Classifications

• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24D—CIGARS; CIGARETTES; TOBACCO SMOKE FILTERS; MOUTHPIECES FOR CIGARS OR CIGARETTES; MANUFACTURE OF TOBACCO SMOKE FILTERS OR MOUTHPIECES
  • A24D1/00—Cigars; Cigarettes
  • A24D1/02—Cigars; Cigarettes with special covers
  • A24D1/025—Cigars; Cigarettes with special covers the covers having material applied to defined areas, e.g. bands for reducing the ignition propensity

Definitions

• the present invention relates to a method of producing a smoking article wrapper and a smoking article wrapper obtainable by the method.
• a "low ignition propensity" smoking article is one that has been designed to be less likely than a conventional cigarette to ignite soft furnishings such as a couch or mattress. Ideally, a low ignition propensity smoking article will continue to burn when freely suspended such as in the holder of an ashtray or when being held in the hand without puffing ("free burn"). The tendency for a cigarette to go out during free burn is referred to as "self extinguishment”. Attempts have been made in the art to produce a smoking article with reduced ignition propensity by designing a smoking article wrapper with rings of reduced porosity and/or reduced diffusion of oxygen.
• the rings are applied to the wrapper by a printing an additive or combination of additives as transverse bands on to a "jumbo" roll of a preformed cigarette wrapper.
• the additive is applied with an aqueous or non-aqueous liquid carrier which evaporates from the wrapper once the additive has been delivered.
• the physical parameters of the wrapper such as tensile strength, burst strength, elongation and stretch, need to be preserved in order for the wrapper to maintain its integrity when transported through the printing process.
• over wetting of the wrapper by the addition of carrier liquids during the printing process has a detrimental effect on the physical properties of the wrapper, for example, by reducing its tensile strength which in turn causes breakages within its structure.
• the printing process needs to be stopped from time to time when the paper breaks in order to repair or replace the wrapper which is time consuming and expensive.
• liquid carrier systems can be detrimental to the visual finish of the wrapper and hence the finished smoking article.
• wetting a cigarette wrapper can lead to "cockling", an effect whereby the surface of the wrapper undergoes a cycle of expansion and contraction due to uptake and removal of carrier liquid causing it to become uneven or wrinkled.
• the expansion/contraction cycles may also cause the wrapper to shrink during the printing process.
• Shrinking in the cross direction can lead to difficulties in alignment, for example during the subsequent slitting process, resulting in unacceptable wrapper quality.
• a smoking article typically involves a longitudinal overlap seam comprising two layers of wrapper held together by an adhesive. Due to the make up of this overlap seam, the addition of an additive to this region does not significantly reduce the permeability or oxygen diffusibility and hence does not significantly alter ignition propensity characteristics of the cigarette.
• an aim of the present invention is to overcome the problems associated with the prior art methods.
• an aim of the present invention is to provide a method of producing a wrapper for a smoking article with acceptable self- extinguishment and low ignition propensity characteristics, but during such process the physical integrity of the wrapper is maintained and the final smoking article is visually acceptable.
• the present invention provides a method of producing a wrapper for a smoking article comprising the steps of:
• the present invention provides a wrapper for a smoking article comprising regions of one or more additives applied to its surface which regions have reduced porosity and/or reduced oxygen diffusion sufficient to reduce the ignition propensity of the smoking article and regions having substantially reduced or zero additive such that the wrapper maintains its physical integrity during processing and had improved visual appearance by reduced wrinkling, wherein the regions of the wrapper with substantially reduced or zero additive form the overlap area along its gluing seam when incorporated into the smoking article.
• the present invention provides a smoking article comprising a wrapper obtainable by a process of the present invention.
• wrapper for a smoking article is to be understood in a broad sense.
• a typical example is a cigarette paper.
• Another example is a tobacco roll wrapper.
• Further examples include a cigar having a wrapper, a cigarillo and a fine-cut tobacco unit wrapper.
• machine direction is understood to mean in the machine direction through which the wrapper passes during the processing steps including unwinding, application of additive, slitting and formation of the smoking article.
• cross direction is understood to mean perpendicular to the machine direction through which the wrapper passes during application of additive.
• substantially reduced in relation to regions of additive means that such areas have generally less additive than those areas which have reduced porosity and/or reduced oxygen diffusion. Such regions of “substantially reduced” additive typically have 50% less additive, preferably 80% and even more preferably 90% less additive, than the areas which have reduced porosity and/ore reduced oxygen diffusion.
• pattern is understood to mean the configuration which the regions of additive form around the circumference of the smoking article when the wrapper is machined to form a smoking article.
• the pattern is generally a ring configuration.
• the ring configuration may be formed by two or more discontinuous areas of applied additive, or by a continuous region of applied additive which is not applied at the gluing seam.
• the areas of applied additive may be in a zig-zag conformation generally configured in the shape of a ring when the wrapper is formed in to the smoking article.
