AU673399B2

AU673399B2 - Tube for storage and dispensing of a product

Info

Publication number: AU673399B2
Application number: AU55292/94A
Authority: AU
Inventors: Jacques Benquet; Michel Rebeyrolle
Original assignee: Cebal SAS
Current assignee: Albea Tubes France SAS
Priority date: 1993-02-22
Filing date: 1994-02-21
Publication date: 1996-11-07
Anticipated expiration: 2014-02-21
Also published as: HU9400468D0; FI940816A; BG61335B1; CA2115705C; IL108682A0; RO113447B1; PL302323A1; CZ40194A3; IL108682A; HK1001042A1; BR9400628A; TNSN94015A1; ATE152040T1; CA2115705A1; BG98497A; KR0127770B1; NZ250882A; MX9401227A; MA23117A1; JPH06297599A

Abstract

The subject of the invention is a storage and dispensing (distribution) tube (C) for a product, for example a water-containing product which may be flavoured or perfumed, comprising a dispensing head which is fixed onto a flexible multilayer skirt, this skirt essentially containing an intermediate polymer layer (20) which has a barrier effect with respect to oxygen and flavours or perfumes, the said layer being sensitive to humidity, as well as, on each face of this intermediate layer, one or more polymer layers (1; 12,14,10) based on polyolefins, all of the said layers being bonded together in a continuous manner, characterised in that the set of layers situated on the inner face of the said intermediate layer having a barrier effect (1,21) has a total thickness of between 40 and 150 micrometres, so as better to conserve the flavour or the perfume which is or may be contained therein. This tube preferably includes one or two means which render the dispensing of the contained product easier and more complete. It applies to the industries for packaging products which are, for example, liquid, creamy or pasty. <IMAGE>

Description

L I TUBE FOR STORAGE AND DISP S\CG OF A PRODUCT The invention concerns a tube for the storage and dispe\s'ng of a product which is typically liquid, creamy or pasty, the tube making it possible for the flavour or scent of the product contained therein to be satisfactorily preserved.

EP-A-0 084 922 US-A-4 626 456 discloses a tube for the storage and dispensn of a product which is for example flavoured or scented and which contains water, the tube ccmprising a distribution head which is fixed on a flexible multi-layer skirt, which skirt essentially comprises an intermediate layer with a barrier effect relative to oxygen and flavourings or scents, said layer being sensitive to moisture, and oin each face of said intermediate layer one or more polymeric layers based on polyolefins, all said layers being joined together. The product contained in the tube is for exanple toothpaste and the intermediate layer with Jhe barrier effect is for example of EVOH (copolymer of ethylene and vinyl alcohol). The structure of the skirt without metallic intermediate layer and ccmprising layers essentially of polypropylene which are filled with powders for example S. of Ca carbonate, mica or talc makes it possible to achieve good retention of the folds produced when the tube is squashed.

20 Such a skirt has been observed to suffer frcm two disadvantages.

On the one hand, and is known for example from US-A-4 407 897, EVOH is highly sensitive to moisture. A toothpaste generally contains 20 to by mass of moisture and substantial losses of flavour of such a paste have been found with multi-layer tubes with a barrier layer of EVOH. In addition it has been found that retention of the local squeezing phenomena of the tubes made it difficult to empty the tube.

In addition patent application GB-A-2 048 209 discloses a tube for a product such as toothpaste, in which the skirt of multi-layer I I I~ I Iplastics materials is of suitable deformability for successive pressings and has a high level of resistance to interlaminar separation phenomena. That skirt comprises at least one barrier layer in relation to oxygen, comprising EVOH or PA (polyamide), a layer of olefin and an adhesive layer of modified olefin interposed between the two preceding layers.

Interlaminar separation of those layers is avoided by virtue of the adhesive layer having an elastic limit which is lower than that of the barrier layer and higher than that of the olefin layer. At the same time the olefin layer is of greater thickness than the sum of the thicknesses of the barrier layer and the adhesive layer and the product of the elastic limit by the thickness of the olefin layer is from 9 to 170 kg/cm; those means improve deformability and restoration of the tube, each time it has been pressed. That document does not indicate how the losses of flavour which are found in the absence of interlaminar separation of the skirt of the tube are to be avoided.

