To provide a method for removing a silicone compound from paper, a method for producing recycled paper from paper, and a silicone compound removing agent.

Abstract

To provide a method for efficiently removing a silicon compound contained in paper, and a removing agent.SOLUTION: The method for removing the silicon compound from the paper comprises a step of treating a raw material slurry containing the paper having a layer containing the silicon compound and water and having a solid content derived from the paper with a solvent containing a cationic surfactant.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention is a paper silicone Compound removal method, method for producing recycled paper from paper, and silicone Compound remover. [Background technology]

[0002] Currently, recycled pulp made from paper is used as a raw material for papermaking, but from the perspective of effective utilization of resources, there is a growing demand to reuse even more paper. The release paper that remains after using a label or sticker is generally attached to the surface of the paper substrate. silicone Examples include those coated with release agents such as compounds and fluorine compounds. Because the paper base material of the release paper and the release agent are tightly bonded, it is difficult to separate the pulp and the release agent. For this reason, release paper is often disposed of as paper that cannot be recycled. Therefore, in response to the demand for more paper to be reused, silicone Efficient removal of compounds is highly desirable.

[0003] Patent Document 1 describes a method for pulping release paper, which comprises providing a coating layer mainly composed of a pigment and an adhesive on at least one side of a paper substrate and providing a release agent layer on at least one side of the coating layer, and subjecting the paper to a mechanical agitation treatment under conditions of (a) a pulp concentration of 15% or more and (b) a temperature of 30°C or more, followed by a flotation treatment and / or a cleaner treatment. silicone A method has been disclosed in which release paper coated with the compound is recycled into pulp by adding a surfactant consisting of an ethylene oxide-propylene oxide adduct of a fatty acid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 1992-209880 Summary of the Invention [Problem to be solved by the invention]

[0005] If release paper is used as recycled paper, problems arise such as a decrease in the uniformity of the coating when the release agent is coated on the recycled paper again, and air bubbles easily forming when the release agent is coated and dried by heating. silicone from paper containing pulp fibers having a layer containing the compound, silicone Therefore, in order to use the release paper as recycled paper, it is necessary to remove the silicone Removal of the compounds has been a challenge. The present invention is based on the release agent contained in the paper. silicone Efficiently removes compounds from paper silicone Compound removal method and silicone A compound remover is provided. [Means for solving the problem]

[0006] The present invention provides silicone A method for producing a paper-based polymer comprising treating a raw material slurry containing paper having a layer containing a compound and water with a solvent containing a cationic surfactant. silicone It relates to a compound removal method. The present invention also provides silicone From paper with a layer containing a compound silicone Contains a cationic surfactant to remove compounds silicone Concerning compound removers. Furthermore, the present invention provides silicone The present invention relates to a method for producing recycled paper from paper, which includes a step of treating a raw material slurry containing paper having a layer containing a compound and water with a solvent containing a cationic surfactant. [Effects of the Invention]

[0007] According to the present invention, the paper silicone Improves compound removal from paper silicone Compound removal method and silicone Further, the present invention provides a compound remover for removing the cellulose from paper. siliconeA method for producing recycled paper from which compounds have been removed is provided. In the present invention, the term "paper" refers to anything that is recycled as recycled paper. DETAILED DESCRIPTION OF THE INVENTION

[0008] Although the detailed mechanism by which this effect is obtained is unknown, it is thought that part of it is as follows. The silicone compounds that have been separated from the pulp and finely dispersed during the defibration and kneading processes are aggregated to an appropriate size by the cationic surfactant, which strengthens their interaction with air bubbles during the flotation process, thereby increasing removal efficiency. It is believed that this aggregation action of the fine silicone compounds increases the efficiency of desiliconization and reduces the amount of silicone remaining in the finished pulp.

[0009] <Cationic surfactants> The present invention silicone The compound removal method uses a cationic surfactant. The cationic surfactant is preferably an ammonium type cationic surfactant, and is represented by the general formula (1): [ka] (In the formula, R 1 represents an alkyl or alkenyl group having 8 to 18 carbon atoms. 2 ~R 4 each independently represents an alkyl group having 1 to 18 carbon atoms which may be substituted with a hydroxy group, or a benzyl group. Z - indicates the counter anion.) The quaternary ammonium salt cationic surfactant represented by silicone This is particularly preferable from the viewpoint of improving the compound removal rate.

[0010] R 1 The number of carbon atoms in the alkyl or alkenyl group represented by siliconeFrom the viewpoint of improving the compound removal rate, the number is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more, and from the same viewpoint, the number is preferably 18 or less, more preferably 16 or less, and even more preferably 14 or less.

[0011] R 2 ~R 4 The number of carbon atoms of the alkyl group which may be substituted with a hydroxy group, represented by silicone From the viewpoint of improving the compound removal rate, it is preferably 1 or more, more preferably 2 or more, and from the same viewpoint, it is preferably 18 or less, more preferably 16 or less, and even more preferably 14 or less.

