EP4511231A1 - Procédé permettant de remouiller une bande en papier, et installation - Google Patents

Procédé permettant de remouiller une bande en papier, et installation

Info

Publication number
EP4511231A1
EP4511231A1 EP24709349.5A EP24709349A EP4511231A1 EP 4511231 A1 EP4511231 A1 EP 4511231A1 EP 24709349 A EP24709349 A EP 24709349A EP 4511231 A1 EP4511231 A1 EP 4511231A1
Authority
EP
European Patent Office
Prior art keywords
unit
web
moistening
units
drying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP24709349.5A
Other languages
German (de)
English (en)
Other versions
EP4511231B1 (fr
Inventor
Julian MESSER
Tim Slawik
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BHS Corrugated Maschinen und Anlagenbau GmbH
Original Assignee
BHS Corrugated Maschinen und Anlagenbau GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BHS Corrugated Maschinen und Anlagenbau GmbH filed Critical BHS Corrugated Maschinen und Anlagenbau GmbH
Publication of EP4511231A1 publication Critical patent/EP4511231A1/fr
Application granted granted Critical
Publication of EP4511231B1 publication Critical patent/EP4511231B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F23/00—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing
    • B41F23/02—Devices for treating the surfaces of sheets, webs, or other articles in connection with printing by dampening
    • 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
    • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/008—Steam showers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00—Calenders; Smoothing apparatus
    • D21G1/0073—Accessories for calenders
    • D21G1/0093—Web conditioning devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G7/00—Damping devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/12—Making corrugated paper or board

