阅读说明：本技术 清洁剂组合物 (Detergent composition ) 是由 长野智彦 福田辉幸 前田高宏 于 2019-03-13 设计创作，主要内容包括：本发明涉及对于附着有聚合物的硬质表面等在室温下也具有优异的清洁力的清洁剂组合物。本发明提供：〔1〕一种清洁剂组合物,其中,含有水溶性有机胺(a)、下述通式(1)所示的烷基氧化胺(b)、在20℃下的汉森溶解度参数(HSP值)为15～19.5的有机溶剂(c)、和水；以及,〔2〕一种硬质表面的清洁方法,其中,对硬质表面在45℃以上且85℃以下的温度用上述清洁剂组合物进行清洁。(R<Sup>1</Sup>)(R<Sup>2</Sup>)(R<Sup>3</Sup>)N→O(1)(式中,R<Sup>1</Sup>和R<Sup>2</Sup>分别独立地表示碳原子数为1～3的烷基或烯基,R<Sup>3</Sup>表示碳原子数为8～16的烷基或烯基。)。(The present invention relates to a detergent composition having excellent cleaning power even at room temperature for a hard surface or the like to which a polymer is attached. The present invention provides: [ 1] A detergent composition comprising a water-soluble organic amine (a), an alkylamine oxide (b) represented by the following general formula (1), an organic solvent (c) having a Hansen solubility parameter (HSP value) of 15 to 19.5 at 20 ℃, and water; and the number of the first and second groups,a method for cleaning a hard surface, wherein the hard surface is cleaned at a temperature of 45 ℃ to 85 ℃ by using the above-mentioned cleaning composition. (R) 1 )(R 2 )(R 3 ) N → O (1) (in the formula, R 1 And R 2 Each independently represents an alkyl group or alkenyl group having 1 to 3 carbon atoms, R 3 Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms. ).)

1. A detergent composition comprising, in a detergent composition,

comprises the following components: a water-soluble organic amine (a), an alkyl amine oxide (b) represented by the following general formula (1), an organic solvent (c) having an HSP value at 20 ℃ of 15-19.5, and water,

(R¹)(R²)(R³)N→O (1)

in the formula, R¹And R²Each independently represents an alkyl group or alkenyl group having 1 to 3 carbon atoms, R³Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms,

the HSP value is the hansen solubility parameter.

2. The detergent composition of claim 1,

the water-soluble organic amine (a) is an alkanolamine.

3. The detergent composition of claim 2,

the alkanolamine is at least 1 selected from monoethanolamine, diethanolamine and N-methylethanolamine.

4. A detergent composition according to any one of claims 1 to 3,

the alkylamine oxide (b) is at least 1 selected from lauryl dimethylamine oxide, lauryl diethylamine oxide, myristyl dimethylamine oxide and coco alkylamine oxide.

5. The detergent composition according to any one of claims 1 to 4, wherein,

the organic solvent (c) is at least 1 selected from the group consisting of a compound having an ether group, a compound having an ester group, and a compound having a ketone group.

6. The detergent composition according to any one of claims 1 to 5, wherein,

the organic solvent (c) is at least 1 selected from tetrahydrofuran, diethyl ether, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate, methyl ethyl ketone, methyl acetone, methyl isobutyl ketone and diisobutyl ketone.

7. A detergent composition according to any one of claims 1 to 6,

the mass ratio (a)/(b) of the water-soluble organic amine (a) to the alkyl amine oxide (b) is 0.1 to 50.

8. The detergent composition of claim 7,

the mass ratio (a)/(b) of the water-soluble organic amine (a) to the alkyl amine oxide (b) is 1 to 20 inclusive.

9. A detergent composition according to any one of claims 1 to 8,

the mass ratio (c)/(b) of the organic solvent (c) to the alkylamine oxide (b) is 10 to 300 inclusive.

10. The detergent composition of claim 9,

the mass ratio (c)/(b) of the organic solvent (c) to the alkylamine oxide (b) is 15 to 250 inclusive.

11. A detergent composition as claimed in any one of claims 1 to 10,

the detergent composition has a pH of 9 or more.

12. A method for cleaning a hard surface, wherein,

cleaning a hard surface at a temperature of 0 ℃ or more and 50 ℃ or less with the detergent composition according to any one of claims 1 to 11.

13. The method of cleaning a hard surface according to claim 12,

a hard surface is the surface of a metal part that the polymer contacts.

14. The method of cleaning a hard surface according to claim 12 or 13,

the hard surface is cleaned in a state where the detergent composition is foamed.

15. Use of the detergent composition according to any one of claims 1 to 11 for cleaning ink production equipment for inkjet recording.

16. Use of a detergent composition as claimed in any one of claims 1 to 11 for inkjet printing system cleaning.

Technical Field

The present invention relates to a detergent composition and a method for cleaning a hard surface using the same.

Background

A hard surface such as an inner wall of a reaction vessel used in a production process for producing a polymer or using a polymer is adhered with a highly viscous or solidified polymer typified by a residual polymer, a residue of various inorganic and/or organic additives added to the polymer, a highly viscous or solidified polymer mixture obtained by mixing the polymer and the additives, and the like after the polymer is used or the produced polymer is discharged (hereinafter, the above-mentioned polymer, residue, and polymer mixture are collectively referred to as "polymer and the like" for simplicity).

When the hard surface to which the polymer is attached such as the above-mentioned reaction tank is repeatedly used, it is necessary to clean the hard surface to remove the attached polymer or the like after each use or before the next use.

For example, in the field of production of aqueous dispersions for inkjet recording, aqueous dispersions are generally obtained by using a polymer dispersion containing a polymer as a main component, a colorant composed of a pigment or a dye, and various additives added as necessary. In the production of the aqueous dispersion, a polymer-like deposit is accumulated on the inner wall of a production apparatus including a reaction tank or the like at a gas-liquid interface with a solvent used in the production. When the variety of the aqueous dispersion is changed, the inner walls of the production apparatus and the reaction tank are cleaned, but when the amount of the polymer-like retention increases, the polymer-like retention is mixed into the aqueous dispersion, and the performance of the aqueous ink containing the aqueous dispersion is degraded. In addition, it is known that: in the ink for inkjet recording, a polymer is subjected to a crosslinking treatment in order to achieve a low viscosity and a high print density, but the polymer subjected to such a crosslinking treatment is difficult to clean with a conventional cleaning agent. Therefore, a method for cleaning a polymer or the like adhered to a hard surface of a reaction vessel or the like has become an important technical problem.