The applicants sought to develop a tube which can provide for improved preservation of the flavour or scent of a product contained therein. The applicants further sought to provide that the tube permits easier and more complete distribution of the product.

There is disclosed herein a tube for the storage and distribution of a product which is for example flavoured or scented and which contains water, comprising a disLibution head which is fixed on a flexible multi-layer skirt, said skirt essentially comprising an intermediate polymeric layer with a barrier effect relative to oxygen and flavouring or scents, said layer being sensitive to moisture, and on each face of said intermediate layer one or more polymeric layers or and based on polyolefins, characterised in that a) the surface layers are of low density polyethylene (LDPE); b) a first layer of high density polyethylene (HDPE) is inserted between an internal layer of low density polyethylene (LDPE) and a first intermediate layer of LDPE which is disposed inside the intermediate barrier-effect layer and/or a second layer of high density polyethylene (HDPE) is inserted between an internal layer of low density polyethylene (LDPE) and a second intermediate layer of low density polyethylene (LDPE) which is disposed outside the intermediate barrier-effect layer; c) the assembly of the layers which are located on the internal face of said intermediate barrier-effect layer is of a total thickness of between 55 and 140 micrometres, so as better to preserve the flavouring or the scent of a product which is or may be contained therein.

The applicants' interpretation on this subject is as follows: when the thickness of the layers disposed on the internal face of the barrier-effect layer is smaller than micrometres, the moisture in the product which passes through those layers causes a r$7 rapid degradation in terms of the barrier qualities in relation to oxygen and N:LB 48'40 r~\i~-LU'

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[N:\LIBLLa0489:JCC ~PLeP a~ L -L I the flavours or scents of the barrier-effect layer, and the flavours or scents of the product can progress beyond that layer and even escape from the tube.

When the thickness of the layers in question is greater than 150 micrometres, the moisture does not reach the intermediate barriereffect layer in a sufficient amount to cause a deterioration in its qualities, but the flavours or scents are absorbed and retained in a substantial amount by said layers. Those flavours or scents are typically compounds in solution in the water contained in the product, and evaporation and absorption thereof in a first approximation follow evaporation and absorption of the water forming the moisture in the product.

GB-A-2 048 209 does not make it possible to foresee such effects, in spite of the magnitude thereof, and it affords no direct or indirect indication relating to the thickness of the layers disposed on the internal face of the barrier layer.

Even better results in terms of preserving the flavours or the scents of the product contained in the tube are achieved when the total thickness of the layers on the intermediate barrier-effect layer is 20 between 55 and 140 micrometres and still more preferably between 65 and 130 micrnmetres, with an optimum value of 70 to 120 micrometres.

The foregoing conditions permit the use for the structure of the tube of economic polyolefins, giving excellent welding of the layers to each other, namely the family of polyethylenes. The applicants are thus interested in a tube in which the polymeric layers based on polyolefins of the skirt consist on the one hand of an internal surface layer of low or very low or linear low density polyethylene, of a specific mass of between 0.86 and 0.93 g/an 3 and on the other hand, other layers which are respectively either of low density polyethylene (LDPE), of a specific mass of between 0.90 9nd 0.93 g/an3 or high density polyethylene (HDPE), of a specific mass of g~~ri~arrar~--~c~ 3 II I 3 between 0.935 and 0.97 g/a-n Wishing then to make distribution of the product stored in the tube of the invention easier and more ccomplete, which tube better preserves the flavour or scent of said prcduct, the applicants ascertained that it was possible to avoid local crushing effects due to the tube being pressed, by enhancing the elastic resistance to depression of said skirt. For that purpose the polyethylene layers of the skirt of the tube contain one or more layers of HDPE of a total thickness of greater than or equal to 90 micrcrnetres. Tests show that, when the total thickness of 1-DPE ooes fran 84 to 125 micrcrnetres, the elastic reaction force of the skirt in response to depression thereof is more than double. When the thickness of the skirt is between 260 and 380 micranetres, for example in the case of a toothpaste tube, the total thickness of the HDPE layers is preferably between 100 and 140 micranetres, the surface layers preferably being of LDPE, or else for the internal layer linear low density PE. In fact, the properties sought for those surface layers are gocd ductility with gocd aptitude to impression in regard to the exterior of the tube and good resistance to micro-cracking phenomena in the interior of the tube.

