Water-soluble polymer composition

Abstract

The present invention provides a water-soluble polymer composition which is suppressed in decrease of the viscosity over time if formed into an aqueous solution that contains iron ions.　A water-soluble polymer composition which contains a water-soluble polymer, a phenolic antioxidant and an inorganic salt other than a transition metal salt, wherein the content of the inorganic salt is from 0.001 part by mass to 10 parts by mass relative to 100 parts by mass of the water-soluble polymer.

Description

[Technical Field]

[0001] The present invention relates to a water-soluble polymer composition, an aqueous water-soluble polymer solution, an industrial chemical, a method for producing an aqueous water-soluble polymer solution, a kit, and a method for producing paper. [Background technology]

[0002] Water-soluble polymers such as polyalkylene oxides are widely used as industrial chemicals (e.g., thickeners for papermaking, flocculants, dispersants, sedimentation promoters, etc.) in various industrial applications such as papermaking, mining, cement, and dyeing (see Patent Document 1). In these fields, water-soluble polymers are often used as aqueous solutions with a concentration of about 1 ppm to 15%. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 104496 Summary of the Invention [Problem to be solved by the invention]

[0004] In the industrial fields described above, the water used to prepare the aqueous solution of the water-soluble polymer may contain iron ions, for example, because industrial water is used or iron rust is formed on pipes.

[0005] When iron ions are contained in the aqueous solution of a water-soluble polymer, there is a problem that the viscosity decreases over time.

[0006] For example, in the papermaking process, paper is made by dispersing and diluting the stock in water, then placing it on a wire (net) and draining the water (wire part). A papermaking thickener such as a water-soluble polymer is blended into the water to increase the viscosity of the water that disperses the stock (pulp fibers), thereby achieving uniform dispersion of the stock and preventing sedimentation. It takes a certain amount of time for the papermaking thickener to be dissolved or diluted in water, blended into an aqueous stock dispersion, and then used to make paper. If the viscosity of the aqueous stock dispersion decreases over time during this time, problems arise in that the papermaking thickener's effects of uniformly dispersing the stock and preventing sedimentation are not fully realized.

[0007] In particular, when producing extremely thin paper such as tissue paper, or thin paper that requires high uniformity, such as that used in the production of electronic components, a decrease in the viscosity of the aqueous dispersion of paper stock has a significant impact on the uniformity of the paper.

[0008] Under these circumstances, a primary object of the present invention is to provide a water-soluble polymer composition that inhibits a decrease in viscosity over time when the aqueous solution contains iron ions. Another object of the present invention is to provide a water-soluble polymer aqueous solution, an industrial chemical, a method for producing a water-soluble polymer aqueous solution, a kit, and a paper production method that utilize the water-soluble polymer. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that a water-soluble polymer composition containing a water-soluble polymer, a phenolic antioxidant, and an inorganic salt other than a transition metal salt, in which the content of the inorganic salt is set to the range of 0.001 to 10 parts by mass per 100 parts by mass of the water-soluble polymer, when used to prepare an aqueous solution of the water-soluble polymer containing iron ions, suppresses a decrease in viscosity over time of the aqueous solution of the water-soluble polymer. The present invention was completed based on this finding and through further extensive research.