Japanese patent laid-open No. 2000-127419 (patent document 1) discloses a cleaning method for cleaning nozzles of an ink jet recording head using a cleaning liquid containing a surfactant, an alkali compound and water and having a pH of 9 or more after printing with an ink composition containing a pigment.

Japanese laid-open patent publication No. 2012-67152 (patent document 2) discloses a method for cleaning a hard surface, wherein the hard surface is cleaned by using an aqueous cleaning agent having a cleaning temperature of 45-85 ℃, the aqueous cleaning agent comprising (a) an alkaline agent, (b) an alkylamine oxide and (c) a solubility parameter of 8-12 (cal/cm)³)^1/2The pH of the aqueous cleaning agent is 11 to 14.

Jp 2016 & lt60156 & gt (patent document 3) discloses a cleaning liquid for cleaning a portion to which an aqueous ink ejected from an ink jet printer adheres, the cleaning liquid containing an amphoteric surfactant, an alkali compound and water, the cleaning liquid having a pH of 9 to 12 and containing 0.1 to 3 mass% of an amphoteric surfactant such as dimethyl lauryl amine oxide with respect to the total amount of the cleaning liquid.

Disclosure of Invention

The invention relates to a detergent composition, which comprises: a water-soluble organic amine (a), an alkyl amine oxide (b) represented by the following general formula (1), an organic solvent (c) having a Hansen solubility parameter (HSP value) at 20 ℃ of 15 to 19.5, and water,

(R¹)(R²)(R³)N→O (1)

in the formula, R¹And R²Each independently represents a carbon atom number of 1 to 3The following alkyl or alkenyl groups, R³Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms.

Detailed Description

The cleaning methods and cleaning liquids described in the above patent documents 1 to 3 do not sufficiently satisfy the cleaning effect on a hard surface to which a polymer or the like is adhered.

The present invention relates to a cleaning composition and a method for cleaning a hard surface using the same, which has excellent cleaning ability even at room temperature for a hard surface, particularly a hard surface to which a polymer is attached, particularly a hard surface constituting a production line of an ink for inkjet recording.

The present inventors have found that: when a specific detergent composition containing a water-soluble organic amine, an alkyl amine oxide and an organic solvent is used, a hard surface can be effectively cleaned.

Namely, the present invention relates to the following [ 1] and [ 2 ].

[ 1] A detergent composition comprising: a water-soluble organic amine (a), an alkyl amine oxide (b) represented by the following general formula (1), an organic solvent (c) having a Hansen solubility parameter (HSP value) at 20 ℃ of 15 to 19.5, and water,

(R¹)(R²)(R³)N→O (1)

in the formula, R¹And R²Each independently represents an alkyl group or alkenyl group having 1 to 3 carbon atoms, R³Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms.

A method for cleaning a hard surface, wherein the hard surface is cleaned at a temperature of 0 ℃ to 50 ℃ by using the above-mentioned cleaning composition.

According to the present invention, a cleaning composition and a method for cleaning a hard surface using the same can be provided, which has excellent cleaning ability even at room temperature for a hard surface, particularly a hard surface to which a polymer is attached, particularly a hard surface constituting a production line of an ink for inkjet recording.

[ detergent composition ]

The detergent composition of the present invention is characterized by containing a water-soluble organic amine (a), an alkylamine oxide (b) represented by the following general formula (1) (hereinafter, also simply referred to as "alkylamine oxide (b)"), an organic solvent (c) (hereinafter, also simply referred to as "organic solvent (c)") having a hansen solubility parameter (HSP value) at 20 ℃ of 15 or more and 19.5 or less, and water.

(R¹)(R²)(R³)N→O (1)

(in the formula, R¹And R²Each independently represents an alkyl group or alkenyl group having 1 to 3 carbon atoms, R³Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms. )

The use of the detergent composition of the present invention enables effective cleaning of a hard surface to which a polymer or the like is adhered, which is an object to be cleaned, particularly at room temperature.

The hard surface is preferably a surface of a member in contact with a polymer or the like, and examples of such a member include a polymer, a metal constituting a production line for producing a polymer, glass, ceramics, plastics, and the like. Among these, metals having high alkali resistance and being less likely to be deformed by temperature are particularly preferable. That is, the hard surface is preferably a surface of a metal member in contact with a polymer or the like, and such a metal is preferably iron or stainless steel, and more preferably stainless steel.

The object to be cleaned by the cleaning composition of the present invention is a deposit of a polymer or the like generated by using a polymer or generated at the time of production of a polymer. The polymer and the like are not particularly limited.

Specific examples of the hard surface include: a production line using an addition-clustering polymer such as a vinyl polymer such as a styrene-acrylate copolymer, a polycondensation polymer such as polyester, polyethylene terephthalate, or polyurethane, or a ring-opening polymerization polymer such as epoxy resin; and the inner wall of a reaction vessel of an apparatus in a production line having a high adhesion frequency of a polymer, such as the production line for synthesizing the above-mentioned polymer. In particular, hard surfaces to which a crosslinked polymer, a polymer having a low acid value (for example, polyester, or the like) or the like has adhered are difficult to clean with a conventional cleaning agent.

The detergent composition of the present invention is applied to, for example, a production line of an aqueous ink for inkjet recording, and particularly to a production line of an aqueous dispersion including a step of granulating a raw material component containing a polymer in an aqueous medium, and a hard surface to which a polymer or the like is adhered. In this case, the hard surface of the reaction vessel as the object to be cleaned is mainly a polymer-like deposit which is accumulated at a gas-liquid interface of a solvent used in the production of the aqueous dispersion, and includes raw material components such as a polymer and an unreacted polymer raw material monomer in the production of the aqueous dispersion described later, and various additives such as a colorant and a surfactant, and the main component thereof is a polymer.

Hereinafter, each component and the like used in the detergent composition of the present invention will be described.