• the wrapper may be supplied from a storage roll, a so called jumbo-roll.
• the wrapper supplied from the storage roll may have a width of up to a few meters.
• the width of the wrapper is determined by its manufacturing process and is generally trimmed to the desired wrapper width before incorporation into the wrapper manufacturing process.
• the width of each individual wrapper may be 26.75mm which corresponds to the circumference of a typical cigarette plus the width of the gluing seam of the wrapper.
• the jumbo roll may have a width of one or more multiples of the standard 26.75mm width plus edge trimmings the dimension of which varies dependent upon the original supplied material.
• Such a jumbo roll may be cut after the additive is applied to the required dimensions for incorporation in to the smoking article.
• a longitudinal overlap seam comprising two layers of wrapper held together by an adhesive.
• this overlap region can vary from 1 .5mm to 3mm wide and for standard size cigarettes the overlap region is approximately 2mm wide.
• the method of the present invention may be applied to the manufacture of individual smoking papers. Such smoking papers are used by consumers who make ("roll") their cigarettes from a supply of tobacco and individual rolling papers provided in a booklet containing folded and interleaved rolling paper sheets.
• the method of the present invention may be used in a smoking article rod making machine during the manufacture of smoking article rods. Generally, existing commercial smoking rod making machines may be equipped with the necessary means to carry out the present invention.
• the additive may be applied to the wrapper by any printing method typically used in the field. Preferably, gravure printing is used which allows for a much higher level of printing quality and for large block areas of colour/additive to be uniformly applied. Gravure printing may be used on line in the printing process.
• the additive is applied to the wrapper at a print station within a printing machine.
• the additive is applied as a series of discontinuous lines in the cross direction to form areas of applied additive and areas of substantially reduced or zero additive. These areas of substantially reduced or zero additive in the cross direction correspond to the areas of the wrapper which form the overlap region at the gluing seam when the wrapper is incorporated in to the smoking article.
• the complete pattern of additive can be applied at a single print station or applied at two or more print stations within a single printing machine.
• multiple pass printing may be used.
• the surface pattern of the wrapper is formed by single pass through the printing machine whereby multiple print stations each produce a subset of the overall printing pattern in the machine direction.
• Such use of multiple printing stations in a single pass provides the further benefit of minimising the area of the base wrapper onto which the additive is printed and hence minimises the area where the physical properties of the base wrapper are reduced at any given time in the printing process.
• each station applies additive to only part of the base wrapper with the sum of the applications from the individual print station equalling the complete pattern of additive over the base wrapper.
• each print station is spaced apart along the machine direction of the wrapper such that the physical properties of the wrapper may be sufficiently restored after passing through one print station and drying station before further additive is applied to the wrapper.
• the average physical properties of the wrapper are maintained to enable effective and efficient processing.
• the additive is applied to the wrapper as two or more discontinuous lines such that the applied regions of additive from adjacent discontinuous lines are arranged in columns across the machine direction of the wrapper and spaced apart with regions of substantially reduced or zero additive.
• Substantially reduced of zero additive is applied in the region of the wrapper which forms the overlap along its gluing seam when incorporated in to the smoking article.
• the regions of applied additive may be aligned across the width of the wrapper.
• the applied regions of additive may be offset from adjacent applied regions of additive to form a staggered pattern. The extent of this offset between adjacent applied regions of additive and in totality can be further optimised to maximise the residual physical properties of the wrapper.
• each individual region of applied additive may be offset at an angle perpendicular to the machine direction of the jumbo roll.
• the regions of print additive may be offset at an angle of up to 15° from perpendicular to the machine direction. More preferably the angle of offset is up to 10° and most preferably it is 5°. This can be beneficial in improving the durability of print rollers used in the print stations.
• excess liquid carrier may be removed from the surface the printing roller by means of a doctor blade, running essentially perpendicular to the machine direction.
• Cross direction printing patterns typically used to produce wrapper having leading and trailing edges coincident with the doctor blade. The pressure exerted by the doctor blade effectively reduces cylinder life.
• One benefit of such an offset is that the leading edge of the printing pattern does not coincide with the leading edge of a doctor blade used in typical printing stations thereby reducing wear on the blade and reducing the chance of tearing of the wrapper as it passes through and from the doctor blade.
• a further benefit is that the transfer of additive within a region of printing typical in the art is made more efficient by the use of such an offset.
• the angle and direction of offset may be varied between discrete regions of printing or be consistent throughout the total printing pattern.
