A biodegradable laminate for aseptic packaging

Abstract

A biodegradable laminate (1) comprising a base board (2) with a first side (2a) and a second side (2b). The base board comprises 0-30 wt% filler, the laminate further comprises a PHA, dispersion coated, primer layer (3) arranged on the second side of the base board, wherein the primer layer has a coat weight of 0.5-15 g / m2, the primer layer comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH, P(3HB4HB), other co-polymers of PHB, other homopolymers such as PHO, PHH, P3HP, and combinations thereof; a vacuum deposited layer (4) coated on the primer layer which vacuum deposited layer has a thickness of 20-500 nm, the vacuum deposited layer comprises material selected from the group consisting of aluminum, magnesium, silicon, copper, aluminum oxides, magnesium oxides, silicon oxides and combinations thereof; and at least one extrusion coated heat-sealable PHA layer (5, 6) which is coated on the first side of the base board and / or on the vacuum deposited layer.

Description

[0001] A BIODEGRADABLE LAMINATE FOR ASEPTIC PACKAGING

[0002] TECHNICAL FIELD

[0003] A biodegradable laminate for aseptic packaging, said laminate comprising a base board with a first side and a second side .

[0004] BACKGROUND - PROBLEM

[0005] Packaging materials for food and liquids including aseptic packages in ambient distribution, chilled distribution, or hot filled products , play an important role in the protection of the packed content . The packages should not only prolong shelf time of the packed content , but also offer a laminate or packaging structure which enables reuse and recycling .

[0006] Fibre-based materials represents a renewable source and sustainable alternative to fossil based or plastic based packaging . Fibre-based substrates such as paper or paperboard are usually extrusion or dispersion coated and / or laminated with thin polymer layers to provide barrier properties as for providing other functions such as sealing properties .

[0007] For more demanding applications , aluminium foil has been used in the laminates to provide barrier properties against particularly aroma, light , and water vapor and gases .

[0008] To offer the market more sustainable solutions , there is a need to find aluminium foil free solution, but also laminate structure which are more sustainable in terms of recycling, reuse and / or compostability . OBJECT OF THE INVENTION

[0009] An obj ect with the invention is to provide a laminate with good barrier properties and which is recyclable and reusable .

[0010] Another obj ect is to provide a laminate for which recyclability is improved and especially pre- and postconsumer recyclability .

[0011] SUMMARY OF THE INVENTION

[0012] In accordance with the invention the base board is biodegradable and comprises 0-30 wt% filler, the laminate further comprises :

[0013] - a PHA, dispersion coated, primer layer arranged on the second side of the base board, wherein the primer layer has a coat weight of 0 . 5-15 g / m2, preferably 1-10 g / m2, the primer layer comprises a PHA type selected from the group consisting of PHB , PHBV, PHBH, P ( 3HB4HB ) , other copolymers of PHB , other homopolymers such as PHO , PHH, P3HP , and combinations thereof ;

[0014] - a vacuum deposited layer coated on the primer layer which vacuum deposited layer has a thickness of 20-500 nm, preferably 20-200 nm, the vacuum deposited layer comprises material selected from the group consisting of aluminum, magnesium, silicon, copper , aluminum oxides , magnesium oxides , silicon oxides and combinations thereof , preferably aluminum oxides ; and

[0015] - at least one extrusion coated heat-sealable PHA layer which is coated on the first side of the base board and / or the vacuum deposited layer , wherein the extrusion coated layer has a coat weight of 5-25 g / m2, the layer comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH , P ( 3HB4HB ) , other co-polymers of PHB, other homopolymers such as PHO , PHH, P3HP , and combinations thereof .