[0012] Z - is a counter anion of the ammonium ion in the general formula (1), and is not particularly limited, silicone From the viewpoint of improving the compound removal rate, examples of the anion include one or more anions selected from alkyl sulfate ions having 1 to 3 carbon atoms, (1 / 2) sulfate ions, (1 / 3) phosphate ions, fatty acid ions having 1 to 3 carbon atoms, and halide ions. Among these, from the same viewpoint, one or more anions selected from alkyl sulfate ions having 1 to 3 carbon atoms and halide ions are preferred. Examples of alkyl sulfate ions having 1 to 3 carbon atoms include one or more anions selected from methyl sulfate ions and ethyl sulfate ions. Examples of halide ions include one or more anions selected from fluoride ions, chloride ions, bromide ions, and iodide ions. From the same viewpoint, the anion is preferably one or more anions selected from methyl sulfate ions, ethyl sulfate ions, chloride ions, and bromide ions, more preferably one or more anions selected from methyl sulfate ions, ethyl sulfate ions, and chloride ions, and even more preferably ethyl sulfate ions. The counter anion of the ammonium ion of general formula (1) may be one type alone or two or more types.

[0013] <Paper pulping process> The present invention silicone In the compound removal method, the raw material paper has a base material containing at least a part of the base material. siliconeThe present invention relates to a paper having a layer containing a compound, more specifically, a substrate having a layer containing a compound on at least a portion of the substrate. silicone Examples of the paper include paper containing pulp fibers coated with a compound. In the method of the present invention, the substrate may be a paper substrate, or even a substrate containing pulp fibers. Examples of the paper that can be used as the raw material include release paper. Note that the paper that can be used as the raw material has a base material that is at least partially coated with a compound. silicone Paper that does not fall under the category of paper having a layer containing a compound may also be included. silicone The compound is cured on the substrate. silicone Compounds such as silicone After the compound is applied to the paper substrate, it is cured by heating or UV irradiation. silicone A resin layer is formed. These silicone The compounds include: silicone It contains a base resin and a crosslinking agent, and is cured by a catalyst, photopolymerization initiator, etc. silicone The main agent contains linear dimethylpolysiloxane in the molecule from the viewpoint of peelability. silicone Compounds include: More specifically, polydimethylsiloxane containing silanol groups at its terminals is used. silicone It is a thermosetting resin that uses polymethylhydrogensiloxane as the crosslinking agent and undergoes a condensation reaction when heated in the presence of an organotin catalyst. silicone Compound, polydimethylsiloxane containing vinyl groups silicone It is a thermosetting resin that uses polymethylhydrogensiloxane as a crosslinking agent and reacts and hardens in the presence of a platinum catalyst. silicone compound, silicone A UV-curing type that combines a modified silicone with an alicyclic epoxy group in the base compound with a photopolymerization initiator (photocation catalyst) that has a maximum absorption in the UV range, and generates cations when irradiated with UV light, causing the reaction and hardening. silicone Compounds include: The raw material, paper, is made up of a base material and silicone Between the compound-containing layer and the paper substrate siliconeA filler layer may be provided between the layer formed by curing the compound and the layer formed by curing the compound. Examples of the filler layer include a filler layer containing polyvinyl alcohol, polyethylene, or clay.

[0014] The present invention silicone The paper pulping method to which the compound removal method is applied is a method for pulping paper containing release paper, and further, a method for pulping paper containing release paper at least partially on a substrate. silicone The present invention may also be a method for pulping paper containing pulp fibers to which a compound has been applied. silicone The compound removal method is silicone From the viewpoint of improving the compound removal rate, it is sufficient to include a step in which the paper is brought into contact with a cationic surfactant, but it is preferable to use the following treatment method. silicone The compound removal method preferably includes one or more steps selected from a disintegration step, a concentration step, a chemical addition step, a pre-kneading step, an aging step, a dilution step, a post-kneading step, a flotation step, and a washing step, and more preferably includes a disintegration step and a flotation step.

[0015] <Disintegration process> The defibration process is a process in which paper is mixed with water, and if necessary, an alkaline agent or a deinking agent is further added to obtain a raw material slurry. silicone From the viewpoint of compound removal efficiency, the temperature is preferably 20° C. or higher, more preferably 25° C. or higher, and even more preferably 30° C. or higher, and from the viewpoint of operability, the temperature is preferably 80° C. or lower, more preferably 75° C. or lower, and even more preferably 70° C. or lower. The water that can be used in this step and the steps described below may be any of ion-exchanged water, purified water, tap water, industrial water, etc., but industrial water is preferred from the viewpoint of economy.

[0016] The deinking agent may be one or more selected from alkylene oxide adducts of fats and oils / glycerin, higher fatty acids, alkylene oxide adducts of higher fatty acids, and alkylene oxide adducts of higher alcohols. Non-limiting examples include DI-7020, DI-7250, DI-7300, DI-7460, and DI-767 manufactured by Kao Corporation, DIA-Z-100 and DIA-Z-5000 manufactured by Nissin Chemical Research Institute Co., Ltd., Neoscore FW-780, Neoscore FW-790, Neoscore FW-795, FT-467, FT-470, FT-487, FT-511, FT-513, FT-514, and FT-515 manufactured by Toho Chemical Industry Co., Ltd., Daihope 940 and Daihope 960 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Lipobright DP-810 manufactured by Nicca Corporation.

