Composite filler, preparation method and application

Abstract

The invention relates to the technical field of papermaking fillers, in particular to a composite filler, a preparation method and application, and the method comprises the following steps: preparing a filler suspension by using calcium silicate powder; then, adding an alum solution into the filler suspension, and reacting to obtain a prefabricated composite filler; and finally, preparing a prefabricated composite filler suspension, and treating the prefabricated composite filler suspension by using carbon dioxide to obtain the composite filler. The chemical property of the calcium silicate powder is changed and the dissolution rate of the calcium silicate powder is reduced through combined use of the alum and the carbon dioxide, and more filler can be retained in paper instead of being dissolved in slurry in the papermaking process, so that the yield of the filler is increased, and the production cost is reduced. The problems of low filler yield and high cost caused by high dissolution rate of calcium silicate filler in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking fillers, specifically to a composite filler, a preparation method and an application thereof, and in particular to a low-dissolution rate composite filler suitable for ultra-high ratio chemical pulp light paper, a preparation method and an application thereof. Background Art

[0002] In recent years, paper producers have paid more and more attention to the indicator of paper bulk. Since high-bulk paper can replace the original high-weight paper of the same thickness, it not only saves fiber raw materials, but also reduces production and transportation costs, thus bringing better economic benefits to enterprises. Since paper made of chemical pulp usually has a lower bulk, the light paper used on the market is mainly made of chemical mechanical pulp or a small amount of chemical pulp. However, the higher the proportion of chemical mechanical pulp, the worse the paper strength is, and it will also cause a series of problems such as yellowing of the paper.

[0003] Calcium silicate is a natural mineral or synthetic compound. In a broad sense, it is a hydrate of calcium oxide and silicon dioxide. Its molecular formula can be expressed as CaO·mSiO2·nH2O. It is a new silicate product, non-toxic and tasteless. Calcium silicate is an alternative product to titanium dioxide and antimony dioxide as a reinforcing agent, brightener and thickener. It has the characteristics of porous structure, low bulk density, high porosity and good absorbency. The porous structure of calcium silicate allows it to occupy more space in paper, thereby increasing the bulk of the paper and improving product quality.

[0004] However, calcium silicate powder has a high solubility problem. If the solubility of calcium silicate powder in water is too high, it will directly cause the filler to dissolve prematurely in the wet part of the paper machine, affecting the distribution and retention rate of the filler in the paper, and further affecting the filler yield. The dissolved calcium silicate may also increase the solid content in the white water of the paper machine, increasing the difficulty and cost of wastewater treatment. Summary of the invention

[0005] Aiming at the problem in the prior art that the calcium silicate filler has a high dissolution rate, resulting in a low filler yield and high cost, the present invention provides a method for preparing a composite filler.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a composite filler, comprising: Calcium silicate powder is used to prepare a filler suspension; adding an alum solution to the filler suspension to react and obtain a prefabricated composite filler; Using the prefabricated composite filler, preparing a prefabricated composite filler suspension; The prefabricated composite filler suspension is treated with carbon dioxide to obtain the composite filler through reaction.

[0007] Optionally, the mass concentration of calcium silicate powder in the filler suspension is 8% to 15%.

[0008] Optionally, the specific surface area of ​​the calcium silicate powder is 80 to 300 m 2 / g.

[0009] Optionally, in the process of adding alum solution to the filler suspension to react and obtain the prefabricated composite filler, the mass concentration of the alum solution is 5% to 10%; after adding the alum solution, the pH value of the filler suspension is 10 to 11.55.

[0010] Optionally, the aluminum oxide content of the alum in the alum solution is greater than 15%, and the iron oxide content is less than 0.7%.

[0011] The invention provides a composite filler prepared by the method, wherein the dissolution rate of the composite filler is less than 0.05% and the loss amount is less than 2.5%.

