Method for manufacturing paper-making filler using mixed solution of organic fiber and inorganic compound and use thereof

Abstract

The present invention relates to a method for manufacturing a paper-making filler using a mixed solution of an organic fiber and an inorganic compound, and a use thereof. The paper including the paper-making filler manufactured by the manufacturing method according to the present invention has greatly improved bulk compared to paper using an existing ground calcium carbonate filler, thus exhibiting excellent breaking length and superior smoothness. With such characteristics, high-quality paper can be produced even when using a larger amount of filler than ground calcium carbonate, thereby enhancing economic efficiency, reducing the amount of organic fiber used, and achieving energy savings in drying.

Description

Technical Field

[0001] The present invention relates to a method for preparing a filler for papermaking using a mixed solution of organic fibers and an inorganic compound, and a use thereof.Background Art

[0002] The raw materials used for manufacturing printing paper include wood pulp, fillers, and other additives. Among these, wood pulp is used as the main raw material, and next, the content of the filler is high. The filler is also used to improve paper qualities such as opacity, brightness, and printability, but because the price of the filler is lower compared to wood pulp, a cost-saving effect can also be expected due to the replacement of pulp.

[0003] Recently, in the paper industry, as the price of not only pulp raw materials but also oil is on an increasing trend, the development of technology for the efficient utilization of fillers, which are not only cheaper than pulp but also advantageous compared to pulp in terms of drying load, can be said to be a very important task. However, because these fillers have disadvantages such as hindering the formation of hydrogen bonds between fibers and reducing the tensile strength and stiffness of the paper, the use of fillers has been limited. To overcome problems such as the above, various measures have been sought. To prevent a decrease in paper strength while increasing the filler content, many technologies such as a mixture of pulp and filler (fiber-filler composite), preflocculation, lumen loading, and hybrid calcium carbonate have been developed and have also been applied.

[0004] For example, the pre-flocculation technology refers to a technology that forms stabilized preflocs having a uniform size by mixing calcium carbonate and an ionic polymer to cause the calcium carbonate particles to form aggregates, and then forming a strong vortex. These preflocs are used as a raw material for papermaking, and when paper is manufactured by adding the preflocs to the raw material for papermaking, paper having a higher tensile strength than paper using ordinary calcium carbonate can be manufactured. However, its use is being limited because the bulk does not increase.

[0005] As conventional technologies for manufacturing a filler for papermaking, Korean Laid-open Patent Publication No. 2009-0040682 discloses a method for manufacturing paper to which filler pre-flocculation using amphoteric polyacrylamide is applied; Korean Laid-open Patent Publication No. 2005-0023824 discloses a method for manufacturing paper using a cationic starch; and Korean Laid-open Patent Publication No. 2015-1510313 discloses a method for manufacturing hybrid calcium carbonate in which calcium carbonate and a calcium compound are pre-flocculated with an ionic polymer, and then carbon dioxide is injected to cause the calcium carbonate and newly generated calcium carbonate to aggregate. However, a method for preparing a filler for papermaking using a mixed solution of organic fibers and an inorganic compound of the present invention and a use thereof have not yet been disclosed.Detailed Description of the Invention Technical Problem

[0006] The present invention has been devised in response to needs such as those described above, and the present invention provides a method for preparing a filler for papermaking using a mixed solution of organic fibers and an inorganic compound, and a use thereof, and the present invention was completed by confirming that paper manufactured using the filler prepared by the filler preparation method of the present invention has superior bulk and breaking length compared to paper manufactured by a conventional preparation method.Solution to Problem

[0007] To achieve the above object, the present invention provides a method for preparing a filler for papermaking, comprising the steps of: (1) preparing a mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100, and having a solids content of 1 to 60 wt%; (2) adding an ionic polymer to the mixed aqueous solution and stirring to form preflocs; and (3) preparing the filler for papermaking by, with respect to 100 parts by weight of the inorganic compound contained in the mixed aqueous solution in which the preflocs were formed, adding 10 to 1000 parts by weight of a calcium compound, and then injecting carbon dioxide at 10 to 80 °C until a pH is maintained at 7.0 ± 1.0.

[0008] According to an Example of the present invention, the step (1) may comprise: (1-1) a step of preparing a mixed solution having a solids content of 1 to 60 wt% by mixing organic fibers and an inorganic compound in a weight ratio of 1 : 5 to 100, and then adding water; and (1-2) a step of preparing a mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100, and having a solids content of 1 to 60 wt%, by grinding the mixed solution.

[0009] In addition, the inorganic compound may be one or more selected from calcium carbonate (CaCO 3 ), calcium oxide (CaO), calcium hydroxide (Ca(OH) 2 ), magnesium carbonate (MgCO 3 ), gypsum, kaolin, calcined clay, talc, perlite, diatomaceous earth, zinc carbonate, lithium carbonate, magnesium hydroxide, and aluminum trihydrate.

[0010] In addition, the calcium carbonate may be one or more selected from ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC).

[0011] In addition, the fiber fibril may comprise one or more selected from cellulose and chitin.

[0012] In addition, the ionic polymer may be one or more selected from an anionic polymer and a cationic polymer.

[0013] In addition, the anionic polymer may be one or more selected from a polysaccharide, a protein, polyvinyl alcohol, polyvinyl acetate, a cellulose derivative, epoxy acrylate, polyester, polyurethane, polyester acrylate, polyether acrylate, a polyolefin dispersion, polyamide, a vinyl copolymer, and polyacrylate.

[0014] In addition, the cationic polymer may be one or more selected from a polyamidoamine-epihalohydrin polymer, a polyalkyldiallylamine-epihalohydrin polymer, polyethyleneimine, polyacrylamide, polyamine, polyvinylamine, and a cationic starch.

[0015] In addition, in the step (2), the amount of the ionic polymer added may be 0.01 to 10 parts by weight of one or more kinds of ionic polymers with respect to 100 parts by weight of the mixed aqueous solution.

[0016] In addition, in the step (3), the calcium compound may be one or more selected from calcium oxide, calcium hydroxide, calcium sulfate, and calcium phosphate.

