WO2025114062A1

WO2025114062A1 - Paper-based barrier laminate

Info

Publication number: WO2025114062A1
Application number: PCT/EP2024/082703
Authority: WO
Inventors: Joshua Russell BOOTH; Maria Fernanda Jimenez Solomon
Original assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Current assignee: Unilever Global IP Ltd; Unilever IP Holdings BV; Conopco Inc
Priority date: 2023-11-27
Filing date: 2024-11-18
Publication date: 2025-06-05
Anticipated expiration: 2026-05-27

Abstract

A flexible barrier laminate comprising a paper layer, a parylene layer and a sealing layer.

Description

PAPER-BASED BARRIER LAMINATE

The present invention relates to a flexible barrier laminate comprising paper and parylene. It further relates to a process to provide a flexible barrier laminate comprising paper and parylene. The invention further relates to the use of parylene to provide barrier property in flexible paperbased barrier laminate.

Background

Consumer goods, such for example food products including frozen confectionary, liquid and dry bouillon, soup, sauce products; savoury snack products, instant meals, but also soap bars, laundry detergent, etc, are typically packaged before they are used by the consumer. Besides marketing purposes, depending on the consumer product, the packaging provides structure to the product and/or keeps it in place, and protects the product against external influences that may affect the quality, including light, water, and air, which results in the presence of several barrier materials that are included in a packaging material, depending on the product need. In addition, the consumer product itself may affect the packaging material, because of for example ingredients like water, fat, salts, corrosive alkaloids etc., and the packaging material typically may need to be resistant against such influences to ensure proper protection of the packaged product. For this reason, packaging materials for consumer products typically are laminates of different materials, such as different polymer materials (plastics), and metal, such as aluminum.

With increasing emphasis on environmentally friendlier packaging materials or on the recyclability of packaging materials, the use of paper has gained interest. The paper obviously is typically thin, to allow high flexibility, for example during packaging processes and in packaging lines. Although paper provides to a certain extent texture to a packaged consumer product, its barrier properties for external influences such as water are limited, and it can be easily damaged upon contact with fat or water from the packaged consumer product. Laminates comprising paper and polymers are found as a solution. To ensure recyclability of the material, for technical and in many countries also legal reasons, the polymer layer should be less than 20% of the total grammage of the packaging material, and in most countries even less than 10%. Laminating paper becomes a challenge, especially for paper that is suitable for continuous packaging lines, since polymer and metal lamination at a grammage of less than 20% or even less than 10% of the total material width easily results in cracks of the laminate layers, resulting in protection risks for the consumer product. Without willing to be bound to theory, the relatively rough surface of paper contributes to this risk. Other coating procedures rely on dispersion coating wherein the coating material is dispersed in solvent followed by evaporation. Dispersion coatings, however, are typically thin and of low grammage and, especially when used alone, typically do not to provide the barrier property required for consumer goods.

A need therefore is recognized for a paper-based packaging material, that overcomes the above-mentioned complications, at least to some extent. In particular, there is a need for a paper-based flexible packaging material, which provides barrier properties to several external and internal influences on a consumer product to be packaged and on the paper of the packaging material, respectively, and which preferably meets the criteria to be recyclable.

Summary of the invention

Surprisingly, this need could be met by the present invention, which in a first aspect relates to a flexible barrier laminate (1) comprising:

• A paper layer (2),

• A first parylene layer (3),

• A sealing layer (4).

In a second aspect, the invention relates to a process to provide the barrier laminate (1) of the invention, wherein the process comprises the steps of: a) Providing a paper layer (2) or a paper-comprising laminate into a deposition chamber, b) Providing an atmosphere comprising parylene monomer in vapour form, c) Allowing parylene monomer to deposit on the paper layer or on the paper-comprising laminate and to polymerize, to form a parylene layer, d) Applying a sealing layer, to provide the barrier laminate (1) according to the invention.

The parylene is preferably applied to result in a layer thickness of between 0.5 and 30 microns, preferably between 1 and 20 microns, more preferably of between 1.5 and 10 microns, most preferably of between 1 .5 and 6 microns on the paper or paper-comprising laminate.

In a third aspect, the invention relates to a flexible packaging product for a consumer product, the packaging product comprising the barrier laminate of the invention.

In a fourth aspect, the invention relates to the use of parylene in a flexible paper-based barrier laminate comprising a sealing layer, to provide barrier property, in particular against the influence from one or more of moisture, such as liquid water, water vapor, oxygen, fat, salt, alkaloid, acid, fragrances, flavours and mixtures thereof.

Detailed description of the invention.

Packaging types, laminates

The present invention relates to a barrier laminate that is paper-based. The paper-based barrier laminate is a flexible material. It can typically be easily bended without damaging the integrity. The laminate is not rigid. It typically is a laminate of several materials, one or more of these layers being paper. The flexible barrier laminates are typically laminates comprising from 2 to 9, preferably 3 to 8, more preferably 4 to 7 layers.

Paper layer

The flexible barrier laminate comprises preferably a total of one, or a total of two, but preferably a total of one layer of paper. Paper typically comprises cellulose fibers.

The paper layer preferably comprises paper, or more preferably is paper with a grammage of between 40 and 100 gram/m², preferably of 50 to 90 gram/m² and most preferably of 50 to 70 gram/m². This provides suitable rigidity to the final packaging product to comprise a consumer product, such as for example a sachet, whereas it can be suitably transported in a packaging line, e.g. over rollers.

In view of the aim of providing a barrier laminate with less impact on the environment, paper is preferably present in an amount of more than 80 wt%, more preferably more than 85 wt%, even more preferably more than 90 wt%, based on the total weight of the barrier laminate. Preferably paper fibers constitute more than 80 wt%, more preferably more than 85 wt%, even more preferably more than 90 wt%, based on the total weight of the barrier laminate. The amount of total polymer, for example the amount of plastic, is preferably below 20 wt%, preferably below 15 wt%, based on the weight of the barrier laminate. It can be for example from 9 to 20 wt%, more preferred from 11 to 15 wt%.