< Water-soluble organic amine (a) >)

The detergent composition of the present invention contains the water-soluble organic amine (a) from the viewpoint of enhancing the cleaning power on a hard surface.

As used herein, "water-soluble" means having a solubility of 5g/100gH for 100g of water at 25 ℃₂O or more, preferably 10g/100gH₂O or more.

From the viewpoint of enhancing the cleaning power to the hard surface, the number of carbon atoms of the water-soluble organic amine (a) is preferably 2 or more, more preferably 3 or more, and preferably 10 or less, more preferably 8 or less, and still more preferably 6 or less.

From the viewpoint of enhancing the cleaning power for a hard surface, the water-soluble organic amine (a) has an acid dissociation constant pKa of preferably 9.0 or more, more preferably 9.2 or more, and still more preferably 9.5 or more in an aqueous solution at 25 ℃.

Examples of the water-soluble organic amine (a) include alkanolamines, alkylamines, aralkylamines, polyamines, and cyclic amines. Among these, alkanolamines are preferable from the viewpoint of improving the cleaning property.

As the alkanolamine, any of primary, secondary and tertiary alkanolamines can be used.

Examples of the primary alkanol amine include monoethanolamine, monopropanolamine, monoisopropanolamine, and monobutanolamine.

Examples of the secondary alkanol amine include N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine, N-butylethanolamine, diethanolamine, diisopropanolamine, N-methylpropanolamine, N-methylisopropanolamine, N-ethylisopropanolamine, and N-propylisopropanolamine.

Examples of the tertiary alkanol amine include N, N-dimethylethanolamine, N-dimethylpropanolamine, N-diethylethanolamine, N-ethyldiethanolamine, N-methyldiethanolamine, triethanolamine (pKa: 7.72), triisopropanolamine and the like.

Among these, water-soluble alkanolamines having 2 to 8 carbon atoms are preferable, 1 or more selected from primary and secondary alkanolamines are more preferable, and 1 or more selected from monoethanolamine (pKa: 9.44), monoisopropanolamine (pKa: 9.45), N-methylethanolamine (pKa: 9.99), N-ethylethanolamine (pKa: 9.9), diethanolamine (pKa: 8.88), diisopropanolamine (pKa: 8.84), N-methylisopropanolamine, N-dimethylethanolamine (pKa: 9.22), N-diethylethanolamine (pKa: 9.75), and N-methyldiethanolamine (pKa: 8.56) are even more preferable.

From the viewpoint of enhancing the cleaning property and the versatility, the water-soluble organic amine (a) is more preferably 1 or more selected from the group consisting of monoethanolamine, diethanolamine and N-methylethanolamine.

Furthermore, the alkanolamines listed as preferred examples above have a solubility of 50g/100gH for 100g of water at 25 ℃₂O or more.

The various water-soluble organic amines (a) can be used alone or in combination of 2 or more.

< alkylamine oxide (b) represented by the general formula (1) >)

The detergent composition of the present invention contains the alkylamine oxide (b) from the viewpoint of improving the cleaning power on a hard surface. By containing the alkylamine oxide (b), not only the adhesion of the detergent composition to the hard surface but also the uniform wet spreadability to the entire hard surface can be improved. In addition, the foam forming property is also improved, and the rinsing property is also improved.

The alkylamine oxide (b) contained in the detergent composition of the present invention is represented by the following general formula (1).

(R¹)(R²)(R³)N→O (1)

In the general formula (1), R¹And R²Each independently represents an alkyl group or an alkenyl group having 1 to 3 carbon atoms, and is preferably a methyl group or an ethyl group, and more preferably a methyl group, from the viewpoint of improving the cleaning ability when the cleaning agent composition is repeatedly used a plurality of times. In the present invention, by using a specific alkylamine oxide, a characteristic cleaning property can be exhibited.

In addition, from the viewpoint of improving the cleaning property when the detergent composition is repeatedly used a plurality of times, R is³Represents an alkyl group or alkenyl group having 8 to 16 carbon atoms, preferably a linear or branched alkyl group or alkenyl group having 8 to 14 carbon atoms, and more preferably a linear or branched alkyl group having 8 to 14 carbon atoms.

Specific examples of the compound represented by the general formula (1) include 1 or more selected from lauryl dimethyl amine oxide, lauryl diethyl amine oxide, myristyl dimethyl amine oxide, and coco alkyl amine oxide, and more preferably 1 or more selected from lauryl dimethyl amine oxide and lauryl diethyl amine oxide.

The alkyl amine oxide (b) can be used alone or in combination of 2 or more.

(c) > < organic solvent having a Hansen solubility parameter of 15 or more and 19.5 or less

The detergent composition of the present invention contains an organic solvent (c) having a Hansen solubility parameter (HSP value) of 15 to 19.5 at 20 ℃. The unit of the Hansen solubility parameter (HSP value) is ((J/cm)³)^1/2) Unless otherwise specified, the unit of HSP value is ((J/cm)³)^1/2)。

HSP value will be determined by HildebThe solubility parameter (SP value) introduced by rand is divided into 3 components (energy of intermolecular dispersion force)_dEnergy of intermolecular dipole interaction_pEnergy of intermolecular hydrogen bond_h) The value of (c). Of each solvent_d、_p、_hDescribed in detail in "HANSEN solubility PARAMETERS (HANSEN solubility PARAMETERS)" Second Edition of user's manual (AUser's Handbook Second Edition). In addition, HSP values of many solvents and resins are also described in wesley l.

The HSP value when a plurality of organic solvents are used can be determined as a weighted average value m of the HSP values of the respective organic solvents, according to the following formula (2).

m＝₁φ₁+₂φ₂(2)

Here, the first and second liquid crystal display panels are,₁、₂is the HSP value of each solvent component, [ phi ]₁、φ₂The volume fraction of each solvent component.

The HSP value of the organic solvent can also be determined using software HSPiP of charles hansen consulting company (Horsholm, Denmark, hansen-solubility.com).

In the present invention, the values of the solvents registered in the HSPiP 4.1.03 version database (see various HSP documents) were used; for solvents not present in the database, values estimated by HSPiP described above were used.

