JP6361766B1 - Bacterial spore sterilization method in pulp and paper manufacturing process - Google Patents

Abstract

The present invention provides a sterilization method in a paper pulp manufacturing process that can sufficiently reduce the number of bacteria in the paper pulp manufacturing process and reduce the number of bacteria in the paper product. In the paper pulp manufacturing process, a sterilization method in the paper pulp manufacturing process, in which a halogen-based oxidizing fungicide and a polyalkyleneguanidine compound are added. An example of the halogen-based oxidizing disinfectant is at least one selected from the group consisting of hypochlorous acid, hypochlorite, hypobromite, hypobromite, chlorine dioxide, haloamine, and haloamide. An example of a polyalkylene guanidine compound is polyhexamethylene guanidine. [Selection] Figure 1

Description

  The present invention relates to a sterilization method in a paper pulp manufacturing process, and more particularly to a sterilization method for reducing the number of bacteria in a paper product.

  In the pulp and paper manufacturing process, antibacterial agents are used for several purposes. The most common purpose is to prevent slime from sticking to bacteria and fungi on the walls of the paper and pulp manufacturing process, producing sticky substances, and growing while strewn with dust, forming a sticky mass It is. When slime grows in the process and peels off, it enters the paper product and becomes contaminated with foreign matter, which significantly deteriorates the quality of the paper product. Therefore, an antibacterial agent is added to the papermaking process as a slime control agent for preventing slime. In addition, antibacterial agents are used for the purpose of preventing odors caused by the generation of organic acids through the decomposition and fermentation of starch under anaerobic conditions by bacteria and the deterioration of the quality of formulated chemicals such as paints and starches due to pH reduction. Is used.

  In the pulp and paper manufacturing process, sterilization methods combining various antibacterial materials have been studied. In recent years, inorganic antibacterial agents have become mainstream in slime control, such as in the papermaking process in the pulp and paper industry. This is because it is less expensive than conventional organic antibacterial agents and has excellent sterilization and slime prevention effects. Specific examples of inorganic antibacterial agents include hypochlorites such as sodium hypochlorite, sodium hypobromite, and chlorine dioxide. Recently, hypochlorite and ammonium salts, amines, Reaction products with nitrogen compounds consisting of imines, amides and imides are often used. For example, ammonium bromide, ammonium sulfate, ammonium chloride, ammonium carbamate, urea and sulfamic acid. These are oxidative antibacterial agents that form haloamines and haloamides that are reactively bonded with chlorine in hypochlorite, and exhibit high bactericidal and antiseptic effects and slime control effects. Examples of organic antibacterial agents include isothiazolone compounds (Japanese Patent Laid-Open No. 2002-336867). Further, there is an example in which a synergistic effect is exhibited by using an inorganic antibacterial agent and an organic antibacterial agent in combination, and a higher slime control and antiseptic effect are exhibited (Japanese Patent Laid-Open No. 2002-336867).

In recent years, in addition to slime control, deodorization and antiseptic, it has become necessary to use antibacterial agents for the purpose of hygiene of paper products. In particular, hygiene conditions for paper cups and hand wipes are stricter among paper products, and the number of bacteria in paper products is 2.5E + 02 to 1.0E + 03 (2.5 × 10 ^{2 to} 1.0 × 10 ³ ) CFU. Increasing the upper limit such as less than / g is increasing.

  In the method of using an antibacterial agent for the purpose of normal slime control, the number of bacteria is usually 1.0E + 03 CFU / g or more, and it is necessary to apply a more enhanced antibacterial agent different from slime control. . However, at present, it is not easy to sterilize so as to be surely below the above standard. In particular, in the paper pulp manufacturing process, bacterial spores that have not received much attention are obstacles.

  The bacterial spore is a form in which a specific bacterium such as Bacillus forms a strong shell structure and has extremely high heat resistance and chemical resistance. Usually, bacterial spores do not grow as they are and do not form slime or promote spoilage. Therefore, there is no problem with slime control or antiseptic. However, bacterial spores are difficult to die by the heat and antibacterial agents of dryers in the paper manufacturing process, and are therefore a major obstacle when controlling the number of bacteria in paper products.

