CN116949862A

CN116949862A - Paper preparation method for controlling resin deposition and paper

Info

Publication number: CN116949862A
Application number: CN202310887895.4A
Authority: CN
Inventors: 蒋燕飞; 田维实; 王俊明
Original assignee: Ningbo Asia Pulp and Paper Co Ltd
Current assignee: Ningbo Asia Pulp and Paper Co Ltd
Priority date: 2023-07-18
Filing date: 2023-07-18
Publication date: 2023-10-27

Abstract

The application discloses a paper preparation method for controlling resin deposition and paper, comprising the following steps: mixing a plurality of pulps in a mixed pulp tank to obtain mixed pulp; a first resin control agent is added into the mixed pulp pool, and the first resin control agent is used for dispersing resin particles in the mixed pulp; delivering the mixed paper pulp into a paper machine pulp tank, flowing out the mixed paper pulp by using the paper machine pulp tank, and forming on a net to obtain wet paper; a second resin control agent is added in the paper machine pulp tank and is used for reacting with the dispersed resin particles so as to reduce the content of free resin particles in the wet paper; squeezing the wet paper by using a squeezing roller, and stripping the wet paper after the squeezing is completed; the press roll surface is sprayed with a third resin control agent for reducing the deposition of free resin particles on the press roll surface. The application can reduce the deposition of resin particles on the surface of the press roller, and improve the stripping effect of paper and the press roller, thereby improving the paper flatness.

Description

Paper preparation method for controlling resin deposition and paper

Technical Field

The application relates to the field of papermaking, in particular to a paper preparation method for controlling resin deposition and paper.

Background

In the paper industry, the production of pulp is an essential feature. The pulp produced from wood fibers contains, in addition to cellulose, hemicellulose and lignin, water-insoluble resins that deposit on equipment surfaces, which can reduce machine operating efficiency and paper product quality.

In the prior art, the chemical control method is the most effective resin control method, which prevents the resin from depositing on the surface of the equipment by using some resin control agents such as talc, aluminum sulfate, chelating agent, etc. to adhere the resin particles to the surface of the fiber or stably disperse in the slurry system.

However, although the existing resin control method can not affect the running performance of the paper machine system equipment, resin particles can be adsorbed on the surface of fibers, and during the paper making process, the resin particles on the surface of wet paper still can be deposited on the surface of a pressing part of the paper machine, especially the surface of a pressing roller, so that the peeling of the paper and the pressing roller is affected, and the surface smoothness of the paper is poor, and then the product quality is affected.

Disclosure of Invention

The application mainly solves the technical problems of poor stripping effect and poor paper flatness caused by resin deposition on the surface of a press roller by providing a paper preparation method for controlling resin deposition and paper.

In order to solve the technical problems, a first technical scheme adopted by the application is to provide a paper preparation method for controlling resin deposition, which comprises the following steps: mixing a plurality of pulps in a mixing chest to obtain a mixed pulp; wherein, the first resin control agent is added in the mixing pulp pool and is used for dispersing resin particles in the mixed pulp; delivering the mixed paper pulp into a paper machine pulp tank, flowing out the mixed paper pulp by using the paper machine pulp tank, and forming on a net to obtain wet paper; wherein, the paper machine pulp tank is added with a second resin control agent which is used for reacting with the dispersed resin particles so as to reduce the content of free resin particles in the wet paper; squeezing the wet paper by using a squeezing roller, and stripping the wet paper after the squeezing is completed; wherein the surface of the press roll is sprayed with a third resin control agent for reducing the deposition of free resin particles on the surface of the press roll.

Wherein the first resin control agent comprises a surfactant, and the addition amount of the surfactant is 0.2-0.8 ton/absolute dry slurry; a step of mixing a plurality of pulps in a mixing chest to obtain a mixed pulp, comprising: mixing a plurality of slurries in a mixing tank to which a surfactant is added to obtain a mixed pulp; after the step of mixing the plurality of pulps in the mixing chest to obtain a mixed pulp, it comprises: the mixed pulp is fed to a paper machine chest by means of a pump and a pressure screen, so that the surfactant disperses the resin particles by the shearing action of the pump and the pressure screen.

Wherein the surfactant comprises a non-discrete dispersant comprising a lipophilic group and a hydrophilic group; wherein the lipophilic group has a carbon chain length of 12 to 16 carbon atoms.

Wherein the second resin control agent comprises a cationic water-soluble polymer, and the addition amount of the cationic water-soluble polymer is 0.4-1.0 ton/paper; feeding the mixed pulp into a paper machine pulp tank, flowing the mixed pulp out by using the paper machine pulp tank, and forming on a net to obtain wet paper, wherein the method comprises the following steps of: feeding the mixed pulp into a paper machine pulp tank added with a cationic water-soluble polymer so as to enable the cationic water-soluble polymer to react with the dispersed resin particles to obtain a compound attached to the surface of the fiber; and (3) flowing out the mixed paper pulp attached with the compound by using a paper machine pulp tank, and forming on a net to obtain wet paper.

Wherein the step of feeding the mixed pulp into a paper machine chest to which a cationic water-soluble polymer is added to react the cationic water-soluble polymer with the dispersed resin particles to obtain a composite adhered to the surface of the fiber, comprises: preparing a cationic water-soluble polymer and clear water; wherein the mass ratio of the cationic water-soluble polymer to the clear water is 1:20-100; mixing and uniformly stirring the cationic water-soluble polymer and clear water according to the raw material ratio; the diluted cationic water-soluble polymer is added into a paper machine pulp tank.

Wherein the molecular weight of the cationic water-soluble polymer is 30-70 ten thousand, and the charge density is 2.5-6.5 meq/g.

Wherein the third resin control agent comprises a squeeze roll stripper, and the dosage of the squeeze roll stripper is 2-8 mL/min; a step of pressing the wet paper with a press roll and peeling the wet paper after the pressing is completed, comprising: the wet paper is pressed by a press roll coated with a press roll stripper, and the wet paper is stripped after the press is completed.