Definitions

  • the invention relates to a method for remoistening a paper web and a plant for processing a paper web.
  • Examples of systems for processing paper webs are printing machines for printing on such a web and corrugated cardboard systems for producing a web (more precisely corrugated cardboard web) which is composed of several individual layers of paper.
  • the web When processing a paper web, the web is regularly dried, e.g. after printing in a printing machine. During drying, a significant amount of moisture (i.e. water) is removed from the paper, which is then conveniently added back to the paper later as part of remoistening.
  • moisture i.e. water
  • the problem here is that the paper only has a limited ability to absorb water, which is applied to the web during remoistening. In some circumstances, the previously removed moisture cannot be fully returned. This then regularly leads to defects such as wrinkling, tin can effect, roping and the like. Such defects are in turn problematic when the web is wound up at the end of the system or when the web is transferred directly to a subsequent system in inline operation.
  • US 5,596,930 A describes a method for moistening a moving web of printed material.
  • a moistening agent can be applied to the web in several steps.
  • a correspondingly improved method and an improved system are to be specified.
  • a key idea of the present invention is in particular a multi-stage remoistening, in which the remoistening of a paper web is divided into several stages, in each of which a moistening agent is applied to the web.
  • the method according to the invention serves to remoisten a paper web and is in particular also an operating method for a system in which remoistening takes place.
  • a single-layer paper web is assumed, i.e. a paper web in the narrower sense, but the invention is also applicable to other and in particular multi-layer paper webs, e.g. a corrugated cardboard web or a precursor for such a web, which is then composed of several individual layers of paper.
  • the web is guided through a system.
  • the web is, for example, unrolled by an unwinder of the system, then processed and finally rolled up again by a rewinder of the system or alternatively directly to a subsequent system passed on.
  • the system is a printing machine, but the statements made here apply very generally to any system that processes a web of paper and carries out remoistening in connection with this.
  • a particularly advantageous embodiment is one in which the system is a corrugated cardboard system for the production of corrugated cardboard.
  • the system generally has a processing unit with which the web is processed.
  • the system also has a drying unit downstream of the processing unit for drying the web (i.e. the processed web).
  • the drying unit has one or more hot air dryers and/or infrared dryers for drying.
  • the type of processing and drying are not initially relevant; what is more important is that moisture is removed from the paper of the web during drying. As part of the process, this should be replenished as completely as possible by means of remoistening.
  • the system has several moistening units downstream of the drying unit, by means of which the web (i.e. the dried web) is remoistened in several stages with a moistening agent.
  • the moistening units are used to replenish moisture to the web after drying by applying a moistening agent to the web.
  • the web is remoistened with the moistening agent in several stages, with a first of the moistening units pre-moistening the web (also known as initial moistening or “pre-wetting”) and a second of the moistening units post-moistening the web (also known as secondary moistening or “secondary wetting”) after a minimum dwell time.
  • pre-moistening and post-moistening take place in particular on the same side of the web, and in an expedient embodiment even on both sides.
  • the humectant contains in particular water, preferably predominantly (ie > 95% or even > 99%) or is even exclusively water.
  • the water is suitably as soft and/or desalinated as possible.
  • the humectant is a mixture of water and a wetting additive, preferably with a proportion of at most 1% by volume. particularly preferably of at most 0.1 vol.%, which is usually sufficient for high-quality wetting additives to achieve a minimum of surface tension.
  • the wetting additive serves to reduce the surface tension of the water (e.g. from 72.7 mN/m (polar portion: 51 mN/m, disperse portion:
  • the humectant is also mixed with air or another inert gas (e.g. nitrogen).
  • a is upstream of B” and equivalently “B is downstream of A” mean that A is located ahead of B along the path, i.e. the path first passes through A and then through B.
  • upstream/downstream the term pairs “before/behind” and “before/after” are also used.
  • the web is treated (processed, dried, moistened, etc.). This means in particular that the web undergoes the appropriate treatment section by section, i.e. it is not first fully processed, then dried and only then moistened, but that the web is fed continuously (i.e. inline) through the entire system and each web section is treated at a specific point and then passed on directly.
  • the minimum residence time is now selected such that the web in the second moistening unit has an increased absorption rate for the moistening agent due to the pre-moistening (by the first moistening unit).
  • this is understood to mean an absorption rate in the range of 0.1 s to 1 s, in particular for an amount of 3 g/m 2 moistening agent (ie then 3 to
  • the liquid film forms a corresponding barrier and limits the maximum absorption capacity of the paper. This maximum absorption capacity is also limited by the conveyance of the web through the system and the available distance, because as soon as the web is to be further processed or wound up, there must be no excess moistening agent left on the web and it must be skimmed off if necessary.
  • the remoistening is divided into several stages, namely into at least two moistening units, which then form a first and a second stage of remoistening.
  • the premoistening is not carried out with the actual target amount of moistening agent, but with a reduced amount of moistening agent. Additional moistening agent is then only added during the post-moistening with the second moistening unit.
  • the moistening agent of the second moistening unit penetrates the paper much faster than without premoistening (i.e. the absorption rate is increased), so that in total and over the same distance more moistening agent can be introduced into the web than with just one-stage remoistening.
