JP2006022414A - Method for producing ink-removed pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing ink-removed pulp capable of maintaining the low pulp concentration in its cleaning process by enabling the dehydration in a good efficiency in a dehydration and concentration process after the cleaning process. <P>SOLUTION: This method for producing the ink-removed pulp, passing through at least a disintegration process and ink-removal process and performing the dehydration and concentration process after the cleaning process is provided by adding 1-10 ppm water filterability-improving agent in the dehydration and concentration process or prior to that, and then performing the dehydration and concentration process. The water filterability-improving agent is preferably added before the cleaning process, and any of a polyethylene imine, Hofmann degradation product of a polyacrylamide, polyvinylamine-based polymer and benzyl group-containing acrylic cationic copolymer or their combinations can be used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention enables efficient dewatering in the dewatering and concentration process in the deinked pulp (DIP) manufacturing process, thereby enabling the concentration in the pre-selection process, which is the previous process, to be kept low, and improving the operability. The present invention relates to a method for producing black pulp.

  In recent years, the reuse of waste paper has become a major issue from the standpoint of energy saving and resource saving. In order to collect and reuse the used paper, the DIP is obtained through the steps of disaggregation, rough selection (dust removal), deinking, fine selection (dust removal), and bleaching. However, the order of this process is not necessarily limited to this, and for example, DIP production is also performed by providing a bleaching process before the selective process.

  The DIP from which ink and dirt have been removed in this way is used as all or part of raw materials for producing newspaper, medium-size printing paper, household paper and the like.

  However, in any DIP production, the selection process is a dust removal means that is performed at a low concentration after passing through steps such as deinking and washing, so the pulp at the exit of the selection process has a concentration of 0.5 to 2.5%. The concentration is extremely low, and usually a dehydrating and concentrating treatment is performed to make the pulp concentration 10 to 30% and send it to the next step.

  In general, an extractor, a thickener (a wolf type, a camya type, a valveless type, a disk type, etc.), and a press (a disk type, a screw type, a cylinder type, etc.) are used for this dehydration and concentration treatment.

  Here, when the dewatering capacity of the dewatering and concentrating process is insufficient, it is necessary to suppress the DIP production according to the dewatering capacity or to increase the dewatering equipment.

  On the other hand, as the amount of used paper increases, the ash content from the used paper often scales in the preparation and papermaking processes, which causes defects in the papermaking process, troubles in paper breaks, or white spots during printing. It has become.

  As a method for removing ash that is brought in from used paper, for example, Patent Document 1 below proposes a method of removing foreign matter by adding cross-linked polydiallyldimethylammonium chloride to a floater or pulp slurry upstream thereof. Patent Document 2 below proposes a method of adding a water-soluble amphoteric acrylamide polymer as a foreign matter removing agent or an ash removing agent to a floater in a used paper deinking process. Further, Patent Document 3 below proposes a method of newly providing an ash removal process, and performing a process of reducing the ash concentration of the raw material in the ash removal process before sending the disaggregated printed paper to the deinking process. .

However, these ash removal methods cannot remove ash as much as intended by the inventors.
JP 2001-271284 A JP 2002-115191 A JP 2002-138380 A

  The object of the present invention is to perform efficient dehydration in the dehydration concentration step in DIP production, so that the pulp concentration in the previous step of this step can be lowered, and the dust removal efficiency, ash removal rate, deinking It is an object of the present invention to provide a DIP manufacturing method in which operability is improved by increasing efficiency and high white paper is obtained.

  The present inventors have added a drainage improver to the pulp slurry introduced into the dehydration concentration step, or have been added before that, thereby improving the dewatering ability in the dehydration concentration step, Has found that the addition of the drainage improver can perform dust removal, ash removal and deinking better. The present invention has been made based on this.

  Therefore, the above-mentioned subject of the present invention is achieved by the following (1) to (4).

(1) In the method for producing a deinked pulp which has undergone at least a disaggregation step and a deinking step, and a dehydration concentration process is performed after the selection process, A method for producing deinked pulp, comprising adding 10 ppm and performing the dehydration concentration treatment.

(2) In the method for producing a deinked pulp which has undergone at least a disaggregation step and a deinking step, and a dewatering concentration process is performed after the selection process, A method for producing deinked pulp, comprising adding 10 ppm, performing the dehydration concentration treatment, and controlling the ash content to 2 to 12%.

(3) The method for producing a deinked pulp according to the above (1) or (2), wherein the drainage improver is added before the selection process.