Wherein the squeeze roll stripper is an aqueous emulsion composed of organic silicon and synthetic esters.

Wherein the prepared paper is multi-layer composite paper; a step of mixing a plurality of pulps in a mixing chest to obtain a mixed pulp, comprising: respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond added with a surfactant to obtain mixed paper pulp corresponding to each fiber layer; after the step of mixing the plurality of pulps in the mixing chest to obtain a mixed pulp, it comprises: the mixed pulp corresponding to each fiber layer is conveyed to a pulp pool of a paper machine by a pump and a pressure screen, so that the surfactant disperses the resin particles by the shearing action of the pump and the pressure screen; feeding the mixed pulp into a paper machine pulp tank, flowing the mixed pulp out by using the paper machine pulp tank, and forming on a net to obtain wet paper, wherein the method comprises the following steps of: feeding the mixed pulp corresponding to each fiber layer into a paper machine pulp tank added with a cationic water-soluble polymer so as to enable the cationic water-soluble polymer to react with the dispersed resin particles to obtain a compound attached to the surface of the fiber; respectively flowing out the mixed paper pulp which is corresponding to each fiber layer and is adhered with the compound by utilizing a multilayer headbox in a paper machine pulp tank, and performing net surfing and forming to obtain wet paper corresponding to each fiber layer; sequentially compounding the wet paper corresponding to the fiber layers to obtain a plurality of layers of wet paper; a step of pressing the wet paper with a press roll and peeling the wet paper after the pressing is completed, comprising: squeezing the multi-layer wet paper by utilizing a squeezing roller sprayed with a squeezing roller stripping agent, and stripping the multi-layer wet paper after the squeezing is finished; the step of pressing the wet paper with a press roll and peeling the wet paper after the pressing is completed, comprises: and drying the pressed multilayer wet paper, and sizing the dried multilayer paper to obtain the multilayer composite paper.

In order to solve the technical problems, a second technical scheme adopted by the application is to provide paper which is prepared by the paper preparation method for controlling resin deposition.

The beneficial effects of the application are as follows: unlike the prior art, the present application provides a paper preparation method for controlling resin deposition, which can disperse resin particles in mixed pulp by using a first resin control agent by adding the first resin control agent in a mixed pulp tank, so that the dispersed resin particles stably exist in a pulp system. By adding the second resin control agent to the paper machine chest, the second resin control agent can be used to react with the dispersed resin particles to form a composite, so that the content of free resin particles in the wet paper is reduced, and the possibility of depositing the resin particles on the surface of the press roll is reduced. Further, by spraying the third resin control agent on the surface of the press roll, the surface free energy of the press roll surface can be reduced by the third resin control agent, making it difficult for the free resin particles to adhere to the press roll surface. According to the application, through the cooperative use of the first resin control agent, the second resin control agent and the third resin control agent, the deposition of free resin particles on the surface of the press roller can be reduced, and the stripping effect of paper and the press roller is improved, so that the paper flatness is improved, and the product quality is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic flow chart of a first embodiment of a paper making method of the present application for controlling resin deposition;

FIG. 2 is a schematic flow chart of a second embodiment of a paper making method of the present application for controlling resin deposition;

FIG. 3 is a schematic flow chart of a third embodiment of a paper making method of the present application for controlling resin deposition;

fig. 4a and 4b are SEM images of the multi-layered paper in example 3 and control group 2, respectively, of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to fall within the scope of the present application.

The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plurality" generally includes at least two, but does not exclude the case of at least one.

It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

It should be understood that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.

In the prior art, the chemical control method is the most effective resin control method, which prevents the resin from depositing on the surface of the equipment by using some resin control agents such as talc, aluminum sulfate, chelating agent, etc. to adhere the resin particles to the surface of the fiber or stably disperse in the slurry system. However, although the existing resin control method can not affect the running performance of the paper machine system equipment, resin particles can be adsorbed on the surface of fibers, and during the paper making process, the resin particles on the surface of wet paper still can be deposited on the surface of a pressing part of the paper machine, especially the surface of a pressing roller, so that the peeling of the paper and the pressing roller is affected, and the surface smoothness of the paper is poor, and then the product quality is affected.

Based on the above, the application provides a paper preparation method for controlling resin deposition and paper, which can solve the problems of poor stripping effect and poor paper flatness caused by resin deposition on the surface of a press roller.

Referring to fig. 1, fig. 1 is a schematic flow chart of a first embodiment of a paper preparation method for controlling resin deposition according to the present application. In this embodiment, the paper preparation method includes:

s11: mixing a plurality of pulps in a mixing chest to obtain a mixed pulp; wherein, the first resin control agent is added in the mixing pulp pool, and the first resin control agent is used for dispersing the resin particles in the mixing pulp.

In this embodiment, the plurality of pulps includes at least two of bleached long fiber wood pulp, bleached short fiber wood pulp, bleached mechanical pulp, and damaged pulp.

Wherein the bleached long fiber wood pulp is bleached sulfate softwood pulp (NBKP), the bleached short fiber wood pulp is bleached sulfate hardwood pulp (LBKP), and the bleached mechanical pulp can be bleached chemimechanical groundwood pulp (BCTMP) or alkaline hydrogen peroxide mechanical pulp (APMP).

The broke is the pulp of broke, which can be referred to as system recycled paper, and is waste paper produced in the paper making process. The broke referred to in the present application includes both dry broke, which refers in particular to broke produced in the dry part of the machine and later, and wet broke, which refers to broke produced in the wet part, such as the wire part and the press part. Thus, broke may include different pulp fibers used in the paper production process, such as mechanical pulp fibers, long fibers or short fibers, etc.

In this embodiment, the mixed pulp is used to make the top and bottom layers.

