Abstract:
A smokeless tobacco product adapted for oral administration includes a permeable pouch adapted for administration into a user&#39;s mouth and adapted to be removed from the mouth and disposed in nature and smokeless tobacco contained in the pouch. The pouch is made from a degradable polymer whose degradation properties allow the pouch to be essentially intact until the time of disposal and allow the pouch to degrade in nature after disposal.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to smokeless tobacco products, and in particular to a degradable polymer container for smokeless tobacco. 
       BACKGROUND OF THE INVENTION 
       [0002]    Smokeless tobacco in the form of so-called snuff, i.e. tobacco adapted for oral administration, is gaining increased popularity, not least as a substitute for cigarettes, cigars and other more conventional tobacco products. Although not harmless such smokeless tobacco products pose a lesser threat to a user&#39;s health than, for example, smoking, and can therefore be regarded as an acceptable substitute for smoking. 
         [0003]    A popular way of administrating snuff is to contain the snuff in a permeable pouch. Such a pouch holds the tobacco in place, while at the same time letting the flavours and substances of the tobacco pass through the walls of the pouch and into the user&#39;s mouth, to thereby be absorbed by the mucous membranes. When the flavours and active substances are consumed, the user removes the tobacco pouch from his or her mouth and disposes the now moisture-logged pouch. 
         [0004]    Due to lack of suitable public bins, or due to the users&#39; indifference and indolence, the used tobacco pouches frequently end up in public places, such as streets, at golf courses and other sports grounds, at entrances to public buildings and shops, and so forth. Being small and relatively flat objects, the tobacco pouches can not easily be picked up and disposed. 
         [0005]    Conversely, for a person having a high sense of environmental responsibility, the lack of suitable facilities for disposing a used tobacco pouch may lead to the user keeping the tobacco pouch in his/her mouth longer than he/she actually would like to, thereby exposing himself/herself to an unnecessary large dose of potentially harmful agents. 
       SUMMARY OF THE INVENTION 
       [0006]    In the international patent application WO 97/13419 it is mentioned that a degradable sheath could be used to contain smokeless tobacco, but the material of the degradable sheath is only briefly discussed. Furthermore, WO 97/13419 is silent about the tactile feeling that different material compositions evoke in a user&#39;s mouth. An appealing tactile sensation is a prerequisite for gaining the consumers&#39; acceptance of smokeless tobacco products. 
         [0007]    Consequently, there is still a need for an improved degradable smokeless tobacco container which obviates, or at least reduces, the aforementioned environmental and also medical problems that non-degradable tobacco containers present. 
         [0008]    Embodiments of the invention are directed to a pouch containing smokeless tobacco and being adapted for oral administration. After removal from the user&#39;s mouth, the pouch will degrade when exposed to the physical, chemical and biological conditions that prevail in different environments around human beings. 
         [0009]    One embodiment of the present invention includes a pouch that is made from a material which degrades when exposed to humidity over an extended period of time. In a second embodiment the degradation of a pouch is mainly caused by micro-organisms, whereas a pouch according to a third embodiment is made from a material that degrades when exposed to sunlight. A still further embodiment degrades due to the influence of oxygen, i.e. the pouch material degrades via oxidation. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0010]    Generally, the invention is directed to a pouch or container adapted to contain tobacco or a tobacco substitute. The pouch is intended for oral administration and is designed to degrade in a natural environment after removal from the mouth of a user and subsequent disposal. In one embodiment, the pouch completely surrounds (or encloses) the tobacco with a material which is not dissolvable in a user&#39;s mouth. During storage, the pouch and tobacco therein can be stored in an airtight container (eg, a bag or plastic container) to prevent the pouch from being exposed to the oxygen and humidity of ambient air. 
