Production method of folding-resistant body paper and folding-resistant body paper thereof

Abstract

The invention discloses a production method of folding-resistant base paper and the folding-resistant base paper. The production method comprises the following steps: mixing wood pulp, calcium carbonate filler, steamed cationic starch and a sizing agent to obtain mixed pulp; purifying and deslagging the mixed pulp to obtain pre-pulp; adding uncooked cationic starch, hydrophobic modified starch and a dry strength agent into the primary pulp, and mixing to obtain primary pulp; the method comprises the following steps of: screening the primary pulp, carrying out on-line treatment after the screening treatment, and drying after the on-line treatment. According to the mode, the uncooked cationic starch and the hydrophobic modified starch are added before drying, so that the ungelatinized cationic starch is gelatinized by utilizing a subsequent drying process, and then the gelatinized cationic starch and the hydrophobic modified starch form a net-shaped structure, so that the strength and cohesive force of the raw paper can be improved; further, the folding resistance frequency of the raw paper is improved.

Description

Technical Field

[0001] The present application relates to the technical field of papermaking, and in particular to a production method of fold-resistant base paper and the fold-resistant base paper. Background Art

[0002] With the development of the papermaking industry, the requirements for base paper have also increased, especially in some industries, the strength and folding endurance of base paper are higher than those of paper used in other industries, such as playing card paper in the entertainment industry. In the existing technology, to improve the strength and folding endurance of base paper, the generally used means include reducing ash content, increasing the amount of long fibers, reducing pulping freeness, increasing auxiliary pulping chemicals, increasing the amount of cationic starch added, etc., or using the stiffness and strength of the composite glue itself to reinforce during subsequent compounding to improve the cohesion of the paper.

[0003] However, the lifting range and space of the base paper made by the above means are limited, and excessive adjustment will also lead to difficulties in dehydration, resulting in serious problems such as web sticking, paper breakage, and machine pulling. The finished product is also difficult to meet the requirements of high folding resistance and high strength for base paper such as playing cards. Summary of the invention

[0004] The embodiments of the present application provide a method for producing fold-resistant base paper and the fold-resistant base paper thereof, which can utilize the papermaking method of the present application to improve the cohesion of the paper, thereby improving its strength and folding times.

[0005] In a first aspect, an embodiment of the present application provides a method for producing fold-resistant base paper, comprising:

[0006] Mixing wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent to obtain mixed pulp;

[0007] Purifying and removing slag from the mixed pulp to obtain pre-pulp;

[0008] Adding uncooked cationic starch, hydrophobically modified starch and a dry strength agent into the pre-slurry to obtain the original slurry;

[0009] The raw pulp is subjected to screening treatment, and then subjected to screen processing, and then subjected to drying.

[0010] In some embodiments, the uncooked cationic starch is used in an amount of 40-50 kg / t paper, the hydrophobically modified starch is used in an amount of 5-8 kg / t paper, and the dry strength agent is used in an amount of 5-20 kg / t paper.

[0011] In some embodiments, the step of adding uncooked cationic starch, hydrophobically modified starch and a dry strength agent to the pre-slurry to obtain a raw slurry comprises: first mixing the uncooked cationic starch with the hydrophobically modified starch, adding water to disperse the mixture to obtain a starch slurry, and adding the starch slurry and the dry strength agent to the pre-slurry.

[0012] In some embodiments, in the step of first mixing the uncooked cationic starch with the hydrophobically modified starch and then adding water to disperse the mixture, the dispersion ratio of the uncooked cationic starch to the hydrophobically modified starch is in the range of [7.5-9.5]:[0.5-2], the solid content of the starch slurry is 25-35%, and the absolute dry weight of the starch slurry is 40-52 kg.

[0013] In some embodiments, after the step of drying after the web-surface treatment, the steps further include: performing a surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain a semi-base paper, and performing off-machine coating on the semi-base paper to obtain a finished base paper;

[0014] The off-machine coating steps include: primer coating, top coating and back sizing.

[0015] In some embodiments, the coating amount of the primer is 8-12 g / m 2 The coating amount of the top coating is 10-12g / m 2 The amount of glue applied to the back side is 1-3 g / m 2 The solid content of the coating used for the primer and the topcoat is 66-68%.