Parylene layer

The barrier laminate of the invention comprises a first layer of parylene (3).

Parylene is known in the art. Parylene is the common name of a class of polymers whose backbone consists of para-benzenediyl rings -CeH4- connected by 1 ,2-ethanediyl bridges - CH2-CH2-. Parylenes are obtain through polymerization of vaporized monomers, for instance parylene N can be obtained by polymerization of para-xylylene H2C=C6H4=CH2. Another name for parylene N is poly-(para-xylol).

Reaction scheme showing pyrolysis of dimer starting reagent to form the para-xylylene monomer which polymerises to form parylene N polymer.

Repeating unit of parylene N.

In traditional applications, parylene coatings are applied to electronic circuits and other equipment. They are used in medicine to prevent adverse reactions to implanted devices. Parylene coatings are typically applied by chemical vapor deposition in an atmosphere of the monomer such as para-xylylene.

Several varieties of parylene can be used in the context of the present invention. Derivatives of parylene can be obtained by replacing hydrogen atoms on the phenyl ring or the aliphatic bridge by other functional groups. Parylene N is the unsubstituted polymer that is obtained by polymerization of the para-xylylene intermediate. Parylene C has one hydrogen atom in the aryl ring replaced by chlorine. Parylene D has two chlorine substitutions on the ring with chorine at the meta position, as known in the art.

Repeating unit of parylene C

Parylene AF-4 has the four hydrogen atoms on the aliphatic chain replaced by fluorine atoms. Parylene VT-4 (also called parylene F) has fluorine substituted for the four hydrogens on the aryl ring.

Specifically, replacement of one hydrogen on the phenyl ring by a methyl group or an ethyl group yields parylene M and parylene E, respectively.

Another common variant is parylene D, with two such substitutions on the ring.

Substitution may occur by alkyl groups on either the phenyl ring or the ethylene bridge, or both. Replacement of one hydrogen on the phenyl ring by a methyl group yields parylene M, substitution or an ethyl group yields and parylene E, respectively.

Parylene AM2 Suitably, the parylene used for a layer in the laminate of the invention is selected from the group consisting of parylene N (poly(p-xylene) or a derivative thereof. Accordingly, the layer is preferably selected from the group consisting of parylene N, parylene C (poly(2-chloro-p- xylene), parylene D, parylene F, parylene AF4, parylene E, parylene M, parylene A, parylene AM2 and mixtures thereof. More preferably, the parylene is selected from the group consisting of parylene N, parylene D or parylene C and mixtures thereof. Even more preferably, the parylene is selected from the group consisting of parylene N or parylene C and mixtures thereof. Most preferably, the parylene is parylene C. It was observed, that in the context of the present invention, parylene N and C showed a particular good resistance to moisture and impact of chemicals when used in paper-based flexible barrier laminate for packaging consumer products. Parylene C is particularly preferred for example in a situation, but not necessarily limited to that situation, wherein no precoat (5) or no additional barrier layer (6) or neither of them is used in the paper-based barrier laminate.

The first parylene layer (3) is preferably located between the paper layer (2) and the sealing layer (4), but can be located on the side of the paper opposite to the sealing layer, in which case the paper is located between the first parylene layer and the sealing layer.

The first parylene layer (3) has preferably a thickness of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 12 microns, more preferably of between 1.5 and 10 microns, even more preferably of between 1.5 and 8 microns, or most preferably of between 1.5 and 6 microns. A thickness may be preferred of between 3 and 12 microns or even 5 to 12 microns. Preferably, the first parylene layer (3) has a thickness of between 0.45 and 23.5 gsm (grams per square meter), more preferably of between 0.45 and 20 gsm, even more preferably between 0.9 and 12.5 gsm, even more preferably between 1.35 and 6.25 gsm, and most preferably between 1.35 and 4.65 gsm. The latter weight ranges (expressed as gsm) correspond typically with the respective thickness ranges indicated earlier (microns). In particular when the first parylene layer is used in absence of a precoat layer (5), or further barrier layer (6), such as preferably a metal or metal oxide layer such as aluminum or aluminum oxide, the thickness of the first parylene layer is preferably of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 10 microns, most preferably of between 1 .5 and 6 microns. Accordingly, it can for example be preferred that when the first parylene layer is parylene C and used in absence of a precoat layer (5), or further barrier layer (6), such as preferably a metal or metal oxide layer such as aluminum or aluminum oxide, the thickness of the first parylene layer is of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 10 microns, most preferably of between 1.5 and 6 microns. Also, it can be preferred that when the first parylene layer is parylene N and used in absence of a precoat layer (5), or further barrier layer (6), such as preferably a metal or metal oxide layer such as aluminum or aluminum oxide, the thickness of the first parylene layer is of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 10 microns, most preferably of between 1.5 and 6 microns.

It is desired, that the grammage of the first parylene layer (3) is less than 15wt%, preferably less than 10wt%, more preferably less than 5wt% of the total weight of the barrier laminate. In this manner optimal recyclability of the barrier laminate is achieved. The grammage of the first parylene layer (3) is preferably from 0.5 to 15wt%, more preferably from 1 to 15wt%, even more preferably from 1 .5 to 10wt% of the total weight of the barrier laminate. The amount of polymer other than parylene may be from 1 to 20 wt%, preferably from 2 to 15 wt%, more preferably from 4 to 12 wt%, based on the weight of the barrier laminate.

Sealing layer

The barrier laminate is a flexible material and comprises a sealing layer (4). The sealing layer allows the packaging laminate to be formed and fixed to form a packaging product in the form of e.g. a sachet or wrapper to contain a consumer product. Accordingly, the sealing layer is typically a peripheral layer of the barrier laminate, which typically represents the product-facing side in a packaging (like a sachet) made from the laminate. Accordingly, within the barrier laminate, the sealing layer is preferably only on one side in contact with another layer of the laminate, and the sealing layer is preferably facing the outside world (i.e. not covered with a further layer). The sealing layer may be selected from the group of heat seal layer, cold seal layer and pressure seal layer.