When the HSP value is less than 15 or exceeds 19.5, the cleaning property is deteriorated due to the lowered compatibility with the polymer or the like as the contaminant. The SP value is preferably 15.5 or more, more preferably 16.0 or more, still more preferably 16.5 or more, still more preferably 17.0 or more, and preferably 19.4 or less.

In addition, the organic solvent (c) is preferably: at least 1 kind selected from compounds having ether group such as cyclic ether and chain ether, compounds having ester group such as acetic ester, and compounds having ketone group such as chain ketone.

Preferable examples of the organic solvent having an HSP value of 15 or more and 19.5 or less in a single solvent include: a cyclic ether solvent selected from tetrahydrofuran (HSP value: 19.46) and the like; a chain ether solvent such as diethyl ether (HSP value: 15.49); acetic ester solvents such as ethyl acetate (HSP value: 18.15), isopropyl acetate (HSP value: 17.59), propyl acetate (HSP value: 17.62), butyl acetate (HSP value: 17.41), and the like; and (3) at least 1 kind of chain ketone solvent such as methyl ethyl ketone (HSP value: 19.05), methyl acetone (HSP value: 18.33), methyl isobutyl ketone (HSP value: 16.97), diisobutyl ketone (HSP value: 16.93). Among these, a chain ketone solvent is preferable, and methyl ethyl ketone is more preferable.

These organic solvents can be used alone in 1 or in combination of 2 or more.

In addition to an organic solvent having an HSP value of 15 or more and 19.5 or less as a single solvent, a mixed solvent having a plurality of solvents in combination can also be used as long as m obtained from the above formula (2) has an HSP value of 15 or more and 19.5 or less. For example, when methyl ethyl ketone (HSP value: 19.05) and cyclohexanone (HSP value: 20.33) which is a cyclic ketone are 80% and 20% by volume fraction, respectively, m is 19.31, and thus, it can be used as the organic solvent (c) having an HSP value of 15 or more and 19.5 or less.

< other additives >

The detergent composition of the present invention may contain known additives such as nonionic surfactants, chelating agents, solubilizers, slurrying agents, and defoaming agents, as long as the object of the present invention is not impaired.

The nonionic surfactant preferably has an HLB (by Davies method) of 4.3 to 8.2, more preferably 5 to 7.9, and even more preferably 5.5 to 7.5, from the viewpoint of improving the cleaning property of a deposit such as a polymer on a hard surface.

As the nonionic surfactant, commercially available products such as BLAUNONEH-2, BLAUNON EH-4, BLAUNON EH-6 and BLAUNON EH-11 manufactured by Qingmu oil and fat industries, Emulgen109P manufactured by Kao corporation, Emulgen 120, Softanol EP9050 and Softanol EP12030, and Softanol 90, Softanol 120, Softanol 150 and Softanol 200 manufactured by Nippon catalytic chemical industries, can be used.

Chelating agents can enhance the cleaning effect of polymers and the like on hard surfaces.

Preferred examples of the chelating agent include gluconic acid, glucoheptonic acid, ethylenediaminetetraacetic acid, citric acid, malic acid, alkali metal salts or lower amine salts of hydroxyethylenediphosphonic acid, and the like, from the viewpoint of improving the cleaning property of a polymer or the like on a hard surface, and sodium gluconate, sodium glucoheptonate, sodium ethylenediaminetetraacetate, sodium citrate, sodium hydroxyethylenediphosphonate, and the like are more preferred.

When the detergent composition is thick, it is preferable to contain a solubilizer for forming a stable aqueous solution in which no separation or precipitation of components occurs, and if necessary, a slurrying agent for ensuring the fluidity of the thick system.

Examples of the solubilizer include alkenyl succinic acid having 6 to 18 carbon atoms and salts thereof, caproic acid, heptanoic acid, caprylic acid, capric acid, lauric acid, butyric acid, n-valeric acid, isobutyric acid, 2-ethylhexanoic acid, and salts thereof.

Examples of the sizing agent include water-soluble high-molecular carboxylic acids, naphthalenedicarboxylic acids, and alkali metal salts or amine salts thereof.

< detergent composition >

The detergent composition of the present invention contains a water-soluble organic amine (a), an alkyl amine oxide (b) represented by general formula (1), an organic solvent (c) having an HSP value of 15-19.5 at 20 ℃, and water.

The content of each component in the detergent composition of the present invention can be appropriately adjusted depending on the kind of the object to be cleaned and the kind of the contaminant, and the following range is preferable from the viewpoint of improving the cleaning power of the polymer or the like adhering to the hard surface.

The content of the water-soluble organic amine (a) in the detergent composition is preferably 0.05 wt% or more, more preferably 0.1 wt% or more, still more preferably 0.5 wt% or more, and still more preferably 1 wt% or more, and is preferably 12 wt% or less, more preferably 10 wt% or less, still more preferably 8 wt% or less, and still more preferably 5 wt% or less.

The content of the alkylamine oxide (b) is preferably 0.01% by weight or more, more preferably 0.05% by weight or more, still more preferably 0.1% by weight or more, and even more preferably 0.5% by weight or more, and is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less, and even more preferably 2% by weight or less.

The content of the organic solvent (c) in the detergent composition is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 5% by weight or more, and still more preferably 10% by weight or more, and is preferably 45% by weight or less, more preferably 40% by weight or less, still more preferably 35% by weight or less, and still more preferably 30% by weight or less.

The content of water such as deionized water, distilled water, or the like in the detergent composition is preferably 30% by weight or more, more preferably 40% by weight or more, and still more preferably 50% by weight or more, and is preferably 95% by weight or less, more preferably 90% by weight or less, and still more preferably 85% by weight or less.

When the solubilizer is used, the content thereof in the detergent composition is preferably 0.01 to 3% by weight, more preferably 0.05 to 1% by weight, from the viewpoint of improving the low-temperature stability and the economical efficiency of the detergent.

The mass ratio [ (a)/(b) ] of the water-soluble organic amine (a) to the alkyl amine oxide (b) in the detergent composition is preferably 0.1 or more, more preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, still more preferably 4 or more, and is preferably 50 or less, more preferably 35 or less, still more preferably 20 or less, still more preferably 10 or less.

