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    • 专利摘要:
    1) Multilayer film comprising 2 thin layers D and E of a thermoplastic material bonded together by a continuous layer A consisting of a hot-melt self-adhesive composition comprising: - from 40 to 70% by weight of a composition of block copolymers styrenics consisting of a mixture of diblock and triblock copolymers; and - from 30 to 60% by weight of one or more tackifying resins; said multilayer film being such that the adhesive layer A is: - connected to layer D by means of a bonding layer B, and - connected to layer E by means of a bonding layer C, each 2 layers B and C being respectively constituted by a composition (b) and (c) each comprising: - a polyolefin (P) chosen from a polyethylene (PE) and a polypropylene (PP), optionally modified with an unsaturated carboxylic anhydride; and - at least one elastomeric compound (EL) chosen from a copolymer of ethylene and propylene (EL1) and a styrenic block copolymer (EL 2) comprising at least one elastomer block. 2) Method of manufacturing said film by co-extrusion 3) Use of said film for the production of reclosable packaging.
    公开号:FR3088239A1
    申请号:FR1871410
    申请日:2018-11-08
    公开日:2020-05-15
    发明作者:Romain Puchois；Christophe Robert
    申请人:Bostik SA；
    IPC主号:
    专利说明:

    DESCRIPTION
    TITLE: NEW MULTILAYER FILM FOR RECLOSABLE PACKAGING WITH IMPROVED RECLOSING
    The subject of the present invention is a multilayer film comprising a layer constituted by an extrudable hot-melt self-adhesive composition, a method of manufacturing said film, as well as its use for the manufacture of reclosable packaging (or trays), intended in particular for packaging. food, especially perishable food.
    Applications WO 02/064694, WO 12/045950, WO 12/045951 and WO 14/020243 are known from extrudable hot-melt self-adhesive compositions intended for use in the manufacture of reclosable packaging (or trays).
    Resealable packaging, for example in the form of trays or sachets, is used in the food industry and mass retailing to package perishable goods, especially fresh products. Such packaging is also described by patent EP 1053952.
    After a first opening of the packaging, and consumption of a part of the food product which it contains, the consumer can manually close the packaging in a substantially hermetic way and consequently ensure, if necessary after putting in the refrigerator, the conservation of the remaining portion of the product. A succession of reopenings and closings is also possible.
    These packages generally comprise a container (or receptacle) and a cover forming a lid, which are fixed to each other hermetically by welding.
    The receptacle, more or less deep and relatively rigid, consists of a multilayer sheet (also called complex or composite) having a minimum thickness of 200 μm, generally between 200 and 1000 μm. This sheet is thermoformed so as to have a flat bottom on which the food product rests and a periphery in the form of a flat strip. This periphery, generally parallel to the bottom, is linked by welding to the flexible and flat cover, which consists of a multilayer film (also qualified as complex or composite) with a thickness generally between 40 and 150 μm, and which is sometimes referred to as a seal film.
    When the package is opened, the sealing film is manually separated from the receptacle at the level of the flat band around the edge. This operation reveals an adhesive layer at the level of this flat strip, both on the seal strip and on the receptacle strip which were previously in contact. These 2 adhesive layers (continuous or discontinuous) "said girls" result from the rupture of an initial adhesive layer or "mother" or, possibly, from its separation (or separation) from one of the 2 layers of the complex multilayer film which are adjacent to it. The initial adhesive layer is therefore one of the layers of said multilayer complex film which is itself an element included either in the composite sheet which constitutes the receptacle or, preferably, in the sealing film.
    The 2 daughter adhesive layers which are present, after opening the packaging, on the strips located on the respective periphery of the receptacle and of the cover are therefore opposite one another. Thus, it suffices to reposition the cover on the receptacle, in accordance with their position in the packaging before opening, in order to bring the 2 strips of daughter adhesive layers back into contact. A simple manual pressure then allows the packaging to be closed.
    The adhesive composition which constitutes the mother and daughter adhesive layers is therefore necessarily a pressure-sensitive adhesive (also known as self-adhesive or PSA, from the English "Pressure Sensitive Adhesive").
    The extrudable self-adhesive compositions described in the abovementioned applications are hot-melt compositions comprising a tackifying resin and a styrenic block copolymer including an elastomer block. The hot-melt self-adhesive compositions are also commonly called HMPSA, corresponding to the initials of the English translation "Hot Melt Pressure Sensitive Adhesive". These are solid substances at room temperature which do not contain water or solvents. Applied in the molten state, they solidify upon cooling, thus forming an adhesive layer which ensures the connection between the 2 thin layers of thermoplastic polymeric material to be assembled, while offering the corresponding packaging the advantageous opening properties. and reclosing.
    Furthermore, these hot-melt self-adhesive compositions (or HMPSA), which are prepared by hot mixing of their ingredients, have the additional advantage of being able to be put in the form of granules (of size between 1 and 10 mm) by means of an extrusion step carried out directly hot after the mixing step, for example by means of a 2-screw extruder provided with a tool for cutting the extruded product.
    Thanks to the granules thus obtained, the three-layer film which consists of the layer of hot-melt self-adhesive composition and the 2 thin layers of thermoplastic polymeric material to be assembled, can be conveniently manufactured by co-extrusion, for example by feeding a blowing device. bubble by the constituent materials of the 3 layers in the form of granules of size defined previously.
    The ease of opening such packages is closely linked to the properties of PSA and more particularly to the force that must be applied, when opening the package (hereinafter called first opening), to obtain the rupture of the layer. mother adhesive and / or its separation from one of the 2 layers which are adjacent to it in the previously mentioned multilayer composite film.
    The ability of the packaging to close and the quality of the reclosure obtained (hereinafter referred to as the first reclosure) are also important in order to once again have a substantially hermetic packaging and therefore capable of ensuring the preservation of its content. The quality of the first reclosure is also closely linked to the properties of PSA. It is evaluated by the force which must be applied, upon re-opening (hereinafter referred to as the second opening), to again obtain the rupture and / or detachment of the adhesive layer which has been formed by the repositioning. 2 daughter adhesive layers, followed by manual pressure applied around the packaging.
