WO2024013378A1 - Film multicouche à orientation uniaxiale - Google Patents

Film multicouche à orientation uniaxiale Download PDF

Info

Publication number
WO2024013378A1
WO2024013378A1 PCT/EP2023/069674 EP2023069674W WO2024013378A1 WO 2024013378 A1 WO2024013378 A1 WO 2024013378A1 EP 2023069674 W EP2023069674 W EP 2023069674W WO 2024013378 A1 WO2024013378 A1 WO 2024013378A1
Authority
WO
WIPO (PCT)
Prior art keywords
film
multilayer
layers
layer
eba
Prior art date
Application number
PCT/EP2023/069674
Other languages
English (en)
Inventor
Raquel LASIERRA MORALES
María Soledad BERMÚDEZ UYARRA
Mariana SANCHEZ CAPUTO
Almudena DOMÍNGUEZ DORADO
Luis Miguel MÉNDEZ LLATAS
Original Assignee
Repsol, S.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Repsol, S.A. filed Critical Repsol, S.A.
Publication of WO2024013378A1 publication Critical patent/WO2024013378A1/fr

Links

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
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • 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
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/308—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising acrylic (co)polymers
    • 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
    • B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
    • 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
    • B32B2250/00—Layers arrangement
    • B32B2250/05—5 or more layers
    • 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
    • B32B2250/00—Layers arrangement
    • B32B2250/24—All layers being polymeric
    • B32B2250/246—All polymers belonging to those covered by groups B32B27/32 and B32B27/30
    • 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
    • B32B2250/00—Layers arrangement
    • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
    • 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
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/406—Bright, glossy, shiny surface
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/412—Transparent
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/514—Oriented
    • B32B2307/516—Oriented mono-axially
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength
    • 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

