CA1159742A - Tobacco smoke filter having improved tar/carbon monoxide ratio - Google Patents
Tobacco smoke filter having improved tar/carbon monoxide ratioInfo
- Publication number
- CA1159742A CA1159742A CA000424206A CA424206A CA1159742A CA 1159742 A CA1159742 A CA 1159742A CA 000424206 A CA000424206 A CA 000424206A CA 424206 A CA424206 A CA 424206A CA 1159742 A CA1159742 A CA 1159742A
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- Prior art keywords
- smoke
- inner member
- filter
- providing
- elongated
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT OF THE DISCLOSURE
A tobacco smoke filter having an improved tar/carbon monoxide ratio is disclosed. The filter is obtained by sealing off the center portion of the filter with an inner member which is impermeable to the passage of smoke, thus directing all of the smoke to the periphery of the filter.
In one embodiment, the inner member is formed as a thin walled tube of a material such as polypropylene, with the tube being crimped to seal one end of the tube. The crimped tube is then overwrapped with a smoke permeable material
A tobacco smoke filter having an improved tar/carbon monoxide ratio is disclosed. The filter is obtained by sealing off the center portion of the filter with an inner member which is impermeable to the passage of smoke, thus directing all of the smoke to the periphery of the filter.
In one embodiment, the inner member is formed as a thin walled tube of a material such as polypropylene, with the tube being crimped to seal one end of the tube. The crimped tube is then overwrapped with a smoke permeable material
Description
-I ~597~2 BACKGROUN~ AND SUMMARY OF THE INVENTION
The present ;nvention reIates to the production of fil-ter means, and reIates more particularly to tobacco smoke filter elements. More specifically, the instant inventive concepts are primarily concerned with producing filter means for cigarettes, although the products of this invention are generally useful as filters, particularly for tobacco smoking means, whether they be cigarettes, cigars, pipes or the like. Since filters for ci-gerettes are particularly commerciall~ important, the basic em-bodiments of the instant invention will be discussed as they re-late to the production of filtered cigarettes.
In making filters for use in connection with cigarettes and the like, a number of different properties of the resultant filter must be taken into consideration. While filtration ef-ficiency, i.e., the ability of the filter to remove undesirable constituents from tobacco smoke, is perhaps the most important property of cigarette filters, filtration efficiency must fre-quently be compromised in order for the filter to possess a com-mercially acceptable combinationofother properties, including pressure drop, taste, hardness, appearance and cost. For example, :
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the most commonly utilized cellulose acetate filter has a rela-tiYely low filtration efficiency since increased efficiency can onl~r be obtained either by increasing the densit~ of the filter material or the length of the filter element, both of which pro-S duce a pressure drop across the filter which is excessive and un-acceptable from a commercial standpoint.
In recent years, air dilution has become a popular tech-nique for compensating for the relatively low filtration effi-ciency of cigarette filters having a sufficiently low pressure drop for commercial acceptance. The air dilution technique em-ploys ventilating air to dilute the smoke stream from the cigar-ette and thereby reduce the quantity of tar and other undesir-able tobacco smoke constituents drawn into the smoker's mouth for each puff or draw. The ventilating air is generally provid-ed through a plurality of perforations in the tipping paper employed for joining the filter to the tobacco column of the ci-garette, and if the filter is overwrapped with plugwrap paper, an air pervious plugwrap paper is employed.
The air dilution technique has several advantages in that it is the most economical method o~ reducing tar, it enables achievement of the exact amount of tar delivery desired, and it also contributes to the removal of undesirable gas phase consti-tuents, such as CO and NO. Disadvantages of the air dilution technique include lack of taste and uneven staining of the fil-ter. Also, even though air dilution is an excellent ~ -- 2 ....... . . .
.
, ~ ~597~2 means of providing for vapor phase removal. there is a need for selectively removing CO in xelation to the tar content.
Previous methods for remoYal of the vapor phase have included the method described in British Patent Application No.
2tol2,554 published August l, 1979, wherein the filter surface area is reduced by placing a thick plastic coating over a small acetate rod.
According to the present invention there is provided a method of making smoke filters comprising the steps of: (a) providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) providing a filter-ing material including a multiplicity of fibrous elements; (c) continuously passing said inner member through an elongated bonding zone and defining an annular space around said inner member in said bonding zone; (d) continuously passing said fil-tering material into and through said annular space and, in-termediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, chereby forming an elongated, smoke-permeable outer member defining a tortuous path for pas-. sage of smoke therethrough; and (e) transversely severing the resulting product at selected locations to form filter elements.
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, - ' ' - ' -3 A- ~159~2 .
In the use of a crimped tube, the beneficial r~sults ob-tained by directing the smoke to the periphery of the filter are obt:ained primarily in the uncrimped po~tion where the smoke is directed to the outer periphery of the filter, rather than in S the crimped area where the outer smoke permeable member will have a relatively large cross-sectional areaO Also the air dilution holes are located outwardly of the uncrimped portion of the smoke impermeable inner member, as shown in the examples described hereinafter.
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``^ ~159~2 In addition to directing the smoke to the periphery of the filter, the amount of surface area through which the smoke travels is reduced, thus reducing the filtration efficiency of the tar removal. It has been found that low filtration filters, in conjunction with the air dilution feature, deliver more taste at the same tar levels, provided the draw resistance can be main-tained. The theory on which this is based is that unfiltered smoke offers more taste than filtered smoke. By reducing the filtration and blending the air with all of the smoke the same weight of tar is achieved but with improved taste. In addition, this method of completely blending the smoke can be designed so that it will provide the filter with a clean appearance after smoking and so that, in any event, the staining will be uniform.
A most important feature of the present invention is that a tar/CO ratio of approximately 2 is achieve~, compared to a ratio of 1 for conventional air diluted cigarettes which deli-ver from 5 to 10 mgs. of tar. An additional important feature of the present invention i8 that the present filter can be pro-duced at a lower cost than conventional acetate filters.
Other advantages of the tobacco smoke filter of the pre-sent invention include the fact that different shaped tubes may be extruded in order to provide various shapes for the filter.
~y modifying the crimp, many unique end appearances for the fil-ter can be achieved. Also, by modifying the process and using white tubing, for example, a conventional end ~J - 4 ..... .
_5_ ~ 1597~2 appearance of the filter can be maintained. In addition, a thick sheet of filter material can be employed rather than the acetate tow, by use of the wrapped filter-making technique so that the crimped filter tube would be wrapped with a filter ~aterial.
An additional feature of the present invention is the use of a plug of acetate tow material to prevent the thin wall crimped tube from being shown at the end of the filter.
Another feature of the present invention is a progressive ventilation feature, wherein the thin walled tube is provided with a series of perforations around its periphery in order to obtain a more uniform amount of tar passing through the filter.
Yet another feature of the present invention is the use ~5 of a filter comprising a reconstituted tobacco member, wherein the tobacco member is hidden from being shown at the end of the filter by the use of a plug of acetate tow.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the present invention will b~ more fully understood from the following description of the preferred embodiments, taken in conjunction with the accompany-ing drawings, wherein:
Fig. 1 is an enlarged perspective view of one form of cigarette pro~uced according to the invention, with parts being . broken away for illustrative clarity;
~ .. .. ..
I 1597~2 Fig. 2 is a schematic view of a method and means for making filter elements according to the instant inventive con-cepts:
Fig. 3 is a fragmentary view in partial cross-section of a filter rod produced according to this invention, taken along line 3-3 of Fig. 1:
Fig. 4 is a transverse cross-sectional view through the filter element of the filterec cigarette of Fig. 1, taken along line 4-4 of Fig. l;
Fig. 5 is an end elevational view of the filter element of Fig. 1, taken along line 5-5 of Fig. l;
Fig. 6 is a fragmentary elevational view of the crimping means utilized in forming the inner member according to this invention:
15, Fig. 7 is a sectional view taken along line 7-7 of Fig. 6;
Fig. 8 and 9 are alternative embodiments of the crimping wheel configuration shown in Figs. 6 and 7;
Fig. 10 is a fragmentary sectional view showing the manner in which the outer member of the filter element is
The present ;nvention reIates to the production of fil-ter means, and reIates more particularly to tobacco smoke filter elements. More specifically, the instant inventive concepts are primarily concerned with producing filter means for cigarettes, although the products of this invention are generally useful as filters, particularly for tobacco smoking means, whether they be cigarettes, cigars, pipes or the like. Since filters for ci-gerettes are particularly commerciall~ important, the basic em-bodiments of the instant invention will be discussed as they re-late to the production of filtered cigarettes.
