JP2005290617A - Method for controlling slime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling slime with which slime preventing effects are great and the running cost is low at small expenses for ensuring working environments. <P>SOLUTION: A bleached pulp slurry 1 is stored in a mixing chest 2 once and a deinked pulp slurry 4 is stored in a pulp chest 5, then transferred to the mixing chest 2 and stored therein. Sodium hypochlorite is fed to the pulp chest 5 and 3-bromo-3-chloro-5,5-dimethylhydantoin is fed to a machine chest 7 and a white water silo 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a papermaking water-based slime control method in a paper mill. This method is suitable for use in a papermaking process water system in which waste paper or newspaper is collected and mixed with raw pulp to produce paper.

  In a papermaking process water system in a paper mill, a viscous material called slime may be formed. This slime is generated due to the propagation of microorganisms such as filamentous fungi and bacteria, and causes various troubles in the paper making process.

  For example, slime adheres to a storage pit for storing pulp slurry, a white water pit, a flow box, a transportation pipe, and the like, which deteriorates the flow of white water or causes metal corrosion.

  Also, when the slime adhering to the white water pits grows to a certain extent, a part of the slime peels off the wall surface and floats in the white water, and is mixed in the paper made in the paper making process and is present in the paper called deposit It becomes a foreign object. This deposit causes coloring, spots, and the like on the surface of the paper, which significantly reduces the product value of the paper. Furthermore, the deposit causes a decrease in the strength of the paper, causing the paper to break from the deposit while the paper is being wound at a high speed, and the paper production is temporarily stopped, resulting in a great loss. It will be.

  For this reason, conventionally, the slime control agent which consists of an organic halogen microbicide is added with respect to a papermaking process water system, and generation | occurrence | production of slime is performed (for example, refer patent document 1).

JP 10-17413 A (second page)

  Organic halogen microbicides gradually generate hypohalous acid in water, and the microbicidal effect is exhibited by this hypohalous acid. For this reason, organic halogen microbicides have a microbicidal effect that lasts longer than when hypohalite is used as a microbicide. Even in this place, the microbicidal effect can be exerted evenly. In addition, since organic halogen microbicides are less corrosive to metals than hypohalites, the durability of the entire papermaking process water system can be extended.

  However, since organic halogen microbicides have a slow-acting microbicidal effect, if the number of microorganisms is large in the papermaking process water system, a sufficient microbicidal effect may not be exhibited.

  In addition, organic halogen microbicides are more expensive than hypohalites and have a problem of increased running costs.

  The present invention has been made in view of the above-described conventional situation, and it is an object to be solved to provide a slime control method that can exhibit an excellent slime prevention effect and has a low running cost.

  In order to solve the above-mentioned problems, the inventors paid attention to a recovered pulp slurry made of deinked pulp from which waste paper or newspaper was recovered. That is, in the paper mill, if the paper made in the paper making process has dirt or missing parts, it is recovered as waste paper and mixed with water again to make a recovered pulp slurry of 3-5% concentration. Mixed and reused. In addition, old newspaper is made into deinked pulp by removing ink components, and then mixed with raw material pulp and reused. Since these recovered pulp slurries contain a large amount of organic matter (for example, organic matters such as starch, casein, sizing agent, and lignin derived from wood) that are nutrient sources for microorganisms, microorganisms such as filamentous fungi and bacteria Will be easier to breed. Moreover, since the time for which the recovered pulp slurry stays in the storage tank is usually as short as 1 hour to several hours, the recovered pulp slurry is stored before the microbicidal effect is exhibited when the organic halogen microbicide is used. Get out of the tank. For this reason, it was thought that slime generation can be effectively prevented by using a hypohalite having an immediate effect on the recovered pulp slurry.

