Papermaking method of high-performance digital paper

Abstract

The invention provides a papermaking method of high-performance digital paper, which comprises the following steps: mixing sulfate softwood pulp, bleached sulfate hardwood pulp and alkaline hydrogen peroxide mechanical pulp to form a pulp mixed solution, then adding modified ground calcium carbonate and positive starch, and fully mixing to obtain raw paper pulp for producing raw paper; and coating by adopting film transfer double-sided coating, calendering and modifying the paper surface, and finally coating by using the treating fluid to obtain the high-performance digital paper. According to the invention, the modified calcium carbonate and the starch glue solution are combined with a reasonable coating raw material ratio and a proper treatment solution, so that the performance of the paper can be enhanced, the digital paper can quickly absorb water-based ink, and the ink is high in adhesion degree and high in color reducibility. In addition, according to the high-performance digital paper researched and developed by the invention, water-based ink is used for replacing solvent-based ink, so that environmental pollution caused by organic solvents can be avoided, and the high-performance digital paper adapts to the development trend of green and environmental protection in the world.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking, and in particular to a method for making high-performance digital paper. Background Art

[0002] As an innovative material, digital paper has broad application prospects in the printing field. Good printability is the core technical requirement of digital paper, which determines the performance and effect of digital paper in the printing process.

[0003] With the popularization of computers and the Internet, as well as the concern for environmental quality, digital inkjet printing, especially inkjet printing with water-based ink as the medium, will impact or replace traditional printing technology based on solvent-based inks, which will be an important development trend. In the face of the booming digital inkjet printing technology, the papermaking industry can only better adapt to the rapid development of digital inkjet printing technology by regarding itself as a key link in this "digital inkjet printing" system, paying close attention to the requirements of new digital inkjet printing technology on paper performance, constantly adjusting the composition and surface treatment methods of paper to improve the grade of existing paper products and developing new paper products.

[0004] High-end digital paper needs to have the following excellent properties:

[0005] ① Fast drying performance: Digital inkjet printing is an inkjet printing technology that uses water-based ink as the medium to impact or replace traditional printing technology based on solvent-based inks. It requires paper to have a faster drying time for water-based inks. ② Surface smoothness and color reproduction: Digital paper needs to have a highly smooth surface to ensure that the graphic effects of printed products are delicate and the color reproduction is high. This places high demands on the texture and manufacturing process of paper. ③ Abrasion resistance and water resistance: Digital paper needs to have a certain degree of abrasion resistance during the printing process to ensure the durability of the printing quality. At the same time, digital paper also needs to have a certain degree of water resistance to cope with humidity changes and water-based inks during the printing process. ④ Compatibility with pre-coating liquid: Before printing, a layer of pre-coating liquid is generally applied to inkjet digital paper to improve the printing performance, so the printing base paper must have good compatibility with the pre-coating liquid. ⑤ Printing speed and accuracy: Digital paper needs to be able to adapt to the requirements of high-speed printing equipment to achieve fast and accurate printing. This places high demands on the strength and flatness of the paper. ⑥ Sustainability and environmental protection: Digital paper needs to be sustainable and environmentally friendly to meet the needs of the modern printing industry for environmentally friendly materials. This poses a challenge to the material selection and production process of paper. Summary of the invention

[0006] In view of this, the present invention proposes a high-performance digital paper making method.

[0007] The technical solution of the present invention is achieved in this way:

[0008] A method for making high-performance digital paper comprises the following steps:

[0009] S1: taking kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mixing them in a weight ratio of 65-70:5-12:15-30 to form a pulp mixture;

[0010] S2: Add modified ground calcium carbonate and positive starch to the slurry mixture of step S1 and mix them thoroughly at a rotation speed of 600-800 r / min to obtain base paper pulp; by weight, the base paper pulp includes 70-80% of the slurry mixture, 12-30% of the modified ground calcium carbonate, and 0.6-1.0% of the positive starch; the wire speed is 1200-1300 m / min; the modified ground calcium carbonate includes the following raw materials in parts by weight: 50-60 parts of ground calcium carbonate, 2-4 parts of fatty acid polyvinyl alcohol, 2-4 parts of silane coupling agent, 0.5-1.6 parts of calcium stearate, and 280-320 parts of water;

[0011] S3: using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 160-180 g / m 2 , of which the water content is 4-8%;

[0012] S4: The starch glue is applied to the surface of the base paper by film transfer double-sided sizing process, the low shear viscosity is 10-14cps, and the total sizing amount is 2-3g / m 2 , obtaining a surface-sizing base paper; the starch glue solution comprises the following raw materials in parts by weight: 70-80 parts of starch, 15-20 parts of polyacrylamide, 8-12 parts of polyvinyl alcohol, 8-12 parts of water-soluble cellulose ether, 4-7 parts of sodium hexametaphosphate, and 800-900 parts of water;

