A method for improving the printability of a matte art paper

Abstract

The application provides a method for improving the printing performance of a matte art paper, which comprises the steps of preparing stock pulp, forming, sizing, coating and calendering, characterized in that after the sizing step, the coating step is performed, after the bottom coating, the middle coating and the top coating are performed in sequence by using a middle coating paint and a top coating paint containing modified butadiene-styrene latex as adhesive B, and finally, the matte art paper is obtained by calendering; and the preparation method of the modified butadiene-styrene latex comprises the following steps: adding emulsifiers and surfactants into water, stirring at 50-60 DEG C to obtain a solvent; mixing butadiene, styrene and trichloroethyl phosphate, and stirring to obtain a monomer solution; adding the monomer solution into the solvent, adding an initiator, and reacting at 70-80 DEG C for 1-2 h, then continuously adding the monomer solution and the initiator into the reaction solution, and reacting at 70-80 DEG C for 1-2 h, and repeating the operation to obtain the modified butadiene-styrene latex. The method provided by the application improves the flatness of the base paper, makes the printing surface of the matte art paper better, and effectively solves the problems of printing mottle and the like.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking, and in particular to a method for improving the printing performance of matte coated paper. Background Art

[0002] Printing smudges are a common paper defect in the printing industry. Most causes stem from poor contact caused by aging and deformation of the ink transfer medium during the printing process, insufficient or uneven printing pressure, and improper use of ink additives. However, as one of the primary printing media, paper's impact on print quality cannot be underestimated.

[0003] The fundamental cause of print drift can be explained as uneven ink distribution across the print surface. This results in varying shades and densities of the same color across different areas of the print, ultimately resulting in uneven color distribution and poor visual quality. Print drift often occurs when printing a single color across a full page or large areas. Resolving this issue is a complex undertaking.

[0004] Coated paper is made by applying three or four coats of coating to a base paper to create the desired coated paper. The impact of different pulp ratios on the base paper's surface is particularly significant. Currently, the main pulp ratios for base paper are LBKP (short fiber pulp), NBKP (long fiber pulp), and BCTMP (mechanical pulp). When these three pulps are used in different proportions during papermaking, the base paper exhibits different uniformity. Currently, paper grades with high requirements for folding resistance and cohesion require a higher proportion of long fiber pulp, resulting in poor base paper uniformity. Even using a more optimized coating formula still cannot mask the unevenness of the base paper. Therefore, to improve the base paper's flatness, adjustments must be made to the pulp ratio, pulp freeness, pulp brand, and the use of chemicals during papermaking to improve base paper uniformity.

[0005] Coating formulation is one of the most important factors influencing printing results, and pigment selection is the primary factor affecting the roughness and gloss of coated paper. Currently, coated paper production in China primarily uses ground calcium carbonate, and latexes such as bio-latex prepared from styrene-butadiene latex and starch. Functional additives such as defoamers, lubricants, dispersants, and thickeners are added to coating formulations to achieve desired paper machine runnability and paper properties. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a method for improving the printing performance of matte coated paper, so as to improve the paper forming performance and printing performance.

[0007] The technical solution of the present invention is achieved as follows:

[0008] A method for improving the printing performance of matte coated paper, comprising the steps of preparing a stock pulp, forming a sheet, sizing, coating, and calendering. After sizing, in the coating stage, a primer is applied, followed by a mid-coat and a top-coat containing a modified styrene-butadiene latex as an adhesive B, the mid-coat and the top-coat are applied in sequence, and finally calendering is performed to obtain the matte coated paper.

[0009] The preparation method of the modified styrene-butadiene latex comprises the following:

[0010] (1) Adding an emulsifier and a surfactant to water and stirring at 50-60° C. to obtain a solvent;

[0011] (2) mixing butadiene, styrene, and trichloroethyl phosphate in a mass ratio of 20-40:8-18:4-7, and stirring to obtain a monomer solution;

[0012] (3) Add the monomer solution to the solvent, add the initiator while stirring, react at 70-80°C for 1-2 hours, then continue to add the monomer solution and initiator to the reaction solution while stirring, react at 70-80°C for 1-2 hours, repeat the operation 2-4 times to obtain modified styrene-butadiene latex.