  That is, the slime control method of the present invention comprises a recovered pulp slurry containing at least one of waste paper and deinked pulp and a raw pulp slurry to form a mixed pulp slurry, and a slime in a papermaking process for papermaking the mixed pulp slurry. In the control method, hypohalite is used as a slime control agent of the recovered pulp slurry, and after mixing the recovered pulp slurry and the raw pulp slurry, an organic halogen microbicide is used as the slime control agent. It is characterized by that.

  In the slime control method of the present invention, a rapid-acting hypohalite is used as a slime control agent for recovered pulp slurry containing at least one of waste paper and deinked pulp. For this reason, the microorganisms in the recovered pulp slurry containing a large amount of organic substances serving as nutrient sources for microorganisms can be reduced in a short time, and slime generation can be effectively prevented. In addition, since the hypohalite is less expensive than the organic halogen microbicide, the running cost is low.

  Further, after treating the recovered pulp slurry with hypohalite and mixing with the raw pulp slurry to obtain a mixed pulp slurry, a slow-acting organic halogen microbicide is used as a slime control agent. For this reason, the microbicidal effect lasts for a long time, and the microbicidal effect can be exerted evenly at any location of the circulating papermaking process water.

  Therefore, according to the slime control method of the present invention, an excellent slime prevention effect can be exhibited, and the running cost can be reduced.

  Hypohalite is one selected from sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, bleached powder, sodium hypobromite, potassium hypobromite and calcium hypobromite This can be done. Among these, hypochlorite has a low price, so that the running cost can be further reduced.

  Organic halogen microbicides include a type that gradually generates hypohalous acid in water and a type that does not generate hypohalous acid in water.

  Examples of types that gradually generate hypohalous acid in water include halogenated hydantoins and halogenated isocyanuric acids. Specific examples of halogenated hydantoins include 3-bromo-3-chlorohydantoin, 3-bromo-3-chloro-5,5-dimethylhydantoin, 3-bromo-3-chloro-5,5-diethylhydantoin, 3, Examples include 3-dichloro-5,5-dimethylhydantoin, 3,3-dibromo-5,5-dimethylhydantoin, and 3,3-dichloro-5,5-dimethylhydantoin. Specific examples of the halogenated isocyanuric acid include trichloroisocyanuric acid, dichloroisocyanuric acid, sodium dichloroisocyanurate, and disodium chloroisocyanurate.

  These halogenated hydantoins and halogenated isocyanuric acids are hydrolyzed in water to be in equilibrium with hypohalous acid. The resulting hypohalous acid is consumed by acting as a microbicide. Furthermore, in order to maintain an equilibrium state, the halogenated isocyanuric acid and the halogenated hydantoin are hydrolyzed, and the consumed amount of hypohalous acid is replenished. For this reason, hypohalous acid is gradually released as necessary, and the microbicidal effect is sustained.

  On the other hand, types that do not generate hypohalous acid in water include halogenated nitroamide-based 2,2-dibromo-3-nitrilopropionamide (DBNPA); halogenated nitroalcohol-based 2-bromo-2-nitro-1 , 3-propanediol (BNPD), 2,2-dibromo-2-nitroethanol (DBNE), 1,1-dibromo-1-nitro-2-propanol (DNBP); 1,4-halogenated carboxylic acid-based 1,4- Bis (bromoacetoxy) -2-butene (BBAB), 1,4-bis (bromoacetoxy) -2-ethene (BBAE), 2-bromo-2-nitro-1,3-diacetoxypropane (MAC); halogen Phthalonitrile-based 5-chloro-2,4,6-trifluoro-isophthalonitrile (CTF); Nate (MBTC), 4,5-dichloro-1,2-dithiol-3-one (DDO), 1,2-benzisothiazolin-3-one (BIT), 5-chloro-2-methylisothiazolin-3-one (CMIT), 2-methylisothiazolin-3-one (MIT), and the like.

  Among the above organic halogen microbicides, it is preferable to use a halogenated hydantoin and / or a halogenated isocyanuric acid. These compounds are relatively excellent in bactericidal activity among organic halogen microbicides, have weak skin irritation, and are inexpensive.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Embodiments of the invention will be described below with reference to the drawings.

