Method for improving the effectiveness of paper strength agents in the papermaking process

Abstract

To provide a manufacturing method of a paper-strengthening agent used in a paper making step, a composition for effect improvement for a paper-strengthening agent, and an effect improvement method of a paper-strengthening agent.SOLUTION: A manufacturing method of a composition for effect improvement for a paper-strengthening agent is characterized by blending a first composition including an ammonium salt and an alkali agent with a halogen-based oxidant, or blending a second composition including a halogen-based oxidant and an alkali agent with an ammonium salt.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for improving the effect of a paper strength agent in a papermaking process. [Background technology]

[0002] 2. Description of the Related Art Paper mills have traditionally used paper strength agents to impart strength to paper. In recent years, paper mills have been using a weaker raw pulp containing short fibers derived from waste paper due to an increase in the proportion of waste paper used. In addition, the use of waste paper causes metal ions contained in the papermaking white water to increase the electrical conductivity in the papermaking system, making it difficult to exert the effect of the paper strength enhancer added to the raw pulp. In such an environment, it is necessary to improve the effect of the paper strength enhancer, but increasing the amount of paper strength enhancer added leads to deterioration of water quality and is not environmentally preferable.

[0003] In addition, virgin pulp such as softwood pulp and hardwood pulp is mainly used as a raw material for tissue paper, western paper, wrapping paper, etc., but in order to maintain the strength of the final sheet, measures to increase the strength of the paper are necessary. Therefore, even when waste paper is not used as a raw material, paper strength enhancers are used, and from an environmental perspective, there is a need to improve the effect of paper strength enhancers without increasing the amount added.

[0004] As a method for reducing the amount of paper strength agent added, for example, Patent Document 1 discloses a method in which an aqueous solution of a hypochlorite salt such as an aqueous solution of sodium hypochlorite and an aqueous solution of a water-soluble inorganic ammonium salt such as an aqueous solution of ammonium sulfate or an aqueous ammonia solution are added to the pulping process water in the manufacture of paperboard using waste paper as the main raw material, thereby effectively reducing the amount of paper strength agent added in the preparation process.

[0005] Patent Document 2 also discloses a method for producing paper that inhibits starch decomposition during the paper production process and does not cause strength deterioration of paper products. Specifically, it discloses that the method for producing paper containing recycled paper includes (1) a step of continuously or intermittently measuring water quality, and (2) a step of inactivating microorganisms having starch decomposition ability based on the water quality measurement results obtained in the step (1). Furthermore, various antibacterial agents are disclosed as agents that can inactivate microorganisms. Patent Document 3 also discloses that microbial contamination progresses using recycled paper, broken pulp, internally added starch, etc. as nutrient sources, and starch decomposition leads to strength deterioration of paper products, so that damage caused by microbial contamination is controlled by adding a bactericide with an oxidizing effect to the raw material.

[0006] Incidentally, as a method for sterilizing raw materials in the papermaking process, for example, Patent Document 4 discloses that a mixed aqueous solution of components (a) and (b) is prepared in a dilution water line having active ingredient addition points in the order of (a) an aqueous sodium hypochlorite solution addition point and (b) an aqueous ammonium sulfate solution addition point, by adding components (a) and (b) to dilution water in the dilution water line so as to flow into a white water line in the papermaking process, and that the pH of the mixed aqueous solution is 8 or higher. However, this document does not disclose a method for improving the effect of a paper strength agent.

[0007] Patent Document 5 discloses a method for improving the effectiveness of a paper strength agent, which includes a step of adding an oxidizing agent (an oxidizing agent containing a halogen and / or hydrogen peroxide) to papermaking process water and a step of adding the paper strength agent, and which improves the effectiveness of the paper strength agent by bringing the oxidizing agent into contact with the paper strength agent at a specific concentration. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5621082 [Patent Document 2] JP 2010-100945 A [Patent Document 3] JP 2011-226043 A [Patent Document 4] Patent No. 4914146 [Patent Document 5] Patent No. 6664627 Summary of the Invention [Problem to be solved by the invention]

[0009] The above-mentioned Patent Document 1 discloses the addition of a chemical to the pulping process water in the pulping process in order to reduce the amount of paper strength agent added in the preparation process. The above-mentioned Patent Documents 2 and 3 disclose that the addition of an antibacterial agent such as an oxidizing agent to inhibit starch decomposition by microorganisms in the paper manufacturing process can prevent paper strength loss, which is a type of microbial damage. In both of these cases, the chemical is added to the papermaking process water before the addition of the paper strength agent, and does not improve the effect of the paper strength agent itself. Furthermore, the above-mentioned Patent Document 4, which discloses a method for sterilizing raw materials in the papermaking process, does not disclose a method for improving the effect of the paper strength agent itself.

[0010] Furthermore, Patent Document 5 discloses an invention relating to a method for improving the effect of a paper strength agent, but there is room for further study on a method for improving the effect of the paper strength agent itself and on such a composition.