[0016] In some embodiments, the wood pulp includes softwood pulp and hardwood pulp.

[0017] In some embodiments, the mass percentage of the coniferous wood pulp is 20-30%, the mass percentage of the hardwood pulp is 70-80%, the mass percentage of the calcium carbonate filler is 6-10%, the amount of the cationic starch after cooking is 9-11 kg / t paper; the amount of the sizing agent is 8.5-11.5 kg / t paper.

[0018] In some embodiments, the web surfing process includes: adjusting the web surfing flow, controlling the scanned paper weight to be between 120-123 g / m 2 between.

[0019] In a second aspect, an embodiment of the present application provides a fold-resistant base paper, which is prepared by the production method described above.

[0020] The beneficial effect of the present application is that the present application adds uncooked cationic starch and hydrophobically modified starch before drying, so that the ungelatinized cationic starch is gelatinized during the subsequent drying process, and then a network structure is formed with the hydrophobically modified starch, so that the strength and cohesion of the base paper can be improved, thereby improving the folding endurance of the base paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 It is a flow chart of an embodiment of the method for producing folding-resistant base paper of the present application;

[0023] Figure 2 is a flow chart of another embodiment of the method for producing folding-resistant base paper of the present application;

[0024] Figure 3 It is a flow chart of another embodiment of the method for producing folding-resistant base paper of the present application;

[0025] Figure 4 It is a flow chart of another embodiment of the method for producing folding-resistant base paper of the present application;

[0026] Figure 5 It is a simplified structural schematic diagram of an embodiment of a production system of fold-resistant base paper of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] This embodiment provides the following Figure 1 A method for producing folding-resistant base paper is shown, comprising:

[0029] Step S100, mixing wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent to obtain a mixed pulp;

[0030] Step S200, purifying and removing slag from the mixed pulp to obtain pre-pulp;

[0031] Step S300, adding uncooked cationic starch, hydrophobically modified starch and dry strength agent into the pre-slurry to obtain raw slurry;

[0032] Step S400, screening the raw pulp, putting it on a screen after the screening, and drying it after the screen.

[0033] First, the steps in the above production method are introduced:

[0034] In step S100 of this embodiment, wood pulp is one of the main raw materials for papermaking, generally including long-fiber wood pulp and short-fiber wood pulp, and the purpose is to provide a fiber basis for paper. Calcium carbonate filler is used to improve the optical properties of paper and improve the physical properties of paper, such as increasing the opacity and whiteness of paper, and increasing the softness and compactness of paper. Cationic starch after cooking is a necessary factor to help the forming of paper, and can also improve the strength of paper. Specifically, the positive charge carried by cationic starch can produce adsorption with the fiber surface with negative charge. This adsorption promotes the close combination between fibers, thereby enhancing the strength of paper, and the particles of cationic starch can fill the gaps and pores of paper, thereby making the structure of paper more compact, and can also reduce the phenomenon of hair loss and powder loss of paper. Sizing agent is used to improve the physical properties of paper, such as paper strength, surface smoothness, surface flatness and water resistance, and can shorten the time of paper forming.

[0035] In step S200 of this embodiment, the mixed pulp is purified and deslagging is performed to obtain pre-slurry, the main purpose of which is to remove slag and impurities in the mixed pulp and improve the flatness and fineness of the subsequent formed paper.

[0036] In step S300 of this embodiment, the purpose of adding uncooked cationic starch, hydrophobically modified starch and dry strength agent is to improve the quality of base paper to a higher strength and further improve the number of folding times of paper while ensuring the formation of paper. This step is a key step in this application. Uncooked cationic starch is different from cooked cationic starch. The cooked cationic starch has become gelatinized. It is added in step S100 to ensure that the paper can be formed. The uncooked cationic starch added in step S300 is added to the pre-slurry in powder form because it is not cooked. It is spontaneously gelatinized through the drying step in the subsequent papermaking process, and can be mixed with the relatively large particles of hydrophobically modified starch to form a network structure to improve the strength. The addition of dry strength agent is to improve dehydration and increase the drying speed and strength of paper.