[0013] A further solution is that the mass ratio of the solvent, monomer solution and initiator is 280-350:90-120:0.2-1;

[0014] The mass ratio of water, emulsifier and surfactant is 100-150:0.5-2:0.8-2;

[0015] The initiator includes ammonium persulfate and / or sodium persulfate;

[0016] In step (1), the stirring time at 50-60° C. is 20-40 min; in step (2), the stirring time is 20-40 min.

[0017] A further solution is that the base coating comprises the following raw materials in parts by weight: 84-86 parts of ground calcium carbonate C65 grade, 13-15 parts of adhesive A, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer and 0.4-0.8 parts of thickener.

[0018] The midcoat formulation includes the following raw materials, in parts by weight: 88-90 parts of ground calcium carbonate C60 grade, 10-13 parts of adhesive B, 0.05-0.2 parts of dispersant, 0.02-0.08 parts of defoamer, and 0.4-0.8 parts of thickener;

[0019] The topcoat formulation includes the following raw materials, measured in parts by weight: 40-50 parts of ground calcium carbonate C65 grade, 40-50 parts of ground calcium carbonate C98 grade, 7-9 parts of adhesive B, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer, 0.1-0.3 parts of lubricant, and 0.2-0.6 parts of thickener;

[0020] The adhesive A comprises at least one of styrene-butadiene latex and bio-latex;

[0021] The ground calcium carbonate C60 grade has a particle size of less than 1 μm accounting for 20% to 40% of the content, and a particle size of less than 2 μm accounting for 58% to 62% of the content;

[0022] The ground calcium carbonate C65 grade has a particle size of less than 2 μm and a content of 62% to 66%;

[0023] The ground calcium carbonate C98 grade has a particle content of particles with a particle size of less than 2 μm accounting for more than 98%.

[0024] A further solution is that the adhesive B further comprises styrene acrylic latex and / or bio-latex, and the mass ratio of styrene acrylic latex to modified styrene butadiene latex is 1-2:7-8;

[0025] Or the mass ratio of bio-latex to modified styrene-butadiene latex is 3-4:8-10;

[0026] Or the mass ratio of biological latex, styrene acrylic latex and modified styrene butadiene latex is 8-10:1-2:3-5.

[0027] A further solution is to use film transfer double-sided coating to carry out the primer coating, the coating solid content is 56% to 62%, the low shear viscosity is 200 to 400 cps, and the film transfer coating amount is 10 to 15 g / m 2 , the ratio of the upper roller pressure to the lower roller pressure of the primer metering rod is 1.4~1.8:1.4~1.8;

[0028] The intermediate coating is carried out by two knife coatings, the coating solid content is 57% to 62%, the low shear viscosity is 400 to 600 cps, and the film transfer coating amount is 16 to 22 g / m 2 , the pressure of the middle coating scraper is 35% to 60%;

[0029] The top coating is carried out by two knife coatings, the coating solid content is 66% to 69%, the low shear viscosity is 800 to 1100 cps, and the film transfer coating amount is 16 to 22 g / m 2 , the surface coating scraper pressure is 30~55%.

[0030] A further solution is that, by weight percentage, the raw materials of the raw pulp are: 69% to 90% of pulp mixture, 9% to 30% of ground calcium carbonate and 0.6% to 1.0% of positive starch;

[0031] The pulp mixture comprises kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp in a weight ratio of 50-70:5-20:15-30;

[0032] The ground calcium carbonate is of grade C60, wherein particles with a particle size of less than 1 μm account for 20% to 40%, and particles with a particle size of less than 2 μm account for 58% to 62%.

[0033] A further solution is to use film transfer double-sided sizing to apply the sizing, the glue solution includes a starch glue solution with a mass concentration of 8% to 12%, a low shear viscosity of 8 to 13 cps, and a total film transfer sizing amount of 1 to 3 g / m 2 .