[0011] An object of the present invention is to provide a method for producing a composition for improving the effect of a paper strength agent used in the papermaking process, a composition for improving the effect of a paper strength agent, and a method for improving the effect of a paper strength agent. [Means for solving the problem]

[0012] Means for Solving the Problems The inventors of the present invention conducted intensive research to solve the above problems and discovered that the effect of a paper strength agent added in the papermaking process can be greatly improved by contacting the agent with monochloramine and / or monobromamine produced by a specific production method, thereby completing the present invention.

[0013] The present invention relates to a method for producing a composition for improving the effectiveness of a paper strength agent, which is characterized by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or by mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt. The ammonium salt is preferably at least one selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium bromide, and ammonium sulfamate. The halogen-based oxidizing agent is preferably at least one selected from the group consisting of hypochlorite, chlorite, chlorate, perchlorate, and chlorine dioxide. The molar ratio of the halogen-based oxidizing agent to the ammonium salt is preferably 1:1 to 1:2, calculated as the molar ratio of the residual chlorine amount to nitrogen. The first composition preferably has a pH of 4.5 to 8.5.

[0014] The present invention also relates to a composition for improving the effect of a paper strength agent, which is produced by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or by mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt. The molar ratio of the halogen-based oxidizing agent to the ammonium salt (halogen-based oxidizing agent:ammonium salt) is preferably 1:1 to 1:2, calculated as the molar ratio of the residual chlorine amount to nitrogen. The first composition preferably has a pH of 4.5 to 8.5.

[0015] The present invention also relates to a method for improving the effect of a paper strength agent in the papermaking process, the method comprising a composition addition step of adding a composition for improving the effect of the paper strength agent of the present invention to papermaking process water, and a paper strength agent addition step of adding the paper strength agent, wherein the composition and the paper strength agent are in contact with each other. The contact concentration of the composition for improving the effect of a paper strength agent of the present invention when it comes into contact with the paper strength agent is preferably 0.1 to 35 mg / L. The residual chlorine concentration in the papermaking process water after the composition addition step is preferably 0.1 to 35 mg / L. Effect of the Invention

[0016] According to the present invention, it is possible to provide a method for producing a composition for improving the effect of a paper strength agent used in the papermaking process, a composition for improving the effect of a paper strength agent, and a method for improving the effect of a paper strength agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described. However, the embodiment described below is merely one example of a typical embodiment of the present invention, and the scope of the present invention is not to be construed narrowly by this.

[0018] In this specification, "X to Y" means "X or more and Y or less."

[0019] As disclosed in the above-mentioned Patent Document 5, the applicant of the present invention discloses an invention of a method for improving the effect of a paper strength agent, which comprises a step of adding an oxidizing agent to papermaking process water and a step of adding a paper strength agent, and the oxidizing agent (an oxidizing agent having a halogen and / or hydrogen peroxide) and the paper strength agent are brought into contact with each other, and the contact concentration of the oxidizing agent when the paper strength agent and the oxidizing agent are brought into contact with each other is 0.1 to 35 mg / L. As a result of intensively studying a method for further improving the effect of a paper strength agent, the inventors have found that the effect of the paper strength agent is greatly improved by contacting the paper strength agent added in the papermaking process with monochloramine and / or monobromamine produced by a specific production method (i.e., the composition for improving the effect of the paper strength agent of the present invention), and have completed a method for producing the composition for improving the effect of the paper strength agent of the present invention.

[0020] Hereinafter, a general method for producing monochloramine and monobromamine will be described, and then a method for producing the composition for improving the effect of a paper strength agent of the present invention will be specifically described.

[0021] Monochloramine and monobromamine, which are commonly used as oxidizing agents, are OCl - (Br - )+NH4 + →It is a mild oxidizing agent generated by a reaction such as NH2Cl(Br)+H2O. For example, monochloramine can be generated by mixing sodium hypochlorite with an ammonium salt, and specific examples of the ammonium salt include ammonium sulfate, ammonium bromide, ammonium chloride, and ammonium sulfamate, and it is known that these can be used alone or in combination of two or more. It is also known that monochloramine or monobrolamine is mixed with an alkaline agent for the purpose of stabilizing monochloramine and monobrolamine produced by a conventional method. It is also known that monochloramine, monobrolamine, and an alkaline agent are added separately to a target to adjust the pH of the target to which monochloramine or monobrolamine is added (Patent Document 4 above).