         [0011]    In one embodiment of the present invention, the pouch is made from a degradable material, the degradation of which is mainly induced by water, e.g. in the form of humidity and/or rainwater. Here it should, however, be appreciated that such pouch material will start to degrade as soon as it comes into contact with the tobacco contained in the pouch as tobacco contains a certain amount of moisture. The degradation process will then proceed during the entire time of storage before the corresponding smokeless tobacco product is used by a consumer. A degradable pouch for a smokeless tobacco product must be made from a material that withstands the degradation induced by the moisture of the tobacco product itself during the whole storage period, at least to such an extent that any change in the mechanical properties of the pouch material does not compromise the quality of the tobacco product. It is well-known that the moisture content varies with different tobacco types and products, and also the intended shelf life may vary. A pouch for a smokeless tobacco product must therefore be tailored for the specific tobacco product, including the intended shelf life, of which the pouch is a part. This is in particular true when the pouch is made from one or several degradable polymers, because any change in mechanical properties of the pouch, such as strength or stiffness, is not to be regarded as a general feature among the polymers, and will be different from material to material even if their relative degradation is the same. Consequently, specific knowledge of the general degradation characteristics of the polymer(s) is required to design a pouch material that will withstand the maximal allowed storage time for any specific smokeless tobacco product. 
         [0012]    In passing it may be mentioned that the time period during which a consumer actually enjoys the smokeless tobacco product is relatively short, approximately 10 to 30 minutes, in particular in comparison with the intended shelf life, which can range from 3 to 12 months; and normally this relatively short time period during which the tobacco product is in the user&#39;s mouth does not come into consideration when selecting a suitable pouch material. 
         [0013]    Degradable pouch materials whose degradation predominantly is induced by humidity—or more precisely by the water that is abundant in humid air—are typically polymers characterized by having hydrolysable bonds in the backbone of the polymer chain. Examples of hydrolysable bonds are those found in the polymer groups comprising polyanhydrides, polyesters, polycarbonates, polyorthoesters, polyphosphazenes, polyesterurethane, polycarbonateurethane, and polyaminoacids. More specifically, polyesters or polycarbonates made through ring-opening polymerization of the monomers generally known as lactones is of particular applicability. The lactones may be un-substituted or substituted, and some non-limiting examples of lactones that can be used are propiolactone, pivalolactone, β-butyrolactone, 6-valerolactone, glycolide, L-lactide, D-lactide, mesolactide, paradioxanone, trimethylene carbonate, ε-caprolactone, and 1,5-dioxepan-2-one. Also the dimeric lactones from ε-caprolactone and 1,5-dioxepan-2-one are readily polymerized into polymers with high molecular weight. 
         [0014]    The aforementioned examples of lactone monomers can furthermore be mixed with each other during the polymerization step to create block or random copolymers with a wide spectrum of properties. The various homopolymers and copolymers from the aforementioned monomers can furthermore be blended with each other or with any polymer of the aforementioned polymer groups in a variety of different proportions to further fine-tune some of the desirable properties. One such property of particular importance is the degradation time, but also other properties, like strength and softness, should be considered. 
         [0015]    Other synthetic polyesters as degradable materials for a pouch according to the present invention are those generally known as condensation polymers. This group contains polyesters made from diacids and diols, and several of these polyesters are able to form fibres which will degrade in nature. Examples of various diacids are, but not limited to, succinic, glutaric, adipic, pimelic, suberic, azelaic and sebacic acid. These acids can be polymerized in the presence of a variety of diols, such as ethyleneglycol, 1,2-propyleneglycol, 1,3-proanediol, 1,4-butandiol, pentamethylenglycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, or 1,4-cyclohexandiol, to form suitable material for a pouch according to the present invention. 
         [0016]    In another embodiment of the present invention, the pouch is made from a degradable material having slow or very slow degradation kinetics when exposed to humidity only, but with accelerated degradation kinetics when also exposed to microorganisms which are abundant in nature. In comparison with materials that mainly degrade due to humidity, such materials have an enhanced ability to preserve the mechanical integrity of a corresponding pouch over an extended time of storage. Several microorganisms and especially several families of bacteria residing in soil will readily degrade synthetic polymer, and particularly polyesters. When active microorganisms are taking part in the degradation process, the degradation will proceed by oxidation and also enzymatic cleavage and not only by pure hydrolysis. This will further enhance the ongoing degradation process. The degradation processes of natural polymers like polysaccharides, proteins, and polyhydroxybutyrate including its various copolymers, mostly involve microorganisms, and consequently a pouch made from such natural polymers would exhibit advantageous properties. 
