JP7407998B1 - anti-scaling agent - Google Patents

Abstract

[Problem] To provide a scale inhibitor that suppresses the generation and growth of scale. The scale inhibitor of the present invention is characterized by containing an oil agent and a surfactant. [Selection diagram] None

Description

The present invention relates to scale inhibitors.

In the production of pulp, the Kraft method (KP method) is the main method both in the world and in Japan. This is because the KP method can be used with a variety of materials, and the strength of the pulp produced is higher than that of other pulps.In addition to the increased productivity due to efficient recovery boilers and continuous digesters, the continuous method This is due to the dramatic improvement in chemical and energy recovery rates and the significant reduction in manufacturing costs due to the development of causticizing equipment.

However, the types and proportions of resins and inorganic substances vary depending on the wood type and production area, and in addition, alkaline chemicals are used during cooking, so in the chemical recovery process, especially in the black liquor concentration process, water-insoluble substances are used. Troubles occur when scale forms and adheres to the heat transfer plates inside the tank and evaporator.

In the dilute black liquor tank where the black liquor produced in the pulp washing process is stored, light calcium salts float when left standing, and the water evaporates because the temperature inside the tank is around 80 to 90 degrees Celsius. Then, lignin etc. aggregate with the calcium salt as a nucleus, scale grows, and concentrated lumps are generated one after another. When the black liquor flows in from above, scale is sent to the next concentration process, causing a blockage in the piping.

Conventionally, as countermeasures to the above-mentioned problems associated with scale generation, addition of scale inhibitors targeting inorganic substances, improvement of evaporator cleaning methods, addition of viscosity reducing agents, etc. are known. Conventional scale inhibitors are intended to disperse scale using water-soluble components.

As a scale inhibitor, Patent Document 1 describes a water-soluble graft polymer obtained by graft polymerizing a monoethylenically unsaturated monomer component onto a polyether compound, and Patent Document 2 describes a water-soluble graft polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component to a polyether compound, and Patent Document 2 describes a water-soluble graft polymer obtained by graft polymerizing a monoethylenically unsaturated monomer component to a polyether compound, and Patent Document 2 describes a water-soluble graft polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component to a polyether compound. A composition using the salt thereof has been proposed. Patent Document 3 proposes the use of a polybasic acid type aminocarboxylic acid compound in an aqueous system under alkaline conditions in cleaning the scale of an evaporator in a black liquor concentration process. As a thinning agent added in the black liquor concentration step, Patent Document 4 proposes a composition containing urea, a quaternary ammonium salt, or an alkanolamine, and Patent Document 5 proposes a composition containing a radical scavenger. U.S. Pat. No. 6,000,300 describes determining the level of scale deposition in a pulp mill evaporator or concentrator and, if the determined level of scale deposition is higher than a predetermined level, an effective amount of a scale inhibiting composition comprising a monocarboxylic acid; selected from the group consisting of: carboxylic acids; fatty acids; low and high molecular weight aromatic aliphatic compounds and aromatic sulfonic acids; esters, anhydrides and amides thereof; low and high molecular weight amines; and combinations thereof. A method has been proposed for monitoring the concentration of scale-inhibiting compositions in pulp effluents by using an inert fluorescent tracer using one or more compounds of the present invention.

Japanese Patent Application Publication No. 9-192691 Japanese Unexamined Patent Publication No. 7-119064 Japanese Patent Application Publication No. 2007-63696 Japanese Patent Application Publication No. 2014-19993 JP 2019-11543 Publication Special Publication No. 2010-527749

However, in Patent Documents 1 and 2, although it is effective against inorganic scales such as calcium carbonate, calcium phosphate, and silica, its effectiveness against lignin and organic salts such as fatty acids is not clarified. In Patent Document 3, scale can be removed without stopping operation after scale is generated, but scale generation cannot be suppressed. In Patent Documents 4 and 5, the operability in the concentration step is improved by reducing the viscosity of the black liquor, but it is necessary to add a scale inhibitor, a pitch control agent, etc. In Patent Document 6, by dissolving or dispersing a scale inhibiting composition in black liquor, which is pulp waste liquid, calcium carbonate, calcium phosphate, etc. are captured and dispersed before they become scale, and the generation of scale is inhibited. , it is necessary to determine the scale accumulation level and monitor the concentration of the scale-inhibiting composition in the pulp waste liquid.

In recent years, wood such as acacia has come to be used due to the demand for lower costs in pulp production, but low-cost wood such as acacia generates calcium salts. This calcium salt is mainly an organic calcium salt such as a resin fatty acid salt, and when such wood is used, scale formation is often observed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a scale inhibitor that suppresses the generation and growth of scale.

In order to solve the above-mentioned problem, the present inventor conducted extensive research and found that the cause of scale formation when using wood that generates the above-mentioned organic calcium salts was floating calcium salts. . Calcium salts contain many organic salts such as fatty acid salts. Therefore, by adding an oily component, the floating scale containing organic salts with many fatty acid salts is captured, and an oil film is formed on the top surface of the black liquor to prevent water evaporation. We obtained the knowledge that it is possible to prevent the scale from drying out and becoming hard, and from growing as a nucleus. At this time, it was discovered that when a surfactant is used together with an oil agent, the generation and growth of scale can be effectively suppressed, and the amount of oil agent used can also be reduced, and the present invention has been completed.

That is, the scale inhibitor of the present invention is characterized by containing an oil agent and a surfactant.

According to the present invention, generation and growth of scale can be suppressed.

It is a diagram showing an outline of the cooking process, the washing process, and the process of concentrating and burning the black liquor taken out in the washing process to recover a chemical solution and reusing it in the cooking process, in the manufacturing process of kraft pulp. FIG. 2 is a longitudinal cross-sectional view schematically showing a tank for handling black liquor in which an oil film is formed on the upper surface of the black liquor by a scale preventive agent containing an oil agent.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated concretely.
The scale targeted by the scale inhibitor of the present invention is not particularly limited, but includes, for example, scale generated during the pulp manufacturing process, and the pulp manufacturing method and pulp type are not particularly limited. Methods for producing pulp include, but are not particularly limited to, mechanical production methods, chemical production methods, intermediate production methods thereof, production methods using waste paper, and the like.

Pulp produced by a mechanical production method is not particularly limited, and examples thereof include mechanical pulp such as ground wood pulp and refiner ground pulp.
Pulp produced by a chemical production method is not particularly limited, but includes, for example, chemical pulp such as sulfite pulp and kraft pulp.
Examples of intermediate manufacturing methods between mechanical and chemical include, but are not limited to, semi-chemical pulp and chemical ground pulp.
The pulp produced by the method using waste paper is not particularly limited, but examples include waste paper pulp.

