US3217715A - Smoke filter and smoking devices formed therewith - Google Patents

Description

Nov. 16, 1965 R. M. BERGER ETAL 3,217,715

SMOKEH FILTER AND SMOKING DEVICES FORMED THEREWITH Filed May 24, 1965 Richard MBerger Raovis C. Sprouli ATTORNEYS nited States This application is a continuation-in-part of our earlier copending applications, Serial Numbers 306,343, 343,463, 351,161, and 392,014 filed September 3, 1963, February 10, 1964, March 11, 1964, and August 25, 1964, respectively, all of which earlier co-pending applications are noW abandoned.

This invention relates generally to smoke filters, and is particularly concerned with the provision of a smoke filter in which particles having both solid and gas phase filtration activity, specifically, activated carbon, are largely, if not solely, responsible for the filtering or smoke modification characteristics thereof. Further, the invention is concerned with smoking devices, particularly cigarettes, incorporating such filters.

Cigarette filters in widespread commercial use at the present time comprise, at least predominantly, filaments or fibers of a continuous nature. Specifically, in most all instances, the cigarette filters are formed from a processed paper structure or from so-called filamentary tow. Such filters are, in and of themselves, subject to certain limitations even though powdered additives can be incorporated therein.

The commercially acceptable filamentary smoke filters have the filaments or fibers thereof in a general longitudinal alignment, and as indicated, such fibrous filaments are of a continuous nature throughout the filter body. Accordingly, the manner in which the blending of desirable materials can be achieved are substantially limited. Moreover, with such filter structures, density properties, resistance to draw properties, filtration efficiency, hardness properties, and the surface areas of smoke controlling and/or modifying materials are only adjustable within relatively minimum ranges.

It has been previously been recognized that activated carbon possesses desirable properties for use in a smoke filter. However, the use of activated carbon has been generally limited because of the structure of the filters with which activated carbon has been previously associted. For example, with the conventional continuous tow or paper type smoke filter, activated carbon could, at best, take the form of a powdered additive, rather than a predominant structural material within the filter. Furthermore, it has been suggested that a cigarette filter be formed of two spaced tow sections having loose activated carbon particles disposed therebetween, with the filter sections and the intermediate carbon being maintained in position by a paper overwrap, or the like.

Dispersing of carbon particles in a filamentary tow does not sufficiently overcome the limitations on tow type filters, nor does it permit one to take full advantage of the activated carbon particles. Forming a filter with loose particles is not only expensive, but also the same results in sloppy handling and some inefficiency due to the inability to completely fill, on a commercial machine, the space between the two filter sections with the particles. As a result, the smoke can channel through the particle section without effective filtration therein.

Bearing in mind the foregoing, a primary object of the present invention is to provide a smoke filter wherein particles having both solid and gas phase activity such as activated carbon particles form a predominant structural part of the filter.

atent D ice More specifically, it is a primary object of the present invention to provide a smoke filter structure which consists essentially of activated carbon particles bonded together by a bonding agent to provide a stable filter structure suitable for use with a smoking device, e.g., as a cigarette filter, as a pipe filter, as a cigar filter, and/ or for other smoke filtering purposes, and capable of operating with increased filtration efiiciency.

In addition to the above it is a primary object of the present invention to provide such a smoke filter incorporating activated carbon particles wherein the bonding agent can be one of the presently commercially available comparatively inexpensive thermoplastic bonding agents, preferably a polyhydrocarbon, more particularly, polyethylene or polypropylene.

