Microcoated dictionary paper and method of making same

Abstract

The present application provides a kind of micro-coated dictionary paper and its preparation method, including beating, pulp preparation, screening, wet paper sheet papermaking, pre-drying, hard calendering, coating, post-drying and soft roll calender finishing;With 100% of absolute dry pulp as the basis, 0.2~0.4% of carboxymethyl starch is added in the beating process;The coating used in the coating process includes the following components by weight fraction: light calcium carbonate 70~90 parts, rutile titanium dioxide 10~30 parts, styrene-acrylic latex 5~8 parts, coating starch 15~20 parts, carboxymethyl cellulose 1.0~2.0 parts, lubricant 0.3~0.5 parts, water repellent 0.3~0.5 parts.The dictionary paper provided by the present application has an opacity of 88%, a transverse folding endurance of 50 or more, clear and colorful printed patterns, and is suitable for high-speed rotary printing and lithographic printing of large-format books such as dictionaries, dictionaries, manuals, tool books and classics.

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-quality printing paper made from 100% wood pulp. It features thinness, low basis weight, and high opacity. It is thin yet strong and fold-resistant, with a white, delicate surface and a tight, smooth texture. It is primarily used for printing dictionaries, manuals, reference books, Bibles and other religious texts, and other high-level classics—books with many pages, frequent use, and ease of portability. To save on airmail costs, dictionary paper is also used for printing materials for air express delivery.

[0003] Dictionary paper, due to its low quantitative content and high requirements, is difficult and expensive to produce. In the past, my country had to import Bible paper to print high-end dictionaries and other publications. With the rapid development of my country's economy and cultural publishing, changes in printing methods have led to a growing demand for dictionary paper. Therefore, there is an urgent need to develop a production process for high-quality dictionary paper. Summary of the Invention

[0004] The purpose 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 present invention provides a preparation method of 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 in beating;

[0007] During 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 a sizing agent, 1.2-1.5% of the absolute dry pulp weight of a cationic starch, 0.8-1.2% of the absolute dry pulp weight of a dry strength agent, 0.06-0.08% of the absolute dry pulp weight of a 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, softwood pulp and hardwood pulp are used as raw materials for beating and then pulping, and the mass ratio of softwood pulp to hardwood pulp is (30-50): (50-70).

[0012] Preferably, the freeness of the softwood pulp after beating is 100-120 mL, and the freeness of the hardwood 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 in 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 pressure zones 1 and 7, with the hot roller temperatures being 50° C. and 50° C., respectively, and the line pressures being 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 is: first pressure line pressure: 162~168 kN / m, second pressure line pressure: 715~745 kN / m, and the headbox lip opening is 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 present invention provides a preparation method of micro-coated dictionary paper, which includes beating, pulping, screening, wet paper sheet making, pre-drying, hard calendering, coating, post-drying and soft roller calendering finishing; in the pulping process, 0.2-0.4% of carboxymethyl starch by weight of the absolute dry pulp is added to assist the beating; in the pulping process, 10-15% of filler by weight of the absolute dry pulp is added, and the filler is calcined kaolin; in the screening process, 0.8-1.5% of sizing agent by weight of the absolute dry pulp and 1.2-1.5% of cationic starch by weight of the absolute dry pulp are added. , 0.8-1.2% dry strength agent by weight of the absolute dry pulp, 0.06-0.08% polyacrylamide as a retention aid by weight of the absolute dry pulp, and 0.2-0.4% modified diatomaceous earth by weight of the absolute dry pulp. The coating used in the coating process includes the following components by weight: 70-90 parts light calcium carbonate, 10-30 parts rutile titanium dioxide, 5-8 parts styrene-acrylic latex, 15-20 parts coating starch, 1.0-2.0 parts carboxymethyl cellulose, 0.3-0.5 parts lubricant, and 0.3-0.5 parts water repellent. The present invention uses CMS (carboxymethyl starch) to assist in beating to improve paper strength and filler retention, employs 100% calcined kaolin for in-slurry filling, uses alkenyl succinic anhydride for neutral sizing, and uses light calcium carbonate and rutile titanium dioxide pigment for a micro-coating of the surface, meeting the opacity and folding resistance requirements of dictionary paper products. 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 present invention provides a preparation method of micro-coated dictionary paper, comprising 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 in beating;

[0023] During 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 a sizing agent, 1.2-1.5% of the absolute dry pulp weight of a cationic starch, 0.8-1.2% of the absolute dry pulp weight of a dry strength agent, 0.06-0.08% of the absolute dry pulp weight of a 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 pulp and broadleaf pulp as raw materials to prepare micro-coated dictionary paper. First, the coniferous pulp and broadleaf 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 softwood pulp to the hardwood pulp is (30-50): (50-70), such as 30:70, 40:60 or 50:50.