Preferably, the sealing layer is a heat seal layer. Typical heat seal layers comprise one or more thermoformable polymers such as poly(ethylene) homo- and co-polymers, poly(propylene) homo- and co-polymers, poly(1 -butene) (PB), ethylene vinyl acetate) (EVA) copolymers and terpolymers, poly(ethylene-co-acrylic acid) (EAA), poly(ethylene-co-methacrylic acid) (EMA), ionomer, polyvinyl alcohol (PVOH) semicrystalline poly(ethylene terephthalate) (CPET), amorphous PET (APET), poly(ethylene glycol-co-1 ,4-cyclohexanedimethanol terephthalate) (PETG), poly(lactic acid) (PLA), poly(butylene succinate) (PBS), poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), styrene/butadiene (SBS) copolymers, thermoplastic starch, poly(hexano-6-lactam) (Nylon 6), preferably ethylene-vinyl acetate (EVA) copolymers, poly(ethylene-co-methacrylic acid) (EMA), or styrene/butadiene (SBS) copolymers. The heat seal layer may be applied by dispersion coating or extrusion coating. The heat seal layer may be with or without a mineral filler. Apart from possibly in the sealing layer, it can be preferred that the barrier laminate of the present invention does not comprise polypropylene, polyethylene, polyethylene terephthalate.

As known in the art, the sealing polymer can be deposited on the underlying layer by providing a dispersion of polymer particles in a solvent that is provided on the base layer, such as the on the parylene layer (dispersion coating). The solvent is consequently removed, for example by heating, and the polymer particles are deposited on the base layer, e.g. the parylene layer. Alternatively, as known in the art, the sealing polymer can be extruded (extrusion coating), typically via extruding molten resin through a slot die directed onto the base laminate and then passed through a nip that may comprise a covered pressure roller, typically rubber-covered, and cooling roller that typically may be chrome plated. This base-laminate surface is typically moving at a speed which is faster compared to the extruded film and draws the film onto the desired thickness. The sealing layer (4) is typically located on the side of the barrier laminate that will face the product to be packaged. Preferably, the sealing layer is deposited on the product-facing side of the first parylene layer (3). It can be preferred that no other layer is present between the first parylene layer and the sealing layer, typically when the sealing layer (4) is applied at the same site of the paper layer as the first parylene layer (3). It can be preferred, e.g. typically when the sealing layer is applied at the opposite side of the paper layer, e.g. when one parylene layer is present, that the paper is between the sealing layer and the parylene layer. This is exemplified in examples G and H.

The sealing layer is preferably of between 1 and 10 gsm, preferably between 1.5 and 6 gsm, more preferred between 2 and 5 gsm.

Pre-coating of paper

It may be preferred, that the flexible barrier laminate comprises a pre-coat layer (5). A pre-coat is preferably present adjacent to the paper layer (2). A pre-coat proved beneficial to further block the open paper fiber surface and enhance adhesion of the first parylene layer (3) to the paper. Adhesive is less suitable for this purpose in the present context and preferably is absent from the paper-based barrier laminate of the present invention, preferably absent between the paper and parylene layer. The precoat may be, for example, one or more layers, either with or without a mineral filler, selected from the group consisting of acrylic acid, ethylene-acrylic or methacrylic acid copolymers, butenediol vinyl alcohol copolymers (BVOH), cellulose nitrate, ethyl-vinyl acetates, ethylene vinyl alcohol (EVOH), microfibri Hated cellulose (MFC), nanocrystalline cellulose (NCC), native and chemically modified starches, polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(butylene succinate-co-adipate) (PBSA), polyesters, polyhydroxyalkanoates (PHA) and their copolymers, polylactic acid (PLA), polyolefins, polyurethanes (Pll), polyvinyl acetate (PVAc), polyvinyl alcohol (PVOH), polyvinyl dichloride, silanes, styrene acrylate, styrene-butadiene, waxes, or xylan and chemically modified xylan, preferably acrylic acid, ethylene-acrylic or methacrylic acid copolymers, butenediol vinyl alcohol copolymers (BVOH), ethyl-vinyl acetates, ethylene vinyl alcohol (EVOH), polyesters, styrene acrylate, styrene-butadiene, and combinations thereof. The precoat layer (5) has preferably a thickness of between 1 and 5 gsm, preferable 1.5 to 4 gsm. The precoat preferably has a thickness of from 1 .3 to 6.5 microns, more preferably of from 1 .95 to 5.2 microns. The pre-coat can suitably be applied using dispersion or extrusion coating, as known to the skilled person. In the case a pre-coat is present on the paper, it is typically present at the surface facing the first parylene layer, i.e. preferably the side to face the product to be packaged. The pre-coat may be a plasma-treated pre-coat. In this situation the precoat typically is plasma-treated before the parylene is deposited on it.

Additional barrier layer

The barrier laminate of the present invention may further comprise an additional barrier layer (6), i.e. in addition to a first parylene layer. An additional barrier layer is preferably in contact with the parylene layer. The additional barrier layer (6) is preferably located between the first parylene layer (3) and the paper (2), more preferably between a pre-coat layer (5) and the first parylene layer. An additional barrier layer is preferably directly adjacent to the first parylene layer. The additional barrier layer may comprise a metal or metal oxide layer. The additional barrier layer preferably comprises one or more selected from the group consisting of aluminum metal, aluminum oxide, zinc oxide, titanium oxide, silicon oxide and combined layers of these. More preferably, the additional barrier layer comprises aluminum metal or aluminum oxide, and most preferably is an aluminum oxide layer. It may be preferred that the additional barrier layer is aluminum metal or aluminum oxide, preferably in combination with zinc oxide or titanium oxide. The additional barrier layer, such as preferably the metal or metal oxide layer, may be deposited on a precoat layer (5) that precoats the paper. The additional barrier layer may be deposited using techniques used in the art, such as physical or chemical vapor deposition. In case the additional barrier layer comprises multiple materials, such as for example a combination of a metal and a metal oxide or two metal oxides, the layers are deposited on top of each other in layers. The additional barrier layer, such as preferably the metal or metal oxide layer, is preferably treated with plasma, preferably at least at the side facing the parylene layer. If a metal layer or metal oxide layer is present, it is preferred, that a pre-coat is present on which the metal is deposited. It is preferred that a total of one additional barrier layer (6) is present. In such a case, a single additional barrier layer may consist of layers of metal, metal oxide or both. Alternatively, it can be preferred that the single barrier layer consists of only of a single type of metal or a single type of metal oxide.

