JP4824568B2 - Cigarette smoke filter - Google Patents

Description

  The present invention relates to a tobacco smoke filter, particularly for cigarettes.

  The use of activated carbon to remove unwanted gas phase (VP) components from tobacco smoke is well known.

  There are over 400 compounds in the VP fraction of cigarette smoke (eg, aldehydes, ketones and hydrocarbons). Activated carbon is a strong adsorbent, which is effective in removing many of these compounds from tobacco smoke. However, all the compounds in the VP fraction tend to be reduced to a similar extent by activated carbon, which can be described as an effective “generic adsorbent”.

  In recent years, there has been increased interest in selective filtration through cigarette filters, ie enhanced removal of certain compounds from tobacco smoke compared to removal of other smoke components. One compound where selective removal is particularly desirable is HCN because hydrogen cyanide (HCN) is generally recognized as one of the most toxic compounds found in the VP fraction. HCN is removed by standard activated carbon when used in cigarette filters, but it is not selectively removed compared to other VP compounds. In fact, the removal rate is usually lower than other VP compounds.

  It is well known that various chemical substances are added to activated carbon to increase the removal rate of a specific compound. These “impregnated carbons” can remove specific compounds through chemical reactions as well as by physical adsorption. Such impregnated charcoal, for example, is widely used in gas mask and ventilator applications where, for example, activated carbon is generally impregnated with one or more of many chemicals targeted for the removal of specific poisons. In our experiments, it has been shown that such ventilator class activated carbon provides relatively low levels of overall removal and is therefore relatively ineffective when used in cigarette filter applications. It is clear that ventilator class activated carbon is not suitable for a cigarette filter environment with much less contact time between carbon and gas than in gas mask / ventilator applications. These ventilator class activated carbons also showed little evidence of enhanced selectivity for HCN. The above will generally predict that a high loading of the additive will be required for effective removal of HCN in cigarette filter applications.

  We have unexpectedly found that the use of a relatively low level of additive in combination with a base activated carbon having a higher activity than that used in standard cigarette filters helps remove HCN from cigarette smoke. It has been found to be extremely effective.

  According to the present invention, there is provided a tobacco smoke filter containing a highly active activated carbon impregnated with a metal additive.

  Preferably, the metal additive is present in an amount of 10% or less of the dry weight of the high activity activated carbon. More preferably, the additive is present in an amount that is 1-5% of the high activity activated carbon. The metal additive can be, for example, one or more of copper, manganese, molybdenum, cobalt, iron, and zinc. In one preferred embodiment, the additive is copper. In another preferred embodiment, the metal additive is a combination of copper and molybdenum.

  As used herein, “metal additive”, “copper”, “molybdenum” and the like refer to the metals themselves and / or their ions in any form (eg, salt, complex, chelate, etc.).

  The activated carbon of the present invention can be derived from any raw material from which activated carbon can be prepared [these raw materials from which activated carbon can be prepared include, for example, wood, coal , Nut shells such as coconut, peat, petroleum coke and bone, and synthetic sources such as poly (acrylonitrile) or phenol-formaldehyde].

  The activated carbon is a “high activity” activated carbon. “Activity” in this context refers to the specific vapor (eg, carbon tetrachloride-CTC) adsorbed under equilibrium conditions with base activated carbon (base activated carbon refers to activated carbon prior to addition with an additive such as copper and / or molybdenum). ) Weight percentage. The level of activity herein is given as a% CTC value. Thus, an activated carbon activity value of 95% CTC refers to an adsorption level of 95% by weight of CTC under equilibrium conditions. “High activity” refers to a base activated carbon that adsorbs above about 90% CTC under equilibrium conditions (ie, activated carbon prior to metal deposition). Preferably, the activity is greater than 90% before application. More preferably, the activity of the activated carbon is greater than 100% prior to application (ie, the base activated carbon adsorbs greater than about 100% CTC under equilibrium conditions).

  Preferably, the activated carbon has an activity of greater than 80% CTC, more preferably greater than 90% CTC after application.