[0013] S5: Use film transfer double-sided coating to coat the surface sized base paper once to obtain a primary coated paper; the film transfer coating amount is 10-20g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4~1.8 / 1.4~1.8bar;

[0014] S6: Use film transfer double-sided coating to perform secondary primer coating on the primary primer paper to obtain secondary primer paper; the film transfer coating amount is 8 to 18 g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4~1.8 / 1.4~1.8bar; S7: Scraper coating the secondary primer paper twice, coating one side each time, and then performing mid-coating; mid-coated paper is obtained; mid-coating scraper pressure is 35~60%, and the total coating amount of mid-coating is 18~24g / m 2 ;

[0015] S8: The middle-coated paper is coated with a knife twice, coating one side each time, and then top-coating is performed to obtain top-coated paper; the top-coating knife pressure is 30-55%, and the total top-coating coating amount is 16-22 g / m 2 ;

[0016] S9: The surface of the coated paper is calendered and modified by a super calender, and the calender adopts the 4th and 9th presses at a calendering temperature of 40 to 60° C. and a line pressure of 70 to 90 kN / m to produce a base paper for digital paper;

[0017] S10: coating the digital paper base paper with a treatment liquid to obtain high-performance digital paper; the coating amount of the treatment liquid is 0.3-5g, and the solid content of the treatment liquid is 20-40%; the treatment liquid comprises, by weight: 60-80 parts of trisaccharide, 20-30 parts of diethylene glycol monobutyl ether, 10-20 parts of phosphoric acid, 1-5 parts of benzotriazole, and 0.1-1 part of ethanol.

[0018] Furthermore, in step S2, the preparation process of the modified ground calcium carbonate is: adding silane coupling agent and fatty acid polyvinyl alcohol to water and stirring at a speed of 500-600 r / min for 4-5 minutes, and then adding ground calcium carbonate and calcium stearate and stirring at a speed of 800-1000 r / min for 5-6 minutes to obtain modified ground calcium carbonate.

[0019] Furthermore, in step S4, the starch is one or both of corn starch or tapioca starch.

[0020] Furthermore, in step S4, the preparation process of the starch glue is as follows: starch and 20-30% of the total amount of water are stirred and mixed at a speed of 600-800 r / min, then polyvinyl alcohol is added and stirred and mixed at a speed of 600-800 r / min, the temperature is raised to 90-95°C for reaction for 15-20 minutes, the temperature is lowered to 35-40°C, the remaining water is added and mixed at a speed of 600-800 r / min, and then sodium hexametaphosphate, water-soluble cellulose ether and polyacrylamide are added in sequence and stirred and mixed to obtain starch glue.

[0021] Furthermore, in steps S5 and S6, the coatings of the primary primer and the secondary primer include the following raw materials in parts by weight: 20 to 28 parts of ground calcium carbonate grade 60, 36 to 42 parts of ground calcium carbonate grade 65, 1 to 3 parts of silane coupling agent, 8 to 10 parts of hydroxypropyl starch, 12 to 15 parts of vinyl acetate-ethylene copolymer latex, 0.5 to 1.0 parts of polydimethylsiloxane, 0.10 to 0.16 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butyl alcohol, and 50 to 60 parts of water.

[0022] Furthermore, the coating preparation process of the primary primer and the secondary primer is as follows: under the condition of a stirring speed of 300 to 400 r / min, polydimethylsiloxane, sodium polyacrylate, and tert-butyl alcohol are added to water and stirred for 5 to 6 minutes, then ground calcium carbonate grade 60 and ground calcium carbonate grade 65 are added and stirred and mixed, then a silane coupling agent is added and stirred and mixed, and finally hydroxypropyl starch and vinyl acetate-ethylene copolymer latex are added and stirred and mixed at a speed of 700 to 800 r / min to obtain the coating.

[0023] Furthermore, in step S7, the coating of the mid-coat includes the following raw materials in parts by weight: 40 to 46 parts of ground calcium carbonate grade 60, 36 to 40 parts of ground calcium carbonate grade 65, 2 to 4 parts of silane coupling agent, 8 to 10 parts of hydroxypropyl starch, 9 to 11 parts of bio-latex, 1 to 1.5 parts of polydimethylsiloxane, 0.08 to 0.15 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butanol, and 50 to 70 parts of water.

[0024] Furthermore, the preparation process of the topcoat coating is as follows: under the condition of a stirring speed of 300 to 400 r / min, polydimethylsiloxane, sodium polyacrylate, and tert-butyl alcohol are added to water and stirred for 5 to 6 minutes, then ground calcium carbonate grade 65 and ground calcium carbonate grade 98 are added and stirred and mixed, then a silane coupling agent is added and stirred and mixed, and finally hydroxypropyl starch and bio-latex are added and stirred and mixed at a speed of 700 to 800 r / min to obtain the coating.

