PH26618A - Wrapper for smoking articles and method for preparing same - Google Patents

Description

/ jl . ; / | | . ~~ 26618 ’

WRAPPER FOR SMOKING ARTICLES AND

. METHOD FOR PREPARING SAME

BACKGROUND OF THE INVENTION

. 1. Field Of The Invention " The present invention relates to the manufacture of wrappers for smoking articles such as cigarettes;

More particularly, this invention relates to the use of ) gels produced by a solution-gelation or "sol-gel"

Co process for controlling the combustion of wrappers for smoking articles. In one embodiment, the gels made hy this process are applied as coatings to paper fibers hefore the paper ig formed into wrappers for smoking’ . articles. The coated paper wrappers of this invention ‘ are useful in reducing or preventing combustion of the - wrappers of smoking articles. The wrappers are also, ugeful in controlling the mass burn rate af cigarettes. 2. Description Of Related Art

Co One problem with smoking articles such as rigarettes is the amount of sidestream smoke generated during burning. Sidestream smoke is the smoke generated oo hy cigarettes when they are burning but not being drawn to | upon hy the smoker, as when a cigarette is placed in an ashtray between puffs, Sidestream smoke may he objectionable to non-smokers.

Efforts have heen made to reduce the amount of | .

E ‘aidestream smoke generated hy cigarettes. While these methods may reduce the amount of sidestream smoke, they do not provide the smoker with a cigarette that looks, feels, and tastes the same as conventional cigarettes, a0 1.S. Pat. No. 4,231,377 to Cline et al. ("Cline . | .

BAD ORIGINAL 9 oo Co I

I") refers to a method of reducing sidestream smoke by applying a specified amount of magnesium oxide or magnesium hydroxide in combination with specific chemical "adjuvants" to paper fibers as a filler or : coating. The magnesium salts are applied as a solution.

However, according to U.S. Pat. No. 4,433,697 to Cline et al. ("Cline II") the ash generated hy burning

Co cigarettes made from paper prepared according to the method of Cline I is unacceptable because of its

Co 10 flakiness. Cline II proposes to reduce the flakiness of ‘ the ash by adding ceramic fihers to the paper-making : slurry. The method of Cline IT is problematic hecause . of the substantial cost of the ceramic fibers. A i further short-coming of the proposal of Cline IT is that the ceramic fibers must he added to the paper-making slurry; commercially available cigarette papers cannot be madified according to the proposal after their manufacture, 17.S. Pat, No. 4,450,847 to Owens refers to the use of fine particle size magnesium hydroxide gel in place of the magnesium hydroxide referred to in Cline I and

It. Although Owens characterizes his magnesium hydroxide as a gel, he states that the gel is actually "an apparently homogeneous substance or a dispersion consisting of an aggregate of very small particles in ) very close association with a liquid, and the gel at the concentrations used in this invention is actually broken B into flocs floating in the aqueous medium.” (Col, 3, lines 62-68). Owens’ magnesium hydroxide gel is said to | i

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he used with magnesium oxide or calcium carbonate and =a ) suitable chemical "adjuvant" as in Cline I and II.

Hampl et al., U.K. Patent Application GR 2 191 830

A refers to cigarette papers that have heen formed with

A 5 high superficial surface area fillers. These cigarette papers are stated to yield reduced sidestream smoke when used as wrappers for cigarettes. Filler such as . attapulgite clay, fumed or activated alumina, chalk, fumed silica, and peroxides of magnesium, calcium, and : 10 strontium are said to he useful. Other fillers such as the carbonates, phosphates, sulphates, aluminates, and silicates of certain metals are also said to he useful as long as their superficial surface area exceeds 20m2/¢g. Hampl et Al's method also requires the use of . 15 potassium or sodium calts of varios acids to maintain : the integrity of the cigarette ash.

Apart from the prohlems already noted, the : | modified wrappers of Cline I and 1, Owens, and Hampl et ] al. all suffer from a serious disadvantage the smoking of cigarettes made from paper containing magnesium oxide or magnesium hydroxide produces an off. taste. it is believed that this taste arises from the strongly alkaline nature nf the magnesium and from the other chemicals used.

In addition, the size of the particles employed by

Cline I and 1I, Owens, or Hampl is critical. If the particles are too small, they will he dislodged from the CL wrapper, creating an objectionable dust, If they are too large, they will obstruct the posority of the wrapper, interfering the combustion of the tobacco fuel a . . ’ :

Co | Co BAD ORIGINAL 9

} rod.

