FR2560155A1 - Composite seal for the packaging of products sensitive to humidity and manufacturing method - Google Patents

Abstract

The invention relates to a composite seal used for stopping and for reclosing containers containing a product sensitive to humidity. The composite seal 8 of the invention comprises a fluidtight cover constituted by a combination 5 of decorated and/or printed aluminium 6 + paper 7, whose paper surface must be stuck to the end 13 of the neck 11, and a seal 1 at the base of the cap made of expanded polyethylene in three layers with, between the decorated aluminium 6 and the seal 1 made of expanded polyethylene in three layers, a double-sided self-adhesive polyethylene film 4. The manufacturing method of the composite seal 8 comprises a separation by simple peeling of the cutting skeleton of the seals 1 made of expanded polyethylene, and the recycling of this crushed skeleton in the extrusion load giving the internal layer 3 of the seals 1. The composite seal of the invention may be used to advantage for sealing and reclosing a container containing any product sensitive to humidity.

Description

COMPOSITE JOINT FOR PACKAGING PRODUCTS
SENSITIVE TO HUMIDITY AND PROCESS OF MANUFACTURE
The technical field to which the present invention relates is that of seals associated with devices for capping containers.

PRESENTATION OF THE PRIOR LDART AND ITS DISADVANTAGES
The packaging of a bumble-tolerant product, such as freeze-dried soluble coffee, in a jar-like container, jar or bottle, frequently uses a composite seal comprising a sealed seal adhered to the upper edge or drinking from the neck of the container. container and a seal remaining at the bottom of the closure cap screwed or snapped on the first opening of this capsule by the consumer.For the purposes of the manufacture of the composite seal and packaging, the two previous constituent parts are secured by a means of temporary adhesion; this adhesion being for example made on the motherboard before the cutting of the composite joints. It is thus known to use composite gaskets whose "capsule bottom seal" portion is constituted by corrugated cardboard covered with smooth kraft paperboard and whose "sealed seal" portion is constituted by a complex aluminum foil decorated with foil. composite seal is placed at the bottom of the closure cap where it is retained by pins or ribs, and after filling of the container, for example a glass jar, the capsule is screwed or snapped onto the neck whose rim is coated with glue . The aluminum film Xpapier is then tightened on the upper edge of the neck and is firmly bonded to it by its underside "paper", then constituting a sealed seal that allows the good preservation of the product contained until consumption.

The temporary adhesion of the aluminum / paper and capsule bottom cardboard gasket is made using a microcrystalline wax so that the cardboard seal separates easily from the foil / bonded foil seal on the neck when opening the capsule.

To consume, the user usually cuts the aluminum / paper seal by tearing and tearing or by cutting along the contour of the mouth of the neck. Consumption of the product is often spread over several weeks or months, it includes a number of intermediate quenching and storage periods in the plugged state of up to several months. These plugs are not waterproof because, on the one hand, there are irregularly fragments of aluminum / paper on the upper edge or drinking neck, on the other hand, the cardboard seal remained at the bottom of the capsule has practically more elasticity, the corrugated cardboard having been more or less crushed during the initial capping.

The moisture uptake of the product then aids degradations, up to a clogged or sweetened state of the product instead of the granular starting state, making this product unfit for consumption. These resumptions of moisture of the product then result not only the opening times of the container, but also and often predominantly the lack of sealing plugs.

PRESENTATION OF THE PROBLEM
The Applicant has sought to develop a splitting composite joint like the seal of the prior art in a sealed seal on the neck of the container when performing the packaging and in a capsule bottom seal, said bottom seal of capsule giving an improved seal when filling the container. The applicant has at the same time sought to develop a composite seal and a method of manufacturing this seal, for which the material cost is lowered.

SUMMARY OF THE INVENTION
The composite gasket of the invention comprises, as in the prior art, a tight seal composed of a decorated and / or printed aluminum / paper complex, the paper face being to be adhered to the rim of the neck and thus constituting an outer surface of the composite seal, and in a new manner a three-layer expanded polyethylene capsule bottom seal and a temporary adhesive means consisting of a double-sided self-adhesive polyethylene film, this double-sided self-adhesive film being placed between the three-layer polyethylene or "bottom seal" of capsule "and decorated aluminum.