20 The ranges of total thickness in respect of the HDPE which are set out above are to be transposed into relative values with respect to the :thickness of the skirt if the latter is outside the specified range.

For that increase in elastic reaction of the skirt to being depressed, account can be taken of the influence of the intermediate barriereffect layer which has more elevated characteristics than the HDPE of P:the same thickness. For the skirt thickness specified above, the sum of twice the thickness of said barrier layer and the total thickness of the HDPE layers is preferably between 130 and 180 micrcrnetres, in which case the foregoing condition relating just to the total 30 thickness of the layers of HDPE may or may not be satisfied.

To facilitate manufacture, having surface layers of the nature specified above, that is to say typically of LDPE, it is preferable, to obtain the desired total thickness of HDPE, to use: l~ll -I 1 either a first layer of HDPE which is inserted between said internal surface layer and a first intermediate layer of LDPE which is itself disposed outside the intermediate barrier-effect layer or a second layer of HDPE which is inserted between an external layer of LDPE and a second intermediate layer of LDPE which is itself disposed outside the intermediate barrier-effect layer.

Such first and second layers of HDPE are conveniently employed simultaneously, with thicknesses which are respectively between 10 and micrcmetres and between 60 and 140 micrcmetres.

The layer or layers of HDPE are typically 'in a condition of continuity of fusion' with the layers between which they are inserted, their materials being compatible in terms of fusion and the production process having produced a welding effect with perfect continuity of structure of the layers between each other. A layer of HDPE which is inserted in that way can then be distinguished in cross-section by micro-hardness measurements, not by virtue of the appearance of its structure. Layers which are welded in that way are obtained by coextrusion of the skirt or by welding with overlap of the edges of a multi-layer blank which itself results fran one or more colaminatics 20 after assembly operations using a covering by extrusion of molten PE.

Typically, the first and second intermediate layers of PE are each joined to a face of the intermediate barrier-effect layer that they enclose by means of a bonding layer, often of EAA or EMA. The five layers in question are often used in the form of a multi-layer item which is prepared in advance and in which the barrier-effect layer, being sensitive to moisture, is relatively well protected in that regard.

Among the materials for the intermediate barrier-effect layers of the skirt, which are sensitive to moisture, mention may be made of 30 EVOH and PVOH (polyvinyl alcohol), the deterioration of which due to moisture is described in above-mentioned US-A-4 407 897, and with a •degree of sensitivity smaller polyamides and modified polyamides, e* MI rr--9- II I I for example polymetaxylylene adipamide (MXD6). Such an intermediate barrier-effect layer is in the skirt of a thickness which is typically between 0.01 and 0.05 mm, and there may be a plurality of barrier-effect layers which are preferably altogether of the total thickness specified above.

In order to make distribution of the product stored in the tube of the invention easier and more complete, the applicants developed a second means which can be used alone or in combination with the first means, requiring a minimum thickness in respect of the HDPE layers of the skirt, of greater than 90 micrometres.

The second means referred to above is to have a squashable annular shoulder between the skirt and the neck of the tube. It is known that the shoulder of known tubes, by virtue of the ways in which they are produced, are rigid and form a kind of wall retaining a fraction of the product to be distributed, which product is typically creamy or pasty. By virtue of the production process which is the subject-matter of the present applicants' French patent application No 93 01065 of 27th January 1993, that preferably affords a tube in which the distribution head comprises a neck of smaller diameter than the skirt and an annular shoulder connecting the neck to the skirt, the shoulder being smooth and of a thickness of between 0.9 times and 1,35 times and preferably between 0.8 times and 1.25 times the thickness of the skirt and affording continuity of structure with the skirt and comprising folds which are squashed and welded to each other, said shoulder being easily squashable laterally. The squashed and welded folds include extensions of the barrier layer or layers in the skirt and hence e" the shoulder, and typically at least a part of the neck of the tube, contain a barrier layer or layers. The neck may be completed by an annular ring of PE which is welded to the head such that at least half of the shoulder remains squashable.