[0025] Furthermore, in step S8, the topcoat coating includes the following raw materials in parts by weight: 40 to 46 parts of ground calcium carbonate grade 65, 30 to 38 parts of ground calcium carbonate grade 98, 3 to 5 parts of silane coupling agent, 10 to 15 parts of hydroxypropyl starch, 8 to 11 parts of vinyl acetate-ethylene copolymer latex, 0.5 to 1.2 parts of polydimethylsiloxane, 0.08 to 0.15 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butanol, and 40 to 60 parts of water.

[0026] Furthermore, the preparation process of the topcoat coating is as follows: under the condition of a stirring speed of 300 to 400 r / min, polydimethylsiloxane, sodium polyacrylate, and tert-butyl alcohol are added to water and stirred for 5 to 6 minutes, then ground calcium carbonate grade 65 and ground calcium carbonate grade 98 are added and stirred and mixed, then a silane coupling agent is added and stirred and mixed, and finally hydroxypropyl starch and vinyl acetate-ethylene copolymer latex are added and stirred and mixed at a speed of 700 to 800 r / min to obtain the coating.

[0027] Furthermore, the ground calcium carbonate C60 has a particle size of less than 2 um and a content of 60-62% of the particles; the ground calcium carbonate C65 has a particle size of less than 2 um and a content of 64-66%.

[0028] Furthermore, the ground calcium carbonate C65 has a particle size of less than 2 um and a content of 64-66%; the ground calcium carbonate C98 has a particle size of less than 2 um and a content of 98-100%.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention combines modified calcium carbonate and starch glue with a reasonable coating raw material ratio and a suitable treatment liquid to enhance the performance of paper, so that the paper is fine and smooth with high whiteness, and the obtained digital paper can also quickly absorb water-based ink, and the ink has strong adhesion, no diffusion, strong color reproduction, and fast drying speed, and will not be smudged during printing. Water-based ink can replace solvent-based ink to avoid the pollution of the environment caused by organic solvents, which is green and environmentally friendly.

[0031] In the process of preparing high-performance digital paper, the present invention adopts fatty acid polyvinyl alcohol, silane coupling agent and calcium stearate to jointly modify the ground calcium carbonate, which can improve the dispersion degree of the ground calcium carbonate in the pulp slurry, increase the penetration compatibility of the ground calcium carbonate with other raw materials, make the paper more delicate and smooth, and also improve the absorption and drying time of the ink, and the performance is excellent.

[0032] When preparing starch glue, starch is compounded with polyacrylamide, polyvinyl alcohol and water-soluble cellulose ether to form a cross-linked water-permeable network structure, which can ensure the tensile and folding strength of the paper while promoting the penetration and absorption of water-based ink, preventing diffusion and improving printing effects.

[0033] The production process of the high-performance digital paper of the present invention complies with relevant laws and regulations and meets national environmental protection requirements and various emission standards. DETAILED DESCRIPTION

[0034] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0035] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0036] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0037] Example 1

[0038] The high-performance digital paper making method of this embodiment comprises the following steps:

[0039] S1: taking kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mixing them in a weight ratio of 65:8:30 to form a pulp mixture;

[0040] S2: Add modified ground calcium carbonate and positive starch to the slurry mixture of step S1 and mix them thoroughly at a rotation speed of 800r / min to obtain base paper pulp; by weight, the base paper pulp includes 75% of the slurry mixture, 24.4% of the modified ground calcium carbonate, and 0.6% of the positive starch; the wire speed is 1300m / min; the modified ground calcium carbonate includes the following raw materials in parts by weight: 60 parts of ground calcium carbonate, 3 parts of fatty acid polyvinyl alcohol, 2 parts of silane coupling agent, 1.6 parts of calcium stearate, and 320 parts of water; the preparation process of the modified ground calcium carbonate is: add silane coupling agent and fatty acid polyvinyl alcohol to water and stir for 5 minutes at a rotation speed of 600r / min, then add ground calcium carbonate and calcium stearate and stir for 6 minutes at a rotation speed of 800r / min to obtain modified ground calcium carbonate;

[0041] S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 160g / m 2 , of which the water content is 7%;

[0042] S4: The starch glue is applied to the surface of the base paper using a film transfer double-sided sizing process. The low shear viscosity is 12cps and the total sizing amount is 2.5g / m 2 , obtaining a surface sized base paper; the starch glue solution comprises the following raw materials in parts by weight: 80 parts of corn starch, 15 parts of polyacrylamide, 8 parts of polyvinyl alcohol, 10 parts of water-soluble cellulose ether, 5 parts of sodium hexametaphosphate, and 800 parts of water; the preparation process of the starch glue solution is: stirring and mixing starch and 20% of the total amount of water at a speed of 600r / min, then adding polyvinyl alcohol and stirring and mixing at a speed of 600r / min, heating to 90°C for reaction for 15min, cooling to 35°C, adding the remaining water and mixing at a speed of 600r / min, then adding sodium hexametaphosphate, water-soluble cellulose ether and polyacrylamide in sequence and stirring and mixing to obtain the starch glue solution;