    Patent application EP 1053952 teaches resealable packaging with a container which comprises a complexable layer, a layer of adhesive and a tear-off weldable layer. This adhesive is a self-adhesive which is described very generally.
    Application US2013 / 0029553 describes a multilayer film for reclosable packaging comprising a heat-sealable layer made of a specific amorphous PolyEthyleneTerephthalate, a layer of PSA, and at least one bonding layer made of a copolymer of ethylene and methyl acrylate .
    Application WO 12/045951 discloses a multilayer film comprising 2 thin layers of thermoplastic materials bonded together by a layer of an adhesive composition based on styrenic block copolymers, said layer having a thickness of between 7 and 300 μm. This multilayer film, which is suitable for the manufacture of reclosable packaging, makes it easier to open the latter, by lowering the force of first opening, while maintaining substantially at the same level the quality of the subsequent reclosing (or first reclosing).
    Application EP2946920 describes a multilayer film which comprises, in addition to the 2 thin layers D and E of a thermoplastic material and the layer of hot-melt self-adhesive composition A which secures them, 2 bonding layers B and C which are inserted between a firstly layer A and secondly, respectively, layers D and E, giving the resulting multilayer film a D / B / A / C / E structure. Said layers B and C consist of a composition based on a polyethylene (PE) or polypropylene (PP) modified with a cyclic anhydride of an unsaturated acid, such as maleic anhydride, and in particular a PE grafted with the maleic anhydride.
    Such a multilayer film advantageously makes it possible to improve the reclosing performance of the corresponding packaging, while maintaining a first easy opening. Increasing reclosure performance and in particular the quality of the first reclosure and assures the consumer that has proceeded to the era of opening the resealable package to consume a portion of the content, more effective conservation of the remaining portion of perishable food product.
    An object of the invention is to provide new bonding layers, resulting in a multilayer system suitable for the manufacture of reclosable packaging, which allow - while maintaining a first easy opening of the packaging - to improve the quality of its reclosing (or first reclosing), so as to ensure the consumer more efficiently the conservation of the remaining portion of the perishable food product.
    The invention also aims to increase the force of second opening, while maintaining the force of first opening at an acceptable level.
    Another object of the present invention is to provide a multilayer film enabling the above objects to be achieved at room temperature, corresponding to the temperature at which the consumer opens and recloses the packaging.
    Another object of the present invention is to provide a multilayer film capable of being manufactured by co-extrusion from raw materials packaged in the form of granules, in particular by co-extrusion by bubble blowing, with a view to the manufacture of '' resealable packaging.
    It has now been found that these aims can be obtained, in whole or in part, by means of the multilayer film according to the invention which is described below.
    The present invention therefore relates primarily to a multilayer film comprising 2 thin layers D and E of a thermoplastic material bonded together by a continuous layer A which has a thickness ranging from 7 to 50 μm, and is constituted by a composition hot-melt self-adhesive (a) comprising, on the basis of the total weight of said composition:
    - from 40 to 70% by weight of a composition (al) of styrenic block copolymers comprising at least one elastomer block, said composition (al) being formed, on the basis of its total weight:
    from 30 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and
    - from 10 to 70% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS;
    the content of total styrenic units in said composition (a1) varying from 10 to 40% by weight based on the total weight of (a1); and
    - from 30 to 60% by weight of one or more tackifying resins (a2);
    said multilayer film being further characterized in that the adhesive layer A is:
    - connected to layer D via a link layer B, and
    - connected to layer E via a bonding layer C;
    each of the 2 layers B and C being constituted respectively by a composition (b) and (c) each comprising:
    - a polyolefin (P) chosen from polyethylene (PE) and polypropylene (PP), optionally modified with an unsaturated carboxylic anhydride which is either a ring comprising 4 or 5 carbon atoms or a straight chain comprising 6 or 8 carbon atoms ; and
    - At least one elastomeric compound (EL) chosen from a copolymer of ethylene and propylene (hereinafter EL1) and a styrenic block copolymer (hereinafter EL2) comprising at least one elastomeric block.
    In addition to the percentages indicated above, all the percentages used generally in this text to designate the amounts of ingredients of a composition correspond, in the absence of contrary indication, to percentages expressed by weight on the basis the total weight of said composition.
    The characteristics of the layers A, B, C, D and E included in the multilayer film according to the invention are now described in more detail below.
    Description of the composition (a) constituting the adhesive layer A:
    Composition (al) of styrenic block copolymers comprising at least one elastomer block:
    The composition (al) of styrenic block copolymers comprising at least one elastomer block, which is included in the HMPS composition A (a) constituting the adhesive layer A is itself constituted, on the basis of its total weight:
    from 30 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and
    - from 10 to 70% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS.
    The styrenic block copolymers used have a weight-average molar mass Mw generally between 50 kDa and 500 kDa.
    These styrenic block copolymers are made up of blocks of different polymerized monomers including at least one polystyrene block, and are prepared by radiealaire polymerization techniques.
    Unless otherwise indicated, the weight average molecular weights M w which are given in the present text are expressed in dalton (Da) and are determined by gel permeation chromatography, the column being calibrated with polystyrene standards. .
    The triblock copolymers include 2 polystyrene blocks and an elastomer block. They can have various structures: linear, star (also called radial), trendy or even comb. Diblock copolymers include 1 polystyrene block and 1 elastomer block.
    The general formula for tri-block copolymers is:
    ΑΒΑ (I) in which:
    - A represents a non-elastomeric styrene (or polystyrene) block, and
    - B represents an elastomer block which can be:
    - polyisoprene. The block copolymer then has the structure: polystyrene-polyisoprene-polystyrene, and for denomination: SIS;
    - polyisoprene followed by a polybutadiene block. The block copolymer then has the structure: polystyrene-polyisoprene-polybutadiene-polystyrene, and for denomination: S IB S
    - polybutadiene. The block copolymer then has the structure: polystyrene-polybutadiene-polystyrene, and for denomination: SBS;
    - totally or partially hydrogenated polybutadiene. The block copolymer then has the structure: polystyrene-poly (ethylenebutylene) - polystyrene and for denomination: SEBS;
    - totally or partially hydrogenated polyisoprene. The block copolymer then has the structure: polystyrene-poly (ethylenepropylene) - polystyrene and for denomination: SEPS.
