JP2016216600A - Ink, ink accommodation container and manufacturing method of ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink that prevents the deposition of titanium dioxide as a coloring agent and is capable of easily re-dispersing titanium dioxide even when it is deposited.SOLUTION: There is provided an ink containing titanium dioxide and water, where average value (%) M of supernatant relative change amount percentage after standing at 25°C for 240 hours by integration of back scattered light strength peak with the deposition of the titanium dioxide in the ink and viscosity η(mPa s) at 25°C of a liquid after removing the titanium dioxide from the ink satisfy the formula [(M×η)]/10<10.SELECTED DRAWING: None

Description

  The present invention relates to an ink, an ink container, and an ink manufacturing method.

  2. Description of the Related Art Conventionally, an ink jet recording method for forming characters and images on a recording medium by discharging ink droplets from nozzles of an ink jet recording head is known. In addition, when recording a color image on a transparent recording medium or a recording medium that is not white, a white ink is used to lower the transparency of the transparent recording medium or improve the color image coloring property. Shielding of the background color is performed.

  A white ink using titanium dioxide as a colorant has a specific gravity larger than that of an organic colorant, so that titanium dioxide is likely to settle. Therefore, an image forming apparatus equipped with a stirring mechanism or a circulation mechanism has been used.

  With regard to such a white ink having titanium dioxide as a colorant, for example, titanium oxide is surface-treated with a silane coupling agent in addition to alumina and silica, and a white aqueous colorant for ink jet recording in which the ratio of alumina treatment amount is defined. A dispersion has been proposed (see Patent Document 1).

  An object of the present invention is to provide an ink in which titanium dioxide, which is a colorant, does not easily settle, and can be easily redispersed even if it settles.

The ink of the present invention as means for solving the above problems is an ink containing titanium dioxide and water,
An average value (%) M of the percentage of the relative change in the supernatant after 240 hours of standing at 25 ° C. in the integration of the backscattered light intensity peak accompanying the precipitation of the titanium dioxide in the ink;
The viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink satisfies the following formula: [(M × η _V )] / 10 <10.

  According to the present invention, it is possible to provide an ink in which titanium dioxide, which is a colorant, hardly settles and can be easily redispersed even if it settles.

FIG. 1 is a schematic diagram illustrating an example of an ink container. FIG. 2 is a schematic view including the case of the ink container of FIG. FIG. 3 is a perspective view showing an example of an ink jet recording apparatus. FIG. 4 is a schematic sectional view showing the ink jet recording apparatus of FIG. FIG. 5 is a main part schematic plan view showing a mechanism part of the ink jet recording apparatus of FIG.

(ink)
The ink of the present invention contains titanium dioxide and water, preferably further contains a water-soluble organic solvent, and further contains other components as necessary.

In the present invention, the average value (%) M of the percentage of the relative change in the supernatant after 240 hours of standing at 25 ° C., which is the sum of the backscattered light intensity peaks associated with the precipitation of the titanium dioxide in the ink,
The viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink satisfies the following formula (1).
<Formula (1)>
[(M × η _V )] / 10 <10
The left side of the formula (1) is a value normalized as a sedimentation index corresponding to a dispersion medium viscosity of 10 mPa · s based on the particle sedimentation speed according to the Stokes type dispersion medium viscosity, and is less than 10.
By satisfy | filling the requirements of said Formula (1), the titanium dioxide particle surface can have moderate hydrophilicity and hydrophobicity with sufficient balance.
The viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink can be measured at 25 ° C. using a known viscosity measuring device. The liquid after removing the titanium dioxide from the ink can be prepared as a supernatant obtained by precipitating titanium dioxide after the ink has been stored for a long time (for example, for one month or longer). Moreover, when long-term stationary storage is difficult, it can prepare as a supernatant which precipitated the titanium dioxide by centrifugation (58,000 rpm, 1 minute-60 minutes), for example.
The viscosity η _{V at} 25 ° C. of the liquid after removing the titanium dioxide from the ink is preferably 5 mPa · s or more and 60 mPa · s or less.

It is preferable that the average value (%) of the percentage of the relative change in the supernatant after 240 hours of standing at 25 ° C. as the integrated backscattered light intensity peak accompanying the precipitation of the titanium dioxide in the ink is less than 5%. .
When the average value (%) of the percentage of the relative change in the supernatant is less than 5%, the titanium dioxide as the coloring agent is difficult to settle, and even if it settles, it can be easily redispersed.
The average value (%) of the percentage of relative change in the supernatant is suitably used as an index of titanium dioxide sedimentation that can be quantified even in a thick dispersion of titanium dioxide where it is difficult to visualize the sedimentation of titanium dioxide. Is done.
The average value (%) of the percentage of the relative change in the supernatant can be measured as follows using, for example, Turbscan MA2000 manufactured by Formal Action.
The ink is subjected to ultrasonic dispersion treatment (100 W, 40 minutes) using an ultrasonic cleaner (US-3, manufactured by ASONE Co., Ltd.) to be in a uniform state, and then the ink is applied to a glass cell dedicated to the apparatus using a pipette. Add 5.5 mL.
Measurement is performed 30 minutes after the ink level in the glass cell is stabilized, and this time is set as the start of sedimentation evaluation. Then, it is allowed to stand at 25 ° C. and measured until 240 hours later, and the sedimentation property of titanium dioxide is confirmed by a deviation display based on the start of sedimentation evaluation. Confirmation of the sedimentation is performed by integrating the backscattered light intensity peaks accompanying sedimentation of titanium dioxide (20 mm below the sample tube to the liquid surface) at an average value (%) ).

<Titanium dioxide>
The ink of the present invention contains titanium dioxide as a colorant.
The titanium dioxide is preferably titanium dioxide surface-treated with a phosphonic acid derivative, and is preferably titanium dioxide having a group composed of the phosphonic acid derivative on the surface. Further, the titanium dioxide is more preferably titanium dioxide having a group composed of a phosphonic acid derivative having one organic phosphonic acid group in the molecule by surface treatment with the phosphonic acid derivative and hydrolysis.

The cumulative 50% particle size (D50) in the volume-based particle size distribution of titanium dioxide is preferably 200 nm to 600 nm, more preferably 210 nm to 500 nm, and still more preferably 210 nm to 320 nm. If the cumulative particle diameter is in the range of 50%, the concealability of the printed image can be ensured, the clogging of the ink flow path and the discharge nozzle in the image forming apparatus can be suppressed, and the apparatus can be operated stably. It becomes possible.
The cumulative 50% particle diameter (D50) can be measured by, for example, a particle size distribution measuring device (Microtrac UPA-EX150, manufactured by Nikkiso Co., Ltd.).