[0017] In addition, the present invention provides a filler for papermaking, wherein a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region, and a metal carbonate has a shape in which it is disposed on the fiber fibrils, the filler for papermaking comprising 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate (this filler is hereinafter referred to as hybrid flexible calcium carbonate (HFCC)).

[0018] In addition, the present invention provides a method for manufacturing paper, comprising the steps of: (1) mixing 1 to 60 wt% of the above-described filler for papermaking (HFCC); and 40 to 99 wt% of beaten natural pulp or recycled pulp; and (2) introducing the mixture of the step (1) into a paper machine to manufacture paper.

[0019] In addition, the present invention provides a method for manufacturing ultra-high-filler-content paper, in which an inorganic material is 50 wt% or more of the total weight, the method comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking (HFCC); and 1 to 40 wt% of beaten natural pulp or recycled pulp; and adding 1 to 30 % of an ionic polymer for strength enhancement; and (2) introducing the mixture of the step (1) into a paper machine to manufacture the paper.

[0020] In addition, the present invention provides a method for manufacturing a composite, comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking (HFCC); and 1 to 50 wt% of beaten natural pulp or recycled pulp; (2) introducing the mixture of the step (1) into a paper machine to manufacture a paper-form sheet; and (3) after the step (2), manufacturing the composite by impregnating, spraying, or performing curtain coating with 50 to 5000 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

[0021] In addition, the present invention provides a method for manufacturing stone paper, comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking and 1 to 50 wt% of beaten natural pulp or recycled pulp; (2) introducing the mixture of the step (1) into a paper machine to manufacture a paper-form sheet; and (3) after the step (2), manufacturing the stone paper by coating or impregnating with 1 to 50 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

[0022] In addition, the present invention provides a paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0023] In this case, the paper may comprise 1 to 60 wt% of the filler (HFCC).

[0024] In addition, the present invention provides ultra-high-filler-content paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0025] In this case, the ultra-high-filler-content paper may comprise the filler (HFCC) in an amount of 50 wt% or more based on the total weight of the ultra-high-filler-content paper.

[0026] In addition, the present invention provides a composite formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0027] In addition, the present invention provides a stone paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.Effects of Invention

[0028] The present invention relates to a method for preparing a filler for papermaking using a mixed solution of organic fibers and an inorganic compound, and a use thereof, wherein paper comprising the filler for papermaking prepared by the preparation method according to the present invention has a greatly improved paper bulk compared to paper using a conventional ground calcium carbonate filler, has the effect of possessing an excellent breaking length, and comes to have a characteristic of excellent smoothness. By using these characteristics, it becomes possible to make paper of excellent quality even when using a larger amount of the filler than ground calcium carbonate, and therefore, the economic feasibility is excellent, and the effects of reducing the amount of organic fibers used and reducing drying energy can be obtained.Brief Description of Drawings

[0029] FIG. 1 is a process flowchart schematically showing a process of manufacturing paper using the filler for papermaking prepared according to the present invention. FIG. 2 is a comparison of the bulk (A), breaking length (B), and internal bond strength (C) of the papers prepared in Examples 4 to 9 and Comparative Examples 1 to 4 of the present invention. FIG. 3 is an electron micrograph showing the timing of the carbon dioxide reaction in step 3 of Example 1 of the present invention, wherein FIG. 3A shows an initial state of the carbon dioxide reaction, FIG. 3B shows an intermediate state of the carbon dioxide reaction, and FIG. 3C is FIG. 3A is an electron micrograph of a final form of the carbon dioxide reaction. Mode for Carrying out the Invention

[0030] The present invention relates to a method for preparing a filler for papermaking (HFCC), comprising the steps of: (1) preparing a mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100, and having a solids content of 1 to 60 wt%; (2) adding an ionic polymer to the mixed aqueous solution and stirring to form preflocs; and (3) preparing the filler for papermaking by, with respect to 100 parts by weight of the inorganic compound contained in the mixed aqueous solution in which the preflocs were formed, adding 10 to 1000 parts by weight of a calcium compound, and then injecting carbon dioxide at 10 to 80 °C until a pH is maintained at 7.0 ± 1.0.

[0031] In this case, the step (1) may also be performed by a method comprising: 1) preparing a separate mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100; 2) preparing by mixing an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100; or 3) mixing organic fibers and an inorganic compound and grinding to prepare a mixed aqueous solution having the same size and weight ratio.

[0032] According to an Example of the present invention, the step (1) may comprise: (1-1) a step of preparing a mixed solution by mixing organic fibers and an inorganic compound, and then adding water; and (1-2) a step of preparing a mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1 : 5 to 100, and having a solids content of 1 to 60 wt%, by grinding the mixed solution.

[0033] In this case, in the step (1-1), the organic fibers and the inorganic compound may be mixed in a weight ratio of 1 : 5 to 100, and the mixed solution may have a solids content of 1 to 60 wt%.

[0034] In the step (1-2), the step of grinding the mixed solution of organic fibers and the inorganic compound not only reduces the size of the inorganic compound to an appropriate level, but also, as the organic fibers are fibrillated with low energy by friction with the inorganic compound in a strong alkaline state due to hydration of the inorganic compound, energy consumption in the preparation of the organic fiber fibrils can be greatly reduced compared to a method of separately preparing and using microfibrils or nanofibrils. The grinding is preferably performed using a grinder or a ball mill, but is not limited thereto.

[0035] In the steps (2) and (3), preflocs are prepared using the inorganic compound and the organic fiber fibrils that were mixed together, and by reacting in water through a method of adding calcium oxide thereon and injecting carbon dioxide, a metal carbonate is made to adhere to the surface of the preflocs, whereby a robust and elongated metal carbonate can be prepared.

[0036] In the present invention, preflocculation means changing the inorganic compound particles and the organic fiber fibrils into an aggregate by treating them with coagulants and a flocculant.

[0037] The stirring of the step (2) is preferably performed at 500 to 5,000 rpm; if stirring is performed at less than 500 rpm, a problem arises in that the physical properties of the paper deteriorate because the size of the aggregate particles formed is very large when paper is manufactured using them, and if stirring is performed at more than 5,000 rpm, a problem arises in that it is not effective because the particle size becomes too small.

[0038] The particle size of the preflocs formed in the step (2) may be 1 to 100 µm.