Aside from the above more basic and general objects of the present invention, there are certain specific objects hereof, including the following: (a) the provision of a smoke filter conforming with the preceding objects, which filter can be formed within wider density range limits, wider pressure drop limits, and with more diversified filtration properties than previously available filters; (b) the provision of such a smoke filter which is adapted to incorporate natural and/ or synthetic fibers therein where low density properties are desirable; (c) the provision of such a smoke filter which is adapted to incorporate smoke modifying filler materials such as puffed and/ or comminuted tobacco stocks and which is adapted to be chemically stabilized with alkalis and acid modifiers; (d) the provision of such a smoke filter which can be formed with more dense filler and/or strength providing materials, such as, for example, metal fibers; (e) the provision of such a smoke filter which can be made in accordance with high production techniques so as to be available for widespread use at relatively low cost; and (f) the provision of such a smoke filter which possesses increased ability to retain solids over presently available types of smoke filters.

It is another object hereof to provide an improved filter cigarette construction wherein a substantial quantity of a particulate filtering material is used in the filter sec tion, which quantity of material is stabilized in position and disposed adjacent the tobacco section. More particularly in this respect, it is an object hereof to provide a cigarette which includes successively, a tobacco section, a stabilized activated particulate filtering section and a rear fibrous filter section. Consistent with these objects, and in a more basic sense, it is a further object of the invention to use a generally solid activated particulate material filter, specifically, activated carbon, in combination with a plasticized fibrous filter in such a manner that the plasticizer does not seriously diminish the effectiveness of the activated particulate material. Plasticizers have apparently tended to adversely alfect prior activated carbontow segment filters so that the activated material lost some of is efiiciency. The cigarette construction made in accordance herewith appears to diminish this adverse effect.

The invention resides in the construction of a cigarette and the construction :of a filter element possessing structural properties consistent herewith. The invention will be better understood, and objects other than those set forth above will become apparent, after reading the following detailed description. To facilitate an understanding of the construction hereby, reference is made in the detailed description to the annexed drawings wherein:

FIGURE 1 is a longitudinal elevational view of one form of cigarette constructed in accordance herewith;

FIGURE 2 is an illustrative enlarged fragmental sectional view of a part of the filter section of the cigarette shown in FIGURE 1; v

FIGURE 3 is a longitudinal sectional view through a portion of the preferred form of cigarette constructed in accordance herewith.

Referring first to FIGURE 1, it will be noted that the so-called filter tip cigarette shown therein is generally designated by the numeral 10. This cigarette, as usual, includes a tobacco section 12 and a filter section 14. Both the tobacco section 12 and the filter section 14 are of rod-like shape, with the filter section 14 being shorter than the tobacco section 12, and with both sections being joined together by a conventional paper overwrap extending for the length of the cigarette 10. The overwrap, as customary, has opposed longitudinal edges overlapped and secured together by a suitable adhesive. While this cigarette is made in accordance with the invention, the preferred cigarette construction is presented in FIGURE 3 and discussed more fully below. For convenience, attention is now directed to the filter section 14, and thereafter consideration is given to the preferred cigarette construction hereof.

An enlarged portion of the filter section 14 is presented in the exemplary FIGURE 2. It is to be noted that the filtering or carbon particles are designated by the letter C and the binder material is designated by the letter B. The filtering particles C are tack welded together by discrete bonding means in the form of the bonding bridges B defined essentially alone by the thermoplastic bonding material, these bonding means B being predominantly individually smaller than the activated carbon particles C. The carbon particles (and any additives or fillers if in= eluded as mentioned hereinabove and hereinafter) cooperate through the bonding means to provide a continuous porous matrix with a labyrinth of smoke passages therethrough.

In the preceding discussion, it has been assumed that the filter section of the cigarette is formed solely by the particulate material filter element constructed according to this invention. This is entirely feasible, and such filter assures most desirable results. However, in certain instances, it is desired to utilize a fibrous type filter section in combination with a particulate material section whereby the user observes a conventional fibrous element at the filter tip end of the cigarette. This arrangement has previously created problems. At least one of the problems has allegedly been attributed to the fact that the activated materials (e.g., activated carbon) tend to absorb plasticizer which escapes from the fibrous filter section. For example, when the carbon is dispersed throughout a tow, there is a substantial quantity of plasticizer and the activated material is positioned to readily accept the plasticizer. When the carbon is sandwiched between plasticized tow sections, then there is no internal escape route for the plasticizer and again the plasticizer apparently tends to have some adverse eifect on the activated material.

