EP4179144A1

EP4179144A1 - Method for producing a cellulose-fibre-based drinking straw

Info

Publication number: EP4179144A1
Application number: EP21754888.2A
Authority: EP
Inventors: Lars Goran Berglund; Petr Jindra; Elisabeth SCHWAIGER
Original assignee: Mondi AG
Current assignee: Mondi AG
Priority date: 2020-07-10
Filing date: 2021-07-06
Publication date: 2023-05-17
Also published as: AT523915B1; WO2022006608A1; US20240018724A1; AT523915A4; CN115867706A

Abstract

The invention relates to a method for producing cellulose-fibre-based drinking straws (1) and to a cellulose-fibre-based drinking straw (1). The method comprises the following steps: - providing a cellulose material (2), - producing at least one aqueous suspension (3) comprising the cellulose material (2) and optionally adding additives (4) to the suspension (3), - homogenising the at least one aqueous suspension (3) and pre-drying to form at least one water-containing non-woven web (5) having a first side (6) and a second side (7), - drying the at least one water-containing non-woven web (5) in a plurality of drying steps to form at least one paper web (8) having a first side (6) and a second side (7), - further processing the at least one paper web (8) or a plurality of the paper webs (8) to form a cellulose-fibre-based drinking straw (1). According to the invention, at least the first side (6) of the at least one non-woven web (5) is compressed with a line load of 80 kN/m to 500 kN/m before, during or after one of the drying steps and before being further processed to form a cellulose-fibre-based drinking straw (1).

Description

PROCESS FOR MANUFACTURING CELLULOSE FIBER-BASED DRINKING STRAWS

The invention relates to a method for producing cellulose fiber-based drinking straws and a cellulose fiber-based drinking straw.

The demand for recyclable products is growing as a result of consumers' increased environmental awareness and, last but not least, also due to legal and normative regulations relating to disposable products in the packaging and food industries.

The replacement of plastic-based products with alternatives based on cellulose fibers has become established in many areas of the packaging and food industry. However, the use of cellulose fiber-based drinking straws instead of plastic-based drinking straws or straws confronts manufacturers with a number of specific problems. One of the greatest challenges for cellulose fiber-based drinking straws is to simultaneously offer waterproofness or water resistance - at least during their useful life - while at the same time being as complete and technically uncomplicated as possible to recycle is required.

According to the state of the art, papers are provided with coatings so that the required water resistance is guaranteed. Naturally, however, such coatings are problematic with regard to their recyclability. WO 2019175470 A1 should be mentioned here as an example, which presents a drinking straw in which the drinking straw material is basically recyclable and biodegradable but coated cardboard. The drinking straw consists of a substantially rectangular sheet-like piece of coated cardboard. However, WO 2019175470 A1 discloses very little about the properties of the paper or cardboard used.

The person skilled in the art is also aware of the use of papers with at least partial crosslinking of the cellulose fibers. To ensure that the paper for cellulose fiber-based drinking straws remains mechanically stable, at least temporarily, when exposed to moisture or moisture, so-called wet strength agents are added during paper manufacture. Wet-strength agents are water-miscible polymer solutions in the processing state, which primarily consist of polyamines and epichlorohydrin derivatives. be produced. Products based on urea-formaldehyde or melamine-formaldehyde are also conceivable as wet strength agents, but these are no longer preferred for reasons of avoiding health risks. When reacting with cellulose fibers, cross-links form between the fibers, which lead to increased water resistance of the corresponding paper. However, this hydrophobic linkage prevents easy or successful recycling. A return of used drinking straws to a cellulose cycle is therefore not possible or only possible to a limited extent through the use of high temperatures and/or additional chemicals and additives.

Bleached and/or unbleached cellulose fibers and mixtures thereof are conceivable as starting material for cellulose fiber-based drinking straws.

The object of the present invention was to provide a process for the production of cellulose fiber-based drinking straws which is as efficient as possible from a technical, economic and ecological point of view. In addition, the object of the invention was to provide a cellulose fiber-based drinking straw that satisfies the requirements of consumers - such as taste neutrality - and the packaging and food industry as well as aspects of sustainability such as recyclability, compostability and bio logical degradability.

This object is achieved by a manufacturing method and a cellulose fiber-based drinking straw according to the claims.

The method according to the invention for the production of cellulose fiber-based drinking straws comprises the steps:

- providing a pulp material,

- Production of at least one aqueous suspension comprising the cellulose material and optional addition of additives to the suspension,

- Equalizing the at least one aqueous suspension and pre-drying to at least one water-containing nonwoven web with a first side and a second side,

- Drying the at least one water-containing nonwoven web in several drying steps to at least one paper web with a first side and a second side,

- Further processing of the at least one paper web or several of the paper webs to egg nem cellulose fiber-based drinking straw. It is provided that at least the first side of the at least one fleece web is compressed before, during or after one of the drying steps and before further processing to form a cellulose fiber-based drinking straw with a line load of 80 kN/m to 500 kN/m.

The at least one-sided compression of the nonwoven web causes a cellulose fiber-based drinking straw made from a nonwoven web according to the invention or a paper web produced according to the invention to be water-resistant or water-resistant at least for the duration of its use. It has been found that the densification of the surface of the non-woven web causes the cellulose fibers in the vicinity of the surface to be smoothed. The compaction achieved in this way is equivalent to a kind of sealing, which works without any paints, coatings or similar auxiliary materials. This type of sealing reduces or even prevents liquids from penetrating undesirably or too quickly into the wall structure of the drinking straw. Premature softening can thus be effectively prevented or at least delayed for a sufficiently long period of time so that the function and dimensional stability of the drinking straw can be guaranteed during its period of use. Surprisingly, it has been shown that to achieve this "sealing effect" a one-sided compaction and a smoothing of the fleece web or the paper web that may go hand in hand with it is basically sufficient. Whether compression on both sides is advisable depends, among other things, on the specific application.

