JP2017190303A - Microorganism suppression method of cooling water system and coating method of coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of suppressing proliferation of microorganism in a cooling water system and a coating method of a coating agent.SOLUTION: There is provided a method for suppressing proliferation of microorganism in a liquid contact part contacting with cooling water of cooling water system 4 having a cooling tower 10, an antimicrobial coated film is formed on the liquid contact part by coating the liquid contact part with a coating agent containing at least hardly water-soluble polycarboxylic acid ion complex formed from polycarboxylic acid and cationic antimicrobial agent so that coated amount of the cationic antimicrobial agent is 0.05 mmol to 10 mmol per 1 cm. Thereby not only corrosion of the liquid contact part can be suppressed, but also microorganism in the cooling water system can be suppressed for long time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for suppressing microorganisms in a cooling water system including a cooling tower, and a method for applying a coating agent used for suppressing microorganisms.

  In the cooling water system of various factory facilities, when microbial slime is generated in the system, slime troubles such as a decrease in the heat efficiency of the heat exchanger, blocking of the cooling water piping, and corrosion of piping metal materials occur. Therefore, drugs that suppress the growth of causative microorganisms have been proposed as so-called slime control agents, which include organic bromine, thiocyanate, dithiol, cyclic nitrogen sulfur, isothiazoline, quaternary. Ammonium salt systems are known.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-292405) proposes an aqueous dispersion or block-shaped slime control agent comprising a quaternary ammonium salt of boron tetrafluoride. Patent Document 1 also discloses a composition containing a polycarboxylic acid, but this polycarboxylic acid is only used as a scale dispersant.

  Patent Document 2 (Japanese Patent Laid-Open No. 2003-286112) discloses a sustained-release antibacterial agent containing a quaternary ammonium salt such as benzalkonium chloride or benzethonium chloride. However, this sustained-release antibacterial agent only controls the elution rate of the quaternary ammonium salt by protecting the inner layer of the quaternary ammonium salt with an outer layer containing a water-soluble substance and a synthetic resin.

  The sustained-release antibacterial agent with this structure has a complicated coating process, and the quaternary ammonium salt itself is water-soluble and the amount of elution into water is not constant. This requires a complicated replacement of the sustained-release antibacterial agent.

  As another antibacterial agent, for example, Patent Document 3 (2014-122203) discloses a polyglutamate ion complex formed from a cationic fungicide such as poly-γ-glutamic acid and quaternary ammonium, and the like. The antifungal agents used as well as the coating agents are disclosed. Patent Document 4 (Japanese Patent Laid-Open No. 2015-163686) discloses a polyacrylic acid ion complex formed from polyacrylic acid and quaternary ammonium ions, and an antibacterial plastic material using the same. However, in these patent documents 3 and 4, there is no description regarding slime suppression in a cooling water system or the like.

JP 2003-292405 A JP 2003-286112 A JP 2014-122203 A JP-A-2015-163686

  The “cooling water system” is a water-cooling type cooling facility having a cooling tower, and is a facility having not only the cooling tower but also related devices (parts) such as a refrigerator, a circulation pump, and piping. In the cooling tower (cooling tower), in order to evaporate the cooling water, it is brought into contact with the atmosphere. At that time, since the water scatters in the form of a mist (aerosol), not only the part that directly contacts the cooling water, The surrounding area gets wet with cooling water.

  Microorganisms such as algae, bacteria, and fungi grow on the wetted parts (wetted parts), and slime (biofilm) is easily formed. Causes slime disorders such as obstruction. In addition, when the wetted part is made of metal, corrosion troubles such as rust, cracks, pitting corrosion and the like also occur.

  In addition, harmful microorganisms such as Legionella bacteria may propagate (symbiotic) on the slime, so that the control of cooling water microorganisms is important in terms of safety.

  In addition to the above-mentioned Patent Document 2, a method of adding a slime control agent to cooling water is known, but in order to maintain an effective concentration for inhibiting reproduction, it is necessary to add the slime control agent continuously or periodically. In addition, the cost is high and the microorganism is constantly exposed to the drug, so the microorganism may acquire drug resistance.

  Moreover, since most of the existing slime control agents use halogen ions such as chlorine and bromine as counter ions, the slime control agent itself may cause corrosion of metal equipment and piping. Moreover, since the quaternary ammonium salt easily foams, there has been a problem that its use and the like are limited.

  The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a cooling water-based microorganism suppression method capable of maintaining a microorganism suppression effect for a long time while preventing corrosion of metals and the like, and an application related thereto. It is in providing the coating method of an agent.

  In order to solve the above problems, the present invention can be configured as follows.

