High-ash chromo board and preparation method thereof

Abstract

The invention belongs to the technical field of papermaking, and particularly relates to a high-ash chromo board and a preparation method thereof. Comprising raw paper and a coating layer, the raw paper consists of a surface layer, a core layer and a bottom layer; the core layer comprises filler, and the retention rate of the core layer is greater than or equal to 84%; the filler is GCC coated with a filler pretreatment agent obtained by mixing GCC 60 and the filler pretreatment agent; the coating layer adopts a process of coating the front surface and the back surface for three times, and the front surface coating and the back surface coating respectively comprise a base coating, a middle coating and a surface coating; wherein the base coat and the floating coat adopt GCC 60 as filler, and the top coat adopts GCC 98 and porcelain clay as filler; coating starch, styrene-butadiene latex and polyvinyl alcohol are adopted as adhesives for the first coat, and styrene-butadiene latex and polyvinyl alcohol are adopted as adhesives for the middle coat and the top coat. Through the combination of the core layer high retention rate GCC filler and the coating layer multi-component collaborative design, the comprehensive improvement of the performance of the high ash chromo board is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of papermaking, and particularly relates to a high-ash coated art paper and a preparation method thereof. Background Art

[0002] With the continuous improvement of the requirements for paper properties in the printing and packaging industries, high-ash coated art paper has gradually stood out in the fields of cards, posters, high-end packaging, etc. and become the preferred material due to its excellent stiffness, good printing suitability, and significant cost advantages. However, traditional high-ash coated art paper mostly adopts the base paper structure of a mixture of chemical pulp and mechanical pulp, and enhances the surface properties through single-layer or double-layer coating processes. However, this process route has many limitations. Specifically, the retention rate of the core layer filler (such as calcium carbonate) is insufficient, which leads to a low ash content of the formed paper, thus limiting the further improvement of paper stiffness and the space for cost optimization. At the same time, a high filler addition amount is likely to cause charge imbalance in the pulp system, resulting in problems such as filler loss and a decrease in the interlayer bonding strength. During the coating process, if the solid content and viscosity of the coating are not properly controlled, defects such as bubbles and uneven coating are likely to occur, affecting the performance stability of the formed paper. In addition, the existing coating layers mostly use a single filler, which makes it difficult to achieve a balance between surface smoothness and ink absorption, and printing patterns are prone to blurring, dull color, etc., affecting the printing suitability. More importantly, the traditional process highly relies on a high proportion of chemical pulp, which not only has high raw material costs but also does not conform to the current development trend of green manufacturing. Therefore, there is an urgent need to develop a new preparation technology for high-ash coated art paper to solve the above problems and meet the urgent market demand for high-performance, environmentally friendly, and economical paper. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a high-ash coated art paper, which realizes the comprehensive improvement of the performance of the high-ash coated art paper through the combination of high retention rate GCC filler in the core layer and multi-component collaborative design in the coating layer.

[0004] Another purpose of the present invention is to provide a preparation method for the high-ash coated art paper.

[0005] The technical solutions adopted by the present invention are as follows: The described high-ash coated paperboard includes base paper and a coating layer; the base paper consists of a surface layer, a core layer, and a bottom layer; the core layer contains a filler with a retention rate of ≥84%; the filler is GCC coated with a filler pretreatment agent obtained by mixing GCC 60, filler pretreatment agent FillerTEKDEV 210, and filler pretreatment agent FillerTEK DEV 310; the addition amount of GCC60 is 150 - 220 kg / t pulp; the weight ratio of filler pretreatment agent FillerTEK DEV 210 to GCC 60 is 3 kg:150 t; the weight ratio of filler pretreatment agent FillerTEK DEV 310 to GCC 60 is 1.5 kg:150 t; The described coating layer adopts a three - coat process on both the front and back sides. The front coating and the back coating each include a primer coat, a middle coat, and a top coat; among them, the primer coat and the middle coat use GCC 60 as the filler, and the top coat uses GCC 98 and kaolin with a weight ratio of (85 - 88):(12 - 15) as the filler.

[0006] In the described GCC 60, the content ratio of particles with a particle size of ≤2μm is 59 - 61%. Its preparation method is: crushing calcium carbonate ore into coarse particles with a particle size of less than 5 cm, then transferring them to a ball mill for pre - grinding to obtain an intermediate product with a particle size of less than 500μm, then adding a dispersant and zirconium beads for wet grinding. After the wet grinding is completed, the ground product is dried to obtain the product with the target particle size; the dispersant is ZH - 671 (purchased from Changshu Juhe Chemical Co., Ltd.), and the addition amount of the dispersant is 0.2 - 0.3% of the dry - basis mass of the intermediate product.

[0007] In the described GCC 98, the content ratio of particles with a particle size of ≤2μm is 97 - 99%. Its preparation method is the same as that of GCC 60, the difference is that the addition amount of the dispersant is 0.6 - 0.7% of the dry - basis mass of the intermediate product.

[0008] The described primer coat uses coating starch, styrene - butadiene latex, and polyvinyl alcohol as adhesives, and the middle coat and the top coat use styrene - butadiene latex and polyvinyl alcohol as adhesives.

[0009] The coating of the described primer coat also includes a pH regulator, a dispersant, a bactericide, an antifoaming agent, a water - repellent agent, and a lubricant; the coatings of the middle coat and the top coat also include a pH regulator, a dispersant, a bactericide, an antifoaming agent, a water - repellent agent, a lubricant, and a fluorescent brightening agent.