[0039] If the particle size of the preflocs formed in the step (2) is less than 1 µm, there is a problem that there is no effect of improving the physical properties of paper manufactured using them because the size of the preflocs is very small, and if it exceeds 100 µm, there is a problem that it is difficult for the filler to be uniformly distributed when manufacturing paper using them.

[0040] The inorganic compound may comprise one or more selected from calcium carbonate (CaCO 3 ), calcium oxide (CaO), calcium hydroxide (Ca(OH) 2 ), magnesium carbonate (MgCO 3 ), gypsum, kaolin, calcined clay, talc, perlite, diatomaceous earth, zinc carbonate, lithium carbonate, magnesium hydroxide, and aluminum trihydrate, and may preferably comprise a metal carbonate comprising one or more selected from calcium carbonate, magnesium carbonate, aluminum carbonate, lithium carbonate, and zinc carbonate, and more preferably may be calcium carbonate, but is not limited thereto.

[0041] The calcium carbonate is preferably one or more selected from ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC), but is not limited thereto, and the fiber fibril preferably comprises one or more selected from cellulose and chitin, but is not limited thereto.

[0042] The ionic polymer is preferably one or more ionic polymers selected from an anionic polymer and a cationic polymer, but is not limited thereto.

[0043] The anionic polymer is preferably one or more selected from a polysaccharide, a protein, polyvinyl alcohol, polyvinyl acetate, a cellulose derivative, epoxy acrylate, polyester, polyurethane, polyester acrylate, polyether acrylate, a polyolefin dispersion, polyamide, a vinyl copolymer, and polyacrylate, but is not limited thereto. The cationic polymer is preferably one or more selected from a polyamidoamine-epihalohydrin polymer, a polyalkyldiallylamine-epihalohydrin polymer, polyethyleneimine, polyacrylamide, polyamine, polyvinylamine, and a cationic starch, but is not limited thereto.

[0044] The amount of the ionic polymer added in the step (2) is preferably 0.01 to 10 parts by weight of the ionic polymer with respect to 100 parts by weight of the mixed aqueous solution, and more preferably 0.1 to 0.3 parts by weight of the ionic polymer, but is not limited thereto.

[0045] In the step (3), the calcium compound is preferably one or more calcium compounds selected from calcium oxide, calcium hydroxide, calcium sulfate, and calcium phosphate, and more preferably is calcium oxide or calcium hydroxide, but is not limited thereto.

[0046] In a case where calcium hydroxide is used as the calcium compound, calcium hydroxide prepared by reacting sodium hydroxide and calcium chloride may be used. That is, because calcium hydroxide can be formed by reacting sodium hydroxide and calcium chloride, calcium carbonate can be formed by reacting with carbon dioxide even without directly adding calcium hydroxide.

[0047] In the step (3), the calcium contained in the calcium compound component is dissolved in the form of a salt such as calcium hydroxide in the diluted solution in which the preflocs are formed, and calcium carbonate can be synthesized through a carbonation reaction by injecting carbon dioxide thereinto. In this case, it is preferable to react the carbon dioxide until the pH of the diluted solution generally reaches 7.0, and it is necessary to carry out the reaction until the injected carbon dioxide no longer reacts. In addition, in the step (3), the temperature for reacting the diluted solution by injecting carbon dioxide is preferably 10 to 80 °C.

[0048] In addition, the present invention provides a filler for papermaking, wherein a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region, and a metal carbonate has a shape in which it is disposed on the fiber fibrils, the filler comprising 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0049] As the filler has a structure in which the metal carbonate is disposed on the fiber fibrils, when forming paper comprising the same, the bulk of the paper is greatly improved, it has an excellent breaking length, and it may be more advantageous in terms of having excellent smoothness. In addition, as the filler satisfies the content range of the fiber fibrils and the metal carbonate, when forming paper comprising the same, the bulk of the paper is greatly improved, it has an excellent breaking length, and it may be more advantageous in terms of having excellent smoothness.

[0050] In addition, the present invention provides a method for manufacturing paper, comprising the steps of: (1) mixing 1 to 60 wt% of the above-described filler for papermaking (HFCC); and 40 to 99 wt% of beaten natural pulp or recycled pulp; and (2) introducing the mixture of the step (1) into a paper machine to manufacture paper.

[0051] In addition, the present invention provides a method for manufacturing ultra-high-filler-content paper, in which an inorganic material is 50 wt% or more of the total weight, the method comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking and 1 to 50 wt% of beaten natural pulp or recycled pulp; and adding 1 to 30 % of an ionic polymer for strength enhancement; and (2) manufacturing the ultra-high-filler-content paper by introducing the mixture of the step (1) into a paper machine.

[0052] In addition, the present invention provides a method for manufacturing a composite, comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking and 1 to 50 wt% of beaten natural pulp or recycled pulp; (2) introducing the mixture of the step (1) into a paper machine to manufacture a paper-form sheet; and (3) after the step (2), manufacturing the composite by performing impregnation, spraying, and / or curtain coating with 50 to 5000 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

[0053] The composite is a material that exhibits new characteristics different from previous materials by combining two or more materials of different characteristics, and the difference from a synthetic material is that the constituent components are still separated and unchanged. The composite can replace metal instruments or metal sheets in airplanes or automobiles, and its uses, such as for cell phone cases, tennis rackets, golf clubs, industrial pipes or tanks, are endless, and continuous development of applications is being carried out. In the present invention, as a synthetic polymer or a biodegradable polymer is added to the metal carbonate, it is characterized in that high strength and dimensional stability are enhanced, and it can be used for various applications.

[0054] In addition, the present invention provides a method for manufacturing stone paper, comprising the steps of: (1) mixing 50 to 99 wt% of the above-described filler for papermaking and 1 to 50 wt% of beaten natural pulp or recycled pulp; (2) introducing the mixture of the step (1) into a paper machine to manufacture a paper-form sheet; and (3) after the step (2), manufacturing the stone paper by coating or impregnating with 1 to 50 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

[0055] Although the stone paper uses the name 'paper', it is something that can replace paper or plastic. The stone paper is robust, and although it has waterproof properties, it has a characteristic of decomposing in a short time like a biodegradable plastic after use; it can be processed into various forms and can be folded, and its printability is superior to that of ordinary paper.