  The slime control method of the embodiment is for preventing slime generation in the papermaking process water in a paper mill that produces neutral coated paper from bleached kraft pulp and deinked pulp. The deinked pulp may contain neutral coat waste paper.

  The papermaking process water system in this paper mill circulates as follows. That is, as shown in FIG. 1, the bleached pulp slurry 1 supplied through the cooking process and the bleaching process is once stored in the mixing chest 2. The deinked pulp slurry 4 supplied from the pulper 3 is stored in the pulp chest 5 and then transferred to the mixing chest 2.

  The papermaking process water system in this paper mill circulates as follows. That is, the bleached pulp slurry 1 supplied through the cooking step and the bleaching step is once stored in the mixing chest 2. The deinked pulp slurry 4 supplied from the pulper 3 is stored in the pulp chest 5 and then transferred to the mixing chest 2.

  Thus, the mixed pulp slurry 6 in which the bleached pulp slurry 1 and the deinked pulp slurry 4 are mixed further flows from the stock inlet 9 onto the wire 10 via the machine chest 7 and the seed box 8. Pulp is made on the wire 10, and the white water flowing downward from the gap of the wire 10 is collected by the saveall 11 and collected in the white water silo 12.

  Further, the white water collected in the white water silo 12 is returned to the mixing chest 2. On the other hand, the wet paper on the wire 10 is dehydrated in the press part 13.

  The slime control agent was added in the pulp chest 5, machine chest 2, and white water silo 12 to the papermaking process water circulating as described above.

Example 1
In Example 1, a sodium hypochlorite aqueous solution having a residual chlorine concentration of 12% was added from the chemical supply device 15 to the pulp chest 5 at a flow rate of 200 g / min for 15 minutes 6 times a day. Further, 3-bromo-3-chloro-5,5-dimethylhydantoin was added from the drug supply device 16 to the machine chest 7 at a flow rate of 200 g / min for 15 minutes 6 times a day. Further, 3-bromo-3-chloro-5,5-dimethylhydantoin was added from the drug supply device 17 to the white water silo 12 at a flow rate of 300 g / min for 15 minutes 6 times a day.

(Example 2)
In Example 2, the sodium hypochlorite aqueous solution having a residual chlorine concentration of 12% was added from the chemical supply device 15 to the pulp chest 5 at a flow rate of 200 g / min for 20 minutes four times a day. Further, 5-chloro-2-methylisothiazolin-3-one (CMIT) was added from the drug supply device 16 to the machine chest 7 at a flow rate of 150 g / min for 15 minutes four times a day. Further, 2,2-dibromo-3-nitrilopropionamide (DBNPA) was added from the drug supply device 17 to the white water silo 12 at a flow rate of 150 g / min for 15 minutes four times a day. To 4,5-dichloro-1,2-dithiol-3-one (DDO) at a flow rate of 100 g / min for 15 minutes was added four times a day.

(Example 3)
In Example 3, the sodium hypochlorite aqueous solution having a residual chlorine concentration of 12% was added from the chemical supply device 15 to the pulp chest 5 at a flow rate of 250 g / min for 15 minutes four times a day. In addition, 2,2-dibromo-3-nitrilopropionamide (DBNPA) was added from the drug supply device 16 to the machine chest 7 at a flow rate of 150 g / min for 15 minutes four times a day. Further, 3-bromo-3-chloro-5,5-dimethylhydantoin was added from the drug supply device 17 to the white water silo 12 at a flow rate of 300 g / min for 15 minutes four times a day.