    The general formula for di-block copolymers is:
    A-B (II) in which A and B are as defined above.
    When the composition (a1) comprises several triblock styrenic copolymers, the latter being chosen from the group comprising SIS, SBS, SEPS, SIBS, SEBS, it is understood that said triblocks may belong to one or more of these 5 families of copolymers. It is the same, mutatis mutandis, for diblock copolymers.
    It is preferred to use a composition (a1) comprising a triblock copolymer and a diblock copolymer having the same elastomer block, due in particular to the fact that such mixtures are commercially available.
    According to a particularly preferred embodiment, the content of diblock copolymer in the composition (a1) can vary from 40 to 90%, preferably from 50 to 90%, even more preferably from 50 to 60%.
    According to a particularly advantageous embodiment of the composition (a) constituting the layer A included in the multilayer film according to the invention, the composition (al) consists of a triblock copolymer SIS and a diblock copolymer SI. In this case, the content of total styrenic units in composition (a1) preferably varies from 10 to 20%.
    The triblock copolymers included in composition (a1) preferably have a linear structure.
    The styrenic block copolymers with an elastomer block, in particular of the SI and SIS type, which can be used in composition (a) are commercially available, often in the form of triblock / diblock mixtures.
    Kraton® D1113BT from Kraton and Quintac® 3520 from Zeon Chemicals are examples of compositions al consisting of SIS and SI.
    Kraton® Dl 113BT is a composition with an overall styrenic unit content of 16%, which is made up of 45% of linear SIS triblock copolymer of M w around 250 kDa, and of 55% of diblock SI copolymer of M w about 100 kDa. Quintac® 3520 is a composition which consists respectively of 22% and 78% of linear SIS triblock (M w around 300 kDa) and SI diblock (M w around 130 kDa), and whose total content in motifs styrenics is 15%.
    Tackifying resins (a2):
    The HMPSA composition (a) constituting the layer A also comprises one or more tackifying resins (a2).
    The tackifying resin (s) (a2) which can be used have average molar masses by weight M w generally between 300 and 5000 Da and are chosen in particular from:
    - (i) rosins of natural or modified origin, such as for example rosin extracted from pine gum, wood rosin extracted from the roots of the tree and their hydrogenated, dehydrogenated, dimerized, polymerized or esterified derivatives monoalcohols or polyols such as glycerol;
    - (ii) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having about 5, 9 or 10 carbon atoms derived from petroleum fractions;
    - (iii) terpene resins generally resulting from the polymerization of terpene hydrocarbons such as, for example, mono-terpene (or pinene) in the presence of Friedel-Crafts catalysts, optionally modified by the action of phenols;
    - (iv) copolymers based on natural terpenes, for example styrene / terpene, alpha-methyl styrene / terpene and vinyl toluene / terpene.
    According to a preferred variant, the softening temperature (or point) of the tackifying resins which can be used in the composition according to the invention can vary from 5 to 140 ° C. The softening temperature is determined in accordance with the standardized test ASTM E 28, the principle of which is as follows. A brass ring with a diameter of approximately 2 cm is filled with the resin to be tested in the molten state. After cooling to room temperature, the ring and the solid resin are placed horizontally in a thermostated glycerin bath, the temperature of which can vary by 5 ° C. per minute. A steel ball with a diameter of about 9.5 mm is centered on the solid resin disc. The softening temperature is - during the temperature rise phase of the bath at a rate of 5 ° C per minute - the temperature at which the resin disc flows from a height of 25.4 mm under the weight of the ball.
    According to a preferred variant, aliphatic resins belonging to categories (ii) or (iii) are used for which examples of commercially available resin may be cited:
    (ii) Escorez® 1310 LC available from Exxon Chemicals which is a resin obtained by polymerization of a mixture of unsaturated aliphatic hydrocarbons having about 5 carbon atoms, and which has a softening temperature of 94 ° C. and a weight average molar mass Mw of about 1800 Da; Γ Escorez® 5400 also from the company Exxon Chemicals which is a resin obtained by polymerization, then hydrogenation of a mixture of unsaturated aliphatic hydrocarbons having approximately 9 or 10 carbon atoms and which has a softening temperature of 100 ° C. and a Mw of about 570 Da;
    (iii) Dercolyte® S115 available from the company “Resin and Terpene Derivatives or DRT) which a terpene resin having a softening temperature of 115 ° C. and a Mw of around 2300 Da.
    According to a preferred variant, the HMPSA composition (a) constituting the layer A consists essentially:
    - from 40 to 70% of the composition (al) of styrenic block copolymers; and
    - from 30 to 60% of at least one tackifying resin (a2) having a softening temperature between 5 and 140 ° C.
    According to another preferred variant, the HMPSA composition (a) constituting the layer A comprises or consists essentially:
    - from 50 to 70% of the composition (al) of styrenic block copolymers; and
    - from 30 to 50% of at least one tackifying resin (a2) having a softening temperature between 5 and 140 ° C.
    According to yet another preferred variant, the HMPSA composition (a) constituting the layer A can also comprise, in addition to the composition (a1) and the tackifying resin (s) (a2), from 0.1 to 2% of a or several stabilizers (or antioxidant). These compounds are introduced to protect the composition from degradation resulting from a reaction with oxygen which is likely to be formed by the action of heat, light or residual catalysts on certain raw materials such as tackifying resins. . These compounds can include primary antioxidants which scavenge free radicals and are generally substituted phenols such as Irganox® 1010 from CIBA. The primary antioxidants can be used alone or in combination with other antioxidants such as phosphites such as Irgafos® 168 also from CIBA, or also with UV stabilizers such as amines.
    Composition (a) can also comprise a plasticizer, but in an amount not exceeding 5%. A paraffinic and naphthenic oil (such as Primol® 352 from the company ESSO) can optionally be used as plasticizer, optionally comprising aromatic compounds (such as Nyflex 222B).
