ORAL POUCH COMPRISING A POUCH ENVELOPE MADE OF A CHEMICALLY BONDED NONWOVEN FABRIC AND A FILLING MATERIAL ARRANGED THEREIN

Description

TECHNICAL FIELD

The invention relates to an oral pouch comprising a pouch envelope made of a crosslinked nonwoven fabric (nonwoven) and a filling material arranged therein.

CURRENT PRIOR ART

Oral pouches which contain a generally moist tobacco composition or a nicotine-containing substrate in a small pouch made of nonwoven fabric are known (oral tobacco packs). Snus is a form of oral tobacco that is particularly widespread in Scandinavia and is produced from dried, ground tobacco mixed with water, salt, and flavorings. Sometimes, a nicotine-containing substitute to which flavoring agents are added, if applicable, is used instead of tobacco. In addition, oral pouches containing a dry, often not brownish but rather white nicotine-containing substitute instead of moist tobacco are also known. The Snus pouch is placed behind the upper lip or lower lip. Within 15 to 60 minutes, it releases the tobacco flavor or else the added flavoring agents and the nicotine. The released substances are absorbed by the body via the oral mucosa. Afterwards, the pouch is removed from the mouth.

Furthermore, oral pouches for absorbing medications or stimulants or other active substances, for example caffeine or taurine, via the oral mucosa are known.

In the case of oral pouches which are used, for example, for nicotine pouches, an interaction can occur between the active substances (e.g. powders, granules, etc.) contained in the pouches and the nonwoven fabric, which is disadvantageous for the functionality of the oral pouch. Thus, a sometimes significant decrease in the strength of the nonwoven fabric and of the sealing seam is observed in oral nicotine pouches depending on the composition of the substances contained. This effect is observed, in particular, with increasing moisture content of the powders and the use of “strong flavors” (e.g. wintergreen) and occurs, in particular, in nonwovens that are crosslinked by means of binding agents (e.g. wet-laid or binder-bonded carded nonwovens). In addition to the loss of strength of the nonwoven and sealing seam, the nonwoven fabrics are sometimes observed to be sticky in the case of strong flavor powders with a high moisture content (moist powder).

EP 4 070 671 A1 describes an oral pouch which comprises a pouch envelope made of a chemically bonded nonwoven fabric and a filling material filled therein that contains nicotine and citric acid as the flavoring agent. During oral use, the flavoring agent is released in order to produce a sour taste.

Technical Problem

The object of the invention is to provide a thermally sealable nonwoven fabric for an oral pouch and an oral pouch having a pouch envelope made of a crosslinked nonwoven fabric and a filling material contained therein, the use properties of which are impaired less by the filling material of the pouch when used as an envelope of an oral pouch.

Solution to the Problem

The object is achieved according to the invention by a crosslinked nonwoven fabric according to claim 1 and by an oral pouch according to claim 11. Advantageous embodiments of the crosslinked nonwoven fabric and of the oral pouch are specified in the dependent claims and in the following description.

Advantageous Effects of the Invention

Investigations by the applicant have shown that the effect of the loss of strength of the nonwoven and sealing seam and of the occurrence of stickiness is also observed in nonwoven fabrics which, aside from the binder, only use fibers (e.g. cellulose, polypropylene) that are inert with respect to the ingredients of “strong flavor” powders. Therefore, an interaction between the binder and active substances contained in the strong flavor powders can be assumed. The described effect is largely reversible, and therefore the nonwoven fabrics recover the majority of their strength if the nonwoven is left in the air and if the active substances contained in the strong flavor, including water, are allowed to escape. Rinsing and drying of the nonwoven leads to a substantial recovery of the strength of the nonwoven. It can therefore be assumed that the observed effect is not based on a chemical reaction, but rather on a physical effect, in which active substances from the substances enclosed in the oral pouch penetrate the structure of the binder and cause swelling or act as a plasticizer. Since the effect increases with increasing moisture content of the powder, it is conceivable that water molecules are involved in the mechanism of action.

