JP5391051B2 - Deposit removal method - Google Patents

Description

  The present invention relates to a deposit removal method in an apparatus for producing an aqueous pigment dispersion that is suitably used for ink jet recording ink. Specifically, when manufacturing two or more water-based pigment dispersions using different raw materials using a single manufacturing apparatus, a method for removing deposits from the manufacturing apparatus at the time of color change or product type switching, and cleaning of the manufacturing apparatus The present invention relates to a method for removing deposits at difficult places or places where deposits are firmly attached.

  The ink jet recording method is a recording method in which characters and images are obtained by directly ejecting and attaching ink droplets from very fine nozzles onto a recording member. This method has many advantages such as easy full colorization, low cost, the ability to use plain paper as a recording member, and non-contact with the printed material. . In addition, environmentally friendly water-based inks are preferred for ink jet recording inks. Therefore, various water-soluble dyes or pigments are dissolved in water-based ink media of water or a mixed solvent of water and an organic solvent. Those in the form of dispersed water-based pigment dispersions are widely used.

  By the way, when manufacturing an aqueous pigment dispersion, many processes, such as a mixing process, a dispersion | distribution process, a concentration process, and an adjustment process which adds various additives, are required. And in each of these processes, the deposit | attachment containing a pigment, a dispersing agent, etc. adheres to the tank inner wall, a stirrer, piping, etc. of a manufacturing apparatus. When two or more types of water-based pigment dispersions using different raw materials are manufactured using a single manufacturing apparatus, if there are deposits of one type of product remaining in the manufacturing apparatus, There is a risk that the product may be contaminated, whereby the aqueous pigment dispersion as the product may not exhibit the predetermined performance. Therefore, when two or more types of water-based pigment dispersions are manufactured using one manufacturing apparatus, the water-based pigment dispersion is manufactured after the manufacture of one type of product is completed and before the product of another type is manufactured. It is necessary to clean the manufacturing apparatus and remove the deposits.

  Therefore, as a cleaning method of such an aqueous pigment dispersion manufacturing apparatus, Patent Documents 1 and 2 use a cleaning agent or an alkaline agent containing an organic solvent in combination, or increase the cleaning property by defining the cleaning order. Is disclosed.

JP 2008-75023 A JP 2008-178842 A

  However, with the cleaning methods disclosed in Patent Documents 1 and 2, it is difficult to sufficiently remove deposits from the manufacturing apparatus.

  An object of the present invention is to efficiently remove deposits from an aqueous pigment dispersion manufacturing apparatus.

  The present invention relates to a method for removing deposits in an apparatus for producing an aqueous pigment dispersion containing a pigment, an acid-type water-insoluble polymer as a dispersant, and a neutralizing agent, and a portion to which deposits due to the aqueous pigment dispersion adhere After the liquid is contacted with acid, the deposits are removed from the portion.

  According to the present invention, after the acid is in contact with the portion where the deposit due to the aqueous pigment dispersion has adhered, the deposit is removed from the portion, thereby efficiently removing the deposit from the aqueous pigment dispersion manufacturing apparatus. can do.

It is a figure which shows the structure of an aqueous pigment dispersion manufacturing apparatus. (A) Vertical cross-sectional photograph of piping of water-based pigment dispersion manufacturing apparatus, (b) Partial enlarged electron micrograph of piping with no deposits inside, and (c) Portion of piping with deposits inside It is an enlarged electron micrograph. (A) Surface photograph of test piece before rubbing with sponge, (b) Surface photograph of test piece after rubbing with sponge, and (c) Surface photograph of sponge after rubbing. It is (a) the surface photograph of the test piece before washing | cleaning in the deposit | attachment removal test 2, and (b) the surface photograph of the test piece after washing | cleaning. (A) The surface photograph of the test piece before washing | cleaning in the deposit | attachment removal test 3, and (b) The surface photograph of the test piece after washing | cleaning. (A) The surface photograph of the test piece before washing | cleaning in the deposit | attachment removal test 4, and (b) The surface photograph of the test piece after washing | cleaning. It is (a) the surface photograph of the test piece before washing | cleaning in the deposit | attachment removal test 5, and (b) the surface photograph of the test piece after washing | cleaning.

  Hereinafter, embodiments will be described in detail.

(Water-based pigment dispersion manufacturing equipment)
<Basic configuration>
FIG. 1 shows an example of an aqueous pigment dispersion manufacturing apparatus 10 according to this embodiment.

  The water-based pigment dispersion manufacturing apparatus 10 according to this embodiment is provided with a preliminary dispersion tank 11, a concentration tank 12, and a productization tank 13 in order from the raw material supply side to the product recovery side.

  A raw material supply unit 14 is provided at the inlet 11 a at the top of the preliminary dispersion tank 11.