[0010] That is, the present invention provides the following configuration. Item 1. A composition comprising at least a water-soluble polymer, a phenolic antioxidant, and an inorganic salt excluding transition metal salts, The water-soluble polymer composition, wherein the content of the inorganic salt is 0.001 to 10 parts by mass relative to 100 parts by mass of the water-soluble polymer. Item 2. The water-soluble polymer composition according to Item 1, wherein the water-soluble polymer is at least one polymer selected from the group consisting of a (meth)acrylamide homopolymer, a neutralized (meth)acrylamide-(meth)acrylic acid copolymer, polyethylene oxide, polypropylene oxide, and an ethylene oxide-propylene oxide copolymer. Item 3. The water-soluble polymer composition according to Item 1 or 2, wherein the inorganic salt is neutral or alkaline in its aqueous solution state. Item 4. The water-soluble polymer composition according to any one of Items 1 to 3, wherein the content of the phenolic antioxidant is 0.001 to 5 parts by mass per 100 parts by mass of the water-soluble polymer. Item 5. The water-soluble polymer composition according to any one of Items 1 to 4, wherein the ratio of the inorganic salt to 100 parts by mass of the phenolic antioxidant is 20 to 10,000 parts by mass. Item 6. The water-soluble polymer composition according to any one of Items 1 to 5, which is a pressure-sensitive adhesive for papermaking. Item 7. An aqueous water-soluble polymer solution comprising the water-soluble polymer composition according to any one of items 1 to 6, iron ions, and water. Item 8. An industrial chemical comprising the water-soluble polymer composition according to any one of items 1 to 6. Item 9. A method for producing an aqueous water-soluble polymer solution, comprising a step of mixing the water-soluble polymer composition according to any one of items 1 to 6 with an aqueous solution containing iron ions. Item 10. A first agent containing a water-soluble polymer and a phenolic antioxidant; a second agent containing an inorganic salt excluding transition metal salts; Equipped with A kit in which the ratio of the inorganic salt in the second agent is 0.001 to 10 parts by mass per 100 parts by mass of the water-soluble polymer in the first agent. Item 11. A method for producing an aqueous water-soluble polymer solution using the kit according to Item 10, a step of mixing the second agent with an aqueous solution containing iron ions to obtain a mixed solution; mixing the mixed solution with the first agent; A method for producing a water-soluble polymer aqueous solution, comprising: Item 12. A step of mixing the aqueous solution of the water-soluble polymer according to Item 7 with a paper stock to prepare an aqueous dispersion of the paper stock; A step of making paper from the aqueous dispersion of the paper stock; A paper manufacturing method comprising: [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a water-soluble polymer composition that, when formed into an aqueous solution containing iron ions, is inhibited from decreasing in viscosity over time. Furthermore, according to the present invention, it is also possible to provide an aqueous water-soluble polymer solution, an industrial chemical, a method for producing an aqueous water-soluble polymer solution, a kit, and a method for producing paper, all of which utilize the water-soluble polymer composition. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a graph showing the evaluation results of the water-soluble polymer compositions of Example 3 and Comparative Example 1 as a papermaking adhesive (a graph showing the relationship between the viscosity of a 0.2% aqueous solution and the anti-freeze degree). DETAILED DESCRIPTION OF THE INVENTION

[0013] The water-soluble polymer composition of the present invention is characterized by containing at least a water-soluble polymer, a phenolic antioxidant, and an inorganic salt other than a transition metal salt. By virtue of this constitution, the water-soluble polymer composition of the present invention is suitably prevented from decreasing in viscosity over time when it is prepared into an aqueous solution containing iron ions. The water-soluble polymer composition of the present invention, as well as a water-soluble polymer aqueous solution, an industrial chemical, a method for producing a water-soluble polymer aqueous solution, a kit, and a paper production method using the water-soluble polymer composition are described in detail below.

[0014] The water-soluble polymer composition of the present invention contains at least a water-soluble polymer, a phenolic antioxidant, and an inorganic salt excluding transition metal salts, and the content of the inorganic salt is 0.001 to 10 parts by mass per 100 parts by mass of the water-soluble polymer.

[0015] [Water-soluble polymer] The water-soluble polymer contained in the water-soluble polymer composition of the present invention is not particularly limited as long as it is a polymer that is water-soluble.

[0016] Specific examples of water-soluble polymers include water-soluble polyalkylene oxides such as polyethylene oxide, polypropylene oxide, and ethylene oxide-propylene oxide copolymers; neutralized (meth)acrylamide-(meth)acrylic acid copolymers; and (meth)acrylamide homopolymers. The copolymers may be block copolymers or random copolymers. Furthermore, the propylene oxide constituting the polypropylene oxide can usually be 1,2-propylene oxide or 1,3-propylene oxide, or both can be used in combination.

[0017] Water-soluble polyalkylene oxides can be produced by known methods, such as polymerizing alkylene oxide in the presence of an alkali or metal catalyst. Examples of commercially available water-soluble polyalkylene oxides include the "PEO" (registered trademark) series from Sumitomo Seika Chemicals Co., Ltd., the "POLYOX" series from Dow Chemical Company, Ltd., the "Alkox" series from Meisei Chemical Industry Co., Ltd., and the "ZEOSPAN" series from Zeon Corporation.

[0018] The degree of neutralization of the neutralized (meth)acrylamide-(meth)acrylic acid copolymer is preferably 20 to 100%, and more preferably 40 to 100%.

[0019] From the viewpoint of suitably suppressing a decrease in viscosity over time when the water-soluble polymer composition of the present invention is made into an aqueous solution containing iron ions, the molecular weight of the water-soluble polymer is preferably 100,000 to 22,000,000, more preferably 200,000 to 15,000,000, in terms of viscosity average molecular weight. The viscosity average molecular weight is measured by the following method.