[0010] Specifically, the primer coating material comprises the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.05 - 0.07 parts, dispersant FLO2288: 0.18 - 0.22 parts, fungicide AmiCide BX 9058: 0.008 - 0.012 parts, defoamer DF-3000: 0.03 - 0.07 parts, styrene-butadiene latex: 5 - 8 parts, coating starch: 2 - 6 parts, polyvinyl alcohol: 0.1 - 0.3 parts, water repellent Ksk386-50: 0.1 - 0.4 parts, lubricant NCC ® MS-268: 0.1 - 0.3 parts, sodium carboxymethyl cellulose: 0.6 - 1.0 parts; The intermediate coating material comprises the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.07 - 0.11 parts, dispersant FLO2288: 0.18 - 0.22 parts, fungicide AmiCide BX 9058: 0.008 - 0.012 parts, defoamer DF-3000: 0.03 - 0.07 parts, styrene-butadiene latex: 8 - 12 parts, polyvinyl alcohol: 0.1 - 0.3 parts, water repellent Ksk386-50: 0.1 - 0.4 parts, lubricant NCC ® MS-268: 0.1 - 0.3 parts, sodium carboxymethyl cellulose: 0.6 - 1.0 parts, tetrasulfonated whitening agent ABP-C: 0.15 - 0.19 parts, hexasulfonated whitening agent HST C.I.357: 0.15 - 0.19 parts; The top coating material comprises the following components in parts by weight: GCC 98: 85 - 88 parts, kaolin: 12 - 15 parts, NaOH: 0.05 - 0.07 parts, dispersant FLO2288: 0.18 - 0.22 parts, fungicide AmiCide BX 9058: 0.008 - 0.012 parts, defoamer DF-3000: 0.03 - 0.07 parts, styrene-butadiene latex: 10 - 14 parts, polyvinyl alcohol: 0.15 - 0.35 parts, water repellent Ksk386-50: 0.1 - 0.4 parts, lubricant NCC ® MS-268: 0.1 - 0.3 parts, sodium carboxymethyl cellulose: 0.6 - 1.0 parts, tetrasulfonated whitening agent ABP-C: 0.14 - 0.18 parts, hexasulfonated whitening agent HST C.I.357: 0.14 - 0.18 parts.

[0011] The coating amounts of the primer coating, intermediate coating and top coating are respectively: primer coating on the front side 12.5 - 13.5 g / m 2 , intermediate coating on the front side 11.0 - 12.5 g / m 2 , top coating on the front side 13.0 - 14.5 g / m 2 ; primer coating on the back side 12.5 - 13.5 g / m 2, the back middle coating is 11.0 - 12.5 g / m 2 , the back surface coating is 14.0 - 15.5 g / m 2 .

[0012] The slurries of the surface layer and the bottom layer are composed of 20 - 25 wt.% bleached sulfate softwood pulp and 75 - 80 wt.% bleached sulfate hardwood pulp.

[0013] The slurry of the core layer is composed of 3 - 10 wt.% bleached sulfate softwood pulp, 5 - 10 wt.% bleached sulfate hardwood pulp, 45 - 55 wt.% bleached chemithermomechanical pulp, and 25 - 47 wt.% broke. The broke includes the waste paper that fails to be made into the final product in each link of the coated art paper production.

[0014] The preparation method of the bleached chemithermomechanical pulp includes the following steps: Using 90 wt.% poplar and 10 wt.% pine as raw materials, feeding them in a ratio of 1.1:1 by the mass ratio of raw wood chips to pulp output. After washing the raw wood chips, add NaOH for pre - impregnation. The addition amount of NaOH is 2.5 - 3.5 wt.% of the raw wood chips; after pre - impregnation, through primary refining, bleaching, secondary refining and concentration, the bleached chemithermomechanical pulp is obtained. Among them, in the bleaching stage, a mixed solution of NaOH, H2O2, chelating agent CH - 1636 (purchased from Guangdong Liangshi Industrial Materials Co., Ltd.) and stabilizer WT - 3066 (purchased from Guangdong Liangshi Industrial Materials Co., Ltd.) with a mass ratio of 1.5:3:0.2:1 is added. The addition amount of the mixed solution is 4.5 - 5.5 wt.% of the slurry; the brightness of the obtained bleached chemithermomechanical pulp is 74 - 78%, the bulk is 2.45 - 2.65 cm 3 / g, the tensile index is 21 - 24 N·m / g, and the process methods used are all conventional methods in the field.

[0015] The pH of the slurries of the surface layer, bottom layer and core layer is 7.5 - 8.5.

[0016] The freeness of the slurries is: bleached sulfate softwood pulp: 310 - 330 mL, bleached sulfate hardwood pulp: 340 - 360 mL, bleached chemithermomechanical pulp: 390 - 410 mL, broke: 240 - 260 mL.

[0017] The preparation method of the high - ash - content coated art paper includes the following steps: (1) Base paper preparation: After the slurries of the surface layer, core layer and bottom layer are respectively pulped, refined, mixed and diluted, they are formed on the wire through a three - layer headbox, and then obtained the base paper through pressing, pre - drying, surface sizing, post - drying and hard calendering; among them: Pulping: Use the white water separated during the forming process on the wire as the pulping water, and pulp the surface layer, core layer, and bottom layer slurries separately. The pulping consistency is 5%.

[0018] Refining: During refining, the reflux ratio is controlled between 10 - 15% to reduce excessive fiber disintegration caused by repeated refining of the slurry. Blending: Blending is carried out according to the ratio.

[0019] Dilution: The surface layer and bottom layer slurries are diluted from (3.2 ± 0.2)% after blending to (0.3 ± 0.05)%. After dilution, 0.15 - 0.4 kg / t of cationic polyacrylamide is added to the surface layer and bottom layer slurries; the core layer slurry is diluted from (3.7 ± 0.2)% after blending to (1.0 ± 0.2)%. After dilution, 6 - 7 kg / t of neutral sizing agent AKD, 10 - 20 kg / t of cationic starch, 5 - 8 kg / t of silica, cationic polyacrylamide, and GCC coated with a filler pretreatment agent are added to the core layer slurry. The addition amount of cationic polyacrylamide is 100 - 300 ppm of the total weight of the slurry.

[0020] Forming on the wire: After the slurry is distributed by a three - layer headbox, it enters the forming wire. Through gravity dewatering, the core layer is first combined with the surface layer, and tapioca native starch is sprayed on the surface layer to enhance the bonding strength. After the surface layer and the core layer are combined, they are then combined with the bottom layer to form a three - layer base paper.

[0021] Pressing: Pass through the first press, second press (shoe press), and third press (gloss press) in sequence to eliminate the wire marks and felt marks. After pressing, the dryness of the base paper reaches 45 - 48%.