[0017] From the viewpoint of de-peeling, the addition rate of the de-inking agent to the solid content contained in the raw slurry is calculated using the following formula: [Mass of deinking agent (g)] / [Mass of solids contained in raw slurry (g)] x 100 (mass%) However, the deinking agent is added to the raw slurry so that the content is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and from the viewpoint of operability, preferably 1.0% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.5% by mass or less.

[0018] The solid content concentration of the raw material slurry in the macerating step is calculated by adding a predetermined amount of the raw material slurry to an empty aluminum cup whose dry mass has been measured, drying it in a dryer at 105°C for 2 hours or more, measuring the mass of the aluminum cup after removing the moisture, and using the following formula (1). [{(mass of the dried aluminum cup (g)) - (mass of the empty aluminum cup (g))} / (mass of the added raw material slurry (g))] × 100 (mass%) (1)

[0019] The disintegration step may also serve as the chemical addition step described below, and the deinking agent and alkaline agent may be added in the chemical addition step described below. The alkaline agent is preferably added in the chemical addition step.

[0020] The cationic surfactant may be added during the disintegration step, and the addition rate of the cationic surfactant is calculated according to the following formula: [Amount of cationic surfactant added (g)] / [Mass of solids contained in raw slurry (g)] x 100 (mass%) The addition rate of the cationic surfactant is silicone From the viewpoint of improving the compound removal rate, the concentration is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, and from the same viewpoint, the concentration is preferably 1% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.7% by mass or less.

[0021] <Concentration process> The concentration step is a step of dehydrating and concentrating the raw material slurry treated in the pulverization step. The solid content concentration after the concentration step is calculated by the above formula (1) in the same manner as in the method for measuring the solid content concentration of the raw material slurry in the pre-disintegration step. The solids concentration of the raw slurry in the concentration step is preferably 15% or more, more preferably 20% or more, and even more preferably 25% or more, from the viewpoint of the efficiency of the chemical solution, and from the same viewpoint, is preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less.

[0022] <Chemical solution addition process> The chemical solution addition step is a step of adding one or more selected from an alkaline agent, a bleaching agent, a scale inhibitor, a pitch control agent, a defoaming agent, a foaming agent, and a slime control agent. The alkaline agent may be one or more selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide. From the viewpoint of pulp swelling, the addition rate of the alkali agent to the solid content contained in the raw material slurry is calculated using the following formula: [Weight of alkaline agent (g)] / [Weight of solids contained in raw slurry (g)] x 100 (% by mass) The alkali agent is added to the raw material slurry so that the alkali agent content is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and from the viewpoint of economy, preferably 2.0% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.0% by mass or less.

[0023] The bleaching agent may be one or more selected from hydrogen peroxide, hypochlorites, and hyposulfites. The hypochlorites and hyposulfites may be alkali metal salts, preferably sodium salts. From the viewpoint of bleaching, the addition rate of bleaching agent to the solid content of the raw slurry is calculated using the following formula: [Bleaching agent mass (g)] / [Solids mass in raw slurry (g)] x 100 (mass%) However, the bleaching agent is added to the raw material slurry so that the content is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and from the viewpoint of economy, preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 3% by mass or less.

[0024] The cationic surfactant may be added in the chemical addition step, and the addition rate of the cationic surfactant in this case is calculated by the following formula: [Amount of cationic surfactant added (g)] / [Mass of solids contained in raw slurry (g)] x 100 (mass%) The addition rate of the cationic surfactant is silicone From the viewpoint of improving the compound removal rate, the concentration is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, and from the same viewpoint, the concentration is preferably 1% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.7% by mass or less.

[0025] <Pre-kneading process> The pre-kneading step is a step in which the raw material slurry is kneaded under alkaline conditions at a solids concentration of 15% by mass or more and 45% by mass or less.

[0026] In the first kneading step, the solid content concentration of the raw material slurry to be subjected to the step is: silicone From the viewpoint of separation and pulverization of the compounds, the content is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and from the viewpoint of operability, the content is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. The solid content concentration of the raw material slurry to be subjected to the pre-kneading step is calculated by the above formula (1) in the same manner as the method for measuring the solid content concentration of the raw material slurry in the macerating step.

[0027] The processing temperature of the raw material slurry in the first kneading step is silicone From the viewpoint of compound removal efficiency, the temperature is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 30°C or higher, and from the viewpoint of operability, the temperature is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower.

[0028] <Aging process> The aging step is carried out by applying a fermentation agent to at least a portion of the substrate. silicone This is a step of holding a raw material slurry containing water and paper having a compound-containing layer under alkaline conditions of pH 10 or higher at a temperature of 50°C to 90°C for 30 minutes to 12 hours. In the aging step, the raw slurry can be mixed with one or more alkaline agents selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide to bring the raw slurry into a predetermined alkaline condition.