In accordance herewith, and as shown in FIGURE 3,

a particulate filter section 14' is disposed in the preferred form of cigarette ltl' hereof between the tobacco section 12' and a fibrous filter section 14''. The fibrous section 114" is a plasticized tow sectione.g., a conventional plasticized cellulose acetate tow segment. The filter sec tion 14 occupies a substantial portion of the overall filter unit, preferably at least one-half of the total length of the filter unit, and for most desired results, at least twothirds of such length. This arrangement which is permitted by having a stable particulate filter section 14' (preferably corresponding exactly to filter section 114 of FIGURES 1 and 2), reduces the amount of plasticized tow required in a combined activated particle-tow section unit, thus reducing adverse plasticizer effects.

In accordance with the invention, activated carbon particles are integrally mixed with a bonding agent and the bonding agent and carbon particles are formed into a stable filter structure. The bonding agent can comprise any thermoplastic material, such as polyhydrocarbons having from 2-10 carbon atoms, preferably polyolefins, e.g., polyethylene and polypropylene, other thermoplastics such as vinyl acetate, other vinyl homopolymers and copolymers, plasticized cellulose acetate, Artrite (a thermoplastic polyester resin), Escorex (a fine powdered petroleum hydrocarbon resin), and combinations of any of the above, all of these materials being of the type which are effective to provide bonding at temperatures in excess of that of the normal smoke temperature passing through the plug.

However, the best results are obtained when the bonding agent is a polyolefin or, more specifically, polyethylene, polypropylene, or combinations thereof.

Consistent herewith, activated carbon particles are initially mixed with the bonding agent particles, and the particles providing the bonding agent are so selected that they have a size no greater than equal to, and preferably substantially less than, the particle size of the activated carbon particles. Preferably, the activated carbon particles have a particle size of between 10 and 200 mesh and the binder has a particle size of less than 100, preferably less than 50, microns. The mixing is carried out in any suitable manner, but with the activated carbon particles present in a relative amount of between 50 percent and 95 percent by weight, preferably 70 or even to 93 /2 percent by weight, and the particles of the bonding agent present in a relative amount of between 5 and 50 percent by weight, preferably 6 /2 to 30 percent by weight. After the carbon and bonding particles are integrally mixed, the mixture is formed into a stable rod-like structure with heat being applied to soften the bonding agent whereby it adheres to the adjacent carbon particles and serves as a binder therebetween, this procedure inherently resulting in the multiplicity of bonding bridges B predominantly individually smaller than the carbon particles C.

It may be desirable, as indicated above, to incorporate a filler material in the filter structure, which filler material serves as a smoke modifier. For example, where density characteristics are important, natural or synthetic fibers may form part of the filter structure. Alternatively, puifed and/ or comminuted tobacco stocks and stems may be included within the filter structure together with alkalies and acid modifiers which chemically stabilize the ultimate unit. Where porosity and even strength properties are of major consideration, then metal fibers can be included within the filter unit hereof. Additionally, the filler material can comprise fibrous carbon, as, for example, where porosity is of particular significance. Orzan, a sulfonate polymer, possessing good dispersing and chelating properties, has been found to be a suitable additive from the standpoint of hardness and sorptivity. Sucrose (table sugar) and methyl cellulose serve as suitable additives to improve hardness and sorptivity. N-vinyl- 5-methyl-2-oxazolidinone (Delvex) is a useful additive because of its film forming and chelating properties, and when used, the resultant filter has improved uniformity as well as good sorptivity and hardness.