[0020] <Viscosity average molecular weight> The viscosity average molecular weight is calculated from the intrinsic viscosity value measured using an Ostwald viscometer using the Staudinger equation. Specifically, the viscosity average molecular weight [M] of a polyalkylene oxide is calculated from the intrinsic viscosity [η] measured using an Ostwald viscometer using the following Staudinger equation. [η]=6.4×10 -5 ×M 0.82 However, the solvent is pure water and the measurement temperature is set to 35°C.

[0021] The viscosity average molecular weight (Mw) of the (meth)acrylamide homopolymer and the neutralized (meth)acrylamide-(meth)acrylic acid copolymer is a value calculated by dissolving the (meth)acrylamide homopolymer or the neutralized (meth)acrylamide-(meth)acrylic acid copolymer in a 1N aqueous sodium nitrate solution, determining the intrinsic viscosity [η] at 30°C, and using the following conversion formula: Intrinsic viscosity formula: [η]=3.73×10 -4 ×(Mw)×0.66

[0022] From the viewpoint of suitably suppressing a decrease in viscosity over time when the water-soluble polymer composition of the present invention is made into an aqueous solution containing iron ions, the viscosity at 25°C of a 0.5% by mass aqueous solution is preferably 10 to 4,000 mPa s, and the viscosity at 25°C of a 5.0% by mass aqueous solution is preferably 50 to 80,000 mPa s. The viscosity of the aqueous solution is measured as follows.

[0023] <Measurement of aqueous solution viscosity> The viscosity of the resulting aqueous solution is measured by immersing the beaker in a thermostatic bath at 25°C for at least 30 minutes using a B-type rotational viscometer (rotation speed: 12 r / min, 3 minutes, 25°C). The rotor used for the measurement is rotor No. 1 when the viscosity to be measured is less than 500 mPa·s, rotor No. 2 when the viscosity is 500 mPa·s or more but less than 2,500 mPa·s, and rotor No. 3 when the viscosity is 2,500 mPa·s or more but less than 10,000 mPa·s.

[0024] The water-soluble polymer composition of the present invention may contain one type of water-soluble polymer, or two or more types of water-soluble polymers.

[0025] From the viewpoint of suitably suppressing a decrease in viscosity over time when the water-soluble polymer composition of the present invention is made into an aqueous solution containing iron ions, the content (blending ratio) of the water-soluble polymer in the water-soluble polymer composition of the present invention is preferably 70.00% by mass or more (e.g., 70.00 to 99.99% by mass), more preferably 80.00% by mass or more (e.g., 80.00 to 99.99% by mass), and even more preferably 90.00% by mass or more (e.g., 90.00 to 99.99% by mass).

[0026] [Inorganic salts excluding transition metal salts] The inorganic salts other than transition metal salts contained in the water-soluble polymer composition of the present invention are inorganic salts that are not transition metal salts, i.e., do not include iron salts.

[0027] The inorganic salt is preferably neutral or alkaline in its aqueous solution. Specifically, it is preferable that the pH of a 40 mmol% aqueous solution of the inorganic salt is 7 or higher (for example, 7 to 13). The pH is measured by the glass electrode method.

[0028] The inorganic salt is not particularly limited as long as it is not a transition metal salt, but from the viewpoint of suitably suppressing a decrease in viscosity over time when the water-soluble polymer composition of the present invention is made into an aqueous solution containing iron ions, preferred specific examples include carbonates such as potassium carbonate, lithium carbonate, sodium carbonate, magnesium carbonate, and sodium hydrogencarbonate; silicates such as sodium silicate; phosphates such as trisodium phosphate; sulfates such as magnesium sulfate and sodium sulfate; sulfites such as sodium sulfite; thiosulfates such as sodium thiosulfate; chlorides such as calcium chloride and lithium chloride; bromides such as lithium bromide; iodides such as sodium iodide; sulfides such as sodium sulfide; hydrogen sulfides such as sodium hydrogen sulfide; nitrates such as sodium nitrate; and nitrites such as sodium nitrite.

[0029] The inorganic salt contained in the water-soluble polymer composition of the present invention may be one type or two or more types.