         [0017]    For example, polyhydroxybutyrate and its various copolymers are, for example, utilized by certain bacteria abundant in soil to store energy, and it can therefore be expected that a pouch comprising polyhydroxybutyrate will be quickly consumed by such bacteria. Some polysaccarides are available in nature and can in many cases easily be formed into fibres. Examples of such natural polysaccarides are starch and chitosan. Starch is found in a variety of different crops and among the larger sources are corn and potatoes. Chitosan is the second most abundant biopolymer on earth and is most readily available from shrimp and crab shell. Both starch and chitosan are easily degraded in nature by various microorganisms. Oxidative degradation by chitosan is very fast and especially so in the presence of metal ions like iron, which is naturally present in the environment. Non-limiting examples of proteins which can be used to make the pouch according to the invention and which degrade due to influence of microorganisms are fibrin, collagen and zein. Natural materials may further be stabilized by crosslinking with diepoxides, dialdehydes or polycarbocylic acids to manipulate degradation and mechanical properties of the end product. Degradation of polymers by sunlight and especially the ultraviolet part is also well known and most synthetic polymers today contain some kind of additive to avoid this type of degradation. Sunlight in combination with oxygen in air will cause oxidation of the polymer leading to chain scission and thus degradation. There is often a complex chain of chemical reactions leading to the observed polymer chain cleavage that involves radicals and the oxygen found in the surrounding air. When the polymer has been degraded into smaller fragments these will be more readily available for microorganisms, which will further degrade the material into carbon dioxide and water. The process of breakdown by sunlight and oxidation alone is typically known as a rather slow process but today several industries have additives that will speed up the degradation in the environment. Various additives incorporate pre-oxidized polymers, trace metals or metal chelates that will speed up the oxidation reactions when the material is exposed to sunlight. A number of additives exist on the market, which will speed up degradation of common plastic material, such as TDPA™ from EPI Environmental Products Inc. and Envirocare™ from CIBA. Copolymerization of ordinary vinyl monomers, ethylene and polypropylene together with carbon monoxide and thus introducing a keto group in the main polymer chain which is readily further oxidized has also been used to speed up degradation of polymers in nature. The most well known photo degradable resins made from carbon monoxide is known as Ecolyte which has been used to modify other materials to be fully degradable when exposed to unshielded sunlight and humidity. 
         [0018]    Another polymer, which readily forms fibers and thin foils, is polyvinylalcohol or its various copolymers. The biodegradation of this polymer is well known and proceeds through oxidation and subsequent chain cleavage into smaller polymer chains. The oxidation process is most readily performed by sunlight and soil bacteria and results in low molecular fragments that are water soluble and thus more susceptible to oxidation and hydrolysis, which leads to full degradation of the polymer. 
         [0019]    The above materials are non-limiting examples of degradable polymers that can be used alone or in blends with each other to result in the most preferred degradation profile of the pouch. Various additives such as oxidizers, sencitizers, and plasticizers can be employed to alter the degradation characteristics of the material. Plasticizers such as but not limited to various substituted or non substituted citric acid esters, such as triethyl-citrate or acetyl triethyl-citrate, and glycerol esters, such as triacetin, can be used to modify the softness of the material to minimize the feel of the pouch once in the mouth. 
