FR2824496A1 - METHOD OF MANUFACTURING A DEVICE CAPABLE OF MODIFYING THE GAS ATMOSPHERE IN A HERMETIC OR CONTROLLED PERMEABILITY ENCLOSURE - Google Patents

Abstract

Method for manufacturing a device capable of modifying the gaseous atmosphere prevailing in a hermetic enclosure or with controlled permeability following the absorption or release of a target gas, device containing a reactive powder trapped in an at least partially permeable envelope to the target gas so as to allow gaseous exchanges, method characterized by the succession of the following steps:- the reactive powder is mixed with a more or less viscous fatty or volatile vector liquid so as to obtain a suspension (3, 13, 23) slightly or not reactive, - the slightly or not reactive suspension (3, 13, 23) is applied to a base film (41, 141, 241), - a covering film (42, 142, 242) is glued onto the base film (41, 141, 241) thus coated so as to obtain a complex (1, 11, 21) in which the slightly or not reactive suspension (3, 13, 23) is sandwiched between the base film ( 41, 141, 241) and the covering film (42, 142, 242), and- we eliminate e at least a significant proportion of the vector fluid by evaporation or by migration and absorption in one or both films constituting the complex (1, 11, 21) so as to restore the powder's reactivity.

Description

hydrodearomatization, and selective or total hydrogenations or

  The present invention relates to a method for manufacturing a device capable of modifying the gaseous atmosphere prevailing in an airtight enclosure or with controlled permeability following absorption or

release of a target gas.

  s Such a device can, for example, make it possible to increase the shelf life of industrial prepared meals condi

  packaged in essentially gas-tight packaging.

  In recent decades, we have observed a radical change in the eating habits of people in industrialized countries, mainly due to the growing number of women working outside and having only a limited time to devote to preparation.

meals.

  To take this situation into account, manufacturers have recently developed a wide range of ready meals packaged in packaging (bags or trays) more or less gas tight

  and presented to the "fresh" department of large surfaces.

  These prepared dishes can be of a very varied type: cooked dishes based on meat, fish or lemmes, cold cuts or cold meats such as quiches or pizzas, or appetizers or sweet pastry dishes The main obstacle to conservation of these substances is linked to changes in the internal atmosphere of the packaging occurring over time: absorption / desorption of oxygen, carbon dioxide, water vapor, desorption of ethylene As an example , it is common for the internal atmosphere of a package to have a non-negligible oxygen content which may be present from the outset or have entered it as a result of its residual permeability; a given amount of oxygen can also be included or

  dissolved in the packaged food (fatty phase, wet phase).

  However, it is well known that oxygen promotes the development of aerobic microorganisms or the appearance of molds and therefore leads to a dogradation of the product which in the long term becomes impro

ready for consumption.

  Oxygen also intervenes through its oxidizing properties which can lead to discoloration or browning of the foodstuffs as well as the reduction of their organoloptic qualities and their nutritional value. Given this situation, we had the idea of installing active devices in the packaging capable of blocking the gases that are present, or generated in them by a chemical or biological process during storage or even to generate "in situ"

  s gases likely to improve the conservation of packaged products.

  Among these active devices, one can by way of example men-

  oxygen absorbers, carbon dioxide absorbers, carbon dioxide generators, sulfur dioxide generators, ethylene absorbers, generators of stabilizers o (antioxidants, bactericides, metal ions. ..), generators

  ethanol, water retentants ...

  Such devices which have the function of modifying

  the gaseous atmosphere prevailing in a hermetic or permeable enclosure

  Controlled playability following absorption or release of a target gas s generally contain a reactive powder known per se trapped in an envelope at least partially permeable to

  target gas to allow gas exchange.

  More specifically, devices of this type have primitive-

  have been presented in the form of individual sachets consisting of

  a porous or permeable envelope to the target gas containing the powder

active.

  Such sachets can be widely assimilated to sa-

  classic sugar or tea chips and are most often made in

  special papers (non-woven fabrics, multi-layer complex, ...).

  2s These sachets have the advantage of being able to contain relatively large quantities of reactive powder and of allowing gas exchanges and very rapid reactions: their presence therefore makes it possible to significantly improve the shelf life of dishes prepared in industry. o However, their introduction and their placement in packaging at the high rates required by the manufacturers entail

serious difficulties.