[0034] A further solution is to further include a hard calendering step after sizing and before coating, wherein the calendering line pressure of the hard calendering is 30-50 kN / m and the calendering temperature is 60-80°C.

[0035] A further solution is that the calendering adopts 4+9 two-pressure zones, the calendering line pressure is 60-90 kN / m, and the calendering temperature is 40-60°C.

[0036] Another aspect of the present invention provides matte coated paper prepared by the above method.

[0037] Coated paper consists of base paper, sizing, primer, midcoat, and topcoat. The coating is very thin, and the smoothness of the innermost base paper is a crucial factor in determining the smoothness of the finished paper. The coating formulation significantly influences the gloss and roughness of the finished paper, while the choice of pigment can lead to smearing and light spots. Furthermore, the papermaking process significantly impacts the surface feel of the finished paper.

[0038] Specifically:

[0039] Improve the smoothness of base paper: 1. Reduce the amount of N pulp to improve the evenness; 2. Increase the coating amount to improve the finishing performance of the coating on the base paper.

[0040] Improve paper surface feel: 1. Use bio-latex in the primer to improve the water retention of the paint; 2. Optimize the paint formula to improve the surface feel of the finished paper.

[0041] Improve the ink absorption problem of the coating and improve the printing effect: 1. Use modified styrene-butadiene latex in the coating to improve the ink absorption performance; 2. Optimize the pigment ratio and coating parameters, improve the porosity of the paper surface, and improve the ink absorption problem.

[0042] The key technology lies in improving the flatness of the base paper. The main reason why coated paper has a poor surface feel when printing on a full page is poor ink absorption and the problem of light spots on the finished paper. Ink absorption can be improved by improving the ink absorption of the finished paper or increasing the printing pressure and the amount of ink during printing. In addition, latex can be used to allow the ink to be absorbed into the shallower part of the coating to avoid the problem of uneven coating caused by the unevenness of the base paper, which in turn affects the depth of ink absorption. Modified latex can make the ink uniformly absorbed shallower, which helps to evenly distribute the ink and achieve the effect of improving the flatness of the base paper. The light spot problem can be improved by improving the flatness of the base paper and adjusting the pigment type or proportion of the coating formula. The long fibers of the N pulp itself will cause the flatness of the base paper to deteriorate. Reducing the amount of N pulp will significantly improve the flatness of the base paper.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) Adjustment of base paper formula: The present invention significantly reduces the amount of N pulp used, increases the white water concentration during papermaking, fills the pores of the base paper, and improves the flatness of the base paper;

[0045] (2) Selection of coating pigments: The present invention adjusts the pigment particle size of the bottom, middle and top coatings to obtain a more uniform coating distribution, and by selecting bio-latex and modified styrene-butadiene latex respectively, achieves the purpose of improving the ink absorption problem of the coating and enhancing the printing performance of the paper; optimizes the coating formula to give the paper better gloss and ink absorption performance.

[0046] (3) Adjustment of coating parameters: By setting the bottom, middle and top coating parameters, the covering performance of the base paper can be effectively improved, thereby making the finished paper smoother and improving the printing performance of matte coated paper. DETAILED DESCRIPTION

[0047] In order to better understand the technical content of the present invention, specific examples are provided below to further illustrate the present invention.

[0048] Unless otherwise specified, the experimental methods used in the examples of the present invention are all conventional methods.

[0049] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0050] The ground calcium carbonate used in the embodiment of the present invention is ground calcium carbonate C60 treated with a polymer, wherein the content of particles with a particle size less than 1 μm is within 20-40%, and the content of particles with a particle size less than 2 μm is within 58-62%.

[0051] The ground calcium carbonate used in the embodiment of the present invention is ground calcium carbonate C65 treated with a polymer, and the content of particles with a particle size less than 2 μm is within 62-66%.

[0052] The ground calcium carbonate used in the embodiment of the present invention is ground calcium carbonate C98 treated with a polymer, and the content of particles with a particle size of less than 2 μm is greater than 98%.

