Parchment with high oxygen barrier properties

Abstract

The present invention relates to a barrier paper comprising a parchment substrate and a discontinuous coating layer formed on a surface thereof wherein the discontinuous coating layer is made of at least one of a water-soluble polymer and a water-dispersible polymer.

Description

Technical Field

[0001] The present invention relates to a parchment paper which can be used as an oxygen barrier layer in a packaging material for oxygen sensitive items. Further aspects of the present invention include a method for producing an oxygen barrier parchment paper and a packaging material comprising the oxygen barrier parchment paper. Background Art

[0002] Packaging materials contribute to a large amount of waste, which many countries are currently trying to reduce by replacing fuel-based plastic packaging materials with fully biodegradable, compostable and bio-derived packaging materials. Such biodegradable packaging materials must meet various conditions, depending on the end use. For example, when used as food packaging, they must be safe for food contact, and when used as packaging for life science and diagnostic devices, they must meet strict safety requirements. In particular, when used as packaging material for oxygen-sensitive products, sufficient gas barrier properties of the packaging material are necessary. Pure vegetable parchment (GVP), which is known to be made of 100% cellulose, is a biodegradable packaging material with moisture vapor barrier properties and inherent grease barrier properties.

[0003] In order to achieve the desired oxygen barrier properties, parchment paper is either produced with a very high level of parchmentization or an additional oxygen barrier layer is laminated thereto.

[0004] EP 3 819 426 A1 describes parchment paper having a very high level of parchmentization.

[0005] However, there are some limitations in terms of mechanical properties when using GVP with very high levels of parchment. Although such very highly parchmented GVP grades are very interesting because they have inherent oxygen barrier properties and they are completely bio-sourced (made from 100% cellulose) and certified home compostable, very highly parchmented GVP grades can be more brittle and fragile due to being very highly converted, which makes them relatively sensitive to wrinkles and tears. This may limit the use of highly parchmented GVP grades in some packaging applications, especially those that require the sheet to be formed into a desired shape to contain food. They may also be somewhat difficult to handle in converting equipment running at higher web loads.

[0006] Furthermore, very highly sheepskinned GVP grades require very specific manufacturing processes to provide 3 / m2 / day oxygen transmission rate (OTR) value, and may lead to a large amount of waste and low production efficiency in the production process. Therefore, it is necessary to propose an improved process and product to achieve high OTR, simplify the manufacturing process and reduce the amount of waste.

[0007] WO 2018 / 197676 A1 describes a multilayer article comprising a vegetable parchment carrier and an oxygen barrier layer containing polyvinyl alcohol (PVOH).

[0008] When coating GVP with oxygen barrier coatings such as PVOH, polyvinylidene chloride (PVdC), the OTR properties obtained are not always satisfactory, either due to the sensitivity of the coating to the use conditions (PVOH is sensitive to moisture) or due to environmental issues (PVdC). When GVP is laminated with oxygen barrier layers such as polymer layers (e.g. polyolefin extrusion coating), barrier properties can be imparted, but these methods involve additional processing stages and have a negative impact on the product's life cycle. In other words, lamination with polyolefins has a very negative impact on the sustainability of the packaging material (low bio-sourced content and no active end-of-life scheme).

[0009] Furthermore, vapor deposition can also be used to coat the GVP. Although metallization or other vapor phase processes allow excellent barrier properties to be imparted with very little raw material, these processes are very expensive and are usually done under specific vacuum conditions, which requires an external conversion step. Moreover, if a paper substrate is used, an additional coating step is required before metallization to improve the surface roughness. In fact, without such additional coating, the paper substrate may swell due to moisture and the metal coating may crack and lose its barrier properties. In addition to having a strong impact on the packaging costs, the life cycle of these processes remains to be discussed.

[0010] In summary, to obtain the desired oxygen barrier properties, specialized process conditions or the use of non-biodegradable materials are required.

[0011] Therefore, the object of the present invention is to provide an improved biodegradable packaging material having very good oxygen barrier properties and excellent mechanical properties, such as tear strength, wet burst strength and dry burst strength. A further object of the present invention is to provide a biodegradable packaging material that is easy to manufacture in an energy-saving and waste-reducing manner and at low cost.

[0012] Compared to the prior art paper taught in WO 2021 / 089778 A1, the present invention has better mechanical properties and can be produced in a more efficient manner due to the parchment paper used as a substrate having a lower parchmentization level and a thin non-continuous oxygen barrier coating formed thereon. Compared to existing multi-layer products comprising a parchment base paper and an oxygen barrier coating, the present invention provides a fully compostable material having better oxygen barrier properties due to a thin non-continuous coating made of a water-soluble polymer and / or a water-dispersible polymer. Summary of the invention

[0013] The present invention solves the problems of the prior art in the following ways.

