Flavor-releasing Smoking Article And Method Of Making The Same

Abstract

This disclosure relates to a flavor-releasing smoking article and to methods of making the same. More particularly, the disclosure relates to a smoking article embodying a filter for tobacco smoke, which filter contains, as an essential filtering element, a solid polymer having controlled pore size and containing therein a flavor for incorporation in tobacco smoke, said polymer being capable of removing undesirable elements from tobacco smoke while imparting desirable flavor thereto.

Description

The polymeric material which is employed in accordance with the present invention comprises a normally solid, finely divided, microporous, organic polymer as hereinafter defined, e.g. a microporous copolymer of a divinyl aromatic hydrocarbon and a monovinyl aromatic hydrocarbon, such as a copolymer of divinylbenzene and styrene, or a copolymer of divinylbenzene, ethylvinylbenzene and styrene, or a homopolymer of ethylene glycol dimethacrylate.

With the increasing effectiveness of filter materials for the removal of undesired elements of tobacco smoke a different problem has arisen in connection with tobacco smoke filtration. Many of the more effective filter materials have been found to remove desirable flavoring materials, such as menthol, from the tobacco smoke.

Another problem which has long been present in connection with smoking products resides in the fact that it is difficult to incorporate smoke flavoring agents in smoking products in a manner whereby the tobacco products can be stored for relatively long periods of time without losing the flavorants due to volatilization and yet in such a manner that the flavorants will be released when the smoking product is smoked.

In addition, materials have been suggested for filtration of tobacco smoke. Among some of the materials which have been employed as tobacco smoke filters are certain open-pore sponge or foam materials, and porous activated adsorbent materials, such as charcoals. Such materials have been used by themselves and in conjunction with papers, fibers, and other known filter materials. Though such materials have been found to have some effectiveness in removing tobacco smoke components, their effectiveness in general, has been with regard to the removal of the less volatile components of the smoke. Such materials have been found relatively indiscriminate and/or ineffective with regard to the removal of undesirable smoke ingredients generally.

The so-called open-cell foams, i.e., foams having an open-pore structure through which smoke may be drawn for filtration, have been found to possess variable pore sizes and a large distribution of pore sizes. As a consequence, such foams have imparted variable resistance-to-draw (RTD) and, thus, variable quality to the tobacco products in which they have been employed. In addition, such foams are often so open in structure that an inconveniently long filter section must be employed to effect significant particle removal. Moreover, so-called open-cell foams have some pores which are blocked so that they form useless dead space which does not interconnect with both ends of the filter.

Activated porous adsorbents, in general, also have been found to have many disadvantages. For example, in addition to their function as gas phase removers, they also have been employed in the filter to carry flavorants or other additives to be transferred to the smoke stream. When such materials have pores of varying sizes, some of the additive is wasted in the small pores which retain it too firmly to permit transfer to the smoke.

In contrast, when the pores of such adsorbents having uniform but very small pore size, such as the zeolite type materials are used, they do not take up certain additive molecules. For example, the few zeolite type materials which have room for additives, are, due to their strong hydrophilic properties, susceptible to premature displacement of the additive by tobacco moisture.

We have discovered a novel filter material which provides selective filtration and excellent control of the RTD of filters in which they are employed and which provides for the proper retention and delivery to the tobacco smoke of desirable volatile additives and flavorants such as menthol and anethole.

The present invention relates to a flavor-releasing smoking article and to methods of making the same. More particularly, the present invention relates to a smoking article embodying a filter for tobacco smoke, which filter contains, as an essential filtering element, a solid polymer having controlled pore size and containing therein a flavor for incorporation in tobacco smoke, said polymer being capable of removing undesirable elements from tobacco smoke while imparting desirable flavor thereto.

The present invention involves use in filters for tobacco smoke of solid polymers or resins of controlled pore size.

A filter comprising a polymeric material of controlled pore size, in accordance with the present invention can be chosen to accommodate and retain undesirable smoke components and at the same time to permit ready egress to small molecules of the volatile and flavorful components of smoke such as isoprene, acetaldehyde, acetone, and the like. The polymers or resins employed in accordance with the present invention are, in general, not strongly hydrophilic, so that the problem of displacement by or interference by moisture is not encountered as it is with the zeolites. The resins can, in addition, be chosen to have a strongly nonpolar aromatic character and thus can be chosen to provide an affinity for aromatic and polynuclear hydrocarbons and not for polar alcohols and the like.

The polymeric material which is employed in accordance with the present invention comprises a normally solid, finely divided, microporous, organic polymer as hereinafter defined, e.g. a microporous copolymer of a divinyl aromatic hydrocarbon and a monovinyl aromatic hydrocarbon, such as a copolymer of divinylbenzene and styrene, a copolymer of divinylbenzene and ethylbenzene or a polymer of divinylbenzene, ethylvinylbenzene and styrene, or a homopolymer of ethylene glycol dimethacrylate.