In other embodiments, the mixed pulp may also be used to make the facing layer and the core layer, as the application is not limited in this regard.

Specifically, the mixed pulp used to make the facer layer typically includes bleached sulfate softwood pulp and bleached sulfate hardwood pulp, the mixed pulp used to make the core layer typically includes bleached sulfate hardwood pulp, bleached chemimechanical groundwood pulp, and broke pulp, and the mixed pulp used to make the bottom layer typically includes bleached sulfate softwood pulp and bleached sulfate hardwood pulp.

The wood pulp slurry comprises Dichloromethane (DCM) extract, the dichloromethane extract belongs to organic matter pollution, and the deposition on the surface of equipment can also influence the operation of a paper machine and the quality of paper.

In this embodiment, the first resin control agent is used for dispersing organic contaminants in addition to emulsifying and dispersing resin particles in the mixed pulp.

It is understood that by adding the first resin control agent to the mixed slurry tank, the large-particle resin can be dispersed into the fine-particle resin by the first resin control agent, so that the dispersed resin particles are stably present in the mixed slurry.

S12: delivering the mixed paper pulp into a paper machine pulp tank, flowing out the mixed paper pulp by using the paper machine pulp tank, and forming on a net to obtain wet paper; wherein, the paper machine pulp tank is added with a second resin control agent which is used for reacting with the dispersed resin particles so as to reduce the content of free resin particles in the wet paper.

In this embodiment, the second resin control agent reacts with the dispersed resin particles to form a composite, and the composite can be adsorbed on the surface of the fibers and then flows out of the machine chest together with the fibers, thereby reducing the deposition of the resin in the machine chest and further improving the operability of the machine system equipment.

It will be appreciated that the content of free resin particles in the mixed pulp is reduced due to the formation of the composite, and that the content of free resin particles in the formed wet paper is also reduced after the mixed pulp is discharged from the machine chest and formed on the wire.

S13: squeezing the wet paper by using a squeezing roller, and stripping the wet paper after the squeezing is completed; wherein the surface of the press roll is sprayed with a third resin control agent for reducing the deposition of free resin particles on the surface of the press roll.

When the wet paper is stripped from the press roll, the wet paper can be subjected to the reverse pulling force of the press roll on the wet paper, when more resin is deposited on the surface of the press roll, the reverse pulling force of the wet paper can be increased, so that the stripping effect of the wet paper and the press roll is poor, the surface smoothness of the paper is affected, and the quality of finished paper is finally affected.

In this embodiment, since the content of free resin particles in the wet paper has been reduced in the foregoing step, the precipitation phenomenon of resin particles on the surface of the press roll has been greatly alleviated. Further, by spraying the third resin control agent on the surface of the press roll, the surface free energy of the press roll surface can be reduced by the third resin control agent, and the free resin particles are less likely to adhere to the press roll surface. Wherein, the surface free energy is the expression of intermolecular forces on the surface of an object and is closely related to the wettability of the solid surface.

It can be appreciated that by the synergistic use of the first resin control agent, the second resin control agent and the third resin control agent, the deposition of resin particles on the surface of the press roll can be reduced, and further the reverse pulling force of the press roll on wet paper is reduced, the stripping efficiency and stripping effect of the paper and the press roll are improved, thereby improving the paper flatness and further improving the product quality.

In addition, organic contaminants and fine fiber-based contaminants are also difficult to attach to the press roll surface due to the reduced surface free energy of the press roll surface.

It can be appreciated that by reducing the deposition of organic and fine fiber type contaminants on the surface of the press roll, paper defects such as spots, holes, etc. and paper breakage caused by the contaminants can be reduced, thereby further improving the product quality.

Unlike the prior art, the present embodiment can disperse resin particles in mixed pulp by the first resin control agent by adding the first resin control agent to the mixed pulp tank, and stably present the dispersed resin particles in the pulp system. By adding the second resin control agent to the paper machine chest, the second resin control agent can be used to react with the dispersed resin particles to form a composite, so that the content of free resin particles in the wet paper is reduced, and the possibility of depositing the resin particles on the surface of the press roll is reduced. Further, by spraying the third resin control agent on the surface of the press roll, the surface free energy of the press roll surface can be reduced by the third resin control agent, making it difficult for the free resin particles to adhere to the press roll surface. According to the embodiment, through the cooperative use of the first resin control agent, the second resin control agent and the third resin control agent, the deposition of free resin particles on the surface of the press roller can be reduced, the stripping effect of paper and the press roller is improved, and therefore the paper flatness is improved, and the product quality is improved.

Referring to fig. 2, fig. 2 is a schematic flow chart of a paper preparation method for controlling resin deposition according to a second embodiment of the present application. In this embodiment, the paper preparation method includes:

s21: the various slurries are mixed in a mixing chest to which a surfactant is added to obtain a mixed pulp.

In this embodiment, the amount of the surfactant added is 0.2 to 0.8 ton/absolute dry slurry.

In this embodiment, the surfactant comprises a non-discrete dispersant comprising a lipophilic group and a hydrophilic group. Wherein the lipophilic group has a carbon chain length of 12 to 16 carbon atoms.

It can be understood that the lipophilic group in the non-discrete dispersant is similar to the components of the resin particles, and has better affinity to the resin particles and stronger emulsifying and dispersing effects to the resin particles under the condition of moderate carbon chain length. The hydrophilic group in the non-discrete dispersant can prevent the resin particles from flocculating into large particles to form resin barriers, thereby improving the stability of the dispersed resin particles in the mixed slurry.

S22: the mixed pulp is fed to a paper machine chest by means of a pump and a pressure screen, so that the surfactant disperses the resin particles by the shearing action of the pump and the pressure screen.

In this embodiment, the pump and the pressure screen are devices provided between the mixed pulp tank and the paper machine pulp tank, the pump is used for transporting the mixed pulp, the pressure screen is used for screening and purifying the mixed pulp, and both have a certain shearing action on the mixed pulp.

