Packaging

Abstract

Wrapper-type packaging composed of a flexible plastics sheet material in the form of a sack or bag having a front wall and a rear wall, which are located opposite one another and are sealed by a side sealing seam to form a flexible sack-like or bag-like tube, of which the opening is covered by a closure flap which is formed by a projection of the rear wall and is folded onto the front wall at least as far as the opening and is closed by longitudinal sealing and, possibly, transverse sealing or adhesive bonding, the opening having an opening aid, wherein the flexible plastics sheet material is oriented at least uniaxially and optionally is embossed and has a tear-propagation resistance in the machine direction which differs by at least 30% from the tear propagation resistance in the direction transverse to the machine direction.

Description

[0001] This application is a Continuation of International Patent Application No. PCT/EP2015/000612, filed Mar. 19, 2015, which claims foreign priority benefit under 35 U.S.C. .sctn.119 of German Patent Applications 10 2014 004 042.9 filed Mar. 21, 2014, 10 2014 010 691.8 filed Mar. 21, 2014, and 10 2014 010 987.9 filed Jul. 29, 2014 the contents of all of which are incorporated herein by reference.

[0002] A wrapper-type packaging made of a flexible polymeric film in the form of a sack or bag and consisting of a front wall and a rear wall, which are located opposite one another and are sealed in each case by a side sealing seam to form a sack-like or bag-like tube, of which the opening is covered by a closure flap which is formed by a projection of the rear wall and is folded onto the front wall at least as far as, and preferably beyond, the opening and is closed by in each case longitudinal side sealing and, optionally, transverse sealing or adhesive bonding, and preferably having an opening aid, wherein the flexible polymeric film is oriented at least monoaxially and is optionally embossed and has a tear propagation resistance in machine direction which differs by at least 30% in relation to the tear propagation resistance in the direction transverse to the machine direction and the wrapper-type packaging is suitable in particular for optionally self-adhesive articles, preferably optionally self-adhesive hygiene articles, which are preferably provided for single use.

BACKGROUND OF THE INVENTION

[0003] It is known that wrapper-type packagings made from flexible polymeric films are suitable for packaging a very wide variety of articles, especially articles for single use. In particular in the hygiene sector an increasing tendency to package hygiene articles for single use individually, in order to achieve the maximum protection and the maximum hygiene for the sensitive use of such products. A disadvantage of the known wrapper-type packaging for folded hygiene products, such as sanitary towels or panty liners, for example, has been that sealing during production or during closing of a wrapper-type packaging made of an optionally sealable, flexible polymeric film, if possible, has been avoided. The reason for this is that such packaging even only partly closed in this way can only be opened with difficulty and the simple removal of the packaged product can risk a contamination. In order to facilitate the opening and the removal of the packaged product, particularly of an individually packaged hygiene product, in the production the front wall and the rear wall for the formation of a sack-like or bag-like tube of a wrapper-type packaging are preferably not sealed longitudinally, but instead are joined longitudinally by a particular type, namely by crimping, in each case together with the closure flap folded over the front wall, whereby said closure flap is closed transversely. Therefore, there is no need to tear any seal seam for opening, which would be more difficult for the end user and, furthermore, would cause not only a fairly unpleasant noise, but also the risk of an unintended tearing of the packaging.

[0004] Therefore, it was an object of the present invention to provide a wrapper-type packaging which ensures secure packaging by avoiding any access to the packaged product prior to the intended use, but however is easy to open.

SUMMARY OF THE INVENTION

[0005] This object is solved by the provision of a wrapper-type packaging made of a flexible polymeric film in the form of a sack or bag and consisting of a front wall and a rear wall, which are located opposite one another and are sealed in each case by a side sealing seam to form a sack-like or bag-like tube, of which the opening is covered by a closure flap which is formed by a projection of the rear wall and is folded onto the front wall and is closed by in each case longitudinal side sealing and, optionally, transverse sealing or adhesive bonding, and preferably having an opening aid, characterized in that the flexible polymeric film is oriented at least monoaxially and is optionally embossed and has a tear propagation resistance in machine direction which differs by at least 30% in relation to the tear propagation resistance in the direction transverse to the machine direction.

DETAILED DESCRIPTION

[0006] Preferably the closure flap can be closed completely by longitudinal sealings at both sides and a transverse sealing or by the transverse adhesive bonding of the closure flap, against the front wall of the packaging, since by means of an opening aid, i.e. a marking in the form, for example, of a notch, the tearing direction for the opening of the packaging can be provided without any tearing of one of the seal seams. This marked tearing direction marks the direction of relatively low tearing propagation resistance of the polymeric film used. In case the inventive packaging is closed completely by means of the sealed closure flap the end user has a guaranty for retained hygiene requirements and that no unallowed access to the packaged product took place before its end use.

[0007] The sealable, flexible polymeric film used for producing the inventive wrapper-type packaging may be a single-layer or multilayer film. Preferably it is a multilayer polymeric film, more preferably an at least 3-layer film, very preferably an at least 5-layer film.

[0008] The polymeric film used according to the invention has at least a monoaxial orientation in the machine direction. This orientation is usually achieved by a difference in speed between its extrusion speed and takeoff speed during the film production. The ratio of the speed (i.e., the draw ratio) is preferably at least 1:30, preferably at least 1:50.