The microporous resinous polymer to be employed can be any rigid, cross-linked, insoluble organic polymer having a plurality of interconnecting pores therein, a surface area of at least 50 square meters per gram, a high porosity and is in the form of particles of sizes between about 5 and 850 microns. Best results are obtained when the polymer is used in the form of particles having a relatively narrow range of sizes or of substantially the same size, preferably within the range of 80 to 180 microns.

The cross-linking must be sufficient to maintain a rigid structure, and to inhibit or prevent appreciable shrinking upon drying, which decreases the porosity of the polymer. The amount of cross-linking necessary is dependent in part both upon the cross-linking agent and the monomer being polymerized and the manner in which the polymer is made. In the instance where the monomer is difunctional it can act as a cross-linking agent. For example, a polymer made of divinylbenzene alone will be highly cross-linked, as will a polymer prepared exclusively from ethylene glycol dimethacrylate. Either of these polyfunctional monomers can be used to make cross-linked homopolymers of copolymers with one another, or to cross-link polymers made from mixtures of such divinyl monomers and other copolymerizable vinyl monomers.

Polymers useful in the process of the invention are: the homopolymers of divinylbenzene, divinyltoluene, divinylxylene, or ethylene glycol dimethacrylate; copolymers of any two or more of such divinyl monomers; or copolymers of at least 20 percent by weight of at least one such divinyl monomer and up to 80 percent by weight of a monovinyl aromatic hydrocarbon such as styrene, ethylvinylbenzene, vinyltoluene, vinylxylene, isopropylstyrene, t-butylstyrene, or sec-butylstyrene. Mixtures of two or more polyvinyl monomers such as for example, divinyl benzene, driving toluene, divinylxylene, diallyl phthalate, diallyl fumarate, or ethylene glycol dimethacrylate, can also be used. These latter difunctional monomers can be used alone, or with the monovinyl aromatic hydrocarbon monomers, to give cross-linked homopolymers and copolymers, respectively. Other nonaromatic vinyl monomers useful in forming copolymers with the aforementioned divinyl monomers are: methyl methacrylate, ethylene glycol monomethacrylate, ethyl acrylate, propyl acrylate, butylacrylate, vinyl acetate, vinyl propionate and the like. Copolymers prepared from monomers such as N-vinyl pyrrolidone, 4-vinyl pyridine N-vinyl morpholinone and N-vinyl oxazolidinone and the difunctional monomers such as divinyl benzene, or ethylene glycol dimethacrylate, and/or one or more monovinyl aromatic hydrocarbons can also be used in the proportions hereinbefore stated.

The microporous copolymers can be prepared by polymerizing the monomers in admixture with from about 0.5 to 20 times their weight of a solvent that is miscible with the monomers, but exhibits or has limited solubility for the polymer.

The solvent for the monomer or diluent must be nonpolymerizable with the monomers, and only swell, but not dissolve the polymer. The size of the pores in the polymer and its density is dependent in part upon the kind of solvent employed, e.g. whether an aromatic hydrocarbon such as toluene or ethylbenzene, or an aliphatic compound such as heptane or an alcohol such isoamyl alcohol, or a mixture of such compounds is employed. The polymerization can be carried out in mass or in aqueous suspension, at temperatures between 50.degree. and 120.degree. C. and at atmospheric, subatmospheric, or superatmospheric pressure.

In preparing the polymer, a reaction vessel is charged with suitable amounts of styrene, ethylvinylbenzene and divinylbenzene, or a desired amount of other suitable monomers or monomer, and an inert liquid such as diethylbenzene, octane, or isoamyl alcohol, or a mixture of diethyl benzene and isoamyl alcohol. A catalyst, e.g. 0.01 to 1 percent by weight of benzoyl peroxide, based on the total weight of the monomer is added. The vessel is purged with nitrogen to remove air, then sealed. The mixture is heated and stirred at temperatures between 50.degree. and 120.degree. C. until the monomer is polymerized. The vessel is opened and the porous polymer removed.

Other methods for making porous cross-linked styrene polymers are described in British Pat. No. 980,299, wherein microporous hydrocarbon polymers are prepared by heating a mixture of a thermoplastic hydrocarbon polymer such as polystyrene and a water-soluble anionic surfactant to a temperature sufficient to render the polymer and surfactant mutually soluble. The resulting homogeneous mixture is cooled, after which the surfactant phase is removed by extraction with water or other liquid in which the surfactant is soluble and the polymer is not. A peroxide cross-linking agent may be included in the mixture to cross-link the polymer before cooling and extraction of the surfactant.