  • This advantage also applies analogously to remoistening with more than two stages.
  • the minimum dwell time is now used in particular to wait for the most favorable time for the re-moistening.
  • the moistening agent initially forms a liquid film on the web, which should be broken down as far as possible when the web reaches the second moistening unit.
  • the absorption rate for further applied moistening is moistening agent is practically zero and only increases when the liquid film has been absorbed by the web. Therefore, the minimum residence time is preferably selected such that the moistening agent applied with the first moistening unit is completely absorbed into the web when the web reaches the second moistening unit. In this state and at this point in time in particular, an increased absorption rate results.
  • the rate at which the humectant is absorbed into the paper is highly dependent on the initial moisture content (i.e. initial moisture content) of the paper.
  • Dried-out paper as it is after the drying unit, absorbs water more slowly than pre-moistened paper.
  • the reason for this is that the hydrophilicity is increased by the adsorbed water molecules on the capillary walls of the paper. This reduces the contact angle and thus increases the absorption rate.
  • This relationship is also summarized in the so-called Lucas-Washburn equation (or just Washburn equation). Accordingly, a lower contact angle results in a higher penetration depth per unit of time, and thus an increased absorption rate. Equivalent to an increased absorption rate are in particular an increased penetration depth, increased hydrophilicity, a reduced contact angle and a reduced surface tension.
  • a particularly problematic factor for the absorption rate of the web is the so-called keratinization of the paper.
  • the paper contains paper fibers which absorb moisture and release it again during drying.
  • the term keratinization is understood to mean any fiber change (ie actual change in the paper fibers) which occurs during drying and remoistening processes. Examples of such fiber changes are an irreversible pore closure (reduction of the specific surface) through the formation of hydrogen bonds of neighboring cell walls or the coalescence of microfibrils. Keratinization is particularly irreversible. Keratinization occurs when drying in the drying unit regularly occurs. Starting with keratinized paper, a renewed supply of moisture is particularly difficult, i.e. the absorption rate is particularly low.
  • the method presented here does not attempt to introduce as much moisture as possible within a given time and over a given distance using just a single humidification unit, but preferably initially to produce an increased absorption rate in a first stage by means of pre-humidification. Only when the absorption rate has been significantly increased, ideally when a suitable threshold value for the absorption rate is reached (e.g. from the range already mentioned above), is further moisture introduced into the paper in a second stage by means of post-humidification, but this time much more efficiently than with keratinized paper, so that overall more moisture is introduced into the paper over the same time and distance.
  • the multi-stage rehumidification and the higher moisture content of the paper that this makes possible advantageously even reduces or completely prevents keratinization of the paper in the system, especially when drying after rehumidification or drying between the two stages of rehumidification.
  • the multi-stage remoistening has a positive effect on the web shrinkage in the system, in particular by significantly reducing the effect of the web shrinkage due to drying through the subsequent remoistening.
  • the multi-stage remoistening makes it possible to achieve a difference in the moisture cross-section of less than 2%. in particular a maximum of 1.3% can be achieved, i.e. the difference in moisture at any two points along the width of the web is less than 2% or a maximum of 1.3%. From a difference of 2% onwards, what is known as warp usually occurs during further processing of the web in a corrugated cardboard plant, i.e. the corrugated cardboard web distorts.
  • multi-stage remoistening also enables high machine dynamics for the plant, particularly with regard to a change in web speed and a change of order, since shrinkage of the web is compensated for at a suitable point as required. This can be demonstrated in particular by means of suitable sensors for measuring the width of the web in the plant and is also noticeable at the end of further processing in a corrugated cardboard plant as a precisely cut blank.
  • the minimum dwell time is preferably in the range from 0.5 s to 30 s, particularly preferably in the range from 1 s to 30 s, although the upper limit of 30 s is basically unnecessary, ie the minimum dwell time is preferably at least 0.5 s or at least 1 s. Investigations have shown that such a minimum dwell time is sufficient to achieve the described effect.
  • the minimum dwell time is equivalent to a minimum distance that the web travels between the first and second moistening units.
  • the conversion between minimum dwell time and minimum distance is carried out using the web speed, ie the speed at which the web is conveyed through the system.
  • the web speed may vary depending on the order.
  • a nominal minimum distance in the range of 1 m to 225 m results; in any case, a minimum distance of at least 2 m is advantageous.
  • the maximum minimum distance is in particular significantly less than 225 m, since the web run (i.e. the distance that the web travels) through the entire system is typically significantly less than 200 m.
  • the minimum residence time between the first and second moistening stage is selected for a maximum web speed (e.g. 450 m/min) of the system.
  • a maximum web speed e.g. 450 m/min
  • the main relevant factor is that the web is still moist when it reaches the second moistening unit and is certainly not completely dry, so that an increased absorption rate results for the remoistening.
  • the amount of moistening agent applied is expediently set depending on the web speed in such a way that, with varying web speeds, the same amount of moistening agent is always applied per unit of time and per unit of area.