(Comparative Example 1)
In Comparative Example 1, 2,2-dibromo-3-nitrilopropionamide (DBNPA) was added from the drug supply device 15 to the pulp chest 5 at a flow rate of 250 g / min for 15 minutes three times a day. Further, 5-chloro-2-methylisothiazolin-3-one (CMIT) was added from the drug supply device 16 to the machine chest 7 at a flow rate of 200 g / min for 15 minutes three times a day. Further, 2,2-dibromo-3-nitrilopropionamide (DBNPA) was added from the drug supply device 17 to the white water silo 12 at a flow rate of 200 g / min for 15 minutes three times a day. To 4,5-dichloro-1,2-dithiol-3-one (DDO) at a flow rate of 150 g / min for 15 minutes was added three times a day.

(Comparative Example 2)
In Comparative Example 1, 5-chloro-2-methylisothiazolin-3-one (CMIT) was added from the drug supply device 15 to the pulp chest 5 at a flow rate of 200 g / min for 20 minutes four times a day. Also, 2,2-dibromo-3-nitrilopropionamide (DBNPA) was added from the drug supply device 16 to the machine chest 7 at a flow rate of 150 g / min for 20 minutes four times a day. To machine chest 7 was added 4,5-dichloro-1,2-dithiol-3-one (DDO) at a flow rate of 100 g / min for 20 minutes four times a day. Further, 1,4-bis (bromoacetoxy) -2-butene (BBAB) was added from the drug supply device 17 to the white water silo 12 at a flow rate of 150 g / min for 20 minutes four times a day.

  About the said Examples 1-3 and the comparative examples 1 and 2, the number of bacteria of the pulp slurry before the machine chest 7, the number of bacteria in the white water of the white water pit 11 under the wire, and the number of paper spots (paper piece width 1 m × length Table 1 shows the results of measuring the number of spots generated at 1000 m.

  From Table 1, in Examples 1-3 which added sodium hypochlorite to the pulp chest 5, compared with the comparative examples 1 and 2 which added the organohalogen-type microbicide to the pulp chest 5, it is fungi | strain in any place. It can be seen that the number is small and the number of printed spots is small.

  From the above results, in the slime control methods of Examples 1 to 3, the deinked pulp slurry 4 that contains abundant nutrients necessary for microorganisms and is easy to generate slime has a high immediate effect on sodium hypochlorite. Since it was supplied, it turned out that generation | occurrence | production of slime can be prevented effectively. Moreover, since the price of sodium hypochlorite is low, the running cost is also low. Furthermore, since sodium hypochlorite is not very irritating to odors and mucous membranes, no special facilities are required to ensure a working environment.

  In addition, after the strong microbicidal action on the deinked pulp slurry 4 is made by sodium hypochlorite, the microbicidal action is carried out by the slow-acting organic halogen microbicide, so that the microbicidal effect is sustained and circulated. It was found that the microbicidal effect can be exerted evenly at any location of the paper making process water.

  The present invention can be suitably used for controlling a papermaking water-based slime in a paper mill.

It is a conceptual diagram of the papermaking process in embodiment.

Explanation of symbols

4. Deinked pulp slurry (recovered pulp slurry)
1 ... Bleached pulp slurry (raw pulp slurry)
6 ... mixed pulp slurry 3 ... pulper 5 ... pulp chest 7 ... machine chest 12 ... white water silo 15, 16, 17 ... chemical supply device

Claims (3)

In the slime control method in the paper making process of making the mixed pulp slurry by mixing the recovered pulp slurry containing at least one of the waste paper and the deinked pulp and the raw pulp slurry, and making the mixed pulp slurry,
A hypohalite is used as the slime control agent of the recovered pulp slurry, and an organic halogen microbicide is used as the slime control agent after mixing the recovered pulp slurry and the raw pulp slurry. How to control slime.   Hypohalite is one selected from sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, bleached powder, sodium hypobromite, potassium hypobromite and calcium hypobromite The slime control method according to claim 1, which is as described above.   3. The slime control method according to claim 1, wherein the organic halogen microbicide is a halogenated hydantoin and / or a halogenated isocyanuric acid.

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