Dry modified pulp having a content of microfibrils and prefibrilized fiber

Abstract

The present invention relates to a modified pulp having a moisture content of less than 15% and a content of microfibrils and pre-fibrillated fibers. The modified pulp may be used either directly or subjected to additional refinement after suspension. The invention also relates to a method for producing a cellulosic product using the modified pulp.

Description

Technical Field

[0001] The present invention relates to a modified pulp having a certain content of microfibrils and prefibrillated fibers. The modified pulp can be used directly or undergo additional refining. The present invention also relates to a method for producing a cellulosic product using the modified pulp. Background Art

[0002] Paper, paperboard and films comprising microfibrillated cellulose (MFC) or highly refined cellulose are known in the art. Depending on the way they are produced, paper, paperboard and films may have particularly advantageous strength and / or barrier properties while being biodegradable and renewable. Films comprising MFC are used, for example, in the manufacture of packaging materials and may be laminated or provided on the surface of a paper or paperboard material.

[0003] There remains a need for more efficient processes for efficiently producing MFC and with limited use of energy, both for dehydration / drying and fibrillation / mixing and when considering efficient mixing of functional chemicals into the gel product. In addition, there is a need to be able to efficiently provide an intermediate product that can be easily stored, transported and, if desired, converted to microfibrillated cellulose in situ and immediately prior to use in a process for making a paper or paperboard product. For such an intermediate product, it is important that the intermediate product can be used with limited energy input and, ideally, without the use of complex fiber activation, wetting agents, enzyme treatments or expensive equipment.

[0004] When dewatering and drying the microfibrillated cellulose or prefibrillated fibers, such as in preparation for storage and / or transportation, there is a risk of blending failure or co-drying of the materials leading to keratinization and subsequent loss of the effect provided by the fibrils. If this occurs, the desired effect of the final product, for example on strength and / or barrier properties, will not be achieved.

[0005] Potential solutions to this problem are to reduce the intensity of drying or use additives that reduce keratinization such as low molecular carbohydrates. However, such chemicals may increase the risk for microbial growth and are not a preferred solution.

[0006] EP3289004 relates to a method for producing a dry-mixed product comprising cellulose filaments and carrier fibers, as well as a redispersible dry-mixed product of cellulose filaments and carrier fibers, which allows the cellulose filaments to retain their dispersibility in water and their reinforcing capabilities in papermaking furnishes, composite materials or other materials using cellulose filaments. Summary of the invention

[0007] It is an object of the present invention to provide a method which overcomes one or more of the problems of the prior art.

[0008] A specific object of the present invention is to provide an improved pulp which can be easily transported in dry form and which can be resuspended to obtain a suspension comprising microfibrillated cellulose or highly refined pulp, wherein the beneficial strength or barrier properties of the microfibrillated cellulose or highly refined pulp are not lost due to keratinization resulting from the dried microfibrillated cellulose or highly refined pulp. In particular, it has been found that the improved pulp according to the present invention provides improved tensile strength and stiffness properties combined with gas barrier properties without significantly reducing bulk in paper, paperboard and film products produced using the improved pulp. Surprisingly, it has also been found that products produced using the improved pulp according to the present invention have improved stretching properties, i.e. the product has an improved ability to stretch before it breaks.

[0009] Furthermore, it was an object of the present invention to provide a process for producing such pulp and its use in the production of cellulosic products such as paper, board, moulding products and films.

[0010] The invention is defined by the attached independent claims. Embodiments are set out in the attached dependent claims and in the following description.

[0011] According to a first aspect, there is provided a method for producing a modified pulp, wherein the method comprises the following steps:

[0012] - Provide wood pulp furnish;

[0013] - mixing a wood pulp furnish with highly refined pulp and / or microfibrillated cellulose to obtain a cellulosic suspension, wherein the total content of highly refined pulp and / or microfibrillated cellulose in the obtained cellulosic suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content, wherein the cellulosic suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 14 to 20;

[0014] - Drying the cellulosic suspension to obtain a modified pulp having a moisture content of less than 15% by weight.

[0015] The second aspect of the present invention is a modified pulp obtained according to the first aspect. The modified pulp has a moisture content of less than 15%. The modified pulp contains flaky particles in the range of from 10 to 20%, wherein the flaky particles are particles having a width of less than 10 μm and a length of more than 0.2 mm. The percentage is the percentage of the length, wherein the total length of the flaky particles is divided by the total length of all measured particles longer than 0.2 mm and multiplied by 100.