Among these, most of the pulp produced today is chemical pulp, which is mainly produced by craft pulp, because it can be used with a variety of materials, has high pulp strength, and can reduce manufacturing costs by improving the efficiency of recovering chemicals and energy. It's pulp. The method of the present invention can be particularly suitably used in chemical manufacturing methods since it includes steps in which scale is particularly likely to occur (cooking step and washing step described below). It can be used particularly suitably.

Figure 1 shows an overview of the kraft pulp manufacturing process, including the cooking process, the washing process, and the black liquor taken out in the washing process, which is concentrated and burned to recover the chemical solution, which is reused in the cooking process. In the cooking process, wood chips are supplied to the cooking tank 1, and the wood chips are boiled with chemicals to extract wood fibers as pulp.

Next, in the washing step, the pulp is washed with the pulp washing device 2 to remove resin contained in the pulp. After that, pulp is manufactured through a bleaching process. In the bleaching process, the pulp washed in the washing process is bleached into pure white pulp.

The resin washed away during the cleaning process is extracted as black liquor, which is concentrated and used as fuel for the boiler. That is, by burning the concentrated black liquor, water vapor is generated and electricity is obtained by driving a generator. The thermal energy obtained by burning black liquor can also be used for paper drying processes and other purposes within factories.

In a system for handling black liquor produced in the pulp manufacturing process, the black liquor is sequentially transferred to the dilute black liquor tank 3, evaporator 4, intermediate tank 5, evaporator 6, and stock solution tank 7 in FIG. 1 through piping or the like. The concentrated black liquor in the raw solution tank 7 is supplied to a recovery boiler 8 and burned, and the chemicals in the black liquor are recovered as combustion residue, and the chemicals are regenerated and supplied to the digester 1 in the pulp plant's cooking process. and reuse.

In the black liquor concentration process, various materials and chemicals are contained in the black liquor, and therefore there are many substances that cause scale generation, such as calcium phosphate and resin fatty acid salts. Concentration increases their concentration, and concentration also increases their viscosity. Therefore, hard scale etc. are likely to occur. This can cause scale to clog or stick to pipes, evaporators, filters, etc., resulting in poor concentration.

In the present invention, a scale preventive agent containing an oil agent and a surfactant is added to black liquor, and the substance and/or scale that causes scale generation is capped with the scale preventive agent containing an oil agent, thereby preventing scale generation. and suppress growth.

Substances that cause scale generation include organic salts, especially resin fatty acid salts, which are mainly oily substances in black liquor, and these are mainly calcium salts.

In the present invention, scale broadly includes water-insoluble aggregates generated in black liquor, strong hard scale, and the like. It also includes deposits and deposits on structures in systems that handle black liquor produced in the pulp manufacturing process, such as tanks, piping, evaporators, filters, etc. Water-insoluble aggregates generated in black liquor include suspended matter or sludge floating in water, also called sludge, and calcium salts, lignin, primary walls, cell intermediate layers, etc. Examples include aggregates of hydrophilic black substances.

In the present invention, capping refers to capturing substances and/or scales that cause scale generation in the oil phase of a scale preventive agent that is added to black liquor and contains an oil agent that is dispersed without being dissolved in water. This process involves forming an oil film using a scale preventive agent containing an oil agent on the upper surface of the liquid, and trapping the oil film between the oil film and the black liquor.

The present invention captures substances and/or scales that cause scale generation by adding a scale preventive agent containing an oily component, or as shown in FIG. By forming an oil film 11 and preventing water evaporation, substances and/or scales that cause scale generation are captured and removed between the oil film 11 and the black liquor 10. Alternatively, it is possible to prevent substances and/or scale that cause scale generation, such as aggregates, from proceeding to the next step. When water evaporates, it becomes dry and hard, which causes sludge to be generated, but this can be suppressed by forming an oil film 11 on the water surface to prevent evaporation.
If too much calcium salt goes on to the next process, it becomes a cause of scale generation during concentration, but by capping the substances and/or scale that cause scale generation, the amount of calcium salt that goes on to the concentration process is reduced, and It is possible to suppress the occurrence of scale.
When the particle size of water-insoluble aggregates increases, it can cause clogging in filters, piping, and subsequent processes. Furthermore, when wall scale becomes large and strong, it is difficult to remove the strong scale, and a large amount of water and time are required. However, when the scale inhibitor of the present invention is used, the particle size of the water-insoluble aggregates is small, and less calcium salt goes on to the next step. The wall scale is small and flexible, and forms a flexible calcium salt aggregate within or under the oil film, making it easy to remove. When the scale inhibitor of the present invention is used, the addition of water or black liquor for removing scale can be omitted, and the labor and time during collection and removal can be reduced.

During the concentration process, sludge that is insoluble in black liquor is generated in the diluted black liquor tank 3 shown in FIG. For example, calcium salts such as resin fatty acid salts float to the surface of the black liquor and coagulate due to water evaporation, resulting in sludge. If this sludge further grows as a scale, a portion of it will be drawn into the next process, causing contamination of tank walls and clogging of filters, piping, and the next process. In the diluted black liquor tank 3 where the black liquor is temporarily stored before concentration, organic calcium salts, which are the cause of scale, are removed by capping the top surface of the black liquor using an oil that is a base that is insoluble in water. It can suppress the solidification of scale due to evaporation etc. while capturing it, and suppress the formation of solid scale in the tank and evaporator.

In the evaporators 4 and 6, various components are dispersed, the various components are aggregated by concentration, and the viscosity is increased by concentration. As a result, hard scale is generated with calcium salts such as resin fatty acid salts as the core, and the hard scale remains without being dispersed. For example, the evaporators 4 and 6 are of a type using a heat transfer plate that uniformly disperses the liquid to the heating element from above using a distributor, but such evaporators 4 and 6 have a problem in that the heat transfer properties of the evaporators 4 and 6 decrease, Operational stoppages occur due to poor concentration, cleaning, etc. According to the present invention, a scale preventive agent containing an oil agent and a surfactant is added to black liquor, and the oil agent is used to remove substances and/or scales that cause scale generation, such as oily substances and/or aggregates. These can be suppressed by capping.

In the intermediate tank 5 between the evaporators 4 and 6 and in the raw solution tank 7 containing concentrated black liquor, generation and growth of high viscosity black liquor scale occurs. This will cause contamination of the tank wall, which will cause clogging of filters, piping, and the next process. According to the present invention, scale can be suppressed by adding a scale inhibitor containing an oil agent and a surfactant to black liquor to cap scale.

In the above, the oil film added to the black liquor can be collected by sucking it up from the upper surface side. The scale in the recovered material becomes a flexible calcium salt aggregate in the oil layer or the lower layer, and is easy to remove because it does not become hard.