[0012] A method for preparing paper using the composite filler, comprising: The plant fiber chemical pulp board and the chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; Using the composite filler, preparing a composite filler suspension; The composite filler suspension is added to the mixed slurry, and the cationic polyacrylamide solution is added, and after stirring, forming on a screen, pressing and drying, the paper filled with the modified calcium silicate composite filler is obtained.

[0013] Optionally, the plant fiber chemical pulp board includes a hardwood chemical pulp board and a softwood chemical pulp board, and the mass ratio of the hardwood pulp board to the softwood pulp board is 3:1; among the plant fiber chemical pulp board and the chemical mechanical pulp, the mass percentage of the plant fiber chemical pulp board is 85% to 100%, and the mass percentage of the chemical mechanical pulp is 0 to 15%.

[0014] Optionally, the mass concentration of the composite filler in the composite filler suspension is 8% to 15%; the mass concentration of the cationic polyacrylamide solution is 0.04% to 0.07%; the mass of the composite filler is 14% to 16% of the total mass; and the amount of the cationic polyacrylamide solution added to a single hand sheet is 0.3 to 0.5 mL.

[0015] A paper comprising the above filler, wherein the paper weight is 70 g / m 2 Under these conditions, the solubility of the composite filler is 0.03% to 0.05%, and the bulk thickness of the paper is 1.5 to 2.85 cm 3 / g, the tensile strength of paper is 22.32~28.32kN / m.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a method for preparing a composite filler. The method comprises the following steps: preparing a filler suspension by using calcium silicate powder; then, adding an alum solution to the filler suspension to react and obtain a prefabricated composite filler; finally, preparing a prefabricated composite filler suspension, and treating the prefabricated composite filler suspension with carbon dioxide to obtain a composite filler. Traditional calcium silicate powder is prone to scaling and equipment corrosion during papermaking due to its high alkalinity. The present invention effectively reduces the pH value of the filler by adding alum to the calcium silicate powder suspension and then treating it with carbon dioxide. This change not only alleviates the scaling, equipment corrosion and other problems caused by the high alkalinity of calcium silicate powder in the production process of papermaking enterprises, but also makes the filler more adaptable to the production environment of papermaking enterprises, reducing the cost increase caused by equipment failure and maintenance; the combined use of alum and carbon dioxide not only changes the chemical properties of calcium silicate powder, but also reduces its dissolution rate. In the papermaking process, more fillers can be retained in the paper instead of being dissolved in the slurry, thereby increasing the yield of the filler and reducing the production cost. At the same time, using the modified composite filler as papermaking filler can promote the lightweight and green nature of paper while ensuring that there is no significant difference in the bulk thickness and strength of the paper. The preparation method is simple to operate, has low equipment requirements, is environmentally friendly, is easy to industrialize, and has broad application prospects.

[0017] The present invention provides a composite filler prepared by the above method, wherein the dissolution rate of the composite filler is less than 0.05%, the loss amount is less than 2.5%, and the pH value of a suspension prepared by the composite filler with a concentration of 10% is 10-11.55. Minimal dissolution loss means that more fillers can be retained in the paper, thereby improving the utilization rate of the filler, reducing waste in the production process, helping to maintain the stability of the papermaking slurry, and reducing the change in slurry viscosity caused by the dissolution of the filler, thereby ensuring the uniformity and stability of the paper quality. A pH value of 10-11.55 can effectively avoid the occurrence of problems such as scaling and equipment corrosion, ensure the smooth progress of production, help improve the production efficiency and product quality of papermaking enterprises, and promote the development of the papermaking industry in a more environmentally friendly and efficient direction.