  The content of the titanium dioxide is preferably 1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the total amount of the ink.

  The type of titanium dioxide used for performing the surface treatment is not particularly limited and may be appropriately selected depending on the purpose. The surface may be untreated, and the phosphonic acid derivative There is no particular limitation as long as the wettability is improved and the treatment efficiency is improved, and it can be appropriately selected according to the purpose. Examples thereof include oxides such as aluminum, silicon, zirconium, and zinc.

The titanium dioxide is preferably titanium dioxide surface-treated with at least one of a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative. More preferred is titanium dioxide surface-treated on both sides.
Since the titanium dioxide is surface-treated with at least one of a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative, the titanium dioxide as a colorant is difficult to settle, and even if it settles. Easy re-dispersion.

-Phosphonic acid derivative-
The phosphonic acid derivative may have a substituent represented by the general formula: R—P (═O) (OH) ₂ (R: an alkyl group which may have a substituent). And an organic phosphonic acid having a phosphate group. The phosphonic acid derivative preferably has one phosphate group in the molecule.
Examples of the phosphonic acid derivative include hydrophilic phosphonic acid derivatives and hydrophobic phosphonic acid derivatives. The hydrophilicity and hydrophobicity of the phosphonic acid derivative are determined by the hydrophilicity and hydrophobicity of the alkyl group which may have the substituent.
There is no restriction | limiting in particular as carbon number of the said alkyl group, Although it can select suitably according to the objective, 1 or more and 20 or less are preferable, and 2 or more and 18 or less are more preferable.

--Hydrophilic phosphonic acid derivative--
Examples of the hydrophilic phosphonic acid derivative include a phosphonic acid derivative having a hydrophilic substituent, and examples of the substituent include a hydroxyl group, an amino group, a carboxyl group, and an oligoethylene glycol ester. Group, phthalimide group and the like.
Among these, compounds represented by the following structural formulas (H-1) to (H-5) are preferable, and compounds represented by the following structural formulas (H-1) to (H-4) are more preferable.

<H-1>

<H-2>

<H-3>

<H-4>

<H-5>

-Hydrophobic phosphonic acid derivative-
Examples of the hydrophobic phosphonic acid derivative include a phosphonic acid derivative having an unsubstituted alkyl group, a phosphonic acid derivative having a hydrophobic substituent, and the like. Substituents having a fluoro group such as a fluoroalkyl group (for example, CF ₃ (CF ₂ ) ₃ —, CF ₃ (CF ₂ ) ₅ —, CF ₃ (CF ₂ ) ₇ —), 3,5-difluorophenyl group, etc. Is mentioned.
Among these, for example, compounds represented by the following structural formulas (L-1) to (L-5) are preferable, and compounds represented by the following structural formulas (L-1) to (L-4) are more preferable. .

<L-1>

<L-2>

<L-3>

<L-4>

<L-5>

Hydrophobicity H1 of titanium dioxide surface-treated with the hydrophilic phosphonic acid derivative and the hydrophobic phosphonic acid derivative,
Hydrophobicity H2 of titanium dioxide surface-treated with the hydrophilic phosphonic acid derivative and not surface-treated with the hydrophobic phosphonic acid derivative;
It is preferable that the degree of hydrophobicity H3 of titanium dioxide surface-treated with the hydrophobic phosphonic acid derivative and not surface-treated with the hydrophilic phosphonic acid derivative satisfies the following formula: H2 <H1 <H3.
Thereby, the surface of titanium dioxide can have moderate hydrophilicity and hydrophobicity in good balance.

  The hydrophobization degree (%) of the titanium dioxide can be determined by a method of measuring the floating ratio of titanium dioxide with respect to each solvent prepared by changing the volume ratio of water-methanol. For example, a powder wettability tester ( WET-101P (manufactured by Reska) can be used.

The hydrophobicity of titanium dioxide surface-treated with the phosphonic acid derivative is preferably 5% or more and 45% or less, and more preferably 15% or more and 40% or less. Thereby, the titanium dioxide particle surface can have moderate hydrophilicity and hydrophobicity in a well-balanced manner, and excellent sedimentation resistance and redispersibility of titanium dioxide can be obtained.
The degree of hydrophobicity can be controlled by adjusting the type, combination, quantity ratio, and the like of the phosphonic acid derivative used.

--Group consisting of phosphonic acid derivative--
The group composed of the phosphonic acid derivative is a group (organic phosphonic acid group) in which two H ⁺ are removed from the phosphoric acid group of the phosphonic acid derivative, and has a general formula: RP (═O) (O ⁻ ) ₂ (R: an alkyl group which may have a substituent).
The titanium dioxide is more preferably titanium dioxide having on the surface at least one of a group consisting of a hydrophilic phosphonic acid derivative and a group consisting of a hydrophobic phosphonic acid derivative, and a group consisting of a hydrophilic phosphonic acid derivative. Particularly preferred is titanium dioxide having on the surface both a group composed of a hydrophobic phosphonic acid derivative.

Titanium dioxide having a group composed of the phosphonic acid derivative on the surface is obtained by surface-treating titanium dioxide with the phosphonic acid derivative.
Examples of the surface treatment method include a method of immersing the titanium dioxide together with a phosphonic acid derivative together with a solvent as necessary. At this time, the titanium dioxide is preferably dried before the surface treatment, and the surface treatment can be suitably performed by drying in the range of 80 ° C. to 150 ° C. for 1 hour to 1 week.
There is no restriction | limiting in particular as said solvent, According to the objective, it can select suitably, For example, methanol, ethanol, isopropyl alcohol (IPA), tetrahydrofuran (THF) etc. are mentioned.
Next, after immersing the titanium dioxide together with the phosphonic acid derivative, the solvent is removed by a drying process such as a vacuum dryer.
In addition, it is possible to shorten a drying process by isolate | separating the said titanium dioxide and a solvent by centrifugation etc. before the said drying process. Then, the surface treatment by the dehydration condensation reaction of the said titanium dioxide and phosphonic acid is completed by performing a heating process. As said heating process, it is preferable to heat at 120 degreeC or more and 150 degrees C or less for 1 hour or more and 2 days or less.

The phosphonic acid derivative is manufactured by Dojindo Laboratories Co., Ltd., and commercially available products can be purchased from Wako Pure Chemical Industries, Ltd.
In addition, if the degree of hydrophobicity of titanium dioxide surface-treated with a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative is controlled, the titanium dioxide is less likely to settle in the dispersion and can be easily precipitated. It becomes possible to redistribute.

