Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels
  • B29C48/08—Flat, e.g. panels flexible, e.g. films
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/10—Polymers of propylene
  • B29K2023/12—PP, i.e. polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
  • B32B2309/08—Dimensions, e.g. volume
  • B32B2309/10—Dimensions, e.g. volume linear, e.g. length, distance, width
  • B32B2309/105—Thickness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2553/00—Packaging equipment or accessories not otherwise provided for
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
  • B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
  • B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state

Definitions

• the present invention relates to a multilayer film comprising at least one layer (A), based on a homopolymer or copolymer of propylene, at least one layer (B), essentially based on a radical homopolymer or copolymer of ethylene, and at least one particular binder layer (L), disposed between two layers (A) and (B).
• Bi-layer films are known comprising a first layer of a composition based on a mixture of polypropylene and polyethylene and a second layer based on polyethylene, as well as bilayer films comprising two layers each of a composition based on polypropylene and polyethylene, the proportions of the two constituents being different from one layer to another.
• bilayer films are not always satisfactory in applications where it is desired that one of the layers is predominantly polyethylene and the other, predominantly polypropylene, such as, for example, in the case of shrink wrapping for wrapping, such as described below.
• the bilayer films comprising a layer based on radical polyethylene and a layer based on polypropylene, do not exhibit sufficient adhesion of these two layers, leading to unacceptable delamination on 'use. It is this problem of incompatibility between these two types of layers that the Applicant Company sought to resolve.
• the solution which it proposes for this purpose, and which is the subject of the present invention, consists in providing, between two layers of the aforementioned type, a binder layer of a copolymer of ethylene and at least one alpha -olefin, which may be advantageously associated with a homopolymer and / or a copolymer of propylene. It has been observed - which will be shown by
• the adhesion after aging of the films according to the invention, the adhesion generally shows only a very small decrease in its original value (less than 10%).
• the present invention therefore firstly relates to a multilayer film comprising two external (surface) layers and at least one intermediate layer, characterized in that, for all the successive layers which compose it, it comprises at least once the succession of the following three layers: a layer (A), which comprises: (a) at least one homopolymer of propylene, and / or
• binder layer (L) which comprises:
• At least one radical polymer of ethylene chosen from radical homopolymers of ethylene and radical copolymers of ethylene and of at least one polar comonomer, or
• the multilayer film according to the invention can constitute a complex structure comprising layers of a nature different from (A), (L) and (B).
• its two outer layers are of type (A) and / or (B). They can be of different types (A on the one hand, B, on the other hand) in a three-layer film or 7 layers; they are of the same nature (A or B) in a film with 5 or 9 layers.
• multilayer films in which a layer of a polymer of the same kind as that constituting at least one layer A and / or B is attached to said layer.
• multilayer films of type A '/ A / L / B, A / L / B / B' and A '/ A / L / B / B' in which the polymer constituting layer A 'is of the type (a) and / or (b), and the polymer constituting the layer B * is of the type (c) and / or (d).
• the same polymer can constitute the layers (A) and (A *).
• the same other polymer can constitute the layers (B) and (B ').
• the binding layer (L) can further comprise:
• the binder layer (L) thus notably consists of a mixture of: 93 to 30% by weight, preferably 83 to 43% by weight, more preferably 78 to 53% by weight, of the component (e); and
• component (f) and / or (g) 7 to 70% by weight, preferably 17 to 57% by weight, even more preferably 22 to 47% by weight, of component (f) and / or (g).
• the constituent (a) of a layer (A) is a homopolymer of propylene, obtained, for example, by polymerization using Ziegler type catalysts, and having in particular a density between 0.89 and 0.91, an index fluidity advantageously between 2 and 20 g / 10 min. about.