Since no non-recyclable additives or the like have to be added to bring about these properties, a cellulose fiber-based drinking straw produced according to the invention is also easily accessible for recycling or repulping, i.e. returning to an aqueous cellulose suspension. With any additives that are added to the aqueous suspension, care must be taken to ensure that only such additives are included that are harmless to a user and the environment with regard to an aqueous extraction application, such as the use of drinking straws are. This can apply to both cold and hot extraction applications. A cellulose fiber-based drinking straw produced according to the invention can be recycled without any additional effort or without additional complex process steps. Efficient “repulping” can be facilitated in particular if the process according to the invention does not require the addition of additives in the form of wet strength agents.

Furthermore, it can be expedient if at least the first side of the at least one fleece web is thermally treated in the course of compression. This can preferably be done in one or more steps at a temperature of 90°C to 97°C and/or at a temperature of 200°C to 295°C. A thermal treatment that takes place in addition to the pressurization can have an advantageous effect on the water resistance of the cellulose fiber-based drinking straw produced according to the invention. This can be achieved in that the influence of heat can bring about an additional smoothing or further compression of the surface of the fleece or paper web.

Provision can also be made for at least one nonwoven web to be compacted by means of a wide nip calender having a heating roller and a shoe roll which interacts with the heating roller and forms a wide nip, with the at least one nonwoven web being guided through the wide nip calender with its first side facing the heating roller. Such processing by means of a wide nip calender, which is also referred to as a shoe calender, can usually take place at the end of a drying section.

In addition, it can be provided that at least one nonwoven web is pressed with its first side against the surface of a heated drying cylinder by means of one or more pressure rollers, with the at least one nonwoven web being guided over a large part of the circumference of the drying cylinder and additionally by means of a drying cylinder at least least partially surrounding drying hood is heated from the outside. So-called “MG papers” (“machine-glazed” papers) or calendered papers can also be produced with low grammages and are generally easy to print on.

Also advantageous is an embodiment according to which it can be provided that the pulp material used is a pulp mixture consisting of long-fiber sulfate pulp and short-fiber sulfate pulp, preferably short-fiber sulfate pulp, with a length-weighted average fiber length according to ISO 16065-2:2014 from 1.05mm to 2.50mm. Sulfate pulp is also known to those skilled in the art under the term kraft pulp. It can be advantageous if the cellulose mixture is provided from 20% by weight to 80% by weight long-fiber sulphate cellulose and from 20% by weight to 80% by weight short-fibre cellulose, preferably short-fibre sulphate cellulose will. A mixture within the specified limits has proven to be particularly advantageous in practice for achieving good compressibility.

According to a further development, it is possible for the at least one suspension to contain at least one sizing agent as an additive based on the active substance of the sizing agent in an amount of 0.07% by weight to 1.0% by weight based on 100% by weight of the total dry matter of the at least is added to a suspension. The addition of sizing agents to at least one aqueous suspension is also referred to as internal sizing.

Lemer, it can be expedient if at least one sizing agent selected from a group consisting of alkenylsuccinic anhydride (ASA), alkyl ketene dimer (AKD), resin sizes or natural sizing agents, or a mixture of sizing agents selected from this group is added to the at least one suspension. The sizing agents mentioned can have a particularly advantageous effect on various properties of the paper web or of the cellulose fiber-based drinking straw. The addition of these sizing agents can have a positive effect on the contact angle of the paper web.

In addition, it can be provided that the at least one suspension is produced with a consistency of 0.15% to 0.70%. Depending on which special procedure is used for the compaction step, it can be advantageous if the aqueous suspension is used as a low-consistency suspension with a consistency of 0.15% to 0.30% or as a high-consistency suspension with a consistency of up to 0 .70% is manufactured. The consistency selected in each case can depend on the machine type, the laser material mixture, the drying performance of the machine and other other parameters.

Provision can also be made for one or more of the paper webs to be layered one on top of the other and connected in the course of further processing into a cellulose fiber-based drinking straw. The specific structure of such a layer can be adapted to the special requirements of the specific application. According to a particular embodiment, it is possible for the compressed first side of a paper web to be in contact with the uncompacted second side of the additional paper web layered on top.

According to an advantageous development, it can be provided that the paper webs are glued to one another, with an adhesive being applied over the entire surface or in sections to the contacting sides of the paper webs. Depending on the type of adhesive, applying it in sections can be sufficient to ensure permanent cohesion during use of the cellulose-fiber-based drinking straw. However, for hot applications or for repeated use of the drinking straw, it can also be advantageous if the adhesive is applied over the entire surface or at least over a large part of the contact surface.

Furthermore, it can be provided that the at least one paper web or several layered and connected paper webs are made up into paper strips in the course of further processing into a cellulose fiber-based drinking straw, with a paper strip being delimited by two leading edges and two transverse edges and with in the area of the two Each catch edge has an overlapping area, and that bending a paper strip around a drinking straw axis forms a preferably cylindrical hollow body that is open on both sides, with the paper strip being shaped in such a way that an overlapping section is formed by overlapping the two overlapping areas, and that the two overlapping areas are glued together in the overlapping section.

In addition, it can be provided that the paper strip is shaped in such a way that its two catch edges run essentially parallel to the axis of the drinking straw.

Also advantageous is an embodiment according to which it can be provided that the paper strip is formed in such a way that the two catch edges essentially run spirally or helically around the axis of the drinking straw.