[0018] The present invention provides a method for preparing paper using the composite filler, wherein the method comprises the following steps: disintegrating and grinding plant fiber chemical pulp board and chemical mechanical pulp to obtain a mixed pulp; preparing a composite filler suspension, adding the composite filler suspension to the mixed pulp, and adding a cationic polyacrylamide solution, stirring, forming on a net, pressing and drying to obtain paper filled with a modified calcium silicate composite filler. The modified calcium silicate composite filler itself has good whiteness and glossiness, and adding it to paper can not only significantly improve the whiteness and opacity of the paper, but also the modified calcium silicate composite filler can fill the gaps in the paper, making the fiber distribution of the paper more uniform, thereby improving the bulk of the paper, and the cationic polyacrylamide as a retention aid can not only improve the retention rate of the filler, but also reduce the discharge of wastewater, thereby reducing pollution to the environment and improving the environmental protection and efficiency of paper manufacturing.

[0019] The present invention provides a paper, which is prepared by the above method, and has a basis weight of 70g / m 2 Under these conditions, the solubility of the composite filler is 0.03% to 0.05%, and the bulk thickness of the paper is 1.5 to 2.85 cm 3 / g, the tensile strength of paper is 22.32~28.32kN / m. Low solubility improves the utilization rate of fillers, reduces waste in the production process, and avoids the problems of paper quality degradation and environmental pollution caused by filler dissolution. The bulk thickness of paper is 1.5~2.85cm 3 / g ensures the softness and thickness of the paper, while avoiding the decrease in paper strength caused by excessive bulk. The moderate bulk makes the paper have good stiffness and wrinkle resistance while maintaining a good hand feel, which is of great significance for improving the printing suitability and writing performance of the paper. The paper has shown significant advantages in terms of composite filler solubility, paper bulk and tensile strength, which make the paper have a wider application prospect and market value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a schematic diagram of a process for preparing a composite filler.

[0021] Figure 2 The present invention is a schematic diagram of a process for preparing paper using a composite filler. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0024] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0025] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0026] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0029] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0030] See also Figure 1 The present invention provides a method for preparing a composite filler, comprising: S1: Prepare filler suspension using calcium silicate powder, specifically: Calcium silicate powder and water are mixed in a reactor at 50°C to 80°C, preferably 60°C to 70°C, to prepare a filler suspension with a mass concentration of 8% to 15%, preferably 9% to 13%, and more preferably 10% to 12%; wherein the specific surface area of ​​the calcium silicate powder is 80 to 300 m 2 / g, the pH value of the filler suspension is 12 to 12.5; S2: adding an alum solution to the filler suspension to react to obtain a prefabricated composite filler, specifically: adding an alum solution to the filler suspension, wherein the mass concentration of the alum solution is 5% to 10%, preferably 6% to 9%, and more preferably 7% to 8%. After the reaction is completed, filtering, washing and dehydrating to obtain the prefabricated composite filler; wherein the alum in the alum solution has an aluminum oxide content greater than 15%, and an iron oxide content less than 0.7%. After adding the alum solution, the pH value of the filler suspension is 10 to 11.55.

[0031] S3: using the prefabricated composite filler to prepare a prefabricated composite filler suspension, specifically: using 60° C. to 80° C. water to prepare the prefabricated composite filler into a prefabricated composite filler suspension with a solid mass concentration of 10% to 15%, preferably 10% to 12%.

[0032] S4: treating the prefabricated composite filler suspension with carbon dioxide to obtain the composite filler, specifically: introducing carbon dioxide into the prefabricated composite filler suspension for 30 to 80 minutes, filtering, washing, and drying to make the dryness of the prefabricated composite filler suspension reach more than 50%, and breaking it up with a blade type breaker to obtain the composite filler.

[0033] The present invention provides a composite filler prepared by the above method, wherein the dissolution rate of the composite filler is less than 0.05%, the loss amount is less than 2.5%, and the pH value of a suspension prepared by the composite filler with a concentration of 10% is 10-11.55. Minimal dissolution loss means that more fillers can be retained in the paper, thereby improving the utilization rate of the filler, reducing waste in the production process, helping to maintain the stability of the papermaking slurry, and reducing the change in slurry viscosity caused by the dissolution of the filler, thereby ensuring the uniformity and stability of the paper quality. A pH value of 10-11.55 can effectively avoid the occurrence of problems such as scaling and equipment corrosion, ensure the smooth progress of production, help improve the production efficiency and product quality of papermaking enterprises, and promote the development of the papermaking industry in a more environmentally friendly and efficient direction.