Specifically, as a certain contact time is required for dispersing the resin particles by the surfactant and a mechanical action is required in the dispersing process, the surfactant is added into the mixing tank in the embodiment, so that the dispersing effect of the surfactant on the resin particles can be ensured by utilizing a certain conveying time and shearing action of equipment such as a pump, a pressure screen and the like in the conveying process in the process of conveying mixed paper pulp into the paper machine tank.

S23: the mixed pulp is fed into a paper machine chest to which a cationic water-soluble polymer is added, so that the cationic water-soluble polymer reacts with the dispersed resin particles to obtain a composite attached to the surface of the fiber.

In this embodiment, the amount of the cationic water-soluble polymer added is 0.4 to 1.0 ton/paper.

In this embodiment, the cationic water-soluble polymer has a molecular weight of 30 to 70 tens of thousands and a charge density of 2.5 to 6.5meq/g. The cationic water-soluble polymer has high cationic charge density and low molecular weight, and can retain effective charge in a wide pH value range.

Specifically, the resin particles are usually negatively charged, and the cationic water-soluble polymer is combined with the resin particles through charge-interaction adsorption, so that a compound can be generated, and the compound can be fixed on the surface of the fiber through adsorption, and then flows out of the paper machine chest together with the fiber, thereby reducing the deposition of the resin in the paper machine chest, and further improving the operability of the paper machine system equipment.

Further, since the cationic water-soluble polymer can be adsorbed to the surface of the anionic particles quickly, the cationic water-soluble polymer needs to be diluted in advance before reacting with the resin particles so as to be uniformly distributed in the mixed pulp.

Specifically, preparing a cationic water-soluble polymer and clear water, wherein the mass ratio of the cationic water-soluble polymer to the clear water is 1:20-100. Mixing and stirring the cationic water-soluble polymer and clear water according to the raw material ratio, and adding the diluted cationic water-soluble polymer into a paper machine pulp pool.

S24: and (3) flowing out the mixed paper pulp attached with the compound by using a paper machine pulp tank, and forming on a net to obtain wet paper.

It is understood that the content of free resin particles in the mixed pulp decreases due to the formation of the composite, and that the content of free resin particles in the formed wet paper is also decreased after the mixed pulp to which the composite is attached is discharged from the machine chest and formed on the wire.

S25: the wet paper is pressed by a press roll coated with a press roll stripper, and the wet paper is stripped after the press is completed.

In this embodiment, the amount of the press roll stripper is 2 to 8mL/min.

In this embodiment, the press roll stripper is an aqueous emulsion composed of silicone and synthetic esters.

Wherein the surface tension of the press roll stripper is 15 to 20mN/m (stock solution surface tension at 20 ℃), and the stripping force is 90 to 150gf (sample preparation with a solid content of 0.5%).

In this embodiment, since the content of free resin particles in the wet paper has been reduced in the foregoing step, the precipitation phenomenon of resin particles on the surface of the press roll has been greatly alleviated. Further, the free energy of the surface of the press roll surface sprayed with the press roll stripping agent is reduced, free resin particles in wet paper are difficult to adhere to the surface of the press roll, the reverse pulling force of the press roll on the wet paper can be reduced, the stripping efficiency and stripping effect of the paper and the press roll are improved, the paper flatness is improved, and the product quality is improved.

Unlike the prior art, the present embodiment can disperse resin particles in mixed pulp by adding a surfactant to a mixing tank, and stably present the dispersed resin particles in a pulp system. By adding the cationic water-soluble polymer into the paper machine chest, the cationic water-soluble polymer and the dispersed resin particles react to form a compound, so that the content of free resin particles in the wet paper is reduced, and the possibility of depositing the resin particles on the surface of the press roller is reduced. Further, by spraying the press roll release agent on the press roll surface, the surface free energy of the press roll surface can be reduced by the press roll release agent, making it difficult for the free resin particles to adhere to the press roll surface. According to the embodiment, through the cooperative use of the surface control agent, the cationic water-soluble polymer and the squeeze roll stripper, the deposition of free resin particles on the surface of the squeeze roll can be reduced, and the stripping effect of paper and the squeeze roll is improved, so that the paper flatness is improved, and the product quality is improved.

Referring to fig. 3, fig. 3 is a schematic flow chart of a third embodiment of a paper preparation method for controlling resin deposition according to the present application. In this embodiment, the paper to be produced is a multi-layer composite paper, and the paper production method includes:

s31: and respectively mixing the multiple slurries of each fiber layer in a mixed slurry pond added with the surfactant to obtain mixed paper pulp corresponding to each fiber layer.

The specific process is described in S21, and will not be described here again.

In the present embodiment, the multi-layer composite paper may be a four-layer paper jam or a three-layer paper jam, which is not limited in the present application.

The multilayer cardboard can be cardboard or coated paper, and the multilayer cardboard can be single-sided coating cardboard or double-sided coating, which is not limited in the application.

In a specific implementation scenario, the multi-layer composite paper to be prepared is a four-layer single-sided coated white cardboard, and the fiber layer comprises a surface layer, a surface lining layer, a core layer and a bottom layer which are sequentially laminated. Wherein the mixed paper pulp for making the surface layer comprises bleached sulfate softwood pulp and bleached sulfate hardwood pulp, the mass percentage of the bleached sulfate softwood pulp is 15-30%, and the mass percentage of the bleached sulfate hardwood pulp is 70-85%. The mixed paper pulp used for manufacturing the surface lining layer comprises bleached sulfate softwood pulp and bleached sulfate hardwood pulp, wherein the mass percentage of the bleached sulfate softwood pulp is 15%, and the mass percentage of the bleached sulfate hardwood pulp is 85%. The mixed paper pulp used for manufacturing the core layer comprises 25-45% of bleached sulfate hardwood pulp, 35-60% of bleached chemimechanical ground wood pulp and 15-20% of damaged paper pulp. The mixed paper pulp used for manufacturing the bottom layer comprises bleached sulfate softwood pulp and bleached sulfate hardwood pulp, wherein the mass percentage of the bleached sulfate softwood pulp is 20-30%, and the mass percentage of the bleached sulfate hardwood pulp is 70-80%.

