JP2005206978A - Method for producing waste paper pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a waste paper pulp by which the waste paper pulp having a high ash content and high whiteness is obtained from a printed, waste paper having the high ash content to reduce sludge ash and the amount of a filler used. <P>SOLUTION: The method for producing the waste paper pulp comprises disaggregating the waste paper, removing the ink from the disaggregated pulp, passing the ink-removed pulp through a cleaning step, and sending the resultant cleaned pulp to a raw material-regulating step of a paper machine. A coagulant 12 is added to the sent raw material by a transporting chest 2 or a transporting pump 3 in a step for sending the waste paper to the raw material-regulating step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing waste paper pulp, and more particularly to a method for producing waste paper pulp having a high ash content.

  Conventionally, various yield agents and yield systems have been studied and adopted for improving the yield of fillers and fine fibers in the papermaking stage. The most widely adopted system is a single polymer formulation using a cationic polymer. However, in the used paper recycling process, it is necessary to remove stains derived from used paper and printing inks such as carbon black, and therefore it has not been considered at all to use a coagulant that makes it difficult to remove these inhibitors. Further, even when a coagulant is used, there is a drawback that the effect cannot be exhibited due to the influence of mechanical pulp, anionic substance, suspended colloidal substance, etc. contained in the used paper.

  Therefore, in the conventional general waste paper pulp manufacturing method, waste paper pulp is manufactured through the steps of disaggregation, dust removal, bleaching, deinking, and washing regardless of the ash content in the waste paper raw material, and the ash content in the washing step. The mainstream method is to carry out the removal and produce waste paper pulp with low ash content.

  In addition, prescription using an anionic polymer in the used paper recycling process is also considered, but since the polymer itself is anionic, it is not easily affected by mechanical pulp, anionic substances and suspended colloidal substances contained in the used paper. Although it has the characteristics, there is a drawback in that deinking and bleaching are hindered by the circulation of the anionic polymer in the used paper recycling process.

In addition, technology using polyethylene oxide in the yield improvement system has been studied, and there is an advantage that it is hardly affected by mechanical pulp, anionic substances and suspended colloidal substances contained in waste paper, but polyethylene oxide alone is used. There are few methods of using polyethylene oxide and polyphenol resin (sulfonated phenol formaldehyde resin) together (for example, refer to Patent Document 1).
JP-A-9-188993

  However, the conventional waste paper pulp manufacturing method has a problem that the ash content of the waste paper pulp is low, which increases the cost of the filler used in the paper making process, while the waste discharged from the manufacturing process is high. There is a problem that the increase causes environmental degradation.

  Also, the formulation using both polyethylene oxide and polyphenol resin has the problem of high chemical costs due to the use of two liquids, and further, deinking and bleaching in the same way as anionic polymers due to circulation in the waste paper treatment process. There is a disadvantage that it becomes a factor that hinders the efficiency and effectiveness of the system.

  In view of the above-mentioned conventional problems, the present invention provides a method for producing waste paper pulp that can obtain waste paper pulp having high ash content and high whiteness from high ash printed waste paper, which can reduce sludge ash and use fillers. The issue is to provide.

  The method for producing waste paper pulp of the present invention is to add a coagulant to waste paper pulp that has been subjected to the treatment processes of waste paper decontamination, dust removal, bleaching, deinking, and washing, before being sent to the raw material adjustment process of the paper machine. To do.

  Waste paper pulp made from waste paper collected from the city contains a lot of printing ink components such as dirt derived from waste paper and carphone black, so as described above, disaggregation, dust removal, bleaching, deinking, washing process, etc. After the removal of impurities, it is recycled as raw material pulp, and the finished material of recycled recycled paper pulp still contains more inorganic materials such as fillers than kraft pulp, and the inorganic materials are subjected to deinking and bleaching processes. Therefore, the whiteness is generally high, and even if it is contained in the raw material pulp, it does not hinder the use as the raw material pulp. Therefore, in the present invention, by adding a coagulant to the final stage of the used paper pulp manufacturing process, ash is condensed in the used paper pulp, and used paper pulp having high ash content and high whiteness can be obtained. Thus, it is possible to prevent the outflow of ash after the raw material adjustment step of the paper machine using waste paper pulp and suppress the generation amount of sludge ash, and to reduce the use filler and reduce the cost.

