JP2005240188A - Method for producing waste paper pulp and waste paper pulp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing waste paper pulp realizing high brightness with a small amount of an added chemical. <P>SOLUTION: The method for producing the waste paper pulp comprises a disintegrating step of disintegrating and opening the waste paper, a bleaching/soaking step of adding the chemical to the disintegrated pulp and carrying out bleaching and soaking treatments, a floating step of diluting the pulp subjected to the bleaching and soaking treatments, blowing bubbles therein, floating and separating an ink and/or a washing step of washing the pulp. In the method for production, a chemical comprising an alkaline chemical, a deinking agent, hydrogen peroxide and its bleaching stabilizer is added to the disintegrated pulp and a dispersion treatment is carried out with a disperser as a pretreatment in the bleaching/soaking step. The bleaching and soaking treatments are then conducted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing waste paper pulp and waste paper pulp.

  In recent years, there has been a strong demand for recycling recycled paper from the viewpoint of protecting forest resources and the global environment, and deinked pulp produced from printed used paper can also be obtained from deinked pulp with high whiteness by appropriate processing. It is requested to be usable again as a raw material for various printing papers.

  An example of a method for producing deinked pulp will be described with reference to FIG. The waste paper is added with a deinking agent and an alkaline chemical, sent to the disaggregation process, disaggregated and defibrated by the pulper 1, and then removed by the screen 2 in the dust removal process. Next, ink is floated and separated by a flotation process by the flowator 3 in the deinking process. Next, after being carefully selected by the cleaner 4 in the selection process, the bleaching agent, the bleach stabilizer, the alkaline chemicals and the deinking agent are added in the bleaching / soaking process, and then put into the alkali soaking tower 5 for aging and bleaching. As the treatment is performed, an alkali soaking treatment is performed to swell the pulp fibers and peel the ink from the pulp fibers. Next, the ink is separated and removed by the floater 6 in the deinking process, and then dehydrated and washed by supplying the shower water 8 by the dehydrator 7 in the dehydrating and washing process. Thereafter, it is stored as waste paper pulp (DIP) in the stock tower 9 in the stock process. In addition, after passing through the bleaching / soaking step, deinking can also be performed by the dehydrator 7 in the dehydrating / washing step without going through the deinking step by the flowator 6.

  Further, in the bleaching and soaking process, conventionally, as shown in FIG. 3, the carefully selected pulp is passed through the disperser 10 to disperse the deposits such as fine ink still remaining on the pulp fibers. Thereafter, alkaline chemicals, a surfactant as a deinking agent, hydrogen peroxide as a bleaching agent, and the like are added to the pulp, and the pulp is put into the alkali soaking tower 5 to be aged.

  In addition, in the deinking process, by adding an ethylene glycol ether compound, the dispersibility of the deinking agent in water and fluidity are improved to improve the treatment effect, and a method for obtaining deinked pulp with higher whiteness is as follows. It is known (for example, refer to Patent Document 1).

In addition, in the alkali soaking treatment or the bleaching step, a method is also known in which the pulp is treated with ozone from neutral to alkaline to enhance the treatment effect and obtain deinked pulp with higher whiteness (for example, , See Patent Document 2).
JP-A-7-145582 JP-A-7-189154

  However, in the above conventional deinked pulp manufacturing method, the added amount of hydrogen peroxide is about 3.5 to 4.0% of dry pulp, and even if the added amount is increased, the whiteness of 77 to 87% is ensured. However, it was difficult to realize. In addition, in order to obtain higher whiteness, when a chemical such as an ethylene glycol ether compound is newly added as in Patent Literature 1 or a new treatment such as ozone treatment is added as in Patent Literature 2, There is a problem that it is difficult to obtain waste paper pulp having a whiteness of 77 to 87% because the cost is increased and a sufficient effect is not exhibited.

  In view of the above-described conventional problems, an object of the present invention is to provide a method for producing used paper pulp and a used paper pulp capable of realizing high whiteness with a small amount of added chemicals.

  The method for producing waste paper pulp according to the present invention includes a disaggregation process for disaggregating and defibrating waste paper, a bleaching / soaking process for adding chemicals to the disaggregated pulp to perform bleaching and soaking treatment, and diluting the bleached and soaked pulp. In the waste paper pulp manufacturing method, which has a floating step of blowing air bubbles to separate the ink and / or a washing step of washing the pulp, alkaline chemicals, deinking agents and peroxides are used as a pretreatment in the bleaching and soaking steps. A chemical containing hydrogen and its bleach stabilizer is added and dispersed with a disperser, followed by bleaching and soaking.

