JP2017179660A - Deinking method from uv printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of producing a deinked pulp from waste paper raw material hard to be deinked such as a UV printed matter.SOLUTION: Provided is a deinking technique comprising: a step where printed waste paper including a UV printed matter is disaggregated into an aqueous solvent to obtain pulp slurry; and a step where a deinking agent containing alcohol, a surfactant and an electrolyte is contacted with the pulp slurry in a gel shape.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for producing deinked pulp by deinking printed matter. In particular, the present invention relates to a technique for producing a deinked pulp by deinking waste paper materials including a UV printed material (UV printed material). According to the present invention, it is possible to efficiently produce a deinked pulp of excellent quality from a UV printed material that is difficult to deink.

  In recent years, the use of waste paper has expanded from the viewpoint of resource saving or environmental problems. On the other hand, the quality and diversification of printed materials has progressed, and among the printed materials collected as used paper, it is often mixed with printed paper that is difficult to recycle, for example, UV-printed materials or printed materials coated with resin films. It is like that.

  When producing deinked pulp (DIP) using these printed materials as raw materials, problems such as deterioration in operability of the production process and deterioration in the quality of the obtained recycled paper may occur (Non-Patent Document 1). ). When manufacturing pulp from waste paper raw materials that contain such hard-to-recycle printed matter, a strong mechanical load may be applied to the waste paper raw materials, and many chemicals may be used. New problems such as increased costs will arise.

  It has been studied to sort out such hard-to-reproduce printed matter and remove the hard-to-regenerate printed matter as a contraindicated product from the waste paper raw material. However, for example, a UV clear-coated printed material is made so as not to cause an uncomfortable appearance with an existing aqueous clear-coated printed material, so it is difficult to visually distinguish the UV-clear coated printed material. is there. Therefore, as a technique for identifying printed matter, Japanese Patent Laid-Open No. 10-149473 (Patent Document 1) proposes a method for identifying bills and the like using a Fourier transform near-infrared analyzer (FT-NIR). Japanese Patent Application Laid-Open No. 2005-345208 (Patent Document 2) proposes a method of selecting a printed material that is difficult to recycle as used paper based on the solubility of the printed surface of the printed material in a solvent.

  In addition, devising how to use a deinking agent, it has been studied to efficiently perform deinking from raw paper materials. For example, JP 2007-119955 A (Patent Document 3) discloses that deinking can be efficiently performed by adding a polyethylene glycol type nonionic surfactant having a cloud point of 0 to 25 ° C. to a pulper. Have been described. Japanese Patent Application Publication No. 2005-520057 (Patent Document 4) proposes to effectively remove ink from pulp fibers by using a plurality of deinking agents having different cloud points.

  It has also been proposed to use an anionic surfactant as a deinking agent. For example, in Japanese Patent Application Laid-Open No. 2007-314894 (Patent Document 5) and Japanese Patent Application Laid-Open No. 2009-221636 (Patent Document 6), deinking is performed using a nonionic surfactant and an anionic surfactant in combination. Proposed.

Japanese Patent Laid-Open No. 10-149473 JP 2005-345208 A JP 2007-119955 A JP 2005-520057 Gazette JP 2007-314894 A JP 2009-221636 A

“Survey Report on Materials for Confirmation of Inhibition in Waste Paper Recycling” (issued by the Waste Paper Recycling Promotion Center)

  In view of the situation as described above, an object of the present invention is to provide a technique for producing deinked pulp from waste paper raw materials that are difficult to deink, such as UV printed matter.

  As a result of intensive studies on the above problems, the present inventors have found that gel-like deinking agents can be efficiently deinked from pulp by bringing them into contact with the pulp, and have completed the present invention.