  • the amount of moisture that the paper can absorb typically depends on the grammage (e.g. in the range of 100 g/m 2 to 300 g/m 2 or even more) of the paper and generally also on the type of paper. The higher the grammage, i.e. the heavier the paper, the more moisture the paper can absorb. In addition, paper with a higher grammage (in particular > 300 g/m 2 ) is typically dried out less (when considering the moisture in %), so that a strong re-moistening corresponding to the high grammage is generally not necessary, nevertheless larger amounts (in particular > 3 g/m 2 ) than with lower grammages are possible without any problems (i.e. in particular without creasing).
  • grammage e.g. in the range of 100 g/m 2 to 300 g/m 2 or even more
  • an amount of moistening agent which is applied to the web per unit of time by means of the moistening units is therefore set depending on the grammage of the paper, with the amount also being increased for a higher grammage.
  • the relationship is not necessarily linear and in particular not necessarily continued up to very high grammages.
  • the quantity is set depending on the paper type. This is based on the consideration that even a Binders in the paper and, if necessary, other additives as well as the porosity and initial moisture content of the paper, i.e. generally the type of paper, influence the absorption rate, i.e. the ability of the paper to absorb moisture.
  • a maximum of 3 g/m 2 of humectant is applied with each humidification unit.
  • This amount is optimal in particular for a typical dimensioning of the system and the ranges mentioned above for the minimum residence time, and is also suitable for typical paper types and grammages.
  • a quantity of 1 g/m 2 to 3 g/m 2 of humectant is preferably applied with a single humidification unit, whereby - as already described - a higher quantity is also used for a higher grammage.
  • a total of up to 6 g/m 2 of humectant can thus be applied, which is also completely absorbed by the paper due to the multi-stage re-humidification, so that a correspondingly high moisture content is achieved.
  • very high grammages in particular > 300 g/m 2
  • a quantity of up to 4, 5 or 6 g/m 2 or even more is expediently applied with a single humidification unit. The total quantity of humectant then increases accordingly.
  • At least 5 g/m 2 of moistening agent are applied together with the moistening units or the web is remoistened to at least 4% (i.e. here and elsewhere % by weight) residual moisture.
  • the moistening units are used to remoisten a web of coated paper to at least 4% to 5% residual moisture and/or a web of uncoated paper is remoistened to at least 5% to 7% residual moisture.
  • a target amount of moistening agent is suitably specified, which is then distributed to the moistening units so that they apply the target amount to the web in several stages.
  • the residual moisture indicates the amount of moisture in the web relative to the weight of the web. Depending on the grammage, a quantity of 5 g/m 2 to 8 g/m 2 is preferred, although - as already described - a higher amount is used for a higher grammage. Alternatively or additionally, a residual moisture content in the range of 5% to 6% is preferred, particularly regardless of the grammage.
  • the drying unit regularly dries the web to a residual moisture content in the range of 2.5% to 3.5% (uncoated paper), and accordingly 1.5% to 3.5% residual moisture is then added during remoistening, which is typically not possible with just one-stage remoistening.
  • Coated paper regularly stores less water than uncoated paper based on the layer thickness of the paper and is then typically dried to 1% to 1.5% (with an initial moisture content of 5%), so that 2.5% to 4% residual moisture is then added during remoistening to achieve a moisture content of 4% to 5%.
  • the humidification units are each designed as spray bars. These are characterized in particular by a particularly small installation space requirement and high cost-effectiveness.
  • spray bars are advantageously not operated in circulation mode, so that only fresh humidification agent is ever applied to the web.
  • other designs are also conceivable, e.g. dampening units with rollers or spray plates, although the latter in particular are less economical than spray bars and also require significantly more installation space.
  • the installation space requirement in particular is an important aspect in multi-stage rehumidification as described here, because this requires that a humidification unit is housed in at least two different places within the system.
  • spray bars are particularly compact and can easily be retrofitted at various points in existing systems without having to abandon the previous system design.
  • the use of spray bars also has the advantage that they typically have several spray nozzles arranged along a width of the web, so that an inhomogeneous moisture profile can be easily compensated, ie homogenized, by selectively controlling individual spray nozzles, e.g. switching them on and off or adjusting the amount of moistening agent discharged.
  • the humidification units are arranged downstream of a cooling unit of the system, which is arranged downstream of the drying unit.
  • the cooling unit serves to cool the web again after the drying unit.
  • the humidification units are not integrated into this cooling unit, but are arranged separately and at a different location, in particular further downstream of the cooling unit.
  • the system has several system sections, each with a processing unit for processing the web and a subsequent drying unit for drying the web, and at least one of the moistening units is arranged downstream of each drying unit, so that the web is moistened at least once after each drying and in particular before the next drying or before the end of the system.
  • the moistening units are now distributed over the system and are not arranged contiguously.
  • Humidification between two drying processes also advantageously prevents the described keratinization of the paper, so that even if the distance between two humidification units and possibly a drying unit in between is longer than the minimum distance, there is an increased absorption speed at the humidification unit further downstream, produced by the humidification unit further upstream.
  • the system is a printing machine, in particular a digital printing machine.
  • the processing unit is suitably a printing unit for printing the web with an ink, preferably a water-based ink and/or inkjet ink.
  • the printing unit typically has several printing bars, in particular for different colors (e.g. CMYK).
  • the drying unit is then a printing drying unit for drying the ink.
  • the multi-stage remoistening described here is particularly suitable for use in a printing machine, as the web is regularly heavily dried in order to dry the print created when printing with the ink. As a side effect of this, moisture is also removed from the paper, which is then added back in with the remoistening.
