Polypropylene coated paper and board

Abstract

The present invention relates to a paper or paperboard containing cellulose fibers, the paper or paperboard comprising at least one coating layer formed by extrusion coating with PP (polypropylene) resin, the PP resin having a viscosity of 890 to 910 kg / m 3 (determined in accordance with ISO 1183), a melting temperature (determined in accordance with ISO 11357-3) in the range of 155 to 170°C, and a melt flow rate (230°C / 2.16 kg) (determined in accordance with ISO 1133) in the range of 10 to 15 g / 10 min, wherein the PP resin is 30 g / m 2 It is characterized by being applied to paper or paperboard in amounts of less than 1 g.

Description

[Technical field]

[0001] Technical Field The present disclosure relates to polymer-coated paper and paperboard. More specifically, the present disclosure relates to paper or paperboard that includes at least one coating layer formed by extrusion coating of polypropylene (PP) resin. [Background technology]

[0002] background Coating paper or paperboard with plastics is often employed to combine the mechanical properties of paperboard with the barrier and sealing properties of plastic films. Paperboard coated with relatively small amounts of the appropriate plastic material can provide the necessary properties to make it suitable for many demanding applications.

[0003] Extrusion coating is the process of applying molten plastic material to a substrate such as paper or paperboard in a very thin, smooth, uniform layer. The coating may be formed by the extruded plastic itself, or the molten plastic may be used as an adhesive to bond a solid plastic film to the substrate. Common plastic resins used in extrusion coating include polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).

[0004] Paper and paperboard are generally suitable for packaging dry products. However, untreated paperboard is limited in its applications in direct contact with wet or oily products because moisture affects the mechanical properties of the packaging and absorbed oils can cause stains on the paper. These effects impair not only the protective function of the packaging but also its appearance.

[0005] Extrusion coatings can be used, for example, to provide moisture resistance, water vapor, oxygen, and aroma barrier properties, stain resistance, oil resistance, heat sealability, and / or to impart a desired finish or texture to a substrate surface.

[0006] Extrusion coating and lamination greatly expand the range of uses for paper and paperboard. A thin plastic layer provides resistance to oils, oils, moisture, and in some cases heat resistance. Plastic coatings can also be used for heat sealing. Depending on the application, paper or paperboard can be extrusion coated on one or both sides.

[0007] One application in which the properties of extrusion coated or laminated paperboard are particularly useful is food containers intended for heating food in a microwave oven. In such microwave packs, the packaging material must be able to withstand high temperatures of moisture and oil without being absorbed by the paperboard. The high heating temperatures in a microwave oven, 150-160°C, require materials with high melting points and high heat resistance.

[0008] Polypropylene is known to have excellent properties for microwave packs, such as high grease resistance, heat sealability, and heat resistance at high temperatures. However, polypropylene has the disadvantage that it is relatively difficult to process by extrusion coating. For example, polypropylene coating is prone to pinholes, and if the coating weight is low, adhesion to the substrate is poor. For this reason, polypropylene is often mixed with polyethylene for processing.

[0009] For environmental and economic reasons, it is generally desirable to make plastic coatings as thin as possible, provided that the barrier and protective properties are acceptable. Generally, only a very thin layer is required to provide sufficient barrier and protective properties, as long as the coating is uniform and free of defects. However, further reduction in thickness (or grams) of plastic coatings is often limited by reduced adhesion and stability of the film formation during the extrusion process, and by the formation of pinholes. For example, conventional PP resins can be applied at approximately 30-40 g / m2 on paper or paperboard without a significant increase in the amount of pinholes formed in the coating. 2It cannot be extrusion coated at grams less than 100g. Pinholes are microscopic holes that may form in plastic films during the coating process. The main reasons for pinholes are substrate surface irregularities (e.g. high surface roughness or loose fibers), uneven distribution of coating or too low grams of coating. Pinholes affect the barrier properties of the film, e.g. moisture and CO2 barrier properties. This is important for product safety in high heat end uses, e.g. microwaveable applications.

[0010] When extrusion coating polypropylene with polyethylene, the pinhole problem at low coating grams remains unresolved.Therefore, there remains a need for improved solutions to reduce the PP coating grams while maintaining good barrier properties in PP extrusion coating. Summary of the Invention [Means for solving the problem]

[0011] Description of the Invention The objective of this disclosure is to provide a low gram weight, particularly 30 g / m 2 The objective of this invention is to reduce the problem of pinhole formation in the extrusion coating of paper and paperboard with PP at less than 1 g.

