Trace coating dictionary paper and preparation method thereof

Abstract

The invention provides trace coating dictionary paper and a preparation method thereof. The preparation method comprises the steps of pulping, pulp mixing, screening, wet paper sheet manufacturing, pre-drying, hard calendaring, coating, post-drying and soft roller calendaring finishing. Based on 100% of oven dry pulp, 0.2-0.4% of carboxymethyl starch is added in the pulping process to assist pulping; a coating used in the coating process is prepared from the following components in parts by weight: 70 to 90 parts of light calcium carbonate, 10 to 30 parts of rutile type titanium dioxide, 5 to 8 parts of styrene-acrylic latex, 15 to 20 parts of coating starch, 1.0 to 2.0 parts of carboxymethylcellulose, 0.3 to 0.5 part of a lubricating agent and 0.3 to 0.5 part of a water repellent agent. The opaqueness of the dictionary paper provided by the invention reaches 88%, the transverse folding endurance is more than 50 times, the printed pattern is clear, the color is full, and the dictionary paper is suitable for high-speed rotary printing and lithographic printing of most head books such as dictionaries, dictionary handbooks, reference books, classics and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking, and in particular relates to a micro-coated dictionary paper and a preparation method thereof. Background Art

[0002] Dictionary paper is a thin high-grade printing paper made of 100% wood pulp fiber. It has the outstanding characteristics of thin paper, low basis weight, high opacity, etc. The paper is thin but strong and fold-resistant, the paper surface is white and delicate, and the texture is tight and smooth. It is mainly used to print dictionaries, manuals, reference books, Bibles and other religious books, advanced classics and other books with many pages, high frequency of use, and easy to carry. In order to save airmail fees, dictionary paper is also used to print materials for air express delivery.

[0003] Dictionary paper has low quantitative and high requirements, and its production is difficult and costly. In the past, my country could only import Bible paper to print some high-end dictionaries and other publications. With the rapid development of my country's economy and cultural publishing, the change in printing methods has led to an increase in the demand for dictionary paper year by year. Therefore, it is urgent to develop a production process for high-quality dictionary paper. Summary of the invention

[0004] The object of the present invention is to provide a micro-coated dictionary paper and a preparation method thereof. The dictionary paper prepared by the present invention has a smooth and delicate surface, high opacity, and good folding strength, and is suitable for high-speed rotary and lithographic printing of dictionaries, encyclopedias, manuals, reference books, classics, etc.

[0005] The invention provides a method for preparing a micro-coated dictionary paper, comprising pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, micro-coating, post-drying and soft roller calendering finishing;

[0006] During the beating process, 0.2-0.4% of the absolute dry pulp mass of carboxymethyl starch is added to assist the beating;

[0007] In the slurry preparation process, 10-15% of the absolute dry slurry mass of filler is added, and the filler is calcined kaolin;

[0008] During the screening process, 0.8-1.5% of the absolute dry pulp weight of sizing agent, 1.2-1.5% of the absolute dry pulp weight of cationic starch, 0.8-1.2% of the absolute dry pulp weight of dry strength agent, 0.06-0.08% of the absolute dry pulp weight of retention aid polyacrylamide, and 0.2-0.4% of the absolute dry pulp weight of modified diatomaceous earth are added;

[0009] The coating used in the micro-coating process includes the following components in parts by weight:

[0010] 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent.

[0011] Preferably, the coniferous wood pulp and the broadleaf wood pulp are used as raw materials for pulping and then pulping, and the mass ratio of the coniferous wood pulp to the broadleaf wood pulp is (30-50): (50-70).

[0012] Preferably, the freeness of the coniferous wood pulp after beating is 100-120 mL, and the freeness of the broadleaf wood pulp after beating is 125-150 mL.

[0013] Preferably, the solid content of the coating used in the micro-coating process is 35-45%.

[0014] Preferably, the pressure of the nip during the micro-coating process is: transmission side / operation side: (17-20) / (17-20) kN / m, the pressure of the metering rod is: upper roller / lower roller: (0.8-1.5) / (0.8-1.5) bar, and the coating amount is 5-6 g / m 2 ; The paper tension setting value of the gluing department is 180~220N / m.