Definitions

  • This invention relates to a polyethylene multilayer film with some improved mechanical properties that has been uniaxially stretched in the machine direction.
  • a multilayer blocked MDO film comprising an inner blocking layer which is an ethylene vinyl acetate (EVA) or an ethylene butyl acrylate (EBA) copolymer.
  • EVA ethylene vinyl acetate
  • EBA ethylene butyl acrylate copolymer
  • Machine Direction Orientation is a proven technology based on monoaxial stretching of blown films. This technology allows improving physical and barrier properties, while significantly reducing material costs.
  • MDO machine direction oriented
  • multilayer films typically several polymer melt streams are coextruded to form a tube which is blown-up.
  • the formed bubble can then be collapsed (blocked) in nip rolls to form a film where the inner layers are contacted inside/inside. Then the multilayer film is subjected to an MDO process.
  • the first step in the MDO process is preheating, where a film is introduced into the stretching unit and uniformly heated to a temperature slightly below its melting point. This is followed by orientation, where the film is stretched between a series of rollers rotating at different speeds. Then, the film is subjected to an annealing stage, during which the new properties of the film are defined. Finally, it is cooled at or close to room temperature again.
  • the inner layer has some "natural stickiness" so that the tube is well blocked after the film extrusion process.
  • Plastomers and elastomers are currently used for the blocking layer.
  • a multilayer machine direction oriented blocked blown film which comprises a specific combination of a high density polyethylene (HDPE) outer layer, a metallocene linear low density polyethylene (mLLDPE) core layer, and an EVA or EBA inner blocking layer provides advantageous mechanical properties, such as higher tensile stress and strain at break in transverse direction, than a similar film where a plastomer is used as blocking layer.
  • the multilayer MDO film of the invention has also an improved gloss while having a similar or even better haze value compared to prior art films prepared with a plastomer as blocking layer, what means a better aesthetic performance of final package.
  • a first aspect of the invention relates to a blocked blown multilayer uniaxially oriented film (multilayer MDO film) comprising a structure comprising:
  • a second outer layer (A’) wherein the first and second inner blocking layers are fused and form one layer, and wherein the layers (A) and (A’) have the same composition and comprise a high-density polyethylene (HDPE), the layers (B) and (B’) have the same composition and comprise a metallocene linear low density polyethylene (mLLDPE), and the layers (C) and (O’) have the same composition and comprise a copolymer selected from the group consisting of ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), and a mixture thereof.
  • HDPE high-density polyethylene
  • mLLDPE metallocene linear low density polyethylene
  • EVA ethylene vinyl acetate
  • EBA ethylene butyl acrylate
  • a second aspect of the invention relates to a process for preparing a blocked blown multilayer MDO film as defined in claim 1, the process comprising a) coextruding at least: a composition comprising a high density polyethylene (HDPE); a composition comprising a metallocene linear low density polyethylene (mLLDPE); and a composition comprising a copolymer selected from the group consisting of ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), and a mixture thereof; to form a tubular multilayer film structure comprising: an outer layer (A) comprising HDPE; a core layer (B) comprising mLLDPE; and an inner blocking layer (C) comprising a copolymer selected from the group consisting of EVA, EBA, and a mixture thereof; b) blowing by blown extrusion into the multilayer tubular film to form a bubble; c) collapsing the formed bubble to form a blocked blown multilayer film where layers (C) are
  • the process of the invention allows to reduce neck-in in the MDO stretching and, consequently, trimming after orientation, while requiring lower extruder pressure and motor load than by using a plastomer as blocking layer. All this results in an improved production economy.
  • EVA or EBA as blocking layer provide a better blocking of the primary film, what means a higher security against delamination.
  • a third aspect of the invention relates to the use of the multilayer MDO film as defined herein above and below in packaging.
  • a further aspect relates to an article packaged using a multilayer MDO film as defined herein above and below.
  • a first aspect of the present disclosure relates to a multilayer MDO film as defined above comprising a structure comprising at least six layers, (A), (B), (C), (C’), (B’), and (A’), wherein layers C and C are fused and form one layer.
