WO2024003314A1 - Machine glazed paper and method for preparing the machine glazed paper - Google Patents

Machine glazed paper and method for preparing the machine glazed paper Download PDF

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Publication number
WO2024003314A1
WO2024003314A1 PCT/EP2023/067929 EP2023067929W WO2024003314A1 WO 2024003314 A1 WO2024003314 A1 WO 2024003314A1 EP 2023067929 W EP2023067929 W EP 2023067929W WO 2024003314 A1 WO2024003314 A1 WO 2024003314A1
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WIPO (PCT)
Prior art keywords
machine glazed
paper
glazed paper
fibers
machine
Prior art date
Application number
PCT/EP2023/067929
Other languages
French (fr)
Inventor
Markus Saari
Ari Tuominen
Helena KARLSSON
Original Assignee
Billerud Aktiebolag (Publ)
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Publication date
Application filed by Billerud Aktiebolag (Publ) filed Critical Billerud Aktiebolag (Publ)
Publication of WO2024003314A1 publication Critical patent/WO2024003314A1/en

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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
    • 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
    • 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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/62—Rosin; Derivatives thereof
    • 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
    • D21H19/00—Coated paper; Coating material
    • D21H19/36—Coatings with pigments
    • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
    • D21H19/54—Starch

Definitions

  • the present disclosure relates to the field of machine glazed paper and a method for preparing the machine glazed paper. More specifically the present disclosure relates to a machine glazed paper for preparing paper sticks.
  • Paperbased materials have however traditionally been considered less suitable for replacement of such single-use plastic material, such as for example cotton buds and lollipop sticks, as paperbased items have been considered having low shape stability compared to such plastic items. It has also been difficult to attain a proper sealability without including components negatively affecting the degradability of the items. During manufacturing of such paper component, dusting and blunting have also been causing important issues in the converting machines.
  • a machine glazed paper comprising softwood fibers and starch, the machine glazed paper comprising the starch in an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper and the amount of softwood fibers of the total amount of fibers is 63 wt.% or more.
  • the machine glazed paper has a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
  • the machine glazed paper comprises softwood cellulose fibers, also called long fibers.
  • softwood cellulose fibres measure from about 2 to 4 millimetres in length, compared to hardwood fibres ranging from about 0.5 to 1.5 millimetres.
  • softwood include pine, fir, spruce, larch and cedar.
  • paper after refining the softwood fibers are below 2mm.
  • the paper comprises long fibers which enables production of paper sticks having an improved bending resistance and reduced dusting during slitting operations.
  • the high starch content in combination with the high and fast water absorption of the paper has been found by the present inventors to enable an improved tensile strength and sealability of the paper during formation of paper sticks.
  • Both of the sides of the machine glazed paper i.e. the glazed and the non-glazed side of the machine glazed paper, have a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
  • the machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
  • the machine glazed paper may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, preferably 0.4 wt.% to 2 wt.% of the dry weight of the machine glazed paper.
  • the Cobb value of the paper may be obtained by lowering the amount of sizing agents in the paper, such as to a level of below 0.9 wt.%, optionally to a level of below 0.5 wt.%.
  • the amount of sizing agents in the paper may be 0.3 wt.% or below, such as 0.1 wt.% or below.
  • the paper is free Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
  • the machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
  • the machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
  • Alum aluminum sulfate
  • the machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, even more preferably 0.2 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
  • a machine glazed paper comprising softwood fibers and having a Cobb value according to the present disclosure comprising with 4 wt.% or less of fillers, based on the total dry weight of the paper, was found favourable with respect to dusting during cutting and blunting of the cutting and slitting tools. It was also found to increase the stiffness of paper sticks produced by the paper.
  • 65 wt.% or more of the fibers in the machine glazed paper are softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably, from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
  • the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
  • the machine glazed paper may have a basis weight within the range of from 35 gsm to 100 gsm, preferably within the range of from 38 gsm to 85 gsm. It has been found that the machine glazed paper according to the present disclosure is within these ranges are particularly suitable for forming paper sticks. When using the machine glazed paper of higher basis weight, the stiffness was increased and when using lower ranges, the process of making the paper sticks was negatively affected since an increased number or rolling is needed which increases the complexity and the defect rate of the paper sticks during process.
  • the softwood fibers may be unbleached softwood fibers. It was surprisingly found that the sealability of the paper, during manufacturing of paper sticks, was improved by using unbleached softwood fibers.
  • the softwood fibers may alternatively be bleached softwood fibers or a mix between bleached and unbleached softwood fibers.
  • the machine glazed paper may have an CD/MD ration of from 0.5. This provides an indication that the fibers of the machine glazed paper mainly are oriented in the MD direction. During slitting of the paper, when manufacturing paper sticks, such fiber orientation was found advantageous in that dusting was reduced.
  • the machine glazed paper may have a MD stretch of from 0.5% to 2%, preferably a MD stretch of from 1% to 1.9%, as measured according to the standard method ISO 1924/3. The fact that the machine glazed paper exhibited a MD stretch of from of from 0.5% to 2% enabled production of stiffer paper sticks by the paper according to the present disclosure.