  A circulation pipe 15 extends from the discharge port 11b at the bottom of the preliminary dispersion tank 11 and is connected to the reinlet 11c at the top of the tank. The circulation pipe 15 is provided with a liquid feed pump 16 and a bead mill 17 in this order. A branch pipe 18 extends from a portion of the circulation pipe 15 between the pump 16 and the bead mill 17 and is connected to the inlet 12 a at the upper part of the concentration tank 12.

  A concentrate circulation pipe 19 extends from the outlet 12 b at the bottom of the tank 12 and is connected to the inlet 13 a at the top of the product tank 13. A filtration filter 20 is interposed in the concentrated liquid circulation pipe 19.

  A recovery pipe 21 extends from the outlet 13 b at the bottom of the product tank 13 and is connected to the product recovery unit 22.

  Each of the pre-dispersion tank 11, the concentration tank 12, and the productization tank 13 includes a stirrer having a stirring blade and a jacket for temperature control. The capacity | capacitance of the preliminary dispersion tank 11 is 300-2000L, the capacity | capacitance of the concentration tank 12 is 300-2000L, for example, and the capacity | capacitance of the product tank 13 is 300-2000L, for example.

  Using this water-based pigment dispersion manufacturing apparatus 10, 200 to 1500 L of water-based pigment dispersion can be manufactured per batch.

<Locations where it is difficult to remove deposits from the water-based pigment dispersion manufacturing apparatus>
In the water-based pigment dispersion manufacturing apparatus 10, deposits due to the water-based pigment dispersion occur at every corner. Among the places where it is difficult to remove the deposits, for example, the preliminary dispersion tank 11, the concentration tank 12, and the The joint between the stirring shaft and the stirring blade in each of the commercialization tanks 13, bolts and bolt holes for fixing them; the circulation pipe 15, the branch pipe 18, the concentrated liquid circulation pipe 19, and the recovery pipe 21 have fine surfaces. Uneven portion, bent portion, branching portion, connecting portion, and reservoir portion; inside of liquid feed pump 16, suction port, and discharge port; inside of bead mill 17, dispersion medium, and small diameter pipe connected to bead mill 17; filtration filter 20 and the eyes of the filtration filter 20 and the like.

<Materials used for members of water-based pigment dispersion manufacturing apparatus>
In the water-based pigment dispersion manufacturing apparatus 10 used industrially, each tank of the pre-dispersion tank 11, the concentration tank 12, and the productizing tank 13 in which the deposits of the water-based pigment dispersion are generated, the circulation pipe 15, and the branch are formed. In general, the pipe 18, the concentrate flow pipe 19, and the recovery pipe 21 are made of stainless steel such as SUS304 or SUS316. Of these tanks, tanks that have been subjected to surface finishing treatment by polishing such as # 320 finishing or # 400 finishing are often used. However, for piping, surface finishing treatment by polishing is particularly performed from a cost standpoint. It is rare that used ones or sanitary ones are used. Therefore, the piping of the aqueous pigment dispersion manufacturing apparatus 10 usually has fine irregularities on the surface as shown in FIGS. 2 (a) to 2 (c) (FIG. 2 (b)). Deposits due to the aqueous pigment dispersion adhere densely (FIG. 2 (c)). However, according to the deposit removal method of this embodiment described later, No. 1 finishing, 2D finish or No. Even a stainless steel member that has been subjected to a surface finishing treatment such as 2B finishing can efficiently remove deposits.

(Raw material for aqueous pigment dispersion)
The water-based pigment dispersion manufactured by the water-based pigment dispersion manufacturing apparatus 10 includes a raw material, a pigment, an acid-type water-insoluble polymer as a dispersant, a neutralizer, and water or water and a water-soluble organic as a dispersion medium. Including mixed solvent with solvent. In addition, the water-based pigment dispersion may further contain an antiseptic / antifungal agent.

<Pigment>
Examples of the pigment include organic pigments and inorganic pigments.

  Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.

  The hue of the organic pigment is not particularly limited, and examples thereof include chromatic pigments such as a red organic pigment, a yellow organic pigment, a blue organic pigment, an orange organic pigment, and a green orange organic pigment.

  Specific examples of preferable organic pigments include C.I. I. Pigment Yellow 13, 17, 74, 83, 97, 109, 110, 120, 128, 139, 151, 154, 155, 174, 180; I. Pigment Red 48, 57: 1, 122, 146, 176, 184, 185, 188, 202; I. Pigment violet 19, 23; C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 16, 60; I. Pigment Green 7, 36, etc.

  Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Among these, carbon black is particularly preferable for black water-based ink. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.

  The pigment may be composed of a single type of organic pigment or inorganic pigment, may be composed of a plurality of types of organic pigment and / or inorganic pigment, and in addition to the organic pigment and / or inorganic pigment. If necessary, an extender pigment may be included.

  Examples of extender pigments include silica, calcium carbonate, and talc.

  The content of the pigment is preferably 0.5 to 24% by mass and more preferably 1.5 to 20% by mass with respect to the aqueous pigment dispersion.

<Dispersant>
The dispersant contains an acid form of a water-insoluble polymer.

