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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
  • D21H11/04—Kraft or sulfate pulp
• • 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
  • D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
• • 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
• • 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

Definitions

• the present invention relates to a kraft paper with a basis weight according to ISO 536 in the range from 60 g / m 2 to 120 g / m 2 , in particular from 70 g / m 2 to 110 g / m 2 , a density in the range from 680 kg / m 3 to 720 kg / m 3 and a tensile strength index in the machine direction according to ISO 1924-3 between 79 kNm / kg and 98 kNm / kg, which optionally has a coating and / or an auxiliary element on at least one side, and a paper sack made therefrom .
• Kraft papers have been widely used for a number of years, especially in the packaging sector, and are characterized by a number of positive properties, in particular they are stable, relatively tear-resistant, rather insensitive to moisture and, despite these properties, have sufficient air permeability, for example as bags To be used for building materials, food and the like.
• Kraft paper has the advantage over many other types of paper currently in use that, apart from a few additives, it is a natural material that can be reused, recycled or, if it does not contain other components such as plastic coatings and the like, also compostable.
• Kraft paper is usually made with a very high content of pulp. In addition to cellulose, all common additives such as starch and glue are contained in Kraft paper. Because of its high strength, Kraft paper is used primarily in industrial applications for sacks such as cement sacks, sandbags and the like.
• Packaging materials without plastic linings or coatings must, in addition to requirements such as having sufficient air permeability, for example to prevent air from escaping to allow during their filling, also have sufficient elasticity, for example when filling with a high specific gravity materials, such as cement, not due to the shaping work or deformation, which acts when a sack is put down or when a sack is placed under pressure or when it falls to tear up.
• Kraft papers are increasingly used as shopping bags or garbage bags in order to replace non-recyclable plastic bags or non-compostable plastic bags with "natural materials" as far as possible.
• paper sacks currently in use have the disadvantage that, on the one hand, they are not compostable or biodegradable due to the currently not yet dispensable linings or, if such coatings are not present, are not sufficiently stable not to be exposed to unexpected loads or If it contains objects with corners and edges, tear it immediately.
• the aim of the invention is to provide a kraft paper that is sufficiently stable not to tear when exposed to stress, the wet strength of which is such that tearing is not to be feared even when filled with moist materials and that even without the use of unwanted coatings can be completely rotted away.
• a kraft paper according to the present invention is essentially characterized in that the kraft paper is formed from long-fiber cellulose with a minimum content of cellulose in the kraft paper of at least 96% by weight, preferably at least 97% by weight, and that a pore volume of the uncoated Kraft paper, measured with mercury porosimetry according to ISO 15901-1, is from 200 ⁇ l / g to 220 ml / g.
• such a Kraft paper can both simply be recycled and composted and furthermore has due to the special design a pore volume between 200 ⁇ l / g and 220 ml / g sufficient gas permeability for a quick filling of a sack made from it with simultaneous stability of the paper in order to be able to accommodate heavy, bulky and moist objects in the paper without it being unintentionally torn or destroyed. Furthermore, due to an extremely high pulp content and the fact that it is free of a coating, such a paper is 100% rotting.
• a Kraft paper for household applications, in particular, for example, as garbage bags, it is essentially further developed in that it has at least one coating and / or the at least one auxiliary element that is / are applied to at least one side selected from Group of markings, indicators, sensors and chemically or physically processed surface areas, such as viewing windows.
• a coating and / or at least one auxiliary element which is applied to at least one side of the kraft paper, it is possible to provide markings, texts, viewing windows, adhesive elements or tools for gluing, etc. on the paper in order to put the paper in the This means, for example, based on the text applied thereon, of being able to distinguish from markings, color markings, fluorescent markings, etc. from other papers or to be able to reliably transport or close a sack made from such paper or to be able to detect the contents.
• a coating is understood to mean any material applied to the surface of a kraft paper according to the present invention, such as inks, dyes, gumming or the like.
• a coating here extends over only a small part of the surface of the paper or it are covered up to 50% of the area.
• a coating according to the present invention differs fundamentally from additional layers of, for example, plastic applied over the entire surface, as were customary in the prior art, but always affects only one area of the surface of the paper and changes the properties, such as tear resistance, water solubility or air permeability of the paper and / or the sack made from it not or only very slightly.