[0022] The present inventors have found that when monochloramine and / or monobromamine is produced, an alkaline agent is added to an ammonium salt, the pH of the ammonium salt is controlled to the alkaline side, and the monochloramine and / or monobromamine produced by reacting the ammonium salt with a halogen-based oxidizing agent has an excellent effect of improving the effect of a paper strength agent compared to conventional monochloramine and / or monobromamine produced by reacting an ammonium salt that does not contain an alkaline agent with a halogen-based oxidizing agent, and compared to conventional monochloramine and / or monobromamine containing an alkaline agent. Furthermore, the present inventors have found that when producing monochloramine and / or monobromamine, monochloramine and / or monobromamine produced by reacting a halogen-based oxidizing agent containing an alkali agent with an ammonium salt has an excellent effect of improving the effect of a paper strength agent compared to conventional monochloramine and / or monobromamine produced by reacting a halogen-based oxidizing agent containing no alkali agent with an ammonium salt, and conventional monochloramine and / or monobromamine containing an alkali agent. That is, it was found that a composition produced by reacting an ammonium salt containing an alkaline agent and controlling the pH of the ammonium salt to the alkaline side with a halogen-based oxidizing agent, and a composition produced by reacting an ammonium salt containing an alkaline agent with a halogen-based oxidizing agent have an excellent effect of improving the effect of paper strength enhancers compared to conventional monochloramine and / or monobromine, and conventional monochloramine and / or monobromine containing an alkaline agent. Hereinafter, a composition produced by reacting an ammonium salt containing an alkaline agent and controlling the pH of the ammonium salt to the alkaline side with a halogen-based oxidizing agent, and a composition produced by reacting an ammonium salt containing an alkaline agent with a halogen-based oxidizing agent are referred to as a "paper strength agent effect improving composition" or simply as an "effect improving composition".

[0023] The present invention relates to a method for producing a composition for improving the effectiveness of a paper strength agent, which is characterized by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or by mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt.

[0024] The present invention also relates to a composition for improving the effect of a paper strength agent, which is produced by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or by mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt.

[0025] The ammonium salt used in the present invention is not particularly limited as long as it is an inorganic ammonium salt which is a reaction product of an inorganic acid and ammonia, or an organic ammonium salt which is a reaction product of an organic acid and ammonia. The inorganic ammonium salt is preferably at least one selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium bromide, ammonium sulfamate, ammonium carbonate, ammonium bicarbonate, ammonium hydrogen carbonate, ammonium iron (III) sulfate, ammonium persulfate, ammonium tungstate, ammonium metatungstate, ammonium thiocyanate, and ammonium polyphosphate. The organic ammonium salt is preferably at least one selected from the group consisting of ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, ammonium citrate, ammonium malate, ammonium succinate, ammonium fumarate, ammonium lactate, and ammonium tartrate. Moreover, the ammonium salt is more preferably at least one selected from the group consisting of ammonium sulfate, ammonium chloride, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium bromide, and ammonium sulfamate, and further preferably at least one selected from the group consisting of ammonium sulfate, ammonium bromide, and ammonium sulfamate.

[0026] The halogen-based oxidizing agent used in the present invention is preferably at least one selected from the group consisting of hypochlorite, chlorite, chlorate, perchlorate, and chlorine dioxide.

[0027] Examples of the hypochlorite include sodium hypochlorite, calcium hypochlorite, potassium hypochlorite, magnesium hypochlorite, etc. The hypochlorite is preferably at least one selected from the group consisting of sodium hypochlorite, calcium hypochlorite, potassium hypochlorite, and magnesium hypochlorite, and more preferably at least one selected from the group consisting of sodium hypochlorite, calcium hypochlorite, and potassium hypochlorite.

[0028] Examples of the chlorite include sodium chlorite, potassium chlorite, calcium chlorite, magnesium chlorite, etc. The chlorite is preferably at least one selected from the group consisting of sodium chlorite, potassium chlorite, calcium chlorite, and magnesium chlorite.

[0029] The chlorate may be potassium chlorate, sodium chlorate, calcium chlorate, barium chlorate, magnesium chlorate, etc. The chlorate is preferably at least one selected from the group consisting of potassium chlorate, sodium chlorate, calcium chlorate, barium chlorate, and magnesium chlorate.

[0030] Examples of the perchlorate include sodium perchlorate, potassium perchlorate, calcium perchlorate, magnesium perchlorate, etc. The perchlorate is preferably at least one selected from the group consisting of sodium perchlorate, potassium perchlorate, calcium perchlorate, and magnesium perchlorate.

[0031] Since chlorine dioxide is an extremely unstable chemical substance, its storage and transportation are very difficult. Therefore, it is preferable to produce (generate) chlorine dioxide on-site by a known method and adjust the concentration to be added before use. For example, chlorine dioxide can be produced by the following reaction, and a commercially available chlorine dioxide generator (device) can also be used. (1) Reaction of sodium hypochlorite with hydrochloric acid and sodium chlorite NaOCl+2HCl+2NaClO2→ 2ClO2+3NaCl+H2O (2) Reaction of sodium chlorite with hydrochloric acid 5NaClO2+4HCl → 4ClO2+5NaCl+2H2O (3) Reaction with sodium chlorate, hydrogen peroxide, and sulfuric acid 2NaClO3+H2O2+H2SO4→ 2ClO2+Na2SO4+O2+2H2O

[0032] The halogen-based oxidizing agent used in the present invention is more preferably a hypochlorite.

[0033] The alkaline agent used in the present invention is not particularly limited as long as it is an alkali metal salt and an alkaline earth metal salt that show an alkaline pH when dissolved in water. The alkaline agent is preferably at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, trisodium citrate, monosodium phosphate, disodium phosphate, trisodium phosphate, monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, sodium malate, potassium malate, calcium malate, sodium formate, sodium acetate, sodium propionate, sodium butyrate, sodium citrate, sodium succinate, sodium fumarate, sodium lactate, and sodium tartrate. In addition, the alkaline agent used in the present invention is more preferably at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium bicarbonate, potassium carbonate, and trisodium citrate, and even more preferably at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, and trisodium citrate.