  The present invention in a further aspect provides a tobacco smoke filter containing activated carbon impregnated with copper and molybdenum having a copper to molybdenum ratio greater than 1.3 to 1.

  The preferred ratio (by weight) of copper to molybdenum in the impregnated activated carbon is greater than 2: 1. Particularly preferred is a ratio between 3.5: 1 and 4.5: 1. A particularly preferred ratio of copper to molybdenum in the impregnated activated carbon is 4: 1.

  Preferably, the activated carbon is a high activity activated carbon.

  The present invention in a further aspect provides a tobacco smoke filter containing activated carbon impregnated with copper and molybdenum, which is a high activity activated carbon.

  High activity activated carbon has been discussed above. Preferably, the activated carbon has an activity greater than 90% CTC, more preferably greater than 100% CTC.

  Preferably, copper and molybdenum are present in a combined amount that is 10% or less of the dry weight of the activated carbon. Preferably, copper and molybdenum are present in the activated carbon in an amount that is 1-5% of the dry weight of the activated carbon.

  Preferably, the copper to molybdenum ratio is greater than 1.3 to 1. More preferably, the copper to molybdenum ratio is greater than 2: 1, preferably between 3.5: 1 and 4.5: 1. A particularly preferred copper to molybdenum ratio is 4 to 1.

  We most surprisingly have a dramatic decrease in metal additive concentrations (eg, copper / molybdenum additive concentrations) compared to the additive concentrations normally used in military or non-military artificial respirators. It has been found that there is no discernable deterioration in HCN removal.

  The particle size of the activated carbon of the present invention depends on the required performance and filter structure. In this specification, the given mesh size is a US mesh. Suitable impregnated activated carbon has a particle size between 2 mm (mesh size 10) to 0.15 mm (100 mesh). Preferably, substantially all of the impregnated activated carbon has a particle size between 0.6 mm (30 mesh) and 0.212 mm (70 mesh). More preferably, substantially all of the impregnated activated carbon has a particle size between 0.425 mm (40 mesh) and 0.212 mm (70 mesh).

  The tobacco smoke filter impregnated activated carbon according to the present invention can exhibit surprising selective removal of HCN without adversely affecting the overall VP reduction. Impregnated charcoal has a chemical reaction between the impregnating components (eg, metal ions) and the components present in the smoke (and / or the products of these reactions) to the taste of the cigarette that reduces smoker satisfaction. So far, it has not found an advantage in cigarette applications because of its adverse effects. The tobacco smoke filter of the present invention can include, for example, lower amounts of impregnated copper, impregnated copper and molybdenum, rather than the amount that was previously deemed necessary for acceptable removal of HCN, This is likely to reduce any adverse effects on taste.

  Applicants have also shown that the advantages of the activated carbon of the filter according to the invention are surprisingly effective at lower levels of activated carbon weight. This can reduce the costs associated with filter manufacture. A preferred tobacco smoke filter contains less than 150 mg of activated carbon impregnated with metal additives (eg, copper and molybdenum). Particularly preferred tobacco smoke filters contain 10 mg to 70 mg of impregnated activated carbon, more preferably 30 mg to 60 mg of impregnated activated carbon.

  The filter according to the invention can consist of any design previously proposed for particulate adsorbents including tobacco smoke filters. For example, the impregnated activated carbon according to the present invention can be distributed throughout a filter plug carried on a tow or fiber or sheet material collected to form a plug, which instead extends through a matrix of filter plugs. Is it possible to adhere to one or more yarns or to the inner surface of the wrapper around the filter plug (for example British Patent A-9124535 and British patents to which attention is directed for further information) As described in US Pat. No. A-9221545), or it can form a floor that is sandwiched between a pair of plugs (eg, between cellulose acetate tows) in a conventional wrapper.