(1) The present invention relates to a method for suppressing the growth of microorganisms in a cooling water system having a cooling tower, and in particular, in the cooling water system, the microorganisms are suppressed in a portion (wetted part) in contact with the cooling water used in the cooling tower. A coating agent containing at least a poorly water-soluble polycarboxylic acid ion complex formed from a polycarboxylic acid and a cationic bactericidal agent, and having a cationic bactericidal agent amount of 0.05 nmol or more per 1 cm ^{2 of} wetted part It is characterized by being applied to the wetted part so as to be 10 nmol or less, and forming a bactericide film on the wetted part.

  (2) The polycarboxylic acid can be selected from the group consisting of poly-γ-glutamic acid, polyacrylic acid, polymethacrylic acid, and a copolymer of methacrylic acid and acrylic acid.

  (3) The cationic fungicide can be selected from one or both of a quaternary ammonium salt and a biguanide fungicide.

  (4) As the quaternary ammonium salt, any one or more selected from the group consisting of cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, and laurylpyridinium chloride can be selected.

  (5) As the biguanide fungicide, one or both of chlorhexidine hydrochloride and chlorhexidine gluconate can be selected.

  (6) The coating agent is preferably adjusted so that the content of the polycarboxylic acid ion complex is 0.1 w / v% or more and 30 w / v% or less.

  Furthermore, the present invention also includes the following coating method.

(7) The coating method of the present invention is a cooling water disinfectant (coating agent) used for suppressing the growth of microorganisms in a wetted part of a cooling water system having a cooling tower and in contact with cooling water, A coating agent containing 0.1 w / v% or more and 30 w / v% or less of a poorly water-soluble polycarboxylic acid ion complex formed from a carboxylic acid and a cationic fungicide is applied to the wetted part at least once. , A method for forming a bactericidal agent film containing 0.05 to 10 nmol of the cationic bactericidal agent per 1 cm ² .

  Note that w / v% means mass / volume%, that is, g / 100 ml.

  Since the present invention uses a poorly water-soluble polycarboxylic acid ion complex formed from a polycarboxylic acid and a cationic bactericidal agent as a coating agent, corrosion of the wetted part and foaming of the bactericidal agent are remarkably reduced. It is possible to maintain the effect of suppressing the growth of

FIG. 1 is a flowchart for explaining the outline of the present invention. FIG. 2 is a schematic diagram illustrating an example of a cooling tower. FIG. 3 is a schematic diagram illustrating an example of a cooling water system. FIG. 4 (a) is a photograph immediately after applying the coating agent of Example 1 to the cleaned louver part, and FIG. 4 (b) is a photograph after 6 months of water flow. Fig.5 (a) is a photograph immediately after apply | coating the coating agent of Example 2 to the louver part after washing | cleaning, FIG.5 (b) is a photograph after 6 months of water flow. FIG. 6 (a) is a photograph immediately after washing the louver part, and FIG. 6 (b) is a photograph after passing water in June without a disinfectant coating. FIG. 7 is a photograph explaining the simulated cooling tower used in the experiment.

  Hereinafter, the present invention will be specifically described, but the present invention is not limited to a specific example.

  The present invention relates to a method for suppressing the growth of microorganisms and a method for applying a coating agent used therefor, to apply a coating agent to form a bactericide film, and to use the bactericide film for the suppression of microorganisms (FIG. 1). .

  First, a specific example of the coating agent will be described.

[Coating agent]
The coating agent contains a polycarboxylic acid ion complex as an essential component. The polycarboxylate ion complex is a poorly water-soluble or water-insoluble substance formed by mixing a polycarboxylic acid and a cationic fungicide in a solvent or the like. In addition, slightly water-soluble (water-insoluble) means that the solubility in distilled water at 25 ° C. is less than 10 g / L, preferably less than 1 g / L.

(Polycarboxylic acid)
A polycarboxylic acid is an organic compound having two or more carboxyl groups in the molecule. Although the kind of polycarboxylic acid used for this invention is not specifically limited, Poly-gamma-glutamic acid, polyacrylic acid, and polymethacrylic acid are suitable. Moreover, the copolymer of acrylic acid and methacrylic acid may be sufficient.

  The molecular size of the polycarboxylic acid to be used is not particularly limited, but in the case of poly-γ-glutamic acid, the average molecular weight is preferably 10 kDa or more, and more preferably 100 kDa or more. In general, the larger the molecular size, the higher the performance such as strength. On the other hand, polycarboxylic acids having an excessively large molecular size are expensive to produce and may be technically difficult to produce. In addition, the average molecular weight of poly-γ-glutamic acid can be referred to a catalog value when a commercially available product is used in addition to a value measured by gel filtration chromatography or the like.

  Although the manufacturing method of polyglutamic acid is not specifically limited, For example, the method disclosed by Unexamined-Japanese-Patent No. 2014-122203 is employable.