[0043] S5: Use film transfer double-sided coating to coat the surface sized base paper once to obtain a primary coated paper; the film transfer coating amount is 16g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4 / 1.6 bar; the primary primer coating includes the following raw materials in parts by weight: 26 parts of ground calcium carbonate 60 grade, 42 parts of ground calcium carbonate 65 grade, 2 parts of silane coupling agent, 9 parts of hydroxypropyl starch, 15 parts of vinyl acetate-ethylene copolymer latex, 0.5 parts of polydimethylsiloxane, 0.10 parts of sodium polyacrylate, 0.05 parts of tert-butyl alcohol, and 60 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0044] S6: The primary-primed paper is subjected to secondary primer coating by double-sided film transfer coating to obtain secondary primer paper; the film transfer coating amount is 12g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.8 / 1.8bar; the secondary primer coating includes the following raw materials in parts by weight: 25 parts of ground calcium carbonate 60 grade, 40 parts of ground calcium carbonate 65 grade, 1 part of silane coupling agent, 9 parts of hydroxypropyl starch, 14 parts of vinyl acetate-ethylene copolymer latex, 0.8 parts of polydimethylsiloxane, 0.12 parts of sodium polyacrylate, 0.06 parts of tert-butyl alcohol, and 52 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0045] S7: The secondary primer paper is coated twice by a doctor blade, coating one side each time, and then the intermediate coating is performed to obtain the intermediate coated paper; the intermediate coating doctor blade pressure is 60%, and the total intermediate coating amount is 20g / m 2 The coating of the intermediate coating comprises the following raw materials in parts by weight: 45 parts of ground calcium carbonate grade 60, 36 parts of ground calcium carbonate grade 65, 3 parts of silane coupling agent, 8 parts of hydroxypropyl starch, 11 parts of biological latex, 1.2 parts of polydimethylsiloxane, 0.13 parts of sodium polyacrylate, 0.08 parts of tert-butyl alcohol, and 64 parts of water; the content of particles with a particle size of less than 2um in the ground calcium carbonate C60 is 60%; the content of particles with a particle size of less than 2um in the ground calcium carbonate C65 is 65%;

[0046] S8: The middle-coated paper is coated with a knife twice, coating one side each time, and then the top-coated paper is obtained; the top-coating knife pressure is 30%, and the total coating amount of the top-coating is 18g / m 2 The top coating comprises the following raw materials in parts by weight: 43 parts of ground calcium carbonate grade 65, 38 parts of ground calcium carbonate grade 98, 5 parts of silane coupling agent, 12 parts of hydroxypropyl starch, 8 parts of vinyl acetate-ethylene copolymer latex, 1.1 parts of polydimethylsiloxane, 0.12 parts of sodium polyacrylate, 0.08 parts of tert-butyl alcohol, and 50 parts of water; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%; the ground calcium carbonate C98 has a particle size of less than 2um and a content of 98%;

[0047] S9: The surface of the coated paper is calendered and modified by a super calender, and the calender uses the 4th and 9th presses at a calendering temperature of 40°C and a line pressure of 80 kN / m to produce a digital paper base paper;

[0048] S10: coating the digital paper base paper with a treatment liquid to obtain high-performance digital paper; the coating amount of the treatment liquid is 3g, and the solid content of the treatment liquid is 35%; the treatment liquid comprises, by weight: 80 parts of trisaccharide, 25 parts of diethylene glycol monobutyl ether, 16 parts of phosphoric acid, 4 parts of benzotriazole, and 0.8 parts of ethanol.

[0049] Example 2

[0050] The high-performance digital paper making method of this embodiment comprises the following steps:

[0051] S1: taking kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mixing them in a weight ratio of 70:10:18 to form a pulp mixture;

[0052] S2: Add modified ground calcium carbonate and positive starch to the slurry mixture of step S1 and mix them thoroughly at a rotation speed of 600r / min to obtain base paper pulp; by weight, the base paper pulp includes 77% of the slurry mixture, 22% of the modified ground calcium carbonate, and 1.0% of the positive starch; the wire speed is 1200m / min; the modified ground calcium carbonate includes the following raw materials in parts by weight: 50 parts of ground calcium carbonate, 2 parts of fatty acid polyvinyl alcohol, 3.5 parts of silane coupling agent, 0.8 parts of calcium stearate, and 300 parts of water; the preparation process of the modified ground calcium carbonate is: add silane coupling agent and fatty acid polyvinyl alcohol to water and stir for 4 minutes at a rotation speed of 550r / min, then add ground calcium carbonate and calcium stearate and stir for 5 minutes at a rotation speed of 900r / min to obtain modified ground calcium carbonate;

[0053] S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 170g / m 2 , of which the water content is 6%;

