A method for producing a cultural paper

Abstract

The application discloses a kind of preparation methods of cultural paper, comprising: (1) bleaching pulp is beaten to obtain pulp, and pulp is prepared slurry;(2) adding cationic starch and sizing agent to slurry;(3) adding porous calcium silicate or the mixture of inorganic filler obtained by compounding porous calcium silicate and calcium carbonate;(4) finally adding retention aid and reacting with pulp, then the concentration of paper material is adjusted, and paper sheet is made.The application adds porous calcium silicate or the mixture obtained by compounding porous calcium silicate and calcium carbonate in the process of preparing paper according to the characteristics of high ash content cultural paper, effectively solves the problem of high ash content cultural paper bulkiness, significantly improves the bulkiness of cultural paper, and improves the quality of high ash content cultural paper.The application has strong adaptability, can flexibly adapt to different processes, different varieties of cultural paper production application scenarios, and realizes good balance of product quantity, thickness, ash content and other key indicators.

Description

Technical Field

[0001] This invention relates to a method for preparing paper, and more particularly to a method for preparing cultural paper, belonging to the field of paper preparation. Background Technology

[0002] Paper fillers are the addition of fine white mineral pigments or synthetic fillers to paper stock to alter the optical, physical, and / or printability properties of the paper, thereby meeting certain specific performance requirements. Fillers have a relatively high density, are inexpensive, and can replace some fibers in papermaking, saving raw materials. Furthermore, adding fillers improves paper drying, which is beneficial for increasing paper machine speed, reducing steam consumption, and lowering paper production costs.

[0003] The paper industry uses a variety of fillers, with ground calcium silicate (GCC) and precipitated calcium carbonate (PCC) being the most commonly used fillers for cultural paper. The ash content of cultural papers such as writing paper, offset paper, and copy paper is generally between 10% and 20%. To further reduce production costs, cultural paper manufacturers add as much filler as possible, gradually increasing the ash content to over 20%. However, with the increase in ash content, the paper's physical strength decreases, its absorbency increases, and its bulk decreases. While paper strength and sizing can be improved through optimization of pulp ratios, fiber raw material processing, wet-end chemistry, and surface sizing, the decrease in bulk is a difficult problem to solve for high-ash cultural paper, and effective technical measures and solutions have been lacking.

[0004] To improve paper bulk, paper manufacturers typically use a specific ratio of chemimechanical pulp. While chemimechanical pulp can improve paper bulk to some extent, it presents several problems: the use of chemimechanical pulp leads to varying degrees of decline in the paper's optical, physical, and printability properties, such as reduced paper whiteness; decreased weather resistance, making the paper more prone to yellowing; decreased paper strength, requiring an increase in the amount of softwood pulp in the pulp mix and a higher degree of pulp treatment; deteriorated paper surface properties; and the coarsening of chemimechanical pulp fibers upon contact with water, affecting the paper's printability.

[0005] Therefore, existing methods are not only inefficient in improving the bulk of high-ash cultural paper, but also have a significant adverse impact on the paper's physical properties, printing performance, and user experience, and urgently need to be improved. Summary of the Invention

[0006] The main objective of this invention is to provide a method for preparing cultural paper that can significantly improve the bulk of the prepared paper.

[0007] To achieve this objective, in a basic embodiment, the present invention provides a method for preparing cultural paper, the method comprising:

[0008] A method for preparing cultural paper includes: (1) beating bleached wood pulp to obtain paper pulp, and preparing pulp stock; (2) adding cationic starch and sizing agent to the prepared pulp stock in sequence; (3) adding porous calcium-based filler; (4) finally adding pulp additives to thicken the paper stock, and then forming paper sheets to obtain the paper; wherein the porous calcium-based filler contains porous calcium silicate, and the amount of porous calcium-based filler added is 3%-15% by weight of the pulp stock.

[0009] In a preferred embodiment of the present invention, the amount of porous calcium-based filler added is 7%-8% by weight of the slurry.

[0010] In a preferred embodiment of the present invention, the porous calcium-based filler may be a mixture of porous calcium silicate and calcium carbonate, wherein the proportion of porous calcium silicate accounts for 8-20% by weight of the total mixture; or the porous calcium-based filler may be porous calcium silicate.