  In addition, the presence of these sachets in packaging can lead to serious misunderstandings by consumers when they are opened: these sachets are not really assimilated to packaging and can sometimes be confused with other sachets, in particular containing salt or spices (for example in the case of piz zas). To overcome these drawbacks, specialists have had the idea of presenting such devices capable of modifying the gaseous atmosphere prevailing in the packages in which foodstuffs are packaged in the form of adhesive labels which are much better similar to packaging since they are stuck to it: such labels,

  whose volume is necessarily reduced and which therefore cannot contain-

  sea that small quantities of reactive powder on their internal part, are however distinguished by a capacity and a speed of absorption or

  very low release, detrimental to a large extent to their effectiveness.

  To remedy the drawbacks of the above-mentioned sachets, specialists have also already proposed active films capable of absorbing or releasing a target gas in which the reactive powder is directly incorporated in a plastic polymer or between two plastic films. However, such active films also exhibit only limited performance in terms of reaction speed and capacity for action since they contain only small amounts of reactive powder.

  tive and that it is incorporated directly into a polymer.

  For example, an oxygen-absorbing sachet has an average capacity of 100 to 1,000 ml per day at 6/8 C for 0.25 to 0.7 dm2 while a label only has a capacity from 5 to 10 ml per day at 6/8 C for 0.06 dm2 and a film with a capacity of 1 to 5 ml per

day and per dm2 always at 6/8 C.

  Another drawback of all these devices capable of modifying the gaseous atmosphere prevailing in hermetic enclosures or with controlled permeability is linked to the fact that their manufacture requires the handling of reactive powders which is always inconvenient and results in an industrial calf number of problems related to the external volatility of the particles of these powders which are extremely fine, which constitutes

a major handicap.

  The object of the present invention is to remedy these drawbacks by proposing a method making it possible to manufacture, in a simple and automated manner, an active device of the above-mentioned type which can be in direct contact with wet or fatty foods, without danger for consumers and which is distinguished. by a much higher efficiency than 3 s that of the adhesive labels and active films currently on the market. To this end, the invention relates to a process characterized by the succession of the following steps: - the reactive powder is mixed with a more or less viscous fatty or volatile carrier liquid so as to obtain a suspension which is not very reactive or not, - the little or no reactive suspension on a base film,

  s - a covering film is glued onto the base film thus coated in

  to obtain a complex in which the suspension has little or no reaction

  tive is sandwiched between the base film and the covering film, and - at least a significant proportion of the carrier fluid is eliminated by evaporation or by migration and absorption in one or both films

  constitutive of the complex so as to restore the reactivity of the powder.

  It should be noted that the application of the suspension with little or no reactivity on the base film can be partial or total and in particular be carried out according to a predetermined geometry; we can indeed have to position reactive areas in certain places and not

  others without departing from the scope of the invention.

  According to the invention the base film and the covering film are advantageously constituted by two films of absorbent material

paper or cardboard type.

  The essential feature of the process according to the invention is linked to the application of the reactive powder in the form of a suspension which may have a consistency similar to that of an ink, a paint, an adhesive or a '' a putty, thanks to its mixture with

a fatty or volatile carrier liquid.

  s According to the invention, it has been established that this suspension must as a rule contain in weight proportion more than 50% of reactive powder and preferably approximately 2/3 of reactive powder and approximately 1/3

  of carrier liquid so that its viscosity is of the order of 100 poises.

  Such a suspension which is little or not reactive can indeed be pumped, transferred to a non-powdery state and applied very easily to the base film in particular by a printing technique such as, for example, screen printing; this makes it possible to largely simplify the manufacturing of the device, while guaranteeing

  a uniform distribution of a large quantity of reactive powder.

  3s Of course, after applying the suspension to the base film, it is necessary to at least partially remove the liquid with

  so as to restore the reactivity of the powder.

  This elimination can, depending on the nature of the carrier liquid, be consecutive to its evaporation or to its migration and absorption.

  in at least one of the two constituent films of the complex.