[0056] Currently manufactured stone papers have a density of 1.0 or more and thus have the disadvantage of being heavy when making books or printed materials, but the stone paper using the metal carbonate manufactured in the present invention has a density of 1.0 or less and thus can be comparable to ordinary paper, and as it has high hydrophobicity, high-grade printability, and biodegradability, it is an inexpensive material that can replace non-degradable plastics or paper that uses wood.

[0057] In addition, the present invention provides a paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0058] In this case, the paper may comprise 1 to 60 wt% of the filler (HFCC).

[0059] In addition, the present invention provides ultra-high-filler-content paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0060] In this case, the ultra-high-filler-content paper comprises the filler (HFCC) in an amount of 50 wt% or more based on the total weight of the ultra-high-filler-content paper.

[0061] In addition, the present invention provides a composite characterized in that the composite is formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0062] In addition, the present invention provides a stone paper characterized in that the stone paper is formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, and wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

[0063] As the paper and the ultra-high-filler-content paper use the filler (HFCC), the bulk is greatly improved, they have an excellent breaking length, and they may be more advantageous in terms of having excellent smoothness.

[0064] In addition, as the filler satisfies the weight range of the fiber fibrils and the metal carbonate, it may be more advantageous in terms of manufacturing a biocomposite and a stone paper.Mode for Carrying out the Invention

[0065] Hereinafter, the present invention will be described in more detail using Examples. It is apparent to a person having ordinary skill in the art to which the present invention pertains that these Examples are only for describing the present invention more specifically, and the scope of the present invention is not limited by them.Example 1. Preparation 1 of Filler for Papermaking

[0066] Step 1-1: A mixed solution was prepared by adding 2 g of organic fibers and 40 g of calcium oxide (CaO. Taekyung Industrial. Diameter about 10 µm) to 200 ml of water.

[0067] The organic fibers were used after beating bleached hardwood chemical pulp to a standard freeness of 200 ml CSF. It was confirmed that the average width of the pulp was about 15.5 µm.

[0068] Step 1-2: The mixed solution prepared in the step 1-1 was placed in a ball mill and treated for 1 hour. After the ball mill treatment was finished, the sizes of the calcium oxide and the width of the organic fiber fibrils were measured with an electron microscope. As a result, it was confirmed that the average diameter of the calcium oxide was 3.1 µm, and the average width of the organic fibers was about 678 nm.

[0069] Step 2: With respect to 100 parts by weight of total solids in the mixed aqueous solution of calcium oxide and organic fiber fibrils after the ball mill treatment was finished, 0.1 parts by weight of a cationic polymer, polyacrylamide (PAM, Ciba Chemical Korea), was added to impart a weak cationic property, and thereafter, in a state where a vortex was formed, with respect to 100 parts by weight of total solids, 0.1 parts by weight of an anionic polymer, a micropolymer (Eka Chemical Korea), was added so that the overall zeta potential, that is, the charge, maintained neutrality. Here, the precise amount of ionic polymer added was based on the zeta potential. Thereafter, the diluted solution was stirred at a rotation speed of 2,000 rpm for 10 minutes to form preflocs.

[0070] Step 3: After the step 2, after additionally adding 5 g of calcium oxide to the mixed aqueous solution, the filler for papermaking was prepared by continuously injecting carbon dioxide into the diluted solution while stirring at 2000 rpm at 30 °C until the pH reached 7.0. Here, the reaction endpoint was also set as the point at which the injection rate and the discharge rate of carbon dioxide became equal.

[0071] In this case, a total amount of 45 g of calcium oxide reacted to form 80 g of precipitated calcium carbonate, thereby forming a filler attached to 2 g of cellulose fibrils (cellulose fibrils: precipitated calcium carbonate = 1:40).Example 2. Preparation 2 of Filler for Papermaking

[0072] Step 1-1: A mixed solution was prepared by adding 2 g of organic fibers and 40 g of ground calcium carbonate (GCC, Omyakorea Co., Ltd. Diameter 5 µm or more) to 200 ml of water.

[0073] The organic fibers were used after beating bleached hardwood chemical pulp to a standard freeness of 200 ml CSF. It was confirmed that the average width of the pulp was about 15.5 µm.

[0074] Step 1-2: The mixed solution prepared in the step 1-1 was placed in a ball mill and treated for 1 hour. After the ball mill treatment was finished, the sizes of the ground calcium carbonate and the width of the organic fiber fibrils were measured with an electron microscope. As a result, it was confirmed that the average diameter of the calcium carbonate was 3.2 µm, and the average width of the organic fibers was about 825 nm.

[0075] Step 2: With respect to 100 parts by weight of total solids in the mixed aqueous solution of ground calcium carbonate and organic fiber fibrils after the ball mill treatment was finished, 0.1 parts by weight of a cationic polymer, polyacrylamide (PAM, Ciba Chemical Korea), was added to impart a weak cationic property, and thereafter, in a state where a vortex was formed, with respect to 100 parts by weight of total solids, 0.1 parts by weight of an anionic polymer, a micropolymer (Eka Chemical Korea), was added so that the overall zeta potential, that is, the charge, maintained neutrality. Here, the precise amount of ionic polymer added was based on the zeta potential.

[0076] Thereafter, the diluted solution was stirred at a rotation speed of 2,000 rpm for 10 minutes to form ground calcium carbonate-cellulose fibril preflocs.

[0077] Step 3: After adding 22.5 g of calcium oxide to the preflocs formed in the step 2 under a vortex of 2,000 rpm at 30 °C, the filler for papermaking was prepared by continuously injecting carbon dioxide into the diluted solution until the pH reached 7.0. Here, the reaction endpoint could also be set as the point at which the injection rate and the discharge rate of carbon dioxide became equal. In this case, 40 g of ground calcium carbonate and 40 g of newly generated precipitated calcium carbonate formed a filler (HFCC) attached to the surface of the cellulose fibrils.Example 3. Preparation 3 of Filler for Papermaking

[0078] Step 1-1: A diluted mixture was prepared by adding 5.6 g of the calcium oxide used in step 1-1 of Example 1, 30 g of the ground calcium carbonate used in step 1-1 of Example 2, and 2 g of organic fibers to 200 ml of water.