Furthermore, it can be expedient if the first side of the at least one paper web is printed with food-safe and biodegradable inks before further processing into a cellulose-fiber-based drinking straw. Individual designs, brands, etc. can be applied to the cellulose fiber-based drinking straw. According to the invention, a cellulose fiber-based drinking straw is also provided, which is produced in particular by a method according to one of claims 1 to 16 and comprises a preferably cylindrical hollow body open on both sides with an outer surface and an inner surface. It is provided that the hollow body is formed by at least one shaped paper strip, the at least one paper strip being made up of at least one paper web with at least one compressed first side.

The use of a paper web compressed at least on one side has the effect that a cellulose fiber-based drinking straw produced from it is water-resistant or water-resistant at least for the duration of its use. It has been found that the compression of the surface of at least one paper web causes the cellulose fibers in the vicinity of the surface to be smoothed. The compaction achieved in this way is equivalent to a kind of sealing, which, however, works without any paint, coating or similar additives. This type of seal reduces or even prevents liquids from penetrating undesirably or too quickly into the wall structure of the drinking straw. Premature softening can thus be effectively prevented or at least delayed long enough so that the functionality and dimensional stability of the drinking straw can be guaranteed during its service life. Surprisingly, it has been shown that to achieve this “sealing effect” a one-sided compaction and a smoothing of the fleece web or the paper web that may go hand in hand with this is basically sufficient. Whether compression on both sides is appropriate depends, among other things, on the specific application.

Because no non-recyclable additives or the like have to be added to bring about these properties, a cellulose fiber-based drinking straw according to the invention is also easily accessible for recycling or repulping, i.e. returning to an aqueous cellulose suspension . With any additives that are added to the aqueous suspension, care must be taken to ensure that only such additives are included that are harmless to a user and the environment with regard to an aqueous extraction application, such as the use of drinking straws are. This can apply to both cold and hot extraction applications. A cellulose fiber-based drinking straw according to the invention can be recycled without any additional effort or without additional complex process steps. Efficient “repulping” can be facilitated in particular if the process according to the invention does not require the addition of additives in the form of wet strength agents.

Furthermore, it can be provided that the compacted first side of the at least one paper web has a Cobb 1800s value according to ISO 535:2014 of 24 g/m ² to 62 g/m ² .

Due to the fact that the Cobb 1800s value according to ISO 535:2014 represents an absolute value of the water absorption capacity of a paper, and the grammage of the paper can play a significant role or have a significant influence on this absolute value, a better comparability between different papers, a percentage of water content over the entire grammage range can also be meaningful for characterizing the paper properties. Such a percentage water content can be calculated from the relationship between a measured Cobb 1800s value according to ISO 535:2014 and the grammage of the paper. In particular, a percentage water content of 35% to 48% can be advantageous for a paper web - this under the assumption that 7% water in the paper as equilibrium moisture content when stored in a climate at 23°C ± 1°C and 50% ± 2% relative humidity according to ISO 187:1990 are present. Three sample calculations for different paper webs are given below as an example:

Example 1:

Grammage when stored in a standard climate at 23 °C ± 1 °C and 50% ± 2% relative humidity according to ISO 187:1990 = 40.0 g/m ²

Cobb 1800s value according to ISO 535:2014 = 26.2 g/ ^m2

Grammage of the paper according to the Cobb 1800s test = 66.2 g/m ²

Total water content in the paper according to the Cobb 1800s test = ((40.0/100*7)+26.2)/66.2 *100 = 43.8% Example 2:

Grammage when stored in a standard climate at 23 °C ± 1 °C and 50% ± 2% relative humidity according to ISO 187:1990 = 60.0 g/m ²

Cobb 1800s value according to ISO 535:2014 = 33.3 g/ ^m2

Grammage of the paper according to the Cobb 1800s test = 93.3 g/m ²

Total water content in the paper according to the Cobb 1800s test = 40.2%

Example 3:

Grammage when stored in a standard climate at 23 °C ± 1 °C and 50% ± 2% relative humidity according to ISO 187:1990 = 120.0 g/m ²

Cobb 1800s accordance with ISO 535: 2014 = 59.7 g / m ²

Grammage of the paper according to the Cobb 1800s test = 179.7 g/m ²

Total water content in the paper according to the Cobb 1800s test = 37.9%

In addition, it can be expedient if a difference in a Cobb 1800s value according to ISO 535:2014 between the compressed first side and the second side, which is not or less strongly compressed, is a maximum of 3 g/m ² . By less compacted is meant that the second side is less compacted compared to the first side because it is not pressed against a smooth surface, for example. According to the manufacturing processes and machine concepts, papers according to the invention with grammages preferably from 22 g/m ² to 200 g/m ² according to ISO 536:2012 can be used for the production of cellulose fiber-based drinking straws. In principle, however, the use of papers with lower, but also with higher grammages is of course also conceivable and possibly expedient.

According to a particular embodiment, it is possible for the compressed first side of the at least one paper web to have a Bendtsen roughness according to ISO 8791-2:2013 of 30 ml/min to 250 ml/min. According to an advantageous development, it can be provided that the at least one paper web has a gloss value of 20% to 35% according to TAPPI T 480:2015. It can be advantageous, particularly in a manufacturing process with shoe calenders, if a gloss value according to TAPPI T 480:2015 is from 21% to 25%. When manufacturing MG papers, it can be useful if the gloss value is from 24% to 33% according to TAPPI T 480:2015.

In particular, it can be advantageous if the compacted first side of the at least one paper web has a static contact angle according to ISO 19403-2:2020 with water as the test liquid used of 100° to 120°.

It can also be advantageous if the difference in a static contact angle according to ISO 19403-2:2020 using water as the test liquid between the compacted first side and the second side that is not or less compacted is a maximum of 6°. By less compacted is meant that the second side is less compacted compared to the first side because it is not pressed against a smooth surface, for example.