  After evaporation the bead of adhesive allowing solidari

  s the base film and the cover film can surround the powder

  active so as to avoid leaks.

  According to the invention, at least one of the two constituent films

  of the complex is preferably made of a permeable or po-

  rous vis-à-vis the target gas to be absorbed or released, this in order to guarantee an easy transit of this gas and therefore good gas exchange efficiency. Thus according to the invention, the reactive product is. like an ink or paint or glue or mastic, not very reactive before use because it is presented in a creamy or pasty liquid phase (as a result of the isolation and coating of the reactive solid particles included in

  this liquid mass) but is liable in use to solidify by eli-

  mination of the fluid vector, by evaporation or migration and absorption

  in one or other of the constituent films of the support complex, allows

  so much to the residual solid elements, rid of the gangue of the fluid vector, to constitute a porous particulate semi-solid assembly

  accessible to gas exchanges throughout the structure.

  According to a first variant of the invention, the above process

  mentioned leads to the production of an active "layered" device formed by the superposition of several essentially flat layers or films and 2s which can simply be constituted by the complex itself, that is to say by a middle layer of suspension containing reactive powder

  sandwiched between a base film and a cover film.

  According to this variant, the active device pre-

  feels in the form of cut pieces which can have various shapes

  o (round, square, ...) in which the suspension containing the powder

  active is maintained by a peripheral bead of glue.

  However, in the general case in which the active device is intended to be introduced into packages containing foodstuffs, it is necessary to ensure that there is no direct contact between the reactive powder and these foods. , and that it cannot

  nor risk dissolving on or in food.

  To this end, and according to another characteristic of the invention, the complex is coated on at least one of its two faces with a film permeable to water and / or to fats forming a barrier such as example and without limitation a polymeric film or a mixed film

paper / polymer.

  When the complex is thus coated with an impermeable film on each of its two faces, the gas exchanges can only take place at the thickness of the device, through the bead of adhesive or the edge of the film. base and / or covering film constituting the complex. It was however possible to verify that such a gas transfer is sufficient

o in many cases.

  According to a second variant of the invention after obtaining it

  tion, the complex is passed between rolls of micro fluting or nano fluting and a waterproof film is glued on each of its faces. According to this variant, the device is in the form of composite pieces cut out of any shape having a geometry comparable to that of corrugated cardboard in which the

  complex is sandwiched between an upper film and a lower film.

  In accordance with this second variant, the two films im

  permeable (upper film and lower film) can also be

  titrated by a polymer film or by a mixed paper / polymer film.

  This second variant allows, thanks to the presence of micro-grooves or nano-grooves, gas exchanges which are markedly more intense between the reactive powder and the atmosphere of the packaging than in the case of the first variant since these exchanges can take place on the entire surface of the internal complex, without risk of

  direct contact with foodstuffs.

  According to a third variant of the invention, the suspension, which has little or no reactivity, is partially applied to a base film no.

  o made in an oil-absorbing cardboard using regular strips

  a lot of space and a covering film consisting of a fluted film and an upper bonded film is bonded to the base film thus coated, between the slightly reactive suspension strips or not at all

  directly on it so as to obtain a complex.

  s It should be noted that such an overlap film can be

  purchased directly from the store.

  In accordance with this variant, the base film of the complex can, if necessary, be coated with an impermeable film forming a barrier.

  having the function of stopping the migration of oil.

  This waterproof film can in particular be made of a plastic or aluminized material. I1 it should be noted that this third variant corresponds to a

  compromise between the first and the second variant.

  The invention also relates to a device capable of modifying the gaseous atmosphere prevailing in a hermetic enclosure or with controlled permeability following the absorption or release of a target gas and containing a reactive powder trapped in at least one envelope. partially permeable to the target gas so as to allow gas exchange, characterized in that it is obtained following the setting in _u

vre of the above process.

  i5 Such a device may, by way of nonlimiting example, be an oxygen absorbing device, in which case the reactive powder may advantageously be composed in a manner known per se of iron powder, of a dehydrating compound capable of absorb and store water vapor

and an electrolyte.

  In the case of such a reactive powder whose water is a catalyst, it is necessary that the carrier liquid is a non-aqueous liquid, the supply of water being carried out by absorption of the water vapor emitted by the product. to preserve, after closing the waterproof packaging

  in which it is packaged with the device according to the invention.

