JP2018071020A - Paper containing deinking froth-derived pulp fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for producing a paper utilizing a deinking froth.SOLUTION: The production of a paper according to the present invention involves a step of giving a mechanical treatment to a deinking froth generated in a deinking treatment of a printed waste paper and a step of producing a paper from a pulp slurry containing the deinking froth to which the mechanical treatment has been performed.SELECTED DRAWING: None

Description

  The present invention relates to a technique for manufacturing paper using deinking floss generated in a deinking process of waste paper. In particular, the present invention relates to a technique for producing paper using pulp fibers contained in deinking floss. According to the present invention, paper is efficiently produced by effectively utilizing deinking floss as waste. be able to.

  In recent years, the use of waste paper has expanded from the viewpoint of resource saving or environmental problems. In general, deinked pulp (DIP) is produced by removing ink and the like from a printed matter collected as used paper by deinking treatment, and so-called recycled paper is produced using the deinked pulp.

On the other hand, a technique for effectively utilizing deinking floss generated in deinking processing of waste paper has been proposed.
For example, Patent Document 1 (Japanese Patent Laid-Open No. 2012-97368) proposes producing inorganic particles containing calcium carbonate from deinking floss discharged from the deinking process of used newspaper. Patent Document 2 (Japanese Patent Application Laid-Open No. 2012-201565) proposes producing composite particles of silica and calcium carbonate from deinking floss discharged from the deinking process of used newspaper, metakaolin and There are described particles in which calcium carbonate and silica are combined on the surface of hydrous magnesium silicate.

  Further, Patent Documents 3 to 5 propose that paper is produced using inorganic particles produced from the deinking floss discharged from the deinking process as a filler. That is, Patent Document 3 (Japanese Patent Laid-Open No. 2011-144470) includes newspaper paper internally containing inorganic particles derived from deinking floss, and Patent Document 4 (Japanese Patent Laid-Open No. 2011-25447) includes paper derived from deinking floss. Japanese Laid-Open Patent Publication No. 2010-229564, an ink jet recording paper internally containing inorganic particles, proposes a kraft paper internally containing inorganic particles derived from deinking floss.

JP 2012-097368 A JP 2012-201565 JP 2011-144470 JP 2011-025447 JP 2010-229564 A

  In general, deinking floss generated in the deinking process of waste paper mainly consists of foreign matter such as ink and adhesive contained in printed matter, inorganic particles contained in paper, etc. Thermal recycling has been performed to produce particles and to recover heat by burning deinked floss.

However, the deinking floss also contains pulp fibers. If the pulp fibers contained in the deinking floss can be reused, the deinking floss can be used more effectively.
In view of such circumstances, an object of the present invention is to provide a technique for effectively utilizing deinking floss generated in a deinking process of waste paper. In particular, the present invention relates to a technique for producing paper using pulp fibers contained in deinking floss.

  As a result of intensive studies on the above problems, the present inventors have found that deinking floss can be effectively utilized in the papermaking process by performing a specific mechanical treatment on the deinking floss generated in the deinking process of waste paper. The present invention has been completed.

Although not limited to this, this invention includes the following aspects.
(1) A step of performing mechanical treatment on deinking floss generated in deinking treatment of used printed paper, and a step of manufacturing paper from pulp slurry containing deinking floss subjected to mechanical treatment, Production method.
(2) The method according to (1), wherein a flotation treatment is performed after the step of performing the mechanical treatment.
(3) The method according to (1) or (2), wherein in the step of performing the mechanical treatment, mechanical treatment using cavitation is performed.
(4) The method according to any one of (1) to (3), wherein mechanical processing using a jet cavitation generator is performed in the step of performing the mechanical processing.
(5) The method according to (1) or (2), wherein in the step of performing the mechanical treatment, mechanical treatment using a rotary defibrator is performed.
(6) The method according to any one of (1) to (5), wherein the pulp slurry includes deinked pulp.
(7) Paper with internally added pulp fibers derived from deinking floss.
(8) A paper strength enhancer containing pulp fibers derived from deinking floss.