  Here, in this specification, the “water-insoluble polymer” means a polymer having a dissolution amount of 10 g or less when dried in 100 g of water at 25 ° C. after being dried at 105 ° C. for 2 hours. . In the present specification, the “acid-type water-insoluble polymer” means a water-insoluble polymer having an acid-type substituent of an anionic group such as a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group.

  Acid-type water-insoluble polymer as a dispersant has a solubility of 5 g or less when neutralized with sodium hydroxide, dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C. Are preferred, and those of 1 g or less are more preferred.

  Examples of the acid-type water-insoluble polymer include water-insoluble vinyl polymers, water-insoluble ester polymers, and water-insoluble urethane polymers each containing an anionic group. Among these, a water-insoluble vinyl polymer containing an anionic group is preferable from the viewpoint of the stability of the aqueous pigment dispersion.

  A more specific example of the acid-type water-insoluble polymer is a water-insoluble graft polymer from the viewpoint of developing a sufficient printing density, and the main chain is at least an anionic group-containing monomer (a) [hereinafter (a ) Component] and a polymer chain comprising an aromatic ring-containing (meth) acrylate monomer (b) [hereinafter referred to as component (b)], and the side chain is at least a hydrophobic monomer ( c) A polymer chain containing a structural unit derived from [hereinafter referred to as component (c)] is preferred. Further, the main chain may contain a nonionic (meth) acrylate monomer (d) [hereinafter referred to as component (d)] as necessary.

  It is considered that the mobility of the anionic group can be enhanced by the main chain of the acid-type water-insoluble polymer containing the structural unit derived from the component (a) and the structural unit derived from the component (b). As a result, when the ink using the produced aqueous pigment dispersion is ejected from the nozzle onto the dedicated paper (photographic paper, glossy paper), the cohesiveness of the anionic group is alleviated, and thus the printing (printing) surface It is considered that the smoothness of the paper increases and the gloss and scratch resistance of the printed matter (printed matter) improve.

  Examples of the anionic group-containing monomer that is component (a) include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, and unsaturated phosphoric acid monomers.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid.

  (B) As a structural unit derived from a component, what has a structural unit represented by following formula (1) is mentioned, for example.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² has an arylalkyl group having 7 to 22 carbon atoms, preferably 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, or a substituent thereof. Or an aryl group having 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 to 12 carbon atoms, or a substituent thereof.

Specific examples of R ² include a benzyl group, a phenethyl group (phenylethyl group), a phenoxyethyl group, a diphenylmethyl group, and a trityl group. The arylalkyl group or the substituent that the aryl group may have may contain a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Specific examples of the substituent include an alkyl group having 1 to 9 carbon atoms, an alkoxy group, an acyloxy group, a hydroxyl group, an ether group, an ester group, and a nitro group.

The structural unit represented by the formula (1) can be obtained by polymerizing a monomer represented by the following formula (2).
CH ₂ = CR ¹ COOR ² (2)
(In the formula, R ¹ and R ² are the same as the above formula (1).)
Specifically, examples of the compound represented by the formula (2) include benzyl (meth) acrylate, phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, and 1-naphthalene. Acrylate, 2-naphthalyl (meth) acrylate, phthalimidomethyl (meth) acrylate, p-nitrophenyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxy Examples thereof include propyl phthalate and 2-acryloyloxyethyl phthalate. Of these, benzyl (meth) acrylate is preferred. The compound represented by Formula (2) may be comprised by single type, and may be comprised by multiple types.

  When the water-insoluble graft polymer contains a structural unit derived from the hydrophobic monomer (c) in the side chain, the water-insoluble graft polymer particles can be sufficiently contained in the water-insoluble graft polymer particles to improve the printing density.

  Examples of the hydrophobic monomer as component (c) include vinyl monomers, and styrene monomers are particularly preferable. Examples of the styrene monomer include styrene, α-methylstyrene, vinyltoluene, and the like. Among these, styrene is preferable. A side chain containing a structural unit derived from a styrenic monomer can be obtained by copolymerizing a styrenic macromer having a polymerizable functional group at one end (hereinafter referred to as a styrenic macromer). The styrenic macromer is preferably one having a number average molecular weight of 1,000 to 10,000 from the viewpoint of improving the adsorption performance to the pigment and improving the storage stability and keeping the viscosity of the aqueous pigment dispersion low. Some are more preferred.

  The content of the structural unit derived from the component (c) in the side chain is preferably 60% by mass or more from the viewpoint of sufficiently containing the pigment in the water-insoluble graft polymer particles and improving the printing density. More preferably, it is more than 90 mass%, and it is especially preferable that it is 90 mass% or more.

  The weight average molecular weight of the acid-type water-insoluble polymer is preferably 90000-400000 from the viewpoints of pigment dispersion stability, water resistance, dischargeability, and the like. The weight average molecular weight of the acid-type water-insoluble polymer was determined by gel chromatography using dimethylformamide in which 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide were dissolved as a solvent, and polystyrene as a standard substance. Can be measured.