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[N:\LIBLL]00489:JCC Cpb~P~sa 1 I I The second means therefore affords both the possibility of easier and more complete distribution of the product contained in the tube, and improved protection for its flavouring or scent, at the level of the head of the tube. The folds which are reduced in thickness at locations in a barrier layer in the shoulder usually together satisfy the preferred condition regarding a total thickness '0.01 to 0.05 mm', with increased effectiveness. The production process leading to that second means will be briefly described in the Examples.

Examples Figures 1 to 3 are sectional views of the skirts of three tubes, the first being outside the invention (Figure 1, reference), while the other two (Figures 2 and 3) being in accordance with the invention, Figure 4 is a view in axial section of an arrangement for measuring the elastic reaction to depression of a tube skirt, in relation to the first means involving easier and more complete distribution of the product, Figure 5 is a graph showing the gain in weight of samples of skirts in dependence on the total thickness of the layers inside the barrier layer, in a flavouring loss test, *i 0*: i :"5 0 0 00 0i 0 [N:\LIBLL]00489:JCC prsllllSP~ C IP~ I I 8 Figure 6 shows in a graph the variation in the resistance to depression of the skirt in dependence on the total thickness of the layers of HDPE which are present therein, Figures 7 to 10 relate to the second means involving improved distribution, namely a squashable shoulder; Figure 7 is an isometric projection of a comparison tube produced by shaping at ambient temperature, Figure 8 is a half view in axial section of a tube according to the invention having a squashable shoulder, Figure 9 is a half view in axial section of another tube with a squashable shoulder, provided with an annular ring of PE constituting the exterior of its neck, and Figure 10 is a view in axial section of a micrographic aspect of the top of the shoulder of the tube and the connection of the shoulder to the annular ring.

1) Structure of the skirts of the tubes of Figures 1 to 3 These three structures all have an intermediate barrier-effect layer 20 of EVOH of a thickness of 0.02 mn, joined by two adhesive layers 21 and 22 of EMA coppolymer (copolymer of ethylene and methacrylic acid) each of a thickness of 0.01 mm to layers of PE Scomprising in contact with said bonding layers 21 and 22 LDPE with a S 3 specific mass of 0.92 g/cm in layer 1 or in intermediate sub-layer 11 or 12. The limits of layers of different natures are marked in solid lines while the invisible limits between LDPE and HDPE sub-layers, resulting from assembly thereof in a molten state at least at the surface, are shown by broken lines.

The term 'sub-layer' is used here in respect of such layers in which at least one limit surface is invisible, these are however layers entirely involved in regard to the technical functions studied 30 in the present invention. They may be identified by measurements in respect of micro-hardness.

9*9999 9* sBrST 'C L1 L~C' It can also be seen, frcm Figures 1 to 3, that the sub-layers 13 3 and 14 of HDPE, with a specific mass of 0.95 g/cm are each disposed between an intermediate sub-layer 11 or 12 of LDPE and an internal linear low density PE sub-layer 100 or an external LDPE sub-layer Going frcn the interior of the tube outwardly, the successions of thicknesses are as follows, the details of sub-layers being shown in parentheses: Tube A (Figure layer LDPE 0.035 rm; layers EMA '21' of 0.01 rim, EVOH '20' of 0.02 m, EMA '22' of 0.01 nrm; layer of PE '12+14+10' of 0.215 rm (LDPE '12' of 0.082 mn HDPE '14' of 0.105 rm external LDPE '10' of 0.023 m); Tube B (Figure internal layer of PE '100+13+11' of 0.09 rm (internal linear low density PE '100' of 0.01 rm HDPE '13' of 0.02 rm LDPE '11' of 0.06 succession of EMA, EVOH and EMA as for A; layer of PE '12+14+10' of 0.215 rm, of the same composition as for A; and Tube C (Figure internal layer of LDPE of 0.125 mm; succession of EM4A, EVOH and EMA as for A and B; layers of PE '12+14+10' of 0.175 rm (LDPE '12' of 0.073 rrm HDE '14' of 0.084 rrm external LDPE '10' of 0.018 rnm).