Although not limited to this, this invention includes the following aspects.
(1) A step of disaggregating used printing paper containing UV printed matter into an aqueous solvent to obtain a pulp slurry, and a step of bringing a gel-like deinking agent containing alcohol, a surfactant and an electrolyte into contact with the pulp of the pulp slurry. A method for producing deinked pulp from used printed paper.
(2) The method according to (1), wherein the gel deinking agent is brought into contact with the pulp at a temperature equal to or lower than the dissolution temperature of the surfactant.
(3) The method according to (1) or (2), wherein the surfactant is a fatty acid surfactant.
(4) The method according to any one of (1) to (3), wherein the surfactant includes a fatty acid salt having 6 to 24 carbon atoms.
(5) The method according to any one of (1) to (4), wherein a dissolution temperature of the surfactant is 20 ° C. or higher.
(6) The method according to any one of (1) to (5), further including a step of removing ink from the pulp slurry treated with the gel deinking agent.
(7) A gel-like deinking agent comprising alcohol, a surfactant and an electrolyte for deinking waste printed paper containing UV printed matter.
(8) The deinking agent according to (7), wherein the surfactant is a fatty acid surfactant.
(9) The deinking agent according to (7) or (8), wherein the surfactant comprises a fatty acid salt having 6 to 24 carbon atoms.
(10) The deinking agent according to any one of (7) to (9), wherein the surfactant has a dissolution temperature of 20 ° C. or higher.

  According to the present invention, it is possible to produce deinked pulp by efficiently deinking printed matter that is difficult to regenerate. Since the technology according to the present invention can produce high-quality deinked pulp from printed materials that are difficult to recycle, it is possible to effectively utilize printed old paper that could not be used as a raw material for deinked pulp as a contraindicated product as a resource. It becomes possible.

FIG. 1 is a schematic view showing an embodiment of a process for producing deinked pulp from used paper raw materials. FIG. 2 is an appearance photograph of the gel prepared in Experiment 1 (1).

  The present invention relates to a technique for producing deinked pulp (DIP) by deinking waste paper raw materials. The present invention also relates to a technique for making recycled paper using deinked pulp obtained by deinking waste paper raw materials.

  In the present invention, a printed material is used as a raw paper raw material. The printed material 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, or printed on coated paper. The present invention can be applied to printed matter, printed matter obtained by printing 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, corrugated cardboard, white paperboard, and the like, and the present invention can also be applied to glossy printed matter and printed matter subjected to surface processing such as OP varnish or UV clear coat.

  As printed matter to which the present invention is applied, waste paper printed by any printing method can be used, and according to the present invention, it is possible to select a printed matter suitable for producing deinked pulp and recycled paper. Examples of printing methods applied to printed materials include UV printing, hybrid UV ink, UV printing using high-sensitivity UV ink, relief printing such as flexographic printing, intaglio printing such as gravure printing, and lithographic printing such as offset printing. And stencil printing such as screen printing (silk printing), electrostatic printing (toner printing) using static electricity, inkjet 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. For example, UV printing is a printing method in which ink is cured and fixed by UV light, and UV printed matter is known as printing that is difficult to deink. It is a printed matter that is prevented from mixing. Even with such UV printed matter, according to the present invention, deinked pulp can be produced. In recent years, hybrid UV inks and high-sensitivity UV inks that are easier to recycle than conventional UV inks have been developed and used to improve the recyclability of UV printed materials and / or to reduce the energy required for UV printing. However, a printed matter printed with such a high-sensitivity UV ink can also be deinked by the present invention. Here, the high-sensitivity UV ink refers to a UV ink that is compatible with a printing method such as a so-called energy saving UV system, a hybrid UV system, or an LED-UV system.

  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.

  In the present invention, deinked pulp can be produced using waste paper raw materials containing printed matter. The method for producing the deinked pulp is not particularly limited, and generally known methods can be employed. 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 floatator. 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. In addition, for example, after dehydrating the pulp to adjust to a pulp concentration of 10 to 35% by mass, an alkaline chemical or a surfactant is added to further peel the ink from the pulp (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”.

Gel deinking agent In the present invention, a gel deinking agent containing a surfactant is used. By contacting the deinking agent in the gel state with the pulp of the pulp slurry, the pulp and the deinking agent are in contact with each other in a locally high viscosity state, so that the ink can be effectively peeled from the pulp fiber. it can.