  The dispersant may be composed of a single species or a plurality of species.

  The content of the dispersant is preferably 0.2 to 15% by mass, and more preferably 0.6 to 12.5% by mass with respect to the aqueous pigment dispersion.

<Neutralizing agent>
The neutralizing agent includes a base that neutralizes the acid-type water-insoluble polymer.

  Examples of the neutralizing agent base include lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, trimethylamine, and triethanolamine. The degree of neutralization of the salt-forming group of the neutralizer is preferably 10 to 400%, more preferably 30 to 250%.

Here, the degree of neutralization can be determined by the following equation.
Degree of neutralization = A / B × 100
A = [mass of neutralizing agent (g) / equivalent of neutralizing agent]
B = [Polymer acid number (KOHmg / g) × Polymer mass (g) / (56 × 1000)]
The acid value can be calculated from the polymer structural unit. Alternatively, it can also be determined by a method in which a polymer is dissolved in a suitable solvent (for example, methyl ethyl ketone) and titrated.

<Dispersion medium>
The dispersion medium is water or a mixed solvent of water and a water-soluble organic solvent.

  Examples of the water-soluble organic solvent in the mixed solvent include glycerin, propylene glycol, and polyethylene glycol, which are polyhydric alcohols as a wetting agent and a viscosity modifier.

  The content of the dispersion medium is preferably an amount such that the solid content concentration of the aqueous pigment dispersion is 1 to 30% by mass, and preferably 3 to 25% by mass, from the viewpoint of printing density, ejection stability and the like. It is more preferable that

<Antiseptic / antifungal agent>
As an antiseptic / antifungal agent, it has good compatibility with the dispersion medium, and does not cause white turbidity, alteration, thickening, or gelation when mixed or diluted, and is stable to heat and pH. Preferred are, for example, isothiazole derivatives such as 1,2-benzisothiazolin-3-one (trade name: Proxel).

  The content of the antiseptic / antifungal agent is preferably 50 to 2000 mg / kg from the viewpoint of antiseptic performance with respect to the aqueous pigment dispersion or the aqueous ink of the final product.

<Optional component>
In addition, the water-based pigment dispersion may contain an antifoaming agent, a chelating agent, and the like.

(Production of water-based pigment dispersion)
By charging the raw material from the raw material supply unit 14 of the water-based pigment dispersion manufacturing apparatus 10 described above, the preliminary dispersion process in the preliminary dispersion tank 11, the dispersion process in the preliminary dispersion tank 11, the circulation pipe 15, etc., the concentration tank 12 The water-based pigment dispersion, which is a product, is manufactured through the concentrating step in FIG. 1 and the sterilizing step in the productification tank 13 in order, and recovered in the product recovery unit 22. The antiseptic / antifungal agent is preferably added in the sterilization step.

(Adherent removal method in water-based pigment dispersion manufacturing apparatus)
After the water-based pigment dispersion manufacturing apparatus 10 manufactures the water-based pigment dispersion, deposits due to the water-based pigment dispersion firmly adhere to each tank and each pipe. Here, the deposit by the aqueous pigment dispersion is a film-like solid composed of a composition obtained by removing the dispersion medium from the aqueous pigment dispersion.

  Hereinafter, the deposit removal method in the aqueous pigment dispersion manufacturing apparatus 10 according to the present embodiment will be described.

  In the deposit removal method in the aqueous pigment dispersion manufacturing apparatus 10 according to the present embodiment, in order to reduce the amount of solvent used, washing is performed step by step in the order of a water washing step, an acid contact step, a washing step, and a rinse water washing step. . This procedure is also effective for disassembly and cleaning when performing regular maintenance or parts replacement.

  Moreover, in the deposit removal method in the aqueous pigment dispersion manufacturing apparatus 10 according to the present embodiment, the liquid circulation mechanism of the aqueous pigment dispersion manufacturing apparatus 10 is operated, and water or deposit removal liquid agent is recovered from the raw material supply unit 14. It distribute | circulates to each tank and each piping to the part 22. FIG. Thereby, the deposit removal from the aqueous pigment dispersion manufacturing apparatus 10 can be performed efficiently. At this time, from the viewpoint of enhancing the removal effect, it is preferable to operate the stirrer of each tank to generate a stirring flow.

<Washing process>
First, the liquid distribution mechanism of the water-based pigment dispersion manufacturing apparatus 10 is operated, and water is supplied from the raw material charging unit 14 so that water is distributed to each tank and each pipe from the raw material supply unit 14 to the product recovery unit 22. .

  You may make water contain an antifoamer etc. The water temperature is preferably 10 to 70 ° C. It is preferable that the amount of water used for one washing is an amount that fills the water in accordance with the capacity of the aqueous pigment dispersion manufacturing apparatus 10. The water flow rate is preferably 0.01 to 50 m / s. This washing with water may be performed only once, or may be repeated a plurality of times (for example, 2 to 5 times).