[0079] Step 1-2: Grinding was performed using a ball mill as in step 1-2 of Example 2. After grinding, the average width of the cellulose fibrils was confirmed to be 782 nm.

[0080] Step 2: Preflocs were formed in the same manner as in step 2 of Example 2.

[0081] Step 3: In the same manner as step 3 of Example 2, to make the total amount of calcium oxide 22,5 g, 16.9 g of calcium oxide, excluding the 5.6 g of calcium oxide added in the step 1-1, was additionally added so that the total amount of calcium oxide became 22.5 g, and the filler was prepared by injecting carbon dioxide into the ground calcium carbonate at 30 °C to attach it to the cellulose fibrils together with newly generated precipitated calcium carbonate. The reason for adding the calcium oxide in divided portions in this manner is to maintain an alkaline state during the ball mill treatment to aid in the fibrillation of the organic fibers.Example 4. Preparation 1 of Paper Comprising Filler for Papermaking

[0082] Step 1: As pulp for making paper, bleached softwood pulp and bleached hardwood pulp were mixed at a ratio of 2:8, and after performing beating so that the freeness became 500 ml CSF (Canadian Standard Freeness), the filler for papermaking prepared in Example 1 and the pulp were mixed at a weight ratio of 25:75.

[0083] Step 2: Using the filler for papermaking and the pulp mixed in the step 1, paper having a basis weight of 60 g / m 2< was manufactured according to a paper testing method (ISO 5269 / 1) (FIG. 1).Example 5. Preparation 2 of Paper Comprising Filler for Papermaking

[0084] Paper was manufactured under the same conditions as in Example 4, except that in step 1 of Example 4, the filler for papermaking prepared in Example 1 and the pulp were mixed at a weight ratio of 35:65.Example 6. Preparation 3 of Paper Comprising Filler for Papermaking

[0085] Paper was manufactured under the same conditions as in Example 4, except that in step 1 of Example 4, the filler for papermaking prepared in Example 2 was used.Example 7. Preparation 4 of Paper Comprising Filler for Papermaking

[0086] Paper was manufactured in the same manner as in Example 4, except that in step 1 of Example 4, the filler for papermaking prepared in Example 2 and pulp were mixed at a weight ratio of 35:65.Example 8. Preparation 5 of Paper Comprising Filler for Papermaking

[0087] Paper was manufactured by performing in the same manner as in Example 4, except that the filler for papermaking used in step 1 of Example 4 was the filler for papermaking prepared in Example 3.Example 9. Preparation 6 of Paper Comprising Filler for Papermaking

[0088] Paper was manufactured in the same manner as in Example 4, except that in step 1 of Example 4, the filler for papermaking prepared in Example 3 and pulp were mixed at a weight ratio of 35:65.Comparative Example 1.

[0089] Step 1: As pulp for manufacturing paper, bleached softwood pulp and bleached hardwood pulp were mixed at a ratio of 2:8, and beating was performed so that the freeness became 500 ml CSF (Canadian Standard Freeness).

[0090] Step 2: Ground calcium carbonate (GCC, Omyakorea Co., Ltd. 2 to 3 µm) as a filler and the pulp beaten in the step 1 were mixed at a weight ratio of 25:75, and paper having a basis weight of 60 g / m 2< was manufactured according to a paper testing method (ISO 5269 / 1).Comparative Example 2.

[0091] Paper was manufactured under the same conditions as in the Comparative Example 1, with the exception that in step 2 of the Comparative Example 1, the filler and the pulp were mixed at a weight ratio of 35:65.Comparative Example 3.

[0092] Paper was manufactured under the same conditions as in the Comparative Example 1, with the exception that in step 2 of the Comparative Example 1, precipitated calcium carbonate (PCC, manufactured by Artone Paper. About 1.5 µm) was used instead of ground calcium carbonate.Comparative Example 4.

[0093] Paper was manufactured under the same conditions as in the Comparative Example 1, with the exceptions that in step 2 of the Comparative Example 1, precipitated calcium carbonate (PCC, manufactured by Artone Paper. About 1.5 µm) was used instead of ground calcium carbonate, and the filler and the pulp were mixed at a weight ratio of 35:65.

[0094] The GCC filler used in the Comparative Examples 1 and 2 was a filler mainly used in a general wood-free paper factory, and the PCC filler used in the Comparative Examples 3 and 4 is a high-grade filler used to increase bulk and brightness more than GCC.Experimental Example 1. Analysis of Paper Characteristics

[0095] To analyze the characteristics of the paper manufactured comprising the filler for papermaking according to the present invention, the following experiments were conducted.(1) Analysis of bulk and breaking length of paper

[0096] To evaluate the effectiveness of the papers prepared in Examples and Comparative Examples according to the present invention, the bulk and breaking length of the prepared papers were analyzed. The basis weight of the paper prepared in Examples 4-9 and Comparative Examples 1 to 4 was 60 g / m 2< . In addition, the bulk and breaking length were analyzed. The bulk was obtained by measuring the density of the paper (unit g / cm 3< ) and then taking the reciprocal (bulk unit cm 3< / g). The breaking length (unit km) is a value obtained by dividing the tensile strength (unit kN / m) by the basis weight of the paper, and as a value that eliminates the influence of the deviation of the basis weight in the comparison of tensile strength, it can be said to be a more reliable value in the comparison of strength.

[0097] As a result, as shown in Table 1 below, the bulk of the paper prepared with GCC (ground calcium carbonate) in Comparative Example 1 and Comparative Example 2 was 1.71 and 1.68, respectively, which was much lower than the bulk of the paper prepared in Examples 4 to 9, which was 1.86 to 1.92, and this leads to a very large difference in thickness and bending stiffness, which are important physical properties of actual paper. In particular, since bending stiffness is proportional to the third power of the paper thickness, a very large difference in bending stiffness occurs (Table 1).

[0098] Since the bending stiffness decreases when the filler content is increased, this is an important reason why the filler content cannot be increased, but it was confirmed that the filler according to the present invention exhibits a very high bending stiffness (bending stiffness of Examples 4 to 9 was 550 to 680; bending stiffness of Comparative Examples 1 and 2 was 150 to 250).

