METHOD FOR PRODUCING A CELLULOSE-FIBRE-BASED DRINKING STRAW
20240018724 ยท 2024-01-18
Assignee
Inventors
Cpc classification
D21H23/04
TEXTILES; PAPER
International classification
D21H23/04
TEXTILES; PAPER
Abstract
A method for producing cellulose-fibre-based drinking straws and a drinking straw. The method comprises: providing a cellulose material, producing at least one aqueous suspension comprising the cellulose material and adding additives to the suspension, homogenizing the aqueous suspension and pre-drying to obtain at least one water-containing non-woven web having a first side and a second side, drying the water-containing non-woven web in a plurality of drying steps to form at least one paper web having a first side and a second side, further processing the paper web or a plurality of paper webs to form a cellulose-fibre-based drinking straw.
At least the first side of the non-woven web 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 the further processing to form a cellulose-fibre-based drinking straw.
Claims
1. Method for producing cellulose-fibre-based drinking straws comprising the steps: providing a cellulose material, producing at least one aqueous suspension comprising the cellulose material and adding additives to the suspension, homogenizing the at least one aqueous suspension and pre-drying to obtain at least one water-containing non-woven web having a first side and a second side, drying the at least one water-containing non-woven web in a plurality of drying steps to form at least one paper web having a first side and a second side, further processing the at least one paper web or plurality of paper webs to form a cellulose-fibre-based drinking straw, wherein at least the first side of the at least one non-woven web 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 the further processing to form the cellulose-fibre-based drinking straw, wherein a cellulose mixture consisting of long-fibre sulphate cellulose and short-fibre cellulose is provided as the cellulose material, and that at least the first side of the at least one non-woven web is thermally treated in the during the compression.
2. The method according to claim 1, wherein the at least one non-woven web is compressed of a broad-nip calender comprising a heated roller and a shoe roller cooperating with the heated roller and forming a broad nip, wherein the at least one non-woven web is guided through the broad-nip calender with its first side facing the heated roller.
3. The method according to claim 1, wherein the at least one non-woven web is pressed by means of one or more pressure rollers with its first side onto the surface of a heated drying cylinder, wherein the at least one non-woven web is guided over a large part of the circumference of a drying cylinder and is additionally heated from outside by means of a drying hood which at least partially surrounds the drying cylinder.
4. The method according to claim 1, wherein the cellulose mixture is prepared from 20 wt. % to 80 wt. % long-fibre sulphate cellulose and from 20 wt. % to 80 wt. % short-fibre cellulose.
5. The method according to claim 1, wherein at least one sizing agent is added as an additive to the at least one suspension relative to the active substance of a sizing agent in a quantity of 0.07 wt. % to 1.0 wt. % relative to 100 wt. % of total dry mass of the at least one suspension.
6. The method according to claim 5, wherein at least one sizing agent selected from a group consisting of alkenyl succinic acid 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.
7. The method according to claim 1, wherein the at least one suspension is produced with a consistency of 0.15% to 0.70%.
8. The method according to claim 1, wherein during the further processing to form a cellulose-fibre-based drinking straw, one or a plurality of the paper webs are layered one above the other and joined.
9. The method according to claim 8, wherein a compressed first side of the at least one paper web is contacted with an uncompressed second side of a further paper web layered thereover.
10. The method according to claim 8, wherein the paper webs are glued together, wherein one adhesive is applied over the full surface or in sections to contacting sides of the paper webs.
11. The method according to claim 1 in the course of the further processing to form a cellulose-fibre-based drinking straw, the at least one paper web or a plurality of layered and joined paper webs are assembled to form paper strips, wherein in each case one paper strip is delimited by two longitudinal edges and two transverse edges, and wherein in the region of the two longitudinal edges an overlap region is formed in each case and that by bending the paper strip about a drinking straw axis, a cylindrical hollow body open on both ends is formed, wherein the paper strip is formed by overlapping the two overlap regions and the two overlap regions are glued together.
12. The method according to claim 11, wherein the paper strip is formed so that its two longitudinal edges run substantially parallel to the axis of the drinking straw.
13. The method according to claim 11, wherein the paper strip is formed so that the two longitudinal edges run substantially in a spiral or helical shape about the axis of the drinking straw axis.
14. The method according to claim 1, wherein before further processing to form the cellulose-fibre-based drinking straw the first side of the at least one paper web is printed with food-safe or biologically degradable inks.
15. A cellulose-fibre-based drinking straw produced according to method according to claim 1, comprising a cylindrical hollow body which is open on both ends having a lateral outer surface and a lateral inner surface, wherein the cylindrical hollow body is formed by at least one formed paper strip, wherein the at least one paper strip is assembled from at least one paper web having at least one compressed first side, wherein the compressed first side of the at least one paper web has a Cobb 1800s value according to ISO 535:2014 from 24 g/m.sup.2 to 62 g/m.sup.2.