  Titanium dioxide surface-treated with the hydrophilic phosphonic acid derivative and the hydrophobic phosphonic acid derivative comprises the hydrophilic phosphonic acid derivatives represented by the structural formulas (HH-1) to (HH-4). At least one selected from the group and at least one selected from the group consisting of the hydrophobic phosphonic acid derivatives represented by the structural formulas (LL-1) to (LL-4). It is preferable from the viewpoint of achieving both sedimentation resistance, redispersibility and image hiding properties.

--Group consisting of hydrophilic phosphonic acid derivative--
Examples of the group consisting of the hydrophilic phosphonic acid derivative include groups represented by the following structural formulas (HH-1) to (HH-5). Among these, at least one selected from groups represented by the following structural formulas (HH-1) to (HH-4) is preferable.

<HH-1>

<HH-2>

<HH-3>

<HH-4>

<HH-5>

--Group consisting of hydrophobic phosphonic acid derivative--
Examples of the group comprising the hydrophobic phosphonic acid derivative include groups represented by the following structural formulas (LL-1) to (LL-5). Among these, at least one selected from the following structural formulas (LL-1) to (LL-4) is preferable.

<LL-1>

<LL-2>

<LL-3>

<LL-4>

<LL-5>

Hydrophobicity HH1 of titanium dioxide having a group consisting of the hydrophilic phosphonic acid derivative and a group consisting of a hydrophobic phosphonic acid derivative on the surface;
Hydrophobic degree HH2 of titanium dioxide having a group consisting of the hydrophilic phosphonic acid derivative on the surface and not having a group consisting of the hydrophobic phosphonic acid derivative on the surface;
The degree of hydrophobicity HH3 of titanium dioxide having a group composed of the hydrophobic phosphonic acid derivative on the surface and not having a group composed of the hydrophilic phosphonic acid derivative on the surface is expressed by the following formula: HH2 <HH1 <HH3 It is preferable to satisfy.
Thereby, the surface of titanium dioxide can have moderate hydrophilicity and hydrophobicity in good balance.

  The hydrophobization degree (%) of the titanium dioxide can be determined by a method of measuring the floating ratio of titanium dioxide with respect to each solvent prepared by changing the volume ratio of water-methanol. For example, a powder wettability tester ( WET-101P (manufactured by Reska) can be used.

The group consisting of the phosphonic acid derivative is covalently bonded to the titanium dioxide surface at the phosphonic acid moiety.
Here, the confirmation of the group consisting of the phosphonic acid derivative was carried out by separating and washing the surface-treated titanium dioxide, removing the mixture, and then subjecting the phosphonic acid derivative liberated by hydrolysis to microscopic FT-IR, NMR, The identification can be performed by using a combination of various analytical instruments such as GC-MS and LCD-MS.

Hereinafter, a method for identifying the surface-treated titanium dioxide phosphonic acid derivative will be described.
First, the surface-treated titanium dioxide particles are separated from other components in the ink by ink centrifugation.
Next, after washing titanium dioxide with a solvent such as ethanol, the solvent is dried under reduced pressure at room temperature.
Next, the phosphonic acid derivative ester of the dried surface-treated titanium dioxide is hydrolyzed with an alkali having a pH of 12 or more and 13 or less, and then the titanium dioxide particles are separated by centrifugation, and the phosphonic acid derivative released from the surface-treated titanium dioxide. The solution containing is recovered. As a solvent to be used, water, methanol, tetramethylammonium hydroxide (TMAH) or the like alone or a mixed solvent thereof can be used.
Next, if the obtained solution is analyzed by GC-MS or LC-MS according to the molecular weight, it can be discriminated whether it is a mixture of phosphonic acid derivatives or a simple substance. Moreover, the kind of phosphonic acid derivative can be identified from MS fraction library comparison.

<Water>
There is no restriction | limiting in particular as said water, According to the objective, it can select suitably, For example, pure water, such as ion-exchange water, ultrafiltration water, reverse osmosis water, distilled water; Ultrapure water etc. are mentioned. . These may be used individually by 1 type and may use 2 or more types together.
The water content is preferably 15% by mass or more and 60% by mass or less, and more preferably 25% by mass or more and 50% by mass or less, based on the total amount of the ink.

<Water-soluble organic solvent>
The water-soluble organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3 -Butanediol, 3-methyl-1,3-butanediol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, 3-ethyl-3-hydroxymethyloxetane, 2-pyrrolidone, glycerin Etc.
Among these, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy-1-butanol 3-methoxy-3-methyl-1-butanol is preferred.
The content of the water-soluble organic solvent is preferably 10% by mass or more and 70% by mass or less, and more preferably 20% by mass or more and 60% by mass or less with respect to the total amount of the ink.

<Other ingredients>
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a dispersing agent, surfactant, resin emulsion, a penetrating agent, a pH adjuster, antiseptic / antifungal agent etc. are mentioned. .

-Dispersant-
As the dispersant, a dispersant conventionally used for preparing a pigment dispersion can be used.
Preferred examples of the commercially available dispersant include DISPERBYK-180, DISPERBYK-190, DISPERBYK-198, DISPERBYK-2010, DISPERBYK-2012, and DISPERBYK-2015 (all manufactured by BYK Chemie). Among these, DISPERBYK-190 is more preferable.

-Surfactant-
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. However, silicone surfactants and fluorosurfactants are preferred from the viewpoint of good leveling and improved wettability. And a fluorine-based surfactant is particularly preferable. These are indispensable when they are used in common as ink that can be printed on plain paper.
Also, when printing on plastic surface sheets, keeping the surface tension low with a surfactant improves wettability and leveling on the media surface, and has a positive effect on drying and image quality uniformity. .

  Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Examples include polyoxyalkylene ether polymer compounds. Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain has a low foaming property, and the bioaccumulation property of a fluorine compound that has been regarded as a problem in recent years is low and highly safe. Particularly preferred.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate.
Examples of the perfluoroalkyl carboxylic compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylic acid salts.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters and perfluoroalkyl phosphate salts.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether having a perfluoroalkyl ether group in the side chain. Examples thereof include a sulfate salt of a polymer and a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.
Examples of the salt counter ion in these fluorosurfactants include Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ and the like.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used. Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.), Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited), MegaFuck F-470, F1405 , F-474 (all manufactured by DIC Corporation), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110 , FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Corporation), PF-151N ( Omninova).
Among these, FT-110, FT-250, FT-251, FT-400S, FT-150, manufactured by Neos Co., Ltd., from the point that good print quality, particularly color developability, and leveling on paper are significantly improved. FT-400SW and OM-nova PF-151N are particularly preferred.

The silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, and side chain. Examples thereof include polydimethylsiloxane modified at both ends.
As the modifying group, those using a polyoxyethylene group or a polyoxyethylene polyoxypropylene group exhibit good properties as an aqueous surfactant.