Accordingly it is an object of this invention to provide a wrapper for smoking articles which reduces or ' prevents combustion of the wrappers of smoking articles | and which may be incorporated into a smoking article : which has the look, feel, and taste of conventional ‘ smoking articles, ‘ SUMMARY OF THE INVENTION

The present invention solves the problems associated with prior art wrappers for smoking articles hy providing a wrapper with desirable combustion characteristics, yet which may he incorporated into smoking articles that have the look, feel, and taste of conventional cdigarettes, The present invention employs sol-gel processes to form a film of metal oxides that may be applied as a coating on cigarette paper to produce the desired comhustion and subjective characteristics.

A sol-gel process is a soft chemical method of preparative solid state chemistry, The product of the process is an amorphous inorganic network. See generally R. Roy, "Ceramics Ry The Solution-Sol-Gel-

Route," Science, 238, pp. 1664-69 (1987) and H. Schmidt, "Chemistry Of Material Preparation By The Sol-Gel 26 Process," JT. Non-Crystalline Solids, 100, pp. 51-64 {198R), :

KB In one embodiment of this invention, a sol-gel oo process is used to produce a gel of seleated metal oxides that is applied as a film upon the surface of 4 .

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} fibers of conventional cigarette paper. In a further emhaodiment, at least one annular hand of a gel formed hy a sol-gel process according to this invention is applied to the surface of a cigarette in order to produce a cigarette whose mass hurn rate will approach zero when allowed to idle for a predetermined amount of time,

Preferahly, a plurality of discrete hans, each of which substantially circumscribes the periphery of a smoking article, are present. And in a yet further embodiment, the wrapper of a novel smoking article described in . copending U.S. application Ser. No. 07/223,153, filed

July 11, 1988, which is incorporated herein hy reference (hereinafter, "novel smoking article"), is modified with the gels made as described herein in order to prevent 15° combmstion of the wrapper of this novel smoking article. 3 : | . . BRIEF DESCRIPTION OF THE DRAWINGS ’ - . | } The ahove and other ohjects and advantages of the ) . oo ol invent inn will he apparent upon consideration of the

Cn p following detailed description, taken in conjunction - Lo 20 with the accompanying drawings; in which like reference characters refer ta like part throughout , and in which:

FIG, 1 is a longitudinal cross-sectional view of a novel smoking article, : FIG. 2 is a perspective view of a cigarette showing an annulus of a gel of the present invention which has heen applied tao the wrapper.

FIG. 3 is a radial cross-sectional view of the cigarette of FIG. 2, taken from line 3-3 of FIG. 2.

FIGS. 4 and 5 are graphs of the mass burn rates of - 5

BAD ORIGINAL 9 cigarettes made with wrappers to which an annulus of a gel of the present invention has heen applied. : DETAILED DESCRIPTION OF THE

INVENTION

The sol-gel process permits synthesis of homogeneous gels of metal oxides. When dried after ~ application to wrappers for smoking articles, these gels form films. Because dried films produced by a sol-gel process reduce the propensity of smoking articles to : burn, they may be employed to produce self-extinguishing : cigarettes and to substantially eliminate flaming combustion of novel smoking articles. .

The sol-gel process generally consists of the . - following steps: preparation of a solution of a - 15 precursor of a metal oxide, hydrolysis, condensation or gelling, formation, and drying. R. Rov, "Ceramics Ry } The Solution-Sal-Gel Route," Science, 238 pp. 1664, , 1669, 1665 (1987), The state nf the gel resulting from the condensation step is determined hy the extent of hydrolysis and formation. Thus, the specific morphology of the product of the sol-gel process may he controlled hy adjusting the concentration of the reactants, temperature, and pH during the hydrolysis and condensation steps.

The process for preparing the films of the present invention begins with the selection of suitahle metal oxide precursors. It is preferred that these substances are metal alkoxides. In addition to alkoxides, other precursors such as metallic borate and silicate salts, . . a 0

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or alternately, organic or inorganic salts or complexes aE may be employed as metal oxide precursors. :

While the alkoxides of almost every metal in the periodic tahle have heen prepared, the preferred