[0030] From the viewpoint of suitably suppressing viscosity reduction over time when the water-soluble polymer composition of the present invention is prepared as an aqueous solution containing iron ions, the content (blended amount) of the inorganic salt in the water-soluble polymer composition of the present invention may be 0.001 to 10 parts by mass per 100 parts by mass of the water-soluble polymer. From the viewpoint of more suitably exerting the effects of the present invention, the lower limit is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, and the upper limit is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, per 100 parts by mass of the water-soluble polymer. Preferred ranges for the content include 0.001 to 5 parts by mass, 0.001 to 2 parts by mass, 0.01 to 10 parts by mass, 0.01 to 5 parts by mass, 0.01 to 2 parts by mass, 0.05 to 10 parts by mass, 0.05 to 5 parts by mass, and 0.05 to 2 parts by mass.

[0031] [Phenol-based antioxidant] The phenolic antioxidant contained in the water-soluble polymer composition of the present invention may be any known phenolic antioxidant. Examples of the phenolic antioxidant include dibutylhydroxytoluene (BHT), dibutylhydroxyanisole (BHA), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenylacrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenylacrylate, 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4, Examples of suitable phenolic compounds include 4'-thiobis(3-methyl-6-tert-butylphenol), tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 3,9-bis[2-(3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionyloxy)-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, various phenolic compounds available commercially under the product name "ADEKA STAB AO" series from ADEKA Corporation, and various compounds available commercially under the product name "IRGANOX" series from BASF.

[0032] The phenolic antioxidant contained in the water-soluble polymer composition of the present invention may be one type or two or more types.

[0033] From the perspective of suitably suppressing the decrease in viscosity over time when the aqueous solution containing the water-soluble polymer composition of the present invention contains iron ions, the content (blending amount) of the phenolic antioxidant in the water-soluble polymer composition of the present invention is, with respect to 100 parts by mass of the water-soluble polymer, preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, still more preferably 0.05 part by mass or more for the lower limit, and preferably 5 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1 part by mass or less for the upper limit. Preferred ranges of the content include 0.001 to 5 parts by mass, 0.001 to 2 parts by mass, 0.001 to 1 part by mass, 0.01 to 5 parts by mass, 0.01 to 2 parts by mass, 0.01 to 1 part by mass, 0.05 to 5 parts by mass, 0.05 to 2 parts by mass, 0.05 to 1 part by mass, and the like.

[0034] Also, from the perspective of suitably suppressing the decrease in viscosity over time when the aqueous solution containing the water-soluble polymer composition of the present invention contains iron ions, in the water-soluble polymer composition of the present invention, the ratio of the inorganic salt to 100 parts by mass of the phenolic antioxidant is preferably 20 to 10000 parts by mass.

[0035] The water-soluble polymer composition of the present invention preferably has a pH of 5 to 13, more preferably 6 to 12, when it is an aqueous solution with a concentration of the water-soluble polymer dissolved in ion-exchanged water of 0.2%. The method for measuring the pH is specifically as follows.

[0036] <Measurement of pH> The pH is measured at room temperature (25 °C) using a commercially available pH meter (for example, the pH meter D-51 manufactured by Horiba, Ltd. calibrated at three points), and the pH value at the time when the indicated value is stable is read.

[0037] The water-soluble polymer composition of the present invention may contain various additives (excluding transition metal salts) in addition to the water-soluble polymer, inorganic salt, and phenolic antioxidant described above. The additives can be appropriately selected depending on the intended use of the water-soluble polymer composition of the present invention, and known additives for each intended use can be used. Examples of additives include antioxidants other than phenolic antioxidants, UV absorbers, fillers, colorants (e.g., pigments and dyes), preservatives, rust inhibitors, surfactants, solvents (e.g., organic solvents), flow improvers (e.g., silica), viscosity modifiers (e.g., hydrophilic silica and water-soluble polymers), and electrolytes. The water-soluble polymer composition of the present invention may contain one or more additives. The content of the additives in the water-soluble polymer composition of the present invention can be appropriately determined depending on the intended use, etc.

[0038] The water-soluble polymer composition of the present invention is not particularly limited in terms of its state, and may be, for example, a solid (e.g., powdery or granular (powdery or granular) or lumpy) at 25°C and 1 atmosphere, or may be a liquid such as a liquid, solution, or dispersion. When the water-soluble polymer composition of the present invention is in a liquid state, it is preferable to use water, and in this case, the water-soluble polymer composition contains a water-soluble polymer, a phenolic antioxidant, an inorganic salt excluding transition metal salts, and water.