Such a surfactant can be easily obtained as a commercial product from Big Chemie, Shin-Etsu Silicone, Toray Dow Corning, or the like.
The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the dimethylpolysiloxane Si part. It is done.
Commercially available products can be used as the polyether-modified silicone compound, such as KF-618, KF-642, KF-643 (all manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-347, BYK-348, BYK-UV3500, 3510, 3530, 3570 (by Big Chemie Japan Co., Ltd.) and the like can be mentioned.

In addition to the fluorine-based surfactant and the silicone-based surfactant, anionic surfactants, nonionic surfactants, amphoteric surfactants, acetylene glycol surfactants, and the like can be used.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, , 5-dimethyl-1-hexyn-3-ol and the like.
Examples of commercially available acetylene glycol surfactants include Surfynol 104, 82, 465, 485, and TG manufactured by Air Products (USA).
The said surfactant is not limited to these, You may use individually by 1 type, or may mix and use multiple things. Even if one kind alone does not dissolve easily in ink, it can be solubilized by mixing and can exist stably.
Among these surfactants, a silicone surfactant is preferable, and a nonionic silicone surfactant containing a polyether-modified silicone compound is more preferable.

(Ink dispersion)
The ink dispersion of the present invention contains titanium dioxide and a water-soluble organic solvent, and further contains water and other components as necessary.

<Titanium dioxide>
As the titanium dioxide, the titanium dioxide of the ink of the present invention is used.
The content of the titanium dioxide is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 40% by mass or less with respect to the total amount of the ink dispersion.

<Water-soluble organic solvent>
Examples of the water-soluble organic solvent include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, and 3-methoxy. At least one selected from -1-butanol and 3-methoxy-3-methyl-1-butanol is used.
The content of the water-soluble organic solvent is preferably 1% by mass or more and 99% by mass or less, and more preferably 5% by mass or more and 70% by mass or less with respect to the total amount of the ink dispersion.

<Water>
There is no restriction | limiting in particular as said water, According to the objective, it can select suitably, For example, pure water, such as ion-exchange water, ultrafiltration water, reverse osmosis water, distilled water; Ultrapure water etc. are mentioned. . These may be used individually by 1 type and may use 2 or more types together.
The content of the water is preferably 0% by mass or more and 98% by mass or less, and more preferably 5% by mass or more and 90% by mass or less with respect to the total amount of the dispersion liquid for ink.

<Other ingredients>
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, the said surfactant, the said dispersing agent, etc. are mentioned.
The ink dispersion liquid is not particularly limited and may be appropriately selected depending on the intended purpose. However, it can be produced in the same manner as the dispersion step of the ink production method described later.

(Ink production method)
The ink production method of the present invention includes at least a surface treatment step and a dispersion step, preferably includes an ink preparation step, and further includes other steps as necessary.

<Surface treatment process>
The surface treatment step is a step of surface-treating titanium dioxide with a phosphonic acid derivative.
As the phosphonic acid derivative, those similar to the ink can be used. The phosphonic acid derivative is preferably at least one of a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative, more preferably both a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative. preferable.

<Dispersing process>
In the dispersing step, the surface-treated titanium dioxide is converted into 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butane. It is a step of dispersing with a dispersion medium containing at least one water-soluble organic solvent selected from diol, 3-methoxy-1-butanol, and 3-methoxy-3-methyl-1-butanol and water.
The dispersion is not particularly limited and can be appropriately selected depending on the purpose. For example, the dispersion can be performed using a sand mill, a homogenizer, a ball mill, a bead mill, a paint shaker, an ultrasonic disperser, or the like.

<Ink preparation process>
In addition to the titanium dioxide dispersion prepared in the dispersion step, a water-soluble organic solvent, and an ink dispersion containing water, if necessary, a solvent, a resin emulsion, a penetrant, a pH adjuster, an antiseptic / antifungal agent, etc. Ink can be manufactured by adding and stirring and mixing.
There is no restriction | limiting in particular in the said stirring mixing, According to the objective, it can select suitably, For example, it can carry out with the stirrer using a stirring blade, a magnetic stirrer, a high-speed disperser etc.

-Physical properties of ink-
The physical properties of the ink are not particularly limited and may be appropriately selected depending on the intended purpose. For example, the viscosity and surface tension are preferably in the following ranges.
The viscosity at 25 ° C. of the ink is preferably 2 mPa · s or more and 25 mPa · s or less, more preferably 2 mPa · s or more and 20 mPa · s or less, and further preferably 10 mPa · s or more and 12 mPa · s or less. By setting the viscosity of the ink to 2 mPa · s or more, there is an effect that residual vibration is less likely to occur at the time of ink discharge, vibration after the discharge by the drive waveform can be easily suppressed, and the next discharge can be performed in a short time. This makes it suitable for high-speed printing. On the other hand, by suppressing the viscosity of the ink to 20 mPa · s or less, it becomes easy to stabilize the ejection performance.
Here, the viscosity can be measured at 25 ° C. using, for example, an R-type rotational viscometer (RE550L, manufactured by Toki Sangyo Co., Ltd.).

  The surface tension of the ink is preferably 30 mN / m or less, more preferably 28 mN / m or less at 25 ° C. When the surface tension of the ink is 30 mN / m or less, the permeability is improved and the beading is reduced, so that the drying property for printing on plain paper is improved. Moreover, since it becomes easy to get wet with a pretreatment layer, color developability improves. On the other hand, if the surface tension of the ink exceeds 30 mN / m, leveling of the ink on the recording medium is difficult to occur, and the drying time may be prolonged (drying property is deteriorated).

Since the ink of the present invention can perform recording with sufficient whiteness and high visibility on various surfaces such as low brightness substrates such as black and transparent substrates, industrial products such as plastic products It is useful for marking on
In addition, since the titanium dioxide, which is a colorant, does not easily settle and can be easily redispersed even when the ink is settled, the ink can be suitably used for various applications such as ink for ink jet recording and paint. .

(Ink container)
The ink container of the present invention includes the ink of the present invention and a container, and further includes other members such as an ink bag as necessary. Accordingly, it is not necessary to directly touch the ink in operations such as ink replacement, there is no concern about dirt on fingers and clothes, and foreign matters such as dust can be prevented from being mixed into the ink.

Examples of the ink container include an ink cartridge and an ink tank.
There is no restriction | limiting in particular as said container, The shape, a structure, a magnitude | size, a material, etc. can be suitably selected according to the objective, For example, it has an ink bag etc. which were formed with the aluminum laminate film, the resin film, etc. A thing etc. are suitable.