  • the inner blocking layer can simply be defined as one layer C
  • a ABCB'A' can simply be defined as ABCBA.
  • first outer layer (A) is in direct contact with the first core layer (B) and the second outer layer (A’) is in direct contact with the second core layer (B’).
  • first core layer (B) is in direct contact with the first inner first blocking layer (C) and the second core layer (B’) is in direct contact with the second inner second blocking layer (C’).
  • the first outer layer (A) is in direct contact with the first core layer (B), the first core layer (B) is in direct contact with the first inner first blocking layer (C), the second outer layer (A’) is in direct contact with the second core layer (B’), and the second core layer (B’) is in direct contact with the second inner second blocking layer (C’).
  • the structure consists of an ABCBA structure.
  • the blocked blown multilayer MDO film of the invention comprises or consists of an ABCBA structure.
  • the outer layers (A) and (A’) comprises from 60 wt.% to 100 wt.% HDPE. In another embodiment, the outer layers (A) and (A’) comprises from 70 wt.% to 100 wt.% HDPE. In another embodiment, the outer layers (A) and (A’) comprises from 80 wt.% to 100 wt.% HDPE. In another embodiment, the outer layers (A) and (A’) comprises from 90 wt.% to 100 wt.% HDPE.
  • the core layers (B) and (B’) comprises from 60 wt.% to 100 wt.% mLLDPE. In another embodiment, the core layers (B) and (B’) comprises from 70 wt.% to 100 wt.% mLLDPE. In another embodiment, the core layers (B) and (B’) comprises from 80 wt.% to 100 wt.% mLLDPE. In another embodiment, the core layers (B) and (B’) comprises from 90 wt.% to 100 wt.% mLLDPE.
  • the outer layers (A) and (A’) comprises from 60 wt.% to 100 wt.% HDPE and the core layers (B) and (B’) comprises from 60 wt.% to 100 wt.% mLLDPE.
  • the outer layers (A) and (A’) consists essentially of a HDPE.
  • the core layers (B) and (B’) consists essentially of a mLLDPE.
  • the inner blocking layers (C) and (C’) consists essentially of a copolymer selected from EVA, EBA, or a mixture thereof.
  • each layer independently may contain conventional film additives such as antioxidants, UV stabilisers, acid scavengers, nucleating agents, anti-blocking agents, slip agents, etc. as well as polymer processing agent (PPA), and so on.
  • additives e.g. conventional film additives, i.e. each layer independently may contain conventional film additives such as antioxidants, UV stabilisers, acid scavengers, nucleating agents, anti-blocking agents, slip agents, etc. as well as polymer processing agent (PPA), and so on.
  • PPA polymer processing agent
  • each one of the layers above comprise the mentioned polyolefin polymers or copolymers in the absence of any other polymer components, particularly of other polyolefins, and, optionally, comprise at least one additive, particularly selected from the ones mentioned above. Additives can be present as part of a masterbatch.
  • the outer layers (A) and (A’) consists of a HDPE.
  • the core layers (B) and (B’) consists of a mLLDPE.
  • the inner blocking layers (C) and (C’) consists of a copolymer selected from the group consisting of EVA, EBA, and a mixture thereof.
  • the layer A amounts less than a 60 wt.% of the total weigh of layers A, B and C. This can also be expressed as that layers A and A' amount less than a 60 wt.% of the total weigh of layers A, A', B, B', C, and C. In another embodiment, the layer A amounts less than a 50 wt.% of the total weigh of layers A, B and C. In another embodiment, the layer A amounts less than a 40 wt.% of the total weigh of layers A, B and C. In another embodiment, the layer A amounts less than a 30 wt.% of the total weigh of layers A, B and C.
  • the layer A amounts less than a 20 wt.% of the total weigh of layers A, B and C.
  • the thickness of the layers may conform to 7-15%/25-35%/15-25%/25-35%/7-15%, such as of 10%/30%/20%/30%/10%, wherein the total film thickness is 100% and the amount of blocking inner layer is the sum of two layers (C) and (C’).
  • the blocked blown multilayer MDO film of the invention does not comprise any barrier layer.
  • barrier layer refers to a film layer comprising a barrier polymer such as ethylene vinyl alcohol copolymer (EVOH) or polyamide (PA), known to serve as an oxygen, hydrogen, water vapor, and/or aroma barrier.
  • EVOH ethylene vinyl alcohol copolymer
  • PA polyamide
  • HDPE is a thermoplastic polymer produced by the polymerization of ethylene monomers and optionally longer-chain olefins. It provides heat resistance for the laminate during heat seal.
  • the HDPE has a density from 940 to 970 kg/m 3 such as of 948 kg/m 3 , 955 kg/m 3 , or 958 kg/m 3 .
  • the HDPE has an MFI (according to ISO 1133, 190 °C/2.16 kg) from 0.2 to 1.0 g/10 min, such as of 0.25 g/10 min, 0.23 g/10 min, or of 0.55 g/10 min.