U.S. Pat. No. 2,537,951 involves the manufacture of porous cross-linked copolymers of vinyl aromatic compounds, such as a mixture of styrene, ethylvinylbenzene and divinylbenzene, which may be employed in accordance with the present invention.

The various cross-linked insoluble popcorn or proliferous polymers such as are described by Kondakow (J. prakt Chim. [2] 64, p. 109 (1961)); carothers (J.A.C.S. 53, D. 4203 (1931)); Staudinger et al. (Berichte 68 p. 1618 (1935)); Britton (U.S. Pat. No. 2,341,175 of Feb. 8, 1944); Karasch et al. (Ind. Eng. Chem. 39, p. 830 (1947)); and mentioned in U.S. Pat. Nos. 2,597,437-8-9 and 2,597,493, can also be used, as well as the microporous polymers used for the preparation ion-exchange resins described in British Pat. No. 889,304. Such cross-linked insoluble polymers should preferably have a surface area of at least 50 square meters per gram, and be in the form of particles of sizes between about 5 and 500 microns.

The following examples are illustrative.

Example 1

A charge of 900 ml. of a liquid consisting of a mixture of 55 percent by weight of divinylbenzene, 43 percent by weight of ethylvinylbenzene and 2 percent by weight of diethylbenzene, and 600 ml. of diethylbenzene as solvent and reaction medium, together with 5.5 grams of azobisisobutyronitrile as catalyst, was suspended in 1500 ml. of water containing 100 grams of finely divided basic magnesium carbonate (3MgCO.sub.3.sup. . Mg(OH).sub. 2.sup. . 3H.sub.2 0), as suspending agent, and 0.1 gram of potassium dichromate. The mixture was stirred and heated under time and temperature conditions as follows: 4 hours at 50.degree. C., 4 hours at 55.degree. C., and 16 hours at 65.degree. C., to polymerize the monomers in the mixture. Thereafter, concentrated hydrochloric acid was added to the mixture in the amount sufficient to neutralize the basic magnesium carbonate and bring the aqueous liquid to a pH value between 3 and 4. The polymer was recovered by filtering and was washed with water, then with acetone, and finally with diethylbenzene. The product was in the form of small particles having a large surface area and a high porosity. The product was separated into fractions having particles of sizes between 119-165 microns; 150-196 microns; 173-238 microns and 192-288 microns. The product having particles of sizes between 119 and 165 microns was separated from the main portion of the product and was washed with acetone, after which the washed product was dried by heating it at a temperature between 70.degree. and 80.degree. C. in vacuum oven at an absolute pressure of less than 1 millimeter, for a period of 16 hours. The surface area of the polymer was 700 square meters per gram.

Example 2

A copolymer of 21.8 grams of styrene, 10 grams of divinylbenzene and 7.8 grams of ethylvinylbenzene, was prepared by polymerizing the monomers in an aqueous suspension containing basic magnesium carbonate as suspending agent, and a mixture of diethylbenzene and isoamyl alcohol, as diluent, employing procedure similar to that employed in Example 1.

Example 3

A charge of 750 ml. of ethylene glycol dimethacrylate together with 750 ml. of methyl isobutyl ketone, and 5.5 grams of azobisisobutyronitrile as catalyst, were added to a 5 liter three-neck glass reaction vessel equipped with a reflux condenser and stirrer and containing 1500 ml. of water having dispersed therein 50 grams of basis magnesium carbonate, 0.1 gram of K.sub.2 Cr.sub.2 O.sub.7 and 12 grams of methyl cellulose. The mixture was stirred and heated at a temperature of 55.degree. C. for a period of 5 hours, then was stirred and maintained at 65.degree. C. for 20 hours longer. The polymer was recovered employing procedure similar to that employed in Example 1, washed with water and dried.

Example 4

A polymer of about 46.75 percent by weight of divinylbenzene, 38.25 percent by weight ethylvinylbenzene and 15 percent by weight N-vinylpyrrolidone was prepared employing procedure similar to that used in Example 1 from a mixture of 75 parts by volume of commercial divinylbenzene consisting of about 55 percent divinylbenzene and about 45 percent ethylvinylbenzene and and 25 parts by volume of N-vinylpyrrolidone and with diethylbenzene as the diluent. The product was an insoluble microporous polymer.

Example 5

A copolymer of about 51.15 percent by weight divinylbenzene, 41.85 percent by weight diethylbenzene and 7 percent by weight N-vinyl pyrrolidone was made by procedure similar to that used in Example 4.

As set forth later in this specification, the polymers used in the present invention are preferably ethylvinylbenzene-divinylbenzene polymers in spherelike particles of 80.times.100 mesh size (which are marketed as "Porapak Q" polymers). These polymers have a pore size of 10.sup.4 Angstrom units (1 micron), a total surface area of 50 meters.sup.2 /milliliter and a bulk density of 0.5 gram/ml.

