JP5464837B2 - Deposit removing agent and deposit removing method for color coat coating process for papermaking - Google Patents

Description

  The present invention relates to a deposit removing agent and a deposit removing method in a paper coat color coat coating process.

  In recent years, there has been a social eagerness to improve the production capacity of coated paper due to a surge in demand. In view of this, speeding up of the coating process has progressed, and for that purpose, excellent high-speed fluidity has been demanded of the composition for paper coating. In recent years, the coated paper industry has introduced a blade coater as a main coating machine in order to increase productivity, and has taken various measures to increase the coating speed. In the case of this high-speed coating, good fluidity and water retention of the paint are required, but good fluidity and water retention are also required for the latex used as a binder in the paint. On the other hand, the printing speed has been increased, and the coated paper is required to have excellent wet topic strength and blister resistance that can withstand such high-speed printing. By increasing the printing speed and the quality and function of the coated paper, the performance of the coating liquid has been improved so as to cope with this.

  A papermaking coating liquid (paper coating composition) for producing coated paper is an aqueous dispersion mixture mainly composed of a pigment, a binder, water, and various additives. Clay, calcium carbonate, kaolin and the like are used, and as the binder (or adhesive), copolymer latex such as SBR latex and NBR latex is used. The method of applying the coating liquid to the coated paper is performed by a coating machine such as a blade coater, a roll coater, or a bar coater. In addition, after coating, the surface is dried and finished by calendaring or the like.

The coating liquid is usually circulated between the coating liquid storage tank and the transfer pipe, the transfer pump and the coater. The coating liquid adheres to the coating liquid storage tank, the transfer pipe and the coater as it is used, solidifies and deposits. Sex sticking occurs. If the deposit deposits that are generated become large, not only will the coating condition be affected by a decrease or fluctuation in the flow rate of the coating solution in the piping, etc., but the deposits will peel off and be included in the coating solution as fine lumps. In addition to making scratches on the coated paper surface with the coater, not only significantly reducing the quality of the coated paper, but also damaging the tooth surface of the coater, causing significant damage to the device and must be avoided. Therefore, a filter is installed in the circulation line between the coating liquid storage tank and the transfer pipe, transfer pump, and coater to remove fine lumps, and the deposits on the coating liquid circulation line are periodically removed with mineral acid. Various methods such as a method of washing and removing using an organic acid or an alkali agent have been proposed. For example, a method of dispersing and washing with an acrylic acid polymer (for example, see Patent Document 1), a method of using an organic phosphonic acid or a salt thereof (for example, see Patent Document 2), and an inorganic acid and an organic acid. A method using a deposit removing agent (see, for example, Patent Document 3), and a method in which a soiled coating roll is immersed in a cleaning solution containing an organic solvent, an alkaline cleaning agent, and a surfactant to apply ultrasonic waves to perform cleaning (for example, Patent Document 4). See), a method of attaching an elastic body to the discharge portion of the coating liquid supply header (see, for example, Patent Document 5), a coating machine in which a cleaning device is incorporated in the coating apparatus (see, for example, Patent Document 6), and a die coater There is a method in which a movable core is provided inside and the inside of the die coater is cleaned by the movement (for example, see Patent Document 7). However, the cleaning method using an acrylic acid polymer or a chelating agent cannot effectively remove the cured product of the resin derived from the SBR latex in the deposit, and can also remove mineral acids / organic acids, organic phosphones. Even in a method using an acid or a salt thereof, calcium carbonate contained in the deposit can be dissolved, but a cured product of the resin cannot be effectively removed. A cleaning solution containing an alkaline cleaner and a surfactant cannot sufficiently remove the filler / pigment, SBR latex, etc. in the deposit, and has not yet achieved a desired sufficient deposit cleaning effect. Therefore, in addition to these cleaning methods, physical deletion work is performed manually. Therefore, there is still a strong demand for an effective cleaning method.
Japanese Patent Laid-Open No. 62-21893 JP-A-8-246374 JP 2000-64069 A JP-A-5-177177 Japanese Utility Model Publication No. 5-52000 JP 2003-145020 A Japanese Unexamined Patent Publication No. 2006-00007

  The present invention relates to a deposit removing agent and a deposit removing method in a paper coat color coat coating process in the paper pulp manufacturing industry, and more specifically, without using acid cleaning, inorganic fillers and inorganic pigments such as calcium carbonate, and SBR. It is an object of the present invention to provide a deposit removing agent and a deposit removing method derived from a coating liquid containing a copolymer latex such as a system latex and an NBR system latex.