[0034] See also Figure 2 The present invention provides a method for preparing paper using the composite filler, comprising: S1: Deflashing and grinding the plant fiber chemical pulp board and the chemical mechanical pulp to obtain a mixed pulp; wherein the plant fiber chemical pulp board includes a hardwood chemical pulp board and a softwood chemical pulp board, and the mass ratio of the hardwood pulp board to the softwood pulp board is 3:1; in the plant fiber chemical pulp board and the chemical mechanical pulp, the mass percentage of the plant fiber chemical pulp board is 85% to 100%, and the mass percentage of the chemical mechanical pulp is 0 to 15%. During grinding, the plant fiber chemical pulp board and the chemical mechanical pulp can be mixed and then ground, or the plant fiber chemical pulp board can be used for grinding alone, and only the chemical mechanical pulp is deflashed, and the beating degree of the mixed pulp is 40 to 50°SR.

[0035] S2: preparing a composite filler suspension using the composite filler; wherein the mass concentration of the composite filler in the composite filler suspension is 8% to 15%; S3: Add the composite filler suspension to the mixed slurry, and add the cationic polyacrylamide solution, after stirring, screen forming, pressing and drying, obtain the paper filled with modified calcium silicate composite filler. Among them, the mass concentration of the cationic polyacrylamide solution is 0.04% to 0.07%; the mass of the composite filler is 14% to 16% of the total mass; the amount of the cationic polyacrylamide solution added to a single hand-made sheet is 0.3 to 0.5 mL; the stirring time is 5 to 10 seconds; the mass concentration of the screen during the screen forming is 0.044%; the pressing conditions are: pressure of 0.4 MPa, time of 4 minutes; drying conditions are: temperature of 105°C, time of 9 minutes; The present invention also provides a paper prepared by the above method, wherein the paper has a basis weight of 70 g / m 2 Under these conditions, the solubility of the composite filler is 0.03% to 0.05%, and the bulk thickness of the paper is 1.5 to 2.85 cm 3 / g, the tensile strength of paper is 22.32~28.32kN / m.

[0036] Low solubility improves the utilization rate of fillers, reduces waste in the production process, and avoids the problems of paper quality degradation and environmental pollution caused by filler dissolution. The bulk thickness of paper is 1.5 to 2.85 cm 3 / g ensures the softness and thickness of the paper, while avoiding the decrease in paper strength caused by excessive bulk. The moderate bulk makes the paper have good stiffness and wrinkle resistance while maintaining a good hand feel, which is of great significance for improving the printing suitability and writing performance of the paper. The paper has shown significant advantages in terms of composite filler solubility, paper bulk and tensile strength, which make the paper have a wider application prospect and market value.

[0037] Example 1 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 11.55, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%; the prefabricated composite filler suspension is treated with carbon dioxide for 30 minutes, and the composite filler is obtained after washing, filter pressing and breaking up.

[0038] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0039] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0040] Example 2 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 11.12, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 50 minutes, and the composite filler is obtained after washing, filter pressing and breaking up.

[0041] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0042] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0043] Example 3 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10.89, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%; the prefabricated composite filler suspension is treated with carbon dioxide for 80 minutes, and the composite filler is obtained after washing, filter pressing and breaking up.

[0044] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0045] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0046] Example 4 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 11, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%; the prefabricated composite filler suspension is treated with carbon dioxide for 30 minutes, and the composite filler is obtained after washing, filter pressing and breaking up.