[0016] A third aspect of the present invention is a method for preparing a cellulosic product, comprising the following steps:

[0017] - preparing a fibrous suspension of the modified pulp of the invention;

[0018] - forming an intermediate product comprising a cellulosic suspension;

[0019] - The intermediate product is dehydrated and dried to a moisture content of less than 15 wt. % to obtain a cellulosic product.

[0020] A fourth aspect of the invention is a cellulosic product produced using the modified pulp according to the invention. DETAILED DESCRIPTION

[0021] The wood pulp furnish used according to the present invention is prepared from dried or never dried fibers from softwood and / or hardwood. The wood pulp furnish is prepared using methods known in the art. Preferably, the wood pulp has a lignin content of less than 15% by weight, based on the total dry weight of the pulp, more preferably less than 10% by weight, based on the total dry weight of the pulp. Preferably, the wood pulp has a hemicellulose content in the range of 10-30% by weight, based on the total dry weight of the pulp. The term wood pulp as used herein does not refer to recycled or manufactured fibers such as lyocell or viscose. In one embodiment, the wood pulp is bleached. In one embodiment, the wood pulp is unbleached.

[0022] Highly refined pulp can be made from unfractionated cellulosic starting material. Highly refined pulp can also be prepared according to the method disclosed in WO2021 / 001751A. In this embodiment, the highly refined pulp is preferably produced by the following

[0023] a) providing a fine fiber fraction obtained by fractionation of cellulose pulp;

[0024] b) subjecting the fine fiber fraction to refining at a consistency in the range of 0.5-30% by weight to a Schopper-Riegler (SR) value in the range of 80-98 determined by standard ISO 5267-1, in order to obtain a highly refined pulp.

[0025] Thus, one embodiment of the present invention is a method for producing a modified pulp, wherein the method comprises the following steps:

[0026] a) Providing wood pulp furnish;

[0027] b) providing a highly refined pulp, wherein the highly refined pulp is produced by

[0028] i. providing a fine fiber fraction obtained by classification of cellulose pulp;

[0029] ii. subjecting the fine fiber fraction to refining at a consistency in the range of 0.5-30% by weight to a Schopper-Riegler (SR) value in the range of 80-98 as determined by standard ISO 5267-1 to obtain a highly refined pulp;

[0030] c) mixing a wood pulp furnish with a highly refined pulp to obtain a fibrous suspension, wherein the total content of highly refined pulp in the obtained fibrous suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content, wherein the fibrous suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 14 to 20;

[0031] d) drying the cellulosic suspension to obtain a modified pulp having a moisture content of less than 15 wt. %.

[0032] The fine fiber fraction used in the preparation of highly refined pulp can be obtained, for example, by separating the cellulosic pulp starting material in a pressure screen to obtain a fraction with shorter and finer fibers. The dry weight of the fine fiber fraction can, for example, contain less than 75 wt%, less than 50 wt%, less than 25 wt% of the total dry weight of the unfractionated cellulosic pulp starting material used in the preparation of highly refined pulp.

[0033] If the fine fiber fraction is used in the preparation of highly refined pulp, it typically has an average fiber length of fibers with a length of >0.2 mm and below 1.7 mm (which is determined according to ISO 16065-2) and a content of fibers with a length of >0.2 mm of at least 5 million fibers / g, based on dry weight. The content of fibers with a length of >0.2 mm of the fine fiber fraction is typically less than 10 million fibers / g, based on dry weight.

[0034] In the production of highly refined pulp, the fine fiber fraction is obtained by fractionating the size of the cellulose pulp starting material into a fine fiber fraction and a coarse fiber fraction. The fine fiber fraction has a higher amount of shorter and finer fibers than the cellulose pulp starting material. The fine fiber fraction can be obtained, for example, by separating the cellulose pulp starting material in a pressure screen to obtain a fraction with shorter and finer fibers. The dry weight of the fine fiber fraction can, for example, contain less than 75% by weight, less than 50% by weight, less than 25% by weight of the total dry weight of the unfractionated cellulose pulp starting material.