  The inventors relate to a deposit remover and a deposit removal method in a color coat coating process for papermaking. Specifically, without using acid washing, inorganic fillers and inorganic pigments such as calcium carbonate, SBR latex, NBR latex, and the like. As a result of earnest research on the agent and removal method for removing deposits derived from the coating liquid containing the copolymer latex, a specific aminocarboxylic acid, organic phosphonic acid, sodium hydroxide and / or potassium hydroxide, and The inventors have found that the combined use of hydrogen peroxide is effective and completed the present invention.

That is, the invention according to claim 1 includes (A) aminocarboxylic acid and its salt, (B) organic phosphonic acid and its salt, (C) sodium hydroxide and / or potassium hydroxide, and (D) hydrogen peroxide. the characterized in that it contains, papermaking color coat coating step of an inorganic filler and inorganic pigments and SBR latex, a deposit removing agent of the coating liquid containing a copolymer latex of NBR-based latex scan, (A) and (B) are contained at a weight ratio of 1: 4 to 4: 1, and (D) the amount of hydrogen peroxide is 0.1 to 10% by weight as an active ingredient of hydrogen peroxide. A deposit remover.

In the invention according to claim 2 , (A) the aminocarboxylic acid is ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethyleneiminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, dicarboxymethyl. glutamic acid, dihydroxy glycine, 1,3-diamino-2-hydroxy-tetraacetic deposit removal agent according to claim 1 Symbol placement papermaking color coat application step at least one member selected from acetic acid in a.

In the invention according to claim 3 , (B) the phosphonic acid is phosphonobutanetricarboxylic acid, hydroxyethylidene-1,1-diphosphonic acid, nitrilotrismethylenephosphonic acid, N, N, N ′, N′-tetrakis (phosphonomethyl) 3. A deposit remover for a paper coat color coat coating process according to claim 1 or 2 which is one or more selected from ethylenediamine.

The invention according to claim 4 is the color coat coating process for papermaking, wherein the cleaning liquid containing the deposit remover in the colorcoat coating process for papermaking according to any one of claims 1 to 3 is used in the colorcoat coating process for papermaking. It is the deposit removal method of the color coat coating process for paper manufacture characterized by making it distribute | circulate to.

The invention according to claim 5 is the deposit removal method in the paper coat color coat coating process according to claim 4 , wherein the pH of the cleaning liquid is 8-14.

The invention according to claim 6 is, in the color coat coating process for papermaking, (A) aminocarboxylic acid and its salt, (B) organic phosphonic acid and its salt, (C) sodium hydroxide and / or potassium hydroxide, and (D), characterized by using hydrogen peroxide, papermaking color coat application step mineral fillers and inorganic pigments and SBR latex, NBR based latex scan copolymer latex deposit of coating solution containing (A) and (B) are used at a weight ratio of 1: 4 to 4: 1, and the concentration of (D) hydrogen peroxide in the cleaning liquid is 0.1 wt. It is the deposit removal method which is 10 to 10 weight%.

The invention according to claim 7 is the deposit removing method in the paper coat color coat coating process according to claim 6 , wherein the pH at the time of deposit removing washing is 8 to 14.

In the invention according to claim 8 , (A) the aminocarboxylic acid is ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethyleneiminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, dicarboxymethyl. 8. The deposit removing method in a paper coat color coat coating process according to claim 6, wherein the deposit is one or more selected from glutamic acid, dihydroxyglycine, and 1,3-diamino-2-hydroxypropanetetraacetic acid.

In the invention according to claim 9 , (B) the phosphonic acid is phosphonobutanetricarboxylic acid, hydroxyethylidene-1,1-diphosphonic acid, nitrilotrismethylenephosphonic acid, N, N, N ′, N′-tetrakis (phosphonomethyl) 9) The deposit removing method in a paper coat color coat coating process according to any one of claims 6 to 8 , which is at least one selected from ethylenediamine.