According to the invention, during the production of the nonwoven fabric containing cellulose fibers, citric acid, for example, as an additional crosslinking agent is added together with a (dispersion) binder to the fibers of a layer of fibers. If the layer of fibers is then transferred to a dryer, the citric acid can react with the cellulose molecules at the temperatures prevailing in the dryer so as to form ester bonds and release water. By removing the water in the dryer, the reaction equilibrium is shifted almost entirely to the ester compound.

In addition to the formation of ester bonds with the cellulose molecules, other crosslinking agents that can form a covalent bond with the cellulose molecule are also conceivable. Derivatives of epichlorohydrin (e.g. polyamidoamine epichlorohydrin (PAAE)), which can form an ether bond with the cellulose molecule, can be mentioned here by way of example.

Citric acid is used in the paper industry as a crosslinking agent in order to increase the strength of papers. When the wet strength of paper is increased by means of crosslinking using citric acid, the effect is permanent (does not disappear when the water evaporates . . . ) and is based on crosslinking of the glycosidically linked glucose units of the cellulose and/or citric acid via the formation of ester groups.

If citric acid is added to the (dispersion) binder during the production of a nonwoven chemically bonded by means of binder and containing a high proportion of cellulose fibers, the stickiness is, surprisingly, eliminated or at least significantly reduced regardless of the binder used and very different results arise with regard to the influence of the crosslinking agent on the strength or else the sealing strength of the nonwoven. This is utilized according to the invention in order to create a crosslinked nonwoven fabric for an oral pouch with at least significantly reduced stickiness and increased longitudinal strength and/or sealing strength under the influence of saliva with active substances from a filling material of an oral pouch.

The invention is explained in more detail below based on the accompanying drawings of exemplary embodiments. In the drawings:

FIG. 1 shows a Snus pouch according to the invention in a front view;

FIG. 2 shows the Snus pouch in a rear view;

FIG. 3a/b shows the longitudinal strength of the nonwoven fabric upon addition of citric acid to the Vinacryl binder;

FIG. 4 shows the sealing strength of the nonwoven fabric upon addition of citric acid to the Vinacryl binder;

FIG. 5a/b shows the longitudinal strength of the nonwoven fabric upon addition of citric acid to the Plextol binder;

FIG. 6 shows the sealing strength of the nonwoven fabric upon addition of citric acid to the Plextol binder.

According to FIGS. 1 and 2, a Snus pouch 1 comprises a pouch 2 made of a nonwoven fabric 3, in which small amounts of tobacco material 4 and/or another nicotine-containing material or other active substance is arranged. The tobacco material 4 is Snus, for example. The nonwoven fabric 3 is produced from a fiber mixture with 80% viscose fibers and 20% PP fibers, which are bonded using a chemical binder.

The pouch 2 is designed as a tubular pouch. A strip of nonwoven fabric 3 is folded over on the longitudinal sides and the longitudinal edges are interconnected by means of a longitudinally oriented heat-sealed seam 5. Furthermore, the two transverse edges of the pouch 2 are interconnected by means of transversely oriented heat-sealed seams 6, 7.

During application, the Snus pouch 1 is placed behind the lower lip or upper lip. Saliva from the oral cavity enters and leaches nicotine and other flavoring agents or else active substances from the tobacco material 4 or else from the substrate contained in the pouch, which arrive via the saliva at the oral mucosa, where they are absorbed by the body.

The following test methods are used to ascertain the properties of the nonwoven fabrics according to the invention:

• • NWSP 130.1.R0 (15) (basis weight) (edana/inda)
  • The test method for nonwoven fabrics according to DIN EN 29073-3 was used to ascertain the sealing seam strength. The test device HS-2 from the manufacturer RDM Test Equipment Ltd., Unit 39, Golds Nurseries Business Park, Jenkins Drive, Elsenham, Herts., CM22 6JX, England, was used to produce the sealed samples for testing the sealing strength.
  • EDANA WSP 110.4 Longitudinal strength/transverse strength (dry and wet) in machine direction and transverse direction, respectively
  • EDANA WSP 110.4 Elongation in machine (longitudinal) and transverse direction (dry and wet)
  • To ascertain the stickiness of the different nonwoven fabrics, two layers of nonwoven fabric (15 cm×15 cm) are in each case laid one on top of the other on a smooth surface and weighed down with a rectangular weight made of steel (2 kg) with the dimensions 15 cm×15 cm for 5 minutes at 23° C. and a relative humidity of 50%. Then, the nonwoven fabrics are pulled apart by hand and comparatively assessed by the examiner and rated relative to one another in terms of stickiness. The test is carried out with at least 4 independent testers, wherein only two different nonwoven fabrics are compared against one another in each case.