16. The cellulose-fibre-based drinking straw according to claim 15, wherein a difference amount of a Cobb 1800s value according to ISO 535:2014 between the compressed first side and the non-compressed or less strongly compressed second side is a maximum of 3 g/m.sup.2.
17. The cellulose-fibre-based drinking straw according to claim 15, wherein the compressed first side of the at least one paper web has a Bendtsen roughness according to ISO 8791-2:2013 of 30 ml/min to 250 ml/min.
18. The cellulose-fibre-based drinking straw according to claim 15, wherein the at least one paper web has a gloss value according to TAPPI T 480:2015 of 20 to 35%.
19. The cellulose-fibre-based drinking straw according to claim 15, wherein the compressed first side of the at least one paper web has a static contact angle according to ISO 19403-2:2020 using water as test liquid of 100 to 120.
20. The cellulose-fibre-based drinking straw according to claim 15, wherein a different amount of a static contact angle according to ISO 19403-2:2020 using water as test liquid between the compressed first side and the non-compressed or less strongly compressed second side is a maximum of 6.
21. The cellulose-fibre-drinking drinking straw according to claim 15, wherein at least two paper webs are arranged so that the first side of a first paper web forms the lateral outer surface of the hollow body and that a first side of the second paper web forms the lateral inner surface of the hollow body.
Description
DESCRIPTION OF THE DRAWINGS
[0059] For a better understanding of the invention, this is explained in detail with reference to the following figures.
[0060] In the figures in each case in a highly simplified schematic view:
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DETAILED DESCRIPTION OF THE INVENTION
[0068] Firstly it should be noted that in the variously described embodiments the same parts are provided with the same reference numbers or the same component designations, wherein the disclosures contained in the entire description can be applied accordingly to the same parts with the same reference numbers or the same component designations. The positional information selected in the description such as top, bottom, laterally etc. are related to the figure described directly and depicted, and in the event of a change in position this positional information can be applied accordingly to the new position.
[0069] The method for producing cellulose-fibre-based drinking straws 1 begins, as is known per se, with the production of an aqueous suspension 3 comprising a cellulose material 2 with optional addition of additives 4.
[0070] The person skilled in the art is sufficiently aware of how the cellulose material 2 can be produced which is why the corresponding possible process steps are not described in detail or are not depicted in figures. For the sake of completeness one possible process sequence is only briefly outlined at this point. Advantageously a cellulose mixture consisting of long-fibre sulphate cellulose and short-fibre cellulose, preferably short-fibre sulphate cellulose having a length-weighted, average fibre length in accordance with ISO 16065-2:2014 of 1.05 mm to 2.50 mm can be provided as cellulose material 2. The cellulose mixture can be composed of 20 to 80 wt. % long-fibre sulphate cellulose and of 20 to 80 wt. % short-fibre cellulose, preferably short-fibre sulphate cellulose. For example, a cellulose mixture of comminuted hard wood as sulphate cellulose and of comminuted soft wood as sulphate cellulose can be used as starting material to produce the cellulose material 2. Naturally this can also comprise a mixture of various comminuted hard woods and soft woods. This cellulose mixture is prepared by a process comprising chemical treatment of the comminuted first and second cellulose in a pulp digester. Depending on the requirement, it can be expedient if, after the chemical treatment, a mechanical treatment and defibration of an aqueous solid suspension of the cellulose mixture is carried out in a high-consistency defibrator. A consistency of the solid suspension before the mechanical treatment and defibration in the high-consistency defibrator can, for example be set to 25% to 40%. Such a defibration in a high-consistency defibrator is used, inter alia, to reduce the so-called splinter fraction of the cellulose mixture, i.e. the dissolution of still-wood-like cellulose agglomerates. In addition, it can also be expedient if, after the first mechanical processing and defibration in the high-consistency defibrator, a mechanical treatment and grinding of the cellulose mixture or an aqueous cellulose suspension of the cellulose mixture is carried out in a low-consistency refiner. A consistency of the solid suspension before the mechanical treatment and grinding in the low-consistency refiner can expediently be set to 2% to 6%. It can certainly be provided that only a mechanical treatment of the cellulose mixture is carried out in a high-consistency defibrator. In precisely the same way, in other cases however it can also be expedient if a defibration in a high-consistency defibrator is omitted and only a mechanical treatment of the cellulose mixture in a low-consistency refiner is carried out. The specific grinding powers of the individual grinding stages should be adapted to the selected cellulose mixture of the desired paper parameters.