The ink container will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating an example of an ink bag 241 of an ink container, and FIG. 2 is a schematic diagram illustrating an ink container 200 in which the ink bag 241 of FIG. 1 is stored in a cartridge case 244.
As shown in FIG. 1, after filling ink into the ink bag 241 from the ink inlet 242 and exhausting the air remaining in the ink bag, the ink inlet 242 is closed by fusion. In use, the needle of the apparatus main body is pierced into the ink discharge port 243 made of a rubber member and supplied to the apparatus. The ink bag 241 is formed of a packaging member such as a non-permeable aluminum laminate film. As shown in FIG. 2, the ink container 200 is usually housed in a plastic cartridge case 244 and detachably attached to the ink jet discharge apparatus as the ink container 200.
The ink container is preferably detachable from the ink jet discharge device. Thereby, replenishment and replacement of ink can be simplified and workability can be improved.

(Inkjet ejection device)
The inkjet discharge apparatus of the present invention includes the ink container of the present invention, preferably includes an ink discharge unit, and further includes other units as necessary.

<Ink ejection means>
The ink discharge means is means for discharging ink onto the surface of the substrate by an ink jet recording method.
Examples of the ink ejection unit include a continuous ejection type and an on-demand type.
Examples of the on-demand type include a piezo method, a thermal method, and an electrostatic method.
The size of the ejected ink droplet is preferably, for example, 3 pL or more and 40 pL or less, and the ejection speed is preferably 5 m / s or more and 20 m / s or less. The driving frequency is preferably 1 kHz or higher, and the resolution is preferably 300 dpi or higher.

-Base material-
There is no restriction | limiting in particular as said base material, According to the objective, it can select suitably, For example, paper, a plastics, a metal, a ceramic, glass, or these composite materials etc. are mentioned.
Among these, the ink of the present invention is made of polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, ABS resin, polyvinyl chloride, polystyrene, acrylic resin, polyester resin, polyamide resin, vinyl-based material, or a composite material thereof. A plastic film or a plastic molding is more preferable.

<Other means>
There is no restriction | limiting in particular as said other means, According to the objective, it can select suitably, For example, a drying means, a conveyance means, a control means, etc. are mentioned.

Next, with reference to FIGS. 3 to 5, the ink jet discharge apparatus of the present invention will be described in more detail.
The ink jet recording apparatus shown in FIG. 3 stocks an apparatus main body 101, a paper feed tray 102 for loading paper mounted on the apparatus main body 101, and paper on which an image is recorded (formed) mounted on the apparatus main body 101. And a paper discharge tray 103. The upper surface of the upper cover 111 of the apparatus main body 101 is a substantially flat surface, and the front surface 112 of the front cover of the apparatus main body 101 is inclined obliquely rearward with respect to the upper surface. A paper discharge tray 103 and a paper feed tray 102 protruding toward the front side are provided. Further, an ink cartridge loading section 104 is provided on the end portion of the front surface 112 so as to protrude forward from the front surface 112 and lower than the upper cover 111. An operation key or the like is provided on the upper surface of the ink cartridge loading section 104. An operation unit 105 such as a display is arranged. The ink cartridge loading unit 104 has an openable / closable front cover 115 for attaching and detaching the ink cartridge.

  As shown in FIGS. 4 and 5, in the apparatus main body 101, the carriage 133 is slidably held in the main scanning direction by a guide rod 131 and a stay 132 that are horizontally mounted on left and right side plates (not shown). Then, it is moved and scanned in the carriage scanning direction of FIG. 5 by a main scanning motor (not shown).

On the carriage 133, a recording head 134 composed of four ink jet heads for ejecting ink droplets of yellow, cyan, magenta, and black is arranged with a plurality of ink ejection openings in a direction intersecting with the main scanning direction to eject ink droplets. Wearing the direction downward.
As a head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change are used. A shape memory alloy actuator, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.

  In order to improve ejection stability and wiping properties, a layer formed of Ni / PTFE eutectoid, silicone resin, and fluorine-based water repellency-imparting agent is provided on the nozzle surface that is the ink ejection portion of the inkjet head. In the present invention, the surface energy of the inner wall of the nozzle hole is defined by the discharged liquid, but the surface energy of the nozzle surface is more effective when combined with that of the inner wall of the nozzle hole. Therefore, the inner wall of the nozzle hole is subjected to the same treatment as the nozzle surface as necessary.

  The carriage 133 is equipped with a sub tank 135 for each color for supplying ink of each color to the recording head 134. Ink is replenished and supplied to the sub tank 135 from the ink cartridge loaded in the ink cartridge loading unit 104 via an ink supply tube (not shown). On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 103, the paper 142 is fed separately from the paper stacking unit (pressure plate) 141 one by one. A separation pad 144 made of a material having a large friction coefficient is provided facing the paper roller (half-moon roller) 143 and the paper feed roller 143, and the separation pad 144 is biased toward the paper feed roller 143 side.

  As a transport unit for transporting the paper 142 fed from the paper feed unit on the lower side of the recording head 134, a transport belt 151 for electrostatically attracting and transporting the paper 142, and a paper feed unit A counter roller 152 for transporting the paper 142 fed through the guide 145 while sandwiching it between the transport belt 151 and the paper 142 fed substantially vertically upward are changed by approximately 90 ° and copied onto the transport belt 151. A conveyance guide 153 for adjusting the pressure and a tip pressure roller 155 urged toward the conveyance belt 151 by a pressing member 154. In addition, a charging roller 156 that is a charging unit for charging the surface of the conveyance belt 151 is provided.

  Here, the conveyance belt 151 is an endless belt, and is configured to be looped around the conveyance roller 157 and the tension roller 158 in the belt conveyance direction. The transport belt 151 has a thickness of about 40 μm, for example, a pure resin material that is not subjected to resistance control, for example, a surface layer that becomes a sheet adsorption surface formed of ETFE pure material, and resistance control by carbon using the same material as the surface layer. And a back layer (medium resistance layer, earth layer). In addition, a guide member 161 is disposed on the back side of the conveyance belt 151 so as to correspond to a printing area by the recording head 134. Further, as a paper discharge unit for discharging the paper 142 recorded by the recording head 134, a separation claw 171 for separating the paper 142 from the transport belt 151, a paper discharge roller 172, and a paper discharge roller 173 are provided. A paper discharge tray 103 is provided below the paper discharge roller 172. A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101. The double-sided paper feeding unit 181 takes in the paper 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. Further, a manual paper feed unit 182 is provided on the upper surface of the double-sided paper feed unit 181.

  In the ink jet recording apparatus configured as described above, the sheet 142 is separated and fed one by one from the sheet feeding unit, and the sheet 142 fed substantially vertically upward is guided by the guide 145, and includes the transport belt 151 and the counter roller 152. The leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °. At this time, the conveyance belt 151 is charged by the charging roller 156, and the sheet 142 is electrostatically attracted to the conveyance belt 151 and conveyed. Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped sheet 142 to record one line, and after the sheet 142 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 142 has reached the recording area, the recording operation is finished and the paper 142 is discharged onto the paper discharge tray 103. When a near-end remaining amount of ink in the sub tank 135 is detected, a required amount of ink is supplied to the sub tank 135 from the ink cartridge.