  The gel-like deinking agent used in the present invention contains an alcohol, a surfactant, and an electrolyte, (a) a lower alcohol having 1 to 4 carbon atoms, and (b) 6 carbon atoms having a melting temperature of 20 ° C. or higher. What contains (c) electrolyte containing the surfactant of -24 fatty acid salt is preferable.

<Lower alcohol>
The alcohol used in the present invention is preferably a lower alcohol having 1 to 4 carbon atoms and can be used regardless of whether it is linear or branched. In particular, when ethanol or isopropyl alcohol having a bactericidal action is used, the bactericidal action can be imparted to the gel-like deinking agent.

<Surfactant>
The surfactant used in the present invention is preferably a surfactant containing a fatty acid salt having 6 to 24 carbon atoms. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, may be a linear fatty acid or a branched fatty acid, and may further have a substituent such as a hydroxyl group. The number of carbon atoms of the constituent fatty acid is 6 to 24, preferably fatty acids having different carbon numbers are mixed, and soap or fatty acid derived from hardened oil can be used. Moreover, when there are many constituent ratios of the fatty acid with a long carbon chain, a gel-like deinking agent which is more stable at higher temperatures can be obtained.

  Moreover, it is preferable that the melt | dissolution temperature (craft point) of surfactant is 20 degreeC or more, It is preferable that it is the range of 20-65 degreeC, 30-60 degreeC is more preferable, Even if it is 40-55 degreeC. Good. Surfactant dissolution temperature (Kraft point) is the temperature at which the surfactant precipitates when the emulsion in which the surfactant is dissolved in water is cooled. If the temperature is increased, the solubility at the Kraft point Soars and micelles are formed. In general, at a temperature lower than the dissolution temperature, the surfactant cannot form micelles, so the cleaning effect by the surfactant is lost.In the present invention, the gel-like deinking agent containing the surfactant is dissolved at the dissolution temperature. It is preferably used in the following.

  Examples of the fatty acid salt having 6 to 24 carbon atoms include caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, partoleic acid, stearic acid, isostearic acid, Examples of such salts include oleic acid, linoleic acid, behenic acid, lignoceric acid, erucic acid, ricinoleic acid, and hydroxystearic acid. As the fatty acid salt, sodium salt, potassium salt, magnesium salt, calcium salt, zinc salt, and aluminum salt may be used alone or in combination.

  As the surfactant, only a fatty acid salt may be used, but other anionic, cationic, amphoteric and nonionic surfactants may be added as long as the object of the present invention is not impaired.

<Electrolyte>
Although it does not specifically limit as electrolyte used by this invention, What is necessary is just to use the salt containing sodium, potassium, magnesium, calcium, zinc, and aluminum individually or in mixture. Specifically, as the inorganic substance, sodium carbonate, sodium sesquicarbonate, sodium sulfate, sodium chloride, potassium carbonate, magnesium sulfate, calcium chloride, zinc chloride, aluminum sulfate, or the like can be used. As the organic substance, acetate, lactate, citrate, malate, tartrate, glutamate, gluconate, nitrilotriacetate and the like can be used.

  The deinking agent according to the present invention may contain an aqueous component, and the aqueous component usually means water, but it may be a mixed solution of polyhydric alcohol such as ethylene glycol, glycerin, propylene glycol and water. In the case of a mixed solution of water and polyhydric alcohol, the mixing ratio is not particularly limited, but the water content is usually 70% by weight or more, preferably 90% by weight or more in the solvent. Further, the solid content ratio of the gel deinking agent, that is, the gel deinking agent / (gel deinking agent + aqueous component) is usually 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more. 20% or less by mass.

  The mixing ratio of each component of the gel-like deinking agent of the present invention is such that (b component) / (a component + b component + c component) is usually 0.1% by mass to 50% by mass, preferably 1% by mass to 10%. It is below mass%. Moreover, (a component) / (a component + b component) is 30 to 90 mass% normally, Preferably it is 50 to 80 mass%. If the amount of the surfactant contained in the gel-like deinking agent is too small, the effect of promoting the ink peeling tends to be reduced. If the amount is too large, the fluidity of the gel-like deinking agent may deteriorate and operation may become difficult. .