[0071] The description of
[0072] Regardless of how preparation of the cellulose mixture to form a cellulose material 2 is carried out, production of at least one aqueous suspension 3 comprising the cellulose material 2 is carried out for further processing of the cellulose material 2. This process step is illustrated, for example, in
[0073] Regardless of this, before the homogenization and pre-drying to form at least one water-containing non-woven web 5 having a first side 6 and a second side 7, a consistency of the at least one aqueous suspension 3 can be set to a value of 0.15% to 0.8%, preferably of 0.3% to 0.7%. The further processing of this at least one aqueous suspension 3 can then be accomplished, as is known per se, by means of a paper machine 29, as is described roughly schematically hereinafter with reference to
[0074] As shown in
[0075] Hereinafter, as shown in
[0076] A so-called slalom drier 37 can be arranged after the press section 31 according to
[0077] For compression according to the invention with a line load of preferably 210 kN/m to 370 kN/m, a so-called broad-nip calender 9 or also shoe calender having a shoe length of, for example, 50 mm and a shoe tilt of 24% can be provided in the drier section 32 following a slalom drier 37 for further drying and compression of the non-woven web 5. For compression according to the invention with a line load of preferably 380 kN/m to 490 kN/m, for example, a shoe length of 75 mm and a shoe tilt of 24% can be provided in a shoe calender.
[0078] A broad-nip calender 9 can be formed substantially by a heated roller 10 and by a shoe roller 12 cooperating with the heated roller 10. The shoe roller 12 can act as a flexible counter-pressure element to the heated roller 10 and have a circulating jacket 38. This circulating jacket 38 cooperates with the heated roller 10 and forms a broad nip 11. The first side 6 of the at least one non-woven web 5 facing the heated roller 10 is finished by passing between heated roller 10 and shoe roller 12. This means that the non-woven web 5 is at the same time compressed with elevated pressure and exposed to an elevated temperature. Temperatures at the surface of the heated roller can, for example, be about 250 C. to 295 C. The temperature can be achieved, for example, by means of a thermal oil having a correspondingly higher oil flow temperature. Other heating elements such as, for example, an induction heater can be provided for further stabilization of the surface temperatures. Fundamentally it is also feasible but not shown in the figures that a second, advantageously identically constructed broad nip calender 9 is provided, which is arranged in the paper machine 29 in such a manner that a so-called satin finishing of the second side 7 in addition to the satin finishing of the first side 6 of the at least one non-woven web 5 can take place.
[0079] It is also feasible that a process-technical combination of press section 31 and drier section 32 is provided after the wire section 30 by means of which the compression according to the invention with a line pressure of about 80 kN/m can take place in a first shoe press, in a second smoothing press at about 90 kN/m and in a third smoothing press at about 100 kN/m. The surface temperature of the smoothing cylinder can, for example, be about 94 C. This feasible design is shown roughly schematically by
[0080] The paper machines 29 shown as examples according to
[0081] 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%. In this case, both high-consistency and also low-consistency suspensions 3 can be used for arrangements based on
[0082] The person skilled in the art is familiar with a plurality of different methods for producing cellulose-fibre-based drinking straws 1 from at least one paper web 8 which is why the possible process steps are not discussed in detail.
[0083] Advantageously one but also more, preferably three or even four of the paper webs 8 produced according to the invention can be further processed to form a cellulose-fibre-based drinking straw 1. In the course of the further processing, one or more paper webs 8 produced from the same cellulose material 2, i.e. a plurality of identical paper webs 8 can be layered one above the other. However, it is also feasible and has proved particularly advantageous if paper webs 8 produced from various cellulose materials 2 and therefore different with regard to their technical properties are layered one above the other and joined.
[0084] A single paper web 8 can, for example, also be further processed by a corresponding single or multiple folding. Thus, a single paper web 8 can, for example, be multiply folded so that it runs in a zigzag manner or in a meander shape so that a paper web 8 that is quasi-multi-layered or layered one above the other is formed. This feasible embodiment is shown by
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[0086] Alternatively but also not shown in the figures, it can also be advantageous if at least one layer of the paper produced according to the invention is fabricated in an arrangement of several paper webs 8. In particular, it can also be expedient if in particular one of the two exterior paper webs 8, i.e. one of the two directly in contact with a drinking liquid is produced according to the method according to the invention. However, it can also be advantageous that both the finished cellulose-fibre-based drinking straw 1 exterior paper webs 8 are produced according to the method according to the invention. In this case, it can be expedient if in each case, the compressed first side 6 is in direct contact with a liquid. By means of a targeted arrangement of the paper webs 8, various parameters or product properties such as, for example, optical properties such as gloss, printability, haptics and the like can be set accordingly in an advantageous manner.