• Components (b) and (g) may be the same or different. They each consist of at least one propylene copolymer, chosen from random, block and block copolymers of propylene and at least one alpha-olefin chosen from ethylene and C 1 -C 4 alpha-olefins. These copolymers can be obtained by copolymerization of propylene and of the selected comonomer (s) (preferably ethylene), in the presence of stereospecific Ziegler type catalysts, for example in suspension in a solvent or in phase liquid.
• copolymers advantageously have a density between 0.89 and 0.91, and a melt index advantageously between 3 and 20 g / 10 min.
• An isotactic, random copolymer containing 85 to 99%, preferably 90 to 99%, in moles of propylene units, and 1 to 15%, preferably 1 to 10%, in moles of ethylene units, will advantageously be chosen.
• whose melting point J is between 130 and 150 "C, preferably between 130 and 140 ° C.
• Concerning the constituent (c) of a layer (B), by radical homopolymer of ethylene is meant a product obtained by polymerization of ethylene under high pressure
• radical copolymer of ethylene is meant a product obtained, by a polymerization carried out under the same conditions as those which have just been indicated, of ethylene with at least one monomer copolymerizable with ethylene, such as , for example, carbon monoxide, ethylenically unsaturated carboxylic acids, esters derived from said acids and from an alcohol having from 1 to 8 carbon atoms, maleic anhydride, vinyl acetate, etc.
• a radical homo- or copolymer of ethylene having a density of between approximately 0.910 and 0.940, in particular a density of between approximately 0.915 and 0.935, and a melt index included between about 0.15 and 20 dg / min.
• the alpha-olefin used to prepare the copolymer (d) advantageously has from 3 to 12 carbon atoms, preferably from 3 to 8 carbon atoms. It is chosen, for example, from propylene, butene-1, methyl-4-pentene-1, hexene-1, octene-1 and their mixtures.
• These ethylene copolymers are prepared by copolymerization of ethylene with at least one of the alpha-olefins mentioned above, in the presence of catalytic systems of the Ziegler type, in solution, in emulsion, in gas phase or in the state hypercritical.
• copolymers obtained using a process consisting in copolymerizing ethylene and at least one alpha-olefin are used at a temperature between approximately 180 and 300 ° C., under a pressure comprised between approximately 300 and 2500 bars, preferably according to a method continuous, the residence time of the catalytic system in the copolymerization reactor being between 1 and 150 seconds.
• the content of the comonomer in the gas stream is adjusted as a function of the nature of the latter and of the density desired for the copolymer.
• a gas stream is polymerized containing from 30 to 50% by weight of approximately ethylene and from 50 to 70% of comonomer (s).
• a transfer agent such as hydrogen
• linear copolymers of ethylene in the mixture (d) it may be indicated that a choice is made not to affect the optical properties of the radical polymers (c) too much, although it is increased thus the mechanical properties.
• the linear copolymer (s) of ethylene and at least one ⁇ -olefin entering the mixture defining the constituent (d) advantageously represents from 5 to 15% by weight of said ( or said radical polymer (s) of ethylene as the base of said mixture.
• the layer (A) can also comprise: (h) up to 20% by weight of said external layer (A) of at least one copolymer of ethylene and at least one C 3 -CiL 2 alpha-olefin, having a content of units derived from ethylene of at least 70 mol%.
• the constituent (e) involved in the formation of the binder layer (L) is at least one copolymer chosen in particular from ethylene copolymers: with at least one alpha-olefin having 3 to 12 carbon atoms; containing at least 70 mole% of units derived from ethylene; - having a density between 0.860 and 0.930; having a degree of crystallinity, measured by X-ray diffraction, of at least 2%; and having a melt index of between 0.5 and 10 g / 10 min.
• ethylene copolymers chosen in particular from ethylene copolymers: with at least one alpha-olefin having 3 to 12 carbon atoms; containing at least 70 mole% of units derived from ethylene; - having a density between 0.860 and 0.930; having a degree of crystallinity, measured by X-ray diffraction, of at least 2%; and having a melt index of between 0.5 and 10 g / 10 min.
• a layer (B) advantageously constitutes at least one outer layer and consists of the radical polymer (s) and the binder layer (L) only comprises the copolymer (e ), it is preferable that the latter has a density between 0.900 and 0.930.