In making filters for use in connection with cigarettes and the like, a number of different properties of the resultant filter must be taken into consideration. While filtration ef-ficiency, i.e., the ability of the filter to remove undesirable constituents from tobacco smoke, is perhaps the most important property of cigarette filters, filtration efficiency must fre-quently be compromised in order for the filter to possess a com-mercially acceptable combinationofother properties, including pressure drop, taste, hardness, appearance and cost. For example, :
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~ ' ." ~ , ~ 30 ., '' '':
~, -- 1 --*~
~ 1 ~97~ ~
the most commonly utilized cellulose acetate filter has a rela-tiYely low filtration efficiency since increased efficiency can onl~r be obtained either by increasing the densit~ of the filter material or the length of the filter element, both of which pro-S duce a pressure drop across the filter which is excessive and un-acceptable from a commercial standpoint.
In recent years, air dilution has become a popular tech-nique for compensating for the relatively low filtration effi-ciency of cigarette filters having a sufficiently low pressure drop for commercial acceptance. The air dilution technique em-ploys ventilating air to dilute the smoke stream from the cigar-ette and thereby reduce the quantity of tar and other undesir-able tobacco smoke constituents drawn into the smoker's mouth for each puff or draw. The ventilating air is generally provid-ed through a plurality of perforations in the tipping paper employed for joining the filter to the tobacco column of the ci-garette, and if the filter is overwrapped with plugwrap paper, an air pervious plugwrap paper is employed.
The air dilution technique has several advantages in that it is the most economical method o~ reducing tar, it enables achievement of the exact amount of tar delivery desired, and it also contributes to the removal of undesirable gas phase consti-tuents, such as CO and NO. Disadvantages of the air dilution technique include lack of taste and uneven staining of the fil-ter. Also, even though air dilution is an excellent ~ -- 2 ....... . . .
.
, ~ ~597~2 means of providing for vapor phase removal. there is a need for selectively removing CO in xelation to the tar content.
Previous methods for remoYal of the vapor phase have included the method described in British Patent Application No.
2tol2,554 published August l, 1979, wherein the filter surface area is reduced by placing a thick plastic coating over a small acetate rod.
According to the present invention there is provided a method of making smoke filters comprising the steps of: (a) providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) providing a filter-ing material including a multiplicity of fibrous elements; (c) continuously passing said inner member through an elongated bonding zone and defining an annular space around said inner member in said bonding zone; (d) continuously passing said fil-tering material into and through said annular space and, in-termediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, chereby forming an elongated, smoke-permeable outer member defining a tortuous path for pas-. sage of smoke therethrough; and (e) transversely severing the resulting product at selected locations to form filter elements.
,,il,., ,,, .,~ .. . .
.
, - ' ' - ' -3 A- ~159~2 .
In the use of a crimped tube, the beneficial r~sults ob-tained by directing the smoke to the periphery of the filter are obt:ained primarily in the uncrimped po~tion where the smoke is directed to the outer periphery of the filter, rather than in S the crimped area where the outer smoke permeable member will have a relatively large cross-sectional areaO Also the air dilution holes are located outwardly of the uncrimped portion of the smoke impermeable inner member, as shown in the examples described hereinafter.
.
~, .
``^ ~159~2 In addition to directing the smoke to the periphery of the filter, the amount of surface area through which the smoke travels is reduced, thus reducing the filtration efficiency of the tar removal. It has been found that low filtration filters, in conjunction with the air dilution feature, deliver more taste at the same tar levels, provided the draw resistance can be main-tained. The theory on which this is based is that unfiltered smoke offers more taste than filtered smoke. By reducing the filtration and blending the air with all of the smoke the same weight of tar is achieved but with improved taste. In addition, this method of completely blending the smoke can be designed so that it will provide the filter with a clean appearance after smoking and so that, in any event, the staining will be uniform.
A most important feature of the present invention is that a tar/CO ratio of approximately 2 is achieve~, compared to a ratio of 1 for conventional air diluted cigarettes which deli-ver from 5 to 10 mgs. of tar. An additional important feature of the present invention i8 that the present filter can be pro-duced at a lower cost than conventional acetate filters.
Other advantages of the tobacco smoke filter of the pre-sent invention include the fact that different shaped tubes may be extruded in order to provide various shapes for the filter.
~y modifying the crimp, many unique end appearances for the fil-ter can be achieved. Also, by modifying the process and using white tubing, for example, a conventional end ~J - 4 ..... .
_5_ ~ 1597~2 appearance of the filter can be maintained. In addition, a thick sheet of filter material can be employed rather than the acetate tow, by use of the wrapped filter-making technique so that the crimped filter tube would be wrapped with a filter ~aterial.
An additional feature of the present invention is the use of a plug of acetate tow material to prevent the thin wall crimped tube from being shown at the end of the filter.
Another feature of the present invention is a progressive ventilation feature, wherein the thin walled tube is provided with a series of perforations around its periphery in order to obtain a more uniform amount of tar passing through the filter.
Yet another feature of the present invention is the use ~5 of a filter comprising a reconstituted tobacco member, wherein the tobacco member is hidden from being shown at the end of the filter by the use of a plug of acetate tow.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages and features of the present invention will b~ more fully understood from the following description of the preferred embodiments, taken in conjunction with the accompany-ing drawings, wherein:
Fig. 1 is an enlarged perspective view of one form of cigarette pro~uced according to the invention, with parts being . broken away for illustrative clarity;
~ .. .. ..
I 1597~2 Fig. 2 is a schematic view of a method and means for making filter elements according to the instant inventive con-cepts:
Fig. 3 is a fragmentary view in partial cross-section of a filter rod produced according to this invention, taken along line 3-3 of Fig. 1:
Fig. 4 is a transverse cross-sectional view through the filter element of the filterec cigarette of Fig. 1, taken along line 4-4 of Fig. l;
Fig. 5 is an end elevational view of the filter element of Fig. 1, taken along line 5-5 of Fig. l;
Fig. 6 is a fragmentary elevational view of the crimping means utilized in forming the inner member according to this invention:
15, Fig. 7 is a sectional view taken along line 7-7 of Fig. 6;
Fig. 8 and 9 are alternative embodiments of the crimping wheel configuration shown in Figs. 6 and 7;
Fig. 10 is a fragmentary sectional view showing the manner in which the outer member of the filter element is
2~ formed;
FigD 11 is an enlarged perspective vie~ of an alternative embodiment of the filter produced according to the present ~n-vention, with parts being broken away for purposes of clarity:
Fig. 12 ls a schematic view of a method and means fo ma~ing filter elements according to the embodiment o Fig. :1;
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~159~2 Fig. 13 is a fragmentary sectional view showing means for severing the inner rod to form discrete inner members employed in the embodiment of Fig. 11, Fig. 14 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig. 11 is formed;
Fig. 15 is an enlarged perspective view of another alter-native embodiment of the filter produced according to the present invention with parts being broken away for purposes of clarity;
Fig. 16 is a schematic view of a method and means for making filter elements according to the embodiment of Fig. 15;
Fig. 17 is fragmentary sectional view showing means for severing the inner rod to form discrete inner members employed in the embodiment of Fig. 15;
Fig. 18 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig. 15 is formed;
Fig. 19 is an enlarged perspective view of another alterna-tive embodiment of the filter produced according to the present invention, with parts being broken away for purposes of clarity;
Fig. 20 is a schematic view of a method and means for making filter elements according to the embodiment of Fig. 19;
FigO 21 is a fragment~ry sectional view showing means for providing perforations around the periphery of the inner members employed in the embodiment of Pig. 19;
Fig. 22 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig, 19 is formed; and Fig. 23 is an enlarged perspective view of another alternative embodiment of the filter of the present invention.
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-fi- 1 1597~2 DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to Fig. 1, a filtered cigarette according to the instant inventive concepts is designated generally by the reference nurneral 20 and comprises basically a tobacco rod shown partially at 22 and a filter element according to one embodiment of this invention designated generally by the reference nume~al 24, a conventional tipping overwrap being shown at 26 securing the tobacco rod and the filter element in end-to-end relation-ship according to well known prior art techniques. The tip-ping paper overwrap 26 is provided with a plurality of air dilution perforations 30 arranged circumferentially around the filter element 24 to permit ventilating air to be drawn through the filter element with each draw or puff of the cigarette.
15 Filter element 24 comprises basically an axially elon-gated, hollow, crimped inner member 28 and an axially elon-gated, hollow, outer member 32 which is uncrimped and provides a uniformly round periphery for attachment of the tipping over-wrap 26.