EXAMPLE 1

A fiber mixture of 80% viscose fibers (0.9 dtex, 40 mm length) and 20% PP fibers (1.7 dtex, 40 mm length) and a basis weight of 17 g/m² is bonded to a nonwoven with a basis weight of 34 g/m² in a drum dryer at 160° C. by means of a dispersion binder (Vinacryl 4378 from Celanese) applied in a foam padder (solids content of the binder of the nonwoven fabric formed: 50%). The tensile strength in the machine direction and the sealing seam strength in the machine direction are measured for the formed nonwoven fabric (see the description of the test method for forming the sealing seam).

In a second experiment with the same fiber composition and binder content, 1 wt. % or else 0.5 wt. % (based on the solids content of the binder) of citric acid is added to the binder before the binder is applied to the fibers in the foam padder and dried and cured in a drum dryer at 160° C. In this case, too, the basis weight of the nonwoven is 34 g/m².

The nonwoven strength in the machine direction and the sealing seam strength in the machine direction are measured for this nonwoven treated with citric acid.

Both nonwovens (nonwoven test specimen and nonwoven test specimen with sealing seam for determining the sealing strength) are then placed in a nicotine powder with a strong flavoring agent at 23° C. ((data in weight percent): 5% xylitol, 63.6% MCC 200 (microcrystalline cellulose), 0.4% sucralose, 1% NaCl, 1.5% nicotine, 7.5% water, 13.5% glycerol, 7.45% Wintergreen Flavour HR.CNT007) in a vessel that is sealed in an airtight manner (samples are referred to in the drawings below as “marinated”). After 5 days, the strength in the longitudinal direction and the sealing strength in the longitudinal direction are ascertained.

FIG. 1 shows that the addition of citric acid increases the longitudinal strength of the nonwoven bonded with Vinacryl binder, both for untreated nonwoven and for the nonwoven placed in nicotine powder with wintergreen additive. This could mean that the citric acid becomes crosslinked with the cellulose fibers (viscose) contained in the nonwoven so as to form ester bonds. This could also explain the observation that the nonwoven produced with citric acid added to the binder has a reduced stickiness after the nonwoven has been placed in the nicotine powder with wintergreen additive.

FIG. 2 shows that the sealing strength of the nonwoven bonded with Vinacryl is significantly reduced by the addition of citric acid to the binder. After the nonwoven is treated with the nicotine powder with wintergreen additive, only a very small increase in the sealing strength can be seen due to the addition of the citric acid.

It seems that the citric acid reacts with the Vinacryl binder and reduces the ability thereof to form a stable sealing seam. Since both the binder and the PP fibers contained in the nonwoven contribute to the formation of the thermal sealing seam, wherein PP is largely inert with respect to citric acid, it can be assumed that the citric acid reacts with the Vinacryl polymer and reduces the thermal sealing strength thereof. This could occur due to a crosslinking reaction, which converts the binder into a crosslinked structure which only has reduced thermoplastic properties and can thus only form a weaker thermal sealing seam.

In the case of the nonwoven bonded with Vinacryl, the stickiness of the nonwoven fabric is somewhat reduced after exposure to nicotine powder with wintergreen additive. This was ascertained in a haptic comparative test with 5 participants. The participants comparatively assessed the stickiness of nonwoven samples (nonwoven without added citric acid and nonwoven with 0.5% added citric acid) which had been placed in a nicotine powder with wintergreen additive for 5 days. As shown in Table 1, 4 of the 5 participants assessed the stickiness of the nonwoven produced with 0.5% added citric acid as being somewhat less than that of the untreated nonwoven. One participant did not notice any difference in the stickiness.