While it is known that various constituents of tobacco smoke are harmful, it is not known with any degree of certainty which are the most harmful. It is believed that certain additives eliminate certain of these constituents and it is therefore within the scope of this invention to add a minor amount of an additive to enhance the operating or taste characteristics of the filter unit. Accordingly, it has been found that certain natural and synthetic resins as well as certain inorganic materials can be employed for control purposes. Examples of control additives include powdered resins such as polyvinyl acetate, polycarbonates, polyarnides of the nylon types, for example, nylon 6, nylon 6/6 and nylon 6/10, modified cellulose resins, for example, cellulose acetate, and dimethyl cellulose, powdered natural gums, carbohydrates, for example, the various sugars, powdered calcium carbonate and fiberized wood pulp.

It should be understood from the preceding paragraph,

that the term filler material, as used herein, refers to a material other than those which provide the basic structural components of the ultimate smoke filter constructed in accordance herewith. Activated carbon particles and the bonding agent or binder are the basic structural materials, and the filler material is auxiliary thereto. Yet, the filler material is not necessarily an inactive constituent of the filter, but instead, can be an active material, as for example, a chemical or chemical compound yielding desirable taste properties or the like. In this latter regard, it will be appreciated that various additives can be utilized in the filter hereof to achieve a given ultimate effect. Moreover, it is to be understood that while various filler materials have been set forth individually above, such filler materials need not be used individually in the ultimate filter. Instead, they can be used in selected combinations or individually and with or without so-called additives.

If a filler material or additive is utilized, then preferably the same is integrally mixed with the basic structural materials during the initial mixing operation referred to above. However, it is within the scope of the invention to treat a structure formed in accordance herewith with additives or the like after its formation into a stable structure.

Regardless of the manner in which a filler material or additive is incorporated in the ultimate unit, the same forms a minor part by weight of the final unit. Accordingly, the weight ranges set forth above for the basic structural materials, namely, the activated carbon particles and the bonding agent are applicable even in cases where filler materials and additives are utilized.

Bearing in mind the fact that filler materials and/or additives can be incorporated in the unit, and preferably mixed with the basic structural ingredients initially, consideration can be given to the mixing and forming operations that can be utilized in making a filter embodying the invention.

The particular method of forming a filter constructed in accordance herewith can vary. For example, the filter can be formed by any one of the following processes.

Process 1 .-A weighed amount of activated carbon particles and a weighed amount of dry bonding agent particles are fed to a conventional blending machine of the type incorporating a spiral agitator and adapted to carry out a dough mixing type operation. Such machines, as well known, can easily provide a simultaneous mixing and kneading actioni.e., the respective particles of activated carbon and of the bonding agent are worked together while being mixed. After the initial blending operation of the particles, performed by the blending machine, the mixture is pressed or passed through a heated tube or confined area so that the bonding agent particles are softened and adhered to adjacent activated carbon particles and/or filler particles, if a filler is used. The ultimate result of this process is a unitary rod-like structure which is formed as an extrusion.

Process 2.As an alternative to Process 1, the activated carbon particles and bonding agent particles can be blended by mixing the same together and feeding the mixture through a venturi throat type arrangement to a collecting and forming area. In the collecting and forming area, the mixture is shaped, and steam is passed therethrough to soften the bonding agent particles and cause adherence thereof to adjacent activated carbon particles and/ or filler material. A feeding, forming and heating process of this type, and equipment suitable for carrying out such process, is disclosed in co-pending United States patent application Serial No. 285,293, filed June 4, 1963, entitled Woven Type Fiberous Bodies and assigned to the assignee of the present application.

Process 3.As a further alternative process, the mixture can be formed in a blending machine as described in Process 1, or thorough mixing in a hammermill. Thereafter, the mixture can be fed onto an accumulating screen or belt and formed into a rod shape. The rod shape is heated during the formation thereof to provide the ultimately stable filter structure with the bonding agent particles and/or filler material together. A more detailed discussion of a process of this type, and of the equipment used in carrying out such process is found in co-pending United States patent application Serial No. 230,981, filed October 16, 1962, entitled Fiber Filter, and also assigned to the same assignee of the present application, this application further disclosing in detail a procedure for the production of tack welds between the constituents of the filter plug, i.e., small bonding bridges.