  When polyacrylic acid (homopolymer or copolymer of acrylic acid), polymethacrylic acid (homopolymer or copolymer of methacrylic acid), and a copolymer of acrylic acid and methacrylic acid are used as polycarboxylic acid The viscosity average molecular weight is preferably 100,000 or more and 1,000,000 or less.

  When the viscosity average molecular weight is less than 100,000, the strength of the formed ion complex becomes low, and it becomes difficult to form the ion complex alone such as heat forming. On the other hand, when the viscosity average molecular weight exceeds 1,000,000, the solubility is lost and spraying and coating (coating) cannot be performed, and the moldability (uniformity of the coating film) is deteriorated due to gelation.

  The viscosity average molecular weight is more preferably 150,000 or more, more preferably 200,000 or more, still more preferably 300,000 or more, particularly preferably 400,000 or more, more preferably 900,000 or less, 800, 000 or less is more preferred, 700,000 or less is more preferred, 600,000 or less is even more preferred, and 500,000 or less is particularly preferred.

  Viscosity average molecular weight is the average molecular weight obtained from the viscosity of the polymer. Normally, the viscosity average molecular weight of the polymer is measured by measuring the intrinsic viscosity [η] of a standard sample whose molecular weight is known and the intrinsic viscosity of the sample whose molecular weight is to be obtained. Is what you want. In this invention, it uses as a reference | standard of the molecular weight of the copolymer of polyacrylic acid, polymethacrylic acid, and the copolymer of polyacrylic acid and polymethacrylic acid.

  As these poly (meth) acrylic acids, for example, poly (meth) acrylic acid or a salt thereof described in JP-A-2015-163686 can be used.

  When any of the above polycarboxylic acids is used, a slightly water-soluble ion complex obtained after mixing with the following cationic bactericidal agent is used. The polycarboxylate ion complex can be produced by a known method. For example, it can be produced by the methods described in JP-A-2014-122203 and JP-A-2015-163686. More specifically, an aqueous solution or dispersion of polycarboxylic acid is prepared, and if necessary, pretreatment such as neutralization is performed on this solution, and it is mixed with a cationic bactericidal aqueous solution to form a poorly soluble polycarboxylic acid ion. Precipitate the complex. In addition, when there is a high possibility that water-soluble materials such as low-molecular carboxylic acids (water-soluble) are mixed after production, for example, the slightly water-soluble material should be separated from the aqueous dispersion by filtration or the like. You can also.

(Cationic fungicide)
The cationic fungicide used in the present invention ionically bonds with the carboxyl group of the polycarboxylic acid to form a complex. Although the kind is not specifically limited, Use of any one or both of a quaternary ammonium salt and a biguanide type fungicide is preferable.

  Examples of quaternary ammonium salts include cetylpyridinium chloride, benzethonium chloride, distearyldimethylammonium chloride, stearyldimethylbenzylammonium chloride, stearyltrimethylammonium chloride, lauryltrimethylammonium chloride, laurylpyridinium chloride, benzalkonium chloride, and dichloride chloride. Examples include decyldimethylammonium. Examples of the biguanide fungicide include chlorhexidine hydrochloride, chlorhexidine acetate, chlorhexidine gluconate, alexidine hydrochloride, alexidine acetate, and alexidine gluconate.

  Among these, cetylpyridinium chloride, benzethonium chloride, benzalkonium chloride, laurylpyridinium chloride, chlorhexidine hydrochloride, and chlorhexidine gluconate are preferable. Only 1 type may be used for these cationic disinfectants, and 2 or more types may be used for them.

(Coating agent adjustment)
As the coating agent used in the present invention, a solution in which a polycarboxylic acid ion complex is dissolved or dispersed in an organic solvent can be used.

  As the organic solvent, one or more of the group consisting of alcohols, hydrocarbons, ketones and esters can be used, but from the viewpoint of safety in handling and consideration for the environment, methyl alcohol, ethyl alcohol, Alcohols such as propyl alcohol are preferred, and ethyl alcohol is more preferred. Further, a mixed solution of ethyl alcohol and water may be used.

  The content concentration of the polycarboxylic acid ion complex in the coating agent is preferably 0.1 w / v% (mass / volume%) or more and 30 w / v% or less, more preferably 0.5 w / v% or more and 20 w / v% or less. preferable.

  When the content concentration of the polycarboxylic acid ion complex is less than 0.1 w / v%, it is necessary to repeat the coating / drying process until the predetermined concentration is reached, which is not preferable because the operation time becomes long. On the other hand, if it exceeds 30 w / v%, the viscosity of the coating agent becomes high and unevenness of the coating occurs, which is not preferable.

  One or more additives such as dyes, pigments, other preservatives, viscosity modifiers, coupling agents, and pH adjusters (acids, alkalis) may be added to the coating agent.

  Next, the application target of the coating agent will be described.