  Bacterial spore treatment methods are being studied especially in food handling facilities and cleaning facilities. For example, sterilization with high-pressure steam such as autoclave, treatment at extremely high temperature, or use of glutaraldehyde, peracetic acid, sodium hypochlorite, etc. as a chemical is a kind of bacillus that forms spores. Recommended by the World Health Organization for the disinfection of anthrax (JP 2004-75659). In addition to these general drugs, polyhexamethylene guanidine salts and quaternary ammonium salts are also recommended (Japanese Patent Laid-Open Nos. 2009-108184 and 2006-160245).

  These agents are not sufficiently effective by themselves and are made highly alkaline or contain a surfactant or the like, but these are used as cleaning agents. However, it is not realistic to add such a high-pressure, high-temperature, high-alkali, high-concentration chemical treatment or foaming surfactant in the paper manufacturing process.

  In this way, in the pulp and paper manufacturing process, the application of antibacterial agents based on known slime control and antiseptic technology, in particular, becomes an obstacle to bacterial spores, and sufficiently reduces the number of bacteria in the pulp and paper manufacturing process. It is difficult to reduce the number of bacteria. Furthermore, existing spore processing technology for food and cleaning facilities cannot be applied to the pulp and paper manufacturing process as it is.

JP 2002-336867 A JP 2004-75659 A JP 2009-108184 A Japanese Patent Laid-Open No. 2006-160245

  An object of this invention is to provide the sterilization method in the paper pulp manufacturing process which can fully reduce the number of bacteria in a paper pulp manufacturing process, and can reduce the number of microbes in paper products.

The gist of the present invention is as follows.
[1] A method for sterilizing bacterial spores in a paper pulp manufacturing process in which a halogen-based oxidizing fungicide and a polyalkyleneguanidine compound are added in the paper pulp manufacturing process.

[2] In [1], the halogen-based oxidizing disinfectant is selected from the group consisting of hypochlorous acid, hypochlorite, hypobromite, hypobromite, chlorine dioxide, haloamine, and haloamide. A method for sterilizing bacterial spores in a paper pulp manufacturing process, which is at least one selected and the polyalkyleneguanidine compound is a polyalkylene biguanide.

[3] A method for sterilizing bacterial spores in a paper pulp manufacturing process according to [2], wherein the polyalkylene biguanide is polyhexamethylene biguanide.

[4] In [2] or [3], the haloamine or haloamide is a reaction product of ammonium bromide, ammonium sulfate, ammonium chloride, ammonium carbamate urea or sulfamic acid and hypochlorous acid and / or hypochlorite. A method for sterilizing bacterial spores in a paper pulp manufacturing process.

  According to the present invention, in the pulp and paper manufacturing process, bacterial spores can be sterilized by using a small amount of antibacterial agent without performing high-temperature and high-pressure treatment, and without using a high alkali or surfactant. The number of bacteria in the product can be sufficiently reduced.

It is a block diagram which shows an example of a paper pulp manufacturing process.

  The sterilization method in the paper pulp manufacturing process of the present invention is to add a halogen-based oxidizing fungicide and a polyalkylene guanidine compound in the paper pulp manufacturing process.

[Applicable to]
The application target of the present invention is a paper pulp manufacturing process. As shown in FIG. 1, the paper pulp manufacturing process includes at least the following processes (1) to (4).

(1) Pulp forming step: There are a plurality of methods for producing pulp as a raw material for paper as a final product as follows.
In the pulping process of chemical pulp, usually, wood chips are steamed with alkali in a digester to remove lignin, and further bleached with chlorine dioxide, hydrogen peroxide, ozone or the like to obtain pulp. In a paper mill without such a pulping process, kraft pulp is dehydrated and used as a raw material.
In the case of waste paper pulp, water is added to magazine waste paper or newspaper waste paper to form a slurry that loosens the fibers with a disintegrator (pulpa), then deinked with a deinking agent, and whitened with a bleaching agent. Get ink pulp.
In the case of a pulp sheet, pulp is obtained by simply loosening the fibers of the corrugated cardboard or the like with a disintegrator (pulpa).

(2) Preparation step: A step in which the above-described pulp slurry is modified (beaten) with mechanical force, mixed and then various chemicals are added. The chemicals to be added are fillers that fill the gaps in the pulp and increase the whiteness and opacity, fine fibers and fillers stay on the wire, improve the dehydration, improve the yield and drainage, and blot the paper ink. Water-proofing agent for preventing water, sizing agent, paper strength enhancing agent for enhancing the strength of paper, dye for adjusting color, antifoaming agent for suppressing foaming, slime control agent for preventing slime.