  • the HDPE has a density of 948 kg/m 3 and an MFI of 0.55 g/10 min. In another embodiment, the HDPE has a density of 955 kg/m 3 and a MFI of 0.23 g/10 min. In another embodiment, the HDPE has a a density of 958 kg/m 3 and a MFI of 0.25 g/10 min.
  • HDPE polymers are commercially available, for example, from Repsol Quimica.
  • mLLDPE is a polyethylene produced in a low-pressure polymerisation process using a metallocene catalyst to copolymerise ethylene and alpha-olefins such as butene, hexene or octene.
  • the co-polymerization process produces an mLLDPE polymer having a narrow molecular weight distribution, which in combination with the linear structure, provides significant improvements in optical and mechanical film properties.
  • mLLDPEs are commercially available from, for example, Repsol Quimica.
  • the mLLDPE is a metallocene ethylene-hexene copolymer.
  • the mLLDPE has a density from 914 to 940 kg/m 3 .
  • the mLLDPE has a density from 916 to 933 kg/m 3 (ISO 1183) such as of 918 kg/m 3 , or of 927 kg/m 3 .
  • mLLDPE has a melt flow index (MFI; according to ISO 1133, 190 °C/2.16 kg) of 0.5 to 3 g/10 min. In another embodiment, the mLLDPE has an MFI from 1 to 2 g/10 min. In a particular embodiment, optionally in combination with one or more features of the embodiments defined above, mLLDPE has a density of 918 kg/m 3 and an MFI (according to ISO 1133, 190 °C/2.16 kg) of 1.0 g/10min. In another embodiment, the mLLDPE has a density of 918 kg/m 3 and an MFI of 2.0 g/10 min.
  • MFI melt flow index
  • the mLLDPE has a density of 933 kg/m 3 and an MFI of 1.0 g/10min. In another embodiment the mLLDPE has a density of 916 kg/m 3 and an MFI of 1.4 g/10 min. In another embodiment the mLLDPE has a a density of 927 kg/m 3 and an MFI of 1.0 g/10 min.
  • mLLDPE polymers are commercially available, for example, from Repsol Quimica.
  • EVA is a copolymer of ethylene and vinyl acetate prepared by high pressure radical polymerization.
  • the weight percent of vinyl acetate ( A) usually varies from 3 to 40%, with the remainder being ethylene.
  • EVA copolymers are commercially available from, for example, Repsol Quimica.
  • EVA has a VA content from 7 to 40%.
  • the EVA has a VA content from 13 to 30 wt.%, such as of 7.5 wt.%, 12.5 wt.%, 18 wt.%, 24 wt.%, or 27 wt.%.
  • the EVA has a VA content of 24.
  • EVA has an MFI (according to ISO 1133, 190 °C/2.16 kg) from 0.3 to 7.0 g/10 min. In a particular embodiment, the EVA has an MFI from 0.5 to 7.0 g/10 min. In another particular embodiment, the EVA has an MFI from 0.3-4 g/10 min, such as of 0.7 g/10 min, 2 g/10 min, 3 g/10 min, or 3.5 g/10 min, 4 g/10 min.
  • EVA has a melting point from 70 to 100 °C, such as of 77 °C.
  • the EVA has a VA content of about 24 wt.% and an MFI (ISO 1133) of about 3 g/10 min. In another embodiment, the EVA has a VA content of about 13% by weight and an MFI of 4.0 g/10 min. In another embodiment, the EVA has a VA content of about 18% by weight and an MFI of 0.7 g/10 min. In another embodiment, the EVA has a VA content of about 18% by weight and an MFI of 2.0 g/10 min. In another embodiment, the EVA has a VA content of about 27% by weight and an MFI of 3.5 g/10 min.
  • an EVA copolymer film having a vinyl acetate content of at least 24 wt.% may be film formed to provide a thermoplastic film having a low melting point in the range of about 70-80 °C.
  • EVA polymers are commercially available, for example, from Repsol Quimica.
  • the EVA has a density (ISO 1183) from 925 to 955 kg/m 3 such as of 926 kg/m 3 . In another embodiment the EVA has a density of 931 kg/m 3 . In another embodiment the EVA has a density of 937 kg/m 3 . In another embodiment the EVA has a density of 941 kg/m 3 .
  • the EVA has a Vicat temperature (LINE-EN ISO 306:2015) from 45 to 70 °C. In another embodiment, the EVA has a Vicat temperature from 47 to 62 °C, such as of 49 °C.
  • EBA is a copolymer consisting of ethylene and butyl acrylate prepared by high pressure radical polymerization.
  • the weight percent of butyl acrylate (BA) usually varies from 3 to 40%, with the remainder being ethylene.
  • Such copolymers are commercially available, for instance, from Repsol Quimica.
  • EBA has a BA content from 3 to 30 wt.%.
  • the EBA has a BA content from 8 to 20 wt.% such as of 3 wt.%, 8 wt.%, 12 wt.%, 13 wt.%, or 17 wt.%.
  • the EBA has a BA content of 17 wt.%.
  • the EBA has an MFI (according to ISO 1133, 190 °C/2.16 kg) from about 0.3 g/10 min to about 7.0 g/10 min. In a particular embodiment, the EBA has an MFI from 0.3 to 4 g/10 min, particularly of 1.5 g/10 min.
  • the EBA has a melting point from 85 to 115 °C, such as of 89 °C, 93 °C, 95 °C, 96 °C, 100 °C, 101 °C, 106 °C, or 110 °C. In a particular embodiment, the EBA has a melting point of 95 °C.