    Composition (a) can finally comprise mineral or organic fillers, pigments or dyes.
    The flow index (or Melt Elow Index MEI) of the hot-melt self-adhesive composition (a) of layer A is measured at 190 ° C. and for a total weight of 2.16 kg, in accordance with condition d) of the ISO 1133 standard. The MEI is the mass of composition (previously placed in a vertical cylinder) which flows in 10 minutes through a die of fixed diameter, under the effect of a pressure exerted by a piston loaded with a total weight of 2.16 kg. In the absence of any indication to the contrary, the values of MFI indicated in the present text have been measured under these same conditions.
    The hot-melt self-adhesive compositions of layer A having an MFI ranging from 2 to 100 g / 10 minutes are more particularly preferred.
    Description of the compositions (b) and (c) constituting, respectively, the bonding layers B and C:
    The link layers B and C are also known by the term "intermediate layers" or by the English term "tie layers".
    These 2 layers respectively consist of compositions (b) and (c), identical or different, each comprising:
    - a polyolefin (P) chosen from polyethylene (PE) and polypropylene (PP), optionally modified with an unsaturated carboxylic anhydride which is either a ring comprising 4 or 5 carbon atoms or a straight chain comprising 6 or 8 carbon atoms ; and
    - At least one elastomeric compound (EL) chosen from a copolymer of ethylene and propylene (hereinafter EL1) and a styrenic block copolymer (hereinafter EL2) comprising at least one elastomeric block.
    According to one embodiment, each of the compositions (b) and (c) comprises and, according to a preferred variant, consists essentially of:
    - from 50 to 98% by weight of the polyolefin (P); and
    - from 2 to 50% by weight of the elastomeric compound (EL);
    based on the total weight of said composition.
    A more particularly preferred area is:
    - from 55 to 97% by weight of the polyolefin (P); and
    - from 3 to 45% by weight of the elastomeric compound (EL).
    Polyolféine (P):
    The polyolefin (P) is chosen from polyethylene (PE) and polypropylene (PP), optionally modified with an unsaturated carboxylic anhydride which is either a ring comprising 4 or 5 carbon atoms or a straight chain comprising 6 or 8 carbon atoms .
    (PE) is a homopolymer (or copolymer) of polyethylene which can include a linear polyethylene such as HDPE (High Density PolyEthylene), linear low density polyethylene (LLDPE), very low or ultra low density (VLDPE or ULDPE) , a branched polyethylene such as low density polyethylene (or LDPE). Such polyethylenes can be prepared by several methods, including polymerization in the presence of a Ziegler-Natta catalyst, metallocene-catalyzed polymerization, radical polymerization.
    The (PE) or the (PP) included in the compositions (b) and (c) of the bonding layers (B) and (C) can optionally be modified by an unsaturated carboxylic anhydride which is either a ring comprising 4 or 5 atoms of carbon is a straight chain comprising 6 or 8 carbon atoms.
    As cyclic unsaturated carboxylic anhydride comprising 4 or 5 carbon atoms, the following compounds may be mentioned:
    - maleic anhydride of formula:
    - itaconic anhydride of formula:
    - citraconic anhydride of formula:
    As linear unsaturated carboxylic anhydride comprising 6 or 8 carbon atoms, the following compounds may be mentioned:
    - crotonic anhydride of formula:
    - the acrylic anhydride of formula:
    Maleic anhydride is a particularly preferred anhydride.
    The polyolefin (P) is preferably a (PE), which can optionally be modified by the unsaturated carboxylic anhydride as defined above.
    The term “modified polyethylene” is intended to denote by said anhydride either a copolymer of ethylene and said anhydride, or a homopolymer or copolymer of ethylene grafted with said anhydride.
    The ethylene and anhydride copolymers are, for example, random copolymers comprising:
    - a repeating pattern derived from ethylene,
    - a repeat motif derived from the anhydride, and possibly
    - a repeating motif derived from an alpha-olefin which may have from 3 to 20 carbon atoms. The alpha-olefins used can be propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene and 1octadecene.
    The copolymers of ethylene and anhydride can comprise from 0.3 to 20% by weight of the anhydride defined above, and - when the corresponding comonomer is present - from 20 to 30% by weight of alpha-olefin. The repeating unit derived from ethylene can represent from approximately 20, 40 or 50% to approximately 70, 80, 90 or 95% by weight of the copolymer.
    The grafted homopolymers (or copolymers) of ethylene are prepared by reacting an ethylene (co) polymer already formed with the compound to be grafted by heating, with or without a catalyst generating free radicals (such as an organic peroxide). and in the presence or not of a solvent.
    None of the constituent atoms of the grafted radical, often added by a radical reaction, is incorporated into the main chain of the (co) polymer of ethylene. The grafted radical is linked, as a pendant group, to certain repeating units of the main chain of the (co) polymer.
    The ethylene polymer which is grafted with the anhydride is either a homopolymer or a copolymer. Such a copolymer is for example a random copolymer comprising, in addition to the repeat unit derived from ethylene, a repeat unit derived from an alpha-olefin as defined above.
    According to a first alternative embodiment, the polyolefin (P) included in at least one of the compositions (b) and (c) is a (PE), preferably a (LDPE).
    According to a second alternative embodiment, the polyolefin (P) included in at least one of the compositions (b) and (c) is a (PE) grafted with maleic anhydride, preferably a (LLDPE) grafted with maleic anhydride .
    Many polyethylenes modified with maleic anhydride are commercially available.
    Æx
    We can thus cite Bynel 4206 marketed by DuPont which is an LLDPE Æx modified by maleic anhydride, or Orevac 18360 marketed by Arkema and ÆX
    Bynel 41E865 from DuPont which are both LLDPE grafted with maleic anhydride.
    According to a preferred variant, the modified polyethylene included in compositions (b) and (c) is a homopolymer or copolymer of grafted ethylene.
    Elastomeric compound (EL):
    The elastomeric compound (EL) is chosen from an ethylene-propylene copolymer (EL1) and a styrenic block copolymer (EL2) comprising at least one elastomer block.