[0022] Pre - drying: The temperature of the drying cylinders in the entire pre - drying section needs to be increased from 40 - 50°C to 130 - 140°C to promote the ripening of the neutral sizing agent AKD, cationic starch, and sprayed starch, ensure the printing strength performance after leaving the machine. The dryness of the base paper is increased from 45 - 48% before entering to 93 - 94%, which is beneficial to the penetration of the surface sizing solution.

[0023] Surface sizing: Use enzyme - converted starch (using tapioca native starch as the raw material, diluting it with water to a solid content of 28%, then adding amylase BUZYME 2583, and the dosage of amylase is 320 - 380 ppm. Transfer the prepared starch slurry to an enzyme - conversion tank and carry out a mixing and conversion reaction at 85°C. The conversion time is set to 16 min. After the conversion is completed, perform a high - temperature treatment on the reaction system, and the treatment temperature range is 125 - 135°C. Through the high - temperature effect, the enzyme is inactivated to terminate the enzyme - conversion reaction.) as the surface sizing agent. The viscosity of the sizing solution during preparation is 210 ± 10 cps, the solid content during preparation is 28 ± 1%, the temperature during machine operation is 75 ± 3°C, the viscosity during machine operation is 35 ± 5 cps, the solid content during machine operation is 12 ± 2%, and the sizing amount on both the front and back sides is 4.8 ± 0.5 g / m2 。

[0024] Post-drying: The temperature is 100 - 120°C to ensure that the adhesive solution can be fully cured, increase the surface strength of the paper, and reduce the phenomenon of linting and powdering during printing.

[0025] Hard calendering: The temperature is 170 - 190°C and the pressure is 5 - 20 kN / m. The paper surface is modified through high temperature and high pressure to reduce the roughness of the base paper.

[0026] (2) Coating: Primer coating, intermediate coating, and top coating are successively carried out on both sides of the base paper, and drying is performed after each coating; a hard doctor blade is used for primer coating, and soft doctor blades are used for intermediate coating and top coating.

[0027] (3) Calendering and post-treatment: Soft calendering is carried out on both sides of the coated paper, followed by slitting after curling to obtain high-ash coated art paper. Among them: the temperature of soft calendering is 140 - 160°C, the pressure is 15 - 25 kN / m, the coated surface is finished, the glossiness, smoothness are improved, and the roughness is reduced. Soft calendering is used on both the front and back sides to reduce the two-sided difference.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By using GCC fillers coated with a filler pretreatment agent in the core layer (retention rate ≥ 84%) and optimizing the pulp ratio, the ash content of the formed paper is ≥ 45%. The increase in the ash content of the formed paper directly reduces the raw material cost. At the same time, the high filler ratio in the core layer significantly enhances the stiffness of the paper, with the number of folding resistance times in the CD direction ≥ 30 times and in the MD direction ≥ 22 times; (2) The coating layer adopts a "primer coating / intermediate coating GCC + top coating GCC / clay composite system". The primer coating and intermediate coating ensure that the coating has high hiding power and ink absorption, while the clay in the top coating effectively improves the surface smoothness and glossiness. The adhesive is designed in stages, which not only ensures the adhesion of the coating but also enhances the water resistance, effectively reducing the phenomenon of linting and powdering during printing; (3) Broke is introduced into the core layer pulp, effectively reducing the consumption of virgin pulp. At the same time, through the synergistic effect of neutral sizing agent AKD and cationic starch, the retention rate is improved. The coating process adopts a combination of "hard doctor blade for primer coating + soft doctor blades for intermediate / top coating", combined with soft calendering technology, which ensures accurate coating amount while reducing energy consumption and equipment wear, and is suitable for large-scale industrial production. Specific embodiments

[0029] The following further illustrates the present invention in conjunction with embodiments, but it does not limit the implementation of the present invention.

[0030] Unless otherwise specified, the raw materials used in the examples and comparative examples are all conventional commercially available raw materials, and the process methods used in the examples and comparative examples are all conventional methods in the art.

[0031] Descriptions of some of the raw materials used in the examples and comparative examples are as follows: Filler pretreatment agent FillerTEK DEV 210, purchased from Nalco (China) Environmental Technology Services Co., Ltd.; Filler pretreatment agent FillerTEK DEV 310, purchased from Nalco (China) Environmental Technology Services Co., Ltd.; Bleached softwood kraft pulp, purchased from Arauco Group; Bleached hardwood kraft pulp, purchased from Asia Pulp & Paper Co., Ltd.; Dispersant FLO2288, purchased from SNF (China) Flocculants Co., Ltd.; Bactericide AmiCide BX 9058, purchased from Amazon Papermaking Chemicals Co., Ltd.; Defoamer DF-3000, purchased from Zhucheng Tongshun Rubber Industry Co., Ltd.; Water repellent Ksk386-50, purchased from Zhejiang Kelsi High-Tech Materials Co., Ltd.; Lubricant NCC ® MS-268, purchased from Kyushu Bio (Suzhou) Technology Co., Ltd.; Fluorescent brightener (tetrasulfonate) ABP-C, purchased from Zhejiang Transfar Huayang Chemical Co., Ltd.; Fluorescent brightener (hexasulfonate) HST, purchased from Hebei Shenmao New Material Technology Co., Ltd.; Enzyme BUZYME 2583, purchased from Buckman Laboratories Chemicals (Shanghai) Co., Ltd.; Cassava native starch, purchased from Siam Winthai Industry Co., Ltd. (SWI); The preparation method of the bleached chemi-thermomechanical pulp includes the following steps: Using 90 wt.% poplar and 10 wt.% pine as raw materials, feeding them in a ratio of 1.1:1 based on the mass ratio of raw material wood chips to pulp output. After washing the raw material wood chips, add NaOH for pre-impregnation, and the addition amount of NaOH is 3 wt.% of the raw material wood chips; after pre-impregnation, perform primary grinding, bleaching, secondary grinding and concentration to obtain bleached chemi-thermomechanical pulp. Among them, in the bleaching stage, add a mixed solution of NaOH, H2O2, chelating agent CH-1636 (purchased from Guangdong Liangshi Industrial Materials Co., Ltd.) and stabilizer WT-3066 (purchased from Guangdong Liangshi Industrial Materials Co., Ltd.) with a mass ratio of 1.5:3:0.2:1, and the addition amount of the mixed solution is 5 wt.% of the pulp; the whiteness of the obtained bleached chemi-thermomechanical pulp is 76%, and the bulk is 2.55 ± 0.1 cm3 / g, the tensile index is 22.0 ± 1.0 N·m / g, and the process methods used are all conventional methods in the art.