[0015] Preferably, in the soft roller calendering finishing process, calendering treatment is performed using 1 and 7 pressure zones, the hot roller temperatures are 50° C. and 50° C., respectively, and the line pressures are 15 kN / m and 10 kN / m, respectively.

[0016] Preferably, in the papermaking process, the wire speed is 1180 m / min, the pulp-to-wire speed ratio is 1.032, the pressing pressure: first pressure line pressure: 162-168 kN / m, second pressure line pressure: 715-745 kN / m, and the headbox lip opening: 9.0-10.0 mm.

[0017] Preferably, the hard calendering line pressure is 0-10 kN / m, and the paper tension at the hard calendering point is 130-190 N / m.

[0018] The invention provides a micro-coated dictionary paper, which is prepared according to the preparation method described above.

[0019] Preferably, the micro-coated dictionary paper has a basis weight of 30-40 g / m 2 , opacity is 85~90%, transverse folding endurance is 50~100 times, smoothness is 60~100s, and surface strength is 1.5~2.0m / s.

[0020] The invention provides a preparation method of micro-coated dictionary paper, including pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, coating, post-drying and soft roller calendering finishing; 0.2-0.4% of carboxymethyl starch by weight of absolute dry pulp is added to assist pulping during the pulping process; 10-15% of filler by weight of absolute dry pulp is added during the pulping process, and the filler is calcined kaolin; 0.8-1.5% of sizing agent by weight of absolute dry pulp and 1.2-1.5% of cationic starch by weight of absolute dry pulp are added during the screening process. , 0.8-1.2% of the absolute dry pulp mass of dry strength agent, 0.06-0.08% of the absolute dry pulp mass of retention aid polyacrylamide, 0.2-0.4% of the absolute dry pulp mass of modified diatomite; the coating used in the coating process includes the following components in parts by weight: 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent. The present invention uses CMS (carboxymethyl starch) to assist in pulping to improve paper strength and filler retention rate, uses 100% calcined kaolin for filling in the pulp, uses alkenyl succinic anhydride for neutral sizing, and uses light calcium carbonate and rutile titanium dioxide pigment for surface micro-coating, which meets the requirements of dictionary paper products for opacity and folding resistance. The dictionary paper provided by the present invention has an opacity of 88%, a horizontal folding endurance of more than 50 times, clear printed patterns and rich colors, and is suitable for high-speed rotary printing and lithographic printing of large books such as dictionaries, encyclopedias, reference books, and classics. DETAILED DESCRIPTION

[0021] The invention provides a method for preparing a micro-coated dictionary paper, including pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, coating, post-drying and soft roller calendering finishing;

[0022] During the beating process, 0.2-0.4% of the absolute dry pulp mass of carboxymethyl starch is added to assist the beating;

[0023] In the slurry preparation process, 10-15% of the absolute dry slurry mass of filler is added, and the filler is calcined kaolin;

[0024] During the screening process, 0.8-1.5% of the absolute dry pulp weight of sizing agent, 1.2-1.5% of the absolute dry pulp weight of cationic starch, 0.8-1.2% of the absolute dry pulp weight of dry strength agent, 0.06-0.08% of the absolute dry pulp weight of retention aid polyacrylamide, and 0.2-0.4% of the absolute dry pulp weight of modified diatomaceous earth are added;

[0025] The coating used in the coating process includes the following components in parts by weight:

[0026] 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent.

[0027] The present invention preferably uses coniferous wood pulp and hardwood pulp as raw materials to prepare the micro-coated dictionary paper. First, the coniferous wood pulp and hardwood pulp are pulped separately. During the pulping process, CMS (carboxymethyl starch) is added at a rate of 0.2-0.4% of the absolute dry pulp mass to assist in the pulping, preferably 0.2-0.3% CMS (carboxymethyl starch).

[0028] In the present invention, the weight ratio of the coniferous wood pulp to the broadleaf wood pulp is (30-50):(50-70), such as 30:70, 40:60 or 50:50.