  • the EBA has a BA content of about 17 wt.% and an MFI (ISO 1133) of about 1.5 g/10 min. In another embodiment, the EBA has a BA content of about 13% by weight and an MFI of 0.3 g/10 min. In another embodiment, the EBA has a BA content of about 17% by weight and an MFI of 0.4 g/10 min. In another embodiment, the EBA has a BA content of about 27% by weight and an MFI of 3.5 g/10 min.
  • an EBA copolymer film having a butyl acrylate content of at least 24% by weight may be film formed to provide a thermoplastic film having a low melting point in the range of about 80-90 °C.
  • EBA polymers are commercially available, for example, from Repsol Quimica.
  • the EBA has a density (ISO 1183) from 920 to 926 kg/m 3 . In another embodiment the EBA has a density of 923 kg/m 3 . In another embodiment the EBA has a density of 925 kg/m 3 . In another embodiment the EBA has a density of 924 kg/m 3 .
  • EBA has a a Vicat temperature from 50 to 90 °C. In a particular embodiment, the EBA has a Vicat temperature from 60 to 80 °C, particularly of 68 °C.
  • plastomers that can be utilized in films are very low-density copolymers and terpolymers of ethylene with an alpha olefin, and these plastomers are characterized as having a density of about 0.912 g/cm 3 or less and a melting point in the range of about 40- 105 °C.
  • These copolymers typically comprise from 2 to 30 wt.% or from 5 to 25% of the alpha olefin.
  • alpha olefins include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1 -octene, 1 -decene and 1 -dodecene.
  • Particularly useful alpha olefins include 1-butene and 1-hexene.
  • An example of an ethylene terpolymer is ethylene-1 -hexene-1 -butene.
  • low-density ethylene copolymers are obtained by copolymerization of ethylene with an alpha olefin using single-site metallocene catalysts. Such copolymers are available commercially.
  • ABCCBA type film structures can be prepared by first coextruding compositions forming the layers (B), (C) and (A) through a multi-channel tubular, annular or circular die; blowing by blown extrusion into a tubular film to form a bubble; and then, collapsing the formed bubble, e.g. in nip rolls to form said film where layers (C) are contacted inside/inside, i.e. ABC/CBA.
  • the two halves, ABC and CBA are forced together to effectively form a multilayer structure.
  • an ABCCBA film is formed from two identical ABC films laminated together via their (C) layers. In this way, the film thickness is effectively doubled, and the desired initial film thickness achieved.
  • the manufacture of blocked blown film is a well-known process.
  • the blown (co)extrusion can be effected at a temperature in the range 160 °C to 240 °C, and cooled by blowing gas (generally air) at a temperature of 10 to 50 °C.
  • blowing gas generally air
  • the obtained multilayer film is subjected to a subsequent stretching step, wherein the film is stretched in a machine direction. Stretching may be carried out by any conventional technique which are well known to those skilled in the art, for instance, using a conventional MDO line, such as the ones manufactured by Hosokawa Alpine AG in Augsburg/Germany.
  • the MDO film orientation process is divided into four phases: heating, stretching, annealing, and cooling.
  • the first step in the MDO process is preheating, where a film obtained from the blown-film line is fed into the stretching unit and evenly warmed to the desired temperature, utilizing multiple heating rollers.
  • orientation where the film is stretched between a series of rollers that are revolving at different speeds.
  • a monoaxial stretching line the film is drawn between two rollers. The rollers rotate at different speeds.
  • the film thickness is reduced while optical and mechanical properties are improved.
  • the temperature range for orientation can be up to 25 °C, such as from 5 °C to 20 °C, below the VICAT A-level of the (outer) film layer material up to the melting temperature of the (outer) film layer material.
  • the oriented film then enters annealing thermal rollers, which allow stress relaxation by holding the film at an elevated temperature for a period of time and the film’s new properties are locked in and made permanent.
  • the annealing temperature is preferably within the same temperature range as used for stretching or slightly below (e.g. 10 to 20 °C below), with room temperature being the lower limit.
  • the film is cooled through cooling rollers to room temperature.
  • the ratio of the film thickness before and after orientation is called stretch ratio.
  • the stretch ratio varies depending on many factors including the desired film thickness, film properties and multilayer film structures.