The mass ratio of the organic solvent (c) to the alkylamine oxide (b) [ (c)/(b) ], in the detergent composition is preferably 10 or more, more preferably 15 or more, still more preferably 20 or more, still more preferably 25 or more, and is preferably 300 or less, more preferably 270 or less, still more preferably 250 or less, still more preferably 200 or less.

From the viewpoint of enhancing the cleaning power of a polymer or the like on a hard surface, the viscosity of the cleaning composition at 32 ℃ is preferably 1mPa · s or more, more preferably 1.1mPa · s or more, and even more preferably 1.2mPa · s or more, and is preferably 8mPa · s or less, more preferably 6mPa · s or less, even more preferably 4mPa · s or less, and even more preferably 2mPa · s or less.

From the viewpoint of improving the cleaning power for polymers and the like on hard surfaces, the static surface tension of the detergent composition is preferably 18mN/m or more, more preferably 20mN/m or more, still more preferably 22mN/m or more, and still more preferably 25mN/m or more, and is preferably 45mN/m or less, more preferably 40mN/m or less, still more preferably 35mN/m or less, and still more preferably 32mN/m or less.

From the viewpoint of improving the cleaning power of a polymer or the like on a hard surface, the pH of the detergent composition at 20 ℃ is preferably 9 or more, more preferably 9.5 or more, more preferably 10 or more, and still more preferably 11 or more, and is preferably 14 or less, more preferably 13 or less, and still more preferably 12 or less.

The viscosity, static surface tension and pH of the detergent composition were determined by the methods described in the examples.

[ method for cleaning hard surface ]

The method for cleaning a hard surface of the present invention is characterized by cleaning a hard surface at a temperature near room temperature, that is, at a temperature of 0 ℃ to 50 ℃ inclusive, using the detergent composition of the present invention. The method for cleaning a hard surface of the present invention is simple and useful because it does not require a special treatment such as heating the hard surface.

As described above, the hard surface is preferably the surface of a metal member in contact with a polymer or the like, and more preferably the surface of a member constituting a production line (a production line for a step of granulating a component containing a polymer or the like in an aqueous medium).

In the cleaning method of the present invention, the hard surface to which the polymer or the like is adhered preferably exhibits an excellent cleaning effect at a cleaning temperature of 50 ℃ or less, more preferably 45 ℃ or less, and even more preferably 42 ℃ or less, from the viewpoint of reducing energy consumption.

The cleaning operation in the cleaning method of the present invention is not particularly limited, and any of general cleaning operations such as dip cleaning, agitation cleaning, spray cleaning, brush cleaning, and the like can be used. It is preferable that the detergent composition of the present invention is intentionally foamed by stirring, spray brushing, or the like, and the cleaning is performed, whereby a higher cleaning effect can be obtained.

In the cleaning method of the present invention, the cleaning composition of the present invention can be stored in a storage facility such as a separate tank or a metal bucket after use and reused, and thus can be repeatedly used several times. Therefore, it is desired that the cleaning effect can be maintained even when the used detergent composition is stored, and the detergent composition of the present invention has high stain durability and excellent storage performance, and therefore, can be repeatedly used for 5 times or more, further 8 times or more, and further 10 times or more, usually, on a hard surface to which a polymer is attached.

< object to be cleaned, device to be cleaned >

In the detergent composition and the method for cleaning a hard surface of the present invention, the object to be cleaned may be a polymer, and the polymer is preferably a water-insoluble polymer from the viewpoint of exerting cleaning power. There is no particular limitation on the apparatus or equipment to which the detergent composition and the method for cleaning a hard surface of the present invention are applied. For example, the cleaning target device can be applied to: cleaning of apparatuses or facilities such as a reaction tank for producing a polymer, a mixing tank for mixing a polymer, piping for transporting a liquid containing a polymer, and a storage tank for storing a liquid containing a polymer. In addition, it can also be used for: cleaning of printers using the aqueous dispersion for inkjet recording or the ink for inkjet recording, equipment for storing the printers, inkjet printing systems, and the like.

For example, when the cleaning composition and the method for cleaning a hard surface of the present invention are used, an apparatus for producing an aqueous dispersion having a hard surface to which an object to be cleaned is attached is used, and after at least the hard surface is cleaned by the cleaning composition and the method for cleaning of the present invention, a raw material component containing a polymer can be granulated in an aqueous medium to produce an aqueous dispersion.

The apparatus for producing an aqueous dispersion may be a production apparatus of various sizes, from a small-scale production apparatus of a laboratory scale to a large-scale production apparatus for mass production. Specifically, the method can be applied to a production apparatus having a reaction vessel with a capacity of about 200L to 10m³Capacity, further 20m³A reaction tank having a larger capacity.

The reaction vessel can preferably use a surface exemplified as the hard surface. For example, the reaction vessel described in japanese patent application laid-open No. 9-258479, specifically, a glass-lined reactor having a glass lining on the surface, a reactor having an electrically conductive surface, a reactor made of a corrosion-resistant metal such as stainless steel, and various materials can be favorably used.

The polymer used for cleaning the production equipment of the aqueous dispersion, particularly the aqueous dispersion for inkjet recording and the aqueous ink for inkjet recording is not particularly limited.

In the present invention, it is preferable that: after cleaning a device or equipment with the detergent composition, for example, an aqueous dispersion for inkjet recording is produced by a production method described later. The aqueous ink is obtained by adding and mixing an organic solvent and water to the obtained aqueous dispersion to appropriately adjust the concentration, and if necessary, adding additives such as a wetting agent generally used in aqueous inks.

< Polymer >

Examples of the polymer of the object to be cleaned include water-insoluble polymers, and examples thereof include vinyl polymers such as polyesters, polystyrenes, and polyvinyl chlorides, and polyurethane polymers.

For example, as the polymer used for producing the above-mentioned aqueous dispersion and aqueous ink, a water-insoluble polymer such as polyester or vinyl polymer is preferably used from the viewpoint of improving dispersibility and storage stability by micronizing a colorant such as a pigment, and improving print density and adhesion to a recording medium (hereinafter also referred to as "substrate adhesion") of an aqueous ink obtained using the aqueous dispersion. The polymer can also be used as a fixing resin used as a coating film forming agent for aqueous ink.