Preparation of Gel Deinking Agent The surfactant of the present invention is added to the pulp slurry after making it into a gel form, and the gel containing the surfactant can be prepared by a known gelation method. Each component of the present invention does not necessarily need to be homogenized. However, it is easier to prepare the gel deinking agent and the preparation time can be shortened. Homogenization of each component can be performed by stirring and mixing each component. When the viscosity is too high at room temperature and mixing is difficult, stirring and mixing may be performed in a state where the fluidity is increased by heating. When mixing the powdery component and the liquid component, first dissolve the powdery component in an appropriate solvent such as water or alcohol, then add the liquid component and stir and mix The gel-like deinking agent can be obtained by uniformly dissolving the aqueous component and, if necessary, other components and cooling.

  The gel-like deinking agent of the present invention may contain other components depending on its use. For example, when used for a cleaning agent, a chelating agent may be blended in order to sufficiently exert the cleaning power. By using this chelating agent, not only can the white turbidity of the hard water aqueous solution due to the generation of scale in hard water containing calcium, magnesium, etc. be prevented, but also the detergency, foaming power and foam feel in hard water can be maintained it can. Such a chelating agent is not particularly limited, and those used in the past are used, and specifically, citrate, malate, tartrate, glutamate, pyrophosphate, polyacrylate, polymaleic acid Examples thereof include salts, gluconates, nitrilotriacetates, zeolites, tripolyphosphates, ethylenediaminetetraacetic acid (EDTA), and ethylenediamine. Among these, citrate, malate, tartrate, glutamate, pyrophosphate, etc. are highly safe to the human body, have no environmental pollution, and water, alcohol, etc. that constitutes a gel deinking agent It is suitable for use because it is highly compatible with and has excellent detergency, dirt dispersibility, foaming power and foam feel. One or more chelating agents selected from these groups may be contained in the gel-like deinking agent of the present invention in an amount of usually 0.01 to 50% by mass, preferably 1 to 30% by mass.

  The gel-like deinking agent containing a surfactant is preferably used immediately after preparation. If a long time elapses after the gel is prepared, the effect of promoting ink peeling may be reduced.

  The amount of the gel-like deinking agent used in the present invention is preferably 0.1 to 5% by mass, more preferably 0.1 to 3.0% by mass with respect to the weight of the absolutely dry pulp. By making the addition amount 0.1% by mass or more, the disaggregation property and ink releasability of the used paper can be improved. Further, if the added amount exceeds 5% by weight, the effect may be saturated, and the present invention can be carried out particularly efficiently in an amount of 5% by weight or less.

  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 11, more preferably 8 to 10.5, and even more preferably 9 to 10. 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.

Disaggregation Step In the present invention, the used paper is disaggregated in an aqueous solvent to obtain a pulp slurry. In this disaggregation step, a known device such as a high-concentration pulper, a low-concentration pulper, or a drum pulper can be used without limitation, but it is preferable to perform disaggregation using a high-concentration pulper. As for the temperature during the disaggregation treatment, as described above, when a nonionic surfactant is used, it is preferably carried out at a temperature equal to or higher than the cloud point, for example, 35 ° C or higher, 40 ° C or higher, 45 ° C. As described above, disaggregation can be performed at a temperature of 50 ° C. or higher.

Ink Stripping Treatment In the present invention, when performing an ink stripping process by mechanical share, known devices such as a kneader, a disperser, and a refiner can be used without limitation.