  According to the present invention, paper can be manufactured using fibers derived from the deinking floss generated in the deinking process of used paper. According to the present invention, it is possible to effectively use deinking floss as a resource as a resource. Further, when paper is made using pulp fibers derived from deinking floss, the strength (breaking length) of the paper and the printing surface feel are improved.

FIG. 1 is a diagram showing an example of a paper manufacturing flow according to the present invention. FIG. 2 is a diagram showing the processing apparatus used in Experiment 1 (Sample 2).

The present invention relates to a technique for producing paper using a deinking floss generated in a deinking process of used paper raw materials. In particular, the present invention relates to a technology that utilizes pulp fibers contained in deinking floss.
Deinking floss The present invention uses deinking floss. In the present invention, the deinking froth is a foam generated in the flotation process when used paper raw materials including printed matter are subjected to the deinking process, and contains ink components, fine fibers, inorganic chemicals, and the like. is there. As a printed material that is a raw material for waste paper, it can be used without particular limitation as long as it is printed on a base material including paper. For example, a printed material obtained by printing on a paper with a film or the like, coated paper It may include printed matter that has been printed, printed matter that has been printed on non-coated paper, and the like. Specifically, for example, newsprint paper, medium-quality paper, high-quality paper, coated paper, fine-coated paper, thermal recording paper, carbonless paper, high-quality colored paper, PPC paper (toner printing paper), paper container, seal paper The present invention can be applied to used paper printed on labels, forms, cardboard, white paperboard, and the like, and may be glossy printed matter or surface-treated printed matter such as OP varnish or UV clear coat.

  As printed matter to which the present invention is applied, used paper printed by any printing method can be used. Examples of printing methods applied to printed materials include relief printing such as flexographic printing, intaglio printing such as gravure printing, lithographic printing such as offset printing, stencil printing such as screen printing (silk printing), and static electricity using static electricity. Examples thereof include electroprinting (toner printing), UV ink, hybrid UV ink, UV printing using high-sensitivity UV ink, and ink jet printing and laser printing widely used for printers for personal computers. Moreover, there is no restriction | limiting in particular also about the printed ink (ink), The printed matter on which the color material used with various printing systems was printed can be used.

  In the present invention, the deinked pulp (DIP) means a pulp regenerated by removing printing ink and the like from a printed material. In general, chemicals such as mechanical stress and deinking agent are obtained while the printed material is disaggregated into a slurry. Is obtained by removing the ink using Examples of the printed material as a raw material include newspapers, flyers, magazines, books, office paper, sealed letters, thermal paper, carbonless paper, cardboard, white paperboard, other copiers, and printing papers generated from OA equipment. A printed material including a pressure-sensitive adhesive, an adhesive, a pressure-sensitive adhesive tape, a pressure-sensitive adhesive such as a magazine back glue, a coating or a laminate of a resin, etc. can also be used as the printed material of the present invention. The printed matter may contain inorganic particles called ash. Ash content refers to inorganic particles in general, and is a substance that remains when paper is incinerated, such as fillers and pigments added internally or coated during paper manufacture. Examples include calcium carbonate, talc, kaolin, titanium dioxide and the like, but are not limited thereto.

  The deinking floss according to the present invention occurs in the flotation process when producing deinked pulp using waste paper raw materials containing printed matter, but the method for producing the deinked pulp is not particularly limited and is generally known. This method can be adopted.