  • the machine glazed paper may have a CD stretch of from 1.5% to 6.5%, preferably a CD stretch of from 2% to 5.5%, such as a CD stretch within the range of from 2 to 4.5%, as measured according to the standard method ISO 1924/3.
  • the fact that the machine glazed paper exhibited a CD stretch of from 1.5% to 6.5% enabled production of stiffer paper sticks which also resist bending without breakage.
  • the fact that the first side of the paper is machine glazed provides the paper with enhanced sealing when being an inner side during paper stick production.
  • the non-glazed side of the machine glazed paper may have a roughness of 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min.
  • the fact that the second side, being the outer side during paper stick production, is a non-glazed side having a roughness of from 350 ml/min to 2000 ml/min, such as 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min, provides an improved adherence to, by frictional force, for example the cotton part in a cotton bud. It has also seen providing an improved user handfeel.
  • the paper may be a non-calendered paper, this provides an increased roughness for the non-glazed side of the paper.
  • the machine glazed paper may have an air resistance within the range of from 15 to 35 s, as measured according to the standard method ISO 5636 "Paper and board - Determination of air permeance (medium range) - Part 5: Gurley method. It was surprisingly found by the present inventor that the sealing speed of the machine glazed paper is improved when the air resistance of the paper is within the range of from 15 to 35 s.
  • the machine glazed paper may be for use to prepare paper sticks, such for ear buds or lollipop sticks.
  • the present disclosure relates to a use of the machine glazed paper according to the first aspect for producing a paper stick.
  • the present disclosure relates to a paper stick, such as an ear bud stick or a lollipop stick comprising or consisting of the machine glazed paper according to the first aspect.
  • the present disclosure relates to a method for producing the machine glazed paper according to the first aspect, the method comprising the steps of;
  • a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight and the amount of softwood fibers of the total amount of fibers are 63 wt.% or more;
  • the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the according to the standard method ISO 535:2014.
  • the method may comprise a pre-drying step, between the dewatering step and the glazing step, wherein the fibrous web is pre-dried in the pre-drying step.
  • the moisture content in the fibrous web may be controlled in the pre-drying step, and if needed, the moisture content in the fibrous web may be adapted in the pre-drying step.
  • the moisture content is within the range of from 40 to 60 wt. % when entering the glazing unit. This may for example be achieved by adapting the speed and/or the temperature of the drying cylinders.
  • the adherence to the cylinder in the glazing unit may be improved by controlling the moisture content of the fibrous web in a pre-drying step, and if necessary, adapting the moisture content of the fibrous web to be within a set moisture content range when entering the glazing unit.
  • An unfavourable adherence/rejection of the fibrous web to the cylinder may give rise to a non-uniform drying of the fibrous web and such non- uniform drying was seen to provide a higher roughness value, impairing the sealing of the paper upon preparation of the paper sticks.
  • the adherence to the cylinder may be improved and also the roughness of the surface, which may lead to an improved sealing of the paper sticks prepared by the machine glazed paper.
  • the roughness of the first side i.e. the glazed side may be within the range of from 100 to 400 ml/min.
  • 65 wt.% or more of the fibers in the machine glazed paper may be softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably, from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
  • the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
  • the machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
  • the machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
  • Alum aluminum sulfate
  • the machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
  • the amount of filler may be measured by means of ash content by the standard method ISO 1762:2001.
  • the type of fillers may be determined by Fourier- transform infrared spectroscopy (FTIR).
  • the machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
  • the suspension may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% based on total dry weight, preferably 0.4 wt.% to 2 wt.% based on total dry weight.
  • the softwood fibers of the suspension may be unbleached or bleached softwood fibers.
  • the softwood fibers may alternatively be bleached softwood fibers or a mix between bleached and unbleached softwood fibers.
  • the machine glazed paper may have an CD/MD ration of from 0.5. This is an indication of that the fibers of the machine glazed paper may mainly be oriented in the MD direction, such as that 75 wt.% of the fibers of the machine glazed paper are oriented in the MD direction.
  • the second side of the machine glazed paper may have a roughness of from 350 ml/min to 2000 ml/min, optionally within the range of from 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min. This provides an improved adherence to, by frictional force, for example the cotton part in a cotton bud. It has also seen providing an improved user handfeel.
  • the present disclosure thus relates to a machine glazed paper comprising softwood fibers and starch.
  • a major part of the fibers of the machine glazed paper are softwood fibers, i.e. 63 wt.% or more, or 65 wt.% or more, or from 85 wt.% to 100 wt.%, more preferably from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, such as 100 wt.% of the fibers.
  • the machine glazed paper comprises starch in an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper.
  • the machine glazed paper furthermore has a Cobb value within the range of from 20 gsm to 50 gsm.
  • the Cobb value is measured according to the standard method ISO 535:2014.
  • the Cobb value provides information about the water absorption capacity of the paper sample and determines the amount of water that is absorbed by a defined area of the paper through one-sided contact with water, within a certain amount of time.