[0012] A further object of the present disclosure is to reduce the minimum grams of PP resin required in extrusion coating of paper and paperboard to achieve a useful coating, particularly in terms of moisture and CO2 barrier properties.

[0013] A further object of the present disclosure is to provide a method for reducing the grams of PP resin, e.g., to 30 g / m, while maintaining good moisture and CO2 barrier properties. 2 The present invention provides a method for producing PP resin coated paper or paperboard, which can reduce the number of grams, such as to less than 100 grams.

[0014] The above objectives, and other objectives which will be realized by those skilled in the art in light of the present disclosure, are accomplished by various aspects of the present disclosure.

[0015] According to a first aspect exemplified herein, there is provided a paper or paperboard comprising cellulose fibres, the paper or paperboard comprising at least one coating layer formed by extrusion coating of a PP (polypropylene) resin, the PP resin having a viscosity of 890 to 910 kg / m 3 (determined according to ISO 1183), a melting point (determined according to ISO 11357-3) in the range of 155 to 170 °C, and a melt flow rate (determined according to ISO 1133) in the range of 10 to 15 g / 10 min (230 °C / 2.16 kg), 2 The composition is characterized in that it is applied to paper or paperboard in amounts of less than 1 g.

[0016] Paper is a material generally made from wood pulp or other fibrous substances containing cellulose fibers, formed into thin sheets that can be used for writing or printing, or as packaging material.

[0017] Paperboard generally refers to a strong, thick paper or corrugated board containing cellulose fibers used for packaging such as boxes. Paperboard can be either bleached or unbleached, coated or uncoated, and can be produced in a variety of thicknesses depending on the end use.

[0018] The term coating as used herein means the operation of covering the surface of a substrate with a composition to impart a desired property, finish or texture to the substrate. The coating may be a single layer or a multi-layer coating in which the PP coating resin may be used in one or several layers. The coating may be applied to one or both sides of the paper or paperboard.

[0019] The problem of pinhole formation in low gram PP coatings is especially evident in the coating of paper and paperboard. The fibre-based substrate and its natural porosity and surface roughness seem to play a key role here. PP extrusion coatings for paper and paperboard-based microwave food containers today usually have a coating weight of at least 30-40 g / m 2 A coating weight of 100 grams is required, and usually higher weights are used. At lower coating weights, the number of pinholes in the coating increases significantly.

[0020] The inventors have now discovered that by using certain types of PP resins, the minimum grams of PP resin required to achieve pinhole free, or nearly pinhole free, coatings in extrusion coating of paper and paperboard can be significantly reduced.

[0021] Reducing pinhole formation is very important for product safety in high heat end uses where pinhole formation is a risk, i.e. microwave use. The solution of the present invention allows for the adjustment of moisture and CO2 barrier to a sufficient and desirable level at lower grams.

[0022] Additionally, the particular type of PP resin used in the present invention has been found to offer advantages over standard extrusion coating grades of PP, such as improved adhesion to paper or paperboard substrates at low grams, excellent runnability allowing for higher line speeds in the extrusion coating process, and improved heat sealability.

[0023] The PP resin used in the present invention has a density of 890 to 910 kg / m 3 (determined according to ISO 1183), a melting temperature in the range of 155-170°C (determined according to ISO 11357-3), and a melt flow rate (230°C / 2.16 kg) of 10-15 g / 10 min (determined according to ISO 1133).

[0024] The PP copolymer used in the present invention is a branched PP copolymer. Branching can be achieved by using specific catalysts, i.e. specific single-site catalysts, or by chemical modification. Branched polypropylene obtained by chemical modification is called high melt strength polypropylene. Preferably, the branched PP copolymer of the present invention is obtained by chemical modification and is therefore a high melt strength polypropylene (HMS-PP).

[0025] In some embodiments, the PP copolymer is a long-chain branched polypropylene (LCB-PP). Long-chain branched polypropylene generally refers to polypropylene that has been modified by the addition of long-chain branches. This modification can be achieved in a variety of different ways, for example, by reactive extrusion processes with the addition of multifunctional monomers and peroxides.

[0026] In some embodiments, the PP copolymer is 895 to 905 kg / m 3 in the range of 898 to 902 kg / m 3 It has a density in the range of

[0027] In some embodiments, the PP copolymer has a melting temperature in the range of 158-166°C, preferably in the range of 160-164°C.