[0037] In step S400 of this embodiment, the pulp still needs to be screened to ensure that the residue or impurities generated after the two additions of raw materials are removed, thereby ensuring that the subsequent paper forming can obtain a higher flatness and density. The web treatment is the initial stage of converting the pulp into paper, by evenly spraying or spreading the pulp onto the forming web of the paper machine to form a thin layer of wet paper, and then entering the drying step to form the paper.

[0038] In one example of this embodiment, as shown in the attached Figure 2 As shown, the wood pulp in step S100 includes coniferous wood pulp and broadleaf wood pulp. Coniferous wood pulp is long-fiber wood pulp, and broadleaf wood pulp is short-fiber wood pulp. The two are mixed to complete the pulping of fiber raw materials in paper.

[0039] In one example of this embodiment, further as shown in the attached Figure 2 As shown, before step S100, it also includes:

[0040] Step S01, respectively, the long fiber pulp and the short fiber pulp in the wood pulp are subjected to process processes such as crushing, screening, dispersion, bleaching, and refining to obtain long fiber pulp and short fiber pulp respectively. Among them, the freeness (CSF) of the long fiber pulp can be controlled at 320-380ml, and the freeness (CSF) of the short fiber pulp can be controlled at 330-400ml. CSF is Canadian Standard Freeness. Further, the freeness of the long fiber pulp can be controlled to 320ml, 350ml, 360ml or 380ml, and the freeness of the short fiber pulp can be controlled to 330ml, 350ml, 360ml or 400ml.

[0041] In one example of this embodiment, step S100 is optimized, the mass percentage of coniferous pulp is set to 20-30%, the mass percentage of hardwood pulp is set to 70-80%, the mass percentage of calcium carbonate filler is set to 6-10%, the amount of cationic starch after cooking is 9-11kg / t paper; the amount of sizing agent is 8.5-11.5kg / t paper. Further, the sizing agent in this application can use AKD Alkyl Ketene Dimer. Among them, the mass percentage of coniferous pulp can be set to 20%, 25%, or 30%. The mass percentage of hardwood pulp can be set to 70%, 75% or 80%. The mass percentage of calcium carbonate filler can be set to 6%, 8% or 10%. The amount of cationic starch after cooking can be set to 9g / t paper, 10g / t paper or 11g / t paper. The amount of sizing agent can be set to 8.5kg / t paper, 10kg / t paper or 11.5kg / t paper. Furthermore, the ash content of the calcium carbonate filler can be controlled to be around 7-8%, which can be 7%, 8% or 9%, and in a specific embodiment can be 8%.

[0042] In one example of this embodiment, the purification and slag removal in step S200 is set as: purification and slag removal is achieved by a conical purifier.

[0043] In one example of this embodiment, step S300 is optimized, and the amount of uncooked cationic starch is set to 40-50 kg / t paper, the amount of hydrophobically modified starch is set to 5-8 kg / t paper, and the amount of dry strength agent is set to 5-20 kg / t paper. The amount of uncooked cationic starch can be set to 40 kg / t paper, 45 kg / t paper, or 50 kg / t paper. The amount of hydrophobically modified starch can be set to 5 kg / t paper, 6 kg / t paper, 7 kg / t paper, or 8 kg / t paper. The amount of dry strength agent can be set to 5 kg / t paper, 15 kg / t paper, or 20 kg / t paper.

[0044] In one example of this embodiment, as shown in the attached Figure 3 As shown, step S300 is optimized, specifically, the step of adding uncooked cationic starch, hydrophobically modified starch and dry strength agent to the pre-slurry to obtain the original slurry comprises:

[0045] Step S301, firstly mix the uncooked cationic starch with the hydrophobically modified starch, add water to disperse after mixing, obtain starch slurry, add starch slurry and dry strength agent to the pre-slurry. The purpose of this step is to ensure that the uncooked cationic starch can be preliminarily mixed with the hydrophobically modified starch first, so as to ensure that the two are fully contacted in the subsequent drying and form a network structure.