[0035] Refining of the fine fiber fraction to obtain a highly refined pulp is preferably performed with a total refining energy in the range of 100-1500 kW / t, preferably in the range of 500-1500 kW / t, more preferably in the range of 750-1250 kW / t.

[0036] The highly refined pulp preferably has a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 80-98, more preferably in the range of 85-98, most preferably in the range of 90-98. The highly refined pulp preferably has a content of fibers with a length of >0.2 mm of at least 12 million fibers / gram, based on dry weight. More preferably, the highly refined pulp has a content of fibers with a length of >0.2 mm of at least 15 million fibers / gram (based on dry weight) and preferably at least 20 million fibers / gram (based on dry weight). Preferably, the highly refined pulp has a crill value of at least 1.7, preferably at least 1.8, more preferably at least 1.9. The content of fibers with a length of >0.2 mm and the crill value are determined using an L&W Fiber tester Plus instrument (L&W / ABB). The powder fiber measurement method is based on the ability of particles to absorb and scatter light of different wavelengths depending on their diameter. By directing a pulp suspension through a UV and an IR light source with detectors on the opposite side, the presence of small particles in the solution can be detected. The more particles there are, the more light is scattered or absorbed. Small particles such as powder fibers will diffuse and absorb light from the UV source, while the fibers affect light from the IR source. The powder fiber content is obtained as the ratio of detected UV / IR.

[0037] Thus, one embodiment of the present invention is a method for preparing a modified pulp, wherein the method comprises the following steps:

[0038] a) Providing wood pulp furnish;

[0039] b) providing a highly refined pulp having a content of fibers having a length > 0.2 mm of at least 12 million fibers / gram, based on dry weight;

[0040] c) mixing a wood pulp furnish with a highly refined pulp to obtain a fibrous suspension, wherein the total content of highly refined pulp in the obtained fibrous suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content, wherein the fibrous suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 14 to 20;

[0041] d) drying the cellulosic suspension to obtain a modified pulp having a moisture content of less than 15 wt. %.

[0042] The microfibrillated cellulose used according to the invention is preferably natural microfibrillated cellulose. Natural microfibrillated cellulose means that the microfibrillated cellulose is provided in its natural form, i.e. without the fibres from which the microfibrillated cellulose is derived or the microfibrillated cellulose itself being subjected to chemical derivatization (wherein functional groups are covalently bound, such as for example phosphorylation or carboxymethylation).

[0043] The total amount of microfibrillated cellulose and / or highly refined pulp of the cellulosic suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content. Preferably, the total amount of microfibrillated cellulose and / or highly refined pulp of the cellulosic suspension is in the range from 3 to 13 wt.-%, based on the total dry solids content. More preferably, the total amount of microfibrillated cellulose and / or highly refined pulp of the cellulosic suspension is in the range from 4 to 12 wt.-%, based on the total dry solids content.

[0044] Preferably, the microfibrillated cellulose and / or highly refined pulp of the cellulosic suspension is never-dried microfibrillated cellulose and / or highly refined pulp.

[0045] Preferably, the solids content of the cellulosic suspension is at least 0.4%, ie 1 kg of suspension contains at least 4 grams of suspended matter in solid form. More preferably, the solids content of the cellulosic suspension is at least 0.5%.

[0046] In the highly refined pulp and / or microfibrillated cellulose used according to the invention, the average width of the particles or fibers therein is at least 5 μm, preferably at least 10 μm.

[0047] In the highly refined pulp and / or microfibrillated cellulose used according to the present invention, the average length of the particles or fibers therein is preferably in the range from 20% to 60% of the average length of the fibers before processing into highly refined pulp or microfibrillated cellulose.

[0048] The highly refined pulp and / or microfibrillated cellulose is preferably wet when mixed with the pulp furnish.Thereby, the highly refined pulp and / or microfibrillated cellulose is provided in the form of a suspension, preferably an aqueous suspension.

[0049] The dewatering resistance of the fibrous suspension according to the invention, measured as the Schopper-Riegler (SR) value determined by standard ISO 5267-1, is in the range of 14 to 20. Preferably, the SR value is in the range of 15-18.

[0050] The cellulosic suspension according to the invention preferably has a pH in the range from 3 to 10, preferably in the range from 4 to 7.