[0028] In some embodiments, the PP copolymer has a melt flow rate (230° C. / 2.16 kg) in the range of 12-14 g / 10 min, preferably about 13 g / 10 min.

[0029] In some embodiments, the PP copolymer is subjected to visbreaking, which means reducing the molecular weight of polypropylene by mixing the molten polymer in an extruder with a free radical generator such as peroxide. Visbreaking is well known to those skilled in the art and described in the literature.

[0030] In a particular embodiment, the PP resin used in the present invention has a compressibility of about 900 kg / m3 In a further specific embodiment, the PP resin used in the present invention comprises at least 50% by weight of a branched PP copolymer having a density in the range of about 900 kg / m (determined according to ISO 1183), a melting temperature in the range of about 162° C. (determined according to ISO 11357-3), and a melt flow rate (230° C. / 2.16 kg) in the range of about 13 g / 10 min (determined according to ISO 1133). 3 in the range of about 162°C (determined in accordance with ISO 11357-3), and a melt flow rate (230°C / 2.16 kg) in the range of about 13 g / 10 min (determined in accordance with ISO 1133).

[0031] An example of a branched PP copolymer having such favorable properties is Daploy TM SF313HMS (Borealis AG) is one example. TM SF313HMS is a polypropylene copolymer with high melt strength, good heat resistance and excellent heat sealability.

[0032] The branched PP copolymers used in the present invention are generally more expensive than conventional extrusion coating grade polypropylene, however, because the grams of coating can be significantly reduced, branched PP copolymers can still provide a cost-effective alternative.

[0033] The PP resin of the present invention comprises at least 50% by weight of PP copolymer. In some embodiments, the PP resin comprises at least 70% by weight, preferably at least 90% by weight of PP copolymer. The PP resin of the present invention can also consist or essentially consist of PP copolymer. The embodiment in which the PP resin consists or essentially consists of PP copolymer is particularly interesting, since such a single material coating offers obvious recycling advantages.

[0034] The remainder of the PP resin may be composed of other polymeric or non-polymeric coating components. In other words, the PP resin may be a blend of a PP copolymer with other polymers. In some embodiments, the remainder of the PP resin may be composed of other polymeric or non-polymeric coating components. In some embodiments, the remainder of the PP resin may be composed of other polymers with a viscosity of 890 to 910 kg / m 3 (determined in accordance with ISO 1183), a melting temperature outside the range of 155-170 °C (determined in accordance with ISO 11357-3), and a melt flow rate outside the range of 10-15 g / 10 min (230 °C / 2.16 kg) (determined in accordance with ISO 1133).

[0035] For environmental and economic reasons, it is generally desirable to make plastic coatings as thin as possible while still maintaining acceptable levels of barrier and protective properties. The PP resins used in the present invention make it possible to prepare thin, pinhole-free PP coatings on paper and paperboard. In particular, the PP resins used in the present invention have a coating thickness of 30 g / m 2 In some embodiments, the PP resin allows for the preparation of thin, pinhole-free PP coatings on paper and paperboard with coating grams of less than 28 g / m. 2 Less than 26 g / m 2 less than 24 g / m 2 The coating is applied to the substrate in grams or less.

[0036] Coating resin formulations can vary widely depending on the application of the coating and the paper or paperboard being coated. Coating compositions can contain a wide range of ingredients in varying amounts to improve the final performance of the product or the processing of the coating. In some embodiments, the PP resin contains at least one additional ingredient selected from the group including polymers other than PP, pigments, dyes, and fillers.

[0037] The paper or paperboard of the present invention has a viscosity of 890 to 910 kg / m 3Alternatively, the paper or paperboard of the present invention may be coated only with a PP resin comprising at least 50 wt. % of a branched PP copolymer having a density in the range of 100° C. (determined according to ISO 1183), a melting temperature in the range of 155-170° C. (determined according to ISO 11357-3), and a melt flow rate (230° C. / 2.16 kg) in the range of 10-15 g / 10 min (determined according to ISO 1133). Alternatively, the paper or paperboard of the present invention may comprise a PP resin coating layer as one of two or more polymer coating layers. The PP resin of the present invention can provide a thin, pinhole-free PP coating on the paper or paperboard, and therefore can preferably be used as the first (or innermost) coating layer applied directly to the surface of the paper or paperboard. The extrusion coated PP resin coating layer can then serve to promote the adhesion of a subsequent applied or coextruded PP coating layer having a different composition than the first PP resin coating layer.