Furthermore, it can be provided that at least two paper webs are arranged such that the first side of the first paper web forms the outer surface of the hollow body and that the first side of the second paper web forms the inner surface of the hollow body.

For a better understanding of the invention, it is explained in more detail with reference to the following figures.

They each show in a greatly simplified, schematic representation:

Fig. 1 shows an embodiment of a process scheme for the production of a nonwoven web and its drying to form a paper web;

2 shows a further exemplary embodiment of a process diagram for producing a fleece web and drying it to form a paper web;

3 shows three paper webs layered one on top of the other in a three-dimensional exploded view;

4 shows a further paper web made up into a paper strip; 5 shows a three-dimensional representation of a cellulose fiber-based drinking straw;

6 shows another cellulose fiber-based drinking straw in a three-dimensional representation;

7 shows a three-dimensional view of a paper web that has been stacked or folded.

As an introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numbers or the same component designations, and the disclosures contained throughout the description can be transferred to the same parts with the same reference numbers or the same component designations. The position information chosen in the description, such as top, bottom, side, etc., is related to the directly described and illustrated figure and these position information are to be transferred to the new position in the event of a change of position.

The method for producing cellulose fiber-based drinking straws 1 begins, as is known, with the production of an aqueous suspension 3 comprising a cellulose material 2, with the optional addition of additives 4.

The person skilled in the art is well aware of how the cellulose material 2 can be produced, which is why the corresponding possible method steps are not described in detail, or are also not shown in the figures. For the sake of completeness, a possible process cascade is only briefly outlined at this point. A cellulose mixture consisting of long-fiber sulphate cellulose and short-fibre cellulose, preferably short-fibre sulphate cellulose, with a length-weighted, average fiber length according to ISO 16065-2:2014 of 1.05 mm to 2. 5 mm can be provided. The pulp mixture can be made up of 20 to 80% by weight of long-fiber sulphate pulp and 20 to 80% by weight of short-fibre cellulose, preferably short-fiber sulphate pulp. As a starting material for producing the cellulose material 2, for example, a cellulose mixture of comminuted hardwood can be used as sulphate cellulose and comminuted softwood can be used as sulphate pulp. Of course, it can also be a mixture of different, crushed hardwoods and softwoods. This pulp mixture is prepared by a process comprising chemically treating the comminuted first and second pulp in a digester. Depending on the requirement, it can be useful if, after the chemical treatment, mechanical processing and defibration of an aqueous solids suspension of the pulp mixture is carried out in a high-consistency defibrator. For example, a consistency of the solids suspension prior to mechanical processing and defibration in the high-consistency pulper can be adjusted to 25% to 40%. Such defibration in a high-consistency defibrator serves, among other things, to reduce the so-called splinter content of the pulp mixture, ie to break up pulp agglomerates that are still wood-like. In addition, it can also be expedient if, after the first mechanical processing and defibration in the high-consistency defibrator, mechanical processing and grinding of the pulp mixture or an aqueous solids suspension of the pulp mixture is carried out in a low-consistency refiner. A consistency of the solids suspension prior to mechanical processing and grinding in the low-consistency refiner can suitably be adjusted to 2% to 6%. Provision can certainly also be made for only mechanical processing of the pulp mixture to be carried out in a high-consistency defibrator. In other cases, however, it can also be useful for defibration in a high-consistency defibrator to be superfluous and only mechanical processing of the pulp mixture to be carried out in a low-consistency refiner. The specific refining performance of the individual refining stages must be adapted to the selected pulp mixture and the desired paper parameters.

In the following, the description of FIGS. 1 and 2 is made together as far as is reasonable and possible in order to avoid unnecessary repetitions, the same reference numbers being used for the same parts. FIGS. 1 and 2 each show an exemplary embodiment of a process scheme for producing a nonwoven web 5 and drying it to form a paper web 8.

Irrespective of how the cellulose mixture is prepared to provide a cellulose material 2, at least one aqueous suspension 3 comprising the cellulose material 2 is produced for further processing of the cellulose material 2. This process step is shown in Figures 1 and 2, for example illustrated by means of a tank 28 with an agitator. In particular, this at least one aqueous suspension 3 can be admixed with various additives 4 or aggregates and auxiliaries, such as fillers, starch, etc. that are customary in paper technology. It can be the at least one suspension 3 as an additive 4 at least one sizing agent based on the active substance of Sizing agent in an amount of 0.07% by weight to 1.0% by weight based on 100% by weight of total dry matter of the at least one suspension 3 are added. Sizes can be selected from a group consisting of alkenylsuccinic anhydride (ASA), alkyl ketene dimer (AKD), resin sizes or natural sizes, or a mixture of sizes selected from this group.

Irrespective of this, the consistency of the at least one aqueous suspension 3 can be reduced to a value of 0.15% to 0.8%, preferably from 0 .3% to 0.7% can be set. The further processing of this at least one aqueous suspension 3 can then be carried out, as is known per se, by means of a paper machine 29, as is described roughly schematically below with reference to FIGS. Typically, paper machines 29 may include a wire section 30, a press section 31 and a dryer section 32, each of these process steps being drying or dewatering operations. According to the invention, at least the first side 6 of the at least one fleece web 5 is compressed before, during or after one of the drying steps and before further processing to form a cellulose fiber-based drinking straw 1 with a line load of 80 kN/m to 500 kN/m . This compression step can either be generated in a single nip, i.e. compression step, or in several nips arranged one behind the other, each with the specified line loads. In addition, it can be expedient if at least the first side 6 of the at least one fleece web 5 is thermally treated in the course of this compression. In other words, this means that a thermal influence can take place in the same process step at the same time as the pressure is applied.