E 5 starting materials are alkoxides of aluminum, calcium, } titanium, magnesium, and zirconium. In alternative emhodiments, the alkoxides of sodium and potassium may he used, but it is preferred that they he mixed with alkoxides of other metals. When the desired film is - magnesium oxide, it is preferred to form a solution for the snl-gel process from a combination of a magnesium “alkoxide and an aluminum, titanium, or zirconium : alkoxide, The most preferred films comprise oxides of calcium, aluminum, and mixtures of aluminum and magnesium, mixtures of calcium and aluminum, and mixtures of calcium, magnesium, or aluminum with - zirconium, i Water and a suitable acid are added to the metal alkoxide, for example, aluminum alkoxide and preferably - aluminum-sec-butoxide, to initiate hydrolysis while the , mixture is stirred.* Hydrolysis may also he initiated : by the addition of hases, a1though the use of acids is preferred, The acid may an organié¢ or an inorganic acid. Inorganic acids, including hydrochloric, phosphoric, and nitric are preferred, Hydrochloric acid ig particularly preferred. Organic acids, such as acetic, succinic, and citric acids are also within the

Co. scope of this invention. Increasing acidity or hasicity . as well as increasing the temperature cause the an - ‘hydrolysis reactions to occur more rapidly. Moderate . : 7 : r .

BAD ORIGINAL 9) : = conditions are preferred, as the reaction is then easier to control. In commercial embodiments of this invention, it is preferred to conduct this part of the © sol-gel process in an inert atmosphere, such as under a : blanket or stream of nitrogen.

After hydrolysis, the mixture is heated and - continually stirred to initiate condensation. The addition of an acid or a neural salt facilitates the condensation and affects the viscosity of the resulting gel, The acid may he any of the acids used in the hydrolysis step. The neutral salt may be potassium’ acetate, potassium chloride, sodium chloride, ar sodium i - rhosphate. Preferahly, gels have a concentration of } metal oxides of about 12% and a viscosity of ahout 5 to ’ ‘ 15 20 centipoise after completion of the gelation step,

The most preferred gels have a metal oxide concentration oe of about 16 to 18% with attendant increases in

Co viscosity.

After the desired degree of gelation has nccurred, . the mixture is allowed to cool. The resulting gel, in diluted or undiluted form, is applied as a film to paper fibers for use in cigarette wrappers. Gels may be applied by any of a variety of techniques known in the art. Preferably, the gels are applied to wrappers using } ' 25 a size press, rotogravure press, or hlade coater, although they may also be applied hy hand... Following . application of the gel to paper, the gel is dried to form a film upon the paper. Preferably the gel is dried at a temperature of 100° to 150° C. The method of . | 8 / = BAD ORiGluaL. 0 :

Sng h— zi drying may be by any known method such as hy contact with a heated surface,

When used as wrappers for smoking articles, papers modified hy the application of the gels of the present invention have superior burn characteristics when compared with untreated papers, These improvements . : include reduced incidence of flaming combustion and, if desired, complete elimination of combustion. Although } not intending te be bound by theory, it. is believed that during the combustion of gel-coated papers, the ceramics collapse to form a sheath around the paper and tobacdo on ash at the end of the smoking article, This sheath maintains its structural integrity because of the } strength imparted hy the cross-linked structure of the _ 15 dried sal-gel film. The thickness, uniformity in oo ; oo . coverage, and porosity of the sheath, in both the radial

CE Co oe and longitudinal directions, determines the resulting

BN oo oo Co burn characteristics bf the smoking article. .

Y In one emhodiment-of this invention) a cigarette is manufactured according to methods well known in the

B art, except that a wrapper is formed from cigarette ’ paper to vhich a thin and continuous coating of the gels : . So | of this invention has heen applied. This coating may be , applied to cigarette paper hefore cigarettes are | manufactured hy using, for example, size presses, ‘ rotogravure presses, or hlade caters.

In another emhadiment of this invention, an annular coating of the gels of this invention is applied to the paper fibers of the wrapper of a cigarette in at least one separate ring disposed perpendicularly to the : 9 rr - N

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} longitudinal axis of a cigarette, This produces a cigarette that will cease burning if not actively smoked, i.e., drawn upon hy the smoker, for a : predetermined amount of time, Preferably, a plurality of discrete hands, each of which substantially circumscribes the periphery of a smoking article, are employed. This coating is preferahly applied in the form of a gel which is subsequently dried to form a film upon the paper, The gel may he applied directly to . cigarettes or it way be applied to cigarette paper, with a size press, rotogravure press, or a blade coater, which is then used to manufacture : : cigarettes, Such treatment results in a cigarette that will have a mass burn rate approaching zero if : " allowed to idle as when it is placed in an ashtray between puffs. The time required for a cigarette made according to this embodiment to approach cero mass burn rate varies with the location and - thickness of the film applied to the paper fibers.

