CN108457125A - The processing unit and processing method of the production line of production barrier cloth of coating-type fiber web - Google Patents

Abstract

The present invention relates to a kind of processing units of the production line for producing barrier cloth of coating-type fiber web, particularly obstructing cloth of coating-type board web, the processing unit includes coating part (70), it includes a device, which is applied to coating substance layer on fiber web to be formed：One or more barrier coating layer；Heat sealable coating layer on barrier coating layer, can also form one of described barrier coating layer；And protection coating, it is located at or without on the heat sealable coating layer of barrier property, the glass transition temperature (Tg) and the glass transition temperature of the heat sealable coating layer with or without barrier property of the protection coating are same or higher.The invention further relates to a kind of methods for producing barrier cloth of coating-type fiber web, particularly obstructing cloth of coating-type board web.

Description

Handling section and handling method of a production line for the production of barrier coated fibrous webs

technical field

The present invention relates to a treatment section of a production line for producing barrier coated fibrous webs and a treatment method for producing barrier coated fibrous webs. In particular, the invention relates to the treatment section of a production line for producing barrier coated paperboard webs and to a treatment method for producing barrier coated fibrous webs, in particular barrier coated paperboard webs.

Background technique

As is known in the prior art, a fibrous web production process usually involves an assembly formed of a plurality of devices arranged in succession in a production line. A typical production line consists of a headbox, a wire section and a press section followed by a dryer section and a reel. Production lines and processing lines still further comprise other devices and/or sections for finishing the fibrous web, such as pre-calenders, sizers, final calenders, coating sections. The production line usually also includes at least one slitter-winder for forming customer rolls and roll wrappers or sheet cutters. In the present description and the following claims, fibrous web means eg paper web and board web.

When producing fibrous webs such as paper or board webs, sizing is used by adding sizing substances, such as adhesive chemicals, in order to modify the properties of the fibrous web. Sizing can be divided into internal sizing and surface sizing. During internal sizing, sizing medium is added to the pulp at the wet end of the fiber web machine before forming. In surface sizing, the sizing substance is added to the surface of the fiber web directly or by means of rollers, usually at the dry end of the fiber web machine, but it can also be applied at other parts of the fiber web production line The substance is added to the fibrous web. The sizing of the paper and board webs is usually carried out using separate size machines. With regard to the sizing machines, different kinds of sizing technologies are used in prior art configurations, such as pond sizing technology or film transfer technology or spray sizing technology.

Coated fiber web grades and coatings are becoming more and more popular, so the requirements for coating processes and equipment are getting higher and higher. In coating, especially in pigment coating, at least one surface of the fibrous web is formed with one or more layers of coating pigment (coating substance) at a coating station and then dried. The process of coating can be divided into supplying coating color onto the web surface (called applying coating color), and adjusting the final amount of coating color. Coating layers of paper and board webs usually use a coating device - a coater. With regard to the coating machines, different kinds of coating techniques are used in the prior art in cooperating structures, such as curtain coating, knife coating, spray coating or film transfer coating techniques.

In publication DE 20 2007 005 188 U1 a device for providing multi-layer curtain coating on a fibrous web is disclosed, which device is formed as a multi-layer tool with a plurality of feed devices connected to associated storage containers for A free-falling multilayer ply is created to apply a multilayer coating on the fibrous web.

Barrier Coated fibrous web products (i.e. barrier products) are typically coated paper or paperboard based fibrous web products having one or more layers with barrier functions such as water barrier, water vapor barrier, grease / oil / solvent barrier, gas and fragrance barrier. These barriers are thus resistant to the penetration of gases (odours, fragrances, oxygen, nitrogen, carbon dioxide, water vapor, etc.), of polar (eg water) or non-polar (eg grease, oil) fluids or solvents, Resistance to solid and particulate pollutants (nanoparticles, dust, smog, dirt, etc.) and radiation penetration. A barrier product may have one or more barrier layers with one or more different barrier functions.