[0054] S4: The starch glue is applied to the surface of the base paper using a film transfer double-sided sizing process. The low shear viscosity is 10cps and the total sizing amount is 2g / m 2 , obtaining a surface sized base paper; the starch glue solution comprises the following raw materials in parts by weight: 70 parts of starch composed of corn starch and cassava starch in a mass ratio of 1:1, 20 parts of polyacrylamide, 12 parts of polyvinyl alcohol, 9 parts of water-soluble cellulose ether, 6 parts of sodium hexametaphosphate, and 900 parts of water; the preparation process of the starch glue solution is: stirring and mixing starch and 30% of the total amount of water at a speed of 800r / min, then adding polyvinyl alcohol and stirring and mixing at a speed of 700r / min, heating to 95°C for reaction for 18min, cooling to 40°C, adding the remaining water and mixing at a speed of 800r / min, then adding sodium hexametaphosphate, water-soluble cellulose ether and polyacrylamide in sequence and stirring and mixing to obtain the starch glue solution;

[0055] S5: Use film transfer double-sided coating to coat the surface sized base paper once to obtain a primary coated paper; the film transfer coating amount is 18g / m 2, Primer metering rod pressure: upper roller / lower roller is 1.8 / 1.4 bar; the primary primer coating includes the following raw materials in parts by weight: 20 parts of ground calcium carbonate grade 60, 40 parts of ground calcium carbonate grade 65, 1.5 parts of silane coupling agent, 8 parts of hydroxypropyl starch, 12 parts of vinyl acetate-ethylene copolymer latex, 0.9 parts of polydimethylsiloxane, 0.16 parts of sodium polyacrylate, 0.08 parts of tert-butyl alcohol, and 50 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0056] S6: The primary primed paper is primed twice by double-sided film transfer coating to obtain secondary primed paper; the film transfer coating amount is 18g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.6 / 1.4 bar; the secondary primer coating includes the following raw materials in parts by weight: 22 parts of ground calcium carbonate 60 grade, 37 parts of ground calcium carbonate 65 grade, 3 parts of silane coupling agent, 10 parts of hydroxypropyl starch, 15 parts of vinyl acetate-ethylene copolymer latex, 0.7 parts of polydimethylsiloxane, 0.10 parts of sodium polyacrylate, 0.08 parts of tert-butyl alcohol, and 58 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0057] S7: The secondary primer paper is coated twice by a doctor blade, coating one side each time, and then the intermediate coating is performed to obtain the intermediate coated paper; the intermediate coating doctor blade pressure is 40%, and the total intermediate coating amount is 18g / m 2 The coating of the intermediate coating comprises the following raw materials in parts by weight: 46 parts of ground calcium carbonate grade 60, 38 parts of ground calcium carbonate grade 65, 2.5 parts of silane coupling agent, 9 parts of hydroxypropyl starch, 9 parts of biological latex, 1.5 parts of polydimethylsiloxane, 0.12 parts of sodium polyacrylate, 0.06 parts of tert-butyl alcohol, and 60 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0058] S8: The medium-coated paper is coated with a knife twice, coating one side each time, and then top-coating is performed to obtain top-coated paper; the top-coating knife pressure is 40%, and the total top-coating coating amount is 22g / m 2 The top coating comprises the following raw materials in parts by weight: 42 parts of ground calcium carbonate grade 65, 33 parts of ground calcium carbonate grade 98, 4 parts of silane coupling agent, 13 parts of hydroxypropyl starch, 10 parts of vinyl acetate-ethylene copolymer latex, 1 part of polydimethylsiloxane, 0.09 parts of sodium polyacrylate, 0.07 parts of tert-butyl alcohol, and 50 parts of water; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%; the ground calcium carbonate C98 has a particle size of less than 2um and a content of 98%;

[0059] S9: The surface of the coated paper is calendered and modified by a super calender, and the calender adopts the 4th and 9th presses at a calendering temperature of 60°C and a line pressure of 90 kN / m to produce a digital paper base paper;

[0060] S10: coating the digital paper base paper with a treatment liquid to obtain high-performance digital paper; the coating amount of the treatment liquid is 4g, and the solid content of the treatment liquid is 40%; the treatment liquid comprises, by weight: 75 parts of trisaccharide, 20 parts of diethylene glycol monobutyl ether, 13 parts of phosphoric acid, 5 parts of benzotriazole, and 1 part of ethanol.

[0061] Example 3

[0062] The high-performance digital paper making method of this embodiment comprises the following steps:

[0063] S1: taking kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mixing them in a weight ratio of 68:12:15 to form a pulp mixture;

[0064] S2: Add modified ground calcium carbonate and positive starch to the slurry mixture of step S1 and mix them thoroughly at a rotation speed of 700r / min to obtain base paper pulp; by weight, the base paper pulp includes 80% of the slurry mixture, 19.2% of the modified ground calcium carbonate, and 0.8% of the positive starch; the wire speed is 1250m / min; the modified ground calcium carbonate includes the following raw materials in parts by weight: 56 parts of ground calcium carbonate, 4 parts of fatty acid polyvinyl alcohol, 3 parts of silane coupling agent, 1.2 parts of calcium stearate, and 280 parts of water; the preparation process of the modified ground calcium carbonate is: add silane coupling agent and fatty acid polyvinyl alcohol to water and stir for 5 minutes at a rotation speed of 500r / min, then add ground calcium carbonate and calcium stearate and stir for 6 minutes at a rotation speed of 1000r / min to obtain modified ground calcium carbonate;