  In the present invention, after finishing the disaggregation process and the ink peeling process, a flotation aid such as a deinking agent, a bleaching agent, a chelating agent, and a flocculant is added as desired, and a flotation treatment and a washing treatment. Etc. can be performed. 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, paper can be produced using the deinked pulp obtained as described above. The papermaking method is not particularly limited, and generally known methods can be employed. According to the present invention, since it is possible to use a waste paper raw material with less mixing of printed matter that is difficult to deink, it becomes possible to efficiently produce excellent deinked pulp, and thus excellent recycled paper can be efficiently produced. Can be manufactured. In the papermaking method of the present invention, papermaking is not necessarily performed only with the deinked pulp obtained according to the present invention, and the deinked pulp obtained according to the present invention is used as a raw material pulp at an arbitrary ratio. Can be manufactured.

  In addition to the deinked pulp according to the present invention, for example, softwood or hardwood kraft pulp (NKP or LKP), mechanical pulp using softwood or hardwood, for example, groundwood pulp (GP), refiner groundwood pulp (RGP), thermo Loss including mechanical pulp (TMP), Chemi-thermo-mechanical pulp (CTMP), Chemi-Grand pulp (CGP), semi-chemical pulp (SCP), etc. You may make paper by using together the coat broke formed by disaggregating paper, 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 containing deinked pulp 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. . 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: Manufacture of surfactant-containing gel (1-1) In a flask equipped with a stirrer, a heater, a cooler, and a thermometer, 20 g of fatty acid sodium anionic surfactant (New pure soap, made by Miyoshi Oil & Fats) 20 g of water and 340 g of water were added, and the mixture was heated to 55 ° C. and dissolved by stirring. Then, 20 g of ethanol and 20 g of sodium sesquicarbonate were sequentially added, and further dissolved by stirring.

  Then, it cooled at 20 degreeC for 4 hours, and obtained the gel-like mixture of surfactant and ethanol. An appearance photograph of this gel-like mixture is shown in FIG. 2. This gel-like mixture maintained a gel state at 40 ° C., but dissolved when heated to 45 ° C.

  Further, a mixture was prepared in the same manner as above except that sodium sesquicarbonate was not added (comparative product). This mixture did not become a gel.

The composition of the fatty acid sodium anionic surfactant used in this experiment is as follows: C12 fatty acid sodium salt: C14 fatty acid sodium salt: C16 fatty acid sodium salt: C18 fatty acid sodium salt: C18 unsaturated fatty acid sodium salt = 15: 5: 20:20:40, and the C18 unsaturated fatty acid had one double bond.
(1-2) Anionic surfactant 20 g (DIA-NK-315, manufactured by Nisshin Chemical Co., Ltd., palmitic acid (carbon number 16) sodium was added to a flask equipped with a stirrer, a heater, a cooler and a thermometer. A mixture of sodium salt of stearic acid and stearic acid (18 carbon atoms, dissolution temperature: about 56 ° C.), 3 g of sodium hydroxide and 337 g of water were added, and the mixture was heated to 65 ° C. to stir and dissolve the components. Then, 20 g of sodium carbonate was sequentially added and further dissolved by stirring.

  Then, it cooled at 20 degreeC for 1 hour, and obtained the gel-like mixture of surfactant and ethanol. This gel-like mixture maintained a gel state at 55 ° C, but dissolved when heated to 60 ° C.

  Moreover, the mixture was created like the above except not adding sodium carbonate (comparative product). This mixture was suspendable but never gelled.

Experiment 2: Production of deinked pulp Deinked pulp was produced from raw materials including waste printed paper printed with UV ink by the following procedure. Furthermore, recycled paper was manufactured by hand-drawing using the obtained deinked pulp, and the quality of the deinked pulp was evaluated.
(1) Disaggregation with a pulper Using a high-concentration disaggregator (manufactured by Rikuma Kumagai), mixed printed waste paper (80 g) printed with UV ink and PPC paper (330 g, unprinted) with warm water (40 ° C, 2 L) Then, it was disaggregated at 40 ° C. for 6 minutes to obtain a pulp slurry having a solid concentration of about 15%. Furthermore, it was dehydrated by centrifugal dehydration to obtain a pulp slurry (non-deinked) having a solid concentration of about 25%.
(2) Miniaturization of ink and deinking (2-1) Deinking using the mixed gel of Experiment 1-1 As a deinking agent, the mixed gel prepared in Experiment 1-1 was used as a solid content with respect to the waste paper material It was used in an amount of about 3.0% by weight in terms of conversion. Specifically, this deinking agent was added to the pulp slurry, and the pulp slurry was stirred at about 40 ° C. for about 25 minutes. Further, the mixture of comparative products prepared in Experiment 1-1 (not containing Na and does not gel) is added to the pulp slurry in an amount of about 2.0% by weight in terms of solid content, and at about 55 ° C. for 25 minutes. The pulp slurry was stirred.