  • the second aspect of the invention relates to a process for preparing a multilayer MDO film as defined above, the process comprising a) coextruding a composition comprising a high density polyethylene (HDPE); a composition comprising a metallocene linear low density polyethylene (mLLDPE); and a composition comprising a copolymer selected from the group consisting of ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), and a mixture thereof; to form a tubular multilayer film structure comprising an outer layer (A) comprising HDPE, a core layer (B) comprising mLLDPE, and an inner blocking layer (C) comprising EVA, EBA, or a mixture thereof, b) blowing by blown extrusion into the multilayer tubular film to form a bubble; c) collapsing the formed bubble to form a multilayer film where layers (C) are contacted; d) subjecting the multilayer film to a subsequent stretching step, where
  • HDPE high
  • the film is oriented in the machine direction at a stretch ratio greater than 1 :3 and less than 1:10, particularly of 1 :4, 1:5, 1 :6, or 1 :7.
  • a stretch ratio of, for instance, 1 :4 means that the film has been stretched 4 times up its original length in the machine direction, i.e. "1" represents the original length of the film and "4" denotes that it has been stretched to 4 times that original length.
  • the multilayer MDO film of the invention can have a thickness from 15 to 60 pm, particularly from 20 to 55 pm, more particularly of 25 to 50 pm.
  • the machine direction oriented films according to the invention show advantageous and surprising properties.
  • the multilayer MDO films of the invention have a higher gloss, while having similar or even better haze values, and higher tensile stress and strain at break in transverse direction (TD) compared to films comprising a plastomer as an inner blocking layer.
  • the multilayer MDO film of the invention has a gloss (60°) according to ASTM D2457-21 for a film thickness of 50 pm of at least 130, particularly of at least 134, more particularly of at least 135, or even more particularly of at least 137, preferably of at least 140.
  • the multilayer MDO film of the invention has a haze according to ASTM D-1003-21 equal to or lower than 4% for a film thickness of 50 pm.
  • the multilayer MDO film of the invention has a tensile stress at break TD according to LINE-EN ISO 527-3:2019 of at least 40 MPa, such as of 44 MPa or 45 MPa for a film thickness of 50 pm.
  • the multilayer MDO film of the invention has a tensile strain at break TD according to LINE-EN ISO 527-3:2019 of at least 600%, preferably of at least 620%, such as of 622% or 626%, for a film thickness of 50 pm.
  • an inherent result of the method of the invention is that it allows obtaining a multilayer MDO film having improved properties compared with the ones of the prior art. Therefore, a multilayer MDO film obtainable by the method defined above is also part of the invention.
  • the first aspect of the invention can also be defined as a blocked blown multilayer MDO film comprising a structure comprising:
  • a second outer layer (A’) wherein the first and second inner blocking layers are fused and form one layer, and wherein the layers (A) and (A’) have the same composition and comprise a high-density polyethylene (HDPE), the layers (B) and (B’) have the same composition and comprise a metallocene linear low density polyethylene (mLLDPE), and the layers (C) and (C’) have the same composition and comprise a copolymer selected from the group consisting of ethylene vinyl acetate (EVA), ethylene butyl acrylate (EBA), and a mixture thereof; wherein the blocked blown multilayer MDO film is obtainable by a process comprising a) coextruding at least: a composition comprising a high density polyethylene (HDPE); a composition comprising a metallocene linear low density polyethylene (mLLDPE); and a composition comprising a copolymer selected from the group consisting of ethylene vinyl acetate (EVA), ethylene butyl acryl
  • coextrusion is carried out with an coextrusion systems comprising a tubular-shaped extruder for each polymer composition.
  • coextrusion systems usually have from two to nine extruders an produce from three- to seventeen-layer films.
  • a symmetrical five-layer [ABCBA] structure film from the three different polymer streams can be produced; with a four-extruder system, a symmetrical seven-layer [ABCDCBA] structure can be produced; and so on.
  • another aspect of the invention relates to the use of the multilayer MDO film as defined above in packaging, in particular in a form fill and seal packaging process, that is a process wherein a package is formed, filled with a product, and then seal.
  • the film is especially suitable for use in grocery sacks, institutional and consumer can liners, merchandise bags, shipping sacks, food packaging films, multi-wall bag liners, produce bags, shrink films, label films, tissue overwrap, deli wraps and shrink wraps.
  • Vinyl acetate (VA) and butyl acrylate (BA) contents were measured by Fourier transform infrared (FTIR) spectroscopy using both molded plates and film, applying a thickness correction in the latter case.