[0034] In the production method of the present invention, before mixing the ammonium salt and the halogen-based oxidizing agent, a first composition containing the ammonium salt and the alkaline agent, or a second composition containing the halogen-based oxidizing agent and the alkaline agent is prepared. The preparation method of the first composition and the second composition is not particularly limited, and a general mixing method can be used.

[0035] The first composition in the present invention preferably contains an alkaline agent so that the pH of the first composition is 1.08 times or more the pH of the ammonium salt itself. This is because the composition produced by controlling the pH of the ammonium salt to the alkaline side to the above level and reacting it with a halogen-based oxidizing agent has a sufficient effect of improving the effect of the paper strength agent.

[0036] The second composition in the present invention preferably contains an alkaline agent so that the pH of the second composition is 1.05 times or more, and more preferably 1.2 times or more, of the halogen-based oxidizing agent itself. This is because the composition produced by reacting the halogen-based oxidizing agent, the pH of which is controlled to the above-mentioned alkaline side, with an ammonium salt has a sufficient effect of improving the effect of the paper strength agent.

[0037] In the present invention, the first composition preferably has a pH of 4.5 to 8.5. Specifically, when the ammonium salt is ammonium sulfate, the pH of the first composition is preferably 4.5 to 8.5, when the ammonium salt is ammonium bromide, the pH of the first composition is preferably 7.0 to 8.5, and when the ammonium salt is ammonium sulfamate, the pH of the first composition is preferably 5.5 to 8.5. In the present invention, the pH can be measured using a commonly used measuring device, for example, a pH meter manufactured by Horiba, Ltd.

[0038] In the present invention, the second composition preferably has a pH of 10.5 to 12.5.

[0039] In the present invention, the molar ratio of the halogen-based oxidizing agent to the ammonium salt (halogen-based oxidizing agent:ammonium salt), expressed as the molar ratio of the residual chlorine amount to nitrogen, is preferably 1:1 to 1:2, more preferably 1:1.1 to 1:2, even more preferably 1:1.2 to 1:2, and particularly preferably 1:1.2 to 1:1.6.

[0040] In the present invention, the weight ratio of the first composition to the halogen-based oxidizing agent and the weight ratio of the second composition to the ammonium salt are preferably determined so that the molar ratio of the halogen-based oxidizing agent to the ammonium salt (halogen-based oxidizing agent:ammonium salt) falls within the above range.

[0041] The paper strength enhancer in the present invention may be any of those commonly used in the papermaking process without any particular limitation, and may be any of cationic, anionic, amphoteric, and nonionic. For example, cationic group-introduced polyacrylamide, polyamidoamine-epichlorohydrin, polyamidoamine, glyoxal-modified polyamidoamine-epichlorohydrin, amine polyester polyether, and salts thereof, and other paper strength enhancers having cationic structures; anionic group-introduced polyacrylamide, polyacrylamide-acrylic acid copolymer, polyacrylic acid, polyacrylamide partial hydrate, polyacrylamide-2-acrylamide-2-methylpropanesulfonic acid copolymer, carboxymethylcellulose, and salts thereof, and other paper strength enhancers having anionic structures; polyacrylamide or starch, compounds having both cationic and anionic groups, and salts thereof, and other paper strength enhancers having amphoteric structures; polyacrylamide, starch, polyvinyl alcohol, and salts thereof, and other paper strength enhancers having nonionic structures. As the paper strength agent in the present invention, one of these may be used alone or two or more may be used in combination. In addition, these paper strength agents may be in any form, such as a solution (liquid) or a powder (solid). In particular, from the viewpoint of promoting the paper strength enhancing effect, it is preferable to use a cationic paper strength agent as the paper strength agent.

[0042] As the cationic paper strength enhancer, commercially available paper strength enhancers can be used. Examples of cationic paper strength enhancers include internal strength enhancers and surface strength enhancers, and internal strength enhancers are further classified into dry strength enhancers and wet strength enhancers. Examples of internal strength enhancers include polyacrylamide, polyacrylamide with cationic groups, anionic groups, or both, and polyamidoamine epichlorohydrin. Examples of surface strength enhancers include polyacrylamide and polyvinyl alcohol. Preferred dry strength enhancers are polyacrylamide, polyacrylamide with cationic groups, anionic groups, or both, and polyamidoamine epichlorohydrin.