  In the case of disassembly and cleaning for regular maintenance or the like, washing may be performed for each part to the extent that thick coloring due to the aqueous pigment dispersion is eliminated from the washed water by dipping, dipping, or passing water.

<Acid contact process>
After washing with water, the aqueous acid solution is supplied from the raw material charging unit 14, whereby the aqueous acid solution is circulated through each tank and each pipe from the raw material supply unit 14 to the product recovery unit 22. By this operation, the acid is brought into contact with the portion of the aqueous pigment dispersion manufacturing apparatus 10 where the deposits due to the aqueous pigment dispersion are attached.

  Examples of the acid include strong acids such as sulfuric acid, nitric acid, and hydrochloric acid, and weak acids such as citric acid, phosphoric acid, lactic acid, boric acid, and carbonic acid. From the viewpoint of promoting salt exchange for returning the water-insoluble polymer to the acid form, it is preferable to use a strong acid. Here, “strong acid” means an acid dissociation index pK of 3 or less. The acid included in the acid aqueous solution may be a single species or a plurality of species.

  The acid aqueous solution is preferably a low-concentration aqueous solution from the viewpoint of the corrosion resistance of the device material and the safety of handling the acid. For example, in the case of a strong acid, the acid aqueous solution is preferably 5 N or less. The temperature of the aqueous acid solution is preferably 10 to 70 ° C. The amount of the acid aqueous solution used for one acid contact liquid is preferably set to an amount that fills the water in accordance with the capacity of the aqueous pigment dispersion manufacturing apparatus 10. The flow rate of the aqueous acid solution is preferably 0.01 to 50 m / s. The acid contact time is preferably 10 seconds or longer. This acid contact liquid may be performed only once, or may be repeated a plurality of times (for example, 2 to 5 times).

<Washing process>
Subsequent to the acid contact liquid, the deposit removing liquid agent is supplied from the raw material charging unit 14, whereby the deposit removing liquid agent is circulated through each tank and each pipe from the raw material supplying unit 14 to the product recovery unit 22.

  Examples of the deposit removing liquid agent include a cleaning agent containing an organic solvent having 6 to 12 carbon atoms, an organic solvent having 1 to 5 carbon atoms, and water. Of these, it is preferable to use a cleaning agent containing an organic solvent having 6 to 12 carbon atoms and / or an organic solvent having 1 to 5 carbon atoms.

  The cleaning agent containing an organic solvent having 6 to 12 carbon atoms may be the organic solvent itself having 6 to 12 carbon atoms, or may be obtained by diluting an organic solvent having 6 to 12 carbon atoms with a solvent. .

Examples of the organic solvent having 6 to 12 carbon atoms include glyceryl ether solvents such as monoalkyl glyceryl ether; ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether and the like. Examples include glycol solvents. Of these, glyceryl ether represented by the following formula (3) is preferable. R of the glyceryl ether represented by the formula (3) is preferably an alkyl group or an alkenyl group, and preferably an alkyl group having 1 to 9 carbon atoms, particularly 3 to 7 carbon atoms.
R—OCH ₂ CH (OH) CH ₂ OH (3)
The organic solvent having 6 to 12 carbon atoms included in the cleaning agent may be a single type or a plurality of types.

  Examples of the solvent for diluting the organic solvent having 6 to 12 carbon atoms with a solvent include water. The dilution rate is preferably 2 to 200 times, and more preferably 4 to 100 times.

  In addition, the detergent containing an organic solvent having 6 to 12 carbon atoms may contain a surfactant, a builder, an alkali agent, an antifoaming agent, etc., and the detergent containing an organic solvent having 6 to 12 carbon atoms. For example, a liquid detergent composition described in JP-A-11-189796 can be used.

  Examples of the organic solvent having 1 to 5 carbon atoms include ketones such as methyl ethyl ketone (MEK) and methyl isobutyl ketone; alcohols such as methanol, ethanol and isopropyl alcohol; nitrogen-containing organic compounds such as nitriles, amines and amides. Is mentioned. Of these, ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used. The organic solvent included in the organic solvent having 1 to 5 carbon atoms may be a single type or a plurality of types.

  In addition, the organic solvent having 1 to 5 carbon atoms may contain an antifoaming agent or the like.

  When a cleaning agent containing an organic solvent having 6 to 12 carbon atoms and / or an organic solvent having 1 to 5 carbon atoms is used as a deposit removing liquid agent, cleaning may be performed with only one of them, or both of them. You may wash with. When cleaning is performed with both a cleaning agent containing an organic solvent having 6 to 12 carbon atoms and an organic solvent having 1 to 5 carbon atoms, either of the cleaning may be performed first, and cleaning may be performed once to several times. May be performed alternately.