In vet another embodiment of this invention, a smoking article of the type described in copending U.S. dpplication Ser. No, 07/223,152, filed July 11, 1988, and incorporated herein hy : reference (hereinafter "novel smoking article"), is prepared using cigarette paper manufactured in accordance with this invention. Alternatively, a 10 mm wide annulus of the gels of the present invention is bo applied about 8 mm from a distal or lighting end of such ; novel smoking articles. After the gel is dried, the 10 f———— : BAD ORIGINAL 9

: resulting film protects the wrappers of these smoking : articles from thermal damage including charring and flaming combustion.

As shown in FIG. 1, novel smoking articles consist of a mouth end 13, a spacer element 12, So and an active element 11 at a distal end remote from the mouth end, The active element 11 is in fluid communication with the mouth end 13, The active element 11 includes a heat reflective substantially hollow sleeve 22 having an internal wall 23 and an external wall 24 and having a } first end at the distal end and a second end } closer to the mouth end, A reflective end cap 16 may he clipped over the external wall 24 of sleeve 22 at the first end of the sleeve, Cap 15 has one or more orifices or perforations 16 . which allow air into active element 11. Disk 27 may he provided nf the second end of sleeve 22 ] to close off active element 11 from spacer element

R 20 12 while still allowing fluid communication }

TL through orifice 28. : A substantially cylindrical carbon-containing heat source 20 is inserted in sleeve 22 adjacent the first end of the sleeve, Preferably, sleeve 22 jis fitted with one or more metallic «clips 17 which hold heat source 20 suspended away from internal wall 23 of sleeve 22, defining an nN , annular space 25 around the heat source, The on - | heat source 20 has a fluid passade 2068

CA a0 suhstantially through the center thereof, § : 11 Fe }

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_ A flavor hed 21 is held within sleeve 22 hetween clip 17 and heat source 20 oh one end and a screen-like clip 26, which holds ‘pellets of flavor bed 21 while allowing air passage, on the other end. Flavor hed 21 is in radiative and convective heat transfer relationship with heat source 20, Active element 11 and spacer element 12 are jointly wrapped in an abutting relationship by wrapper 14.

Mouth end 13 may include a filter segment 29 and a tobacco rod segment 230, Filter segment 29 may be a cellulose acetate filter plug 201

Co wrapped in plug. wrap 202. Tobacco rod segment 30 may he tohacco filler 2023 ‘wrapped in plug wrap 208, Filter segment 29 and tobacco rod segment 30 are jointly overwrapped in an ahutting relationship hy plug wrap 204. Mouth end 13 is jointly overwrapped with spacer element 12, which is jointly overwrapped with active element 11, in an abutting relationship by tipping paper 205,

When the heat source is ignited and air is drawn through the smoking article, air is heated as it passes through the Fluid passage. The heated air flows through the flavor hed causing the release of a flavored aerosol which the heated air then carries to the mouth end.

The following examples rresent specific

Le methods of preparation and uses of the gels of the present invention. These examples and the , | neil 12 | BAD ORIGINAL GJ : ss. ’ + - -

‘ particular methods of use described should he read as being illustrations of, rather than limitations on, the present invention.

EXAMPLE I

_ Preparation Of Aluminum Oxide Gels With

Acetic Acid

Approximately 240 eg (1 mole) of aluminum sec-butoxide was mixed with 3 L of distilled water containing 50 ml of IN acetic acid (0.05 moles). The mixture was divided into two equal portions, and each portion WAS brought to a hoil., Constant stirring using a magnetic stirring hot. plate, at a rate sufficient to produce a

BE . vortex at the surface of the mixture, was

Cl 15 - maintained throughout the process and for an oo : additional 1.5 hours. A 10 ml volume af a

Co solution containing 0.486 g of potassium acetate oo dissolved in 20 ml of distilled water was added oo to | one portion of the mixture. The potassium acetate solution was added dropwise over a period of 1 hour, After an additional 0.5 hours, hoiling of hoth mixtures was stopped. The two mixtures were then comhined and this combined mixture was hrought to a temperature of 80°C,

EXAMPLE II

Coating Papers With Gels Prepared By The Sol-Gel

Process

Commercial grade calcium carbonate filled cigarette papers (TOD 04242 ohtainet from Ecusta, a a0 division of P.H. Glatfelter Co,, P.O. Box 200, 13 . oT i -