[0032] In the GCC 60 described above, the content ratio of particles with a particle size ≤ 2 μm is 60 ± 1%. Its preparation method is as follows: The calcium carbonate ore is crushed into coarse particles with a particle size below 5 cm, and then transferred to a ball mill for pre-grinding to obtain an intermediate product with a particle size below 500 μm. Then, a dispersant and zirconium beads are added for wet grinding. After the wet grinding is completed, the ground product is dried to obtain a product with the target particle size; the dispersant is ZH-671 (purchased from Changshu Juhe Chemical Co., Ltd.), and the addition amount of the dispersant is 0.25% of the dry basis mass of the intermediate product.

[0033] In the GCC 98 described above, the content ratio of particles with a particle size ≤ 2 μm is 98 ± 1%. Its preparation method is the same as that of GCC 60, except that the addition amount of the dispersant is 0.65% of the dry basis mass of the intermediate product.

[0034] Example 1 The high-ash coated paper card described above includes a base paper and a coating layer; the base paper is composed of a surface layer, a core layer, and a bottom layer; the basis weight of the base paper is 127 g / m 2 , the basis weight of the surface layer is 27 g / m 2 , the basis weight of the core layer is 73 g / m 2 , the basis weight of the bottom layer is 27 g / m 2 .

[0035] The core layer contains a filler, and its retention rate is 85%; the filler is GCC coated with a filler pretreatment agent obtained by mixing GCC 60, filler pretreatment agent FillerTEK DEV 210, and filler pretreatment agent FillerTEK DEV 310; the addition amount of GCC 60 is 220 kg / t pulp; the weight ratio of filler pretreatment agent FillerTEK DEV 210 to GCC 60 is 3 kg:150 t; the weight ratio of filler pretreatment agent FillerTEK DEV 310 to GCC 60 is 1.5 kg:150 t; The coating layer adopts a three-coating process on both the front and back sides. The front coating and the back coating each include a primer coat, a middle coat, and a top coat; among them, The primer coat paint includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.06 part, dispersant FLO2288: 0.2 part, bactericide AmiCide BX 9058: 0.01 part, defoamer DF-3000: 0.05 part, styrene-butadiene latex: 7.5 parts, coating starch: 4 parts, polyvinyl alcohol: 0.2 part, water repellent Ksk386-50: 0.3 part, lubricant NCC® MS - 268: 0.2 parts, sodium carboxymethyl cellulose: 0.90 parts; The coating for the intermediate coat includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.09 parts, dispersant FLO2288: 0.20 parts, fungicide AmiCide BX 9058: 0.01 parts, defoamer DF - 3000: 0.05 parts, styrene - butadiene latex: 10 parts, polyvinyl alcohol: 0.1 part, water - repellent agent Ksk386 - 50: 0.2 parts, lubricant NCC ® MS - 268: 0.3 parts, sodium carboxymethyl cellulose: 0.90 parts, fluorescent brightener (tetrasulfonic acid) ABP - C: 0.17 parts, fluorescent brightener (hexasulfonic acid) HST: 0.17 parts; The coating for the top coat includes the following components in parts by weight: GCC 98: 87 parts, kaolin: 13 parts, NaOH: 0.06 parts, dispersant FLO2288: 0.2 parts, fungicide AmiCide BX 9058: 0.01 parts, defoamer DF - 3000: 0.05 parts, styrene - butadiene latex: 12 parts, polyvinyl alcohol: 0.25 parts, water - repellent agent Ksk386 - 50: 0.3 parts, lubricant NCC ® MS - 268: 0.2 parts, sodium carboxymethyl cellulose: 0.6 parts, fluorescent brightener (tetrasulfonic acid) ABP - C: 0.16 parts, fluorescent brightener (hexasulfonic acid) HST: 0.16 parts.

[0036] The coating amounts of the primer coat, intermediate coat, and top coat are respectively: 12.5 g / m for the front - side primer coat 2 , 11.0 g / m for the front - side intermediate coat 2 , 13.0 g / m for the front - side top coat 2 ; 12.5 g / m for the back - side primer coat 2 , 11.0 g / m for the back - side intermediate coat 2 , 14.0 g / m for the back - side top coat 2 .

[0037] The surface layer and bottom layer slurries are composed of 20 wt.% bleached softwood kraft pulp and 80 wt.% bleached hardwood kraft pulp.

[0038] The core layer slurry is composed of 8 wt.% bleached softwood kraft pulp, 10 wt.% bleached hardwood kraft pulp, 50 wt.% bleached chemi - thermomechanical pulp, and 32 wt.% broke. The broke includes the waste paper generated in various links of coated card production that fails to be made into the final product.

[0039] The pH of the surface layer, bottom layer, and core layer slurries is 8.0.

[0040] The freeness of the slurries is as follows: bleached softwood kraft pulp: 320 mL, bleached hardwood kraft pulp: 350 mL, bleached chemithermomechanical pulp: 400 mL, broke: 250 mL.

[0041] The preparation method of the high-ash coated paperboard comprises the following steps: (1) Base paper preparation: The slurries of the surface layer, core layer and bottom layer are respectively pulped, ground, mixed and diluted, and then formed on the wire through a three-layer headbox, and then subjected to pressing, pre-drying, surface sizing, post-drying and hard calendering to obtain the base paper; wherein: Pulping: The white water separated during forming is used as the pulping water, and the slurries of the surface layer, core layer and bottom layer are respectively pulped, and the pulping consistency is 5%.

[0042] Grinding: During grinding, the reflux ratio is controlled at 10%.

[0043] Mixing: Mixing is carried out according to the ratio.