Process 4.--As a still further alternative, the mixture can be formed in a blending machine as described in Process 1. The mixture is then poured into a vertically disposed filter shaped cavity (bore in a block). The cavity with the mixture therein is then heated slightly above the melt temperature of the binder being used. The cavity and mixture are then allowed to cool, and the formed rod is dropped or punched out by overturning the cavity.

Where all of the basic structured ingredients and filler materials or additives, if used, are available in the dry state, and are readily susceptible to air mixing, then Process 2 and Process 3 referred to above are preferred. However, Processes 1 and 4 are completely satisfactory, and since the techniques thereof are conventional, it may be found particularly desirable to use such processes under given circumstances.

It has been found that for obtaining close control of product quality, a portion of the binder can be co-blended as an emulsion in a liquid carrier, such as, for example, water. With the use of a carrier, initial mixing is facilitated, particularly in Process 1, and moreover, it is possible to obtain an almost completely uniform heterogeneous mixture of the basic structural materials.

Regardless of the particular forming process utilized, the structural unit resulting from the process can be subject to further curing for desired final stability. Final curing of the filter to the desired hardness and pressure drop can be performed in various ways with the application of heat and subsequent cooling being the primary factors. One suitable final curing sequence is disclosed in the aforesaid application Serial Number 230,981.

The following examples illustrate the manner in which the filters hereof can be provided and efliciently utilized.

EXAMPLE 1 Activated charcoal particles passing an mesh screen were integrally mixed according to Process 1 above with finely divided polyethylene particles having a size of approximately 50 microns. The ultimate mixture contained 75 percent by weight of carbon particles and 25 percent by weight of polyethylene particles.

(A) The mixture was extruded by hand through a heated orifice of 8 mm. diameter which orifice was heated to a temperature of approximately 210 F. The extrusion resulted in the formation of a filter rod, and a 17 mm. long segment of such rod was utilized as a smoke filter tip. Testing of this tip showed that the same had a pressure drop across its length of 2.35 inches of water. Furthermore, testing of this filter rod showed that the same gave complete removal of acetaldehyde and isoprene. (It will be appreciated that acetaldehyde and isoprene are undesirable constituents of smoke tars, i.e., the constituents which give a biting effect and which prevent a socalled smooth smoke.)

(B) The mixture was also formed according to Process 4 above using the same sizes and temperatures as prescribed in Example 1(A). The results were the same.

EXAMPLE 2 A filter rod was formed by the same procedure as set forth in Example 1(B). However, the mixture utilized contained 5 percent by Weight of polyethylene particles and 95 percent by weight of carbon. The pressure drop along a filter rod of the same dimensions as in Example 1, but formed in accordance with this example, was 1.4 inches of water. Moreover, the total solid retention percent of such filter rod was 48 percent.

EXAMPLE 3 A filter was formed by the same procedure as set forth in Example 1(B) but the mixture utilized contained 10 percent by weight of polyethylene particles and 90 percent by weight of carbon particles. With a filter rod of the same dimensions as used in Example 1, but formed consistent with this example, the pressure drop was 2.3 inches of water, and the total solid retention percent was 58 percent.

EXAMPLE 4- A filter was formed by the same procedure as set forth in Example 1(B), but the mixture utilized contained 15 percent by weight of polyethylene particles and 85 percent by weight of carbon particles. A filter rod of the same dimensions as set forth in Example 1, but formed consistent with the pressure drop was 2.35 inches of water and the total solid retention percent was 53.5 percent.