(4) The above (1) to (1), wherein any one or combination of polyethyleneimine, polyacrylamide Hoffman degradation product, polyvinylamine polymer, benzyl group-containing acrylic cationic copolymer is used as the drainage improver. (3) The method for producing a deinked pulp according to any one of the above.

  According to the first aspect of the present invention, in the DIP manufacturing process, 1 to 10 ppm of a drainage improver is added at the time of the dehydration concentration process subsequent to the selection process, or before that, so that the dehydration capacity is reduced in the dehydration concentration process. Therefore, the concentration of the pulp slurry can be kept low in the selection process that is the first stage of the dehydration concentration process. In other words, since the pulp slurry concentration in the flowator, the selection process, the weight cleaner, etc. can be kept low, the operability can be improved.

  According to the invention of claim 2, in addition to the above, since the ash content of the pulp slurry is controlled to 2 to 12% by the addition of the drainage improver, ash, adhesive foreign matter, and dust are efficiently removed. DIP is obtained.

  The present invention is described in further detail below.

  In the DIP production method of the present invention, 1 to 10 ppm of a drainage improver is added during or before the dehydration concentration process following the selection process, and the pulp slurry to which the drainage improver is added is treated in the dehydration concentration process. The target is to perform dehydration and concentration. That is, in the present invention, by improving the dewatering ability in the dewatering and concentration treatment, the concentration of the pulp slurry can be kept low in the selection process that is the previous stage of the dewatering and concentration treatment, and the above-described drainage improver is added. Thus, the ash content is controlled to 2 to 12%.

  DIP is manufactured through a disaggregation process, a rough selection process, a deinking process, a fine selection (dust removal) process, a bleaching process, etc., and the pulp slurry concentration (0.5 to 2.5%) from the fine selection process is And 10 to 30% through the dehydration and concentration step. As an apparatus used in the dehydration and concentration step, for example, an extractor, a thickener (wolf type, kamiya type, valveless type, disk type, etc.), a press (disk type, screw type, cylinder type, etc.) can be used.

  As the drainage improver used in the present invention, any of those conventionally used in this field can be used. Typical examples include polyethyleneimine, polyacrylamide Hoffman degradation products, polyvinylamine polymers, combined use of benzyl group-containing acrylic cationic copolymers and colloidal silica. These can be easily obtained as commercial products. Among these, a polyacrylamide Hoffman degradation product is particularly preferable in terms of drainage.

  The drainage improver usually reduces the drainage on the wire and the wet paper moisture content after the dehydration press, speeds up the papermaking, reduces the steam consumption of the dryer, and improves the productivity. It is added to the papermaking raw material. In the present invention, such a drainage improver is added to the pulp slurry before or after the dehydration concentration step, and the pulp concentration of the pulp slurry is increased in the dehydration concentration treatment. It is considered that the rise of the value is caused by promoting the aggregation of pulp.

  The amount of the drainage improver added is 1 to 10 ppm, preferably 3 to 7 ppm, based on the pulp slurry. If the addition amount is less than 1 ppm, the dehydration concentration of the pulp slurry is insufficient, and if it exceeds 10 ppm, agglomeration occurs excessively, resulting in a problem that drainage is reduced.

  Further, the addition of this freeness improver can control the ash content to 2 to 12%, preferably 4 to 8%. In other words, the ash content is 2 to 12% by weight, preferably 4 to pulp. It can be reduced to ˜8% by weight.

  The reason why the ash content is reduced by the addition of the drainage improver is not necessarily clarified, but it is considered that the aggregation of the pulp is promoted preferentially over the aggregation of the ash content and the foreign matter. Considering these points, it is desirable to add the drainage improver before the selection process in order to increase dispersibility.

  The disaggregation step in the DIP production in the present invention is to add raw material waste paper to water containing alkali such as caustic soda and sodium silicate, and disaggregate the waste paper with a pulper to make a pulp slurry. While bleaching progresses.

  The coarse selection / selection process (dust removal) is a process in which white water of papermaking is circulated, and is also a process of removing foreign substances in the raw material with a screen cleaner, and the cleaner removes heavy foreign substances.

  In the deinking step, the pulp slurry sent through gentle kneading and crushing by a chemical immersion tower and a kneader is deinked by flotation. When fine bubbles are injected into a pulp slurry having a concentration of about 1% in the flotation, the bubbles are adsorbed to the ink particles aggregated to an appropriate size by the action of the deinking agent, and are lifted and removed.