An important advantage of the choice of the three materials is that the double-sided self-adhesive polyethylene film adheres less on the three-layer expanded polyethylene than on the decorated side of the aluminum. The adhesion is sufficient so that the components thus bonded remain attached during the cutting of the seals, their handling and their installation at the bottom of the capsules. But when a peel or separation force is exerted on the expanded polyethylene, it separates easily, the double-sided polyethylene film remaining then adhering to the decorated aluminum.

This feature makes it possible to separate by peeling and to recycle the expanded polyethylene cutting skins, exclusively in the charge giving rise to the inner layer of this expanded polyethylene containing gaseous bubbles, the external faces in contact with the food product or the bottom of the capsule being made of virgin polyethylene.

The three-layer expanded polyethylene capsule bottom seal is insensitive to moisture and has good compressibility as well as good elastic recovery. The tests have shown that in the case of freeze-dried soluble coffee pots, even if the upper edge of the neck has fragments of complex aluminum / paper irregularly torn off, such a compressible and elastic seal in a durable way can greatly reduce the recoveries of storage humidity.

The invention also relates to the method of manufacturing composite seals, wherein the three-layer expanded polyethylene cutting skeleton is peeled off from the decorated aluminum complex skeleton / paper covered with self-adhesive polyethylene film, then crushed and recycled into the barge. This crushing and recycling can concern both the drop-offs of the three-layer expanded polyethylene strip and the skeletons are thus cut off by peeling.
DRAWINGS AND COMPLEMENTARY EXPLANATIONS
The peculiarities of the structure and method of manufacture of the composite gasket of the invention will be described in detail with reference, where appropriate, to Jessins. Identical landmarks are used for parts or components; having the same function.

Figure 1 schematically shows a three-layer expanded polyethylene seal, or capsule bottom seal, in cross-section.

Figure 2 schematically shows the composite joint of the invention, in cross section.

Figure 3 shows the capsule provided with the composite gasket of the invention above the neck of the closure container, neck whose rim was glued, in axial section.

FIG. 4 represents the capsule of the previous figure tightened by screwing on the neck of the container, in axial section.

Figure 5 shows the capsule being opened, the container being still closed by the sealed seal, in axial section.

Figure 6 shows the neck of the container after cutting the opes cule sealed by the consumer, in axial section.

Figure 7 shows the collapsed container, in axial section.

Figure 8 schematically shows the separation of the three-layer expanded polyethylene backbone by peeling, after cutting the composite seals, for recycling.

The three-layer expanded polyethylene gasket (1) consists of two outer layers (2) and (2 ') of virgin polyethylene each representing on average 5 to 10% of the thickness and an inner layer (3) representing average 80 to 90% of the screener and containing gas bubbles (Figure 1). This seal is manufactured according to the process of the company TRI-SEAL
International Inc, of New York. The manufacture of the joint begins with a coextrusion with a special die, the two outer layers (2) and (2 ') based on virgin polyethylene coating the thicker inner layer (3) obtained from polyethylene added with a blowing agent such as azodicarbamide, which dissociates at the temperature of the extrusion (typically 200 to 2200 C), giving bubbles of nitrogen and carbon dioxide. The extruded strip is, almost immediately after extrusion, calendered between water-cooled rollers, then cooled by immersion in water and dried for example by blowing air before being made to width. The franking of the banks makes it possible to eliminate the lateral parts of the extruded strip, which are more heterogeneous. The product obtained and the joints cut therein are referred to hereinafter as the "three-layer expanded polyethylene", but the three layers. transformed by the extrusion are melted together and there is only a greater density of bubbles to mid-thickness and the total absence of bubbles in the immediate vicinity of the outer faces. The gaseous bubbles are contained in sealed micro-cavities and give the product its compressibility and good elasticity, while the absence of bubbles towards the outside joined to the frosting of the external faces (2) and (2v) by the calendering contribute to the cleanliness of the three-layer expanded polyethylene gasket and its insensitivity to moisture.