  • the machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
  • each of the sides shall be tested and fulfil the Cobb value, i.e. be in contact with water during measurements, the exposure time of testing is 60 seconds, and the test area is 100 cm 2 .
  • the machine glazed paper was conditioned at a temperature of 23°C and at 50% RT.
  • the machine glazed paper may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, preferably 0.4 wt.% to 2 wt.% of the dry weight of the machine glazed paper.
  • the machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
  • the machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
  • Alum aluminum sulfate
  • the machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
  • the amount of filler may be measured by means of ash content by the standard method ISO 1762:2001.
  • the type of fillers may be determined by Fourier- transform infrared spectroscopy (FTIR).
  • Bending resistance of the paper is measured herein according to the standard method ISO 2493-1.
  • the Cobb value of the paper as disclosed herein may be obtained by using a low amount of sizing agents in the paper in combination with adding of the starch in amounts as disclosed herein.
  • the machine glazed paper may comprise sizing agents in the paper in an amount of below 0.9 wt.%, such as to a level of below 0.5 wt.%.
  • the paper may be free from Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
  • the machine glazed paper comprises rosin in an amount of below 0.5 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, more preferably within the range of from 0.09 wt.% to 0.3 wt.%, based on the dry weight of the machine glazed paper.
  • the present disclosure also relates to a method for producing the machine glazed paper as disclosed herein, the method comprising the steps of;
  • a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight, the amount of softwood fibers of the total amount of fibers being 63 wt.% or more;
  • the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the according to the standard method ISO 535:2014.
  • the method comprises a pre-drying step, between the dewatering step and the glazing step, wherein the fibrous web is pre-dried in the pre-drying step to have a moisture content within the ranger of from 40 to 60 wt. %.
  • the present disclosure furthermore relates to a use of the machine glazed paper as disclosed herein for producing a paper stick.
  • the paper sticks may be used for example as ear buds or lollipop sticks.
  • a method of forming a paper stick from the machine glazed paper as disclosed herein comprises the following steps;
  • the cut paper stripe may have a length, as measured in the machine direction of the machine glazed paper, of about 60 to 80 mm, optionally from 65 to 75 mm, and a width, as measured in the cross direction of the machine glazed paper of about 250 to 350 mm, optionally from 280 to 320 mm.
  • the width of the machine glazed paper may have a width of 560 to 640 mm, such as typically when the final paper stick is a paper stick other than a paper stick for ear buds or lollipop stick.
  • the final pressed, sealed and cut paper sticks may have a diameter of about 2.2 to 2.7 mm, such as from 2.4 to 2.5 mm, and a length of about 70 to 80 mm, such as about 74 to 76 mm.
  • Three types of 60 gsm base paper were produced, each comprising 100% softwood fibers, starch, Alum and Rosin as disclosed in Table 1.
  • the paper was subjected by a large diameter steam-heated drying cylinder (MG cylinder) on one side, such that the paper has one side with a higher roughness.
  • MG cylinder steam-heated drying cylinder
  • Table 1 Each of the sample papers Exl-Ex3 were evaluated and the Cobb value on both side of the samples, air resistance, tensile strength CD/MD and bending resistance both in the MD and the CD directions were measured, see table 1 below for the results.
  • Table 2 Each of the sample papers Exl-Ex3 were evaluated and the Cobb value on both side of the samples, air resistance, tensile strength CD/MD and bending resistance both in the MD and the CD directions were measured, see table 1 below for the results. Table 2
  • the target Cobb values were achieved by reducing the amount of alum and rosin. No further sizing agents were included in the paper.
  • Example 2 paper sticks were produced using three different types of paper.
  • One paper, Ex. 4 according to the present invention a comparative example CExl, being a non-glazed paper comprising 100% softwood fibers and a comparative example CEx2, being a machine-glazed paper comprising 60% softwood fibers and 40% hardwood fibers.
  • a comparative example CExl being a non-glazed paper comprising 100% softwood fibers
  • a comparative example CEx2 being a machine-glazed paper comprising 60% softwood fibers and 40% hardwood fibers.
  • Paper sticks were produced according to the method disclosed above. Paper sticks were cut to a length of 71.5 mm, with a cutting length of 70 mm. The bending resistance of the paper sticks were measured with the L&W Bending tester from ABB measuring the force needed to bend a test piece at a predetermined angle.
  • a machine glazed paper comprising softwood fibers, the machine glazed paper comprising starch to an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, has a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014 and the machine glazed paper comprises 4 wt.% or less of fillers.
  • the machine glazed paper according to item 1 wherein the machine glazed paper comprises 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
  • fillers such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
  • the machine glazed paper according to any one of the preceding items, wherein the level of sizing agents in the machine glazed paper is below 0.9 wt.%, such as a level of below 0.5 wt.%, optionally, the paper is free from Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
  • ALD Alkylketen Dimer
  • ASA Alkenyl Succinic Anhydride
  • machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a basis weight within the range of from 35 gsm to 100 gsm, preferably within the range of from 38 gsm to 85 gsm.