[0043] Here, in the papermaking process, which is the conventional paper manufacturing process, oxidizing agents such as monochloramine and monobromamine are added for the purpose of sterilization, and paper strength enhancers are added for the purpose of improving paper strength. It is known that by adding a bactericide to the raw material line in the papermaking process, it is possible to prevent the consumption of paper strength agents derived from raw materials such as starch by microorganisms, and to reduce the amount of paper strength enhancers added in the adjustment process, etc. (Patent Documents 1 to 3 above). In addition, various chemicals are added in the papermaking process according to their purpose, for example, pH adjusters (alkali agents), sizing agents, drainage improvers, etc. are also added. These chemicals are added so that the effects of each chemical are exerted, and are added so that the effects of one chemical are not inhibited by other chemicals. As mentioned above, there are cationic and anionic strength agents, but the position of addition of other agents is not changed depending on the type of strength agent, and the strength agent is added so as not to come into contact with the anionic agent. This is because if the cationic strength agent reacts with the anionic agent (bactericide such as an oxidizing agent) and causes aggregation, the strength agent may not be uniformly dispersed and the agent effect may not be fully exerted. Since the non-uniform dispersion of the strength agent in the papermaking process leads to deterioration of the quality of the paper produced, conventionally, the strength agent and the anionic bactericide (oxidizing agent, etc.) were added at a concentration that would cause a reaction so as not to come into contact with each other. On the other hand, the present invention was completed as a result of investigating ways to improve the effect of the paper strength agent itself, and as a result of discovering for the first time that the effect of a paper strength agent can be improved by contacting the agent with an effect-enhancing composition (anionic oxidizing agent) which is monochloramine and / or monobromamine produced by a specific production method.

[0044] The present invention is a method for improving the effect of a paper strength agent in the papermaking process, which includes a composition addition step of adding a composition for improving the effect of the paper strength agent of the present invention to papermaking process water, and a paper strength agent addition step of adding the paper strength agent, wherein the composition and the paper strength agent are in contact with each other.

[0045] In the present invention, the papermaking process includes a preparation process in which a chemical is added to the pulp, a papermaking process, and a finishing process, and may include a pulping process in which pulp is obtained from a paper raw material before the preparation process. The method for improving the effect of a paper strength agent of the present invention can be used in either the papermaking process from the paper raw material to the production of paper, or the papermaking process from the pulp to the production of paper. The paper raw material may be either waste paper or wood.

[0046] For example, when waste paper is used as the raw material for paper, the papermaking process may include a waste paper pulping process as the pulping process. The waste paper pulping process mainly includes a disintegration process, a rough screening / refining process, and a dewatering / washing process. In addition, it may also include a deinking process to remove ink contained in the waste paper and a bleaching process to chemically bleach the pulp. Each process is specifically described as follows: disintegration (pulper) process in which the raw material waste paper is mixed with water and turned into pulp slurry by mechanical force, rough screening (dust removal) process in which foreign matter contained in the waste paper is removed, deinking process in which a deinking agent is added to remove ink components, refinement process in which foreign matter contained in the waste paper is separated from the pulp content by a screen, washing process in which the pulp slurry is washed with water, dewatering process in which pulp is dewatered, and bleaching process in which pulp is bleached by adding a bleaching agent. The water used in each of the above processes and the water discharged are called white water, and the mixture of the raw material waste paper and white water in the pulper process is called pulp slurry.

[0047] When wood is used as the raw material for paper, the papermaking process may include a chemical pulp making process or a mechanical pulp making process as the pulp making process. The chemical pulp making process mainly includes a wood-cutting process, a cooking process, a screening and washing process, and a dehydration process. It may also include a bleaching process in which the pulp is chemically bleached. In the cooking process, chemicals are added to the chips, and the chips are boiled at high temperature and pressure to dissolve the resin (lignin), extract the fiber, and turn the chips into pulp. That is, the pulp raw material is turned into pulp slurry through the cooking process. The mechanical pulp making process mainly includes a wood-cutting process, a dust removal process, and a concentration process. It may also include a bleaching process in which the pulp is chemically bleached. In the above process, the pulp is mechanically fiberized to turn it into pulp slurry.

[0048] In the present invention, the papermaking process water is water containing pulp, which is a raw material for paper. Since each step in the papermaking process proceeds using a large amount of water as a medium, water is reused. In the present invention, the water containing pulp, which is a raw material for paper, is water that moves through the raw material line of each step (hereinafter also referred to as pulp slurry), not water that is discharged from the raw material line of each step. However, even if the water is discharged from the raw material line, water (white water) that is stored in a white water pit or the like and reused in the papermaking process returns to the raw material line, and is therefore also included in the papermaking process water. In other words, among the reused white water, white water that moves through a circulation line from a tank such as a white water pit to the raw material line is also included in the papermaking process water.

[0049] The composition addition process in which the composition for improving the effect of the paper strength agent of the present invention is added to the papermaking process water, and the paper strength agent addition process in which the paper strength agent is added may be carried out simultaneously or separately, regardless of whether the process is before or after the other process, as long as the composition of the present invention comes into contact with the paper strength agent. In more detail, whether the composition of the present invention comes into direct contact with the paper strength agent or comes into contact with the paper strength agent in the water during the papermaking process, it is sufficient that the composition of the present invention is added so as to come into contact with the paper strength agent at a concentration at which they react.