[0029] The pH of the raw material slurry in the aging process is 10 or higher, preferably 10.5 or higher, more preferably 11 or higher, from the viewpoint of swelling of pulp fibers and penetration of chemicals, and from the viewpoint of economy, it is preferably 13.5 or lower, more preferably 13 or lower, even more preferably 12.5 or lower. The pH of the raw material slurry is the pH at the temperature during the aging process, and if the pH of the raw material slurry at 60°C is within the above range, it can be determined that the pH of the raw material slurry during the process satisfies the above range. The same applies to the pH of the raw material slurry in the other processes below. The pH of the raw material slurry was measured by the following pH measurement method. The pH of the raw material slurries in the other processes was also measured by the same method as the pH measurement method described below. A pH measurement combination electrode (HORIBA glass ground sleeve type) is connected to a pH meter (HORIBA pH / ion meter F-23) and the power is turned on. A saturated potassium chloride aqueous solution (3.33 mol / L) is used as the pH electrode internal solution. Next, 100 mL of pH 6.86 standard solution (neutral phosphate standard solution), pH 9.18 standard solution (borate standard solution), and pH 12.0 standard solution (saturated calcium hydroxide standard solution) are each filled into a beaker and immersed in a thermostatic bath adjusted to the temperature during treatment for 30 minutes. The pH measurement electrode is immersed in the thermostatically adjusted standard solution for 3 minutes, and calibration is performed in the following order: pH 6.86 → pH 9.18 → pH 12.0. The sample to be measured (raw material slurry) is adjusted to the temperature during treatment, and the pH meter electrode is immersed in the sample and measured after 1 minute.

[0030] The treatment temperature of the raw material slurry in the aging process is 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher, from the viewpoint of swelling of the pulp fibers and penetration of the chemicals, and 90°C or lower, preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of economy.

[0031] In the aging process, the time for which the raw material slurry is maintained at a predetermined temperature is 30 minutes or more, preferably 60 minutes or more, more preferably 2 hours or more, from the viewpoint of swelling of the pulp fibers and penetration of the chemicals, and is 12 hours or less, preferably 9 hours or less, more preferably 6 hours or less, from the viewpoint of economy.

[0032] In the aging step, the solids concentration of the raw material slurry is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of the penetration of the chemicals, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of the economy during dehydration. The solid content concentration of the raw material slurry is calculated by the above formula (1) in the same manner as in the method for measuring the solid content concentration of the raw material slurry in the macerating step.

[0033] The aging step can be carried out, for example, by holding the raw material slurry in a tower maintained at a predetermined temperature and keeping the raw material slurry warm. In the aging step, the raw material slurry may or may not be heated as long as the raw material slurry can be maintained at a predetermined temperature. From the viewpoint of maintaining the raw material slurry at a predetermined temperature, it is preferable to heat the raw material slurry in the aging step. In the aging step, the raw material slurry may be stirred.

[0034] <Post-kneading process> The latter-stage kneading step may be a kneading step carried out under the same conditions as the former-stage kneading step, i.e., the latter-stage kneading step is a step in which the raw material slurry treated in the aging step is kneaded under alkaline conditions of pH 10 or higher at a solids concentration of 15% by mass or more and 45% by mass or less. In the latter kneading step, the kneading treatment is carried out under alkaline conditions of pH 10 or higher. Since the raw material slurry after the aging step is alkaline at pH 10 or higher, the raw material slurry after the aging step may be directly subjected to the latter kneading step.

[0035] In the post-kneading treatment, the solid content concentration in the raw material slurry to be treated is silicone From the viewpoint of separation and pulverization of the compounds, the content is 15% by mass or more, preferably 20% by mass or more, more preferably 25% by mass or more, and from the viewpoint of operability, the content is 45% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less. The solid content concentration of the raw material slurry to be treated is calculated by the above formula (1) in the same manner as in the method for measuring the solid content concentration of the raw material slurry in the macerating step.

[0036] The pH of the raw material slurry in the post-kneading process is: silicone From the viewpoint of separation and pulverization of compounds, it is 10 or more, preferably 10.5 or more, more preferably 11 or more, and from the viewpoint of operability, it is preferably 13.5 or less, more preferably 13 or less, even more preferably 12.5 or less.

[0037] The processing temperature of the raw material slurry in the post-kneading step is silicone From the viewpoint of separation and pulverization of compounds, the temperature is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 30°C or higher, and from the viewpoint of operability, the temperature is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower.

[0038] The post-kneading step can be carried out using a known kneading device, such as a kneader or a disperser. The kneading process can be carried out, for example, in an experimental beating machine (PFI Mill, manufactured by Kumagai Riki Kogyo Co., Ltd.) that simulates the kneading process, under conditions of a clearance of 0.1 mm between the inner wall of the kettle and the gear, and a count of 50 to 500, with 10 rotations of the gear being one count. In the latter kneading step, the raw material slurry may or may not be heated as long as the raw material slurry can be maintained at a predetermined temperature.

[0039] In the latter kneading step, the raw material slurry may be optionally mixed with one or more selected from a bleaching agent, a deinking agent, a scale inhibitor, a pitch control agent, a defoaming agent, a foaming agent, and a slime control agent. The preferred embodiments of the bleaching agent and deinking agent are the same as those described in the chemical solution addition step. In addition, the preferred amounts of the bleaching agent and deinking agent added in the latter kneading step are the same as those described in the chemical solution addition step.

[0040] Between the latter kneading step and the flotation step, one or more steps selected from a dilution step in which the raw slurry is mixed with water to dilute the raw slurry, and a foaming agent addition step in which a foaming agent is added to the raw slurry can be optionally performed.