  The temperature of the deposit removing liquid is preferably 10 to 70 ° C. The amount of the deposit removing liquid used for one washing is preferably set to an amount that fills the water in accordance with the capacity of the aqueous pigment dispersion manufacturing apparatus 10. The average flow rate of the deposit removing liquid agent is preferably 0.01 to 50 m / s, and more preferably 3 m / s or more. The cleaning with the deposit removing liquid agent may be performed only once, or may be repeated a plurality of times (for example, 2 to 5 times).

  At this time, if each tank and each pipe portion to which deposits due to the aqueous pigment dispersion are deposited are subjected to physical cleaning in addition to chemical cleaning, a higher deposit removal effect can be obtained. Such physical cleaning typically includes scrubbing. As for scrubbing, cleaning using a brush or sponge, cleaning using a solid-liquid dispersion to impart frictional force to the adhesion surface, gas-liquid multiphase flow is used to reduce the film thickness between the adhesion surface and high flow velocity. And the like performed in the above. In the case of using a solid-liquid dispersion, for example, water-soluble sodium chloride, sodium bicarbonate, or the like is used in a supersaturated state, and can be discharged from the facility as a dissolved state after washing. Moreover, when using a gas-liquid mixed phase flow, it is preferable to adjust the liquid gas ratio and operate in a region where an annular flow or a dispersed flow is formed.

  Examples of other physical cleaning include jet cleaning, cleaning using ultrasonic energy and acoustic energy, and the like. Among these, those using ultrasonic energy are suitable, and the peeling of the deposit can be promoted by the energy of vibration by ultrasonic waves. Here, the frequency of the ultrasonic wave is, for example, 20 to 1000 kHz.

<Rinse washing process>
Finally, water for rinsing is circulated in each tank and each pipe from the raw material supply unit 14 to the product recovery unit 22 by supplying water from the raw material input unit 14.

  You may make water contain an antifoamer etc. The water temperature is preferably 10 to 70 ° C. It is preferable that the amount of water used for one rinsing with water is an amount that fills water in accordance with the capacity of the aqueous pigment dispersion manufacturing apparatus 10. The flow rate of water is preferably 0.01 to 50 m / s, and more preferably 3 m / s or more. This rinsing with water may be performed only once, or may be repeated a plurality of times (for example, 2 to 5 times).

  As described above, if the water-based pigment dispersion manufacturing apparatus 10 and the equipment parts used therein are cleaned, even if two or more water-based pigment dispersions are manufactured on an industrial scale using one manufacturing apparatus 10, Deposits adhering to the water-based pigment dispersion manufacturing apparatus 10 at the time of cleaning such as replacement can be efficiently removed. Therefore, even if different types of water-based pigment dispersions are manufactured thereafter, contamination between different products is suppressed, and a stable quality water-based pigment dispersion can be industrially manufactured.

  In this embodiment, the liquid distribution mechanism of the water-based pigment dispersion manufacturing apparatus 10 is operated to supply water, an acid aqueous solution, or a deposit removing liquid agent from the raw material input unit 14 and distribute it through each tank and each pipe. Then, the deposits are removed by discharging the product from the product recovery unit 21. However, the present invention is not particularly limited to this, and each unit of the aqueous pigment dispersion manufacturing apparatus is individually attached in the same procedure. The kimono may be removed.

  In the present embodiment, after the wetted acid, the deposits are removed by washing with a deposit removing liquid agent. However, the present invention is not limited to this, and after the wetted acid, The deposit may be removed by rubbing or the like without using the deposit removal liquid.

(Synthesis of acid-type water-insoluble polymer as dispersant)
In a 300 L reactor, 4.91 kg of methyl ethyl ketone, 18.6 g of a polymerization chain transfer agent (2-mercaptoethanol), and the composition shown in Table 1 ((a) component: 11% by mass of methacrylic acid, (b) component: benzyl methacrylate) 49% by mass, (c) component: 20% by mass of styrene macromer (50% by mass solution), and (d) component: 120% of a monomer mixture of polypropylene glycol monomethacrylate (30% by mass) were mixed and nitrogen gas was added. Substitution was sufficiently performed to obtain a mixed solution.

  On the other hand, the remaining 90% of the monomer mixture was charged into a dropping tank, and 167 g of a polymerization chain transfer agent (2-mercaptoethanol), 44.2 kg of methyl ethyl ketone, and 2,2′-azobis (2,4-dimethylvaleronitrile) 1 0.09 kg was added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.

  While stirring the mixed solution in the reaction vessel under a nitrogen atmosphere, the temperature was raised to 75 ° C., and the mixed solution in the dropping tank was dropped over 5 hours. After 2 hours while maintaining the temperature at 75 ° C. from the end of dropping, a solution prepared by dissolving 0.98 kg of 2,2′-azobis (2,4-dimethylvaleronitrile) in 13.1 kg of methyl ethyl ketone was added, and further at 75 ° C. for 2 hours. Then, the mixture was aged at 80 ° C. for 2 hours to obtain an acrylic water-insoluble polymer solution which is an acid type.