[0050] In the method for improving the effect of a paper strength agent of the present invention, the contact concentration of the composition for improving the effect of a paper strength agent of the present invention when the composition comes into contact with the paper strength agent is preferably 0.1 to 35 mg / L. This is because a more sufficient paper strength enhancing effect can be obtained by contacting the composition of the present invention in the above concentration range with the paper strength agent.

[0051] In this specification, "the contact concentration of the composition when the composition for improving the effect of a paper strength agent contacts with the paper strength agent" means the concentration of the composition in the papermaking process water when the composition of the present invention contacts with the paper strength agent. To be more specific, when there is a composition addition step and a paper strength agent addition step so that the composition of the present invention and the paper strength agent come into direct contact with each other, it indicates the addition concentration of the composition to be added to the papermaking process water. In addition, when there is a paper strength agent addition step after the composition addition step so that the composition of the present invention and the paper strength agent come into contact in the papermaking process water, it indicates the residual chlorine concentration of the composition in the papermaking process water that comes into contact with the paper strength agent. In addition, when there is a composition addition step after the paper strength agent addition step, it indicates the addition concentration of the composition to be added to the papermaking process water to which the paper strength agent has been added. The contact concentration of the composition of the present invention is a value obtained by converting it into a residual chlorine concentration (residual chlorine concentration equivalent value).

[0052] In the present invention, the residual chlorine concentration (equivalent residual chlorine concentration) of the papermaking process water after the composition addition step is preferably 0.1 to 35 mg / L. Moreover, the residual chlorine concentration of the papermaking process water after the composition addition step is more preferably 0.5 to 30 mg / L, further preferably 1 to 30 mg / L, and from the economical point of view, preferably 1 to 25 mg / L or 1 to 20 mg / L.

[0053] In the present invention, the timing of the composition addition step of adding the composition of the present invention to the papermaking process water and the paper strength agent addition step of adding the paper strength agent to the papermaking process water is not particularly limited as long as it is the timing at which the composition of the present invention and the paper strength agent come into contact with each other at concentrations that allow them to react, as described above, and can be set, for example, depending on the conditions of the papermaking process water. For example, under harsh conditions where the ORP of the papermaking process water is -400 mV or less, it is preferable that the composition addition step and the paper strength agent addition step are performed simultaneously, or each step is performed within 1 minute. On the other hand, under an environment where the consumption of the composition of the present invention in the papermaking process water is low (for example, a system where the supply of fresh water is abundant relative to the papermaking process water), the composition addition step and the paper strength agent addition step may be performed within 120 minutes. In the present invention, it is preferable that the composition addition step and the paper strength agent addition step are performed simultaneously or each step is performed within 60 minutes, more preferably, the simultaneous or each step is performed within 10 minutes, even more preferably, the simultaneous or each step is performed within 5 minutes, and particularly preferably, the simultaneous or each step is performed within 1 minute. This is because a paper strength agent with a higher concentration can be contacted with the composition of the present invention with a higher concentration.

[0054] In the present invention, the paper strength agent addition step is preferably provided at the same location as the composition addition step and / or upstream of the composition addition step. This is because the composition of the present invention may be consumed by microorganisms in the papermaking process water as soon as it is added to the papermaking process water. In this specification, the "upstream side" means the upstream side with respect to the flow direction of the papermaking process water. Specifically, when the composition step and the paper strength agent addition step are configured in the raw material line for the papermaking process water, the upstream side means the side closer to the raw material (or raw material pulp) such as waste paper or wood. On the other hand, when the oxidizing agent addition step and the paper strength agent addition step are configured in the circulation line for reusing white water, the upstream side means the side closer to a tank such as a white water pit. In addition, in this specification, the same location means the same equipment, the same tank, and the same piping (piping between equipment).

[0055] In the present invention, when the composition addition step and the paper strength agent addition step are performed at the same location in the papermaking process and the paper strength agent addition step is upstream of the composition addition step, it is preferable that the timing at which the chemical addition is started in the above two steps is determined by the flow rate of the papermaking process water. This is because by adding the oxidizing agent at the timing when the paper strength agent added upstream of the papermaking process reaches the oxidizing agent addition position, it is possible to more reliably bring the more concentrated paper strength agent into contact with the more concentrated composition of the present invention.

[0056] The amount of the composition of the present invention added may be set so that the contact concentration of the oxidizing agent when the composition of the present invention and the paper strength agent come into contact with each other is 0.1 to 35 mg / L. For example, when the paper strength agent and the composition of the present invention come into contact with each other in the papermaking process water, the amount of the composition of the present invention added is set so that the paper strength agent comes into contact with the papermaking process water having a residual concentration (converted to residual chlorine concentration) of the composition of the present invention of 0.1 to 35 mg / L. The paper strength enhancing effect can be obtained by contacting the paper strength agent and the composition of the present invention at a concentration at which they react with each other.

[0057] The strength agent is preferably added in an amount of 0.01 to 2.0% by weight, more preferably 0.05 to 1.0% by weight, based on 100% by weight of pulp solids. If the amount of strength agent added is less than 0.01% by weight, the strength enhancing effect may not be sufficient, whereas if it exceeds 2.0% by weight, the strength agent may adhere to the pulp sheet or the paper obtained as the final product, causing defects.