In the scale inhibitor of the present invention, the oil agent is insoluble in water, or slightly soluble or slightly soluble in water. One indicator is the formation of an oil film on the top surface of the black liquor.

The boiling point of the oil is preferably 100°C or higher, and 120°C or higher to prevent it from evaporating or disappearing when added to the black liquor, since black liquor is used at temperatures ranging from about 80°C to around the boiling point of water. is more preferable.

Examples of oil agents include substances that separate from water or black liquor when mixed with water or black liquor, such as mineral oils, ester oils, glycol ether compounds, higher fatty acids, higher alcohols, silicone oils, etc. . These may be used alone or in combination of two or more.
Among these, mineral oils, ester oils, glycol ether compounds, and higher alcohols are preferred in terms of suppressing scale generation and growth.

Examples of the mineral oil include, but are not limited to, petroleum hydrocarbons, aromatic hydrocarbons, paraffin hydrocarbons, naphthenic hydrocarbons, olefin hydrocarbons, and the like.

Examples of the ester oil include, but are not limited to, esters of fatty acids and alcohols, esters obtained by adding alkylene oxides having three or more carbon atoms to fatty acids, and the like. The fatty acids constituting the ester oil are not particularly limited, but may be linear or branched, saturated or unsaturated, monobasic acids, polybasic acids, etc. It may be either. Further, the alcohol constituting the ester oil is not particularly limited, and may be, for example, a monohydric alcohol or a polyhydric alcohol.

Among the acids constituting ester oil, fatty acids having 2 to 24 carbon atoms are usually used as monobasic acids, and such fatty acids may be linear or branched, and may be saturated or unsaturated. It can be either saturated or saturated. Specifically, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched heptanoic acid, Straight chain or branched octanoic acid, straight chain or branched nonanoic acid, straight chain or branched decanoic acid, straight chain or branched undecanoic acid, straight chain or branched dodecanoic acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecanoic acid, Linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched henicosanoic acid , saturated fatty acids such as linear or branched docosanoic acid, linear or branched tricosanoic acid, linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched butenoic acid, linear or branched pentenoic acid, linear or branched hexenoic acid, linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched nonenoic acid, linear or branched nonenoic acid, linear or branched linear or branched decenoic acid, linear or branched undecenoic acid, linear or branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear linear or branched pentadecenoic acid, linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched nonadecenoic acid, linear or branched icosenoic acid, linear or branched henicosenoic acid, linear or branched docosenoic acid, linear or branched tricosenic acid, Examples include linear or branched unsaturated fatty acids such as tetracosenoic acid, and mixtures thereof.

Among the alcohols constituting the ester oil, monohydric alcohols usually have 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, and more preferably 1 to 8 carbon atoms, and such alcohols include linear, It may be branched, and may be saturated or unsaturated. Examples of alcohols having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, linear or branched pentanol, and linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol, linear or branched undecanol , linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched pentadecanol, linear or branched hexadecanol Nol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonadecanol, linear or branched icosanol, linear or branched henicosanol , linear or branched tricosanol, linear or branched tetracosanol, and mixtures thereof.

Among the alcohols constituting the ester oil, polyhydric alcohols are usually divalent to decavalent, preferably divalent to hexavalent. Specifically, the dihydric to decavalent polyhydric alcohols include propylene glycol, dipropylene glycol, polypropylene glycol (tri- to 15-mer of propylene glycol), 1,3-propanediol, 1,2-propanediol , 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol , 1,4-pentanediol, 1,5-pentanediol, neopentyl glycol, and other dihydric alcohols; Methylolalkane (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their dimers to octamers, pentaerythritol and their dimers to tetramers, 1,2,4-butanetriol, 1,3,5 - Polyhydric alcohols such as pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol; xylose, arabinose , ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, and mixtures thereof.

Among alcohols, trivalent or lower alcohols are preferred, and divalent or lower alcohols are more preferred, since they have low viscosity and are suitable for further suppressing the generation and growth of scale.

The total number of carbon atoms in fatty acids and alcohols in ester oil is difficult to absorb with water when decomposed at the heating temperature in the system that handles black liquor, and the number of carbon atoms in ester oil is low in terms of more effectively suppressing the generation and growth of scale. Larger is preferable. From this point of view, the total number of carbon atoms is preferably 4 or more, more preferably 8 or more.

Examples of linear ester oils include, but are not particularly limited to, ethyl butyrate, butyl butyrate, hexyl butyrate, ethyl laurate, butyl laurate, hexyl laurate, ethyl stearate, butyl stearate, hexyl stearate, and oleic acid. Examples include ethyl acid, butyl oleate, hexyl oleate, and the like.

Branched ester oils include, but are not particularly limited to, ethyl 2-ethylhexylate, butyl 2-ethylhexylate, octyl 2-ethylhexylate, ethyl isooctylate, butyl isooctylate, octyl isooctylate, ethyl isostearate, isostearin. Esters consisting of a fatty acid with a branched carbon chain length and an alcohol with a straight carbon chain length such as butyl acid, octyl isostearate, isooctyl isostearate, 2-ethylhexyl butyrate, 2-ethylhexyl laurate, 2-ethylhexyl oleate, butyric acid Ester consisting of a fatty acid with a straight carbon chain length such as isooctyl, isooctyl laurate, isooctyl oleate, isostearyl butyrate, isostearyl laurate, and isostearyl oleate and an alcohol with a branched carbon chain length, 2-ethylhexylate 2- Examples include esters consisting of a fatty acid with a branched carbon chain length and an alcohol with a branched carbon chain length, such as ethylhexyl, isooctyl 2-ethylhexylate, isostearyl 2-ethylhexylate, 2-ethylhexyl isostearate, and isooctyl isostearate.

Saturated ester oils include, but are not particularly limited to, ethyl butyrate, butyl butyrate, hexyl butyrate, ethyl laurate, butyl laurate, hexyl laurate, ethyl stearate, butyl stearate, hexyl stearate, and 2-ethylhexyl. Examples include butyl acid, octyl 2-ethylhexylate, ethyl isooctylate, butyl isooctylate, octyl isooctylate, ethyl isostearate, butyl isostearate, octyl isostearate, isooctyl isostearate, and the like.

Examples of the unsaturated ester oil include, but are not limited to, ethyl oleate, butyl oleate, hexyl oleate, 2-ethylhexyl oleate, oleyl butyrate, oleyl laurate, oleyl stearate, and the like.

Among these, unsaturated ester oils are preferred because the viscosity of the oil agent does not become too high and handling is easier.

The number of ester bonds in one molecule of ester oil is not particularly limited, and examples thereof include 1 to 4 (monoester, diol monoester, diester, diol diester, triester, tetraester). The number of ester bonds in one molecule of ester oil is preferably 3 or less (monoester, diester, triester), and 2 or less (monoester, diester) from the viewpoint that the viscosity of the oil agent does not become too high and handling is easier. is more preferable.