[0051] Drying of the cellulosic suspension is carried out using methods known in the art to obtain a modified pulp having a moisture content of less than 15%, and according to one embodiment, may be carried out by vacuum, hot air, hot calender, wet pressing or a combination thereof. It has been surprisingly found that the present invention minimizes the degree of keratinization of the microfibrillated cellulose and / or highly refined pulp. This is particularly advantageous because the properties of the microfibrillated cellulose and / or highly refined pulp are retained during drying, so that the final shaping after re-pulping still benefits from the improved properties of the microfibrillated cellulose and / or highly refined pulp. Therefore, the modified pulp can be easily transported in a dry state (moisture content of less than 15%) and subsequently resuspended to obtain a resuspended modified pulp, wherein the properties of the microfibrillated cellulose and / or highly refined pulp substantially correspond to its properties before drying. Preferably, the modified pulp has a moisture content of less than 10%, more preferably less than 8%.

[0052] The moisture content of the modified pulp can be determined using methods known in the art, such as thermogravimetric analysis according to ISO 638:2008.

[0053] The modified pulp according to the invention comprises from 10 to 20% flaky fines, wherein flaky fines are particles having a width of less than 10 μm and a length of greater than 0.2 mm, and wherein the percentages are percentages of length, wherein the total length of the flaky fines is divided by the total length of all measured particles longer than 0.2 mm and multiplied by 100. The flaky fines as defined herein constitute part of the total amount of fines. The fines are cellulose based. Preferably the modified pulp comprises from 14 to 18% flaky fines. The amount of flaky fines can be determined according to ISO 16065 using a Valmet Fiber Image Analyzer (Valmet FS5).

[0054] The modified pulp according to the invention can be used to produce cellulosic products. For such use, the modified pulp is resuspended in water using methods known in the art. The resuspended modified pulp can be used in the production of cellulosic products without refining. Optionally, the resuspended modified pulp can be subjected to refining before being used in the production of cellulosic products. If such refining is performed, the energy input for refining is preferably less than 150 kWh / ton of solid to be subjected to refining. Refining is optionally carried out in the presence of inorganic particles.

[0055] In one embodiment, the production of the cellulosic product is done in a papermaking machine using a porous wire on which the cellulosic web is formed. According to one embodiment, the production speed of the papermaking machine may be in the range of 20 to 1200 m / min.

[0056] The modified pulp according to the invention can be used, for example, in the manufacture of paper, films, boards, coatings, barrier coatings, adhesives, paints, cosmetics, nonwoven products, ropes, yarns, composites and other products in which it is desirable to include microfibrillated cellulose and / or highly refined pulp. In the manufacture of paper, the suspension according to the fifth aspect of the invention is typically added to the wet end of a conventional process for papermaking. The proportion or amount of suspension added to the wet end depends on the desired properties of the paper product to be produced.

[0057] The cellulosic product may also be a three-dimensionally shaped object, such as a tray or a cup, which can be produced, for example, using molding as known in the art. Examples of such molded products are trays, bowls and other 3D-shaped articles. It has been found that the molded articles produced from the modified pulp according to the invention are denser and exhibit lower air and oil permeability, higher strength and bending resistance and twice as high elongation as the corresponding products made from conventional softwood pulp or from a mixture of softwood and hardwood pulp.

[0058] In one embodiment, the cellulosic product is paper, preferably greaseproof paper or glassine or high density paper.

[0059] When the cellulosic product is paper, paperboard or film, it may form part of a laminate wherein the laminate also comprises other layers or films, such as thermoplastic polymers such as any of polyethylene, polyethylene terephthalate and polylactic acid.

[0060] The microfibrillated cellulose used according to the present invention preferably has a Schopper Riegler value (SR°) of greater than 75 SR°, or greater than 80 SR°, or greater than 90 SR°, or greater than 93 SR°, or greater than 95 SR°.

[0061] The microfibrillated cellulose is preferably provided in the form of a suspension. The amount of microfibrillated cellulose in the suspension is preferably in the range of from 40 to 100 wt %, based on the total dry solids content. The solids content of the suspension of microfibrillated cellulose is preferably in the range of from 0.1 wt % to 5 wt %, such as from 1 wt % to 4 wt %.