    According to a 1 st embodiment, the elastomeric compound (EL) is a copolymer of ethylene and propylene (EL1).
    The copolymers of ethylene and propylene (also known as EthylenePropylene Rubber) form a class of synthetic rubbers used in the fields of automobile engines, electrical wiring and construction. They are prepared by polymerization of ethylene and propylene in solution in an organic solvent (such as hexane) in the presence of a Ziegler-Natta catalyst. The ethylene content by weight is usually 40 to 65% by weight, based on the total weight of monomers used. Copolymers of ethylene and propylene are also widely available commercially.
    According to an advantageous variant of this 1 st embodiment, at least one of the compositions (b) and (c) constituting the bonding layers B and C, comprises, and preferably consists essentially of:
    - from 50 to 85% by weight of (PE) grafted with maleic anhydride, preferably from 50 to 70%; and
    - from 15 to 50% by weight of (EL1), preferably from 30 to 50%, even more preferably from 35 to 45%.
    The (LLDPE) grafted with maleic anhydride is very particularly preferred as (PE) in the case of this variant.
    Such a mixture is also commercially available. Mention may thus be made of the product ADMER ™ AT1955E available from MITSUI CHEMICALS, which is a composition consisting essentially of approximately 55-60% by weight of LLDPE grafted with maleic anhydride and 40-45% by weight of Ethylene-Propylene Rubber.
    According to a 2 nd embodiment, the elastomeric compound (EL) is a styrenic block copolymer (EL2) comprising at least one elastomeric block.
    Said styrenic block copolymer is as defined above for the HMPSA composition (a) constituting the adhesive layer A, and is, according to a preferred variant of the invention, in the form of a diblock and triblock composition which is itself as defined above for the composition (al), and which can be identical or different to (al).
    According to an advantageous variant of this 2 nd embodiment, at least one of the compositions (b) and (c) constituting the bonding layers B and C, comprises, and preferably consists essentially of:
    - from 70 to 98% by weight of (PE), preferably from 80 to 97%; and
    - from 2 to 30% by weight of (EL2), preferably from 3 to 20%.
    (LDPE) is very particularly preferred as (PE) in the case of this variant.
    According to a preferred variant of the invention, the styrenic block copolymer (EL2) is itself included in an HMPSA composition which also comprises one or more tackifying resins and which is itself as defined above for the HMPSA composition (a ), and which may be the same or different from (a).
    Preferably, the styrenic block copolymer (EL2) is included in an HMPSA composition which is identical to the HMPSA composition (a) constituting the adhesive layer A.
    According to a variant also preferred, the compositions (b) and (c) of the layers B and C are identical.
    Description of the constituent composition of layers D and E:
    The adhesive layer A makes it possible, via the bonding layers B and C, to ensure the connection between a thin complexable layer D and a thin sealable and breakable layer E.
    The complexable layer can be complexed (or laminated) with other layers for producing the packaging, for example with a rigid layer for producing the receptacle.
    The sealable and breakable layer ensures, at the periphery along which the receptacle is linked by welding to the seal, the first opening of the package, by means of a breakable weakened zone. After opening, the weakened area reveals:
    - the mother adhesive layer on the lid strip and / or on the receptacle strip which were in contact in the closed packaging, and / or
    - 2 daughter adhesive layers resulting from the rupture of the mother adhesive layer and located on the seal strip and / or the receptacle strip.
    The material which can be used to form the 2 layers D and E is generally a thermoplastic polymer (identical or different for the 2 layers) such as:
    - polyethylene (PE),
    - polypropylene (PP),
    - a copolymer based on ethylene and propylene,
    - polyamide (PA),
    - polyethylene terephthalate (PET), or
    a copolymer based on ethylene such as for example a grafted copolymer of maleic anhydride, a copolymer of ethylene and vinyl acetate (EVA), a copolymer of ethylene and vinyl alcohol (EVOH), a copolymer of ethylene and an alkyl acrylate such as methyl acrylate (EMA) or butyl acrylate (EBA),
    - polystyrene (PS),
    - polyvinyl chloride (PVC),
    - polyvinylidene fluoride (PVDF),
    - a lactic acid polymer (PLA), or
    - a polyhydroxyalkanoate (PHA).
    It is preferred to use to form the 2 layers D and E a polyolefinic material, and very particularly PE, and even more preferably a low density PE (also designated by the English name of Low Density PolyEthylene or LDPE).
    The thickness of the layer A included in the multilayer film according to the invention can vary from 7 to 50 μm, preferably from 8 to 25 μιιι. even more preferably from 10 to 20 μ ιη.
    The thickness of the bonding layers B and C included in said multilayer film is generally between 1 and 10 μm, preferably between 2 and 8 μm.
    The thickness of the 2 layers D and E, as well as of the other layers possibly used in the multilayer film according to the invention is likely to vary within a wide range ranging from 5 to 150 μm.
    According to an alternative embodiment, the multilayer film according to the invention is a 5-layer film consisting of the adhesive layer A, the 2 intermediate layers B and C and the 2 outer layers D and E, according to the sequence D / B / A / C / E in which the sign “/” signifies that the faces of the layers concerned are in contact.
    According to another alternative embodiment, the multilayer film according to the invention comprises, in addition to the 5 layers A, B, C, D and E, other thin layers necessary for producing the packaging, such as for example:
    - a rigid layer necessary for the mechanical strength of the receptacle, or
    - a printable layer, or
    - a layer with a barrier effect against oxygen, water vapor or carbon monoxide.
    The materials which can be used to constitute said layers can be identical or different and generally comprise thermoplastic polymers which can be chosen from the polymers mentioned above for layers D and E.
    According to a more preferred variant embodiment, the multilayer film according to the invention is a 7-layer film consisting of:
    - the adhesive layer A,
    - the 2 intermediate layers B and C, of which at least layer B consists of 50 to 85% by weight of (PE) grafted with the anhydride as defined above and from 15 to 50% by weight of ethylene copolymer and propylene (EL1);
    a layer B O consisting of EVOH with a barrier effect against oxygen;
    - A 3rd intermediate layer B 'whose composition is as defined for composition (b), and preferably identical to that of the layer B;
    - a thin complexable layer D; and
    - a thin sealable and breakable layer E;
    according to the sequence D / B '/ BO / B / A / C / E in which the sign "/" means that the faces of the layers concerned are in contact.