[0046] In one example of this embodiment, step S301 is optimized, and in the step of first mixing uncooked cationic starch with hydrophobically modified starch, and then adding water for dispersion, the dispersion ratio of uncooked cationic starch to hydrophobically modified starch is set to [7.5-9.5]:[0.5-2], and the solid content of the starch slurry is 25-35%. Among them, the dispersion ratio range can be 7.5:0.5, 8:1 or 9.5:2, and in a specific embodiment it can be 8:1, that is, one part of uncooked cationic starch and two parts of hydrophobically modified starch. The solid content of the starch slurry can be set to 25%, 30% or 35%. Furthermore, the absolute dry weight of the starch slurry (usually refers to the absolute dry matter content of paper, which is a relative concept used to describe the proportion of dry matter in paper after removing water) can be set between 40-52 kg, for example, set to 40 kg, 45 kg or 52 kg, and the specific ratio of uncooked cationic starch and hydrophobically modified starch contained therein can be set with reference to the above-mentioned dispersion ratio range.

[0047] Furthermore, the dry strength agent of the present application may use cationic GPAM (Glyoxalated Polyacrylamide).

[0048] In one embodiment, the screening process in step S400 is performed by using a pressure screen.

[0049] In one embodiment, the online processing of step S400 includes: adjusting the online flow rate, controlling the scanned paper weight to be 120-123 g / m 2 That is, before the subsequent gluing (step S500), the scanned paper sheet quantitative processing needs to be performed to carry out the subsequent quantitative production, and the scanned paper sheet quantitative can be set to 120g / m 2 , 122g / m 2 or 123g / m 2 .

[0050] In one embodiment, the web processing method of step S400 is: web processing through a headbox.

[0051] In one example of this embodiment, as shown in the attached Figure 4 As shown, after step S400, that is, after the step of drying after the web processing, the following steps are also included:

[0052] S500, performing surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain semi-base paper, and performing off-machine coating on the semi-base paper to obtain finished base paper;

[0053] Among them, the steps of off-machine coating include: primer coating, top coating and back sizing treatment.

[0054] In one example of this embodiment, step S500 is optimized to set the coating amount of the primer to 8-12 g / m 2 The coating amount of the top coating is 10-12g / m 2 The amount of glue applied to the back side is 1-3g / m 2 Among them, the coating amount of the primer can be selected as 8g / m 2 , 10g / m 2 or 12g / m 2 The coating amount of the top coating can be 10g / m 2 , 11g / m 2 or 12g / m 2 The glue application amount can be 1g / m 2 , 2g / m 2 or 3g / m 2 Furthermore, the total coating amount of the primer and topcoat can be controlled within 18-24g / m 2 For example, it can be controlled at 18g / m 2 , 23g / m 2 or 24g / m 2 In addition, the solid content of the coating can be controlled between 66% and 68%, for example, 66%, 67% or 68%.

[0055] In one example of this embodiment, step S500 is further optimized, and the coating for the topcoat or topcoat includes ultrafine calcium carbonate, ultrafine porcelain clay, SBL latex (styrene-butadiene latex, which is a stable emulsion formed by low-temperature polymerization of butadiene and styrene) and WEB latex. WEB latex is a special latex for rotary coated paper. By using this latex, the porosity of the coating can be better after coating and film formation.

[0056] Among them, the ultrafine porcelain clay can be an ultrafine porcelain clay with a diameter of 2μm and a particle content of more than 98%. Further, in one of the examples, ultrafine calcium carbonate is set to 79-82 parts, ultrafine porcelain clay is set to 18-24 parts, SBL latex is set to 9-12 parts, and WEB latex is set to 1-3 parts. In a specific embodiment, ultrafine calcium carbonate can be set to 79 parts, 80 parts or 82 parts, specifically 80 parts. Ultrafine porcelain clay can be set to 18 parts, 20 parts or 24 parts, and in a specific embodiment, it can be 20 parts. SBL latex can be set to 9 parts, 10 parts or 12 parts, and in a specific embodiment, it can be 10 parts. WEB latex can be set to 1 part, 2 parts or 3 parts, and in a specific embodiment, it can be 2 parts.