As shown in FIGS. 1 and 2, the at least one aqueous suspension 3 comprising the cellulose material 2 can be applied to a circulating endless screen 33 of a screen section 30, as is known per se. In such a wire section 30, the at least one aqueous suspension 3 is moderated and pre-dried to form at least one water-containing nonwoven web 5. The endless wire 33 can be guided over dewatering means 34 of the wire section 30, which dewatering means 34 can be formed by suction strips, for example. In principle, dewatering in a wire section 30 can also take place solely by means of gravity. In addition, however, depending on the design of a wire section 30, for example, the dewatering or pre-drying of the at least one Nonwoven web 5 are supported by generating a negative pressure. The at least one first fleece web 5 comprising the cellulose material 2 can be pre-dried by means of the wire section 30, for example to a water content of 75% by weight to 85% by weight.

The at least one fleece web 5 can then be further dewatered or further dried by means of a press section 31, as shown in FIGS. According to FIG. 1, the nonwoven web 5 can be passed between rollers 35 of the press section 31 and thereby be further dewatered under pressure. In addition, further drying can be supported by means of absorbent support material 36 . As is known per se, felt mats, for example, can be used for this purpose. As is known per se, a press section 31 according to FIG. 1 can comprise more than just two rolls 35; in particular, a plurality of roll pairs formed by rolls 35 can be arranged one after the other. A water content of the fleece web 5 after it has been passed through a press section 31 can be, for example, approximately 45% by weight to 65% by weight, based on the total mass of the fleece web 5 .

According to FIG. 1, a so-called slalom dryer 37 can be arranged after the press section 31 as a drying section 32 or as part of a drying section 32 . As shown in FIG. 1, a slalom dryer 37 can comprise numerous rotating drying cylinders 15 over which the at least one nonwoven web 5 can be guided. The drying cylinders 15 can be heated directly. For example, heating ducts (not shown in detail) can be designed to conduct superheated steam into the drying cylinder 15 . Alternatively, for example, the drying cylinder 15 can also be heated by means of an electrical resistance heater. A temperature of the drying cylinders 15 of a drying section 32 can, for example, rise successively in the direction of passage of the at least one nonwoven web 5 . The fleece web 5 can be dried by means of the slalom dryer 37, for example to a water content of 1% by weight to 10% by weight.

For compression according to the invention with a fin load of preferably 210 kN/m to 370 kN/m, a so-called wide nip calender 9 or shoe calender with a shoe length of, for example, 50 mm and a shoe tilt of 24% can be used in the dryer section 32 downstream of a slalom dryer 37 Drying and compression of the fleece web 5 may be provided. For compaction according to the invention with a final load of preferably 380 kN/m to 490 kN/m, a shoe length of 75 mm and a shoe tilt of 24% can also be provided in a shoe calender, for example. A wide nip calender 9 can essentially be formed by a heating roll 10 and by a shoe roll 12 cooperating with the heating roll 10 . The shoe roll 12 can act as a flexible counter-pressure element for the heating roll 10 and can have a peripheral jacket 38 . This peripheral jacket 38 interacts with the heating roller 10 and forms a wide nip 11 . This means that the fleece web 5 is simultaneously compressed with increased pressure and subjected to an increased temperature. Temperatures on the surface of the heating roller can be from about 250°C to 295°C, for example. The temperature can be achieved, for example, using a thermal oil with a correspondingly higher oil flow temperature. Other heating elements, such as induction heating, can also be provided to further stabilize the surface temperatures. In principle, it is also conceivable, but not shown in the figures, that a second, advantageously structurally identical wide nip calender 9 is provided, which is arranged in the paper machine 29 in such a way that a so-called calendering of the second side 7 is carried out in addition to the calendering of the first side 6 of the at least one Fleece web 5 can be done.

It is also conceivable that after the wire section 30, a procedural combination of press section 31 and dryer section 32 is provided, by means of which the compression according to the invention with a line pressure of approx. 80 kN/m in a first shoe press, in a second smoothing press with approx kN/m and in a third smoothing press with approx. 100 kN/m. The surface temperature of the Yankee cylinder can be about 94°C, for example. This conceivable embodiment is roughly shown schematically in FIG. As an alternative to the embodiment variant according to FIG. 1, FIG. Papers which are produced by means of such an arrangement or a comparable arrangement are usually referred to in the technical world as “machine-glazed” or “MG papers”. As part of a paper machine 29, FIG. 2 thus shows a combined press section 31 and drying section 32 in the form of a Yankee cylinder 39 with an attached drying hood 16 or gas drying hood. The at least one nonwoven web 5 adhering to a pick-up felt is pressed with its first side 6 by two pressure rollers 13 against the surface 14 of the steam-heated Yankee cylinder 39 and dried further or completely by additional blowing of hot air by means of the drying hood 16. The end of the paper machines 29 shown as an example according to FIGS. 1 and 2 is represented by a winder 40, by means of which the finished at least one paper web 8 can be wound onto a roll. Alternatively, however, it is also conceivable and possibly also expedient if the at least one paper web 8 is fed directly to further processing or packaging.

Depending on how a paper machine 29 is constructed, the at least one suspension 3 can be produced with a consistency of 0.15% to 0.70%. Both high-consistency and low-consistency suspensions 3 can be used for arrangements based on FIG. 1 with a wide nip calender 9, while for an arrangement based on FIG. 2 with a Yankee cylinder 39, a low-consistency suspension 3 with a consistency of 0.15% to 0.30% may be more appropriate.

For the production of cellulose fiber-based drinking straws 1 from at least one paper web 8, a large number of different methods are well known to the person skilled in the art, which is why the possible method steps are not discussed in detail.