    Due to the contact between the layer BO on the one hand and the layers B and B 'on the other hand, said multilayer film has improved cohesion, while being particularly suitable for the manufacture of a reclosable packaging which allows to keep more foodstuffs capable of reacting by oxidation with oxygen in the air, such as meat products.
    The present invention also relates to a process for manufacturing the multilayer film as defined above, characterized in that it comprises the co-extrusion of the hot-melt self-adhesive composition (a), of the compositions (b) and (c), and of the constituent materials of layers D and E.
    Preferably, the compositions and materials constituting the layers A, B, C, D and E are fed into the co-extrusion device in the form of granules of size between 1 and 10 mm, preferably between 2 and 5 mm. Thus, the self-adhesive composition (a) used in the multilayer film according to the invention makes it possible, in a particularly advantageous manner, to ensure both the properties required for said film and the possibility of a presentation of said composition. (a) in the form of the aforementioned granules. The other layers possibly included in the multilayer film can be obtained either by the incorporation in the co-extrusion device of the corresponding constituent materials in the form of granules of the same size, or by a process of complexing the film directly from the co -extrusion, using for example an adhesive based on polyurethane.
    The adhesive composition (a) can be prepared, in this form of granules, by simple mixing of its ingredients hot, between 150 and 200 ° C, preferably at about 160 ° C, using a 2-screw extruder provided a tool for cutting the extruded product at the outlet of the die
    The method of co-extrusion by bubble blowing (also known under the name of "co-extrusion by blowing of sheath") is more particularly preferred. In a manner known to a person skilled in the art, this process comprises:
    - the fusion, in separate extruders, of the compositions and materials constituting layers A, B, C, D and E, then
    - the passage of the corresponding flows through a set of annular and concentric dies, so as to form a tubular bubble with several layers, in the order corresponding to that desired for the final structure, then
    - the radial expansion (relative to the annular die) and the stretching (in the axial direction) of the bubble, then
    - the cooling of the bubble.
    The geometrical characteristics of the dies, as well as the process parameters such as the rate of radial expansion and the speed of stretching are fixed so as to obtain the desired thickness for the various constituent layers of the multilayer film. Reference is made in particular to the further description of the co-extrusion process by bubble blowing at the patent application US2013 / 0029553.
    The present invention also relates to the use of the multilayer film as described above for the manufacture of reclosable packaging.
    The use for the manufacture of resealable trays is particularly advantageous, and according to a particularly preferred embodiment for the manufacture of the sealing film of these trays.
    The following examples are given purely by way of illustration of the invention, and should in no case be interpreted to limit its scope.
    Example A (reference): composition (a) of layer A
    A composition is prepared, in the form of granules of approximately 4 mm in diameter, consisting, on the basis of% w / w, of 59.5% of Kraton® D1113BT, 25% of Escorez® 1310 LC, 15% of Dercolyte® S115 and 0.5% of Irganox® 1010 by simple mixing of the ingredients at 160 ° C using a 2-screw extruder.
    MEI of 57 g / 10 minutes is measured.
    Example B (reference): three-layer film D / A / E consisting of a layer A of the composition of example A:
    This three-layer film is manufactured by means of a continuous bubble blowing co-extrusion pilot device, into which 3 extruders are supplied:
    - for one, by the composition a of example A, and
    - for the other 2, by LDPE;
    the 3 compositions being in the form of granules with a size of approximately 4 mm.
    The process parameters are adjusted so as to manufacture a three-layer film consisting of:
    - as layer A, a layer of thickness 15 μm made up of the composition of example A,
    - As a complexable thin layer D, a layer 25 μm thick made of LDPE;
    - as a sealable and breakable thin layer E, with a thickness of 10 μm ιη also made of LDPE.
    Among the parameters usually set, there is a radial expansion rate of the bubble equal to 3, a stretching speed of 7 m / minute and an overall flow rate of 11 kg / hour.
    The three-layer film thus obtained has a total thickness of 50 μm, a length of 50 m and is packaged in the form of a roll of 250 mm in width.
    Measurement of the force of first opening by T peeling at 23 ° C:
    A sample is cut from the three-layer film thus obtained in the form of a rectangular sheet in A4 format (21 x 29.7 cm).
    The external face of the complexable layer D of this sample is:
    - initially subjected to a Corona surface treatment (using a plasma), then
    - in a second step complexed (in other words laminated or laminated) on a PET film with a thickness of 23 μm using a solvent-based adhesive based on polyurethane and using a coating device of the Mayer bar type .
    The rectangular sheet is then placed in a press for 24 hours.
    Then, said rectangular sheet is folded along a line located in its middle and parallel to the short side of the rectangle, leading to the bringing into contact with itself of the sealable and breakable layer E.
    We then proceed to a partial sealing, by means of two jaws heating to 130 ° C, applied under a pressure of 6 bar for 1 second, so as to obtain sealed areas of rectangular shape (8 cm in length and 1 cm in width ) arranged perpendicular to the fold line. Each sealed area is cut to obtain a tensile test piece in which the sealed area of 8 cm in length is extended (to that of its ends which is opposite to the fold line) by 2 strips of about 2 cm in length left free and not sealed.
    These two free bands are fixed on two fastening devices (called jaws) connected, respectively, to a fixed part and a mobile part of a traction device which are located on a vertical axis. This traction device is a dynamometer.
    While a drive mechanism communicates to the moving part a uniform speed of 300 mm / minute leading to the peeling of the 2 sealed layers, the ends move progressively along a vertical axis at an angle of 180 °. A force sensor connected to said movable part measures the force supported by the test piece thus maintained. The measurement is carried out in a climatic room maintained at a temperature of 23 ° C.
    The force obtained is shown in Table 1.
    Second opening force measurement by T peeling at 23 ° C:
    The 2 parts of the previous test piece are, after peeling, repositioned opposite one another and brought into contact manually. They are then subjected to a pressure exerted by means of a roller of mass 2 kg with which one proceeds to a back-and-forth movement in a direction parallel to the length of the test piece.