[0029] The freeness of the softwood pulp after beating is preferably 100-125 mL, more preferably 105-120 mL, and the freeness of the hardwood 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 the slurry is sent to the slag remover for purification and slag removal 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 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, together with the retention aids polyacrylamide and modified diatomaceous earth, forms a multi-component microparticle retention system. The polyacrylamide retention agent in this microparticle retention system is added before the slurry pump. It forms large flocs with the slurry, which are transformed into small, uniform, positively charged flocs under the shear force of the slurry pump, thereby opening up the structure of the paper sheet. After the pressure screen, the sheared flocs combine with the high specific surface area, pore structure, and negatively charged calcined kaolin and modified diatomaceous earth to form uniform fine fiber flocs due to surface charge adsorption, forming a very uniform and relatively open structure. While improving the retention rate, the paper sheet uniformity and water filtration performance are improved, and the paper opacity is significantly increased.

[0032] In the present invention, the addition amount of the calcined kaolin is 10-15% of the absolute dry slurry 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 any of the above values ​​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 any of the above values ​​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, more preferably 0.2-0.3%.

[0036] The slurry after screening is sent to the headbox to be put on the screen, and the flow rate on the screen is adjusted to control the scanning paper sheet 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 is: first pressure line pressure: 162~168 kN / m, second pressure line pressure: 715~745 kN / m, and the headbox lip opening is 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] After drying to a paper sheet dryness of ≥95%, it enters 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 any of the above 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, and 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, a high refractive index, high opacity, and strong hiding power. Light calcium carbonate, on the other hand, has the characteristics of uniform particle size distribution, good suspension properties, and strong hiding power, and exhibits good opacity, surface smoothness, and printability. Extensive coating tests have shown that the combination of rutile titanium dioxide and flaky precipitated calcium carbonate fully utilizes 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 produce a loose coating, providing better coverage of the base paper. This not only significantly improves key quality indicators such as paper opacity, whiteness, and ink absorbency, but also significantly reduces coating viscosity, accelerates coating dehydration, and makes the coating easier to dry, adapting to the needs of the rapid development of coating machines. At the same time, light calcium carbonate replaces expensive titanium dioxide in large quantities, significantly 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 the styrene acrylic latex in combination with rutile titanium dioxide and flaky precipitated calcium carbonate pigment can not only significantly improve the opacity and printing performance of the paper, but also improve the surface strength and folding strength of the 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 to 2.0 parts, more preferably 1.2 to 1.8 parts, such as 1.0 part, 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 portion of the lubricant is preferably 0.3 to 0.5 parts, more preferably 0.3 to 0.4 parts; the weight portion of the water repellent is preferably 0.3 to 0.5 parts, more preferably 0.3 to 0.4 parts.

[0049] In the present invention, the solid content of the coating used in 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 in 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 has a dryness of ≥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℃ respectively, 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 present invention provides a preparation method of micro-coated dictionary paper, which includes beating, pulping, screening, wet paper sheet making, pre-drying, hard calendering, coating, post-drying and soft roller calendering finishing; in the pulping process, 0.2-0.4% of carboxymethyl starch by weight of the absolute dry pulp is added to assist the beating; in the pulping process, 10-15% of filler by weight of the absolute dry pulp is added, and the filler is calcined kaolin; in the screening process, 0.8-1.5% of sizing agent by weight of the absolute dry pulp and 1.2-1.5% of cationic starch by weight of the absolute dry pulp are added. , 0.8-1.2% dry strength agent by weight of the absolute dry pulp, 0.06-0.08% polyacrylamide as a retention aid by weight of the absolute dry pulp, and 0.2-0.4% modified diatomaceous earth by weight of the absolute dry pulp. The coating used in the coating process includes the following components by weight: 70-90 parts light calcium carbonate, 10-30 parts rutile titanium dioxide, 5-8 parts styrene-acrylic latex, 15-20 parts coating starch, 1.0-2.0 parts carboxymethyl cellulose, 0.3-0.5 parts lubricant, and 0.3-0.5 parts water repellent. The present invention uses CMS (carboxymethyl starch) to assist in beating to improve paper strength and filler retention, employs 100% calcined kaolin for in-slurry filling, uses alkenyl succinic anhydride for neutral sizing, and uses light calcium carbonate and rutile titanium dioxide pigment for a micro-coating of the surface, meeting the opacity and folding resistance requirements of dictionary paper products. 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 examples, but they should not be understood as limiting the scope of protection of the present invention.