  By applying the deposit removing agent and deposit removing method in the paper color coat coating process of the present invention, the coating liquid storage tank and the transfer pipe, coater, pump, and their auxiliary devices are coated by circulating the paper coating liquid. Deposits (fixed matter) generated by the adhesion and solidification of the liquid can be easily removed. In addition, the operational stoppage associated with deposit removal is shortened. Furthermore, since it becomes possible to completely remove the deposit, scratches on the coated paper surface caused by peeling off the remaining deposit and carrying it to the coater are eliminated, contributing to an improvement in the quality of the paper.

  The deposit remover in the paper color coat coating process of the present invention is a deposit produced by gradually adhering and solidifying the coating liquid in a coating liquid storage tank, a transfer pipe, and a coater of the papermaking coating liquid ( Specific (A) aminocarboxylic acid and salt thereof, (B) organic phosphonic acid and salt thereof, (C) sodium hydroxide and / or potassium hydroxide, and (D) hydrogen peroxide. A deposit remover for a paper coat color coat coating process.

  The deposit in the color coat coating process for papermaking of the present invention (hereinafter referred to as “deposit”) is a coating liquid storage tank, a transfer pipe, a coater, a pump, and their associated devices, etc. by circulating the coating liquid. This is a deposit (fixed matter) where the coating liquid gradually adheres and solidifies. A method for applying the coating liquid is not particularly limited, and examples thereof include a blade coater, a roll coater, and a gate roll coater.

  The said coating liquid is not specifically limited, It is a coating liquid for papermaking generally used. The coating liquid is generally a pigment such as kaolin, calcium carbonate, clay, satin white, talc, titanium oxide, aluminum hydroxide, silica, zinc oxide, activated clay, acid clay, silicon clay, plastic pigment, etc .; styrene-anhydrous maleic Acid copolymer, styrene-acrylic copolymer, styrene-butadiene copolymer, styrene-butadiene-acrylonitrile copolymer, (meth) acrylic acid-vinyl acetate copolymer, acrylic acid-methyl methacrylic acid copolymer, Synthetic binders such as methyl methacrylic acid-butadiene copolymer, butyl acrylic acid-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, isobutene-maleic anhydride copolymer; oxidized starch, etherified starch, Esterified starch, cationized starch, enzyme-modified starch Natural binders such as cold water soluble starch, casein, and soy protein obtained by flash drying them, pH adjusters such as sodium hydroxide and sodium carbonate; preservatives, water, and other lubricants and additives as needed It is a viscous slurry containing various auxiliary agents such as a sticking agent, a water retention agent, an antifoaming agent, a water resistance agent, and a coloring agent.

  Deposits include not only those derived from the above-mentioned coating liquid blends, but also those derived from pulp and paper components, blends and additives. For example, those derived from pulp and paper components and blends / additives include fibers and resins derived from pulp such as fatty acids, glycerides, lignins, terpenes, sterol compounds; rosin size, alkyl ketene dimers, alkenyl anhydrides Includes succinic acid and other sizing agents, acrylic acid polymers, urea-formaldehyde copolymers, melamine-formaldehyde copolymers, paper strength enhancers such as starch and cationized starch, and yield improvers; fine fibers, etc. . In addition, slime containing microorganisms such as bacteria and mold may be included.

  The (A) aminocarboxylic acid and salts thereof (hereinafter referred to as “(A) aminocarboxylic acids”) used in the present invention are aminocarboxylic acids and salts thereof that are soluble in neutral water or alkaline water. Specifically, ethylenediaminetetraacetic acid and its 1-4 sodium salt or potassium salt (EDTA · 1-4Na salt, EDTA · 1-4K salt), nitrilotriacetic acid and its 1-3 sodium salt or potassium salt (NTA · 1-3Na, NTA · 1-3K), hydroxyethyleneiminodiacetic acid and its 1-2 sodium salt or potassium salt (HIDA · 1-2Na, HIDA · 1-2K), hydroxyethylethylenediaminetriacetic acid and its 1-3 Sodium salt or potassium salt (HEDTA · 1-3Na, HEDTA · 1-3K), diethylenetriaminepentaacetic acid and its 1-5 sodium salt or potassium salt (DTPA · 1-5Na salt, DTPA · 1-5K salt), triethylene Tetraamine hexaacetic acid and its 1-6 sodium salt or potassium salt (TTHA · 1-6) a salt, TTHA · 1-6K salt), dicarboxymethylglutamic acid and its 1-4 sodium salt or potassium salt (GLDA · 1-4Na salt, GLDA · 1-4K salt), dihydroxyglycine and its sodium salt or potassium salt Propanediaminetetraacetic acid and its 1-4 sodium salt (PDTA · 1-4Na salt, PDTA · 1-4K salt), 1,3-diamino-2-hydroxypropanetetraacetic acid and its 1-4 sodium salt or potassium salt (DPTA-OH · 1-4Na salt, DPTA-OH · 1-4K salt) and the like. Ethylenediaminetetraacetic acid and its 1 to 4 sodium salt (EDTA · 1 to 4Na salt) are preferable. You may use these 1 type or in combination of 2 or more types.