Examples of monoesters include, but are not particularly limited to, butyric acid alkyl esters such as ethyl butyrate, butyl butyrate, and octyl butyrate, and alkyl 2-ethylhexylate such as ethyl 2-ethylhexylate, butyl 2-ethylhexylate, and octyl 2-ethylhexylate. Examples include esters, isostearate alkyl esters such as ethyl isostearate, butyl isostearate, octyl isostearate, and isooctyl isostearate, and oleate alkyl esters such as butyl oleate, octyl oleate, and isooctyl oleate.

The diol monoester is not particularly limited, but includes, for example, propylene glycol fatty acid ester, neopentyl glycol fatty acid ester, which is an ester of the above dihydric alcohol and a fatty acid having 4 to 30 carbon atoms. Specifically, propylene glycol caprylate, propylene glycol caprate, propylene glycol laurate, propylene glycol palmitylate, propylene glycol stearate, propylene glycol oleate, neopentyl glycol laurate, and neopentyl glycol laurate. Examples include pentyl glycol palmitylate, neopentyl glycol stearate, neopentyl glycol oleate, and the like.

The diester is not particularly limited, but includes, for example, propylene glycol fatty acid diester, neopentyl glycol fatty acid diester, which is a diester of the above-mentioned dihydric alcohol and a fatty acid having 4 to 30 carbon atoms. Specifically, propylene glycol caprylate diester, propylene glycol caprylate diester, propylene glycol laurate diester, propylene glycol palmitylate diester, propylene glycol stearate diester, propylene glycol oleate diester, propylene glycol caprylate diester, Examples include propylene glycol capric acid lauric acid diester, neopentyl glycol lauric acid diester, neopentyl glycol palmitic acid diester, neopentyl glycol stearic acid diester, neopentyl glycol oleic acid diester. One type of fatty acid may be used alone, or two or more types may be used in combination.

The triester is not particularly limited, but includes, for example, trifatty acid trimethylolpropane ester, trifatty acid pentaerythritol ester, which is a triester of the above-mentioned polyhydric alcohol and a fatty acid having 4 to 30 carbon atoms. Specifically, trimethylolpropane tricaprylate, trimethylolpropane tricaprate, trimethylolpropane trilaurate, trimethylolpropane tripalmitylate, trimethylolpropane tristearate, trimethylolpropane trioleate, and tricapryl. Acid caprate trimethylolpropane ester, tricaprate laurate palmitate trimethylolpropane ester, trilaurate pentaerythritol ester, tripalmitylate pentaerythritol ester, tristearate pentaerythritol ester, trioleate pentaerythritol ester, rapeseed oil, palm oil , vegetable oils such as coconut oil, animal oils such as beef tallow and pork fat, and fish oils. One type of fatty acid may be used alone, or two or more types may be used in combination.

Tetraesters are not particularly limited, but include, for example, tetrafatty acid pentaerythritol esters of fatty acids, which are tetraesters of the above-mentioned polyhydric alcohols and carbon atoms having 4 to 30 carbon atoms. Specific examples include pentaerythritol tetralaurate, pentaerythritol tetrapalmitylate, pentaerythritol tetrastearate, pentaerythritol tetraoleate, pentaerythritol tetracaprylate, and the like. One type of fatty acid may be used alone, or two or more types may be used in combination.

The glycol ether compound is not particularly limited, but includes, for example, a carbon atom, a hydrogen atom, and an ether bond, and may be linear, branched, or cyclic.

Glycol ether compounds include, but are not particularly limited to, alkylene glycols, alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, and the like. The alkylene unit preferably has 2 to 5 carbon atoms.

Although the alkylene glycol is not particularly limited, it is preferable that the alkylene glycol has three or more alkyl groups, for example, in terms of being insoluble in water. Specific examples include polypropylene glycol, polybutylene glycol, and the like.

Although the alkylene glycol monoalkyl ether and the alkylene glycol dialkyl ether are not particularly limited, for example, it is preferable that the number of alkyl groups is 3 or more in terms of insolubility in water. The alkyl group preferably has 4 to 30 carbon atoms. Specifically, oleyl alcohol PO (4 mol) adduct, oleyl alcohol PO (8 mol) adduct, oleyl alcohol PO (12 mol) adduct, 2-ethylhexyl alcohol PO (4 mol) adduct, 2- Ethylhexyl alcohol PO (8 mol) adduct, 2-ethylhexyl alcohol PO (12 mol) adduct, oleyl alcohol BO (4 mol) adduct, oleyl alcohol alcohol BO (8 mol) adduct, oleyl alcohol BO (12 mol) Examples include adducts, 2-ethylhexyl alcohol BO (4 mol) adducts, 2-ethylhexyl alcohol BO (8 mol) adducts, 2-ethylhexyl alcohol BO (12 mol) adducts, and the like.

Higher fatty acids are not particularly limited, and may be, for example, linear or branched, and may be saturated or unsaturated. The number of carbon atoms in the higher fatty acid is preferably 6 to 24, more preferably 8 to 20, since it is preferable to have low solubility in water.

Examples of higher fatty acids include caproic acid, 2-ethylhexylic acid, isostearic acid, oleic acid, linolenic acid, and linoleic acid.

Examples of higher alcohols include, but are not limited to, saturated alcohols such as 2-ethylhexyl alcohol, lauryl alcohol, palmityl alcohol, stearyl alcohol, and isostearyl alcohol, and unsaturated alcohols such as oleyl alcohol. Unsaturated alcohols are preferred because they are easier to handle.

Silicone oils may include, but are not limited to, linear, cyclic, monomeric silicon/oxygen (organosiloxane) monomers, which may optionally have some additional functional groups. , or a branched polymer or oligomer. The polymer backbone is typically composed of alternating silicon and oxygen atoms. The silicon atom may have various substituents which may be the same or different. Functional end-blocking groups may have nitrogen or hydroxyl moieties.

Examples of the silicone oil include, but are not limited to, dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, stearoxymethylpolysiloxane, polyether-modified organopolysiloxane, and fluoroalkyl-polyoxyalkylene co-modified organopolysiloxane. Examples include silicone compounds such as siloxane, alkyl-modified organopolysiloxane, terminal-modified organopolysiloxane, fluorine-modified organopolysiloxane, amino-modified organopolysiloxane, silicone gel, acrylic silicone trimethylsiloxysilicate, and cyclopentasiloxane.