[0009] Optionally the polymeric film used according to the invention can additionally also have at least a monoaxial orientation in machine direction of at least 1:2, preferably of at least 1:3, more preferably from 1:3 to 1:5. It can also be biaxially oriented, i.e., can also have orientation transverse to the machine direction of 1:2 to 1:3.5. In the case of a biaxial direction and transversely to the machine direction, the draw ratio in the two directions should be different, whereby preferably the orientation in machine direction is higher than transversely to the machine direction.

[0010] The multilayer polymeric film used according to the invention preferably comprises at least a three-layer sequence of [0011] (a) an optionally sealable layer (a) as surface layer, [0012] (b) optionally an adhesion promoter layer (b), [0013] (c) a layer (c), optionally with barrier effect, [0014] (d) optionally an adhesion promoter layer (d), and [0015] (e) an optionally sealable layer (e) as surface layer, with at least one of the surface layers preferably being sealable.

[0016] The layers of the polymeric film used according to the invention have preferably been prepared from thermoplastic polymers selected from the group comprising polyolefins, polyamides, polyesters, biodegradable polymers, copolymers of at least two monomers of the mentioned polymers and mixtures of at least two of the mentioned polymers.

[0017] The polymeric film used according to the invention preferably consists of at least 50 wt %, more preferably of at least 70 wt % of polyolefins, preferably of C.sub.2-C.sub.8 olefin polymers, more preferably of C.sub.2-C.sub.3 olefin polymers, their mixtures or copolymers, olefin copolymers or their mixtures.

[0018] The layers (a) and (e) and also, optionally, the layer (c) of the multilayer film used according the invention are based preferably in each case, identically or differently, on polyolefins and olefin copolymers of .alpha.,.beta.-unsaturated olefins having 2-8, preferably 2-3, carbon atoms, which are preferably selected from the group comprising polyethylenes (PE)--especially polyethylenes of low density between 0.86 and 0.93 g/cm.sup.3 (LDPE), linear polyethylenes of low density between 0.86 and 0.94 g/cm.sup.3 (LLDPE) containing as comonomer one or more .alpha.-olefins having more than 2 carbon atoms, polyethylenes of medium density between 0.926 and 0.94 g/cm.sup.3 (MDPE), polyethylenes of high density between 0.94 and 0.97 g/cm.sup.3 (HDPE), copolymers of ethylene with an .alpha.-olefin having 4 or more carbon atoms (mPE); polypropylenes (PP), polyisobutylenes (PI), polybutylenes (PB) and ethylene-propylene copolymers with preferably 1-10 mol % of ethylene (EPC). With particular preference a mixture of LDPE and MDPE or a mixture of LDPE, MDPE and PP can be used in which case the fraction of MDPE and optionally PP in the mixture can amount to 25 wt % to 85 wt %, based on the total weight of the respective layer.

[0019] The layers (a) and (e) can also consist of olefin/vinylcarboxylic acid copolymers or olefin/vinyl ester copolymers such as ethylene-acrylic acid copolymers (EAA), their esters such as (EMA), ethylene-methacrylic acid copolymers (EMAA), their esters such as (EMMA), ethylene-vinyl acetate copolymers with preferably 60-99 mol % of ethylene (EVA), or of mixtures of in each case at least two of the before mentioned types of polymers.

[0020] In a further embodiment, at least the layer (e) as surface layer may be based on at least one polyester or at least one copolyester which is preferably selected from the group comprising polyethylene terephthalates (PET, c-PET, a-PET) and copolymers such as coPET, PBT and CoPBT). "PET" refers to polyethylene terephthalates prepared by polycondensation of ethylene glycol and terephthalic acid. Furthermore, amorphous PET (a-PET) and crystalline PET (c-PET) can be used. "CoPET" refers to copolyesters which in addition to ethylene glycol and terephthalic acid can additionally contain further monomers, such as branched or aromatic diols, for example. "CoPBT" refers to polybutylene terephthalates. The polyester or copolyester used preferably has an intrinsic viscosity of preferably 0.1 to 2.0 dl/g, more preferably of 0.3 to 1.5 dl/g, more particularly of 0.6 to 1.0 dl/g, the methods for determining the intrinsic viscosity being known to the skilled person. A comprehensive description of suitable PET and PBT is disclosed in Kunststoffhandbuch volume 3/1--technische Thermoplaste: Polycarbonate, Polyacetale, Polyester, Cellulosester; Carl Hanser Verlag, 1992, the content of which is hereby referenced in full.

[0021] In a further embodiment, at least the layer (e) may be based on at least one biodegradable polymer. As suitable biodegradable, thermoplastic polymers it is possible to use at least one biodegradable polymer selected from the group comprising lactic acid homopolymers and copolymers, preferably polylactides, more preferably of DL-lactide, of L-lactide and of D-lactide, polyhydroxyalkanoates, cellulose, cellulose derivatives, thermoplastic starch, polyesters, preferably polycaprolactones, polyethers, at least partly hydrolyzed polyvinyl acetates, ethylene-vinyl alcohol copolymers and copolymers of at least two monomers of the mentioned polymers.