  The (B) organic phosphonic acid and salts thereof (hereinafter referred to as “(B) organic phosphonic acids”) used in the present invention are organic phosphonic acids and salts thereof that are soluble in neutral water or alkaline water. Specifically, phosphonobutane tricarboxylic acid and its 1-5 sodium salt (PBTC · 1-5Na), phosphonobutane tricarboxylic acid and its 1-5 potassium salt (PBTC · 1-5K), hydroxyethylidene-1, 1-diphosphonic acid and its 1-4 sodium salt (HEDP · 1-4Na), hydroxyethylidene-1,1-diphosphonic acid and its 1-4 potassium salt (HEDP · 1-4K), nitrilotrismethylenephosphonic acid and its 1-6 sodium salt (NTP · 1-6Na), nitrilotrismethylenephosphonic acid and its 1-6 potassium salt (NTP · 1-6K), N, N, N ′, N′-tetrakis (phosphonomethyl) ethylenediamine and its 1-4 sodium salt (EDTMP · 1-4Na), N, N, N ′, N′-tetrakis (phos Nomechiru) ethylenediamine and the like 1-4 potassium salt (EDTMP · 1~4K) and the like. Preferred are hydroxyethylidene-1,1-diphosphonic acid and its 1-4 sodium salt (HEDP · 1-4Na), phosphonobutanetricarboxylic acid and its 1-5 sodium salt (PBTC · 1-5Na). You may use these 1 type or in combination of 2 or more types.

  (C) Sodium hydroxide and / or potassium hydroxide (hereinafter referred to as “(C) sodium hydroxide and the like”) used in the present invention is not particularly limited, and is commercially available sodium hydroxide or water. Either potassium oxide or a combination of sodium hydroxide and potassium hydroxide can be used.

  (D) Hydrogen peroxide (hereinafter referred to as “(D) hydrogen peroxide”) used in the present invention is not particularly limited, and commercially available hydrogen peroxide can be used. For example, there are a 35 wt% liquid product, a 50 wt% liquid product, a 60 wt% liquid product, and the like, and any of them may be used.

  The mixing ratio of (A) aminocarboxylic acids and (B) organic phosphonic acids in the deposit removing agent of the present invention is 20:80 to 80:20 by weight. The blending amounts of (A) aminocarboxylic acids and (B) organic phosphonic acids are each 0.1 wt% to 30 wt%, and the total amount of (A) aminocarboxylic acids and (B) organic phosphonic acids is 0. .2 wt% to 50 wt%. The compounding amount of (D) hydrogen peroxide in the deposit removing agent of the present invention is 0.1% by weight to 10% by weight as an active ingredient of hydrogen peroxide. (C) Sodium hydroxide and / or potassium hydroxide in the deposit removing agent of the present invention adjusts the final product pH of the deposit removing agent of the present invention containing (A) to (D) to 8 to 14. Blend in. Moreover, the water used for the deposit removing agent of the present invention is fresh water and / or pure water.

  The deposit remover in the present invention is a mixture of (A) aminocarboxylic acids, (B) organic phosphonic acids, (D) hydrogen peroxide while stirring water, and then (C) sodium hydroxide or the like is added. A method of adjusting the pH to 8-14, or (A) aminocarboxylic acids and (B) organic phosphonic acids were added and mixed while stirring water, and (C) the pH was adjusted to 8-14 with sodium hydroxide or the like. Then, it can prepare by the method of adding and mixing (D) hydrogen peroxide. However, in the preparation method in which (C) sodium hydroxide or the like is added and (D) hydrogen peroxide is added and mixed, it is confirmed that the final pH is 8 to 14, and the final pH is out of the range ( C) Add sodium hydroxide or the like to adjust the pH to be within this range.