  Further, it is preferable that the feed material to which the coagulant is added is stored in a pulp concentration of 2 to 5%, a temperature of 20 to 60 ° C., and a pH of 4 to 10. And, the addition amount of the coagulant is preferably 100 to 1000 ppm by weight against the dry pulp. If it is less than 100 ppm by weight, sufficient effects are not exhibited, and if it exceeds 1000 ppm by weight, problems such as pipe contamination may occur.

  The coagulant is composed of any one or a mixture selected from aluminum sulfate, polyacrylamide, polydadomac, polyamine, polyethyleneimine, 2- (methacryloyloxy) ethyltrimethylammonium chloride polymer, and modified polyethyleneimine. Is preferred.

  The addition place of the coagulant is preferably added by a flow pump or a flow chest.

  According to the present invention, before the waste paper pulp is fed to the raw material adjustment process of the paper machine, a waste paper pulp having high ash content and high whiteness can be obtained by adding a coagulant to the feed raw material. The generation amount can be suppressed, and the cost can be reduced by reducing the filler used.

  Hereinafter, an embodiment of the method for producing waste paper pulp of the present invention will be described in detail with reference to FIG.

  In FIG. 1, 1 is a high-ash content waste paper dissociated by a pulper, and deinked by performing dust removal treatment, alkali soaking treatment, flotation treatment and / or washing treatment on the dissociated pulp. It is a used paper pulp tank (DIP tank) which stores used paper pulp (DIP) which was bleached in response. The required amount of DIP in the DIP tank 1 is taken out by the take-out pump 2 and supplied to the flow chest 3, and the DIP having a predetermined concentration of about 2 to 5% with white water in the white water pit 4 from the flow chest 3. The slurry is diluted with slurry and fed to the raw material adjustment process section 6 of the paper machine 11 by the feed pump 5.

  In the raw material adjusting process section 6, a dewatering device 7 is disposed at the inlet, and the DIP slurry thus fed is dewatered by the dewatering device 7 to a concentration suitable for blending as a papermaking raw material. The dehydrated white water is temporarily stored in the white water pit 8 and then returned to the white water pit 4 of the DIP manufacturing process section. The DIP slurry having a predetermined concentration by the dewatering device 7 is once received by the DIP chest 9, then fed to the blending chest 10, blended with other various raw materials, and then fed to the paper machine 11. .

  The coagulant 12 is added to the DIP slurry in the flow chest 3 at the final stage of the DIP manufacturing process section. In addition, you may make it add to the suction side of the inflow pump 5 instead of adding in the inflow chest 3 as shown with a virtual line. In this way, by adding the coagulant 12 to the DIP slurry in the final stage of the DIP manufacturing process section, waste paper pulp having a content of ash content of 10% or more can be obtained from waste paper pulp that has been disaggregated from high ash printed waste paper.

  As the coagulant 12, aluminum sulfate, polyacrylamide, polydadomac, polyamine, polyethyleneimine, 2- (methacryloyloxy) ethyltrimethylammonium chloride polymer, and modified polyethyleneimine are preferable, and one or more of them are selected. It is preferred to add the mixture. Further, the amount added is preferably about 100 to 1000 ppm by weight against dry pulp. If it is less than 100 ppm by weight, the coagulation effect is not sufficiently exerted, and if it exceeds 1000 ppm by weight, excessive additives may leak and form a lump of dust in the flow pipe, which is not preferable.

  In this way, at the final stage of the used paper pulp manufacturing process, the coagulant 12 is added to the DIP slurry on the suction side of the flow chest 3 or the flow pump 5, so that the coagulant 12 can coagulate ash into the pulp. As a result, waste paper pulp with high ash content and high whiteness can be obtained. Therefore, it is possible to prevent the ash outflow after the raw material adjustment step 6 of the paper machine 11 using waste paper pulp and suppress the generation amount of sludge ash, and to reduce the use filler and reduce the cost. .

  In addition, in the dehydrator 7 of the raw material adjustment process 6, by adding a coagulant such as polyacrylamide, polydadomac, polyamine, polyethylimine, the ash content in the filter is improved, and the ash content flowing into the white water is reduced. The ash outflow to the waste water can be reduced.