[0038] In some embodiments, the paper or paperboard further comprises at least one additional polymer coating layer disposed over the extrusion coated PP resin, the additional polymer coating layer having a different composition than the extrusion coated PP resin. In a preferred embodiment, the at least one additional coating layer comprises polypropylene (PP).

[0039] In some embodiments, the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

[0040] The paper or paperboard of the present invention is particularly useful for the manufacture of heat-resistant receptacles, such as food containers or trays. According to a second aspect exemplified herein, there is provided a heat-resistant receptacle, preferably a microwaveable food container, comprising the paper or paperboard defined above with reference to the first aspect.

[0041] According to the third embodiment exemplified in this specification, 890 to 910 kg / m 3In accordance with the present invention, there is provided a use of a PP resin comprising at least 50% by weight of a branched PP copolymer having a density in the range of 30 g / m2 (determined according to ISO 1183), a melting temperature in the range of 155 to 170°C (determined according to ISO 11357-3), and a melt flow rate in the range of 10 to 15 g / 10 min (230°C / 2.16 kg) (determined according to ISO 1133), for coating a paper or paperboard substrate comprising cellulose fibres, wherein the PP resin has a density in the range of 30 g / m2 2 The inventors have found that by using this particular type of PP resin, the minimum grams of PP resin required to achieve pinhole free film formation in extrusion coating of paper and paperboard can be significantly reduced.

[0042] The PP resin of the third aspect may be further defined as defined above with reference to the first aspect.

[0043] According to a fourth aspect exemplified herein, there is provided a method for producing a PP resin coated paper or paperboard substrate comprising cellulose fibers, the method being characterized in that it comprises: a) providing a paper or paperboard substrate; b) applying at least one layer of molten PP resin to the surface of the substrate by extrusion coating; c) cooling and solidifying the PP resin; and d) Recovering PP resin coated substrates. Moreover, the PP resin has a strength of 890 to 910 kg / m 3 in the range of 155-170°C (determined according to ISO 11357-3), and a melting temperature in the range of 10-15 g / 10 min (230°C / 2.16 kg) (determined according to ISO 1133), Here, the PP resin is 30 g / m 2 The coating is applied to the substrate in grams or less.

[0044] The PP resin of the fourth aspect may be further defined as defined above with reference to the first aspect.

[0045] The paper or paperboard of the present invention has a viscosity of 890 to 910 kg / m 3 Alternatively, the paper or paperboard of the present invention may comprise a PP resin coating layer as one of two or more polymer coating layers. The PP resin of the present invention can be preferably used as the first (or innermost) coating layer applied directly to the surface of the paper or paperboard, since it can provide a thin, pinhole-free PP coating on the paper or paperboard. The extrusion coated PP resin coating layer can then serve to promote the adhesion of a subsequent applied or co-extruded PP coating layer having a different composition than the first PP resin coating layer.

[0046] In some embodiments, the method further comprises applying at least one additional polymer coating layer disposed over the extrusion coated PP resin, the additional polymer coating layer having a different composition than the extrusion coated PP resin. In a preferred embodiment, the at least one additional coating layer comprises polypropylene (PP).

[0047] In some embodiments, the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

[0048] Although the present invention has been described with reference to various exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

[0049] Example: Pinhole formation as a function of grams of coating in different PP grades 180-190g / m 2 A paperboard having a gram weight of 100 g (Cupforma Natura, Stora Enso Oy) was extrusion coated with a polypropylene monolayer (one-sided coating, top extruder temperature 290-300° C.).

[0050] In the first test, the board was coated with standard extrusion coating grade polypropylene (Std PP). Standard extrusion coating grade polypropylene has a strength of 910 kg / m 3 (determined according to ISO 1183), a melting temperature of 161° C. (determined according to ISO 11357-3), and a melt flow rate of 25 g / 10 min (230° C. / 2.16 kg) (determined according to ISO 1133).

[0051] In the second test, the board had a density of 900 kg / m 3 (determined according to ISO 1183), melting temperature 162°C (determined according to ISO 11357-3), melt flow rate (230°C / 2.16 kg) 13 g / 10 min (determined according to ISO 1133).

[0052] For each PP coated board, two different coating weights were used (first coating weight approximately 30 g / m 2 , second coating weight about 20g / m 2 ) was prepared.