T~e inner member 28 is formed of a material which is impermeable to the passage of smoke. Thu- the material employed may be, for example, polypropylene, polyethylene or a similar material which does not allow smoke to pass through. The mate--iai employed for member 28 is preferably self-supportin~
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, 1S~2 in order to provide a suitable fr~mework for the overwrap of outer member 32, as described hereinafter. While the inner member 28 is shown in Fig. 4 as having a cavity 34 formed therein, it is within the scope of the present invention to employ an inner member 28 which is of solid cross-section, without such a cavity 34, the primary ~equirement for inner member 28 being that it be formed of a material which is impermeable or non-porous to the passage of smoke so that the smoke is forced to pass through the outer member 32.
In a preferred embodiment, the inner member 28 is formed by extruding a thin wall plastic tube of a material such as polypropylene, in accordance with well known methods, and crimping the tube thus formed so as to seal one end thereof as shown at 36 in Fig. 5.
The outer member 32 is preferably and primarily formed from a continuous tow of cellulose acetate filamentary material, although other filtering material may be used with slight modifications. For example, fil~mentary tow formed of other material such as polyethylene, pclypropylene and the lik2 ~; 20 or even non-woven staple fibers cf the type described in some detail in U.S. Patents Nos. 3,297,041 and 3,552,400 which are commonly assigned, may be used for the ou er member 32. In fact, it i5 even possibie to produce filt~r elements according to the present invention wherein the outer member 32 is produced from ~n extruded, open celle_ .~. ., .-- . :
. .
~ ~97~2 oamed material, such as cellulose acetate foam or the like.
However, since cellulose acetate filamentary tow is the pre-sently preferred material from a commercial standpoint, the remainder of this specification will be directed to the use of such material for the outer member 32.
Thus the outer member 32 is preferably formed of filamen-tary cellulose acetate members bonded together at their contact points to form smoke-permeable elements defining tortuous paths ~or passage of smoke therethrough. Filtering material of this nature is well known as are techniques for producing same.
As will be seen from Fig. 4, the outer surface of the inner member 28 is juxtaposed to the inner surface of the outer member 3Z. Since the inner member 28 is impermeable to the passage of smoke~ all of the smoke is forced to travel through the outer member 32 and none of the smoke enters the internal cavity 34 of the inner member 28. The diameter of the inne~ member 28 relative to the overall diameter of the filter 24 determines the percentage of the surface area of the filter 24 which is exposed to smoke. Of course this will vary somewhat along the length of the filter 24, due to the crimped configuration of the inner me~ber 28, except in cases when the outer tube is formed prior to inserting the inner tube (see Figs. 14 and 22). It has been found, in accordance with the present invention, that the greater the diameter of the inner mem~er 28, or correspondingly the thinner the cross-section of outer member 32, the higher will be the .,:;
~ ~ ' 1597~2 tar/C0 ratio and the lower the filtration efficiency. Thus, for example, by the use of an inner member 28 having an out-side diameter of about 6 mm, which corresponds to approximately 2/3 the cross-sectional area of a standard cigarette filter, there have been obtained nearly ideal characteristics for m~nu-facturing purposes when such an inner member 28 is used in combination with an outer member 32 of cellulose acetate tow material.
While the filter means 24 has been shown in Fig. 1 as having the crimped portions 36 of the inner member 28 juxta-posed to the tobacco section Z2 of the filtered cigarette, it is, of course, possible to reverse the filter means 24 so that the open area formed by the inner cavity is juxtaposed to the tobacco section 22, thus providing a mouth piece having a de-sign such as shown, for example, in Fig. S or presenting anyother crimped section at the mouth piece end of the filtered cigarette.
In Fig. 3 a continuous rod 40 made up of a multiplicity of integrally connected filter elements of the type shown at 24 in Fig. 1 will be seen. This rod is severed transversely along the lines 42,44 to produce individual filter elements such as shown at 24. Of course, the rod could be severed at other locations to produce filter elements of multiple length. More-over, it is common practice to initially produce double filters which are then secured to two tobacco sections by a common tip-ping overwrapj following which individual filtered cigarettes ,,,~, ' ' ~. .
-12- 1~59~42 are formed by severing the double filter at its midpoint.
In Figs. 2 and 6 through 10, there is shown the overall method and means utilized in producing filter elements in accordance with the present invention. Basically, this over-all technique is similar in many respects to the techniquesdescribed in detail in U.S. Patents Nos. 3,637,447 and 4,046, 063.
According to preferred embodiments of this invention, as indi-cated above, the material utilized in the production of the inner member 28 of the filter elements is a continuous extrusion of thin walled plastic tubing, designated generally by the reference numeral 50, formed of a material such as polypropylene.
The material 50 passes out of a conventional plastic extruder 52 where the tube shape is initially formed and then passes through a water and vacuum box 54 of conventional construction.
Such thin walled plastic tubing 50 can be formed by any of the methods well known in the art which result in a continuous tube, the walls of which are impermeable to the passage of smoke.
The- resultant thin-walled tube is crLmped at 60 by a multiplicity of crimping wheels 62, portions of which are sche-matically shown in detail in Figs. 6 and 7, to produce discrete, axially spaced, internal cavities 34 sealed at both ends by crLmped portions 36 as shown in Fig. 3. Ot:~er alternative crimping wheel configurations 62a, 62b with corresponding crimped portions 36a, 36b are shown in Figs. 8 and 3. Details of such crimping wheels will be seen, for example, in Figs. 10-13 of '`':"'' 1 1 a97 1 2 U.S. Patent No. 3,637,447.
The crimped tubing which is to form the inner members 28 passes out of the crimping area 60, being continuously pulled b~ garniture means 56, and passes into a conventional stuffer jet 66. Here the crimped inner member 28 functions as a mandrel, with the outer member 32 being formed about the inner member 28 from a filamentary tow material 72 during this portion of the processing as will be seen in detail in Fig. 10. As indicated previously, the filtering material utilized in the pro~uction of the outer member 32 of the filter elements is a continuous filamentary tow 72, which includes a multiplicity of bondable fibrous members activated by contact with a hot fluid, such as steam. The filtering tow material 72 is continuously passed into and through an elongated bonding zone, including a conven-1~5 tional stuffer jet 66, steam head 68 and cooling head 70, with the tow 72 being continuously pulled therethrough by garniture means 64. The tow 72 is contacted with steam in the steam head 68 to produce a smoke-perm2able annular ~all of bonded fibrous members formed about the inner member 28, with the resulting filter element formed by members 2~ and 32 being rendere~ self-supporting as it is cooled by air or the like in the cooling head 70.
After exiting from the cooling head 70, the resultant two-layered rod is then severed transvers21y at selected locations in a cutting means as sho~n sc~amaticall~ at 76. Prior to passing into the cutting means -6, the t~o-layered ro~ ma~ be ~ 1 ~97-1 2 overwrapped by a conventional plug wrap if desired. Since the rod is self-supporting, h.owever, a separate plug wrap is not re-quired. If a plug wrap is employed, an air permeable filter material should be used for this purpose, in order to retain the air dilution characteristics of the resulting filter.
While the use of acetate fibers to provide the outer mem-ber 32, as described previously, is the preferred method for co-vering the inner member 28, a:.thick sheet of filter material may be employed instead of the acetate fibers to cover or wrap the inner member 28. Such filter material employed for this purpose is a stiff material of the type used in the manufacture of ci-garette mouth pieces and the wrapping of the crimped inner mem-ber 28 with such filter material can be carried out by the method as described in U.S. Patent No. 3,599,646. If a sheet of filter material is employed rather than the acetate tow for the outer member 32, the limitation on the diameter of the inner member 28 would depend upon how thin a sheet could be used for the outer member 32 and still provide an acceptable pressure drop.
In an alternative embodiment, the filter 24a is produced so that the inner member 28a is hidden from the outer end of the filter 24a by a material which comprises the outer member 32a, as shown in Fig. 11. Such a filter 24a may be produced by the method as shown schematically in Fig. 12, which corres-ponds in many respects to the method as described in U.S. Patent No.
.. - 14 -~ ~ 597~ 2 4,064,791. In this alter-native m~thod, the thin walled plastic tubing 50 passes out of the! extruder 52 and through the water and vacuum box 54 and the crimping assem~ly 60 as described previously in connection with the first e~bodiment. The crimped thin walled tube, being pulled continuously by garniture means 56, then passes into a cutter and feed tube assembly 57 where the tube 50 is transv~rsely severed at axially spaced locations to form dis-crete inner members 28. The cutter and feed tube assembly 57, one form of which is shown in detail in Fig. 13, includes one or more radially, circumferentially spaced blades 80 which are rotatably supported as at 81 to transversely sever the tube 50. Jets of pressurized air or the like are employed in a spacing means 83 to axially separate the discrete members 28 lS as they pass into elongated tube 82, with the details of appa-ratus for this purpose being described in detail in U.S. Patent No. 4,064,791.