Barrier coated fibrous webs are produced eg by extrusion applying polyethylene to the surface of the fibrous web and/or by laminating aluminum foil on the surface of the fibrous web. A disadvantage of extrusion-coated barrier products is their poor pulpability and therefore poor recyclability. It is also possible to use application by means of dispersion coating, in which a binder is applied, for example a latex with several different types of fillers and/or mineral pigments and/or additives. The use of dispersion coating is limited because the coating substances are more expensive than those typically used for extrusion coating. The coating layer is dried after application to provide a fixed, continuous, non-porous coating on the fiber surface with the desired barrier properties. A major goal of barrier coating applications is to achieve a uniform coating layer. Since a continuous and uniform coating layer is required, the drying of the coating needs to be accurately and precisely measured, but at the same time, the drying must be effective enough to prevent sticking of the coating layer during winding and/or rewinding, i.e. to avoid Blocking phenomenon, but not so strong as to maintain the heat sealability (hot melt) properties of the barrier coating layer. Typically, the surfaces of dispersion coated barrier products need to be joined when manufacturing packages where good heat sealability is required. In the blocking phenomenon, if the drying is not effective enough or the coated product is exposed to unsuitable temperature, humidity or pressure, the surface of the product is blocked, i.e. the coated fibrous web is rewinding) adhesion. Especially in the inline production of barrier coated fibrous webs, the risk of clogging is very high if the fibrous web does not have sufficient time to cool down after dispersion coating and before winding or rewinding. Especially in the in-line production of barrier coated fibrous webs there is also the risk that the temperature of the fibers during coating is too high, possibly causing excessive penetration of the coating substance into the fibrous web.

In publication WO2010052571, a coated recycled paper or board product and a process for its production are disclosed to provide a coated paper or board product with enhanced barrier properties, in which process the In one or more coating stations in-line, paper or board is coated with a polymer emulsion. The disclosed method of producing coated recycled paper or paperboard comprises: supplying to at least one coater an aqueous coating stock comprising from about 70 to about 90% by weight of the coating stock based on the dry weight of the coating stock polymer emulsion, and based on the dry weight of the coating material, the aqueous coating material comprises about 10 to about 30% by weight of pigment; the aqueous coating material is applied to paper or paperboard to form on paper or paperboard coating layer; drying the aqueous coating layer to provide coated paper or paperboard; and cooling the coated paper or paperboard, wherein the coating, drying and cooling are carried out at a temperature such that the coated The paperboard product effectively provides a water resistance of less than about 10 g/ ^m2 and a water vapor transfer rate of less than 120 g/ ^m2 , wherein the coated paper or paperboard product is heat sealable. In this method, the aqueous coating stock is supplied to an off-line coater, and the off-line coater is at the same location as the machine feeding the paper or board. The polymer emulsion is selected from the group consisting of acrylic polymers, acrylic copolymers, copolymers of styrene and butadiene, vinyl acetate polymers, polyvinyl alcohol, polyethylene vinyl acetate , polyvinyl chloride, polyvinyl chloride and mixtures thereof, pigments selected from the group consisting of aqueous dispersions of coating grade clay, titanium dioxide, calcium carbonate, barium sulfate, talc, zinc sulfate, aluminum sulfate , calcium oxide reaction products, lithopone, zinc sulfide and mixtures thereof. It is disclosed that about 5 g/m ² to about 10 g/m ² of aqueous coating material is applied by rod or rod, and that more than one coating layer is applied to the surface of paper or board, and each coating layer is composed of Different polymer emulsions are formed and at least one coating layer is applied to each side of the paper or board.

Contents of the invention

The object of the present invention is to create a treatment section of a production line for producing barrier coated fibrous webs and a treatment method for producing barrier coated fibrous webs, wherein the above mentioned problems are solved or at least minimized.

