Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/10—Bleaching ; Apparatus therefor
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
  • D21H17/28—Starch
  • D21H17/29—Starch cationic
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/16—Sizing or water-repelling agents

Definitions

• the present invention relates to unbleached packaging paper for sharp-edged articles and/or articles having unevenly arranged, projecting, substantially non-deformable elevations on at least one of its surfaces, which consists of kraft sulfate pulp as the main component and fillers, starch, sizing agents and other processing aids and optionally coating agents.
• Packaging papers must meet the respective requirements of the goods to be packaged in them; in particular, they must have sufficient tear resistance, elasticity, air permeability, etc.
• packaging paper used for packaging moisture-sensitive materials must have sufficient moisture resistance and, in particular, a barrier property against moisture or only have very limited moisture permeability.
• the specific properties that a packaging paper must have for a particular intended use can be estimated and determined by a person skilled in the art.
• the composition, manufacturing process, possible or necessary treatment steps, and materials can be at least roughly estimated by a person skilled in the art.
• the production of a paper that meets all of these requirements must take into account a multitude of factors, which often interact with one another, so that the final composition of the packaging paper and its production usually requires many trials and errors.
• packaging paper In order to avoid such tearing of packaging paper, it has often been the case in the past that it was coated on at least one side with plastic films, polymers or other tear-resistant and at the same time elastic materials or an insert made of such materials was inserted into multi-layer paper in order to be able to use paper as packaging material for sharp-edged objects or objects with uneven surfaces.
• cationic starch also increases the dry strength of the paper to which it is added, which is why, particularly when using unbleached pulp for the production of packaging paper, the aim is to use starch contents of over 12 kg/t of paper atro (atro means absolutely dry).
• Bleaching paper removes impurities and is used in particular when the surface of the paper has to be printed, for example, since bleached papers are usually easier to print on due to the improved brilliance of the printing inks.
• the packaging paper is used as unbleached packaging paper, for the production of which pulps with kappa numbers according to ISO 302:2015 in the range of 35 or higher were used.
• the unbleached packaging paper is designed to contain 100% primary pulp. While an admixture of secondary pulp of up to a maximum of 5% does not adversely affect the strength and elasticity of the paper, the use of 100% primary pulp ensures that the packaging paper is suitable for packaging foods with a non-uniform, uneven surface, such as pasta, cereal bars, nuts, or the like.
• packaging papers it is possible to provide single- or multi-layer packaging papers, depending on the basis weight of the respective paper, which can serve, for example, as a replacement for plastic packaging or packaging cardboard.
• Such packaging paper also has a puncture energy index in accordance with DIN EN 14477:2004 with a test speed of 10.0 mm/min measured on any side of the packaging paper in the range of 30 to 75 mJ.m 2 /kg, which means that when such paper is used to package sharp-edged objects and/or objects that have irregularly arranged, protruding and essentially non-deformable elevations on at least one of their surfaces, penetration or puncture of the sharp-edged objects through the paper can be prevented.
• What is surprising here is that a packaging paper with an elongation at break of over 6.0% also simultaneously exhibits the highest values for the puncture energy index and thus can reduce adverse effects that are associated with very high elongation values, such as very strong roughening of the paper surface.
• a packaging paper according to the invention can now be used safely and without the risk of loss of the items packaged therein due to abrasion from protruding areas of the items packaged therein, for packaging sharp-edged items such as gravel, pellets, metal parts such as screws, clothing with buttons, shoes with sharp heels, children's toy blocks, but also foodstuffs such as muesli bars, chocolate-nut bars, nuts, pasta, and the like.
• Puncture energy which is defined in DIN EN 14477:2004, is the force, taking into account elongation, that must be applied to penetrate a piece of paper or cardboard with a defined test specimen.
• Puncture energy index which is the puncture energy of a paper divided by its grammage, was measured in connection with the present invention using the standard DIN EN 14477:2004, which is commonly used to determine the puncture energy of flexible packaging materials, such as plastic films.