[0014] In a first aspect, the present invention relates to a barrier paper comprising parchment paper as a substrate and a non-continuous coating layer formed on a surface of the substrate, wherein the non-continuous coating layer is made of at least one of a water-soluble polymer and a water-dispersible polymer.

[0015] It has been found that a non-continuous coating of a water-soluble polymer and / or a water-dispersible polymer applied to parchment paper solves the problems of the prior art by providing a biodegradable barrier paper having excellent oxygen barrier properties while exhibiting advantageous mechanical properties.

[0016] In a second aspect, the present invention relates to a method for producing barrier paper, the method comprising applying at least one water-soluble polymer or water-dispersible polymer to the surface of parchment paper as a substrate to form a non-continuous coating.

[0017] Thus, an additional advantage of the present invention is that the barrier papers described herein may be produced in a sustainable and more efficient manner and may reduce waste and production costs compared to prior art procedures.

[0018] In a third aspect, the present invention relates to a packaging material for oxygen sensitive products, the packaging material comprising the barrier paper described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a cross-sectional view of uncoated parchment paper under a scanning electron microscope (SEM). DETAILED DESCRIPTION

[0020] The present invention relates to a barrier paper comprising parchment paper as a substrate and a non-continuous coating layer formed on the surface of the substrate, wherein the non-continuous coating layer is made of at least one of a water-soluble polymer and a water-dispersible polymer.

[0021] In the context of the present invention, the following definitions and test methods apply.

[0022] The expression "biodegradable" is usually defined in accordance with standard EN 13432. When applied to a material or a product, the expression "biodegradable" means that the material or the entire product will biodegrade and disintegrate. "Biodegradation" means that the chemical structure or material breaks down under the action of microorganisms, while "disintegration" means that the material or the product made therefrom will physically break down into small, visually indistinguishable fragments at the end of a typical composting cycle.

[0023] The term "parchment" or "pure vegetable parchment (GVP)" refers to a material comprising primarily cellulose that has been subjected to a parchmenting process. Cellulosic materials are derived from artificial sources, such as regenerated cellulose fibers or films, or from natural sources, such as fibers or pulps from woody or non-woody plants. In the parchmenting process, a cellulose paper is treated with a gelling agent comprising, for example, sulfuric acid, under conditions that limit the reaction time between the gelling agent and the cellulose to control the dissolution, hydrolysis, and degradation of the cellulose. The treated paper is then washed thoroughly to remove the gelling agent and then dried. The bath chemicals partially dissolve or gel the cellulose in the paper. When the bath chemicals are diluted by washing the treated paper, the dissolved cellulose subsequently precipitates. This process is called parchmenting or parchmentizing, and results in a very hard, strong, smooth paper whose appearance somewhat resembles that of real parchment. Because paper treated in this manner has a tendency to become brittle and wrinkle when dried, it is sometimes treated with a plasticizer such as glycerol, glucose, or sorbitol. Vulcanized fiber is a related product made by treating cellulose paper with a gelling agent comprising, for example, zinc chloride.The surface of parchment paper or GVP typically has small cracks and grooves formed therein, which may give rise to a certain average surface roughness.

[0024] The term "discontinuous coating" refers to a coating formed on the surface of a substrate, which provides discontinuous coverage of the surface. This means that although the discontinuous coating is evenly distributed over the entire surface of the substrate, it may be applied in an amount that is insufficient to form a continuous coating. In the present invention, the discontinuous coating does not necessarily cover the entire surface area of ​​the substrate, but can represent a partial coating, as long as the discontinuous coating fills the cracks and grooves on the surface of the substrate. Some parts of the surface can remain exposed without being covered by the coating. The cracks and grooves filled with the discontinuous coating are evenly distributed over the entire surface area of ​​the substrate, thereby forming a more uniform surface (having a surface roughness reduced than the substrate used).

[0025] The term "water-soluble polymer" refers to a polymer that is substantially soluble in water, i.e., a polymer that forms a substantially uniform solution with water by dissolving therein. The water-soluble polymers described herein are completely dissolved before use. Examples of water-soluble polymers are carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), polyvinyl alcohol, and cationic starch.

[0026] The term "water-dispersible polymer" refers to a polymer that is substantially insoluble in water but can be mixed with water to form a heterogeneous mixture, which can be a dispersion or an emulsion. Examples of water-dispersible polymers are acrylic latex, styrene-butadiene latex, styrene acrylic latex, starch, and biopolyesters such as polylactic acid (PLA), polyhydroxybutyrate (PHB), polyhydroxyalkanoate (PHA), or mixtures thereof.