[0053] Example 1

[0054] The preparation method of modified styrene-butadiene latex comprises the following steps:

[0055] (1) Add an emulsifier and a surfactant to water at a mass ratio of 120:1:1, and stir at 50-60°C for 30 minutes to obtain a solvent;

[0056] (2) Butadiene, styrene, and trichloroethyl phosphate were mixed in a mass ratio of 30:12:5 and stirred for 30 minutes to obtain a monomer solution;

[0057] (3) Add 100 g of monomer solution to 300 g of solvent at a mass ratio of 300:100:0.8, add 0.8 g of initiator ammonium persulfate while stirring, react at 70-80°C for 1 hour, continue to add 100 g of monomer solution and 0.8 g of initiator ammonium persulfate to the reaction solution while stirring, react at 70-80°C for 1 hour, then add 100 g of monomer solution and 0.8 g of initiator ammonium persulfate to the reaction solution while stirring again, react at 70-80°C for 1 hour to obtain modified styrene-butadiene latex

[0058] Example 2

[0059] A method for improving the printing performance of matte coated paper, comprising the following steps:

[0060] S1: Take kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mix them in a weight ratio of 60:10:20 to form a pulp mixture. The energy consumption of kraft softwood pulp refining is 80-90 kwh / t, the energy consumption of bleached kraft hardwood pulp refining is 220-240 kwh / t, and the energy consumption of alkaline hydrogen peroxide mechanical pulp refining is 40-50 kwh / t.

[0061] S2: Adding ground calcium carbonate and positive starch to the slurry mixture of step S1 and mixing thoroughly to obtain base paper pulp; the base paper pulp is composed of 86.2% of the slurry mixture, 13% of the ground calcium carbonate C60 grade, and 0.8% of the positive starch by weight; the wire speed is 1400 m / min, and the wire vacuum Form.roll is -120 to -30 mbar.

[0062] S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 120-130 g / m 2 , of which the moisture content is 8% to 10%;

[0063] S4: Based on step S3, double-sided sizing is performed using film transfer, with a starch glue solution having a mass concentration of 10%, a low shear viscosity of 10 cps, and a total film transfer sizing amount of 2 g per square meter of coated paper, and the resulting base paper is sizing the surface;

[0064] S5: Based on step S4, hard calendering is adopted, with a calendering line pressure of 45 kN / m and a calendering temperature of 70-75°C.

[0065] S6: Based on step S5, a double-sided film transfer coating is used for primer coating. The coating solid content is 58%, the low shear viscosity is 250 cps, the film transfer coating amount is 12 g per square meter of coated paper, and the primer metering rod pressure is: upper roller / lower roller: 1.4-1.8 / 1.4-1.8 bar;

[0066] The formula of the primer coating for film transfer coating is as follows by weight: 85 parts of ground calcium carbonate C65 grade, 15 parts of adhesive (m styrene-butadiene latex: m biolatex = 2:15), 0.08 parts of dispersant, 0.06 parts of defoamer and 0.6 parts of thickener.

[0067] S7: Based on step S6, two doctor blade coatings are applied, one side at a time, for intermediate coating. The coating solid content is 60%, the low shear viscosity is 500 cps, and the total doctor blade coating amount per square meter of paper is 18 g. The doctor blade pressure for intermediate coating is 50% to 60%.

[0068] By weight, the coating applied by the middle coating blade includes 88 parts of ground calcium carbonate C60 grade, 12 parts of adhesive (m modified styrene-butadiene latex of Example 1: m biolatex = 4:10), 0.12 parts of dispersant, 0.10 parts of defoamer and 0.7 parts of thickener.

[0069] S8: Based on step S7, two doctor blade coatings are used, one side at a time, to perform top coating. The coating solids content is 68%, the low shear viscosity is 1200 cps, and the total top coating weight per square meter of paper is 18 g. The top coating doctor blade pressure is 50% to 55%;

[0070] The formulation of the topcoat blade coating, in parts by weight, is: 48 parts ground calcium carbonate C65 grade, 46 parts ground calcium carbonate C98 grade, 8 parts adhesive (modified styrene-butadiene latex of Example 1), 0.06 parts dispersant, 0.04 parts defoamer, 0.2 parts lubricant, and 0.3 parts thickener.