[0057] In one example, the basis weight (weight per unit area) of the finished base paper produced by the above method is 125-155 g / m 2 and the thickness is between 150-162μm.

[0058] In one embodiment of the present application, a fold-resistant base paper is further provided. The fold-resistant base paper is prepared by the production method of any one or more combinations of the above embodiments.

[0059] Secondly, some application descriptions and embodiments of the technology of the present application in the production and manufacturing of playing cards are provided below for those skilled in the art to understand. It should be noted that the fold-resistant base paper of the present application is not limited to application in playing cards, for example, book printing paper, packaging paper, map making paper, notebook paper, etc., which have high requirements on the strength and folding frequency of paper, and the technical solution of the present application can also be used.

[0060] First, let's introduce the existing paper for playing cards. The quality requirements for playing cards are mainly the number of folding resistance, opacity, interlayer bonding strength, stiffness, etc. The purpose is to increase the number of uses, prevent cheating by light transmission, and improve the application feel. The folding resistance of ordinary playing cards is generally about 500 times, and the interlayer bonding strength is about 300J / m 2 The production of playing cards requires gluing to increase their strength. For example, the production method of black core playing cards uses about 5 grams of glue. Such a small amount of glue does not have a significant impact on the folding resistance and interlayer bonding strength of the playing card paper, which still requires base paper. Generally speaking, the interlayer bonding strength of about 150 grams of single-sided coated paper is 250-300 J / m 2 about.

[0061] The following provides specific examples for further explanation:

[0062] In one embodiment of the present application, the production method provided comprises the following steps:

[0063] Step S01, respectively subjecting the long fiber pulp and the short fiber pulp in the wood pulp to process processes such as crushing, screening, dispersion, bleaching, and refining to obtain long fiber pulp and short fiber pulp, respectively; wherein, the long fiber pulp is coniferous pulp, and the short fiber pulp is broadleaf pulp, and the ratio of coniferous pulp to broadleaf pulp is 20:80; the freeness of the long fiber pulp is controlled to be 360ml, and the freeness of the short fiber pulp is controlled to be 350ml.

[0064] Step S100, wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent are selected and mixed to obtain a mixed pulp; wherein the ash content of the filler is controlled at 8%. In addition, a retention aid can be added according to actual needs for papermaking of playing cards. It should be noted that in any embodiment of the present application, the addition of the retention aid can be selected according to actual papermaking needs, or the retention aid can be selected not to be added.

[0065] Step S200, purifying and removing slag from the mixed pulp to obtain pre-pulp.

[0066] Step S301, firstly mix the uncooked cationic starch and the hydrophobically modified starch, add water to disperse them after mixing to obtain starch slurry, add the starch slurry and the dry strength agent to the pre-slurry to obtain the original slurry; wherein, the solid content of the starch slurry is controlled at 30%, the absolute dry weight of the starch slurry is set to 45kg, the dispersion ratio is 8:1, that is, the uncooked cationic starch is eight parts, the hydrophobically modified starch is 1 part, and the amount of the added dry strength agent is 15kg / t paper.

[0067] Step S400, screening the raw pulp, putting it on a screen after the screening, and drying it after the screen.

[0068] S500, performing surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain semi-base paper, and performing off-machine coating on the semi-base paper to obtain finished base paper;

[0069] The off-machine coating step includes: primer coating, top coating and back sizing. Specifically, the total coating amount of primer and top coating is controlled to be 23g / m 2 The coating includes 80 parts of ultrafine calcium carbonate, 20 parts of ultrafine porcelain clay with a 2μm particle content of more than 98%, 10 parts of SBL latex and 2 parts of WEB latex. The solid content of the coating is 66-68%. The amount of sizing applied to the back side is 1.5-2.0g / m 2 .

[0070] Furthermore, the base paper obtained by papermaking according to the above steps has a basis weight of 120 g / m 2 , thickness is 150-155μm. After subsequent super calendering and finishing, the basis weight is controlled to be 145g / m 2 , thickness is 148-152μm, glossiness is 40-50%, and interlayer bonding strength can reach 530-600J / m 2 , you can get playing card paper with high inter-layer bonding strength and high folding resistance.

