Treatment section and treatment method for processing a fibrous web

Abstract

The present invention relates to a treatment unit and a treatment method for processing fiber webs, the treatment unit comprising at least two treatment substance application devices (10, 40, 50). The first treatment substance application device (10) is a double-sided curtain application device (10) for applying a treatment substance to one or both sides of the fiber web, followed by a drying section (20) for drying one or both sides of the fiber web respectively, the drying section (20) comprising at least partially non-contact drying by a hot air dryer (21), and the second treatment substance application device (40) is a double-sided film application device (40) for applying a treatment substance to one or both sides of the fiber web, followed by a drying section (20) for drying one or both sides of the fiber web respectively, the drying section (20) comprising at least partially non-contact drying by a hot air dryer (21).

Description

Technical Field

[0001] This invention generally relates to the production of fiber webs, and more particularly to the production of treated fiber webs. More specifically, this invention relates to a dryer and a treatment unit. Background Technology

[0002] As is known from existing technology, in fiber web machines, particularly in paper and paperboard machines, fiber webs are produced and processed in an assembly formed by multiple devices arranged sequentially in a production line. A typical production line includes: a forming section, which includes a headbox and forming units; a press section; and subsequently a drying section and a winding machine. The production line may also include other devices and sections for processing and / or finishing the fiber webs, such as a sizing section, a calender, and a coating section. The production and processing line connected thereto typically also includes at least one rewinder for forming customer rolls and roll sealing equipment.

[0003] In this specification and the following claims, fiber webs specifically refer to paper webs and paperboard webs. Fiber webs (especially paper and paperboard) come in various types and can be classified into two grades based on their basis weight: single-layer paper with a basis weight of 25-300 g / m²; and technically manufactured paperboard with a basis weight of 150-600 g / m². It should be noted that the distinction between paper and paperboard is flexible, as the lightest paperboard grade is lighter than the heaviest paper grade.

[0004] The following descriptions are examples of values ​​currently applied to fiber webs and may vary considerably from published values. These descriptions are primarily based on Papermaking Science and Technology, section Papermaking Part 3, edited by Rautiainen, P., and published by the PaperEngineers' Association, Helsinki 2009, 404 pages.

[0005] Mechanical pulp-based (i.e., wood-based) printing paper includes newsprint, uncoated magazine paper, and coated magazine paper.

[0006] Current newsprint pulp primarily consists of 80% to 100% deinked pulp (DlP). The remainder is mechanical pulp (typically TMP). However, newsprint can also be made from 100% mechanical fiber pulp. DlP-based newsprint can contain up to 20% filler. Virgin fiber-based newsprint pulp contains approximately 8% filler.

[0007] Typical values ​​for CSWO newsprint are: basis weight 40-48.8 g / m³ 2 PPS S10 roughness (SCAN-P 76-95) 4.0-4.5 µm; Bendtsen roughness (SCAN-P21:67) 150 ml / min; density 600-750 kg / m³ 3 Brightness (ISO 2470:1999) 58-59%; and opacity (ISO 2470:1998) 92-95%.

[0008] Uncoated magazine paper (SC - supercalendered paper) grades typically contain 50%-75% mechanical pulp, 5%-25% chemical pulp, and 10%-35% filler. This paper may also contain DLP. Typical values ​​for calendered SC paper (e.g., containing SC-C, SC-B, and SC-A / A+) include a basis weight of 40-60 g / m². 2 Ash content (SCAN-P 5:63) 0-35%; Hunter gloss (ISO / DIS 8254 / 1) <20-50%; PPS s10 roughness (SCAN-P 76:95) 1.0-2.5 µm; Density 700-1250 kg / m³ 3 Brightness (ISO 2470:1999) 62-75%; and opacity (ISO 2470:1998) 90-95%.

[0009] Coated machine-made paper includes grades such as MFC (Machine Finish Coated), LWC (Lightweight Coated), MWC (Medium Weight Coated), and HWC (Heavy Weight Coated). Coated machine-made paper typically contains 45%-75% machine-made or recycled fibers and 25%-55% chemical pulp. Semi-chemical pulp is a typical LWC grade produced in the Far East. Filler content is approximately 5%-10%. Basis weight is typically 40-80 g / m². 2 Within the range.

[0010] Typical values ​​for LWC paper are: basis weight 40-70 g / m² 2 Hunter gloss 50-65%; PPS s10 roughness 1.0-1.5 µm (offset printing paper) and 0.6-1.0 µm (rotary printing paper); density 1100-1250 kg / m³ 3 Brightness: 70-75%; Opacity: 89-94%.