[0027] The "oxygen transmission rate (OTR)" of a material refers to the oxygen transmission rate (OTR) of a material through a specified area (m2) of the material during one day at an atmospheric pressure of 1.013 bar (1 atm), a temperature of 23°C and a relative humidity of 50%. 2 ) of oxygen (cm 3 ). Oxygen Transmission Rate (OTR) (cm 3 / m2 / day) is measured according to ASTM D 3985 and ASTM F 1927. Unless otherwise stated, the OTR described herein is measured on an OX-TRAN 2 / 22 device (supplier: MOCON), which complies with the ASTM D3985 standard. The OTR of a material is a measure of the oxygen barrier properties of the material and indicates the gas barrier level. In other words, the lower the OTR of a material, the smaller the amount of gas transmitted through the material, which makes the material provide a high barrier to gases, especially oxygen.

[0028] As described above, the first aspect of the present invention relates to a barrier paper, the barrier paper comprising parchment as a substrate, the parchment having a non-continuous coating made of at least one of a water-soluble polymer and a water-dispersible polymer formed on the surface thereof. The inventors surprisingly found that when the parchment is coated with a water-soluble polymer and / or a water-dispersible polymer to obtain a non-continuous coating, the barrier paper has high oxygen barrier properties and excellent mechanical properties at the same time. When the parchment is coated with 1.5 g / m 2 or less, preferably 0.05 g / m 2 Up to 1.5g / m 2 , more preferably 0.2 g / m 2 Up to 1.0g / m 2 When the parchment paper is coated with the water-soluble polymer and / or water-dispersible polymer, the oxygen barrier properties are particularly excellent.

[0029] An important aspect of the present invention is the discovery that forming a non-continuous coating on the surface of parchment paper is sufficient to significantly improve its oxygen barrier properties. Figure 1 As shown, the surface of parchment paper usually contains certain irregularities, such as cracks and grooves, which reduce the oxygen barrier properties of the parchment paper. It is believed that the high oxygen barrier properties of the barrier paper according to the present invention are due to the non-continuous coating filling the irregularities present in the surface of the parchment paper used as the substrate.

[0030] Another key aspect of the present invention is the discovery that parchment paper with high to moderate parchmentization levels and insufficient oxygen barrier properties can be suitably used as a substrate for barrier paper before coating with a discontinuous coating. In particular, when using parchment paper with low oxygen barrier properties as a substrate, improved oxygen barrier properties can be obtained by coating such parchment paper with a discontinuous coating made of a water-soluble polymer and / or a water-dispersible polymer.

[0031] Therefore, the barrier paper described herein can be advantageously used as a barrier layer for constructing highly air- and moisture-impermeable packaging materials, especially as packaging materials for oxygen-sensitive items. In addition, since the barrier paper described herein has excellent mechanical properties in terms of tear strength, wet burst strength, and dry burst strength, it can also be used as a reinforcing layer for the construction of packaging materials, especially for packaging with a predetermined shape.

[0032] The present invention provides a fully biodegradable, compostable and bio-sourced product, which consists essentially of cellulose and acts as an oxygen barrier as well as a reinforcing layer. Since parchment paper with a lower parchmentization level can be used as the base paper, the energy required during the parchmentization in the production process can be saved, and the waste produced during the production can be reduced, making the production process more efficient and cheaper.

[0033] Substrate

[0034] The parchment used as the substrate may be pure vegetable parchment (GVP).In a preferred embodiment, the parchment is substantially made of short fiber pulp.

[0035] The parchment used as substrate preferably comprises at least 50%, and even more preferably at least 80% cellulose. In a preferred embodiment, the parchment consists of 100% cellulose, making the parchment completely bio-derived and completely biodegradable / compostable. Therefore, the parchment preferably contains no more than 5 wt.% of non-compostable materials or materials of uncertain compostability, to meet the requirements of the EN 13432 standard. Most preferably, any additives added to the cellulose fiber-based sheet are compostable.

[0036] The OTR of parchment paper used as a substrate is preferably less than 10,000 cm 3 / m2 / day, more preferably less than 5000cm 3 / m2 / day, even more preferably less than 1000cm 3 / m2 / day, as measured at 23°C and 50% relative humidity. When using OTR over 10,000cm 3 / m2 / day parchment paper as the substrate, the OTR value of the resulting barrier paper may not be low enough to be suitable for packaging oxygen sensitive items. Under the same basis weight, the higher the OTR of the parchment paper, the lower its parchment level. For example, the OTR is about 5000-150,000cm 3 / m2 / day parchment with low parchment level (e.g. Ahlstrom Sulpack manufactured by ), OTR is about 150-3000cm 3 / m2 / day of parchment with a medium parchment level (e.g. Ahlstrom Sulflex manufactured by ), and OTR is 10cm 3 / m2 / day or less has a very high parchment level (e.g. Ahlstrom PureBarrier manufactured by ).