[0016] DEFINITIONS

[0017] Polyhydroxyalkanoate ( PHA)

[0018] PHAs or polyhydroxyalkanoates shall in the context of the patent application refer to a biopolyester family that has a variety of structures and that are synthesized by a broad range of natural and genetically engineered bacteria and genetically engineered plant crops . PHAs can be synthesized in a wide range of environmental conditions and media by 30% of bacteria that live in soil . The bacteria produce PHAs by fermentation of sugar or lipids with the aim to store carbon and energy . Examples of bacterial strains that can produce PHAs include Alcaligenes eutrophus , Alcaligenes latus , Azotobacter , Aeromonas , Comamonas , Pseudomonads , and other genetically engineered organisms , such as genetically engineered microbes like Pseudomonas , Ralstonia and Escherichia coll . In general , PHAs are formed by enzymatic polymerization of one or more monomer units inside living bacteria or plant cell . Over 100 different types of monomers have been identified and incorporated into the PHA polymers , including 3-hydroxybutanoic acid and 3-hydroxypentanoic acid . PHAs can be classified into homopolymers , such as the well-known polyhydroxybutyrate ( PHB ) , or co-polymers like poly ( 3-hydroxybutyrate-co-3-hydroxyvalerate ) ( PHBV) . Additionally, depending on the size of the carbon chain, they are further categorized into short chain length ( SCL ) , medium chain length (MCL ) or long chain length (LCL ) PHAs . Since they constitute a broad family of biodegradable polymers , PHAs display very versatile properties that can benefit many different industrial applications , including cosmetics , biomedicine and packaging , to name a few .

[0019] DESCRIPTION OF THE INVENTION

[0020] In the following, the invention will be described further with reference to Figures 1-2 . Note that the drawings in Figures 1-2 are schematical and not to scale .

[0021] Figure 1 shows a first embodiment of the inventive laminate .

[0022] Figure 2 shows a second embodiment of the inventive laminate .

[0023] Laminate

[0024] The inventive is a biodegradable laminate 1 suitable for aseptic packaging, liquid packaging, non-aseptic packaging, cups , lids , trays , etc .

[0025] Base board

[0026] The laminate 1 comprising a base board 2 with a first side 2a and a second side 2b . The base board 2 is biodegradable and comprises 0-30 wt% filler . The base board 2 is both biodegradable and compostable .

[0027] The base board 2 base board comprises delignified and / or bleached CTMP or HT-CTMP . Which CTMP or HT-CTMP has a low kappa number such as below 60 , preferably below 50 and most preferred below 40 according to ISO 302 : 2015 or TAPPI / ANSI T236 . The delignified and / or bleached CTMP or HT-CTMP (High temperature CTMP) can be derived from hardwood or softwood or be a mixture thereof.

[0028] The amount of the delignified and / or bleached CTMP or HT- CTMP in the board is preferably at least 20 wt%, more preferred at least 30 wt% such as 30-90 wt% based on the total fibre content. Also, the delignified or bleached CTMP or HT-CTMP is preferably used in the middle ply for creating a bulky layer.

[0029] Preferably, the base board 2 is a 3-ply paperboard comprising a first ply forming a top ply, a second ply forming a back ply and a third ply forming a middle ply.

[0030] The middle ply having a high bulk with a grammage in the range 30-250 gsm and density less than 850 kg / m3, preferably less than 750 kg / m3and most preferred less than 650 kg / m3.

[0031] At least one of the base board plies have 0-100% recycled fibres, which is defined as pre- or post-consumer waste or recycled pulp.

[0032] The base board 2 is repulpable according to PTS RH 021 / 97 test method for Category II products standard (PTS reject <20% and preferably <15%) .

[0033] The base board 2 is recyclable according to DIN EN 13430:2004, biodegradable according to EN 13432:2000.

[0034] The base board 2 is compostable according to at least one of EN 13432:2000, ASTM D6868-21 and AS-4736-2006. Primer layer

[0035] The laminate further comprises a PHA, dispersion coated, primer layer 3 which is arranged on the second side 2b of the base board 2. The primer layer has a coat weight of 0.5-15 g / m2, preferably 1-10 g / m2. The primer layer can be applied as one layer or even two or three layers, preferably with interim drying.

[0036] The primer layer 3 comprises a comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH, P(3HB4HB) , other co-polymers of PHB, other homopolymers such as PHO, PHH, P3HP, and combinations thereof.

[0037] The crystallinity of the used PHA in dispersion coated primer layer 3 is 10-45% according to ASTM E794-06 (2018) .

[0038] The PHA, used in the primer layer 3, has a melting point in the range of 100-170°C, preferably 120-160°C determined by differential scanning calorimetry according to standard ASTM D3418.

