85% 89% 77% __________________________________________________________________________

TABLE 3 --------------------------------------------------------------------------- Effect with Addition of Calcium Carbonate Filler

Vapor Phase Side- T.P.M. Acrolein stream Description Yield Yield T.P.M. Carbon filled paper inner wrap Main- Main- Yield stream stream __________________________________________________________________________ Medium Activity Mill Waste Carbon; Paper contained 70% Carbon by weight; 72 mg Carbon per Cigarette, No CaCO.sub.3 77% 54% 54% Medium Activity Mill Waste Carbon; Paper Contained 50% Carbon by weight; 52 mg Carbon per Cigarette, 20 mg CaCO.sub.3 74% 61% 67% Medium Activity Mill Waste Carbon; Paper Contained 30% Carbon by weight; 31 mg Carbon per Cigarette, 41 mg CaCO.sub.3 74% 59% 72% Medium Activity Mill Waste Carbon; Paper Container 10% Carbon by weight; 10 mg Carbon per Cigarette, 62 mg CaCO.sub.3 tj 74% 60% 78% __________________________________________________________________________

TABLE 4 --------------------------------------------------------------------------- Effects with Calcium Carbonate and Burning Chemical

Vapor Phase Side T.P.M. Acrolein stream Description Yield Yield T.P.M. Carbon Filled Paper Inner Wrap Main- Main- Yield stream stream High Activity Wood carbon; Paper Container 70% Carbon by weight; Paper Treated with 2.0% Solution of Na.sub.2 CO.sub.3 ; 72 mg Carbon per Cigarette, No CaCO.sub.3 66% 44% 32% High Activity Wood Carbon; Paper Contained 50% Carbon by weight; Paper Treated with 1.5% Solution of Na.sub.2 CO.sub.3 ; 52 mg Carbon per Cigarette, 20 mg CaCO.sub.3 73% 19% 40% High Activity Wood Carbon; Paper Contained 30% Carbon by weight; Paper Treated with 1.0% Solution of Na.sub.2 CO.sub.3 ; 31 mg Carbon per Cigarette, 41 mg CaCO.sub.e 81% 13% 52% High Activity Wood Carbon; Paper Contained 10% Carbon by weight; Paper Treated with 0.5% Solution of Na.sub.2 CO.sub.3 ; 10 mg Carbon per Cigarette, 62 mg CaCO.sub.3 __________________________________________________________________________ 3 83% 56% 65%

similar beneficial results are obtained using carbon filled wrappers made from wood pulp both with and without the additon of calcium carbonate as the filler. Also, while all of the above cigarettes tested employed the carbon filled paper as an inner wrap under the conventional cigarette paper outer wrap for the tobacco column, other samples tested using the carbon filled paper as the sole wrapper produced similar reductions in the particulate and vapor phase yields of the cigarettes. Likewise, comparable results are obtained with carbon filled wrappers used as cigar wrap.

The effectiveness of the carbon filled wrapper of this invention for cigarettes and cigars is quite apparent from the foregoing illustrative examples. Many variations will become apparent to those skilled in the art, and the invention is not limited to the preferred embodiments shown. Various modifications and changes may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

What we claim is:

1. A smoking article of generally cylindrical form comprising a tobacco charge, an intermediate wrapper for said tobacco charge, said intermediate wrapper comprising a combustible porous paper sheet of cellulosic fibers and finely pulverized carbon particles, said carbon particles constituting at least 5 percent by weight of said sheet, and an outer wrapper for said tobacco charge selected from the group consisting of conventional cigarette paper and cigar wrap having good combustibility, said outer wrapper encircling and in contact with said intermediate wrapper, whereby upon burning of the smoking article a substantial decrease in the visible sidestream smoke emanating therefrom is manifested while also reducing the constituents in the mainstream smoke as compared to a smoking article of the same composition without said intermediate wrapper.

2. The smoking article of claim 1 in which said intermediate wrapper contains an alkaline earth metal carbonate, said carbonate constituting at least 5 percent by weight of the intermediate wrapper.

3. The smoking article of claim 2 in which the alkaline earth metal carbonate is calcium carbonate.

4. The smoking article of claim 1 in which the finely pulverized carbon used in said intermediate wrapper is medium to highly activated.

5. The smoking article of claim 1 in which the intermediate wrapper contains a flavorant absorbed by the carbon.

6. A composite wrapper adapted to encircle a tobacco charge in a smoking article, said wrapper constituting two superposed sheets, the first of said sheets comprising a porous paper sheet of combustible cellulosic fibers and finely pulverized carbon particles, said carbon particles constituting at least 5 percent by weight of the paper sheet, and the second of said sheets selected from group consisting of conventional cigarette paper and cigar wrap having good combustibility, whereby when the composite wrapper is employed as the wrapper for a tobacco charge, with the first said sheet positioned intermediate the tobacco charge and the second said sheet, a substantial decrease in the visible sidestream smoke emanating from the smoking article is manifested during burning while also reducing the constituents in the mainstream smoke as compared to a smoking article of the same composition without said intermediate wrapper.

7. The composite wrapper of claim 6 in which the first said sheet contains an alkaline earth metal carbonate, said carbonate constituting at least 5 percent by weight of the first said sheet.

8. The composite wrapper of claim 7 in which the alkaline earth metal carbonate is calcium carbonate.

9. The composite wrapper of claim 6 in which the finely pulverized carbon used in the first said sheet is medium to highly activated.

10. The smoking article of claim 6 in which the first said sheet contains a flavorant absorbed by the carbon.