  The weight average molecular weight of the obtained water-insoluble polymer was measured by gel chromatography using 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide-containing dimethylformamide as a solvent using polystyrene as a standard substance. It was 180000.

  Moreover, after neutralizing 100% of the obtained acrylic water-insoluble polymer solution with sodium hydroxide and drying at 105 ° C. for 2 hours, about 0.5 g of the obtained dried product was added to 100 g of water at 25 ° C. As a result, the presence of insoluble matter was confirmed.

The details of component (c) and component (d) shown in Table 1 are as follows.
(c) Component: Styrene macromer (product name: AS-6S, number-average molecular weight: 6000, polymerizable functional group: methacryloyloxy group, manufactured by Toa Gosei Co., Ltd.)
Component (d): Polypropylene glycol monomethacrylate (Nippon Yushi Co., Ltd., trade name: Blemmer PP-800, propylene oxide average added mole number: 12)

(Production of water-based pigment dispersion)
A water-based pigment dispersion was manufactured using the acid-type water-insoluble polymer synthesized above by the water-based pigment dispersion manufacturing apparatus having the same configuration as shown in FIG. The pre-dispersion tank has a capacity of 300 L with a disper blade and a temperature control jacket, and the filter is a cartridge type 5 μm filter (trade name: Profile Star, Material: Polypropylene, manufactured by Nihon Pall). It was.

  Specifically, 6.7 kg of acid-type water-insoluble polymer obtained by drying the water-insoluble polymer solution under reduced pressure in a pre-dispersion tank of the water-based pigment dispersion production apparatus was dissolved in 37.9 kg of methyl ethyl ketone, A neutralizing agent (5N sodium hydroxide aqueous solution) 1.52 kg (neutralization degree 75%) and ion-exchanged water 113 kg were added to neutralize the salt-forming group to obtain an emulsified composition. Then, 20 kg of magenta pigment: unsubstituted quinacridone pigment (CI Pigment Violet 19 [PV19], product name: Hostaperm Red E5B02) manufactured by Clariant Japan Co., Ltd. is added, and the disper blade is operated at a temperature of 20 ° C. A pre-dispersion was obtained by mixing for 1 hour.

  Subsequently, 179 kg of the obtained pre-dispersion was circulated through a circulation pipe and repeatedly circulated through a bead mill under conditions of a peripheral speed of 12 m / s and an average number of passes of 10 passes to perform atomization dispersion treatment.

  Subsequently, the obtained dispersion was transferred to a concentration tank through a branch pipe, and after adding 89.7 kg of ion-exchanged water and stirring, methyl ethyl ketone and a part of water were distilled off with hot water at 60 ° C. under reduced pressure, Subsequently, coarse particles are removed by circulating a concentrated liquid distribution pipe provided with a filtration filter, and a water-based pigment having a solid content concentration of 25% is passed to a product recovery section via a productification tank and a product recovery pipe. The dispersion was recovered.

(Adhesion removal test evaluation)
-Deposit removal test 1-
After production of the above aqueous pigment dispersion, a part of the upstream side of the filtration filter in the concentrated liquid distribution pipe (material: SUS304, pipe diameter: 25A) is cut out and equally divided into two vertically to obtain a test piece. The inner surface was observed after washing with water. As a result, as shown in FIG. 3A, it was confirmed that the deposits due to the aqueous pigment dispersion were uniformly adhered to the inner surface.

  Further, the left half of the test piece was immersed in a 1N-sulfuric acid aqueous solution for about 30 seconds, and then the entire test piece was rubbed once with a constant load friction force (1.96 N) using a sponge corresponding to the pipe diameter. And the internal surface was observed. As a result, as shown in FIG. 3 (b), it was confirmed that the left half immersed more effectively removed deposits than the right half not immersed in the 1N sulfuric acid aqueous solution. . This can also be confirmed from the dirt on the sponge surface after rubbing as shown in FIG.

-Deposit removal test 2-
After production of the above aqueous pigment dispersion, a part of the upstream side of the filtration filter in the concentrated liquid distribution pipe (material: SUS304, pipe diameter: 25A) is cut out and equally divided into two vertically to obtain a test piece. The inner surface was observed after washing with water. As a result, as shown in FIG. 4 (a), it was confirmed that deposits due to the aqueous pigment dispersion were uniformly adhered to the inner surface.

  Further, the left half of the test piece was immersed in a 1N-sulfuric acid aqueous solution for about 30 seconds, and then the entire test piece was immersed in methyl ethyl ketone (an organic solvent having 5 carbon atoms) as an adhering substance removing agent and an ultrasonic cleaner (Aiwa). Ultrasonic energy was applied for 5 minutes by a medical industry company model: AU-260C). And the internal surface was observed. As a result, as shown in FIG. 4 (b), it was confirmed that the left half immersed more effectively removed the deposits than the right half not immersed in the 1N-sulfuric acid aqueous solution. .