[0037] Very highly vellumed parchments (such as PureBarrier) can show less than 10cm 3 / m2 / day. However, when the parchment level is increased, the mechanical properties of the parchment paper decrease, because very high parchment levels make the paper more brittle and sensitive to cracking. By combining parchment paper with a high to medium parchment level with a discontinuous coating, the decrease in mechanical properties can be avoided and a barrier paper with significantly better mechanical properties (for example in terms of tear resistance) as well as with excellent oxygen barrier properties can be obtained.

[0038] The average Bekk smoothness of the parchment used as the substrate is preferably 4.0s to 20.0s, more preferably 5.0s to 16.0s. When having an average Bekk smoothness within this range, a non-continuous coating can be formed on the surface of the parchment, so that the unevenness (cracks and grooves) present in the surface of the parchment is filled with the coating, and a more uniform thickness profile can be obtained. Therefore, the OTR of the resulting barrier paper can be advantageously reduced. The average Bekk smoothness of the parchment used as the substrate can be measured according to the Bekk roughness determination method ISO 5627:1995. The average Bekk smoothness can be determined using a Buchel 131ED device.

[0039] The profile roughness parameters of the parchment paper used as the substrate are preferably as follows: It is preferred that the -Ra value of the parchment paper substrate is less than 6 μm, preferably 1 μm to 6 μm, and more preferably 1 μm to 4 μm;

[0040] - Rq value is less than 15 μm, preferably 2 μm to 15 μm, and more preferably 2 μm to 10 μm; and

[0041] - Rz value is less than 35 μm, preferably 5 to 35, and more preferably 5 to 25.

[0042] The Ra value is the arithmetic mean of the deviations of the profile height from the mean line, the Rq value is the root mean square mean of the deviations of the profile height from the mean line, and the Rz value is the maximum peak-to-valley height of the profile within a single sampling length. The lower the Ra value, the Rq value, and the Rz value, the more uniform the thickness profile of the substrate. Since OTR is a function of thickness, it is preferred to have a relatively constant thickness profile to minimize the appearance of weak points. The profile roughness parameters Ra, Rq, and Rz can be measured using a surface roughness tester according to the EN ISO 4287 standard.

[0043] The basis weight of the parchment paper used as the substrate can be selected according to the composition of the fibers and / or filaments and the intended end use. In some embodiments, the basis weight of the parchment paper on a dry basis can be 200 gsm or less, preferably 30 gsm to 130 gsm, more preferably 45 gsm to 115 gsm. When the basis weight of the parchment paper is within these ranges, the barrier paper obtained thereby has excellent mechanical properties and provides excellent barrier properties.

[0044] From the viewpoint of achieving excellent mechanical reinforcement characteristics, the average thickness of parchment paper used as the substrate is generally 30 μm to 200 μm, preferably 35 μm to 140 μm, even more preferably 45 μm to 120 μm.

[0045] From the viewpoint of achieving excellent oxygen barrier properties, the density of the parchment paper used as the substrate is preferably at least 800 kg / m 3 , more preferably 800kg / m 3 Up to 1200kg / m 3 , even more preferably 850kg / m 3 Up to 1150kg / m 3 In fact, the higher the density, the smaller the pore volume. Therefore, by applying a discontinuous coating, satisfactory OTR values ​​can be achieved.

[0046] Typically, parchment paper will not include binders and other additives. However, additives may be used to achieve a specific desired result. For example, a softener such as glycerol may be added to make the parchment less brittle, or a granular material such as TiO may be added. 2 Fillers such as cellulose and / or polypropylene may be added to change the opacity of the parchment, or pigments may be added to change the color of the parchment. Preferably, the parchment contains no more than 5 wt.% of non-compostable materials or materials of uncertain compostability to meet the requirements of the EN 13432 standard. Most preferably, any additives added are biodegradable and / or compostable.

[0047] Discontinuous coating

[0048] A discontinuous coating is formed on the surface of the substrate. Preferably, the coating is 1.5 g / m 2 Apply a discontinuous coating in very light amounts (i.e., up to 1.5 g / m 2 A coating of 0.1 g / m 2 is sufficient to obtain excellent oxygen barrier properties. A small amount of coating can be applied, since it is sufficient that cracks and grooves present in the surface of the parchment are at least partially filled with the coating. In a further preferred embodiment, the discontinuous coating is applied in an amount of 0.1 g / m 2. 2 Up to 1.5g / m 2 , more preferably 0.1 g / m 2 Up to 1.0g / m 2 , even more preferably 0.1 g / m 2 Up to 0.5g / m 2 , and most preferably 0.2 g / m 2 Up to 0.3g / m 2 The barrier paper is applied in an amount of 1000 g / cm2 to fill the unevenness present in the surface of the parchment paper used as the substrate, so that the resulting barrier paper has a smoother surface, i.e., a surface with a reduced profile roughness parameter. The profile roughness parameter can be reduced by about 10% to 20%, further minimizing the occurrence of weak points. Thus, the barrier paper has a thickness of less than 10 cm2. 3 Low OTR of / m2 / day.