The skirts of the tubes A, B and C were rolled-welded frcm blank-forming films of the structures and thicknesses indicated above, then the heads of the tubes were moulded on to the skirts.

2) Flavouring loss tests 25 Circular portions of a diameter of 50 mn of the three qualities indicated above, as shown in Figures 1 to 3, were subjected to T ""impregnation of their face which is the internal face in the skirt, being that of the layer 1 or 100, with a standard toothpaste containing 25% of water and menthol, for a period of 4 weeks, being 30 maintained in an enclosure at 38°C.

At the end of the test toothpaste remaining at the surface of the sample is cleaned off. The gain in weight of the sample is ascertained, and it takes account of the loss of water and flavouring.

I~rs I ~pU I L I The wish is to have a quality which, in this test, gives a gain 2 in weight per unit of surface area of less than 1.2 mg/cm and preferably less than 0.66 mg/on 2 A is satisfactory in accordance with the first criterion but not the second. The results oi che tests are set out in Table 1 and shown in Figure Interpretation is as follows: there are no samples in which the barrier layer of EVOH is bare on the inward side of the sKirt as such a layer of EVOH would then be completely degraded by moisture during manufacture of the corresponding multi-layer ite a sample which in fact is theoretical, the result that uoserved in Figure 5 would be a high gain in weight, due to the fat that moisture passes easily through the EVOH and that such moisture is absorbed by the layers outside the EVOH. When one has 0.02 mn of layers which are internal to the EVOH, a considerable gain in 2 weight is still observed, more than 2.5 mg/cn 2 The gain in weight decreases considerably when the thickness of the layers which are internal to the EVOH exceeds 0.03 mn and the steep linear curve portion in which A is located corresponds to absorption with degradation of the EVOH due to the moisture, and then the passage through that EVOH of water and flavouring, the water and flavouring then being absorbed both by the layers which are external to the EVOH, at 21, 12, 14 and 10, and by the internal layers such as 21 and 1. The decrease from A to B corresponds to a preponderant protection effect in relation to the layer 20 of EVOH, by virtue of the increasing 25 thickness of the internal layers, and the subsequent rise frcm B to C corresponds to the influence, which has become preponderant, of the absorption of water and flavouring by the internal layers, their thickness and therefore their absorption capacity increasing as the EVOH is sufficiently protected.

30 3) Pressing test or test in respect of resistance to depression of the skirt A sample 15 of skirt is held in such a way as to form a I L IIBIL~L___III)I~L C II reproducible semicircular cylindrical dome 16 of a diameter of 25 mand a length of 100 mm, and it is pressed with a rigid rod 17 of a diameter of 3 rm along the linear generatrix 18 of the top of the dome. The broken line 19 indicates the shape assumed by the dome 16 when depression of the rod 17 at a constant speed has progressed.

A system (not shown) measures the reaction exerted by the dome 16 or 19 against the rod 17 and determines the maximun thereof. When that reaction is strong, the corresponding tube skirt resists better to pressing forces and depression thereof remains in part at least in the elastic range, which makes it possible to avoid local constrictions, which is opposite to the teaching of EP-A-0 084 922.

The results of the tests are shown in Table 2 and Figure 6. The representative points A, B and C are aligned in Figure 6. As the reaction in the absence of HDPE in the skirt, then entirely of LDPE except for the EVOH and the thin adhesive layers 21 and 22 which surround it, is necessarily slightly positive (representative point it can be seen that the effect of an increasing thickness of HDPE on reaction of the skirt to depression involves an increase which S"accelerates between 40 and 70 micrcmetres (broken-line curve portion

ZX).

At the level of the thickness of 90 micrcmetres which has been taken as a minimum, the effect is confirmed. The tube B according to the invention has a skirt which has good resistance to depression, but the tube C is inadequate in that respect. The tube A which is inadequate in relation to losses of flavouring and which therefore falls outside the scope of the invention claimed in the present application is satisfactory in terms of resistance to depression.