[0039] After the PHA primer layer 3 has been coated the second side 2b of the base board 2, the second side 2b has a surface roughness, Parker Print-Surf (PPS) , in the range 0.5-4 pm, according to ISO 8791-4, measured with a clamping pressure of 1.0 MPa.

[0040] The PHA particles in the dispersion coating composition have a median particle size (D50) below 15 pm, preferably below 12 pm and most preferred in the range 0.5-11 pm or 0.8-8 pm. The particle size distribution may be multimodal or unimodal. The particle sizes and particle size distributions are determined by a laser diffraction method using Mastersizer 3000 according to ISO 13320:2009.

[0041] Preferably the dispersion coated PHA primer coating, comprises less than 10 pinholes / m2, preferably less than 8 pinholes / m2, and more preferably less than 2 pinholes / m2, as measured according to standard EN13676: 2001.

[0042] The PHA primer layer 3 is thermal stable, i.e. it has a relative high melting temperature (Tm) . The measured melting temperature (Tm) , according to ISO 11357-3:2018, is in the range 50-180 °C, preferably 60-150 °C and most preferred 100-140 °C.

[0043] Moreover, co-polymers of PHB comprising 0-40 mol%, preferably 2-30 mol%, more preferably 5-25 mol% of specific functional group (e.g., valerate, hexanoate) or change in the backbone (e.g. , alternating 3HB and 4HB) for flexibility. Whereas homopolymers other than PHB are flexible by nature.

[0044] The primer layer 3 comprises stabilizers (e.g., PVOH, EVOH, PVAc, cellulose derivates, polysaccharides) , fillers (e.g., clays, calcium carbonate, talc, kaolinite, montmorillonite, bentonite, silica, chitin, titanium dioxide, nano clay, nanocellulose, or mixtures thereof. ) , nucleating agents (e.g. , talc, mica, boron nitride, crystalline nanocellulose, sodium benzoate, calcium carbonate, silica, ionomers, clay, diacetal, titanium oxide, dibenzylidene sorbitol, benzophenone, diacetal benzoate, lithium benzoate, sodium benzoate, potassium benzoate, thymine, sodium organophosphate) .

[0045] The PHA, dispersion coated, primer layer 3 may also comprise: Surfactants: cationic, anionic, non-ionic, and amphoteric surfactants - e.g., polysorbates, aromatic polyethylene oxides, sorbitan derivatives, block copolymers of poly ( ethylene oxide) and poly (propylene oxide) , poly(glycol ethers) , alkyl sulfates, alkyl phosphates, stearates saponins.

[0046] Defoamers: polyether siloxanes, silicones, stereates, glycols, vegetable oils.

[0047] Plasticizers: glycerol, sorbitol, mannitol, xylitol, ethylene glycol, fatty acids, monosaccharides, urea, vegetable oils.

[0048] The solid content of PHA dispersion is >20 wt%, preferably >35 wt% and most preferred 45-60 wt% .

[0049] According to the TAPPI test method T 701 pm-01, the dispersion has a water retention value below 150 g / m2, preferably less than 140 g / m2and most preferred 20-130 g / m2.

[0050] The content of PHA in the primer layer 3 is at least 40%.

[0051] The primer layer 3 may contain pigments / f illers up to 40 wt%, which in turn have a great impact, i.e. better blocking effect on UV transparency and light transmission . The primer layer 3 has a WVTR value less than 100 , preferably less than 75 and most preferred less than 50 g / m2 / day at 23 ° C / 50% RH according to ASTM F1249-20 .

[0052] Optionally, at least 5 wt% of the PHA content in the primer layer 3 is recycled PHA, wherein up to 20 wt% of the PHA is pre- or post-consumer recycled PHA (mechanical or chemical recycling ) .

[0053] The primer layer 3 also gives a barrier effect, especially improved KIT value , which is surprising . It also reduces MOAH / MOSH migration and enable use of recycled fibre in board . Additionally, the primer layer 3 also prevents moisture to escape from the base board 2 .

[0054] Vacuum deposited layer

[0055] The laminate also comprises a vacuum deposited layer 4 , which is coated on the primer layer 3 . The vacuum deposited layer 4 has a thickness of 20-500 nm, preferably 20-200 nm.