  In the present invention, when the printed material is deinked, a known deinking device or deinking agent can be used. Examples of apparatuses used in the deinking process include a kneader, a disperser, and a kneading pulper. Examples of deinking agents include known surfactants such as nonionic surfactants such as fatty acid salts, higher alkyl sulfates, alkylbenzene sulfonates, higher alcohols, alkylphenols, alkylene oxide adducts such as fatty acids, and the like. Examples include, but are not limited to, ionic surfactants, cationic surfactants, amphoteric surfactants, and organic solvents, proteins, enzymes, natural polymers, and synthetic polymers. Of course, it can be used as a deinking agent, whether it is a single component or a mixture of two or more components. For example, in one embodiment for producing deinked pulp, a disaggregation process for disaggregating used paper by adding an alkaline chemical or a surfactant, an ink exfoliation process for exfoliating ink from pulp under mechanical share and alkaline conditions, A flotation treatment and / or a washing treatment for removing the ink separated from the pulp can be performed. Also, for example, after dehydrating the pulp and adjusting it to a pulp concentration of 18 to 35% by weight, the ink is further peeled off by adding alkaline chemicals or surfactants (alkali dipping treatment or aging treatment), The ink may be removed from the pulp by re-floating or washing. Moreover, a dust removal step (foreign matter removal step) may be provided to remove foreign matters.

  In the present invention, the process of peeling the ink adhering to the pulp fiber by giving a mechanical share is called the “deinking process”, and the process of removing the peeled ink out of the system. Sometimes referred to as “ink removal process”.

  In the present invention, an alkaline chemical can be added to perform the deinking step. It is preferable to perform the deinking step at a pH of neutral or higher because the disaggregation property and ink releasability of waste paper are improved. In a preferred embodiment, the pH in the deinking step is 7 to 13, more preferably 8 to 12, and still more preferably 9 to 11. The pH may be adjusted at any time, but it is most preferable that the pH be adjusted during the disaggregation process, which is the first stage of the deinking process. The alkaline chemical may be at least one of caustic soda, potassium hydroxide, sodium silicate, and sodium carbonate.

  The deinking floss according to the present invention occurs in the flotation process when producing deinked pulp using waste paper raw materials containing printed matter, but the method for producing the deinked pulp is not particularly limited and is generally known. This method can be adopted.

Deinking treatment of used printing paper (Manufacture of deinked pulp)
In general, deinked pulp can be produced from waste printed paper by, for example, a series of processes as described below. In other words, waste paper is made into a slurry (pulverization process) with a disaggregation device with mechanical defibration, such as a pulper, and foreign matter is removed with a dust removal device such as a screen or a cleaner (dust removal treatment). Waste paper deinked pulp is produced by flotation and selection of fine fibers and ink components (flotation treatment), washing treatment and dehydration treatment using a flotation machine such as a floatator (bleaching treatment). Of course, for example, the flotation process may be performed in multiple stages, or the kneading (kneading) process or the dispersion (dispersion) may be performed during a series of processes.

(Disaggregation processing)
Generally, the used printing waste paper is made into a state where it is broken into pulp fibers by a pulper or the like, and a pulp slurry is obtained in which the waste paper is disaggregated in an aqueous solvent. The pulp concentration at the time of disaggregation is not limited, but the pulper is classified into a low-concentration pulper (concentration: 3 to 5%) and a high-concentration pulper (concentration: 13 to 18%) according to the pulp concentration to be treated. However, it may be classified based on the structure of the device (such as a kneading pulper). In the present invention, any pulper may be used, but it is desirable to use a high-density pulper or a drum pulper. According to these pulpers, the pulp can be disaggregated without making the foreign matter such as hot melt fine, so that the foreign matter can be processed with a cleaner or a screen in a state where the foreign matter has not been subdivided, and the foreign matter removal efficiency is improved. Get better.