Pisgah Farest, NC 28768) were coated with the ~ gel of Example I. The gels were maintained at a Co i temperature of 80°C. threughout the coating operation. Hand sheets of cigarette paper were dipped into the gel and the excegs gel was allowed to drip from the paper. The papers were dried in a microwave aven (Sharp Carousel, 650 :

Watts total power at medium low setting) to form a film. The papers were then handpressed with an | iron to remove wrinkles,

EXAMPLE III

CL Coating Papers With Gels Prepared By The Sol-Gel . Process

Commercial grade © cigarette papers (TOD 04242 ohtained from Ecusta) were coated with gels ~ prepared according to Example I in a single pass through a size press applicator. The coating . produced a weight gain of 3.5 to 4.0%, The coated paper was dried in a microwave oven as in Example IT, | | :

EXAMPLE IV

Testing Of Smoking Articles Made With Aluminum }

Oxide Gel Treated Wrappers :

Novel smoking articles were made with wrappers of paper coated as described in Examples

II and III. The novel smoking articles were then tested on a single port smoking maching using a ~ 70 ce puff every 15 seconds. Each article was: lit and 4 puffs were taken hy the smoking 14 BAD ORIGINAL 9 machine to achieve a normal smoking temperature : within the article hefore actual testing commenced,

Three tests were then conducted to determine the: combustion of the outer paper wrapper. First, a lighter flame was brought to within about 1 mm of the distal of the novel smoking article during static burn. Second, a. lighter flame was held directly under the distal end of ' the novel smoking article during static burn. Third, a lighter flame was hrought under the distal end of the novel smoking article during a puff to stimulate . lighting of an already lit article.

When novel smoking articles made with wrappers treated with the. gels of Example I were tested as . deccribed here, it was observed that «hether the gels - were applied hy dipping (Example II) or with a size oo press (Example IIT) the wrappers substantially resisted combustion. | ~

EXAMPLE V

Preparation Of Aluminum Oxide Gels

With Hydrochloric Acid

This preparation was similar te that of Example I . except that hydrochloric acid wag used, Approximately 240 g (1 mole) of aluminum sec-butoxide was mixed with 3

L of distilled water containing 30 ml (0.03 moles) of 1IN : hydrochloric acid, The mixture was then heated with - constant stirring as in Example I until complete

Co Bb solution was obtained. The mixture was then divided inte two equal portions. Each portion was placed on Aa magnetic stirring hot plate and brought rapidly te a - - | ap ORIGINAL 9

- . temperature of 95°C, Congtant stirring and temperature were maintained for an additional 1.5 hours. After this } time, 60 ml (0,06 moles) of 1N hydrochloric acid was added to each portion. The temperature of the solution

Co 5 was maintained at 95°C. and stirring continued for an additional 1.8 hours. The two mixtures were then combined and this mixture was hrought tao a temperature : of 80° C. : -

EXAMPLE v1 | :

Evaluation Of Wrappers Treated i co } . With Aluminum Oxide Gels.

A film of the gel of Example V was deposited on - : the fihers of commercial grade calcium carhonate filled - cigarette papers as described in Examples II and III and novel smoking articles were prepared from then. The teste described in Example IV were performed on the novel smoking articles. In all three test situations, whether gels were applied by dipping (as in Example 11) or with a size press (as in Example IIT) paper wrappers on 20 treated with the gel prepared by Example V resisted . : flaming combustion, ‘

EXAMPLE VII

Preparation Of Dilute Aluminum Oxide Gels

And Application To Cigarette Paper

In a nitrogen atmosphere, approximately 52 g (0.2 : : moles) of aluminum tri-sec-hutoxide was mixed with 600 ml of distilled water containing 6 ml (0.006 moles) of

IN hydrochloric acid, The solution was placed on Aa magnetic stirring hot plate, and the solution was 16 or oN

BAD CRIGINAL

= LL es ~ : oo aE .

rapidly hrought to a hoil with constant stirring as in

Example I. Boiling and stirring continued for approximately 1 hour. Then 32 ml of 1IN hydrochloric acid (0.032 moles) was added to the solution. Boiling 3 and stirring continued for an additional 5 minutes, At this time, the gel was divided into two equal portions. ]

EE One portion of the gel was retained as a source } for concentrated gel, The other portion of the gel : : prepared from this procedure was diluted in a 50:50 ratio with distilled water. The gel of this Example WAS applied to cigarette paper as described in Example II. i

A second dilution of the gel was prepared hy i adding 50 ml of concentrated gel to 15 ml of distilled water. The same paper sample was dipped into this diluted gel and dried as in Example TI. Finally, the o same paper sample was dipped in the concentrated gel } zaolution and dried as before. The paper was then hand- pressed with an iron to remove wrinkles, )