[0041] <Flotation process> The flotation step is a step of subjecting the raw slurry to flotation treatment. There are no limitations on the type of floater used in the flotation step, and examples include a box-type floater, an Ecocell floater, and an MT floater.

[0042] In the flotation step, the solid content concentration of the raw material slurry to be treated is silicone From the viewpoint of compound removal efficiency, the concentration is preferably 0.6 mass% or more, more preferably 0.7 mass% or more, and even more preferably 0.8 mass% or more, and from the viewpoint of operability, the concentration is preferably 1.5 mass% or less, more preferably 1.4 mass% or less, and even more preferably 1.3 mass% or less. The solids concentration of the raw slurry to be subjected to the flotation step is calculated by the above formula (1) in the same manner as the method for measuring the solids concentration of the raw slurry in the above maceration step.

[0043] The pH of the raw slurry in the flotation process is: silicone From the viewpoint of compound removal efficiency, the ratio is preferably 7.5 or more, more preferably 8 or more, and even more preferably 8.5 or more, and from the viewpoint of economy, the ratio is preferably 11 or less, more preferably 10.5 or less, and even more preferably 10 or less.

[0044] The treatment temperature of the raw material slurry in the flotation process is: silicone From the viewpoint of compound removal efficiency, the temperature is preferably 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher, and from the viewpoint of operability, the temperature is preferably 60°C or lower, more preferably 55°C or lower, and even more preferably 50°C or lower.

[0045] In the flotation step, the treatment time of the raw material slurry is adjusted appropriately depending on the number of flotators and the amount of foam, and is not particularly limited. silicone From the viewpoint of compound removal efficiency, the time is preferably 3 minutes or more, more preferably 4 minutes or more, and even more preferably 5 minutes or more, and from the viewpoint of yield, the time is preferably 20 minutes or less, more preferably 15 minutes or less, and even more preferably 10 minutes or less.

[0046] <Cleaning process> In the method of the present invention, one or more steps selected from a washing step and a dust removal step can be optionally carried out.

[0047] The washing step is a step of dehydrating and washing away fine ink particles that could not be removed by, for example, a flotator, and is preferably carried out after the flotation step. In the washing step, the raw slurry, which has a solids concentration of 0.6 to 1.5% by mass after flotation, is preferably diluted with water, and then dehydrated and washed until the solids concentration of the raw slurry reaches approximately 10% by mass. Fresh water or clear white water from a paper machine can be used as the water to dilute the raw slurry. The solids concentration is calculated using the above formula (1).

[0048] In the pulping method, each step may be carried out multiple times, or a group of steps may be repeatedly carried out, if necessary. Furthermore, steps may be omitted if necessary.

[0049] The present invention silicone The compound removal method is carried out by adding the cationic surfactant in one or more of the above steps. The cationic surfactant may be added in any of the above steps, but is preferably added in a step before the flotation step, from the viewpoint that the effect of the cationic surfactant is most pronounced in the flotation step. For example, it is preferable to add the cationic surfactant to the raw material slurry in the disintegration step or chemical addition step, and then subject the slurry to the flotation step.

[0050] From the viewpoint of convenience, it is preferable to add the cationic surfactant dissolved in a solvent. Examples of the solvent that can be used include water and ethanol, but from the viewpoint of economy, water is most preferable.

[0051] The addition rate of the cationic surfactant is calculated by the following formula. [Amount of cationic surfactant added (g)] / [Mass of solids contained in raw slurry (g)] x 100 (mass%) Therefore, the concentration of the cationic surfactant is calculated by the following formula: [Amount of cationic surfactant added (g)] / [Mass of raw slurry (g)]×10 6 (ppm) In addition, the concentration of the cationic surfactant in the raw slurry present during the flotation process [Mass of solids contained in raw slurry in the flotation process (g)] x [Addition rate of cationic surfactant (% by mass)] / [Mass of raw slurry (g)] x 10 6 (ppm) teeth, silicone From the viewpoint of improving the compound removal rate, the concentration is preferably 1 ppm or more, more preferably 3 ppm or more, even more preferably 5 ppm or more, and even more preferably 10 ppm or more, and from the same viewpoint, the concentration is preferably 100 ppm or less, more preferably 80 ppm or less, and even more preferably 70 ppm or less.

[0052] The present invention provides silicone From paper with a layer containing a compound silicone Contains a cationic surfactant to remove compounds silicone A compound remover is provided. silicone The paper to be treated with the compound remover and the treatment process can be the same as those described above. That is, the present invention silicone The compound remover is a remover obtained by dissolving a predetermined amount of the cationic surfactant in the solvent, and is applied to at least a part of the substrate. silicone Paper having a layer containing a compound, more specifically, at least a part of the base material of the paper silicone Paper containing pulp fibers coated with the compound can be used in the treatment process described above. The remover of the present invention may be added in any of the above-mentioned treatment steps, but is preferably added in a step prior to the flotation step. For example, it is preferable to add the remover in the disintegration step or chemical solution addition step, and then carry out the flotation step.