(Dust removal treatment)
When producing deinked pulp, foreign matter can be removed using a dust removing device such as a screen or a cleaner. The dust removal treatment can be carried out in a plurality of times, and in a preferred embodiment, the foreign matter is removed to a level that satisfies the quality required for the finished pulp and the rough selection step for removing coarse foreign matter after disintegration of the used paper. A selection process can be provided. In a preferred embodiment, the waste paper slurry that has come out of the pulper is first separated by sand or metal with a high-concentration cleaner (concentration 3 to 4%) to remove heavy foreign substances, and then a coarse screen (concentration 1.5 to 4). %) Can remove strings and large sticky foreign matter. The treatment screen has a processing concentration of about 1.0 to 1.5%. However, when it is installed at the front stage of the floatator, it is relatively high concentration (1.5 to 2) in consideration of downsizing of the equipment and economy. %). In a preferred embodiment, a screen such as a round hole screen or a slit screen can be used. For example, the hole diameter of the round hole screen can be 1.0 to 7.0 mmφ, and the slit width of the slit screen is 0. .10 to 0.40 mm. In the present invention, dust can be removed using a cleaner, but the cleaner is a device that sorts out foreign matter based on the difference in specific gravity between fibers and foreign matter caused by eddy currents, and the weight of fine sand or metal that is difficult to remove with a screen. Suitable for removing foreign materials, hot melts, lightweight foreign materials such as poly string. In the cleaner, since the foreign matter removal efficiency is high when the slurry is at a low concentration, the slurry is usually processed at a concentration of about 1%.

(Bleaching treatment)
In the present invention, if necessary, a treatment such as bleaching can be performed using a chemical such as hydrogen peroxide. By ripening the pulp slurry under alkaline conditions, the unpeeled ink can be reduced. For example, the treatment is preferably performed after the coarse selection screen or the selective selection screen. When aging under alkaline conditions, it is also preferable to use a chemical such as hydrogen peroxide bleaching and add hydrogen peroxide and sodium silicate simultaneously with the alkaline chemical. Since the chemical effect is higher as the pulp concentration is higher, the pulp concentration is preferably about 13 to 30%. For example, when bleaching at a medium concentration, about 13 to 20%, when bleaching at a high concentration, It can be about 25 to 30%.

(Flotation process)
The flotator process (flotation process) is a process for sending air bubbles into the pulp slurry, adsorbing hydrophobic ink particles on the foam surface, and removing them out of the system. In a preferred embodiment, the pulp concentration at the time of performing the floatator treatment can be about 0.8 to 1.5%. Various devices can be used in the flotation process. As a device used for the flotation treatment, a forced air supply type flow rotator that forcibly sends air to the main body of the floatator by an externally installed blower, or an air self-supply that sucks air by pumping pulp slurry to the injector unit. Examples thereof include a floater of a formula, a BOX type flowator, an eco-cell type flowator, an MT flowator, an OK flowator, and a Maxell flowator.

(Kneading / dispersing)
In the present invention, since the ink is peeled off by mechanical force, kneading and dispersion can be performed. In addition to ink peeling, it is effective for making the particle diameter easy to remove with a floatator and reducing black dyed fibers. The treatment concentration is generally about 20 to 35%.

(Ink peeling treatment)
In the present invention, when performing an ink peeling process by mechanical share, known devices such as a kneader, a disperser, a mica processor, a kneading pulper, and a refiner can be used without limitation.

  In the present invention, after finishing the disaggregation step and the ink peeling treatment, various treatments may be performed by adding a flotation aid such as a deinking agent, a bleaching agent, a chelating agent, and a flocculant as desired. it can. Thereafter, a dust removal step (foreign matter removal step) may be performed. In these cases, since a high shearing force is not applied to the fibers and foreign matters, the pH may remain weakly neutral or neutral, or may be alkaline. However, it is desirable that the treatment with the weak alkalinity to neutrality be performed, the time during which the pulp fibers are under alkaline conditions is shortened, so that the COD reduction effect is enhanced. You may perform a dust removal process (foreign matter removal process) after a disaggregation process and / or after an ink peeling process.