[0039] The water-soluble polymer composition of the present invention can be produced by various methods. For example, a solid water-soluble polymer composition can be prepared by dry-blending the required components all at once or in stages. On the other hand, a liquid water-soluble polymer composition can be prepared by, for example, adding a composition prepared by dry-blending the required components to a solvent or dispersion medium and mixing to dissolve or disperse the composition, or by adding the required components to a solvent or dispersion medium all at once or in stages and mixing to dissolve or disperse the composition. The latter method for preparing a liquid water-soluble polymer composition can involve, for example, preparing a solution or dispersion of the water-soluble polymer and then appropriately blending the inorganic salt and phenolic antioxidant into this solution or dispersion. The concentration of the liquid water-soluble polymer composition can be adjusted by controlling the solvent or dispersion medium used during preparation or by appropriately removing the solvent or dispersion medium after preparation.

[0040] A solid water-soluble polymer composition can also be prepared by removing the solvent or dispersion medium from a liquid water-soluble polymer composition and drying the composition.

[0041] The solvent or dispersion medium used to prepare the liquid water-soluble polymer composition is water or various organic media, and is not particularly limited. The water that can be used here is usually purified water such as ion-exchanged water or pure water, but depending on the application of the water-soluble polymer composition, tap water or industrial water may also be used. On the other hand, examples of organic media that can be used here include alcohols such as methanol and ethanol, esters such as ethylene carbonate and propylene carbonate, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran, aromatic hydrocarbons such as benzene, toluene, and xylene, and polar solvents such as dimethylformamide, chloroform, and dichloroethane. One or more organic media may be used.

[0042] The water-soluble polymer composition of the present invention can be used as an industrial chemical (for example, a papermaking thickener, a flocculant, a dispersant, a sedimentation promoter, etc.) in various industrial applications such as papermaking, mining, cement, dyeing, etc. The water-soluble polymer composition of the present invention is particularly suitable as a papermaking thickener.

[0043] When the water-soluble polymer composition of the present invention is used in the production of paper, for example, as a papermaking adhesive, the water-soluble polymer composition of the present invention is made into a powdery or granular form, and when used, is mixed with water to form an aqueous solution of the water-soluble polymer. The concentration is then adjusted so that when the paper stock is subjected to papermaking, the concentration of the water-soluble polymer in the aqueous dispersion containing the paper stock is, for example, about 1 to 5,000 ppm.

[0044] The paper manufacturing method of the present invention is, for example, a method comprising the steps of mixing a water-soluble polymer aqueous solution (containing iron ions) prepared using the water-soluble polymer composition of the present invention as described above with paper stock to prepare an aqueous dispersion of the stock, and making paper from the obtained aqueous dispersion of the stock. Methods for using papermaking thickeners in papermaking are known, and known papermaking methods (paper manufacturing methods) can be applied even when the water-soluble polymer composition of the present invention is used as a papermaking thickener. Known methods can also be applied when the water-soluble polymer composition of the present invention is used for other industrial purposes.

[0045] As described above, in the industrial fields described above, the water used to prepare an aqueous alkylene oxide solution may contain iron ions, for example, when industrial water is used or when iron rust is formed on pipes. When the water-soluble polymer composition of the present invention is used to prepare an aqueous water-soluble polymer solution containing iron ions, the viscosity of the aqueous water-soluble polymer solution is inhibited from decreasing over time. Therefore, an aqueous solution containing iron ions can be used to prepare the aqueous water-soluble polymer solution.

[0046] The water-soluble polymer composition of the present invention can also be prepared as a two-component kit. Specifically, the kit comprises a first component containing the water-soluble polymer composition of the present invention and a phenolic antioxidant, and a second component containing an inorganic salt excluding transition metal salts, with the inorganic salt content of the second component being 0.001 to 10 parts by mass per 100 parts by mass of the water-soluble polymer in the first component. When producing a water-soluble polymer aqueous solution using this kit, it is preferable to produce the water-soluble polymer aqueous solution by a method comprising the steps of: mixing the second component with an aqueous solution containing iron ions to obtain a mixed solution; and mixing the resulting mixed solution with the first component. By premixing the inorganic salt with the aqueous solution containing iron ions before mixing the water-soluble polymer with the aqueous solution containing iron ions, a decrease in viscosity of the water-soluble polymer aqueous solution over time can be effectively suppressed. [Example]

[0047] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0048] Example 1 A water-soluble polymer composition (1) was produced by dry blending 1.993 parts by mass of polyethylene oxide having a viscosity average molecular weight of 8,000,000, 0.0020 parts by mass of dibutylhydroxytoluene (BHT), and 0.0050 parts by mass of potassium carbonate.

