JP6618146B2 - Method for deinking UV printed matter - Google Patents

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 Application Laid-Open No. 10-149473 (Patent Document 1) proposes a method for identifying bills or 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. Has 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-A-2005-345208 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 Recycle Promotion Center)

  In view of the circumstances 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 made it possible to efficiently use the waste paper raw material by using a chemical containing an anionic surfactant in an emulsion state at a temperature higher than the dissolution temperature of the anionic surfactant. As a result, the present invention has been completed.

Although not limited to this, this invention includes the following aspects.
(1) A step of obtaining pulp slurry by dissociating used printing paper containing UV printed matter into an aqueous solvent, and a deinking agent containing an anionic surfactant in an emulsion form at a temperature below the dissolution temperature of the anionic surfactant A method for producing deinked pulp from waste printed paper, comprising a step of contacting with a pulp slurry.
(2) The method according to (1), further comprising a step of removing ink from the pulp slurry treated with the deinking agent.
(3) The method according to (1) or (2), wherein the anionic surfactant is a fatty acid surfactant.
(4) The method in any one of (1)-(3) in which the said anionic surfactant contains the fatty acid salt of C18-C22.
(5) The method according to any one of (1) to (4), wherein the dissolution temperature of the anionic surfactant is 20 to 65 ° C.
(6) The method according to any one of (1) to (5), wherein the deinking agent contains 10 to 50% by weight of a C18 to C22 fatty acid salt.
(7) A deinking agent comprising an anionic surfactant having a melting temperature of 20 to 65 ° C. for deinking waste printed paper containing UV printed matter.
(8) The deinking agent according to (7), wherein the anionic surfactant is a fatty acid surfactant.
(9) The deinking agent according to (7) or (8), comprising a fatty acid salt of C18 to C22.
(10) The deinking agent according to any one of (7) to (9), comprising 10 to 50% by weight of a fatty acid salt of C18 to C22.

  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 a graph showing the results of differential thermal analysis measured in Experiment 1 (1: anionic surfactant A, 2: anionic surfactant B, 3: anionic surfactant C). FIG. 3 is a photograph showing the state of the surfactant solution prepared in Experiment 1 (2) (left: 40 ° C., right: 50 ° C.).

  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 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. However, UV printing is known as printing that is difficult to deink, and in some cases, as a contraindicated product, a process for producing deinked pulp is performed. 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 highly sensitive UV inks that are easier to recycle than conventional UV inks have been developed and used to improve the recyclability of UV prints 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 by releasing the printed material into a slurry. Is obtained by removing the ink using Examples of the printed material used as a raw material include newspapers, flyers, magazines, books, office paper, sealed letters, thermal paper, carbonless paper, cardboard, white paperboard, other copiers, and printing paper 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 such as a resin, or a laminate 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 can be used. Examples of apparatuses used in the deinking process include a kneader, a disperser, and a floatator. For example, in one embodiment of producing a deinked pulp, a disaggregation process in which an alkaline chemical or a surfactant is added to disaggregate used paper, an ink exfoliation process in which ink is separated from the 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. Further, for example, after dehydrating the pulp and adjusting it to a pulp concentration of 20 to 35% by mass, an ink is further peeled off from the pulp by adding an alkaline chemical or a surfactant (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 matter.

  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”.

Anionic Surfactant In the present invention, a chemical containing an anionic surfactant is used in an emulsion state at a temperature not higher than the dissolution temperature (Kraft point) of the anionic surfactant. By using an anionic surfactant at a temperature equal to or lower than the dissolution temperature, the anionic surfactant is used in an emulsion state (suspension state), and the pulp fiber and the deinking agent are efficiently brought into contact with each other to effectively produce ink. Can be peeled off.

  The dissolution temperature of the anionic surfactant used in the present invention is preferably in the range of 20 to 65 ° C, more preferably 30 to 60 ° C, and may be 40 to 55 ° C. The dissolution temperature (Kraft point) of an anionic surfactant is the temperature at which the surfactant precipitates when the emulsion in which the surfactant is dissolved in water is cooled. As a result, the solubility rapidly increases and micelles are formed. In general, it is said that the surfactant does not form micelles at a temperature lower than the dissolution temperature, and thus the cleaning effect of the surfactant is lost. Surprisingly, the inventors have dissolved the anionic surfactant in its dissolution state. It has been found that deinking can be efficiently performed from UV printed matter by using it below the temperature.

  In a preferred embodiment, the anionic surfactant used in the present invention is a fatty acid anionic surfactant and contains 10 to 50% by weight of a long-chain fatty acid salt having 18 to 22 carbon atoms. In general, the longer the hydrophobic chain of the anionic surfactant, the higher the dissolution temperature, but the dissolution temperature is supposed to change depending on the composition of other components.

  In one embodiment, the anionic surfactant can be in the form of an emulsion and then added to the pulp slurry. Although the preparation method of an emulsion is not specifically limited, It can prepare by adding an anionic surfactant so that it may become a desired density | concentration in water, and fully stirring at the temperature below a dissolution temperature. In the present invention, the solid content concentration of the emulsion containing the anionic surfactant is preferably 1 to 50% by weight, and more preferably 5 to 30% by weight. When the solid content concentration is 1% by weight or less, the effect of promoting the ink peeling tends to be reduced. When the solid content concentration is 50% by weight or more, the fluidity of the suspension is deteriorated, and the operation may be difficult. There is.