[0022] In the selection of the polymer components of the layer (a) and (e), respectively, it should preferably be ensured that the layer (a) can be bonded to the layer (e) by heat sealing, at least with respect to the two longitudinal side seal seams of the wrapper-type packaging.

[0023] According to a preferred embodiment, the multilayer polymeric film used according to the invention has at least one layer (c) having a barrier effect. The skilled person is aware of suitable polymers with which it is possible to achieve a barrier effect, more particularly against loss of gas or loss of aroma, against migration of low molecular mass components and/or against impairment of flavor and/or odor, or against moisture and/or against oils and fats.

[0024] Accordingly the layer (c) with a barrier effect against gases, preferably against O.sub.2, (H.sub.2O--) vapor and/or gaseous flavors, against migration of low molecular mass organic compounds and/or against impairment of taste and/or odor, is based on at least one thermoplastic polymer selected from the group comprising ethylene-vinyl alcohol copolymers, polyvinyl alcohols, polyvinylidene chlorides, vinylidene chloride copolymers, polyether-polyamide block copolymers and mixtures of the polymers with ethylene-vinyl acetate copolymers. Preferred vinylidene chloride copolymers have a vinylidene chloride fraction of 80% or more. Ethylene-vinyl alcohol copolymers are particularly preferred.

[0025] According to another preferred embodiment, the layer (c) has a barrier effect against moisture and/or oils and fats which is based preferably on a thermoplastic, aliphatic or (partially) aromatic polyamide or copolyamide or mixtures thereof.

[0026] As polyamides (PA) or copolyamides (coPA) it is possible, for producing at least one layer (c), to use preferably aliphatic or (partially) aromatic polyamides, preferably having a melting point in the range from 160 to 240.degree. C., more preferably from 170 to 220.degree. C. Preference is given to aliphatic polyamides, for which at least one polyamide or copolyamide is selected from the group comprising PA 6, PA 12, PA 6,6, PA 6,12, PA 6/6,6, PA 6,6/6; or partially aromatic polyamides, such as PA6T and PA6I, which may preferably also comprise isophorone diamine units. A comprehensive description of polyamides and copolyamides is found in Kunstoff-Handbuch volume VI, Polyamide, Carl Hanser Verlag Munich, 1966; and Melvin I. Kohan, Nylon Plastics Handbook, Carl Hanser Verlag Munich, 1995, the content of which is hereby included by reference in full.

[0027] As already mentioned, particularly for producing the layer (c), it is possible to use homopolyamides and/or copolyamides selected from the group comprising thermoplastic, aliphatic, partially aromatic and aromatic homopolyamides or copolyamides with isophorone diamine units. These homopolyamides or copolyamides with isophorone diamine units can be composed of further aliphatic and/or cycloaliphatic diamines having 2-10 carbon atoms such as hexamethylene diamine and/or aromatic diamines having 6-10 carbon atoms such as p-phenylene diamine, and of aliphatic or aromatic dicarboxylic acids having 6-14 carbon atoms such as adipic acid, terephthalic acid or isophthalic acid. Furthermore, copolyamides with isophorone diamine units can also comprise lactam units having 4-10 carbon atoms such as s-caprolactam, for example. To produce homopolyamides and/or copolyamides, isophorone diamine can preferably be used as at least one diamine component that the homopolyamides and/or copolyamides which are preferably suitable for producing the layer (c) having units consisting of isophthalic acid or terephthalic acid and isophorone diamine. Homopolyamides and/or copolyamides which are particularly preferably used according to the invention comprise units consisting of s-caprolactam, isophorone diamine and of an aromatic dicarboxylic acid, preferably isophthalic acid.

[0028] In one preferred embodiment the fraction of the units of isophorone diamine and isophthalic acid of the polyamide component of the layer (c) is at least 1 to 10 wt %, most preferably 2 to 6 wt %, based on the total weight of the polyamide component.

[0029] The thermoplastic polyesters mentioned before useful for the production of the layer (e) can also be used for producing the layer (c).

[0030] With the composition of the layer (c) as barrier layer and with appropriate selection of suitable polymers it is possible to provide a multilayer polymeric film having also a DIN 53380-3 oxygen permeability which is significantly reduced which amounts up to 10.00 cm.sup.3/(m.sup.2dbar) at 23.degree. C. and 50% rh.

[0031] The oxygen permeability of the multilayer polymeric film used according to the invention can be further reduced to at most 8 cm.sup.3/(m.sup.2dbar), preferably at most 7 or 6 cm.sup.3/(m.sup.2dbar), more preferably at most 5, 4 or 3 cm.sup.3/(m.sup.2dbar), even more preferably at most 2, 1 or 0.5 cm.sup.3/(m.sup.2dbar), most preferably at most 0.4, 0.3 or 0.2 cm.sup.3/(m.sup.2dbar), and more particularly at most 0.1, 0.09 or 0.08 cm.sup.3/(m.sup.2dbar) (in each case at 23.degree. C. and 50% rh).

[0032] With the composition of the layer (c) as barrier layer and with appropriate selection of suitable polymers it is likewise possible to reduce the water vapor permeability of the multilayer polymeric film used according to the invention down to the values mentioned above for the oxygen permeability, the water vapor permeability being determined in accordance with DIN ISO 53 122.