• the regions of applied additive typically have a width corresponding to width of the final wrapper used to produce the smoking article or multiples thereof less the regions of the wrapper which form the overlap at the gluing seam when the wrapper is incorporated into the smoking article.
• the regions of applied additive from continuous transverse sections across this width minus any overlap region at the edges.
• the additive region forms a ring around the circumference of the smoking article but not at the gluing seam of the wrapper.
• the region of the final wrapper used to form the overlap in the smoking article is left essentially unprinted or printed at substantially reduced levels.
• the width of these regions of reduced additive are typically up to a maximum of twice the overlap width of the wrapper incorporated in to the final smoking article.
• the overlap seam in a smoking article typically comprises two layers of the wrapper held together by an adhesive; the addition of an additive to this overlap region does not significantly reduce the permeability or oxygen diffusibility and hence does not significantly alter ignition propensity characteristics of the cigarette.
• the regions of applied additive are generally from 4 to 12mm wide.
• the regions of applied additive are 5-10mm wide, and most preferably 6 ⁇ 9mm wide
• the regions of reduced additive in the machine direction are generally less than 30 mm wide, more preferably from 10 to 30mm wide. Most preferably the regions of reduced additive are 18-20 mm wide.
• the overall pattern on the jumbo has continuous zones of reduced or zero additive across its entire surface in both the machine and cross directions. As these areas have little carrier liquid applied to them, the physical properties remain similar to the original jumbo roll wrapper. Thus the final printed wrapper may be considered as a continuous mesh of unprinted wrapper with isolated regions of additive. While the physical properties of the printed regions may be reduced, overall the wrapper retains its integrity through the residual mesh of unprinted wrapper.
• the additives applied to the wrapper may be applied with a liquid carrier.
• the liquid carrier is in the form of a solution, suspension, emulsion or combination thereof.
• the liquid carrier is aqueous, non-aqueous or a combination thereof and may contain an emulsifying agent depending on the nature of the additives.
• a suspension of additive may be applied within an aqueous carrier.
• the aqueous carrier penetrates the wrapper transporting the additive into the matrix of the wrapper. Once the carrier evaporates, the additive is left within the wrapper matrix where it can reduce the porosity and/or oxygen diffusibility either before or during the burning of the smoking article.
• the liquid carrier is allowed to evaporate allowing the wrapper to dry and for the additive to set within the matrix of the wrapper.
• the evaporation process may occur naturally or may be aided by the application of an external heat source or forced air movement to the surface of the wrapper at a "drying station".
• the external heat source is selected from heated contact rollers, hot air drying, microwave drying, radio frequency drying, infrared lamps or combinations thereof.
• the drying station may be positioned at any point along the length of the wrapper as it is processed.
• a drying station is provided between adjacent print stations.
• the wrapper is allowed to dry after application of the additive in the liquid carrier from a first print station before further additive is applied from second and subsequent print stations. This configuration is advantageous since it allows the integrity of the wrapper to be maintained after addition of additive by a print station before being processed by subsequent print stations.
• the additives that may be applied to the wrapper may be any of those used in the art to reduce the ignition propensity of smoking articles.
• the additive is selected from alginates, polyvinyl alcohol, polyvinyl acetates including partially hydrolysed derivatives and copolymers, modified and unmodified starches, cellulose derivatives such as carboy-methyl cellulose, ethyl-cellulose and hydroxymethyl-cellulose, pectins and combinations thereof.
• the additive further comprises inorganic ions such as phosphates, mono or divalent metal salts, silicas and other agents know in the art to modify the burn rate and combinations thereof.
• the base wrapper is machined to produce a wrapper which upon in incorporation into the smoking article.
• Figure 1 is a schematic drawing of a standard machine for printing additive on to cigarette wrappers to which the method of the present invention may be carried out;
• Figure 2 is a schematic drawing of three consecutive print stations and associated heat sources
• Figure 3 is a schematic drawing of a jumbo wrapper having multiple discontinuous lines of printed additive regions applied obtainable by a method of the present which is slit to making widths of wrapper;
• Figure 4 is an alternative jumbo wrapper obtainable by a method of the present invention.
• Figure 5 is a further alternative jumbo wrapper obtainable by a method of the present invention.
• Figures 6a and 6b is a graph of the distribution of additive loading levels in the cross direction of the wrapper
• Figure 7 is a graph of an alternative distribution of additive loading levels in the cross direction of the wrapper;
• Figures 8a and 8b are graphs of alternative distributions of additive loading levels in the machine direction of the wrapper;
• Figure 9 is a schematic drawing of a final wrapper showing the additive pattern and the wrapper incorporated in to a smoking article with annular rings of additive except in the overlap region.
• a typical printing machine 1 comprises a compartment 2 for holding a jumbo roll 3 of wrapper 4, a series of rollers 5 and a series of print stations 6.
• Additive is applied to the surface of the wrapper as it passes through the each print station 6.