[0071] S9: The paper product obtained in step S8 is calendered and modified on the paper surface using a super calender, the calender adopts 4+9 two-pressure zones, the calendering temperature is 55-60°C, the linear pressure is 85kN / m, and then matte coated paper is produced.

[0072] Example 3

[0073] A method for improving the printing performance of matte coated paper, comprising the following steps:

[0074] S1: Take kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mix them in a weight ratio of 65:15:20 to form a pulp mixture. The energy consumption of kraft softwood pulp refining is 90-100 kwh / t, the energy consumption of bleached kraft hardwood pulp refining is 240-260 kwh / t, and the energy consumption of alkaline hydrogen peroxide mechanical pulp refining is 50-60 kwh / t.

[0075] S2: Adding ground calcium carbonate and positive starch to the slurry mixture of step S1 and mixing thoroughly to obtain base paper pulp; the base paper pulp is composed of 86.2% of the slurry mixture, 13% of the ground calcium carbonate C60 grade, and 0.8% of the positive starch by weight; the wire speed is 1400 m / min, and the wire vacuum Form.roll is -120 to -30 mbar.

[0076] S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 100-120 g / m 2 , of which the moisture content is 8% to 10%;

[0077] S4: Based on step S3, double-sided sizing is performed using film transfer, with a starch glue solution having a mass concentration of 12%, a low shear viscosity of 12 cps, and a total film transfer sizing amount of 3 g per square meter of coated paper, and the resulting base paper is sizing the surface;

[0078] S5: Based on step S4, hard calendering is adopted, with a calendering line pressure of 45 kN / m and a calendering temperature of 70-75°C.

[0079] S6: Based on step S5, a double-sided film transfer coating is used for primer coating. The coating solid content is 58%, the low shear viscosity is 250 cps, the film transfer coating amount is 12 g per square meter of coated paper, and the primer metering rod pressure is: upper roller / lower roller: 1.4-1.8 / 1.4-1.8 bar;

[0080] The formula of the primer coating for film transfer coating is as follows by weight: 85 parts of ground calcium carbonate C65 grade, 15 parts of adhesive (m styrene-butadiene latex: m biolatex = 2:15), 0.08 parts of dispersant, 0.06 parts of defoamer and 0.6 parts of thickener.

[0081] S7: Based on step S6, two doctor blade coatings are applied, one side at a time, for intermediate coating. The coating solid content is 60%, the low shear viscosity is 500 cps, and the total doctor blade coating amount per square meter of paper is 18 g. The doctor blade pressure for intermediate coating is 50% to 60%.

[0082] By weight, the coating applied by the middle coating blade includes 88 parts of ground calcium carbonate C60 grade, 12 parts of adhesive (m modified styrene-butadiene latex of Example 1: m biolatex = 4:10), 0.12 parts of dispersant, 0.10 parts of defoamer and 0.7 parts of thickener.

[0083] S8: Based on step S7, two doctor blade coatings are used, one side at a time, to perform top coating. The coating solids content is 68%, the low shear viscosity is 1200 cps, and the total top coating weight per square meter of paper is 18 g. The top coating doctor blade pressure is 50% to 55%;

[0084] The formulation of the topcoat blade coating, in parts by weight, is: 48 parts ground calcium carbonate C65 grade, 46 parts ground calcium carbonate C98 grade, 8 parts adhesive (modified styrene-butadiene latex of Example 1), 0.06 parts dispersant, 0.04 parts defoamer, 0.2 parts lubricant, and 0.3 parts thickener.

[0085] S9: The paper product obtained in step S8 is calendered and modified using a super calender. The calender adopts a 4+9 two-pressure zone, a calendering temperature of 55-60°C, a linear pressure of 85kN / m, and is finally made into matte coated paper.