         [0020]    The examples of materials and additives that can be used for the pouch (which is characterized by an acceptable degradation of the pouch throughout storage and during use while being accelerated after disposal) are not limiting examples to achieve the most preferred degradation profile. While the storage periods may be different and also the amount of moisture present, in different tobacco blends, the storage time may affect the different materials differently and consequently the material selection for a suitable pouch material must be determined with these factors in mind, e.g. a pouch made from a relatively dry tobacco product with a short storage time can preferably be made from a material composition having a faster degradation kinetic than a pouch that will house a moist tobacco product. For those materials where the primary degradation arises from simple hydrolysis, the moisture content in the tobacco will be of primary importance for selecting the suitable material. The storage period is typically 3 to 12 months and degradation during this time period should not lead to any such change in mechanical properties such as strength or pliability that will compromise the end use of the pouch or how the customer perceives the pouch. After disposal of the pouch, the pouch should be disintegrated, e.g. fragmented into smaller pieces, or fully degraded within a time period of 3 years, but more preferably within 2 years and more preferably within a time period of 1 year or less. Polymers of particular interest are those that degrade by means of sunlight and oxidation together with those that degrade by hydrolysis and/or in combination with micro organisms. As non-limiting examples of polymers that can be used to meet the various selection criteria set forth above, the polylactide, polyhydroxybutyric acid, polycaprolactone family of polymers can be used. The above-mentioned polymers are only slowly degraded in a humid environment, a feature that can be manipulated, either accelerated or retarded, by copolymerisation or blending with synthetic or natural polymers. Poly-1-lactide has a degradation time of about 4 to 6 years as a pure homo polymer. As an example, the degradation time for pure polyglycolide is too short for the polymer to be of interest as the main component in the pouch material, but if glycolide is used as a co-monomer in the polylactide polymerisation, the glycolide will be found as short but more easily degradable sequences within the lactide-glycolide copolymer and thus lead to a faster disintegration and degradation of the pouch material. Non-limiting examples of other monomers that can be used instead of glycolide to manipulate the degradation kinetic of polylactide and polycaprolactone is paradioxanone, 1,5-dioxepan-2-one and trimethylene carbonate. Various additives like natural polymers like carbohydrates and proteins may further be used to manipulate the degradation characteristics. 
         [0021]    The pouch itself can be made from a fibre mat. Several techniques can be employed to make the fibres used for production of the pouch material such as melt spinning and dry or wet spinning. Typical fibre diameters especially useful in this application are found in the range of 0.5 to 50 microns, preferably in the range of 2 to 30 microns, and more preferably in the range of 8 to 24 microns. It must be understood that a more stiff material may require a smaller diameter than a more soft material to obtain a pouch that does not feel hard or stiff once in the mouth. The fibres can later be converted into non-woven fibre mats by well-known techniques. Other techniques that may be used for production of the inventive pouch material are fibre blowing or electro-spinning. In the two latter methods a fibre mat is produced at the same time the fibre is formed, and may for some materials be a more convenient method to produce the pouch material. The thickness of the pouch material is typically in the range of 25 to 300 microns, but more preferably in the range of 75 to 150 microns. Although fibre forming processes may be a convenient method to make the inventive pouch material, other techniques may be used. One such method is to make the pouch from a thin, perforated polymer foil. These thin foils can be made very flexible. One convenient way to perforate the thin foil is to use electrical discharge across the foil area or any type of laser equipment such as carbon dioxide or excimer lasers. Foils are most conveniently extruded, and during this process several layers can be combined to achieve the right feel of the pouch material. Additives can also be used in one or all of the layers. Such additives could be any type of pharmacological substance, nicotine, nicotine extract, any type of oral health substance such as sodium fluoride, chlorhexidin or teeth whitening substances to mention a few. The pouch material, e.g. in the form of a fibre mat or a film, can be formed into a pouch by well-known techniques such as folding and subsequent welding, sewing or gluing, etc. 
         [0022]    The pore size of the pouch needs to be adjusted to the tobacco product so that a minimum of solid particles escape the pouch but should allow for a free exchange of water soluble substances. If very small pores are used and the material in the pouch is relatively hydrophobic, free water flow may be hindered and larger pores may be needed. The same but opposite is true when a more hydrophilic material is used to manufacture the pouch. Typically the porosity or transparency, i.e. the area not occupied by any type of material is in the range of 5 to 40%, but preferably found in the range of 10 to 30%, or more preferably in the range of 15 to 25%. The shape of the pores is not important for the proper function of the inventive pouch and may take any type of shape. It is therefore difficult to specify the dimensions of the pores, however, the area of any type of pore can easily be defined and the pore size can then be specified as the diameter of a circle with equivalent area. The so defined equivalent pore diameter should be a maximum of 500 microns and preferably less than 300 microns. Preferably, at least 50% of the porosity in the pouch is made up by pores having an equivalent diameter of 100 microns or less. 
         [0023]    Although the present invention has been described with reference to specific embodiments, it will be apparent for those skilled in the art that many variations and modifications can be done within the scope of the invention as described in the specification and defined with reference to the claims below.