[0011] Typical values ​​for MFC paper (machine finishing coated) can be: basis weight 48-70 g / m² 2 Hunter gloss 25-40%; PPSs10 roughness 2.2-2.8 µm, density 900-950 kg / m³ 3 Brightness 70-75%, opacity 91-95%.

[0012] Typical values ​​for MWC paper (medium weight coated paper) can be: basis weight 70-90 g / m². 2 Hunter gloss 65-70%; PPS s10 roughness 0.6-1.0 µm; density 1150-1250 kg / m³ 3 Brightness 70-75%; and opacity 89-94%.

[0013] Wood-free paper is divided into two categories (segments): uncoated and coated. Traditionally, the pulp of wood-free paper consists of bleached chemical pulp with less than 10% mechanical pulp.

[0014] Typical values ​​for uncoated WFU copy paper are: basis weight 70-80 g / m²; Bentessen roughness 150-250 ml / min; bulk > 1.3 cm. 3 / g. Typical values ​​for uncoated offset printing paper are: basis weight 60-240 g / m²; Bentsen roughness 100-200 ml / min; bulk 1.2-1.3 cm. 3 / g. Typical values ​​for color copy paper are: basis weight 100 g / m²; Bentsen roughness <50 ml / min; bulk 1.1 cm. 3 / g.

[0015] In coated pulp-based printing paper (WFC), the coating amount varies considerably depending on requirements and intended application. The following are typical values ​​for single-coated and double-coated pulp-based printing paper: Single-coated: basis weight 90 g / m², Hunter gloss 65-80%, PPS s10 roughness 0.75-1.1 µm, brightness 80-88%, opacity 91-94%; Double-coated: basis weight 130 g / m², Hunter gloss 70-80%, PPS s10 roughness 0.65-0.95 µm, brightness 83-90%, opacity 95-97%.

[0016] Containerboard includes linerboard and corrugated medium. Depending on the pulp used, the linerboard layer can be categorized as kraft paper linerboard, recycled linerboard, or white-backed linerboard. The linerboard layer typically consists of 1-3 layers with a basis weight of 100-300 g / m². 2 Variations within the range.

[0017] Paperboard is usually uncoated, but the production of coated white-backed paperboard is increasing to meet higher requirements for printability.

[0018] The main cartonboard grades include Folded Board (FBB), White Pulp Lined Corrugated Board (WLC), SBS (Saturated Bleached Sulfate Board), and Liquid Packaging Board (LPB). These grades are typically used for various types of consumer product packaging. Cartonboard grades range from one to five layers (150-400 g / m²). The top and side coatings are usually one to three layers (20-40 g / m²). 2 (); less or no coating on the back side. A wide range of quality data exist within the same paperboard grade. FBB has the highest bulk thanks to the mechanical or chemimechanical pulp used in the intermediate layer of the substrate. WLC's intermediate layer consists primarily of recycled fibers, while SBS is made solely of chemical pulp.

[0019] The bulk of FBB is typically between 1.1 and 1.9 cm. 3 Between / g, the bulk of WLC is typically 1.1-1.6 cm. 3 Between 0.95 and 1.3 cm / g, the bulk of SBS is typically between 0.95 and 1.3 cm. 3 The smoothness of PPS-s10 is as follows: FBB: 0.8-2.1 µm; WLC: 1.3-4.5 µm; SBS: 0.7-2.1 µm.

[0020] Release paper is used as a backing paper for labels in a variety of end-use applications, such as food packaging and office labels. The most common release paper in Europe is supercalendered glassine paper coated with silicone resin to provide good peel performance.

[0021] Typical values ​​for supercalendered release paper are: basis weight 60-95 g / m², thickness (caliper) 55-79 µm, IGT 12-15 cm, dense side Cobb Unger absorbency 0.9-1.6 g / m², and open side Cobb Unger absorbency 1.2-2.5 g / m².

[0022] Coated label paper is used as the surface paper for release linerboards, as well as for coated backing paper and flexible packaging. Coated label paper typically has a basis weight of 60-120 g / m², is usually sizing or pre-coated with a sizing agent, and is coated on one side using a single doctor blade. Some typical paper properties of coated and calendered label paper are: basis weight 50-100 g / m²; Hunter gloss 70-85%; PPS s10 roughness 0.6-1.0 µm; Buick smoothness 1500-2000 s; and thickness 45-90 µm.

[0023] As treated fiber web grades (such as sizing and / or coating fiber webs) become increasingly popular, the requirements for treatment methods and equipment used to treat fiber webs are also increasing.