EXAMPLE 5 A filter is formed by the same procedure as set forth in Example 1(5), but the mixture utilized contains 6 /2 percent by weight of polyethylene particles and 93 /2 percent by weight of carbon particles. A filter rod of the same dimensions as set forth in Example 1, but formed consistent with this example, has a pressure drop of approximately 210 inches of water and a total solids retention percent of over 50 percent.

The substantial efficiency of the filter formed in accordance with the invention as compared to the efficiency of now commercially available filter rods, can be appreciated by comparison of relative total solids retention percents. Using a conventional cellulose acetate smoke filter formed from a continuous filamentary tow, but having the same dimensions as described in the preceding examples, would give a filter having solids retention percentages between 35 percent and 45 percent. On the other hand, with the invention, even in accordance with Example 2, there was an increase of at least 3 percent, and with Example 3, there was an increase in eificiency of over 13 percent from the solids retention standpoint.

The term pressure drop as used above, refers to a pressure drop measurement across a filter rod under test. For this purpose, as conventional, a smoke stream through the filter is created having a flow rate of 17 /2 cubic centimeters per second. Then, through the use of a conventional U-tube containing water, the difference in pressure at the inlet end of the filter and at the outlet end of the filter is measured in terms of inches of water.

To ascertain solids retention percent, as also conventional, a Cambridge filter apparatus is utilized. The filter under test, in this instance, is placed in series relation with the standard Cambridge filter (the Cambridge filter being accepted in the industry as a standard having 100 percent solids retention). Then, a cigarette is puffed by the apparatus with a 35 mm. puff over a two-second interval and at the rate of one puff per minute. The material collected on the filter undergoing test and the material collected on the Cambridge filter together yield the total solids. The material or solids collected on the filter undergoing test (as determined by a conventional weight comparison) is then compared against the total, and the solids retention percent of the filter under test is calculated. This testing method is conventional, as indicated, and accordingly, further discussion appears unnecessary.

Generally, the same results are achieved, as prescribed above, by a filter formed pursuant to the following examples.

EXAMPLE 6 Activated carbon particles are integrally mixed with polyethylene particles to yield a mixture containing 25 percent by weight of polyethylene and percent by weight of activated carbon particles. Such mixture is fed to the apparatus as disclosed in aforesaid application Serial No. 285,293. Steam is fed to the mixed mass passing through the forming section of the apparatus disclosed in such application, and the ultimate rod resulting therefrom. Testing of the ultimate rod resulting therefrom indicated that the activated carbon is still efficient even with the increased relative amount of polyethylene.

EXAMPLE 7 The steps set forth in Example 1(8) are performed in the same manner and in the same sequence as there stated. However, the mixture contains 75 percent by weight of carbon particles, 15 percent by weight of polyethylene particles, and 10 percent by weight of comminuted wood pulp.

EXAMPLE 8 Filter rods were formed by the same procedure as set forth in Example 1(3). However, the mixture employed contained percent by weight of activated carbon, 10 percent by weight of polyethylene particles and 5 percent by weight of one of the following materials: (a) polyvinyl acetate particles; (b) polycarbonate polymer; (c) powdered calcium carbonate; ((1) fiberized wood pulp; (e) polycaprolactam, nylon 6; (f) hexamethylene adipimide, nylon 6/6; and (g) sucrose. Similarly, filter rods have been prepared having the following compositions: (a) 60 percent by weight activated carbon, 25 percent by weight polyethylene particles and 15 percent by weight polyvinyl acetate particles; (b) 70 percent by weight activated carbon, 20 percent by weight polyethylene and 10 percent by weight powdered cellulose acetate, (c) 60 percent by weight activated carbon, 10 percent by weight polyethylene, 15 percent by weight powdered cellulose acetate and 15 percent by weight finely divided polyvinyl acetate; and (d) 70 percent by weight activated carbon, 10 percent by weight polyethylene, 10 percent by weight sodium carbonate and 10 percent by weight nylon 6. Smoke filter tips cut from all of the above rods had properties similar to those tips of the foregoing examples.