[0053] The present invention also provides silicone The present invention provides a method for producing recycled paper from paper, which includes a step of treating a raw material slurry containing water and paper having a layer containing a compound with a solvent containing a cationic surfactant. silicone The treatment step including a step of treating a raw material slurry containing water and paper provided with a layer containing a compound with a solvent containing a cationic surfactant can be performed in the same manner as described above. That is, the manufacturing method of the present invention is silicone Paper having a layer containing a compound, more specifically, at least a part of the base material of the paper silicone The method of the present invention may be a method for producing recycled paper from paper, in which recycled paper is produced from paper containing pulp fibers coated with a compound.The method of the present invention may also be a method for producing recycled paper from paper, in which recycled paper is produced from paper containing release paper. In the manufacturing method of the present invention, a preferred embodiment of the cationic surfactant and the treatment step is silicone The cationic surfactant may be added in any of the steps described above, but is preferably added in a step prior to the flotation step, for example, in the disintegration step or chemical solution addition step, as is the preferred embodiment described in the compound removal method. The manufacturing method of the present invention also provides recycled pulp that has been pulped through a treatment process, i.e., the paper of the present invention. silicone The method may involve producing recycled paper by discharging the recycled pulp that has been pulped by removing the compounds into a paper machine. An existing paper machine can be used as the paper machine.

[0054] The present invention provides a method for manufacturing a substrate. silicone Paper having a layer containing a compound, more specifically, at least a part of the base material of the paper silicone The present invention provides recycled paper obtained by a manufacturing method including a step of treating paper containing pulp fibers coated with a compound with a solvent containing the cationic surfactant of the present invention. [Example]

[0055] The following compounds were used as cationic surfactants. (C1) Ethylbis(2-hydroxyethyl)laurylammonium ethyl sulfate (Electrostripper KS-48, manufactured by Kao Corporation) (C2) Bis(2-hydroxyethyl)methyloleylammonium chloride salt (Liposocard O / 12, manufactured by Lion Specialty Chemicals Co., Ltd.) (C3)(C8-18 alkyl)bis(2-hydroxyethyl)methylammonium chloride salt (Liposocard C / 12, manufactured by Lion Specialty Chemicals Co., Ltd.) (C4) alkyl (C12-16) benzyl dimethyl ammonium chloride (Sanisol B-50, manufactured by Kao Corporation) (C5) Coconut trimethylammonium chloride (Cotamine 24P, manufactured by Kao Corporation) (C6) Trimethylstearylammonium chloride (Cortamin 86W, manufactured by Kao Corporation) (C7) Cetyltrimethylammonium chloride (Cortamin 60W, manufactured by Kao Corporation) (C8) Di(C12-18 alkyl)dimethylammonium chloride (Chotamin D-2345P, manufactured by Kao Corporation) (C9) Dimethyl distearyl ammonium chloride (Cortamin D-86P, manufactured by Kao Corporation) In addition, a comparative study was also carried out using the following nonionic surfactants. <Nonionic surfactants (numbers in parentheses indicate the average number of moles of oxyethylene groups added)> (N1) Polyoxyethylene (5) lauryl ether (Emulgen 106, manufactured by Kao Corporation)

[0056] The effects of the surfactants were examined using the above surfactants in the following three treatment methods.

[0057] (i) Example 1 and Comparative Example 1 <Disintegration process> In the disintegration process, one side of the glassine paper is coated with silicone The compound-coated direct-type release paper was used as the paper stock, and a sample of 100 g of bone-dry solids was added to a pulper to achieve a solids concentration of 5% by mass, 0.4% by mass (relative to the mass of solids contained in the raw slurry), 0.2% by mass (relative to the mass of solids contained in the raw slurry) of sodium hydroxide, 0.2% by mass (relative to the mass of solids contained in the raw slurry) of a higher alcohol-based deinking agent (Kao Corporation, DI-7250), and 0.2% by mass (relative to the mass of solids contained in the raw slurry) of cationic surfactant C1 and nonionic surfactant N1. Industrial water was then added, and the total mass was adjusted to 2,000 g. The pulper treatment was carried out at 40°C for 10 minutes to obtain a raw slurry containing direct-type release paper and water. The concentrations of sodium hydroxide and deinking agent were determined relative to the bone-dry solids of the direct-type release paper, i.e., relative to the mass of solids contained in the raw slurry. The solids concentration of the raw slurry can be considered to be the solids concentration calculated using the above formula (1). All water used below is industrial water.

[0058] <Dilution process> The raw slurry after the disintegration step was diluted with water to a solids concentration of 1% by mass, and the diluted raw slurry was then subjected to the subsequent flotation treatment.

[0059] <Flotation process> 4,300 g of raw slurry containing 43 g of solids (solid concentration 1% by mass) was transferred to a flotator (manufactured by Kyokuto Shinko Co., Ltd.) and subjected to flotation treatment at 40° C. for 5 minutes. The concentrations of the cationic and nonionic surfactants added in the disintegration step and contained in the raw slurry in the flotation step were 20 ppm relative to the raw slurry.