[0057] Example 1:

[0058] During the beating process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 30%:70%. Then 12% calcined kaolin filler is added and 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. After that, it 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 for screen, and the screen flow is adjusted to control the scanned paper sheet quantity at 30g / m3 before sizing. 2After exiting the screen, the wet paper enters the press 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 is ≥95%. The paper enters the size press for a 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, with a coating solid content of 35%. The paper is stirred evenly and coated on the reverse side of the paper entering the pre-drying section using a metering rod-type surface sizing machine, with a coating amount of 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, 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 wound up to obtain a basis weight of 35g / m 2 , opacity is 86%, transverse folding endurance is 68 times, smoothness is 79s, and surface strength is 1.6m / s. Micro-coated dictionary paper.

[0059] Example 2:

[0060] During the beating process, 0.3% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 40%:60%. 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. After that, it 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 for screen, and the screen flow is adjusted to control the scanned paper sheet basis weight at 30g / m before sizing. 2After exiting the screen, the wet paper sheet 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 sheet to a dryness of ≥95%. The paper sheet enters the size press for a 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% are applied. The mixture is stirred evenly, and a metering rod-type surface sizing machine is used to coat the reverse side of the paper sheet entering the pre-drying section, with a coating amount of 6g / 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, 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 wound 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] Example 3:

[0062] During the beating process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 50%:50%. Then 12% calcined kaolin filler is added and 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. After that, it 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 for screen, and the screen flow is adjusted to control the scanned paper sheet basis weight at 32g / m3 before sizing. 2 After exiting the screen, the wet paper sheet 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 sheet to a dryness of ≥95%. The paper sheet enters the size press for a 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% are added. The mixture is stirred evenly and coated on the reverse side of the paper sheet entering the pre-drying section using a metering rod surface sizing machine, with a coating amount controlled at 6g / m2 , 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, the calender uses 1+7 pressure zones, the hot roller temperature is 50℃, the line pressure at 50℃ is 10kN / m and 15kN / m respectively; after calendering, the paper is wound up to obtain a basis weight of 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 beating process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 30%:70%. Then 25% rutile titanium dioxide filler is added and the pulp is sent to a first-stage four-stage conical cleaner for purification and deslagging through a pulp 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, and the screen flow is adjusted to control the scanned paper sheet quantity at 30g / m3 before sizing. 2 After exiting the screen, the wet paper enters the press 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 is ≥95%. The paper enters the size press for starch surface sizing. The solid content of the starch in the surface sizing is 15% and the sizing amount is 2.5g / m 2 Then it leaves the surface sizing machine and enters the post-drying process. The drying cylinder temperature is controlled at 40~130℃. The dryness of the paper sheets leaving the post-drying section is ≥93%. The paper sheets entering the post-drying section enter the calendering area for calendering. The calendering machine 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 wound 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 beaten without adding CMS (carboxymethyl starch) during the beating process. The softwood pulp (100-125 ml) and hardwood pulp (125-150 ml) beaten to the 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 cleaner for purification and deslagging through a slurry 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 for screen, and the screen flow is adjusted to control the scanned paper sheet quantity at 30g / m3 before sizing. 2 After exiting the screen, the wet paper enters the press 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 is ≥95%. The paper enters the size press for starch surface sizing. The solid content of the starch in the surface sizing is 15% and the sizing amount is 2.5g / m 2 Then it leaves the surface sizing machine and enters the post-drying process. The drying cylinder temperature is controlled at 40~130℃. The dryness of the paper sheets leaving the post-drying section is ≥93%. The paper sheets entering the post-drying section enter the calendering area for calendering. The calendering machine 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 wound 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 beaten without adding CMS (carboxymethyl starch) during the beating process. The softwood pulp (100-125 ml) and hardwood pulp (125-150 ml) beaten to the freeness requirement of 1 are mixed in a ratio of 30%:70%. Then 25% of synthetic calcium silicate filler is added and the pulp is sent to a first-stage four-stage conical cleaner through a pulping pump for purification and deslagging. Then it enters the degassing tank for degassing treatment. After that, it enters the 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 it is sent to the headbox to be screened, and the screen flow is adjusted to control the scanned paper sheet quantity at 30g / m3 before sizing. 2After exiting the screen, the wet paper enters the press 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 is ≥95%. The paper enters the size press for starch surface sizing. The solid content of the starch in the surface sizing is 15% and 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, 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 wound up to obtain a basis weight of 35g / m 2 , dictionary paper with opacity of 75%, horizontal folding endurance of 35 times, smoothness of 70s, and surface strength of 1.1m / s.