• compositions of each layer (A), (B) and (L) of the film according to the invention can be prepared by any known means of mixing their constituents, for example, by mixing granules or powder, then, as the case may be. if necessary, mixing in the molten state of this mixture, then extrusion and regranulation. From these granules, the film is converted.
• the films are obtained in a known manner, by using a coextrusion of the compositions in the molten state intended to form the layers (A), (B) and (L), through a flat die, or else to through a die comprising at least three concentric channels, opening in a circular air gap co-axial with said channels, in which case it is followed by a blowing of the tubular sheath formed, the compositions of each of the three layers each having a melt index in particular between 0.5 and 5 g / 10 min .
• the thickness of the three-layer film is generally between 15 and 500 ⁇ m, each of the layers (A), (B) and (L) having a thickness ranging from 5 ⁇ m to 300 ⁇ m.
• the present invention also relates to the use of a multilayer film as defined above, more particularly in its simplest form of three-layer film, in the field of shrinkable covers, for example for wrapping on pallets of products contained in envelopes of polyethylene, at least one layer (A) of said multilayer film constituting an external layer and being in contact with said polyethylene envelopes, thus avoiding sticking of the cover to the envelopes.
• the characteristics of the copolymers and the results of the measurements were obtained as follows: the molar contents in units constituent of polymers: by infrared spectroscopy; - densities: according to standard ASTM D-1505; the fluidity indices, expressed in g / 10 min. : according to standard ASTM D-1238 under the conditions: (E) (190 ° C., 2.16 kg) for polymers of ethylene; and
• the sample to be tested is, after having started the peeling, placed in the tensiometer so that each of the primers is clamped by one of the two jaws. A 90 ° peeling angle between on the one hand each of the outer layers and, on the other hand, the rest of the sample is maintained during peeling. The width of the sample is 15 mm.
• the tensile test (peeling phase) is carried out at a speed of 300 mm / min. The measurements were carried out on days 0 and 14, after storage at room temperature. In the examples below, the sample was taken in the longitudinal direction (machine direction).
• Aal or Lfl homopolymer of propylene, sold under the name "VESTOLENE P 6000"; Ab2 or Lg2: block copolymer of propylene, sold under the name “HOSTALENE PPR 1042”; Bel: radical homopolymer of ethylene, density 0.924 and melt index 0.80, marketed under the name "RIBLENE
• Le2 (or Ahl): terpolymer of ethylene, propylene and butene-1, having a density of 0.881 and a melt index of 1.2, sold under the name "CLEARFLEX CH GO" by the company ECP - ENICHEM POLYMERES FRANCE SA;
• Le3 terpolymer of ethylene (88 mol%), propene and butene-1, density 0.898, and melt index 0.8, sold under the name "CLEARFLEX FF DO" by the company ECP - ENICHEM POLYMERES FRANCE SA;
• Le4 copolymer of ethylene (96 mol%) and butene-1, density 0.920, and melt index 1.0, sold under the name "FLEXIRENE FG 20" by the company ECP - ENICHEM POLYMERES FRANCE SA In the examples, the percentages are given by weight unless otherwise indicated.
• a bilayer film B / A was produced by coextrusion, the thicknesses of the outer layers (B) and (A) being 30 ⁇ m and 20 ⁇ m respectively.
• the results of the adhesion test are reported in Table 1 below:
• the thicknesses of the layers (B), (L) and (A) being 30 ⁇ m, 10 ⁇ m and 20 ⁇ m respectively.
• the constituents of layer (L) were dry mixed for extrusion.
• the layer (A) constitutes, as in all the examples, the layer facing the outside of the sheath during the extrusion-blowing.
• the binder layer being obtained as in Examples 4 to 7.
• Layer A is also obtained after dry mixing of the granules.
• the thicknesses of the successive layers B, L and A are respectively 20 ⁇ m, 10 ⁇ m and 30 ⁇ m.

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Cited By (1)

Citations (10)

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• 1992
  • 1992-12-31 FR FR9215999A patent/FR2699856B1/fr not_active Expired - Fee Related
• 1993
  • 1993-12-30 KR KR1019940703042A patent/KR950700172A/ko not_active Application Discontinuation
  • 1993-12-30 EP EP94903932A patent/EP0627992A1/fr not_active Withdrawn
  • 1993-12-30 JP JP6515739A patent/JPH08500550A/ja active Pending
  • 1993-12-30 CA CA002131085A patent/CA2131085A1/fr not_active Abandoned
  • 1993-12-30 WO PCT/FR1993/001320 patent/WO1994015787A1/fr not_active Application Discontinuation
• 1994
  • 1994-08-30 NO NO943205A patent/NO301465B1/no unknown
  • 1994-08-30 FI FI943972A patent/FI943972A/fi not_active Application Discontinuation

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