• the elongation upon puncture in mm is also crucial for ensuring that the packaging is not damaged.
• the integral under a force-elongation curve represents the energy that a material, and according to the present invention, packaging paper, can absorb without causing damage.
• the puncture energy index in mJ.m 2 /kg is divided by the grammage according to ISO 536:2019 of the respective paper, converted to kg/m 2.
• the puncture energy index is calculated analogously to the calculation of the tensile work index according to ISO 1924-3:2005.
• hardwood and softwood can be the fiber length of the fibers they contain, whereby this fiber length is influenced not only by the type of wood but also by the age of the tree and the position of the fiber in the cross-section of the log.
• softwoods with a length-weighted average fiber length of at least 2.1 mm and, optionally, hardwoods with a length-weighted average fiber length of at least 1.0 mm are used.
• This length-weighted fiber length of a pulp fiber is defined in ISO 16065-2:2014 and is determined according to this standard.
• the unbleached packaging paper is essentially characterized in that the primary pulp is formed from a mixture consisting of at least 80% softwood pulp, more preferably at least 90% softwood pulp, in particular at least 95% softwood pulp with an average length-weighted fiber length according to ISO 16065-2:2014 of at least 2.1 mm and the remainder hardwood pulp with an average length-weighted fiber length according to ISO 16065-2:2014 of at least 1.0 mm.
• the unbleached packaging paper is designed such that the primary pulp consists of 100% softwood pulp with an average length-weighted fiber length according to ISO 16065-2:2014 of at least 2.1 mm.
• packaging paper made from 100% softwood pulp with an average length-weighted fiber length according to ISO 16065-2:2014 of at least 2.1 mm is thinner, has good strength, and is also printable than papers containing hardwood components or made exclusively from hardwood pulp.
• higher hardwood components for example, make the paper even more uniform in its sheet structure, and the achievable print quality can also be improved.
• filler When using unbleached packaging paper in all areas other than food packaging, the choice of filler is less critical. However, to achieve the desired tensile strength indices in the machine direction between 60 Nm/g and 140 Nm/g, the filler content should generally be kept low. Another additive used to adjust strength properties could be derivatized starch, preferably cationic starch. In general, all additives used in the papermaking process must be considered to ensure their suitability as a feedstock for the production of food packaging paper.
• the unbleached packaging paper is designed such that the primary pulp is contained as ground pulp, in particular high-consistency ground pulp with a Schopper-Riegler freeness level according to ISO 5267-1:1999 between 13°SR and 20°SR.
• Refining pulp influences the fiber strength and thus increases the quality of the product manufactured with it from a number of perspectives.
• non-bleached i.e. unbleached (i.e. natural brown) pulp
• the paper quality can be influenced in such a way that residual wood splinters contained in the pulp and fiber agglomerates not broken down by pulp cooking are finely ground during high-consistency refining, thus better evening out the texture of the paper and, in particular, smoothing it.
• the unbleached packaging paper is designed such that the puncture energy index according to DIN EN 14477:2004 differs between a surface-treated side of the packaging paper and an untreated side of the packaging paper by a factor greater than 1.0 to 1.7.
• the puncture energy index is generally influenced by the implementation of surface treatment steps, such as the introduction of functional barrier coatings.
• a corresponding surface treatment is particularly advantageous and useful when one side of the paper comes into contact with sharp-edged objects and the other side is to be printed or written on, for example. in which case the two surfaces of the packaging paper must be subjected to different finishing treatments.
• An unbleached pulp consisting of 95% primary softwood pulp with a kappa number of 42 and 5% primary hardwood pulp with a kappa number of 40 was used. This pulp was first subjected to high-consistency refining with a refining capacity of 190 to 210 kWh/ton. The pulp's freeness after high-consistency refining was 17°SR. This pulp was then subjected to low-consistency refining with a refining capacity of 75 kWh/ton until a freeness of at least 18°SR was achieved. The additives are added in the approach flow system of the paper machine. The pH was adjusted to a pH of 6.5 to 7.5 with aluminum sulfate.