  • the system has a primer application unit and a primer drying unit upstream of the printing unit and a varnish application unit and a varnish drying unit downstream of the printing unit.
  • the primer application unit processes the web in such a way that a primer is applied, which in particular serves as a basis for the subsequent printing.
  • the primer drying unit dries the applied primer.
  • the varnish application unit processes the web in such a way that a varnish is applied, which in particular serves as a finish for the previous printing.
  • the varnish drying unit dries the applied varnish.
  • the varnish application unit is either analogue, i.e. the varnish is applied or sprayed on using a roller or a bath, for example, or digital, i.e. the varnish is printed on with one or more printing bars, as with a digital printing unit.
  • the primer application unit and the paint application unit are further processing units of the system.
  • Two of the humidification units are now conveniently arranged between the primer drying unit and the printing unit, or alternatively only one of the humidification units.
  • another of the humidification units is suitably arranged between the printing drying unit and the paint application unit, or alternatively even two of the humidification units are arranged.
  • two more of the humidification units are preferably arranged downstream of the paint drying unit, or alternatively only one of the humidification units.
  • the system has five humidification units, of which two of the humidification units are arranged between the primer drying unit and the printing unit, and another between the printing drying unit and the paint application unit. of the humidification units and downstream of the varnish drying unit two more of the humidification units.
  • first and second humidification units are basically arbitrary and is expediently set depending on the concrete operating mode and especially depending on the paper type and grammage. It is fundamentally advantageous if the two humidification units between the primer drying unit and the printing unit are a first and second humidification unit for pre-humidification and post-humidification as described and/or if the two humidification units downstream of the varnish drying unit are a first and second humidification unit for pre-humidification and post-humidification as described.
  • An advantageous multi-stage re-humidification is then implemented at the corresponding point, in particular a two-stage humidification section, even before the web is processed in the subsequent processing unit or even before the web is wound up at the end of the system or transferred to a subsequent system.
  • the web is not wound up at the end of the system, but is transferred to a subsequent system via a transfer line, e.g. a corrugated cardboard system, it is advisable to arrange a further, in particular sixth, moistening unit along the transfer line.
  • a transfer line e.g. a corrugated cardboard system
  • a respective moistening unit is not necessarily tied to the operation of the processing unit upstream of it, but moistening takes place in a suitable configuration regardless of whether processing has taken place beforehand or not.
  • This is particularly advantageous if the drying unit upstream of the moistening unit is active or continues to have an effect when an order is changed, even though the associated processing unit is inactive, because then the web continues to be dried and remoistening remains advantageous.
  • the primer application unit is not required and activated for every order, so that it may be inactive at certain times. In these cases, however, the primer drying unit is still active and dries the web, which is then conveniently remoistened with one or more subsequent moistening units before or while the web enters the printing unit.
  • the system has an analogue varnish application unit downstream of the printing unit and an additional digital varnish application unit downstream of the analogue varnish application unit.
  • the system has a primer application unit and a primer drying unit upstream of the printing unit, as already described above.
  • the system also has an associated varnish drying unit downstream of the respective varnish application unit, by means of which the varnish applied in each case is dried.
  • one of the humidification units is arranged between the printing unit and the analogue varnish application unit (and downstream of the printing drying unit).
  • Another of the humidification units is arranged between the analogue varnish application unit and the digital varnish application unit (and downstream of the varnish drying unit to the analogue varnish application unit).
  • Another of the humidification units is arranged downstream of the digital varnish application unit (more precisely, even downstream of the varnish drying unit to the digital varnish application unit).
  • the system therefore has a total of three humidification units. Which of these humidification units are then the above-mentioned first and second humidification units is basically arbitrary and is conveniently set depending on the specific operating mode and especially depending on the paper type and grammage. Using all three humidification units together is also advantageous. Alternatively, one of the three aforementioned humidification units can be omitted, so that the system then only has two humidification units, which is already advantageous in itself.
  • the system according to the invention is used to process a paper web.
  • the system has a processing unit for processing the web and a drying unit, which is arranged downstream of the processing unit, for drying the web.
  • the system also has several moistening units, which are arranged downstream of the drying unit and are designed to remoisten the web with a moistening agent in several stages, in that a first of the moistening units premoistens the web and a second of the moistening units remoistens the web after a minimum dwell time.
  • the minimum dwell time is selected such that the web in the second moistening unit has an increased absorption rate for the moistening agent due to the premoistening.
  • Fig. 1 a system
  • Fig. 3 a variant of the system from Fig. 1 ,
  • Fig. 4 shows a further variant of the system from Fig. 1 .
  • a variant of a system 2 is shown for processing a web 4 of paper.
  • a digital printing machine is assumed as system 2, in which a single-layer web 4 of paper is printed.
