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
  • A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
  • A24D3/06—Use of materials for tobacco smoke filters
  • A24D3/16—Use of materials for tobacco smoke filters of inorganic materials
  • A24D3/163—Carbon
• • 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
  • A24D3/00—Tobacco smoke filters, e.g. filter-tips, filtering inserts; Filters specially adapted for simulated smoking devices; Mouthpieces for cigars or cigarettes
  • A24D3/06—Use of materials for tobacco smoke filters
  • A24D3/14—Use of materials for tobacco smoke filters of organic materials as additive
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/30—Active carbon
  • C01B32/354—After-treatment
  • C01B32/372—Coating; Grafting; Microencapsulation

Definitions

• the present invention relates to activated carbon which is treated to reduce the presence of fine particles in smoking articles.
• activated carbon is treated to reduce the formation and presence of fine particles in smoking articles.
• the surface of the activated carbon is modified to improve the mechanical integrity of the activated carbon and thus decrease the propensity of the activated carbon to form fine particles.
• the surface of the activated carbon is also modified to attach or fasten existing fine particles to the activated carbon to reduce the presence of fine particles.
• the surface of the activated carbon can be modified by forming a hydrocarbon compound layer, a polymer layer or a carbon layer on external and internal surfaces of the activated carbon.
• a method of manufacturing a cigarette comprises forming surface-modified activated carbon by providing activated carbon having fine carbon particles on surfaces thereof; and forming a layer on internal and external surfaces of the activated carbon, wherein the layer comprises hydrocarbon compound, carbon or polymer on the activated carbon, wherein if the layer is polymer, the polymer is about 9-20 wt % of the surface-modified activated carbon total weight; incorporating the surface-modified activated carbon into a cigarette filter; and attaching the cigarette filter to a tobacco rod to form a cigarette.
• Activated carbon is a generic term used to describe a family of carbonaceous adsorbents with an extensively developed internal pore structure.
• Activated carbon can be produced by activating an amorphous (non-graphitic) carbon, wherein amorphous (non-graphitic) carbon can be produced by carbonizing a precursor, such as wood, lignite, coal, coconut husk, peat, pitch, polymers, cellulose fibers, or polymer fibers, etc., to form char.
• a precursor such as wood, lignite, coal, coconut husk, peat, pitch, polymers, cellulose fibers, or polymer fibers, etc.
• carbonization is carried out at high temperatures, i.e., 300-1000° C., preferably above 600° C. in an inert atmosphere.
• Activated carbon may include a distribution of micropores, mesopores and macropores.
• microporous generally refers to such materials having pore sizes of about 20 ⁇ or less, while the term “mesoporous” generally refers to such materials with pore sizes of about 20 to 500 ⁇ .
• macropores refers to pore sizes above 500 ⁇ .
• the relative amounts of micropores, mesopores and macropores can be pre-selected relative to the selected components from mainstream tobacco smoke that are to be targeted and removed. Thus, the pore sizes and pore distribution can be adjusted accordingly as needed for a certain application.
• the activated carbon can be surface-modified by forming a layer of hydrocarbon compound, such as a wax, onto the activated carbon, wherein the hydrocarbon compound can adhere to external and internal surfaces of activated carbon.
• the hydrocarbon compound can strengthen the activated carbon by increasing the mechanical integrity of the activated carbon, as well as fasten fine particles by coating the fine particles into the layer.
• a carbon coated activated carbon can be formed with the increased mechanical strength from the pitch precursor carbon layer with decreased cost by providing a base of less expensive coconut husk precursor activated carbon.
• the hydrocarbon compound can be formed on internal and external surfaces of the activated carbon. This is done by first, forming a liquid solution, preferably a homogeneous liquid solution, by melting or dissolving the hydrocarbon compound in a solvent or solvent mixture. Next, the activated carbon can be suspended in the liquid solution to impregnate the hydrocarbon compound into the activated carbon, thus covering the internal and external surfaces of the activated carbon with the hydrocarbon compound. Next, the solvent can be removed by evaporating or extracting the solvent from the activated carbon to form a hydrocarbon compound layer, preferably a thin, uniform thickness layer, on internal and external surfaces of the activated carbon.
• a viscous wax layer can be formed on activated carbon, wherein the viscous wax layer sticks to both the activated carbon and the fine particles, and the viscous wax layer also increases the mechanical strength of the activated carbon because of its viscosity.
• the hydrocarbon compound is either non-polar or weakly polar to minimize surface tension between the hydrocarbon compound layer and the activated carbon, which is often weakly polar.
• non-polar or weakly polar hydrocarbon compounds By using non-polar or weakly polar hydrocarbon compounds, an improved uniformity of the layer can be realized based on the polarity. Additionally, the non-polarity or weak polarity of the hydrocarbon compounds can change the selectivity of the activated carbon to target non-polar or weakly polar smoke constituents.
• the amount of polymer coated on the activated carbon is about 9 to 20 wt % of the total polymer coated activated carbon weight in order to provide mechanical strength, while still providing accessibility to the pores and thus the activated carbon smoke adsorption properties.
• the polymer is preferably provided in about 10-18%, 11-17 wt %, 12-16 wt %, 10-12 wt %, 12-14 wt %, 14-16 wt %, 16-18 wt % or 18-20 wt % to balance the mechanical strength of the activated carbon with the adsorption properties of the activated carbon.
• the polymer layer can possess electrical charges capable of trapping fine particles with electrical forces, such as by static electricity force.
• polymers examples include, but are not limited to: synthetic polymers, such as polypropylene, polyethylene, silicone polymer, poly(ethylene oxide), poly(ethylene glycol), poly(acrylic acid), poly(vinyl acetate), poly(vinyl alcohol), various block poly(ethylene oxide)-poly(propylene oxide)copolymers, other copolymers or other block copolymers or their derivatives and/or natural polymers, such as pectin, alginate or starch.
• synthetic polymers such as polypropylene, polyethylene, silicone polymer, poly(ethylene oxide), poly(ethylene glycol), poly(acrylic acid), poly(vinyl acetate), poly(vinyl alcohol), various block poly(ethylene oxide)-poly(propylene oxide)copolymers, other copolymers or other block copolymers or their derivatives and/or natural polymers, such as pectin, alginate or starch.
• Exemplary solvents or co-solvents preferably have relatively low boiling points, and can solvate the exemplary polymers listed above, for example, exemplary solvents include, but are not limited to: water, alcohol, such as methanol or ethanol, or hexane.
• the layered activated carbon can be stabilized by heating according to a predetermined heating schedule, such that the aromatic compounds can be converted into a stabilized, infusible form prior to carbonization.
• the stabilized, infusible form aromatic compounds can be carbonized by heat treating the stabilized, infusible form aromatic compounds on the activated carbon in an inert environment. By carbonizing the stabilized, infusible form aromatic compounds, a new carbon layer can thereby be formed on the surfaces of the activated carbon.
• aromatic compounds examples include, but are not limited to: petroleum pitches, coal tar pitches and pine tar pitches, other natural or synthetic aromatic compounds, and mixtures thereof. These aromatic compounds are preferred because of their high density, which in turn after carbonization, leads to higher mechanical strength carbon than can be achieved by carbonizing lower density carbonaceous precursors. Thus, by coating and carbonizing a pitch precursor on a lower density precursor activated carbon, the higher mechanical strength of a carbonized pitch can be provided on a lower cost, lower density precursor activated carbon.
• a cigarette typically contains two sections, a tobacco-containing portion often referred to as the tobacco or cigarette rod, and a filter portion, which may be referred to as a filter tipping.
• the tipping paper overlaps an end portion of the tobacco rod to hold the filter and tobacco rod together.
• the tobacco rod, or tobacco containing element of the cigarette typically includes a cigarette wrapping paper in which shreds of tobacco is wrapped with an adhesive holding the seams of the paper together.
• mainstream smoke includes the mixture of gases and/or aerosols passing down a smoking article, such as a tobacco rod, and issuing from an end, such as through the filter end, i.e., the amount of smoke issuing or drawn from the mouth end of a cigarette during smoking of the cigarette.
• the mainstream smoke contains air that is drawn in through the heated region of the cigarette and through the paper wrapper.
• the tobacco is normally used in the form of cut filler, i.e., in the form of shreds or strands cut into widths ranging from about 1/10 inch to about 1/20 inch or even about 1/40 inch.
• the lengths of the strands range from between about 0.25 inch to about 3.0 inches.
• the cigarettes may further comprise one or more flavors, as described above, or other additives (e.g., burn additives, combustion modifying agents, coloring agents, binders, etc.).
• Mono filters typically contain cellulose acetate tow or cellulose paper materials. Pure mono cellulose filters or paper filters offer good tar and nicotine retention, and are highly degradable.
• Dual filters typically comprise a cellulose acetate mouth end and a pure cellulose or cellulose acetate segment. The length and pressure drop of the segments in a dual filter may be adjusted to provide optimal sorption, while maintaining acceptable draw resistance.
• Triple filters may include mouth and smoking material or tobacco side segments, and a middle segment comprising paper.
• Cavity filters include two segments, e.g., acetate-acetate, acetate-paper or paper-paper, separated by at least one cavity.
• Recessed filters include an open cavity on the mouth side.
• the surface-modified activated carbon is provided in filters of the smoking articles, as mentioned above.
• the filters may also be ventilated and/or may include in addition to the surface-modified activated carbon, other sorbents, catalysts or other additives suitable for use in filters of smoking articles.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Cigarettes, Filters, And Manufacturing Of Filters (AREA)
• Carbon And Carbon Compounds (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