Here, the meaning of the "water-insoluble polymer" and the "water-soluble polymer" is as follows: when the polymer has a salt-forming group, the salt-forming group of the polymer is 100% neutralized with acetic acid or sodium hydroxide depending on the type thereof, and then 100g of pure water at 25 ℃ is added to 10g of the neutralized product and sufficiently stirred, and if all of the salt-forming group is dissolved, the polymer is a "water-soluble polymer" in the present invention.

For example, a polymer is dissolved in an organic solvent such as methyl ethyl ketone in advance, a 100% neutralized product thereof is dropped into pure water, the organic solvent is removed to make the concentration 10% by weight, the obtained water dispersion is separated by centrifugation, and the polymer obtained by precipitation is referred to as a "water-insoluble polymer", and the dissolved polymer is referred to as a "water-soluble polymer".

< Water-insoluble Polymer >

As typical examples of the water-insoluble polymer, polyester, vinyl polymer, polyurethane polymer, and the like can be preferably cited.

[ polyester ]

The polyester is preferably a polyester obtained by polycondensation of at least (i) an alcohol component and (ii) a carboxylic acid component.

(i) Alcohol component

The alcohol component which is a structural unit of the polyester preferably contains an aromatic diol from the viewpoint of pigment dispersibility of the obtained aqueous ink.

The aromatic diol is preferably an alkylene oxide adduct of bisphenol a. In the present invention, the alkylene oxide adduct of bisphenol a refers to the entire structure obtained by adding an alkylene oxide to 2, 2-bis (4-hydroxyphenyl) propane.

Specifically, the oxyalkylene adduct of bisphenol A is preferably a compound represented by the following general formula (I).

In the general formula (I), OR¹、R²Each O is an oxyalkylene group, and each is independently preferably an oxyalkylene group having 1 to 4 carbon atoms, and more preferably an oxyethylene group or an oxypropylene group.

x and y are each independently a molar number of addition of the oxyalkylene group, and are preferably 1 or more, more preferably 2 or more, and preferably 16 or less, more preferably 7 or less, still more preferably 5 or less, and still more preferably 3 or less. From the viewpoint of reactivity with the carboxylic acid component, the average value of the sum of x and y is preferably 2 or more. From the same viewpoint, the average value of the sum of x and y is preferably 7 or less, more preferably 5 or less, and still more preferably 3 or less.

In addition, x ORs¹And y R²The O groups may be the same or different, and are preferably the same from the viewpoint of improving the adhesion to the substrate. As the alkylene oxide adduct of bisphenol A, 1 kind can be used alone or 2 or more kinds can be used in combination. The oxyalkylene adduct of bisphenol A is preferably an oxypropylene adduct of bisphenol A and an oxyethylene adduct of bisphenol A, and more preferably an oxypropylene adduct of bisphenol A.

The content of the oxyalkylene adduct of bisphenol a in the alcohol component as the raw material monomer is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and preferably 100 mol% or less, from the viewpoint of improving the adhesion to the substrate.

The alcohol component as a raw material monomer of the polyester may contain the following alcohol component in addition to the oxyalkylene adduct of bisphenol a.

Examples thereof include ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol a, sorbitol, and alkylene oxide (having 2 or more and 4 or less carbon atoms) adducts thereof (average molar number of addition is 1 or more and 16 or less).

The alcohol component can be used alone in 1 or a combination of 2 or more.

(ii) Carboxylic acid component

The carboxylic acid component which is a structural unit of the polyester includes a carboxylic acid, an acid anhydride of the carboxylic acid, an alkyl (having 1 to 3 carbon atoms) ester of the carboxylic acid, and the like.

The carboxylic acid component is preferably an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, or a 3-or more-membered polycarboxylic acid, and from the viewpoint of improving the reactivity of the carboxylic acid component with the alcohol component and the adhesion to the substrate, an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are more preferable, and an aliphatic dicarboxylic acid is even more preferable.

The aromatic dicarboxylic acid is preferably phthalic acid, isophthalic acid, or terephthalic acid, and more preferably terephthalic acid.

The aliphatic dicarboxylic acid includes unsaturated aliphatic dicarboxylic acids and saturated aliphatic dicarboxylic acids, and the unsaturated aliphatic dicarboxylic acids are preferable from the viewpoint of improving the reactivity of the carboxylic acid component and the alcohol component and the adhesion to the substrate.

The unsaturated aliphatic dicarboxylic acid is preferably fumaric acid or maleic acid, and more preferably fumaric acid. The saturated aliphatic dicarboxylic acid is preferably adipic acid or succinic acid (succinic acid may be substituted with an alkyl group and/or an alkenyl group).

The alicyclic dicarboxylic acid is preferably cyclohexanedicarboxylic acid, decalinedicarboxylic acid, or tetrahydrophthalic acid.

The trivalent or higher polycarboxylic acid is preferably trimellitic acid or pyromellitic acid.

The carboxylic acid component can be used alone in 1 or a combination of 2 or more.

(production of polyester)

The polyester can be produced, for example, by the following method: the alcohol component and the carboxylic acid component are subjected to polycondensation at a temperature of 180 ℃ to 250 ℃ in an inert gas atmosphere, if necessary, using an esterification catalyst.

From the viewpoint of particle size control when the obtained polyester is used as resin particles, it is preferable that the polyester has a narrow molecular weight distribution, and polycondensation is preferably performed using an esterification catalyst.

Examples of the esterification catalyst include tin catalysts, titanium catalysts, metal compounds such as antimony trioxide, zinc acetate, and germanium dioxide. From the viewpoint of reaction efficiency of the esterification reaction in the production of a polyester, a tin catalyst is preferred. The tin catalyst is preferably dibutyltin oxide, tin (II) bis (2-ethylhexanoate), or a salt thereof, and more preferably tin (II) bis (2-ethylhexanoate).

If necessary, an esterification co-catalyst such as 3,4, 5-trihydroxybenzoic acid can be used. Further, a polymerization inhibitor such as 4-t-butylcatechol or hydroquinone may be used in combination.