EXAMPLE VIII Co

Preparation Of Magnesium Aluminate Gels

And Treatment Of Cellulose Fibers

Approximately 120 ¢ (0.5 moles) of aluminum : . sec-hutoxide was mixed with 1.5 L of distilled water ; containing 15 ml (0.015 moles) of IN hydrochloric acid. 2h The mixture was brought to a bhoil and continuously : stirred as in Example I. Boiling and stirring continued : until the mixture was reduced to a volume of . approximately 870 ml. The mixture was then divided into one aliquot of 150 ml and six aliquots of 120 ml Sach.

One of the 120 ml aliquots was heated .to a hoil

Co 17

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and then 3.8 g (0.033 moles) of magnesium ethoxide was added with stirring. After complete dissolution of the magnesium ethoxide, sufficient distilled water was added : to bring the volume of the solution to 250 ml and then "12 ml (0.012 moles) of IN hydrochloric acid was added. .

The pH of this solution was ahout 12 and considerable ° foaming was present, Concentrated hydrochloric acid (approximately 12N) was added dropwise until the pH. . reached about 4. The volume of concentrated hydrochloric acid added was approximately 8 ml.

Co Co The gel of this Example was applied to commercial cigarette paper according to Example II and formed into a a hollow tube for testing of its burn characteristics.

Ce The cigarette paper coated with the gel prepared as : 15 described in this Example resisted combustion when ignition with an open flame was attempted. - : EXAMPLE IX

Preparation Of Calcium Aluminate Gel

A solution of calcium ethoxide was prepared by reacting metallic calcium with absolute ethanol while heating the solution in a nitrogen atmosphere, A sample of 24.6 g of aluminum-sec-butoxide (0.1 moles) was mixed with 50 ml (0.05 moles) of a 1M solution of caleium ethoxide in ahsolute ethanol.

After comhining the calcium ethoxide and aluminum : sec-bntoxide, the mixture was stirred and allowed to stand for 48 hours. Needle shaped crystals were observed on the hottom of the reaction vessel. The supernatant was decanted and the crystals wete washed - : “ 18 rr

CURE CTA 80 oranaL gf) Co .. . cL Co “A So with absolute ethanol. Upon standing, the crystals were : nhserved to disappear and the solution took on the : consistency of a gel. Sufficient hydrochloric acid (1N) was added to the gel to reduce the pH from 12 to 8.

Upon standing, the supernatant separated into a huff colored alcoholic layer and a cloudy calloidal ’ layer. One ml of the alcoholic layer was added to 0.1 : ml of 0.09 N hydrochloric acid to form a transparent gel. This gel was rinsed quickly with 2 ml of distilled water and dried in an oven at ahout 150° C, The resulting white powder was applied to carbon support grids for elemental analysis using a scanning and } transmission electron microscope, Strong calcium and . aluminum signals were present. It is believed that the : 15 gel prepared in this Example consists of an amorphous Co network of calcium aluminate (CaAlqgOy). Preliminary experiments indicate that flax paper dipped into the - gels of this Example resist combustion, .

Co EXAMPLE X oo

RE 20 Preparation of Titania Gel ! 17.52 ml (0.3 moles) of absolute ethanol was added te a 50 ml beaker. The heaker was placed in an ice - ‘bath. A stream of nitrogen gas was directed into the oo | | heaker. While stirring vigorously with a magnetic | stirrer, 11.16 ml (0.1 moles) of titanyl tetrachloride . was added dropwise to the beaker. After the addition : nL was complete, the heaker was removed from the ice bath.

The mixture was stirred for an additional 2 hours. At this time, the mixture was stored for later use. 10 f

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Ce Co CL. . i ' Co Co

EXAMPLE XI

Coating And Evaluation Of Papers With Gels :

Prepared By The Sol-Gel Process

Approximately 0.6 g of the gel of Example XI, | which had solidified, was dissolved in 25 ml of 70% ethanol. Samples of commercial grade flax cigarette paper were coated by dipping as described in Example II.