[0033] If layer (c) functions as barrier layer (c), it is preferably connected to the adjacent layers via adhesion promoter layers (b) and (d).

[0034] Suitable thermoplastic polymers which can be used as adhesion promoting materials are known to the skilled person. The adhesion promoter layers (b) and (d), identically or differently, are preferably based on a preferably modified polyolefin and/or olefin copolymers, preferably selected from the group comprising carboxyl group-modified or cyclic anhydride group-modified polyethylenes, polypropylenes, more particularly maleic anhydride group-modified polyethylenes, polypropylenes, and ethylene-vinyl acetate copolymers. Preferred are maleic anhydride-modified PE, PE modified with COOH groups, carboxyl group-modified copolymers of ethylene-vinyl acetate, or of ethylene(meth)acrylate or anhydride-modified ethylene-vinyl acetate copolymers, and a polymer blend containing at least two of the mentioned polymers. Copolymers modified with maleic anhydride are particularly preferred.

[0035] In one preferred embodiment the polymeric film employed in accordance with the invention has at least a five-layer sequence of [0036] (a) a layer (a) based on a mixture of polyethylenes, preferably composed of a mixture of MDPE and LDPE or of LLDPE and LDPE and optionally further fillers and auxiliaries, [0037] (b) an adhesion promoter layer (b), [0038] (c) a barrier layer (c) based on a polyamide, preferably aliphatic polyamide, or copolyamide, preferably a (partially) aromatic copolyamide, [0039] (d) a further adhesion promoter layer (d), and [0040] (e) a layer (e) based on a mixture of polyethylenes, preferably composed of a mixture of MDPE and LDPE or of LLDPE and LDPE.

[0041] In a further particularly preferred embodiment the multilayer polymeric film used according to the invention comprises more than one layer (c) and comprises the following layer sequence: [0042] (a) an optionally heat-sealable, optionally multi-ply layer (a) preferably of at least one thermoplastic olefin homopolymer or copolymer or mixtures thereof, which is optionally coated with a release layer as surface layer, [0043] (b) an adhesion promoter layer (b), [0044] (c) a layer (c) preferably based on at least one homopolyamide and/or copolyamide, [0045] (b) optionally a further adhesion promoter layer (b), [0046] (c) a further layer (c), preferably based on at least one homopolyamide and/or copolyamide, or ethylene-vinyl alcohol copolymers, [0047] (d) a further adhesion promoter layer (d), and [0048] (e) an optionally heat-sealable surface layer (e) based on at least one thermoplastic olefin homopolymer or copolymer or mixtures thereof, with at least one surface layer preferably being heat-sealable.

[0049] The layers (c) are preferably based on homopolymers, copolymers or mixtures of polymers as described before, more preferably on copolyamides or ethylene-vinyl alcohol copolymers. The other layers as well correspond preferably in their composition to the details given before in relation to these layers and have the mentioned property profile.

[0050] The layers of the multilayer polymeric film used according to the invention can in each case contain the same or different additives selected from the group encompassing antioxidants, antiblocking agents, antifog agents, antistats, active antimicrobial ingredients, light stabilizers, UV absorbers, UV filters, dyes, color pigments, stabilizers, preferably heat stabilizers, process stabilizers, and UV and/or light stabilizers, preferably based on at least one sterically hindered amine (HALS), process assistants, flame retardants, nucleating agents, crystallizing agents, preferably crystal seed formers, lubricants, optical brighteners, plasticizers, silanes, spacers, fillers, such as CaCO3, silicates, peel additives, seal additives, waxes, wetting agents, surface-active compounds, preferably surfactants, and dispersants.

[0051] The layers of the polymeric film can contain at least 0.01-30 wt %, preferably at least 0.1-20 wt %, in each case based on the total weight of an individual layer, of at least one of the before mentioned additives.

[0052] Advantageously, by the monoaxial orientation of the polymeric film used according to the invention a tear propagation resistance in machine direction is obtained which differs by at least 30%, preferably up to 50%, from the tear propagation resistance transverse to the machine direction (measured according to DIN 53356-trouser leg). Thus, an inventive packaging produced from such a preferably multilayer and monoaxially oriented polymeric films is easy to open outside any seal seam region and the optionally present adhesive seam regions, i.e., without the need of the end user for opening a seal seam or adhesive seam for this purpose.

[0053] Furthermore, the difference in the tear propagation resistance can also be increased by a corresponding monoaxial stretching and thereby the difference in the tear propagation resistance modified in the desired amount.

[0054] In this context it has been found that, surprisingly, additionally monoaxially stretching a polymeric film in machine direction, which is already monoaxially oriented and having an at least five-layer sequence, comprising a barrier layer, which is composed preferably of a partially aromatic copolyamide, a film with a tear propagation resistance in machine direction up to 50% higher than the tear propagation resistance transverse to the machine direction is obtained. As a result it is possible not only to produce the wrapper-type packaging of the invention with far less reject material, but also to facilitate the tearing of an inventive packaging by a corresponding marking, as for example by notching, to identify the tearing direction for the end user.

[0055] The polymeric film used according to the invention can also be embossed. As a result at least a certain area of the surface layer (a) has an embossed structure, more preferably the entire surface of the layer (a), preferably with the exception of the seal seam regions.