[0086] Example 4

[0087] The difference between this embodiment and embodiment 2 is that the adhesives used in steps S7 and S8 are different, as follows:

[0088] S7: Use two doctor blade coatings, coating one side each time, and then perform the intermediate coating. The solid content of the coating is 60%, the low shear viscosity is 500cps, and the total doctor blade coating amount per square meter of paper is 18g. The doctor blade pressure of the intermediate coating is 50% to 60%.

[0089] By weight, the coating applied by the middle coating blade includes 88 parts of ground calcium carbonate C60 grade, 12 parts of adhesive (m modified styrene-butadiene latex of Example 1: m styrene acrylic latex: m biolatex = 3:1:10), 0.12 parts of dispersant, 0.10 parts of defoamer and 0.7 parts of thickener.

[0090] S8: Based on step S7, two doctor blade coatings are used, one side at a time, to perform top coating. The coating solids content is 68%, the low shear viscosity is 1200 cps, and the total top coating weight per square meter of paper is 18 g. The top coating doctor blade pressure is 50% to 55%;

[0091] The formulation of the coating applied by the topcoat blade is, by weight, 48 parts of ground calcium carbonate C65 grade, 46 parts of ground calcium carbonate C98 grade, 8 parts of adhesive (m modified styrene-butadiene latex of Example 1: m styrene-acrylic latex = 7:1), 0.06 parts of dispersant, 0.04 parts of defoamer, 0.2 parts of lubricant and 0.3 parts of thickener.

[0092] The remaining steps S1-S6 and S9, as well as the parameters, are the same as those in Example 2.

[0093] Example 5

[0094] The difference between this embodiment and embodiment 2 is that in step S1, the weight ratio of kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp is 20:55:20, and they are mixed to form a pulp mixture. The energy consumption of kraft softwood pulp refining is 80-90 kwh / t, the energy consumption of bleached kraft hardwood pulp refining is 220-240 kwh / t, and the energy consumption of alkaline hydrogen peroxide mechanical pulp refining is 40-50 kwh / t.

[0095] Comparative Example 1

[0096] The difference between this comparative example and Example 2 is that the adhesives in steps S7 and S8 are different, as follows:

[0097] S7: Use two doctor blade coatings, coating one side each time, and then perform the intermediate coating. The solid content of the coating is 60%, the low shear viscosity is 500cps, and the total doctor blade coating amount per square meter of paper is 18g. The doctor blade pressure of the intermediate coating is 50% to 60%.

[0098] In parts by weight, the coating applied by the mid-coat blade includes 88 parts of ground calcium carbonate C60 grade, 12 parts of adhesive (m styrene-butadiene latex: m biolatex = 8:4), 0.12 parts of dispersant, 0.10 parts of defoamer and 0.7 parts of thickener.

[0099] S8: Based on step S7, two doctor blade coatings are used, one side at a time, to perform top coating. The coating solids content is 68%, the low shear viscosity is 1200 cps, and the total top coating weight per square meter of paper is 18 g. The top coating doctor blade pressure is 50% to 55%;

[0100] The formulation of the coating applied by the topcoat scraper is, by weight, 48 parts of ground calcium carbonate C65 grade, 46 parts of ground calcium carbonate C98 grade, 8 parts of adhesive (m styrene-butadiene latex: m biolatex = 7:3), 0.06 parts of dispersant, 0.04 parts of defoamer, 0.2 parts of lubricant and 0.3 parts of thickener.

[0101] The remaining steps S1-S6 and S9, as well as the parameters, are the same as those in Example 2.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Example 2 is that the adhesives in steps S6, S7 and S8 are different, as follows:

[0104] S6: Based on step S5, a double-sided film transfer coating is used for primer coating. The coating solid content is 58%, the low shear viscosity is 250 cps, the film transfer coating amount is 12 g per square meter of coated paper, and the primer metering rod pressure is: upper roller / lower roller: 1.4-1.8 / 1.4-1.8 bar;

[0105] The formula of the primer coating for film transfer coating is as follows, by weight: 85 parts of ground calcium carbonate C65 grade, 14 parts of adhesive (bio-latex), 0.08 parts of dispersant, 0.06 parts of defoamer and 0.6 parts of thickener.