In another specific implementation scenario, the multi-layer composite paper to be prepared is three-layer double-sided coated paper, and the fiber layer comprises a surface layer, a core layer and a bottom layer which are sequentially laminated. Wherein the mixed paper pulp for making the surface layer comprises bleached sulfate softwood pulp and bleached sulfate hardwood pulp, the mass percentage of the bleached sulfate softwood pulp is 15-30%, and the mass percentage of the bleached sulfate hardwood pulp is 70-85%. The mixed paper pulp used for manufacturing the core layer comprises 25-45% of bleached sulfate hardwood pulp, 35-60% of bleached chemimechanical ground wood pulp and 15-20% of damaged paper pulp. The mixed paper pulp used for manufacturing the bottom layer comprises bleached sulfate softwood pulp and bleached sulfate hardwood pulp, wherein the mass percentage of the bleached sulfate softwood pulp is 20-30%, and the mass percentage of the bleached sulfate hardwood pulp is 70-80%.

Wherein, the resin content of the bleached sulfate softwood pulp is less than that of the bleached sulfate hardwood pulp, the content of the dichloromethane extract in the bleached sulfate softwood pulp is generally less than or equal to 0.10 percent, and the content of the dichloromethane extract in the bleached sulfate hardwood pulp is generally 0.10 to 0.40 percent.

The preparation cost of the bleached sulfate softwood pulp is higher than that of the bleached sulfate hardwood pulp, and the finished paper needs better stiffness, toughness and other strength properties and flatness, so that the bleached sulfate hardwood pulp used in the surface layer and the bottom layer is more.

It will be appreciated that the selection of bleached kraft hardwood pulp with a methylene chloride extract of 0.10 to 0.15% for the preparation of the top and bottom layers can reduce the total content of resin and organic contaminants at the source and thus reduce the deposition of resin and organic contaminants on the press roll surfaces.

Further, as the total content of resin and organic pollutants is reduced, the dosages of the surfactant added in the mixed pulp tank, the cationic water-soluble polymer added in the subsequent paper machine pulp tank and the press roller stripper sprayed on the surface of the press roller can be correspondingly reduced, so that the chemical cost is reduced, and the preparation cost of paper is further reduced.

S32: the mixed pulp corresponding to each fiber layer is conveyed to a pulp pool of a paper machine by a pump and a pressure screen, so that the surfactant disperses the resin particles by the shearing action of the pump and the pressure screen.

The specific process is described in S22, and will not be described here again.

S33: the mixed pulp corresponding to each fiber layer is fed into a paper machine pulp tank added with the cationic water-soluble polymer, so that the cationic water-soluble polymer reacts with the dispersed resin particles to obtain a compound attached to the surface of the fiber.

The specific process is described in S12 and S23, and will not be described here again.

S34: and (3) respectively flowing out the mixed paper pulp which is corresponding to each fiber layer and is adhered with the compound by utilizing a multilayer headbox in a paper machine pulp tank, and performing net surfing and forming to obtain the wet paper corresponding to each fiber layer.

S35: and sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper.

S36: the multi-layered wet paper sheet is pressed by a press roll coated with a press roll stripper, and the multi-layered wet paper sheet is stripped after the press is completed.

The specific process is described in S25, and will not be described here again.

When the wet paper is stripped from the press rolls, the wet paper can be subjected to reverse pulling force of the press rolls on the wet paper, and when the strength of the multi-layer wet paper is poor, the large reverse pulling force can cause slight delamination between layers, so that paper diseases similar to orange peel appear on the surface of the paper. When more resin is deposited on the surface of the press roll, the reverse pulling force of the multi-layer wet paper is increased, more serious layering occurs between layers, and further the orange peel is more serious. The paper diseases can further influence the printing performance of paper, the phenomena of dot unreliability, printing and patterning, bubble point generation during film transfer, poor flatness, poor mirror effect and the like occur during printing, and even print bubble layering can be caused during severe cases.

In this embodiment, since the content of free resin particles in the multi-layer wet paper sheet has been reduced in the foregoing steps, the precipitation phenomenon of resin particles on the surface of the press roll has been greatly alleviated.

Further, the free energy of the surface of the press roll surface sprayed with the press roll stripping agent is reduced, free resin particles in the multi-layer wet paper are difficult to adhere to the press roll surface, the reverse pulling force of the press roll on the multi-layer wet paper can be reduced, the stripping efficiency and stripping effect of the multi-layer wet paper and the press roll are improved, and therefore separation and generated appearance paper diseases among layers of the multi-layer wet paper are avoided, and the paper flatness and the final product quality are improved.

S37: and drying the pressed multilayer wet paper, and sizing the dried multilayer paper to obtain the multilayer composite paper.

In one specific implementation, the multi-layer composite paper to be prepared is a four-layer single-sided coated white cardboard, and after sizing the dried multi-layer paper, the coating is performed on only one side surface.

In another specific implementation, the multi-layer composite paper to be prepared is three-layer double-sided coated paper, and after sizing the dried multi-layer paper, both surfaces of the two sides are coated.

Accordingly, the present application provides a paper sheet prepared by the paper sheet preparation method of controlling resin deposition in the above embodiment.

Compared with the prior art, the paper provided by the embodiment has better flatness, lower printing surface roughness (PPS) and higher smoothness. Furthermore, the binding force between layers in the multilayer composite paper provided by the application is stronger, the surface is smooth, and the calendaring performance is good.