EXAMPLE 2

A fiber mixture of 80% viscose fibers (0.9 dtex, 40 mm length) and 20% PP fibers (1.7 dtex, 40 mm length) and a basis weight of 17 g/m² is bonded to a nonwoven with a basis weight of 34 g/m² in a drum dryer at 170° C. by means of a dispersion binder (Plextol B 500 from Synthomer) applied in a foam padder (solids content of the binder of the nonwoven fabric formed: 50%). The tensile strength in the machine direction and the sealing seam strength in the machine direction are measured for the formed nonwoven fabric (see the description of the test method for forming the sealing seam).

In a second experiment with the same fiber composition and binder content, 1 wt. % or else 0.5 wt. % (based on the solids content of the binder) of citric acid is added to the binder before the binder is applied to the fibers in the foam padder and is dried and cured in a drum dryer at 170° C. In this case, too, the basis weight of the nonwoven is 34 g/m².

The nonwoven strength in the machine direction and the sealing seam strength in the machine direction are measured for this nonwoven treated with citric acid.

Both nonwovens (nonwoven test specimen and nonwoven test specimen with sealing seam for determining the sealing strength) are then placed in a nicotine powder with a strong flavoring agent at 23° C. ((data in weight percent): 5% xylitol, 63.6% MCC 200 (microcrystalline cellulose), 0.4% sucralose, 1% NaCl, 1.5% nicotine, 7.5% water, 13.5% glycerol, 7.45% Wintergreen Flavor HR.CNT007) in a vessel that is sealed in an airtight manner (samples are referred to in the drawings below as “marinated”). After 5 days, the strength in the longitudinal direction and the sealing strength in the longitudinal direction are ascertained.

FIG. 3 shows that the addition of citric acid only slightly changes the longitudinal strength (dry and wet) of the nonwoven for the nonwoven not treated with nicotine powder with wintergreen additive, but significantly increases same for the nonwoven placed in the nicotine powder with wintergreen additive relative to the untreated nonwoven. The nonwoven produced with Plextol binder also exhibits the effect that the nonwoven produced with citric acid added to the binder has a significantly reduced stickiness after the nonwoven has been placed in the nicotine powder with wintergreen additive for 5 days at 23° C.

FIG. 4 shows that the sealing strength of the nonwoven is significantly increased by the addition of citric acid to the Plextol B 500 binder in contrast to the nonwoven bonded with Vinacryl binder.

After the nonwoven is treated with the nicotine powder with wintergreen additive, the drop in thermal sealing strength can be seen to be significantly reduced by the addition of citric acid to the Plextol binder, and therefore a significantly higher thermal sealing strength can be observed with an increasing proportion of citric acid added.

In contrast to the Vinacryl binder, no negative influence on the sealing ability of the binder is observed with the addition of citric acid to the Plextol B 500 binder. The two chemically similar binders (Vinacryl: partially self-crosslinking mixture of polymers based on vinyl acetate and butyl acrylate/Plextol: non-self-crosslinking thermoplastic acryl polymer) substantially differ in that the Vinacryl binder is partially self-crosslinking, whereas the Plextol binder is not self-crosslinking and consists of a dispersion of a thermoplastic acryl polymer. The surprising difference in the behavior of both binders with respect to the addition of citric acid for increasing the nonwoven strength and sealing seam strength appears to be due to the fact that the self-crosslinking groups of the Vinacryl binder react with the citric acid and thus restrict the ability thereof to form a stable thermal sealing seam, whereas the addition of citric acid to the Plextol binder results in no crosslinking of the binder, and therefore the thermal sealing ability thereof is maintained and the citric acid contributes to the consolidation of the nonwoven by reacting with the cellulose molecules.

In the case of the nonwoven bonded with Plextol, the stickiness of the nonwoven fabric is reduced slightly after exposure to nicotine powder with wintergreen additive. This was ascertained in a haptic comparative test with 5 participants. The participants comparatively assessed the stickiness of nonwoven samples (nonwoven without added citric acid and nonwoven with 0.5% added citric acid) which had been placed in a nicotine powder with wintergreen additive for 3 days. As shown in Table 2, 2 of the 5 participants assessed the stickiness of the nonwoven produced with 0.5% added citric acid as being somewhat less than that of the untreated nonwoven. Three participants did not notice any difference in the stickiness.