[0044] Dilution: The slurries of the surface layer and bottom layer are diluted from (3.2±0.2)% after mixing to (0.3±0.05)%, and after dilution, 0.4 kg / t of cationic polyacrylamide is added to the surface layer slurry, and 0.15 kg / t of cationic polyacrylamide is added to the bottom layer slurry; the core layer slurry is diluted from (3.7±0.2)% after mixing to (1.0±0.2)%, and after dilution, 6 kg / t of neutral sizing agent AKD, 15 kg / t of cationic starch, 6 kg / t of silica, cationic polyacrylamide and GCC coated with a filler pretreatment agent are added to the core layer slurry, and the addition amount of cationic polyacrylamide is 300 ppm of the total weight of the slurry.

[0045] Forming on the wire: After the slurry is distributed by the three-layer headbox, it enters the forming wire, and through gravity dewatering, the core layer is first compounded with the surface layer, and tapioca native starch is sprayed on the surface layer to enhance the bonding strength. After the surface layer and the core layer are compounded, they are then compounded with the bottom layer to form a three-layer base paper.

[0046] Pressing: Passing through the first press, the second press (shoe press) and the third press (gloss press) in sequence to eliminate the wire marks and felt marks, and the dryness of the base paper after pressing reaches 46±1%.

[0047] Pre-drying: The cylinder temperature of the entire pre-drying section needs to be gradually increased from 45±5℃ to 135±5℃, and the dryness of the base paper is increased from 46±1% before entering to 93%.

[0048] Surface sizing: Use enzyme-converted starch (using cassava native starch as raw material, diluting it with water to a solid content of 28%, then adding amylase BUZYME 2583, and the dosage of amylase is 380 ppm. Transfer the prepared starch slurry to an enzyme conversion tank, carry out a mixing and conversion reaction at 85 °C, set the conversion time to 16 min. After the conversion is completed, perform a high-temperature treatment on the reaction system, and the treatment temperature range is 130 °C. Through the high-temperature effect, the enzyme is inactivated, thus terminating the enzyme conversion reaction.) as the surface sizing agent. The viscosity of the sizing solution during preparation is 210 ± 10 cps, the solid content during preparation is 28 ± 1%, the temperature during machine coating is 75 ± 3 °C, the viscosity during machine coating is 35 ± 5 cps, and the solid content during machine coating is 12 ± 2%. The sizing amount on both the front and back sides is 4.8 ± 0.5 g / m 2 .

[0049] Post-drying: The temperature is 110 ± 10 °C.

[0050] Hard calendering: The temperature is 180 ± 10 °C, and the pressure is 5 kN / m.

[0051] (2) Coating: Apply primer coating, intermediate coating, and top coating on both the front and back sides of the base paper in sequence, and dry after each coating; among them, a hard doctor blade is used for primer coating, and soft doctor blades are used for intermediate coating and top coating.

[0052] (3) Calendering and post-treatment: Perform soft calendering on both the front and back sides of the coated paper, cut it after curling to obtain high-ash coated paperboard, where: the temperature of soft calendering is 150 ± 10 °C, and the pressure is 20 kN / m.

[0053] Example 2 The high-ash coated paperboard described above includes a base paper and a coating layer; the base paper is composed of a surface layer, a core layer, and a bottom layer; the basis weight of the base paper is 127 g / m 2 , the basis weight of the surface layer is 27 g / m 2 , the basis weight of the core layer is 73 g / m 2 , the basis weight of the bottom layer is 27 g / m 2 .

[0054] The core layer contains fillers, and its retention rate is 85%; the fillers are: GCC 60 coated with a filler pretreatment agent obtained by mixing filler pretreatment agent FillerTEK DEV 210 and filler pretreatment agent FillerTEK DEV 310; among them, the addition amount of GCC 60 is 180 kg / t of pulp; the weight ratio of filler pretreatment agent FillerTEK DEV 210 to GCC 60 is 3 kg:150 t; the weight ratio of filler pretreatment agent FillerTEK DEV 310 to GCC 60 is 1.5 kg:150 t; The coating layer adopts a three - coating process on both the front and back sides. The front - side coating and the back - side coating each include a primer coat, an intermediate coat, and a top coat. Among them, The primer - coat paint includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.06 part, dispersant FLO2288: 0.2 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 7.5 parts, coating starch: 4 parts, polyvinyl alcohol: 0.2 part, water - repellent Ksk386 - 50: 0.3 part, lubricant NCC ® MS - 268: 0.2 part, sodium carboxymethyl cellulose: 0.90 part; The intermediate - coat paint includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.09 part, dispersant FLO2288: 0.20 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 10 parts, polyvinyl alcohol: 0.1 part, water - repellent Ksk386 - 50: 0.2 part, lubricant NCC ® MS - 268: 0.3 part, sodium carboxymethyl cellulose: 0.90 part, fluorescent brightener (tetrasulfonate) ABP - C: 0.17 part, fluorescent brightener (hexasulfonate) HST: 0.17 part; The top - coat paint includes the following components in parts by weight: GCC 98: 87 parts, kaolin: 13 parts, NaOH: 0.06 part, dispersant FLO2288: 0.2 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 12 parts, polyvinyl alcohol: 0.25 part, water - repellent Ksk386 - 50: 0.3 part, lubricant NCC ® MS - 268: 0.2 part, sodium carboxymethyl cellulose: 0.6 part, fluorescent brightener (tetrasulfonate) ABP - C: 0.16 part, fluorescent brightener (hexasulfonate) HST: 0.16 part.

[0055] The coating amounts of the primer coat, intermediate coat, and top coat are respectively: 13.0 g / m for the front - side primer coat 2 , 12.0 g / m for the front - side intermediate coat 2 , 14.0 g / m for the front - side top coat 2 ; 12.5 g / m for the back - side primer coat 2 , 12.0 g / m for the back - side intermediate coat 2 , 15.0 g / m for the back - side top coat 2 .

[0056] The surface layer and bottom layer slurries are composed of 20 wt.% bleached softwood kraft pulp and 80 wt.% bleached hardwood kraft pulp.

[0057] The core layer slurry consists of 5 wt.% bleached softwood kraft pulp, 5 wt.% bleached hardwood kraft pulp, 50 wt.% bleached chemithermomechanical pulp, and 40 wt.% broke. The broke includes waste paper generated in various links of coated card production that fails to be made into the final product.