  According to this configuration, in the bleaching and soaking process, chemicals are added to the disaggregated pulp as a pretreatment for the bleaching and soaking process, and then the dispersion process is performed by the disperser, followed by the bleaching and soaking process. The chemicals are mixed evenly and the reaction proceeds efficiently, and the chemicals penetrate into the disaggregated pulp strongly in the subsequent bleaching and soaking treatments. High whiteness can be achieved with the added amount.

  The amount of hydrogen peroxide used in the bleaching and soaking process is 1.0 to 2.5% by weight, preferably 1.5 to 2.5% by weight, and most preferably 2.0 to 2%. .5% by weight The preferred amount of the bleach stabilizer used in the bleaching and soaking process is 0.01 to 5% by weight against dry pulp.

  As the bleach stabilizer, it is preferable to use one of sodium silicate and diethylenetriaminepentamethylenephosphoric acid or a mixture of both.

  Further, chemical addition in the bleaching and soaking process can be performed by both the dispersion treatment by the disperser and the bleaching and soaking treatment.

  Moreover, the used paper pulp of this invention is manufactured by the said manufacturing method, and whiteness is 77 to 87%.

  According to the present invention, in the bleaching / soaking step, chemicals are added to the disaggregated pulp as a pretreatment for the bleaching / soaking treatment, and then the dispersion treatment is performed by the disperser, and then the bleaching / soaking treatment is performed. The chemicals are uniformly mixed in the pulp and the reaction proceeds efficiently, and the subsequent chemical bleaching and soaking processes strongly penetrate the disaggregated pulp. High whiteness can be achieved by adding chemicals.

  Hereinafter, an embodiment of the method for producing waste paper pulp of the present invention will be described in detail with reference to FIGS. 1 and 2. In addition, the whole structure of the manufacturing method of the used paper pulp of this embodiment is fundamentally the same as the conventional method demonstrated with reference to the said FIG. 1, The description here is abbreviate | omitted using the description.

  In this embodiment, as shown in FIG. 2, first, alkaline chemicals, surfactant as a deinking agent, hydrogen peroxide as a bleaching agent, a bleaching stabilizer, etc., for the disaggregated pulp sent from the fine selection process Is added to the disperser 10 for dispersion treatment, and then the disperser 10 is fed to the alkali soaking tower 5 for aging reaction to perform bleaching and soaking treatment.

  Caustic soda is preferably used as the alkaline chemical. Further, the amount of hydrogen peroxide added for preventing alkali burn and bleaching of the pulp is 1.0 to 1.0% compared to the conventional dry pulp 3.5 to 4.0%. About 2.5%, preferably 1.5-2.5%, optimally 2.0-2.5% is sufficient. In addition, it is preferable to use sodium silicate, diethylenetriaminepentamethylenephosphoric acid or a mixture thereof as the bleach stabilizer for hydrogen peroxide, and the addition amount thereof is about 0.01 to 5.0% against dry pulp. Is enough. Moreover, it is preferable to perform the dispersion process by the disperser 10 in the range of 20-90 degreeC, PH6-11, More preferably, 60-90 degreeC and PH9-11.

  The pulp soaked in the alkali soaking tower 5 is then fed to the flowator 6, deinked by this flotation treatment, then fed to the dehydrator 7, and dehydrated while supplying shower water 8. The pulp that has been washed and dehydrated and washed is stored in the stock tower 9. It should be noted that deinking can also be performed in the dehydration / washing process instead of deinking with the flowator 6.

  The pulp that has undergone the dehydration / washing process may be fed to a bleaching tank, added with hydrogen peroxide and further bleached, and then stored in the stock tower 9. The amount of hydrogen peroxide added in this bleaching process is, for example, automatically measuring the content of residual hydrogen peroxide in waste paper pulp discharged from the bleaching tank, and automatically controlling the amount of hydrogen peroxide added according to the measurement result. However, it is preferable to control to add the minimum amount of hydrogen peroxide required.

  As described above, by passing through the disaggregation step, the bleaching / soaking step, the floating step and / or the washing step, the whiteness by measurement in accordance with JIS P8148 (using an ISO whiteness meter) is as high as 75 to 87%. Waste paper pulp with whiteness can be produced.

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

Waste magazine paper was fed to the disaggregation step, and disaggregation was carried out with a pulper (manufactured by Aikawa Tekko, high concentration pulper) at a concentration of 18% for 0.5 hours. Next, remove the dust with a screen, add a deinking agent, pass through a flotator, deink, further select with a cleaner,
[Processing conditions]
Pulp concentration: 28%
Alkaline chemical addition amount: Caustic soda 0.4%
Hydrogen peroxide addition amount: 0.9-3.0%
Bleach stabilizer addition amount: Sodium silicate 0.01-5.0%
Surfactant: 0.03%
Temperature and PH: 70 ° C, PH10-11
Disperser treatment was performed.