[0071] In another embodiment of the present application, a production method is provided comprising the following steps:

[0072] Step S01, respectively subjecting the long fiber pulp and the short fiber pulp in the wood pulp to process processes such as crushing, screening, dispersion, bleaching, and refining to obtain long fiber pulp and short fiber pulp, respectively; wherein, the long fiber pulp is coniferous pulp, and the short fiber pulp is broadleaf pulp, and the ratio of coniferous pulp to broadleaf pulp is 25:75; the freeness of the long fiber pulp is controlled to be 350ml, and the freeness of the short fiber pulp is controlled to be 360ml.

[0073] Step S100, wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent are selected and mixed to obtain a mixed pulp; wherein the ash content of the filler is controlled at 8%. In addition, a retention aid can be added according to actual needs for papermaking of playing cards. It should be noted that in any embodiment of the present application, the addition of the retention aid can be selected according to actual papermaking needs, or the retention aid can be selected not to be added.

[0074] Step S200, purifying and removing slag from the mixed pulp to obtain pre-pulp.

[0075] Step S301, firstly mix the uncooked cationic starch and the hydrophobically modified starch, add water to disperse them after mixing to obtain starch slurry, add the starch slurry and the dry strength agent to the pre-slurry to obtain the original slurry; wherein, the solid content of the starch slurry is controlled at 30%, the absolute dry weight of the starch slurry is set to 52kg, the dispersion ratio is 8:1, that is, the uncooked cationic starch is eight parts, the hydrophobically modified starch is 1 part, and the amount of the added dry strength agent is 15kg / t paper.

[0076] Step S400, screening the raw pulp, putting it on a screen after the screening, and drying it after the screen.

[0077] S500, performing surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain semi-base paper, and performing off-machine coating on the semi-base paper to obtain finished base paper;

[0078] The off-machine coating steps include: primer coating, top coating and back sizing. Specifically, the total coating amount of primer and top coating is controlled to be 23g / m 2 The coating includes 80 parts of ultrafine calcium carbonate, 20 parts of ultrafine porcelain clay with a 2μm particle content of more than 98%, 10 parts of SBL latex and 2 parts of WEB latex. The solid content of the coating is 66-68%. The amount of sizing applied to the back side is 1.5-2.0g / m 2 .

[0079] Furthermore, the base paper obtained by papermaking according to the above steps has a basis weight of 125 g / m 2 , thickness is 150-160μm. After subsequent super calendering and finishing, the basis weight is controlled to be 150g / m 2, thickness is 150-155μm, glossiness is 40-50%, interlayer bonding strength can reach 530-600J / m 2 , you can get playing card paper with high inter-layer bonding strength and high folding resistance.

[0080] In another embodiment of the present application, a production method is provided comprising the following steps:

[0081] Step S01, respectively subjecting the long fiber pulp and the short fiber pulp in the wood pulp to process processes such as crushing, screening, dispersion, bleaching, and refining to obtain long fiber pulp and short fiber pulp, respectively; wherein, the long fiber pulp is coniferous pulp, and the short fiber pulp is broadleaf pulp, and the ratio of coniferous pulp to broadleaf pulp is 30:70; the freeness of the long fiber pulp is controlled to be 350ml, and the freeness of the short fiber pulp is controlled to be 360ml.

[0082] Step S100, wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent are selected and mixed to obtain a mixed pulp; wherein the ash content of the filler is controlled at 10%. In addition, a retention aid can be added according to actual needs for the papermaking requirements of playing card paper. It should be noted that in any embodiment of the present application, the addition of the retention aid can be selected according to the actual papermaking requirements, or the retention aid can be selected not to be added.

[0083] Step S200, purifying and removing slag from the mixed pulp to obtain pre-pulp.

[0084] Step S301, firstly mix the uncooked cationic starch and the hydrophobically modified starch, add water to disperse them after mixing to obtain starch slurry, add the starch slurry and the dry strength agent to the pre-slurry to obtain the original slurry; wherein, the solid content of the starch slurry is controlled at 30%, the absolute dry weight of the starch slurry is set to 50.6 kg, the dispersion ratio is 8:1, that is, the uncooked cationic starch is eight parts, the hydrophobically modified starch is 1 part, and the amount of the added dry strength agent is 20 kg / t paper.