[0029] The freeness of the coniferous wood pulp after beating is preferably 100-125 mL, more preferably 105-120 mL, and the freeness of the broadleaf wood pulp after beating is preferably 125-150 mL, more preferably 130-145 mL.

[0030] After beating, the slurry is prepared according to the weight ratio, and then the calcined kaolin filler is added, and then sent to the deslagging device for purification and deslagging through the slurry pump, and then enters the degassing tank for degassing treatment, and then enters the pressure screen for screening treatment, and the first auxiliary material is added at the inlet of the pressure screen, and the second auxiliary material is added at the outlet of the pressure screen.

[0031] In the present invention, the calcined kaolin is a high-temperature calcined modified kaolin. The high-temperature modified calcined kaolin has higher light scattering ability and fiber coverage, and has a larger specific surface area, pore structure and adsorption capacity. The calcined kaolin, retention aids polyacrylamide and modified diatomaceous earth together form a multi-particle retention system. The polyacrylamide retention agent in the particle retention system is added before the slurry pump. It forms a large flocculent group with the slurry, which becomes a tiny, uniform flocculent group with positive charge under the action of the shear force of the slurry pump, opening the structure of the paper sheet. The flocculent group under the shearing effect forms a uniform fine fiber flocculent group with the calcined kaolin and modified diatomaceous earth with high specific surface area, pore structure and negative charge after the pressure screen under the action of surface charge adsorption, forming a very uniform and relatively open structure. While improving the retention rate, the uniformity and water filtration performance of the paper sheet are improved, and the opacity of the paper is significantly improved.

[0032] In the present invention, the addition amount of the calcined kaolin is 10-15% of the absolute dry pulp mass, more preferably 11-14%, such as 10%, 11%, 12%, 13%, 14%, 15%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0033] In the present invention, the first auxiliary material includes 0.8-1.5% of the absolute dry pulp mass of sizing agent, 1.2-1.5% of the absolute dry pulp mass of cationic starch, 0.8-1.2% of the absolute dry pulp mass of dry strength agent, and 600-800ppm of the absolute dry pulp mass of retention aid polyacrylamide.

[0034] In the present invention, the sizing agent is alkenyl succinic anhydride, and the addition amount of the sizing agent is preferably 0.8-1.5% of the absolute dry pulp mass, more preferably 1-1.2%, such as 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, preferably a range value with the above any numerical value as the upper or lower limit; the addition amount of the cationic starch is preferably 1.2-1.5% of the absolute dry pulp mass, more preferably 1.3-1.4%; the addition amount of the dry strength agent is preferably 0.2-0.4% of the absolute dry pulp mass, more preferably 0.2-0.3%; the addition amount of the polyacrylamide is preferably 0.06-0.08% of the absolute dry pulp mass, more preferably 0.065-0.075%, such as 0.060%, 0.065%, 0.070%, 0.075%, 0.080%, preferably a range value with the above any numerical value as the upper or lower limit.

[0035] In the present invention, the second auxiliary material is preferably modified diatomaceous earth, and the added amount of the modified diatomaceous earth is preferably 0.2-0.4% of the absolute dry pulp mass, and more preferably 0.2-0.3%.

[0036] The screened pulp is sent to the headbox to be screened, and the screen flow is adjusted to control the scanned paper weight at 30g / m before sizing. 2 After the wet paper leaves the screen section, it enters the pressing section for secondary composite pressing. After being pressed to a dryness ≥ 39%, it enters the pre-drying section.

[0037] In the present invention, the wire speed in the papermaking process is preferably 1180 m / min, the pulp-to-wire speed ratio is 1.032, the pressing pressure: first pressure line pressure: 162-168 kN / m, second pressure line pressure: 715-745 kN / m, and the headbox lip opening: 9.0-10.0 mm.

[0038] In the present invention, a drying cylinder is used for pre-drying, and the surface temperature of the drying cylinder is preferably 90-130°C, more preferably 100-120°C.

[0039] Dry until the paper sheet dryness is ≥95%, and then enter the size press for micro-coating surface treatment.