[0060] <Cleaning process> After the flotation process, 300 g of the raw material slurry was sampled, passed through an 80-mesh wire sieve to dehydrate and filter fine substances, and concentrated and washed to 30 g (solid content concentration: 10% by mass). After completion of the above steps, the following were evaluated: the mass of the scum, the amount of silicon in the dry solids of the recycled pulp, and the yield.

[0061] <Method for Measuring the Mass of Scum> The effluent (scum) from flotation was collected, and the mass of the collected effluent was measured.

[0062] <Method for Measuring the Si Content> The Si content in the recycled pulp obtained after the washing process was measured by high-frequency inductively coupled plasma (ICP) optical emission spectrometry (ICP-AES). Specifically, the recycled pulp after the washing process was dried in an electric dryer at 105 °C for 12 hours. 0.1 g of the dry solids of this recycled pulp was weighed into a platinum crucible, a few drops of sulfuric acid were added and allowed to soak in, then dried to dryness with a heater, and then sufficiently ashed in an electric furnace at 550 °C. Then, 1 g of an alkali flux (sodium carbonate: boric acid = 1:0.4 (mass ratio)) was added and melted in an electric furnace at 950 °C. Covered with a watch glass, ultrapure water and 5 mL of 6N hydrochloric acid were added, heated and dissolved on a hot plate at 70 - 80 °C, and after cooling, it was made up to 50 mL with ultrapure water to obtain a sample measurement solution. Using a standard solution for atomic absorption analysis (Si: 1,000 mg / L), a solution for preparing a calibration curve of 0.2 - 20 mg / L was prepared. Alkali flux and hydrochloric acid were added to each solution to the same extent as in the sample measurement solution. The prepared sample measurement solution was used to measure Si under the following conditions with an ICP optical emission spectrometer. Based on the Si measurement results, the concentration (ppm) of the amount of Si in the dry solids of the recycled pulp obtained after the washing process was calculated, and the results are shown in Table 1. The lower the Si content in the dry solids of the recycled pulp, the better the silicone It is a method for pulping paper with improved removal rate of compounds from paper. In addition, the Si content in the dry solid matter of the direct release paper (untreated direct release paper) before treatment in each example and comparative example was measured using the same method, and the Si content in the direct release paper was found to be 4,500 ppm.

[0063] (Measurement conditions for ICP optical emission spectrometer) Analytical equipment: Thermo Fisher Scientific iCAP6500Duo Wavelength:Si 251.611nm RF power: 1150W Coolant gas flow rate: 12L / min Nebulizer flow rate: 0.70 L / min Auxiliary gas: 0.5L / min Pump flow rate: 50 rpm

[0064] <Yield measurement method> The entire discharged liquid (froth) from the flotation process was poured into an empty aluminum cup whose dry mass had been measured, and dried in a dryer at 105°C until all the water was removed. Next, the mass of the aluminum cup after water removal was measured, and the amount of solids discharged was calculated using the following formula (2). The yield was calculated from the calculated amount of solids discharged using the following formula (3). The results are shown in Table 1. Solids discharged (g) = mass of aluminum cup after drying (g) - mass of empty aluminum cup (g) (2) Yield (%) = [Solid mass (g) contained in raw slurry - Solid mass (g) discharged] / Solid mass (g) contained in raw slurry × 100 (3) The results of the froth mass, silicon content in the dry solid content of the recycled pulp, and yield are shown in Table 1.

[0065] [Table 1]

[0066] As shown in Table 1, the addition of cationic surfactants reduced the Si content more than the addition of nonionic surfactants.

[0067] (ii) Examples 2 to 10 <Dissociation step> The dissociation step was performed in the same manner as in (i), except that no surfactant was added.

[0068] <Concentration step> In the concentration step, 2,000 g of the raw material slurry was transferred to a centrifugal dehydrator, and dehydration was performed using an 80-mesh cloth under the condition of 2,000 rpm until the total mass reached 333 g. By the concentration step, the solid content concentration of the raw material slurry was concentrated from 5% by mass to 30% by mass.

[0069] <Chemical solution addition step> In the chemical solution addition step, the following chemicals were added to achieve the concentrations shown in Table 2. The concentration of each chemical in Table 2 is the mass % with respect to the mass of the solid content contained in the raw material slurry. (Chemical) · Alkali agent: Aqueous sodium hydroxide solution, concentration 4 mol / L, manufactured by FUJIFILM Wako Pure Chemical Corporation · Bleaching agent: Hydrogen peroxide solution, H2O2 concentration 30% by mass, manufactured by FUJIFILM Wako Pure Chemical Corporation · Cationic surfactant: 0.2% by mass with respect to the mass of the solid content contained in the C1 - C9 raw material slurry <Pre-stage kneading step> Using a beating machine (PFI mill: manufactured by Kumagai Riki Kogyo Co., Ltd.), the kneading treatment of the raw material slurry was performed under the conditions of 40°C and 100 counts. The clearance of the beating machine was 0.1 mm. Two counts on the count measuring device attached to the beating machine corresponded to approximately 1 second. When the pH of the raw material slurry was measured by the same measurement method as the <pH measurement method> above, the pH of the raw material slurry at 60°C was 12. Note that the amount of the solid content with respect to the raw material slurry after this step was 30% by mass, and there was no change from after the concentration step.