With the arrangement as described, the elongated tube 82 may be simultaneously utilized to provide a mandrel extending through a stuffer jet 84 and into a steam head 85, as shown in Fig. 14, to form an annular sp3ce for production of th- outer member 32 from a filamentary tow material such as shown at 72.
In order that the tow material 72 whic~ forms the outer mamber 32 will also fill the axial spaces between inner member. 28, the tube 82 should stop short of th2 steam head 85 so that the steam which contacts the filamentary tow 72 at points ~6 will ~ ' ~ 1$97~2 bond the fibers of the tow 72 located both circumferentially around the spac~d inner members 28 as well as between these members 28. As will be seen in Fig. 14, the inner members 28 are thus deposited, in axially spaced relationship, into the internal bore of the outer member 32, and with portions of member 32 forming a solid wall of bonded filamentary material between discrete inner members 28. The composite rod formed of the outer and inner members then passes through a cooling head 87 and is continuously moved forwardly by a fur ~er garniture means 88, passing into a cutting means 89 where the rod is severed transversely at selected locations. By severing the rod at locations 90, 91 in Fig. 14, for example, a filter 24a will be obtained wherein the inner membex 28a will be hidden within the filter and will not be visible on the exterior of the filter 24a, as shown in Fig. 11.
In an embodiment which is somewhat related to that just previously described, a reconstituted tobacco member is employed as the inner member 28b, as shown in Fig. 15, and the inner member 28b is hidden within the filter 24b by a portion of outer member 32b so as not to be visible on the exterior of the filter 24b. The reconstituted tobacco member is formed from a coherent sheet of reconsti~uted tobacco which has been uniformly embossed with a series of parallel grooves, and then compacted and bonded into a self-sustaining dimensionally stable axially elongated body whose longitudinal axis extends parallel to the embossed grooves.
,................................................ .
. -'~
~ ~ 597~ 2 It is pointed out that the reconstituted tobacco member is permeable to smoke and thus, when such a tobacco material is employed for the inner member 28b as shown in Fig. 15, smoke will pass through both the inner 28b and outer 32b members of the filter 24b.
Referring to Figs. 16, 17 and 18, a method and means for producing filter member 28b is shown. As shown schem~tically in Fig. 16, a continuous web 101 of reconstituted tobacco sheet, taken from a supply roll 102, is first passed through a pair of circumferentially grooved embossing wheels 103.
The embossed web lOla emerging from the embossing rolls 103 has its surface uniformly embossed with a series of parallel longitudinally extending grooves. The embossed web is then passed through a feed funnel 104 wherein it becomes formed and compacted together into an axially elongated rod-like formation.
; The compacted embossed ~eb is then passed through a heat-bonaing head 105 where, as the web passes through, it is sub-jected to heated gas treatment and thereby becomes heat-bonded into a self-sustaining axially elongated rod-like reconstituted Z5 to~acco body lOlb shaped to its desired cross-section. The - rod-like tobacco body lOlb is then preferably passed through ~1 - -.
(~ -18- t ~597~2 a conventional air-injecting cooling head 106 and thereafter through an elongated pulling device 107 provided with a longitudinally-extending passageway having a cross-sectional size and shape substantially equal to that of the reconstituted tobacco body lOlb in order to hold it in such size and shape for a period sufficient to ensure that its dimensional stability will be maintained in the subsequent processing stations.
The rod lOlb is next passed into a cutter and feed tube assembly 108, shown in detail in Fig. 17 and being of the type previously described in connection with Fig. 13. Thus the assembly 108 includes a plurality of cutting blades 109 which are rotatably supported at 110 to transversely sever the rod lOlb. Spacing means 111 is employed to axially separate the severed discrete members 28b as they pass into an elongated tube 112.
The remainder of the apparatus and method of forming the filter member 24b is similar to that described previously in connection with Fig. 12, with the tube 112 functioning as a mandrel extending through a stuffer jet 114 and into a steam head llS, as shown in Fig. 18, to form an annular space for production of the outer member 32b from a filamentary tow material such as shown at 116. Here again, as in connection with the embodiment of Fig. 14 previously discussed, the tube 112 should stop short of the steam head 115 so that the steam which contacts the filamentary tow 116 at points 118 will bond the fibers of the tow 116 located both circumferentially around the spaced ...... .
.
inner members 28 as well as between these members 28. As seen in Fig. 18, the inner members 28 are thus deposited, in axially spaced relationship, into the internal bore of outer member 32, and with portions of member 32 forming a S solid wall of bonded filamentary material between successive discrete inner members 28.
The composite rod formed of the outer and inner members then passes through a cooling head 120 and is continuously moved forwardly by a garniture means 121, passing into a cutting means 122 where the rod is severed transversely at selected locations. By severing the rod at locations 123, 124 in Fig. 18, for example, a filter 24b will be obtained wherein the inner member 24b, formed of reconstituted tobacco, will be hidden within the filter and will not be visible on the exterior of the filter 24b, as shown in Fig. lS.
In the embodimentsof Fi~.ll, and lS, the length of the inner member 28 should be at least approximately 20%
the length of the outer member 32 so that the desired effect of the use of an inner member 28 which is impermeable to the 2~ passage of smoke will be obtained.
In another alternative embodiment, the inner member 28c is provided with a series of perforations or holes 130 around the periphery of the uncrimped portion, iust ahead of the crimped portion of the member 28c, as shown in Fig. 19.
Such a configuration contributes to provide constant tar delivery from puff to puff. Thus, as smoke passes through : ' -: , '. ' ~, ' ' ' 9 ~ ~ 2 the holes 130 into the cavity 34 during initial puffs, greater amounts of tar, with a corresponding improYed taste, are allowed to pass through. During later puffs, however, the outer tow material 32 tends to fill up or clog the holes 130, thus prevent-ing smoke from passing through into the cavity 34 so that all the smoke must pass through the outer m~mber 32.
A method and apparatus for production of the filter 24c of Fig. 19 is partially shown in Fig. 20, with the portion of the apparatus which includes the plastic extruder, the water and vacuum box, the crimper and the first garniture means being the same as shown in the embodiment of Fig. 2 and thus not be-ing shown in Fig. 20. The first garniture means passes the crimped inner member 28 into a laser assembly 131, shown sche-matically at Fig. 21, wherein a laser device 132 is employed in a conventional manner to make a series of small holes or perfor-ations 130 on the end of the inner members 28. Any other con-ventional means may be employed in a similar manner to perforate the inner member 28 around the periphery thereof.
From the perforating laser assembly 131,the crimped tub-ing which is to form the inner members 28 passes into a conven-tional stuffer jet 133, steam head 134 and cooling head 135, wherein the formation of the outer member 32 about 11~9~
the inner member 28 is similar to the embodiment of Fig. 2 previously described. Thus the filtering tow material 136 which is to form the outer members 32 continuously passes into the bonding zone and is contacted with steam in the steam head 134, as described previously in connection with Fig. 2, to produce a smoke-permeable annular wall of bonded fibrous members formed about the inner member 28, as shown in Fig. 22. The resulting filter element formed by members 28 and 32 is then cooled in the cooling head 135 and is passed by garniture means 137 into the cutting means 138 to be severed at selected locations.
One advantage of the use of the filter of the present invention is the reduced weight of the filter. Thus, in the embodiment of Fig. 1, for example, by using as the inner member 28 a thin walled plastic tube having a 5 mil wall thickness, the weight reduction is approximately 3~/0 compared to the use of acetate tow ~aterial in an equal volume, i.e., 50% of the volume of the filter is replaced with a polypro-pylene tube weighing 30/0 12ss than the acetate which was removed. An additional advantage is the savings in prod_c i~n costs, duë to the use of less expensive polypr~pylene as compared to the more expensive acetate material.
The following Table I test data on tar/CO ratios o~taine~
¦ for the filter of the present invention as illustrated i~
~r. ~
~ , , .
:: .
~ 1~9`~2 .
Fig. 1, as compared to two known commercial cigarettes.