[0056] The vacuum deposited layer 4 comprises material selected from the group consisting of aluminum, magnesium, silicon, copper , aluminum oxides , magnesium oxides , silicon oxides and combinations thereof , preferably aluminum oxides .

[0057] Example of technologies for applying the thin vacuum deposition layer : plasma enhanced chemical vapor deposition ( PECVD) , atomic layer deposition (ALD) , conventional metallization, CCVD or PECVD, or as is alumina and / or silica layer is deposited via CCVD or PECVD at open atmosphere . Other methods are sputtering, chemical vapor deposition (CVD) , combustion chemical vapor deposition ( CCVD) , physical vapor deposition ( PVD) , plasma enhanced chemical vapor depos ition ( PECVD ) , vacuum deposition, flame deposition, and flame hydrolysis deposition .

[0058] Extrusion coated heat-sealable layer Moreover , the laminate comprises at least one extrusion coated heat-sealable PHA layer 5 , 6 which is coated on the first side 2a of the base board 2 and / or on the vacuum deposited layer 4 . Each extrusion coated layer 5 , 6 has a coat weight of 5-25 g / m2.

[0059] The layer comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH, P ( 3HB4HB ) , other copolymers of PHB , other homopolymers such as PHO , PHH, P3HP , and combinations thereof .

[0060] Optionally, at least 5 wt% of the PHA content in the extrusion coated layer 5 , 6 is recycled PHA, wherein up to 20 wt% of the PHA is pre- or post-consumer recycled PHA (mechanical or chemical recycling ) .

[0061] Figure 1 discloses a first embodiment wherein the PHA dispersion coated layer 4 is coated directly on the second side 2b of the base board .

[0062] Figure 2 discloses a second embodiment wherein the laminate further comprises a pre-coating layer 7 which is arranged between the second side 2b of the base board 2 and the PHA dispersion coated layer 4 . The pre-coating layer 7 has a grammage of 1-8 gsm .

[0063] The pre-coating layer 7 can be applied single , double or triple coating .

[0064] In a first embodiment the pre-coating layer 7 is PVOH or Polysaccharide such as starch or CMC .

[0065] In a second embodiment the pre-coating layer 7 is nanocrystalline cellulose , microcrystalline cellulose or microf ibrillated cellulose .

[0066] Pre-coating layer

[0067] In a third embodiment the pre-coating layer ( 7 ) is nanocrystalline cellulose , microcrystalline cellulose or microf ibrillated cellulose in combination with either PVOH or Polysaccharide .

[0068] The pre-coating layer 7 prevents or at least reduces the migration of MOSH ( (Mineral Oil Saturated Hydrocarbons ) and MOAH (Mineral Oil Aromatic Hydrocarbons ) from the packaging material into food or other products .

[0069] An advantage with the innovative structure is that it passes the organoleptic test according to the Robinson test DIN EN 1230-1 and DIN EN 1230-2 such that the value is below 0 . 5 .

[0070] In the foregoing, the invention has been described on some specific embodiments . However, a skilled person realizes that other embodiments and variants are possible within the scope of the following claims .

Claims

C L A I M S1. A biodegradable laminate (1) for aseptic packaging, said laminate comprising a base board (2) with a first side (2a) and a second side (2b) , characterized in that the base board is biodegradable and comprises 0-30 wt% filler, the laminate further comprises:- a PHA, dispersion coated, primer layer (3) arranged on the second side (2b) of the base board (2) , wherein the primer layer (3) has a coat weight of 0.5-15 g / m2, preferably 1-10 g / m2, the primer layer (3) comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH, P(3HB4HB) , other co-polymers of PHB, other homopolymers such as PHO, PHH, P3HP, and combinations thereof;- a vacuum deposited layer (4) coated on the primer layer (3) which vacuum deposited layer (4) has a thickness of 20-500 nm, preferably 20-200 nm, the vacuum deposited layer (4) comprises material selected from the group consisting of aluminum, magnesium, silicon, copper, aluminum oxides, magnesium oxides, silicon oxides and combinations thereof, preferably aluminum oxides; and- at least one extrusion coated heat-sealable PHA layer (5, 6) which is coated on the first side (2a) of the base board (2) and / or on the vacuum deposited layer (4) , wherein the extrusion coated layer (5, 6) has a coat weight of 5-25 g / m2, the layer comprises a PHA type selected from the group consisting of PHB, PHBV, PHBH, P(3HB4HB) , other co-polymers of PHB, other homopolymers such as PHO, PHH, P3HP, and combinations thereof.