Advantageously, one, but also several, preferably three or also four, of the paper webs 8 produced according to the invention can be further processed into a cellulose fiber-based drinking straw 1 . In the course of further processing, one or more paper webs 8 made from the same cellulose material 2, ie several identical paper webs 8, can be layered one on top of the other. However, it is also conceivable and has proven to be particularly advantageous if several paper webs 8 made from different cellulose materials 2 and thus having different technical properties are layered one on top of the other and connected.

A single paper web 8 can also be further processed, for example, by a corresponding single or multiple fold. For example, a single paper web 8 can be folded several times in a zigzag or meandering manner, so that a quasi multi-layered or stacked paper web 8 is formed. This conceivable embodiment is shown in FIG. 7 in a schematic three-dimensional view. With such a fold, the compressed first side 6 contacts each other and the non-compacted second side 7 contacts each other. A similar paper strip 18, as exemplified by FIG. larisch outlined and described below, are manufactured. A strip of paper folded in this way consisting of the paper according to the invention can be fixed in its position by means of appropriately selected adhesive points using an adhesive 17 . An adhesive 17--which is not explicitly shown in FIG. 7--can be applied for this purpose, for example, over the entire surface, at points, or else in strips between the folded layers.

FIG. 3 shows three paper webs 8 layered one on top of the other in a three-dimensional exploded view. A smaller or larger number of paper webs 8 can of course also be provided. It can be useful if the uppermost of the three paper webs 8 shown was compressed on a paper machine 29 with a wide nip calender 9 and if the middle and the lower paper web 8 were compressed on an MG machine using a Yankee cylinder 39. An arrangement of three layered Papierbah NEN 8 with a compressed by means of a Yankee cylinder 39, uppermost paper web 8 and each with a compressed by means of a wide nip calender 9 middle and lower paper web 8 can be useful. The paper webs 8 can be layered one on top of the other, as shown in FIG. Alternatively, but not shown in the figures, it can also be advantageous if the paper webs 8 are stacked one on top of the other in such a way that the compressed first side 6 of the two outer paper webs 8 is on the outside. At this point it should be noted that an uncompacted second page 7 can also be a page that is less compressed than the compressed first page 6 .

Alternatively, but also not shown in the figures, it can also be advantageous if at least one layer is made of the paper produced according to the invention in an arrangement of several paper webs 8 . In particular, it can also be expedient if primarily one of the two outer paper webs 8, ie one of the two paper webs that come into direct contact with a drinking liquid, is produced according to the method according to the invention. However, it can also be advantageous that both of the paper webs 8 lying on the outside of the finished cellulose fiber-based drinking straw 1 are produced according to the method according to the invention. It can be useful if the compressed first page 6 is in direct contact with a liquid. By a targeted arrangement of the paper webs 8 can various parameters or product properties, such as optical properties such as gloss, printability, feel and the like, can be set accordingly in an advantageous manner.

The paper webs 8 can be glued to one another, with an adhesive 17 being applied over the entire surface or in sections to the contacting sides 6, 7 of the paper webs 8 who can. FIG. 3 shows that the adhesive 17 can be applied in strips and approximately symmetrically to one side 6, 7 of a paper web 8 in each case. Depending on the requirements and adhesive strength, it is of course also conceivable that the adhesive 17 can be applied over the entire surface and to each contacting side 6, 7 or only at certain points or along the edges of the sheet. In particular, to achieve food approval for the cellulosic fiber-based drinking straw 1 and with regard to any leaching of ingredients from the cellulosic fiber-based drinking straw when it comes into contact with cold and/or hot liquids, it can be important if the adhesive 17 is a food-safe, biological biodegradable glue of animal and/or plant origin is used. Different legal requirements and recommendations apply to the harmless use of paper, cardboard and cardboard that is intended for direct contact with food. To name just a few relevant ones, for example, Recommendation XXXVI of the Federal Institute for Risk Assessment and also Recommendation XXXVI/1 for boiling and hot filter papers should be consulted. Regulation (EC) No. 1935/2004 and the Food, Consumer Goods and Feed Codes are examples of these. Other national regulations are Decreto Ministeriale 21 marzo 1973, Code of Federal Regulations, Food and Drugs (FDA), 21 CFR Ch. I (issue April 1, 2019), §§ 176.170 and 176.180, Regeling von de Minister von Volksgezondheid, Welzijn from 14 maart 2014, code 328583-117560-VGP, Warenwetregeling, Mercosure and Chinese regulations mentioned.

A single paper web 8, but also paper webs 8 layered in the sense of FIG. 3, can be made up into paper strips 18 in the course of further processing into a cellulose fiber-based drinking straw 1. To illustrate this, a further paper web 8 made up into a paper strip 18 is shown in FIG. A paper strip 18 can be delimited by two longitudinal edges 19 and two transverse edges 20, it being possible for an overlapping region 21 to be formed in the region of each of the two longitudinal edges 19. The length 41 of such a paper strip 18 can correspond to a multiple of the length 25 of a finished cellulose fiber-based drinking straw 1 . Possible positions for subsequent cutting areas are shown in FIG. 3 by dashed lines. It is also possible for the first side 6 of the at least one paper web 8 to be printed with food-safe and biodegradable inks before further processing into a cellulose-fiber-based drinking straw 1 .

FIGS. 5 and 6 also show two conceivable embodiments of cellulose fiber-based drinking straws 1 in a three-dimensional representation, the cellulose fiber-based drinking straws 1 comprising a preferably cylindrical hollow body 23 which is open on both sides and has an outer jacket surface 26 and an inner jacket surface 27 . It is provided that the hollow body 23 is formed by at least one shaped paper strip 18 , the at least one paper strip 18 being made up of at least one paper web 8 with at least one compressed first side 6 . As an alternative to cylindrical hollow bodies 23, drinking straws 1 with a canted or polygonal cross-section are also conceivable, for example.