TABLE I
Tar CO Tar/CO Ratio Control 1: Commercial Brand 5.3 mgs. 5.8 mgs..9 5Commercial Brand 4.0 mgs. 4.5 mgs..9 Control 2: Commercial Brand 7.3 mgs. 7.0 mgs.1.0 Colmmercial Brand 7.5 mgs. 6.8 mgs.1.1 C O D Filter 12 mgs. 5.9 mgs.2.0 C 0 D Filter 8.5 mgs. 4.0 mgs.2.1 10C O D Filter 6.5 mgs. 3.0 mgs.2.2 C O D Filter 8.1 m~s. 3.7 mgs.2.2 _ _ _ . _ Note: 1. The C O D filter is the filter of the present inv~ntion as shown in Fig. 1, using one strand of 12/48 tow material formed over a 6 mm O.D. plastic tube.
The data of Table I illustrate the significant improve-ment in the tar/C0 ratios of the filter of the present invention.
Table II below shows the effects of tube diameter on the tar,/CO r~tio and filtration efficiency, employing a filter in accordance with Fig. 1.
TABLE II
ilter Diameter Material ~ar/CO Ratio Filtration Efficiency 8mm 12/48 acetate tow, 2.1 41%
6mm O.D. plastic tube 8mm 12/48 acetate tow, 4.8 mm O.D. plastic tube 1.8 46%
8mm 8/35 acetate tow, 6mm O.D. plastic tube 2.0 45%
8mm 8/35 acetate tow, 4.1 mm O.D. plastic tube 1.; 58%
. : .
~ 1597~2 In the use of the filter of Fig. 19 with the perforated inner tube member, as previously described, Table III shows data obtained on tar/C0 ratios for such filters as compared to a known commercial cigarette.
S TABLE III
COM~ERCIAL BRAND C O Dl Tar/C0 Ti~ P.D.,in. Mqs.Tar ~ P~,in. Mqs.Tar ~qs.C0 Ratio Before 4.1 -- 3~2 --1st Puff 4.2 .5 3.5 .6 .22 2.7 2nd " 4.2 .8 4.2 O7 ~0 3.5 3rd " 4.5 .9 5.6 .8 .22 3.6 4th " 4.7 1.0 5.7 .6 .23 2.6 5th " 4.6 1.5 5O3 .3 .27 1.1 lS 6th " 4.7 1.7 6.0 7 .29 2.4 7th " 5.9 .5 .20 2.5 Note: 1. The C O D filter is the filter of the present invention as shown in Fig. 19, with 12/48 acetate tow for the outer member and a 6mm O.D. plastic tube with four 0.020 inch diameter holes for the inner member.
In Figu 23, there is shown an alternative embodiment wherein the inner member 28d of the filter element 24d is open at both :
ends and crimped in the mid-portion of the length thereof. The filter element 24d of this embodiment may be manufactured by a method such as described previously in connection with the embodi-ment of Fig. 1, with the exception that the element 24d is cut at ' ~ :
locations such as to place the crimped portion of inner member 28d ' ~ at the mid-point of the length of the filter element 24d. Table IV
~30 shows data obtained on tar/C0 ratios for such filters as compared -~ to known commercial cigarettes.
i: -: ' ~ ' ' .
, ~ ~59 1~2 TABLE IV
Tar _ Tar/CO Ratio Control 1: 5.3 mgs. 5.8 mgs. .9 " 4.0 mgs. 4.5 mgs. .9 S Control 2: 7.3 mgs. 7.0 mgs. 1.
" 7.5 mgs. 6.8 mgs. 1.1 COD JI 7.8 mgs. 2.5 mgs. 3.1 " 6.7 mgs. 2.2 mgs. 3.1 Note: 1. The COD II filter is the filter of the presentinvention as shown in Fig. 23.
It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacri-ficing its material advantages, the forms hereinbefore described being merely preferred embodiments thereof.
,~:
.
~,J
'"*~
FigD 11 is an enlarged perspective vie~ of an alternative embodiment of the filter produced according to the present ~n-vention, with parts being broken away for purposes of clarity:
Fig. 12 ls a schematic view of a method and means fo ma~ing filter elements according to the embodiment o Fig. :1;
". ., ; ,,~,) ~' .
~159~2 Fig. 13 is a fragmentary sectional view showing means for severing the inner rod to form discrete inner members employed in the embodiment of Fig. 11, Fig. 14 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig. 11 is formed;
Fig. 15 is an enlarged perspective view of another alter-native embodiment of the filter produced according to the present invention with parts being broken away for purposes of clarity;
Fig. 16 is a schematic view of a method and means for making filter elements according to the embodiment of Fig. 15;
Fig. 17 is fragmentary sectional view showing means for severing the inner rod to form discrete inner members employed in the embodiment of Fig. 15;
Fig. 18 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig. 15 is formed;
Fig. 19 is an enlarged perspective view of another alterna-tive embodiment of the filter produced according to the present invention, with parts being broken away for purposes of clarity;
Fig. 20 is a schematic view of a method and means for making filter elements according to the embodiment of Fig. 19;
FigO 21 is a fragment~ry sectional view showing means for providing perforations around the periphery of the inner members employed in the embodiment of Pig. 19;
Fig. 22 is a fragmentary sectional view showing the manner in which the outer member of the embodiment of Fig, 19 is formed; and Fig. 23 is an enlarged perspective view of another alternative embodiment of the filter of the present invention.
..~
' ~
-fi- 1 1597~2 DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to Fig. 1, a filtered cigarette according to the instant inventive concepts is designated generally by the reference nurneral 20 and comprises basically a tobacco rod shown partially at 22 and a filter element according to one embodiment of this invention designated generally by the reference nume~al 24, a conventional tipping overwrap being shown at 26 securing the tobacco rod and the filter element in end-to-end relation-ship according to well known prior art techniques. The tip-ping paper overwrap 26 is provided with a plurality of air dilution perforations 30 arranged circumferentially around the filter element 24 to permit ventilating air to be drawn through the filter element with each draw or puff of the cigarette.
15 Filter element 24 comprises basically an axially elon-gated, hollow, crimped inner member 28 and an axially elon-gated, hollow, outer member 32 which is uncrimped and provides a uniformly round periphery for attachment of the tipping over-wrap 26.
T~e inner member 28 is formed of a material which is impermeable to the passage of smoke. Thu- the material employed may be, for example, polypropylene, polyethylene or a similar material which does not allow smoke to pass through. The mate--iai employed for member 28 is preferably self-supportin~
.. .~
, ...
, 1S~2 in order to provide a suitable fr~mework for the overwrap of outer member 32, as described hereinafter. While the inner member 28 is shown in Fig. 4 as having a cavity 34 formed therein, it is within the scope of the present invention to employ an inner member 28 which is of solid cross-section, without such a cavity 34, the primary ~equirement for inner member 28 being that it be formed of a material which is impermeable or non-porous to the passage of smoke so that the smoke is forced to pass through the outer member 32.
In a preferred embodiment, the inner member 28 is formed by extruding a thin wall plastic tube of a material such as polypropylene, in accordance with well known methods, and crimping the tube thus formed so as to seal one end thereof as shown at 36 in Fig. 5.
The outer member 32 is preferably and primarily formed from a continuous tow of cellulose acetate filamentary material, although other filtering material may be used with slight modifications. For example, fil~mentary tow formed of other material such as polyethylene, pclypropylene and the lik2 ~; 20 or even non-woven staple fibers cf the type described in some detail in U.S. Patents Nos. 3,297,041 and 3,552,400 which are commonly assigned, may be used for the ou er member 32. In fact, it i5 even possibie to produce filt~r elements according to the present invention wherein the outer member 32 is produced from ~n extruded, open celle_ .~. ., .-- . :
. .
~ ~97~2 oamed material, such as cellulose acetate foam or the like.
However, since cellulose acetate filamentary tow is the pre-sently preferred material from a commercial standpoint, the remainder of this specification will be directed to the use of such material for the outer member 32.
Thus the outer member 32 is preferably formed of filamen-tary cellulose acetate members bonded together at their contact points to form smoke-permeable elements defining tortuous paths ~or passage of smoke therethrough. Filtering material of this nature is well known as are techniques for producing same.
As will be seen from Fig. 4, the outer surface of the inner member 28 is juxtaposed to the inner surface of the outer member 3Z. Since the inner member 28 is impermeable to the passage of smoke~ all of the smoke is forced to travel through the outer member 32 and none of the smoke enters the internal cavity 34 of the inner member 28. The diameter of the inne~ member 28 relative to the overall diameter of the filter 24 determines the percentage of the surface area of the filter 24 which is exposed to smoke. Of course this will vary somewhat along the length of the filter 24, due to the crimped configuration of the inner me~ber 28, except in cases when the outer tube is formed prior to inserting the inner tube (see Figs. 14 and 22). It has been found, in accordance with the present invention, that the greater the diameter of the inner mem~er 28, or correspondingly the thinner the cross-section of outer member 32, the higher will be the .,:;
~ ~ ' 1597~2 tar/C0 ratio and the lower the filtration efficiency. Thus, for example, by the use of an inner member 28 having an out-side diameter of about 6 mm, which corresponds to approximately 2/3 the cross-sectional area of a standard cigarette filter, there have been obtained nearly ideal characteristics for m~nu-facturing purposes when such an inner member 28 is used in combination with an outer member 32 of cellulose acetate tow material.