[0056] This embossed structure of such release film used according to the invention is based preferably on a repeating, regularly or irregularly arranged pattern. The embossed structure can be a continuous embossed structure such as a continuous groove structure, for example, or two or more, preferably repeating, individual embossed structures, or a regularly repeating but inherently random embossed structure, in each case corresponding to the embossing roll employed.

[0057] According to one embodiment, each embossed structure can be based on a multiplicity of preferably repeating individual embossed structures. These respective individual embossed structures can be based preferably on a structure with embossment indentations (grooves), which have more or less pronounced embossment elevations such as ridges, for example, by which the embossed height of the embossed structure is defined. In accordance with the respective geometry of the elevations of a preferably repeating individual embossed structure, a plan view may show a multiplicity of respectively different, preferably repeating, individual embossed structures such as, for example, preferably serpentine, sawtooth, hexagonal, diamond-shape, rhomboidal, parallelogrammatical, honeycomb, circular, dot-shaped, star-shaped, rope-shaped, reticular, polygonal, preferably triangular, tetragonal, more preferably rectangular and square, pentagonal, hexagonal, heptagonal, and octagonal, wire-shaped, ellipsoidal, oval, and lattice-shape-designed patterns, it also being possible for at least two patterns to be superimposed on one another. The embossment elevations may each preferably have a length in longitudinal direction of up to one centimeter, particular preference being given to a length of 0.001 mm to 10 mm. The fraction of the elevations as a proportion of the total length of the structure with indentations can be preferably 75%, more preferably from 5% to 60%, and very preferably from 10% to 50%. The elevations are arranged preferably at uniform or alternating repeating distances. The elevations of the individual embossed structures may also preferably have a curvature, i.e., a convex or concave structure.

[0058] In a further preferred embodiment, the embossed structure has repeating units of randomly arranged embossment indentations and embossment elevations. The embossment elevations of the embossed structure are to amount preferably to .ltoreq.75%, more preferably 50%, based on the overall embossed area of the polymeric film of the invention.

[0059] The embossment elevation of the optionally uniform embossment elevations of the polymeric film used according to the invention amounts preferably to .gtoreq.5 .mu.m as measured according to DIN 53370 2006.

[0060] The embossment elevation of the embossed structure of the polymeric film used according to the invention is determined in accordance with DIN 53370 2006 by mechanical scanning of the surface. In this procedure, the embossment elevations are measured at not less than 10 locations, distributed uniformly in a line over the web width of the sample, it being necessary to ensure that the scanning device does not compress the embossed structure of the polymeric film, and the average of the measurements is formed, from which the thickness of the corresponding unembossed polymeric is subtracted.

[0061] In a further preferred embodiment, the polymeric film used according to the invention has an asymmetric embossed structure, i.e., an embossed structure which is present consistently throughout the film and provides both the top face and the bottom face of the film with an embossment, meaning that these faces are no longer planar, but the extent of the embossment is different on the two faces of the film. Below, the top face of the film is identified as that film side on which the embossing tool acts or has acted. The bottom face of the film, accordingly, may have a weaker embossment (negative form).

[0062] The effect achieved by the embossment of the polymeric film used according to the invention is not only to obtain a release effect on the part of the polymeric film used according to the invention but also, surprisingly, to reduce the shrinkage of the oriented and optionally stretched polymeric film drastically, by more than 50% in comparison to a corresponding oriented and optionally stretched, unembossed polymeric film.

[0063] The oriented, optionally stretched and embossed polymeric film employed in accordance with the invention, moreover, has excellent tensile strength, good to very good tear characteristics, and an excellent puncture resistance, which markedly improves the handling and the opening characteristics of the packaging according to the invention.

[0064] The multilayer polymeric film used according to the invention may also have a release coating on a surface layer, to improve its release effect, said surface layer being that which comes into contact with the packaged product in the context of the inventive wrapper-type packaging that is produced from the film.

[0065] The release coating is based preferably on a cured polysiloxane coating, with which the polymeric film employed in accordance with the invention may be furnished even prior to any occurring orientation or after this additional orientation. The release coating that generates release effect is present over substantially the whole area, preferably except for at least one stripe which extends in machine direction, or over a partial area, preferably in the form of in-register transverse stripes with all of the seal seam regions of the packaging of the invention preferably not being furnished with a release coating.

[0066] The term "polysiloxane" in the sense of the present invention refers to compounds whose polymer chains are constructed alternately of silicon atoms and oxygen atoms. A polysiloxane is based on n repeating siloxane units --[Si(R.sub.2)--O]--, which each independently of one another are disubstituted by two organic radicals R, with R preferably being in each case R.sup.1 or OR.sup.1, and with R.sup.1 in each case being an alkyl radical or an aryl radical. The cured polysiloxane coating is preferably based on a repeating dialkylsiloxane unit or on a repeating alkylarylsiloxane unit. Depending on the number of Si--O bonds possessed by an individual siloxane unit, based in each case on a tetravalent silicon atom, these units may be differentiated as terminal monofunctional siloxanes (M) having one Si--O bond, difunctional siloxanes (D) having two Si--O bonds, trifunctional siloxanes (T) having three Si--O bonds, and tetrafunctional siloxanes (Q) having four Si--O bonds. The polysiloxane coating of the invention preferably has a crosslinked cyclic or catenated structure, more preferably a crosslinked catenated structure, which is linked by (D), (T) and/or (Q) units to form a two- or three-dimensional network. The number n of the repeating siloxane units --[Si(R.sub.2)--O]-- in the polysiloxane chain is termed the degree of polymerization of the polysiloxane.