In the diagram of Figure 2, we can see below the expanded polyethylene gasket three layers (1) and-its underside (2 '> double-sided adhesive polyethylene film (43 and the complex alusinium / paper (5) composed of a decorated and / or printed aluminum foil (6), the decorations and prints being on top and in contact with the double-sided self-adhesive polyethylene film (4), and a sheet of paper (7) laminated to the aluminum foil (6), all constituting the composite seal (8).

In Figure 3, we see the composite seal (8) placed at the bottom of the capping cap (9), forcing slightly to pass the lugs or ribs such as (10) holding the composite seal in this position. The capsule (9) is presented above the neck (11D of the container (12) which contains the moisture-sensitive product, the upper or drinking edge (13) of this neck (11) having been coated with glue (16). >, for example a food glue in the case of a food product
FIG. 4 shows the capsule (9) tightened by screwing on the neck (11), the paper (7) which constitutes the lower face of the aluminum / paper complex (5) being thus tight and glued on the "drinking" or end (13) of the neck (11) .The aluminum / paper complex (5) then forms a tight seal for the preservation of the packaged product.

When subsequently the capsule (9) is unscrewed (Figure 5), the double-sided adhesive polyethylene film (4); remains adhered to the decorated and / or printed aluminum (6) constituting the top of the complex (5) forming the seal, and the three-layer expanded polyethylene seal (1) has separated from the self-adhesive polyethylene film (4) ) and remained at the bottom of the capsule. The peripheral part of the sealed complex or operculum (5) is easily crossed by the lugs or retaining ribs (10), this peripheral part projecting from the rim (13) being thin and flexible.

The consumer, after having unscrewed the closure cap <9), cuts the complex (5) often invisible covered double-sided polyethylene film (4), for example by piercing and cutting with a knife inside of the mouth of the neck <11).

This cutting is optionally completed by the tearing of fragments of the lid (5) + (4), and it remains for example in certain places, such as (15), (Figure 6), a little glue (16) and paper (7), and at other locations such as (17), operculum fragments (5) + (4). The opening by the consumer has thus caused unevenness above the upper edge or drinking (13) of the neck (11).

we:
FIG. 7 represents the filling arrangement of the container of FIG. 6 by screwing the capsule (9) to the bottom, at the bottom of which remained the three-layer expanded polyethylene gasket (1), on its neck (11). . Thanks to its compressibility and its good elastic recovery, the joint.

(1) applies with tightening all around the rim (13) of the neck (11), fitting the operculum fragments such as (5) + (4). Much better sealing tightness than in the case of the seal of the prior art, the bottom seal is constituted by corrugated cardboard covered with smooth kraft paperboard, is thus achieved.

FIG. 8 is a diagrammatic representation of the peel separation of the expanded polyethylene cutting backbone (18) of the decorated and / or printed aluminum complex (5) skeleton (19) + paper coated with double-sided self-adhesive polyethylene film (4) .

This separation by peeling is done after the cutting of the joints, the steps of the manufacturing process of the composite seal being successively:
a) extruding the three-layer expanded polyethylene gasket (1) followed by calendering, cooling with water and drying, according to the known method described above.

 (b) the franking or shelling of the banks, for setting the width of the strip. This fall reduces for example the width of an extruded strip 1 mm thick from 145 mm to 125 mm, it generally reduces the width of 10 to 20%.

 c) depositing on the expanded polyethylene strip three layers (1) of a strip of double-sided self-adhesive polyethylene film (4), and over this film (4), an aluminum complex strip (5) decorated and / or printed + paper. This removal can be done simultaneously for the film (4) and the complex (5), the film <4) and the complex (5) are both applied to the good polyethylene expanded three layers (1) by the same pressure roller, or can be done successively.

 d) cutting the composite anoints, in the composite strip obtained in the preceding step by known means, which gives composite seals (8) according to lnvntion and a composite cutting skeleton (19).

The three-layer expanded polyethylene cutting skeleton (18) is easily separated from the skeleton (20) of the self-adhesive film (4) and the aluminum / paper complex (5) by virtue of the adhesion of the double-sided self-adhesive polyethylene film (4). ) on the decorated and / or printed surface of the aluminum (6), adhesion much better than the adhesion of the same film (4) on the polyethylene foamed three layers (1 18).