[0040] In the present invention, the coating used in the micro-coating process includes the following components in parts by weight:

[0041] 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent.

[0042] In the present invention, the light calcium carbonate is a flaky precipitated calcium carbonate product obtained by limestone calcination, steam drying and airflow screening, and has a flaky morphology. The weight proportion of the light calcium carbonate is preferably 70 to 90 parts, more preferably 75 to 85 parts, such as 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, 81 parts, 82 parts, 83 parts, 84 parts, 85 parts, 86 parts, 87 parts, 88 parts, 89 parts, and 90 parts, preferably a range value with the above arbitrary numerical values ​​as the upper or lower limit.

[0043] In the present invention, the weight proportion of the rutile titanium dioxide is preferably 10 to 30 parts, more preferably 15 to 25 parts, such as 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, preferably a range value with any of the above values ​​as the upper or lower limit.

[0044] The rutile titanium dioxide used in the present invention has fine and uniform particles, high refractive index, high opacity and strong hiding power. Light calcium carbonate has the characteristics of uniform particle size distribution, good suspension, strong hiding power, etc., and shows good opacity, surface smoothness and printing adaptability. The present invention has been shown through a large number of coating tests that the use of rutile titanium dioxide and flaky precipitated calcium carbonate in combination gives full play to the advantages of the high refractive index of rutile titanium dioxide and the flaky structure of light calcium carbonate. The combination of particles of different shapes can obtain a loose coating, giving the base paper better coverage, not only significantly improving the key quality indicators of paper opacity, whiteness, ink absorption, etc., but also greatly reducing the viscosity of the coating, accelerating the dehydration of the coating, and the coating is easier to dry, which meets the needs of the rapid development of coating machines. At the same time, light calcium carbonate replaces expensive titanium dioxide in large quantities, greatly reducing production costs.

[0045] In the present invention, the weight proportion of the styrene acrylic latex is preferably 5 to 8 parts, more preferably 6 to 7 parts. The use of styrene acrylic latex in combination with rutile titanium dioxide and flaky precipitated calcium carbonate pigment can not only greatly improve the opacity and printing performance of paper, but also improve the surface strength and folding strength of paper.

[0046] In the present invention, the weight proportion of the coated starch is preferably 15 to 20 parts, more preferably 16 to 18 parts, such as 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, preferably a range value with any of the above values ​​as the upper or lower limit.

[0047] In the present invention, the weight proportion of the carboxymethyl cellulose is preferably 1.0-2.0 parts, more preferably 1.2-1.8 parts, such as 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, preferably a range value with any of the above values ​​as the upper or lower limit.

[0048] In the present invention, the weight percentage of the lubricant is preferably 0.3-0.5 parts, more preferably 0.3-0.4 parts; the weight percentage of the water repellent is preferably 0.3-0.5 parts, more preferably 0.3-0.4 parts.

[0049] In the present invention, the solid content of the coating used for the micro-coating is preferably 35-45%, more preferably 35-40%, and the coating amount is preferably 5-6 g / m 2 .

[0050] In the present invention, the pressure of the nip during the micro-coating process is: transmission side / operation side: (17~20) / (17~20) kN / m, the pressure of the metering rod is: upper roller / lower roller: (0.8~1.5) / (0.8~1.5) bar, and the paper tension setting value of the gluing section is 180~220 N / m.

[0051] After coating, post-drying is performed, preferably using a drying cylinder for post-drying, and the drying cylinder temperature is preferably 40-130°C, more preferably 50-120°C, and most preferably 80-100°C.

[0052] After post-drying, the paper sheet dryness is ≥93%, and enters the calendering area for soft roller calendering finishing. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃, and the line pressures are 10kN / m and 15kN / m respectively.

[0053] After calendering, the paper is rolled up to obtain the lightly coated dictionary paper.

[0054] The present invention also provides a micro-coated dictionary paper, which is prepared according to the preparation method described above, and the micro-coated dictionary paper has a basis weight of 30-40 g / m 2 , opacity is 85~90%, transverse folding endurance is 50~100 times, smoothness is 60~100s, and surface strength is 1.5~2.0m / s.