In order to achieve the objects mentioned above and set forth below, the treatment section according to the invention is mainly characterized in that the coating section comprises means for applying a layer of coating substance to the fibrous web to form: one or more barrier coating layers a heat-sealable coating layer which can also form one of said barrier coating layers; a protective coating located on said heat-sealable coating layer with or without barrier properties; On the seal coating layer, the glass transition temperature of the protective coating is the same as or higher than the glass transition temperature of the heat-sealable coating layer with or without barrier properties. Instead, the treatment method according to the invention is mainly characterized in that, in the treatment method, a layer of coating substance is applied to the fiber web in the coating section on one side or on both sides to form: one or more barrier coatings layer; a heat-sealable coating layer on said barrier coating layer, said heat-sealable coating layer also being capable of forming one of said barrier coating layers; and a protective coating located on said barrier coating layer On said heat-sealable coating layer with or without barrier properties, the glass transition temperature of said protective coating is the same as the glass transition temperature of said heat-sealable coating layer with or without barrier properties or higher. Other preferred embodiments and features of the invention are disclosed herein.

According to the invention, the processing section of a production line for the production of barrier-coated fiber webs, in particular barrier-coated paperboard webs, comprises a coating section comprising a device for applying a layer of coating substance clothed onto the fibrous web to form: one or more barrier coating layers; a heat-sealable coating layer on the barrier coating, which may also form one of the barrier coating layers; and a protective coating on the barrier coating with On a heat-sealable coating layer with or without barrier properties, the glass transition temperature of the protective coating is the same as or higher than that of the heat-sealable coating layer with or without barrier properties.

According to the invention, in the treatment method for producing a barrier-coated fibrous web, in particular a barrier-coated paperboard web, a layer of coating substance is applied to the fibrous web on one side or on both sides in the coating section to form: one or more barrier coating layers; a heat-sealable coating layer on the barrier coating layer, which may also form one of the barrier coating layers; and a protective coating layer on the barrier coating layer with or without barrier coating layer The glass transition temperature of the protective coating is the same as or higher than the glass transition temperature of the heat-sealable coating layer with or without barrier properties.

According to a preferred feature of the invention, the glass transition temperature of the protective coating is between -20°C and 50°C, preferably between -10°C and 20°C, and the glass transition temperature of the heat-sealable coating layer with or without barrier properties The transition temperature is -20°C to 50°C, preferably -10°C to 20°C.

According to a preferred feature of the invention, the coating section comprises a multilayer curtain coater for applying one or more coating layers on the fibrous web to provide a barrier coating Cloth, heat sealable coatings with or without barrier properties and protective coatings. According to a preferred feature of the invention, the coating section comprises one or more coaters for applying one or more layers of coating substances on the fibrous web to provide barrier coating, heat sealable coating Cloth layer and protective coating.

According to a preferred feature of the invention, the processing section comprises a size press for sizing the fibrous web before the coating section.

According to a preferred feature of the invention, the treatment section comprises a pre-calender.

According to a preferred feature of the invention, the processing section comprises a cooling device before the size press and/or the pre-calender, and/or the processing section includes a reel and an optional cooling device before the reel.

According to a preferred feature of the invention, the fibrous web is sized on one or both sides in a size press before the coating section.

According to a preferred feature of the invention, the fibrous web is calendered in a pre-calender.

According to a preferred feature of the invention, the fibrous web is cooled before the size press and/or the pre-calender and/or the reel.

Preferably, according to a preferred embodiment of the present invention, the coated outermost layer of the barrier coated fibrous web is a protective coating layer, which prevents the fibrous web layer adhesion and/or friction reduction in the further processing of the fiber web, for example in sheet production. Even though the glass transition temperature (Tg) of the protective coating layer is the same as or higher than that of the heat-sealable barrier coating layer, the protective coating layer does not prevent heat fusion due to the thinner protective coating layer.