[0047] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0048] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0049] Example 5 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10.51, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 50 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0050] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0051] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0052] Example 6 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 80 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0053] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0054] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0055] Example 7 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 11.55, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 30 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0056] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0057] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0058] Example 8 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 11.12, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 50 minutes, and the composite filler is obtained after washing, filter pressing and breaking up.

[0059] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0060] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0061] Example 9 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10.89, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 30 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0062] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0063] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0064] Example 10 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material, and is configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 10% is added to adjust the concentration of the filler suspension to 11, and after filtering, washing and dehydration, it is again configured into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 30 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0065] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0066] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0067] Embodiment 11 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 80 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0068] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0069] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0070] Example 12 Adopt high specific surface area (80~300m 2 / g) calcium silicate powder is used as a raw material and configured into a filler suspension with a mass concentration of 10% in a reactor; an alum solution with a mass concentration of 5% is added to adjust the concentration of the filler suspension to 10.51, and after filtering, washing and dehydration, it is configured again into a prefabricated composite filler suspension with a mass concentration of 10%, and the prefabricated composite filler suspension is treated with carbon dioxide for 80 minutes, and a composite filler is obtained after washing, filter pressing and breaking up.

[0071] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the composite filler is prepared into a suspension with a mass concentration of 10%, added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixture is formed on a net after stirring, and then pressed and dried to obtain a modified calcium silicate composite filler-filled paper.

[0072] Among them, the plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of hardwood pulp board to softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0073] Comparative Example 1 Untreated porous calcium silicate was selected and deionized water was added to prepare a filler liquid with a mass concentration of 10% and a pH value of 12.07.

[0074] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the filler liquid is added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixed pulp is formed on a screen after stirring, and then the paper is obtained after pressing and drying.

[0075] The plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of the hardwood pulp board to the softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 0%, the proportion of the plant fiber chemical pulp board is 100%, and the beating degree of the mixed pulp is 45°SR.

[0076] Comparative Example 2 Untreated porous calcium silicate was selected and deionized water was added to prepare a filler liquid with a mass concentration of 10% and a pH value of 12.07.

[0077] The plant fiber chemical pulp board and chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; the filler liquid is added to the mixed pulp, and then a cationic polyacrylamide solution with a mass concentration of 0.05% is added, and the mixed pulp is formed on a screen after stirring, and then the paper is obtained after pressing and drying.

[0078] The plant fiber chemical pulp board includes hardwood chemical pulp and softwood chemical pulp, the mass ratio of the hardwood pulp board to the softwood pulp board is 3:1, the proportion of chemical mechanical pulp is 15%, the proportion of the plant fiber chemical pulp board is 85%, and the beating degree of the mixed pulp is 45°SR.

[0079] When the filler content of all papers is controlled to be 15%, the paper bulk is tested using a thickness density meter and the paper strength is tested using a tensile strength tester. The filled papers prepared in Examples 1 to 12 are tested, and the test results are shown in the following table:

[0080] The test results of Comparative Examples 1 and 2 are shown in the following table:

[0081] It can be seen that in Comparative Examples 1 and 2, the pH value of the unmodified calcium silicate filler suspension reached 12.07, and the high filler dissolution rate led to an increase in its loss, affecting the filler yield. When unmodified calcium silicate is used as papermaking filler, when the proportion of chemical mechanical pulp increases, the bulk of the filled paper is significantly increased, and the tensile strength of the paper decreases.

[0082] The pH value of the suspension of calcium silicate modified by alum and carbon dioxide is reduced, the dissolution rate of fillers is reduced, and the loss is correspondingly reduced. Therefore, this modification method can improve the filler yield to a certain extent. At the same time, when the proportion of chemical mechanical pulp is 0%, taking Examples 1 to 6 as examples, it can be found through Comparative Example 1 that the modified composite filler filled paper has a relatively high bulk and its tensile index is reduced. When the proportion of chemical mechanical pulp in the filled paper is 15%, taking Examples 7 to 12 as examples, it can be found through Comparative Example 2 that the modified composite filler filled paper has a high bulk, but its tensile strength is lower than that of the unfilled paper in Comparative Example 2. By comparing Examples 1 to 6, it can be found that the higher the proportion of chemical pulp, although the bulk of the modified calcium silicate composite filler filled paper is lower than that of the paper with a high chemical mechanical pulp content, its tensile index is significantly improved relative to that of the paper with a high chemical mechanical pulp content.