[0099] The bulk of the paper prepared using PCC (precipitated calcium carbonate) in Comparative Examples 3 and 4 was 1.84 and 1.83, respectively, which can exhibit a higher bulk than ground calcium carbonate, and it can be seen that it exhibits a bulk value similar to the bulk of Examples 4 to 9.

[0100] However, it can be confirmed that precipitated calcium carbonate (PCC) has a very low tensile strength compared to Examples 4 to 9 (Table 1 and FIG. 2).

[0101] In addition, as shown in Table 1 below, the breaking length of the paper manufactured using ground calcium carbonate (GCC) in Comparative Example 1 and Comparative Example 2 was shown to be 2.18 when 25 % of filler was added, and 1.84 when 35 % was added. The breaking length of the paper manufactured in Examples 4 to 9 was shown to be 3.13 to 3.53 when 25 % of filler was added, and 3.07 to 3.14 when 35 % of filler was added, and thus, compared to Comparative Examples 1 to 2, it was confirmed that the breaking length of Examples 4 to 9 of the present invention was significantly higher under the same filler content.

[0102] In the case of the breaking length of paper manufactured using precipitated calcium carbonate (PCC), it was 1.88 when 25 % of filler was added and 1.65 when 35 % was added, which was lower under the same filler content than in the case of Examples 4 to 9 or even in the case of Comparative Example 1 and Comparative Example 2 using ground calcium carbonate (GCC).

[0103] Accordingly, it could be confirmed that the paper manufactured using the filler for papermaking according to the present invention has high bulk and breaking length. FIG. 2 compared the bulk, breaking length, and internal bond strength when 25 % and 35 % of filler were added. It was confirmed that the bulk, breaking length, and internal bond strength of Examples 4 to 9 were all higher than in the case of using ground calcium carbonate or precipitated calcium carbonate as a filler.(2) Analysis of brightness and smoothness of paper

[0104] To evaluate the effectiveness of the papers prepared in Examples and Comparative Examples according to the present invention, the brightness and smoothness of the prepared papers were analyzed. Specifically, the brightness analysis was measured using the ISO 2470 method, which is a method for measuring paper brightness, and the smoothness was measured using the Bekk smoothness method TAPPI T479 cm-99.

[0105] As a result, as disclosed in Table 1 below, Comparative Example 1 and Comparative Example 2 used ground calcium carbonate, and the brightness showed an average of 86.3 %. Comparative Example 3 and Comparative Example 4 used precipitated calcium carbonate, and showed an average brightness of 88.8 %. That is, precipitated calcium carbonate showed a significantly higher brightness than ground calcium carbonate. The average brightness of Examples 4 and 5 was 88.5 %, which was higher than in the case of ground calcium carbonate and was at a level similar to that of precipitated calcium carbonate. However, the average brightness of Examples 6 and 7 was 87.3 %, which was lower than in the case of using only precipitated calcium carbonate. The average brightness of Examples 8 and 9 was 88.8 %, which was at a level similar to the brightness of precipitated calcium carbonate, and it was judged that this result was due to the effect of precipitated calcium carbonate being mainly synthesized and attached to the filler surface of Examples 8 and 9. It was judged that the case of Examples 6 and 7 was due to a significant amount of ground calcium carbonate being included.

[0106] It could be seen that the paper comprising HFCC, which is the filler for papermaking according to the present invention, has superior bulk, breaking length, and bending stiffness than in the case of ground calcium carbonate or precipitated calcium carbonate, and has a characteristic in that brightness and smoothness are maintained. [Table 1]Results of Paper Characteristic AnalysisType of PaperType of FillerFiller:Pul p Mixing RatioBrightnes s (%)Bulk (cc / g )Breakin g Length (km)Tensile Strengt h (kN / m)Smoothnes s* (sec)Internal Bond Strengt h (lbfft / in 2< × 1000)Bendin 9 Stiffnes s (Gurley unit)Example 4Exampl e 125:7588.81.893.452.0312.375.8652.4Example 5Exampl e 135:6588.11.913.131.8413.871.5565.3Example 6Exampl e 225:7587.41.863.131.8515.777.2621.5Example 7Exampl e 235:6587.21.863.071.8115.574.3548.6Example 8Exampl e 325:7588.81.883.532.0814.874.3635.8Example 9Exampl e 335:6588.91.893.141.8513.272.1568.2Comparativ e Example 1GCC25:7586.21.712.181.2813.468.5245.6Comparativ e Example 2GCC35:6586.31.681.841.0812.765.2168.2Comparativ e Example 3PCC25:7588.61.841.881.1114.566.3235.6Comparativ e Example 4PCC35:6589.11.831.650.9515.862.5142.8 (3) Evaluation of Shape and Composition of Filler

[0107] With respect to the filler for papermaking prepared in Examples 1 to 3, by observing through an electron microscope during the intermediate process of filler formation, the process of calcium carbonate attaching and forming on the central region of a plurality of fiber fibrils could be confirmed, and this is shown in FIG. 3. As seen in FIG. 3, when calcium carbonate is formed on the fiber fibrils, it can be seen that a plurality of fiber fibrils is involved, and when sufficient calcium carbonate is attached, the appearance of the fiber fibrils is no longer visible. As a result, it was confirmed that the filler for papermaking prepared in Examples 1 to 3 has a plurality of fiber fibrils present in a central region, and has a shape in which calcium carbonate is attached to the fiber fibrils.

[0108] Also, the fiber fibril and metal carbonate content were measured using the standard method TAPPI T211 om-02 (Ash in wood, pulp and paperboard: combustion at 525 °C). That is, from a filler sample using the prepared calcium carbonate metal salt, moisture was removed at 105 °C, and after measuring the total weight (A), it was treated again at 525 °C for 1 hour and then cooled to measure its weight (B). At this time, the calcium carbonate remains as it is, but all of the fiber fibrils are removed as water and carbon dioxide. The value (A-B) is the weight of the fiber fibrils, and B becomes the weight of the calcium carbonate.