  The deposit removing agent thus prepared is immediately circulated in the color coat coating process for papermaking where the deposit is generated using a chemical injection pump, and the cleaning liquid is circulated using a circulation pump to remove the deposit. To do. The deposit remover can be used by diluting it with water as appropriate in the color coat coating process for papermaking. The concentration of the deposit remover in the case of dilution is usually 1% to 50% by weight.

  The deposit removal method in the paper coat color coat coating process of the present invention includes (A) aminocarboxylic acid and its salt, (B) organic phosphonic acid and its salt, (C) sodium hydroxide and / or potassium hydroxide, and (D) A method for removing deposits in a paper coat color coat coating process characterized by using hydrogen peroxide.

  The addition ratio of (A) aminocarboxylic acids to (B) organic phosphonic acids in the deposit removal method of the present invention is appropriately determined in consideration of the desired deposit cleaning effect, and should be uniformly determined. However, the ratio of (A) aminocarboxylic acids to (B) organic phosphonic acids is usually 20:80 to 80:20, preferably 30:70 to 70:30, by weight. In addition, the concentrations of (A) aminocarboxylic acids and (B) organic phosphonic acids in the cleaning liquid using the deposit removing method of the present invention are not particularly limited, but each is usually 0.1% to 30% by weight, (A The total amount of aminocarboxylic acids and (B) organic phosphonic acids is usually 0.2 wt% to 50 wt%.

  The concentration of (D) hydrogen peroxide in the cleaning solution using the deposit removing method of the present invention is appropriately determined in consideration of the target deposit cleaning effect and cannot be uniformly determined. The active ingredient of hydrogen peroxide is 0.1 to 10% by weight. When (D) hydrogen peroxide at the time of deposit cleaning is less than 0.1% by weight, a sufficient effect may not be obtained from experience, and when hydrogen peroxide is contained by 10% by weight or more, rapid foaming may occur. Yes, not preferred.

  The water used for the deposit removing method of the present invention can be fresh water, industrial water, or process water, and is not particularly limited. In addition to water, a water-soluble organic solvent such as methanol, ethanol, dioxane, ethylene glycol or the like can be used as the solvent used for the deposit cleaning liquid.

  The pH in the cleaning solution using the deposit removing method of the present invention must be (D) alkaline in order to promote the decomposition of hydrogen peroxide, and (C) adjusted to pH 8 to 14 with sodium hydroxide or the like. More preferably, the pH is in the range of 9-13. If the pH is less than 8, (D) hydrogen peroxide is not sufficiently decomposed, and the effects of the present invention may not be obtained.

  In the deposit removal method of the present invention, (D) hydrogen peroxide in a state where the pH is maintained alkaline with sodium hydroxide or the like is decomposed by contacting with organic substances such as deposit, This effectively oxidizes and decomposes the cured product of the resin derived from the binder such as SBR latex contained in the resin, and further, the hydrogen peroxide that has entered the voids of the fine deposit is decomposed to generate fine oxygen gas. And (A) aminocarboxylic acids and (B) organic phosphonic acids, (D) suppresses the rapid decomposition of hydrogen peroxide, and calcium carbonate, which is a pigment. As a result, hard deposits are unraveled in a relatively short time, and very weak force (for example, pinched and crushed by fingers). Become crushed state), it is possible to easily removed. Moreover, peeling from the adhesion surface is facilitated. Moreover, the effect is maintained over a long period of cleaning time without finishing in a short time. Hereinafter, the deposit removal method of the present invention will be described in detail.

  In the deposit removal method of the present invention, water is poured into the paper coat color coat coating process in which deposit is generated, and (A) aminocarboxylic acids, (B) organic phosphonic acids, (C) sodium hydroxide, etc. (D) Add hydrogen peroxide solution. (A) to (D) are added by circulating water embedded in a paper color coat coating process using a circulation pump, and (A) aminocarboxylic acids, (B) organic phosphonic acids, (D ) After adding and mixing hydrogen peroxide, (C) A method of adjusting the pH to 8 to 14 by adding sodium hydroxide or the like, or water circulating in the paper coat color coat coating process, And (A) aminocarboxylic acids, (B) organic phosphonic acids, (C) sodium hydroxide and the like to adjust the pH to 8 to 14, and then (D) hydrogen peroxide is added and mixed. Any of the methods can be used. However, after (C) sodium hydroxide or the like is added and (D) hydrogen peroxide is added and mixed, it is confirmed that the final pH is 8 to 14, and if the final pH is out of the range (C ) Add sodium hydroxide or the like to adjust the pH to be within this range.