[0024] In the production of fiber webs (e.g., in the production of paper webs or paperboard webs), sizing is used to modify the properties of the fiber webs by adding sizing agents (e.g., starch). Sizing can be divided into internal sizing and surface sizing. In internal sizing, the sizing agent is added to the pulp in the wet section of the fiber web machine before forming. In surface sizing, the sizing agent is typically added to the surface of the fiber web in the sizing section of the dry section of the fiber web machine. Surface sizing is used in the production of many fiber web grades to improve paper web properties (particularly water resistance, water absorption, strength, internal strength, surface strength, and flexural stiffness), as well as to improve the adhesion of coating pigments / coloring pigments to the surface of the fiber web. Furthermore, running performance and dust removal trends can be favorablely affected. In surface sizing, the sizing agent is typically added to the surface of the fiber web by a sizing machine in the dry section of the fiber web production line, usually by passing the fiber web through a sizing pressure zone formed between two sizing rolls, and is typically subsequently dried in a dryer in the sizing section.

[0025] When coating the surface of a fiber web, a layer of coating pigment is applied at a coating station and then dried, thereby providing the fiber web with a coating that has the desired properties. The formation of the coating pigment can be divided into: supplying the coating pigment to the surface of the web, which is called the application of the coating pigment; and adjusting the final amount of coating pigment. In the production of fiber webs (e.g., in the production of fiber webs or paperboard webs), during coating (especially in color coating), a layer of coating pigment is formed on the surface of the fiber web at a coating station (coating machine), which is usually subsequently dried by a dryer. Coating of paper webs and paperboard webs typically utilizes coating equipment—coating machines.

[0026] Regarding the treatment of fiber webs (regarding sizing and coating), different types of treatment techniques are used, such as pooling, film transfer, spraying, doctor blade, or curtain coating.

[0027] Hot air dryers (such as air cushion web dryers and / or impact dryers) are typically connected to the fiber web processing unit for non-contact drying of fiber webs. Hot air dryers operate based on convection (i.e., heat transfer through a medium). In a hot air dryer, hot air is blown onto the surface of the fiber web through nozzles to dry it. Hot air dryers are a very energy-efficient method for drying moving fiber webs.

[0028] As is well known, in relation to processing apparatuses (such as sizing machines and coating machines), sizing / coating rollers are used to press the processing material into the web within a pressure zone formed between these rollers, and the fiber web is guided through this pressure zone. In curtain-based processing apparatuses (i.e., sizing machines and coating machines), it has proven advantageous to use so-called hard rollers to form the processing pressure zone. By using hard rollers to form the processing pressure zone, the pressure in the pressure zone is increased, thereby enhancing the processing. Typically, rollers made of hard materials or rollers with hard coatings or overlays are used as hard rollers, such as ceramic rollers or metal rollers, or advantageously, rollers with hard polymer roller overlays (rubber, polyurethane, or composite materials) having a surface hardness of 60-100 Shore hardness D are used as hard rollers. In film transfer-based processing apparatuses, rollers are typically soft rollers.

[0029] Depending on the type of production line, calendering can be pre-calendering or final calendering. Pre-calendering is typically used to produce the surface properties required for further processing (such as coating), while final calendering is typically used to improve the properties (such as smoothness and gloss) of web-like materials (such as paper webs or paperboard webs). During calendering, the web enters a pressing zone (i.e., the calendering zone), which is formed between rollers pressing against each other, in which the web is deformed due to the effects of temperature, humidity, and pressing zone pressure. In a calender, the pressing zone is formed between press rollers with smooth surfaces (such as metal rollers) and rollers coated with elastic materials (such as polymer rollers), or between two rollers with smooth surfaces. The rollers with elastic surfaces self-adjust to the shape of the web surface and press the opposite sides of the web evenly against the press rollers with smooth surfaces. As known in the art, belts or boots can also be used instead of one of the rollers to form the pressing zone. Many different types of calenders are known to be used as pre-calenders and / or final calenders, such as hard calenders, soft calenders, supercalenders, metal strip calenders, boot calenders, long calenders, multi-zone calenders, etc.

[0030] As described above, fiber web production processes produce different types and grades of fiber webs. Typically, a single fiber web production and processing line is used for only one grade, or for a very limited number of grades, because different grades of fiber webs require different finishing processes. In some cases, the variety of grades is limited because different processes cannot be performed using a single type of equipment with a particular technology (especially in sizing or coating). Therefore, several different processing units (especially for sizing and / or coating) need to be connected to the fiber web production line. Generally, in the prior art, the focus is on production optimization, such as the width and operating speed of the fiber webs to be produced, which leads to a focus on a narrow range of different grades of fiber webs. Therefore, there is a need for a fiber web production line with a processing unit that provides the possibility of processing multiple fiber webs, making it possible to produce several different grades of fiber webs within the same fiber web production line. Summary of the Invention

[0031] The object of the present invention is to create a processing unit and processing method for processing fiber webs, wherein the disadvantages and problems of the prior art are eliminated or at least minimized, especially addressing the problem that the possibility of producing different grades of fiber webs in the same fiber web production line is limited without the need to use several different technologies of processing units and methods connected to the fiber web production line.