[0065] S3: Using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 180g / m 2 , of which the moisture content is 8%;

[0066] S4: The starch glue is applied to the surface of the base paper using a film transfer double-sided sizing process. The low shear viscosity is 14cps and the total sizing amount is 3g / m 2, obtaining a surface sized base paper; the starch glue solution comprises the following raw materials in parts by weight: 76 parts of starch composed of corn starch and cassava starch in a mass ratio of 2:1, 18 parts of polyacrylamide, 10 parts of polyvinyl alcohol, 8 parts of water-soluble cellulose ether, 7 parts of sodium hexametaphosphate, and 800 parts of water; the preparation process of the starch glue solution is: stirring and mixing starch and 30% of the total amount of water at a speed of 700r / min, then adding polyvinyl alcohol and stirring and mixing at a speed of 800r / min, heating to 90°C for reaction for 20min, cooling to 35°C, adding the remaining water and mixing at a speed of 700r / min, then adding sodium hexametaphosphate, water-soluble cellulose ether and polyacrylamide in sequence and stirring and mixing to obtain the starch glue solution;

[0067] S5: Use film transfer double-sided coating to coat the surface sized base paper once to obtain a primary coated paper; the film transfer coating amount is 20g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.6 / 1.6bar; the primary primer coating includes the following raw materials in parts by weight: 28 parts of ground calcium carbonate 60 grade, 36 parts of ground calcium carbonate 65 grade, 3 parts of silane coupling agent, 10 parts of hydroxypropyl starch, 14 parts of vinyl acetate-ethylene copolymer latex, 0.8 parts of polydimethylsiloxane, 0.15 parts of sodium polyacrylate, 0.06 parts of tert-butyl alcohol, and 52 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0068] S6: The primary-primed paper is subjected to secondary primer coating by double-sided film transfer coating to obtain secondary primer paper; the film transfer coating amount is 16 g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4 / 1.8 bar; the secondary primer coating includes the following raw materials in parts by weight: 27 parts of ground calcium carbonate 60 grade, 42 parts of ground calcium carbonate 65 grade, 2.5 parts of silane coupling agent, 9 parts of hydroxypropyl starch, 13 parts of vinyl acetate-ethylene copolymer latex, 1.0 parts of polydimethylsiloxane, 0.14 parts of sodium polyacrylate, 0.08 parts of tert-butyl alcohol, and 50 parts of water; the ground calcium carbonate C60 has a particle size of less than 2um and a content of 60%; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%;

[0069] S7: The secondary primer paper is coated twice by a knife, one side is coated each time, and then the intermediate coating is performed to obtain the intermediate coated paper; the intermediate coating knife pressure is 50%, and the total intermediate coating amount is 24g / m 2The coating of the intermediate coating comprises the following raw materials in parts by weight: 42 parts of ground calcium carbonate grade 60, 40 parts of ground calcium carbonate grade 65, 4 parts of silane coupling agent, 10 parts of hydroxypropyl starch, 10 parts of biological latex, 1.3 parts of polydimethylsiloxane, 0.15 parts of sodium polyacrylate, 0.07 parts of tert-butyl alcohol, and 55 parts of water; the content of particles with a particle size of less than 2um in the ground calcium carbonate C60 is 60%; the content of particles with a particle size of less than 2um in the ground calcium carbonate C65 is 65%;

[0070] S8: The medium-coated paper is coated with a knife twice, coating one side each time, and then top-coating is performed to obtain top-coated paper; the top-coating knife pressure is 50%, and the total top-coating coating amount is 16g / m 2 The top coating comprises the following raw materials in parts by weight: 45 parts of ground calcium carbonate grade 65, 35 parts of ground calcium carbonate grade 98, 3 parts of silane coupling agent, 15 parts of hydroxypropyl starch, 9 parts of vinyl acetate-ethylene copolymer latex, 0.9 parts of polydimethylsiloxane, 0.14 parts of sodium polyacrylate, 0.05 parts of tert-butyl alcohol, and 49 parts of water; the ground calcium carbonate C65 has a particle size of less than 2um and a content of 65%; the ground calcium carbonate C98 has a particle size of less than 2um and a content of 98%;

[0071] S9: The surface of the coated paper is calendered and modified by a super calender, and the calender adopts the 4th and 9th presses at a calendering temperature of 50°C and a line pressure of 70 kN / m to produce a digital paper base paper;

[0072] S10: coating the digital paper base paper with a treatment liquid to obtain high-performance digital paper; the coating amount of the treatment liquid is 2g, and the solid content of the treatment liquid is 30%; the treatment liquid comprises, by weight: 70 parts of trisaccharide, 30 parts of diethylene glycol monobutyl ether, 18 parts of phosphoric acid, 2 parts of benzotriazole, and 0.3 parts of ethanol.