(3) Papermaking process: About 3% of the pulp slurry obtained in the above preparation process is diluted to about 1%. Next, it is sent out to the traveling papermaking wire using a head box and dehydrated. The dehydrated water is called white water and is used for dilution of pulp slurry. In the case of multilayer papermaking, starch slurry is sprayed on each layer of wet paper as an adhesive. The wet paper exiting the wire has a solid content of about 20%, and is then dehydrated to a solid content of about 50% by press dehydration with felt. Next, it is dried to a moisture content of less than 10% by a dryer using steam as a heat source. In addition, a size press process may be provided between the dryer parts. The size press is a method of applying a sizing agent to the paper surface, and is a step of applying a coating liquid containing not only the sizing agent but also a pigment for improving the gloss and smoothness of the paper.

(4) Recovery process: In the paper pulp manufacturing process, in addition to dehydrated water (white water) and excess pulp, paper breakage occurs due to out of paper and poor quality. All of these are reused, and only the remaining part becomes wastewater treatment or waste.

  The processing target of the present invention includes all the steps (1) to (4). By sterilizing and bacteriostatic in all of the bacterial contamination sources and breeding sources, the bacterial count level in the paper product can be sufficiently reduced.

  Specifically, in the pulping step (1), the pulp and bleaching at the time of disaggregation mixed with bacteria are all completed and stored, and in the preparation step (2), all the steps, especially bacteria In the paper-making process (3), the starch-based sizing agent, paper strength improver, and pulp slurry and white water before the paper-making wire, multi-layered adhesive starch, starch-based size starch and coating liquid In the recovery step (4), and the raw materials (calcium carbonate, clay, starch, latex, etc.), all recovered white water and waste paper are targeted.

  In particular, the pulp slurry and white water in the preparation step (2), the paper making step (3), and the recovery step (4) circulate through the white water from which the starch added to each place is recovered. It is easy for bacteria to grow. Depending on the factory, supplementary water such as river water and well water may also be a source of contamination with bacteria.

Bacterial spores are detected at any of these sites, but are often found particularly at the following three sites.
(i) Bringing in from outside: For example, starch or pulp slurry purchased from outside
(ii) Bacterial spores are formed and survived in the starch paste solution that has been subjected to a cooking process in which starch is heated and swollen.
(iii) Tank for storing waste paper slurry and recovered water (recovered water) for a long time. It is presumed that the survival becomes severe and the bacterial spores are formed as the decay progresses.

[Antimicrobial agent]
<Halogen-based oxidizing disinfectant>
Examples of the halogen-based oxidizing disinfectant include hypochlorous acid (salt), hypobromite (salt), and chlorine dioxide. In addition, examples of the halogen-based oxidizing bactericides include ammonium bromide, ammonium sulfate, ammonium chloride, ammonium carbamate, haloamine and haloamide which are a reaction product of urea or sulfamic acid and hypochlorous acid (salt). As the halogen-based oxidizing bactericides, one or more of these are used.

<Polyalkylene guanidine compound>
As the polyalkylene guanidine compound, polyalkylene biguanide or a derivative thereof is preferable, and specifically, polyhexamethylene biguanide (PHMB) is preferable.

[Location of antibacterial agent]
The addition point of the oxidizing bactericide and the polyalkylene guanidine compound need not be the same, and the addition location may be freely determined according to the situation. This is because, in the paper pulp manufacturing process, water and raw materials are circulated, and in particular, the oxidizing disinfectant tends to remain from the addition point to the subsequent process. For example, only an oxidizing bactericide is added to a place where there are almost no bacterial spores, and a polyalkylene guanidine compound is additionally added to a place where there are many bacterial spores downstream.

  As a more specific example, the recovered water of white water is often used as feed water at the time of disaggregation of pulp and broken paper. Here, there are almost no bacterial spores in the recovered water of white water, but if there are many normal bacteria, sterilization and bacteriostasis with a normal oxidizing bactericide is necessary. On the other hand, when there are brought-in spores in the pulp, the oxidizing fungicide alone is not sufficient, and a polyalkyleneguanidine compound is additionally added. However, since the oxidizing disinfectant is mixed into the pulp through the recovered water of white water serving as the feed water, it is not necessary to add it at the time of disaggregation of the pulp unless the residual concentration is extremely reduced.

  On the other hand, the starch slurry and paste liquid processes are basically non-circulating and transient, so when bacterial spores are present, the addition points are at the same or close positions.

[Additive concentration of antibacterial agent]
Since the halogen-based oxidizing disinfectant is generally defined by the effective chlorine concentration, all the halogen-based oxidizing disinfectants are also defined by the effective chlorine concentration in this specification. Normally, halogen-based oxidizing disinfectants often have adverse effects such as corrosion of stainless steel, fading of dyes, and decomposition of polymers when the concentration is excessively high due to its oxidizing power.

  The polyalkylene guanidine compound does not particularly have an adverse effect in the process, but it is more expensive than the halogen-based oxidative fungicide, so that the amount used is preferably as small as possible.

  From the above points and various experimental results, the addition concentration is preferably in the following range.

Halogen-based oxidizing fungicide: 0.1 to 100 mg / L as Cl _2, especially 1.0 to ₂₀ mg / L as Cl ₂
Polyalkylene guanidine compound: 0.1 to 200 mg / L, particularly 1.0 to 50 mg / L

[Method of adding antibacterial agent]
The antibacterial agent may be added either intermittently or continuously. However, since the purpose is to constantly suppress the bacterial count level in the paper product, an addition interval that always keeps chemicals is desirable even with intermittent addition. For example, in the case of batch production such as pulp disaggregation and starch dissolution, it is efficient to add each batch. However, since it may be difficult to control the addition of chemicals linked to the batch, it may be added frequently.

  In the pulp and paper manufacturing process, as described above, water and raw materials are circulated. However, the flow of the circulation and the ratio of circulation / waste water / waste raw materials are completely different for each facility. Although it is difficult to prescribe uniformly, a tank having a long residence time (recovered water tank or waste paper tank) can always keep chemicals even if it is added infrequently.

  The pulper tank and the size circulating fluid need to be added at a high frequency because the residence time is short. In particular, since the halogen-based oxidizing disinfectant is likely to remain until the subsequent process, the halogen-based oxidizing disinfectant added to the white water or the recovered water tank remains in the pulper, so it is not necessary to add it to the pulper. In order to reduce the number of normal bacteria, a halogen-based oxidative fungicide alone can be sufficient. Therefore, it is efficient to add polyalkylene guanidine compounds only in places where many bacterial spores are detected. .

An example of the addition method is given below.
Pulping step: Polyalkylene guanidine compound is added to the pulper tank 24 times / day.
Papermaking process: Polyalkylene guanidine compound and halogen-based oxidative disinfectant in white water tank
Add 12 times / day.
Recovery process: Polyalkylene guanidine compound and halogen-based oxidative disinfectant in the waste paper tank
Add 8 times / day.
Add halogen-based oxidizing disinfectant 8 times / day to the recovered water tank.
Polyalkylene guanidine compound and halogen-based oxidation in size starch charging tank
Batch of fungicide.
The polyalkylene guanidine compound is added 24 times / day to the circulating starch solution.

[Example 1 and Comparative Example 1]
[Preparation of sample for bacterial test]
White water (pH 7.4, temperature 30 ° C., SS concentration 0.1%) was collected from the paper making process of the A factory that manufactures the cup base paper. However, the number of bacterial spores was as small as 7.0E + 01 CFU / ml, and the number of bacterial spores was increased by the following method in order to conduct a bactericidal test.

  General bacteria other than bacterial spores are killed by heating the white water sample at 80 ° C. for 20 minutes, and then mixed with standard agar medium (5 g of meat extract, 10 g of peptone, 1 L of water, 15 g of powdered agar, pH 7). Then, it was left to stand at 30 ° C. for 2 days in a thermostat to obtain bacterial spore colonies. The bacterial spore colony is scraped with a platinum loop, added to a test tube containing 2 ml of a liquid medium excluding the agar of the standard agar medium, and cultured with shaking at 30 ° C. and 80 rpm overnight. Obtained. This bacterial solution was added to 0.01% white water, and the total number of bacteria that had not been heat-treated and the number of bacterial spores that had been heat-treated were measured in the same manner. As a result, the total number of bacteria was 3.0E + 04CFU / ml, 8E + 03 CFU / ml, which was used as a sample for sterilization test.