While the filter means 24 has been shown in Fig. 1 as having the crimped portions 36 of the inner member 28 juxta-posed to the tobacco section Z2 of the filtered cigarette, it is, of course, possible to reverse the filter means 24 so that the open area formed by the inner cavity is juxtaposed to the tobacco section 22, thus providing a mouth piece having a de-sign such as shown, for example, in Fig. S or presenting anyother crimped section at the mouth piece end of the filtered cigarette.
In Fig. 3 a continuous rod 40 made up of a multiplicity of integrally connected filter elements of the type shown at 24 in Fig. 1 will be seen. This rod is severed transversely along the lines 42,44 to produce individual filter elements such as shown at 24. Of course, the rod could be severed at other locations to produce filter elements of multiple length. More-over, it is common practice to initially produce double filters which are then secured to two tobacco sections by a common tip-ping overwrapj following which individual filtered cigarettes ,,,~, ' ' ~. .
-12- 1~59~42 are formed by severing the double filter at its midpoint.
In Figs. 2 and 6 through 10, there is shown the overall method and means utilized in producing filter elements in accordance with the present invention. Basically, this over-all technique is similar in many respects to the techniquesdescribed in detail in U.S. Patents Nos. 3,637,447 and 4,046, 063.
According to preferred embodiments of this invention, as indi-cated above, the material utilized in the production of the inner member 28 of the filter elements is a continuous extrusion of thin walled plastic tubing, designated generally by the reference numeral 50, formed of a material such as polypropylene.
The material 50 passes out of a conventional plastic extruder 52 where the tube shape is initially formed and then passes through a water and vacuum box 54 of conventional construction.
Such thin walled plastic tubing 50 can be formed by any of the methods well known in the art which result in a continuous tube, the walls of which are impermeable to the passage of smoke.
The- resultant thin-walled tube is crLmped at 60 by a multiplicity of crimping wheels 62, portions of which are sche-matically shown in detail in Figs. 6 and 7, to produce discrete, axially spaced, internal cavities 34 sealed at both ends by crLmped portions 36 as shown in Fig. 3. Ot:~er alternative crimping wheel configurations 62a, 62b with corresponding crimped portions 36a, 36b are shown in Figs. 8 and 3. Details of such crimping wheels will be seen, for example, in Figs. 10-13 of '`':"'' 1 1 a97 1 2 U.S. Patent No. 3,637,447.
The crimped tubing which is to form the inner members 28 passes out of the crimping area 60, being continuously pulled b~ garniture means 56, and passes into a conventional stuffer jet 66. Here the crimped inner member 28 functions as a mandrel, with the outer member 32 being formed about the inner member 28 from a filamentary tow material 72 during this portion of the processing as will be seen in detail in Fig. 10. As indicated previously, the filtering material utilized in the pro~uction of the outer member 32 of the filter elements is a continuous filamentary tow 72, which includes a multiplicity of bondable fibrous members activated by contact with a hot fluid, such as steam. The filtering tow material 72 is continuously passed into and through an elongated bonding zone, including a conven-1~5 tional stuffer jet 66, steam head 68 and cooling head 70, with the tow 72 being continuously pulled therethrough by garniture means 64. The tow 72 is contacted with steam in the steam head 68 to produce a smoke-perm2able annular ~all of bonded fibrous members formed about the inner member 28, with the resulting filter element formed by members 2~ and 32 being rendere~ self-supporting as it is cooled by air or the like in the cooling head 70.
After exiting from the cooling head 70, the resultant two-layered rod is then severed transvers21y at selected locations in a cutting means as sho~n sc~amaticall~ at 76. Prior to passing into the cutting means -6, the t~o-layered ro~ ma~ be ~ 1 ~97-1 2 overwrapped by a conventional plug wrap if desired. Since the rod is self-supporting, h.owever, a separate plug wrap is not re-quired. If a plug wrap is employed, an air permeable filter material should be used for this purpose, in order to retain the air dilution characteristics of the resulting filter.
While the use of acetate fibers to provide the outer mem-ber 32, as described previously, is the preferred method for co-vering the inner member 28, a:.thick sheet of filter material may be employed instead of the acetate fibers to cover or wrap the inner member 28. Such filter material employed for this purpose is a stiff material of the type used in the manufacture of ci-garette mouth pieces and the wrapping of the crimped inner mem-ber 28 with such filter material can be carried out by the method as described in U.S. Patent No. 3,599,646. If a sheet of filter material is employed rather than the acetate tow for the outer member 32, the limitation on the diameter of the inner member 28 would depend upon how thin a sheet could be used for the outer member 32 and still provide an acceptable pressure drop.
In an alternative embodiment, the filter 24a is produced so that the inner member 28a is hidden from the outer end of the filter 24a by a material which comprises the outer member 32a, as shown in Fig. 11. Such a filter 24a may be produced by the method as shown schematically in Fig. 12, which corres-ponds in many respects to the method as described in U.S. Patent No.
.. - 14 -~ ~ 597~ 2 4,064,791. In this alter-native m~thod, the thin walled plastic tubing 50 passes out of the! extruder 52 and through the water and vacuum box 54 and the crimping assem~ly 60 as described previously in connection with the first e~bodiment. The crimped thin walled tube, being pulled continuously by garniture means 56, then passes into a cutter and feed tube assembly 57 where the tube 50 is transv~rsely severed at axially spaced locations to form dis-crete inner members 28. The cutter and feed tube assembly 57, one form of which is shown in detail in Fig. 13, includes one or more radially, circumferentially spaced blades 80 which are rotatably supported as at 81 to transversely sever the tube 50. Jets of pressurized air or the like are employed in a spacing means 83 to axially separate the discrete members 28 lS as they pass into elongated tube 82, with the details of appa-ratus for this purpose being described in detail in U.S. Patent No. 4,064,791.
With the arrangement as described, the elongated tube 82 may be simultaneously utilized to provide a mandrel extending through a stuffer jet 84 and into a steam head 85, as shown in Fig. 14, to form an annular sp3ce for production of th- outer member 32 from a filamentary tow material such as shown at 72.
In order that the tow material 72 whic~ forms the outer mamber 32 will also fill the axial spaces between inner member. 28, the tube 82 should stop short of th2 steam head 85 so that the steam which contacts the filamentary tow 72 at points ~6 will ~ ' ~ 1$97~2 bond the fibers of the tow 72 located both circumferentially around the spac~d inner members 28 as well as between these members 28. As will be seen in Fig. 14, the inner members 28 are thus deposited, in axially spaced relationship, into the internal bore of the outer member 32, and with portions of member 32 forming a solid wall of bonded filamentary material between discrete inner members 28. The composite rod formed of the outer and inner members then passes through a cooling head 87 and is continuously moved forwardly by a fur ~er garniture means 88, passing into a cutting means 89 where the rod is severed transversely at selected locations. By severing the rod at locations 90, 91 in Fig. 14, for example, a filter 24a will be obtained wherein the inner membex 28a will be hidden within the filter and will not be visible on the exterior of the filter 24a, as shown in Fig. 11.
In an embodiment which is somewhat related to that just previously described, a reconstituted tobacco member is employed as the inner member 28b, as shown in Fig. 15, and the inner member 28b is hidden within the filter 24b by a portion of outer member 32b so as not to be visible on the exterior of the filter 24b. The reconstituted tobacco member is formed from a coherent sheet of reconsti~uted tobacco which has been uniformly embossed with a series of parallel grooves, and then compacted and bonded into a self-sustaining dimensionally stable axially elongated body whose longitudinal axis extends parallel to the embossed grooves.
,................................................ .
. -'~
~ ~ 597~ 2 It is pointed out that the reconstituted tobacco member is permeable to smoke and thus, when such a tobacco material is employed for the inner member 28b as shown in Fig. 15, smoke will pass through both the inner 28b and outer 32b members of the filter 24b.
Referring to Figs. 16, 17 and 18, a method and means for producing filter member 28b is shown. As shown schem~tically in Fig. 16, a continuous web 101 of reconstituted tobacco sheet, taken from a supply roll 102, is first passed through a pair of circumferentially grooved embossing wheels 103.