[0055] The invention provides a preparation method of micro-coated dictionary paper, including pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, coating, post-drying and soft roller calendering finishing; 0.2-0.4% of carboxymethyl starch by weight of absolute dry pulp is added to assist pulping during the pulping process; 10-15% of filler by weight of absolute dry pulp is added during the pulping process, and the filler is calcined kaolin; 0.8-1.5% of sizing agent by weight of absolute dry pulp and 1.2-1.5% of cationic starch by weight of absolute dry pulp are added during the screening process. , 0.8-1.2% of the absolute dry pulp mass of dry strength agent, 0.06-0.08% of the absolute dry pulp mass of retention aid polyacrylamide, 0.2-0.4% of the absolute dry pulp mass of modified diatomite; the coating used in the coating process includes the following components in parts by weight: 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent. The present invention uses CMS (carboxymethyl starch) to assist in pulping to improve paper strength and filler retention rate, uses 100% calcined kaolin for filling in the pulp, uses alkenyl succinic anhydride for neutral sizing, and uses light calcium carbonate and rutile titanium dioxide pigment for surface micro-coating, which meets the requirements of dictionary paper products for opacity and folding resistance. The dictionary paper provided by the present invention has an opacity of 88%, a horizontal folding endurance of more than 50 times, clear printed patterns and rich colors, and is suitable for high-speed rotary printing and lithographic printing of large books such as dictionaries, encyclopedias, reference books, and classics.

[0056] In order to further illustrate the present invention, a micro-coated dictionary paper and a preparation method thereof provided by the present invention are described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0057] Embodiment 1:

[0058] During the pulping process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after pulping are prepared in a ratio of 30%:70%; then 12% calcined kaolin filler is added, and the pulp is sent to the first-level four-stage conical slag remover for purification and slag removal through a slurry pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, and the screen flow is adjusted to control the scanned paper sheet quantity before sizing at 30g / m 2After the wet paper leaves the screen, it enters the pressing section for two-pass composite pressing. After being pressed to a dryness of ≥39%, it enters the front drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for micro-coating surface treatment: 90 parts of light calcium carbonate, 10 parts of rutile titanium dioxide, 5 parts of styrene-acrylic latex, 22 parts of coating starch, 1.2 parts of CMC, 0.3 parts of lubricant, 0.3 parts of water repellent, and a coating solid content of 35%; Stir evenly, and use a metering rod-type surface sizing machine to coat the reverse side of the paper entering from the front drying section, and control the coating amount to 5g / m 2 , then out of the surface sizing machine, into the post-drying treatment; the wet paper sheet after the micro-coating treatment continues to be post-dried, the temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper sheet out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area, and the paper sheet is calendered. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a quantitative 35g / m 2 , opacity is 86%, transverse folding endurance is 68 times, smoothness is 79s, and surface strength is 1.6m / s. It is a micro-coated dictionary paper.

[0059] Embodiment 2:

[0060] During the pulping process, 0.3% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after pulping are prepared in a ratio of 40%:60%; then 12% calcined kaolin filler is added, and the pulp is sent to the first-stage four-stage conical slag remover for purification and slag removal through a slurry pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, the screen flow is adjusted, and the scanned paper sheet quantity before sizing is controlled to be 30g / m 2After the wet paper leaves the screen, it enters the pressing section for two-pass composite pressing. After being pressed to a dryness of ≥39%, it enters the front drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for micro-coating surface treatment: 80 parts of light calcium carbonate, 20 parts of rutile titanium dioxide, 8 parts of styrene-acrylic latex, 25 parts of coating starch, 1.5 parts of CMC, 0.4 parts of lubricant, 0.4 parts of water repellent, and a coating solid content of 40%; Stir evenly, and use a metering rod-type surface sizing machine to coat the reverse side of the paper entering from the front drying section, and control the coating amount to 6g / m 2 , then out of the surface sizing machine, enter the post-drying treatment; continue to post-dry the wet paper sheets that have been treated with a small amount of coating, control the temperature of the drying cylinder at 40~130℃, and the dryness of the paper sheets out of the post-drying section is ≥93%; the paper sheets entering from the post-drying section enter the calendering area, and the paper sheets are calendered. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a basis weight of 36g / m 2 , opacity is 88%, transverse folding endurance is 78 times, smoothness is 82s, surface strength is 1.8m / s, and the surface is slightly coated dictionary paper.

