JP2013133356A - Aqueous pigment ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous pigment ink composition high in drying proofness enough to be usable for writing utensils, recorders, printers, etc., and causing no crystal deposition.SOLUTION: The aqueous pigment ink composition is characterized by comprising: a pigment; a styrene-acrylic acid resin and/or styrene-maleic acid resin; pentaerythritol; a fluorine-containing surfactant; and water. In this ink composition, the contents of the pigment, the styrene-acrylic acid resin and/or styrene-maleic acid resin, the pentaerythritol, and the fluorine-containing surfactant are, based on the whole amount of ink composition, 0.1-12 mass%, 1-10 mass%, 1-4 mass%, and 0.005-0.05 mass%, respectively.

Description

  The present invention relates to an aqueous pigment ink composition having excellent drying resistance that can be used for writing instruments, recorders, printers, and the like and that does not cause unintended crystal precipitation.

In writing instruments using conventional water-based inks, if the cap is removed from the writing instrument body and the pen tip is exposed to the atmosphere for a long time, the ink dries and the solid matter clogs the ink flow path. In some cases, the ink in the ink storage tank dries out and writing becomes impossible.
For this reason, in aqueous dye inks, water-based dye ink compositions are known in which a water-soluble organic solvent such as glycols or glycerin or urea is added as an evaporation inhibitor to prevent drying by slowing the evaporation rate of water. Yes.

  In contrast, in a water-based pigment ink composition characterized in that show-through and bleeding do not occur when drawn on paper, if a large amount of a water-soluble organic solvent such as glycols or glycerin is added, drawing and When writing, show-through and bleeding occurred, and the feature of the corner was ruined.

As a countermeasure, a method of adding a substance that exhibits an effect of suppressing water evaporation (masking effect) by slightly depositing crystals on the water surface (gas-liquid interface) where water evaporation is intense can be considered. Initially, applications have been filed by various persons skilled in the art.
For example, 1) an aqueous ink composition comprising a colorant, water, and one or a mixture of two or more selected from pentaerythritol, trimethylolethane, or trimethylolpropane (see, for example, Patent Document 1), 2 ) Aqueous ink composition comprising a colorant, water and paraxylene glycol (see, for example, Patent Document 2 by the present applicant), 3) From the group consisting of a colorant, water, hydantoin and a hydantoin derivative A water-based ink composition containing at least one or more selected substances is known (for example, see Patent Document 3), and any of these substances does not have high solubility in water.

In addition, in order to enhance the effect of suppressing water evaporation (masking effect), the applicant of the present application has proposed a blend in which another substance is added in addition to these so-called evaporation inhibitors.
For example, 4) an aqueous pigment ink composition comprising an alkylene oxide adduct of polyglycerin, a pigment, a dispersant, and water in addition to pentaerythritol (see, for example, Patent Document 4), 5) paraxylylene A water-based ink composition (see, for example, Patent Document 5) characterized by containing a polymer having a phenyl group in the molecule in addition to glycol is proposed.

  Although the water-based ink composition to which an appropriate amount of these evaporation inhibitors is added is excellent in drying resistance itself, it is extremely difficult to control the crystal precipitation at the gas-liquid interface described above, and the control range, for example, is used. If the temperature falls outside the assumed temperature, the precipitated crystals grow greatly, the surface area near the gas-liquid interface increases, and on the other hand, the evaporation rate of water increases, or the ink grows into the grown crystals and the drawn lines become thick. In some cases, it happened to be obscured or look like wrinkles.

Therefore, in order to prevent the above-described crystal precipitation, the applicants of the present application have searched for a substance having a high affinity with water and a high masking effect, and have proposed an ink composition to which these substances are added.
For example, in order to provide 6) a water-based ink excellent in drying resistance of the ink and excellent in suppressing the precipitation of huge crystals at the nib, it contains a colorant, water and xylitol. Ink compositions (see, for example, Patent Document 6), 7) In order to provide a water-based ink composition that not only accelerates drying of writing lines but also can exhibit a drying-inhibiting effect at the nib portion, A water-based ink composition comprising at least water and 1,4-cyclohexanedimethanol, optionally further containing 5 to 20 masses of at least one alcohol selected from ethyl alcohol, n-propyl alcohol and isopropyl alcohol. % Water-based ink composition (for example, see Patent Document 7) is known,
Since these substances are solid at room temperature, they exhibit a certain masking effect, but they have a high affinity with water, and even if they cause corner precipitation at the gas-liquid interface, they are immediately re-dissolved, resulting in a long time. It has been difficult to exert a masking effect over a long period of time.