The following non-limiting examples are provided to facilitate an understanding of embodiments of the present application, which are further described in detail below.

Example 1

Respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond added with a first resin control agent to obtain mixed paper pulp corresponding to each fiber layer; wherein the first resin control agent is a nonionic dispersing agent, and the dosage is 0.5 ton/absolute dry slurry; wherein, the mixed paper pulp used for manufacturing the surface layer and the surface lining layer comprises NBKP and LBKP, the mass percentage of the NBKP is 15%, and the mass percentage of the LBKP is 15%; the mixed pulp for manufacturing the core layer comprises LBKP, BCTMP and damaged pulp, wherein the mass percentage of the LBKP is 25%, the mass percentage of the BCTMP is 60%, and the mass percentage of the damaged pulp is 15%; the mixed pulp used for preparing the bottom layer comprises NBKP and LBKP, wherein the mass percentage of NBKP is 20%, and the mass percentage of LBKP is 80%. The DCM extracts of LBKP used for both the top and bottom layers were 0.31%. The mixed pulp corresponding to each fiber layer is fed into a paper machine chest to which a second resin control agent is added. Wherein the second resin control agent is a cationic water-soluble polymer, the dosage is 0.8 ton/paper, the molecular weight is 63 ten thousand, and the charge density is 5.5meq/g. And (3) respectively flowing out the mixed paper pulp which is corresponding to each fiber layer and is adhered with the compound by utilizing a multilayer headbox in a paper machine pulp tank, and performing net surfing and forming to obtain the wet paper corresponding to each fiber layer. And sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper. The multi-layered wet paper sheet is pressed by a press roll coated with a third resin control agent, and the multi-layered wet paper sheet is peeled after the press is completed. Wherein the third resin control agent is a squeeze roll stripper in an amount of 8mL/min, the surface tension of the stock solution at 20 ℃ is 17mN/m, and the stripping force is 101gf (sample preparation with a dilution solution having a solid content of 0.5%). And drying the pressed multilayer wet paper, sizing the dried multilayer paper, and coating one side surface to obtain four layers of single-sided coated white cardboard.

Example 2

Respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond added with a first resin control agent to obtain mixed paper pulp corresponding to each fiber layer; wherein the first resin control agent is a nonionic dispersing agent, and the dosage is 0.4 ton/absolute dry slurry; wherein, the mixed paper pulp used for manufacturing the surface layer and the surface lining layer comprises NBKP and LBKP, the mass percentage of the NBKP is 15%, and the mass percentage of the LBKP is 15%; the mixed pulp for manufacturing the core layer comprises LBKP, BCTMP and damaged pulp, wherein the mass percentage of the LBKP is 25%, the mass percentage of the BCTMP is 60%, and the mass percentage of the damaged pulp is 15%; the mixed pulp used for preparing the bottom layer comprises NBKP and LBKP, wherein the mass percentage of NBKP is 20%, and the mass percentage of LBKP is 80%. The DCM extracts of LBKP used for both the top and bottom layers were 0.12%. The mixed pulp corresponding to each fiber layer is fed into a paper machine chest to which a second resin control agent is added. Wherein the second resin control agent is a cationic water-soluble polymer, the dosage is 0.6 ton/paper, the molecular weight is 63 ten thousand, and the charge density is 5.5meq/g. And (3) respectively flowing out the mixed paper pulp which is corresponding to each fiber layer and is adhered with the compound by utilizing a multilayer headbox in a paper machine pulp tank, and performing net surfing and forming to obtain the wet paper corresponding to each fiber layer. And sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper. The multi-layered wet paper sheet is pressed by a press roll coated with a third resin control agent, and the multi-layered wet paper sheet is peeled after the press is completed. Wherein the third resin control agent was a squeeze roll stripper in an amount of 4mL/min, the surface tension of the stock solution at 20℃was 17mN/m, and the stripping force was 101gf (sample preparation with a dilution solution having a solid content of 0.5%). And drying the pressed multilayer wet paper, sizing the dried multilayer paper, and coating one side surface to obtain four layers of single-sided coated white cardboard.

Control group 1

Respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond to obtain mixed paper pulp corresponding to each fiber layer; wherein, the mixed paper pulp used for manufacturing the surface layer and the surface lining layer comprises NBKP and LBKP, the mass percentage of the NBKP is 15%, and the mass percentage of the LBKP is 15%; the mixed pulp for manufacturing the core layer comprises LBKP, BCTMP and damaged pulp, wherein the mass percentage of the LBKP is 25%, the mass percentage of the BCTMP is 60%, and the mass percentage of the damaged pulp is 15%; the mixed pulp used for preparing the bottom layer comprises NBKP and LBKP, wherein the mass percentage of NBKP is 20%, and the mass percentage of LBKP is 80%. The DCM extract content of LBKP used for both the top and bottom layers was 0.29%. The mixed pulp corresponding to each fiber layer is fed into a pulp tank of a paper machine. And (3) respectively flowing out the mixed paper pulp corresponding to each fiber layer by utilizing a multi-layer headbox in the paper machine pulp tank, and performing net forming to obtain the wet paper corresponding to each fiber layer. And sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper. The multi-layered wet paper sheet is pressed by a press roll, and the multi-layered wet paper sheet is peeled after the press is completed. And drying the pressed multilayer wet paper, sizing the dried multilayer paper, and coating one side surface to obtain four layers of single-sided coated white cardboard.

For the four-layer single-sided coated white cardboard produced in examples 1 and 2 and control 1, parameters such as printing surface roughness (PPS), smoothness and flatness of the paper were tested, and the test results are shown in table 1:

TABLE 1

The PPS test reference method comprises the following steps: ISO8791-4; the smoothness test reference method comprises the following steps: ISO 5627; flatness data used OSDValue in L & W OptiTopo optical coarseness gauge. Wherein the front surface is a coated surface.