[0062] Microfibrillated cellulose (MFC) is understood in the context of the present patent application as nanoscale cellulose particle fibers or fibrils having at least one dimension less than 100 nm. MFC partially or completely comprises fibrillated cellulose or lignocellulose fibers. The released fibrils have a diameter less than 100 nm, while the actual fibril diameter or particle size distribution and / or aspect ratio (length / width) depends on the source and the manufacturing method. The smallest fibrils are called elementary fibrils and have a diameter of about 2-4 nm (see, for example, Chinga-Carrasco, G., Cellulose fibres, nanofibrils and microfibrils,: The morphological sequence of MFC components from a plantphysiology and fibre technology point of view, Nanoscale research letters 2011, 6:417), while conventionally, aggregated forms of elementary fibrils, also defined as microfibrils (Fengel, D., Ultrastructural behavior of cell wall polysaccharides, Tappi J., March 1970, Vol. 53, No. 3), are the main products obtained when manufacturing MFC, for example by using an extended refining process or a pressure drop decomposition process. Depending on the source and the manufacturing process, the length of the fibrils can vary from about 1 to more than 10 microns. Crude MFC grades may contain a considerable fraction of fibrillated fibres, i.e. fibrils protruding from the tracheids (cellulose fibres) and with a certain amount of fibrils released from the tracheids (cellulose fibres).

[0063] There are different abbreviations for MFC, such as cellulose microfibrils, fibrillated cellulose, nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibrils, cellulose nanofibrils, cellulose microfibrils, cellulose fibrils, microfibrillated cellulose, microfibril aggregates, and cellulose microfibril aggregates. MFC may also be characterized by various physical or physicochemical properties such as its large surface area or the ability to form a gel-like material at low solids (1-5 wt %) when dispersed in water. The cellulose fibers are preferably fibrillated to such an extent that the final specific surface area of ​​the MFC formed is from about 1 to about 200 m when determined using the BET method for freeze-dried material. 2 / g, or more preferably 50-200 m 2 / g.

[0064] The MFC used according to the present invention preferably has a particle size of less than 50, preferably a length weighted distribution of less than 40%, very short fibers (FS5 fines level) classified as 0-0.2 mm with a width of ≥ 10 μm, usually excluded from the fiber length calculation. The MFC used preferably has a FS5 fibrillation higher than 1.5%, more preferably higher than 1.8%, or higher than 2.0%, such as from 4% to 6%. Fines level and fibrillation can be measured using a Valmet FS5 fiber image analyzer.

[0065] There are various methods to make MFC, such as single or multiple pass refining, pre-hydrolysis followed by refining or high shear decomposition or release of fibrils. One or more pretreatment steps are usually required to make MFC manufacture energy efficient and sustainable at the same time. The cellulose fibers of the pulp to be utilized can be pretreated thus, for example, enzymatic or chemical treatment is performed to hydrolyze or expand the fibers or reduce the quantity of hemicellulose or lignin. The cellulose fibers can be chemically modified before fibrillation so that the cellulose molecules contain other (or more) functional groups different from those found in natural cellulose. Such groups include carboxymethyl (CMC), aldehydes and / or carboxyl groups (cellulose obtained by oxidation mediated by N-oxyl, such as "TEMPO"), quaternary ammonium (cationic cellulose) or phosphoryl groups, etc. After modification or oxidation in one of the methods described above, it is easier to decompose the fibers into MFC or nanofibrils.

[0066] Nano-fibrillar cellulose can contain some hemicelluloses, and its amount depends on plant origin. Pretreated fiber for example hydrolysis, pre-expansion or the mechanical decomposition of oxidized cellulose raw material, uses suitable equipment such as refiner, grinder, homogenizer, glue applicator (colloider), friction grinder, ultrasonic generator, fluidizer such as microfluidizer, macrofluidizer or fluidizer type homogenizer to carry out.According to the MFC manufacturing method, product may also contain particulate or nano-crystalline cellulose or be present in wood fiber or other chemicals in papermaking process.Product may also contain micron size fiber particles of various amounts not efficiently fibrillated.

[0067] MFC is produced from wood cellulose fibers, both hardwood and softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse or other non-wood fiber sources. It is preferably made from pulp including pulp from virgin fibers such as mechanical, chemical and / or thermomechanical pulp. It can also be made from broke or recycled paper.