As another approach to these problems, etc., the applicant of the present application considers sealing the gas-liquid interface of the pen tip when the cap is attached to prevent the precipitation of visible crystals, and the ink crystals from the pen core of the marking pen. In order to prevent precipitation (flower bloom) by the structure of the pen core and cap, the main body shaft having an ink storage section for storing ink and the front end side of the main body shaft to eject ink from the ink storage section And a cap that is detachably mounted on the front end side of the main body shaft so as to cover a front protruding portion of the pen core, and the pen core includes a front end portion and a rear end portion. A substrate portion that exposes the ink from the rear end side to the front end side and an outer skin portion that covers the outer periphery of the substrate portion and prevents the ink from leaching to the outer peripheral surface, front end Is mounted with a liquid absorbing member that covers the front end exposed portion of the substrate portion of the pen core and absorbs ink, and the substrate portion of the pen core is formed by the outer skin portion and the liquid absorbing member of the pen core. A marking pen (see, for example, Patent Document 8) is proposed, which prevents contact between the ink inside and the air in the cap.
Here, the above-mentioned Patent Document 8 does not suppress the visible crystal precipitation itself, but physically suppresses the crystal precipitation by minimizing the exposure of the gas-liquid interface. However, this is not a solution from the above point, and there is a problem that the use of special members causes an increase in product cost.

Japanese Patent Laid-Open No. 5-271601 (Claims, Embodiments, etc.) Japanese Patent Laid-Open No. 9-12957 (claims, embodiments, etc.) JP 2001-152067 A (Claims, embodiments, etc.) JP-A-9-87566 (Claims, Embodiments, etc.) JP 2000-95990 A (Claims, embodiments, etc.) JP 2002-173618 A (Claims, embodiments, etc.) JP 2000-319570 A (Claims, embodiments, etc.) Japanese Patent Laid-Open No. 2000-280685 (Claims, Embodiments, etc.)

  The present invention is to solve this problem in view of the progress of the above-mentioned technological development and its problems, current situation, etc., and the effect of suppressing water evaporation (masking effect) is exhibited without problems, such as a pen tip It is an object of the present invention to provide an aqueous ink composition that does not cause visible crystal precipitation at the gas-liquid interface.

  As a result of intensive studies in view of the above-described conventional problems, the present inventor has demonstrated an effect of suppressing water evaporation (masking effect) as yet another approach to the above-described problems. Then, when a substance that is supposed to grow, the substance that inhibits it is mixed, and the growth of large visible crystals is suppressed, and the effect of suppressing water evaporation without any problem (masking) The inventors have found that the above object can be achieved by using a specific surfactant in consideration of exerting the effect), and have completed the present invention.

That is, the present invention resides in the following (1) to (6).
(1) An aqueous pigment ink composition comprising at least a pigment, a styrene acrylic acid resin and / or a styrene maleic acid resin, pentaerythritol, and a surfactant containing fluorine.
(2) The content of the pigment is 0.1 to 12% by mass, the content of the styrene acrylic acid resin and / or the styrene maleic acid resin is 1.0 to 10% by mass with respect to the total amount of the ink composition, The aqueous pigment ink composition as described in (1) above, wherein the content of pentaerythritol is 1 to 4% by mass, and the content of the surfactant containing fluorine is 0.005 to 0.05% by mass. .
(3) The aqueous pigment ink composition as described in (1) or (2) above, wherein the pigment is a chromatic organic pigment.
(4) The aqueous pigment ink composition according to any one of (1) and (2), wherein the pigment is carbon black.
(5) The aqueous pigment ink composition as described in any one of (1) and (2) above, wherein the pigment is a colored emulsion pigment.
(6) The aqueous pigment ink composition as described in any one of (1) to (5) above, wherein the pH of the ink composition is 7.5 to 10.0.

  ADVANTAGE OF THE INVENTION According to this invention, the water-based pigment ink composition excellent in the effect (masking effect) which suppresses the crystal precipitation visible at the gas-liquid interface, such as a nib, and suppresses evaporation of water is provided.

Hereinafter, embodiments of the present invention will be described in detail.
The aqueous pigment ink composition of the present invention is characterized by containing at least a pigment, a styrene acrylic resin and / or a styrene maleic resin, pentaerythritol, and a surfactant containing fluorine. .

Examples of the pigment used in the present invention include conventionally known inorganic and organic pigments for aqueous pigment ink compositions, resin particle pigments containing pigments, colored emulsion pigments in which a fluorescent dye or the like is solid-solved in a resin matrix, white type Plastic pigments, pigments having silica or mica as a base material and multilayer coating of iron oxide, titanium oxide or the like on the surface layer can be used. In addition, you may contain dye as a complementary color as needed.
More specifically, the pigment is a chromatic organic pigment, carbon black, colored emulsion pigment, and carbon black, azo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene pigments produced by various methods. Perinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and the like.
These pigments can be used alone or in admixture of two or more.