The additional barrier layer, preferably comprising a metal layer or metal oxide layer, and more preferably being an aluminum layer or an aluminum oxide layer, preferably has a thickness of between 0.01 and 1 micron. It can be preferred that the barrier laminate comprises a first parylene layer (3) with a thickness of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 12 microns, more preferably of between 1.5 and 10 microns, even more preferably of between 1 .5 and 8 microns, or most preferably of between 1.5 and 6 microns and an additional barrier layer, preferably comprising a metal layer or metal oxide layer, of between 0.01 and 1 micron.

An additional barrier layer (6) may be present between the paper layer and the sealing layer.

It can be preferred that an additional barrier layer (6) is present preferably between the paper layer and the first parylene layer, in which case it can be preferred that a pre-coat (5) is present adjacent to the paper layer and the additional barrier layer (6) is present adjacent to the precoat layer (5). The additional barrier layer (6) therefore preferably is applied to the pre-coat layer (5). The additional barrier layer may or may not be plasma-treated.

It is preferred that parylene is deposited on such an additional barrier layer (6), preferably on a metal or metal oxide layer, preferably on a plasma-treated metal or metal oxide layer, to form the first parylene layer (3).

In a preferred situation, the barrier laminate of the invention comprises a pre-coat layer (5), a metal or metal oxide layer (6), or both a pre-coat layer (5) and a metal or metal oxide layer (6), between the paper (2) and the sealing layer (4), wherein the parylene layer is parylene N or parylene C. Especially if the parylene layer is parylene N, it may be preferred that a precoat (5) and/or an additional barrier layer (6), preferably comprising metal or metal oxide, more preferably comprising aluminum or aluminum oxide, is present.

It can be preferred, that an additional barrier layer (6) and no parylene layer is present between the paper layer and the sealing layer. It can also be preferred that no additional barrier layer (6) is present, preferably, that no metal or metal oxide layer is present in the barrier laminate. It is preferred that no additional barrier layer (6) comprising polypropylene, polyethylene, polyethylene terephthalate, with or without metalisation is present.

Plasma treatment

It was found in the present invention, that for optimal functionality in the paper-based barrier laminate, it is beneficial that the layer on which the parylene is deposited, such as the paper layer (2), a pre-coat layer (5) or additional barrier layer such as a metal and/or metal oxide layer (6), and preferably the paper layer (2), underwent a plasma treatment (9). The technique of plasma treatment is as such known in the art, and involves providing an electrically charged gas that contacts the surface to be treated. The plasma treatment preferably comprises, more preferably is, corona treatment, also called corona discharge. Without willing to be bound by theory, plasma treatment in the presence of oxygen introduces functional groups such as hydroxyl, carbonyl, and carboxyl groups to the surface of the substrate, in particular e.g. to the paper surface (2), to which parylene is to be connected. It was surprisingly found, that in the context of the present invention, plasma treatment enhances the adhesion of the substrate, such as e.g. paper, and of the parylene layer after deposition of the parylene on the substrate, in particular on the paper. It is in particular preferred, that the paper is treated with plasma at the side facing and preferably contacting a parylene layer. It may be preferred that the paper is treated with plasma at both sides of the paper layer (2).

It may be preferred that the first parylene layer (3) is treated with plasma at the surface not facing or directed to the paper layer (2). This can preferably be arranged to ensure an improved connection between the parylene layer (3) and the sealing layer (4). The plasma treatment can be carried out as described above for the plasma treatment of the paper layer.

Also, in case an additional barrier layer (6), such as a layer comprising metal or metal oxide, is present, preferably between the paper and the first parylene layer, it can be preferred that the additional barrier layer is treated with plasma. This contributes to a better adhesion between the additional barrier layer (6) and the first parylene layer (3), after deposition of the parylene.

In a preferred situation, the paper is plasma-treated at the surface facing the first parylene layer, and the first parylene layer is plasma treated at the surface facing the sealing layer. In another preferred situation, the additional barrier layer (6) is plasma treated at the surface facing the first parylene layer, and the first parylene layer is plasma treated at the surface facing the sealing layer. In case a pre-coat is present, it is preferably plasma treated. It may be preferred that the first parylene layer itself is treated with plasma, before the sealing layer is connected to it, preferably the heat sealing layer is connected to it.

Ink layer

The barrier laminate is used to protect a consumer product (10). In this respect, it also provides a communication function to the consumers who will buy the consumer products, typically via information printed on the paper, including information regarding ingredients, appealing artwork and advertisement etc. The barrier laminate therefore preferably comprises a layer of ink (7). This layer of ink is preferably connected to the paper layer. It may be preferred that there is a primer applied between paper layer and ink layer. Appropriate primers are known to the person skilled in the art, and may, for example, be a polyurethane primer. The layer of ink is preferably in direct connection with the layer of paper (2) and typically faces the outside of the barrier laminate (e.g. when applied in a consumer packaging), i.e. the site opposite to the site of the barrier laminate that will be in contact with the consumer product to be packaged. I.e. typically opposite of the side of the paper where the sealing layer (4) is located.