The embossed web lOla emerging from the embossing rolls 103 has its surface uniformly embossed with a series of parallel longitudinally extending grooves. The embossed web is then passed through a feed funnel 104 wherein it becomes formed and compacted together into an axially elongated rod-like formation.
; The compacted embossed ~eb is then passed through a heat-bonaing head 105 where, as the web passes through, it is sub-jected to heated gas treatment and thereby becomes heat-bonded into a self-sustaining axially elongated rod-like reconstituted Z5 to~acco body lOlb shaped to its desired cross-section. The - rod-like tobacco body lOlb is then preferably passed through ~1 - -.
(~ -18- t ~597~2 a conventional air-injecting cooling head 106 and thereafter through an elongated pulling device 107 provided with a longitudinally-extending passageway having a cross-sectional size and shape substantially equal to that of the reconstituted tobacco body lOlb in order to hold it in such size and shape for a period sufficient to ensure that its dimensional stability will be maintained in the subsequent processing stations.
The rod lOlb is next passed into a cutter and feed tube assembly 108, shown in detail in Fig. 17 and being of the type previously described in connection with Fig. 13. Thus the assembly 108 includes a plurality of cutting blades 109 which are rotatably supported at 110 to transversely sever the rod lOlb. Spacing means 111 is employed to axially separate the severed discrete members 28b as they pass into an elongated tube 112.
The remainder of the apparatus and method of forming the filter member 24b is similar to that described previously in connection with Fig. 12, with the tube 112 functioning as a mandrel extending through a stuffer jet 114 and into a steam head llS, as shown in Fig. 18, to form an annular space for production of the outer member 32b from a filamentary tow material such as shown at 116. Here again, as in connection with the embodiment of Fig. 14 previously discussed, the tube 112 should stop short of the steam head 115 so that the steam which contacts the filamentary tow 116 at points 118 will bond the fibers of the tow 116 located both circumferentially around the spaced ...... .
.
inner members 28 as well as between these members 28. As seen in Fig. 18, the inner members 28 are thus deposited, in axially spaced relationship, into the internal bore of outer member 32, and with portions of member 32 forming a S solid wall of bonded filamentary material between successive discrete inner members 28.
The composite rod formed of the outer and inner members then passes through a cooling head 120 and is continuously moved forwardly by a garniture means 121, passing into a cutting means 122 where the rod is severed transversely at selected locations. By severing the rod at locations 123, 124 in Fig. 18, for example, a filter 24b will be obtained wherein the inner member 24b, formed of reconstituted tobacco, will be hidden within the filter and will not be visible on the exterior of the filter 24b, as shown in Fig. lS.
In the embodimentsof Fi~.ll, and lS, the length of the inner member 28 should be at least approximately 20%
the length of the outer member 32 so that the desired effect of the use of an inner member 28 which is impermeable to the 2~ passage of smoke will be obtained.
In another alternative embodiment, the inner member 28c is provided with a series of perforations or holes 130 around the periphery of the uncrimped portion, iust ahead of the crimped portion of the member 28c, as shown in Fig. 19.
Such a configuration contributes to provide constant tar delivery from puff to puff. Thus, as smoke passes through : ' -: , '. ' ~, ' ' ' 9 ~ ~ 2 the holes 130 into the cavity 34 during initial puffs, greater amounts of tar, with a corresponding improYed taste, are allowed to pass through. During later puffs, however, the outer tow material 32 tends to fill up or clog the holes 130, thus prevent-ing smoke from passing through into the cavity 34 so that all the smoke must pass through the outer m~mber 32.
A method and apparatus for production of the filter 24c of Fig. 19 is partially shown in Fig. 20, with the portion of the apparatus which includes the plastic extruder, the water and vacuum box, the crimper and the first garniture means being the same as shown in the embodiment of Fig. 2 and thus not be-ing shown in Fig. 20. The first garniture means passes the crimped inner member 28 into a laser assembly 131, shown sche-matically at Fig. 21, wherein a laser device 132 is employed in a conventional manner to make a series of small holes or perfor-ations 130 on the end of the inner members 28. Any other con-ventional means may be employed in a similar manner to perforate the inner member 28 around the periphery thereof.
From the perforating laser assembly 131,the crimped tub-ing which is to form the inner members 28 passes into a conven-tional stuffer jet 133, steam head 134 and cooling head 135, wherein the formation of the outer member 32 about 11~9~
the inner member 28 is similar to the embodiment of Fig. 2 previously described. Thus the filtering tow material 136 which is to form the outer members 32 continuously passes into the bonding zone and is contacted with steam in the steam head 134, as described previously in connection with Fig. 2, to produce a smoke-permeable annular wall of bonded fibrous members formed about the inner member 28, as shown in Fig. 22. The resulting filter element formed by members 28 and 32 is then cooled in the cooling head 135 and is passed by garniture means 137 into the cutting means 138 to be severed at selected locations.
One advantage of the use of the filter of the present invention is the reduced weight of the filter. Thus, in the embodiment of Fig. 1, for example, by using as the inner member 28 a thin walled plastic tube having a 5 mil wall thickness, the weight reduction is approximately 3~/0 compared to the use of acetate tow ~aterial in an equal volume, i.e., 50% of the volume of the filter is replaced with a polypro-pylene tube weighing 30/0 12ss than the acetate which was removed. An additional advantage is the savings in prod_c i~n costs, duë to the use of less expensive polypr~pylene as compared to the more expensive acetate material.
The following Table I test data on tar/CO ratios o~taine~
¦ for the filter of the present invention as illustrated i~
~r. ~
~ , , .
:: .
~ 1~9`~2 .
Fig. 1, as compared to two known commercial cigarettes.
TABLE I
Tar CO Tar/CO Ratio Control 1: Commercial Brand 5.3 mgs. 5.8 mgs..9 5Commercial Brand 4.0 mgs. 4.5 mgs..9 Control 2: Commercial Brand 7.3 mgs. 7.0 mgs.1.0 Colmmercial Brand 7.5 mgs. 6.8 mgs.1.1 C O D Filter 12 mgs. 5.9 mgs.2.0 C 0 D Filter 8.5 mgs. 4.0 mgs.2.1 10C O D Filter 6.5 mgs. 3.0 mgs.2.2 C O D Filter 8.1 m~s. 3.7 mgs.2.2 _ _ _ . _ Note: 1. The C O D filter is the filter of the present inv~ntion as shown in Fig. 1, using one strand of 12/48 tow material formed over a 6 mm O.D. plastic tube.
The data of Table I illustrate the significant improve-ment in the tar/C0 ratios of the filter of the present invention.
Table II below shows the effects of tube diameter on the tar,/CO r~tio and filtration efficiency, employing a filter in accordance with Fig. 1.
TABLE II
ilter Diameter Material ~ar/CO Ratio Filtration Efficiency 8mm 12/48 acetate tow, 2.1 41%
6mm O.D. plastic tube 8mm 12/48 acetate tow, 4.8 mm O.D. plastic tube 1.8 46%
8mm 8/35 acetate tow, 6mm O.D. plastic tube 2.0 45%
8mm 8/35 acetate tow, 4.1 mm O.D. plastic tube 1.; 58%
. : .
~ 1597~2 In the use of the filter of Fig. 19 with the perforated inner tube member, as previously described, Table III shows data obtained on tar/C0 ratios for such filters as compared to a known commercial cigarette.
S TABLE III
COM~ERCIAL BRAND C O Dl Tar/C0 Ti~ P.D.,in. Mqs.Tar ~ P~,in. Mqs.Tar ~qs.C0 Ratio Before 4.1 -- 3~2 --1st Puff 4.2 .5 3.5 .6 .22 2.7 2nd " 4.2 .8 4.2 O7 ~0 3.5 3rd " 4.5 .9 5.6 .8 .22 3.6 4th " 4.7 1.0 5.7 .6 .23 2.6 5th " 4.6 1.5 5O3 .3 .27 1.1 lS 6th " 4.7 1.7 6.0 7 .29 2.4 7th " 5.9 .5 .20 2.5 Note: 1. The C O D filter is the filter of the present invention as shown in Fig. 19, with 12/48 acetate tow for the outer member and a 6mm O.D. plastic tube with four 0.020 inch diameter holes for the inner member.
In Figu 23, there is shown an alternative embodiment wherein the inner member 28d of the filter element 24d is open at both :
ends and crimped in the mid-portion of the length thereof. The filter element 24d of this embodiment may be manufactured by a method such as described previously in connection with the embodi-ment of Fig. 1, with the exception that the element 24d is cut at ' ~ :
locations such as to place the crimped portion of inner member 28d ' ~ at the mid-point of the length of the filter element 24d. Table IV
~30 shows data obtained on tar/C0 ratios for such filters as compared -~ to known commercial cigarettes.
i: -: ' ~ ' ' .