[0049] The non-continuous coating is made of at least one of a water-soluble polymer and a water-dispersible polymer.

[0050] The water-dispersible polymer is not particularly limited as long as it is dispersible under the conditions of use. The water-dispersible polymer is preferably at least one selected from the following: acrylic latex, styrene-butadiene latex, styrene acrylic latex, starch, and biopolyesters such as polylactic acid (PLA), polyhydroxybutyrate (PHB), polyhydroxyalkanoate (PHA), or mixtures thereof. In a preferred embodiment, the water-dispersible polymer is acrylic latex.

[0051] The water-soluble polymer is not particularly limited as long as it is completely soluble under the conditions of use. The water-soluble polymer is preferably at least one selected from the group consisting of carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), polyvinyl alcohol (PVOH) and cationic starch. In a more preferred embodiment, the water-soluble polymer is CMC.

[0052] Although CMC is typically used as a thickener additive for coating compositions, the inventors surprisingly discovered that CMC can be used as a thin non-continuous coating of a GVP to produce high OTR characteristics. The non-continuous coating preferably contains 50 wt% or more CMC, more preferably 80 wt% CMC, and even more preferably 100 wt% CMC. Very high OTR characteristics can be obtained when the non-continuous coating is made primarily or even entirely of CMC.

[0053] The molecular weight (Mw) of CMC is preferably 100,000 g / mol to 750,000 g / mol, preferably 100,000 g / mol to 400,000 g / mol. The Mw of CMC can be adjusted by both the raw material selection and the conditions of its manufacturing process.

[0054] The Mw of CMC has a critical influence on the coating composition. When the Mw is below 100,000 g / mol, this results in a lower viscosity of the CMC, which makes its application easier but reduces the oxygen barrier properties of the resulting barrier paper. When the Mw is above 750,000 g / mol, this results in a higher viscosity of the CMC, which makes its application on the surface of the substrate problematic, while there is no gain in OTR properties. Therefore, from the point of view of selecting the best compromise between rheology and OTR properties, it is preferred to use CMC with an Mw in the range mentioned above.

[0055] The OTR properties of the barrier paper can be further enhanced by adding a softener such as glycerol to the discontinuous coating composition. The softener helps to form a more uniform discontinuous coating that uniformly fills the unevenness in the surface of the substrate and avoids the formation of additional cracks, thereby further enhancing the oxygen barrier properties of the obtained barrier paper. In a preferred embodiment, the discontinuous coating composition includes less than 20% by weight of glycerol relative to the total dry weight of the discontinuous coating composition.

[0056] The OTR properties of the barrier paper can also be further enhanced by adding processing aids such as salt to the discontinuous coating composition. Salt can reduce the viscosity of the composition and help spread the coating more evenly. This enhances the oxygen barrier properties of the barrier paper obtained. In a preferred embodiment, the discontinuous coating composition includes less than 5% by weight of salt, such as calcium chloride, relative to the total amount of the discontinuous coating composition.

[0057] Barrier paper

[0058] The barrier paper according to the present invention comprises parchment paper as a substrate and a discontinuous coating layer formed on the surface of the substrate. Due to the discontinuous coating layer of a water-soluble polymer and / or a water-dispersible polymer applied to the surface of the parchment paper substrate, a biodegradable barrier paper having excellent oxygen barrier properties and exhibiting favorable mechanical properties is provided.

[0059] The OTR of the barrier paper is preferably 0.05 cm due to the non-continuous coating applied thereto. 3 / m2 / day to 20.0cm 3 / m2 / day, more preferably 0.05cm 3 / m2 / day to 5.0cm 3 / m2 / day.

[0060] According to the construction of the barrier paper of the present invention, sufficient oxygen barrier properties can be obtained even when parchment paper having a relatively low parchmentization level and concomitant low gas barrier properties is used as a substrate.

[0061] Method for producing barrier paper

[0062] In a second aspect, the present invention relates to a method for making a barrier paper, the method comprising applying at least one water-soluble polymer or water-dispersible polymer to the surface of parchment paper as a substrate to form a non-continuous coating.