[0011] The porous calcium silicate described in this invention has a bulk density of <0.1 g / cm³. 3 The sedimentation volume is >8.0 ml / g, and the D90 is mainly in the range of 35~40 micrometers (D90: 90% of the particles are below 40 micrometers, usually in the range of 35-40 micrometers); more preferably, the whiteness of the porous calcium silicate is above 91% ISO, and the abrasion degree is <5.0 mg / 2000 times.

[0012] The porous calcium silicate provided by this invention exhibits good chemical stability; narrow particle size distribution; excellent optical properties, with a whiteness of over 91% ISO; and extremely low bulk density, <0.1 g / cm³. 3 It has an extremely high settling volume, >8.0 ml / g; and a low abrasion rate, <5.0 mg / 2000 cycles.

[0013] Another aspect of the present invention is to provide a method for preparing the porous calcium silicate, the method comprising: (1) processing quicklime to prepare lime milk; (2) mixing lime milk, quartz sand, caustic soda and water together and performing a hydrothermal synthesis reaction by heating from room temperature to reaction temperature; (3) washing and purifying the product of the synthesis reaction to obtain porous calcium silicate.

[0014] In a preferred embodiment of the present invention, in step (1), quicklime is crushed and then digested, aged, and sieved to prepare lime milk; more preferably, the effective calcium content of the quicklime is >85% and the activity is >300; when the quicklime is crushed and digested, the ratio of quicklime to water is preferably 1:4 to 8; the aging time is preferably 8 to 24 hours; more preferably, quicklime and water are digested at a volume ratio of 1:5, aged for 12 hours, and then sieved to obtain lime milk.

[0015] In a preferred embodiment of the present invention, the quartz sand in step (2) has a SiO2 content > 95%, a loss on ignition < 0.5%, and an average particle size < 20 μm.

[0016] In a preferred embodiment of the present invention, the amount of quartz sand in step (2) is calculated based on SiO2, the amount of caustic soda is calculated based on NaOH, and the amount of lime slurry is calculated based on Ca(OH)2. The molar mass ratio of quartz sand, caustic soda and lime slurry is preferably 1:2 to 4:0.8 to 1.2, and more preferably 1:2.5:1.1.

[0017] In a preferred embodiment of the present invention, the mass ratio of the mixture of quartz sand, caustic soda and lime milk in the synthesis reaction in step (2) to water is 1:4 to 20; preferably 1:9.

[0018] In a preferred embodiment of the present invention, in step (2), the heating rate is controlled at 3℃-5℃ / min when heating from room temperature to reaction temperature, preferably at 3℃ / min; the reaction temperature is preferably 150~190℃, most preferably 150~170℃; the reaction time is preferably 1~5h, most preferably 3h.

[0019] In a preferred embodiment of the present invention, the synthesis reaction in step (2) is preferably carried out under stirring, and the stirring speed is preferably 100-500 rpm, and most preferably 300 rpm.

[0020] The method for preparing porous calcium silicate provided by this invention eliminates the sodium silicate preparation step. In addition, when carrying out the hydrothermal synthesis reaction, the heating rate is controlled at 3℃-5℃ / min when slowly heating from room temperature to the reaction temperature, and the reaction temperature is 150-190℃. This not only significantly shortens the process flow, but also results in the prepared porous calcium silicate product exhibiting improved quality stability, reduced bulk density, and increased sedimentation volume, with significant improvements or enhancements in various properties.

[0021] In a preferred embodiment of the present invention, the wood bleaching pulp beating involves separately beating softwood bleached sulfate pulp and hardwood bleached sulfate pulp to obtain softwood bleached sulfate pulp paper and hardwood bleached sulfate pulp paper respectively; preferably, the softwood bleached sulfate pulp is beated to a freeness of 42. o SR-43 o SR produces coniferous bleached sulfate pulp, and hardwood bleached sulfate pulp is beaten to a freeness of 30. o SR-31 o SR yields bleached sulfate pulp from broadleaf wood.

[0022] In a more preferred embodiment, the pulp is prepared by mixing softwood bleached sulfate pulp and hardwood bleached sulfate pulp in a ratio of 5:95.

[0023] The cationic starch described in this invention is a quaternary ammonium cationic starch, such as corn starch, wheat starch or cassava starch; for reference, the weight of the added cationic starch accounts for 0.5-2.0 wt% of the mixed pulp, preferably 1.0 wt%.

[0024] The sizing agent described in this invention can be any conventional sizing agent in the papermaking industry, and all of these sizing agents are applicable to this invention. As a preferred embodiment, the sizing agent can be AKD, or the composite sizing agent disclosed in CN103422397A can be used. The weight of the added sizing agent accounts for 0.1-0.6 wt% of the mixed pulp, preferably 0.36 wt%.

[0025] The pulp additives described in this invention include: pH adjusters, retention aids, dyes, or bactericides; these are all conventional components and dosages used in the papermaking industry; as a reference embodiment, the pH adjuster may be aluminum sulfate; the retention aid is preferably cationic polyacrylamide (CPAM); the dye is preferably violet blue or violet; the bactericide is a non-oxidizing bactericide, including isothiazolinones and their derivatives, organic bromine compounds, amine compounds, or phenolic compounds, etc.

[0026] In a preferred embodiment of the present invention, the weight of the added retention aid accounts for 0.01-0.08 wt% of the mixed pulp, preferably 0.03 wt%.

[0027] When the amount of porous calcium silicate or a mixture of porous calcium silicate and calcium carbonate added to the pulp is 2.5 wt% of the pulp, the bulk of the product is increased by more than 5%; when the basis weight of the paper remains unchanged, the paper thickness can be effectively increased; and the basis weight of the paper can be effectively reduced while maintaining the paper thickness, with a reduction of more than 4%.

[0028] This invention addresses the specific requirements of high-ash-content cultural paper by adding porous calcium silicate or a mixture of porous calcium silicate and calcium carbonate during the paper preparation process. This effectively solves the problem of reduced bulk in high-ash-content cultural paper, significantly improves the bulk of cultural paper, and ultimately improves the quality of high-ash-content cultural paper.

[0029] The method of this invention is highly adaptable and can flexibly adapt to different processes and different varieties of cultural paper production application scenarios. It can also provide different efficient solutions according to product characteristics and user needs, and achieve a good balance of key indicators such as basis weight, thickness, and ash content. Attached Figure Description

[0030] Figure 1 The particle size distribution diagram is shown for the porous calcium silicate prepared in Comparative Example 2.

[0031] Figure 2 Scanning electron microscope image (×5000) of porous calcium silicate prepared in Preliminary Example 1.

[0032] Figure 3 Scanning electron microscope image (×1000) of the porous calcium silicate prepared in Preliminary Example 1.

[0033] Figure 4 Scanning electron microscope image (×5000) of the porous calcium silicate prepared in Preliminary Example 2.

[0034] Figure 5 Scanning electron microscope image (×1000) of the porous calcium silicate prepared in Preliminary Example 2. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described below with reference to examples.

[0036] The materials used in the following implementation schemes are as follows:

[0037] The quartz sand has a SiO2 content of 97.3%, a loss on ignition of 0.35%, and an average particle size of 14 μm.

[0038] The activity of quicklime is 322, and its effective calcium content is 86-88%.

[0039] Quicklime and water are digested at a volume ratio of 1:5, aged for 12 hours, and then sieved to obtain lime milk.

[0040] Preliminary Example 1: Preparation of Porous Calcium Silicate

[0041] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature, with the heating rate controlled at 3℃ / min. The reaction temperature was 150℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours, and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0042] Preliminary Example 2: Preparation of Porous Calcium Silicate

[0043] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0044] Preliminary Example 3: Preparation of Porous Calcium Silicate

[0045] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 180℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0046] Preliminary Example 4: Preparation of Porous Calcium Silicate

[0047] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 190℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0048] Preliminary Example 5: Preparation of Porous Calcium Silicate

[0049] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 2 hours, and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0050] Preliminary Example 6: Preparation of Porous Calcium Silicate

[0051] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 5 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0052] Preliminary Example 7: Preparation of Porous Calcium Silicate

[0053] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 100 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0054] Preliminary Example 8: Preparation of Porous Calcium Silicate

[0055] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 3℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 500 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0056] Preliminary Example 9: Preparation of Porous Calcium Silicate

[0057] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 5℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0058] Comparative Example 1: Preparation of Porous Calcium Silicate

[0059] Quartz sand, caustic soda, and lime slurry were added to a reactor in a molar ratio of SiO2:NaOH:Ca(OH)2 = 1:2.5:1.1 and mixed with water. The synthesis reaction was carried out by hydrothermal synthesis. The temperature was slowly increased from room temperature to the reaction temperature at a rate of 10℃ / min. The reaction temperature was 170℃. The mass ratio of the mixture of quartz sand, caustic soda, and lime slurry to water was 1:9. The reaction time was 3 hours and the stirring speed was 300 rpm. After the reaction was completed, the mixture was filtered, and the filter cake was washed and dried to obtain porous calcium silicate.

[0060] Table 1. Reaction parameters of Preliminary Examples 1-9 and Comparative Example 1

[0061]

[0062] Comparative Example 2: Preparation and Performance Testing of Porous Calcium Silicate

[0063] Porous calcium silicate was prepared according to the method described in Example 1 of CN104975535A.

[0064] The prepared porous calcium silicate has a wide particle size range and uneven particle size distribution. Although it is mainly distributed in the range of 7-50 micrometers, there are a large number of fine particles smaller than 7 micrometers. Figure 1 ).

[0065] The properties of the porous calcium silicate prepared in this comparative example were tested using the same testing methods as in Preliminary Examples 1-9. The specific test results are as follows: the bulk density of the calcium silicate is 0.25 g / cm³. 3 The sedimentation volume was 3.7 ml / g, the whiteness was 90.2%, the D90 was 30.62 micrometers, and the abrasion resistance was 6.8 mg / 2000 cycles.

[0066] Example 1: Preparation and Testing of Cultural Paper

[0067] The bleached sulfate pulp of coniferous wood and bleached sulfate pulp of broadleaf wood were beaten to achieve a freeness of 42.o SR and 30 o After SR, the two are mixed at a mass ratio of 1:9. Corn starch (1.0 wt%) and sizing agent AKD (alkyl ketene dimer) (0.2 wt%) are added to the mixed pulp in sequence. Then, inorganic composite filler (inorganic composite filler obtained by compounding ground calcium silicate filler and porous calcium silicate prepared in Preliminary Example 1 at a mass ratio of 92:8) is added. Finally, retention aid CPAM (cationic polyacrylamide) is added. After the retention aid, inorganic composite filler and pulp have fully reacted for 3 to 5 minutes, the pulp is thickened, paper sheets are formed, and the paper sheets are calendered.

[0068] The added corn starch accounts for 1.0 wt% of the mixed pulp, the added sizing agent AKD accounts for 0.2 wt% of the mixed pulp, the added inorganic composite filler accounts for 8.0 wt% of the mixed pulp, and the added retention aid cationic polyacrylamide accounts for 0.03 wt% of the mixed pulp.

[0069] Example 2: Preparation and Testing of Cultural Paper

[0070] The bleached sulfate pulp of coniferous wood and bleached sulfate pulp of broadleaf wood were beaten to achieve a freeness of 43. o SR and 30 o After SR, the two are mixed at a mass ratio of 5:95 to obtain mixed pulp. Corn starch and sizing agent AKD are added to the mixed pulp first; then, ground calcium silicate (GCC) filler and inorganic composite filler (7wt%) prepared by compounding porous calcium silicate prepared in preparatory example 2 at a mass ratio of 80:20 are added; finally, retention aid cationic polyacrylamide (CPAM) is added. After the retention aid and inorganic composite filler react fully with the mixed pulp for 3-5 minutes, the pulp is thickened, paper sheets are formed, and the paper sheets are calendered.

[0071] The added corn starch accounts for 1.0 wt% of the mixed pulp, the added sizing agent AKD accounts for 0.2 wt% of the mixed pulp, the added inorganic composite filler accounts for 7.0 wt% of the mixed pulp, and the added retention aid cationic polyacrylamide accounts for 0.03 wt% of the mixed pulp.

[0072] Example 3: Preparation and Testing of Cultural Paper

[0073] The bleached sulfate pulp of coniferous wood and bleached sulfate pulp of broadleaf wood were beaten to achieve a freeness of 42. o SR and 31 oAfter SR, the two are mixed at a mass ratio of 5:95. First, 1.0 wt% corn starch and sizing agent AKD are added to the mixed pulp in sequence. Then, precipitated calcium carbonate (PCC) and porous calcium silicate prepared in Preliminary Example 1 are compounded at a mass ratio of 87:13 to obtain an inorganic composite filler. Finally, retention aid CPAM (0.03 wt%) is added. After the additives, fillers and pulp react fully for 3 to 5 minutes, the pulp is thickened and paper sheets are formed.

[0074] The added corn starch accounts for 1.0 wt% of the mixed pulp, the added sizing agent AKD accounts for 0.36 wt% of the mixed pulp, the added inorganic composite filler accounts for 15.0 wt% of the mixed pulp, and the added retention aid cationic polyacrylamide accounts for 0.03 wt% of the mixed pulp.

[0075] Comparative Example 3: Preparation of Cultural Paper

[0076] Except for the addition of 100% ground calcium silicate (GCC) inorganic filler, everything else is exactly the same as in Example 1.

[0077] Test Example 1: Performance Testing of Porous Calcium Silicate

[0078] The properties of the porous calcium silicate prepared in Preliminary Examples 1-9 and Comparative Example 1 were tested, and the test results are shown in Table 2.

[0079] Table 2 shows the test results of various properties of calcium silicate prepared in Preliminary Examples 1-9 and Comparative Example 1.

[0080]

[0081] Scanning electron microscope (SEM) images of the porous calcium silicate prepared in Preliminary Example 1 are shown below. Figure 2 (×5000) and Figure 3 As shown in (×10000), from Figure 2 and Figure 3 It can be seen that the porous calcium silicate has a good porous structure and a very uniform particle size, with a D90 of 35.04 micrometers. No excessively small or large particle size was found.

[0082] Scanning electron microscope images of porous calcium silicate obtained in Preliminary Example 2 are shown below. Figure 4 (×5000) and Figure 5 As shown in (×10000), from Figure 4 and Figure 5 It can be seen that the porous calcium silicate has a good porous structure, uniform particle size, and a D90 of 36.72 micrometers. No excessively small or large particle size was found.

[0083] The porous calcium silicate prepared in Examples 1-9 of this application has a very uniform particle size, with D90 in the range of 35-40 micrometers, good pore structure, low packing density, and large settling volume.

[0084] In contrast, the porous calcium silicate prepared in Comparative Example 1 has a larger particle size, with a D90 of 52.86 micrometers, a relatively poor pore structure, a higher packing density, and a smaller settling volume.

[0085] Experimental Example 2: Performance Comparison Test of Cultural Paper Prepared in Example 1 and Cultural Paper Prepared in Comparative Example 3

[0086] The performance of the cultural paper prepared in Example 1 and the cultural paper prepared in Comparative Example 3 were tested, and the results are shown in Table 3 below.

[0087] Table 3 shows the performance test results of the cultural paper prepared in Example 1 and the cultural paper prepared in Comparative Example 3.

[0088]

[0089] Table 3 shows that, under the same process conditions, when porous calcium silicate and GCC filler are combined and added, compared with adding GCC filler alone, the bulk of the paper after calendering is increased by 5.6% when the inorganic composite filler content is 24 kg / t paper (2.4% per ton of paper); and the paper thickness can be effectively increased when the basis weight remains unchanged.

[0090] Experimental Example 3: Performance Comparison Test of Cultural Paper Prepared in Example 2 and Cultural Paper Prepared in Comparative Example 3

[0091] The performance of the cultural paper prepared in Example 2 and the cultural paper prepared in Comparative Example 3 were tested, and the test results are shown in Table 4 below.

[0092] Table 4 shows the performance test results of the cultural paper prepared in Example 2 and the cultural paper prepared in Comparative Example 3.

[0093]

[0094] The results in Table 4 show that, under the same process conditions, when porous calcium silicate and GCC filler are combined and added, compared with adding GCC filler alone, the bulk of the paper after calendering is increased by 5.7% when the inorganic composite filler content is 27 kg / t paper (2.7% per ton of paper). Under the premise of maintaining the paper thickness, the basis weight of the paper can be effectively reduced, with a basis weight reduction of more than 4%.

[0095] Experimental Example 3: Performance Comparison Test between Cultural Paper Prepared in Example 3 and Cultural Paper Prepared in Comparative Example 3

[0096] The performance of the cultural paper prepared in Example 3 and the cultural paper prepared in Comparative Example 3 were tested, and the results are shown in Table 5 below.

[0097] Table 5 shows the performance test results of the cultural paper prepared in Example 3 and the cultural paper in Comparative Example 3.

[0098]

[0099] The results in Table 5 show that, under the same process conditions, when the inorganic composite filler obtained by compounding porous calcium silicate and PCC filler is added, compared with the addition of PCC filler alone, the paper thickness before calendering is increased by 6.4% when the inorganic composite filler content is 32 kg / t paper (3.2% per ton of paper). When the basis weight of the paper remains unchanged, it can effectively increase the paper thickness.

[0100] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims and their equivalents, this invention is also intended to include these modifications and variations. The above embodiments or implementations are merely illustrative examples of this invention, and it can also be implemented in other specific ways or forms without departing from its gist or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of this invention should be defined by the appended claims, and any changes equivalent to the intent and scope of the claims should also be included within the scope of this invention.

Claims

1. A method for preparing cultural paper, characterized in that, include: (1) Pulping the bleached wood pulp to obtain paper pulp, and preparing the pulp stock; (2) Adding cationic starch and sizing agent to the prepared pulp stock in sequence; (3) Adding porous calcium-based filler; (4) Adding additives to thicken the pulp stock, and then forming paper sheets to obtain the final product; wherein the porous calcium-based filler is a mixture of porous calcium silicate and calcium carbonate, wherein the proportion of porous calcium silicate accounts for 8-20% by weight of the total mixture of the two, and the amount of porous calcium-based filler added is 3%-15% by weight of the pulp stock; The bulk density of the porous calcium silicate is <0.1 g / cm³. 3 Sedimentation volume > 8.0 ml / g, D90 is in the range of 35-40 micrometers; The method for preparing porous calcium silicate includes: (1) preparing lime milk by processing quicklime; (2) mixing lime milk, quartz sand, caustic soda and water together and performing a hydrothermal synthesis reaction by heating from room temperature to reaction temperature; (3) washing and purifying the product of the synthesis reaction to obtain porous calcium silicate; wherein, in step (2), the heating rate is controlled at 3℃-5℃ / min when heating from room temperature to reaction temperature; the reaction temperature is 150~190℃; and the reaction time is 1~5h.

2. The preparation method according to claim 1, characterized in that, The amount of porous calcium-based filler added accounts for 7%-8% by weight of the slurry.

3. The preparation method according to claim 1, characterized in that, The porous calcium silicate has a whiteness of 91% ISO or higher and an abrasion rate of <5.0 mg / 2000 cycles.

4. The preparation method according to claim 1, characterized in that, The aforementioned wood bleaching pulp beating involves separately beating softwood bleached sulfate pulp and hardwood bleached sulfate pulp to obtain softwood bleached sulfate pulp and hardwood bleached sulfate pulp respectively.

5. The preparation method according to claim 4, characterized in that, Bleached coniferous sulfate pulp was beaten to a freeness of 42. o SR-43 o SR produces coniferous bleached sulfate pulp, and hardwood bleached sulfate pulp is beaten to a freeness of 30. o SR-31 o SR yields bleached sulfate pulp from broadleaf wood.

6. The preparation method according to claim 4, characterized in that, The pulp was prepared by mixing softwood bleached sulfate pulp and hardwood bleached sulfate pulp at a mass ratio of 5:

95.

7. The preparation method according to claim 1, characterized in that, The cationic starch is a quaternary ammonium cationic starch.

8. The preparation method according to claim 7, characterized in that, The cationic starch is selected from corn starch, wheat starch or cassava starch.

9. Cultural paper prepared by any one of the preparation methods of claims 1-8.

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