  The object of microorganism suppression in the present invention is a cooling water system having a cooling tower, particularly a member (part, device) that comes into contact with the cooling water used in the cooling tower.

[cooling tower]
The type of the cooling tower 10 is not particularly limited, and is not particularly limited, such as a closed type, an open type, a cross flow type, and a counter flow type, but an example thereof will be described below.

  2 is a schematic diagram showing a cooling tower, and the cooling tower 10 includes a main body 11 and a blower 21 attached to the main body 11. An opening (ventilation port) is formed on the side wall of the main body 11. When the blower 21 is operated, air is discharged from the main body 11, the internal pressure is negatively inclined, and the outside air is drawn from the vent hole.

  A shielding member such as a louver 19 is installed at the vent, and rainwater, dust, and the like are blocked by the louver 19, but outside air flows into the main body 11 through a gap between the louvers 19.

  A filler 25 is disposed inside the main body 11, and the inflowing outside air passes through the filler 25 and is discharged from the blower 21 to the outside again. That is, an air flow through the filler 25 is generated inside the main body 11.

  The main body 11 is provided with watering means 30. The watering means 30 includes a watering tray 31 installed on the ceiling of the main body 11 and water supply means for supplying cooling water to the watering tray 31. Although a water supply means is not specifically limited, For example, it has the piping 33 embed | buried under the partition member 32 (watering bar) etc. of the watering tray 31, and cooling water is supplied to the watering tray 31 from this piping 33. A plurality of through holes are formed in the watering tray 31. The cooling water passes through the through holes and falls into the main body 11. The cooling water is sprinkled on the filler 25, and the cooling water passes through the filler 25. Fall.

  In the case of a cross flow type (cross flow type) cooling tower, air flows from the side wall of the main body 11 in a lateral direction, that is, substantially orthogonal to the cooling water dropping direction. On the other hand, in the case of a counterflow type (counter flow type) cooling tower, air flows from the lower part of the main body 11 to the upper part, that is, facing the falling cooling water. In either case, the cooling water comes into contact with air and at least a part of it evaporates.

  In the case of a hermetic cooling tower, piping is embedded in the filler 25. Cooling water different from the cooling water flows through the pipe, and the cooling water is cooled by heat of vaporization when the cooling water evaporates.

  On the other hand, in the case of an open type cooling tower, excessive cooling water itself that passes through the filler 25 without being evaporated becomes cooling water and is cooled by heat of vaporization during evaporation.

  In the case of an open type cooling tower, the cooling water that has passed through the filler 25 is sent to a cooling device, which will be described later, as cooling water, and then returns to the cooling tower 10 and sprayed onto the filler 25 again. On the other hand, in the case of a closed type cooling tower, the cooling water is sprinkled again into the filler 25 by the sprinkling means 30, while the water to be cooled is sent to the cooling device and then returns to the cooling tower 10 again to fill the filler 25. Cooled within.

  In other words, the water to be cooled circulates between the cooling tower 10 and the cooling device in both the closed type and the open type cooling towers.

  Next, the whole cooling water system including the cooling tower 10 will be described.

[Cooling water system (cooling equipment)]
Although the cooling water system 4 is not specifically limited, For example, in addition to the cooling tower 10, it has the cooling device 50 and the cooling water circulation system 40 which circulates to-be-cooled water between the cooling tower 10 and the cooling device 50.

  The cooling water circulation system 40 has a flow path 41 such as a pipe and a liquid feeding means 42 such as a pump, and the water to be cooled passes through the flow path 41 and is fed to the cooling device 50 by the liquid feeding means 42 and then again. Return to the cooling tower 10.

  The cooling device 50 includes a refrigerant circulation path 51, and an aggregator 52 and an evaporator 53 installed in the circulation path 51, respectively, and water to be cooled from the cooling tower 10 exchanges heat with the refrigerant in the agglomerator 52. At the same time as the refrigerant is cooled, it is heated and returns to the cooling tower 10.

  The cooled refrigerant is sent to the evaporator 53, exchanges heat with the object to be cooled (such as indoor air), evaporates, and returns to the aggregator.

  As described above, the temperature of the object to be cooled can be adjusted by circulating the refrigerant between the evaporator 53 and the aggregator 52 and circulating the cooling water between the cooling device 50 and the cooling tower 10.

  In general, either one or both of tap water (tap water) and brine solution (water containing inorganic salt such as sodium chloride and potassium chloride) is used as the cooling water. The above is water, and there is a possibility that microorganisms will propagate.

  In particular, when tap water (clean water) is used or when an open cooling tower is used, there is a high risk that microorganisms will propagate.

  Therefore, in the present invention, the above-described coating agent is applied to a portion (a wetted portion) in contact with the cooling water in the cooling water system 4 including the cooling tower 10.