The pigment ink containing titanium dioxide as a colorant can obtain a white ink. In particular, the white ink can be suitably used for recording on recording media other than white, and when recording on a transparent recording medium such as a film or an OHP sheet, the white ink is used. It is possible to form. In addition, a white layer is formed by applying the white ink on a transparent recording medium, and an image is formed on the transparent layer using another color ink, thereby obtaining a clearer and higher quality image. Can be obtained. In this case, it is possible to first form the white layer on the transparent medium by applying the ink of the present invention, and form an image on the transparent medium using an ink such as black ink or color ink. It is also possible to obtain a clear image by applying the ink of the present invention after an image is formed on a transparent recording medium using an ink such as black ink or color ink.
There is no restriction | limiting in particular as said black ink and said color ink, According to the objective, it can select suitably, For example, the ink disclosed by Unexamined-Japanese-Patent No. 2009-280749, patent 530423 etc. is used. It is possible.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Production Example 1 of surface-treated titanium dioxide)
10 parts by mass of titanium dioxide (CR-50, manufactured by Ishihara Sangyo Co., Ltd.) dried at 110 ° C. for 2 days in a vacuum dryer is used as a hydrophilic phosphonic acid derivative, and the following exemplified compound (H-4) and hydrophobic As a functional phosphonic acid derivative, the following exemplified compound (L-4) is immersed in a 1 mmol / L ethanol solution for 1 hour and filtered under reduced pressure with a Teflon (registered trademark) filter having an average pore size of 0.1 μm to remove the solution. did.
Next, after the titanium dioxide on the Teflon (registered trademark) filter was washed with ethanol, it was dried in a vacuum dryer at 30 ° C. for 1 hour, returned to atmospheric pressure, and heated at 120 ° C. for 1 day. The surface-treated titanium dioxide was prepared.

<H-4>

<L-4>

(Production Examples 2 to 6 of surface-treated titanium dioxide)
In Production Example 1, surface-treated titanium dioxide of Production Examples 2 to 6 was produced in the same manner as Production Example 1 except that the phosphonic acid derivatives shown in Table 1 were used.

  Next, the hydrophobization degree was measured as follows for the surface-treated titanium dioxide of Production Examples 1 to 6 produced. The results are shown in Table 1.

<Hydrophobicity of titanium dioxide>
The hydrophobicity of titanium dioxide was measured using a powder wettability tester (WET-101P, manufactured by Reska Co., Ltd.).
First, a small amount of titanium dioxide (0.1 g) was suspended in 100 mL of water, and precipitation of titanium dioxide was detected with an optical detector at a liquid rotation speed of 200 rpm and a methanol inflow rate of 3 mL / min. The methanol volume concentration (%) during sedimentation was defined as the degree of hydrophobicity (%) of titanium dioxide.
In addition, the titanium dioxide surface-treated with a mixed phosphonic acid derivative measures the hydrophobicity of each of the hydrophilic phosphonic acid derivative and the hydrophobic phosphonic acid derivative in addition to the hydrophobicity of the mixed phosphonic acid derivative. did.

Details of the abbreviations in Table 1 are as follows.

<DF-PUPA; manufactured by Dojin Chemical Laboratory Co., Ltd.>

<11-PIUPA; manufactured by Dojin Chemical Laboratory Co., Ltd.>

(Preparation Example 1 of Titanium Dioxide Dispersion)
Production Example after 30.0 parts by mass of 3-methoxy-3-methyl-1-butanol and 1.0 part by mass of DISPERBYK-190 (manufactured by Big Chemie) as a dispersant were stirred and homogenized. 6 parts by mass of the surface-treated titanium dioxide of No. 1 was added, and stirring was continued for about 30 minutes so as not to become lumps. Furthermore, 10.0 parts by mass of ion-exchanged water was added and stirred, and then an ultrasonic wave was irradiated (600 W) at 50 ° C. for 8 hours to obtain a dispersion.

(Titanium dioxide dispersion preparation example 2)
Preparation Example 1 in the same manner as in Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide in Production Example 1 was replaced with the surface-treated titanium dioxide in Production Example 2 in Preparation Example 1 of the titanium dioxide dispersion. 2 titanium dioxide dispersion was prepared.

(Preparation Example 3 of Titanium Dioxide Dispersion)
Preparation Example 1 in the same manner as in Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide in Production Example 1 was replaced with the surface-treated titanium dioxide in Production Example 3 in Preparation Example 1 of the titanium dioxide dispersion. No. 3 titanium dioxide dispersion was prepared.

(Preparation Example 4 of Titanium Dioxide Dispersion)
Preparation Example 1 in the same manner as in Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide of Production Example 1 was replaced with the surface-treated titanium dioxide of Production Example 4 in Preparation Example 1 of the titanium dioxide dispersion. No. 4 titanium dioxide dispersion was prepared.

(Preparation Example 5 of Titanium Dioxide Dispersion)
Preparation Example 1 in the same manner as Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide of Production Example 1 was replaced with the surface-treated titanium dioxide of Production Example 5 in Preparation Example 1 of the titanium dioxide dispersion. No. 5 titanium dioxide dispersion was prepared.

(Preparation Example 6 of Titanium Dioxide Dispersion)
Preparation Example 1 in the same manner as in Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide in Production Example 1 was replaced with the surface-treated titanium dioxide in Production Example 6 in Preparation Example 1 of the titanium dioxide dispersion. No. 6 titanium dioxide dispersion was prepared.

(Preparation Example 7 for Titanium Dioxide Dispersion)
In Preparation Example 1 of the titanium dioxide dispersion, the same as Preparation Example 1 of the titanium dioxide dispersion except that the surface-treated titanium dioxide in Production Example 1 was replaced with titanium dioxide (CR-50, manufactured by Ishihara Sangyo Co., Ltd.). Thus, a titanium dioxide dispersion of Preparation Example 7 was produced.

(Examples 1-4 and Comparative Examples 1-3)
-Production of dilution liquid-
The following composition was mixed to prepare a diluted solution.
[Composition of dilution liquid]
・ Acrit WEM-321U ・ ・ ・ 12.3 parts by mass (acrylic urethane aqueous emulsion, manufactured by Taisei Kako Co., Ltd.)
-1,2-propanediol ... 11.7 parts by mass-2-ethyl-1,3-hexanediol-6.3 parts by mass-Polyfox PF-156A-2.8 parts by mass (anion Based fluorosurfactant, manufactured by OMNOVA)
・ Proxel LV (antiseptic / antifungal agent): 0.3 part by mass (1,2-Benzisothiazolin-3-one, manufactured by Avecia)
・ Triethanolamine: 0.2 parts by mass ・ Ion-exchanged water: 28.9 parts by mass

-Preparation of ink-
The dilute solution and the titanium dioxide dispersion shown in Table 2 were mixed in equal amounts in vials to prepare inks of Examples 1-4 and Comparative Examples 1-3.