[0063] The OTR of parchment paper used as a substrate is preferably less than 10,000 cm 3 / m2 / day, more preferably less than 5000cm 3 / m2 / day, even more preferably less than 1000cm 3 / m2 / day. In addition, it is preferred that the OTR of the parchment paper used as the substrate is not less than 150cm 3 / m2 / day. When used to show at least 150cm 3 When a parchment with an OTR of 0.1% to 0.2% / m2 / day is used as the substrate (i.e. a parchment with a medium to high parchmentization grade), the production of the substrate is easier and more efficient because no excessive parchmentization treatment is required, which is required to obtain parchment with a very high parchmentization grade.

[0064] The water-soluble polymers and / or water-dispersible polymers as well as the amounts thereof as described previously can be used in the method for producing barrier paper according to the invention.

[0065] The step of applying the water-soluble polymer and / or water-dispersible polymer to the surface of the parchment substrate is preferably carried out using a pressure of 300 kPa or more, more preferably 500 kPa to 2000 kPa. This can be accomplished, for example, using a size press process, a film pressing process, or a pressure infiltration process. A subsequent calendering step may also be optionally included. Calendering can help to homogenize the thickness of the barrier paper and increase its density, thereby improving the oxygen barrier properties. Optionally, a calendering step may also be performed before the coating step to improve the surface properties of the substrate.

[0066] When the water-soluble polymer and / or water-dispersible polymer is applied using a pressure of at least 300 kPa, the water-soluble polymer and / or water-dispersible polymer can better penetrate into the cracks and grooves present in the surface of the parchment paper substrate, thereby better (more uniformly) forming a non-continuous coating. As a result, the barrier paper obtained has higher oxygen barrier properties.

[0067] Packaging Materials

[0068] In a third aspect, the present invention relates to a packaging material for oxygen sensitive products, the packaging material comprising the barrier paper described herein.

[0069] The packaging material is not particularly limited and can be used to store oxygen-sensitive items, such as oxygen-sensitive foods or oxygen-sensitive life science and diagnostic devices. The packaging material for oxygen-sensitive foods can be, for example, selected from the group consisting of: butter packaging, beverage containers, coffee capsules, coffee cakes, chocolate packaging and biscuit packaging. Preferably, the packaging material is used for the construction of coffee capsules, more preferably for the cover of coffee capsules. The packaging material for oxygen-sensitive life science and diagnostic devices can be, for example, selected from the group consisting of: test kit packaging, biological sample collection and preservation card packaging, laboratory test filter packaging, test pad packaging and DNA / RNA extraction medium packaging.

[0070] The packaging material comprises a barrier paper and optionally an additional layer. That is, the packaging material may be a multilayer product comprising a barrier paper as a first material layer and at least one additional material layer, wherein the at least one additional material layer is laminated on the surface of the barrier paper. The additional layer is not particularly limited and may be appropriately selected according to the desired additional properties that the packaging material should complement. The additional layer is preferably selected from the group consisting of: a water vapor barrier layer, an aroma barrier layer, a waterproof layer, a heat sealable layer, a grease resistant layer, a finishing varnish layer and a printable layer.

[0071] Example

[0072] The properties of the parchment paper used in this example and the barrier paper prepared in this example were measured according to the following methods.

[0073] The oxygen transmission rate (OTR) has been measured according to ASTM D 3985 on an OTR measuring device "OX-TRAN 2 / 22" (produced by MOCON).

[0074] The wet bursting strength has been measured according to ISO 3689 and the dry bursting strength has been measured according to ISO 2758.

[0075] The average Becker smoothness has been measured according to the Becker roughness determination method ISO 5627:1995.

[0076] The profile roughness parameters Ra, Rq and Rz have been measured using a surface roughness tester according to the EN ISO 4287 standard on a surface roughness tester Mitutoyo (Surftest SJ-210 [mm], “R2 μm; 0,75 mN”).

[0077] The following raw materials were used in this example.

[0078] Substrate :

[0079] Table 1 shows the substrates used in this example and the comparative example.

[0080] Table 1

[0081]

[0082] Discontinuous coating:

[0083] (i) Water-soluble polymers:

[0084] ● "CMC FinnFix 300" (produced by Nouryon), which is an aqueous solution containing 2.3 wt% carboxymethyl cellulose and has a Mw of about 180,000 g / mol

[0085] ● "PVOH AQ 4104" (produced by Kuraray), which is an aqueous solution containing 3.2% by weight of polyvinyl alcohol

[0086] ● "PVOH Mowiol 28 / 99" (produced by Kuraray), which is an aqueous solution containing 2.6% by weight of polyvinyl alcohol

[0087] "Cationic starch HiCat 5213A" (produced by Roquette), which is an aqueous solution containing 2.5% by weight of cationic starch

[0088] "Cationic starch Perfectafilm X115" (produced by Avebe), which is an aqueous solution containing 3.1% by weight of cationic starch

[0089] (ii) Water-dispersible polymers:

[0090] ● "Acrylic Latex Rhobarr 135" (produced by Dow), which is an aqueous acrylic emulsion containing 40% by weight solids; the emulsion was diluted to a solids content of 2.5% by weight to give a low coating weight

[0091] Example 1: Base paper type evaluation

[0092] As shown in Table 2, the oxygen barrier properties of different types of base papers have been evaluated, the base papers being either uncoated or coated with 0.3 g / m 2 The coating was carried out using CMC FinnFix 300 (Examples 1.1 to 1.3 and Comparative Examples 1.1 and 1.2).