Subsequently, the pulp slurry was stirred for 500 counts with a PFI mill (manufactured by Rikuma Kumagai), and the ink was refined (sample A). Then, a sample refined on a 150 mesh sieve is taken (about 7 g in solid content), the ink is washed with shower water from above, and the pulp remaining on the sieve (sample B: deinked pulp) is recovered. did.
(2-2) Deinking using the mixed gel of Experiment 1-2 As the deinking agent, the amount of the mixed gel prepared in Experiment 1-2 is about 3.0% by weight in terms of solid content with respect to the waste paper raw material. Used in. Specifically, the deinking agent was added to the pulp slurry, and the pulp slurry was stirred at about 40 ° C. or about 55 ° C. for about 25 minutes. In addition, the mixture of comparative products prepared in Experiment 1-2 (not gelled) was added to the pulp slurry in an amount of about 2.0% by weight in terms of solid content, and the pulp slurry was stirred at about 55 ° C. for 25 minutes. did.

Next, the pulp slurry at about 40 ° C. or about 55 ° C. was stirred for 500 counts with a PFI mill (manufactured by Rikuma Kumagai), and the ink was refined (sample A). Then, a sample refined on a 150 mesh sieve is taken (about 7 g in solid content), the ink is washed with shower water from above, and the pulp remaining on the sieve (sample B: deinked pulp) is recovered. did.
(3) Papermaking and dirt measurement of recycled paper Using Sample A (undeinked pulp) and Sample B (deinked pulp), a handsheet with a basis weight of 60 g / m ² was manufactured according to JIS P 8222. . About the obtained handsheet, the fine ink was measured using the image-analysis apparatus (EasyScan, Nippon Paper Industries Unitech). In the table below, the number of darts means the number of darts per 1 m ² , and the area of the dart means the sum of dart areas (mm ² ) per 1 m ² .

The evaluation results are shown in the above table. As is clear from the table, when deinking is performed using a deinking agent containing a mixed gel of an anionic surfactant and ethanol, a fine dart (diameter φ100 μm or more) and a coarse dart (diameter φ250 μm or more) after deinking. ) Were efficiently removed.

Claims (10)

Depulverizing waste printed paper containing UV printed matter in an aqueous solvent to obtain a pulp slurry;
Contacting a gel-like deinking agent comprising an alcohol, a surfactant and an electrolyte with the pulp of the pulp slurry;
A method for producing deinked pulp from printed waste paper.   The method according to claim 1, wherein the gel-like deinking agent is contacted with the pulp at a temperature not higher than the dissolution temperature of the surfactant.   The method according to claim 1, wherein the surfactant is a fatty acid surfactant.   The method in any one of Claims 1-3 in which the said surfactant contains a C6-C24 fatty acid salt.   The method in any one of Claims 1-4 whose dissolution temperature of the said surfactant is 20 degreeC or more.   The method in any one of Claims 1-5 which further includes the process of removing ink from the pulp slurry processed with the gel-like deinking agent.   A gel-like deinking agent comprising alcohol, a surfactant and an electrolyte for deinking waste printed paper containing UV printed matter.   The deinking agent according to claim 7, wherein the surfactant is a fatty acid surfactant.   The deinking agent according to claim 7 or 8, wherein the surfactant comprises a fatty acid salt having 6 to 24 carbon atoms. The deinking agent according to any one of claims 7 to 9, wherein the surfactant has a dissolution temperature of 20 ° C or higher.