  • machine glazed paper according to any one of the preceding items wherein the machine glazed paper has an CD/MD stretch ratio of 0.5 or higher.
  • machine glazed paper has a MD stretch of from 0.5% to 2%, preferably a MD stretch of from 1% to 1.9%, as measured according to the standard method ISO 1924/3.
  • machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a CD stretch of from 1.5% to 6.5%, preferably a CD stretch of from 2% to 5.5%, preferably a CD stretch of from 2% to 4.5%, as measured according to the standard method ISO 1924/3.
  • machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a first side and a second side, the second side having roughness of from 1000 ml/min to 2500 ml/min.
  • machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper is for use in a paper stick, such as ear buds or lollipop sticks.
  • a paper stick such as an ear bud stick or lollipop stick, comprising or consisting of the machine glazed paper according to any one of item 1 to 12.
  • a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight and the machine glazed paper comprises no more than 4 wt.% of fillers;

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  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
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Abstract

The present disclosure relates to a machine glazed paper comprising softwood fibers, the machine glazed paper comprising starch to an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, the amount of softwood fibers of the total amount of fibers being 63 wt.% or more, and the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. The present disclosure furthermore relates to a method of producing the machine glazed paper.

Description

MACHINE GLAZED PAPER AND METHOD FOR PREPARING THE MACHINE GLAZED PAPER
TECHNICAL FIELD
The present disclosure relates to the field of machine glazed paper and a method for preparing the machine glazed paper. More specifically the present disclosure relates to a machine glazed paper for preparing paper sticks.
BACKGROUND
There is an increasing requirement to minimize the use of single-use plastic items, such as cotton buds and lollipop sticks.
In view of these requirements there is a need to develop materials which may replace the plastics in such items.
Besides being one of the most abundant biopolymers on Earth, cellulose attracts considerable attention due to its high strength and stiffness combined with features like low weight, biodegradability and renewability. Paperbased materials have however traditionally been considered less suitable for replacement of such single-use plastic material, such as for example cotton buds and lollipop sticks, as paperbased items have been considered having low shape stability compared to such plastic items. It has also been difficult to attain a proper sealability without including components negatively affecting the degradability of the items. During manufacturing of such paper component, dusting and blunting have also been causing important issues in the converting machines.
In view of the above, it is an object to prepare an improved material suitable for use in preparing single-use paper sticks.
SUMMARY
It is an object of the present disclosure to provide a paper that at least partially overcome the above-described deficiencies. This is achieved by a machine-glazed paper according to claim 1, use of the machine-glazed paper according to claim 14, a paper stick comprising or consisting of the machine-glazed paper according to claim 15 and a method for producing the machine-glazed paper according to claim 16.
According to a first aspect, there is provided a machine glazed paper comprising softwood fibers and starch, the machine glazed paper comprising the starch in an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper and the amount of softwood fibers of the total amount of fibers is 63 wt.% or more. The machine glazed paper has a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
There are increasing demands and legislative requirements to replace plastic single-use items such as cotton bud sticks with biodegradable alternatives. Paperbased materials have however traditionally been considered less suitable for use in making cotton bud sticks or the like, as they have been considered to have low shape stability compared to such plastic sticks. It was found by the present inventors that by using a softwood fiber paper, having a high starch content and a fast water absorption, indicated by the Cobb value, according to the present disclosure, a paper particularly suitable for preparing paper sticks was achieved. The machine-glazed paper has improved sealability and when preparing paper sticks with the paper according to the present disclosure stiffer sticks with an improved straightness, as seen in the length direction of the sticks, but which still resist bending of the sticks without breaking was obtained. It was additionally and surprisingly found that this combination of features at least partly solves the problem of dusting and linting when preparing paper sticks from the paper according to the present disclosure.
The machine glazed paper comprises softwood cellulose fibers, also called long fibers. In native condition, softwood cellulose fibres measure from about 2 to 4 millimetres in length, compared to hardwood fibres ranging from about 0.5 to 1.5 millimetres. Common examples of softwood include pine, fir, spruce, larch and cedar. In paper, after refining the softwood fibers are below 2mm.
The paper comprises long fibers which enables production of paper sticks having an improved bending resistance and reduced dusting during slitting operations. The high starch content in combination with the high and fast water absorption of the paper has been found by the present inventors to enable an improved tensile strength and sealability of the paper during formation of paper sticks.
Both of the sides of the machine glazed paper, i.e. the glazed and the non-glazed side of the machine glazed paper, have a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
The machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
The machine glazed paper may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, preferably 0.4 wt.% to 2 wt.% of the dry weight of the machine glazed paper.
The Cobb value of the paper may be obtained by lowering the amount of sizing agents in the paper, such as to a level of below 0.9 wt.%, optionally to a level of below 0.5 wt.%. Preferably, the amount of sizing agents in the paper may be 0.3 wt.% or below, such as 0.1 wt.% or below. Optionally, the paper is free Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
The machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, even more preferably 0.2 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers. A machine glazed paper comprising softwood fibers and having a Cobb value according to the present disclosure comprising with 4 wt.% or less of fillers, based on the total dry weight of the paper, was found favourable with respect to dusting during cutting and blunting of the cutting and slitting tools. It was also found to increase the stiffness of paper sticks produced by the paper.