A filter containing 50 mg. of "Porapak Q" polymer was found to remove approximately 15 percent of the total gas phase. It was found to selectively remove about 87 percent of the limonene and certain aromatics and, to a lesser degree, to selectively remove benzene and toluene.

By contrast polymers of 45 Angstrom pore size sample were found to be less effective, removing a small percentage of the total gas phase and exhibiting less selectivity for any of the compounds tested.

The "Porapak Q" type polymers were found to provide particularly effective performance as flavor release agents. The particles were found to easily retain up to their own weight of flavorants such as anethole or menthol. After cigarettes containing "Porapak Q" type polymers containing a flavorant were stored for several weeks they were smoked and found to release to the smoke as much as 14 percent of the flavor.

Example 6

A styrene-ethylvinylbenzene-divinylbenzene cross-linked polymer ("Porapak Q," Waters Associates, Inc., Framingham, Mass.) was sieved to pass 150 mesh. This resin was applied to cellulose acetate crimped tow, 8 denier/40,000, which had been air-opened. The resin was applied at the rate of 10 grams per meter. This tow was gathered and wrapped as a filter rod by commercial filter-making machinery. Lengths of 1 cm. were cut from the rod and attached to 65 mm. cigarette rods, together with an outer 1 cm. filter of 5 denier/68,000 cellulose acetate tow. The combined filters had a resistance-to-draw (RTD) of 2.2 to 2.8 inches of water.

These cigarettes were smoked and the smoke was separated into particulate and gas phases; the analysis of the gas phase by mass spectrometry by the procedure of C. J. Varsel, F. A. Morrell, F. E. Resnik, and A. Powell, Anal. Chem. 32, No. 2, 182-186 (1960) was compared with the analysis of smoke gas phase delivered from the same cigarette rods filtered by 2.0 cm., 5 denier/68,000 cellulose acetate tow filters with the same range of RTD. It was found that xylene, toluene, benzene, and methylfuran had been reduced significantly (more than 20 percent by the porous resin filter) while the concentrations of methanol, isoprene, butadiene, acetaldehyde, among others, were not significantly affected.

Example 7

A filter plug was prepared for a cigarette consisting of an outer section 7.5 mm. long of crimped, fluffed cellulose acetate, 8 denier/48,000, plasticized with triacetin, and an inner section 12.5 mm. long of cellulose acetate tow approximately 5 denier/15,000 on which had been sprinkled 50 mg. of "Porapak Q" porous ethylvinylbenzene-divinylbenzene-styrene polymer, with pores 10.sup.4 Angstroms in diameter and particles 150 .times.200 mesh. This dual plug had a total resistance-to-draw (RTD) of 3 inches of water. The same combination of tows was made into a similar dual plug without the addition of the "Porapak Q" to serve as a control; this plug had a 1.6 inch RTD. Each was attached to an identical commercial cigarette rod 65 mm. long having a 2.0 inch RTD. A number of cigarettes of each type was smoked for analytical purposes.

Comparative results are given in Tables 1 and 2. It will be seen that removal of aromatic compounds above toluene in molecular weight is excellent. Removal of toluene is very good, while removal of nonaromatic, volatile compounds from the gas phase is insignificant (i.e., less than 20 percent), except for 22 percent HCN removal which is desirable. An activated charcoal filter which removes benzene and toluene to this extent also removes appreciable quantities of isoprene, ester, ketones, aldehydes, and like flavor contributors. This is illustrated in Table 3 where the action of the filters by themselves on a smokelike gas mixture is compared. ##SPC1## ##SPC2##

IR signifies analysis by infrared absorbance of the gas phase or gas mixture; GC signifies analysis by gas chromatography. In the analysis of smoke gas phase, the smoke delivered is passed through a Cambridge "total removal" filter pad (glass microfiber) to remove substantially all the particulate matter. The gaseous portion is introduced into the cell of an infrared spectrometer and its absorbance spectrum is measured. The height of previously identified absorption peaks gives relative measurement of the concentrations of components in comparison with the concentrations when no active gas filter is used.

The gas phase, similarly separated from particulates, and suitably diluted, may be introduced into a gas chromatographic column. The column employed was 15 cm. by 1/8-inch stainless steel packed with 60-80 mesh acid-base washed "Chromsorb P," coated with 10 percent by weight Dow Corning 550 silicone oil. The carrier gas was nitrogen; the components were detected by a flame ionization detector and identified by previously determined retention times for known major components. The peak area gave a relative measure of concentrations in comparison with those when no gas filter was present.