    A tensile test piece is thus obtained which is identical in shape to that prepared for the previous peeling test which is then repeated.
    The force obtained is shown in Table 1.
    Example 1: 5-layer film D / B / A / C / E with layer A consisting of the composition of example A and layers B and C consisting of Γ ADMER ™ AT1955E:
    Example B is repeated, modifying the co-extrusion process so as to add to the three-layer film 2 layers B and C having the same thickness of 5 μm and the same composition, namely the product ADMER ™ AT1955E as indicated in the Table. 1.
    A 5-layer film with a total thickness of 60 µm is obtained.
    The forces of the era and 2nd opening are shown in Table 1.
    Example 2: film with 5 layers D / B / A / C / E with layer A consisting of the composition of example A and layers B and C consisting of 95% LDPE and 5% of the composition of example A :
    Example 1 is repeated, modifying the co-extrusion process so as to add to the three-layer film 2 layers B and C having the same thickness of 5 μm and the same composition. Said composition consists (by weight) of 95% of LDPE and of 5% of the composition of Example A. The composition of the 2 layers B and C is obtained by feeding the corresponding extruders by the appropriate dosage of LDPE granules and of granules of the composition of Example A.
    The forces of the era and 2nd opening are shown in Table 1.
    Examples 3-5: 5-layer film D / B / A / C / E with layer A consisting of the composition of example A and layers B and C consisting of LDPE and the composition of example A:
    Example 2 is repeated using as the material constituting the 2 bonding layers 5 B and C that indicated in Table 1.
    The forces of the era and 2nd opening are also shown in Table 1.
    The force results from the opening ere obtained for Examples 1-5 are of the same order of magnitude as that obtained for one example B, and correspond to a quality opening 10 of reclosable package quite acceptable.
    The results for the strength of 2nd opening show a clear increase compared to Example B, indicating a significantly improved quality of the reclosing of the resealable package, following his opening the era .
    [Table 1]
    Example B Example 1 Example 2 Example 3 Example 4 Example 5 Material of the 2 bonding layers B and C Not concerned ADMER ™AT1955E 95% LDPE and 5% composition example A 90% LDPE and 10% composition example A 80% LDPE and 20% composition example A 70% LDPE and 30% composition example A Force the era opening (N / cm) 4.93 6.80 4.73 4.65 5.32 5.88 Force of 2 nd opening (N / cm) 0.96 2.98 1.26 1.33 1.32 1.27
    权利要求:
    Claims (15)
    [1" id="c-fr-0001]
    1. Multilayer film comprising 2 thin layers D and E of a thermoplastic material bonded together by a continuous layer A which has a thickness ranging from 7 to 50 μm, and is constituted by an HMPSA composition (a) comprising, on the base of the total weight of said composition:
    - from 40 to 70% by weight of a composition (al) of styrenic block copolymers comprising at least one elastomer block, said composition (al) being formed, on the basis of its total weight:
    from 30 to 90% by weight of at least one diblock copolymer chosen from the group comprising SI, SBI, SIB, SB, SEB, and SEP, and
    - from 10 to 70% by weight of at least one triblock copolymer chosen from the group comprising SIS, SIBS, SBS, SEBS and SEPS;
    the content of total styrenic units of said composition (a1) varying from 10 to 40% by weight based on the total weight of a1; and
    - from 30 to 60% by weight of one or more tackifying resins (a2);
    said multilayer film being further characterized in that the adhesive layer A is:
    - connected to layer D via a link layer B, and
    - connected to layer E via a bonding layer C;
    each of the 2 layers B and C being constituted respectively by a composition (b) and (c) each comprising:
    - a polyolefin (P) chosen from polyethylene (PE) and polypropylene (PP), optionally modified with an unsaturated carboxylic anhydride which is either a ring comprising 4 or 5 carbon atoms or a straight chain comprising 6 or 8 carbon atoms ; and
    - At least one elastomeric compound (EL) chosen from a copolymer of ethylene and propylene (EL1) and a styrenic block copolymer (EL 2) comprising at least one elastomer block.
    [2" id="c-fr-0002]
    2. Multilayer film according to claim 1, characterized in that the composition (al) consists of a triblock SIS copolymer and a diblock SI copolymer.
    [3" id="c-fr-0003]
    3. Multilayer film according to one of claims 1 or 2, characterized in that the tackifying resin (s) (a2) which can be used have average molar masses by weight M w generally between 300 and 5000 Da and are chosen in particular from:
    - (i) rosins of natural or modified origin, such as, for example, rosin extracted from pine gum, wood rosin extracted from the roots of the tree and their hydrogenated, dehydrogenated, dimerized, polymerized or esterified derivatives monoalcohols or polyols such as glycerol;
    - (ii) resins obtained by hydrogenation, polymerization or copolymerization (with an aromatic hydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons having about 5, 9 or 10 carbon atoms derived from petroleum fractions;
    - (iii) terpene resins generally resulting from the polymerization of terpene hydrocarbons such as, for example, mono-terpene (or pinene) in the presence of Friedel-Crafts catalysts, optionally modified by the action of phenols;
    - (iv) copolymers based on natural terpenes, for example styrene / terpene, alpha-methyl styrene / terpene and vinyl toluene / terpene.
    [4" id="c-fr-0004]
    4. Multilayer film according to one of claims 1 to 3, characterized in that each of the compositions (b) and (c) constituting the bonding layers B and C comprises:
    - from 50 to 98% by weight of the polyolefin (P); and
    - from 2 to 50% by weight of the elastomeric compound (EL);
    based on the total weight of said composition.
    [5" id="c-fr-0005]
    5. Multilayer film according to one of claims 1 to 4, characterized in that the polyolefin (P) included in at least one of the compositions (b) and (c) is a (PE), preferably a (LDPE).
    [6" id="c-fr-0006]
    6. Multilayer film according to one of claims 1 to 4, characterized in that the polyolefin (P) included in at least one of the compositions (b) and (c) is a (PE) grafted with maleic anhydride, preferably one (LLDPE) grafted with maleic anhydride.