[0058] The pH of the surface layer, bottom layer, and core layer slurries is 8.0.

[0059] The freeness of the slurries is as follows: bleached softwood kraft pulp: 320 mL, bleached hardwood kraft pulp: 350 mL, bleached chemithermomechanical pulp: 400 mL, broke: 250 mL.

[0060] The preparation method of the high ash content coated card includes the following steps: (1) Base paper preparation: The slurries of the surface layer, core layer, and bottom layer are respectively subjected to pulping, refining, sizing, and dilution, and then formed on the wire through a three - layer headbox. After pressing, pre - drying, surface sizing, post - drying, and hard calendering, the base paper is obtained. Among them: Pulping: Use the white water separated during forming as the pulping water, and pulp the slurries of the surface layer, core layer, and bottom layer respectively. The pulping concentration is 5%.

[0061] Refining: During refining, the reflux ratio is controlled at 10%.

[0062] Sizing: Sizing is carried out according to the ratio.

[0063] Dilution: The surface layer and bottom layer slurries are diluted from (3.2 ± 0.2)% after sizing to (0.3 ± 0.05)%. After dilution, 0.4 kg / t of cationic polyacrylamide is added to the surface layer slurry, and 0.15 kg / t of cationic polyacrylamide is added to the bottom layer slurry; the core layer slurry is diluted from (3.7 ± 0.2)% after sizing to (1.0 ± 0.2)%. After dilution, 6 kg / t of neutral sizing agent AKD, 15 kg / t of cationic starch, 6 kg / t of silica, cationic polyacrylamide, and GCC coated with a filler pretreatment agent are added to the core layer slurry. The addition amount of cationic polyacrylamide is 300 ppm of the total weight of the slurry.

[0064] Forming on the wire: After the slurry is distributed by the three - layer headbox, it enters the forming wire. Through gravity dewatering, the core layer is first combined with the surface layer, and tapioca native starch is sprayed on the surface layer to enhance the bonding strength. After the surface layer and the core layer are combined, they are then combined with the bottom layer to form a three - layer base paper.

[0065] Pressing: Pass through the first press, second press (shoe press), and third press (gloss press) in sequence to eliminate the wire marks and felt marks. After pressing, the dryness of the base paper reaches 46 ± 1%.

[0066] Pre-drying: The cylinder temperature of the entire pre-drying section needs to be gradually increased from 45 ± 5 °C to 135 ± 5 °C, and the dryness of the base paper is increased from 46 ± 1% before entering to 93%.

[0067] Surface sizing: Use enzyme-converted starch (using cassava native starch as the raw material, diluting it with water to a solid content of 28%, then adding amylase BUZYME 2583, and the dosage of amylase is 380 ppm. Transfer the prepared starch slurry to an enzyme conversion tank, carry out a mixing and conversion reaction at 85 °C, set the conversion time to 16 min, after the conversion is completed, perform a high-temperature treatment on the reaction system, and the treatment temperature range is 130 °C. Through the high-temperature effect, the enzyme is inactivated, thereby terminating the enzyme conversion reaction.) as the surface sizing agent. The viscosity of the prepared sizing solution is 210 ± 10 cps, the prepared solid content is 28 ± 1%, the machine temperature is 75 ± 3 °C, the machine viscosity is 35 ± 5 cps, the machine solid content is 12 ± 2%, and the sizing amount on both the front and back sides is 4.8 ± 0.5 g / m 2 。

[0068] Post-drying: The temperature is 110 ± 10 °C.

[0069] Hard calendering: The temperature is 180 ± 10 °C, and the pressure is 5 kN / m.

[0070] (2) Coating: Apply primer coat, intermediate coat, and top coat on both sides of the base paper in sequence, and dry after each coating; among them, a hard doctor blade is used for primer coat coating, and soft doctor blades are used for intermediate coat and top coat coating.

[0071] (3) Calendering and post-treatment: Soft calender both sides of the coated paper, slit it after curling to obtain high-ash coated paperboard, where: the temperature of soft calendering is 150 ± 10 °C, and the pressure is 20 kN / m.

[0072] Example 3 The high-ash coated paperboard described above includes a base paper and a coating layer; the base paper is composed of a surface layer, a core layer, and a bottom layer; the basis weight of the base paper is 127 g / m 2 ,and the basis weight of the surface layer is 27 g / m 2 ,the basis weight of the core layer is 73 g / m 2 ,and the basis weight of the bottom layer is 27 g / m 2 。

[0073] The core layer described above contains a filler with a retention rate of 87%; the filler is GCC 60 coated with a filler pretreatment agent obtained by mixing filler pretreatment agent FillerTEK DEV 210 and filler pretreatment agent FillerTEK DEV 310; the addition amount of GCC 60 is 150 kg / t pulp; the weight ratio of filler pretreatment agent FillerTEK DEV 210 to GCC 60 is 3 kg:150 t; the weight ratio of filler pretreatment agent FillerTEK DEV 310 to GCC 60 is 1.5 kg:150 t; The coating layer adopts a three - coating process for both the front and back sides. The front - side coating and the back - side coating each include a primer coat, an intermediate coat, and a top coat; among them, The primer - coat coating includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.06 part, dispersant FLO2288: 0.2 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 7.5 parts, coating starch: 4 parts, polyvinyl alcohol: 0.2 part, water - repellent agent Ksk386 - 50: 0.3 part, lubricant NCC ® MS - 268: 0.2 part, sodium carboxymethyl cellulose: 0.90 part; The intermediate - coat coating includes the following components in parts by weight: GCC 60: 100 parts, NaOH: 0.09 part, dispersant FLO2288: 0.20 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 10 parts, polyvinyl alcohol: 0.1 part, water - repellent agent Ksk386 - 50: 0.2 part, lubricant NCC ® MS - 268: 0.3 part, sodium carboxymethyl cellulose: 0.90 part, fluorescent brightener (tetrasulfonate) ABP - C: 0.17 part, fluorescent brightener (hexasulfonate) HST: 0.17 part; The top - coat coating includes the following components in parts by weight: GCC 98: 87 parts, kaolin: 13 parts, NaOH: 0.06 part, dispersant FLO2288: 0.2 part, fungicide AmiCide BX 9058: 0.01 part, defoamer DF - 3000: 0.05 part, styrene - butadiene latex: 12 parts, polyvinyl alcohol: 0.25 part, water - repellent agent Ksk386 - 50: 0.3 part, lubricant NCC ® MS - 268: 0.2 part, sodium carboxymethyl cellulose: 0.6 part, fluorescent brightener (tetrasulfonate) ABP - C: 0.16 part, fluorescent brightener (hexasulfonate) HST: 0.16 part.