The softening point of the polyester obtained is preferably 80 ℃ or higher, more preferably 85 ℃ or higher, and still more preferably 90 ℃ or higher, and preferably 170 ℃ or lower, more preferably 145 ℃ or lower, and still more preferably 125 ℃ or lower, from the viewpoint of improving the adhesion to the substrate.

The glass transition temperature (Tg) of the polyester obtained is preferably 50 ℃ or higher, more preferably 55 ℃ or higher, and preferably 95 ℃ or lower, more preferably 90 ℃ or lower, more preferably 85 ℃ or lower, and still more preferably 80 ℃ or lower, from the viewpoint of improving the adhesion to the substrate.

From the viewpoint of controlling the particle diameter of the resin particles and improving the adhesion to the substrate, the acid value of the polyester to be obtained is preferably 5mgKOH/g or more, more preferably 15mgKOH/g or more, and still more preferably 20mgKOH/g or more, and is preferably 40mgKOH/g or less, more preferably 37mgKOH/g or less, and still more preferably 35mgKOH/g or less.

The weight average molecular weight (Mw) of the obtained polyester is preferably 5,000 or more, more preferably 7,500 or more, still more preferably 10,000 or more, and preferably 10 ten thousand or less, more preferably 5 ten thousand or less, still more preferably 3 ten thousand or less, from the viewpoint of solvent resistance, dispersion stability, and the like.

[ vinyl Polymer ]

The vinyl polymer preferably contains 1 or more species selected from the group consisting of a structural unit derived from (a) an ionic monomer, a structural unit derived from (b) a hydrophobic monomer, and a structural unit derived from (c) a hydrophilic nonionic monomer, more preferably 2 or more species of these structural units, and still more preferably 3 species of these structural units, from the viewpoint of improving the dispersion stability of the pigment-containing polymer particles in the aqueous ink. For example, there may be mentioned: (a) a combination of an ionic monomer and (b) a hydrophobic monomer; (a) a combination of an ionic monomer, (b) a hydrophobic monomer, and (c) a hydrophilic nonionic monomer.

The vinyl polymer can be obtained, for example, by addition polymerization of a monomer mixture containing (a) an ionic monomer, (b) a hydrophobic monomer, and (c) a hydrophilic nonionic monomer by a known method.

(a) Ionic monomer

Examples of the ionic monomer (a) (hereinafter also referred to as "component (a)") include anionic monomers and cationic monomers, and anionic monomers are preferred.

Examples of the anionic monomer include a carboxylic acid monomer, a sulfonic acid monomer, and a phosphoric acid monomer.

Among the above anionic monomers, from the viewpoint of improving dispersion stability of the pigment-containing polymer particles in the aqueous ink, a carboxylic acid monomer having a carboxyl group is preferable, and acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethylsuccinic acid, and the like are more preferable, and 1 or more species selected from acrylic acid and methacrylic acid are more preferable.

Examples of the cationic monomer include N, N-dimethylaminoethyl methacrylate and N, N-dimethylaminoethylacrylamide.

In addition, the ionic monomer (a) includes a monomer that is not ionic under neutral conditions, such as an acid or an amine, and also includes a monomer that is ionic under acidic or basic conditions.

(b) Hydrophobic monomers

Examples of the hydrophobic monomer (b) (hereinafter also referred to as "component (b)") include alkyl (meth) acrylates and aromatic group-containing monomers.

The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 22 carbon atoms (preferably 6 to 18 carbon atoms), and examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tert) butyl (meth) acrylate, (iso) pentyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, and (iso) stearyl (meth) acrylate.

Further, "(iso or tertiary)" and "(iso)" mean both the case where these groups are present and the case where these groups are absent, and in the case where these groups are absent, they mean "normal". In addition, "(meth) acrylate" means acrylate and/or methacrylate.

The aromatic group-containing monomer is preferably a vinyl monomer having an aromatic group having 6 to 22 carbon atoms, and more preferably a styrene monomer, an aromatic group-containing (meth) acrylate, and a styrene macromonomer.

The styrene-based monomer is preferably styrene, 2-methylstyrene or divinylbenzene, and more preferably styrene. The aromatic group-containing (meth) acrylate is preferably benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, or the like, and more preferably benzyl (meth) acrylate.

The styrene-based macromonomer is a compound having a polymerizable functional group at one end and preferably having a number average molecular weight of 500 or more, more preferably 1,000 or more, and preferably 100,000 or less, more preferably 10,000 or less. As the polymerizable functional group, an acryloyloxy group or a methacryloyloxy group is preferable, and a methacryloyloxy group is more preferable.

Specific examples of the styrenic macromonomer include AS-6 (S), AN-6 (S), HS-6 (S) (trade name of Toyo chemical Co., Ltd.).

(c) Hydrophilic nonionic monomer

Examples of the hydrophilic nonionic monomer (c) (hereinafter also referred to as "component (c)") include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, polypropylene glycol (n ═ 2 to 30, n represents the average number of addition moles of oxyalkylene groups, the same applies hereinafter), polyalkylene glycol (meth) acrylates such as polyethylene glycol (meth) acrylates (n ═ 2 to 30), methoxypolyethylene glycol (n ═ 1 to 30) (meth) acrylates, alkoxypolyalkylene glycol (meth) acrylates such as octyloxypolyethylene glycol (n ═ 1 to 30) (meth) acrylates, and phenoxy (ethylene glycol-propylene glycol copolymerization) (n ═ 1 to 30), and ethylene glycol (n ═ 1 to 29) (meth) acrylates.

Specific examples of commercially available component (c) include: NK ESTER M-20G, NK ESTER M-40G, NK ESTER M-90G, NK ESTER M-230G, etc. of New Zhongcun chemical industries; BLEMMER PE-90, BLEMMER PE-200, BLEMMER PE-350, etc. available from Nichigan corporation; PME-100, PME-200, PME-400, etc.; PP-500, PP-800, PP-1000, and the like; AP-150, AP-400, AP-550, etc.; 50 PEP-300, 50 POEP-800B, 43 PAPE-600B, etc.

The components (a) to (c) can be used alone or in combination of 2 or more.

The vinyl polymer may contain a structural unit derived from a monomer other than the above.