Example 8

Anethole, technical grade, was mixed with approximately twice its weight of "Porapak Q" porous polymer beads and left exposed to air for 2 days, until no more weight loss was observed. Weight loss during exposure was 12 percent of the initial anethole weight. Anethole content of the total weight was 33.2 percent by extraction and analysis.

Filters were prepared by sprinkling this granular material uniformly on crimped, opened cellulose acetate filter tow, 8 denier/24,000 and making the composite into cigarette filter rods which were calculated to contain 10 mg. of the anethole-resin per cm. of length. Filters 1 cm. long were attached to commercial cigarette rods 65 mm. long and 1 cm. backup filters of 8 denier/48,000 cellulose acetate were added. These were smoked by machine, and the smoke was trapped on Cambridge filter pads and analyzed. Some of these cigarettes were subjected to an accelerated aging cycle, in packs, consisting of 7 days at 110 .degree.F., 15 percent R.H. and 4 days at 90.degree. F., 85 percent R.H. Results of smoke analysis for these cigarettes are also given.

Fresh Aged __________________________________________________________________________ TPM, mg. 32 33 Anethole in Smoke, mg. 0.46 0.38 % of Original Anethole 13.9 11.5 __________________________________________________________________________

Example 9

Granular "Porapak Q" was flavored by slowly adding with mixing a solution of menthol in one-fourth its weight of ethanol. The mixture was heated in an air-circulating oven at 100.degree.C. for 61/2 hours until weight became nearly constant. The weights of porous beads and menthol were 20.2 and 14.8 g., respectively; the weight after heating was 35.0 g. Analysis by extraction and gas chromatography showed 45 percent menthol of total weight.

Filters were prepared as in the preceding example, with a loading of flavored granules of 8 mg. per cm. of length, with the same filter tow and backup. These filters, 1 cm.+ 1 cm., were attached as before to 65 mm. commercial cigarette rods. Smoking and analysis were carried out as in the preceding example; packs of cigarettes were aged for two cycles of 11 days each and were then smoked. ---------------------------------------------------------------------------

Fresh Aged 2 Cycles __________________________________________________________________________ TPM, mg. 38 32 Menthol in Smoke, mg. 0.53 0.38 % of Original Menthol 14.5 10.6 __________________________________________________________________________

A second sample of the beads was treated with a menthol-ethanol solution, washed with ethanol, and dried 2 1/2 hours at 100.degree. C. to nearly constant weight. Analysis showed 34 percent menthol of total weight. Cigarettes prepared as above, with 8 mg. of flavored beads in the filter, were smoked. ---------------------------------------------------------------------------

TPM, mg. 34 Menthol in Smoke, mg. 0.30 % of Original Menthol 11.1 __________________________________________________________________________

Example 10

Beads of "Porapak Q" were mixed with one-third their weight of "Magna" lime oil (distilled natural Mexican, Magnus, Mabee & Reynard Inc., N.Y., N.Y.), and applied to filter tow at the rate of 32 mg./cm. of filter length. Sections 5 mm. long were attached to cigarette rods and backed by 15 mm. of conventional cellulose acetate filter. Smokers found the cigarette to have a distinctive flavor which most identified as lime or citruslike.

The following examples are also illustrative of the present invention:

The "Porapak Q" polymer is in the form of small beads. The beads are quite spherical and similar in size when viewed under a stereo microscope. The 80.times.100 mesh size was confirmed by screening as 99 percent passed through an 80 mesh U.S. Standard screen and was held on a 100 mesh screen. Measurements were also taken from enlarged photographs. At 160 power the particles averaged 140 microns with a range from 120 to 175. At 500 power the surface pores could be discerned and their sizes ranged from 0.2 to 2 microns. This confirmed the stated 1 micron or 10.sup.4 Angstrom units size. During the testing our initial supply of "Porapak Q" was exhausted and a new supply received. The beads in this batch were the same size but were irregular in shape, not spherical. There was no indication that the change in shape affected the performance of the material.

The polymer beads appeared to possess a static charge as they showed a definite affinity for each other and tended to form a one layer film on any surface upon which they were in contact.

Another polymer of the "Porapak Q" type had a particle size of 150 .times.200 mesh. In utilizing this material, the main problem was one of filter configuration. Because of the small particle size a space fill plug gave a high RTD even at low loadings. A 12.5 mm. loosely compacted cellulose acetate section was pushed into a 20 mm. empty mouthpiece tube already attached to a cigarette rod. This section was made by dividing 5 dpf/30,000 denier tow in half and threading it through 80 mm. empty tubes. These tubes were cut into 12.5 mm. sections and the tow transferred to the tubes attached to the cigarettes. A weighed amount of the polymer was then dropped into this section and the filter completed by capping with a 7.5 mm. 8 dpf/48,000 machine-made filter section. By this method a good dispersion of material could be presented to the smoke at a reasonable RTD. The following cigarettes were prepared for analytical testing: ---------------------------------------------------------------------------