In addition to the environmental factors of the clogging phenomenon, the composition of the dispersion coating also has an effect. For example, the type of polymer substance used, crosslinking, the use of waxes, fillers and pigments all have an effect on the clogging phenomenon. The main cause of sticking in the blocking effect is the polymer used in the dispersion coating. The glass transition temperature of an amorphous polymer can be considered a measure of its softness. A lower glass transition temperature increases the risk of blocking phenomena, while too high a glass transition temperature has a negative effect on film formation and may lead to difficulties in the heat-sealing process. Polymers with too low a glass transition temperature in dispersion coating can also cause processing problems due to the higher coefficient of friction of the coated surface.

The sizing agent is preferably a starch-based sizing agent, a carboxymethylcellulose-based sizing agent, a polyvinyl alcohol-based sizing agent, a synthetic or bio-based polymer latex. Synthetic or bio-based polymer latices are for example styrene butadiene latex, polyvinyl acetate latex, acrylate latex, polyvinyl alcohol dispersions, polyolefin dispersions or any mixtures, copolymers or derivatives thereof.

Preferably, the materials used in the barrier coating layer comprise synthetic or bio-based polymer latexes and mineral fillers/pigments. Synthetic or bio-based polymer latices are for example styrene butadiene latex, polyvinyl acetate latex, acrylate latex, polyvinyl alcohol dispersions, polyolefin dispersions or any mixtures, copolymers or derivatives thereof.

Preferably, the heat-sealable coating layer, with or without barrier properties, comprises a synthetic or bio-based polymer latex with or without mineral fillers/pigments. Synthetic or bio-based polymer latices are for example styrene butadiene latex, polyvinyl acetate latex, acrylate latex, polyvinyl alcohol dispersions, polyolefin dispersions or any mixtures, copolymers or derivatives thereof.

Preferably, the protective coating layer is a synthetic or bio-based polymer latex with or without mineral fillers/pigments and/or waxy substances. Synthetic or bio-based polymer latices are for example styrene butadiene latex, polyvinyl acetate latex, acrylate latex, polyvinyl alcohol dispersions, polyolefin dispersions or any mixtures, copolymers or derivatives thereof.

All coating compositions may contain additives; thickeners, defoamers/antifoams, dispersion aids, additional pigments, crosslinkers/insolubilizers, slip additives/lubricant, antiblocking and antiblocking agents.

The weight of the barrier coating (for one layer) (dry solids) is 3-20 g/m ² , preferably 4-9 g/m ² . The weight (dry solids) of the heat-sealable coating layer (with or without barrier properties) is 3-20 g/m ² , preferably 6-9 g/m ² . The protective coating has a weight (dry solids) of 1-10 g/m ² , preferably 3-6 g/m ² .

Preferably, according to an advantageous embodiment of the invention, the fibrous web is sized in the treatment section by a size press in the form of surface sizing before the coating layer is applied. The surface strength and stiffness of the barrier coated fibrous web are thereby increased. The sizing also seals and smoothes the fiber surface so that the barrier coating substance does not penetrate into the fiber web, which would result in a loss of barrier properties. The sizing is advantageously provided by pool size presses, membrane size presses, spray size presses or very advantageously by nip size presses with curtain coaters or foam applicators, which increases the smoothness and strength and provides a uniform coating layer, whereby for example short or long fibers, fiber-based granules, nanocellulose-based substances, lignin-based substances, mineral Pigments/fillers, nanofibers.

In the treatment section according to the invention, a dispersion coating device is used for the barrier substance, as it can be used in an in-line treatment coating machine, and generally (as known as such) coating equipment can also be used. Advantageously, a multilayer curtain coater is used.

Preferably, cooling means are located in the processing section after the coater to help prevent clogging.

Preferably, a pre-calender is used in the processing section. Before the size press and/or pre-calender, cooling means are preferably positioned to maintain the loft of the fibrous web and prevent excessive penetration of the coating substance into the fibrous web, thereby enhancing the formation of the barrier coating layer.

The coating layer can be applied to one side of the fibrous web or to both sides of the fibrous web.