• the kraft paper is designed in such a way that areas, in particular merging layers with differing porosities measured with mercury porosimetry according to ISO 15901-1, are formed in the thickness direction of the paper.
• the Kraft paper has different areas in the thickness direction, in particular areas or layers that merge into one another deviating porosity measured by means of mercury prosimetry according to ISO 15901-1, it is possible to form a paper which has properties that change in its thickness direction.
• the porosity on one surface can be significantly smaller compared to the other surface, which is favored on the one hand by the production process, in which there is usually a higher accumulation of shorter fiber components on the wire side of the paper and thus a lower porosity is formed than on the one on the other Side facing away from the sieve.
• Such a porosity gradient is, however, also dependent on other factors and can be controlled, whereby it is achieved that a paper is produced which, on the one hand, has excellent porosities and, on the other hand, is easy to print on.
• the side with the lower porosity according to ISO 15901-1 is selected as the side to be printed on. It is thus possible, using standard printing methods, such as flexographic printing, inkjet printing or the like, to print the kraft paper reliably without the printing inks fading or running off.
• the invention is further developed to the effect that at least one area has pores with a pore diameter less than or equal to 0.3 ⁇ m, in particular 0.01 ⁇ m to less than 0.3 ⁇ m and that a mean value of the porosity of this area or these areas is less than or equal to 5.5 ⁇ l / g measured with mercury porosimetry according to ISO 15901-1.
• the Kraft paper can be printed well without using excessive ink and without worrying about bleeding and bleeding of the colors.
• the paper with a gradient of the pore volume, with one side that has such a low porosity, a significantly increased moisture stability can surprisingly be achieved, whereby the paper tears, for example when it is used as a garbage bag for moist, compostable garbage , can be held back.
• the kraft paper By forming the kraft paper from a cellulose whose mean fiber length is between 2.2 mm and 2.7 mm, in particular between 2.3 mm and 2.6 mm, it is possible to produce a paper which is strong enough to hold a To withstand handling, transport and pressure, for example in garbage collection systems, without a sack formed therefrom tearing and on the other hand, however, within one usual composting time is safely compostable.
• the pulp with such fiber lengths which usually comes from softwood, it is possible to provide a relatively easily and quickly biodegradable paper.
• the kraft paper is designed so that it is made water-repellent by gluing and has a Cobb 60 water absorption value according to ISO 535 between 14 g / m 2 and 21 g / m 2 , it is particularly suitable for the use for the packaging and disposal of moist organic and biodegradable products, such as organic waste and organic household waste, is even more suitable, as the low water absorption value ensures that the paper is kept in a sack made from this paper even if moist biological waste is stored for a long time does not tear or is destroyed prematurely. Furthermore, such a paper or a sack made from this paper can subsequently also be used in compost presses, garbage sorting systems, etc. without it tearing due to the moisture of the material contained therein and contaminating the systems. For a further improved water resistance, the Kraft paper can, as corresponds to a further development of the invention, be equipped with polymeric wet strength agents.
• an optical marking, UV marking, indicator dye or sensor ink is applied to the paper as an auxiliary element.
• an auxiliary element it is not only possible to mark the paper, but also, for example, special patterns, colors, colors or patterns visible in ultraviolet light can be printed on the paper, so that a waste separation system is subsequently able, for example, to To sort out sacks from the waste stream which have a desired pattern in UV light and in this way, for example, biodegradable waste can be sorted out of the waste stream.
• markings can be, for example, indicator dyes which, due to reactions with the contents of a sack made from such paper, form a color reaction and thus a waste separation system is able to recognize that such a waste sack contains, for example, biological waste, oil or the like .
• color pigments which emit different colors when they are excited with UV light are preferably used in order, for example, to differentiate between different types of waste. Examples of such colors are blue with a peak wavelength of 449 nm, green with a peak wavelength of 526 nm, orange with a peak wavelength of 584 nm and red with a peak wavelength of 618 nm.
• Such inks or pigments can can be prepared in a conventional manner as would be known to those skilled in the art.
• the kraft paper is designed in such a way that a translucent area, in particular a viewing window, is provided as an auxiliary element, it is possible to produce or make available paper that, when used as a garbage bag or shopping bag, for example enables the user to see the contents from the outside without having to open the sack again.
• a viewing window can also be helpful in garbage sorting systems or refuse sorting systems in order to be able to detect the contents of the sacks and thus, for example, to sort out sacks according to their contents or to dispose of them for final recycling.