[0049] Next, 997.9977 parts by mass of ion-exchanged water and 0.0023 parts by mass of iron(II) chloride were placed in a 1000 mL plastic beaker, and while stirring using a flat plate (width 80 mm, length 25 mm) at a tip peripheral speed of 1.0 m / s, 2 parts by mass of the water-soluble polymer composition (1) obtained above was added, and stirring was continued under the same conditions for 3 hours to produce an aqueous water-soluble polymer solution (1) containing iron(II) ions.

[0050] Example 2 A water-soluble polymer composition (2) was produced by dry-blending 1.993 parts by mass of polyethylene oxide having a viscosity-average molecular weight of 8,000,000, 0.0020 parts by mass of dibutylhydroxytoluene (BHT), and 0.0050 parts by mass of lithium carbonate. Next, a water-soluble polymer aqueous solution (2) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (2) was used instead of the water-soluble polymer composition (1).

[0051] Example 3 1.993 parts by mass of polyethylene oxide having a viscosity-average molecular weight of 8,000,000, 0.0020 parts by mass of dibutylhydroxytoluene (BHT), and 0.0050 parts by mass of sodium carbonate were dry-blended to produce a water-soluble polymer composition (3). Next, an aqueous water-soluble polymer solution (3) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (3) was used instead of the water-soluble polymer composition (1).

[0052] Example 4 1.993 parts by mass of polyethylene oxide having a viscosity average molecular weight of 8,000,000, 0.0020 parts by mass of dibutylhydroxytoluene (BHT), and 0.0050 parts by mass of sodium silicate were dry-blended to produce a water-soluble polymer composition (4). Next, an aqueous water-soluble polymer solution (4) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (4) was used instead of the water-soluble polymer composition (1).

[0053] Example 5 1.993 parts by mass of polyethylene oxide having a viscosity average molecular weight of 8,000,000, 0.0020 parts by mass of dibutylhydroxytoluene (BHT), and 0.0050 parts by mass of trisodium phosphate were dry-blended to produce a water-soluble polymer composition (5). Next, a water-soluble polymer aqueous solution (5) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (5) was used instead of the water-soluble polymer composition (1).

[0054] Example 6 1.903 parts by mass of polyethylene oxide having a viscosity-average molecular weight of 8,000,000, 0.0019 parts by mass of dibutylhydroxytoluene (BHT), and 0.0952 parts by mass of lithium carbonate were dry-blended to produce a water-soluble polymer composition (6). Next, a water-soluble polymer aqueous solution (6) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (6) was used instead of the water-soluble polymer composition (1).

[0055] Example 7 A water-soluble polymer composition (7) was produced by dry-blending 1.816 parts by mass of polyethylene oxide having a viscosity-average molecular weight of 8,000,000, 0.0018 parts by mass of dibutylhydroxytoluene (BHT), and 0.1818 parts by mass of lithium carbonate. Next, a water-soluble polymer aqueous solution (7) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (7) was used instead of the water-soluble polymer composition (1).

[0056] Example 8 A first part of the water-soluble polymer composition (8) was prepared by dry-blending 1.993 parts by weight of polyethylene oxide having a viscosity-average molecular weight of 8,000,000 and 0.0020 parts by weight of dibutylhydroxytoluene (BHT). Next, 997.9977 parts by weight of ion-exchanged water and 0.0023 parts by weight of iron(II) chloride were placed in a 1000 mL plastic beaker. While stirring with a flat plate (80 mm wide, 25 mm long) at a tip peripheral speed of 1.0 m / s, 0.0050 parts by weight of lithium carbonate was added as the second part. Stirring was continued under the same conditions for 10 minutes to produce an aqueous solution containing iron(II) and inorganic salts. Next, 1.995 parts by weight of the first part was added to the aqueous solution, and stirring was continued under the same conditions for 3 hours to produce an aqueous water-soluble polymer solution (8) containing iron(II) ions.

[0057] Example 9 A water-soluble polymer composition (9) was produced in the same manner as in Example 2, except that a sodium salt of a (meth)acrylamide-(meth)acrylic acid copolymer (PAM, manufactured by Meisei Chemical Industry Co., Ltd., trade name: Pamol H) was used instead of 1.993 parts by mass of polyethylene oxide having a viscosity average molecular weight of 8,000,000.