  Further, the deinked pulp obtained in this way may be subjected to bleaching such as ECF bleaching, if necessary. Paper can be produced using deinked pulp produced by the method of the present invention. The paper containing deinked pulp produced according to the present invention has a small amount of dirt (black spots, dust, etc.) on the paper surface and has excellent quality. In the manufacturing method of the deinked pulp of the present invention, since it is not necessary to apply mechanical force more than necessary, swelling and damage of the pulp fiber is suppressed, and the freeness and strength of the fiber do not decrease. Paper having good bulk, opacity, and rigidity and excellent printability can be obtained.

In the present invention, the deinking floss is mechanically processed. In a preferred embodiment, the mechanical treatment for the deinking floss can be performed by a beater, a disaggregator, a kneading / dispersing machine, a cavitation process, or the like.

  Machines that can be used for mechanical processing include, for example, finer, refiner, refiner, double disc refiner, beater, etc. And kneader / dispersers such as kneaders, dispersers, hot dispersers, new tyzens, mica processors, and cavitation processing devices.

  In a preferred embodiment, it can be mechanically processed by a rotary type defibrator. That is, the deinking floss can be mechanically treated by hydrodynamic shock waves by rotating a disk-shaped or conical blade with a fine slit at high speed and introducing the deinking floss there. Examples of such an apparatus include a finaler, a conifer, a top finaler, a seven finaler, a conical disc, a deflaker, a conical flaker, and a power finalizer.

  The solid content concentration of the deinking floss slurry is preferably 0.01 to 5.0% by weight, more preferably 0.1 to 4.5% by weight, and further preferably 0.5 to 4.0% by weight. . Moreover, it is desirable that the pH of the slurry is in an alkaline condition because the amount of OH active radicals generated is increased. In the present invention, the temperature of the mechanical treatment is not particularly limited, but is preferably 5 to 80 ° C, and more preferably 10 to 70 ° C.

  In the present invention, the required energy can be reduced by adding a surfactant. As the surfactant to be used, known or novel surfactants, for example, nonionic surfactants such as fatty acid salts, higher alkyl sulfates, alkylbenzene sulfonates, higher alcohols, alkylphenols, alkylene oxide adducts such as fatty acids, etc. , Anionic surfactants, cationic surfactants, amphoteric surfactants and the like. These may be a single component or a mixture of two or more components. The addition amount may be an amount necessary for reducing the surface tension of the jet liquid and / or the liquid to be jetted.

  In the present invention, the deinking floss may be mechanically treated by cavitation. Cavitation is known to generate a high impact pressure of several GPa in a local region on the order of several μm when cavitation bubbles collapse, and in the present invention, deinking floss can be processed using cavitation. it can.

  In the present invention, when the cavitation is generated using the liquid jet, the deinking floss can be cavitation-treated by ejecting the deinking floss slurry as a liquid jet. The fluid in which the liquid jet forms a jet may be any liquid, gas, solid such as powder or pulp, or a mixture thereof as long as it is in a fluid state. Further, if necessary, another fluid can be added to the above fluid as a new fluid. The fluid and the new fluid may be uniformly mixed and ejected, but may be ejected separately. Here, the liquid jet is a jet of a fluid in which solid particles or gas are dispersed or mixed in the liquid or the liquid. In the present invention, a liquid jet containing slurry or bubbles of pulp or inorganic particles also corresponds. The gas referred to here may include bubbles due to cavitation.

  When a cavitation jet is generated through a nozzle or orifice tube, the cavitation number σ is (P2−Pv) / (P1−P2) from the nozzle upstream pressure P1, the nozzle downstream pressure P2, and the saturated vapor pressure Pv of the sample water. However, when the pressure difference between P1, P2, and Pv is large and P1 >> P2 >> Pv, the cavitation number σ can be approximated to P2 / P1. In the present invention, the cavitation number σ is desirably 0.001 or more and 0.5 or less, preferably 0.003 or more and 0.2 or less, and particularly preferably 0.01 or more and 0.1 or less. preferable. If the cavitation number σ is too small, the effect is small because the pressure difference from the surroundings when the cavitation bubbles collapse is low, and if the cavitation number σ is too large, the flow pressure difference is low and cavitation is difficult to occur.