[Preparation of halogen-based oxidizing bactericides]
The chemicals produced the following BAC and MAC as halogen-based oxidizing disinfectants.
1) Bromine activated chloramine (BAC)
Ammonium bromide aqueous solution diluted to 7,000 mg / L with pure water and sodium hypochlorite aqueous solution prepared with pure water to an effective chlorine concentration of 5,000 mg / L were mixed and reacted at an effective chlorine concentration of 2 500 mg / L bromine activated chloramine (BAC) was obtained.
2) Monochrome lamin (MAC)
Similarly, an aqueous solution of sodium hypochlorite prepared with pure water to an effective chlorine concentration of 5,000 mg / L and an aqueous solution of ammonium sulfate of 5,000 mg / L in a 1: 1 mixture reaction has an effective chlorine concentration of 2500 mg / L. Monochloramine (MAC) was obtained.

[Polyalkylene guanidine compound]
As a polyalkyleneguanidine compound, 20% polyhexamethylene biguanide (PHMB) was obtained from Lonza Japan.

[Sterilization test]
The sterilization test was performed under the condition that the above chemicals were added to the sample together with the halogen-based oxidizing bactericidal agent alone, PHMB alone, or both. Each chemical was added to the white water sample heated to a temperature of 30 ° C. while stirring and contacted with shaking at 80 ° C. for 30 minutes at 30 ° C. Next, as in the preparation of the sample, the total number of bacteria and the number of bacterial spores were measured.

  Table 1 shows the test results using BAC and PHMB, and Table 2 shows the test results using MAC and PHMB.

<Discussion>
As shown in Tables 1 and 2, when looking at the total drug concentration, the number of spore bacteria is reduced at a lower concentration in BAC alone or in combination with PHMB alone than in PHMB alone, and as a result, a reduction in the total number of bacteria is observed. . Although it cannot be generally stated, in order to fall below 2.5E + 02 CFU / ml as the standard for the number of bacteria in paper products, the total number of bacteria and the number of spore bacteria must be at least less than 1.0E + 02 CFU / ml. In this test, BAC alone required 20 mg / L, and PHMB and MAC alone could not drop below 1.0E + 02 CFU / ml even at 20 mg / L. On the other hand, by using BAC and PHMB or MAC and PHMB in combination, the total concentration of BAC or MAC and PHMB can be said to satisfy the standard at 10 mg / L.

[Example 2]
[Preparation of sterilization test sample]
Manufacture of hand-wiped paper The starch powder for size of Factory B was collected, and 10% (w / w) starch slurry was prepared with sterilized water. When the total number of bacteria and the number of bacterial spores were measured in the same manner as in Example, the total number of bacteria was 2.5E + 05 CFU / ml, and the number of bacterial spores was 8.2E + 03 CFU / ml.

[Antimicrobial agent]
As the antibacterial agent, the same BAC and PHMB as in Example 1 were used.

[Sterilization test]
The same test as in Example 1 was performed using BAC and PHMB. The results are shown in Table 3.

<Discussion>
In the case of starch slurry, unlike white water, the SS concentration is high, and the number of bacteria cannot be measured without dilution, so the lower limit of measurement was 10 CFU / ml. As a result, as in Example 1, it was confirmed that by using BAC and PHMB in combination, the number of spore bacteria was reduced and the total number of bacteria was reduced at a low addition concentration. In order to fall below the total number of bacteria 1.0E + 02CFU / ml, (BAC) alone required 32 mg / L, and PHMB alone could not fall below 16 mg / L. On the other hand, by using together, it was able to fall below 1.0E + 02CFU / ml at the total concentration of 12 mg / L.

Claims (4)

A method for sterilizing bacterial spores in a paper pulp manufacturing process, wherein a halogen-based oxidizing fungicide and a polyalkyleneguanidine compound are added in the paper pulp manufacturing process. 2. The halogen-based oxidizing disinfectant according to claim 1, wherein the halogen-based oxidative disinfectant is at least selected from the group consisting of hypochlorous acid, hypochlorite, hypobromite, hypobromite, chlorine dioxide, haloamine, and haloamide. One kind,
A method for sterilizing bacterial spores in a paper pulp manufacturing process, wherein the polyalkyleneguanidine compound is a polyalkylene biguanide. The method for sterilizing bacterial spores according to claim 2, wherein the polyalkylene biguanide is polyhexamethylene biguanide. 4. Paper pulp production according to claim 2, wherein the haloamine or haloamide is a reaction product of ammonium bromide, ammonium sulfate, ammonium chloride, ammonium carbamate urea or sulfamic acid with hypochlorous acid and / or hypochlorite. A method for sterilizing bacterial spores in the process.

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