Optionally, 65 wt.% or more of the fibers in the machine glazed paper are softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably, from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
Optionally, from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
The fact that 65 wt.% or more of the fibers in the machine glazed paper are softwood fibers, such as from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers has been found favourable with respect to dusting during cutting of the paper and paper sticks formed by the paper according to the present disclosure.
The machine glazed paper may have a basis weight within the range of from 35 gsm to 100 gsm, preferably within the range of from 38 gsm to 85 gsm. It has been found that the machine glazed paper according to the present disclosure is within these ranges are particularly suitable for forming paper sticks. When using the machine glazed paper of higher basis weight, the stiffness was increased and when using lower ranges, the process of making the paper sticks was negatively affected since an increased number or rolling is needed which increases the complexity and the defect rate of the paper sticks during process.
The softwood fibers may be unbleached softwood fibers. It was surprisingly found that the sealability of the paper, during manufacturing of paper sticks, was improved by using unbleached softwood fibers.
The softwood fibers may alternatively be bleached softwood fibers or a mix between bleached and unbleached softwood fibers.
The machine glazed paper may have an CD/MD ration of from 0.5. This provides an indication that the fibers of the machine glazed paper mainly are oriented in the MD direction. During slitting of the paper, when manufacturing paper sticks, such fiber orientation was found advantageous in that dusting was reduced. The machine glazed paper may have a MD stretch of from 0.5% to 2%, preferably a MD stretch of from 1% to 1.9%, as measured according to the standard method ISO 1924/3. The fact that the machine glazed paper exhibited a MD stretch of from of from 0.5% to 2% enabled production of stiffer paper sticks by the paper according to the present disclosure.
The machine glazed paper may have a CD stretch of from 1.5% to 6.5%, preferably a CD stretch of from 2% to 5.5%, such as a CD stretch within the range of from 2 to 4.5%, as measured according to the standard method ISO 1924/3. The fact that the machine glazed paper exhibited a CD stretch of from 1.5% to 6.5% enabled production of stiffer paper sticks which also resist bending without breakage.
The fact that the first side of the paper is machine glazed provides the paper with enhanced sealing when being an inner side during paper stick production. The non-glazed side of the machine glazed paper may have a roughness of 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min. The fact that the second side, being the outer side during paper stick production, is a non-glazed side having a roughness of from 350 ml/min to 2000 ml/min, such as 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min, provides an improved adherence to, by frictional force, for example the cotton part in a cotton bud. It has also seen providing an improved user handfeel.
The paper may be a non-calendered paper, this provides an increased roughness for the non-glazed side of the paper.
The machine glazed paper may have an air resistance within the range of from 15 to 35 s, as measured according to the standard method ISO 5636 "Paper and board - Determination of air permeance (medium range) - Part 5: Gurley method. It was surprisingly found by the present inventor that the sealing speed of the machine glazed paper is improved when the air resistance of the paper is within the range of from 15 to 35 s.
The machine glazed paper may be for use to prepare paper sticks, such for ear buds or lollipop sticks.
According to a second aspect, the present disclosure relates to a use of the machine glazed paper according to the first aspect for producing a paper stick. According to a third aspect, the present disclosure relates to a paper stick, such as an ear bud stick or a lollipop stick comprising or consisting of the machine glazed paper according to the first aspect.
According to a fourth aspect, the present disclosure relates to a method for producing the machine glazed paper according to the first aspect, the method comprising the steps of;
- providing a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight and the amount of softwood fibers of the total amount of fibers are 63 wt.% or more;
- forming a fibrous web of the suspension;
- dewatering of the fibrous web;
- glazing the dewatered fibrous web in a glazing unit on a first side thereof and thereby forming the machine glazed paper, the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the according to the standard method ISO 535:2014.
The method may comprise a pre-drying step, between the dewatering step and the glazing step, wherein the fibrous web is pre-dried in the pre-drying step. The moisture content in the fibrous web may be controlled in the pre-drying step, and if needed, the moisture content in the fibrous web may be adapted in the pre-drying step. Optionally, the moisture content is within the range of from 40 to 60 wt. % when entering the glazing unit. This may for example be achieved by adapting the speed and/or the temperature of the drying cylinders.
It was discovered by the present inventors that the adherence to the cylinder in the glazing unit may be improved by controlling the moisture content of the fibrous web in a pre-drying step, and if necessary, adapting the moisture content of the fibrous web to be within a set moisture content range when entering the glazing unit. An unfavourable adherence/rejection of the fibrous web to the cylinder may give rise to a non-uniform drying of the fibrous web and such non- uniform drying was seen to provide a higher roughness value, impairing the sealing of the paper upon preparation of the paper sticks. However, by controlling the moisture content in the fibrous web in the pre-drying step, and adapting the moisture content when needed, the adherence to the cylinder may be improved and also the roughness of the surface, which may lead to an improved sealing of the paper sticks prepared by the machine glazed paper.