This three-layer expanded polyethylene cutting skeleton (18) is most often 0 to 30% of the expanded polyethylene strip set to width (1), and all of the bankstops and skeletons (18) thus recovered represent typically 20 to 40% of the extruded amount
The skeletons (18) and optionally the three-layer expanded polyethylene scrap are crushed and recycled only in the polyethylene fillers added with a pore-forming agent giving the inner layer (3) of the extruded three-layer expanded polyethylene (1). The rate of this recycling is limited at any time to 50% in order to maintain a sufficiently constant level of quality in the extruded joint (1), and in practice the optimization of the material balance leads to a recycling rate that can vary between 2 @ and 50%.

Typically, the composite gasket of the invention will have the shape of a substantially circular disk with a total thickness of between 0.5 mm and 3.1 mm.

The three-layer expanded polyethylene bottom gasket (1) will have a thickness of between 0.5 mm and 3 mm, while the complex (5) decorated aluminum and / or printed (6) + paper (7) will have a thickness of between 0.025 mm and 0.06 mm and the double-sided self-adhesive film (4) will preferably be of linear polyethylene and with a thickness of between 0.01 mm and 0.025 mm.

The complex (5) aluminum decorated ettou printed + paper will typically be formed of decorated and / or printed aluminum (6) 0.01 mm to 0.03 mm thick and paper (7) thickness 0.015 mm to 0 , 03 mm.

The composite seal (8) of the invention is particularly suitable for cropping and filling receptacles of orifice diameter (14) of the neck (11) between 30 mm and 100 mm. Such containers may be of any moldable or conformable material, for example glass, plastic or metal, while the closure cap (9) associated with them is plastic or metal.

EXCESS COMPOSITE JOINT ACCORDING TO THE INVENTION AND TESTS OF E2ANCHEITZ
REBUCHING
This composite gasket (8) according to the invention is in the form of a circular disk having a diameter of 78 mm and is composed of - a three-layer expanded polyethylene disk (or bottom gasket).
capsule, 1 mm thick, - double-sided self-adhesive linear polyethylene film disc
(4), thickness 0.015 mm, - complex disc (5) aluminum decorated and / or printed (6) + paper
(7), with a total thickness of 0.04 mm (0.02 mm of aluminum and 0.02 mm of
pier).

The double-sided self-adhesive linear polyethylene, whose adhesive agent is in the mass, is of the "Lotex FW1299" type from CdF Chimie (France).

Seven seals (8) of this type were placed at the bottom of plastic screw caps (9) associated with glass jars of 750 g of lyophilized soluble coffee. The bottom of the capsules q9) has a diameter of 79 mm while their internal diameter on ribs (10) of the seal retainer is 77 mm. The diameter of the orifice of the neck (11) or the rim (13) is 76.5 mm. These dimensions can be compared with the indications given in FIGS. 3 and 5: the composite seal (S) slightly forces the passage ribs (10) which retain it thereafter, and the ribs (10) will not interfere with the separation of the capsule bottom seal (1) from the double-sided adhesive polyethylene film (4) adhering to the d-side aluminum decorated and printed (6) of the sealed lid (53 bonded to the rim (13) of the neck (11) of the container (12).

Comparatively, six composite joints of the prior art (corrugated cardboard + smooth cardboard secured to the same aluminiup / paper complex by a microcrystalline wax) were placed in capping capsules g9) identical to the previous ones.

The drinkers (13) of the necks (11) of the 7 + 6 = 13 pots were paraffin-coated, then the pots were filled with freeze-dried soluble coffee carefully extracted from its original packaging.

The pots were then closed by screwing the capsules the paper face of the composite gasket present at the bottom of each capsule t9) then sealingly adhering to the rim (13) of the corresponding neck (11). On the following day, the capsules were unscrewed and the lids were internally cut with a knife, removing the operculum fragments by tearing off according to current practice. Care was taken and it was verified that the fragments (4) + (5) present on the drinkers (13) of the necks (11) of the different pots created substantially comparable irregularities. The net weight of freeze-dried soluble coffee present in each pot was determined with precision, ranging from 689 g to 697 g for all 13 pots.

Each jar filled with freeze-dried soluble coffee was then capped by screwing down its capsule (9), and the jars were incubated at 90% humidity at 40 ° C for four weeks. This stay in an oven was interrupted for weighing every two to three days.