In the scale inhibitor of the present invention, when the surfactant is used in combination with an oil agent, the generation and growth of scale can be effectively suppressed, and the amount of oil agent used can also be reduced. This is thought to be because the surfactant contained in the oil suppresses aggregation of organic calcium and makes it easier to disperse in the oil or black liquor. Examples of surfactants include substances that disperse in water or black liquor when mixed with water or black liquor, such as anionic surfactants, nonionic surfactants, cationic surfactants, Examples include amphoteric surfactants. These may be used alone or in combination of two or more. Among these, anionic surfactants and nonionic surfactants are preferred, and it is more preferred to use an anionic surfactant and a nonionic surfactant in combination.

The anionic surfactant is not particularly limited, but for example, anionic surfactants such as sulfonate type, phosphate ester salt type, sulfate ester salt type, and carboxylate type can be used. These may be used alone or in combination of two or more.

Sulfonate type anionic surfactants include, but are not particularly limited to, alkanesulfonates, α-olefin sulfonates, α-sulfo fatty acid methyl ester salts, acyl isethionates, and alkyl glycidyl ether sulfonates. , alkyl sulfosuccinate, polyoxyalkylene alkyl sulfosuccinate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, N-acylmethyl taurate, formalin condensation sulfonate, paraffin sulfonate, alkylamide sulfonate, Examples include alkenyl amide sulfonates, alkyl glyceryl ether sulfonates, and alkylaryl ether sulfonates.

Examples of the phosphate ester salt type anionic surfactant include, but are not particularly limited to, alkyl phosphates, alkylaryl ether phosphates, fatty acid amide ether phosphates, polyoxyalkylene alkyl ether phosphates, etc. Can be mentioned.
Examples of sulfate ester salt type anionic surfactants include, but are not limited to, alkyl sulfates, alkenyl sulfates, alkyl ether sulfates, alkenyl ether sulfates, polyoxyalkylene alkyl ether sulfates, and alkylaryl ether sulfates. salts, fatty acid alkanolamide sulfates, fatty acid monoglyceride sulfates, polyoxyalkylene aliphatic amide ether sulfates, alkyl glyceryl ether sulfates, sulfated fatty acid alkyl esters, and the like.

Carboxylate type anionic surfactants include, but are not particularly limited to, fatty acid soaps, alkyl ether carboxylates, alkylene alkyl ether carboxylates, fatty acid amide ether carboxylates, acyl lactates, N-acyl Examples include glutamate, N-acylalanine salt, N-acylsarcosine salt, N-acyl-ω-amino acid salt, alkylsulfoacetate, alkenylsulfoacetate, alkenylsuccinate, rosinate, naphthenate, etc. .

Nonionic surfactants include, but are not particularly limited to, ethylene glycol fatty acid esters, monoglycerin fatty acid esters, diglycerin fatty acid esters, polyglycerin fatty acid esters, organic acid monoglycerides, sorbitan fatty acid esters, sucrose fatty acid esters, and polyglycerin fatty acid esters. Oxyethylene fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil fatty acid ester, castor oil fatty acid ester, hydrogenated castor oil fatty acid Examples include ester, polyoxyethylene alkyl ether, polyoxyethylene lanolin alcohol ether, polyethylene glycol fatty acid monoethanolamide, fatty acid alkanolamide, and the like.

Among these, ethylene glycol fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl ether, and polyethylene glycol fatty acid monoethanol are used because organic calcium salts can be easily dispersed in oil or black liquor, and scale growth can be better prevented. Amides and fatty acid alkanolamides are preferred.

Ethylene glycol fatty acid esters are not particularly limited, but include, for example, esters of fatty acids having 4 to 30 carbon atoms, specifically ethylene glycol laurate, ethylene glycol myristate, ethylene glycol palmitate, Examples include ethylene glycol stearate, ethylene glycol oleate, ethylene glycol linoleate, ethylene glycol linolenic acid ester, and ethylene glycol erucate.

Monoglycerin fatty acid esters are not particularly limited, but include, for example, esters of fatty acids having 4 to 30 carbon atoms, specifically monoglycerin laurate, monoglycerin myristate, monoglycerin palmitate, Examples include monoglycerol stearate, monoglycerol oleate, monoglycerol linoleate, monoglycerol linolenic acid ester, and monoglycerol erucate.

The diglycerin fatty acid ester is not particularly limited, but includes, for example, esters of fatty acids having 4 to 30 carbon atoms, and specifically, diglycerin laurate, diglycerin myristate, diglycerin palmitate, Diglycerol stearate, diglycerol oleate, diglycerol linoleate, diglycerol linolenic acid ester, diglycerol erucate, and the like.

Polyglycerin fatty acid esters are not particularly limited, but include, for example, esters of fatty acids having 4 to 30 carbon atoms, specifically, polyglycerin laurate, polyglycerin myristate, polyglycerin palmitate, Examples include polyglycerol stearate, polyglycerol oleate, polyglycerol linoleate, polyglycerol linolenic acid ester, and polyglycerol erucate.

Examples of the organic acid monoglyceride include, but are not limited to, succinic acid fatty acid monoglyceride, citric acid fatty acid monoglyceride, diacetyl tartaric acid fatty acid monoglyceride, acetic acid fatty acid monoglyceride, lactic acid fatty acid monoglyceride, and the like.

Sorbitan fatty acid esters are not particularly limited, but include, for example, esters of fatty acids having 4 to 30 carbon atoms, specifically sorbitan monolaurate, sorbitan dilaurate, sorbitan trilaurate, sorbitan monomyristate, sorbitan dimiristate, sorbitan trimistate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan trimistate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan dioleate, sorbitan Trioleate, monolinoleic acid sorbitan ester, dilinoleic acid sorbitan ester, trilinoleic acid sorbitan ester, monolinolenic acid sorbitan ester, dilinolenic acid sorbitan ester, trilinolenic acid sorbitan ester, and the like.

The sucrose fatty acid ester is not particularly limited, but includes, for example, esters of fatty acids having 4 to 30 carbon atoms, and specifically, sucrose caprylate, sucrose caprate, sucrose laurate, Examples include sucrose myristate, sucrose palmitate, sucrose stearate, sucrose oleate, sucrose erucate, and the like.

Polyoxyethylene fatty acid esters are not particularly limited, but include, for example, esters consisting of a fatty acid having 4 to 30 carbon atoms and 2 to 60 moles of oxyethylene units; Examples include polymers. Specifically, polyoxyethylene monolaurate, polyoxyethylene polyoxypropylene monolaurate, polyoxyethylene dilaurate, polyoxyethylene trilaurate, polyoxyethylene monomyristate, polyoxyethylene poly Oxypropylene monomyristate, polyoxyethylene dimyristate, polyoxyethylene trimyristate, polyoxyethylene monopalmitate, polyoxyethylene polyoxypropylene monopalmitate, polyoxyethylene dipalmitate, Polyoxyethylene tripalmitate, polyoxyethylene monostearate, polyoxyethylene polyoxypropylene monostearate, polyoxyethylene distearate, polyoxyethylene tristearate, polyoxyethylene oleate, polyoxyethylene Examples include oxyethylene linoleic acid ester, polyoxyethylene linolenic acid ester, polyoxyethylene erucic acid ester, and the like.