[0073] Comparative Example 1

[0074] This comparative example is based on Example 3, but the ground calcium carbonate is not modified, and the rest is the same as Example 3. That is, the modified ground calcium carbonate is replaced with the ground calcium carbonate raw material. The process of step S2 of this comparative example is as follows:

[0075] S2: Add modified ground calcium carbonate and positive starch to the pulp mixture of step S1 and mix them thoroughly at a rotation speed of 700 r / min to obtain base paper pulp; by weight, the base paper pulp includes 80% of the pulp mixture, 19.2% of the ground calcium carbonate, and 0.8% of the positive starch; the wire speed is 1250 m / min.

[0076] Comparative Example 2

[0077] This comparative example is based on Example 3, except that the raw material composition and proportion of the starch glue are adjusted, and the rest is the same as Example 3.

[0078] The starch glue solution comprises the following raw materials in parts by weight: 84 parts of starch, 28 parts of polyvinyl alcohol, 7 parts of sodium hexametaphosphate, and 800 parts of water;

[0079] The preparation process of the starch glue solution is as follows: starch and 30% of the total amount of water are stirred and mixed at a rotation speed of 700 r / min, then polyvinyl alcohol is added and stirred and mixed at a rotation speed of 800 r / min, the temperature is raised to 90° C. for reaction for 20 minutes, the temperature is lowered to 35° C., the remaining water is added and mixed at a rotation speed of 700 r / min, and then sodium hexametaphosphate is added and stirred and mixed to obtain the starch glue solution.

[0080] The high-performance digital paper prepared according to the methods of the above-mentioned Examples 1-3 and Comparative Examples 1-2 was subjected to performance testing, and the test process and method are as follows:

[0081] (1) Color density: The high-performance digital paper prepared in Examples 1-4 and Comparative Examples 1-2 was printed with CMYK color blocks using a digital printing press, and the color density of each color block was measured using Xrite.

[0082] (2) Water absorption: refer to GB / T 1540-2002;

[0083] (3) Glossiness: refer to T48;

[0084] (4) ISO whiteness: refer to ISO2470;

[0085] The results are shown in Table 1.

[0086] Table 1 Performance test results of high-performance digital paper

[0087]

[0088] The above results show that the methods of Examples 1-3 of the present invention can make the paper have excellent printing performance. Its color density is good, and the image and text are bright in color, the ink is full, the ink adhesion is strong, and the color reproduction is strong. At the same time, the water absorption performance is good, and the ink can be quickly penetrated, absorbed, dried and not diffused, and the drying time is less than 5s. Compared with Example 3, Comparative Example 1 does not modify the ground calcium carbonate, and the raw material ratio of the starch glue in Comparative Example 2 is different. The glossiness and whiteness of the paper are reduced, and the color density of the paper is reduced. During the printing process, the absorption and drying speed of the paper for the water-based ink is reduced.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for making high-performance digital paper, characterized in that: The following steps are involved: S1: taking kraft softwood pulp, bleached kraft hardwood pulp and alkaline hydrogen peroxide mechanical pulp, and mixing them in a weight ratio of 65-70:5-12:15-30 to form a pulp mixture; S2: Add modified ground calcium carbonate and positive starch to the slurry mixture of step S1 and mix them thoroughly at a rotation speed of 600-800 r / min to obtain base paper pulp; by weight, the base paper pulp includes 70-80% of the slurry mixture, 12-30% of the modified ground calcium carbonate, and 0.6-1.0% of the positive starch; the wire speed is 1200-1300 m / min; the modified ground calcium carbonate includes the following raw materials in parts by weight: 50-60 parts of ground calcium carbonate, 2-4 parts of fatty acid polyvinyl alcohol, 2-4 parts of silane coupling agent, 0.5-1.6 parts of calcium stearate, and 280-320 parts of water; S3: using the base paper pulp obtained in step S2 to produce base paper, the base paper produced has a basis weight of 160-180 g / m 2 , of which the water content is 4-8%; S4: The starch glue is applied to the surface of the base paper by film transfer double-sided sizing process, the low shear viscosity is 10-14cps, and the total sizing amount is 2-3g / m 2 , obtaining a surface-sizing base paper; the starch glue solution comprises the following raw materials in parts by weight: 70-80 parts of starch, 15-20 parts of polyacrylamide, 8-12 parts of polyvinyl alcohol, 8-12 parts of water-soluble cellulose ether, 4-7 parts of sodium hexametaphosphate, and 800-900 parts of water; S5: Use film transfer double-sided coating to coat the surface sized base paper once to obtain a primary coated paper; the film transfer coating amount is 10-20g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4~1.8 / 1.4~1.8bar; S6: Use film transfer double-sided coating to perform secondary primer coating on the primary primer paper to obtain secondary primer paper; the film transfer coating amount is 8 to 18 g / m 2 , Primer metering rod pressure: upper roller / lower roller is 1.4~1.8 / 1.4~1.8bar; S7: The secondary primer paper is coated twice by a knife, one side is coated each time, and then the intermediate coating is performed to obtain the intermediate coated paper; the intermediate coating knife pressure is 35-60%, and the total coating amount of the intermediate coating is 18-24 g / m 2 ; S8: The middle-coated paper is coated with a knife twice, coating one side each time, and then top-coating is performed to obtain top-coated paper; the top-coating knife pressure is 30-55%, and the total top-coating coating amount is 16-22 g / m 2 ; S9: The surface of the coated paper is calendered and modified by a super calender, and the calender adopts the 4th and 9th presses at a calendering temperature of 40 to 60° C. and a line pressure of 70 to 90 kN / m to produce a base paper for digital paper; S10: coating the digital paper base paper with a treatment liquid to obtain high-performance digital paper; the coating amount of the treatment liquid is 0.3-5g, and the solid content of the treatment liquid is 20-40%; the treatment liquid comprises, by weight: 60-80 parts of trisaccharide, 20-30 parts of diethylene glycol monobutyl ether, 10-20 parts of phosphoric acid, 1-5 parts of benzotriazole, and 0.1-1 part of ethanol.