[Application target]
The wetted part to be applied is not particularly limited. For example, a member that is in direct contact with cooling water, such as a watering tray 31, a watering tray cover 34, a pipe 33, a filler 25, a bottom wall of the main body 11, a flow path 41, and other members (sprinkler, strainer, lower water tank, various pipes). There is a high possibility that cooling water droplets (mist) such as the louver 19, the blower 21, the partition member 32, the main body 11 ceiling (inner wall surface and outer wall surface), and the main body 11 side wall (inner side surface and outer side surface) may adhere. It may be a member.

  Among these wetted parts, microorganisms (algae, etc.) that are involved in photosynthesis are applied to parts irradiated with light such as sunlight, such as the watering tray 31, louver 19, main body 11 ceiling outer wall surface, and cover of the blower 21. It is preferable for the suppression of reproduction.

  The material of the wetted part is not particularly limited. For example, the wetted part is made of one or more materials selected from the group consisting of plastic, fiber, wood, concrete, brick, metal, metal oxide, alloy, ceramic, and glass. Is used.

  The coating agent used in the present invention can be applied to the material of each part constituting the cooling tower equipment without limiting the material. In particular, from the viewpoint of preventing metal corrosion by microorganisms, metal, alloy, metal oxide (metal Application to a portion where at least one metal-based material selected from the group consisting of (oxide film) is exposed to the surface is effective.

  In the coating agent used in the present invention, since the cationic sterilizing agent forms a complex with the polycarboxylic acid, not only foaming by the sterilizing agent is difficult to occur, but also the wetted part where the metallic material is exposed. Even if it is directly applied to the surface, the influence of ions (such as chlorine) derived from the cationic bactericide hardly occurs. Therefore, the coating agent can be applied to the wetted parts of various materials.

  The application target is not limited to metallic materials, and can be applied to wetted parts of various materials, but the wetted parts where voids (pores) are exposed on the surface of fibers, etc. are difficult to control. It is inappropriate.

  The application target may be an unused part (apparatus) or a used part (apparatus).

  As an unused part (apparatus), for example, an unused part (apparatus) used for parts replacement with the cooling water system 4 (cooling tower 10) before the start of use or the used cooling water system 4 (cooling tower 10) is used. is there.

  As used parts (devices), there are parts mounted on the used cooling water system 4 (cooling tower 10), parts (apparatus) removed from the used cooling water system 4 (cooling tower 10), and the like. .

  Both unused parts (apparatus) and used parts (apparatus) are preferably cleaned before applying the coating agent. In particular, used parts (apparatus) must be cleaned.

  Hereinafter, the pretreatment process including the cleaning process will be described.

[Pretreatment process]
Cleaning is not particularly limited as long as it can remove slime, scale, rust, and other dirt. For example, high-pressure cleaning that sprays water under pressure, chemical cleaning using chemicals (detergents), brushes and polishing equipment. There are mechanical cleaning (including keren) used, and it is possible to combine one or more of these cleaning processes.

  If necessary, after washing, the wetted part is dried, and if necessary, further pretreatment is performed for use in the coating process.

  Pre-treatment other than cleaning is not particularly limited, but if used parts (equipment) have a coating film for coloring or rust prevention, repair work such as re-coating of the coating film is performed as necessary. May be.

  Other pretreatments include surface treatments such as roughening treatment and base agent treatment in order to improve the adhesion with the coating agent, and two or more surface treatments may be combined. The base agent preferably has a functional group highly reactive with the functional group (carboxyl group, etc.) of the polycarboxylic acid, and can be bonded to the material (metal, glass, etc.) of the wetted part, for example, silane coupling. An agent can be used.

  However, since the coating agent used in the present invention hardly corrodes the metal-based material as described above, it is also possible to directly apply the coating agent to the surface of the wetted part.

[Coating process]
The coating agent may be applied to the entire surface of the component (apparatus) as described above, or may be applied only to a part thereof, but at least a portion that is in contact with or possibly in contact with cooling water. It is preferable to apply to.

  As a coating method of the coating agent, various coating methods including a brush coating method, a roller coating method, a spray spraying method, a dipping method, a coating method, and a printing method can be selected.

In the case of repeating the coating, it is preferable to dry after coating and fix the coating of the polycarboxylic acid ion complex on the construction part, and then perform the next coating. The number of repetitions of coating varies depending on the concentration of the coating agent used, but as a cationic bactericidal agent constituting the polycarboxylic acid ion complex, 0.05 nmol to 10 nmol per square centimeter (cm ² ) of the wetted part, The series of steps of coating, drying, and film fixing is repeated once or more so that it is preferably 0.1 nmoL or more and 5 nmoL or less, more preferably 0.15 nmoL or more and 2 nmoL or less.