By bending a paper strip 18 around a drinking straw axis 22, a preferably cylindrical hollow body 23 open on both sides can be formed, wherein the at least one paper strip 18 can be shaped in such a way that an overlapping section 24 is formed by overlapping the two overlapping areas 21. The cylindrical hollow body 23 can subsequently be cut approximately or largely radially to the drinking straw axis 22 into a finished length 25 of, for example, 5 cm to 50 cm. The at least one paper strip 18 can be shaped in such a way that its two longitudinal edges 19 essentially run parallel to the axis 22 of the drinking straw, as is shown schematically in FIG. Alternatively, FIG. 6 shows that it is also conceivable for the two longitudinal edges 19 to run essentially spirally or helically around the axis 22 of the drinking straw. Advantageously, the two overlapping areas 21 can be glued together in the overlapping section 24 .

At least two paper webs 8 can be arranged such that the first side 6 of the first paper web 8 forms the outer surface 26 of the hollow body 23 and that the first side 6 of the second paper web 8 forms the inner surface 27 of the hollow body 23 . It can be the case here that one or more further paper webs 8 are formed between the two outer ones, ie between the first and the second paper web 8 . With these internal ones or intermediately layered paper webs 8 can be paper webs 8 according to the invention, as well as various other papers with optionally additional advantageous properties. It is also possible for at least two paper webs 8 to be arranged in such a way that the second side 7 of the first paper web 8 that is uncompacted or compressed to a lesser extent than the first side 6 forms the outer surface 26 of the hollow body 23 and that the uncompacted side or, compared to the first page 6 less compressed second page 7 of the second paper web 8, the inner surface 27 of the hollow body 23 forms.

The compressed first side 6 of the at least one paper web 8 or of the paper webs 8 can have a Cobb 1800s value according to ISO 535:2014 of 24 to 62 g/m ² . A difference in a Cobb 1800s value according to ISO 535:2014 can advantageously be a maximum of 4 g/m ² between the compressed first side 6 and the second side 7 that is not compressed or compressed to a lesser extent. In addition, the compressed first side 6 of the paper web(s) 8 can have a Bendtsen roughness according to ISO 8791-2:2013 of 30 to 250 ml/min. It can also be advantageous if the paper web(s) 8 have a gloss value according to TAPPI 480 of 20 to 35%. Furthermore, the compressed first side 6 of the paper web(s) 8 can have a static contact angle according to ISO 19403-2:2020 with water as the test liquid of 100° to 120°. A difference in a static contact angle according to ISO 19403-2:2020 using water as the test liquid can be a maximum of 6° between the compressed first side 6 and the second side 7 that is not compressed or less compressed.

The exemplary embodiments show possible variants, it being noted at this point that the invention is not limited to the specifically illustrated variants of the same, but rather that various combinations of the individual variants are possible with one another and these possible variations are based on the teaching of technical action due to the present invention lies within the ability of a person skilled in the art working in this technical field.

The scope of protection is determined by the claims. However, the description and drawings should be used to interpret the claims. Individual features or combinations of features from the different exemplary embodiments shown and described can represent independent inventive solutions. The the independent inventive solutions underlying problem can be found in the description who the.

All information on value ranges in the present description is to be understood in such a way that it also includes any and all sub-ranges, e.g. the information 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit 1 and the upper limit 10 are, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

Finally, for the sake of clarity, it should be pointed out that some elements are shown not to scale and/or enlarged and/or reduced in order to better understand the structure.

list of reference numbers

Cellulosic fiber-based drinking straw 31 press section

Pulp material 32 dryer section

Suspension 33 endless screen

Additive 34 dehydrating agent

Fleece web 35 Roller first side 36 Supporting material wide side 37 Slalom dryer

Paper web 38 coat

Wide nip calender 39 Y ankee cylinder

Heat roller 40 winder

Wide nip 41 length

shoe roll

pressure roller

surface

Drying szy linder

drying hood

Glue

paper strips

long edge

transverse edge

Overlap area drinking straw axis hollow body

overlap section

length

shell outer surface

jacket inner surface

tank

paper machine

wire section

Claims

P atentClaims

1. Method for producing cellulose fiber-based drinking straws (1) comprising the steps:

- providing a cellulose material (2),

- Production of at least one aqueous suspension (3) comprising the cellulose material (2) and optionally adding additives (4) to the suspension (3),

- Equalizing the at least one aqueous suspension (3) and pre-drying to at least one water-containing nonwoven web (5) with a first side (6) and a second side

(7),

- Drying the at least one water-containing fleece web (5) in several drying steps to form at least one paper web (8) with a first side (6) and a second side

(7),

- Further processing of the at least one paper web (8) or more of the paper webs (8) to form a cellulose fiber-based drinking straw (1), characterized in that at least the first side (6) of the at least one nonwoven web (5) before, during or after a of the drying steps and before further processing to form a cellulose fiber-based drinking straw (1) with a line load of 80 kN/m to 500 kN/m.

2. The method according to claim 1, characterized in that at least the first side (6) of the at least one fleece web (5) is thermally treated in the course of compression, preferably at a temperature of 90 ° C to 97 ° C and / or at a Temperature from 200°C to 295°C is thermally treated.

3. The method according to any one of claims 1 or 2, characterized in that at least one nonwoven web (5) by means of a wide nip calender (9) having a heating roller (10) and one with the heating roller (10) and one wide nip (11) forming shoe roll (12) is compacted, the at least one fleece web (5) being guided through the wide nip calender (9) with its first side (6) facing the heating roll (10).