  • the statements in this context also apply analogously to other systems 2, e.g. a corrugated cardboard system, and other webs 4, e.g. multi-layer webs 4 of paper.
  • the web 4 is guided through the system 2 and, for example, unrolled by an unwinder of the system 2 (not explicitly shown), then processed and finally rolled up again by a winder 6 of the system 2 or, alternatively, passed on directly to a subsequent system (not shown) via a transfer path 8.
  • the system 2 generally has a processing unit 10 with which the web 4 is processed.
  • the system 2 also has a drying unit 12 downstream of the processing unit 10 for drying the web 4.
  • the drying unit 12 has one or more hot air dryers 14 and/or infrared dryers 16 for drying.
  • moisture is fundamentally removed from the paper of the web 4, which should be replenished as completely as possible by means of remoistening.
  • the system 2 has several moistening units 18, 20 downstream of the drying unit 12, by means of which the web 4 is remoistened in several stages with a moistening agent.
  • the web 4 is remoistened in several stages with the moistening agent by pre-moistening with a first moistening unit 18 and post-moistening with a second moistening unit 20 after a minimum residence time T.
  • the humectant in this case contains predominantly water and is also a mixture of water and a wetting additive to reduce the surface tension of the water.
  • the humectant is also mixed with air or something similar.
  • the minimum dwell time T is selected such that the web 4 in the second moistening unit 20 has an increased absorption rate for the moistening agent due to the pre-moistening.
  • the remoistening is divided into several stages, namely into at least two moistening units 18, 20, which then form a first and a second stage of remoistening.
  • the premoistening is not carried out with the actual target amount of moistening agent, but with a reduced amount of moistening agent. Additional moistening agent is then only added during the postmoistening. Since the web 4 is premoistened here, the moistening agent of the second moistening unit 20 penetrates the paper significantly faster than without premoistening, so that in total and over the same distance more moistening agent is introduced into the web 4 than with just one-stage remoistening.
  • the minimum residence time T serves to wait for the most favorable time for re-moistening.
  • the minimum residence time T is selected such that the moistening agent applied by the first moistening unit 18 is completely absorbed into the web 4 (ie at times T2 and T3 in Fig. 2) when the web 4 reaches the second moistening unit 20. This results in an increased absorption rate in particular.
  • an increased absorption rate is initially achieved in a first stage by means of pre-moistening. Only when the absorption rate has increased significantly, ideally when a suitable threshold value for the absorption rate has been reached, is further moisture introduced into the paper in a second stage by means of post-moistening, so that overall more moisture is introduced into the paper in the same time and distance.
  • the minimum residence time T is, for example, in the range from 0.5 s to 30 s.
  • the minimum residence time T is equivalent to a minimum distance that the web 4 travels between the first and second moistening units 18, 20.
  • the conversion between the minimum residence time T and the minimum distance is carried out using the web speed, i.e. the speed at which the web 4 is conveyed through the system 2.
  • the amount of moisture that the paper can absorb is typically dependent on the grammage (eg in the range of 100 g/m 2 to 300 g/m 2 ) of the paper and generally also on the type of paper.
  • the quantity is set depending on the paper type.
  • a maximum of 3 g/m 2 of moistening agent is applied with each moistening unit 18, 20.
  • an amount of 1 g/m 2 to 3 g/m 2 or more of moistening agent is applied with a single moistening unit 18, 20.
  • at least 5 g/m 2 of moistening agent is applied with the moistening units 18, 20 together or the web 4 is remoistened to at least 4% to at least 7% (ie wt. %) residual moisture, in particular depending on whether the paper is coated or uncoated.
  • the humidification units 18, 20 are each designed as spray bars. In principle, other designs are also conceivable, e.g. humidification units with rollers or spray plates.
  • the web 4 is not dried or processed, but rather only conveyed. Accordingly, no further processing unit 10 or drying unit 12 is arranged between the first and second moistening units 18, 20.
  • the first and second moistening units 18, 20 are arranged at the end of a system section 24, but other positions are possible and also suitable.
  • the first and second moistening units 18, 20 and the minimum distance between them are also referred to together as a two-stage moistening section; the system 2 in Fig. 3 accordingly has two such two-stage moistening sections, whereas the system 2 in Fig. 4 has none.
  • the system 2 has a primer application unit 32 and a primer drying unit 34 upstream of the printing unit 28 and a varnish application unit 36 and a varnish drying unit 38 downstream of the printing unit 28.
  • the primer application unit 32 and the varnish application unit 36 are further processing units 10 of the system 2.
  • the primer application unit 32 is used to apply a primer which serves as the basis for the subsequent printing and which is dried with the primer drying unit 34.
  • the varnish application unit 36 is used to apply a varnish which serves as a finish for the previous printing and which is dried with the varnish drying unit 38.
  • the varnish application unit 36 in Fig. 3 is analog, i.e. the varnish is applied or sprayed on, for example, via a roller or a bath; alternatively, a digital varnish application unit 40 is also suitable, i.e. the varnish is printed on with one or more printing bars as with a digital printing unit.
  • the system 2 according to Fig. 3 has five humidification units 18, 20, with two of the humidification units 18, 20 being arranged between the primer drying unit 34 and the printing unit 28, another of the humidification units 18, 20 being arranged between the printing drying unit 30 and the paint application unit 36, and two further humidification units 18, 20 being arranged downstream of the paint drying unit 38.
  • Fig. 3 also shows an example of which of the humidification units 18, 20 are a first and second humidification unit 18, 20. However, this allocation can in principle be varied. In Fig.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Supply, Installation And Extraction Of Printed Sheets Or Plates (AREA)
  • Ink Jet (AREA)