[0109] In addition, the content of fiber fibrils and metal carbonate within the filler prepared in Examples 1 to 3 was measured, and the results are shown in Table 2 below. The specific gravity of calcite-form calcium carbonate is 2.7, and the specific gravity of cellulose is known to be 1.5. Therefore, if the weights of the calcium carbonate and the fiber fibrils are known, their volume can be calculated. [Table 2]ItemFiber Fibril (wt%)Calcium Carbonate (wt%)Fiber Fibril (vol%)Calcium Carbonate (vol%)Example 13.296.85.694.4Example 24.295.87.392.7Example 33.896.26.693.4

[0110] As can be seen in Table 2 above, it could be seen that Examples 1 to 3 according to the present invention satisfy the content range of fiber fibrils and metal carbonate according to the present invention, and accordingly, it can be seen that effects of improved bulk and excellent breaking length and smoothness, as in Table 1 above, can all be expressed simultaneously.<Preparation of Ultra-High-Filler-Content Paper>

[0111] Step 1: As pulp for making ultra-high-filler-content paper, bleached softwood pulp and bleached hardwood pulp were mixed at a ratio of 5:5, and after performing beating so that the freeness became 300 ml CSF (Canadian Standard Freeness), the filler for papermaking prepared in Example 1 and pulp were mixed at a weight ratio of 60:40, and this was referred to as 'ultra-high-filler-content paper 1' stock. Also, the filler for papermaking and pulp were mixed at a weight ratio of 70:30, and this was referred to as 'ultra-high-filler-content paper 2' stock.

[0112] Step 2: To each of the 'ultra-high-filler-content paper 1' stock and 'ultra-high-filler-content paper 2' stock mixed in the step 1, 5 wt% of epoxy resin relative to the solids content was added, and paper having a basis weight of 60 g / m 2< was manufactured according to a paper testing method (ISO 5269 / 1). The physical properties of the manufactured ultra-high-filler-content paper are shown in Table 3 in comparison with the physical properties of Comparative Example 2. The content of the filler included in the paper was calculated by comparing the remaining solids with the initial paper weight after reacting the paper at 525 °C for 1 hour, and is shown as ash content in Table 3. The bulk, breaking length, and smoothness of the ultra-high-filler-content paper to which 50 % or more of filler was added were significantly superior to those of Comparative Example 2. Therefore, it was confirmed that the filler prepared in Example 1 can be used for the preparation and use of ultra-high-filler-content paper. [Table 3]- Comparison of Physical Properties of Ultra-High-Filler-Content PaperType of PaperType of FillerFiller:Pulp Mixing RatioAsh Content (wt%)Brightness (%)Bulk (cc / g)Breaking Length (km)Tensile Strength (kN / m)Smoothness* (sec)Ultra-high-filler-content paper 1Example 160:4057.588.81.982.451.4342.3Ultra-high-filler-content paper 2Example 170:3066.789.12.102.131.2544.8Comparative Example 2GCC35:6533.286.31.681.841.0812.7 <Preparation Example 2: Preparation of Composite>

[0113] Step 1: To prepare a sheet for making a biocomposite, after performing beating on bleached softwood pulp so that the freeness became 300 ml CSF (Canadian Standard Freeness), it was mixed with the filler for papermaking prepared in Example 1 at a weight ratio of 10:90 (beaten bleached softwood pulp:filler of Example 1), and to this stock, 8 wt% of epoxy resin relative to the solids content was added to prepare a paper specimen having a basis weight of 80 g / m 2< according to a paper testing method (ISO 5269 / 1).

[0114] Step 2: After melting PLA at 220 to 240 °C, curtain coating was performed at 350 g / m 2< on the paper prepared in step 1 to prepare a 'biocomposite'. For comparison, a sheet was prepared with only PLA at 430 g / m 2< without a paper specimen, and was referred to as 'biocomposite PLA'. The temperature of the nozzle was maintained at 240 °C. In the case of the paper specimen, coating was performed with the temperature raised to 100 °C, a vacuum plate was applied to the side opposite to where the coating was performed, and a vacuum of 0.6 atm was maintained to adjust for effective internal penetration of the PLA.

[0115] Step 3: The biocomposite was completed after smoothing the surface of the paper specimen, into which the PLA had sufficiently penetrated, using a roller.

[0116] The weight and density of the prepared biocomposite were measured at room temperature, the PLA content was calculated, and the content of calcium carbonate was measured by measuring the weight after treating at 525 °C for 3 hours. In addition, the tensile strength was measured and is shown in Table 4. [Table 4]- Physical Properties of BiocompositeType of PaperType of FillerAsh Content (wt%)Basis Weight (g / m 2< )Tensile Strength (MPa)Elongation (%)PLA Content (wt%)BiocompositeExample 117.2433.334.72.381.5Biocomposite PLA00.1430.00.00.0100.0

[0117] In Table 4, because the Biocomposite PLA was very brittle, it was impossible to measure the tensile strength. On the other hand, the Biocomposite recorded an elongation, which is the strain at the point of fracture by tensile force, of 2.3 %. As the Biocomposite PLA recorded an elongation of 0.0, it did not exhibit any tensile stress at all. The tensile strength of the Biocomposite was recorded as 34.7 MPa, and thus it was not significantly different from a general PLA composite.<Preparation Example 3: Preparation of Stone Paper>

[0118] Step 1: To prepare a sheet for making stone paper, after performing beating on bleached softwood pulp so that the freeness became 300 ml CSF (Canadian Standard Freeness), it was mixed with the filler for papermaking prepared in Example 1 at a weight ratio of 10:90 (beaten bleached softwood pulp:filler of Example 1), and to this stock, 8 wt% of epoxy resin relative to the solids content was added to prepare a paper specimen having a basis weight of 80 g / m 2< according to a paper testing method (ISO 5269 / 1).

[0119] Step 2: After melting HDPE having a density of 0.935 g / cm 3< at 200 to 220 °C, curtain coating was performed in an amount of 20 g / m 2< on the paper prepared in step 1. At this time, with the temperature of the paper specimen raised to 100 °C, a vacuum plate of 0.6 atm was applied to the side opposite to the surface where the coating was performed to adjust for effective internal penetration of the HDPE.