[0074] The coating amounts of the primer coat, intermediate coat, and top coat are as follows: primer coat on the front side is 13.5 g / m 2 , intermediate coat on the front side is 12.5 g / m 2 , top coat on the front side is 14.5 g / m 2 ; primer coat on the back side is 13.5 g / m 2 , intermediate coat on the back side is 12.5 g / m 2 , top coat on the back side is 15.5 g / m 2 .

[0075] The surface layer and bottom layer slurries are composed of 25 wt.% bleached softwood sulfate pulp and 75 wt.% bleached hardwood sulfate pulp.

[0076] The core layer slurry is composed of 3 wt.% bleached softwood sulfate pulp, 5 wt.% bleached hardwood sulfate pulp, 50 wt.% bleached chemithermomechanical pulp, and 42 wt.% broke. The broke includes waste paper generated in various links of coated art paper production that cannot be made into the final product.

[0077] The pH values of the surface layer, bottom layer, and core layer slurries are 8.0.

[0078] The freeness of the slurries is as follows: bleached softwood sulfate pulp: 320 mL, bleached hardwood sulfate pulp: 350 mL, bleached chemithermomechanical pulp: 400 mL, broke: 250 mL.

[0079] The preparation method of the high-ash coated art paper includes the following steps: (1) Base paper preparation: After the slurries of the surface layer, core layer, and bottom layer are respectively pulped, refined, mixed, and diluted, they are formed on the wire through a three-layer headbox and then subjected to pressing, pre-drying, surface sizing, post-drying, and hard calendering to obtain the base paper; among them: Pulping: Use the white water separated during forming as the pulping water, and pulp the slurries of the surface layer, core layer, and bottom layer respectively. The pulping concentration is 5%.

[0080] Refining: During refining, the reflux ratio is controlled at 10%.

[0081] Mixing: Mix the slurries according to the ratio.

[0082] Dilution: The surface layer and bottom layer slurries are diluted from (3.2 ± 0.2)% after pulp preparation to (0.3 ± 0.05)%. After dilution, 0.4 kg / t of cationic polyacrylamide is added to the surface layer slurry, and 0.15 kg / t of cationic polyacrylamide is added to the bottom layer slurry; The core layer slurry is diluted from (3.7 ± 0.2)% after pulp preparation to (1.0 ± 0.2)%. After dilution, 6 kg / t of neutral sizing agent AKD, 15 kg / t of cationic starch, 6 kg / t of silica, cationic polyacrylamide and GCC coated with a filler pretreatment agent are added to the core layer slurry. The addition amount of cationic polyacrylamide is 300 ppm of the total weight of the slurry.

[0083] Wire forming: After the slurry is distributed by a three-layer headbox, it enters the forming wire. Through gravity dewatering, the core layer is first combined with the surface layer. Cassava native starch is sprayed on the surface layer to enhance the bonding strength. After the surface layer is combined with the core layer, it is then combined with the bottom layer to form a three-layer base paper.

[0084] Pressing: Pass through the first press, the second press (shoe press) and the third press (gloss press) in sequence to eliminate the wire marks and felt marks. After pressing, the dryness of the base paper reaches 46 ± 1%.

[0085] Pre-drying: The temperature of the entire pre-drying section of the dryer cylinders needs to be gradually increased from 45 ± 5°C to 135 ± 5°C, and the dryness of the base paper is increased from 46 ± 1% before entering to 93%.

[0086] Surface sizing: Use enzyme-converted starch (using cassava native starch as the raw material, diluting it with water to a solid content of 28%, then adding amylase BUZYME 2583, and the dosage of amylase is 380 ppm. Transfer the prepared starch slurry to an enzyme conversion tank and carry out a mixing and conversion reaction at 85°C. The conversion time is set to 16 minutes. After the conversion is completed, perform a high-temperature treatment on the reaction system, and the treatment temperature range is 130°C. Through the high-temperature effect, the enzyme is inactivated, thus terminating the enzyme conversion reaction.) as the surface sizing agent. The viscosity of the sizing solution during preparation is 210 ± 10 cps, the solid content during preparation is 28 ± 1%, the machine-entry temperature is 75 ± 3°C, the machine-entry viscosity is 35 ± 5 cps, the machine-entry solid content is 12 ± 2%, and the sizing amount on both the front and back sides is 4.8 ± 0.5 g / m 2 。

[0087] Post-drying: The temperature is 110 ± 10°C.

[0088] Hard calendering: The temperature is 180 ± 10°C and the pressure is 5 kN / m.

[0089] (2) Coating: Bottom coating, middle coating and top coating are carried out on both the front and back sides of the base paper in sequence, and each layer is dried after coating; Among them, a hard doctor blade is used for bottom coating, and soft doctor blades are used for middle coating and top coating.

[0090] (3) Calendering and Post-treatment: Soft calendering is performed on both sides of the coated paper, followed by slitting after curling to obtain high-ash coated art paper. Among them: the temperature of soft calendering is 150 ± 10 °C, and the pressure is 20 kN / m.

[0091] Comparative Example 1 The difference from Example 1 is that: In the coating formulation of the surface coating, the weight fraction of GCC99 is 89 parts, and the weight fraction of kaolin is 11 parts. Other conditions are the same as in Example 1.

[0092] Comparative Example 2 The difference from Example 2 is that: The coating weight of the front surface coating is 12.0 g / m 2 and the coating weight of the back surface coating is 13.0 g / m 2 Other conditions are the same as in Example 2.