One sample was dipped once and allowed to dry. Another sample was dipped once, allowed to dry, dipped again, : and allowed to dry. A third sample was dipped twice and then dried in a microwave oven as described in Example ‘

II. Scanning electron micrographs revealed that the gel . of Example XI produced a uniform coating over the | ’ ) surface of the dipped papers. :

EXAMPLE XTI

Preparation of Zirconia Gels 32.72 g (0.1 moles) of zirconium isopropoxide was ' dissolved in 200 ml of isopropanol, While stirring with a magnetic stirring hot plate, approximately 108,56 ml of isopropanol containing 8 ml of glacial acetic acid and 3.6 ml of distilled water was added, The mixture was | | : then heated with constant stirring as in Example I. A ol gel formed within 5 minutes,

EXAMPLE XITI

Preparation Of Aluminum Oxide Gel With © Hydrochloric Acid 15 ml of IN hydrochloric acid was added to 1500 ml of distilled water, The acid and patel Mixture was ’ heated to 70° C. Approximately 120 g (0.5 'nbles) of ‘

So ies 20 BAD ORIGiiv~. ! RB aluminum sec-hutoxide was then added. This mixture was . heated to 95° C, with stirring. The temperature of the solution was maintained at 95° €., and stirring continued until all of the sec-butannl evaporated, This took approximately 2 hours. At this time, 30 ml (0.03 moles) of IN hydrochloric acid was added. The temperature was maintained and stirring continued until a final volume of 400 ml was obtained.

EXAMPLE XIV

Preparation Of Aluminum Oxide Gel With

Hydrochloric Acid : : Approximately 240 g (1 mole) of aluminum-sec- } hutoxide was mixed with 1600 ml of water containing 30 ml (0.03 moles) of IN hydrochloric acid, which had been heated to 70° ¢. prior to mixing. The mixture was hrought rapidly to 95° ©. with continuous stirring and = kept at that temperature for approximately 2.5 hours.

At the end of that period of time, 60 ml of 1N . hydrochloric acid was added to the mixture, The temperature of the solution was maintained and stirring continued until a final velume of 500 ml was obtained.

EXAMPLE XV

Reduction Of Mass Burn Rate:

Conventional cigarettes were treated with gel prepared according to Example XIV, As shown in FIGS. 2 and 2, cigarette 100 was coated with an annulus of gel 101, The annulus of gel 101 was applied tao the wrapper 102 of cigarette 100 by hand with a brush. The center of the annulus was placed 32.5 mm from the 21 [ : : BAD ORIGINAL dP i et CL . : wd Te es . , . . . Loar EE Co lighting end 103 of cigarette 100. One set of cigarettes was coated with an annulus 4 mm wide; another set of cigarettes was coated with an annulus 5 mm wide.

The width of each annulus was measured parallel to the & longitudinal axis of the cigarette. The coated cigarettes were dried in air until the gels formed films on the cigarettes,

Cigarettes from each set were then individually tested hy lighting a cigarette and placing it on a pan halance, The change in the weight of the burning cigarette was measured over time. FIGS. 4 and §& illustrate the change in the weight of one cigarette - from each set against time. FIG, 4 shows the result - when a 4 mm hand of gel was applied; FIG. 5 shows the result when a 5 mm band of gel was applied.

The slope of the lines in FIGS, 4 and 5 represent ’ the mass burn rate of the cigarette, that is, how much weight is lost during a given burn time. The negatively sloping mass burn rate beginning at time equal to 0 seconds, shown in FIGS, 4 and §, illustrate that hath cigarettes experience constant weight loss after lighting. However, the mass hurn rate decreases. when the hurning coal reaches the film annulus on the cigarette wrapper. This point is marked as "A" in hoth figures. In FIG. 4, this change occurred after approximately 197 seconds. In FIG. 5, this change , . : accord after approximately 263 seconds, This change in

Ct - slope illustrates that the annulus nf film inhibits the comhistion of the cigarette, h

BAD ORIGINAL Pp , :

As shown in FIG. 4 at point YR" (at approximately : 455 seconds), after the cigarette has burned through the annulus of film, the mass burn rate again increases,

However, as shown in FIG. § at point "C" (at approximately 417 seconds), the mass burn rate declines _ to zero indicating that the cigarette has extinguished.

The affect of different widths of films is thus evident from a comparison of the mass burn rate lines. With a 4 ' mm wide film annulus, the cigarette remains lit after. } the hurning coal has burned through the full width of the film annulus. However, with a 5 mm wide film annulus, the cigarette ceases burning after the burning l coal reaches the film annulus but hefore burning through ‘ the annulus. . , » che ee eer ee eee re ee pete a Eg Ce a ge gaia dhe r | 2

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Claims (24)

4 Ce . } } ' , - 26618 ) CLAIMS

1. A wrapper for smoking articles comprising oo raper fibers and an amorphous inorganic network produced - by a sol-gel process applied thereto,

2. The wrapper for smoking articles of claim 1, - wherein the amorphous inorganic network produced by a sol-gel process is formed from at least one metal oxide . ~ precursor. ’

i

3. The wrapper for smoking articles of claim 2, wherein the metal of the metal oxide precursor is selected from the group of metals consisting of: aluminum, titanium, zirconium, sodium, potassium, and oo calcium.