  • the measurement of the vinyl acetate content is based on the infrared absorption of the bands 1020 cm -1 (for contents of 0.5 to 5% VA) and 609 cm -1 and 3456 cm -1 (for contents of 5 to 40%. %VA).
  • the infrared absorption of the bands 1465 cm -1 , 2019 cm -1 or 4632-3731 cm -1 can be taken as the thickness correction band.
  • the melt flow index (MFI) was measured according to LINE-EN ISO 1133-1 :2012.
  • the density was measured according to LINE-EN ISO 1183-1 :2019.
  • the melting temperature was measured by differential scanning calorimetry (DSC) using a compression molded film or plate and heating the oven at a rate of 10 °C/min to a temperature high enough to eliminate previous thermal history, approximately 30 °C above melting; it is kept in isotherm for 5 minutes and another temperature scan is made at 10 °C/min, recording the heating curve until the transition has taken place.
  • the Vicat softening temperature was measured according to LINE-EN ISO 306:2015.
  • - ULTRACLEAN 210 (formerly called 1810F) is a metallocene linear low density polyethylenes (mLLDPE) having a density of 918 kg/m 3 and an MFI of 1.0 g/10 min;
  • mLLDPE metallocene linear low density polyethylenes
  • - ULTRACLEAN 230 (formerly called 331 OF) is a metallocene linear low density polyethylenes (mLLDPE) having a density of 933 kg/m 3 and an MFI of 1.0 g/10 min;
  • mLLDPE metallocene linear low density polyethylenes
  • - ULTRACLEAN 110 (formerly called R4805EP) is a high-density polyethylene (HDPE) of a density of 948 kg/m 3 and an MFI of 0.55 g/10 min;
  • HDPE high-density polyethylene
  • - ULTRACLEAN 410 (formerly called P2430C) is an ethylene vinyl acetate (EVA) copolymer with a VA content of 24%, a melting temperature of 77 °C, MFI of 3, density of 944 kg/m 3 , and a Vicat temperature of 49 °C;
  • EVA ethylene vinyl acetate
  • E1715 is an ethylene butyl acrylate (EBA) copolymer with a 17% BA content, a melting temperature of 95 °C, MFI of 1.5 g/10 min, density of 926 kg/m 3 , a Vicat temperature of 68 °C; and
  • EBA ethylene butyl acrylate
  • - Dow AFFINITY EG 8100G is a mLLDPE type plastomer with C8 comonomer with a melting temperature of 55 °C, an MFI (190 °C/2.16 kg) of 1.0 g/10 min, a density of 870 kg/m 3 , a Vicat temperature of 46 °C.
  • This grade is considered a reference grade for the processing of collapsed MDO and, therefore, a relevant benchmark, reason why it was used in the comparative examples.
  • Three co-extruded tube films with a thickness of 150 pm and a film thickness distribution (%) of an ABC layer film of 20%/60%/20% of the total film thickness (100%) were manufactured.
  • the layer distribution consisted of an HDPE outer layer for thermal resistance (A), an mLLDPE core layer for mechanical properties (B), and an inner layer of a blocking material which was a low melt temperature PE grade selected from EVA, EBA, and plastomer (C).
  • the final film formed from two identical ABC type films had 6 layers, ABCCBA, wherein the two inner C layers had merged to become one.
  • Example 1 the pressure for ULTRACLEAN 410 was low, and this grade had the highest MFI (3 g/10 min). Furthermore, the rpm was similar for both A and C layer.
  • the blocked blown films were processed and stretched on a MDO line manufactured by Hosokawa Alpine AG in Augsburg/Germany.
  • the MDO line had four main heating rollers (H1-H4) with nip rollers to ensure good contact, followed by two rollers (S5, S6) for one-step stretching with nip rollers to fix the stretch ratio.
  • the film was thereafter annealed and relaxed on three semi-heated rollers (A7-A9) before the two final rollers (C10, C11) for cooling and slitting and winding of the films.
  • the films were able to be processed without break up until a stretch ratio of 1 :7.
  • the MDO processing showed that the three samples were able to be processed in a similar way and at similar processing temperatures. All the samples were able to be stretched to a ratio of 7:1 and there was film break at 8:1 , which showed that the stretchability and process behavior was very similar.
  • Example 1 and Example 2 with EVA and EBA copolymer as blocking material, respectively, had less neck-in than Comparative Examples 1 and 2, with a plastomer as blocking material.
  • a reduced neck-in mean that less trimming is required after orientation, what results in an improved production economy.
  • MD machine direction
  • TD transverse direction
  • MD machine direction
  • TD transverse direction
  • Example 1 and 2 had higher tensile modulus in TD and MD than comparative Example
  • Example 3 had higher tensile modulus in TD and MD than comparative Example 2. The higher tensile modulus provides higher stiffness.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Laminated Bodies (AREA)