[0093] Performance tests were respectively carried out on the coated art papers prepared in Examples 1 - 3 and Comparative Examples 1 - 2. The test methods are as follows: Basis weight of the formed paper (g / m 2 ) : Tested in accordance with GB / T 451.2 - 2023; Thickness (μm) : Tested in accordance with GB / T 451.3 - 2002; Moisture content (%) : Tested in accordance with GB / T 462 - 2023; Surface roughness (μm) : Tested in accordance with GB / T 22363 - 2008; Folding endurance (times) : Tested in accordance with GB / T 2679.5 - 1995; Interlayer bonding strength (J / m 2 ) : Tested in accordance with GB / T 26203 - 2023; Glossiness (%) : Tested in accordance with GB / T 8941 - 2007; Whiteness (%) : Tested in accordance with GB / T 7974 - 2013; Printing surface strength (m / s) : Tested in accordance with GB / T 22365 - 2008; Ash content of the formed paper (%) : Tested in accordance with GB / T 742 - 2018; The test results are shown in Table 1.

[0094] Table 1 Performance Test Results

[0095] From the test data in Table 1, it can be seen that the ash content of the coated paperboard prepared in Examples 1-3 can all be ≥45%, and other physical property indicators can meet the requirements of coated paperboard. Compared with Example 1, in Example 2, the addition amount of GCC 60 in the core layer is reduced, and the coating amount is increased. While optimizing the core layer of bleached softwood kraft pulp and bleached hardwood kraft pulp to make the ash content of the formed paper reach 45%, the usage amounts of bleached softwood kraft pulp and bleached hardwood kraft pulp can be reduced, and the papermaking cost can be reduced. Compared with Example 1, in Example 3, not only can the cost be further reduced, but also the bleached softwood kraft pulp in the surface layer and the bottom layer is improved, resulting in an improvement in the folding resistance performance (CD&MD) of the paper. In Comparative Example 1, since the number of parts of kaolin in the coating formulation of the surface coating is reduced, the glossiness of both the front and back sides is reduced. In Comparative Example 2, since the coating amounts of the front and back surface coatings are reduced, the surface roughness of both the front and back sides increases, the glossiness decreases, and the ash content of the formed paper decreases.

Claims

1. A high-ash coated art paper, characterized in that, It includes base paper and coating layers; the base paper is composed of a surface layer, a core layer, and a bottom layer; the core layer contains a filler with a retention rate of ≥84%; the filler is GCC coated with a filler pretreatment agent obtained by mixing GCC 60 with the filler pretreatment agent; the addition amount of GCC 60 is 150 - 220 kg / t pulp. The coating layer adopts a three - coating process on both the front and back sides. The front - side coating and the back - side coating each include a primer coat, an intermediate coat, and a top coat. Among them, GCC 60 is used as a filler for the primer coat and the intermediate coat, and a filler composed of GCC 98 and kaolin with a weight ratio of (85 - 88):(12 - 15) is used for the top coat. The coating amount of the front - side top coat is 13.0 - 14.5 g / m 2 , and the coating amount of the back - side top coat is 14.0 - 15.5 g / m 2 ; In the GCC 60, the content ratio of particles with a particle size of ≤2 μm is 59 - 61%. In the GCC 98, the content ratio of particles with a particle size of ≤2 μm is 97 - 99%.

2. The high-ash coated art paper according to claim 1, characterized in that For the base coating, starch, styrene-butadiene latex, and polyvinyl alcohol are used as adhesives, and for the middle coating and surface coating, styrene-butadiene latex and polyvinyl alcohol are used as adhesives.

3. The high-ash coated art paper according to claim 1, characterized in that, The base coating composition further includes a pH regulator, a dispersant, a bactericide, an antifoaming agent, a water repellent, and a lubricant; the middle coating and surface coating compositions further include a pH regulator, a dispersant, a bactericide, an antifoaming agent, a water repellent, a lubricant, and a fluorescent brightening agent.

4. The high-ash coated art paper according to claim 1, wherein The coating amounts of the primer and the intermediate coat are respectively: 12.5 - 13.5 g / m² for the front primer 2 , 11.0 - 12.5 g / m² for the front intermediate coat 2 ; 12.5 - 13.5 g / m² for the back primer 2 , 11.0 - 12.5 g / m² for the back intermediate coat 2 .

5. The high-ash coated art paper according to claim 1, characterized in that, The slurries of the surface layer and the bottom layer are composed of 20 - 25 wt.% bleached kraft softwood pulp and 75 - 80 wt.% bleached kraft hardwood pulp; the slurry of the core layer is composed of 3 - 10 wt.% bleached kraft softwood pulp, 5 - 10 wt.% bleached kraft hardwood pulp, 45 - 55 wt.% bleached chemithermomechanical pulp, and 25 - 47 wt.% broke; the bleached chemithermomechanical pulp is prepared from poplar and pine as raw materials, and is successively subjected to NaOH pre-impregnation, primary refining, bleaching, secondary refining, and concentration; the broke includes waste paper generated in various links of coated art paper production that cannot be made into the final product.

6. The high-ash coated art paper according to claim 5, characterized in that, The freeness of the slurries is as follows: bleached kraft softwood pulp: 310 - 330 mL, bleached kraft hardwood pulp: 340 - 360 mL, bleached chemithermomechanical pulp: 390 - 410 mL, broke: 240 - 260 mL.

7. The preparation method of the high-ash coated copper card according to any one of claims 1-6, characterized in that, It includes the following steps: (1) Base paper preparation: The slurries of the surface layer, the core layer, and the bottom layer are respectively subjected to pulping, refining, sizing, and dilution, then are formed on a three-layer headbox, and are subjected to pressing, pre-drying, surface sizing, post-drying, and hard calendering to obtain the base paper. (2) Coating: The base coating, middle coating, and surface coating are successively applied to both sides of the base paper, and are dried after each coating. (3) Calendering and post-treatment: The coated paper is subjected to soft calendering on both sides, and is slit after coiling.

8. The preparation method of the high-ash coated copper card according to claim 7, characterized in that, In step (1), cationic polyacrylamide is added to the surface layer and bottom layer slurries after dilution.

9. The preparation method of the high-ash coated copper card according to claim 7, characterized in that, In step (1), neutral sizing agent AKD, cationic starch, silica, cationic polyacrylamide, and GCC coated with a filler pretreatment agent are added to the core layer slurry after dilution.

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