The following effects have been noted
1) on all pots, weight drop of 0.5 g - 0.1 g during the first week,
2) then, weight recovery, attributable to the absorption of moisture by freeze-dried soluble coffee, much more marked for the composite joints of the prior art than for the composite seals according to the invention,
composite seals of the prior art: individual weight recoveries of 1.0 - 0.7 - 0.9 - 1.1 - 0.5 - 1.0 g, an average of 0.9 g,
composite seals according to the invention: individual weight recoveries of 0.1 - 0.5 - 0.1 - 0 - 0 - 0 - 0.5 g, an average of 0.2 g.

 It goes without saying that, although done with care, this comparison is not perfect. It goes without saying that, in the case where the cutting of the cap and the removal of its troublesome fragments are made so as not to leave a drop on the rim (13) of the neck (11), the composite seal (8) of the invention makes it possible to reproducibly lead to sealing tightness to moisture, thanks to the characteristics and the surface condition of its three-layer expanded polyethylene capsule bottom gasket (1).

The composite gasket of the invention can be used with advantage for sealing and filling containers containing any moisture-sensitive product, in particular powdered food products or granules, but also for other hydrophilic products such as certain cleaning products.

Claims (4)

10 / Composite seal (8) for packaging of moisture-sensitive products, comprising a sealed seal (5) to be adhered to the neck of a container and a seal (1: capsule bottom, said seal (5) and said seal (1) being secured by temporary adhesive means, characterized in that the sealed seal consists of a complex (5) decorated aluminum and printed or printed (6) + paper (7), whose face paper must be glued to the rim (13) of the neck (11), in that the capsule bottom seal (1) is made of three-layer expanded polyethylene, and in that the temporary adhesive medium placed between the decorated aluminum ( 6) and the three-layer expanded polyethylene gasket (1) consists of a double-sided self-adhesive polyethylene film (4). 20 / Composite seal (8) according to claim 1, characterized in that it has the shape of a substantially circular disk with a total thickness of between 0.5 and 3.1 mm. 30 / composite seal (83 according to claim 1 or 2, characterized in that the complex (5) aluminum decorated and / or printed (6) + paper (7) has a thickness of 0.025 mm to 0.06 mm, in that the three-layer expanded polyethylene capsule bottom gasket (1) has a thickness of 0.5 to 0.3 mm, and in that the double-sided adhesive film (4) is made of linear polyethylene having a thickness of between 0.01 awn and 0.025 mm. 4 / A process for manufacturing a composite seal for packaging products sensitive to moisture, comprising the following steps:  a) a three-layer expanded polyethylene gasket strip (1) is manufactured by coextrusic, l, the two outer layers (2) and l22) being based on virgin polyethylene and the thicker inner layer (3) being polyethylene base added with a blowing agent, then by calendering, cooling to the east and drying.  (b) we put out. Said polyethylene strip expanded three layers (1) by shearing edges.  c) depositing on said expanded polyethylene strip three layers (1) of the double-sided self-adhesive polyethylene film (4), and over this film, the complex (5) decorated aluminum and printed or printed (6) + paper (7).  d) the composite joints (8) and a composite cutting skeleton (19) are further cut to form the composite joints (19), characterized in that, on the one hand, the composite cutting skeleton (19) is made on the one hand. peeling separation of the three-layer expanded polyethylene cutting skeleton (18) and the decorated and / or printed aluminum complex skeleton (20) 46) + paper (7) coated with double-sided self-adhesive polyethylene film (4), and on the other hand, said three-layer expanded polyethylene cutting skeleton 118) and, if appropriate, the edge drops of the strip (1) are crushed and recycled to the polyethylene filler (s) added with a pyrogenic agent giving the layer internal assembly (3) in the manufacture of the special die coextrusion joint according to said process step a) 50 / A method according to claim 4, characterized in that the recycled polyethylene, consisting of skeleton three-layered expanded polyethylene cuttings and possibly crushed shreds, represents 20 to 50% of the polyethylene feed (s) added with a pore-forming agent giving the inner layer (3) of the three-layer polyethylene (1)