  The phosphonic acid derivative on the titanium dioxide surface was identified for each of the inks produced as follows.

<Identification of phosphonic acid derivative>
First, the produced inks of Production Examples 1 to 6 were centrifuged (58,000 rpm, 10 minutes), washed, and the mixture was removed from the surface-treated titanium dioxide.
Next, after the hydrolysis treatment of clean surface-treated titanium oxide, analysis was performed under the following GC-MS analysis conditions, and by comparing the MS fraction library of the group consisting of each phosphonic acid derivative measured in advance, The phosphonic acid derivatives of surface treated titanium dioxide were identified.
As a result, the phosphonic acid derivatives used for the surface treatment as shown in Table 1 were detected for the inks of Production Examples 1 to 6.
The various hydrophilic or hydrophobic phosphonic acid derivatives identified were considered to have been liberated from titanium dioxide by hydrolysis, and it was confirmed that they were not simple mixtures.
[GC-MS analysis conditions]
-Centrifuge: Himax CS150GX (manufactured by Hitachi Koki Co., Ltd.) (rotation speed: 58,000 rpm)
GC-MS: GCMS-QP5000 (manufactured by Shimadzu Corporation)

  Next, various characteristics were evaluated as follows for each of the produced inks. The results are shown in Table 2.

<Sedimentation of titanium dioxide>
The sedimentation property of titanium dioxide in each ink was measured as follows using Turb Scan MA2000 (manufactured by Formal Action).
Each ink is subjected to ultrasonic dispersion treatment (100 W, 40 minutes) using an ultrasonic cleaner (US-3, manufactured by AS ONE Corporation) to be in a uniform state. 5.5 mL of ink was added.
Measurement was performed 30 minutes after the ink level in the glass cell was stabilized, and this time was set as the start of sedimentation evaluation. Then, it left still at 25 degreeC, it measured until 240 hours later, and the sedimentation property of titanium dioxide was confirmed by the deviation display on the basis of the sedimentation evaluation start. Confirmation of the sedimentation is performed by integrating the backscattered light intensity peaks accompanying sedimentation of titanium dioxide (20 mm below the sample tube to the liquid surface) at an average value (%) ) Performed at M and evaluated according to the following criteria.
[Evaluation criteria]
A: Average value (%) of the supernatant relative change amount of the backscattered light 240 hours after the start of the sedimentation evaluation is less than 5% B: Average percentage of the supernatant relative change amount of the backscattered light 240 hours after the start of the sedimentation evaluation Value (%) is 5% or more and less than 10% C: The average value (%) of the percentage of the relative change in the supernatant of the backscattered light 240 hours after the start of sedimentation evaluation is 10% or more

<Conformity of Formula (1)>
From the average value (%) M of the percentage relative change in the supernatant and the viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink, the formula (1): [(M × η _V )] / 10 <10 was evaluated according to the following criteria.
The liquid after removing the titanium dioxide from the ink was prepared as follows.
Centrifugation (58,000 rpm, 10 minutes) was carried out in the centrifuge to precipitate titanium dioxide, and a supernatant was obtained. About the obtained liquid, the viscosity in 25 degreeC was measured with the viscometer (The Toki Sangyo Co., Ltd. make, R type viscometer RE550L).
[Evaluation criteria]
A: The formula (1) is satisfied, and the left side of the formula (1) is less than 5.
B: The expression (1) is satisfied, and the left side of the expression (1) is 5 or more and less than 10.
C: The above formula (1) is not satisfied.

<Redispersibility of titanium dioxide>
30 mL of each ink prepared in a 50 mL vial was placed and allowed to stand at room temperature (25 ° C.) for 1 month, and the titanium dioxide redispersibility was evaluated according to the following criteria for the precipitated titanium dioxide.
[Evaluation criteria]
A: When the vial is shaken by hand for 10 seconds, the titanium dioxide settles and returns to the particle size before standing. B: An ultrasonic cleaner (US-3, When the ultrasonic irradiation treatment (100 W) is performed for 2 minutes by ASONE Co., Ltd., the titanium dioxide settles and returns to the particle size before standing. C: The precipitate in the ink aggregates and re-disperses even when stirred. Not

<Whiteness of printed image (image brightness)>
Using the ink jet printer shown in FIG. 3, each ink was filled in an ink container and set in the ink cartridge loading unit 104. Then, after adjusting the ink discharge amount so that the ink adhesion amount on the recording medium (OHP sheet) is 20 g / m ² , a solid image of 50 mm × 50 mm is printed on the OHP sheet to form a printed image. did. With the commercially available black paper laid under the printed OHP sheet, the printed portion was measured for lightness (L ^* ) using a spectrocolorimetric densitometer (X-Rite 938, manufactured by X-Rite), and the following Evaluation based on the criteria.
For reference, the L ^* value measured with an unprinted OHP sheet laid on black paper was 22.4.
[Evaluation criteria]
A: L ^* value is 75 or more B: L ^* value is 65 or more and less than 75 C: L ^* value is less than 65

From the results of Table 2, the inks of Examples 1 to 4 are superior to the inks of Comparative Examples 1 to 3 in that the titanium dioxide has excellent sedimentation properties, titanium dioxide redispersibility, and whiteness of the printed image. I found out that