[0093] Table 2

[0094]

[0095] Applying CMC coating to Cristal TM Paper and Cristalline TM The oxygen barrier properties of these substrate papers are not significantly affected by the CMC coating on paper (see Comparative Examples 1.1 and 1.2). However, such an effect can be observed when a CMC coating is applied to parchment paper. The OTR of parchment paper with a medium to high parchmentization level can be advantageously reduced by applying a thin CMC coating thereto (see Examples 1.1 to 1.3). The reduction in OTR is particularly evident in papers with a medium to high parchmentization level (see Examples 1.1 and 1.2). PureBarrier 70, which has a very high parchmentization level, already has a low OTR from the beginning, making the reduction in its OTR value not so significant (see Example 1.3).

[0096] Example 2: Evaluation of coating types

[0097] As shown in Table 3, the surface of Sulflex 70 used as the parchment paper substrate was treated with 0.3 g / m 2 The oxygen barrier properties of different types of applied discontinuous coatings were evaluated.

[0098] Table 3

[0099] Coating materials <![CDATA[OTR(cm 3 / m 2 / day)]]> Example 2.1 CMC FinnFix 300 0.34 Example 2.2 PVOH Kuraray AQ 4104 4.3 Example 2.3 PVOH Kuraray Mowiol 28 / 99 0.4 Example 2.4 Cationic starch Roquette HiCat 5213A 2.3 Example 2.5 Cationic starch Perfectafilm X115 3.1 Example 2.6 Acrylic Latex Rhobarr 135 0.8

[0100] From the results of Examples 2.1 to 2.6, it can be seen that excellent oxygen barrier properties can be obtained when a thin layer of water-soluble polymer or water-dispersible polymer is applied to the surface of a parchment substrate due to the formation of a non-continuous coating.

[0101] Example 3: Evaluation of Mechanical Properties of Barrier Paper

[0102] As shown in Table 4, the mechanical properties of different barrier papers have been evaluated.

[0103] Table 4

[0104]

[0105]

[0106] MD = Machine Direction

[0107] CD = Cross direction

[0108] It is clear from the results shown in Table 4 that the use of parchment paper with a high parchment level (see reference example 3.1) enables barrier papers to have improved mechanical properties, especially in terms of dry burst strength, wet burst strength and tear strength, compared to the use of parchment paper with a very high parchment level (PureBarrier 70, see reference example 3.2). Therefore, when seeking to achieve both excellent mechanical properties and high oxygen barrier properties, it is advantageous to use parchment paper that has not been overly parchmented and to apply a thin layer of non-continuous coating to it (see example 3.1).

[0109] Example 4: Evaluation of the pressure used when applying a non-continuous coating

[0110] When a 2.3 wt% CMC coating solution (target coating weight = 0.3 g / m2) was used in the pilot scale sheepskinning apparatus without using any pressure (i.e., only about 20 kg of the pilot scale sheepskinning apparatus roll weight was used), the coating was then dried using a 2.3 wt% CMC coating solution (target coating weight = 0.3 g / m2). 2 ) The CMC coating was applied to an initial OTR value of 750 cm 3 / m2 / day Sulflex 70 surface as parchment paper substrate, the OTR of the barrier paper obtained is 300cm 3 / m2 / day to 500cm 3 / m2 / day. However, when using a pressure of 5 bar in a laboratory size press, a pressure of 1 cm 3 / m2 / day to 3cm 3 / m2 / day OTR, and when using pressures above 10 bar in industrial processes, 0.2cm 3 / m2 / day to 0.6cm 3Therefore, when a sufficient pressure of, for example, 300 kPa or higher is used to form a non-continuous coating, a barrier paper with higher oxygen barrier properties can be obtained.

[0111] Example 5: Evaluation of profile roughness parameters

[0112] The profile roughness parameters of the uncoated and coated parchment papers from Example 1.3 were measured as reported in Table 5. The discontinuous coating reduced the profile roughness parameter by 10% to 20%, thereby improving the thickness profile of the barrier paper.