Protection layer

For example, to protect the ink layer, the barrier laminate preferably comprises a protection layer (8) on top of the ink layer. The protection layer is typically facing the outside world. It is typically located opposite to the product-facing site of the laminate (e.g. when applied in a consumer packaging) and opposite to the side of the laminate where the sealing layer is located. The protection layer (8) may be an over-print varnish (OPV), OPVs are well-known to the person skilled in the art and the chosen varnish depends on the intended use of the barrier laminate of the present invention. For example, the OPV may be selected from the group consisting of conventional offset letterpress varnishes, acrylic varnishes, UV varnishes, and gravure varnishes. OPVs can be water-based polymer formulations or solvent-based polymer formulations. The protection layer may also be a layer comprising parylene, preferably being parylene C or parylene N. In the latter case, the barrier laminate comprises more than one layer of parylene and preferably comprises a total of two layers of parylene. A second parylene layer (8) could be preferred, as it provides an additional protection layer to outside influences. The protection layer (8) typically is deposited directly on the ink layer (7), It is preferably in direct contact with the ink layer. The protection layer, e.g. the second parylene layer, faces an outside of the packaging material, typically the site opposite to the site that is intended to face or faces the consumer product to be packaged, i.e. typically opposite of the side of the paper where the sealing layer is located. The thickness of the protection layer (8), preferably of the second parylene layer, is preferably between 0.5 and 3 microns, preferably of between 1 and 2 microns.

In an embodiment, it is possible that a single parylene layer (6) is present facing the outside world and covering the ink layer, thereby functioning as protection layer of the ink layer (see e.g. example G, H).

Packaging product and packaged consumer product

In a further aspect, the invention relates to a flexible packaging product for packaging a consumer product, the packaging product comprising the flexible barrier laminate of the invention.

The packaging product may be in the form of a flow-wrap, pillow bag, gusseted bag, stand-up pouch, diaper bag, tetrahedral bag, guattro seal bag or sachet. The packaging product may contain a consumer product. Typical consumer products that can be packaged using packaging products with flexible barrier laminate of the invention are preferably selected from the group consisting of frozen confectionary, bouillon, soup, sauces, coffee, tea, supplements, vitamins, electrolyte powders, laundry detergents, skin cleansing products, skin care products and haircare products. In particular, it is preferred that the packaging product is a sachet, a pouch or a wrapper. A wrapper can be used for example to wrap a soap bar, a frozen confectionary productor a condiment like a bouillon or seasoning concentrate.

The invention further relates to a packaged consumer product, wherein the consumer product is packaged in a packaging product comprising the flexible barrier laminate of the invention.

Process

In a further aspect, the present invention relates to a process to provide a barrier laminate according to the invention. The process comprises the steps of: a) Providing a paper layer (2) or a paper-comprising laminate into a deposition chamber, b) Providing an atmosphere comprising parylene monomer in vapour form, preferably para- xylylene, i.e, the monomer for parylene N, or a monomer of parylene C, a monomer of parylene D, a monomer of parylene E, a monomer of parylene F, a monomer of parylene AF-4, parylene M, or a monomer of parylene AM-2, c) Allowing monomer of parylene to deposit on the paper layer or on the paper-comprising laminate and to polymerize, to form a parylene layer, d) Applying a sealing layer, to form a barrier laminate according to the invention. Preferably, the parylene is deposited to form a layer of 0.5 and 30 microns, preferably between 1 and 20 microns, more preferably of between 1.5 and 12 microns, even more preferably of between 1.5 and 10 microns, even more preferably of between 1.5 and 8 microns, and most preferably of between 1.5 and 6 microns on the paper or paper-comprising laminate. It could be preferred that a layer of between 3 and 12 microns is deposited, or that even a thickness of between 5 and 12 microns is preferred.

In step a) a paper layer is provided. The paper is positioned into a deposition chamber, also called coating chamber. The process is essentially illustrated in Figure 1. The paper layer can be coated with one or more other layers before it is brought into the coating chamber. In this situation, a paper-comprising laminate is provided into the deposition chamber. Such a laminate may comprise apart from the paper layer, a precoat layer, a metal layer or a metal oxide layer, such as for example aluminum or aluminum oxide.

Once in the deposition chamber, in step b) an atmosphere is created of a parylene monomer. The parylene monomer is preferably selected from the group consisting of para-xylylene (i.e, the monomer for parylene N), the monomer of parylene C, the monomer of parylene D, the monomer of parylene E, the monomer of parylene F, the monomer of parylene AF-4, the monomer of parylene M, or the monomer of parylene AM-2. It is preferred, that the parylene monomer is selected from the group consisting of para-xylylene (i.e, the monomer for parylene N), the monomer of parylene C, the monomer of parylene D, even more preferably from the group consisting of para-xylylene (i.e, the monomer for parylene N) and the monomer of parylene C, and most preferably the monomer is the monomer for parylene C. This atmosphere is typically created by vaporising a raw material, i.e. a dimer molecule, for example dichloro[2,2]paracyclophane for parylene C, 2,2-paracyclophane for parylene N, octafluor[2.2]paracyclophane for parylene F (AF-4), as the skilled person is aware. This is typically done in a sublimation process at a temperature typically of between 150 and 175 °C and typically in a vaporizer, that may be connected to the coating chamber. The dimer vapour is heated high enough to trigger pyrolysis, typically at a temperature between 650 and 690 °C, typically in a pyrolysis furnace that is connected to the coating chamber. In this respect, for example, the vaporizer feeds into the pyrolysis furnace, and the latter feeds into the coating chamber. During pyrolysis the dimer splits to form two monomer molecules, each with two, highly reactive, carbon-centered free radicals. This reactive monomer vapour then enters the coating chamber, which is held at room temperature, typically at a pressure of 30-50 Torr (39999.7-6666.1 Pa). Accordingly, in step c), the parylene monomer in vapour form is allowed to deposit on the paper or paper-comprising laminate. This is typically achieved by decreasing the temperature below the deposition temperature of the respective monomers. Deposition typically occurs by reducing the temperature below 60°C. Preferably, the temperature is above the polymerization temperature of the parylene, and the temperature is preferably brought to between -30 and 60 °C, preferably between 0 and 30 °C, most preferably between 5 and 25 °C.

The pressure during polymerization is preferably of from 0.3 to 0.5 Torr, which translates to a pressure of from 40.0 - 66.6 Pa.