• the paper sack according to the invention is essentially characterized in that it is designed with a closure element on its upper free edge area and that the closure element consists of a closure tape made of paper or other rotable materials or a closure area provided with an adhesive6. Since the paper sack is formed at its upper free edge area with a closure element, which is formed, for example, from a closure tape or a closure area provided with adhesive, such a paper sack can be closed when it is used as a garbage bag after it has been filled without the contents leaking out and subsequently be processed further in composting plants or waste separation plants.
• a biodegradable adhesive can be used as the adhesive, which is from the group of natural glues, Dextrin, and water-based biodegradable adhesives and the like. Is selected. With the help of such an adhesive it is also ensured that undesired organic adhesive residues remain during composting or, if burned, poisonous gases, which can result from the polymeric adhesive, are formed.
• the paper sack is further developed in that an adhesive is applied to the paper on at least one side in the upper area.
• the sack can be closed, for example, by sticking the upper edges tightly together, thus preventing the contents of the sack from leaking out, or a rollover can be provided, whereby additional strength is achieved in the upper edge area of the sack.
• the paper sack is further developed in such a way that it is provided on an outwardly facing surface with an auxiliary element selected from the group of markings, indicators, sensors and chemically or physically processed surface areas such as viewing windows it is to sort out such bags in, for example, a sorting system on the basis of their auxiliary element or to send them to separate processing.
• an auxiliary element selected from the group of markings, indicators, sensors and chemically or physically processed surface areas such as viewing windows it is to sort out such bags in, for example, a sorting system on the basis of their auxiliary element or to send them to separate processing.
• the auxiliary element is a UV marking and that the marking is on at least 20%, preferably at least 25% but less than 70% of the surface of the sack is provided.
• a very special pattern can be applied, for example, to enable a sorting system to separate biological waste from non-biological waste Separate garbage.
• the invention is further developed in such a way that the marking is formed from a fluorescent ink with a pigment concentration of greater than 0.3%, in particular greater than 0.35%.
• pigment concentrations that are too low can lead to the fact that, in particular if one sack is to be sorted out from among a large number of sacks in a dirty environment, these sacks due to dirt residues cannot be detected on its surface. For this reason, the pigment concentration must be greater than 0.3%.
• the area on which the pigments are applied must be larger than at least 25% of the total surface of the objects in order to ensure that a reader in a garbage sorting system can safely sort out the appropriately labeled bags.
• the marking with a fluorescent ink can be applied during the manufacturing process of the paper, for example, it can be applied in the Clupak system with the help of a spray device, whereby it has proven to be beneficial that at least 20% of the surface is wetted with indicator ink Any pattern can be selected here.
• a clupack paper is produced in the conventional manner, in which a spray device is additionally provided in the clupack system, which applies a pattern consisting of bars and lines, which lines are essentially several centimeters wide, to the wire side of the paper.
• the lines are chosen so that they are not covered by a rollover of the paper, which is stuck over the opening in the course of closing the bag and sticks.
• a single-ply garbage bag with a standing base in the width of about 10 cm and a capacity of 140 l is produced from such paper.
• the paper has a basis weight of 90 g / m 2 , a density of 700 kg / m 3 , a tensile strength index in the machine direction of 85 kNm / kg, a Gurley air resistance of 25 s and a pore volume of the base paper of 210 ml / g.
• the sack is designed with a flap, which has a dextrin adhesive layer applied to one side, which becomes adhesive only when the flap is turned over and is then firmly glued to the underlying paper after the flap has been rolled over in order to prevent the objects contained therein from accidentally escaping .
• a marking visible in UV light in the form of a grid is applied over the circumference of the paper sack, the marking having a width of the bars of about 4 cm.
• the indicator color was applied in a concentration of 0.40% pigment concentration and a diamond or rod pattern that fluoresces yellow in UV light was formed.
• garbage bags After the production of such garbage bags, such a garbage bag was filled with green waste for test purposes, a garbage bag was filled with household garbage, which contained organic and non-organic garbage and finally, in a third case, was filled with differently biodegradable or rotable household garbage.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Paper (AREA)
• Bag Frames (AREA)
• Wrappers (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=67998357

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (2)

Citations (7)

• 2019
  • 2019-09-20 EP EP19198690.0A patent/EP3795745A1/fr active Pending
• 2020
  • 2020-09-18 US US17/762,146 patent/US20240026608A1/en active Pending
  • 2020-09-18 CA CA3153632A patent/CA3153632A1/fr active Pending
  • 2020-09-18 WO PCT/EP2020/076177 patent/WO2021053186A1/fr active Application Filing
• 2022
  • 2022-04-05 ZA ZA2022/03880A patent/ZA202203880B/en unknown

Patent Citations (7)

Non-Patent Citations (1)

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