  The emulsion containing an anionic surfactant is preferably used immediately after preparation. If a long time elapses after the preparation, the effect of promoting ink peeling may be reduced.

  The amount of the anionic surfactant used in the present invention is preferably 0.1 to 5% by weight, more preferably 0.1 to 3.0% by weight, based on 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 printing 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. Moreover, regarding the temperature at the time of disaggregation processing, it can disaggregate at the temperature of 35 degreeC or more, 40 degreeC or more, 45 degreeC or more, 50 degreeC or more, for example.

Ink peeling treatment In the present invention, when performing an ink peeling treatment 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 manner may then be subjected to bleaching such as ECF bleaching as 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 excellent quality with less dirt on the paper (black spots, dust, etc.). 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) and other waste paper pulp, coated paper, coated base paper, and other papers. 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 zwitterionic 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: Analysis of anionic surfactant The physical properties of three types of anionic surfactants used as deinking agents were analyzed.
(1) Measurement of dissolution temperature (Kraft point) The temperature at which the hydrated crystals of an anionic surfactant dissolve is known as the Kraft point, but in a hydrated mixture of fatty acid salts, it differs from the Kraft point of a single component. Dissolves at temperature. Therefore, a differential scanning calorimeter Q2000 (manufactured by TA Instruments) is used for the following three surfactants (the weight ratio of the fatty acid salt is shown in parentheses), and the heating rate is 10 ° C. in a nitrogen atmosphere. The dissolution temperature was measured under the conditions of / min. A DSC chart is shown in FIG.
Anionic surfactant A (New pure soap, Miyoshi oil fatty acid sodium, 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, C18 unsaturated fatty acid has one double bond) Melting temperature: about 47 ° C
Anionic surfactant B (sodium salt of C16 fatty acid: sodium salt of C18 fatty acid = 7: 3, weight ratio) dissolution temperature 60 ° C.
Anionic surfactant C (sodium salt of C6 fatty acid: sodium salt of C10 fatty acid: sodium salt of C14 fatty acid: sodium salt of C18 fatty acid: sodium salt of C22 fatty acid = 10: 20: 20: 25: 25) 60 ° C
(2) Measurement of turbidity With regard to anionic surfactant A, the 660 nm transmitted light intensity of its 1% aqueous solution was measured with an ultraviolet / visible spectrometer, and a JIS K 0101 was obtained from a calibration curve prepared using a formazine standard solution. Turbidity (FTU) was calculated based on this.

  When the turbidity was about 40 FTU or more, the surfactant was present in a suspended state and was in the form of an emulsion (FIG. 3, left: 40 ° C./right: 50 ° C.). As is apparent from the table below, the anionic surfactant solution was in the form of an emulsion at temperatures below the dissolution temperature.

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 (non-deinked) having a solid concentration of about 15%.
(2) Refinement of ink and deinking As a deinking agent, anionic surfactant A (New pure soap, made by Miyoshi oil and fat, sodium fatty acid, melting temperature: about 47 ° C.) Used in an amount of 0.0% by weight. Specifically, the deinking agent was added to the pulp slurry, and the pulp slurry was stirred at about 40 ° C. or about 60 ° C. for about 25 minutes. When used at about 40 ° C., the deinking agent containing an anionic surfactant was in the form of an emulsion, but when used at about 60 ° C., the deinking agent was not in the form of an emulsion.

Next, the pulp slurry at about 40 ° C. was stirred for 500 counts with a PFI mill (manufactured by Kumagai Riki), and the ink was refined (sample A, before complete washing). Then, a sample refined on a 150-mesh sieve is taken (about 7 g in solid content), the ink is washed from above with shower water, and the pulp remaining on the sieve (sample B: deinked pulp, completely washed) After) was recovered.
(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).

The evaluation results are shown in the above table. As is clear from the table, when a deinking agent containing an anionic surfactant is used at a temperature not higher than the dissolution temperature of the anionic surfactant, a fine dirt (diameter of φ100 μm or more) is obtained after deinking. And coarse dirt (diameter φ250 μm or more) were efficiently removed.

Claims (6)

A step of disaggregating used printing paper containing UV printed matter in an aqueous solvent to obtain a pulp slurry;
Contacting the deinking agent containing the anionic surfactant with the pulp slurry in the form of an emulsion at a temperature not higher than the dissolution temperature of the anionic surfactant;
A method for producing deinked pulp from printed waste paper.   The method of claim 1, further comprising removing ink from the pulp slurry treated with the deinking agent.   The method according to claim 1 or 2, wherein the anionic surfactant is a fatty acid surfactant.   The method according to claim 1, wherein the anionic surfactant comprises a C18 to C22 fatty acid salt.   The method in any one of Claims 1-4 whose dissolution temperature of the said anionic surfactant is 20-65 degreeC.   The method according to any one of claims 1 to 5, wherein the deinking agent contains 10 to 50 wt% of a C18 to C22 fatty acid salt.