Excess parylene is typically captured in a cold trap (see Figure 1). A pump, such as a vacuum pump, connected to the coating chamber, typically removes the air and other gasses from the coating chamber, and thereby allows parylene deposition on the paper or paper-comprising laminate.

The parylene coating process may include masking the pre-barrier laminate (an intermediate stage of the final barrier laminate) to prevent the parylene coating all surfaces, for example, masking one side of the paper sheet to get a single-side coating. Masking can include covering one surface, e.g. the paper surface, with an impervious material, for example adhering the paper to a metal plate with an adhesive layer, e.g adhesive tape, that could for example be removed at a later stage.

The thickness of the parylene layer can be controlled by the deposition time, wherein longer deposition results in a thicker coating. Typically, a deposition time is used of from 12 to 48 hours, more preferably of from 12 to 17 hours, to achieve for example parylene layers of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 10 microns, most preferably of between 1.5 and 6 microns.

Plasma treatment

If plasma treatment is carried out, it may be preferred to apply an Ar/Ch plasma. Suitably, the charge of the plasma treatment is from 15 to 100 seem of Argon and Oxygen. The power is preferably from 150 to 500 Watts. The exposure time is preferably of from 1 to 4 minutes. Plasma treatment is preferably carried out immediately before the pre-barrier laminate is loaded into the parylene deposition chamber. Deposition of pre-coating

A pre-coat may be applied e.g. using dispersion coating, using different processes and coaters as known in the art. Various coating methods can be used, such as blade, rod, air knife, gravure and curtain coaters, which are commonly used to apply a thin layer of material to which the solvent is evaporated. Evaporation of solvent can be effectuated by several methods, such as infra-red dryers, air float dryers and impingement dryers. Examples of the dispersion coating process are described by Kimpimaki, T., Savolainen, A.V. (1997), Barrier dispersion coating of paper and board. In: Brander, J., Thorn, I. (eds) Surface Application of Paper Chemicals. Springer, Dordrecht. Regardless of the processing method, the outcome typically is a uniform and continuous polymer film onto the substrate.

Deposition of an additional barrier layer

An additional barrier layer may be applied by deposition techniques as known in the art, such as for example physical vapour deposition (PVD), chemical vapor deposition (CVD), plasma- enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), sputtering and sol-gel coating.

An additional barrier layer may be deposited by PVD as described in Thin Solid Films, Volume 666, 2018, pp 6-14 and Mattox, D.M. (2010), Handbook of Physical Vapor Deposition (PVD) Processing, Elsevier Science, pp. 195-237. During vacuum deposition onto a flexible film, a solid is heated and vaporized in a vacuum before being deposited under vacuum over a web of film that is spooled in the vacuum chamber between a feed roller and a take-up roller.

An additional barrier layer may be deposited by CVD as described in R. F. Bunshah, Vapor deposition technologies, in Handbook of hard coatings: Deposition technologies, properties and applications, G. E. McGuire, S. M. Rossnagel and R. F. Bunshah, eds., 2001 , Noyes Publications, William Andrew Publishing, LLC, Norwich, NY, p. 4-76. The process is similar to PVD but introduces addition a precursor gas which reacts with the vaporized metal for form compounds such as oxides in the vapour phase before being deposited onto a web of film. If a plasma is applied to induce the decomposition of the precursor, the process is called plasma enhanced CVD (PECVD) or plasma assisted CVD (PACVD).

An additional barrier layer may be deposited by ALD as described by Hong Chen Guo, Enyi Ye, Zibiao Li, Ming-Yong Han, Xian Jun Loh, Recent progress of atomic layer deposition on polymeric materials, Materials Science and Engineering: C, Volume 70, Part 2, 2017, Pages 1182-1191. ALD is a special variant of the CVD technique where gaseous reactants known as precursors are introduced into the reaction chamber. These precursors react with the surface of a material one at a time in a sequential, self-limiting, manner. A thin film is slowly deposited through repeated exposure to separate precursors. An additional barrier layer may be deposited by sputtering as described by R Lewin, RP Howson, CA Bishop, Ml Ridge, Transparent conducting oxides of metals and alloys made by reactive magnetron sputtering from elemental targets, Vacuum, Volume 36, Issues 1-3, 1986, Pages 95-98 and by R. C. Merrill; G. J. Egan; B. W. Paszek; A. J. Aronson, Continuous Sputtering of Metals on Plastic Film Substrates, Journal of Vacuum Science & Technology, Volume 9, Issue 1 , 1972, Pages 350-353. Sputtering is a technique in which metal atoms are removed from a solid target by means of ion bombardment and are then absorbed on the substrate surface facing the target.

An additional barrier layer may be deposited by sol-gel coating as described by Wang, S., Mahlberg, R., Nikkola, J., Mannila, J., Jamsa, S., Ritschkoff, A.-C. and Peltonen, J. (2012), Surface characteristics and wetting properties of sol-gel coated base paper. Surf. Interface Anal., 44: 539-547. Sol-gel coatings are inorganic ceramic materials or inorganic-organic hybrid materials. Small molecules are dispersed in a solvent as a colloidal dispersion (sol) that react together via hydrolysis then polycondensation to form a solid three-dimensional polymeric network (or gel).

Deposition of a sealing layer

According to step d) of the process, a sealing layer is applied. This is preferably done with the processes and coaters as used for the application of a pre-coat layer, see above. The coating methods such as blade, rod, air knife, gravure and curtain coaters are commonly used to apply a thin layer of material to which the solvent is evaporated. Evaporation of solvent can be by several methods, such as infra-red dryers, air float dryers and impingement dryers. Examples of the dispersion coating process are described by Kimpimaki, T., Savolainen, A.V. (1997). Barrier dispersion coating of paper and board. In: Brander, J., Thorn, I. (eds) Surface Application of Paper Chemicals. Springer, Dordrecht. Regardless of the processing method, the outcome should be uniform and continuous polymer film onto the substrate.