  The content of these pigments can be appropriately increased or decreased according to the drawn line density of the ink, but is 0.1 to 25% by mass (hereinafter simply referred to as “%”) with respect to the total amount of the ink composition. More preferably, it is desirable to set it as about 0.1-12 mass%.

The styrene acrylic acid resin and styrene maleic acid resin used in the present invention are used as fixing resins.
Styrene acrylic acid resins that can be used include Jonkrill 52J, Jonkrill 57J, Jonkrill 60J, Jonkrill 61J, Jonkrill 62J (above, BASF Japan Ltd.), RS-1191, VS-1047, YS-1274. (The above, manufactured by Seiko PMC Co., Ltd.) Also, as styrene maleic resin, Alastar 700, Alastar 703S (above, manufactured by Arakawa Chemical Co., Ltd.), SMA-1440, SMA-2625, SMA-17352 (above, converted into crude oil from river) Etc.).
Preferably, it is desirable to use a styrene acrylate resin from the viewpoints of handling at the time of manufacture, stability with time of the ink composition, and dissolution stability of pentaerythritol.

The total content of these styrene acrylic acid resins and / or styrene maleic acid resins is 0.5 to 20%, preferably 1 to 10% in terms of solid concentration with respect to the total amount of the ink composition. desirable.
If the content is less than 0.5%, the ink composition is unstable over time, and the dissolved state of pentaerythritol becomes unstable, which is not preferable. On the other hand, when the content exceeds 20%, The viscosity of the ink composition increases explosively and pentaerythritol cannot be precipitated, which is not preferable.

Pentaerythritol [C (CH ₂ OH) ₄ ] used in the present invention is used as a desiccant and does not cause a decrease in ink performance even when blended in an aqueous pigment ink composition. .
The content of pentaerythritol is 0.3 to 5%, preferably 1 to 4%, based on the total amount of the ink composition.
If the content of this content is less than 0.3%, the effect as a desiccant is low, which is not preferable. On the other hand, if it exceeds 5%, the viscosity as an aqueous pigment ink becomes too high, or is always Precipitation of crystals occurs and it becomes unsightly, and a problem arises in the storage stability of the ink.

The surfactant containing fluorine used in the present invention inhibits the evaporation of water when the above-mentioned pentaerythritol exhibits an effect of suppressing the evaporation of water (masking effect). It is incorporated in order to suppress the crystal growth and to exhibit the effect (masking effect) of suppressing the evaporation of water without any problem.
Examples of the fluorine-containing surfactant that can be used include those containing a high molecular weight polymer such as a perfluoroalkenyl ethylene oxide adduct, a perfluoroalkyl group adduct, and a perfluorobutanesulfonic acid group adduct.
Preferably, 1) a perfluoroalkenyl structure branched with a double bond in the molecule, for example, a hexafluoropropene oligomer [(CF ₃ ) ₂ CF] ₂ C═C (F) CF ₃ ], etc. ) Neos's aftergent 100, 100C, 110, 140A, 150, 150CH, AK, 501, 250, 251, 222F, 300, 310, 400SW] 2) Those having a perfluorobutanesulfonic acid group (FC-4430, FC-4432 manufactured by Sumitomo 3M Limited) and the like.

The content of these fluorine-containing surfactants is 0.001 to 0.1%, preferably 0.005 to 0.05% in terms of solid concentration with respect to the total amount of the ink composition. .
If the content of this content is less than 0.001%, the effect of inhibiting visible crystal precipitation is not exhibited at all, and the wettability to the non-absorbing surface of the ink is lowered, which is not preferable. On the other hand, if it exceeds 0.1%, the wettability to the surface of the pentaerythritol crystal is also increased, and on the contrary, enormous crystal precipitation is promoted, which is not preferable.

  In the aqueous pigment ink composition of the present invention, preferably, ammonia or amino is used as a pH adjuster from the viewpoint of improving the dissolution stability of the acrylic resin of the ink composition, that is, the dispersion stability of the pigment of the ink composition. It is preferable that the pH of the ink composition is 7.5 to 10.0 by including methylpropanol, triethanolamine, or the like.

  The aqueous pigment ink composition of the present invention is prepared with water (purified water, distilled water, ion-exchanged water, pure water, etc.) as the balance in addition to the above-mentioned components. Arbitrary components such as a foaming agent and a thickening agent can be appropriately contained as long as the effects of the present invention are not impaired.