[0106] S7: Use two doctor blade coatings, coating one side each time, and then perform the intermediate coating. The solid content of the coating is 60%, the low shear viscosity is 500cps, and the total doctor blade coating amount per square meter of paper is 18g. The doctor blade pressure of the intermediate coating is 50% to 60%.

[0107] In parts by weight, the coating applied by the mid-coat blade includes 88 parts of ground calcium carbonate C60 grade, 10 parts of adhesive (m styrene-butadiene latex: m biolatex = 1:10), 0.12 parts of dispersant, 0.10 parts of defoamer and 0.7 parts of thickener.

[0108] S8: Based on step S7, two doctor blade coatings are used, one side at a time, to perform top coating. The coating solids content is 68%, the low shear viscosity is 1200 cps, and the total top coating weight per square meter of paper is 18 g. The top coating doctor blade pressure is 50% to 55%;

[0109] The formulation of the coating applied by the topcoat scraper is, by weight, 48 parts of ground calcium carbonate C65 grade, 46 parts of ground calcium carbonate C98 grade, 9 parts of adhesive (m styrene-butadiene latex: m biolatex = 5:6), 0.06 parts of dispersant, 0.04 parts of defoamer, 0.2 parts of lubricant and 0.3 parts of thickener.

[0110] The remaining steps S1-S5 and S9, as well as the parameters, are the same as those in Example 2.

[0111] Test Case

[0112] The matte coated paper products produced in Examples 2 to 5 and Comparative Examples 1 to 2 were subjected to performance tests, and the results are shown in Table 1 below.

[0113] Table 1 Performance test results of different matte coated paper products

[0114]

[0115]

[0116] As can be seen from Table 1 above, the finished matte coated paper produced in Examples 1 to 4 of the present invention has a gloss of 28% to 33%, a blur value of 10 to 16, a light spot level of 3, a folding endurance of 3 times, excellent flatness of the finished paper, and improved printing performance. Comparison of Example 5 with Examples 1 to 4 shows that increasing the amount of N pulp (NBKP, bleached kraft softwood pulp) reduces ink absorption during the printing process, and the light spot phenomenon is obvious. Comparative Examples 1 and 2 show that using bio-latex first in the primer coating can improve the water retention of the coating, and then using modified styrene-butadiene latex in the mid-coat and topcoat can improve the ink absorption of the finished paper, making the coating more uniform and ensuring the good appearance quality of the paper.