As can be seen from the above table, in examples 1 and 2, the printing surface roughness of the paper was decreased and both the flatness and smoothness were improved as compared with the control group 1, indicating that the flatness of the paper was improved, i.e., the deposition of the resin particles on the surface of the press roll was effectively reduced and the peeling effect of the paper from the press roll was improved by the synergistic use of the first resin control agent, the second resin control agent and the third resin control agent. Example 2 has significantly reduced amounts of the first resin control agent, the second resin control agent and the third resin control agent compared to example 1, indicating that the same effect can be achieved with reduced amounts of chemicals by using LBKP with smaller DCM extract content for the top and bottom layers.

Example 3

Respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond added with a first resin control agent to obtain mixed paper pulp corresponding to each fiber layer; wherein the first resin control agent is a nonionic dispersing agent, and the dosage is 0.5 ton/absolute dry slurry; wherein the mixed paper pulp for preparing the surface layer comprises NBKP and LBKP, the mass percentage of NBKP is 30%, and the mass percentage of LBKP is 70%; the mixed pulp for manufacturing the core layer comprises LBKP, BCTMP and damaged pulp, wherein the mass percentage of the LBKP is 45%, the mass percentage of the BCTMP is 35%, and the mass percentage of the damaged pulp is 20%; the mixed pulp used for preparing the bottom layer comprises NBKP and LBKP, wherein the mass percentage of NBKP is 30%, and the mass percentage of LBKP is 70%. The DCM extracts of LBKP used for both the top and bottom layers were 0.28%. The mixed pulp corresponding to each fiber layer is fed into a paper machine chest to which a second resin control agent is added. Wherein the second resin control agent is a cationic water-soluble polymer, the dosage is 0.7 ton/paper, the molecular weight is 63 ten thousand, and the charge density is 5.5meq/g. And (3) respectively flowing out the mixed paper pulp which is corresponding to each fiber layer and is adhered with the compound by utilizing a multilayer headbox in a paper machine pulp tank, and performing net surfing and forming to obtain the wet paper corresponding to each fiber layer. And sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper. The multi-layered wet paper sheet is pressed by a press roll coated with a third resin control agent, and the multi-layered wet paper sheet is peeled after the press is completed. Wherein the third resin control agent is a squeeze roll stripper in an amount of 5mL/min, the surface tension of the stock solution at 20 ℃ is 17mN/m, and the stripping force is 101gf (sample preparation with a dilution solution having a solid content of 0.5%). And drying the pressed multilayer wet paper, sizing the dried multilayer paper, and coating the surfaces of two sides to obtain the three-layer double-sided coated paper.

Control group 2

Respectively mixing a plurality of slurries of each fiber layer in a mixed slurry pond to obtain mixed paper pulp corresponding to each fiber layer; wherein the mixed paper pulp for preparing the surface layer comprises NBKP and LBKP, the mass percentage of NBKP is 30%, and the mass percentage of LBKP is 70%; the mixed pulp for manufacturing the core layer comprises LBKP, BCTMP and damaged pulp, wherein the mass percentage of the LBKP is 45%, the mass percentage of the BCTMP is 35%, and the mass percentage of the damaged pulp is 20%; the mixed pulp used for preparing the bottom layer comprises NBKP and LBKP, wherein the mass percentage of NBKP is 30%, and the mass percentage of LBKP is 70%. The DCM extracts of LBKP used for both the top and bottom layers were 0.25%. The mixed pulp corresponding to each fiber layer is fed into a pulp tank of a paper machine. And (3) respectively flowing out the mixed paper pulp corresponding to each fiber layer by utilizing a multi-layer headbox in the paper machine pulp tank, and performing net forming to obtain the wet paper corresponding to each fiber layer. And sequentially compounding the wet paper corresponding to the fiber layers to obtain the multi-layer wet paper. The multi-layered wet paper sheet is pressed by a press roll, and the multi-layered wet paper sheet is peeled after the press is completed. And drying the pressed multilayer wet paper, sizing the dried multilayer paper, and coating the surfaces of two sides to obtain the three-layer double-sided coated paper.

For the three-layer double-sided coated papers produced in example 3 and comparative group 2, parameters such as printing surface roughness (PPS), smoothness and flatness of the papers were tested, and the test results are shown in table 2:

TABLE 2

Wherein the front and the back are coated two side surfaces.

As can be seen from the above table, in example 3, the printing surface roughness of the paper was decreased and both the flatness and smoothness were improved as compared with the control group 2, indicating that the flatness of the paper was improved, i.e., the deposition of the resin particles on the surface of the press roll was effectively reduced and the peeling effect of the paper from the press roll was improved by the synergistic use of the first resin control agent, the second resin control agent and the third resin control agent.

Microscopic topographical features of the multilayered papers in example 3 and control group 2 were observed with a Scanning Electron Microscope (SEM). Specifically, referring to fig. 4a and 4b, fig. 4a and 4b are SEM images of the multi-layered paper in the embodiment 3 and the control group 2, respectively.

As can be seen from fig. 4a and fig. 4b, the delamination phenomenon of the multi-layered paper in example 3 is not obvious, and the delamination phenomenon of the multi-layered paper in the control group 2 is obvious, which indicates that the counter pulling force of the press roll on the multi-layered wet paper can be reduced by the cooperative use of the first resin control agent, the second resin control agent and the third resin control agent, and the peeling efficiency and peeling effect of the multi-layered wet paper and the press roll can be improved, thereby avoiding the separation and the appearance paper diseases generated between the layers of the multi-layered wet paper, and further improving the paper flatness and the final product quality.