[0058] (Comparative Example 1) A water-soluble polymer composition (10) was produced in the same manner as in Example 1, except that no inorganic salt was used. Next, an aqueous water-soluble polymer solution (10) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (10) was used instead of the water-soluble polymer composition (1).

[0059] (Comparative Example 2) A water-soluble polymer composition (11) was produced in the same manner as in Example 1, except that 0.0050 parts by mass of dibutylhydroxytoluene was used instead of 0.0050 parts by mass of potassium carbonate. Next, a water-soluble polymer aqueous solution (11) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (11) was used instead of the water-soluble polymer composition (1).

[0060] (Comparative Example 3) A water-soluble polymer composition (12) was produced in the same manner as in Example 1, except that 0.0050 parts by mass of 2-mercaptobenzothiazole was used instead of 0.0050 parts by mass of potassium carbonate. Next, a water-soluble polymer aqueous solution (12) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (12) was used instead of the water-soluble polymer composition (1).

[0061] Comparative Example 4 A water-soluble polymer composition (13) was produced in the same manner as in Example 1, except that 0.0050 parts by mass of zinc stearate was used instead of 0.0050 parts by mass of potassium carbonate. Next, a water-soluble polymer aqueous solution (13) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (13) was used instead of the water-soluble polymer composition (1).

[0062] (Comparative Example 5) A water-soluble polymer composition (14) was produced in the same manner as in Example 1, except that 0.0050 parts by mass of magnesium oxide was used instead of 0.0050 parts by mass of potassium carbonate. Next, a water-soluble polymer aqueous solution (14) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (14) was used instead of the water-soluble polymer composition (1).

[0063] (Comparative Example 6) A water-soluble polymer composition (15) was produced in the same manner as in Example 2, except that dibutylhydroxytoluene (BHT) was not used. Next, a water-soluble polymer aqueous solution (15) containing iron (II) ions was produced in the same manner as in Example 1, except that the water-soluble polymer composition (15) was used instead of the water-soluble polymer composition (1).

[0064] (Comparative Example 7) A 1000 mL plastic beaker was charged with 997.9977 parts by mass of ion-exchanged water and 0.0023 parts by mass of iron(II) chloride, and while stirring using a flat plate (width 80 mm, length 25 mm) at a tip peripheral speed of 1.0 m / s, 2 parts by mass of polyalkylene oxide was added. Stirring was continued under the same conditions for 3 hours to produce an aqueous water-soluble polymer solution (16) containing iron(II) ions.

[0065] [Changes in viscosity over time] The viscosity of each of the aqueous solutions of water-soluble polymers prepared in Examples 1 to 9 and Comparative Examples 1 to 7 immediately after preparation (aqueous solution storage period: 0 days) and after 24 hours (aqueous solution storage period: 1 day) was measured under the following conditions. Viscosity was measured using a B-type rotational viscometer (manufactured by Tokimec Corporation, rotor No. 1, measurement conditions: rotation speed: 30 rpm, 3 minutes). The 24-hour storage was performed by placing the aqueous solution of water-soluble polymers at 25°C in a 500 mL glass container. The sealed glass container was kept in a thermo-hygrostat (model number: PR-2ST manufactured by ESPEC Corporation) at 40°C and 75% RH. For viscosity measurement, the glass container containing the aqueous solution of water-soluble polymers was removed from the thermo-hygrostat and immersed in a thermostatic bath at room temperature (25°C) for approximately 60 minutes, after which the viscosity was measured. Table 1 shows the measured viscosity (mPa·s), viscosity retention (%), and pH. The pH was measured using a three-point calibrated Horiba pH meter D-51, and the pH value was read when the reading stabilized.

[0066] For Examples 1 to 8 and Comparative Examples 1 to 7, in which polyalkylene oxide was used as the water-soluble polymer, the viscosity retention (%) was measured based on the viscosity of an aqueous solution (0) containing only polyethylene oxide and water, without the iron (II) ions, phenolic antioxidant, and inorganic salts, as in the composition of the iron (II) ion-containing water-soluble polymer aqueous solution (1) of Example 1. For Example 9, in which a sodium salt of a (meth)acrylamide-(meth)acrylic acid copolymer was used as the water-soluble polymer, the viscosity was measured based on the viscosity of an aqueous solution (0) containing only polyethylene oxide or a sodium salt of a (meth)acrylamide-(meth)acrylic acid copolymer and water, without the iron (II) ions, phenolic antioxidant, and inorganic salts, as in the composition of the iron (II) ion-containing water-soluble polymer aqueous solution (9) of Example 9. The viscosity retention was calculated using the following formula: The greater the decrease in viscosity retention from immediately after production to one day, the greater the viscosity decrease over time. Viscosity retention rate = ({viscosity of polyethylene oxide aqueous solution at each time point [mPa s] / viscosity of polyethylene oxide aqueous solution (0) on day 0 [mPa s]} × 100)