  According to another characteristic of the invention, the carrier liquid may advantageously consist of a non-drying fatty liquid such as glycerin, paraffin oil, rapeseed oil or a mixture of several non-drying oils which do not reacts only weakly or

  not at all with the reactive powder.

  The oxygen absorption reaction cannot take place within the suspension, and to restore the reactivity of the powder, it is necessary to remove the non-drying fatty liquid by migration and absorb

  tion in one of the constituent films of the complex.

  It should be noted that, without departing from the scope of 3s of the invention, it is also possible to use as carrier liquid, a volatile liquid such as an alcohol, in which case this liquid is not eliminated by migration and absorption in one of the constituent films of the complex,.

mas by evaporaton.

  The characteristics of the method and of the device which are the subject of the invention will be described in more detail with reference to the accompanying drawings in which: - Figure 1 is a sectional view of a device corresponding to the first variant of the invention, - the figure 2 is a sectional view of a device corresponding to the third variant of the invention, - Figure 3 is a sectional view of a device corresponding to the third

sth variant of the invention.

  o According to figures 1 and 2, the thickness of the device has been noted

  duly increased for the sake of clarity.

  According to figure 1, the device is a laminated piece constituted by a median complex 1 sandwiched between two im films.

  permeable, namely a lower film 2 and an upper film 22.

  is The complex 1 consists of a viscous suspension 3 of consistency similar to that of an ink of a glue of a paint or a mastic which is itself sandwiched between two porous films or permeable to a given target gas, i.e. base film 4 and film

recovery 42.

  The suspension 3, which has little or no reactivity with respect to the target gas, consists of a mixture of approximately 2/3 of a powder reactive with respect to the target gas and of approximately 1/3 of a fatty or volatile carrier liquid

inert towards this gas.

  The base film 4 is glued to the covering film 42 by 2s a peripheral bead of glue 5 which allows the suspension to be trapped

  3 to the internal part of the complex 1.

  The base film 4 and the covering film 42 are respectively bonded to the lower film 2 and to the upper film 22 by their external faces opposite to the emulsion 3 by means of a layer of adhesive 6, 62. After manufacture, the carrier liquid entering the composition of the suspension 3 is gradually eliminated either by evaporation or following its migration into porous or permeable films 4, 42 and its absorption by these films, so that the reactive powder regains its 3s reactivity . Given the configuration of this device, gas exchanges with the outside environment can only be carried out through the

  bead of adhesive 5 or of the edge of the porous or permeable films 4, 42.

  According to FIG. 2, the complex 11 has a configuration broadly similar to that shown in FIG. 1 and consists of a layer of a viscous suspension 13 formed by mixing a reactive powder and a fatty or volatile carrier liquid inert with respect to a given target gas; this layer 13 is sandwiched between two porous or permeable films vis-à-vis this target gas, namely a base film 14 on

  which the suspension 13 is applied and a covering film 142.

  These two films can in particular be all-wood films

  weighing for example 250 g / m2.

  o Suspension 13 is maintained in this complex thanks to

  a peripheral bead of glue 15.

  However, the complex 11 is not planar as in the configuration shown in FIG. 1, but equipped with micro-grooves or nano-grooves 10 consecutive to its passage between rollers

  micro flute or nano flute.

  According to FIG. 2, the complex 11 is also taken in sand wich between two films impermeable to grease, to gases and to moisture laminated, namely a lower film 12r and an upper film 122 to which it is glued by cords. glue 16, 162 located at the top of the

  micro grooves or nano grooves 10.

  Given this configuration, gas exchanges can be carried out over the entire surface of porous or permeable films

  14r, 142 between the waterproof films 12, 122.

  According to Figure 3, the base film 24 is made of cardboard

2s absorbing oil.

  Slightly or non-reactive suspension 23 is applied partially

  Lement on this base film 24 in regularly spaced bands.

  A covering film 242 is bonded to the base film 24 thus coated between the slightly or not reactive suspension strips 23

with beads of glue 26.

  The covering film 242 is formed by the association on the one hand of a fluted film 1242 and on the other hand of an upper film 124'2

  glued directly to it with beads of glue 262.