  In the present invention, it is preferable to generate cavitation due to a liquid jet by injecting an injection liquid through a nozzle or an orifice pipe to the process water in the container. At that time, the pressure of the spray liquid (upstream pressure) is desirably 0.01 MPa or more and 30 MPa or less, preferably 0.7 MPa or more and 15 MPa or less, and particularly preferably 2 MPa or more and 10 MPa or less. When the upstream pressure is less than 0.01 MPa, it is difficult to produce a pressure difference with the downstream pressure, and the effect is small. On the other hand, when the pressure is higher than 30 MPa, a special pump and a pressure vessel are required, and energy consumption increases, which is disadvantageous in terms of cost. On the other hand, the pressure in the container (downstream pressure) is preferably 0.05 MPa to 0.3 MPa in static pressure. Moreover, the ratio of the pressure in the container and the pressure of the jet liquid is preferably in the range of 0.001 to 0.5.

  Further, the jet velocity of the jet liquid is desirably in the range of 1 m / second to 200 m / second, and preferably in the range of 20 m / second to 100 m / second. If the jet velocity is too low, cavitation is difficult to occur. If the jet velocity is too high, a special device is required to generate high pressure, which is disadvantageous in terms of cost.

  In the present invention, the cavitation generation place can be selected from any container such as a tank or inside a pipe, but is not limited thereto. Further, although it is possible to perform processing in one pass, the effect can be further increased by circulating the required number of times. Furthermore, it can be processed in parallel or in permutation using a plurality of generating means. Injection for generating cavitation may be performed in a container open to the atmosphere, but is preferably performed in a pressure container in order to control cavitation.

  In the present invention, the deinking floss that has been subjected to mechanical treatment may be further subjected to a flotation treatment. In a preferred embodiment, the concentration of the deinking floss slurry when performing the floatator treatment is about 0.4 to 3.0%, more preferably about 0.6 to 2.0%, still more preferably 0.8 to About 1.5%.

Production of Paper In the present invention, paper can be produced by internally adding the deinked floss mechanically processed product obtained as described above. The papermaking method is not particularly limited, and generally known methods can be employed. According to the present invention, the pulp fibers in the deinking floss that have been disposed of in the past can be used effectively, which is extremely excellent in terms of effective use of resources.

  According to the study by the present inventors, it has been found that the pulp fibers contained in the deinking floss are mostly fine fibers having a short fiber length. Therefore, the mechanically treated product of the deinking floss according to the present invention is contained in the pulp fiber. In addition, paper having excellent strength can be obtained by paper making. Since the fine fiber enhances the fiber-to-fiber bond between the pulps, it is considered that the mechanically treated product of the deinking floss functions as a paper strength enhancer and the strength of the paper is improved. Further, according to the present invention, since the strength of the paper is improved by adding a mechanically treated product of deinking floss to the paper, the strength of the paper can be maintained even if the blending amount of pulp is reduced.

  In the papermaking method of the present invention, it is not necessary to make paper using only the mechanically processed product of deinking floss, and paper may be manufactured using other pulp as a raw material pulp in an arbitrary ratio. In one preferred embodiment, the weight ratio of the mechanically treated deinking floss and other pulp can be, for example, 1: 99-20: 80, 2: 98-15: 85, 3: It is good also as 97-10: 90.

  In the present invention, as pulp, for example, deinked pulp (DIP), conifer or hardwood kraft pulp (NKP or LKP), mechanical pulp using conifer or hardwood, for example, groundwood pulp (GP), refiner groundwood pulp (RGP) , Thermo-mechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP), chemi-ground pulp (CGP), semi-chemical pulp (SCP), etc. used paper pulp, coated paper, coated paper, and other paper You may make paper by using together the coat broke formed by disaggregating the waste paper to contain, and the mixture of 2 or more types of these pulps.