The roughness of the first side, i.e. the glazed side may be within the range of from 100 to 400 ml/min.
In the method for producing the machine glazed paper, 65 wt.% or more of the fibers in the machine glazed paper may be softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably, from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
Optionally, from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
The machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers. A machine glazed paper comprising softwood fibers and having a Cobb value according to the present disclosure comprising with 4 wt.% or less of fillers, based on the total dry weight of the paper, was found favourable with respect to dusting during cutting and blunting of the cutting and slitting tools. It was also seen increasing the stiffness of paper sticks produced by the paper. The amount of filler may be measured by means of ash content by the standard method ISO 1762:2001. The type of fillers may be determined by Fourier- transform infrared spectroscopy (FTIR).
In order to prepare a machine glazed paper according to the present disclosure, with such a high percentage of softwood fibers and a low, or no, percentage of fillers, sizing agents etc., it may be necessary to adjust the paper quality run previously in the paper machine to ensure that no fillers, sizing agents or nonsoftwood fibers from the previous paper quality are introduced into the fiber suspension by means of the waste water.
The machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
Optionally, the suspension may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% based on total dry weight, preferably 0.4 wt.% to 2 wt.% based on total dry weight.
The softwood fibers of the suspension may be unbleached or bleached softwood fibers.
The softwood fibers may alternatively be bleached softwood fibers or a mix between bleached and unbleached softwood fibers.
The machine glazed paper may have an CD/MD ration of from 0.5. This is an indication of that the fibers of the machine glazed paper may mainly be oriented in the MD direction, such as that 75 wt.% of the fibers of the machine glazed paper are oriented in the MD direction.
The second side of the machine glazed paper may have a roughness of from 350 ml/min to 2000 ml/min, optionally within the range of from 500 ml/min to 2000 ml/min, preferably within the range of from 350 ml/min to 1500 ml/min. This provides an improved adherence to, by frictional force, for example the cotton part in a cotton bud. It has also seen providing an improved user handfeel.
DETAILED DESCRIPTION
The present disclosure thus relates to a machine glazed paper comprising softwood fibers and starch. A major part of the fibers of the machine glazed paper are softwood fibers, i.e. 63 wt.% or more, or 65 wt.% or more, or from 85 wt.% to 100 wt.%, more preferably from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, such as 100 wt.% of the fibers. The machine glazed paper comprises starch in an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper. The machine glazed paper furthermore has a Cobb value within the range of from 20 gsm to 50 gsm.
The Cobb value is measured according to the standard method ISO 535:2014. The Cobb value provides information about the water absorption capacity of the paper sample and determines the amount of water that is absorbed by a defined area of the paper through one-sided contact with water, within a certain amount of time.
The machine glazed paper may have a Cobb value within the range of from 24 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. Optionally, within the range of from 25 gsm to 45 gsm.
When testing the machine glazed paper, each of the sides shall be tested and fulfil the Cobb value, i.e. be in contact with water during measurements, the exposure time of testing is 60 seconds, and the test area is 100 cm2. Prior to testing, the machine glazed paper was conditioned at a temperature of 23°C and at 50% RT.
The machine glazed paper may comprise the starch in an amount within the range of from 0.2 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, preferably 0.4 wt.% to 2 wt.% of the dry weight of the machine glazed paper.
The machine glazed paper may comprise rosin in an amount of below 1 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper, more preferably within the range of from 0.09 to 0.3 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise Alum (aluminum sulfate) in an amount within the range of from 0.1 wt.% to 1 wt.%, preferably within the range of from 0.1 wt.% to 0.5 wt.%, based on the dry weight of the machine glazed paper.
The machine glazed paper may comprise 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers. A machine glazed paper comprising softwood fibers and having a Cobb value according to the present disclosure comprising with 4 wt.% or less of fillers, based on the total dry weight of the paper, was found favourable with respect to dusting during cutting and blunting of the cutting and slitting tools. It was also seen increasing the stiffness of paper sticks produced by the paper.
The amount of filler may be measured by means of ash content by the standard method ISO 1762:2001. The type of fillers may be determined by Fourier- transform infrared spectroscopy (FTIR).
Bending resistance of the paper is measured herein according to the standard method ISO 2493-1.
The Cobb value of the paper as disclosed herein may be obtained by using a low amount of sizing agents in the paper in combination with adding of the starch in amounts as disclosed herein. The machine glazed paper may comprise sizing agents in the paper in an amount of below 0.9 wt.%, such as to a level of below 0.5 wt.%. The paper may be free from Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA). Optionally, the machine glazed paper comprises rosin in an amount of below 0.5 wt.%, preferably within the range of from 0.05 wt.% to 0.5 wt.%, more preferably within the range of from 0.09 wt.% to 0.3 wt.%, based on the dry weight of the machine glazed paper. The present disclosure also relates to a method for producing the machine glazed paper as disclosed herein, the method comprising the steps of;
- providing a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight, the amount of softwood fibers of the total amount of fibers being 63 wt.% or more;
- forming a fibrous web of the suspension;
- dewatering of the fibrous web; and
- glazing the dewatered fibrous web in a glazing unit on a first side thereof and thereby forming the machine glazed paper, the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the according to the standard method ISO 535:2014.