[0067] The cured polysiloxane coating of the polymeric film employed in accordance with the invention is based preferably on at least one cured, i.e., crosslinked, polysiloxane selected from the group comprising addition-crosslinked, preferably addition-crosslinked with metal catalysis, condensation-crosslinked, radically crosslinked and/or cationically crosslinked polysiloxanes.

[0068] More preferably the polysiloxane coating is based on at least one cured polysiloxane which has been cured by thermocuring and/or under the action of UV radiation. The polysiloxane coating is based preferably on at least one cured polysiloxane selected from the group comprising polydialkyl siloxanes, preferably polydimethyl siloxanes and polyalkylaryl siloxanes, preferably polymethylphenyl siloxanes, which in each case are cured. Thermally cured polysiloxanes may be obtained by thermal hydrosililation of polysiloxanes containing silane functions, using a compound having at least one carbon double bond. If orientation of the film used according to the invention is carried out, thermocuring, as well as UV curing, takes place preferably after orientation of the polymeric film employed in accordance with the invention.

[0069] The polymeric film used according to the invention can be produced in principle by any known production methods, such as by extrusion or by coextrusion, for example.

[0070] Here, both individual layers and all the layers of the polymeric film used according to the invention may be formed by extrusion, more particularly by blown film extrusion and/or flat film extrusion (cast extrusion), or preferably coextrusion, more particularly blown film coextrusion and/or flat film coextrusion (cast coextrusion), the latter being preferred. Here it should be ensured that in the case of doping of the layer (a) or of other layers with additives, these additives are employed by blending, where appropriate as a masterbatch, with the polymer component or components of the respective layer for processing. This blending may take place dry in pellet/powder form or pellet/pellet form. An alternative possibility is for the additive to be added to the melted polymer component or components of the respective layer, preferably by metering in an extruder used for the extrusion of the layer in question.

[0071] After the coextrusion process, which is known per se, the melts corresponding to the individual layers of the polymeric film used according to the invention are coextruded simultaneously and jointly through a round die or a flat die, the resulting polymeric film is taken off for orienting and solidification on one or more rolls, at a rate conforming to the before mentioned removal ratio of at least 1:30, in such a way that the ratio of removal is greater than the rate of extrusion and the film oriented in this way is heat-set.

[0072] Subsequent monoaxial or biaxial stretching may be carried out sequentially or simultaneously. Sequential stretching is generally carried out successively, with preference being given to the successive biaxial stretching, where stretching is performed first longitudinally (in machine direction) and transversely (perpendicularly to the machine direction).

[0073] In the case of film production after flat film extrusion with any subsequent monoaxial or biaxial stretching, the polymer or the polymer mixture of the individual layers is compressed in an extruder and fluidized, it being possible for any additives added to be already present in the polymer or polymer mixture. The melts are then pressed simultaneously through a flat die (slot die) and the multilayer film extruded is taken off on one or more take-off rolls at a temperature of 10 to 100.degree. C., preferably 10 to 50.degree. C., with the rate of removal being necessarily greater than the rate of extrusion in order to achieve the before mentioned removal ratio, and it cools and solidifies.

[0074] The multilayer polymeric film used according to the invention can then optionally oriented either only longitudinally, or longitudinally and transversely to the extrusion direction, leading to further orientation of the molecule chains. Longitudinal orientation is carried out preferably at a temperature of 70 to 130.degree. C., preferably 80 to 110.degree. C., usefully with the aid of two rolls which run at different speeds in line with the target draw ratio, and the additional transverse orientation, when practiced, is carried out preferably at a temperature of 120 to 180.degree. C. by means of a corresponding tenter frame. The desired transverse orientation ratios can be set at this point. Orientation is preferably orientation in machine direction in accordance with the invention.

[0075] Any orientation taking place of the polymeric film used according to with the invention is followed preferably by its heat-setting (heat treatment) where the film is held for about 0.1 to 10 s at a temperature of 100 to 160.degree. C. Subsequently, where appropriate after interim storage, the polymeric film of the invention may be furnished with any release coating present. It is also possible for the extruded multilayer stretched polymeric film used according to the invention to be provided with any release coating even prior to orientation.

[0076] The flexible multilayer polymeric films used according to the invention can be transparent, transparently colored, opaque or non transparent. The film can have a printing on the outer side facing away from the packaged product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG. 1 shows an inventive wrapper-type packing in plan view.

[0078] FIG. 2 shows a plan view of the wrapper-type packaging of FIG. 1 in the opened condition.

[0079] FIG. 3 shows a further embodiment of the inventive wrapper-type packaging in plan view.

[0080] FIG. 4 shows a plan view of the wrapper-type packaging of FIG. 3 in the opened condition.

[0081] FIG. 5 shows a further embodiment of the inventive wrapper-type packaging in plan view.