Unlike available technology, the present application has the first resin controlling agent added to the mixed pulp pond to disperse the resin grains in the mixed pulp and to make the dispersed resin grains exist stably in the pulp system. By adding the second resin control agent to the paper machine chest, the second resin control agent can be used to react with the dispersed resin particles to form a composite, so that the content of free resin particles in the wet paper is reduced, and the possibility of depositing the resin particles on the surface of the press roll is reduced. Further, by spraying the third resin control agent on the surface of the press roll, the surface free energy of the press roll surface can be reduced by the third resin control agent, making it difficult for the free resin particles to adhere to the press roll surface. According to the application, through the cooperative use of the first resin control agent, the second resin control agent and the third resin control agent, the deposition of free resin particles on the surface of the press roller can be reduced, and the stripping effect of paper and the press roller is improved, so that the paper flatness is improved, and the product quality is improved.

The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application or directly or indirectly applied to other related technical fields are included in the scope of the present application.

Claims

1. A method of producing a paper sheet for controlling resin deposition, comprising:

mixing a plurality of pulps in a mixing chest to obtain a mixed pulp; wherein, a first resin control agent is added in the mixing pulp tank and is used for dispersing resin particles in the mixed pulp;

feeding the mixed paper pulp into a paper machine pulp tank, flowing out the mixed paper pulp by using the paper machine pulp tank, and forming on a net to obtain wet paper; wherein a second resin control agent is added in the paper machine pulp tank, and the second resin control agent is used for reacting with the dispersed resin particles so as to reduce the content of free resin particles in the wet paper;

squeezing the wet paper by using a squeezing roller, and stripping the wet paper after the squeezing is completed; and the surface of the pressing roll is sprayed with a third resin control agent, and the third resin control agent is used for reducing the deposition of the free resin particles on the surface of the pressing roll.

2. The method for producing paper according to claim 1, wherein,

the first resin control agent comprises a surfactant, and the addition amount of the surfactant is 0.2-0.8 ton/absolute dry slurry;

The step of mixing a plurality of pulps in a mixing chest to obtain a mixed pulp, comprising:

mixing a plurality of pulps in a mixing chest to which the surfactant is added to obtain mixed pulp;

after the step of mixing the plurality of pulps in the mixing chest to obtain a mixed pulp, the method comprises the steps of:

the mixed pulp is fed to the machine chest by means of a pump and a pressure screen, so that the surfactant disperses the resin particles by means of the shearing action of the pump and the pressure screen.

3. The method for producing paper according to claim 2, wherein,

the surfactant comprises a non-discrete dispersing agent, wherein the non-discrete dispersing agent comprises a lipophilic group and a hydrophilic group; wherein the lipophilic group has a carbon chain length of 12 to 16 carbon atoms.

4. The method for producing paper according to claim 1, wherein,

the second resin control agent comprises a cationic water-soluble polymer, and the addition amount of the cationic water-soluble polymer is 0.4-1.0 ton/paper;

the step of feeding the mixed pulp into a paper machine pulp tank, flowing the mixed pulp out by using the paper machine pulp tank and forming the mixed pulp on a net to obtain wet paper comprises the following steps:

Feeding the mixed pulp into the paper machine chest added with the cationic water-soluble polymer so as to enable the cationic water-soluble polymer to react with the dispersed resin particles to obtain a compound attached to the surface of the fiber;

and (3) flowing out the mixed paper pulp attached with the compound by using the paper machine pulp pool and screening and forming to obtain the wet paper.

5. The method for producing paper according to claim 4, wherein,

said step of feeding said mixed pulp into said machine chest to which said cationic water-soluble polymer is added so as to react said cationic water-soluble polymer with said dispersed resin particles to obtain a composite adhered to the surface of the fiber, comprising, before:

preparing the cationic water-soluble polymer and clear water; wherein the mass ratio of the cationic water-soluble polymer to the clear water is 1:20-100;

mixing the cationic water-soluble polymer and the clear water according to the raw material proportion and uniformly stirring;

and adding diluted cationic water-soluble polymer into the paper machine pulp tank.

6. The method for producing paper according to claim 5, wherein,

The molecular weight of the cationic water-soluble polymer is 30-70 ten thousand, and the charge density is 2.5-6.5 meq/g.

7. The method for producing paper according to claim 1, wherein,

the third resin control agent comprises a squeeze roll stripper, and the dosage of the squeeze roll stripper is 2-8 mL/min;

the step of pressing the wet paper sheet with a press roll and peeling the wet paper sheet after the press is completed, comprises:

and pressing the wet paper by using the press roll coated with the press roll stripping agent, and stripping the wet paper after the pressing is completed.

8. The method for producing paper according to claim 7, wherein,

the squeeze roller stripper is an aqueous emulsion composed of organic silicon and synthetic esters.

9. The method for producing paper according to claim 1, wherein,

the prepared paper is multi-layer composite paper;

respectively mixing the multiple pulps of each fiber layer in the mixed pulp pool added with the surfactant to obtain mixed pulp corresponding to each fiber layer;

delivering the mixed pulp corresponding to each fiber layer to the paper machine pulp pool by using a pump and a pressure screen, so that the surfactant disperses the resin particles by the shearing action of the pump and the pressure screen;

feeding the mixed pulp corresponding to each fiber layer into the paper machine pulp tank added with the cationic water-soluble polymer so as to enable the cationic water-soluble polymer to react with the dispersed resin particles to obtain a compound attached to the surface of the fiber;

respectively flowing out and net-forming the mixed paper pulp attached with the compound corresponding to each fiber layer by utilizing a multilayer flow box in the paper machine pulp pool to obtain wet paper corresponding to each fiber layer;

sequentially compounding the wet paper corresponding to the fiber layers to obtain a plurality of layers of wet paper;

Squeezing the multi-layer wet paper by using the squeezing roller sprayed with the squeezing roller stripping agent, and stripping the multi-layer wet paper after the squeezing is completed;

and drying the pressed multilayer wet paper, and sizing the dried multilayer paper to obtain the multilayer composite paper.

10. A paper, characterized in that the paper is produced by the paper production method for controlling resin deposition according to any one of claims 1 to 9.