Optionally, the method comprises a pre-drying step, between the dewatering step and the glazing step, wherein the fibrous web is pre-dried in the pre-drying step to have a moisture content within the ranger of from 40 to 60 wt. %.
The present disclosure furthermore relates to a use of the machine glazed paper as disclosed herein for producing a paper stick. The paper sticks may be used for example as ear buds or lollipop sticks.
A method of forming a paper stick from the machine glazed paper as disclosed herein comprises the following steps;
- cutting the machine glazed paper in an asymmetrical paper strip, the paper strip being asymmetrical as seen in the length direction, corresponding to the machine direction of the paper, with an increasing width from a first longitudinal edge of the paper strips to a second longitudinal edge of the paper strip; forming grooves in the paper strip from the first longitudinal edge to the second longitudinal edge of the paper strip;
- rolling the paper strip, such as between a drum and a counterpart thereby forming a rolled paper stick;
- moistening and slitting of the rolled paper stick; and
- drying the moistened and slitted paper stick.
The cut paper stripe may have a length, as measured in the machine direction of the machine glazed paper, of about 60 to 80 mm, optionally from 65 to 75 mm, and a width, as measured in the cross direction of the machine glazed paper of about 250 to 350 mm, optionally from 280 to 320 mm. Alternatively, the width of the machine glazed paper may have a width of 560 to 640 mm, such as typically when the final paper stick is a paper stick other than a paper stick for ear buds or lollipop stick.
The final pressed, sealed and cut paper sticks may have a diameter of about 2.2 to 2.7 mm, such as from 2.4 to 2.5 mm, and a length of about 70 to 80 mm, such as about 74 to 76 mm. EXAMPLES
Example 1
Three types of 60 gsm base paper were produced, each comprising 100% softwood fibers, starch, Alum and Rosin as disclosed in Table 1. During drying, the paper was subjected by a large diameter steam-heated drying cylinder (MG cylinder) on one side, such that the paper has one side with a higher roughness.
Table 1
Figure imgf000013_0001
Each of the sample papers Exl-Ex3 were evaluated and the Cobb value on both side of the samples, air resistance, tensile strength CD/MD and bending resistance both in the MD and the CD directions were measured, see table 1 below for the results. Table 2
Figure imgf000013_0002
Figure imgf000014_0001
The target Cobb values were achieved by reducing the amount of alum and rosin. No further sizing agents were included in the paper.
Example 2 In this Example, paper sticks were produced using three different types of paper. One paper, Ex. 4 according to the present invention, a comparative example CExl, being a non-glazed paper comprising 100% softwood fibers and a comparative example CEx2, being a machine-glazed paper comprising 60% softwood fibers and 40% hardwood fibers. Ex. 4
Table 3
Figure imgf000014_0002
*kaolin
Paper sticks were produced according to the method disclosed above. Paper sticks were cut to a length of 71.5 mm, with a cutting length of 70 mm. The bending resistance of the paper sticks were measured with the L&W Bending tester from ABB measuring the force needed to bend a test piece at a predetermined angle.
The results are shown in table 4 and table 5 below.
Table 4
Figure imgf000015_0001
**length 20mm, angle 15°
Table 5
Figure imgf000015_0002
**length 20mm, angle 5°
As illustrated in Tables 4 and table 5, the bending resistance significantly improved for when preparing the paper sticks using a machine glazed paper according to the present disclosure compared to when using a paper comprising a higher amount of hardwood fibers or a non-machine-glazed paper. List of items
1. A machine glazed paper comprising softwood fibers, the machine glazed paper comprising starch to an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, has a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014 and the machine glazed paper comprises 4 wt.% or less of fillers.
2. The machine glazed paper according to item 1, wherein the machine glazed paper comprises 3 wt.% or less of fillers, such as 2 wt.% or less of fillers, preferably 1 wt.% or less of fillers, more preferably 0.5 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
3. The machine glazed paper according to item 1 or 2, wherein 63 wt.% or more of the fibers in the machine glazed paper are softwood fibers, optionally 65 wt.% or more of the fibers in the machine glazed paper are softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably, 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
4. The machine glazed paper according to item 1 or 2, wherein from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
5. The machine glazed paper according to any one of the preceding items, wherein the level of sizing agents in the machine glazed paper is below 0.9 wt.%, such as a level of below 0.5 wt.%, optionally, the paper is free from Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
6. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a basis weight within the range of from 35 gsm to 100 gsm, preferably within the range of from 38 gsm to 85 gsm.
7. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has an CD/MD stretch ratio of 0.5 or higher. 8. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a MD stretch of from 0.5% to 2%, preferably a MD stretch of from 1% to 1.9%, as measured according to the standard method ISO 1924/3.
9. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a CD stretch of from 1.5% to 6.5%, preferably a CD stretch of from 2% to 5.5%, preferably a CD stretch of from 2% to 4.5%, as measured according to the standard method ISO 1924/3.
10. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a first side and a second side, the second side having roughness of from 1000 ml/min to 2500 ml/min.
11. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has an air resistance within the range of from 15 to 35 s, as measured according to the standard method ISO 5636 "Paper and board - Determination of air permeance (medium range) - Part 5: Gurley method.
12. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper is for use in a paper stick, such as ear buds or lollipop sticks.
13. Use of the machine glazed paper according to any one of items 1 to 12 for producing a paper stick.
14. A paper stick, such as an ear bud stick or lollipop stick, comprising or consisting of the machine glazed paper according to any one of item 1 to 12.
15. A method for producing the machine glazed paper according to any one of items 1 to 12, the method comprising the steps of;
- providing a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight and the machine glazed paper comprises no more than 4 wt.% of fillers;
- forming a fibrous web of the suspension;
- dewatering of the fibrous web; - glazing the dewatered fibrous web in a glazing unit on a first side thereof and thereby forming the machine glazed paper, the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014. 16. The method for producing the machine glazed paper according to claim 15, wherein the softwood fibers of the suspension are unbleached softwood fibers.

Claims

1. A machine glazed paper comprising softwood fibers, the machine glazed paper comprising starch to an amount within the range of from 0.1 wt.% by weight to 2 wt.% of the dry weight of the machine glazed paper, an amount of softwood fibers of the total amount of fibers being 63 wt.% or more, and the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
2. The machine glazed paper according to claim 1, wherein the machine glazed paper comprises 4 wt.% or less of fillers, such as 3 wt.% or less of fillers, preferably 2 wt.% or less of fillers, more preferably 1 wt.% or less of fillers, based on the total weight of the paper, preferably the machine glazed paper is free from fillers.
3. The machine glazed paper according to claim 1 or 2, wherein 65 wt.% or more of the fibers in the machine glazed paper are softwood fibers, preferably 75 wt.% or more of the fibers in the machine glazed paper are softwood fibers, more preferably from 85 wt.% to 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
4. The machine glazed paper according to claim 1 or 2, wherein from 95 wt.% to 100 wt.% by weight of the of the fibers in the machine glazed paper are softwood fibers, preferably 100 wt.% of the fibers in the machine glazed paper are softwood fibers.
5. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper sizing agents in the paper, such as to a level of below 0.9 wt.%, such as to a level of 0.3 wt.% or lower, optionally, the paper is free from Alkylketen Dimer (AKD) and Alkenyl Succinic Anhydride (ASA).
6. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has a basis weight within the range of from 35 gsm to 100 gsm, preferably within the range of from 38 gsm to 85 gsm.
7. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has an CD/MD stretch ratio of 0.5 or higher.
8. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has a MD stretch of from 0.5% to 2%, preferably a MD stretch of from 1% to 1.9%, as measured according to the standard method ISO 1924/3.
9. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has a CD stretch of from 1.5% to 6.5%, preferably a CD stretch of from 2% to 5.5%, preferably a CD stretch of from 2% to 4.5%, as measured according to the standard method ISO 1924/3.
10. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has a first side and a second side, the second side having roughness of from 1000 ml/min to 2500 ml/min.
11. The machine glazed paper according to any one of the preceding items, wherein the machine glazed paper has a first side and a second side, the first side being the glazed side and having a roughness of from 100 ml/min to 400 ml/min.
12. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper has an air resistance within the range of from 15 to 35 s, as measured according to the standard method ISO 5636 "Paper and board - Determination of air permeance (medium range) - Part 5: Gurley method.
13. The machine glazed paper according to any one of the preceding claims, wherein the machine glazed paper is for use in a paper stick, such as ear buds or lollipop sticks.
14. Use of the machine glazed paper according to any one of claims 1 to 12 for producing a paper stick.
15. A paper stick, such as an ear bud stick or lollipop stick, comprising or consisting of the machine glazed paper according to any one of claim 1 to 12.
16. A method for producing the machine glazed paper according to any one of claims 1 to 12, the method comprising the steps of;
- providing a suspension comprising softwood fibers and starch, the starch being in an amount within the range of from 0.1 wt.% to 2 wt.% based on total dry weight and the amount of softwood fibers of the total amount of fibers in the suspension being 63 wt.% or more;
- forming a fibrous web of the suspension; - dewatering of the fibrous web;
- glazing the dewatered fibrous web in a glazing unit on a first side thereof and thereby forming the machine glazed paper, the machine glazed paper having a Cobb value within the range of from 20 gsm to 50 gsm, as measured according to the standard method ISO 535:2014.
17. The method according to claim 16, wherein the method comprises a predrying step, between the dewatering step and the glazing step, wherein the fibrous web is pre-dried in the pre-drying step to have a moisture content within the ranger of from 40 to 60 wt. %.
18. The method for producing the machine glazed paper according to claim 15, wherein the softwood fibers of the suspension are unbleached softwood fibers.
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