[0113] Table 5

[0114]

Claims

1. A barrier paper, comprising: Parchment paper, the parchment paper serving as a substrate; and a discontinuous coating formed on the surface of the substrate, The discontinuous coating is made of at least one of a water-soluble polymer and a water-dispersible polymer.

2. The barrier paper according to claim 1, wherein the discontinuous coating has a thickness of 1.5 g / m 2 or less, preferably 0.1 g / m 2 Up to 1.5g / m 2 , more preferably 0.1 g / m 2 Up to 1.0g / m 2 , and even more preferably 0.1 g / m 2 Up to 0.5g / m 2 An amount of is formed on the surface of the substrate.

3. The barrier paper according to claim 1 or 2, wherein the oxygen transmission rate of the parchment paper used as the substrate is less than 10,000 cm 3 / m 2 / day, preferably less than 5000cm 3 / m 2 / day, more preferably less than 1000cm 3 / m 2 / day, as measured at 23°C and 50% relative humidity.

4. The barrier paper according to any one of claims 1 to 3, wherein the water-soluble polymer is at least one selected from the group consisting of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol and cationic starch, and the water-dispersible polymer is at least one selected from the group consisting of acrylic latex, styrene-butadiene latex, styrene acrylic latex, starch and biopolyesters such as polylactic acid (PLA), polyhydroxybutyrate (PHB) or polyhydroxyalkanoate (PHA).

5. The barrier paper according to any one of claims 1 to 4, wherein the discontinuous coating comprises 50 wt% or more carboxymethyl cellulose, preferably 80 wt% or more carboxymethyl cellulose.

6. The barrier paper according to claim 5, wherein the molecular weight of the carboxymethyl cellulose is 100,000 g / mol to 750,000 g / mol, preferably 100,000 g / mol to 400,000 g / mol.

7. The barrier paper according to any one of claims 1 to 6, wherein the parchment paper used as the substrate has an average Bekk smoothness of 4.0 s to 20.0 s as measured according to Bekk roughness determination method ISO 5627:1995.

8. The barrier paper according to any one of claims 1 to 7, wherein the parchment paper used as the substrate has an Ra value of less than 6 μm, preferably from 1 μm to 6 μm, and more preferably from 1 μm to 4 μm, The Rq value is less than 15 μm, preferably 2 μm to 15 μm, and more preferably 2 μm to 10 μm, and The Rz value is less than 35 μm, preferably 5 μm to 35 μm, and more preferably 5 μm to 25 μm, wherein the Ra value, the Rq value and the Rz value are measured according to EN ISO 4287.

9. The barrier paper according to any one of claims 1 to 8, wherein the oxygen permeability of the barrier paper is 0.05 cm 3 / m 2 / day to 20.0cm 3 / m 2 / day, preferably 0.05cm 3 / m 2 / day to 5.0cm 3 / m 2 / sky.

10. A method for producing barrier paper, the method comprising: At least one water-soluble polymer or water-dispersible polymer is applied to the surface of parchment paper as a substrate to form a non-continuous coating.

11. The method for producing barrier paper according to claim 10, wherein the at least one water-soluble polymer or water-dispersible polymer is added in an amount of 1.5 g / m 2 or less, preferably 0.1 g / m 2 Up to 1.5g / m 2 , more preferably 0.1 g / m 2 Up to 1.0g / m 2 , and even more preferably 0.1 g / m 2 Up to 0.5g / m 2 An amount of is applied to the surface of the parchment substrate.

12. The method for producing barrier paper according to claim 10 or 11, wherein the oxygen transmission rate of the parchment paper used as the substrate is less than 10,000 cm 3 / m 2 / day, preferably less than 5000cm 3 / m 2 / day, more preferably less than 1000cm 3 / m 2 / day, as measured at 23°C and 50% relative humidity.

13. The method for producing a barrier paper according to any one of claims 10 to 12, wherein the at least one water-soluble polymer or water-dispersible polymer is applied to the surface of the parchment paper substrate using a pressure of 300 kPa or more, preferably 500 kPa to 2000 kPa.

14. The method for producing a barrier paper according to any one of claims 10 to 13, wherein the water-soluble polymer is at least one selected from the group consisting of carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyvinyl alcohol and cationic starch, and the water-dispersible polymer is at least one selected from the group consisting of acrylic latex, styrene-butadiene latex, styrene acrylic latex, starch and biopolyesters such as polylactic acid (PLA), polyhydroxybutyrate (PHB) or polyhydroxyalkanoate (PHA), preferably wherein the discontinuous coating comprises 50 wt% or more of carboxymethyl cellulose, more preferably 100 wt% of carboxymethyl cellulose.

15. A packaging material for oxygen sensitive products, the packaging material comprising the barrier paper according to any one of claims 1 to 9.

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