[0061] Embodiment 3:

[0062] During the pulping process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) that meet the requirements of freeness after pulping are mixed in a ratio of 50%:50%; then 12% calcined kaolin filler is added, and the pulp is sent to the first-level four-stage conical slag remover for purification and slag removal through a slurry pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, and the screen flow is adjusted to control the scanned paper sheet quantity before sizing at 32g / m 2 After the wet paper leaves the screen, it enters the pressing section for secondary composite pressing. After being pressed to a dryness of ≥39%, it enters the front drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for micro-coating surface treatment: 70 parts of light calcium carbonate, 30 parts of rutile titanium dioxide, 8 parts of styrene-acrylic latex, 30 parts of coating starch, 2.0 parts of CMC, 0.4 parts of lubricant, 0.4 parts of water repellent, and a coating solid content of 40%; Stir evenly, and use a metering rod-type surface sizing machine to coat the reverse side of the paper entering from the front drying section, and control the coating amount to 6g / m2 , then out of the surface sizing machine, enter the post-drying treatment; continue to post-dry the wet paper sheets that have been treated with a small amount of coating, control the temperature of the drying cylinder at 40~130℃, and the dryness of the paper sheets out of the post-drying section is ≥93%; the paper sheets entering from the post-drying section enter the calendering area, and the paper sheets are calendered. The calender uses 1+7 pressure zones, and the hot roller temperatures are 50℃ and 50℃, respectively. The line pressure is 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a quantitative 38g / m 2 , opacity is 90%, transverse folding endurance is 90 times, smoothness is 80s, and surface strength is 2.0m / s. Micro-coated dictionary paper.

[0063] Comparative Example 1:

[0064] During the pulping process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after pulping are prepared in a ratio of 30%:70%; then 25% rutile titanium dioxide filler is added, and the pulp is sent to the first-stage four-stage conical slag remover for purification and slag removal through a pulp pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, the screen flow is adjusted, and the scanned paper sheet quantity before sizing is controlled to be 30g / m 2 After the wet paper leaves the screen, it enters the pressing section for secondary composite pressing. After being pressed to a dryness of ≥39%, it enters the pre-drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for starch surface sizing. The solid content of the surface sizing starch is 15%; the sizing amount is 2.5g / m 2 Then it leaves the surface sizing machine and enters the post-drying process. The temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper leaves the post-drying section is ≥93%; the paper leaves from the post-drying section enter the calendering area for calendering. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a basis weight of 35g / m 2 , dictionary paper with opacity of 78%, transverse folding endurance of 55 times, smoothness of 75s, and surface strength of 1.2m / s.

[0065] Comparative Example 2:

[0066] The pulp is directly pulped without adding CMS (carboxymethyl starch) during the pulping process. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) that have been beaten to a freeness requirement of 1 are mixed in a ratio of 30%:70%. Then 25% of rutile titanium dioxide filler is added and sent to a first-stage four-stage conical deslagging device for purification and deslagging through a pulping pump, and then enters a degassing tank for degassing. After that, it enters a pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, the screen flow is adjusted, and the scanned paper sheet quantity before sizing is controlled to be 30g / m 2 After the wet paper leaves the screen, it enters the pressing section for secondary composite pressing. After being pressed to a dryness of ≥39%, it enters the pre-drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for starch surface sizing. The solid content of the surface sizing starch is 15%; the sizing amount is 2.5g / m 2 Then it leaves the surface sizing machine and enters the post-drying process. The temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper leaves the post-drying section is ≥93%; the paper leaves from the post-drying section enter the calendering area for calendering. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a basis weight of 35g / m 2 , dictionary paper with opacity of 76%, transverse folding endurance of 43 times, smoothness of 72s, and surface strength of 1.2m / s.