    [7" id="c-fr-0007]
    7. Multilayer film according to one of claims 1 to 6, characterized in that at least one of the compositions b and c constituting the bonding layers B and C, comprises:
    - from 50 to 85% by weight of (PE) grafted with maleic anhydride; and
    - from 15 to 50% by weight of ethylene-propylene copolymer (EL1).
    [8" id="c-fr-0008]
    8. Multilayer film according to one of claims 1 to 5, characterized in that the styrenic block copolymer (EL2) is in the form of a diblock and triblock composition as defined for the composition (al).
    [9" id="c-fr-0009]
    9. Multilayer film according to one of claims 1 to 5 and according to claim 8, characterized in that at least one of the compositions (b) and (c), constituting the bonding layers B and C, comprises:
    - from 70 to 98% by weight of (PE); and
    - from 2 to 30% by weight of styrenic block copolymer (EL2) comprising at least one elastomer block.
    [10" id="c-fr-0010]
    10. Multilayer film according to one of claims 1 to 5 and 8 or 9, characterized in that the styrenic block copolymer (EL2) is included in an HMPSA composition which is as defined for the HMPSA composition (a).
    [11" id="c-fr-0011]
    11. Multilayer film according to one of claims 1 to 10, characterized in that the compositions (b) and (c) of layers B and C are identical.
    [12" id="c-fr-0012]
    12. Multilayer film according to one of claims 1 to 11, characterized in that it is a 5-layer film consisting of the adhesive layer A, the 2 intermediate layers B and C and the 2 outer layers D and E, according to the sequence D / B / A / C / E in which the sign “/” signifies that the faces of the layers concerned are in contact.
    [13" id="c-fr-0013]
    13. Method for manufacturing the multilayer film as defined in one of claims 1 to 12, characterized in that it comprises the co-extrusion of the hot-melt self-adhesive composition (a), of the compositions (b) and (c) , and constituent materials of layers D and E.
    [14" id="c-fr-0014]
    14. A method of manufacturing the multilayer film according to claim 13, characterized in that the co-extrusion is carried out by bubble blowing.
    [15" id="c-fr-0015]
    15. Use of the multilayer film as defined in one of claims 1 to 12 for the manufacture of reclosable packages.
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    同族专利:
    公开号 | 公开日
    US20210402746A1|2021-12-30|
    EP3877174A1|2021-09-15|
    BR112021008874A2|2021-08-31|
    CO2021005990A2|2021-05-20|
    JP2022506765A|2022-01-17|
    FR3088239B1|2020-11-20|
    KR20210089223A|2021-07-15|
    CA3118349A1|2020-05-14|
    WO2020094945A1|2020-05-14|
    CN113272127A|2021-08-17|
    CL2021001163A1|2021-10-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP1053952A1|1999-05-21|2000-11-22|Soplaril SA|Resealable package having a tearable layer and and method of manufacturing the same|
    WO2002064694A1|2001-02-09|2002-08-22|Bostik Findley S.A.|Hot-extrudable thermofusible self-adhesives and the use thereof in multi-layer films|
    US20080032148A1|2006-08-03|2008-02-07|Lee Chun D|Propylene elastomer-containing adhesive blends|
    WO2012045951A1|2010-09-27|2012-04-12|Bostik S.A.|Multilayer film for resealable packaging|
    WO2012045950A1|2010-09-27|2012-04-12|Bostik S.A.|Multilayer film for resealable packaging|
    US20130029553A1|2011-07-27|2013-01-31|E I Du Pont De Nemours And Company|Multilayer films for reclosable packaging|
    US20130052471A1|2011-08-26|2013-02-28|Equistar Chemicals, Lp|Graft composition having long chain branched olefins for improved layers|
    WO2014020243A1|2012-07-30|2014-02-06|Bostik S.A.|Hot-melt pressure-sensitive adhesive for a reclosable packaging having improved organoleptic properties|
    EP2946920A1|2014-05-22|2015-11-25|Bostik Sa|Multilayer film for reclosable packaging with improved reclosing|WO2021240087A1|2020-05-26|2021-12-02|Bostik Sa|Multilayer film for reclosable packaging with polypropylene layer obtained by flat sheet co-extrusion|
    WO2021240086A1|2020-05-26|2021-12-02|Bostik Sa|Multilayer film for reclosable package with a polyethylene layer obtained by flat sheet coextrusion|
    法律状态:
    2019-10-14| PLFP| Fee payment|Year of fee payment: 2 |
    2020-05-15| PLSC| Publication of the preliminary search report|Effective date: 20200515 |
    2020-10-13| PLFP| Fee payment|Year of fee payment: 3 |
    2021-10-18| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1871410A|FR3088239B1|2018-11-08|2018-11-08|NEW MULTI-LAYER FILM FOR ENHANCED CLOSURE RESEALABLE PACKAGING|FR1871410A| FR3088239B1|2018-11-08|2018-11-08|NEW MULTI-LAYER FILM FOR ENHANCED CLOSURE RESEALABLE PACKAGING|
    CN201980088396.0A| CN113272127A|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealability|
    KR1020217017300A| KR20210089223A|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealability|
    CA3118349A| CA3118349A1|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealing|
    EP19813107.0A| EP3877174A1|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealing|
    US17/292,088| US20210402746A1|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealing|
    PCT/FR2019/052539| WO2020094945A1|2018-11-08|2019-10-24|Novel multilayer film for resealable packaging with improved resealing|
    JP2021524351A| JP2022506765A|2018-11-08|2019-10-24|New multilayer film for resealable packages with improved resealability|
    BR112021008874-1A| BR112021008874A2|2018-11-08|2019-10-24|MULTI-LAYER FILM FOR RESEALABLE PACKAGING WITH IMPROVED RESEALING ABILITY|
    CL2021001163A| CL2021001163A1|2018-11-08|2021-05-03|New multilayer film for resealable containers with improved resealing.|
    CONC2021/0005990A| CO2021005990A2|2018-11-08|2021-05-07|New multilayer film for resealable packaging with improved resealing|
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