Cigarette 1 65 mm. tobacco rod, CA mm. 5/15 Ca plus 50 mg. "Porapak Q," 7.5 mm. 8/48 CA-- RTD 5.0 .+-.0.3" for B(a ) P, whole smoke H.sub.2 O, I.R. Index, gas phase profile, TPM, nicotine, phenol. Cigarette 2 Same as Cigarette 1 except no "Porapak" added-- 3.6 .+-.0.2 " for TPM, nicotine, phenol. Cigarette 3 65 mm. tobacco rod, 20 mm. mouthpiece tube, 2.0 .+-.0.2" for Control I.R. Index, whole smoke H.sub.2 O, TPM, nicotine, phenol. Cigarette 4 65 mm. tobacco rod, 20 mm. Marlboro 4/49CA filter, 4.6.+-.0.2" for Whole smoke H.sub.2 O. Cigarette 5 Filter only: 5 mm. 8/48CA, 10 mm. 5/15 CA plus 50 mg. "Porapak Q," 5 mm. 8/48 CA--2.2.+-.0.2" for Synthetic gas phase. __________________________________________________________________________

The results of the analyses are shown in Tables 4 and 5. The TPM, nicotine and phenol values appear to be a function of RTD and not of the Porapak. That is, the decrease in deliveries shown are the result of a higher RTD filter. The whole smoke water delivery is slightly higher than expected from a cellulose acetate (only) filter of equal efficiency. The "Porapak Q" is somewhat nonselective for water. The I.R. index and the synthetic gas index indicate some general gas phase removal but the amount was not considered significant. ##SPC3##

Table 5 __________________________________________________________________________ Cigarette 1: Results of Gas Phase Profile. Analytical Method: Ratio comparison of the experimental cigarette gas phase delivery to that of a Marlboro monitor control by gas chromatography.

Compounds Ratio __________________________________________________________________________ Methane thru methyl chloride 1.0 Isoprene 0.97 Acetaldehyde 0.98 Acetone 1.0 Acrolein 0.82 Methyl vinyl Ketone* 0.87 Benzene* 0.77 Toluene 0.52 Limonene 0.13 Other possible aromatics 0.13 __________________________________________________________________________ Total of all gas phase 0.86 --------------------------------------------------------------------------- *Compound identity not positive.

The gas phase profile as determined by gas chromatography pinpoints the selective removal properties of this material. While this test showed a general reduction level of 14 percent, certain components (aromatics) were reduced up to 87 percent. Note the agreement of the general 14 percent reduction to the I.R. smoke index of 13.

The smaller gel material was subjected to only limited testing. A loading of 70 mg. of the gel on a loosely compacted cellulose acetate (CA) inner filter showed no affinity for B(a)P or TPM. The I.R. index was 5 which is indicative of almost no activity. A mass spectrograph analysis of the smoke from this sample gave no indication of selectivity or any adsorption.

The following examples are further illustrative of the flavor transfer ability of the present materials.

Anethole was chosen as the flavor to be used with the "Porapak Q" as a possible flavor transfer agent. The reasons for the choice of anethole were the availability of analytical methods for the quantitative determination of anethole and its ease of handling (liquid at room temperature).

Technical grade anethole was slowly hand mixed (due to the heat of adsorption) with the polymer in an approximate 1 anethole--2 polymer ratio. The mixture was then left in the flask and allowed to equilibrate at room conditions (75.degree. F., 60 percent R.H.). Equilibrium was reached in 2 days time as evidence by no further weight loss on periodic weighings. A portion of the sample was submitted for percent anethole analysis and the remainder utilized in cigarette construction for smoke analysis. The cigarettes were made by basically the same technique as described in the previous section. Half of the cigarettes were smoked fresh and the others were taken through one cycle of accelerated aging before smoking. ---------------------------------------------------------------------------

Cigarette 6 65 mm. filter rod, 10 mm. 8/24 Ca plus 10 mg. Porapak/Anethole, 10 mm. 8/48 CA outer filter. Cigarette 7 Porapak/Anethole sample. __________________________________________________________________________

The results as shown in Table 6 were encouraging. The fresh delivery is very good release from a filter. Although delivery decreased after aging it still remained at a high level. ##SPC4##

A more comprehensive study was undertaken using menthol as the flavor to give a comparison with an established flavor system.

The menthol employed was a conventional blend in an ethanol solution.