Examples of the polyoxyethylene glycerin fatty acid ester include, but are not limited to, polyoxyethylene monoglycerin laurate, polyoxyethylene polyoxypropylene monoglycerin laurate, polyoxyethylene polyglycerin laurate, and polyoxyethylene monoglycerin laurate. Glycerin myristate, polyoxyethylene polyoxypropylene monoglycerin myristate, polyoxyethylene polyglycerin myristate, polyoxyethylene monoglycerin palmitate, polyoxyethylene polyoxypropylene monoglycerin palmitate, polyoxyethylene Polyglycerin palmitate, polyoxyethylene monoglycerin stearate, polyoxyethylene polyoxypropylene monoglycerin stearate, polyoxyethylene polyglycerin stearate, polyoxyethylene monoglycerin oleate, polyoxyethylene polyglycerin Examples include oleic acid esters.

Polyoxyethylene sorbitan fatty acid esters are not particularly limited, but examples include polyoxyethylene sorbitan laurate, polyoxyethylene polyoxypropylene sorbitan laurate, polyoxyethylene sorbitan myristate, and polyoxyethylene polyoxypropylene sorbitan. Myristic acid ester, polyoxyethylene sorbitan palmitate, polyoxyethylene polyoxypropylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxyethylene polyoxypropylene sorbitan stearate, polyoxyethylene sorbitan oleate, etc. can be mentioned.

Examples of polyoxyethylene hydrogenated castor oil include, but are not limited to, polyoxyethylene (2) hydrogenated castor oil, polyoxyethylene (2) polyoxypropylene (2) hydrogenated castor oil, and polyoxyethylene (5) hydrogenated castor oil. Oil, polyoxyethylene (5) polyoxypropylene (5) hydrogenated castor oil, polyoxyethylene (6) hydrogenated castor oil, polyoxyethylene (6) polyoxypropylene (6) hydrogenated castor oil, polyoxyethylene (7) Hydrogenated castor oil, polyoxyethylene (7) polyoxypropylene (7) hydrogenated castor oil, polyoxyethylene (10) hydrogenated castor oil, polyoxyethylene (10) polyoxypropylene (10) hydrogenated castor oil, polyoxyethylene ( 16) Hydrogenated castor oil, polyoxyethylene (16) polyoxypropylene (16) hydrogenated castor oil, polyoxyethylene (25) hydrogenated castor oil, polyoxyethylene (25) polyoxypropylene (25) hydrogenated castor oil, polyoxy Ethylene (30) hydrogenated castor oil, polyoxyethylene (30) polyoxypropylene (30) hydrogenated castor oil, polyoxyethylene (35) hydrogenated castor oil, polyoxyethylene (35) polyoxypropylene (35) hydrogenated castor oil, Polyoxyethylene (40) hydrogenated castor oil, polyoxyethylene (40) polyoxypropylene (40) hydrogenated castor oil, polyoxyethylene (45) hydrogenated castor oil, polyoxyethylene (45) polyoxypropylene (45) hydrogenated castor oil Oil, polyoxyethylene (50) Hydrogenated castor oil, polyoxyethylene (50) Polyoxypropylene (50) Hydrogenated castor oil, polyoxyethylene (54) Hydrogenated castor oil, polyoxyethylene (54) Polyoxypropylene (54) Hydrogenated castor oil, polyoxyethylene (60) hydrogenated castor oil, polyoxyethylene (60) polyoxypropylene (60) hydrogenated castor oil, polyoxyethylene (100) hydrogenated castor oil, polyoxyethylene (100) polyoxypropylene ( 100) hydrogenated castor oil, polyoxyethylene (200) hydrogenated castor oil, polyoxyethylene (200) polyoxypropylene (200) hydrogenated castor oil, and the like.

Examples of polyoxyethylene castor oil include, but are not limited to, polyoxyethylene (4) castor oil, polyoxyethylene (4) polyoxypropylene (4) castor oil, polyoxyethylene (10) castor oil, and polyoxyethylene (10) castor oil. Ethylene (10) Polyoxypropylene (10) Castor oil, Polyoxyethylene (20) Castor oil, Polyoxyethylene (20) Polyoxypropylene (20) Castor oil, Polyoxyethylene (25) Castor oil, Polyoxyethylene ( 25) Polyoxypropylene (25) castor oil, polyoxyethylene (30) castor oil, polyoxyethylene (30) polyoxypropylene (30) castor oil, polyoxyethylene (35) polyoxypropylene (35) castor oil, Examples include polyoxyethylene (35) castor oil, polyoxyethylene (50) castor oil, polyoxyethylene (50) polyoxypropylene (50) castor oil, and the like.

Examples of the polyoxyethylene hydrogenated castor oil fatty acid ester include, but are not limited to, polyoxyethylene laurate (10) hydrogenated castor oil, polyoxyethylene laurate (10) polyoxypropylene (10) hydrogenated castor oil, and lauric acid. Polyoxyethylene (20) hydrogenated castor oil, polyoxyethylene laurate (20) polyoxypropylene (20) hydrogenated castor oil, polyoxyethylene laurate (40) hydrogenated castor oil, polyoxyethylene laurate (40) polyoxy Propylene (40) hydrogenated castor oil, polyoxyethylene laurate (50) hydrogenated castor oil, polyoxyethylene laurate (50) polyoxypropylene (50) hydrogenated castor oil, polyoxyethylene myristate (10) hydrogenated castor oil, Polyoxyethylene myristate (10) Polyoxypropylene (10) Hydrogenated castor oil, Polyoxyethylene myristate (20) Hydrogenated castor oil, Polyoxyethylene myristate (20) Polyoxypropylene (20) Hydrogenated castor oil, Myristic acid Polyoxyethylene (40) hydrogenated castor oil, polyoxyethylene myristate (40) polyoxypropylene (40) hydrogenated castor oil, polyoxyethylene myristate (50) hydrogenated castor oil, polyoxyethylene myristate (50) polyoxy Propylene (50) hydrogenated castor oil, polyoxyethylene palmitate (10) hydrogenated castor oil, polyoxyethylene palmitate (10) polyoxypropylene (10) hydrogenated castor oil, polyoxyethylene palmitate (20) hydrogenated castor oil, Polyoxyethylene palmitate (20) Polyoxypropylene (20) Hydrogenated castor oil, Polyoxyethylene palmitate (40) Hydrogenated castor oil, Polyoxyethylene palmitate (40) Polyoxypropylene (40) Hydrogenated castor oil, Palmitic acid Polyoxyethylene (50) Hydrogenated castor oil, polyoxyethylene palmitate (50) Polyoxypropylene (50) Hydrogenated castor oil Polyoxyethylene stearate (10) Hydrogenated castor oil, Polyoxyethylene stearate (10) Polyoxypropylene (10) Hydrogenated castor oil, polyoxyethylene stearate (20) Hydrogenated castor oil, polyoxyethylene stearate (20) Polyoxypropylene (20) Hydrogenated castor oil, polyoxyethylene stearate (40) Hydrogenated castor oil, stearin Acid polyoxypolyoxyethylene (40) propylene (40) hydrogenated castor oil, polyoxyethylene stearate (50) hydrogenated castor oil, polyoxyethylene stearate (50) polyoxypropylene (50) hydrogenated castor oil, etc. .