[0032] A specific and non-limiting object of the present invention is to create an improved processing unit and an improved processing method for fiber webs, wherein the flexibility for producing multiple fiber webs in the same fiber web production line is improved.

[0033] To achieve the above objectives, the main features of the processing unit and processing method according to the present invention are as follows.

[0034] According to the present invention, a processing unit for processing fiber webs includes at least two processing substance application devices, wherein the first processing substance application device is a double-sided curtain type application device for applying processing substance to one or both sides of the fiber web, followed by a drying section for drying one or both sides of the fiber web respectively, the drying section including at least partially non-contact drying by a hot air dryer, and the second processing substance application device is a double-sided film type application device for applying processing substance to one or both sides of the fiber web, followed by a drying section for drying one or both sides of the fiber web respectively, the drying section including at least partially non-contact drying by a hot air dryer.

[0035] According to an advantageous feature of the invention, a curtain-type application device can be used, comprising two processing rollers forming a processing pressure zone between the two processing rollers, and the two processing rollers being hard rollers, one or both of which are metal rollers with a hardness of at least 300 HV, or one or both of which are rollers having a composite coating with reinforcing material and a hardness of at least 80 Shore D, or one or both of which are ceramic rollers with a hardness of at least 300 HV, or one or both of which are rollers having a hard polymer roller coating (rubber or polyurethane) with a hardness of at least 80 Shore D, advantageously at least 90 Shore D.

[0036] According to an advantageous feature of the invention, the processing unit includes two processing substance application devices: a curtain-type application device as a first processing substance application device; and a membrane-type application device as a second and final processing substance application device.

[0037] According to an advantageous feature of the invention, the processing section further includes a scraper-type application device as a third processing substance application device for applying the processing substance to one side of the fiber web, followed by a drying section for drying one or both sides of the fiber web, the drying section including at least partially non-contact drying by a hot air dryer.

[0038] According to an advantageous feature of the invention, the processing unit includes three processing substance application devices: a curtain-type application device as a first processing substance application device; a membrane-type application device as a second processing substance application device; and a scraper-type application device as a third and final processing substance application device.

[0039] According to an advantageous feature of the invention, the processing unit includes at least one calender, which is either a pre-calender or a final calender.

[0040] According to an advantageous feature of the invention, the processing unit includes two calenders, one of which is a pre-calender and is located between at least two processing material application devices, and the other is a final calender located after the last processing material application device.

[0041] According to an advantageous feature of the invention, the processing apparatus is used as a sizing machine for applying sizing agents to fiber webs and / or as a coating machine for applying coating pigments to fiber webs.

[0042] According to the present invention, in this processing method, the fiber web is processed in a processing section comprising at least two processing material application devices. In this method: a) Apply a treatment substance to one or both sides of the fiber web using a double-sided curtain application device; then b) Drying one or both sides of the fiber web by at least partially non-contact drying in a hot air dryer; subsequently c) Apply the treatment substance to one or both sides of the fiber web using a double-sided film application device; then d) Drying one or both sides of the fiber web by at least partially non-contact drying in a hot air dryer.

[0043] An advantageous feature of the method according to the invention is that, after steps a)-d), a treatment substance is applied to one side of the fiber web by a scraper-type application device, and then the one or both sides of the fiber web are dried by at least partially non-contact drying in a hot air dryer.

[0044] According to an advantageous feature of the invention, in the processing method, the fiber web is calendered by at least one calender in the processing section, the at least one calender being a pre-calender or a final calender.

[0045] According to an advantageous feature of the invention, in the processing method, the fiber web is pre-calendered by a pre-calendering machine between at least two processing material application devices, and in the method, the fiber web is calendered by a final calendering machine after the application of processing material by the final processing material application device.

[0046] According to an advantageous feature of the invention, in this processing method, an sizing agent is applied to the fiber web and / or a coating pigment is applied to the fiber web.

[0047] According to an advantageous feature of the invention, the crimping of the fiber web is controlled by controlling the dry matter content (dryness) of the treatment material to be applied and / or by applying water to one side and / or by controlling the drying of the fiber web.