-Deposit removal test 3-
After manufacturing the above aqueous pigment dispersion, a part of the upstream side of the filtration filter in the concentrated liquid distribution pipe (material: SUS304, pipe diameter: 25A) is cut out and divided into two equal parts to make a test piece. The inner surface was observed after washing with water. As a result, as shown in FIG. 5 (a), it was confirmed that the deposits due to the aqueous pigment dispersion were uniformly adhered to the inner surface.

  Further, the left half of the test piece is immersed in a 1N-sulfuric acid aqueous solution for about 30 seconds, and then the entire test piece is immersed in a cleaning agent containing amyl glyceryl ether (an organic solvent having 8 carbon atoms) as a deposit removing liquid agent. At the same time, ultrasonic energy was applied for 5 minutes by an ultrasonic cleaner (model: AU-260C, manufactured by Aiwa Medical Industry Co., Ltd.). And the internal surface was observed. As a result, as shown in FIG. 5 (b), it was confirmed that the left half that was immersed in the right half not immersed in the 1N-sulfuric acid aqueous solution was able to remove deposits more effectively. .

-Deposit removal test 4-
After production of the above aqueous pigment dispersion, three portions on the upstream side of the filtration filter in the concentrate flow pipe (material: SUS304, pipe diameter: 25A) are cut out to form test pieces, which are washed with water, One of the two was vertically divided into two to observe the inner surface. As a result, as shown in FIG. 6 (a), it was confirmed that deposits due to the aqueous pigment dispersion were uniformly attached to the inner surface.

  One of the two remaining test pieces was immersed in a 1N-sulfuric acid aqueous solution for about 30 seconds. Subsequently, water was circulated for 2 hours at an average flow rate of 7.8 m / s for both test pieces. And each test piece was equally divided into two vertically, and the internal surface was observed. As a result, as shown in FIG. 6 (b), the immersed test piece (left side) can remove the deposits more effectively than the test piece (right side) not immersed in the 1N-sulfuric acid aqueous solution. It was confirmed that

-Deposit removal test 5-
After production of the above aqueous pigment dispersion, a part of the upstream side of the filtration filter in the concentrated liquid distribution pipe (material: SUS304, pipe diameter: 25A) is cut out and equally divided into two vertically to obtain a test piece. The inner surface was observed after washing with water. As a result, as shown in FIG. 7A, it was confirmed that the deposits due to the aqueous pigment dispersion were uniformly adhered to the inner surface.

  Further, the left half of the test piece was immersed in 1N-sulfuric acid aqueous solution and the right half in 50% citric acid aqueous solution for about 30 seconds, respectively, and then the whole test piece was treated with amyl glyceryl ether (carbon number 8 And an ultrasonic energy was applied for 10 minutes with an ultrasonic cleaner (model: AU-260C, manufactured by Aiwa Medical Industry Co., Ltd.). And the internal surface was observed. As a result, as shown in FIG. 7 (b), it was confirmed that the deposits were effectively removed from the portion immersed in either the 1N-sulfuric acid aqueous solution or the 50% citric acid aqueous solution. However, in the portion immersed in the 1N-sulfuric acid aqueous solution, the deposits were effectively removed over the details.

  INDUSTRIAL APPLICATION This invention is useful about the deposit removal method in the manufacturing apparatus of the aqueous pigment dispersion containing a pigment, the acid-type water-insoluble polymer as a dispersing agent, and a neutralizing agent.

10 Water-based pigment dispersion production equipment 14 Raw material supply unit 22 Product recovery unit

Claims (7)

A deposit removal method in an apparatus for producing an aqueous pigment dispersion containing a pigment, an acid-type water-insoluble polymer as a dispersant, and a neutralizer,
A deposit removal method for removing deposits from a portion after depositing an acid on a portion to which deposits due to an aqueous pigment dispersion have adhered.   The deposit removal method according to claim 1, wherein the deposit is removed from the portion in contact with the acid by washing with a deposit removing solution.   The deposit removing method according to claim 2, wherein the deposit removing liquid agent is a cleaning agent containing an organic solvent having 6 to 12 carbon atoms and / or an organic solvent having 1 to 5 carbon atoms. The acid contact is performed by circulating the acid from the raw material supply unit to the product recovery unit of the aqueous pigment dispersion manufacturing apparatus,
The washing with the deposit removing liquid is performed by circulating the deposit removing liquid at a mean flow rate of 3 m / s or more from the raw material supply section of the water-based pigment dispersion manufacturing apparatus to the product recovery section. 4. The method for removing deposits according to 3.   5. The deposit removal method according to claim 2, wherein ultrasonic energy is applied to a portion to which deposits due to the water-based pigment dispersion are adhered during washing with the deposit removal liquid agent.   6. The deposit removal method according to claim 1, wherein the acid is a strong acid.   The deposit removal method according to any one of claims 1 to 6, wherein a portion to which the water-based pigment dispersion adheres in the water-based pigment dispersion manufacturing apparatus is formed of stainless steel.