[0120] Step 3: The 'stone paper' was completed after smoothing the surface of the paper specimen, into which the HDPE had sufficiently penetrated, using a roller.

[0121] The weight and density of the prepared stone paper were measured at room temperature, the HDPE content was calculated, and the content of calcium carbonate was measured by measuring the weight after treating at 525 °C for 1 hour. In addition, the tensile strength was measured and is shown in Table 5. [Table 5]- Comparison of Physical Properties of Stone PaperType of PaperType of FillerAsh Content (wt%)Basis Weight (g / m 2< )Density (cc / g)Tensile Strength (kN / m)HDPE Content (wt%)Stone PaperExample 173.2101.30.8852.4618.5Comparative Example 2GCC33.260.20.5951.080.0

[0122] Although the examples of the present invention have been described above, the technical idea of the present invention is not limited to the examples presented in the present specification, and a person skilled in the art who understands the technical idea of the present invention will be able to easily propose other examples within the scope of the same technical idea by way of addition, change, deletion, addition, etc., of constituent elements, and these will also fall within the scope of the technical idea of the present invention.

Claims

1. A method for preparing a filler for papermaking, comprising the steps of: (1) preparing a mixed aqueous solution comprising an inorganic compound having an average size of 0.1 to 10 µm and fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1:5 to 100, the mixed aqueous solution having a solids content of 1 to 60 wt%; (2) adding an ionic polymer to the mixed aqueous solution and stirring to form preflocs; and (3) preparing the filler for papermaking by, with respect to 100 parts by weight of the inorganic compound contained in the mixed aqueous solution in which the preflocs are formed, adding 10 to 1000 parts by weight of a calcium compound, and then injecting carbon dioxide at 10 to 80 °C until a pH is maintained at 7.0 ± 1.0.

2. The method of claim 1, wherein the step (1) comprises: (1-1) preparing a mixed solution having a solids content of 1 to 60 wt% by mixing organic fibers and an inorganic compound in a weight ratio of 1:5 to 100, and then adding water; and (1-2) preparing the mixed aqueous solution, which comprises the inorganic compound having an average size of 0.1 to 10 µm and the fiber fibrils having an average width of 5 nm to 10 µm in a weight ratio of 1:5 to 100 and has a solids content of 1 to 60 wt%, by grinding the mixed solution.

3. The method of claim 1, wherein the inorganic compound is one or more selected from calcium carbonate (CaCO3), calcium oxide (CaO), calcium hydroxide (Ca(OH)2), magnesium carbonate (MgCO3), gypsum, kaolin, calcined clay, talc, perlite, diatomaceous earth, zinc carbonate, lithium carbonate, magnesium hydroxide, and aluminum trihydrate.

4. The method of claim 3, wherein the calcium carbonate is one or more selected from ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC).

5. The method of claim 1, wherein the fiber fibril comprises one or more selected from cellulose and chitin.

6. The method of claim 1, wherein the ionic polymer is one or more selected from an anionic polymer and a cationic polymer.

7. The method of claim 6, wherein the anionic polymer is one or more selected from a polysaccharide, a protein, polyvinyl alcohol, polyvinyl acetate, a cellulose derivative, epoxy acrylate, polyester, polyurethane, polyester acrylate, polyether acrylate, a polyolefin dispersion, polyamide, a vinyl copolymer, and polyacrylate.

8. The method of claim 6, wherein the cationic polymer is one or more selected from a polyamidoamine-epihalohydrin polymer, a polyalkyldiallylamine-epihalohydrin polymer, polyethyleneimine, polyacrylamide, polyamine, polyvinylamine, and a cationic starch.

9. The method of claim 1, wherein in the step (2), an amount of the ionic polymer added is 0.01 to 10 parts by weight of one or more ionic polymers with respect to 100 parts by weight of the mixed aqueous solution.

10. The method of claim 1, wherein in the step (3), the calcium compound is one or more selected from calcium oxide, calcium hydroxide, calcium sulfate, and calcium phosphate.

11. A filler for papermaking having a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region, and metal carbonate is disposed on the fiber fibrils, and comprising 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

12. A method for manufacturing paper, comprising the steps of: (1) mixing 1 to 60 wt% of the filler for papermaking according to claim 11; and 40 to 99 wt% of beaten natural pulp or recycled pulp; and (2) introducing the mixture of step (1) into a paper machine to manufacture paper.

13. A method for manufacturing ultra-high-filler-content paper in which an inorganic material is 50 wt% or more of a total weight thereof, the method comprising the steps of: (1) mixing 50 to 99 wt% of the filler for papermaking according to claim 11, and 1 to 50 wt% of beaten natural pulp or recycled pulp, and adding 1 to 30% of an ionic polymer for strength enhancement; and (2) introducing the mixture of step (1) into a paper machine to manufacture the ultra-high-filler-content paper.

14. A method for manufacturing a composite, comprising the steps of: (1) mixing 50 to 99 wt% of the filler for papermaking according to claim 11, and 1 to 40 wt% of beaten natural pulp or recycled pulp; and (2) introducing the mixture of step (1) into a paper machine to manufacture a paper-form sheet; and (3) after step (2), manufacturing the composite by coating or impregnating the manufactured sheet with 50 to 5000 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

15. A method for manufacturing stone paper, comprising the steps of: (1) mixing 50 to 99 wt% of the filler for papermaking according to claim 11 and 1 to 50 wt% of beaten natural pulp or recycled pulp; (2) introducing the mixture of step (1) into a paper machine to manufacture a paper-form sheet; and (3) after step (2), manufacturing the stone paper by coating or impregnating the manufactured sheet with 1 to 50 parts by weight of a synthetic polymer or a biodegradable polymer with respect to 100 parts by weight of the manufactured sheet.

16. A paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

17. Ultra-high-filler-content paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate, wherein an inorganic material is 50 wt% or more of a total weight of the paper.

18. A composite formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

19. A stone paper formed comprising a filler, wherein the filler has a structure in which a plurality of fiber fibrils having an average width of 5 nm to 10 µm are present in a central region and a metal carbonate is disposed on the fiber fibrils, wherein the filler comprises 1 to 20 vol% of the fiber fibrils and 80 to 99 vol% of the metal carbonate.

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