In the production of the aqueous pigment ink composition of the present invention, the above-mentioned components are mixed and pulverized by a known disperser such as a ball mill, a roll mill, a sand mill, a flow mill, a dyno mill, an attritor and the like with the contents in the above ranges. The intermediate obtained by stirring and mixing or mixing and pulverizing the target aqueous pigment ink composition can be easily obtained by removing coarse particles and dust by a method such as filtration and centrifugal sedimentation, if necessary.
The aqueous pigment ink composition of the present invention can be suitably used for writing instruments such as marking pens and sign pens, recorders, printers and the like.

The water-based pigment ink composition of the present invention configured as described above is excellent in the effect (masking effect) of suppressing crystal precipitation visible at the gas-liquid interface such as a nib and suppressing water evaporation. It will be a thing. The detailed mechanism of action is presumed as follows.
Pentaerythritol has a plurality of hydroxyl groups, and hydrogen bonding with water molecules provides some degree of water evaporation suppression effect from aqueous ink. As a result, the solubility in water decreases without forming hydrogen bonds with water molecules and precipitates as large crystals, and ink is sucked up on the surface of the crystals, causing the precipitation of larger crystals and more intense ink. It may cause evaporation of the solvent (water), and by using a surfactant containing an appropriate amount of fluorine, crystals of an appropriate size are deposited for the first time, and styrene acrylate resin and / or Crystals that are visible at the gas-liquid interface of the nib or the like synergistically (by a synergistic action) because the styrene-maleic acid resin film is applied. Suppressing out, and, masking or the like of the gas-liquid interface is more conducive, evaporation of water from the aqueous ink of the pen tip, it is speculated that dramatically suppress drying.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in full detail, this invention is not restrict | limited by the following Example etc.

[Examples 1 to 12 and Comparative Examples 1 to 5]
Each aqueous pigment ink composition was prepared by mixing and dispersing with a homomixer or a disperer according to the formulation shown in Table 1 below.
For each of the aqueous pigment ink compositions of Examples 1 to 12 and Comparative Examples 1 to 5 obtained above, (1) pH of the ink composition, (2) non-drying property A (initial), ( 3) Non-drying property B (after 3 months at 50 ° C.), (4) Crystal precipitation property, (5) Line drawing drying property, and (6) Adhesion property to non-absorbing surface were evaluated.
These results are shown in Tables 1 and 2 below.

〔Test method〕
(1) pH of ink composition
Each aqueous pigment ink composition (25 ° C.) was measured by “HORIBA PH / 10N METER F-24” manufactured by HORIBA, Ltd.

(2) Non-drying property A (initially left for 2 hours)
A PM-120T pen body manufactured by Mitsubishi Pencil Co., Ltd. is filled with each aqueous pigment ink composition, and the cap is removed in an environment with an air temperature of 25 ° C. and a humidity of 65% and left sideways. The spiral was drawn 8 times, the state of the drawn line was observed, and evaluated according to the following evaluation criteria (n = 10). In addition, it wrote with both the very fine and the fine pen lead, and the thing of bad evaluation was described.
Evaluation criteria:
A: Can be completely written from the first writing.
○: Can be completely written from the second round of the spiral.
○ ': Can be completely written from the second five-fold spiral.
(Triangle | delta): It can write down completely from the 5th helix of the 3rd time.
▲: Can be completely written from the fourth quintuple spiral.
X: Cannot be written completely up to the fourth quintuple spiral.

(3) Non-drying B (after 50 months at 50 ° C)
A PM-120T pen manufactured by Mitsubishi Pencil Co., Ltd. is filled with each aqueous pigment ink composition and stored in an environment of 50 ° C. for 3 months, and then returned to room temperature (25 ° C.), as in (2) above. The evaluation criteria were evaluated and evaluated (n = 10).

(4) Crystal Precipitation The PM-120T pen body manufactured by Mitsubishi Pencil Co., Ltd. was filled with each aqueous pigment ink composition and stored in an environment of 0 ° C. for 1 month. Observe the situation. Thereafter, a spiral of 5 mm and a width of 15 mm was drawn once, the state of the drawn line was observed, and evaluated according to the following evaluation criteria (n = 10). In addition, it observed with both a very fine and a thin pen lead, and the thing of bad evaluation was described.
Evaluation criteria:
A: Crystal precipitation is not observed at all.
○: Crystallization is observed when observed closely, but is very slight and inconspicuous.
Δ: Crystallization is observed by ordinary observation, but there is no effect on the writing line.
▲: Crystal precipitation is observed by ordinary observation, and the effect of this crystal is seen on the handwritten line.
X: Precipitation of large crystals was observed by ordinary observation, and the writing line was significantly thicker than usual.