  A filter according to the present invention is additionally required by the present invention, which may or may not selectively remove other compounds (eg, aldehydes) present in the VP fraction of cigarette smoke. It is possible to include one or more specific adsorbents other than activated carbon (eg, silica gel, different activated carbon or zeolite). The additional adsorbent (s) can be mixed with and / or separated from the activated carbon required by the present invention.

  The tobacco smoke filter according to the present invention can also provide effective removal of HCN even after a long period of time (eg, in storage) following filter or cigarette manufacture. Activated carbon used in known filters adsorbs volatile species present in the filter or tobacco during storage, thereby allowing the filter activated carbon to remove VP compounds when the cigarette is smoking. Can reduce the efficiency. This results in the efficiency with which known filters thereby remove HCN also decreasing over time. Surprisingly, the ability of the filter according to the invention to remove HCN does not deteriorate significantly even after storage over a long period of time (eg 6 months).

  The present invention also provides a filter cigarette comprising a filter according to any preceding claim connected to a tobacco rod packaged at its upstream end. A cigarette filter according to the present invention is typically attached to a packaged tobacco rod having a conventional mouthpiece wrapper that can be a breathable or non-breathable overhang.

  The invention is illustrated by the following examples and with reference to the accompanying drawings.

Comparative Example-Respirator Activated Carbon A number of impregnated commercial activated carbons recommended for HCN removal in ventilator applications are obtained from many suppliers and are routinely used in cigarette filter applications (non-attached) ) Compared with activated carbon. These tests involved assembling cigarettes with “triple granular” filters each containing 100 mg of activated carbon in a packed bed between two cellulose acetate filter segments. Smoke was emitted from filter cigarettes under ISO conditions (35 cm ³ blowing rate, one sampling per minute for 2 seconds each), and hydrogen cyanide HCN and average VP yield were measured. Average VP and HCN reduction percentages for cigarettes A through F (each of which contains one of six common ventilator class activated carbons) compared to equivalent cigarettes without any activated carbon in the filter. It is given in Table 1. The table also includes VP and HCN values for “standard” cigarettes containing filters containing non-impregnated activated carbon derived from coconut shells (as commonly used in cigarette filters).

  It is clear that the ventilator samples AF are not suitable for a cigarette filter environment. It is also clear that the standard filter is not selective for HCN.

Preparation of the impregnated sample The impregnated activated carbon sample was generally dissolved in an aqueous ammoniacal solution of basic copper (II) carbonate, ammonium carbonate and ammonium dimolybdate (VI), and the ratio (copper 2%, 0.5% molybdenum is given) and prepared by mixing with activated carbon. The amounts for other metal concentrations (and ratios) were adjusted accordingly. The resulting slurry was heat treated to 175 ° C. to produce a dry free flowing product which was then sieved to the required mesh size.

Test of impregnated samples Fourteen impregnated activated carbon samples were prepared by the method described above. Filter cigarettes were assembled and each contained 100 mg of a sample and tested using the procedure described for the comparative example above. The results for 14 loaded samples and two non-loaded samples (sample numbers 3 and 4) are given in Table 3.

  A further sample of impregnated activated carbon containing only 2% copper was prepared using the procedure described above, except that ammonium dimolybdate was excluded from the mixture. A sample (Sample No. 27) was tested using the same procedure used for the samples contained in Table 3, and the results are given in Table 3a.

  The results show that in a cigarette filter that is an embodiment of the invention, such as sample numbers 11, 15, and 27, VP material combined with a high HCN reduction rate (decrease rate of HCN in the VP fraction of cigarette smoke) In combination with a relatively low level of metal deposition (less than 10%, preferably 1-5%) to achieve a high reduction rate (ie, a reduction rate of components in the VP fraction of cigarette smoke) It indicates that it is desirable to use a base activated carbon having an activity (greater than about 90% CTC).

  Higher CTC activity tends to have both higher HCN retention and VP retention. VP retention increases with decreasing additive concentration. HCN retention remains fairly constant when measured as a function of copper and molybdenum concentrations (Table 3). Thus, the dramatic reduction in copper / molybdenum additive concentration compared to that used in non-military or military ventilators has resulted in no discernable deterioration in HCN removal by these activated carbon containing filters. It was surprising that they didn't.