  In the color coat coating process for papermaking, the cleaning liquid is circulated with a circulation pump at a linear velocity of about 0.1 to 10 m / S, so that small pieces and particles of the deposit are peeled off from the loosened and soft deposit together with the cleaning liquid. The cleaning efficiency is enhanced by promoting the peeling and removal of other circulated and soft deposits. Moreover, you may make it soak in a washing | cleaning liquid for 6 to 12 hours, before circulating according to a condition.

  As the cleaning progresses, the pH of the cleaning solution decreases. Therefore, a deposit remover or (C) sodium hydroxide is additionally added so that the pH of the cleaning solution is appropriately measured and maintained at 8-14. When the pH of the cleaning liquid is less than 8, the effect of unraveling, peeling and dissolving the deposit is lowered, and the sufficient deposit removing effect of the present invention cannot be obtained.

  In the deposit removing method of the present invention, the cleaning liquid is heated to about 30 ° C. to 80 ° C. with a heater or the like, whereby the cleaning efficiency is increased and the cleaning time is shortened. The temperature of the cleaning liquid is appropriately determined in consideration of the content of the target deposit, the status of the cleaning process, and the cleaning effect of the target deposit, and cannot be determined uniformly. ° C. Preferably it is 40 to 65 degreeC. If the temperature of the cleaning solution is low, the cleaning effect may not be sufficiently exerted. In addition, if the temperature of the cleaning liquid exceeds 80 ° C., the cleaning effect is enhanced, but there are cases where it is not preferable because of the high work risk caused by using a highly alkaline cleaning liquid and the corrosive problem of the apparatus to be cleaned. is there.

  The cleaning time cannot be determined uniformly depending on the deposit generation status, the composition of the deposit, the circulating amount and pH of the cleaning liquid, and the cleaning liquid temperature. Good. The situation of deposit cleaning can be easily judged by the amount of suspended matter SS (JIS K0102 suspended matter and evaporation residue) in the washing solution. If the cleaning is sufficiently performed, the SS content of the cleaning liquid gradually increases with time, and the degree of increase is reduced, and the cleaning may be terminated when it reaches a substantially constant value. With the cleaning liquid using the deposit removing method of the present invention, the deposit is easily unraveled and easily removed. Then, the deposit which peeled off by flowing clean water or the deposit which was removed and floated or settled is removed.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.
[(A) Aminocarboxylic acids]
A-1: Ethylenediaminetetraacetic acid (EDTA)
A-2: Ethylenediaminetetraacetic acid, disodium salt (EDTA.2Na)
A-3: Ethylenediaminetetraacetic acid, tetrasodium salt (EDTA, 4Na)
A-4: Ethylenediaminetetraacetic acid, 4 potassium salt (EDTA, 4K)
A-5: Nitrilotriacetic acid (NTA)
A-6: nitrilotriacetic acid, trisodium salt (NTA, 3Na)
A-7: Hydroxyethyleneiminodiacetic acid (HIDA)
A-8: Hydroxyethylethylenediaminetriacetic acid (HEDTA)
A-9: Diethylenetriaminepentaacetic acid pentasodium salt (DTPA · 5Na)
A-10: Triethylenetetraamine hexaacetic acid, 6 sodium salt (TTHA, 6Na)
A-11: Dicarboxymethyl glutamic acid, tetrasodium salt (GLDA, 4Na)
A-12: Dihydroxyglycine sodium salt A-13: Propanediaminetetraacetic acid, tetrasodium salt (PDTA, 4Na)
A-14: 1,3-diamino-2-hydroxypropanetetraacetic acid, tetrasodium salt (DPTA-OH, 4Na)