The 80 percent menthol--20 percent ethanol solution was slowly added to the polymer by hand mixing in an approximate 1 to 1 ratio. The mixture was then placed in an air-circulating oven until equilibrium was attained. The heating took 6 1/2 hours until no further weight loss was noted. To check if the percent menthol in the mixture could be calculated from the weight loss the following computation was made: ---------------------------------------------------------------------------

Weight of "Porapak Q" 20.205 g. Weight of menthol solution 18.458 Total weight as mixed 38.663 Final weight at equilibrium 35.048 Weight loss 3.615 Percent loss based on menthol solution 19.6 % __________________________________________________________________________

The weight loss was assumed to represent the ethanol as it equaled the amount in the initial solution. Then:

A sample cigarette 8 of the mixture was submitted for menthol analysis to confirm the calculated value. Cigarettes were made for smoke analysis in the same construction as before. A sample was also constructed with an active carbon to test the delivery in the presence of an active gas phase material. ---------------------------------------------------------------------------

Cigt. 9 65 mm. filter rod, 10 mm. 8/24 Ca plus 8 mg. Porapak/menthol, 10 mm. 8 148CA backup. Cigt. 10 65 mm. filter rod, 10 mm. 8 /24CA plus 8 mg. Porapak/menthol plus 50 mg. 50 .times.140 PCB carbon, 10 mm. 81 48 CA backup. Cigt. 11 65 mm. filter rod, 10 mm. 8/24 CA plus 50 mg. 50 .times.140 PCB, 10 mm. 8/48 CA backup. Cigt. 12 65 mm. filter rod, 20 mm. mouthpiece tube control. __________________________________________________________________________

These samples were analyzed fresh and after 2 cycles of accelerated aging. The results are listed in Table 7.

The 45 percent menthol in the sample as analyzed agreed with the 42 percent calculated figure so that it appeared that very little of the menthol was lost in the equilibrium process. The fresh delivery of 14 percent was similar to that with the anethole and about the same as if the menthol had been on the tobacco rod. However, the delivery was reduced after aging and was almost completely stopped by the active carbon. These results lead to the hypothesis that the menthol is not held tightly by the Porapak. Although heat (100.degree. C.) alone does not drive it off, it is released slowly with time or rapidly in the presence of a highly active absorbent. The gas phase activity of the carbon was not reduced as expected, perhaps since the 3.6 mg. of menthol available represents only a small part of the material that this amount of carbon can absorb. ---------------------------------------------------------------------------

TABLE 7 __________________________________________________________________________ ANALYSIS Sample Cigarettes Cigt. 8 -- "Porapak"/menthol only Cigt. 9 -- 8 mg. "Porapak"/menthol Cigt. 10 -- 8 mg. "Porapak" plus 50 mg. 50.times.140 PCB Cigt. 11 -- 50 mg. 50.times.140PCB Cigt. 12Empty tube control Percent Menthol in Cigarette 8 -- 45 % Aged(2 Fresh Cycles __________________________________________________________________________ Cigt. 9 Cigt. 10 Cigt. 11 Cigt. 12 __________________________________________________________________________ Available menthol, 3.6 3.6 -- 3.6 mg. TPM, mg. 38 33 -- 32 Menthol in smoke, mg. 0.53 0.04 -- 0.38 Percent menthol 14.5 1.1 -- 10.6 deliveryIR Index -- 27 25 -- __________________________________________________________________________

Two tests were attempted to determine the maximum retention level of the polymer for menthol with nether being entirely successful.

In the first test a sample of "Porapak Q" was treated with an excess of menthol-ethanol, vacuum filtered washed with a small amount of ethanol and dried in an air-circulating oven to nearly constant weight. A sample (Cigarette 13) of this mixture analyzed as only 34 percent menthol and from a cigarette (Cigarette 14) delivered only 11 percent of the available menthol. Either the Porapak was not left in contact with the menthol solution until saturation was achieved or a portion of the adsorbed menthol was removed by the alcohol wash.

In the second test a different approach was used. Additional menthol-ethanol solution was added to the previously prepared sample Cigarette 8 (45 percent menthol). From weight loss data it was apparent that as more menthol was adsorbed, a higher percent of that adsorbed was driven off in the equilibrating period. The point at which the weight loss would equal the weight gain appeared to be somewhat over 50 percent . The test was not run to conclusion as the polymer was inadvertently exposed to 150.degree. C. temperature during the latter stages and some unexpected degradation occurred. Although a definite saturation point is still not known it has been found that the "Porapak Q" can retain its own weight of menthol.

A third flavor, lime oil, was tried with the polymer. The oil was adsorbed on the "Porapak" in an approximately 1 oil to 3 polymer ratio. As no analytical tests are were readily available cigarettes were prepared from this sample and smoked for subjective taste. All who smoked this cigarette (15) detected a definite different flavor and in most cases identified the flavor as lime or citruslike.

Other flavorants may also be effectively incorporated in cigarettes and other tobacco products in the same way.