[0083] In summary, the present invention provides a composite filler, a preparation method and an application thereof. By using alum and carbon dioxide to synergistically modify calcium silicate, the dissolution rate of calcium silicate filler can be reduced to a certain extent, and the filler yield can be improved; and a series of problems such as scaling and corrosion caused by high alkaline fillers in large-scale production of papermaking enterprises can be reduced to a certain extent. At the same time, the ultra-high ratio chemical pulp light paper prepared from the modified composite filler has a significantly improved bulk thickness under the condition of equivalent strength compared with the prior art.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A method for preparing a composite filler, characterized in that: include: Calcium silicate powder is used to prepare a filler suspension; adding an alum solution to the filler suspension to react and obtain a prefabricated composite filler; Using the prefabricated composite filler, preparing a prefabricated composite filler suspension; The prefabricated composite filler suspension is treated with carbon dioxide to obtain the composite filler through reaction.

2. The method for preparing a composite filler according to claim 1, characterized in that: The mass concentration of calcium silicate powder in the filler suspension is 8% to 15%.

3. The method for preparing a composite filler according to claim 1, characterized in that: The specific surface area of ​​the calcium silicate powder is 80 to 300 m 2 / g.

4. The method for preparing a composite filler according to claim 1, characterized in that: In the process of adding alum solution to the filler suspension to obtain the prefabricated composite filler, the mass concentration of the alum solution is 5% to 10%; after adding the alum solution, the pH value of the filler suspension is 10 to 11.

55.

5. The method for preparing a composite filler according to claim 1, characterized in that: The alum in the alum solution has an aluminum oxide content greater than 15% and an iron oxide content less than 0.7%.

6. A composite filler prepared by the method according to any one of claims 1 to 5, characterized in that: The dissolution rate of the composite filler is less than 0.05%, and the loss amount is less than 2.5%.

7. A method for preparing paper using the composite filler according to claim 6, characterized in that: include: The plant fiber chemical pulp board and the chemical mechanical pulp are deflaked and refined to obtain a mixed pulp; Using the composite filler, preparing a composite filler suspension; The composite filler suspension is added to the mixed slurry, and the cationic polyacrylamide solution is added, and after stirring, forming on a screen, pressing and drying, the paper filled with the modified calcium silicate composite filler is obtained.

8. The method for preparing a composite filler according to claim 7, characterized in that: The plant fiber chemical pulp board includes a hardwood chemical pulp board and a softwood chemical pulp board, and the mass ratio of the hardwood pulp board to the softwood pulp board is 3:1; among the plant fiber chemical pulp board and the chemical mechanical pulp, the mass percentage of the plant fiber chemical pulp board is 85% to 100%, and the mass percentage of the chemical mechanical pulp is 0 to 15%.

9. The method for preparing a composite filler according to claim 7, characterized in that: The mass concentration of the composite filler in the composite filler suspension is 8% to 15%; the mass concentration of the cationic polyacrylamide solution is 0.04% to 0.07%; the mass of the composite filler is 14% to 16% of the total mass; and the amount of the cationic polyacrylamide solution added to a single hand sheet is 0.3 to 0.5 mL.

10. A paper, characterized in that: The filler according to claim 6 is included in the paper with a basis weight of 70 g / m 2 Under these conditions, the solubility of the composite filler is 0.03% to 0.05%, and the bulk thickness of the paper is 1.5 to 2.85 cm 3 / g, the tensile strength of paper is 22.32~28.32kN / m.

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