[0067] Comparative Example 3:

[0068] The pulp is directly pulped without adding CMS (carboxymethyl starch) during the pulping process. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) that have been beaten to a freeness requirement of 1 are mixed in a ratio of 30%:70%. Then 25% of synthetic calcium silicate filler is added and sent to a first-stage four-stage conical slag remover for purification and slag removal through a pulping pump, and then enters a degassing tank for degassing treatment; then enters a pressure screen for screening treatment (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then sent to the headbox for screen, the screen flow is adjusted, and the scanned paper sheet quantity before sizing is controlled to be 30g / m 2After the wet paper leaves the screen, it enters the pressing section for secondary composite pressing. After being pressed to a dryness of ≥39%, it enters the pre-drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for starch surface sizing. The solid content of the surface sizing starch is 15%; the sizing amount is 2.5g / m 2 , then out of the surface sizing machine, into the post-drying treatment; the wet paper sheet after the micro-coating treatment continues to be post-dried, the temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper sheet out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area, and the paper sheet is calendered. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a quantitative 35g / m 2 , dictionary paper with opacity of 75%, transverse folding endurance of 35 times, smoothness of 70s, and surface strength of 1.1m / s.

[0069] Comparative Example 4:

[0070] During the pulping process, 0.2% gCMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after pulping are prepared in a ratio of 30%:70%; then 12% calcined kaolin filler is added, and the pulp is sent to the first-level four-stage conical slag remover for purification and slag removal through a slurry pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, the screen flow is adjusted, and the scanned paper sheet quantity before sizing is controlled to be 30g / m 2 After the wet paper leaves the screen, it enters the pressing section for a second composite pressing. After being pressed to a dryness of ≥39%, it enters the front drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for a slight amount of coating surface treatment: 70 parts of heavy calcium carbonate, 30 parts of kaolin, 5 parts of styrene-acrylic latex, 22 parts of coating starch, 1.2 parts of CMC, 0.3 parts of lubricant, 0.3 parts of water repellent, and a coating solid content of 35%; Stir evenly, and use a metering rod-type surface sizing machine to coat the reverse side of the paper entering from the front drying section, and control the coating amount to 5g / m 2, then out of the surface sizing machine, into the post-drying treatment; the wet paper sheet after the micro-coating treatment continues to be post-dried, the temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper sheet out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area, and the paper sheet is calendered. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a quantitative 35g / m 2 , opacity is 80%, transverse folding endurance is 56 times, smoothness is 76s, surface strength is 1.4m / s, and the paper is slightly coated with dictionary.

[0071] Comparative Example 5:

[0072] During the pulping process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in pulping, and the softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after pulping are prepared in a ratio of 30%:70%; then 12% calcined kaolin filler is added, and the pulp is sent to the first-level four-stage conical slag remover for purification and slag removal through a slurry pump, and then enters the degassing tank for degassing; then enters the pressure screen for screening (cationic PAM dosage 0.06%, cationic starch 1.2%, dry strength agent 1.0%, sizing agent alkenyl succinic anhydride 1.0% are added at the pressure screen inlet, and modified diatomaceous earth 0.22% is added at the pressure screen outlet); then it is sent to the headbox to be screened, and the screen flow is adjusted to control the scanned paper sheet quantity before sizing at 30g / m 2 After the wet paper leaves the screen, it enters the pressing section for a second composite pressing. After being pressed to a dryness of ≥39%, it enters the front drying section. The surface temperature of the drying cylinder is controlled at 90~130°C to dry the paper until the dryness of the paper is ≥95%. It enters the size press for a slight coating surface treatment: 70 parts of heavy calcium carbonate, 30 parts of kaolin, 10 parts of carboxylated styrene butadiene latex, 5 parts of coating starch, 0.5 parts of CMC, 0.3 parts of lubricant, 0.3 parts of water repellent, and a coating solid content of 35%; Stir evenly, and use a metering rod surface sizing machine to coat the reverse side of the paper entering from the front drying section, and control the coating amount to 5g / m 2 , then out of the surface sizing machine, into the post-drying treatment; the wet paper sheet after the micro-coating treatment continues to be post-dried, the temperature of the drying cylinder is controlled at 40~130℃, and the dryness of the paper sheet out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area, and the paper sheet is calendered. The calender uses 1+7 pressure zones, the hot roller temperatures are 50℃ and 50℃ respectively, and the line pressures are 10kN / m and 15kN / m respectively; after calendering, the paper is rolled up to obtain a quantitative 35g / m 2, opacity is 79%, transverse folding endurance is 31 times, smoothness is 75s, and surface strength is 0.9m / s. It is a micro-coated dictionary paper.