[(B) Phosphonocarboxylic acids]
B-1: Phosphonobutanetricarboxylic acid (PBTC)
B-2: Phosphonobutanetricarboxylic acid · 3Na (PBTC · 3Na)
B-3: Phosphonobutanetricarboxylic acid · 3K (PBTC · 3K)
B-4: Hydroxyethylidene-1,1-diphosphonic acid (HEDP)
B-5: Hydroxyethylidene-1,1-diphosphonic acid · 4Na (HEDP · 4Na)
B-6: nitrilotrismethylenephosphonic acid hexasodium salt (NTP 6Na)
B-7: N, N, N ′, N′-tetrakis (phosphonomethyl) ethylenediamine tetrasodium salt (EDTMP · 4Na)

[Deposit removal test-1]
Coating liquid (kaolin, calcium carbonate as pigment; styrene-butadiene copolymer as binder, polyvinyl alcohol; sodium hydroxide, sodium carbonate as pH adjuster; preservative, water, xanthan gum (thickener), water retention agent, The deposit derived from the coating liquid adhered and solidified to the inner wall of the transfer pipe from the storage tank (including antifoaming agent etc.) was peeled off with a hammer, cut into a square of about 10 g, and used as a sample for a cleaning test. Add predetermined amounts of (A) aminocarboxylic acids, (B) organic phosphonic acids, and (D) hydrogen peroxide to 300 mL of warm water (50 ° C.), and then adjust to pH 13.0 with (C) sodium hydroxide and the like. A deposit remover was prepared and placed in a 500 mL beaker. This was put into a constant temperature water bath at 50 ° C. and kept warm. The sample was placed on a cage made of 60 mesh stainless steel wire mesh and continuously stirred with a magnetic stirrer for 2 hours. Deposits that were peeled off the square sample and dropped from the eyes of the cage under stirring were considered washed away. After 2 hours, the deposit remaining on the wire mesh was taken out, dried at 105 ° C., weighed, and the percentage of weight loss with respect to the original sample was defined as the cleaning rate (%). The higher the washing rate, the better. Moreover, the state when the deposit remaining after the test was crushed with a finger was evaluated in three stages of ○, Δ, and ×. Here, ◯ indicates a soft and easily crushed state, Δ indicates a slightly soft but not easily crushed state, and × indicates a hard state. In this case, it is preferable to show a soft and easily crushable state. Table 1 shows the results of various (A) aminocarboxylic acids and (B) organic phosphonic acids.

  The (A) aminocarboxylic acids, (B) organic phosphonic acids, (C) sodium hydroxide, and the like (D) hydrogen peroxide-containing deposit remover and deposit removal method of the present invention have a cleaning rate of 57.1%. Although the cleaning rate is as high as -85.6%, the cleaning rate is as low as 13.6% to 18.1% when used alone (for example, Comparative Examples 3 to 5). (A) Aminocarboxylic acids When (B) and organic phosphonic acid are used in combination, the cleaning rate is 31.2%, and (A) any of aminocarboxylic acids and (B) organic phosphonic acids and (D) hydrogen peroxide is used together, the cleaning rate is 34.1%. It is understood that the deposit removing agent and the deposit removing method of the present invention exhibit a very excellent cleaning / removing effect.

[Deposit removal test-2]
Coating liquid (kaolin, calcium carbonate as pigment; styrene-butadiene copolymer as binder, polyvinyl alcohol; sodium hydroxide, sodium carbonate as pH adjuster; preservative, water, xanthan gum (thickener), water retention agent, The transfer piping from the coating liquid storage tank with the solidified deposits (including antifoaming agent etc.) attached to the inner wall was removed from the actual apparatus and cut into five equal parts to prepare transfer piping samples. Five circulatory systems, each incorporating the transfer pipe sample, were installed independently in a circulatory system equipped with a tank and a circulation pump. Water is added to the circulation system and circulated using a circulation pump, and a predetermined amount of (A) aminocarboxylic acids, (B) organic phosphonic acids, and (D) hydrogen peroxide are added and mixed with the amount of water held in the circulation system. Then, (C) the solution in the system was adjusted to pH 13.0 with sodium hydroxide or the like, and the circulation was continued at 50 ° C. for 3 hours as Example 31. On the other hand, in Example 32, water was added to the circulation system and circulated using a circulation pump, and predetermined amounts of (A) aminocarboxylic acids and (B) organic phosphonic acids were added to the amount of water held in the circulation system. Further, (C) the solution in the system is adjusted to about pH 13 with sodium hydroxide, etc., (D) hydrogen peroxide is added and mixed, and the pH of the solution in the system is further adjusted to pH 13. In this example, after the final adjustment to 0, circulation was continued at 50 ° C. for 3 hours. Moreover, using the same addition order and test method as Example 31, (C) and (D), (A) and (B) and (D), and (B) and (C) and (D) are combined. The example was used as a comparative example. In each example, after the circulation was completed, the cleaning liquid was drained and fresh water was passed, and then the transfer piping sample was removed from the circulation system and the inside was inspected. The state of the deposit inside the transfer pipe sample was evaluated by ○ and ×. Here, ◯ indicates a state where most of the deposit is removed, and x indicates a state where most of the deposit remains. The test results are shown in Table 2.