[0082] FIG. 6 shows a plan view of the wrapper-type packaging of FIG. 5 in the opened condition.

[0083] FIG. 7 shows a further embodiment of the inventive wrapper-type packaging in accordance with FIG. 1, without transverse sealing of the closure tab, in plan view.

[0084] FIG. 8 shows a plan view of the wrapper-type packaging of FIG. 7 in the opened condition.

[0085] FIG. 9 shows a further embodiment of the inventive wrapper-type packaging in accordance with FIG. 3, without transverse sealing of the closure tab, in plan view.

[0086] FIG. 10 shows a plan view of the FIG. 9 in the opened condition.

[0087] FIG. 1 shows an embodiment of the inventive wrapper-type packaging (1), produced from a single film web of the before described multilayer film used according to the invention. The wrapper-type packaging comprises a bag with an opening (7) from which the packaged product can be removed after opening. The bag is formed from a front wall (2) and a rear wall (3) by folding the film along the folding line (6). By means of a closure flap (8) which is formed by a projection of the rear wall (3) and which is folded at a distance from the opening (7) of the bag onto the front wall (2) along the folding line (12), the wrapper-type packaging is closed completely by means of the closure flap (8) by longitudinal sealing (9, 10) and transverse sealing (11) of the inner layer of the closure flap (8) against the outer layer of the front wall (2). For production-related reasons the transverse seal seam (11) is placed at a distance from the edge of the packaging flap.

[0088] Instead of the transverse seal seam (11), the closure flap (8) can also be bonded to the front wall (2) by means of a strip of an adhesive, which runs transversely on the inside of the closure flap, in which case the bond strength of the adhesive, should correspond to the seal strength of a seal seam that is ponding the parts, which is preferably greater than the tear propagation resistance of the inventive wrapper-type packaging in the direction of the marking for the opening of the packaging. Suitable commercial adhesives suitable are known to the person skilled in the art. An opening aid (13), shown as a notch, marks the direction of opening of the inventive packaging, in which the tear propagation resistance is lower than in the direction extending transversely thereto.

[0089] FIG. 2 shows a plan view of the inventive wrapper-type packaging in accordance with FIG. 1, in which a part (14) of the packaging, which is already torn away from the packaging to a predominant extent, starting from the notch (13), via the opening (7) with the packaged product (not shown). Furthermore, on the front wall (2) of the inventive packaging, the side seal seams (11) which extend longitudinally, and the seal seams placed transversely for the closing of the closure flap (8), can be seen to be intact, and so the packaged product can be removed without effort and destruction of the rest of the packaging.

[0090] FIG. 3 shows a further embodiment of the inventive wrapper-type packaging, which differs from the packaging shown in FIG. 1 in that the marking (13) of the direction of opening is located on the folding line (12) of the closure flap. This notch could also be replaced by a barcode (not shown) or could be located in the edge region of the closure flap (8) beneath the transverse seal seam (11) and at right angles to the seal seam (11).

[0091] FIG. 4 shows a plan view of the wrapper-type packaging according to FIG. 3 in the predominantly open condition, and without the packaged product, which has already been removed. Again, on the front wall of the wrapper-type packaging, the transverse seal seam (11) of the closure flap and also the seal seams extending at the sides longitudinally can be seen to be intact.

[0092] Shown in FIG. 5 is a further preferred embodiment of the inventive wrapper-type packaging. According to this packaging, the closure tab (8) is joined to the front wall (2) directly at the level of the opening (7) of the bag, with the edge region of the closure flap being connected to the opening edge region of the front wall by means of a transverse seal seam, formed as so called fin seam. This fin seam has a notch (13) for marking the direction of opening.

[0093] FIG. 6 shows a plan view of the inventive wrapper-type packaging as per FIG. 5, in the partly opened condition and after removal of the packaged product; again, the seal seams extending at the sides longitudinally, and the fin seam extending transversely can be seen to be intact, apart from the tearing along the notch.

[0094] FIG. 7 and FIG. 8 correspond to FIG. 1 and FIG. 2, with the exception that the wrapper-type packaging has no transverse seal seam for the closing of the closure flap. Since, however, the seams (9) and (10) extending at the sides longitudinally are seal seams, and the packaging has a notch as opening aid, the consumer is able to remove the packaged product without effort and without any need for side seal seams to be torn open, in order to get to the packaged product. In spite of the effortless opening of the wrapper-type packaging according to FIG. 7, this wrapper-type packaging ensures a better security during transport and storage than corresponding packaging with less secure side seams for closure.

[0095] Since FIG. 9 and FIG. 10 correspond to FIG. 3 and FIG. 4, with the exception of a transverse seal seam for closing the closure flap, for these embodiments of the invention the same explanations as mentioned in relation to FIG. 7 and FIG. 8 are of relevance.

[0096] Based on the difference in tear propagation resistance between the tear propagation resistance in machine direction and transverse to the machine direction, the inventive packagings, as shown in FIGS. 1 to 6 among others, can be opened easily, without the possibility of an unallowed access to the packaged product before the intended opening for removing the packaged product and the therefore partial destruction of the wrapper-type packaging takes place. In spite of this excellent security against manipulation of the packaged product, the inventive wrapper-type packaging is easy to open.