The polymeric materials used in the present invention may be utilized as components of the ultimate, or mouthpiece, section of a multicomponent filter system. They can then serve to replace flavors removed from the tobacco smoke by filter elements closer to the tobacco. The polymers may also be used as components of a single filter element or as components of any other filter combination.

The polymer may comprise the only component of a filter section or may be employed with other filter material, such as tow or paper, with adhesives and the like and is, as set forth above, employed with flavorant materials to achieve the particularly beneficial results provided by the present invention. The amount of polymer present in the filter element of a smoking article may vary widely, but will generally comprise from about 1 to about 100 parts by weight based on the weight of the tobacco employed. The polymer may be in a variety of shapes and sizes and will be packed depending on the particular flavor release, resistance-to-draw and filtering characteristics desired.

The polymers used in the present invention are preferably ethylvinylbenzene-divinylbenzene polymers in spherelike particles of 80 .times.x 100 mesh size (which are marketed as "Porapak Q" polymers). These polymers have a pore size of 10.sup.4 angstrom units (1 micron ), a total surface area of 50 meters.sup.2 /milliliter and a bulk density of 0.5 gram/ml.

Generally, the polymers will contain or be loaded with from about 10 to 100 parts by weight of flavorant per 100 parts of polymer.

The present polymers are particularly effective for the incorporation of menthol, anethole and similar flavorants into tobacco products but may be employed to incorporate other flavorants as well. For example, any flavorants may be employed which comprise molecules containing polar groups and/or possess some degree of polarity, whereby displacement of the flavorant by the smoke stream may be effected. Illustrative of suitable flavorants are the following materials:

Aromatic acids, such as: phenyl acetic acid, nonanoic acid, and the like.

Aromatic aldehydes, such as: benzaldehyde, tolylaldehyde cinnamaldehyde, anisic aldehyde, citral, ethyl vanillin, vanillin, phenyl acetaldehyde, and the like.

Aromatic ketones, such as: benzophenone (diphenyl ketone), acetophenone, dibenzylketone, ionones, menthone, methyl nonyl ketone, nerone, pulegone, piperine, and the like.

Aromatic ethers, such as: anisole, anethole, benzylisoamyl ether, dihydroanethole, dimethyl hydroquinone, estragole, methyl eugenol, safrole, and the like.

Aromatic esters, including: acetates, anisates, anthranilates, benzoates, butyrates, butyrates, caproates, cinnamates, formates, laurates, palmitates, propionates, and the like, for example, methyl anthranulate, ethyl anthranilate, dimethyl anthranilate, benzylisoamylacetate, p-cresyl acetate, cinnamyl acetate, benzyl acetate, eugenol acetate, benzyl phenyl acetate, and the like.

Aromatic alcohols, such as: menthol, eugenol, cinnamic alcohol, methyl eugenol, anisyl alcohol, citronellol, geraniol, farnesol, nerol, myristyl alcohol, and the like.

As used herein, unless otherwise stated, all parts and percentages are by weight.

The term TPM is defined as the total particulate material in milligrams in the smoke from a cigarette as collected on a Cambridge filter.

Resistance to draw, also referred to in this specification as RTD, was determined as follows:

A vacuum system was set to pull an air flow of 1050 cc./min. by inserting the tapered end of a standard capillary tube through the dental dam of the cigarette holder and adjusting the reading on the water manometer to correct RTD. The water level of the manometer was set at zero before inserting the standard capillary.

Then the butt end of a cigarette or plug was inserted to a depth of 5 mm. in the dental dam of the cigarette holder. The pressure drop behind this cigarette with 1050 cc./min. of air flow passing through was read directly as RTD (inches water) from the inclined water manometer.

Claims

We claim:

1. A filter for tobacco smoke comprising a solid, finely divided, microporous organic polymer containing within the pores from about 10 to about 100 parts, by weight, of an adsorbed flavor for tobacco smoke, per 100 parts of polymer said polymer upon contact with tobacco smoke, being capable of removing undesirable components from said tobacco smoke.

2. A smoking article comprising tobacco and a filter for tobacco smoke, said filter comprising a solid, finely divided, microporous organic polymer containing within the pores from about 10 to about 100 parts, by weight, of an adsorbed flavor for tobacco smoke, per 100 parts of polymer, upon contact with tobacco smoke, being capable of removing undesirable components from said tobacco smoke.

3. The filter of claim 1, wherein said polymer is a copolymer of ethylvinylbenzene and divinylbenzene.

4. The filter of claim 1 wherein said flavorant is anethole.

5. The filter of claim 1 wherein said flavorant is menthol.

6. The filter of claim 3, wherein said polymer is a copolymer of ethylvinylbenzene and divinylbenzene and said flavorant is anethole.

7. The filter of claim 3, wherein said polymer is a copolymer of ethylvinylbenzene and divinylbenzene and said flavorant is menthol.