Abstract

L'invention concerne un film MDO multicouche soufflé bloqué comprenant une structure comprenant (i) une première couche externe (A), (ii) une première couche centrale (B), (iii) une première couche de blocage interne (C), (iv) une seconde couche de blocage interne (C'), (v) une seconde couche centrale (B'), et (vi) une seconde couche externe (A'), les première et seconde couches de blocage internes étant fusionnées et formant une couche, et les couches (A) et (A') ayant la même composition et comprenant un HDPE, les couches (B) et (B') ayant la même composition et comprenant un mLLDPE, et les couches (C) et (C') ayant la même composition et comprenant un copolymère choisi parmi EVA, EBA et un mélange de ceux-ci. L'invention concerne également un procédé pour sa préparation, son utilisation dans des applications d'emballage, et un article emballé à l'aide du film.
PCT/EP2023/069674 2022-07-15 2023-07-14 Film multicouche à orientation uniaxiale WO2024013378A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP22382676 2022-07-15
EP22382676.9 2022-07-15

Publications (1)

Publication Number Publication Date
WO2024013378A1 true WO2024013378A1 (fr) 2024-01-18

Family

ID=83081564

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2023/069674 WO2024013378A1 (fr) 2022-07-15 2023-07-14 Film multicouche à orientation uniaxiale

Country Status (1)

Country Link
WO (1) WO2024013378A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017055174A1 (fr) * 2015-10-02 2017-04-06 Borealis Ag Structures coextrudées pour films rétractables de regroupement
EP3390049A1 (fr) * 2015-12-15 2018-10-24 Borealis AG Structure de film laminé à base de polyéthylène à propriétés barrières
US20200122439A1 (en) * 2017-05-05 2020-04-23 Constantia Pirk Gmbh & Co. Kg Recyclable, Easily Tearable Packaging Laminate Having A Good Barrier Effect And Method For Production Thereof
US20220152906A1 (en) * 2019-02-13 2022-05-19 Exxonmobil Chemical Patents Inc. Oriented Multilayer Polyethylene Films and Laminates Thereof
US20220162405A1 (en) * 2019-04-04 2022-05-26 Amcor Flexibles North America, Inc. Recyclable film for thermoforming

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017055174A1 (fr) * 2015-10-02 2017-04-06 Borealis Ag Structures coextrudées pour films rétractables de regroupement
EP3390049A1 (fr) * 2015-12-15 2018-10-24 Borealis AG Structure de film laminé à base de polyéthylène à propriétés barrières
US20200122439A1 (en) * 2017-05-05 2020-04-23 Constantia Pirk Gmbh & Co. Kg Recyclable, Easily Tearable Packaging Laminate Having A Good Barrier Effect And Method For Production Thereof
US20220152906A1 (en) * 2019-02-13 2022-05-19 Exxonmobil Chemical Patents Inc. Oriented Multilayer Polyethylene Films and Laminates Thereof
US20220162405A1 (en) * 2019-04-04 2022-05-26 Amcor Flexibles North America, Inc. Recyclable film for thermoforming

Similar Documents

Publication Publication Date Title
US11535012B2 (en) Polyethylene based laminated film structure with barrier properties
EP3261838B1 (fr) Structure de film stratifié uniquement à base de polyéthylène
EP2875948B1 (fr) Film orienté dans le sens machine
US8637607B2 (en) Polyethylene blends and films
US20060177641A1 (en) Multilayer polyethylene thin films
EP2653392A1 (fr) Films d'emballage rétractables
US10792899B2 (en) Multilayer films and laminates and articles comprising the same
US8034461B2 (en) Preparation of multilayer polyethylene thin films
US7504141B2 (en) Shrink film
TWI821865B (zh) 用於永續性包裝的高剛性定向聚乙烯膜、包括該膜的層合物、該膜或該層合物的用途及食品包裝
WO2002074854A2 (fr) Melanges de resines de polyethylene et de resines aliphatiques hydrogenees de faible poids moleculaire
US20240092066A1 (en) Multi-layered polyethylene films oriented in the machine direction and articles comprising the same
AU2003248954B2 (en) Schrink film
WO2024013378A1 (fr) Film multicouche à orientation uniaxiale
EP4000924A1 (fr) Structures de film en polyéthylène pour des films rétractables de regroupement plus sûrs
WO2023155081A1 (fr) Stratifiés souples à performance d'étanchéité supérieure
EP4201674A1 (fr) Structure de film multi-couche comprenant un terpolymère d'éthylène multimodal et ldpe recyclé pour films rétractable de collation
EP4183572A1 (fr) Stratifiés de polyéthylène pour emballage durable
CN116669945A (zh) 用于更安全的整理收缩膜的聚乙烯膜结构
WO2024083816A1 (fr) Film de polyéthylène orienté hautement rigide pour emballage durable
WO2023086825A1 (fr) Films de polyéthylène à orientation biaxiale à rigidité élevée

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23741719

Country of ref document: EP

Kind code of ref document: A1