[0053] Four PP-coated paperboard samples were analyzed for the presence of pinholes in the PP coating. The pinhole test was performed by spreading a liquid consisting of 99.5% ethanol stained with Erythrosin B (10 g / 5 L ethanol) on the coating surface, drying the liquid, and counting the number of pinholes in a defined area using an optical microscope. The results were 2 The results were obtained as the number of pinholes per unit area. The results are shown in Table 1. These measurement results demonstrate that the use of branched PP copolymers can significantly reduce the occurrence of pinholes.

[0054] [Table 1]

[0055] In addition to reducing pinhole formation, it was also found that using branched PP copolymers in place of standard extrusion coating grades of PP significantly increased the line speed of an extrusion coating line. Using branched PP copolymers, line speeds could be increased by at least 30% compared to standard grades while maintaining an acceptable standard deviation in coating grams. The following is further disclosed regarding the present invention. [1] A paper or paperboard comprising cellulose fibers, the paper or paperboard comprising at least one coating layer formed by extrusion coating with a PP (polypropylene) resin; PP resin: 890-910kg / m 3 in the range of 155-170°C (determined according to ISO 11357-3), and a melting temperature in the range of 10-15 g / 10 min (230°C / 2.16 kg) (determined according to ISO 1133), Here, the PP resin is 30 g / m 2 applied to paper or paperboard in grams or less; The paper or paperboard as described above. [2] The PP copolymer has a viscosity of 895 to 905 kg / m 3 Density in the range of 898 to 902 kg / m 3 2. The paper or paperboard according to claim 1, having a density in the range of [3] 10. The paper or paperboard according to any of the preceding claims, wherein the PP copolymer has a melting temperature in the range 158-166°C, preferably in the range 160-164°C. [4] 10. The paper or paperboard according to any of the preceding claims, wherein the PP copolymer has a melt flow rate (230°C / 2.16kg) in the range 12-14g / 10min, preferably about 13g / 10min. [5] 13. The paper or paperboard according to any of the preceding claims, wherein the PP copolymer is long chain branched polypropylene (LCB-PP). [6] 2. The paper or paperboard according to any of the preceding claims, wherein the PP copolymer has been visbroken. [7] 2. The paper or paperboard according to any of the preceding claims, wherein the PP resin comprises at least 70% by weight, preferably at least 90% by weight, of said PP copolymer. [8] The remainder of the PP resin has a density of 890 to 910 kg / m 3 (determined in accordance with ISO 1183), a melting temperature outside the range of 155-170°C (determined in accordance with ISO 11357-3), and a melt flow rate (230°C / 2.16 kg) outside the range of 10-15 g / 10 min (determined in accordance with ISO 1133). [9] PP resin is 28g / m 2 Less than 26 g / m 2 less than 24 g / m 2 The paper or paperboard of any preceding claim, wherein the paper or paperboard is applied to a substrate in an amount of less than 1 g.

[10] 10. The paper or paperboard according to any of the preceding claims, wherein the PP resin comprises at least one additional component selected from the group comprising polymers other than PP, pigments, dyes, and fillers.

[11] 13. The paper or paperboard of any preceding claim, further comprising at least one additional polymeric coating layer disposed on the extrusion coated PP resin, the additional polymeric coating layer having a different composition than the extrusion coated PP resin.

[12] 12. The paper or paperboard according to

[11] , wherein the at least one additional coating layer comprises polypropylene (PP).

[13] 13. The paper or paperboard according to

[11] or

[12] , wherein the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

[14] A heat-resistant container, preferably a microwaveable food container, comprising the paper or paperboard described above.

[15] 890~910kg / m 3 % of a branched PP copolymer having a density in the range of 30 g / m2 (determined according to ISO 1183), a melting temperature in the range of 155 to 170 °C (determined according to ISO 11357-3), and a melt flow rate in the range of 10 to 15 g / 10 min (230 °C / 2.16 kg) (determined according to ISO 1133), for coating a paper or paperboard substrate containing cellulose fibers, 2 The above use, wherein the composition is applied to a substrate in amounts of less than 1 g.

[16] The use according to

[15] , wherein the PP resin is further defined as described in any one of [2] to

[10] .

[17] 1. A method for producing a PP resin coated paper or paperboard substrate comprising cellulose fibers, the method comprising: a) providing a paper or paperboard substrate; b) applying at least one layer of molten PP resin to the surface of the substrate by extrusion coating; c) cooling and solidifying the PP resin; and d) recovering the PP resin coated substrate; Including, Moreover, the PP resin has a strength of 890 to 910 kg / m 3 in the range of 155-170°C (determined according to ISO 11357-3), and a melting temperature in the range of 10-15 g / 10 min (230°C / 2.16 kg) (determined according to ISO 1133); and PP resin is 30g / m 2 The method of claim 1, wherein the coating is applied to the substrate in amounts of less than 1 g.