Aspects of the present invention are as follows, for example.
<1> An ink containing titanium dioxide and water,
An average value (%) M of the percentage of the relative change in the supernatant after 240 hours of standing at 25 ° C. in the integration of the backscattered light intensity peak accompanying the precipitation of the titanium dioxide in the ink;
The viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink satisfies the following formula: [(M × η _V )] / 10 <10. Ink.
<2> The ink according to <1>, wherein the titanium dioxide is titanium dioxide having a group composed of a phosphonic acid derivative on the surface.
<3> The ink according to <2>, wherein the titanium dioxide is titanium dioxide having on the surface at least one of a group composed of a hydrophilic phosphonic acid derivative and a group composed of a hydrophobic phosphonic acid derivative.
<4> The ink according to <3>, wherein the titanium dioxide is titanium dioxide having both a group composed of a hydrophilic phosphonic acid derivative and a group composed of a hydrophobic phosphonic acid derivative on the surface.
<5> The group consisting of the hydrophilic phosphonic acid derivative is at least one selected from groups represented by the following structural formulas (HH-1) to (HH-4): <3> to <4 > The ink according to any one of the above.
<HH-1>
<HH-2>
<HH-3>
<HH-4>
<6> The above <3> to <4, wherein the group consisting of the hydrophobic phosphonic acid derivative is at least one selected from the groups represented by the following structural formulas (LL-1) to (LL-4) > The ink according to any one of the above.
<LL-1>
<LL-2>
<LL-3>
<LL-4>
<7> Hydrophobization degree HH1 of titanium dioxide having a group consisting of the hydrophilic phosphonic acid derivative and a group consisting of a hydrophobic phosphonic acid derivative on the surface;
Hydrophobic degree HH2 of titanium dioxide having a group consisting of the hydrophilic phosphonic acid derivative on the surface and not having a group consisting of the hydrophobic phosphonic acid derivative on the surface;
The degree of hydrophobicity HH3 of titanium dioxide having a group composed of the hydrophobic phosphonic acid derivative on the surface and not having a group composed of the hydrophilic phosphonic acid derivative on the surface is expressed by the following formula: HH2 <HH1 <HH3 The ink according to any one of <3> to <6>, wherein
<8> The ink according to any one of <1> to <7>, wherein the degree of hydrophobicity of the titanium dioxide is 5% or more and 45% or less.
<9> The ink according to <8>, wherein the titanium dioxide has a hydrophobicity of 15% or more and 40% or less.
<10> The ink according to any one of <1> to <9>, further including a water-soluble organic solvent.
<11> The ink according to <1>, wherein the titanium dioxide is titanium dioxide surface-treated with a phosphonic acid derivative.
<12> In the above <11>, wherein the titanium dioxide is a titanium dioxide having a group consisting of a phosphonic acid derivative having one organic phosphonic acid group in the molecule by surface treatment with a phosphonic acid derivative and hydrolysis. The ink described.
<13> The ink according to any one of <11> to <12>, wherein the phosphonic acid derivative is at least one of a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative.
<14> The ink according to <13>, wherein the phosphonic acid derivative is both a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative.
<15> Any of <13> to <14>, wherein the hydrophilic phosphonic acid derivative is at least one selected from compounds represented by the following structural formulas (H-1) to (H-4): It is the ink described in the above.
<H-1>
<H-2>
<H-3>
<H-4>
<16> Any of <13> to <14>, wherein the hydrophobic phosphonic acid derivative is at least one selected from compounds represented by the following structural formulas (L-1) to (L-4): It is the ink described in the above.
<L-1>
<L-2>
<L-3>
<L-4>
<17> A dispersion for ink containing the titanium dioxide according to any one of <1> to <16>, water, and a water-soluble organic solvent,
The water-soluble organic solvent is 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy- An ink dispersion liquid comprising at least one selected from 1-butanol and 3-methoxy-3-methyl-1-butanol.
<18> An ink storage container, wherein the ink according to any one of <1> to <16> is stored in a container.
<19> An inkjet discharge device comprising the ink container according to <18>.
<20> a step of surface-treating titanium dioxide with a phosphonic acid derivative;
Surface-treated titanium dioxide was converted into 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy Dispersing in a dispersion medium containing at least one water-soluble organic solvent selected from -1-butanol and 3-methoxy-3-methyl-1-butanol and water;
A method for producing an ink, comprising:
<21> The method for producing an ink according to <20>, wherein the phosphonic acid derivative has one phosphoric acid group.
<22> The method for producing an ink according to any one of <20> to <21>, wherein the surface treatment includes heating at 120 ° C. to 150 ° C. for 1 hour to 2 days.

The ink according to any one of <1> to <16>, the ink dispersion according to <17>, and the method for producing the ink according to <20> to <22> The problem is to solve the problem and achieve the following objectives. That is, the ink and the method for producing the ink provide an ink, an ink dispersion, and a method for producing the ink, in which titanium dioxide as a colorant hardly settles and can be easily redispersed even if it settles. With the goal.
The ink container described in <18> and the ink jet discharge apparatus described in <19> solve the above-described problems and achieve the following object. That is, the ink container and the ink jet discharge device provide an ink container and an ink jet discharge device including an ink that can be easily redispersed even if the titanium dioxide, which is a colorant, does not easily settle. The purpose is to do.

JP 2011-225867 A

134 Recording Head 200 Ink Container 241 Ink Bag 242 Ink Inlet 243 Ink Outlet 244 Cartridge Case

Claims (10)

An ink containing titanium dioxide and water,
An average value (%) M of the percentage of the relative change in the supernatant after 240 hours of standing at 25 ° C. in the integration of the backscattered light intensity peak accompanying the precipitation of the titanium dioxide in the ink;
The viscosity η _V (mPa · s) at 25 ° C. of the liquid after removing the titanium dioxide from the ink satisfies the following formula: [(M × η _V )] / 10 <10. ink.   The ink according to claim 1, wherein the titanium dioxide is titanium dioxide having a group composed of a phosphonic acid derivative on the surface.   The ink according to claim 2, wherein the titanium dioxide is titanium dioxide having at least one of a group consisting of a hydrophilic phosphonic acid derivative and a group consisting of a hydrophobic phosphonic acid derivative on the surface. The ink according to claim 3, wherein the group consisting of the hydrophilic phosphonic acid derivative is at least one selected from groups represented by the following structural formulas (HH-1) to (HH-4).
<HH-1>
<HH-2>
<HH-3>
<HH-4>
The ink according to claim 3, wherein the group comprising the hydrophobic phosphonic acid derivative is at least one selected from groups represented by the following structural formulas (LL-1) to (LL-4).
<LL-1>
<LL-2>
<LL-3>
<LL-4>
  The ink according to claim 3, wherein the titanium dioxide is titanium dioxide surface-treated with at least one of a hydrophilic phosphonic acid derivative and a hydrophobic phosphonic acid derivative. The ink according to claim 6, wherein the hydrophilic phosphonic acid derivative is at least one selected from compounds represented by the following structural formulas (H-1) to (H-4).
<H-1>
<H-2>
<H-3>
<H-4>
The ink according to claim 6, wherein the hydrophobic phosphonic acid derivative is at least one selected from compounds represented by the following structural formulas (L-1) to (L-4).
<L-1>
<L-2>
<L-3>
<L-4>
  An ink storage container comprising the ink according to any one of claims 1 to 8 stored in a container. Surface treatment of titanium dioxide with a phosphonic acid derivative;
Surface-treated titanium dioxide was converted into 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 3-methoxy Dispersing in a dispersion medium containing at least one water-soluble organic solvent selected from -1-butanol and 3-methoxy-3-methyl-1-butanol and water;
A method for producing an ink, comprising: