A multi-element composite papermaking filler coating treatment agent, a preparation method and application thereof

Abstract

The application provides a multi-element composite papermaking filler coating treatment agent, a preparation method and application thereof, and belongs to the papermaking filler treatment field. The preparation method of the multi-element composite papermaking filler coating treatment agent comprises the following steps: a polymerization reaction, preparation of a first component, and preparation of a second component. The multi-element composite papermaking filler coating treatment agent, the preparation method and application thereof can effectively improve the retention rate of papermaking fillers in paper and the single-pass retention rate of papermaking, improve the distribution uniformity and bonding state of the papermaking fillers in paper, and avoid the adverse effects of a large amount of papermaking fillers on the performance of paper. While increasing the content of papermaking fillers in paper, the mechanical performance, printing performance of paper are simultaneously improved, the drainage and running performance of a paper machine are improved, and the high-temperature storage stability of the papermaking filler dispersion liquid after coating treatment is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of papermaking filler treatment, in particular to a multi-element composite papermaking filler coating treatment agent, a preparation method and application thereof. BACKGROUND

[0002] Paper and other paper products have become an important material indispensable to human daily life. In order to reduce production costs and improve paper performance, filler ingredients are usually used in the papermaking process. The application of papermaking filler not only can replace a part of papermaking fiber raw materials, reduce the amount of papermaking fiber raw materials, but also can improve the smoothness, transparency, whiteness and printing performance of paper through the filling effect of filler on fiber pores. Existing papermaking fillers mainly include heavy calcium carbonate, light calcium carbonate, kaolin, talc, titanium dioxide and other inorganic minerals, and the amount can account for 20-30wt% of the paper material component.

[0003] Since the addition of papermaking filler can alleviate the pressure of fiber resource shortage, effectively reduce the raw material cost of papermaking, and improve the economic benefit of papermaking, increasing the proportion of papermaking filler in paper has become the main technical development direction. However, the addition of a large amount of fillers will directly affect the mechanical properties of paper (especially paper strength, internal bonding strength, etc.), and there is a negative correlation problem between filler content and paper strength. Moreover, the large amount of fillers added in the paper are not evenly distributed, and there is a problem of paper surface difference, that is, a large amount of fillers are easily deposited on the back of the paper (the lower part of the gravity direction), and less on the front of the paper (the upper part of the gravity direction), which directly leads to a significant reduction in paper mechanical properties, printing performance, appearance quality, etc. Further, in the papermaking process, after the large amount of fillers are mixed with the pulp, the retention rate of the fillers in the paper sheet is low, and the single-pass retention rate is low, most of the fillers cannot effectively stay in the paper sheet, but enter the white water circulation, resulting in high white water concentration, increased load of white water circulation system, and directly affecting the drainage performance and running performance of the paper machine.

[0004] Although the prior art discloses the use of conventional treatment agents such as cationic starch and polyacrylamide to pretreat fillers to increase the filler content in the paper sheet, the high-temperature storage stability of the filler dispersion liquid obtained by treating the fillers with conventional treatment agents is poor, and it must be prepared on site during the papermaking process. Not only is the application flexibility poor, but also the complexity of the papermaking process is increased, and the overall stability of the process is reduced.

[0005] Based on this, a multi-component composite papermaking filler coating agent is provided. After coating the papermaking fillers, it can effectively improve the retention rate of papermaking fillers in the paper sheet and the single-pass retention rate, improve the uniformity of distribution and binding state of papermaking fillers in the paper, and avoid the adverse effects of adding large doses of papermaking fillers on paper properties. While increasing the content of papermaking fillers in the paper, it simultaneously improves the mechanical properties and printing properties of the paper, and improves the water filtration and operation performance of the paper machine. It also improves the high-temperature storage stability of the coated papermaking filler dispersion, which has important technical significance and research value. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a multi-component composite papermaking filler coating agent, its preparation method, and its application. This agent effectively improves the retention rate of papermaking fillers on paper sheets and the single-pass retention rate during papermaking, enhances the uniformity of filler distribution and bonding within the paper, and avoids the adverse effects of adding large doses of fillers on paper properties. While increasing the filler content in the paper, it simultaneously improves the paper's mechanical and printing properties, and enhances the paper machine's filtration and operational performance. Furthermore, it improves the high-temperature storage stability of the coated filler dispersion.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a multi-component composite paper filling coating agent includes the following steps: polymerization reaction, preparation of a first component, and preparation of a second component;

[0009] The polymerization reaction method is as follows: in a nitrogen atmosphere, the quaternized chitosan solution is heated to 58-60°C and kept at that temperature; under stirring conditions, a mixed monomer emulsion and an initiator solution are simultaneously added dropwise; after the mixed monomer emulsion and initiator solution are added, the temperature is raised to 68-70°C and kept at that temperature for reaction. Then, the pH is adjusted to 5-6, and the solid content is adjusted to 8-8.5 wt% using deionized water to obtain the polymerized product.

[0010] The mixed monomer emulsion is composed of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier, and deionized water.

[0011] The method for preparing the first component is to mix the polymer reactant, defoamer, and bactericide evenly to obtain the first component;

[0012] The method for preparing the second component is to mix anionic polyacrylamide with a molecular weight of 12-15 million with deionized water to obtain the second component.

[0013] Preferably, in the polymerization reaction, the quaternized chitosan used is quaternary ammonium salt modified chitosan, and the quaternary ammonium salt is 2,3-epoxypropyltrimethylammonium chloride or dimethyldiallylammonium chloride.

[0014] Preferably, in the polymerization reaction, the quaternized chitosan solution is a deionized aqueous solution of quaternized chitosan, and the mass concentration of quaternized chitosan is 2.8-3 wt%.

[0015] The initiator solution is a deionized aqueous solution of ammonium persulfate, with a mass concentration of 4.5-5 wt%.

[0016] Preferably, in the polymerization reaction, the weight ratio of vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier, and deionized water in the mixed monomer emulsion is 17-18:11.5-12.5:0.06-0.07:0.3-0.34:0.6-0.7:20-23.

[0017] Preferably, in the polymerization reaction, the mixed monomer emulsion and the initiator solution are added dropwise simultaneously within 2.5-3 hours;

[0018] The holding time for heating to 68-70℃ is 2-2.5 hours.

[0019] Preferably, in the polymerization reaction, the weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is 200-220:50-55:12-12.5;

[0020] In the preparation of the first component, the weight ratio of the polymer reactant, defoamer, and bactericide is 100:2-2.1:0.9-1;

[0021] In the preparation of the second component, the mass concentration of anionic polyacrylamide in the second component is 1-1.2 wt%.

[0022] A multi-component composite paper filling coating agent, as described above, is composed of a first component and a second component.

[0023] The application of the aforementioned multi-component composite paper filling coating agent includes the following steps: filler treatment and mixing and papermaking;

[0024] The method for treating the filler is as follows: papermaking filler is added to deionized water and dispersed evenly to obtain a filler dispersion; under stirring conditions, the diluted first component and the diluted second component are added to the filler dispersion in sequence to obtain a filler treatment solution.

[0025] The papermaking filler is at least one of the following: heavy calcium carbonate, light calcium carbonate, titanium dioxide, talc, and kaolin.

[0026] The method of mixed papermaking involves mixing the filler treatment liquid and papermaking pulp evenly to obtain paper stock; and using the paper stock to make base paper.

[0027] Preferably, in the filler treatment, the mass concentration of the papermaking filler in the filler dispersion is 18-22 wt%.

[0028] The weight ratio of the first component to the second component is 0.6-0.65:1;

[0029] The first component is diluted 80-85 times, and the second component is diluted 10-12 times.

[0030] Preferably, in the filler treatment, the total weight of the first component and the second component added per ton of oven-dry paper filling is 3-6 kg;

[0031] In the mixed papermaking process, the ratio of papermaking filler to papermaking pulp in the filler treatment liquid by oven dry weight is 30-40%:60-70%.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The multi-component composite paper filling coating agent of the present invention uses quaternized chitosan, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, and polyethylene glycol diacrylate to obtain the first component through a polymerization reaction. In this process, quaternized chitosan is used as a cationic backbone. Through free radical graft copolymerization and mixed monomer bonding, vinyl acetate and N-hydroxyethylacrylamide side chains are grafted, which have the flexibility and adhesion provided by vinyl acetate and the hydrogen bonding performance of N-hydroxyethylacrylamide. At the same time, N,N'-methylenebisacrylamide and polyethylene glycol diacrylate are cross-linked to form a graft copolymer microgel with a three-dimensional interpenetrating network structure. High molecular weight anionic polyacrylamide is used as the second component. The first component and the second component are used to coat the paper filling. After the first component contacts the papermaking filler, the quaternized chitosan is first adsorbed onto the negatively charged filler surface through electrostatic attraction. Then, the grafted copolymer microgel further coats the filler surface, forming a dense coating film with flexibility, adhesion, and hydrogen bonding properties. This provides numerous hydrogen bond and adhesion sites on the papermaking filler surface, promoting the subsequent bonding performance between the filler and the papermaking fibers. Furthermore, the microgel structure of the coating film buffers the contact between the filler and the fibers, improving the filler's adaptability to irregular structures on the fiber's outer surface, increasing the filler's distribution uniformity within the paper, increasing the filler content, and improving the paper's mechanical properties. The inherent stability of the microgel structure also enhances the high-temperature storage stability of the coated papermaking filler dispersion, preventing its failure during subsequent storage. Further, after the second component contacts the papermaking filler, its bridging effect improves the retention rate of the papermaking filler on the paper sheet and the single-pass retention rate during papermaking. The aforementioned technical methods work together synergistically to effectively improve the retention rate of papermaking fillers in the paper sheet and the single-pass retention rate, improve the uniformity of distribution and binding state of papermaking fillers in the paper, and avoid the adverse effects of adding large doses of papermaking fillers on paper performance. While increasing the content of papermaking fillers in the paper, the mechanical properties and printing properties of the paper are improved simultaneously, and the water filtration and operation performance of the paper machine are improved. In addition, the high-temperature storage stability of the coated papermaking filler dispersion is improved.

[0034] (2) After using the multi-component papermaking filler coating agent of the present invention to coat heavy calcium carbonate with an average particle size of 2.94 μm and a particle size distribution of 2.61, the average particle size of the coated particles is 16.80-16.85 μm and the particle size distribution is 1.48-1.51.

[0035] (3) After coating heavy calcium carbonate with the multi-component composite papermaking filler coating agent of the present invention, a filler treatment liquid is obtained. The filler treatment liquid is mixed with papermaking pulp to prepare a quantitative amount of 80 g / m³. 2The double-sided offset paper, after testing, has an ash content of 27.6-27.8% and an internal bond strength of 175-178 J / m. 2 The printing strength is 2.99-3.04 m / s, the transverse tensile strength is 2.16-2.20 kN / m, the longitudinal tensile strength is 5.08-5.13 kN / m, and the transverse folding endurance is 31-33 times; meanwhile, the first pass retention rate of the paper machine is 85.7-85.9%, and the white water concentration is 0.13-0.15%.

[0036] (4) After coating heavy calcium carbonate with the multi-component composite papermaking filler coating agent of the present invention, the resulting filler treatment solution is stored in a constant temperature and humidity environment of 45°C and 80% for 10 days, and then mixed with papermaking pulp to prepare a solution with a basis weight of 80 g / m³. 2 The double-sided offset paper, after testing, still has an ash content of up to 26.8% and an internal bond strength of up to 170 J / m. 2 The printing strength can still reach 2.91 m / s, the transverse tensile strength can still reach 2.08 kN / m, the longitudinal tensile strength can still reach 4.85 kN / m, and the transverse folding endurance can still reach 31 times; at the same time, the first pass retention rate of the paper machine can still reach 82.9%.

[0037] (5) The multi-component paper filling coating agent of the present invention has a simple preparation method, the raw materials are easy to obtain, the preparation process is easy to control, and it is suitable for large-scale industrial production. Attached Figure Description

[0038] Figure 1 This is a microscopic image of the coated particles after being treated with the paper filler coating agent of Example 2 on heavy calcium carbonate.

[0039] Figure 2 The image shows the microscopic effect of paper samples produced by papermaking after the filler has been treated with the paper filler coating agent of Example 2.

[0040] Figure 3 The image shows the microscopic effect of the paper sample produced by papermaking after the filler was treated with the paper filler coating agent of Comparative Example 1. Detailed Implementation

[0041] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0043] This invention provides a method for preparing a multi-component composite paper filling coating agent, comprising the following steps: raw material preparation, polymerization reaction, preparation of a first component, and preparation of a second component.

[0044] The method for preparing the raw materials is as follows: Quaternized chitosan is added to deionized water, and under stirring at 100-200 rpm, the temperature is raised to 45-50℃ and maintained for stirring for 2-3 hours to obtain a quaternized chitosan solution with a mass concentration of 2.8-3 wt%. The solution is then naturally cooled to 33-35℃ and kept warm for later use. At room temperature, vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and emulsifier OP-10 are added to deionized water and stirred at high speed at 800-1000 rpm for 15-30 minutes to obtain a mixed monomer emulsion for later use. Ammonium persulfate is added to deionized water and stirred until completely dissolved to obtain an initiator solution with a mass concentration of 4.5-5 wt% for later use.

[0045] In the preparation of the raw materials, the quaternized chitosan is a quaternized salt modified chitosan, and the quaternized salt is 2,3-epoxypropyltrimethylammonium chloride or dimethyldiallylammonium chloride; the quaternized salt is preferably 2,3-epoxypropyltrimethylammonium chloride (that is, the quaternized chitosan is preferably hydroxypropyltrimethylammonium chloride chitosan).

[0046] In the preparation of the raw materials, the weight ratio of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier OP-10, and deionized water in the mixed monomer emulsion is 17-18:11.5-12.5:0.06-0.07:0.3-0.34:0.6-0.7:20-23.

[0047] The polymerization reaction method is as follows: A quaternized chitosan solution is placed in a reactor, and the air inside the reactor is completely replaced with nitrogen. Under a nitrogen atmosphere, the mixture is stirred at 250-300 rpm and heated to 58-60°C. After stirring for 10-20 minutes, a mixed monomer emulsion and an initiator solution are simultaneously added dropwise, ensuring that the addition of the mixed monomer emulsion and initiator solution is completed within 2.5-3 hours. After the addition of the mixed monomer emulsion and initiator solution is complete, the mixture is stirred and heated to 68-70°C. After stirring for 2-2.5 hours, the mixture is allowed to cool naturally to room temperature. The pH is adjusted to 5-6 using a 5-6% acetic acid solution, and the solid content is adjusted to 8-8.5 wt% using deionized water to obtain the polymerized product.

[0048] In the polymerization reaction, the weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is 200-220:50-55:12-12.5.

[0049] The method for preparing the first component is as follows: the polymer reactant, defoamer, and bactericide are mixed evenly according to a weight ratio of 100:2-2.1:0.9-1 to obtain the first component.

[0050] In the preparation of the first component, the defoamer is an organosilicon defoamer; the bactericide is an isothiazolinone bactericide.

[0051] The method for preparing the second component is as follows: high molecular weight anionic polyacrylamide is added to deionized water, and stirred at room temperature for 50-60 minutes under stirring conditions of 500-600 rpm to obtain a second component with an anionic polyacrylamide mass concentration of 1-1.2 wt%.

[0052] In the preparation of the second component, the anionic polyacrylamide has a molecular weight of 12-15 million and an ionic degree of 10-20%.

[0053] The present invention also provides a multi-component composite paper filling coating agent prepared by the aforementioned method, which is composed of a first component and a second component.

[0054] The present invention also provides the application of the aforementioned multi-component composite paper filling coating agent, including the following steps: filler treatment and mixed papermaking.

[0055] The method for treating the filler is as follows: papermaking filler is added to deionized water and dispersed evenly to obtain a filler dispersion with a mass concentration of 18-22 wt%; then, under stirring at 500-600 rpm, the first component diluted 80-85 times is added to the filler dispersion, and after stirring for 15-30 min, the second component diluted 10-12 times is added, and stirring is continued for 10-15 min to obtain the filler treatment solution.

[0056] In the filler treatment, the papermaking filler is one of the following: heavy calcium carbonate, light calcium carbonate, titanium dioxide, talc, or kaolin.

[0057] In the filler treatment, the weight of the paper filler coating agent added per ton of oven-dry paper filler is 3-6 kg;

[0058] The weight ratio of the first component to the second component in the paper filling coating agent is 0.6-0.65:1.

[0059] The method of mixed papermaking involves mixing the filler treatment liquid and the paper pulp, controlling the oven-dry weight ratio of the paper filler to the paper pulp in the filler treatment liquid to be 30-40%:60-70%, and after uniform mixing, obtaining the paper stock; the paper stock is then diluted and papermade to obtain a basis weight of 70-100 g / m³. 2 The base paper.

[0060] The present invention will be further described below with reference to some specific embodiments.

[0061] Example 1

[0062] This embodiment provides a method for preparing a multi-component composite paper filling coating agent, specifically as follows:

[0063] 1. Raw material preparation

[0064] Hydroxypropyltrimethylammonium chloride chitosan was added to deionized water and heated to 45°C under stirring at 120 rpm for 3 hours to obtain a 2.8 wt% quaternized chitosan solution. This solution was then naturally cooled to 35°C and kept warm for later use. At room temperature, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and emulsifier OP-10 were added to deionized water and stirred at 800 rpm for 30 minutes to obtain a mixed monomer emulsion for later use. Ammonium persulfate was added to deionized water and stirred until completely dissolved to obtain a 4.5 wt% ammonium persulfate initiator solution for later use.

[0065] In the mixed monomer emulsion, the weight ratio of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier OP-10, and deionized water is 17:11.5:0.06:0.3:0.6:20.

[0066] 2. Polymerization reaction

[0067] The quaternized chitosan solution was placed in a reactor, and the air inside the reactor was completely replaced with nitrogen. Under nitrogen atmosphere and stirring at 250 rpm, the temperature was raised to 58°C and maintained for 20 min. Then, the mixed monomer emulsion and initiator solution were added dropwise simultaneously over 2.5 h. After the mixed monomer emulsion and initiator solution were added, the temperature was raised to 68°C and maintained for 2 h. The mixture was then allowed to cool naturally to room temperature. The pH was adjusted to 6 with a 5% acetic acid solution, and the solid content was adjusted to 8.5 wt% with deionized water to obtain the polymer.

[0068] The weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is 200:50:12.

[0069] 3. Preparation of the first component

[0070] The first component is prepared by mixing the polymer reactant, silicone defoamer, and isothiazolinone bactericide in a weight ratio of 100:2:0.9.

[0071] 4. Preparation of the second component

[0072] Anionic polyacrylamide was added to deionized water and stirred at room temperature for 60 minutes at 500 rpm to obtain a second component with anionic polyacrylamide concentration of 1.2 wt%.

[0073] Among them, the anionic polyacrylamide has a molecular weight of 15 million and an ionic degree of 20%.

[0074] This embodiment also provides a multi-component composite paper filling coating agent prepared by the aforementioned method.

[0075] Example 2

[0076] This embodiment provides a method for preparing a multi-component composite paper filling coating agent, specifically as follows:

[0077] 1. Raw material preparation

[0078] Hydroxypropyltrimethylammonium chloride chitosan was added to deionized water and heated to 48°C under stirring at 150 rpm for 2.5 h to obtain a quaternized chitosan solution with a mass concentration of 2.9 wt%. The solution was then naturally cooled to 35°C and kept at that temperature for later use. At room temperature, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and emulsifier OP-10 were added to deionized water and stirred at 900 rpm for 20 min to obtain a mixed monomer emulsion for later use. Ammonium persulfate was added to deionized water and stirred until completely dissolved to obtain an initiator solution with a mass concentration of 4.7 wt% for later use.

[0079] In the mixed monomer emulsion, the weight ratio of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier OP-10, and deionized water is 17.6:12.1:0.065:0.33:0.65:21.

[0080] 2. Polymerization reaction

[0081] The quaternized chitosan solution was placed in a reactor, and the air inside the reactor was completely replaced with nitrogen. Under nitrogen atmosphere and stirring at 280 rpm, the temperature was raised to 59°C and maintained for 15 min. Then, the mixed monomer emulsion and initiator solution were added dropwise simultaneously over 3 h. After the mixed monomer emulsion and initiator solution were added, the temperature was raised to 70°C and maintained for 2.3 h. The mixture was then allowed to cool naturally to room temperature. The pH was adjusted to 6 with a 5% acetic acid solution, and the solid content was adjusted to 8.5 wt% with deionized water to obtain the polymer.

[0082] The weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is 210:53:12.3.

[0083] 3. Preparation of the first component

[0084] The first component is prepared by mixing the polymer reactant, silicone defoamer, and isothiazolinone bactericide in a weight ratio of 100:2.1:1.

[0085] 4. Preparation of the second component

[0086] Anionic polyacrylamide was added to deionized water and stirred at room temperature for 60 minutes at 550 rpm to obtain a second component with anionic polyacrylamide concentration of 1.2 wt%.

[0087] Among them, the anionic polyacrylamide has a molecular weight of 15 million and an ionic degree of 20%.

[0088] This embodiment also provides a multi-component composite paper filling coating agent prepared by the aforementioned method.

[0089] Example 3

[0090] This embodiment provides a method for preparing a multi-component composite paper filling coating agent, specifically as follows:

[0091] 1. Raw material preparation

[0092] Hydroxypropyltrimethylammonium chloride chitosan was added to deionized water and heated to 50°C under stirring at 200 rpm for 2 hours to obtain a 3 wt% quaternized chitosan solution. This solution was then naturally cooled to 35°C and kept warm for later use. At room temperature, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and emulsifier OP-10 were added to deionized water and stirred at 1000 rpm for 15 minutes to obtain a mixed monomer emulsion for later use. Ammonium persulfate was added to deionized water and stirred until completely dissolved to obtain a 5 wt% ammonium persulfate initiator solution for later use.

[0093] In the mixed monomer emulsion, the weight ratio of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier OP-10, and deionized water is 18:12.5:0.07:0.34:0.7:23.

[0094] 2. Polymerization reaction

[0095] The quaternized chitosan solution was placed in a reactor, and the air inside the reactor was completely replaced with nitrogen. Under nitrogen atmosphere and stirring at 300 rpm, the temperature was raised to 60°C and maintained for 10 min. Then, the mixed monomer emulsion and initiator solution were added dropwise simultaneously over 2.75 h. After the mixed monomer emulsion and initiator solution were added, the temperature was raised to 70°C and maintained for 2.5 h. The mixture was then allowed to cool naturally to room temperature. The pH was adjusted to 6 with a 5% acetic acid solution, and the solid content was adjusted to 8.5 wt% with deionized water to obtain the polymer.

[0096] The weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is 220:55:12.5.

[0097] 3. Preparation of the first component

[0098] The first component is prepared by mixing the polymer reactant, silicone defoamer, and isothiazolinone bactericide in a weight ratio of 100:2.1:1.

[0099] 4. Preparation of the second component

[0100] Anionic polyacrylamide was added to deionized water and stirred at room temperature for 50 minutes at 600 rpm to obtain a second component with anionic polyacrylamide concentration of 1.2 wt%.

[0101] Among them, the anionic polyacrylamide has a molecular weight of 15 million and an ionic degree of 20%.

[0102] This embodiment also provides a multi-component composite paper filling coating agent prepared by the aforementioned method.

[0103] Example 4

[0104] This embodiment provides an application of the aforementioned multi-component composite paper filling coating agent, specifically:

[0105] 1. Packing material treatment

[0106] Papermaking filler (heavy calcium carbonate) was added to deionized water and dispersed evenly to obtain a filler dispersion with a mass concentration of 20 wt%. Then, under stirring at 600 rpm, the first component diluted 80 times was added to the filler dispersion and stirred for 20 min. After stirring, the second component diluted 10 times was added and stirred for another 15 min to obtain the filler treatment solution.

[0107] The weight of the paper filling coating agent added per ton of oven-dried paper filling is 5.5 kg.

[0108] The weight ratio of the first component to the second component in the paper filling coating agent is 0.65:1.

[0109] 2. Mixed copying

[0110] The filler treatment solution and paper pulp are mixed, and the oven-dry weight ratio of paper filler to paper pulp in the filler treatment solution is controlled at 35%:65%. After uniform mixing, paper stock is obtained. The paper stock is diluted and paper-making to obtain a basis weight of 80 g / m³. 2 The base paper.

[0111] Example 5

[0112] This embodiment provides an application of the aforementioned multi-component composite paper filling coating agent, specifically:

[0113] 1. Packing material treatment

[0114] Papermaking filler (light calcium carbonate) was added to deionized water and dispersed evenly to obtain a filler dispersion with a mass concentration of 22 wt%. Then, under stirring at 600 rpm, the first component diluted 82 times was added to the filler dispersion and stirred for 30 min. The second component diluted 11 times was then added and stirred for another 15 min to obtain the filler treatment solution.

[0115] The weight of the paper filling coating agent added per ton of oven-dried paper filling is 4.2 kg.

[0116] The weight ratio of the first component to the second component in the paper filling coating agent is 0.63:1.

[0117] 2. Mixed copying

[0118] The filler treatment solution and paper pulp are mixed, and the oven-dry weight ratio of paper filler to paper pulp in the filler treatment solution is controlled at 35%:65%. After uniform mixing, paper stock is obtained. The paper stock is diluted and paper-making to obtain a basis weight of 80 g / m³. 2 The base paper.

[0119] Comparative Example 1

[0120] Comparative Example 1 adopts the technical solution of Example 2, the difference being that: in the raw material preparation step, the addition of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate is omitted in the mixed monomer emulsion; correspondingly, in the polymerization reaction step, a mixed monomer emulsion without N,N'-methylenebisacrylamide and polyethylene glycol diacrylate is used for polymerization.

[0121] Comparative Example 2

[0122] Comparative Example 2 adopts the technical solution of Example 2, the difference being: 1) In the raw material preparation step, cationic polyacrylamide with a molecular weight of 5 million and an ionicity of 20% is used to replace quaternized chitosan, and is mixed with deionized water to prepare a cationic polyacrylamide solution with a mass concentration of 2.8 wt%, and in the polymerization reaction step, the cationic polyacrylamide solution is used to replace the quaternized chitosan solution; 2) In the raw material preparation step, acrylamide is used to replace N-hydroxyethyl acrylamide in the mixed monomer emulsion, and in the polymerization reaction step, a mixed monomer emulsion containing acrylamide is used for polymerization.

[0123] The application performance of the papermaking filler coating agents of Examples 1-3 and Comparative Examples 1-2 was tested. Specifically, according to the filler treatment method of Example 4, the papermaking filler coating agents of Examples 1-3 and Comparative Examples 1-2 were used to coat heavy calcium carbonate with an average particle size of 2.94 μm and a particle size distribution of 2.61. The average particle size and particle size distribution of the coated particles obtained after treatment with each papermaking filler coating agent are shown in the table below; among them, the heavy calcium carbonate coated particles treated with the papermaking filler coating agent of Example 2 are shown in the table below. Figure 1 As shown, the treatment agent has a good coating effect on heavy calcium carbonate, and the coated particles have a uniform particle size.

[0124] Furthermore, following the application method of Example 4, heavy calcium carbonate was coated with the papermaking filler coating agents of Examples 1-3 and Comparative Examples 1-2 respectively to obtain filler treatment solutions. Hard calcium carbonate was then coated with the filler treatment agents of Examples 1-3 and Comparative Examples 1-2 to obtain filler treatment solutions. Hardwood bleached sulfate pulp (LBKP), softwood bleached sulfate pulp (NBKP), bleached chemithermomechanical pulp (BCTMP), and recycled waste paper pulp (BROKE) were prepared into papermaking pulps at a weight ratio of 77:12:11:15. The papermaking pulps were then mixed with the filler treatment solutions corresponding to Examples 1-3 and Comparative Examples 1-2, respectively, controlling the oven-dry weight ratio of the papermaking filler to the papermaking pulp in the filler treatment solution to be 35%:65%. After thorough mixing, the mixture was fed into a papermaking machine to obtain a basis weight of 80 g / m³. 2 The ash content, internal bond strength, printing strength, transverse tensile strength, longitudinal tensile strength, and transverse folding endurance of the offset paper were tested. The first pass retention and white water concentration of the paper were also recorded. The specific results are shown in the table below:

[0125]

[0126] The microscopic image of the double-sided offset paper sample obtained after treating heavy calcium carbonate with the paper filling coating agent of Example 2 is shown below. Figure 2 As shown in the figure; the microscopic effect of the double-sided offset paper sample prepared by treating heavy calcium carbonate with the paper filling coating agent of Comparative Example 1 is shown in the figure. Figure 3 As shown.

[0127] As can be seen, the paper filler coating treatment agent in Examples 1-3 uses quaternized chitosan, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, and polyethylene glycol diacrylate, which are combined and polymerized to obtain the first component. In this process, quaternized chitosan serves as a cationic backbone, and through free radical graft copolymerization and mixed monomer bonding, it grafts vinyl acetate and N-hydroxyethylacrylamide branches, possessing both the flexibility and adhesion provided by vinyl acetate and the hydrogen bonding performance of N-hydroxyethylacrylamide. At the same time, it forms a graft copolymer microgel with a three-dimensional interpenetrating network structure through crosslinking of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate. High molecular weight anionic polyacrylamide is used as the second component. The coating treatment of paper fillers using the first and second components results in good coating effect, uniform particle size distribution of the coated particles, and high filler content, uniform filler distribution, and good bonding performance in the double-sided offset paper made using this method (e.g., Figure 2 As shown in the figure, the filler has a high retention rate in the paper during the preparation process, which can effectively improve the mechanical properties of the paper (such as internal bond strength and tensile strength), printing properties (such as printing surface strength), and improve the first pass retention performance of the paper machine.

[0128] Comparative Example 1 omits the addition of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate. The coating layer formed by the first component lacks a microgel cross-linking structure, resulting in reduced coating layer stability and decreased uniformity of filler distribution within the paper (e.g., ...). Figure 3 As shown in the figure, it easily leads to paper shedding and dusting, and the filler retention rate decreases, which in turn reduces the ash content. At the same time, the bonding performance between the filler and the papermaking fiber decreases, resulting in reduced mechanical and printing properties of the finished offset paper. Furthermore, due to the lack of stable bridging effect of the microgel crosslinking structure in Comparative Example 1, the first-pass retention performance of the paper machine is reduced.

[0129] In Comparative Example 2, after replacing quaternized chitosan with cationic polyacrylamide and N-hydroxyethyl acrylamide with acrylamide, the coating performance of the paper filler coating agent, the uniformity of filler distribution, and the bonding performance between the filler and paper fibers were significantly reduced. Specifically, the filler retention rate in the paper decreased, the ash content decreased, the mechanical and printing properties of the resulting offset paper decreased, and the first-pass retention performance of the paper machine decreased.

[0130] Furthermore, following the filler treatment method of Example 4, heavy calcium carbonate was coated with the papermaking filler coating agents of Example 2 and Comparative Example 1 respectively to obtain filler treatment solutions. These solutions were then placed in a constant temperature and humidity environment of 45°C and 80% and allowed to stand for 10 days. Following the mixing and papermaking method of Example 4, the settled filler treatment solutions were then used for a basis weight of 80 g / m³. 2In the preparation of double-sided offset paper, the ash content, internal bond strength, printing strength, transverse tensile strength, longitudinal tensile strength, and transverse folding endurance of the double-sided offset paper were tested, and the first pass retention rate of the paper machine was recorded. The specific results are shown in the table below:

[0131]

[0132] As can be seen, the paper filling coating agent of the present invention uses quaternized chitosan, vinyl acetate, N-hydroxyethylacrylamide, N,N'-methylenebisacrylamide, and polyethylene glycol diacrylate, which are combined and polymerized to obtain the first component. High molecular weight anionic polyacrylamide is used as the second component. Through the two-component coating treatment of the paper filling, the coated filling particles exhibit repulsive forces to prevent aggregation. Furthermore, the coating layer with a microgel cross-linked structure has good storage stability in high-temperature environments. The filling treatment solution retains good application performance even after long-term storage. Specifically, it demonstrates a high retention rate of the filling in the paper during the preparation of offset paper, and the mechanical properties, printing properties, and first-pass retention performance of the paper are not significantly different from those of the newly prepared filling treatment solution. In Comparative Example 1, the addition of N,N'-methylenebisacrylamide and polyethylene glycol diacrylate is omitted. The coating layer formed by the first component lacks a microgel cross-linked structure, resulting in reduced coating layer stability and decreased high-temperature storage stability of the filling treatment solution.

[0133] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0134] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a multi-component composite paper filling coating agent, characterized in that, The process includes the following steps: polymerization reaction, preparation of the first component, and preparation of the second component; The polymerization reaction method is as follows: in a nitrogen atmosphere, the quaternized chitosan solution is heated to 58-60°C and kept at that temperature; under stirring conditions, a mixed monomer emulsion and an initiator solution are simultaneously added dropwise; after the mixed monomer emulsion and initiator solution are added, the temperature is raised to 68-70°C and kept at that temperature for reaction. Then, the pH is adjusted to 5-6, and the solid content is adjusted to 8-8.5 wt% using deionized water to obtain the polymerized product. The mixed monomer emulsion is composed of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier, and deionized water; the weight ratio of vinyl acetate, N-hydroxyethyl acrylamide, N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, emulsifier, and deionized water in the mixed monomer emulsion is (17-18):(11.5-12.5):(0.06-0.07):(0.3-0.34):(0.6-0.7):(20-23). In the polymerization reaction, the quaternized chitosan solution is a deionized aqueous solution of quaternized chitosan with a mass concentration of 2.8-3 wt%; the initiator solution is a deionized aqueous solution of ammonium persulfate with a mass concentration of 4.5-5 wt%. In the polymerization reaction, the weight ratio of the quaternized chitosan solution, the mixed monomer emulsion, and the initiator solution is (200-220):(50-55):(12-12.5). The method for preparing the first component is to mix the polymer reactant, defoamer, and bactericide evenly to obtain the first component; The method for preparing the second component is to mix anionic polyacrylamide with a molecular weight of 12-15 million with deionized water to obtain the second component; the mass concentration of anionic polyacrylamide in the second component is 1-1.2 wt%.

2. The preparation method of the multi-component composite paper filling coating agent according to claim 1, characterized in that, In the polymerization reaction, the quaternized chitosan used is quaternary ammonium salt modified chitosan, and the quaternary ammonium salt is 2,3-epoxypropyltrimethylammonium chloride or dimethyldiallylammonium chloride.

3. The preparation method of the multi-component composite paper filling coating agent according to claim 1, characterized in that, In the polymerization reaction, the mixed monomer emulsion and the initiator solution are added dropwise simultaneously within 2.5-3 hours. The holding time for heating to 68-70℃ is 2-2.5 hours.

4. The preparation method of the multi-component composite paper filling coating agent according to claim 1, characterized in that, In the preparation of the first component, the weight ratio of the polymer reactant, defoamer, and bactericide is 100:(2-2.1):(0.9-1).

5. A multi-component composite paper filling coating agent prepared by the preparation method according to any one of claims 1-4, characterized in that, It consists of a first component and a second component.

6. The application of the multi-component composite paper filling coating agent as described in claim 5, characterized in that, The process includes the following steps: filler treatment and mixing / forming. The method for treating the filler is as follows: papermaking filler is added to deionized water and dispersed evenly to obtain a filler dispersion; under stirring conditions, the diluted first component and the diluted second component are added to the filler dispersion in sequence to obtain a filler treatment solution. The papermaking filler is at least one of the following: heavy calcium carbonate, light calcium carbonate, titanium dioxide, talc, and kaolin. The method of mixed papermaking involves mixing the filler treatment liquid and papermaking pulp evenly to obtain paper stock; and using the paper stock to make base paper.

7. The application of the multi-component composite paper filling coating agent according to claim 6, characterized in that, In the filler treatment, the mass concentration of papermaking filler in the filler dispersion is 18-22 wt%. The weight ratio of the first component to the second component is (0.6-0.65):1; The first component is diluted 80-85 times, and the second component is diluted 10-12 times.

8. The application of the multi-component composite paper filling coating agent according to claim 6, characterized in that, In the filler treatment, the total weight of the first and second components added per ton of oven-dry paper filler is 3-6 kg. In the mixed papermaking process, the ratio of papermaking filler to papermaking pulp in the filler treatment liquid by oven dry weight is (30-40)%:(60-70)%.

Images