(5) Drawn line dryness Pencil body of PM-120T manufactured by Mitsubishi Pencil Co., Ltd. is filled with each aqueous pigment ink composition, and it is confirmed that the ink has reached the tip of the pen. Under an environment where the temperature is 25 ° C. and the humidity is 65%. A spiral with a width of 15 mm was drawn once on a PET film, and the state of the drawn line that was scratched with a cotton swab at 5 second intervals was continuously observed, and the time during which the drawn line was not stretched was measured and evaluated according to the following evaluation criteria (n = 10 ). In addition, it observed with both a very fine and a thin pen lead, and the thing of bad evaluation was described.
Evaluation criteria:
(Double-circle): There is no extending | stretching of a drawn line by abrasion for the first 5 seconds.
○: Stretching of drawn lines was observed only during the first 5 seconds of rubbing.
(Triangle | delta): Stretching of a drawn line was no longer seen by 15 seconds of rubbing.
▲: Stretching of drawn lines was not observed until 30 seconds after rubbing.
X: It took 1 minute or more before drawing line drawing was not observed.

(6) Adhesiveness to non-absorptive surface A PM-120T pen manufactured by Mitsubishi Pencil Co., Ltd. is filled with each aqueous pigment ink composition, and the spiral is 5 layers and 15 mm wide in an environment of air temperature 25 ° C. and humidity 65%. Was drawn 8 times on a PET film, dried, rubbed in the same direction 10 times with the fingerprint of the fingertip, and the drawn line after rubbing was evaluated according to the following evaluation criteria (n = 10). In addition, it wrote with both the very fine and the fine pen lead, and the thing of bad evaluation was described.
Evaluation criteria:
A: Same as before rubbing (not disappeared at all).
○: Up to 25% of the drawn lines are erased.
Δ: Up to 50% of the drawn lines are erased.
▲: Up to 75% of drawn lines are erased.
X: All drawn lines are erased.

* 1 to * 9 in Table 1 and Table 2 are as follows.
* 1: Mitsubishi Chemical Co., Ltd. * 2: Fuji Pigment Co., Ltd. * 3: Dainichi Seika Kogyo Co., Ltd. * 4: Pink, NKW3207E, Nippon Fluorescent Co., Ltd. (nonvolatile content: 37.0%)
* 5: Jonkrill 61J, manufactured by BASF (non-volatile content: 30.5%)
* 6: Alaster 703S, manufactured by Arakawa Chemical Industries, Ltd. (non-volatile content 30%)
* 7: Footgent 251, manufactured by Neos * 8: Ketone resin K-90, manufactured by Arakawa Chemical Industries * 9: Leocoal TD-50, manufactured by Lion

As is clear from the results in Table 1 above, Examples 1 to 12 of the present invention have no crystal precipitation and non-drying properties (initial, 50 ° C. · 3) compared to Comparative Examples 1 to 5 which are outside the scope of the present invention. After a month), it was found that the drawn line dryness and the non-absorbing surface were excellent.
On the other hand, when a comparative example is seen, when Comparative Example 1 contains conventional paraxylylene glycol, Comparative Example 2 contains a nonionic surfactant that falls outside the scope of the present invention, Comparative Example 3 contains no surfactant, Comparative Example 4 contains a resin that is outside the scope of the present invention, and Comparative Example 5 contains a conventional ketone resin. It turned out that the effect of invention cannot be exhibited.

  The aqueous pigment ink composition can be suitably used for writing instruments such as marking pens and sign pens, recorders, and printers.

Claims (6)

  A water-based pigment ink composition comprising at least a pigment, a styrene acrylic resin and / or a styrene maleic resin, pentaerythritol, a surfactant containing fluorine, and water.   The content of the pigment is 0.1 to 12% by mass with respect to the total amount of the ink composition, the content of the styrene acrylic acid resin and / or styrene maleic acid resin is 1 to 10% by mass, and the content of the pentaerythritol The aqueous pigment ink composition according to claim 1, wherein the content of the surfactant containing fluorine is 0.005 to 0.05% by mass.   The aqueous pigment ink composition according to claim 1, wherein the pigment is a chromatic organic pigment.   The aqueous pigment ink composition according to claim 1, wherein the pigment is carbon black.   The aqueous pigment ink composition according to claim 1, wherein the pigment is a colored emulsion.   The aqueous pigment ink composition according to any one of claims 1 to 5, wherein the pH of the ink composition is 7.5 to 10.0.