4. The method according to any one of claims 1 or 2, characterized in that at least one fleece web (5) by means of one or more pressure rollers (13) with its first Side (6) is pressed against the surface (14) of a heated drying cylinder (15), where the at least one nonwoven web (5) is guided over a large part of the circumference of the drying cylinder (15) and additionally by means of a drying cylinder (15) at least partially surrounding drying hood (16) is heated from the outside.

5. The method according to any one of the preceding claims, characterized in that the pulp material (2) is a pulp mixture consisting of long-fiber sulfate pulp and short-fiber sulfate pulp, preferably short-fiber sulfate pulp, with a length-weighted average fiber length according to ISO 16065-2:2014 from 1.05 mm to 2.50 mm.

6. The method according to claim 5, characterized in that the pulp mixture consists of 20% by weight to 80% by weight long-fiber sulphate pulp and 20% by weight to 80% by weight short-fibre cellulose, preferably short-fibre sulphate pulp, is provided.

7. The method according to any one of the preceding claims, characterized in that the at least one suspension (3) contains at least one sizing agent as an additive (4) based on the active substance of the sizing agent in an amount of 0.07% by weight to 1.0% by weight .% Based on 100% by weight of total dry matter, the at least one suspension (3) is added.

8. The method according to claim 6, characterized in that the at least one suspension (3) contains at least one sizing agent selected from a group consisting of alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), resin sizes or natural sizing agents, or a mixture of sizing agents selected from these group is added.

9. The method according to any one of the preceding claims, characterized in that the at least one suspension (3) is produced with a consistency of 0.15% to 0.70%.

10. The method according to any one of the preceding claims, characterized in that in the course of further processing to form a cellulose fiber-based drinking straw (1), one or more of the paper webs (8) are layered one on top of the other and connected.

11. The method according to claim 10, characterized in that the compressed first side (6) of a paper web (8) is contacted with the uncompacted second side (7) of the additional paper web (8) layered on top.

12. The method according to claim 10 or 11, characterized in that the paper webs (8) are glued together, with an adhesive (17) being applied to the contacting sides (6, 7) of the paper webs (8) over the entire surface or from sections .

13. The method according to any one of the preceding claims, characterized in that the at least one paper web (8) or several layered and connected paper webs (8) are made into paper strips (18) in the course of further processing into a cellulose fiber-based drinking straw (1). , wherein a paper strip (18) is delimited by two longitudinal edges (19) and two transverse edges (20) and in the region of each of the two longitudinal edges (19) an overlapping area (21) is formed, and that by bending a paper strip (18 ) a drinking straw axis (22) is formed around a hollow body (23) which is open on both sides and is preferably cylindrical, the paper strip (18) being shaped in such a way that an overlapping section (24) is formed by overlapping the two overlapping areas (21), and that the two overlapping areas (21) are glued together in the overlapping section (24).

14. The method according to claim 13, characterized in that the paper strip (18) is formed in such a way that its two longitudinal edges (19) run essentially parallel to the axis (22) of the drinking straw.

15. The method according to claim 13, characterized in that the paper strip (18) is shaped in such a way that the two longitudinal edges (19) run essentially in a spiral or coil shape around the axis (22) of the drinking straw.

16. The method as claimed in one of the preceding claims, characterized in that the first side (6) of the at least one paper web (8) is printed with food-safe and biodegradable inks before further processing into a cellulose-fiber-based drinking straw (1).

17. A cellulose fiber-based drinking straw (1), in particular produced by a method according to any one of claims 1 to 16, comprising a preferably cylindrical hollow body (23) which is open on both sides and has an outer surface (26) and an inner surface (27), characterized in that the hollow body (23) is formed by at least one shaped paper strip (18), the at least one paper strip (18) being made up from at least one paper web (8) with at least one compressed first side (6).

18. Cellulose fiber-based drinking straw (1) according to claim 17, characterized in that the compressed first side (6) of the at least one paper web (8) has a Cobb 1800s value according to ISO 535:2014 of 24 g/m ² to 62 g /m ² .

19. cellulose fiber-based drinking straw (1) according to any one of claims 17 or 18, characterized in that a difference in a Cobb 1800s value according to

ISO 535:2014 between the compressed first side (6) and the uncompacted or less compressed second side (7) is a maximum of 3 g/m ² .

20. Cellulose fiber-based drinking straw (1) according to one of claims 17 to 19, characterized in that the compressed first side (6) of the at least one paper web (8) has a Bendtsen roughness according to ISO 8791-2:2013 of 30 ml/ min to 250 ml/min.

21. Cellulose fiber-based drinking straw (1) according to one of claims 17 to 20, characterized in that the at least one paper web (8) has a gloss value according to TAPPI T 480:2015 of 20 to 35%.

22. Cellulose fiber-based drinking straw (1) according to any one of claims 17 to 21, characterized in that the compressed first side (6) of the at least one paper web (8) has a static contact angle according to ISO 19403-2:2020 using water as the test liquid of 100° to 120°.

23. Cellulose fiber-based drinking straw (1) according to any one of claims 17 to 22, characterized in that a difference in a static contact angle according to ISO 19403-2: 2020 using water as a test liquid between the compressed th first side (6) and the not or less strongly compressed second side (7) is a maximum of 6°.

24. Cellulose fiber-based drinking straw (1) according to one of claims 17 to 23, characterized in that at least two paper webs (8) are arranged in such a way that the first side (6) of the first paper web (8) covers the outer surface (26) of the Hollow body (23) forms and that the first side (6) of the second paper web (8) forms the lateral inner surface (27) of the hollow body (23).