[0070] <Aging step> Next, 333 g of a slurry with a solid content concentration of 30% calculated from formula (1) was placed in a vinyl chloride resin bag so as to maintain the temperature at 60°C, and immersed in a thermostatic bath filled with warm water at 60°C for 180 minutes to perform an aging process of the raw material slurry. When the pH of the raw material slurry was measured by the same measurement method as the <pH measurement method> above, the pH of the raw material slurry at 60°C was 12.

[0071] <Dilution process> (i) Similarly, the raw material slurry after the aging process was diluted with water to reduce the solid content concentration from 30% by mass to 1% by mass, and the diluted raw material slurry was subjected to a flotation treatment.

[0072] <Flotation process> (i) The flotation process was carried out in the same manner as (i).

[0073] <Washing process> (i) The washing process was carried out in the same manner as (i). After the above processes were completed, the froth mass, the amount of silicon in the dry solid of the recycled pulp, and the yield were evaluated. The results are shown in Table 2.

[0074]

Table 2

[0075] As is clear from Table 2, when various cationic surfactants were added, the Si content in the recycled pulp obtained from the direct release paper with a Si content of 4,500 ppm was reduced to 23~890 ppm.

[0076] (iii) Example 11 <Disintegration process> (ii) The disintegration process was carried out in the same manner as (ii).

[0077] <Concentration process> (ii) By the same concentration process as (ii), the solid content concentration of the raw material slurry was concentrated from 5% by mass to 30% by mass.

[0078] <Chemical Solution Addition Step> In the chemical solution addition step, the following chemicals were added so as to achieve the concentrations shown in Table 3. The concentrations of each chemical in Table 3 are mass % with respect to the mass of the solid content contained in the raw material slurry. (Chemical) ·Alkali agent: Aqueous sodium hydroxide solution, concentration 4 mol / L, manufactured by FUJIFILM Wako Pure Chemical Corporation ·Bleaching agent: Hydrogen peroxide water, H2O2 concentration 30 mass %, manufactured by FUJIFILM Wako Pure Chemical Corporation ·Cationic surfactant: 0.2 mass % with respect to the mass of the solid content contained in the raw material slurry

[0079] <Mixing Step> The mixing step was carried out in the same manner as the <pre-stage mixing step> in (ii). When the pH of the raw material slurry was measured by the same measurement method as the <pH measurement method> above, the pH of the raw material slurry at 60 °C was 12. In addition, the amount of solid content with respect to the raw material slurry after this step was 30 mass %, and there was no change from after the concentration step.

[0080] <Aging Step> The dissociation step was carried out in the same manner as in (ii). When the pH of the raw material slurry was measured by the same measurement method as the <pH measurement method> above, the pH of the raw material slurry at 60 °C was 12.

[0081] <Dilution Step> In the same manner as in (i) and (ii), the raw material slurry after the aging step was diluted with water to reduce the solid content concentration from 30 mass % to 1 mass %, and the diluted raw material slurry was subjected to a flotation treatment.

[0082] <Flotation Step> The flotation step was carried out in the same manner as in (i) and (ii).

[0083] <Washing Step> The washing step was carried out in the same manner as in (i) and (ii). After the above steps were completed, the froth mass, the silicon content in the dry solid content of the recycled pulp, and the yield were evaluated. The results are shown in Table 3.

[0084] [Table 3]

[0085] Good results in the process shown in Table 3 silicone Compound removal was observed.

Claims

1. A method for removing silicon compounds from paper, comprising the step of treating a raw material slurry containing water and paper having a layer containing a silicon compound with a solvent containing a cationic surfactant.

2. 2. The method for removing silicon compounds according to claim 1, wherein the step of treating with a solvent containing a cationic surfactant is a flotation step.

3. The cationic surfactant concentration in the flotation process is calculated using the following formula: [Amount of cationic surfactant added (g)] / [Mass of raw material slurry (g)]×10 ６ (ppm) The method for removing silicon compounds according to claim 2, wherein the concentration of the silicon compound in the solution is 1 ppm or more and 100 ppm or less.

4. The cationic surfactant is represented by the general formula (1) 【Chemistry 1】 (In the formula, R １ represents an alkyl or alkenyl group having 8 to 18 carbon atoms. ２ ~R ４ each independently represents an alkyl group having 1 to 18 carbon atoms which may be substituted with a hydroxy group, or a benzyl group. － indicates the counter anion.) 4. The method for removing silicon compounds according to claim 1, wherein the silicon compound is a quaternary ammonium salt represented by the formula:

5. A silicone compound remover containing a cationic surfactant for removing silicone compounds from paper having a layer containing silicone compounds.

6. A silicon compound remover containing the cationic surfactant according to claim 5, which functions in a flotation step in removing silicon compounds from paper having a layer containing silicon compounds.

7. A method for producing recycled paper from paper, comprising a step of treating a raw material slurry containing water and paper having a layer containing a silicon compound with a solvent containing a cationic surfactant.

8. The method for producing recycled paper from paper according to claim 7, wherein the process in which the solvent containing the cationic surfactant functions is a flotation process.

9. A recycled paper obtained by treating paper having a layer containing a silicon compound on at least a portion of a substrate with a solvent containing a cationic surfactant.

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