2. The high-performance digital paper making method according to claim 1, characterized in that: In step S2, the preparation process of the modified ground calcium carbonate is: adding silane coupling agent and fatty acid polyvinyl alcohol into water and stirring at a speed of 500-600 r / min for 4-5 minutes, then adding ground calcium carbonate and calcium stearate and stirring at a speed of 800-1000 r / min for 5-6 minutes to obtain modified ground calcium carbonate.

3. The high-performance digital paper making method according to claim 1, characterized in that: In step S4, the starch is one or both of corn starch and tapioca starch.

4. The high-performance digital paper making method according to claim 1, characterized in that: In step S4, the preparation process of the starch glue is as follows: starch and 20-30% of the total amount of water are stirred and mixed at a speed of 600-800 r / min, then polyvinyl alcohol is added and stirred and mixed at a speed of 600-800 r / min, the temperature is raised to 90-95°C for reaction for 15-20 minutes, the temperature is lowered to 35-40°C, the remaining water is added and mixed at a speed of 600-800 r / min, and then sodium hexametaphosphate, water-soluble cellulose ether and polyacrylamide are added in sequence and stirred and mixed to obtain starch glue.

5. The high-performance digital paper making method according to claim 1, characterized in that: In steps S5 and S6, the coatings of the primary primer and the secondary primer include the following raw materials in parts by weight: 20 to 28 parts of ground calcium carbonate grade 60, 36 to 42 parts of ground calcium carbonate grade 65, 1 to 3 parts of silane coupling agent, 8 to 10 parts of hydroxypropyl starch, 12 to 15 parts of vinyl acetate-ethylene copolymer latex, 0.5 to 1.0 parts of polydimethylsiloxane, 0.10 to 0.16 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butyl alcohol, and 50 to 60 parts of water.

6. The high-performance digital paper making method according to claim 1, characterized in that: In step S7, the coating of the middle coating includes the following raw materials in parts by weight: 40 to 46 parts of ground calcium carbonate grade 60, 36 to 40 parts of ground calcium carbonate grade 65, 2 to 4 parts of silane coupling agent, 8 to 10 parts of hydroxypropyl starch, 9 to 11 parts of bio-latex, 1 to 1.5 parts of polydimethylsiloxane, 0.08 to 0.15 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butyl alcohol, and 50 to 70 parts of water.

7. The high-performance digital paper making method according to claim 1, characterized in that: In step S8, the topcoat coating includes the following raw materials in parts by weight: 40 to 46 parts of ground calcium carbonate grade 65, 30 to 38 parts of ground calcium carbonate grade 98, 3 to 5 parts of silane coupling agent, 10 to 15 parts of hydroxypropyl starch, 8 to 11 parts of vinyl acetate-ethylene copolymer latex, 0.5 to 1.2 parts of polydimethylsiloxane, 0.08 to 0.15 parts of sodium polyacrylate, 0.05 to 0.08 parts of tert-butyl alcohol, and 40 to 60 parts of water.

8. The high-performance digital paper making method according to any one of claims 2 to 4, characterized in that: The ground calcium carbonate C60 has a particle size of less than 2 um and a content of 60-62% of the particles; the ground calcium carbonate C65 has a particle size of less than 2 um and a content of 64-66%.

9. The method for making high-performance digital paper according to claim 5, characterized in that: The ground calcium carbonate C65 has a particle size of less than 2 um and a content of 64-66% of the particles; the ground calcium carbonate C98 has a particle size of less than 2 um and a content of 98-100% of the particles.

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