[0085] Step S400, screening the raw pulp, putting it on a screen after the screening, and drying it after the screen.

[0086] S500, performing surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain semi-base paper, and performing off-machine coating on the semi-base paper to obtain finished base paper;

[0087] The off-machine coating step includes: primer coating, top coating and back sizing. Specifically, the total coating amount of primer and top coating is controlled to be 25g / m 2The coating includes 80 parts of ultrafine calcium carbonate, 20 parts of ultrafine porcelain clay with a 2μm particle content of more than 98%, 10 parts of SBL latex and 2 parts of WEB latex. The solid content of the coating is 66-68%. The amount of sizing applied to the back side is 1.5-2.0g / m 2 .

[0088] Furthermore, the base paper obtained by papermaking according to the above steps has a basis weight of 132 g / m 2 The thickness is 157-162μm. After subsequent super calendering, the basis weight is controlled to be 160g / m 2 , thickness is 155-160μm, glossiness is 40-50%, interlayer bonding strength can reach 530-600J / m 2 , you can get playing card paper with high inter-layer bonding strength and high folding resistance.

[0089] In another embodiment of this embodiment, a production system using the above production method is provided, as shown in the attached Figure 5 As shown, including the following connected in sequence:

[0090] The pulp mixing box 10 is connected to the output ends of the long fiber wood pulp (LBKP) and the short fiber wood pulp (NBKP) respectively, and is used to mix the long fiber wood pulp and the short fiber wood pulp, and to add calcium carbonate filler;

[0091] Mechanical box 20: connected with a mechanism for cooking cationic starch, used to receive the slurry output from the slurry mixing box 10 and add the cooked cationic starch into the interior;

[0092] The first slurry pump 30 is arranged between the mechanical box 20 and the white water tank 40, and a sizing agent (AKD) adding end can be added between the mechanical box 20 and the first slurry pump 30 for adding sizing agent; the purpose of this arrangement is to accelerate the mixing degree of the aforementioned additives by shaking the slurry during the pumping process of the slurry pump itself, so that the aforementioned added cooked cationic starch and sizing agent can be fully mixed to accelerate the forming of the pulp.

[0093] White water tank 40: used to buffer the aforementioned slurry, perform static treatment, buffer the speed of the slurry, and wait for subsequent transportation to machines in other production links;

[0094] The second slurry pump 50 is used to pump the slurry in the white water tank 40 to the subsequent purification and slag removal process, and further accelerate the mixing degree of the aforementioned additives by shaking the slurry during the pumping process of the slurry pump itself;

[0095] Conical purifier 60: connected to a control mechanism 601, used to purify and remove slag from the pulp pumped by the second slurry pump 50;

[0096] The third slurry pump 70 is provided with an addition end for starch slurry mixed with uncooked cationic starch and hydrophobically modified starch, and an addition end for dry strength agent GPAM between the third slurry pump 70 and the conical clarifier 60; after the starch slurry and dry strength agent are mixed, the slurry is shaken by the pumping process of the third slurry pump itself to further improve the mixing degree of the aforementioned additives, so that it can be uniformly gelatinized later.

[0097] The pressure screen 80 is used to screen the slurry pumped by the third slurry pump 70 to make the slurry more uniform and fine.

[0098] Headbox 90: used for processing the pulp on the screen, i.e., for the final forming and drying work. The drying cylinder in the rear stage can dry the pulp layer after being put on the screen and gelatinize the uncooked cationic starch to form a network structure with the hydrophobic modified starch with larger particles, thereby improving the strength of the base paper after forming.

[0099] In addition, in this embodiment, a fourth slurry pump 100 may be further provided between the slurry mixing box 10 and the mechanical box 20, and its effect is also to help further rapid mixing of the slurry through its own pumping process.

[0100] This application refers to the above preparation method to prepare three sets of finished playing cards as examples, and provides the quality comparison results of the examples and the control group as shown in the following table:

[0101]

[0102] Table 1: Quality comparison results of the embodiment and the control group.