4) Second means of easier and more complete distribution of the product contained in the tube: tube with squashable shoulder (Figures 30 7 to The process for producing this tube involves starting from a tubular blank which is longer than the skirt and constricting a ~i~rlllS~BaP"I~ I- I L- U U I I Y L -e ~C I_ I 12 portion thereof by shaping just that portion which is heated above the fusion temperature of its surface layers, preferably at between 140 and 220°C in the case of surface layers of polyethylene, then crushing that portion between tools, so that the portion crumples in the form of folds, the folds perfectly welding to each other at each face thereof and the faces of the shoulder being typically obtained in a perfectly smcoth condition.

Figure 7 shows a tube having a shoulder formed at ambient temperature, showing that the double folds as at 31 and 32 correspond to inward undulations 31 or outward undulations 32, which have been squashed.

In the hot-shaping operation indicated above, the folds are greatly squashed, including those of the barrier layer 20 which are included therein. It is possible to produce a shoulder 33 whicn is thinner than the skirt. Figure 8 shows a tube 34 with a scre wthreaded neck, in accordance with the invention, which is produc.jd directly by that hot-shaping operation, the internal tool means and annular o .sliders of the external tool means forming between them the screwthread35 on the neck at the end of the clamping operation. Figure 20 9 shows a tube 36 of the same nature which is produced by hot-shaping and then capped by an external annular ring 37 of PE, to complete the neck of the tube. The ring 37 is perfectly welded to the outside and to the upper end. of the hot-shaped tube 36, it was set in position by shaping with compression of an annular blank of PE heated to 160 0

C,

25 this thus involving moulding in a pasty state which is above the melting point. An annular ring can also be set in position by injection moulding or by ultrasonic welding. The tubes 34 and 36 each have a skirt of type B, 0.345 rmn in thickness, which is not modified by the operation of hot-shaping of the head, and their annular 30 shoulder 38 is of a thickness which is adjusted as desired at between 0.3 and 0.4 mm. In the case of the tube 36 (Figure the annular

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I -C 13 ring 37 occupies less than half of the width of the annular shoulder 38, the latter can still be laterally squashed sufficiently to improve expulsion of the product.

Figure 10 shows a sectional view of the tube 36 in the region where the top of the shoulder 38 is joined to the annular ring 37. The view shows that the folds are effectively squashed and welded even in the constricted area around the head of the tube 36.

A double fold 39 of barrier layer 20 is sLown which comprises a substantially unsquashed end portion 40 and two folds 41 which have been squashed to a reduced thickness. The outer PE layers enclosing the barrier layer 20 of the double fold 39 have been effectively welded together into a continuous mass of PE. Similarly the PE enclosing a second portion 42 of barrier layer 20 has been effectively welded to the double fold 39. Adhesive layers 21 remain in areas between the barrier layers 20 and welded PE, but the composition remains continuous. The annular ring 37, also being composed of PE is also effectively welded to the PE layers of the double fold 39, resulting in a smooth continuous region of PE encasing the folded and squashed barrier layers Reduction in thickness of the region can be adjusted as desired by means of the choice of the hot-shaping temperature used and by the clamping effect of the tools.

Industrial Application Tubes with a flexible skirt of plastics material affording improved preservation the flavour or scent of the product contained therein, for example liquid, creamy or pasty. Tubes thus permitting easier and more complete distribution of the product. In particular in the industries of cosmetic, pharmaceutical, hygiene and foodstuff products 2and maintenance products.