  The complex 21 is thus formed by the suspension little or

  3s not reactive 23 sandwiched between the two films 24, 242.

  According to FIG. 3, the base film 24 of the complex 21 is moreover coated with an impermeable barrier film 25 having for

  function of stopping the migration of oil.

  Not shown in the figure, an impermeable film

  similar to film 25 could also be glued to the film

cover 242.

  By way of example, such a device was manufactured, in accordance with the invention, using an oxygen-absorbing powder having the following composition by weight: - metakaolin 12% - iron powder 60% - activated carbon 3% o - 6% NaC1 - 3% moisture absorber - 16% acrylic-based moisture fixator It has been verified that such a powder makes it possible to absorb, after evaporation of part of the carrier liquid by evaporation or by i5 absorption in at least one of the two constituent films of the

  around 20 to 50 ml of oxygen per day per dm2.

Claims (8)

R E V E N D I C A T I O N S   1) Process for manufacturing a device capable of modifying the gaseous atmosphere prevailing in an airtight enclosure or with controlled permeability following the absorption or release of a target gas, device containing a reactive powder trapped in an envelope at least partially permeable to the target gas so as to allow gas exchanges, a process characterized by the succession of the following steps: - the reactive powder is mixed with a more or less viscous fatty or volatile carrier liquid so as to obtain a suspension (3 , 13, 23) o with little or no reactivity, - the suspension with little or no reactivity (3, 13, 23) is applied to a base film (4, 14, 24), - a covering film (42, 142, 242) on the base film (4, 14, 24) thus coated so as to obtain a complex (1, 11, 21) in which the suspension with little or no reactivity (3, 13, 23) is taken in sand wich between the base film (4, 14, 24) and the cover film (42, 14 2, 242), and - at least a significant proportion of the carrier fluid is eliminated by evaporation or by migration and absorption in one or both of the films constituting the complex (1, 11, 21) so as to return the powder its reactivity.  2) Method according to claim 1,., Characterized in that the suspension is applied with little or no reactivity on the base film (4,   14, 24) by a printing technique such as screen printing.   3) Method according to any one of claims 1 and 2,   characterized in that at least one of the constituent films of the complex (1, 11, 21) is made of a material which is permeable or porous with respect to the target gas to be absorbed or released.   4) Method according to any one of claims 1 to 3,   characterized in that the complex (1) is coated with an impermeable film forming a barrier (2, 22) on at least one of its faces.    ) Method according to any one of claims 1 to 3,   characterized in that the complex (11) is passed between rolls of micro-groove or nano-groove and an impermeable film (12, 122) is glued on each of its faces so as to obtain a composite sheet having a geometry similar to that of the corrugated cardboard in which the complex (11) is taken   sandwiched between an upper film (122) and a lower film (121).   6) Method according to any one of claims 1 to 3,   o characterized in that - the suspension, which has little or no reactivity (23), is partially applied to a base film (24) in particular made of cardboard absorbing the oil in regularly spaced strips, and - it is bonded to the base film (24) an assembly constituted by the association of a fluted film (1242) and an upper film (124'2) bonded   directly on the latter so as to obtain a complex (21).   7) Method according to claim 6,., Characterized in that the base film (24) of the complex (21) is coated with an impermeable film forming a barrier (25) having the function of stopping the migration of the 'oil   especially made of a plastic or aluminisce.   8) Method according to any one of claims 1 to 7,   characterized in that the slightly or not reactive suspension contains in proportion by weight more   50% reactive powder and preferably about 2/3 of reactive powder   tive and about 1/3 of carrier liquid and has a viscosity of the order of lOO poises.   9) Device capable of modifying the gaseous atmosphere prevailing in an airtight enclosure or with controlled permeability following the absorption or release of a target gas and containing a reactive powder trapped in an envelope at least partially permeable to the target gas of way to allow gas exchange, characterized in that it is obtained following the implementation of the method according to any one of claims 1 to 8.    ) An oxygen-absorbing device according to claim 9, characterized in that the carrier liquid is a non-drying fatty liquid such as fine paraf oil or glycerin or rapeseed oil or a mixture of several oils