  If the amount of the cationic bactericidal agent is less than 0.05 nmol, the bactericidal agent distribution in the bactericidal agent film is likely to be uneven, and the possibility that the microbial inhibitory effect is reduced is increased. On the other hand, if it exceeds 10 nmol, it is not realistic due to restrictions on working time and processing cost required for fixing the coating.

  In addition, each process of application | coating, drying, and film fixation may be performed in the state which mounted | wore the cooling water system 4 (cooling tower 10) with the components (apparatus) which has a wetted part, and the components (apparatus) which has a wetted part May be performed in a state where it is removed from the cooling water system (cooling tower 10).

  In any case, after application of a predetermined amount of the cationizing agent bactericide is completed and a bactericide coating is formed on the surface of the liquid contact part, use in the cooling water system 4 (cooling tower 10) described above is started.

  As described above, since the coating agent used in the present invention contains a poorly water-soluble polycarboxylic acid ion complex, the disinfectant film is dissolved and removed even when cooling water contacts the disinfectant film on the wetted part. It remains without being. Further, when cooling water or airborne microorganisms come into contact with the bactericidal agent film, the sterilizing agent is sterilized by the cationic bactericidal agent, thereby preventing the formation of slime (biofilm).

  Thus, according to the present invention, since the disinfectant coating is maintained for a long time, the formation of slime (biofilm) in the cooling water system 4 can be suppressed for a longer time than before. It is also possible to re-form the bactericide film during maintenance.

  The time of re-formation is not particularly limited. For example, when a preset period ends, when a preset operation time (total) of the cooling water system 4 has elapsed, sprinkling of the preset amount of cooling water has ended. When the cooling capacity (kW) of the cooling water system 4 decreases, the cooling water quality test results (number of cells, temperature, etc.), observation results of members (confirmation of algae adherence, etc.), operation after a long suspension of operation The above pre-processing step (cleaning) is performed when abnormalities such as abnormal noise, water leakage, deformation, etc. occur, and when one or more of the criteria set in these criteria are reached. Etc. and apply the coating agent again.

If the disinfectant film remains, an application agent may be applied thereon, but in order to control the application amount (nmol / cm ² ) of the cationic disinfectant, the remaining disinfectant film is washed. It is preferable to apply the coating agent again after removing in the step.

  Although the poorly water-soluble polycarboxylate ion complex does not dissolve in cooling water, it can be removed by ordinary cleaning processes such as mechanical cleaning, chemical cleaning, and high-pressure cleaning, unlike oxide films. Can be removed without damaging the device.

  The microorganisms to be suppressed in the present invention are not particularly limited, but an example will be described below.

[Microorganisms]
Although the microorganisms to be suppressed are not particularly limited, examples include algae, bacteria, protozoa, fungi, yeasts and the like. Among these, algae, bacteria, and protozoa, particularly algae and bacteria that cause organic slime generation in the cooling water system 4 are targets for suppression.

  Algae is not particularly limited, Indigo plant gate (Cyanobacteria), Green plant gate (Green algae), Red plant gate (Red algae), Yellow plant gate (Brown algae, Diatoms, etc.), Euglena plant gate, Dinoflagellate plant Various algae such as gates, prokaryotic green plant gates, gray plant gates, cryptophyte gates, chloracarnion plant gates and haptophyte gates are targeted.

  Protozoa is not particularly limited and includes amoeba, Paramecium, etc., and particularly amoeba.

  Bacteria are not particularly limited, and various bacteria such as Gram-negative bacteria, Gram-positive bacteria, aerobic bacteria, and anaerobic bacteria can be suppressed, and are in a symbiotic (parasitic) relationship with the algae and protozoa. It may be a non-symbiotic (non-parasitic) relationship. The bacteria to be specifically controlled in the present invention are bacteria having a symbiotic or parasitic relationship with one or both of the algae and protozoa, in particular, bacteria having a symbiotic relationship with the algae, for example, Aerobic bacteria (including facultative anaerobes), especially aerobic gram-negative bacteria such as Legionella.

[Method for inhibiting microorganisms]
In the present invention, the wetted part is protected by the disinfectant film formed in the above process.

  The disinfectant film formed according to the present invention contains 0.05 to 10 nmoL, preferably 0.1 to 5 nmoL, more preferably 0.15 to 2 nmol per 1 cm 2 of the wetted part. Therefore, it has a sufficient effect on suppressing the above-mentioned microorganisms. Moreover, since the polycarboxylic acid ion complex contained in the bactericidal agent coating is poorly water-soluble, it remains for a long time even in the wetted part in contact with the cooling water, and the effect of inhibiting the growth of microorganisms lasts for a long time.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
0.5 g of a poorly water-soluble polycarboxylate ion complex composed of poly-γ-glutamic acid and benzalkonium chloride was dissolved in 100 mL of a 70% aqueous ethanol solution to produce a 0.5 (w / v%) coating agent. The poly-γ-L-glutamate ion complex was produced as follows.

Poly-γ-L-glutamic acid sodium salt (1.0 g) having an average molecular weight of 1000 kD derived from the hyperhalophilic archaeon Natrialva Edipticia was dissolved in purified water to obtain a 2 w / v% solution. An 8 w / v% aqueous solution of benzalkonium chloride (2.4 g) kept at 60 ° C. was added to the solution. After confirming that a water-insoluble material was formed immediately after addition of benzalkonium chloride from an aqueous solution of poly-γ-L-glutamic acid sodium salt as a raw material, the mixture was further stirred at 25 ° C. for 2 hours. The obtained water-insoluble material was collected by filtration and then washed 3 times with 100 mL of purified water. It vacuum-dried and collect | recovered poly-gamma-glutamate ion complex (3.0g). From the result of ¹ H-NMR of the obtained poly-γ-glutamate ion complex, it was confirmed that poly-γ-L-glutamic acid and benzalkonium were bound at a molar ratio of 100: 100.

  The louver 19 of the cooling tower 10 was previously cleaned with a high-pressure water washer, and after drying, the coating agent was sprayed with a spray and then air-dried to form a disinfectant coating (FIG. 4 (a)).

The coating amount at this time was 0.2 nmol per 1 cm ² of the surface of the louver 19 as benzalkonium chloride.

  After that, when cooling water (tap water) without addition of a slime control agent was used and the cooling tower was operated, no algae was observed even after 2 weeks. After 6 months, although a little algae and microorganisms were attached, the degree of attachment was very slight compared to Comparative Example 1 (FIG. 4 (b)).

[Example 2]
0.5 g of a poorly water-soluble polycarboxylate ion complex composed of poly-γ-glutamic acid and cetylpyridinium chloride was dissolved in 100 mL of a 70% aqueous ethanol solution to produce a 0.5 w / v% coating agent. The poly-γ-L-glutamate ion complex was carried out as follows.

Poly-γ-L-glutamic acid sodium salt (1.0 g) having an average molecular weight of 1000 kD derived from the hyperhalophilic archaeon Natrialva edipitiaca (1.0 g) was dissolved in purified water to obtain a 2 w / v% solution. Cetylpyridinium chloride (2.4 g) kept at 60 ° C. was added to the solution. After confirming that a water-insoluble material was formed immediately after the addition of cetylpyridinium chloride from an aqueous solution of the raw material poly-γ-L-glutamic acid sodium salt, the mixture was further kept at 60 ° C. for 4 hours. The obtained water-insoluble material was collected by filtration and then washed 3 times with 100 mL of purified water. It vacuum-dried and collect | recovered poly-gamma-L-glutamate ion complex (3.0g) as a powder. From the result of ¹ H-NMR of the obtained poly-γ-L-glutamate ion complex, it was confirmed that poly-γ-L-glutamic acid and cetylpyridinium were bound at a molar ratio of 100: 100.

  Using this coating agent, a bactericide film was formed on the surface of the louver 19 under the same conditions as in Example 1 (FIG. 5A), and the cooling tower 10 was operated under the same conditions as in Example 1. Even after the lapse of time, no algae was observed, and after 6 months, although a slight amount of algae and microorganisms was observed, it was very slight compared to Comparative Example 1 (FIG. 5 (b)).

[Comparative Example 1]
The coating surface is cleaned with a high-pressure water washer in advance in the louver portion of the cooling tower (FIG. 6A), and after drying, the cooling tower 10 is operated under the same conditions as in Example 1 without applying the coating agent. did. In Comparative Example 1, adhesion of algae was observed after 2 weeks, and a large amount of algae and microorganisms were observed after 6 months (FIG. 6 (b)).

[Examples 3 to 14]
Except that the coating agent was produced under the conditions shown in Table 1, the disinfectant film was formed under the same conditions as in Example 1 and the cooling tower 10 was operated. Not observed, the adhesion of algae and microorganisms was slight even after 1 month.

  In Table 1, the coating amounts of Examples 7 and 8 are the total amount of two types of cationic fungicides. In addition, the ion complexes of Examples 3 to 8 were produced under the same conditions as in Example 1 except that the type of the cationic fungicide was changed, and the polycarboxylic acid ion complex of Example 9 was the same as in Example 2. The polycarboxylate ion complexes of Examples 10 and 11 were produced by the method described in paragraph 0076 of JP-A-2015-163686, except that HDPB (hexadecylpyridinium bromide) was changed to the substances shown in Table 1. The polycarboxylic acid ion complexes of Examples 12 and 13 were prepared in the same manner as in Examples 10 and 11 except that polyacrylic acid was changed to polymethacrylic acid (Aldrich, weight average molecular weight to 9500). In Example 14, poly-γ-glutamic acid used in Example 1 and polyacrylic acid used in Example 10 were added to the cationic fungicide. It is, except for using 0.5 eq (mass) those prepared by the same manufacturing method as in Example 2.