  In the present invention, chemicals and fillers may be added when paper is made from pulp. Chemicals to be added include rosin emulsion, neutral rosin, alkyl ketene dimer, alkenyl succinic anhydride, styrene / acrylic copolymer, sizing agent, cationic, amphoteric, anionic polyacrylamide, polyvinylamine, polyamine Acrylic acid-containing resins, dry paper strength enhancers such as guar gum, cationic and amphoteric and anionic modified starches, wet paper strength enhancers such as polyamidoamine epichlorohydrin, carboxymethylcellulose, drainage improvers, Coloring agents, dyes, fluorescent dyes, coagulants, bulking agents, retention agents and the like can be mentioned. Further, the filler may be particles generally called inorganic filler and organic filler, and there is no particular limitation. Specifically, as inorganic fillers, calcium carbonate (light calcium carbonate, heavy calcium carbonate, synthetic calcium carbonate), magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay ( Kaolin, calcined kaolin, deramikaolin), talc, zinc oxide, zinc stearate, titanium dioxide, silica produced from sodium silicate and mineral acid (white carbon, silica / calcium carbonate composite, silica / titanium dioxide composite) , White clay, bentonite, diatomaceous earth, calcium sulfate, inorganic filler that regenerates and uses ash obtained from the deinking process, and inorganic filler that forms a complex with silica or calcium carbonate in the process of regeneration. As the calcium carbonate-silica composite, amorphous silica such as white carbon may be used together with calcium carbonate and / or light calcium carbonate-silica composite. Among these, calcium carbonate and light calcium carbonate-silica composite, which are typical fillers for neutral papermaking and alkaline papermaking, are preferably used.

  The paper produced by the present invention can be used as, for example, printing paper, newsprint paper, coated paper, information recording paper, processed paper, sanitary paper, etc., although not limited thereto. More specifically, examples of the information recording paper include electrophotographic transfer paper, ink jet recording paper, thermal recording material, and foam paper. More specifically, examples of processed paper include release paper base paper, laminated base paper, and base paper for molding. More specifically, sanitary paper includes tissue paper, toilet paper, paper towels, and the like. Moreover, it can also be used as a paperboard such as a corrugated base paper. Furthermore, it can be used as a base paper for paper having a coating layer containing a pigment, such as coated paper, information recording paper, and processed paper.

  Hereinafter, the present invention will be described more specifically with reference to experimental examples. However, the present invention is not limited to such experimental examples. In the present specification, unless otherwise specified, the numerical value range includes its end points, and the concentration and the like are based on weight.

Experiment 1: Mechanical treatment of deinking floss In Nippon Paper Industries Co., Ltd.'s A factory, printed waste paper including newspaper waste paper is disaggregated with a pulper (solid content 15%), treated in the order of cleaner and coarse screen, and then foreign matter. (Solid content concentration: 3%) and subjected to a flotation treatment (solid content concentration: 1%) using a floatator (MT flow rotator, manufactured by IHI Voith). The deinking floss (ash content 75%) obtained in the flotation treatment was subjected to the following mechanical treatment, and the obtained deinked pulp was used in Experiment 2.

(Sample 1)
The deinking floss was mechanically processed (solid content concentration) at a treatment amount of 0.3 m ³ / hr and a load of 30 kWh / t using a high-speed rotation type defibrating machine using a conical blade (Topfiner, manufactured by Aikawa Tekko). 2.4%). In this apparatus, a ring-shaped blade having a fine slit rotates at high speed, and the deinking floss is mechanically processed by a hydrodynamic impact force.

  Dilute the deinked floss after treatment to a concentration of 1%, and then treat for 3 minutes with a 5 L lab flotator (forced air supply type, manufactured by IHI Voith) so that the rejection rate is 60% (in terms of solid weight) The accept sample was collected as a sample.