The resultant rods formed according to this example appeared satisfactory, although the characteristics in each mstance were not the best obtained in every respect.

EXAMPLE 10 Example 1(B) was repeated but using for several rods between 89 and 91 percent activated carbon particles passing a 20 mesh screen and retained on a 50 mesh screen and 9 to 11 percent polyethylene having a particle size of approximately 50 microns. Segments of the rod 10 mm. in length had an average pressure drop of 2.5

centimeters of water. The smoke constituents were ret ained therein, on average as follows:

Smoke component: Percent retention Tar 38 Phenol 31 Nicotine 22 HCN 84 Acrolein 93 Formaldehyde 84 EXAMPLES 11-17 Example 11 is repeated but the polyethylene is replaced by the binders shown below. The results in each instance are satisfactory, although the polyethylene produces the preferred product.

Example: Binder l1 Polypropylene. 12 Escorez. 13 Plasticized cellulose acetate. 14 Vinyl acetate. 15 Vinyl h'omopolymer. 16 Vinyl copolymer. 17 Artrite.

It appears unnecessary to give further examples in this specification since the invention can be more than adequately understood from the preceding discussion and even the first example given.

What is claimed is:

1. In a smoking means of the type wherein a quantity of tobacco is ignited and smoke is drawn therefrom by a smoker, the improvement which comprises a filter means interposed between the smoker and the tobacco, said filter means comprising an elongated plug disposed in said smoking means such that smoke passes therethrough to reach the smoker, said plug consisting essentially of the following constituents:

(a) from in excess of 50 to approximately 95 percent by weight of activated carbon particles, said activated carbon particles having a maximum dimension which is a small fraction of the minimum dimension of said plug; and

(b) from at least to approximately 50 percent by weight of a thermoplastic resin, said thermoplastic resin being operative essentially alone to effect bonding bridges between juxtaposed constituents through heating and subsequent cooling, with the temperature of the resin at which th bonding is effective exceeding that of the normal temperatures of smoke passing through said plug;

said plug further being characterized by:

(1) said activated carbon particles serving as the major active component of said plug and being active to remove both solid and gas phase constituents from smoke passing through said plug during utilization of said smoking means;

(2) said thermoplastic resin essentially alone serving as a binder between said constituents and defining a multiplicity of discrete bonding means predominantly individually smaller than said activated carbon particles;

(3) said constituents cooperating through said oonding means to give structural continuity to said plug as a self-sustaining, substantially particulate stable body in the form of a continuous porous matrix with the discrete bonding means and constituents providing a labyrinth of smoke passages therethrough;

(4) said constituents being comingled in any crosssection of said body and with said activated carbon particles randomly arranged in said plug such that a multiplicity of said activated carbon particles are present in substantially any cross section of said body; and

(5) said body deriving its stability substantially only from said cooperation between said bonding means and said constituents.

2. The improvement according to claim 1 wherein said smoking device is a cigarette comprising a tobacco section and a filter section, said filter section including said plug and a fibrous filter body containing a substantial amount of plasticized fibrous material, said plug being interposed between said tobacco section and said fibrous filter body and being disposed adjacent and in end to end contact with said tobacco section.

3. The improvement according to claim 1 wherein said constituents further include in minor part by weight a smoke-modifying additive.

4. The improvement according to claim 1 wherein said thermosplastic resin is polyethylene.

5. The improvement according to claim 1 wherein said activated carbon particles are present in said plug in a relative amount of between about 93%. percent and percent by weight and said thermoplastic resin is present. in said plug in a relative amount of between about 6% percent and 30 percent by weight.

References Cited by the Examiner UNITED STATES PATENTS 665,375 1/1901 Trimble 131-208 X 1,966,553 7/1934 Kropp. 2,373,296 4/ 1945 Donnelly 131208 3,015,367 1/1962 Smith et a1. 183-4 3,039,908 6/1962 Parmele 131-208 3,091,550 5/1963 Doying 117-76 3,101,723 8/1963 Seligman et al. 131-208 FOREIGN PATENTS 1,110,463 10/ 1955 France.

SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner.

Claims (1)

1. IN A SMOKING MEANS OF THE TYPE WHEREIN A QUANTITY OF TOBACCO IS IGNITED AND SMOKE IS DRAWN THEREFROM BY A SMOKER, THE IMPROVEMENT WHICH COMPRISES A FILTER MEANS INTERPOSED BETWEEN THE SMOKER AND THE TOBACCO, SAID FILTER MEANS COMPRISING AN ELONGATED PLUG DISPOSED IN SAID SMOKING MEANS SUCH THAT SMOKE PASSES THERETHROUGH TO REACH THE SMOKER, SAID PLUG CONSISTING ESSENTIALLY OF THE FOLLOWING CONSTITUENTS: (A) FROM IN EXCESS OF 50 TO APPROXIMATELY 95 PERCENT BY WEIGHT OF ACTIVATED CARBON PARTICLES, SAID ACTIVATED CARBON PARTICLES HAVING A MAXIMUM DIMENSION WHICH IS A SMALL FRACTION OF THE MINIMUM DIMENSION OF SAID PLUG; AND (B) FROM AT LEAST 5 TO APPROXIMATELY 50 PERCENT BY WEIGHT OF A THERMOPLASTIC RESIN, SAID THERMOPLASTIC RESIN BEING OPERATIVE ESSETIALLYL ALONE TO EFFECT BONDING BRIDGES BETWEEN JUXTAPOSED CONSTITUENTS THROUGH HEATING AND SUBSEQUENT COOLING, WITH THE TEMPERATURE OF THE RESIN AT WHICH THE BONDING IS EFFECTIVE EXCEEDING THAT OF THE NORMAL TEMPERATURE OF SMOKE PASSING THROUGH SAID PLUG; SAID PLUG FURTHER BEING CHARACTERIZED BY: (1) SAID ACTIVATED CARBON PARTICLES SERVING AS THE MAJOR ACTIVE COMPONENT OF SAID PLUG AND BEING ACTIVE TO REMOVE BOTH SOLID AND GAS PHASE CONSTITUENTS FROM SMOKE PASSING THROUGH SAID PLUG DURING UTILIZATION OF SAID SMOKING MEANS; (2) SAID THERMOPLASTIC RESIN ESSENTIALLY ALONE SERV ING AS A BINDER BETWEEN SAID CONSTITUENTS AND DEFINING A MULTIPLICITY OF DISCRETEBONDING MEANS PREDOMINANTLY INDIVIDUALLY SMALLER THAN SAID ACTIVATED CARBON PARTICLES; (3) SAID CONSTITUENTS COOPERATING THROUGH SAID BONDING MEANS TO GIVE STRUCTURAL CONTINUITY TO SAID PLUG AS A SELF-SUSTAINING, SUBSTANTIALLY PARTICULATE STABLE BODY IN THE FORM OF A CONTINUOUS POROUS MATRIX WITH THE DISCRETE BONDING MEANS AND CONSTITUENTS PROVIDING A LABYRINTH OF SMOKE PASSAGE THERETHROUGH; (4) SAID CONSTITUENTS BEING COMINGLED IN ANY CROSSSECTION OF SAID BODY AND WITH SAID ACTIVATED CARBON PARTICLES RANDOMLY ARRANGED IN SAID PLUG SUCH THAT A MULTIPLICITY OF SAID ACTIVATED CARBON PARTICLES ARE PRESENT IN SUBSTANTIALLY ANY CROSSSECTION OF SAID BODY; AND (5) SAID BODY DERIVING IUTS STABILITY SUBSTANTIALLY ONLY FROM SAID COOPERATION BETWEEN SAID BONDING MEANS AND SAID CONSTITUENTS.

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