Use

Using a parylene layer, a paper-based barrier laminate could be obtained with a water vapour transmission rate measured at 38 °C and 90 %RH that is preferably below 40, more preferably below 30 and optimally below 10 g/m²/day. It can be desired that the barrier laminate has a WVTR of below 15, preferably below 10 and most preferably below 5, when measured at 25 °C and 50 %RH. The barrier laminate preferably has an oxygen transmission rate at 25 °C and at 50 %RH of below 25, preferably 10, more preferably below 5 and more preferably of below 1 and most preferably of below 0.5 cc/m²/day. Accordingly, the present invention relates to the use of parylene in a flexible paper-based barrier laminate to provide barrier property. Preferably, the barrier property is against influence from one or more of liquid water, water vapor, oxygen, fat, salt, alkaloid, acid, fragrance, flavours, and mixtures of these, preferably of liquid water, water vapour or oxygen. It may be preferred that the barrier property is protection against moisture wherein the water vapour transmission rate measured at 38 °C and 90 %RH is below 40, preferably below 30 and optimally below 10 g/m²/day, or the WVTR is measured at 25 °C and at 50 %RH below and is below 15, preferably below 10 and most preferably below 5, or wherein both apply. It can be preferred that the barrier property is protection against oxygen, wherein the barrier laminate has an oxygen transmission rate at 25 °C and at 50 %RH of below 25, preferably 10, more preferably below 5 and more preferably of below 1 and most preferably of below 0.5 cc/m²/day.

The invention is now exemplified by the following, non-limiting examples:

Examples

Example 1 .

Paper-based flexible packaging materials according to the invention were prepared using the following process.

Paper sheets with a grammage of 78 and 80 gsm were introduced in a deposition chamber of size 24 or 36 in³.

Samples 7-12 were pre-coated with Michelman Michem Flex B1002 dispersion coating at 4 gsm dry grammage. Samples 1-6 (UPM Solide Lucent) and 13-18 (Arjowiggins Sylvicta) are commercially available papers with paper grammage of 78 and 80 gsm and thickness of 39 and 71 microns, respectively.

The exposed surface of the masked barrier laminates, paper or pre-coat, were plasma treated with an Ar/Ch plasma (50 seem of each) at 300 Watts for two minutes immediately before being loaded into the parylene deposition chamber.

Two parylene coatings where prepared. The parylene coating method starts by vaporising the raw material dimer. For parylene C, dichloro[2,2]paracyclophane was used and for parylene N, 2,2-paracyclophane was used. 1 kg of dimer was used for the desired coat thickness in a chamber with volume 24 cubic inch (393.29 cm³). The 2,2-paracyclophane or dichloro[2,2]paracyclophane dimer vapour is heated high enough to trigger pyrolysis, resulting in the formation of monomers. For parylene C and parylene N the vapour was heated to 700 °C. This reactive monomer vapour then enters a coating chamber, which was held at room temperature. The monomer molecules simultaneous deposited and polymerised on all available surfaces. Excess parylene vapour is captured in a cold trap and pumped off via a vacuum pump (Figure 1). For both parylene N and C, samples were prepared with target thicknesses of the parylene layer of 6-8 microns and 10 microns, and with different types of paper, kraft paper UPM Solide Lucent 78 gsm; kraft paper UPM Solid Lucent 78 gsm coated with 4gsm Michelman Michem Flex B1002; and microfibrillated paper Arjowiggins Sylvicta, 80 gsm (Table 1). The Solide Lucent paper is based on cellulose fibers, the Sylvatica paper is based on micro-fibrillated cellulose. The thickness of the layer of parylene was controlled by the time of deposition, 15 hours for 6- 8 microns and 17 hours for 10 microns of parylene coating.

Table 1 Samples of paper coated with parylene type-C and type-N at different thicknesses. Paper was parylene coated on one side of the paper. The coating thicknesses were measured using glass witness coupons via spectral reflectance (Filmetrics F20). *Based on densities of parylene N and parylene C as 1.11 and 1.29 g/cm³, respectively. ’’Thickness and grammage of samples 8, 9 and 10 represent the properties of low density polyethylene film.

The samples were tested for water vapour transmission rate and oxygen transmission rate, to test the barrier properties. Results have been depicted in Table 2. WVTR measurements recorded at 38 °C 90 %RH were conducted on a PERMATRAN-W 1/50 G following ASTM F1249 standards.

WVTR measurements recorded at 25 °C 50 %RH were conducted using a MOCON AQUATRAN 3 WVTR Analyser following ASTM F3288-18 standards using a Coulometric P2O5 Sensor.

OTR measurements were conducted using a MOCON OXTRAN OTR Analyser following ISO 15105-2 standards.

Table 2 Water vapour (WVTR) and oxygen transmission rates (OTR) of parylene coated paper measured using MOCON Permeation Testing Analysers

A WVTR of below 40 is preferred, preferably below 30 and optimally below 10 g/m²/day, at 38 °C 90 %RH. At 25 °C 50 %RH, the WVTR is preferably below 5. Preferably, OTR is below 10, preferably below 5, most preferably below 0.1.

Example 1 indicates the water vapour barrier properties of parylene C and parylene N when applied in paper based flexible barrier laminate. Both parylene C and N show acceptable results, especially under the 25°C circumstances. Pre-coat appears to have limited effect on the water vapour barrier properties.

The oxygen transfer rate (OTR), assessed at 25 °C of packaging material without precoat is significantly lower for parylene C coated material. When a pre-coat is used, both parylene C and N showed excellent oxygen barrier behavior, while meeting recyclability requirements (more than 80% paper). Comparative examples (C.E.) 8-10 show acceptable WVTR, and less optimal OTR and recyclability objectives were not met (less than 80 % paper).

The thin layer of parylene as primary barrier material allows for recyclability of the barrier laminate. For example, conventional metalized PP or LDPE should be applied at levels of 20 to 50 gsm to providing similar levels of barrier properties.