, ~ ~59 1~2 TABLE IV
Tar _ Tar/CO Ratio Control 1: 5.3 mgs. 5.8 mgs. .9 " 4.0 mgs. 4.5 mgs. .9 S Control 2: 7.3 mgs. 7.0 mgs. 1.
" 7.5 mgs. 6.8 mgs. 1.1 COD JI 7.8 mgs. 2.5 mgs. 3.1 " 6.7 mgs. 2.2 mgs. 3.1 Note: 1. The COD II filter is the filter of the presentinvention as shown in Fig. 23.
It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacri-ficing its material advantages, the forms hereinbefore described being merely preferred embodiments thereof.
,~:
.
~,J
'"*~
Claims (14)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of making smoke filters comprising the steps of: (a) providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) providing a filtering material including a multiplicity of fi-brous elements; (c? continuously passing said inner member through an elongated bonding zone and defining an annular space around said inner member in said bonding zone; (d) con-tinuously passing said filtering material into and through said annular space and, intermediate the passage of said fil-tering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, thereby forming an elongated, smoke-permeable outer member de-fining a tortuous path for passage of smoke therethrough; and (e) transversely severing the resulting product at selected locations to form filter elements.
2. The method of claim 1, wherein said inner member is formed by extruding a plastic tube and crimping the same at intervals corresponding to one end of the resulting filter elements.
3. The method of claim 1, wherein said filtering ma-terial comprises cellulose acetate tow and wherein said bond activating agent comprises steam.
4. A method of making smoke filters comprising: (a) providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) providing a filtering material in the form of a filter paper overwrapping material in sheet form; (c) overwrapping said inner member with said filtering material to form an outer member around the circumference of said inner member; and (d) transversely severing the resulting product at selected locations to form filter elements.
5. The method of claim l, wherein said inner member is provided as a multiplicity of discrete inner members, and herein said discrete inner members are fed in axially spaced relationship into said bonding zone to form an elongated, smoke-permeable outer member having disposed therein discrete inner members successively joined at their end portions by the filtering material of said outer member.
6. The method of claim 2, which further includes pro-viding a plurality of perforations around the periphery of the uncrimped portion of said inner member.
7. A method of making smoke filters comprising the steps of: (a) providing a multiplicity of axially elongated inner members each of said inner members being in the form of a self-sustaining dimensionally stable reconstituted tobacco member comprising a coherent sheet of reconstituted tobacco compacted and bonded together; (b) providing a filtering ma-terial including a multiplicity of fibrous elements; (c) con-tinuously passing said discrete inner members in axially spaced relationship through an elongated bonding zone and de-fining an annular space around said inner members in said bonding zone; (d) continuously passing said filtering material into and through said annular space and, intermediate the pas-sage of said filtering material through said bonding zone, con-tacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, thereby forming an elongated, smoke-permeable outer member defining a tortuous path for passage of smoke therethrough and with said bonded fibrous material also filling the spaces between the successive discrete inner members; and (e) transversely severing the resulting product at selected locations to form filter elements.
8. Apparatus for making smoke filters comprising:
(a) means for providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) means fox providing a source of a filtering material including a multiplicity of fibrous elements; (c) means for continuously passing said inner member through an elongated bonding zone and defining an annular space around said inner member in said bonding zone; (d) means for continuously passing said filter-ing material into and through said annular space in said bond-ing zone; (e) means for feeding a bond activating agent into said bonding zone and into contact with said filtering mater-ial to bond said fibrous elements to each other at spaced con-tact points thereby forming an elongated, smoke-permeable, outer member defining a tortuous path for passage of smoke therethrough; and (f) means for transversely severing the re-sulting product at selected locations to form filter elements.
(a) means for providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) means fox providing a source of a filtering material including a multiplicity of fibrous elements; (c) means for continuously passing said inner member through an elongated bonding zone and defining an annular space around said inner member in said bonding zone; (d) means for continuously passing said filter-ing material into and through said annular space in said bond-ing zone; (e) means for feeding a bond activating agent into said bonding zone and into contact with said filtering mater-ial to bond said fibrous elements to each other at spaced con-tact points thereby forming an elongated, smoke-permeable, outer member defining a tortuous path for passage of smoke therethrough; and (f) means for transversely severing the re-sulting product at selected locations to form filter elements.
9. The apparatus of claim 8, wherein said means for providing an axially elongated inner member comprises means for extruding a plastic tube and crimping the same at inter-vals corresponding to one end of the resulting filter elements.
10. The apparatus of claim 8, wherein said filtering material comprises cellulose acetate tow wherein said bond activating agent comprises steam.
11. Apparatus for making smoke filters comprising:
(a) means for providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) means for providing a filtering material in the form of a fil-ter paper overwrapping material in sheet form; (c) means for overwrapping said inner member with said filtering material to form an outer member around the circumference of said inner member; and (d) means for transversely severing the resulting product at selected locations to form filter elements.
(a) means for providing an axially elongated inner member of a material which is impermeable to the passage of smoke; (b) means for providing a filtering material in the form of a fil-ter paper overwrapping material in sheet form; (c) means for overwrapping said inner member with said filtering material to form an outer member around the circumference of said inner member; and (d) means for transversely severing the resulting product at selected locations to form filter elements.
12. The apparatus of claim 8, further including means for providing said inner member as a multiplicity of discrete inner members, and including means for passing said discrete inner members in axially spaced relationship into said bonding zone to form an elongated, smoke-permeable outer member having disposed therein discrete inner members successively joined at their end portions by the filtering material of said outer member.
13. The apparatus of claim 9 which further includes means for providing a plurality of perforations around the periphery of the uncrimped portion of said inner member.
14. Apparatus for making smoke filters comprising:
(a) means for providing a multiplicity of axially elongated inner members, each of said inner members being in the form of a self-sustaining dimensionally stable reconstituted tobac-co member comprising a coherent sheet of reconstituted tobacco compacted and bonded together; (b) means for providing a fil-tering material including a multiplicity of fibrous elements;
(c) means for continuously passing said discrete inner members in axially spaced relationship through an elongated bonding zone and defining an annular space around said inner members in said bonding zone; (d) means for continuously passing said filtering material into and through said annular space and, intermediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, thereby forming an elon-gated, smoke-permeable outer member defining a tortuous path for passage of smoke therethrough and with said bonded fibrous material also filling the spaces between the successive dis-crete inner members; and (e) means for transversely serving the resulting product at selected locations to form filter elements.
(a) means for providing a multiplicity of axially elongated inner members, each of said inner members being in the form of a self-sustaining dimensionally stable reconstituted tobac-co member comprising a coherent sheet of reconstituted tobacco compacted and bonded together; (b) means for providing a fil-tering material including a multiplicity of fibrous elements;
(c) means for continuously passing said discrete inner members in axially spaced relationship through an elongated bonding zone and defining an annular space around said inner members in said bonding zone; (d) means for continuously passing said filtering material into and through said annular space and, intermediate the passage of said filtering material through said bonding zone, contacting same with a bond activating agent to bond said fibrous elements of said filtering material to each other at spaced contact points, thereby forming an elon-gated, smoke-permeable outer member defining a tortuous path for passage of smoke therethrough and with said bonded fibrous material also filling the spaces between the successive dis-crete inner members; and (e) means for transversely serving the resulting product at selected locations to form filter elements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000424206A CA1159742A (en) | 1980-05-27 | 1983-03-22 | Tobacco smoke filter having improved tar/carbon monoxide ratio |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/153,560 US4357950A (en) | 1980-05-27 | 1980-05-27 | Tobacco smoke filter having improved tar/carbon monoxide ratio |
| US153,560 | 1980-05-27 | ||
| CA000361646A CA1147629A (en) | 1980-05-27 | 1980-10-06 | Tobacco smoke filter having improved tar/carbon monoxide ratio |
| CA000424206A CA1159742A (en) | 1980-05-27 | 1983-03-22 | Tobacco smoke filter having improved tar/carbon monoxide ratio |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159742A true CA1159742A (en) | 1984-01-03 |
Family
ID=27166837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000424206A Expired CA1159742A (en) | 1980-05-27 | 1983-03-22 | Tobacco smoke filter having improved tar/carbon monoxide ratio |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1159742A (en) |
-
1983
- 1983-03-22 CA CA000424206A patent/CA1159742A/en not_active Expired
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