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Cited By (21)

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Citations (25)

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• 2004
  • 2004-12-30 US US11/025,818 patent/US20060144410A1/en not_active Abandoned
• 2005
  • 2005-12-29 MX MX2007008005A patent/MX2007008005A/es active IP Right Grant
  • 2005-12-29 WO PCT/IB2005/004100 patent/WO2006070291A2/en active Application Filing
  • 2005-12-29 UA UAA200708306A patent/UA89069C2/ru unknown
  • 2005-12-29 EA EA200701415A patent/EA011784B1/ru not_active IP Right Cessation
  • 2005-12-29 EP EP05849375A patent/EP1835820A2/en not_active Withdrawn
  • 2005-12-29 CN CN2005800452953A patent/CN101094598B/zh not_active Expired - Fee Related
  • 2005-12-29 BR BRPI0519453-9A patent/BRPI0519453A2/pt not_active IP Right Cessation
  • 2005-12-29 AU AU2005321022A patent/AU2005321022B2/en not_active Ceased
  • 2005-12-29 JP JP2007548920A patent/JP4916453B2/ja not_active Expired - Fee Related
  • 2005-12-29 KR KR1020077017624A patent/KR20070095380A/ko active IP Right Grant
• 2007
  • 2007-05-16 ZA ZA200703942A patent/ZA200703942B/xx unknown

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