[0103] As shown in the above table, the present application provides three groups of embodiments, including Embodiment 1, Embodiment 2 and Embodiment 3, and provides a control group, which is specifically a playing card made of white kraft paper that is coated on one side and then further compounded (using a compounding machine to perform two-layer, three-layer or multi-layer compounding) and is a traditional product commonly used in the manufacture of playing cards.

[0104] It can be clearly seen from the above comparison results that compared with the playing cards obtained by the traditional preparation method, the quality of the finished paper (i.e., the finished base paper) in this application, i.e., the cohesion, interlayer bonding force and folding resistance of the finished paper are much higher than those of the control group. At the same time, the cohesion, interlayer bonding force and folding resistance of the playing cards further prepared from the finished paper are still much higher than those of the control group. Therefore, the technology of this application can achieve the effect of improving the cohesion and interlayer bonding force of the base paper, thereby improving its strength and folding resistance.

[0105] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for producing folding-resistant base paper, characterized in that: include: Mixing wood pulp, calcium carbonate filler, cooked cationic starch and sizing agent to obtain mixed pulp; Purifying and removing slag from the mixed pulp to obtain pre-pulp; Adding uncooked cationic starch, hydrophobically modified starch and a dry strength agent into the pre-slurry to obtain the original slurry; The raw pulp is subjected to screening treatment, and then subjected to screen processing, and then subjected to drying.

2. The method for producing folding-resistant base paper according to claim 1, characterized in that: The amount of the uncooked cationic starch is 40-50 kg / t paper, the amount of the hydrophobically modified starch is 5-8 kg / t paper, and the amount of the dry strength agent is 5-20 kg / t paper.

3. The method for producing folding-resistant base paper according to claim 1, characterized in that: The step of adding uncooked cationic starch, hydrophobically modified starch and a dry strength agent to the pre-slurry to obtain the raw slurry comprises: firstly mixing the uncooked cationic starch with the hydrophobically modified starch, adding water to disperse the mixed starch to obtain starch slurry, and then adding the starch slurry and the dry strength agent to the pre-slurry.

4. The method for producing folding-resistant base paper according to claim 3, characterized in that: In the step of first mixing the uncooked cationic starch with the hydrophobically modified starch and then adding water to disperse the mixture, the dispersion ratio of the uncooked cationic starch to the hydrophobically modified starch is in the range of [7.5-9.5]:[0.5-2], the solid content of the starch slurry is 25-35%, and the absolute dry weight of the starch slurry is 40-52 kg.

5. The method for producing folding-resistant base paper according to claim 1, characterized in that: After the step of drying after the web-surface treatment, the method further includes the steps of: performing a surface sizing treatment, performing secondary drying after the surface sizing treatment to obtain a semi-base paper, and performing off-machine coating on the semi-base paper to obtain a finished base paper; The off-machine coating steps include: primer coating, top coating and back sizing.

6. The method for producing folding-resistant base paper according to claim 5, characterized in that: The coating amount of the primer is 8-12 g / m 2 The coating amount of the top coating is 10-12g / m 2 The amount of glue applied to the back side is 1-3 g / m 2 The solid content of the coating used for the primer and the topcoat is 66-68%.

7. The method for producing fold-resistant base paper according to claim 1, characterized in that: The wood pulp includes softwood pulp and hardwood pulp.

8. The method for producing folding-resistant base paper according to claim 7, characterized in that: The mass percentage of the coniferous wood pulp is 20-30%, the mass percentage of the hardwood pulp is 70-80%, the mass percentage of the calcium carbonate filler is 6-10%, the amount of the cooked cationic starch is 9-11 kg / t paper; the amount of the sizing agent is 8.5-11.5 kg / t paper.

9. The method for producing fold-resistant base paper according to claim 1, characterized in that: The online processing includes: adjusting the online flow, controlling the scanned paper weight to 120-123g / m 2 between.

10. A fold-resistant base paper, characterized in that: The fold-resistant base paper is prepared by the production method described in any one of claims 1 to 9.

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