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oo °eei [N:\LIBLLJ00489:JCC i I u I g Is~-r I 14 TABLE 1 Gains in weight of samples of skirts after impregnation for 4 weeks with a flavoured toothpaste Tube Thickness of the layers disposed Gain in weight on the internal face of the (mg/cm2) layer of EVOH A (reference) 45 pm 0.83 B (invention) 100 )Jm 0.12 C (invention) 135 um 0.59 TABLE 2 Maximum reaction of the tube skirts to depression in the pressing test (Figure 4) Tube Thickness of Total thickness Total thickness Max.

the skirt (jm) of HDPE (um) of HDPE reaction 2 x thickness (N) of EVOH (jim) A (reference) 290 105 145 6.6 B (invention) 345 125 165 8.7 C (invention) 340 84 124 4.2 *r V or or r o or o o or or

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Claims

1. A tube for the storage and dispensing of a product which is for example flavoured or scented and which contains water, comprising a dispensing head which is fixed on a flexible multi-layer skirt, said skirt essentially comprising an intermediate polymeric layer with a barrier effect relative to oxygen and flavouring or scents, said layer being sensitive to moisture, and on each face of said intermediate layer one or more polymeric layers based on polyolefins, characterised in that: a) the surface layers are of low density polyethylene (LDPE); b) a first layer of high density polyethylene (HDPE) is inserted between an internal layer of low density polyethylene (LDPE) and a first intermediate layer of LDPE which is disposed inside the intermediate barrier-effect layer and/or a second layer of high density polyethylene (HDPE) is inserted between an internal layer of low density polyethylene (LDPE) and a second intermediate layer of low density polyethylene (LDPE) which is disposed outside the intermediate barrier-effect layer; c) the assembly of the layers which are located on the internal face of said intermediate barrier-effect layer is of a total thickness of between 55 and 140 micrometres, so as better to preserve the flavouring or the scent of a product which is or may be contained therein.

2. A tube according to claim 1 wherein said polymeric layers based on polyolefins consist of an internal surface layer of low density or linear low density polyethylene, of a specific mass of between 0.86 and 0.93 g/cm3, and other layers which are respectively either of low density polyethylene (LDPE) of a specific mass of between 0.90 and 0.93 g/cm3 or high density polyethylene (HDPE) of a specific mass of between 0.935 and 0.97 g/cm3. i 25

3. A tube according to claim 1 wherein the total thicknesses of the layers of high density polyethylene is at least equal to 0o micrometers.

4. A tube according to claim 3 wherein said sum of the thicknesses of the layers of HDPE is between 100 and 140 micrometres, the thickness of said skirt being between 260 and 380 micrometres.

5. A tube according to claim 3 wherein the sum of twice the thickness of said barrier layer and the total thicknesses of the layers of high density polyethylene is between 130 and 180 micrometres, the thickness of said skirt being between 260 and 380 micrometres.

6. A tube according 1o claim 1 wherein said first layer of high density polyethylene (HDPE) and/or said second layer of HDPE is or are in a condition of continuity of fusion with said layers of low density polyethylene (LDPE) between which it or they is or are inserted.

7. A tube according to claim 1 wherein said first and second intermediate i- fc layers of low density polyethylene (LDPE) are each joined to a face of said [N:\LIBLL00489:JCC I I L I 16 intermediate barrier-effect layer by a bonding layer of a copolymer of ethylene and acrylic acid (EAA) or of a copolymer of ethylene and metacrylic acid (EMA).

8. A tube according to claim 1 wherein said intermediate barrier-effect layer of the skirt is of one of the materials of the group formed by: copolymers of ethylene and vinyl alcohol (EVOH), copolymers of ethylene and polyvinyl alcohol (PVOH), polyamides and modified polyamides PA, and is of a thickness of between 0.01 and 0.05 mm.

9. A tube according to any one of the preceding claims wherein said distribution head comprises a neck of smaller diameter than the skirt and an annular shoulder connecting the neck to the skirt, said shoulder being of a thickness of between 0.9 times and 1.35 times the thickness of the skirt and affording continuity of structure with said skirt and comprising folds which are squashed and welded to each other, said shoulder being squashable laterally.

A tube according to claim 9 wherein the folds of said shoulder which are squashed and welded together contain folded and squashed prolongations of said intermediate barrier-effect layer of the skirt.

11. A tube for the storage and dispensing of a product which is for example flavoured or scented and which contains water, substantially as herein before described with reference to any of Figures 2, 3, 7, 8, 9 or Dated 26 July, 1996 Cebal SA Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 4. IN:\LIBLL00489:JCC 134111k4 ~CT' -1