  Activated carbons have been prepared derived from various base materials (eg, coconut shells and coal); these differ, for example, in terms of HCN retention between coal and coconut for the same mesh size, loading level and activity. Indicates that there is no.

  The results also clearly show that smaller mesh sizes (eg mesh size 30/70 US mesh) give better performance with respect to HCN than larger mesh sizes (eg compare samples 15 and 16). . This is in contrast to the customarily seen behavior in cigarette filters where it has been found that variations in mesh size have a relatively small effect on VP removal.

  Our experiments have also shown that the significant benefits of activated carbon in embodiments of the present invention are even more pronounced at lower levels of activated carbon weight in the filter. Sample numbers 8 and 11 were used to make cigarette filters with two different activated carbon weights (ie, 5% and 2.5% metal levels, respectively) and were tested as described above. The results are given in Tables 4a and 4b.

Long-term performance retention The disadvantage of known activated carbon containing filters is that the activated carbon in the filter adsorbs volatile species present in the filter or tobacco during storage, thereby causing the activated carbon to smoke. It is to reduce the efficiency with which the VP compound can be removed. This has the effect that the known activated carbon thereby reduces the overall efficiency of removing HCN over time. Applicants have tested changes in the performance of filter cigarettes containing filters embodying the present invention. The filter contained about 95 mg activated carbon per filter.

  Filters embodying the present invention stored as assembled cigarettes and changes in performance were measured at 0, 3 and 6 months. The results are shown in Table 5.

  It is clear that the performance of the HCN reduction rate of the filters embodying the invention, made with sample numbers 8 and 11, is not significantly reduced over 6 months (especially compared to samples containing standard activated carbon). .

  The filter of FIG. 1 includes a cellulose acetate tow cylindrical mouth-side suction filter plug 2, a cellulose acetate tow cylindrical upstream-side filter plug 3, and a filter wrapper attached around the plug to form a cavity 6 therebetween. 4. The cavity 6 is filled with activated carbon granules 17 prepared by the above-described method and loaded with copper and molybdenum having the same composition as the sample number 11 described above.

  FIG. 2 shows the upstream end 7 of the filter rod 10 in its own wrapping paper 11 at its upstream end 7 by means of a whole tip spout 12 which covers and attaches only the entire length of the filter and the adjacent end of the packaged tobacco rod 10, 11. Fig. 2 shows the type 1 filter to be joined.

Example 17
In the particular embodiment of the filter and cigarette according to the invention described with reference to FIGS. 1 and 2, the filter is 27 mm long and around 25 mm around. The mouth-side tip plug 2 is a 10 mm long non-wrapping acetate (NWA) plug--a molded unwrapped plug of plasticized cellulose acetate filaments that are gathered and bonded together as is well known in the art.

  The upstream mouthpiece plug 3 is a 10 mm long packaged acetate (WA) plug--that is, a molded package plug of plasticized cellulose acetate filament. The filter wrapper is 27 mm long and provides a cavity 6 that is 7 mm long extending between plugs 2 and 3. Cavity 6 is filled with 100 mg of activated carbon granules 17 prepared by the above method and affixed to sample number 11 above with copper and molybdenum of the same composition. The filter rod is attached to the commercially available packaged tobacco rods 10, 11 by means of a breathable mouthpiece wrapper 12.

  In a further specific example (Example 17a), the cavity is filled with 100 mg of activated carbon granules 17 prepared by the above method and affixed to sample number 27 above with the same composition of copper.

  It is understood that Example 17 and Example 17a are structurally similar to known triple granule filters, but include activated carbon according to the present invention.