2. Laminate according to claim 1, wherein the PHA dispersion coated layer (3) is coated directly on the second side (2b) of the base board (2) .

3. Laminate according to claim 1, wherein the laminate further comprises pre-coating layer (7) , which precoating layer is arranged between the second side (2b) of the base board (2) and the PHA dispersion coated layer (3) .

4. Laminate according to claim 3, wherein the pre-coating layer (7) is PVOH or Polysaccharide such as starch or CMC.

5. Laminate according to claim 3, wherein the precoating layer (7) is nanocrystalline cellulose, microcrystalline cellulose or microf ibrillated cellulose.

6. Laminate according to claim 3, wherein the pre-coating layer (7) is nanocrystalline cellulose, microcrystalline cellulose or microf ibrillated cellulose in combination with either PVOH or Polysaccharide.

7. Laminate according to any one of claims 3-6, wherein the pre-coating layer (7) has a grammage of 1-8 gsm.

8. Laminate according to any preceding claim, wherein the crystallinity of PHA in the PHA dispersion coated layer (3) is 10-45% according to ASTM E794-06 (2018) .

9. Laminate according to any preceding claim, wherein the PHA, used in the PHA dispersion coated layer (3) has a melting point in the range of 100-170°C, preferably120-160°C determined by differential scanning calorimetry according to standard ASTM D3418.

10. Laminate according to any preceding claim, wherein the PHA, dispersion coated, primer layer (3) has a coating surface roughness, parker Print- Surf (PPS) in the range 0.5-4 pm according to ISO 8791-4 measured with a clamping pressure of 1.0 MPa.

11. Laminate according to any of claims 1-10, wherein the PHA particles in the dispersion coating composition have a median particle size (D50) below 15 pm, preferably below 12 pm and most preferred in the range 0.5-11 pm or 0.8-8 pm.

12. Laminate according to claim 11, wherein the particle size distribution is multimodal or unimodal .

13. Laminate according to any of claims 10-11, wherein the particle sizes and particle size distributions are determined by a laser diffraction method using Mastersizer 3000 according to ISO 13320:2009.

14. Laminate according to any preceding claim, wherein the crystallinity of PHA in the extrusion coated heat- sealable PHA layer (5, 6) is 30-70% according to ASTM E794-06 (2018) .

15. Laminate according to any preceding claim, wherein at least 5 wt% of the PHA content, in the dispersion coated layer (4) and / or the extrusion coated layer (5, 6) , is recycled PHA.

16. Laminate according to claim 15, wherein up to 20 wt% of the PHA is pre- or post-consumer recycled PHA.

17. Laminate according to any preceding claim, wherein the base board 2 is a 3-ply paperboard comprising a first ply forming a top ply, a second ply forming a back ply and a third ply forming a middle ply, which middle having a high bulk with a grammage in the range 30-250 gsm and density less than 850 kg / m3' preferably less than 750 kg / m3and most preferred less than 650 kg / m3.

18. Laminate according to any preceding claim, wherein the base board (2) is repulpable according to PTS RH 021 / 97 test method for Category II products standard (PTS reject <20% and preferably <15%) , recyclable according to DIN EN 13430:2004, biodegradable according to EN 13432:2000 and compostable according to at least one of EN 13432:2000, ASTM D6868-21 and AS-4736-2006.

19. Laminate according to claim 18, wherein the biodegradable and compostable base board comprises delignified or bleached CTMP which CTMP has a low kappa number such as below 60, preferably below 50 and most preferred below 40 according to ISO 302:2015 or TAPPI / ANSI T236.

20. Laminate according to any preceding claim, wherein at least one ply of the base board (2) comprises 0-100% of recycled fibres.

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