[0087] The paper webs 8 can be glued together, wherein an adhesive 17 is applied over the full surface or in sections to the contacting sides 6, 7 of the paper webs 8.
[0088] A single paper web 8 but also in the sense of
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[0090] By bending a paper strip 18 about a drinking straw axis 22, a preferably cylindrical hollow body 23 open on both sides can be folded, wherein the at least one paper strip 18 can be formed in such a manner that an overlap portion 24 is formed by overlap of the two overlap regions 21. The cylindrical hollow body 23 can then 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. In this case, the at least one paper strip 18 can be formed in such a manner that its two longitudinal edges 19 can run substantially parallel to the drinking straw axis 22 as shown schematically by
[0091] At least two paper webs 8 can be arranged in such a manner that the first side 6 of the first paper web 8 forms the lateral outer surface 26 of the hollow body 23 and that the first side 6 of the second paper web 8 forms the lateral 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, i.e. between the first and the second paper web 8. These interior or interposed paper webs 8 can comprise both paper webs 8 according to the invention and also different types of further papers with possibly additional advantageous properties. It can also be the case that at least two paper webs 8 are arranged in such a manner that the uncompressed or less strongly compressed second side 7 of the first paper web 8 compared to the first side 6 forms the lateral outer surface 26 of the follow body 23 and that the uncompressed or less strongly compressed second side 7 of the second paper web 8 compared to the first side 6 forms the lateral inner surface 27 of the hollow body 23.
[0092] The compressed first side 6 of the at least one paper web 8 or the paper webs 8 can have a Cobb 1800s value in accordance with ISO 535:2014 of 24 to 62 g/m.sup.2. A difference amount of a Cobb 1800s value in accordance with ISO 535:2014 between the compressed first side 6 and the non-compressed or less strongly compressed second side 7 can advantageously be a maximum of 4 g/m.sup.2. In addition, the compressed first side 6 of the paper web(s) 8 can have a Bendtsen roughness in accordance with 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 in accordance with TAPPI 480 of 20 to 35%. Furthermore, the compressed first side 6 of the paper web(s) 8 can have a static contact angle in accordance with ISO 19403-2:2020 with water as test liquid of 100 to 120. A difference amount of a static contact angle in accordance with ISO 19403-2:2020 using water as test liquid between the compressed first side 6 and the non-compressed or less strongly compressed second side 7 can be a maximum of 6.
[0093] The exemplary embodiments show possible design variants wherein at this point it is noted that the invention is not restricted to specially depicted design variants of the same but on the contrary, diverse combinations of individual design variants amongst one another are possible and this scope for variation lies within the ability of the person skilled in the art active in this technical field as a result of the teaching on the technical action by the specific invention.
[0094] The scope of protection is determined by the claims. The description and the drawings should however be used to interpret the claims. Individual features or combinations of features from the depicted and described various exemplary embodiments can form independent inventive solutions by themselves. The object forming the basis of the independent inventive solutions can be deduced from the description.
[0095] All the information on ranges of values in the specific description should be understood such that these cover arbitrary and all partial ranges thereof, e.g. the information 1 to 10 should be understood such that all partial ranges starting from the lower limit 1 and the upper limit 10 are covered, i.e. all partial 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.
[0096] For the sake of good order it should finally be pointed out that for better understanding of the structure elements are shown in some cases not to scale and/or enlarged and/or reduced.
REFERENCE NUMBERS
[0097] 1 Cellulose fibre-based drinking straw
[0098] 2 Cellulose material
[0099] 3 Suspension
[0100] 4 Additive
[0101] Non-woven web
[0102] 6 First side
[0103] 7 Second side
[0104] 8 Paper web
[0105] 9 Broad-nip calender
[0106] 10 Heated roller
[0107] 11 Broad nip
[0108] 12 Shoe roller
[0109] 13 Press roller
[0110] 14 Surface
[0111] 15 Drying cylinder
[0112] 16 Drying hood
[0113] 17 Adhesive
[0114] 18 Paper strip
[0115] 19 Longitudinal edge
[0116] 20 Transverse edge
[0117] 21 Overlap region
[0118] 22 Drinking straw axis
[0119] 23 Hollow body
[0120] 24 Overlap section
[0121] 25 Length
[0122] 26 Lateral outer surface
[0123] 27 Lateral inner surface
[0124] 28 Tank
[0125] 29 Paper machine
[0126] 30 Wire section
[0127] 31 Press section
[0128] 32 Drier section
[0129] 33 Endless screen
[0130] 34 Dewatering agent
[0131] 35 Roller
[0132] 36 Support material
[0133] 37 Slalom drier
[0134] 38 Jacket
[0135] 39 Yankee cylinder
[0136] 40 Winder
[0137] 41 Length