Description of drawings

Describe the present invention in detail below with reference to accompanying drawing, in accompanying drawing:

Figure 1 schematically shows a preferred example of a production line for barrier coated fibrous webs.

Figure 2 schematically shows an example of a barrier coated fibrous web.

Detailed ways

In the drawings and their description, the same reference numerals are used for corresponding parts, subassemblies and sections unless mentioned otherwise.

In the example of FIG. 1 , a production line for a barrier coated fibrous web product is shown very schematically, and it is readily understood by those skilled in the art that an actual production line for a barrier coated fibrous web product may include Several assemblies, components and devices constructed in various ways known to the person. It should also be noted that the present invention can be used for the production of single-sided as well as double-sided fibrous web products as well as many types of barrier-coated fibrous web products (barrier products).

In the example of Figure 1, the production line comprises a headbox 10, a wire section (i.e. forming section) 20 and a press section 30, followed by a drying section 40, a size press 50 and optionally a pre-calender 60, a coating Cloth section 70, winder 80 and slitter-rewinder 90. The production line may also include roll wrappers or sheet cutters. In the example of FIG. 1 , the drying device 55 is positioned after the sizer 50 in order to dry the fibrous web, and the drying device 75 is positioned after the coating section 70 so that the fibrous web is wound in a reel 80 into Dry before master roll. In this example, the optional cooling device 100 is located before the size press 50 , the pre-calender 60 and the winder 80 . The size press 50 may be located in any other part or section of the production line prior to the coating section 70 . The size press 50 is advantageously a pond size press, a membrane size press, a spray size press or very advantageously a nip size press with a curtain coater or a foam coater. Applicator. Coating section 70 advantageously includes a multi-layer curtain sizer that applies one or more layers of coating substance to the fibrous web to provide a barrier coating and a heat-sealable coating, which may also form One of the barrier coating layers and protective coating. The coating section 70 may also be provided with a succession of coaters, each for one or more layers of coating substance.

In the treatment process starting at the headbox 10, pulp is fed onto a wire section (ie forming section) 20 and water is removed from the pulp by means of water removal means. In the press section 30, further moisture is removed by pressing the fibers in a press nip and/or in a shoe-or belt nip. The fibrous web is dried in a subsequent drying section 40, usually by contact drying the fibrous web by contacting it on a heated surface of a drying cylinder. After the drying section 40 , in a size press 50 , a sizing substance is applied to the fiber web, which is then usually dried by a subsequent drying device 55 . Next, the fibrous web may be pre-calendered in an optional pre-calender 60, and in a coating section 70 at least one coating layer is applied on the fibrous web to provide a barrier coating and a protective coating. After coating, the fibrous web is dried by a drying device 75, usually by non-contact drying device at least at the beginning of the drying. In the winder 80, the fibrous web is wound into a master roll, which is unwound in the unwinder of the slitter-winder 90, and then cut into partial webs in the slitter, which It is rewound into user volume in the rewinder. User rolls may be wrapped in a roll wrapping machine. The fibrous web can also be cut into pieces in a slicer. By means of an optional cooling device 100 located before the size press 50 and/or the pre-calender 60 and/or the reel 80 the fibrous web can be cooled. Sizing can also be done in any other part or section of the production line preceding the coating section 70 .

An example of a barrier product is shown very schematically in the example of FIG. 2 . In this example, the barrier coating is provided on one side of the fibrous web, i.e. as a single-sided fibrous web product, but it should be noted that this product can also be a double-sided product, where the coating on both sides can be similar or different. Next to the surface of the fibrous web W is shown a layer S of sizing substance. Outwardly from the sizing substance is the barrier coating layer B, which comprises one or more layers of coating substance to form a barrier coating layer on the fibrous web W. Typically at least one coating substance layer is used to provide a barrier coating layer. On top of the barrier coating layer B is a heat sealable coating layer H, which may also form one of the barrier coating layers, and the outermost layer is the protective layer P. The outermost coating layer of the barrier coated fibrous web is a protective coating layer P having a glass transition temperature (Tg) equal to or higher than that of the heat-sealable layer H with or without barrier properties .