(content of each component or structural unit in the vinyl Polymer)

From the viewpoint of improving the dispersion stability of the pigment-containing polymer particles in the aqueous ink, the content of the structural unit derived from each component in the vinyl polymer is as follows.

(a) The content of the ionic monomer is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 8% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass, and still more preferably 40% by mass or less.

(b) The content of the hydrophobic monomer is preferably 20% by mass or more, more preferably 40% by mass or more, and still more preferably 50% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 75% by mass or less.

When the hydrophilic nonionic monomer (c) is contained, the content thereof is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% by mass or more, and is preferably 60% by mass or less, more preferably 55% by mass or less, and still more preferably 50% by mass or less.

When the macromonomer is contained as the component (b), the content of the macromonomer is preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less.

The mass ratio of the ionic monomer (a) to the hydrophobic monomer (b) containing the macromonomer ((a)/(b)) is preferably 0.01 or more, more preferably 0.05 or more, and still more preferably 0.10 or more, and is preferably 1 or less, more preferably 0.60 or less, and still more preferably 0.50 or less.

(production of vinyl Polymer)

The vinyl polymer is produced by copolymerizing a monomer mixture by a known polymerization method. As the polymerization method, a solution polymerization method is preferable.

As the solvent used in the solution polymerization method, a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. The polar organic solvent is preferably an aliphatic alcohol having 1 to 3 carbon atoms, a ketone having 3 to 8 carbon atoms, or a mixed solvent of 1 or more of these and water.

In the polymerization, a known radical polymerization initiator such as an azo compound or an organic peroxide can be used. The amount of the radical polymerization initiator is preferably 0.01 to 2 moles per 1 mole of the monomer mixture.

The polymerization conditions of the monomer mixture vary depending on the kind of the radical polymerization initiator, the monomer, the solvent, etc. used, and therefore, it cannot be said that, in general, the polymerization temperature is preferably 50 to 80 ℃ and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably an inert gas atmosphere such as a nitrogen atmosphere.

From the viewpoint of improving the productivity of the aqueous dispersion of pigment-containing polymer particles, it is preferable that the vinyl polymer is used as a polymer solution without removing a solvent used for the polymerization.

From the viewpoint of improving the productivity of the aqueous dispersion of pigment-containing polymer particles, the solid content concentration of the polymer solution is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 70% by mass or less, more preferably 65% by mass or less.

From the viewpoint of improving dispersion stability, the weight average molecular weight of the polymer is preferably 8,000 or more, more preferably 10,000 or more, and still more preferably 11,000 or more, and is preferably 50 ten thousand or less, more preferably 30 ten thousand or less, and still more preferably 10 ten thousand or less. Further, the determination of the weight average molecular weight can be performed by the method described in examples.

Examples of commercially available products of vinyl polymers include polyacrylic acids such as "Aron AC-10 SL" (manufactured by east asian co., ltd.), styrene-acrylic resins such as "Joncryl 67", "Joncryl 611", "Joncryl 678", "Joncryl 680", "Joncryl 690" and "Joncryl 819" (manufactured by BASF Japan).

The pigment used in the aqueous dispersion and the aqueous ink is not particularly limited, and may be an organic pigment, or a mixture thereof.

The solid content concentration (non-volatile content concentration) of the obtained pigment water dispersion is preferably 10 to 30% by mass, more preferably 15 to 25% by mass, from the viewpoint of improving the dispersion stability of the pigment water dispersion and from the viewpoint of facilitating the preparation of the aqueous ink.

The solid content concentration of the pigment water dispersion can be measured by the method described in examples.

The average particle diameter of the pigment-containing polymer particles in the pigment water dispersion is preferably 50 to 200nm, more preferably 60 to 190nm, and still more preferably 80 to 180nm, from the viewpoint of reducing coarse particles and improving the ejection stability of the aqueous ink.

The average particle diameter of the pigment-containing polymer particles can be measured by the method described in examples.

The average particle diameter of the pigment-containing polymer particles in the aqueous ink is the same as the average particle diameter in the aqueous pigment dispersion, and the preferable mode of the average particle diameter is the same as the preferable mode of the average particle diameter in the aqueous pigment dispersion.

< aqueous dispersion for inkjet recording >

The aqueous dispersion for inkjet recording is produced by: the cleaning agent composition and the cleaning method of the present invention are used for cleaning at least a hard surface of a substrate, and then the substrate is granulated in an aqueous medium, using an apparatus for producing an aqueous dispersion having a hard surface to which a polymer or the like is adhered.

The content of the polymer in the aqueous dispersion is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and still more preferably 3 to 10% by weight, from the viewpoint of print density and storage stability of the aqueous ink containing the aqueous dispersion.

From the same viewpoint as above, the content of the colorant in the aqueous dispersion is preferably 1 to 30% by weight, more preferably 2 to 25% by weight, more preferably 4 to 20% by weight, and still more preferably 5 to 15% by weight.

The content of water in the aqueous dispersion is preferably 30 to 95 wt%, more preferably 40 to 90 wt%, and still more preferably 50 to 80 wt%.

[ Water-based ink for ink-jet recording ]

The aqueous ink for inkjet recording is prepared by adding and mixing an organic solvent and water as needed to the aqueous dispersion obtained by the above method, and among them, a latex emulsion, a wetting agent, a penetrating agent, a dispersing agent, an antifoaming agent, a preservative, and the like, which are generally used in aqueous inks, may be further added.

The content of the polymer in the aqueous ink is preferably 1 to 20% by weight, more preferably 2 to 15% by weight, and still more preferably 3 to 10% by weight, from the viewpoint of print density and storage stability of the aqueous ink.

The content of the colorant in the aqueous ink is preferably 1 to 25% by weight, more preferably 2 to 20% by weight, more preferably 3 to 18% by weight, and still more preferably 4 to 15% by weight, from the viewpoint of improving the print density of the ink.

The water content in the water-based ink is preferably 20 to 90 wt%, more preferably 30 to 80 wt%, and still more preferably 40 to 70 wt%.

The viscosity of the aqueous ink at 32 ℃ is preferably 2 to 12 mPas, more preferably 3 to 9 mPas, and still more preferably 4 to 8 mPas, from the viewpoint of storage stability of the aqueous ink.