[0058] In the present invention, the term "residual chlorine amount" means a "residual chlorine amount equivalent value" when the halogen-based oxidizing agent is not a chlorine-based oxidizing agent.

[0059] (About fungicides) The above-mentioned composition for improving the effect of a paper strength agent of the present invention can be rephrased as the sterilizing composition of the present invention. That is, the present invention may be a method for producing a sterilizing composition, characterized in that a first composition containing an ammonium salt and an alkaline agent is mixed with a halogen-based oxidizing agent, or a second composition containing a halogen-based oxidizing agent and an alkaline agent is mixed with an ammonium salt. The present invention may also be a sterilization composition produced by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or by mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt. The sterilizing composition of the present invention may be similar to the ammonium salt, alkaline agent, halogen-based oxidizing agent, and paper strength agent, and preferred embodiments thereof, in the composition for improving the effect of a paper strength agent of the present invention described above, and the composition and pH of the first composition and second composition may also be similar. EXAMPLES

[0060] The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to these examples.

[0061] (Examples 1 to 4, Comparative Examples 1 to 3, Reference Example 1) (Examples 5 to 8, Comparative Examples 4 to 7, Reference Example 2) [Preparation of paper using recycled paper pulp] (1) 690g of raw material (pulp slurry) with a pulp concentration of 3% was weighed out into a 1000mL beaker. (The weight of bone-dry pulp was 20.7g.) (2) The pulp slurry in the prepared 1000 mL beaker was stirred (350 rpm) with a stirrer (Three-One Motor: manufactured by Shinto Scientific Co., Ltd.), and one minute after the start of stirring, the paper strength agent was added. After a further 30 seconds, a composition for improving the effect of the paper strength agent shown in Tables 1 and 2 below was prepared as shown in Preparation Example 1 or Preparation Example 2 below, and then added so that the concentration relative to the pulp slurry was 5 ppm in the test according to Table 1 and 10 ppm in the test according to Table 2, and the mixture was stirred for 2 minutes. In the test examples according to Comparative Example 1, Comparative Example 4, Reference Example 1, and Reference Example 2, only the paper strength enhancer was added without adding the effect improving composition. Reference Example 1 contained 1.3 times the amount of the paper strength enhancer added in Comparative Example 1, and Reference Example 2 contained 1.3 times the amount of the paper strength enhancer added in Comparative Example 1 and Comparative Example 4, respectively, and these were used as positive controls for confirming the paper strength improvement rate (%). In addition, in the test example of Comparative Example 2, an alkaline agent (sodium hydroxide) was added to the pulp slurry to adjust the pH of the pulp slurry to 9.2, and then stirring was started. As in the other test examples, the paper strength agent of Comparative Example 2 and the effect-improving composition were added in that order. (3) The residual chlorine concentration and pH of the pulp slurry containing the paper strength agent that had been in contact with the effect-improving composition according to each of the obtained test examples were measured. The residual chlorine concentration and pH of each test example are shown in Tables 3 and 4 below. (Test examples excluding Reference Examples 1 and 2, and Comparative Examples 1 and 4) (4) The pulp slurry from (3) was divided into three equal parts, and hand-made paper was made three times to obtain three rectangular (250 mm x 250 mm) pulp sheets for each test example.

[0062] [Adjustment example 1] The second composition was diluted 60 times with ion-exchanged water and the first composition was mixed so that the molar ratio of the residual chlorine amount to the nitrogen was 1:1.5. Preparation Example 1 was used as the test agent in the test examples according to Examples 1 to 5, 7 and 8 and Comparative Examples 2, 3, 5 and 7.

[0063] [Adjustment example 2] The second composition was diluted 60 times with ion-exchanged water to obtain a halogen-based oxidizing agent, and an aqueous sodium hydroxide solution was added to the second composition to obtain a predetermined pH so that the molar ratio of the residual chlorine and nitrogen was 1:1.3, and then the first composition was mixed. Preparation Example 2 was used as the test agent in the test example according to Example 6.

[0064] The drugs used in each test example are as follows. (Paper strength agent) Internally added dry strength agent (cationic polyacrylamide dry strength agent) (Ammonium salt) Ammonium sulfate: Kishida Chemical Co., Ltd. Ammonium bromide: Kishida Chemical Co., Ltd. Ammonium sulfamate: Kishida Chemical Co., Ltd. (Alkaline agent) Sodium hydroxide: Sodium hydroxide, Fujifilm Wako Pure Chemical Co., Ltd. Hydroxide K: Potassium hydroxide, Fujifilm Wako Pure Chemical Co., Ltd. Trisodium citrate: Trisodium citrate, Fujifilm Wako Pure Chemical Co., Ltd. (Halogen-based oxidizing agents) Sodium hypochlorite: Sodium hypochlorite, a reagent manufactured by Kishida Chemical Co., Ltd.