  A bleaching process is a process of whitening a pulp using a chemical | medical agent. For chemicals, in addition to hydrogen peroxide, hydrosulfide, thiourea dioxide, hypo, etc., formamidine sulfonic acid (FAS) is also used to obtain high whiteness.

  The DIP thus produced is sent to the preparation process as a finished raw material or combined with other pulp. In the preparation step, a filler, a dye pigment, a sizing agent, a sulfuric acid band, a fixing agent, a paper strength enhancer, a yield improver, a drainage improver, and the like are internally added as necessary.

  Subsequently, the paper stock obtained in the preparation process is guided to a paper machine to perform paper making, and if necessary, a coating layer is formed on the paper by a coating machine.

  In the DIP obtained in the present invention, ash, adhesive substances, dust and the like are efficiently removed, so that foreign substances are not brought into the preparation process and the papermaking process. As a result, the occurrence of defects and paper breaks in the paper making process is reduced, and a stable quality paper can be obtained. Moreover, the product pulp whiteness increases due to the improved deinking efficiency. Furthermore, according to the present invention, it is possible to increase the production of DIP without requiring improvement of equipment.

  In the present invention, the raw paper used in the DIP production may be high-ash printing waste paper containing 15% or more (generally 15 to 35%) of ash in addition to newspaper waste paper and magazine waste paper. If the ash content is less than 15%, the amount of ash content is the same as that of ordinary newspapers including flyers. However, according to the method of the present invention, these waste papers can also be processed together with high ash printed waste paper. High ash printed waste paper includes 15-35% ash content printed on coated paper (art paper, coated paper, lightweight coated paper) and 15-35% ash content, which is non-coated paper. Examples include imitation waste paper.

  Hereinafter, the present invention will be specifically described based on examples. Unless otherwise specified, the raw material concentration means the solid content concentration, and the chemical addition rate is wt%.

(Examples 1-3 and Comparative Examples 1-3)
Waste paper raw materials, mainly coated paper, were added with caustic soda 1% to pulp and deinking agent (D1 series made by Kao Corporation) 0.3% pulp, and disaggregated at a raw material concentration of 15% to prepare a raw material slurry. . The ash content in this raw material was 15%.

  This raw material is diluted to 2.5% with white water that has been counter-flowed from the subsequent process, and large foreign substances are removed with a cylindrical centrifugal screen. Hymolock E-200, manufactured by Co., Ltd. was added in the amount shown in Table 1 or without addition, and after further selection with a cylindrical centrifugal screen, the raw material was dehydrated to a concentration of 25% with a thickener, and caustic soda was used. Add 0.3% pulp, 0.5% hydrogen peroxide to 0.5% pulp, 0.5% sodium silicate to pulp, rub each other with a high-speed stirrer, stir and mix, then age at 80 ° C for 1 hour, DIP was produced by diluting to a concentration of 1% with white water countercurrently flowing from the subsequent process.

  For these DIPs, the measurement results as shown in Table 1 were obtained.

(Note 1) The treatment capacity of the dehydration concentration step is a relative value when Comparative Example 1 (freeness improver: no addition) is set to 100.
(Note 2) The ash content was determined by the method of JIS P8204 by obtaining the absolute dry weight according to JIS P8203.
(Note 3) State Evaluation scale trouble, installed electronic scanning detector paper machine at (OMRON Corporation KZD-120X-A), × the number of scale detected by 1km ² per not less than 10 , 3-9 pieces were evaluated as Δ, and 2 or less as ◯.

The paper manufacturing method of the present invention can be applied to the manufacture of paperboard in addition to newspapers, magazine papers, and information papers.

Claims (4)

  In the method for producing deinked pulp, which has undergone at least a disaggregation process and a deinking process, and a dewatering concentration process is performed after the selection process, 1 to 10 ppm of a drainage improver is added to the dehydration concentration process process or prior thereto. A method for producing deinked pulp, wherein the dehydration concentration treatment is performed.   In the method for producing deinked pulp, which has undergone at least a disaggregation process and a deinking process, and a dewatering concentration process is performed after the selection process, 1 to 10 ppm of a drainage improver is added to the dehydration concentration process process or prior thereto. The method for producing deinked pulp, wherein the dehydration concentration treatment is performed and the ash content is controlled to 2 to 12%.   The method for producing a deinked pulp according to claim 1, wherein the drainage improver is added before the selection process.   Either one or a combination of polyethyleneimine, polyacrylamide Hoffman degradation product, polyvinylamine polymer, benzyl group-containing acrylic cationic copolymer is used as the drainage improver. The manufacturing method of the deinked pulp of description.