4, The wrapper for smoking articles of claim 2, wherein the metal oxide precursor is a magnesium compound.

5. The wrapper for smoking articles of claim 1, - . wherein the amorphous inorganic network produced by a a sol-gel process is applied as a film,

6. The wrapper for smoking articles of claim 1, wherein the sol-gel process that produces an amorphous inorganic network produced by a sol-gel process comprises the steps of: (a) forming a solution of at least one metal ‘ axide precursor; ’ (hb) hydrolyzing the metal oxide precursor in order to form a sol; . : (c) condensing the =a0l to form a gel: and - (d) drying the gel.

. ,

! . ' . . 7. The wrapper for smoking articles of claim 6, : } ~ vherein the step of condensing further comprises the step of decreasing the pH of the sol by the addition of So acid. Ce

3 8. The wrapper for smoking articles of claim 6, wherein the step of condensing further comprises the addition of a neutral salt. . 9. A wrapper for controlling the mass burn rate of a cigarette comprising a paper wrapper and at least one annular band of an amorphous inorganic network.

10. A wrapper for controlling the mass burn rate of a cigarette comprising a paper wrapper and at least one annular band of a film produced according to any of oo claims ‘1 through 8. 16

11. A wrapper for a novel smoking article that . resists combustion comprising a paper wrapper and an ‘ amorphous inorganic network. <n i RE

12. A wrapper for a novel smoking article that i resists combustion comprising the wrapper for smoking articles according to any of claims 1 through 6. . | oo | )

13. A method of altering the burn characteristics Co So of a paper wrapper for smoking articles comprising: Co | | : (a) creating a gel of at least one metal by a sol-gel process;

25. . (bh) applying the gel to paper fibers; and {c) drying the gel upon the paper fibers,

14. . The method of altering the burn oo } characteristics of a paper wrapper for smoking articles of claim 13, wherein the step of creating further } comprises: ) ’

{a) forming a solution comprising at least one metal oxide precursor; . (bh) converting the solution into a sol by hydrolysis; and ~ le) condensing the sol to form a gel. : 156. The method of altering the burn characteristics of a paper wrapper for smoking articles of claim 14 wherein the metal oxide precursor comprises : a metal, alkoxide. , . 10

16, The method of altering the burn . characteristics of a paper wrapper for smoking articles of claim 14, wherein hydrolysis is effected by the : addition of acid to the solution. ‘

17. The method of altering the burn | characteristics of a paper wrapper for smoking articles . of claim 16, wherein the acid is selected from the group consisting of hydrochloric acid, acetic acid, citric acid, succinic acid, phosphoric acid, and nitric acid.

18. The method of altering the burn characteristics of a paper wrapper for smoking articles of claim 14, wherein the step of condensing also includes the addition of a neutral salt to the solution. . .

19, The method of altering the burn characteristics of a paper wrapper for smoking articles of claim 18, wherein the neutral salt is selected from * the group consisting of potassium acetate, potassium chloride, sodium chloride, and sodium phosphate. <a . :

20. The method for altering the burn : characteristics of a paper wrapper for smoking articles

. Cs CLs . ) © 26618 of claim 14, wherein the gel comprises aluminum oxide.

21. The method for altering the burn characteristics nf a paper wrapper for smoking articles of claim 14, wherein the gel comprises magnesium . aluminate. :

22. The method for altering the combustion ‘characteristics of a paper wrapper for smoking articles of claim 14 wherein the gel comprises calcium aluminate. ’

23. A wrapper for smoking articles comprising

10 . paper fibers and an amorphous inorganic network containing a metal oxide selected from the group . consisting of: aluminum oxide, zironium oxide, titanium Ce oxide, calcium oxide, magnesium aluminate, and. calcium aluminate, : : ‘ 15 +

24. A. wrapper for a .smeking article comprising a -.... = . wrapper and an amorphous inorganic network. nL Inventors: ANDREW G. KALLIANOS

A. CLIFTON LILLY, JR. JERRY F. WHIDBY : - 20 ROWLAND W. DWYER, JR. - ROWLAND W, DWYER, JR.