In addition to the WVTR and OTR, the light transmission was assessed for both parylene C and N when applied at the paper samples indicated in Table 1 . The light transmission was good for both parylene C and N, about 90% of the light was transmitted, and didn’t significantly differ between the parylene types and appeared irrespective of the coating thickness. This makes parylene a good candidate for a protection layer applied over the ink layer, to protect the ink on the packaging material from external influences.

Example 2

Several flexible paper-based barrier laminates are made using the technology of the invention, as depicted in

Table 3 Barrier laminates A-H.

1. Laminate, 2. Paper, 3. Parylene, 4. Heat-seal coating, 5. Pre-coat, 6. Metal oxide, 7. Ink, 8. Over-print Varnish, 9. Plasma, 10. Product (not part of the laminate), 11. Environment (not part of the laminate).

Barrier laminates A and B show paper-based packaging material wherein a coating layer of parylene is present. The parylene is deposited on the paper (material A) or on a pre-coating that is deposited on the paper (2). The paper or pre-coating, respectively, can be treated with plasma. In both laminates A and B, the parylene layer has been treated with plasma before a heat seal coating is applied directly on the parylene layer. Both laminates A and B have an ink layer on the site of the paper facing the environment (11) that has been protected with a protection layer of over print varnish.

Barrier laminates C and D are essentially the same as laminates A and B, respectively, with the difference that a second parylene layer is present in the material. This second parylene layer (8) forms the protection layer to protect the ink layer (7) from outside influences, and provides a further barrier layer to protect the paper (2) and the consumer product in the packaging.

Laminates E and F are based on the laminates B and D respectively. A further protection layer (6) has been deposited in the form of metal oxide (e.g. aluminium oxide). The metal oxide layer is deposited on a pre-coat layer (5), followed by plasma treatment (9) to enhance the connection of parylene (3) to the metal oxide coating. Laminates G and H exemplify the situation wherein the paper layer (2) is present between a first parylene layer (3) and a heat sealing layer (4). A pre-coat (5) is present in laminate example H, between the paper (2) and the sealing layer (4). In barrier laminates C, D, F, G and H the OVP layer (8) is a second parylene layer.

Claims

1. A flexible barrier laminate (1) comprising:

• A paper layer (2),

• A first parylene layer (3),

• A sealing layer (4).

2. Barrier laminate according to claim 1 , wherein a pre-coat layer (5) is present that is in contact with the paper layer, preferably present between the paper layer (2) and the sealing layer, preferably between the paper layer and the parylene layer (3).

3. Barrier laminate according to anyone of the preceding claims, wherein the barrier laminate further comprises a further barrier layer (6) comprising a metal or metal oxide, preferably present between the paper layer (2) and the first parylene layer (3).

4. Barrier laminate according to claim 3, wherein the further barrier layer (6) has a thickness of between 0.01 and 1 micron, and preferably is aluminum or aluminum oxide, preferably in combination with zinc oxide or titanium oxide.

5. Barrier laminate according to any one of the preceding claims, wherein the layer on which the parylene is deposited has been plasma-treated.

6. Barrier laminate according to any one of the preceding claims, wherein the first parylene layer has a thickness of between 0.5 and 30 microns, preferably between 1 and 20 microns, preferably of between 1.5 and 10 microns, most preferably of between 1.5 and 6 microns.

7. Barrier laminate according to any one of the preceding claims, wherein the first parylene layer is plasma treated at the side facing the sealing layer.

8. Barrier laminate according to any one of the preceding claims, wherein the paper layer has a grammage of between 40 and 100 gram/m², preferably of 50 to 90 gram/m² and most preferably of 50 to 70 gram/m².

9. Barrier laminate according to any one of the preceding claims, wherein the barrier laminate comprises more than 80 wt%, preferably more than 85 wt% and even more preferably more than 90 wt% of paper fibers, based on the weight of the barrier laminate.

10. Barrier laminate according to any one of the preceding claims, wherein the parylene is selected from parylene N or a derivative thereof, preferably is selected from the group consisting of parylene N, parylene C, parylene D, parylene F, parylene AF4, parylene E, parylene M, parylene A, and mixtures thereof, more preferably from the group consisting of parylene N, parylene D or parylene C and mixtures thereof, even more preferably from the group consisting of parylene N or parylene C and mixtures thereof, and most preferably wherein the parylene is parylene C.

11 . Barrier laminate according to any one of the preceding claims, wherein the laminate further comprises a protection layer (8), preferably a second parylene layer (8), in addition to first parylene layer (3), preferably being parylene N or parylene C, facing an outside of the barrier laminate opposite to the side of the paper where the sealing layer (4) is present, and having a thickness of between 0.5 and 3 microns, preferably of between 1 and 2 microns.

12. Packaging product comprising the barrier laminate according to any one of the preceding claims.

13. Packaging product according to claim 12, wherein the packaging product contains a consumer product selected from the group consisting of frozen confectionary, bouillon, soup, sauce, coffee, tea, food supplement, vitamins, electrolyte powder, laundry detergents, skin cleansing product, skin care product or haircare product.

14. Process to provide the flexible barrier laminate according to any one of claims 1 to 11 , the process comprising the steps of: a) Providing a paper layer or a paper-comprising laminate into a deposition chamber, b) Providing an atmosphere comprising parylene monomer in vapour form, preferably monomer for parylene N, monomer for parylene C, monomer for parylene D, monomer for parylene E, monomer for parylene F, monomer for parylene AF-4, parylene M, or monomer for parylene AM-2, c) Allowing the parylene monomer to deposit on the paper layer or on the papercomprising laminate and to polymerize, to form a parylene layer, preferably of 0.5 to 30 microns, preferably 1 to 20 microns, more preferably between 1.5 and 10 microns and most preferably between 1.5 and 6 microns, d) Applying a sealing layer, to form a barrier laminate according to any one of the claims 1 to 11 .

15. Use of parylene in a paper-based flexible barrier laminate comprising a sealing layer, to provide barrier property against influence from one or more of liquid water, water vapor, oxygen, fat, salt, alkaloid, acid, fragrance, flavour, and mixtures of these, preferably against liquid water, water vapour or oxygen.