[0067] [Table 1]

[0068] [Evaluation as a papermaking adhesive] The aqueous water-soluble polymer solutions prepared in Example 3 and Comparative Example 1 were added to 1 L of 0.1% pulp slurry at 1000 ppm (vs. pulp). After stirring at 300 rpm for 35 seconds, the amount of filtered water in 0.5 seconds was measured using a static paper-making dynamic R·D tester (SDR-DT, manufactured by Kobayashi Seisakusho Co., Ltd.). The difference in the amount of filtered water in 0.5 seconds from 1 L of pulp slurry without the water-soluble polymer composition was used to determine the anti-freezeness (an index of effectiveness as a papermaking thickener). The results are shown in the graph in Figure 1. Anti-freezeness indicates the degree of retardation of the filtration rate, which is thought to be due to the filter effect of uniformly dispersed pulp through filtration and the viscosity of the papermaking thickener fixed to the pulp. Therefore, the aqueous water-soluble polymer solution of Example 3 exhibited a high anti-freezeness, demonstrating excellent uniform dispersibility in water when used in papermaking. Anti-freeness = drainage rate [addition of water-soluble polymer composition 0 ppm] (mL) - drainage rate [water-soluble polymer composition: the above addition amount] (mL))

Claims

1. The composition contains at least a water-soluble polymer, a phenolic antioxidant, and an inorganic salt excluding transition metal salts, the content of the inorganic salt is 0.001 to 10 parts by mass relative to 100 parts by mass of the water-soluble polymer, the water-soluble polymer is at least one polymer selected from the group consisting of a homopolymer of (meth)acrylamide, a neutralized product of a (meth)acrylamide-(meth)acrylic acid copolymer, polyethylene oxide, polypropylene oxide, and an ethylene oxide-propylene oxide copolymer; A water-soluble polymer composition (excluding those containing cationic surfactants) wherein the inorganic salt is a carbonate, silicate, or phosphate.

2. The water-soluble polymer composition according to claim 1 , wherein the inorganic salt exhibits neutral or alkaline properties in an aqueous solution thereof.

3. 3. The water-soluble polymer composition according to claim 1, wherein the content of the phenolic antioxidant is 0.001 to 5 parts by mass based on 100 parts by mass of the water-soluble polymer.

4. 4. The water-soluble polymer composition according to claim 1, wherein the ratio of the inorganic salt to 100 parts by mass of the phenol-based antioxidant is 20 to 10,000 parts by mass.

5. The water-soluble polymer composition according to any one of claims 1 to 4, which is a tackifier for papermaking.

6. 6. An aqueous water-soluble polymer solution comprising the water-soluble polymer composition according to claim 1, iron ions, and water.

7. An industrial chemical comprising the water-soluble polymer composition according to any one of claims 1 to 5.

8. A method for producing an aqueous water-soluble polymer solution, comprising the step of mixing the water-soluble polymer composition according to any one of claims 1 to 5 with an aqueous solution containing iron ions.

9. a first agent containing a water-soluble polymer and a phenolic antioxidant; a second agent containing an inorganic salt excluding transition metal salts; Equipped with a ratio of the inorganic salt in the second agent is 0.001 to 10 parts by mass with respect to 100 parts by mass of the water-soluble polymer in the first agent; the water-soluble polymer is at least one polymer selected from the group consisting of a homopolymer of (meth)acrylamide, a neutralized product of a (meth)acrylamide-(meth)acrylic acid copolymer, polyethylene oxide, polypropylene oxide, and an ethylene oxide-propylene oxide copolymer; The inorganic salt is a carbonate, silicate, or phosphate.

10. A method for producing an aqueous water-soluble polymer solution using the kit according to claim 9, comprising: a step of mixing the second agent with an aqueous solution containing iron ions to obtain a mixed solution; mixing the mixed solution with the first agent; A method for producing a water-soluble polymer aqueous solution, comprising:

11. A step of mixing the aqueous solution of the water-soluble polymer according to claim 6 with a paper stock to prepare an aqueous dispersion of the paper stock; A step of making paper from the aqueous dispersion of the paper stock; A paper manufacturing method comprising:

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