(Sample 2)
A plant floss (concentration of 2.4%, ash content of 75%) was treated with a lab flowator as in sample 1 except that it was mechanically treated by jet cavitation. It was collected. The cavitation treatment is performed using the apparatus shown in FIG. 1 (nozzle diameter: 1.5 mm), the pressure of the spray liquid (upstream pressure) is 8 MPa, the pressure in the container to be sprayed (downstream pressure) is 0.3 MPa, and the jet flow The flow rate was 70 m / sec and the floss was circulated for 15 minutes for treatment.

(Sample 3: Comparative example)
Factory A floss (concentration 2.4%, ash content 75%) was treated with a lab flowator in the same manner as Sample 1 except that no mechanical treatment was performed, and the accept sample was collected as a sample.

(Analysis of each sample)
When each collected sample was analyzed, the concentration was 0.2% by weight and the ash content was 64%. In addition, each sample is spread on a wire (325 mesh), washed with tap water until the filtrate passing through the wire is not turbid, and then the washed sample is spread on a filter paper and filtered and dried to produce a mat. The ISO whiteness of the mat was measured.

  The results are shown below. The whiteness of the deinking floss was improved by performing the mechanical treatment.

Experiment 2: Polyethyleneimine (molecular weight: about 70) was added to the sample obtained in Paper Production Experiment 1 as a solid at 100 ppm to produce a slurry.

The slurry of Samples 1 to 3 is blended in an amount of 5 parts by weight with respect to 100 parts by weight of the deinked pulp obtained in Experiment 1 (DIP using newspaper waste paper as a raw material). A paper stock was prepared by blending 100 ppm of light calcium carbonate (average particle size 2.0 μm). From this stock, hand-sheets were prepared based on the Tappi standard method so that the basis weight was about 41 g / m ² and the ash content was about 15% (sheets A to C). As a control, a handsheet was prepared without adding the sample obtained in Experiment 1 (Sheet D).

  About the obtained hand-sheet, the tearing length was measured, and contamination of impurities was confirmed by image processing. Contaminants such as coarse ink were measured for the number of dirt having a particle size of 100 μm or more on five different hand-made sheets using a contaminant measuring device (Spec Scan 2000, manufactured by Apoge Technology).

In addition, solid printing was performed using a RI printer (black ink, fill amount 0.5 cc), and the printing surface feeling was evaluated in three stages. Evaluation criteria are as follows and evaluated visually.
○: There is almost no white spots in the solid print part. Δ: Some white spots in the solid print part are slightly observed.

  Hand-worked sheets (A, B) containing mechanically treated floss have improved paper strength (breaking length) and printing compared to hand-made sheets (D) not containing floss-treated products. Aptitude improved. In addition, hand-sheets (A, B) added with mechanically treated floss are more contaminated (dirt) than hand-sheets (C) with floss not mechanically treated. Reduced.

1: sample tank, 2: nozzle, 3: cavitation jet cell, 4: plunger pump, 5: upstream pressure control valve, 6: downstream pressure control valve, 7: upstream pressure gauge, 8: downstream pressure gauge, 9: Water supply valve, 10: Circulation valve, 11: Drain valve, 12: Temperature sensor, 13: Mixer

Claims (8)

  A method for producing paper, comprising: a step of performing mechanical treatment on deinking floss generated in deinking processing of used printed paper; and a step of producing paper from pulp slurry containing deinking floss that has been subjected to mechanical treatment.   The method according to claim 1, wherein a flotation treatment is performed after the step of applying the mechanical treatment.   The method according to claim 1, wherein mechanical processing using cavitation is performed in the step of performing the mechanical processing.   The method in any one of Claims 1-3 which performs the mechanical process using a jet type cavitation generator in the process of performing the said mechanical process.   The method according to claim 1 or 2, wherein in the step of performing the mechanical treatment, a mechanical treatment using a rotary defibrator is performed.   The method according to claim 1, wherein the pulp slurry contains deinked pulp.   Paper containing pulp fibers derived from deinking floss. Paper strength enhancer containing pulp fiber derived from deinking floss.