[0065] In addition, the residual chlorine concentration, pH, and burst strength of each test example were measured using the following instruments. (Measurement of residual chlorine concentration) Residual chlorine measuring device: Kasahara Kogyo Co., Ltd. (pH Measurement) pH meter: Horiba Ltd. (Measurement of specific burst strength) Burst ratio tester: Made by Japan TMC Co., Ltd.

[0066] (Paper strength improvement rate) (1) The paper weight of the pulp sheet for each test example was measured, and the basis weight was calculated. (2) The pulp sheet of (1) was measured in accordance with the method described in JIS P 8112 "Test method for bursting strength of paper and paperboard using a Mullen low pressure bursting tester" specified in JIS P 8223 "Test handsheets - Test methods for physical properties". (3) The burst strength index was calculated from the basis weight obtained in (1) above and the burst strength obtained in (2) above. (4) The paper strength improvement rate was calculated based on the following formula and is shown in Tables 3 and 4 below. [Formula] (Paper strength improvement rate) = (Resistant burst strength of each test example) / (Resistant burst strength of test example without oxidizing agent added*) x 100 *In Table 3, the specific burst strength of Comparative Example 1 was used, and in Table 4, the specific burst strength of Comparative Example 4 was used (the specific burst strength of the test example without the addition of an oxidizing agent).

[0067] [Table 1]

[0068] [Table 2]

[0069] [Table 3]

[0070] [Table 4]

[0071] As can be seen from the results in Table 3 above, although the same amount of paper strength agent was used in Examples 1 to 4 as in Comparative Example 1, a composition for improving the effect of the paper strength agent, which was manufactured by a specific manufacturing method, was added, and the paper strength improvement rate was greatly improved, similar to Reference Example 1, in which 1.3 times the amount of paper strength agent was added compared to Comparative Example 1. On the other hand, in Comparative Example 2 (in which conventional monochloramine produced by mixing ammonium salt and a halogen-based oxidizing agent was added to a pH-adjusted pulp slurry), the paper strength improvement rate was significantly lower than that of Comparative Example 1, even though the same amount of paper strength enhancer was used as in Comparative Example 1. In addition, in Comparative Example 3 (in which conventional monochloramine produced by mixing ammonium salt and a halogen-based oxidizing agent was added to the pulp slurry), the paper strength improvement rate was improved compared to Comparative Example 1, but the effect was not significant. Therefore, it has been confirmed that a composition for improving the effect of a paper strength agent obtained by mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent has an excellent effect of improving the effect of the paper strength agent. From the results in Table 4 above, although the same amount of paper strength agent as in Comparative Example 4 was used in Examples 5, 7 and 8, a composition for improving the effect of the paper strength agent manufactured by a specific manufacturing method was added, and the paper strength improvement rate was greatly improved, similar to Reference Example 2 in which 1.3 times the amount of paper strength agent was added compared to Comparative Example 4. In addition, it was confirmed that Example 6 (a composition for improving the effect manufactured by mixing a second composition containing a halogen-based oxidizing agent and an alkali agent with an ammonium salt) has an excellent effect of improving the effect of the paper strength agent, similar to Example 5.

Claims

1. Mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt; A method for producing a composition for improving the effect of a paper strength agent, comprising:

2. 2. The method according to claim 1, wherein the ammonium salt is at least one selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium bromide, and ammonium sulfamate.

3. 3. The method according to claim 1, wherein the halogen-based oxidizing agent is at least one selected from the group consisting of hypochlorite, chlorite, chlorate, perchlorate, and chlorine dioxide.

4. 4. The method according to claim 1, wherein the molar ratio of the halogen-based oxidizing agent to the ammonium salt (halogen-based oxidizing agent:ammonium salt) is 1:1 to 1:2 in terms of the molar ratio of the residual chlorine amount to nitrogen.

5. 5. The method according to claim 1, wherein the pH of the first composition is 4.5 to 8.

5.

6. Mixing a first composition containing an ammonium salt and an alkaline agent with a halogen-based oxidizing agent, or mixing a second composition containing a halogen-based oxidizing agent and an alkaline agent with an ammonium salt; A composition for improving the effectiveness of a paper strength agent produced by:

7. 7. The composition according to claim 6, wherein the molar ratio of the halogen-based oxidizing agent to the ammonium salt (halogen-based oxidizing agent:ammonium salt) is 1:1 to 1:2 in terms of the molar ratio of residual chlorine to nitrogen.

8. A method for improving the effect of a paper strength agent in a papermaking process, comprising: The method includes a composition adding step of adding the composition for improving the effect of a paper strength agent according to claim 6 or 7 to papermaking process water, and a paper strength agent adding step of adding the paper strength agent, The composition and the paper strength agent are in contact with each other. A method for improving the effect of a paper strength agent, comprising:

9. The method for improving the effect of a paper strength agent according to claim 8, wherein the contact concentration of the composition for improving the effect of a paper strength agent when the composition contacts with the paper strength agent is 0.1 to 35 mg / L.

10. The method for improving the effect of a paper strength agent according to claim 8 or 9, wherein the residual chlorine concentration in papermaking process water after the composition addition step is 0.1 to 35 mg / L.

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