  The filter of FIG. 3 has a cylindrical mouth side suction filtration plug 52 of cellulose acetate tow and a cylindrical upstream side filtration plug 53 of cellulose acetate tow. The upstream filtration prepared by the above-described method and loaded on the tow or fiber or sheet material to collect the activated carbon particles 67 having the same composition and copper and molybdenum impregnated in the above-mentioned sample number 11 to form a plug. Distribute throughout the plug 53. A filter wrapper 54 is attached around the plug. A filter of the type 3 is joined to the tobacco rod at its upstream end 57, for example in the manner shown with reference to Example 17 in FIG. 2 (eg, the overall length of the filter and the proximity of the packaged tobacco rod). It is understood that it is possible (by joining to the tobacco rod in its own wrapping paper) by means of a whole mouthpiece wrapper that only covers the end.

Example 18
In the particular embodiment of the filter according to the invention described with reference to FIG. 3, the filter is 27 mm long and about 25 mm in circumference. The mouth-side suction filter plug 52 is a 14 mm long unwrapped acetate (NWA) plug--a molded unwrapped plug of plasticized cellulose acetate filaments that are collected and bonded together as is well known in the art.

  The upstream tip plug 53 is also a 13 mm long molded plug of plasticized cellulose acetate filaments collected and bonded together as is well known in the art. A filtration plug prepared by the above-described method and supported on a tow material (filament) that collects 50 mg of activated carbon particles 67 having the same composition as the above-mentioned sample No. 11 and impregnated with copper and molybdenum and collected to form a plug. Disperse throughout 53. The methods by which particles can be introduced into the tow material during the collection process are well known in the art. A filter wrapper 54 was attached around the plug, which was 27 mm long.

  The filter rod can be attached to a commercially available packaged tobacco rod with a breathable mouthpiece in the manner shown and described with reference to FIG.

  In a further specific example (Example 18a), the cavities are filled with 50 mg of activated carbon particles 67 prepared by the method described above and impregnated with the same composition of copper as sample number 27 above, and they are placed on the tow material Is dispersed throughout the filtration plug 53 carried on the substrate.

  It is understood that Examples 18 and 18a are structurally similar to known active acetate filters, but include activated carbon according to the present invention.

  It is possible that the filter according to the invention can be of any design previously proposed for particulate adsorbents-including cigarette smoke filters in which known particulate adsorbents are replaced by the impregnated activated carbon of the invention. Understood.

FIG. 3 is a non-proportional schematic cross-sectional side view of individual filters and filter cigarettes according to one embodiment of the invention. FIG. 3 is a non-proportional schematic cross-sectional side view of individual filters and filter cigarettes according to one embodiment of the invention. FIG. 6 is a non-proportional schematic cross-sectional side view of individual filters according to different embodiments of the present invention.

Claims (9)

A cigarette smoke filter containing activated carbon impregnated with a metal additive, wherein the activated carbon is a high activity activated carbon having an activity of greater than 90% CTC prior to application , wherein the metal additive is copper, molybdenum, manganese, Selected from one or more of cobalt, zinc and iron, the metal additive (s) is present in an amount that is not more than 10% of the dry weight of the high activity activated carbon, and the activity of the activated carbon exceeds 80% CTC after the addition And a cigarette smoke filter in which all the activated carbon has a particle size of between 2 mm and 0.15 mm. The filter according to claim 1 , wherein the metal additive (s) is present in an amount that is 1-5% of the dry weight of the activated carbon. The tobacco smoke filter according to claim 1 or 2 , wherein the metal additive is copper. The ratio of copper to molybdenum is greater than 1.3: 1, also containing a high activity activated carbon which is impregnated with copper and molybdenum, tobacco smoke filter according to claim 1 or 2. The filter according to any one of claims 1 to 4 , wherein the activated carbon has an activity exceeding 100% CTC before being applied. The filter according to any one of claims 1 to 5 , wherein the activated carbon has an activity exceeding 90% CTC after being applied. The filter according to any one of claims 1 to 6 , comprising activated carbon between 10 mg and 150 mg. The filter according to any one of claims 1 to 7 , further comprising one or more additional adsorbents. A filter cigarette including the filter according to any one of claims 1 to 8 , which is joined to a tobacco rod packaged at an upstream end thereof.

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