[0097] The inventive wrapper-type packaging can be produced according to known, conventional techniques; whereby during production the difference in tear propagation resistance of the film and the related opening behavior of the packaging produced therefrom, has to be taken into account.

[0098] The inventive wrapper-type packaging is especially suitable for the packaging of articles which are intended for single use, preferably hygiene articles intended for single use, more particularly sanitary towels, tampons, panty liners or incontinence articles that are intended for single use.

[0099] Furthermore, the inventive wrapper-type packaging is suitable as individual packaging for adhesive articles of any kind, more particularly as individual packaging for self-adhesive articles intended for single use, more preferably for self-adhesive hygiene articles intended for single use. Very preferably the inventive wrapper-type packaging is suitable for the packaging of self-adhesive panty liners, self-adhesive sanitary towels or self-adhesive incontinence articles which are intended for single use and are packaged preferably in the folded shape.

Claims

1: A wrapper-type packaging composed of a flexible polymeric film in the form of a sack or bag, having a front wall and a rear wall, which are opposite to one another and are sealed in each case by a side sealing seam to form a sack like or bag like tube, of which the opening is covered by a closure flap which is formed by a projection of the rear wall and is folded onto the front wall, and also closed by respectively longitudinal side sealing and optionally transverse sealing or adhesive bonding, and optionally having an opening aid, wherein the flexible polymeric film is comprised of to an extent of at least 50 wt % of polyolefins, has through monoaxially orientation a tear propagation resistance in machine direction which differs by at least 30% in relation to the tear propagation resistance in the direction transverse to the machine direction, measured according to DIN 53356-trouser leg, and the opening aid marks the direction of relatively low tear propagation resistance for opening the packaging without tearing one of the sealed seams.

2: A wrapper-type packaging as claimed in claim 1, wherein the at least longitudinally side sealed closure flap projects over the opening of the sack or bag and does not fully cover the front wall of the packaging and the packaging optionally has a marking in the opening direction in the form of a notch or of a barcode.

3: A wrapper-type packaging as claimed in claim 1, wherein the closure flap does not fully cover the front wall of the packaging, and the lower edge region of the closure flap is transversely sealed with the longitudinal, unsealed edge region of the opening of the sack or bag in the form of a fin seam, and the fin seam has a notching, extending optionally perpendicular thereto, for marking the direction of opening.

4: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film has a draw ratio of at least 1:2 in machine direction.

5: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film is comprised to an extent of at least 70 wt % of polyolefins.

6: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film contains as polyolefins polyethylenes (PE), optionally LDPE, MDPE, LLDPE, HDPE, polypropylenes (PP) or a mixture of at least two of said polyethylenes.

7: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film has at least one layer, optionally at least two layers based on a mixture of polyolefins, at least one barrier layer, optionally at least a barrier layer against gasses, against fats and oils, against migration of low molecular mass organic compounds and/or against moisture.

8: A wrapper-type packaging as claimed in claim 7, wherein at least one layer of the polymeric film is based on heat-sealable polyolefins.

9: A wrapper-type packaging as claimed in claim 7, wherein the barrier layer of the polymeric film is based on ethylene/vinyl alcohol copolymers, polyvinyl alcohols, polyamides, copolyamides, polyesters and/or a polyether/polyamide block copolymer.

10: A wrapper-type packaging as claimed in claim 9, wherein the barrier layer is based on an aliphatic polyamide or (partially) aromatic copolyamide, and optionally based on a copolyamide of .epsilon.-caprolactam, isophoronediamine and isophthalic acid units.

11: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film has at least a five-layer sequence of (a) a layer (a) based on a mixture of polyethylenes, and optionally further fillers and auxiliaries, (b) an adhesion promoter layer (b), (c) a barrier layer (c) based on a polyamide, or copolyamide, (d) a further adhesion promoter layer (d), and (e) a layer (e) based on a mixture of polyethylenes.

12: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film has a polymeric film with release effect.

13: A wrapper-type packaging as claimed in claim 12, wherein the release effect of the polymeric film is based on an at least partial embossment on at least the inside surface of the polymeric film facing the packaged product.

14: A wrapper-type packaging as claimed in claim 13, wherein the embossment of the polymeric film has an embossment elevation of 5 .mu.m, measured according to DIN 53 370 2006.

15: A wrapper-type packaging as claimed in claim 13, wherein the embossed polymeric film has a shrinkage of at least 50% lower than the shrinkage of a corresponding unembossed, polymeric film.

16: A wrapper-type packaging as claimed in claim 12, wherein the release effect of the polymeric film is based on a release coating on the inside surface of the polymeric film facing a packaged product.

17: A wrapper-type packaging as claimed in claim 13, wherein the polymeric film has neither an embossment nor a release coating in the regions of the longitudinal side sealing and of the transverse sealing respectively.

18: A wrapper-type packaging as claimed in claim 1, wherein the polymeric film has a total thickness of .ltoreq.30 .mu.m.

19: A wrapper-type packaging as claimed in claim 1 as individual packaging for an article packaged therein.

20: A wrapper-type packaging as claimed in claim 1 as individual packaging for a self-adhesive article of any kind packaged therein.

21: A wrapper-type packaging as claimed in claim 1 as individual packaging for a self-adhesive hygiene article.