[0117] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for improving the printing performance of matte coated paper, characterized in that: Here are the steps: S1: taking softwood kraft pulp, bleached hardwood kraft pulp and alkaline hydrogen peroxide mechanical pulp, mixing them in a weight ratio of 50-70:5-20:15-30 to form a pulp mixture; S2: adding ground calcium carbonate and cationic starch to the pulp mixture of step S1 and mixing thoroughly to obtain base paper pulp; the base paper pulp is composed of 69% to 90% of the pulp mixture, 9% to 30% of the ground calcium carbonate C60 grade, and 0.6% to 1.0% of the cationic starch by weight percentage; S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 100-130 g / m 2 , of which the moisture content is 8%~10%; S4: Based on step S3, a starch glue solution with a mass concentration of 8% to 12% is used for double-sided sizing of the film transfer, and the total sizing amount per square meter of coated paper film transfer is 1 to 3 g / m 2 ; S5: Based on step S4, hard calendering is performed; S6: Based on step S5, use film transfer double-sided coating to perform primer coating. The coating solid content is 56%~62%, the low shear viscosity is 200~400cps, and the film transfer coating amount per square meter of coated paper is 10~15g / m 2 ; S7: Based on step S6, two scraper coatings are applied, coating one side each time, for intermediate coating. The coating solid content is 57%~62%, and the low shear viscosity is 400~600cps. After completion, the total scraper coating amount per square meter of paper is 16~22g / m 2 ; S8: Based on step S7, two doctor blade coatings are used, coating one side each time, to perform top coating. The coating solid content is 66% to 69%, and the low shear viscosity is 800 to 1100 cps. After completion, the total top coating amount per square meter of paper is 16 to 22 g / m 2 ; S9: The paper product obtained in step S8 is calendered and modified using a super calender to produce matte coated paper; In step S6, the coating formulation of the primer includes the following raw materials in parts by weight: 84-86 parts of ground calcium carbonate C65 grade, 13-15 parts of adhesive A, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer and 0.4-0.8 parts of thickener; the adhesive A comprises styrene-butadiene latex and bio-latex; In step S7, the coating formula of the mid-coat includes the following raw materials, calculated by weight: 88-90 parts of ground calcium carbonate C60 grade, 10-13 parts of adhesive B, 0.05-0.2 parts of dispersant, 0.02-0.08 parts of defoamer and 0.4-0.8 parts of thickener; the adhesive B in the mid-coat includes modified styrene-butadiene latex and bio-latex; In step S8, the topcoat coating formulation includes the following raw materials, in parts by weight: 40-50 parts of ground calcium carbonate C65 grade, 40-50 parts of ground calcium carbonate C98 grade, 7-9 parts of adhesive B, 0.05-0.20 parts of dispersant, 0.02-0.08 parts of defoamer, 0.1-0.3 parts of lubricant, and 0.2-0.6 parts of thickener; the adhesive B in the topcoat includes modified styrene-butadiene latex; The ground calcium carbonate C60 grade has a particle size of less than 1 μm accounting for 20% to 40% of the particles, and a particle size of less than 2 μm accounting for 58% to 62% of the particles; The ground calcium carbonate C65 grade has a particle size of less than 2 μm and a content of 62% to 66%; The ground calcium carbonate C98 grade has a particle size of less than 2 μm and a content of more than 98%; The preparation method of the modified styrene-butadiene latex comprises the following steps: (1) adding an emulsifier and a surfactant to water in a mass ratio of water, emulsifier and surfactant of 100-150:0.5-2:0.8-2, stirring at 50-60° C. for 20-40 min to obtain a solvent; (2) mixing butadiene, styrene and trichloroethyl phosphate in a mass ratio of 20-40:8-18:4-7, and stirring for 20-40 minutes to obtain a monomer solution; (3) Add the monomer solution to the solvent, add the initiator while stirring, and react at 70-80°C for 1-2 hours. The mass ratio of the solvent, monomer solution and initiator is 280-350:90-120:0.2-1; continue to add the monomer solution and initiator to the reaction solution while stirring, and react at 70-80°C for 1-2 hours. Repeat the operation 2-4 times to obtain modified styrene-butadiene latex.

2. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: The initiator includes ammonium persulfate and / or sodium persulfate.

3. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S4, the low shear viscosity of the starch glue is 8-13 cps.

4. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S5, the calendering line pressure of the hard calendering is 30-50 kN / m, and the calendering temperature is 60-80°C.

5. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S6, the ratio of the upper roller pressure to the lower roller pressure of the primer metering rod is 1.4-1.8:1.4-1.

8.

6. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S7, the pressure of the intermediate coating blade is 50% to 60%.

7. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S8, the pressure of the top coating blade is 50% to 55%.

8. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S9, the calendering adopts 4+9 two-pressure zones, the calendering line pressure is 60-90 kN / m, and the calendering temperature is 40-60°C.

9. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S7, the adhesive B in the mid-coat includes modified styrene-butadiene latex, biological latex and styrene-acrylic latex, and the mass ratio of the modified styrene-butadiene latex, biological latex and styrene-acrylic latex is 3-5:8-10:1-2.

10. The method for improving the printing performance of matte coated paper according to claim 1, characterized in that: In step S8, the adhesive B in the top coating includes modified styrene-butadiene latex and styrene-acrylic latex, and the mass ratio of the modified styrene-butadiene latex to the styrene-acrylic latex is 7-8:1-2.

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