Abstract

L'invention concerne un procédé permettant de remouiller une bande (4) en papier, la bande (4) étant guidée à travers une installation (2), l'installation (2) comprenant une unité de traitement (10), au moyen de laquelle la bande (4) est traitée, en aval de l'unité de traitement (10), l'installation (2) comprenant une unité de séchage (12) pour sécher la bande (4), en aval de l'unité de séchage (12), l'installation (2) comprenant une pluralité d'unités de mouillage (18, 20), au moyen desquelles la bande (4) est réhumidifiée en plusieurs étapes à l'aide d'un agent mouillant, par prémouillage de la bande (4) ayant lieu au moyen d'une première unité de mouillage des unités de mouillage (18), et le post-mouillage de la bande (4) ayant lieu après un temps de séjour minimal (T) au moyen d'une seconde unité de mouillage des unités de mouillage (20), le temps de séjour minimal (T) étant choisi de telle sorte que la bande (4) présente une vitesse d'absorption accrue pour l'agent mouillant dans la seconde unité de mouillage (20) en raison du prémouillage. L'invention concerne en outre une installation (2) pour traiter une bande (4) en papier.
EP24709349.5A 2023-03-06 2024-03-01 Procédé permettant de remouiller une bande en papier, et installation Active EP4511231B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023201978.7A DE102023201978A1 (de) 2023-03-06 2023-03-06 Verfahren zur Rückbefeuchtung einer Bahn aus Papier, und Anlage
PCT/EP2024/055449 WO2024184254A1 (fr) 2023-03-06 2024-03-01 Procédé permettant de remouiller une bande en papier, et installation