  The deposit attached to the inner wall of the transfer pipe sample by the deposit removal method using (D) hydrogen peroxide such as (A) aminocarboxylic acids, (B) organic phosphonic acids, (C) sodium hydroxide, etc. of the present invention is Mostly removed, it can be seen that the deposit removing method of the present invention exhibits a very excellent cleaning and removing effect.

  INDUSTRIAL APPLICABILITY The present invention can be used to remove deposits that become an obstacle in the coating process of a paper / pulp manufacturing factory.

Claims (9)

Papermaking comprising (A) aminocarboxylic acid and salt thereof, (B) organic phosphonic acid and salt thereof, (C) sodium hydroxide and / or potassium hydroxide, and (D) hydrogen peroxide use color coat coating step of an inorganic filler and inorganic pigments and SBR latex, a deposit removing agent of the coating liquid containing a copolymer latex of NBR-based latex scan, the (a) and (B) 1: A deposit remover that is contained in a weight ratio of 4 to 4: 1 and (D) the amount of hydrogen peroxide is 0.1 to 10% by weight as an active ingredient of hydrogen peroxide.   (A) Aminocarboxylic acid is ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethyleneiminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, dicarboxymethylglutamic acid, dihydroxyglycine, 1,3 The deposit remover for a paper coat color coat coating process according to claim 1, wherein the deposit remover is at least one selected from diamino-2-hydroxypropanetetraacetic acid.   (B) One type of phosphonic acid selected from phosphonobutanetricarboxylic acid, hydroxyethylidene-1,1-diphosphonic acid, nitrilotrismethylenephosphonic acid, N, N, N ′, N′-tetrakis (phosphonomethyl) ethylenediamine The deposit remover in the color coat coating process for papermaking according to claim 1 or 2 as described above.   In the papermaking color coat coating process, the cleaning liquid containing the deposit remover in the papermaking color coat coating process according to any one of claims 1 to 3 is distributed to the papermaking color coat coating process. Deposit removal method for paper coat color coat application process.   The method for removing deposits in a color coat coating process for papermaking according to claim 4, wherein the pH of the cleaning liquid is 8 to 14. In the color coat coating process for papermaking, (A) aminocarboxylic acid and salt thereof, (B) organic phosphonic acid and salt thereof, (C) sodium hydroxide and / or potassium hydroxide, and (D) hydrogen peroxide. which comprises using, papermaking color coat coating step of an inorganic filler and inorganic pigments and SBR latex, a coating solution deposit removal method comprising the copolymer latex of the NBR type latex scan, (a ) And (B) in a weight ratio of 1: 4 to 4: 1, and the concentration of (D) hydrogen peroxide in the cleaning liquid is 0.1% to 10% by weight as an active ingredient of hydrogen peroxide. Removal method.   The method for removing deposits in a paper coat color coat coating process according to claim 6, wherein the pH during deposit removal washing is 8-14.   (A) Aminocarboxylic acid is ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethyleneiminodiacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, dicarboxymethylglutamic acid, dihydroxyglycine, 1,3 The method for removing deposits in the paper coat color coat coating process according to claim 6 or 7, wherein the deposit is one or more selected from diamino-2-hydroxypropanetetraacetic acid. (B) One type of phosphonic acid selected from phosphonobutanetricarboxylic acid, hydroxyethylidene-1,1-diphosphonic acid, nitrilotrismethylenephosphonic acid, N, N, N ′, N′-tetrakis (phosphonomethyl) ethylenediamine The method for removing a deposit in a paper coat color coat coating process according to any one of claims 6 to 8.