Castor oil fatty acid esters are not particularly limited, but include, for example, castor oil laurate, castor oil myristate, castor oil palmitate, castor oil stearate, castor oil isostearate, castor oil triisostearate, and the like.

Examples of hydrogenated castor oil fatty acid esters include, but are not limited to, lauric acid hydrogenated castor oil, myristic acid hydrogenated castor oil, palmitic acid hydrogenated castor oil, stearic acid hydrogenated castor oil, isostearic acid hydrogenated castor oil, and triisostearic acid hydrogenated castor oil. Examples include oil.

Examples of the polyoxyethylene alkyl ether include, but are not particularly limited to, esters consisting of alcohols having 4 to 30 carbon atoms and 2 to 60 moles of oxyethylene units, and co-existences with polyoxypropylene, polyoxybutylene, etc. Examples include polymers. Specifically, polyoxyethylene (2) lauryl ether, polyoxyethylene (2) polyoxypropylene (2) lauryl ether, polyoxyethylene (4) lauryl ether, polyoxyethylene (4) polyoxypropylene (4) Lauryl ether, polyoxyethylene (6) lauryl ether, polyoxyethylene (6) polyoxypropylene (6) lauryl ether, polyoxyethylene (9) lauryl ether, polyoxyethylene (9) polyoxypropylene (9) lauryl ether , polyoxyethylene (15) lauryl ether, polyoxypropylene (15) lauryl ether, polyoxyethylene (23) lauryl ether, polyoxyethylene (23) polyoxypropylene (23) lauryl ether, polyoxyethylene (30) lauryl Ether, polyoxyethylene (50) lauryl ether, polyoxyethylene (30) polyoxypropylene (30) lauryl ether, polyoxyethylene (2) cetyl ether, polyoxyethylene (2) polyoxypropylene (2) cetyl ether, Polyoxyethylene (4) cetyl ether, polyoxyethylene (4) polyoxypropylene (4) cetyl ether, polyoxyethylene (7) cetyl ether, polyoxyethylene (7) polyoxypropylene (7) cetyl ether, polyoxy Ethylene (10) cetyl ether, polyoxyethylene (10) polyoxypropylene (10) cetyl ether, polyoxyethylene (13) cetyl ether, polyoxyethylene (13) polyoxypropylene (13) cetyl ether, polyoxyethylene ( 20) Cetyl ether, polyoxyethylene (20) polyoxypropylene (20) cetyl ether, polyoxyethylene (30) cetyl ether, polyoxyethylene (30) polyoxypropylene (30) cetyl ether, polyoxyethylene (2) Stearyl ether, polyoxyethylene (2) polyoxypropylene (2) stearyl ether, polyoxyethylene (4) stearyl ether, polyoxyethylene (4) polyoxypropylene (4) stearyl ether, polyoxypolyoxyethylene (6) Stearyl ether, polyoxyethylene (6) polyoxypolyoxypropylene (6) stearyl ether, polyoxyethylene (8) stearyl ether, polyoxyethylene (8) polyoxypropylene (8) stearyl ether, polyoxyethylene (10) Stearyl ether, polyoxyethylene (10) polyoxypropylene (10) stearyl ether, polyoxyethylene (13) stearyl ether, polyoxyethylene (13) polyoxypropylene (13) stearyl ether, polyoxyethylene (18) stearyl ether , polyoxyethylene (18) polyoxypropylene (18) stearyl ether, polyoxyethylene (20) stearyl ether, polyoxyethylene (20) polyoxypropylene (20) stearyl ether, polyoxyethylene (25) stearyl ether, poly Oxyethylene (25) polyoxypropylene (25) stearyl ether, polyoxyethylene (30) stearyl ether, polyoxyethylene (30) polyoxypropylene (30) stearyl ether, polyoxyethylene (35) stearyl ether, polyoxyethylene (35) Polyoxypropylene (35) stearyl ether, polyoxyethylene (50) stearyl ether, polyoxyethylene (50) polyoxypropylene (50) stearyl ether, polyoxyethylene (2) oleyl ether, polyoxyethylene (4 ) oleyl ether, polyoxyethylene (6) oleyl ether, polyoxyethylene (8) oleyl ether, polyoxyethylene (9) oleyl ether, polyoxyethylene (10) oleyl ether, polyoxyethylene (12) oleyl ether, polyoxyethylene (12) oleyl ether, Oxyethylene (16) oleyl ether, polyoxyethylene (18) oleyl ether, polyoxyethylene (20) oleyl ether, polyoxyethylene (25) oleyl ether, polyoxyethylene (30) oleyl ether, polyoxyethylene (2) Octyl dodecyl ether, polyoxyethylene (4) octyl dodecyl ether, polyoxyethylene (6) octyl dodecyl ether, polyoxyethylene (10) octyl dodecyl ether, polyoxyethylene (14) octyl dodecyl ether, polyoxyethylene (20) Octyl dodecyl ether, polyoxyethylene (25) octyl dodecyl ether, polyoxyethylene (8) nonyl ether, polyoxyethylene (8) undecyl ether, polyoxyethylene (5) isodecyl ether, polyoxyethylene (6) iso Decyl ether, polyoxyethylene (3) tridecyl ether, polyoxyethylene (5) tridecyl ether, polyoxyethylene (7) tridecyl ether, polyoxyethylene (8) tridecyl ether, polyoxyethylene (9) tridecyl ether, Decyl ether, polyoxyethylene (10) tridecyl ether, polyoxyethylene (12) tridecyl ether, polyoxyethylene (15) tridecyl ether, polyoxyethylene (20) tridecyl ether, polyoxyethylene (8) iso Examples include stearyl ether, polyoxyethylene (12) isostearyl ether, polyoxyethylene (16) isostearyl ether, and the like.