[0069] Comparative Example 4:

[0070] During the beating process, 0.2% gCMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 30%:70%. Then 12% calcined kaolin filler is added and 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. After that, it 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 exiting the screen, the wet paper sheet 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 sheet to a dryness of ≥95%. The paper sheet enters the size press for a micro-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, with a coating solid content of 35%. The paper sheet is stirred evenly and coated on the reverse side of the paper sheet entering the pre-drying section using a metering rod surface sizing machine, with a coating amount of 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, 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 wound up to obtain a basis weight of 35g / m 2 , opacity is 80%, transverse folding endurance is 56 times, smoothness is 76s, surface strength is 1.4m / s, and the surface is slightly coated dictionary paper.

[0071] Comparative Example 5:

[0072] During the beating process, 0.2% CMS (carboxymethyl starch) is added to the absolute dry pulp to assist in beating. The softwood pulp (100-125ml) and hardwood pulp (125-150ml) with the required freeness after beating are mixed in a ratio of 30%:70%. Then 12% calcined kaolin filler is added and 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. After that, it 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 for screen, and the screen flow is adjusted to control the scanned paper sheet quantity at 30g / m3 before sizing. 2 After exiting the screen, the wet paper sheet 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 sheet to a dryness of ≥95%. The paper sheet enters the size press for a micro-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, with a coating solid content of 35%. The mixture is stirred evenly, and a metering rod-type surface sizing machine is used to coat the reverse side of the paper sheet entering the pre-drying section, with a coating amount of 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 drying cylinder temperature is controlled at 40~130℃, and the paper sheet dryness out of the post-drying section is ≥93%; the paper sheet entering from the post-drying section enters the calendering area for calendering treatment, 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 wound up to obtain a basis weight of 35g / m 2, opacity is 79%, transverse folding endurance is 31 times, smoothness is 75s, surface strength is 0.9m / s, and the lightly 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing lightly coated dictionary paper, comprising pulping, pulping, screening, wet paper sheet making, pre-drying, hard calendering, lightly 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 in beating; During 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 a sizing agent, 1.2-1.5% of the absolute dry pulp weight of a cationic starch, 0.8-1.2% of the absolute dry pulp weight of a dry strength agent, 0.06-0.08% of the absolute dry pulp weight of a retention aid polyacrylamide, and 0.2-0.4% of the absolute dry pulp weight of modified diatomaceous earth are added; The sizing agent is alkenyl succinic anhydride; The coating used in the micro-coating process is composed of the following components in parts by weight: 70-90 parts of flaky 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 solid content of the coating used in the micro-coating process is 35-45%, and the coating amount of the coating used in the micro-coating process is 5-6 g / m 2 .

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

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

4. The preparation method according to claim 1, characterized in that During the micro-coating process, the pressure in the nip zone is as follows: transmission side / operation side: (17-20) / (17-20) kN / m; the pressure of the metering rod is as follows: 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.

5. 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, with the hot roller temperatures being 50° C. and 50° C., and the line pressures being 15 kN / m and 10 kN / m, respectively.

6. The preparation method according to claim 1, characterized in that During the papermaking process, the wire speed is 1180 m / min, the pulp-to-wire speed ratio is 1.032, the pressing pressure is: 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.

7. 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 position is 130-190 N / m.

8. A micro-coated dictionary paper, prepared according to the preparation method according to any one of claims 1 to 7.

9. The micro-coated dictionary paper according to claim 8, 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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