[Comparative Example 2]
Insert a PVC mesh plate (width: 145 mm x height: 195 mm x thickness: 3 mm) with no coating agent into the filler tank of the simulated cooling tower shown in FIG. Water was circulated from the dish and orthogonal aeration operation was performed from the side of the tower. After 2 weeks, the insertion mesh plate was confirmed. Algae adhesion was confirmed in the mesh hole.

[Comparative Example 3]
The coating agent described in Comparative Example 3 in Table 1 was applied to the PVC mesh plate used in Comparative Example 2 to form a bactericide film. Except for using this PVC mesh plate, an orthogonal ventilation operation of the simulated cooling tower was performed under the same conditions as in Comparative Example 2. After 2 weeks, adhesion of algae was confirmed in the mesh hole.

[Comparative Example 4]
Except that the composition of the coating agent was changed as described in the column of Table 1 and Comparative Example 4, when the orthogonal cooling operation of the simulated cooling tower was performed under the same conditions as in Comparative Example 3, it was 2 weeks as in Comparative Example 3. Later, algae adherence was confirmed in the mesh hole (Photo 5 right).

[Example 15]
The simulated cooling tower was subjected to orthogonal ventilation operation under the same conditions as in Comparative Example 3 except that the composition and the coating amount of the coating agent were changed as described in the column of Table 1 and Example 15. As for the mesh hole part, algae adhesion was very light compared with Comparative Examples 2-4.

[Example 16]
Except that the composition of the coating agent was changed as described in the column of Table 1 and Example 16, the simulated cooling tower was orthogonally ventilated under the same conditions as in Example 15, and then the mesh hole after 2 weeks. Compared with Comparative Examples 2-4, algae adhesion was very slight.

[Example 17]
The simulated cooling tower was subjected to orthogonal ventilation operation under the same conditions as in Example 16 except that the coating amount of the coating agent was changed as described in the column of Table 1 and Example 17. As for the part, algae adhesion was very slight compared with Comparative Examples 2-4.

  In Comparative Example 3 and Example 15, the same polycarboxylic acid ion complex as in Example 1 was used, and in Comparative Example 4 and Examples 16 and 17, the same polycarboxylic acid ion complex as in Example 2 was used.

DESCRIPTION OF SYMBOLS 4 Cooling water system 10 Cooling tower 11 Cooling tower main body 19 Louver 21 Blower 25 Filler 31 Sprinkling tray 32 Partition member 33 Piping 40 Cooling water circulation system 41 Flow path (piping) of cooling water circulation system
50 Cooling device 52 Coagulator

Claims (7)

A cooling water system having a cooling tower, a method for suppressing the growth of microorganisms in a wetted part in contact with cooling water,
A coating agent containing at least a poorly water-soluble polycarboxylic acid ion complex formed from a polycarboxylic acid and a cationic bactericidal agent is used so that the coating amount of the cationic bactericidal agent is 0.05 nmol or more and 10 nmol or less per 1 cm ^2. A cooling water-based microorganism control method comprising applying to the wetted part and forming a bactericide film on the wetted part.   The method for inhibiting microorganisms according to claim 1, wherein the polycarboxylic acid is selected from the group consisting of poly-γ-glutamic acid, polyacrylic acid, polymethacrylic acid, and a copolymer of methacrylic acid and acrylic acid.   The method for inhibiting microorganisms according to claim 1 or 2, wherein the cationic fungicide is one or both of a quaternary ammonium salt and a biguanide fungicide.   The method for suppressing microorganisms according to claim 3, wherein the quaternary ammonium salt is one or more selected from the group consisting of cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, and laurylpyridinium chloride.   The method for inhibiting microorganisms according to claim 3, wherein the biguanide fungicide is one or both of chlorhexidine hydrochloride and chlorhexidine gluconate.   The method for suppressing microorganisms according to any one of claims 1 to 5, wherein the coating agent contains the polycarboxylic acid ion complex in an amount of 0.1 w / v% to 30 w / v%. A coating agent used for suppressing the growth of microorganisms in a wetted part of a cooling water system having a cooling tower in contact with cooling water, which is a poorly water-soluble polymer formed from a polycarboxylic acid and a cationic fungicide. A coating agent containing 0.1 w / v% or more and 30 w / v% or less of a carboxylate ion complex is applied to the wetted part once or more, and 0.05 to 10 nmol of the cationic bactericidal agent is contained per 1 cm ^2. A coating method of a coating agent for forming a disinfectant film.

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