The invention has been described above only with reference to some advantageous embodiments, but many modifications and variations are possible in the original treatment section of barrier-coated fibrous web and in the original treatment method for producing barrier-coated fibrous web .

Claims (14)

1. A treatment section of a production line for the production of barrier-coated fiber webs, in particular barrier-coated paperboard webs, comprising a coating section (70), characterized in that the coating section (70) Means comprising applying a layer of coating substance to said fibrous web (W) to form: one or more barrier coating layers (B); on said barrier coating layer (B) A heat-sealable coating layer (H), which can also form one of the barrier coating layers; a protective coating (P), which is located with or without On said heat-sealable coating layer (H) with barrier properties, the glass transition temperature (Tg) of said protective coating (P) is different from that of said heat-sealable coating layer (H) with or without barrier properties. ) have the same or higher glass transition temperature. 2. The treatment part according to claim 1, characterized in that the protective coating (P) has a glass transition temperature of -20°C to 50°C, preferably -10°C to 20°C, with or without The glass transition temperature of the heat-sealable coating layer (H) having barrier properties is -20°C to 50°C, preferably -10°C to 20°C. 3. The processing section according to claim 1 or 2, characterized in that the coating section (70) comprises a multi-layer curtain coater for coating the fibers One or more layers of coating substances are applied to the web (W) to provide said barrier coating layer (B), said heat-sealable coating layer (H) with or without barrier properties and said protective Coating (P). 4. The treatment section according to claim 1 or 2, characterized in that the coating section (70) comprises one or more coaters for coating the fibrous web (W ) to provide said barrier coating layer (B), said heat-sealable coating layer (H) with or without barrier properties and said protective coating (P ). 5. The treatment section according to any one of the preceding claims, characterized in that it comprises a sizer ( 50). 6. A treatment section according to any one of the preceding claims, characterized in that it comprises a pre-calender (60). 7. The treatment section according to claim 5 or 6, characterized in that it comprises a cooling device (100) before the size press (50) and/or the pre-calender (60), and/ Or the processing section comprises a reel (80) and an optional cooling device (100) before the reel (80). 8. A process for producing a barrier-coated fibrous web, in particular a barrier-coated paperboard web, in which process a layer of coating substance is coated on one or both sides in a coating section (70) applied to said fibrous web (W) to form: one or more barrier coating layers (B); a heat-sealable coating layer (H) on said barrier coating layer (B), said heat-sealable coating layer can also form one of said barrier coating layers; and a protective coating (P) positioned over said heat-sealable coating layer with or without barrier properties On layer (H), said protective coating (P) has a glass transition temperature (Tg) equal to or higher than that of said heat-sealable coating layer (H) with or without barrier properties . 9. The processing method according to claim 8, characterized in that the fiber web is sized on one side or on both sides in a sizer (50) before the coating section (70). 10. Processing method according to claim 8 or 9, characterized in that the fibrous web is calendered in a pre-calender (60). 11. Process according to any one of claims 8-10, characterized in that the fibrous web is processed in a size press (50) and/or a pre-calender (60) and/or a reel (80) was previously cooled. 12. according to the processing method described in any one in claim 8-11, it is characterized in that, sizing agent is starch-based sizing agent, carboxymethylcellulose-based sizing agent, polyvinyl alcohol-based sizing agent, Synthetic or bio-based polymer latex. 13. The treatment method according to any one of claims 8-12, characterized in that the substances used for the barrier coating layer comprise synthetic or bio-based polymer latexes and mineral fillers/pigments. 14. The treatment method according to any one of claims 8-13, characterized in that the protective coating is a synthetic or bio-based polymer latex with or without mineral fillers/pigments and/or waxy substances.