The polyoxyethylene lanolin alcohol ether is not particularly limited, but includes, for example, polyoxyethylene (10) lanolin alcohol, polyoxyethylene (10) polyoxypropylene (10) lanolin alcohol, polyoxyethylene (20) lanolin alcohol, and polyoxyethylene (20) lanolin alcohol. Oxyethylene (20) Polyoxypropylene (20) Lanolin alcohol, Polyoxyethylene (25) Lanolin alcohol, Polyoxyethylene (25) Polyoxypropylene (25) Lanolin alcohol, Polyoxyethylene (40) Lanolin alcohol, Polyoxyethylene (40) polyoxypropylene (40) lanolin alcohol, polyoxyethylene (50) lanolin alcohol, polyoxyethylene (50) polyoxypropylene (50) lanolin alcohol, and the like.

The polyethylene glycol fatty acid monoethanolamide is not particularly limited, but includes, for example, a 2-60 mole ethylene oxide adduct of a fatty acid monoethanolamide having 4 to 30 carbon atoms.

Examples of fatty acid alkanolamides include, but are not particularly limited to, fatty acid alkanolamides having 8 to 18 fatty acid carbon atoms. Specifically, fatty acid alkanolamides include coconut oil fatty acid mono- or diethanolamide, lauric acid mono- or diethanolamide, and palmitic acid. Examples include mono- or diethanolamide, myristic acid mono- or diethanolamide, stearic acid mono- or diethanolamide, oleic acid mono- or diethanolamide, palm oil fatty acid mono- or diethanolamide, and the like.

The cationic surfactant is not particularly limited, but for example, cationic surfactants of the quaternary ammonium salt type, pyridinium salt type, and alkylamine salt type can be used. These may be used alone or in combination of two or more.
The quaternary ammonium salt type cationic surfactant is not particularly limited, but includes, for example, alkyltrimethylammonium salts (oleyltrimethylammonium chloride, etc.), dialkyldimethylammonium salts, alkylbenzalkonium salts, N,N-dial Examples include chiloyloxyethyl-N-methyl, N-hydroxyethylammonium salt, and the like.

The pyridinium salt type cationic surfactant is not particularly limited, but includes, for example, alkylpyridinium salts.

The alkylamine salt type cationic surfactant is not particularly limited, and examples thereof include monoalkylamine salts, dialkylamine salts, trialkylamine salts, and the like.

The amphoteric surfactant is not particularly limited, but for example, amphoteric surfactants such as betaine type, imidazoline type, amino acid type, and amine oxide type can be used. These may be used alone or in combination of two or more.

Examples of betaine-type amphoteric surfactants include, but are not limited to, alkyl betaines, fatty acid amidopropyl betaines (lauramidopropyl betaines, etc.), laurylhydroxysulfobetaines, alkylhydroxysulfobetaines, lecithin, hydrogenated lecithin, and the like. It will be done.

Examples of imidazoline type amphoteric surfactants include, but are not limited to, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, 2-alkyl-1-(2-hydroxyethyl)imidazolinium -1-acetate, undecylhydroxyethylimidazolinium betaine sodium, and the like.

Amino acid type amphoteric surfactants include, but are not particularly limited to, alkyldiethylenetriaminoacetate, alkyloxyhydroxypropyl arginine hydrochloride, sodium lauryl aminodiacetate, dihydroxyalkylmethylglycine, sodium lauryldiaminoethylglycine, and laurimino. Examples include dipropionic acid, N-[3-alkyloxy-2-hydroxypropyl]-L-arginine hydrochloride, sodium alkylaminodipropionate, and the like.

Examples of the amine oxide type amphoteric surfactant include, but are not particularly limited to, alkyldimethylamine oxide and the like.

In the scale inhibitor of the present invention, the mass ratio of oil and surfactant (oil: surfactant) is preferably 99:1 or more, and 98:2 from the viewpoint of effectively suppressing the generation and growth of scale. The ratio is more preferably 95:5 or more, and even more preferably 95:5 or more. In addition, if the surfactant is in excess, the interfacial tension between the oil agent and the black liquor decreases and the capping effect is lost, so the ratio is preferably 60:40 or less, more preferably 75:25 or less, and 85:15 or less. More preferred.

The content of the oil in the scale inhibitor of the present invention is preferably 60% by mass or more, more preferably 65% by mass or more, and even more preferably 75% by mass or more, from the standpoint of effectively suppressing the generation and growth of scale. , 85% by mass or more is particularly preferred.

The scale inhibitor of the present invention may contain other components other than the oil agent and surfactant within a range that does not impair the effects of the present invention. Other components include, but are not particularly limited to, water, antifoaming agents, chelating agents, and the like.

The amount of the scale inhibitor of the present invention added to the black liquor is preferably 0.5% by mass or more, more preferably 1% by mass or more based on the black liquor in the tank, from the viewpoint of suppressing the generation and growth of scale. , more preferably 3% by mass or more. The upper limit is not particularly limited, but from the viewpoint of reducing the amount of oil used and suppressing the generation and growth of scale, it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.
The oils and surfactants listed in Table 2 were used to add to the black liquor. Table 1 shows the types of oil agents and surfactants. A scale inhibitor was prepared by mixing these oil agents and surfactants.
A black liquor sample was prepared by adding 5% by mass of sediment corresponding to the scale mass to the black liquor, dispersing it with ultrasonic waves, and filtering it through a 100 mesh filter cloth.
300 mL of the black liquor sample and 15 mL of the scale inhibitor were added to a stainless steel beaker with a diameter of 7.2 cm and a height of 11.0 cm, and the mixture was heated at about 85° C. for 3 hours. After that, while restricting the discharge amount to about 50 g/min, draw out the black liquor solution (black liquor part: about 290 ml, remaining oil part: 5 to 25 ml) from the bottom, and check the dirt on the wall and the condition of the recovered sample. , the mass of the scale, which is the residue in the beaker, was measured.
Wall surface stains were evaluated based on the scale mass using the following criteria.
◎+: Scale mass is less than 2.5 g ◎: Scale mass is 2.5 g or more and less than 5.0 g ○: Scale mass is 5.0 g or more and less than 7.5 g △: Scale mass is 7.5 g or more and less than 10 g ×: Scale Mass is 10g or more

Table 2 shows the results of the above measurements and evaluations.

1 Digesting tank 2 Pulp cleaning device 3 Dilute black liquor tank 4 Evaporator 5 Intermediate tank 6 Evaporator 7 Raw solution tank 8 Recovery boiler 9 Tank wall 10 Black liquor 11 Oil film

Claims (3)

A scale inhibitor containing an oil agent and a surfactant, the content of the oil agent being 60% by mass or more . The scale inhibitor according to claim 1, wherein the surfactant is one or more selected from anionic surfactants and nonionic surfactants. The scale inhibitor according to claim 1 or 2, wherein the mass ratio of the oil agent to the surfactant is 99:1 to 60:40.

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