[0048] It has now been unexpectedly discovered that a processing unit is provided, comprising: a double-sided curtain application device as a first processing substance application device, followed by a drying section comprising at least partially non-contact drying by a hot air dryer; and a double-sided film application device as a second processing substance application device, followed by a drying section comprising at least partially non-contact drying by a hot air dryer. Various grades of fiber webs can be produced using the same fiber web production line connected to this processing unit according to the invention. The processing method in the processing unit includes the following processing substance application steps: single-sided or double-sided curtain application as a first processing substance application step, followed by a corresponding single-sided or double-sided drying step; and single-sided or double-sided film application as a second processing substance application step, followed by a corresponding single-sided or double-sided drying step. This provides a variety of options for the application of processing substances and for all types of processing substances, thereby enabling the production of many different grades of fiber webs. Furthermore, higher maximum possible production capacity and quality improvements for different fiber web grades can be achieved within a limited space.

[0049] In the processing unit according to the invention, the drying capacity of the drying section of the film application device can be used for the curtain application device, for example, when the film application device is not used for applying the treatment material on both sides. The processing unit according to the invention also provides the possibility of controlling the crimp of the fiber web by controlling the dry matter content of the treatment material to be applied or by applying water on one side. Creep can also be controlled by controlling the drying in the drying section of the treatment material application unit.

[0050] According to an advantageous aspect of the invention, the curtain-type application device is used for applying a sizing agent (e.g., starch) on one side or both sides, or for applying a sizing agent (e.g., starch) on one side and a coloring substance on the other side, or for coating pigments on both sides.

[0051] According to an advantageous aspect of the invention, a multi-layer curtain application is used as the curtain application device. This provides the possibility of applying a treatment substance (chemical), such as a barrier chemical, in a very small amount, such that the treatment substance remains only on the surface of the fiber web. Advantageously, multi-layer curtain application can be used to apply the treatment substance, thereby providing both a treatment effect (e.g., sizing) and ensuring that another substance (chemical) is applied only to the surface of the fiber web. This provides good penetration of the treatment substance (e.g., sizing agent), while the chemicals (e.g., highly hydrophobic and waterproof substances) remain only on the surface of the fiber web.

[0052] According to an advantageous aspect of the invention, in this process, the processing zone of the curtain-type application device is formed between two hard rollers. One of the rollers may be a deflection compensation roller. Advantageously, one or both rollers are metal rollers with a hardness of at least 300 HV, and / or one or both rollers are rollers with a composite coating layer with reinforcing material and a hardness of at least 80 Shore D, advantageously at least 90 Shore D. Advantageously, the composite coating layer is epoxy resin reinforced with glass fiber and / or carbon fiber and / or aramid fiber. One or both rollers may also be ceramic rollers with a hardness of at least 300 HV. Rollers with a hard polymer roller coating layer (rubber or polyurethane) having a hardness of at least 80 Shore D, advantageously at least 90 Shore D, can also be used as one or two rollers. The hard processing zone can be used for calendering. When it is desired to enhance the calendering effect, one roller of the processing zone is advantageously a multi-zone control roller, and the other roller is advantageously a heated roller. Typically, if the processing zone of the application device is used for calendering, no processing material is applied. For better calendering results, water or diluted starch can be applied. The hard-processing pressing zone also offers the possibility of omitting intermediate calendering.

[0053] According to an advantageous aspect of the invention, the film application device is used for applying pigments on one or both sides, or for applying a sizing agent (e.g., starch) on one side and a coloring substance on the other side, or for applying a sizing agent (e.g., starch) on one or both sides.

[0054] According to an advantageous aspect of the invention for applying a treatment substance, a curtain-type application device can be used to press the treatment substance into a fiber web, and a membrane-type application device can be used to apply the treatment substance such that the treatment substance remains on the surface of the fiber web.

[0055] According to an advantageous aspect of the invention, the processing unit further includes a doctor blade application device with a drying section as a third processing material application device, the drying section comprising at least partially non-contact drying. This allows for a further increase in the number of different fiber web grades that can be produced from the same fiber web production line. Doctor blade application improves the final smoothness, and if the doctor blade application device is used for coating, it provides the possibility of increasing coating weight and producing single-sided coated white paperboard fiber web grades (e.g., CWTL (Corrugated White Face Carton Board), SBS, FBB).

[0056] According to an advantageous aspect of the invention, in the treatment material application device, the treatment material can be the same or different, and the treatment material can be the same or different for each side of the fiber web. Therefore, even for the basic configuration of two treatment material application devices (curtain-type application device and film-type application device), the selection of treatment material is simultaneously four different treatment materials, and with the addition of a third treatment material device, a fifth possibility of treatment material is advantageously increased. Furthermore, it is possible to change the treatment material for further different possibilities and therefore for different fiber web grades. The treatment material can be any suitable treatment material, sizing agent, and / or coating pigment / coloring pigment. The treatment material can be a substance with low or high viscosity or a composition with low or high viscosity. The treatment material can be a sizing agent, such as starch, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVOH), polyvinyl acetate (PVA), or other synthetic or bio-based polymer latex. The treatment material can be a coloring sizing agent or coating pigment / coloring pigment, such as adhesive chemicals or a mixture of adhesive chemicals (e.g., starch) with mineral pigments and / or fillers. The treatment substance can be a cellulose-based material, such as microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC), nanocrystalline cellulose (NCC), cellulose nanowhiskers (CNW), or microcrystalline cellulose (MCC), or the treatment substance can be a cellulose-based composite material. The treatment substance can be a lignin-based chemical or a mixture thereof. The treatment substance can also be another biopolymer, such as chitosan, alginate, biopolyester, polyhydroxyalkanoate, or a mixture thereof.

[0057] It has now been unexpectedly discovered that further calendering of the processing section provides more possibilities for changing the grade of the fiber web to be produced. Calendering can be set as pre-calendering after the first processing material application device and its drying section, and / or as final calendering after the final processing material application device and its drying section. Pre-calendering can provide the profile of the fiber web thickness and control the thickness and smoothness of the fiber web. Final calendering can adjust the final smoothness of the fiber web. Many different types of calenders can be used as pre-calenders and / or final calenders, such as hard-zone calenders, soft-zone calenders, supercalenders, metal strip calenders, shoe calenders, long-zone calenders, multi-zone calenders, etc.

[0058] According to an advantageous aspect of the invention, a steam application device can be provided prior to the application device for treating the fiber web with steam before applying the treatment material to provide heat and moisture to the fiber web, which contributes to the improvement of the strength properties of the fiber web because the adhesion formation is improved, and if a hydrophobic sizing agent, such as AKD (alkyl ketene dimer) or SAE (styrene acrylate), is used as the treatment material, improved functionality and enhanced hydrophobicity are achieved.

[0059] This invention and its advantageous features achieve several benefits: it provides an optimal solution for various fiber web grades; the compact structure of the processing unit allows for a wider operating window in fiber web production; it achieves improved sustainability; it improves the smoothness and strength of the fiber webs to be produced; it eliminates the need for starch recycling; and it allows for controlled sizing agent penetration. Furthermore, the possibility of producing multiple different grades of fiber webs on the same fiber web production and processing line provides the ability to produce a wider variety of products, thus greatly enhancing responsiveness to market and demand changes. Attached Figure Description

[0060] The present invention will be described in detail below with reference to the accompanying drawings, but the invention is not limited to the drawings.

[0061] Figure 1 An advantageous example of the processing unit according to the invention is illustrated schematically. Figure 2 Another advantageous example of the processing unit according to the invention is illustrated schematically in the diagram. Figure 3 The diagram schematically illustrates an advantageous example of a steam application device connected to a material application device, and Figures 4A-4B The diagram schematically illustrates an advantageous example of an adjustment system for adjusting the nozzle opening of the application beam of a curtain-type application device. Detailed Implementation

[0062] In the following description, the same numbers and symbols will be used to identify the same elements according to different views illustrating the invention and its advantageous examples. For clarity, some repeated reference numerals have been omitted in the figures.

[0063] exist Figure 1 An example of a processing unit is schematically shown. The processing unit includes processing substance application devices 10 and 40, namely: a double-sided curtain application device 10 as the first processing substance application device 10, followed by a drying section 20, which includes at least partially non-contact drying by a hot air dryer 21; and a double-sided film application device 40 as the second processing substance application device 40, followed by a drying section 20, which includes at least partially non-contact drying by a hot air dryer 21. Therefore, the processing method in the processing unit includes a processing substance application step, namely: a single-sided or double-sided curtain application by the curtain application device 10 as the first processing substance application step, followed by a drying step, whereby at least partially non-contact drying of the single-sided or double-sided application is performed by the hot air dryer 21; and a film application by the film application device 40 as the second processing substance application step, followed by a drying step, whereby at least partially non-contact drying of the single-sided or double-sided application is performed by the hot air dryer 21. In the curtain-type application device 10, the processing material is applied as a curtain C from the curtain-type application beam 13 to the surface of the processing rollers 11, and then transferred to the surface of the fiber web in the processing pressure zone between the processing rollers 11. In this example of the processing section, the processing pressure zone between the processing rollers 11 of the curtain-type application device 10 is formed between two hard rollers 11. In the film-type application device 40, the processing material applied to the surface of the processing roller 41 is metered by the application rod 42 before the processing material enters the processing pressure zone (in which the processing material is transferred to the surface of the fiber web). The processing section also includes calendering, which is arranged as pre-calendering in the calendering pressure zone between two calendering rollers 31 of the pre-calender 30 after the first processing material application device 10 and its drying section, and / or final calendering in the calendering pressure zone between two calendering rollers 61 of the final calender 60 after the last processing material application device 40 and its drying section.

[0064] Figure 2 Examples corresponding to Figure 1 Examples, but in Figure 2In this example, the processing unit also includes a third processing material application device 50, namely, a doctor blade application device 50 having a drying section 20, which includes at least partially non-contact drying performed by a hot air dryer 21. The doctor blade application device 50 with the drying section 20 is located in the processing unit between the second application device 40 (i.e., the film application device 40) and the final calender. In the doctor blade application device, as the fiber web runs on the surface of the processing roller 51, the processing material is applied to the surface of the fiber web by the application member 53 and metered by a doctor blade 52 or scraper.

[0065] A comparative test was conducted on the surface roughness of the fiber web treated in the processing section by the processing method according to the present invention, and the test results are shown in Table 1 below.

[0066]

[0067] Table 1 shows the surface roughness measurement results after each processing device / processing step.

[0068] In the experiment, the Bentsen surface roughness (ISO 8791-2) and PPS-s10 surface smoothness (ISO 8791-4) were measured on both sides of the fiber web, and the average values ​​of the measurements on each side of the fiber web after each processing device / processing step are shown in Table 1.

[0069] In the experiments, both sides of the fiber web were treated, and experimental methods 1 and 2 corresponded to each other. However, in method 1, the first treatment material application device was a curtain-type application device through which both sides of the fiber web were surface-coated (i.e., according to the invention); in method 2, the first treatment material application device was a film-type application device through which both sides of the fiber web were surface-coated. Subsequently, in methods 1 and 2, the fiber web was calendered by a pre-calender and placed between two treatment material application devices (i.e., the first treatment material application device and the second treatment material application device (which is a film-type application device)), through which the fiber web was coated on both sides.

[0070] In Table 1, the measurement results in the "Base Paper" row represent the measurement results of the fiber web before treatment, the "Surface Sizing" row represents the measurement results after the first treatment material application step, the "Calming" row represents the measurement results after the calendering step, and correspondingly, the measurement results in the "Film Coating" row represent the measurement results after the second treatment material application step.

[0071] Regarding these measurement results, it should be particularly noted that when the first treatment substance is applied via a curtain application device (i.e., surface sizing by a curtain sizing machine), the surface roughness of the fiber web does not increase, and this advantage is maintained throughout the processing steps. However, this advantage is not achieved when the first treatment substance is applied via a film application device (i.e., surface sizing by a film sizing machine). Furthermore, it should be particularly noted that, with the processing unit / method (method 1) according to the invention, when the first treatment substance is applied via a curtain application device and the second treatment substance application device is a film application device, the smoothness of the fiber web is at a very good level. When producing high-quality fiber webs, the processing unit and method of the present invention also provide (after the second treatment substance application via film application) a significantly reduced need for further coating, such as blade coating, compared to the case where the first treatment substance application device is a film application device.

[0072] exist Figure 3 The diagram schematically illustrates an example of a steam application device 70 connected to a treatment material application device 40. The steam application device 70 is used to treat one or both sides of the fiber web using steam from a steam unit 71. Located before the application device 40, the steam application device 70 is used to treat the fiber web with steam before applying the treatment material, providing heat and moisture to the fiber web. In the treatment section, the steam application device 70 can be located before any of the treatment material application devices 10, 40, or 50.

[0073] As is known from the prior art, in curtain application devices, the adjustment of the nozzle opening requires very high precision because only the amount of treatment material required for the final treatment is applied through the nozzle opening. It is well known that the coating beam is equipped with adjusting screws, precision adjustment devices, or differential screws for adjusting the nozzle opening. These have proven to be insufficiently precise and / or oversized to achieve adequate accuracy without interfering with the application process itself. Figures 4A-4B The diagram schematically illustrates an example of an adjustment system 90 for adjusting the nozzle opening 95 of the application beam 13 of the curtain-type application device. This adjustment aims to avoid the aforementioned drawbacks and achieve extremely high precision without interfering with the application process itself. The adjustment system 90 includes a pair of adjusting wedges 92 advantageously mounted in grooves 96 aligned with the nozzle opening 95. Several pairs of spaced-apart adjusting wedges 92 can be arranged along the length of the application beam 13. The adjusting wedges 92 are connected to adjusting screws 91 and fastening screws 93 for adjusting the pair of adjusting wedges 92 to adjust the nozzle opening 95. During adjustment, the fastening screws 93 secure the pair of adjusting wedges 92 in the grooves 96, thus achieving a backflash-free arrangement. The desired precision is achieved by adjusting the angle of the adjusting wedges 92, but decreasing the angle improves precision.

[0074] In the preceding description, although some functionalities have been described with reference to certain features and examples, these functionalities can be performed by other features and examples, whether or not they have been described. Similarly, although some features have been described with reference to certain examples, those features can also exist in other examples, whether or not they have been described.

[0075] The above descriptions are merely some advantageous examples of the invention. The invention is not narrowly limited to these examples, and many modifications and variations can be made within the scope of the invention.

Claims

1. A treatment unit for processing fiber webs, the treatment unit comprising at least two treatment substance application devices (10, 40, 50), characterized in that, The first treatment material application device (10) of the two treatment material application devices is a double-sided curtain application device (10) for applying treatment material to one or both sides of the fiber web, followed by a drying section (20) for drying one or both sides of the fiber web respectively, the drying section (20) including at least partially non-contact drying by a hot air dryer (21), and the second treatment material application device (40) of the two treatment material application devices is a double-sided film application device (40) for applying treatment material to one or both sides of the fiber web, followed by a drying section (20) for drying one or both sides of the fiber web respectively, the drying section including at least partially non-contact drying by a hot air dryer (21).

2. The processing unit according to claim 1, characterized in that, The curtain-type application device (10) includes two processing rollers (11) forming a processing pressure zone between the two processing rollers (11), and the two processing rollers (11) are hard rollers, one or both of which are metal rollers with a hardness of at least 300 HV, or one or both of which are rollers with a composite coating layer with a reinforcing material and a hardness of at least 80 Shore D, or one or both of which are ceramic rollers with a hardness of at least 300 HV, or one or both of which are rollers that can use a hard polymer roller coating layer (rubber or polyurethane) with a hardness of 80 Shore D, advantageously at least 90 Shore D.

3. The processing unit according to claim 1 or 2, characterized in that, The processing unit includes two processing material application devices: a curtain-type application device (10), which serves as the first processing material application device; And a membrane application device (40) as a second and final treatment substance application device.

4. The processing unit according to claim 1 or 2, characterized in that, The processing unit further includes a third processing substance application device (50), which is a scraper-type application device (50) for applying processing substance to one side of the fiber web, followed by a drying section (20) for drying one or both sides of the fiber web, the drying section including at least partially non-contact drying by a hot air dryer (21).

5. The processing unit according to claim 1, 2 or 4, characterized in that, The processing unit includes three processing substance application devices: a curtain-type application device (10) as the first processing substance application device; and a membrane-type application device (40) as the second processing substance application device. And a scraper-type application device (50) as the third and final treatment material application device.

6. The processing unit according to any one of claims 1-5, characterized in that, The processing unit includes at least one calender (30; 60), which is either a pre-calender (30) or a final calender (60).

7. The processing unit according to any one of claims 1-6, characterized in that, The processing unit includes two calenders (30, 60), one of which is a pre-calender (30) and is located between at least two processing material application devices, and the other calender is a final calender (60) located after the last processing material application device.

8. The processing unit according to any one of claims 1-7, characterized in that, The processing apparatus (10, 40, 50) is used as a sizing machine for applying sizing agent to the fiber web and / or a coating machine for applying coating pigment to the fiber web.

9. A method for processing fiber webs, wherein the fiber webs are processed in a processing unit comprising at least two processing material application devices (10, 40, 50), characterized in that, In the method: a) Apply a treatment substance to one or both sides of the fiber web using a double-sided curtain application device (10); then b) The fiber web is dried on one or both sides by at least partially non-contact drying in a hot air dryer (21); thereafter c) Apply a treatment substance to one or both sides of the fiber web using a double-sided film application device (40); after d) Drying one or both sides of the fiber web by at least partially non-contact drying in a hot air dryer (21).

10. The processing method according to claim 9, characterized in that, In the method, after steps a)-d), a treatment substance is applied to one side of the fiber web by a scraper-type application device (50), and then the one or both sides of the fiber web are dried by at least partially non-contact drying in a hot air dryer (21).

11. The processing method according to claim 9 or 10, characterized in that, In the processing method, the fiber web is calendered in the processing section by at least one calender (30; 60), the at least one calender being a pre-calender (30) or a final calender (60).

12. The processing method according to any one of claims 9-11, characterized in that, In the processing method, the fiber web is pre-calendered by a pre-calender (30) between at least two processing material application devices (10, 40) for applying processing materials, and in the method, the fiber web is calendered by a final calender (60) after the application of processing materials by the final processing material application device.

13. The processing method according to any one of claims 9-12, characterized in that, In the processing method, an sizing agent is applied to the fiber web and / or a coating pigment is applied to the fiber web.

14. The processing method according to any one of claims 9-13, characterized in that, In the method, the crimping of the fiber web is controlled by controlling the dry matter content of the treatment material to be applied and / or by applying water to one side and / or by controlling the drying of the fiber web.

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