• the printing machine comprises multiple printing stations 6 arranged along the length of the unwound wrapper 4. As the wrapper 4 passes through the first printing station additive is applied to the surface of the wrapper 4 to form discrete regions of additive 7 in the cross direction corresponding to the width of the finished smoking article wrapper less the overlap region interspersed with regions of reduced or no additive 8.
• the regions of additive 7 from an individual printing station 6 take the form of columns in the machine direction.
• subsequent columns of additive regions are applied to the surface of the wrapper adjacent to the first column in the machine direction of the wrapper 4.
• Multiple lines may be sequentially printed on to the surface of the wrapper by passing through consecutive print stations 6.
• the fully printed wrapper retains continuous regions in the machine direction of substantially reduced or zero additive corresponding to the area of the wrapper which will form the overlap at the gluing seam when the wrapper is incorporated in to the smoking article.
• a drying station incorporating a heat source 9 is positioned between adjacent printing stations 6 such that when the wrapper 4 emerges from a print station it passes through the drying station 9 and the liquid carrier in which the additive is loaded evaporates from the surface of the wrapper 4. As a result, the integrity of the wrapper 4 is maintained before it enters the next print station 6 and further liquid carrier is applied to its surface.
• the additive carrier causes the additive to be drawn in to the matrix of the wrapper such that when the carrier evaporates from the wrapper the additive is impregnated within the matrix of the wrapper.
• a wrapper according to a first aspect of the present invention is shown in Figure 3.
• the additive is printed on to the surface of the wrapper 4.
• the use of a suitable liquid carrier which penetrates the matrix of the wrapper causes the additive to be pulled in to the wrapper matrix such that it does not settle on the surface of the wrapper but impregnates the matrix of the wrapper.
• the fully printed wrapper retains continuous regions of substantially reduced or zero additive corresponding to the overlap area of the final wrapper and discrete columns of printing.
• the printing pattern remains consistent with that required for reduced ignition propensity performance.
• the printed regions of additive 7 have dimensions of 4-12mm width whilst the regions of reduced or no additive 8 are 10 ⁇ 30mm wide.
• the printed regions of additive have dimensions equating to the width of the final wrapper less the overlap region.
• wrapper 4 After the wrapper 4 emerges from the printing machine 6 with the additive printed on to its surface it is machined to form an individual wrapper 12 which is incorporated in to the final smoking article 13. Individual columns of printing in the machine direction plus their surrounding envelopes may be cut in the machine direction by a slitting machine 11 to from individual wrappers as shown in figure 3.
• the wrapper making width has multiple continuous additive lines across its width with substantially reduced or zero printing at the edges.
• the printing stations 6 are configured such that the columns of regions of additive 7 formed in the machine direction by printing multiple series of discontinuous lines are offset between adjacent columns.
• the printing stations 6 are arranged such that the regions of additive 7 are printed on to the surface of the wrapper at an angle of up to 15° from the perpendicular to the machine direction.
• the distribution of additive loading levels in the cross direction of the base wrapper 4 may be constant in a region of applied additive 7 as shown in Figure 6a such that there is substantially reduced or no additive applied at the outermost edges of the individual wrapper 12 when the wrapper 4 is slit.
• This distribution of additive loading is repeated cyclically in the cross direction of the wrapper 4 at each region of applied additive 7.
• the additive may be applied in increasing concentration in the cross direction of the wrapper 4 to a maximum level such that the region of applied additive 7 has maximum concentration of additive in an area at the centre of the individual wrapper 12 when the wrapper 4 is slit.
• the additive is applied in reducing concentration in the cross direction to reach a minimum level at the centre of the overlap region of the final wrapper 12.
• the distribution of additive loading levels in the machine direction of the base wrapper 4 can be varied as shown in figures 8a & 8b.
• discontinuous printing of additive and multiple print stations 6 interspersed with heating sources allows the wrapper 4 to maintain its physical integrity during processing.
• the printing process is therefore not interrupted to repair any tears that may appear in the wrapper due to over wetting when applying the additive and shrinkage of the wrapper is minimised.
• the wrapper 4 is generally less wet during the process of the invention compared to prior art methods, the wrapper does not experience "cockling" and the final smoking article has an improved appearance.
• the complete process of taking a width of base paper, printing discontinuous regions of additive, drying, machining to wrapper width and forming smoking articles can be integrated into a sequential or on-line process by the suitable modification of currently existing cigarette making machinery.

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• Cigarettes, Filters, And Manufacturing Of Filters (AREA)
• Paper (AREA)

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Citations (7)

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• 2010
  • 2010-12-03 WO PCT/EP2010/068887 patent/WO2011067396A1/en active Application Filing
  • 2010-12-03 JP JP2012541526A patent/JP5809638B2/ja not_active Expired - Fee Related
  • 2010-12-03 EP EP10785434.1A patent/EP2512272B1/en not_active Not-in-force
  • 2010-12-03 EA EA201200852A patent/EA025115B1/ru not_active IP Right Cessation

Patent Citations (7)

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