Next, the pulp slurry that has been subjected to disperser treatment is fed to an alkali soaking tower,
[Processing conditions]
Pulp concentration: 28%
Treatment time: Alkaline soaking treatment was performed in 2 to 5 hours.

  Next, the pulp slurry subjected to the alkali soaking treatment was diluted to a pulp concentration of 1%, subjected to a flotation treatment with a flotator, and the ink was floated and removed, followed by a dehydration treatment.

  Further, as Comparative Examples 3 and 4 corresponding to the conventional examples, the same as above except that 3.5% (Comparative Example 3) and 4.0% (Comparative Example 4) of hydrogen peroxide were added and no bleach stabilizer was added. The deinking agent was added to the pulp slurry immediately before being fed to the alkali soaking tower. The amount of each deinking agent added is all dry pulp%.

  Table 1 shows the results of measurement of the hydrogen peroxide and bleach stabilizer addition amount and whiteness in each of the above Examples and Comparative Examples, and the relative evaluation of economic efficiency based on the hydrogen peroxide addition amount.

なお、表１中の白色度は、ＩＳＯ白色度計を使用して、ＪＩＳ Ｐ８１４８に準じて測定した。

In addition, the whiteness in Table 1 was measured according to JIS P8148 using an ISO whiteness meter.

  In Table 1, from Example 1 to Example 6, by adding the chemical addition place before the disperser, the addition amount of hydrogen peroxide is added in the range of 1.5 to 2.5%, and the bleach stabilizer is also used. It turns out that the waste paper pulp of whiteness of 79% or more can be manufactured by adding in 0.01 to 5.0% of range. It can also be seen that the higher the amount of hydrogen peroxide added, the higher the whiteness is obtained, and the less the influence of the amount of bleach stabilizer added. Further, since the amount of hydrogen peroxide added can be reduced in this way, the economic efficiency is improved.

  On the other hand, when the amount of hydrogen peroxide added is reduced to 0.9% as in Comparative Example 1, the whiteness is reduced to 76.8%, and a whiteness of 77% or more cannot be obtained. When the addition amount is increased to 3.0% as described above, the whiteness becomes 82% or more. However, since the addition amount of hydrogen peroxide is large, the economy is inferior. Further, in Comparative Examples 3 and 4 where the chemical addition place was set before the soaking tower corresponding to the conventional example, the whiteness was 79% by setting the added amount of hydrogen peroxide to 3.5% or 4.0%. Although it can be set to about 0.07 to 99.5%, it can be seen that the obtained whiteness is lower than that of Comparative Example 2 although the economy is remarkably bad.

  In the method for producing waste paper pulp of the present invention, since the chemical is added to the disaggregated pulp as a pretreatment of the soaking treatment and the soaking treatment is performed after the dispersion treatment with the disperser, the chemical penetrates strongly into the disaggregated pulp and the bleaching efficiency is increased. In order to improve, waste paper with high whiteness can be produced at low cost with a small amount of added chemicals, and it is useful for all waste paper pulp and paper products using it.

It is explanatory drawing of the manufacturing method of the used paper pulp in one Embodiment of this invention. It is explanatory drawing of the principal part of the manufacturing method of the used paper pulp of the embodiment. It is explanatory drawing of the principal part of the manufacturing method of the used paper pulp of a prior art example.

Claims (6)

  A disaggregation process that disaggregates and defibrates waste paper, a bleaching and soaking process that adds chemicals to the disaggregated pulp and bleaches and soaks, and a float that dilutes the bleached and soaked pulp and blows bubbles to separate the ink In the method for producing waste paper pulp having a step and / or a washing step for washing pulp, a chemical containing alkaline chemical, deinking agent, hydrogen peroxide and its bleach stabilizer as a pretreatment in bleaching and soaking process A method for producing waste paper pulp, characterized in that after adding and dispersing with a disperser, bleaching and soaking are performed.   The method for producing waste paper pulp according to claim 1, wherein the amount of hydrogen peroxide used in the bleaching and soaking process is 1.0 to 2.5% by weight of dry pulp.   The method for producing waste paper pulp according to claim 1 or 2, wherein an amount of the bleach stabilizer used in the bleaching / soaking step is 0.01 to 5% by weight with respect to dry pulp.   The method for producing waste paper pulp according to any one of claims 1 to 3, wherein the bleach stabilizer is one of sodium silicate and diethylenetriaminepentamethylenephosphoric acid or a mixture of both.   The method for producing waste paper pulp according to any one of claims 1 to 4, wherein the chemical addition in the bleaching and soaking process is performed by both a dispersion treatment by a disperser and a bleaching and soaking treatment.   Waste paper pulp produced by the production method according to any one of claims 1 to 5 and having a whiteness of 77 to 87%.

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