[0073] The performance of the dictionary papers obtained in the examples and comparative examples was tested, and the results are shown in Table 1.

[0074] Table 1 Comparison of the performance of dictionary paper in the embodiment and the comparative example

[0075]

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a micro-coated dictionary paper, comprising pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, micro-coating, post-drying and soft roller calendering finishing; During the beating process, 0.2-0.4% of the absolute dry pulp mass of carboxymethyl starch is added to assist the beating; In the slurry preparation process, 10-15% of the absolute dry slurry mass of filler is added, and the filler is calcined kaolin; During the screening process, 0.8-1.5% of the absolute dry pulp weight of sizing agent, 1.2-1.5% of the absolute dry pulp weight of cationic starch, 0.8-1.2% of the absolute dry pulp weight of dry strength agent, 0.06-0.08% of the absolute dry pulp weight of retention aid polyacrylamide, and 0.2-0.4% of the absolute dry pulp weight of modified diatomaceous earth are added; The coating used in the micro-coating process includes the following components in parts by weight: 70-90 parts of light calcium carbonate, 10-30 parts of rutile titanium dioxide, 5-8 parts of styrene-acrylic latex, 15-20 parts of coating starch, 1.0-2.0 parts of carboxymethyl cellulose, 0.3-0.5 parts of lubricant, and 0.3-0.5 parts of water repellent.

2. The preparation method according to claim 1, characterized in that: The coniferous wood pulp and the broadleaf wood pulp are used as raw materials for pulping and then pulping, and the mass ratio of the coniferous wood pulp to the broadleaf wood pulp is (30-50): (50-70).

3. The preparation method according to claim 2, characterized in that: The freeness of the coniferous wood pulp after beating is 100-120 mL, and the freeness of the broadleaf wood pulp after beating is 125-150 mL.

4. The preparation method according to claim 1, characterized in that: The solid content of the coating used in the micro-coating process is 35-45%.

5. The preparation method according to claim 1, characterized in that: The pressure of the nip during the micro-coating process is: transmission side / operation side: (17~20) / (17~20) kN / m, the pressure of the metering rod: upper roller / lower roller: (0.8~1.5) / (0.8~1.5) bar, and the coating amount is 5~6 g / m 2 ; The paper tension setting value of the gluing department is 180~220N / m.

6. The preparation method according to claim 1, characterized in that: During the soft roller calendering finishing process, calendering treatment was performed using pressure zones 1 and 7, the hot roller temperatures were 50° C. and 50° C., and the line pressures were 15 kN / m and 10 kN / m, respectively.

7. The preparation method according to claim 1, characterized in that: In the papermaking process, the wire speed is 1180 m / min, the pulp-to-wire speed ratio is 1.032, the pressing pressure: the first pressing line pressure is 162-168 kN / m, the second pressing line pressure is 715-745 kN / m, and the headbox lip opening is 9.0-10.0 mm.

8. The preparation method according to claim 1, characterized in that: The hard calendering line pressure is 0-10 kN / m, and the paper tension at the hard calendering point is 130-190 N / m.

9. A micro-coated dictionary paper, prepared according to the preparation method according to any one of claims 1 to 8.

10. The micro-coated dictionary paper according to claim 9, characterized in that: The micro-coated dictionary paper has a basis weight of 30-40 g / m 2 , opacity is 85~90%, transverse folding endurance is 50~100 times, smoothness is 60~100s, and surface strength is 1.5~2.0m / s.

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