Publications (2)

Publication Number Publication Date
EP4511231A1 true EP4511231A1 (fr) 2025-02-26
EP4511231B1 EP4511231B1 (fr) 2026-01-21

Family

ID=90361688

Family Applications (1)

Application Number Title Priority Date Filing Date
EP24709349.5A Active EP4511231B1 (fr) 2023-03-06 2024-03-01 Procédé permettant de remouiller une bande en papier, et installation

Country Status (7)

Country Link
US (1) US20250163650A1 (fr)
EP (1) EP4511231B1 (fr)
JP (1) JP2025523294A (fr)
CN (1) CN119317540A (fr)
DE (1) DE102023201978A1 (fr)
ES (1) ES3062669T3 (fr)
WO (1) WO2024184254A1 (fr)

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55121055A (en) * 1979-03-09 1980-09-17 Yoshinori Sakamoto Panel and its preparation
DE4227136C3 (de) 1992-08-17 1998-08-13 Weitmann & Konrad Fa Verfahren und Vorrichtung zum Befeuchten einer bedruckten und anschließend thermisch getrockneten, bewegten Materialbahn, insbesondere Papierbahn
DE4405332A1 (de) * 1994-02-19 1995-08-31 Bse Printtechnologie Rückbefeuchtungssystem, insbesondere für Rollenoffsetmaschinen mit Heatsettrocknung
DE9414963U1 (de) * 1994-09-16 1994-11-03 J.M. Voith Gmbh, 89522 Heidenheim Trockenpartie
JPH0952351A (ja) * 1995-08-11 1997-02-25 Techno Roll Kk 印刷装置
JPH1158686A (ja) * 1997-08-26 1999-03-02 Toshiba Mach Co Ltd 印刷機のウェブ加湿装置
FI981594L (fi) * 1998-07-10 2000-01-11 Valmet Corp Menetelmä ja laitteisto rainan kostutuksessa
DE69915836T2 (de) * 1998-07-10 2005-04-21 Metso Paper Inc Verfahren und vorrichtung zur herstellung von oberflächenbehandeltem druckpapier
DE19920091A1 (de) * 1999-05-03 2000-11-16 Baldwin Grafotec Gmbh Verfahren und Vorrichtung zur Konditionierung einer Papierbahn
DE10139219B4 (de) * 2001-08-09 2004-10-07 Koenig & Bauer Ag Wiederbefeuchtungsanlage für eine Materialbahn und Verfahren zum Verbessern der Laufeigenschaften einer Materialbahn
JP5497270B2 (ja) * 2007-03-28 2014-05-21 株式会社小森コーポレーション 液体転移装置
DE102008043767A1 (de) * 2008-11-14 2010-06-02 Koenig & Bauer Aktiengesellschaft Druckmaschine und Verfahren zur Handhabung einer durch die Druckmaschine geführten Bahn
DE102017104658B4 (de) * 2017-03-06 2022-06-23 Leonhard Kurz Stiftung & Co. Kg Verfahren zur Herstellung eines Decals und ein Decal sowie ein Verfahren zum Dekorieren von Oberflächen von Gegenständen

Also Published As

Publication number Publication date
CN119317540A (zh) 2025-01-14
ES3062669T3 (en) 2026-04-13
JP2025523294A (ja) 2025-07-18
EP4511231B1 (fr) 2026-01-21
WO2024184254A1 (fr) 2024-09-12
US20250163650A1 (en) 2025-05-22
DE102023201978A1 (de) 2024-09-12

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