[0068] Preferably, the MFC has a high aspect ratio, i.e. length / diameter in the range of at least 100: 1, preferably at least 500: 1 or more preferably at least 1000: 1. Preferably, the MFC is MFC that has never been dried or MFC that has been dried or MFC that has been concentrated to a dryness of at least 20%.

[0069] The cellulosic suspension used according to the present invention may also contain other additives such as fillers, pigments, retention chemicals, cross-linking agents, optical dyes, fluorescent whitening agents, defoaming chemicals, salts, pH adjustment chemicals, surfactants, antimicrobial agents, optical chemicals, pigments, nanopigments (spacers or fillers) and the like.

[0070] Example

[0071] Example 1

[0072] A kraft pulp furnish from softwood and a dispersion comprising microfibrillated cellulose (MFC) are provided.

[0073] Prepare the following mixture:

[0074] Table 1

[0075]

[0076] The suspension was dewatered under vacuum on a wire mesh, pressed and dried with indirect steam to a dry matter content of >90%.

[0077] The dried pulp suspension was beaten in a Voith-Sulzer refiner.Laboratory sheets for testing and measuring paper properties were produced according to ISO 5269-1.

[0078] Table 2

[0079]

[0080] Initial wet strength was measured according to SCAN-CM 69:09. After tableting and wet pressing, the tensile strength of the test pieces was tested in a tensile testing machine described in accordance with ISO 1924-3. Before starting the tensile test, the test pieces were allowed to dry in the fixture for different time periods. The dry matter content of each test piece was measured immediately after the tensile test. The values ​​at the specific dry matter content were obtained by interpolation.

[0081] Air permeability is measured according to ISO 5636-5. Five test pieces are cut from a conditioned laboratory sheet and measured in an air resistance device (Gurly tester). The average air permeability is calculated.

[0082] Elongation is measured according to ISO 1924-2. Ten test pieces having a width of (15 ± 0.1) mm and long enough to be clamped in the fixture are cut from the conditioned laboratory sheet. Elongation or strain at break is measured as the elongation of the specimen during the force applied at break, as a percentage of the initial test length.

[0083] Example 2

[0084] Unmodified softwood pulp (Sample 1 of Example 1), modified softwood pulp (Sample 3 of Example 1) and a pulp mixture containing 70% hardwood and 30% softwood were evaluated as raw materials in molded products. The third sample is a conventionally preferred formulation for 3-D structural molded products, combining high requirements on surface properties such as smoothness and barrier functionality with product rigidity.

[0085] Three kilograms (dry weight) of each dried sample were disintegrated at room temperature in a disintegrator at 6 wt% consistency for 20 minutes. When the dried pulp was defibrated, the pulp slurry was diluted to 0.5 wt% and pH and SR were measured. Hydrophobic agent AKD (4 kg / ton pulp) was added and the pulp was stirred for 30 minutes thereafter before entering the production unit.

[0086] Table 3

[0087]

[0088] The molded 3-D shaped product produced was tested after cutting to appropriate size. Only the bottom area of ​​the tray was used.

[0089] Table 4

[0090]

[0091] Oil resistance was measured using an in-house method based on the earlier SCAN method, SCAN-P 37:77, the Cobb-Ungers method. 2 The test was carried out on a test piece of known area and weight. 2 cl of consumer type olive oil (extra virgin) was filled in a 12.56 cm 2 The sheet is placed on top of the cup and then the steel plate. The pile of cup, sheet and plate is turned upside down and the contact time is recorded. After 28 seconds, the sheet is taken out of the pile. Any excess oil is gently wiped off the sheet for 2 seconds. Finally, the sheet is weighed. The difference in weight after and before contact with the oil is calculated and divided by the area 12.56 cm 2 Repeat the measurement twice and report it in g / m 2 The average value is reported as oil cobb.

[0092] Tensile index, tensile energy absorption index and elongation were measured on a Zwick instrument according to ISO 1924-3:2005. The average value for ten measurements is reported. Tear index measurements were performed on ten pieces according to TAPPI 496 cm-85 and the average value was calculated.

[0093] The bending resistance was measured on ten workpieces according to ISO 2493-1:2010 and the average value was calculated.

[0094] The results in Example 2 show that if the modified pulp according to the invention is used for molded products, it will give a denser product with lower air and oil permeability, higher strength and bending resistance and twice as high elongation compared to unmodified softwood pulp.