  Next, some examples and comparative examples of the present invention will be described.

  When making LWCP (Low Weight Coated Paper) using waste paper pulp (DIP) that has been deinked using high ash printed waste paper, As shown in Table 1, as Examples 1 to 7 and Comparative Examples 1 and 2, polyacrylamide, polydadomac, polyamine, and polyethyleneimine were added at 50, 100, 500, 1000, and 2000 ppm by weight as dry dry pulp. . Further, as Comparative Example 3, LWCP was similarly made without adding a coagulant to the DIP slurry.

  And about each Examples 1-7 and Comparative Examples 1-3, the ash content rate (%) in the pulp which shows the yield of ash content, and SS (ppm) of returned water were measured. In addition, from the amount of the coagulant to be added, the economic efficiency was evaluated relative to ○ and ×, and comprehensive evaluation was performed. The results are shown in Table 1.

なお、総合評価は灰分含有率と返送水のＳＳと経済性から◎と○と×の３者に相対的に分類評価した。

In addition, comprehensive evaluation was classified and evaluated relative to the three of ◎, ○, and × based on the ash content, SS of returned water, and economic efficiency.

  From Examples 1 to 7 in Table 1, it can be seen that an ash content of 11% or more can be ensured by adding a coagulant at 100 to 1000 ppm by weight with a flow chest or flow pump. In addition, as a coagulant, the polyacrylamide, polydadomac, and polyamine of Examples 1 to 3 and the polyethylimine of Examples 4 to 7 were compared. In Examples 4 to 7 to which polyethylimine was added, SS of the return water was used. It can be seen that this is particularly effective because it can be clearly reduced. Further, Examples 5, 6, and 7 show that a greater effect is exhibited as the amount of the coagulant is increased within the above range. And what added polyethylimine as a coagulant 500 weight ppm with a flow chest or a flow pump became the best in comprehensive evaluation.

  On the other hand, in Comparative Example 1 in which the coagulant was added by 2000 ppm by weight, the ash content and the SS of the return water were almost the same as those in Example 7 in which the coagulant was added by 1000 ppm by weight. Therefore, the economic evaluation is poor and the overall evaluation is poor. In addition, although not shown in the table, excessive coagulant tends to cause a lump of dust in the flow pipe, which may increase the number of maintenance. Further, in Comparative Example 2 in which 50 ppm by weight of the coagulant was added, the effect of adding the coagulant was not obtained so much, and it was finally possible to secure an ash content of 10%, the SS of the return water was high, and the economic efficiency was Although good, the overall evaluation is poor because the effect is low. Moreover, in the comparative example 3 which has not added the coagulant | flocculant, it turns out that ash content is low, especially SS of return water is as high as 500 ppm, and ash content collection | recovery has not been performed.

  The method for producing waste paper pulp of the present invention provides a high whiteness and high whiteness waste paper pulp by adding a coagulant to the feed material before feeding the waste paper pulp to the raw material adjustment step of the paper machine. In addition, since it is possible to reduce the cost by suppressing the amount of sludge ash generated and reducing the amount of filler used, it is useful for all papermaking products using waste paper pulp.

It is a schematic block diagram of the final stage of a used paper pulp manufacturing process in one Embodiment of this invention, and the raw material adjustment process of a paper machine.

Explanation of symbols

1 Waste paper pulp tank (DIP tank)
3 Flowing chest 5 Flowing pump 12 Coagulant

Claims (4)

  Waste paper pulp, which is characterized by adding a coagulant to waste paper pulp that has passed through the treatment processes of waste paper disaggregation, dust removal, bleaching, deinking, and washing before being sent to the raw material adjustment process of the paper machine Method.   The method for producing waste paper pulp according to claim 1, wherein the amount of the coagulant is 100 to 1000 ppm by weight with respect to the dry pulp.   The coagulant is composed of any one or a mixture selected from aluminum sulfate, polyacrylamide, polydadomac, polyamine, polyethyleneimine, 2- (methacryloyloxy) ethyltrimethylammonium chloride polymer, and modified polyethyleneimine. A method for producing waste paper pulp according to claim 1 or 2. The method for producing waste paper pulp according to any one of claims 1 to 3, wherein the coagulant is added to a flow pump or a flow chest.

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