• Cationic starch with a degree of cationization (DS) of 0.03 was added at a rate of 14 kg/tonne of dry paper, and alkenylsuccinic anhydride was used as a sizing agent at a rate of 0.8 kg/tonne of dry paper. Fillers were also added at a rate of 0.3 kg/tonne of dry paper. The consistency of the pulp at the headbox was 0.25%. Dewatering took place on a Foudrinier wire section and in a press section with three nips, one of which could be a shoe press. The line pressure at the three nips was 60 kN/m, 90 kN/m, or 500 kN/m (in the shoe press).
• the paper can be used as is, and the paper properties described in the table below were measured using this paper. It goes without saying that the paper can also be calendered, for example, in a soft-nip or long-nip calender, or subjected to a coating treatment, such as a dispersion coating, which can further modify its properties.
• a coating treatment such as a dispersion coating
• Such packaging paper can be used, for example, with or without an additional coating, for the production of paper bags, for example, for packaging gravel or game pieces.
• An unbleached pulp consisting of 100% primary softwood pulp with a kappa number of 41 was first subjected to high-consistency refining at a refining capacity of 220 to 240 kWh/ton, with the pulp's freeness level after high-consistency refining being 18°SR. Subsequently, this pulp was subjected to low-consistency refining at a refining capacity of 80 to 90 kWh/ton until a freeness level of at least 19°SR was achieved.
• the additives were added in the approach flow system of the paper machine. The pH was adjusted to a pH of 6.7 to 7.3 with aluminum sulfate.
• Cationic starch with a degree of cationization (DS) of 0.03, was added at a rate of 14 kg/tonne of dry paper, and alkenylsuccinic anhydride was used as a sizing agent at a rate of 0.8 kg/tonne of dry paper. No fillers were added. The consistency of the pulp at the headbox was 0.25%. Dewatering took place on a Foudrinier wire section and in a press section with three nips, one of which could be a shoe press. The line pressure at the three nips was 60 kN/m, 90 kN/m, and 500 kN/m (in the shoe press).
• the paper can be used as is, and the paper properties described in the table below were measured using this paper. Needless to say, the paper can also be calendered, for example, in a soft-nip or long-nip calender, or subjected to a coating treatment, such as a dispersion coating, which can further modify its properties.
• a coating treatment such as a dispersion coating
• Such packaging paper can be designed as a multi-layer packaging paper, with or without an additional coating, and can be used as a replacement for cardboard packaging, for example, for food products such as rice.
• the paper produced in this way had the following properties: Paper properties standard Unit Direction Result Grammage ISO 536:2019 g/ m2 131 Tensile strength ISO 1924-3:2005 kN/m MD 10.3 Tensile strength index ISO 1924-3:2005 Nm/g MD 78.6 Tensile strength ISO 1924-3:2005 kN/m CD 8.2 Tensile strength index ISO 1924-3:2005 Nm/g CD 62.6 Elongation at break ISO 1924-3:2005 % MD 10.3 Elongation at break ISO 1924-3:2005 % CD 9.7 Tensile fracture work ISO 1924-3:2005 J/m 2 MD 566 Tensile fracture work ISO 1924-3:2005 J/m 2 CD 497 Air permeability Gurley ISO 5636-5:2013 s 28.6 Bendtsen roughness ISO 8791-2:2013 ml/min Top 1420 Bendtsen roughness ISO 8791-2:2013 ml/min bottom 1890 Puncture resistance DIN EN 14477:2004 with 10 mm/min N From top 1
• the paper produced in this way had the following properties: Paper properties standard Unit Direction Result Grammage ISO 536:2019 g/ m2 160 Tensile strength ISO 1924-3:2005 kN/m MD 18.7 Tensile strength index ISO 1924-3:2005 Nm/g MD 116.9 Tensile strength ISO 1924-3:2005 kN/m CD 7.9 Tensile strength index ISO 1924-3:2005 Nm/g CD 49.4 Elongation at break ISO 1924-3:2005 % MD 13.1 Elongation at break ISO 1924-3:2005 % CD 9.3 Tensile fracture work ISO 1924-3:2005 J/m 2 MD 1140 Tensile fracture work ISO 1924-3:2005 J/m 2 CD 520 Air permeability Gurley ISO 5636-5:2013 s 31.2 Bendtsen roughness ISO 8791-2:2013 ml/min Top 4980 Bendtsen roughness ISO 8791-2:2013 ml/min bottom 4420 Puncture resistance DIN EN 14477:2004 with 10 mm/min N From top 17.2

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

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• 2021
  • 2021-03-31 DK DK21166361.2T patent/DK4067568T3/da active
  • 2021-03-31 EP EP21166361.2A patent/EP4067568B1/de active Active
  • 2021-03-31 PL PL21166361.2T patent/PL4067568T3/pl unknown
  • 2021-03-31 ES ES21166361T patent/ES3033556T3/es active Active
  • 2021-03-31 FI FIEP21166361.2T patent/FI4067568T3/fi active
• 2022
  • 2022-03-18 TW TW111110139A patent/TW202244361A/zh unknown
  • 2022-03-30 WO PCT/EP2022/058495 patent/WO2022207756A1/de not_active Ceased
  • 2022-03-30 CA CA3214122A patent/CA3214122A1/en active Pending
  • 2022-03-30 US US18/552,944 patent/US20250270768A1/en active Pending
  • 2022-03-30 CN CN202280025336.6A patent/CN117321263A/zh active Pending

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