[0095] The modified pulp shows both lower air and oil permeability and much higher strength and elongation than the preferred formulation for high quality molded products. The bending resistance is not on the same level for the modified pulp, but should probably be improved with the higher bulk.

[0096] In view of the above specific embodiments of the present invention, other modifications and variations will become apparent to those skilled in the art. However, it should be apparent that such other modifications and variations can be achieved without departing from the spirit and scope of the present invention.

Claims

1. A method for producing a modified pulp, wherein the method comprises the following steps: - Provide wood pulp furnish; - mixing a wood pulp furnish with highly refined pulp and / or microfibrillated cellulose to obtain a cellulosic suspension, wherein the total content of highly refined pulp and / or microfibrillated cellulose in the obtained cellulosic suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content, wherein the cellulosic suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 14 to 20; - Drying the cellulosic suspension to obtain a modified pulp having a moisture content of less than 15% by weight.

2. The method according to claim 1, wherein the fibrous suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 15-18.

3. The method according to claim 1 or 2, wherein the modified pulp contains from 10 to 20% of lamellar fines, wherein lamellar fines are particles having a width less than 10 μm and a length greater than 0.2 mm determined according to ISO 16065, and wherein the percentage is a percentage of length, wherein the total length of the lamellar fines is divided by the total length of all measured particles longer than 0.2 mm and multiplied by 100 to calculate the percentage.

4. The method of claim 3, wherein the modified pulp comprises from 14 to 18% of flake fines.

5. The method according to any one of claims 1 to 4, wherein the wood pulp in the wood pulp furnish has a hemicellulose content in the range of 10 to 30% by weight, based on the total dry weight of the pulp.

6. The method according to any one of claims 1 to 5, wherein the wood pulp in the wood pulp furnish has a lignin content of below 15 wt.-%, based on the total dry weight of the pulp.

7. The process according to any one of claims 1 to 6, wherein the highly refined pulp has a content of fibers having a length > 0.2 mm of at least 12 million fibers / gram, based on dry weight.

8. The method of claim 7, wherein the highly refined pulp has a powdery fiber value of at least 1.

7.

9. The method according to any one of claims 1 to 8, wherein the wood pulp furnish is mixed with a highly refined pulp having a content of fibers having a length > 0.2 mm of at least 12 million fibers / gram, based on dry weight.

10. Modified pulp obtainable by the method according to any one of claims 1 to 9.

11. A modified pulp having a moisture content of less than 15% and containing lamellar fines in the range from 10 to 20% determined according to ISO 16065, wherein lamellar fines are particles having a width of less than 10 μm and a length of more than 0.2 mm, and wherein the percentage is a percentage of length, wherein the total length of the lamellar fines is divided by the total length of all measured particles longer than 0.2 mm and multiplied by 100 to calculate the percentage.

12. A method for preparing a cellulosic product, comprising the following steps - preparing a fibrous suspension of a modified pulp according to any one of claims 9 or 10; - forming an intermediate product comprising a cellulosic suspension; The intermediate product is dehydrated and dried to a moisture content of less than 15 wt % to obtain a cellulosic product.

13. A cellulosic product comprising the modified pulp according to claim 10 or 11.

14. The cellulosic product of claim 13, wherein the cellulosic product is paper, film, board, coating, barrier coating, adhesive, paint, cosmetic, nonwoven product, rope, yarn, composite or molded fiber article.

15. The cellulosic product according to claim 14, which is greaseproof paper or cellophane.

16. A cellulosic suspension comprising Wood pulp furnish; and Highly refined pulp and / or microfibrillated cellulose, wherein the total content of highly refined pulp and / or microfibrillated cellulose in the obtained cellulosic suspension is in the range from 2 to 15 wt.-%, based on the total dry solids content, wherein the cellulosic suspension has a dewatering resistance measured as a Schopper-Riegler (SR) value determined by standard ISO 5267-1 in the range of 14 to 20; wherein the fibrous suspension comprises from 10 to 20% of lamellar fines determined according to ISO 16065, wherein lamellar fines are particles having a width of less than 10 μm and a length of greater than 0.2 mm, and wherein the percentage is a percentage of length, wherein the total length of the lamellar fines is divided by the total length of all measured particles longer than 0.2 mm and multiplied by 100 to calculate the percentage.

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