[18] The method according to

[17] , wherein the PP resin is further defined in any one of [2] to

[10] .

[19] applying at least one additional polymer coating layer disposed on the extrusion coated PP resin, the additional polymer coating layer having a different composition than the extrusion coated PP resin; The method according to

[17] or

[18] , further comprising:

[20] 20. The method of claim 19, wherein the at least one additional coating layer comprises polypropylene (PP).

[21] The method according to

[19] or

[20] , wherein the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

Claims

1. A paper or paperboard comprising cellulose fibers, the paper or paperboard comprising at least one coating layer formed by extrusion coating with a PP (polypropylene) resin; PP resin: 898-902 kg / m ３ (determined according to ISO 1183), a melting temperature (determined according to ISO 11357-3) in the range of 160-164°C, and a melt flow rate (230°C / 2.16 kg) in the range of 10-15 g / 10 min (determined according to ISO 1133), Here, the PP resin is 30 g / m ２ applied to paper or paperboard in grams or less; The paper or paperboard as described above.

2. Paper or paperboard according to any one of the preceding claims, wherein the PP copolymer has a melt flow rate (230°C / 2.16kg) in the range 12-14g / 10min, preferably about 13g / 10min.

3. 10. The paper or paperboard according to any one of the preceding claims, wherein the PP copolymer is long chain branched polypropylene (LCB-PP).

4. 2. The paper or paperboard according to any one of the preceding claims, wherein the PP copolymer is visbroken.

5. PP resin is 28g / m ２ less than 26 g / m ２ less than 24 g / m ２ 20. The paper or paperboard of any one of the preceding claims, applied to a substrate in an amount of less than 1 g.

6. 2. Paper or paperboard according to any one of the preceding claims, wherein the PP resin comprises at least one additional component selected from the group comprising polymers other than PP, pigments, dyes and fillers.

7. 13. The paper or paperboard according to any one of the preceding claims, further comprising at least one additional polymeric coating layer disposed on the extrusion coated PP resin, the additional polymeric coating layer having a different composition than the extrusion coated PP resin.

8. 8. The paper or paperboard of claim 7, wherein the at least one additional coating layer comprises polypropylene (PP).

9. 9. The paper or paperboard of claim 7 or 8, wherein the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

10. 10. A heat resistant container, preferably a microwaveable food container, comprising the paper or paperboard according to any preceding claim.

11. 898 to 902 kg / m ３ (determined according to ISO 1183), a melting temperature (determined according to ISO 11357-3) in the range of 160 to 164°C, and a melt flow rate (230°C / 2.16 kg) in the range of 10 to 15 g / 10 min (determined according to ISO 1133), for coating a paper or paperboard substrate comprising cellulose fibres, ２ The above use, wherein the composition is applied to a substrate in amounts of less than 1 g.

12. The use according to claim 11, wherein the PP resin is further defined as in any one of claims 2 to 6.

13. 1. A method for producing a PP resin coated paper or paperboard substrate comprising cellulose fibers, the method comprising: a) providing a paper or paperboard substrate; b) applying at least one layer of molten PP resin to a surface of the substrate by extrusion coating; c) cooling and solidifying the PP resin; and d) recovering the PP resin coated substrate; Including, Moreover, the PP resin has a strength of 898 to 902 kg / m ３ in the range of 160-164° C. (determined according to ISO 11357-3), and a melt flow rate (230° C. / 2.16 kg) in the range of 10-15 g / 10 min (determined according to ISO 1133); PP resin is 30g / m ２ The method of claim 1, wherein the coating is applied to the substrate in amounts of less than 1 g.

14. The method of claim 13, wherein the PP resin is further defined in any one of claims 2 to 6.

15. applying at least one additional polymer coating layer disposed over the extrusion coated PP resin, the additional polymer coating layer having a different composition than the extrusion coated PP resin; 15. The method of claim 13 or 14, further comprising:

16. The method of claim 15 , wherein the at least one additional coating layer comprises polypropylene (PP).

17. 17. The method of claim 15 or 16, wherein the at least one additional coating layer is formed by extrusion coating or by extrusion film lamination.

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