JP2018002860A - Aqueous ink composition for writing instruments - Google Patents

Abstract

To provide a water-based ink composition for a writing instrument, which can obtain desired color strength and hue and is excellent in scratch resistance of a drawn line written on paper.
A microsphere having water, a matrix composed of a resin, and a water-insoluble dye is contained, and the water-insoluble dye is present inside the matrix more densely than the surface of the matrix. A water-based ink composition for a writing instrument, wherein the 10% strength of the microsphere by a micro compression test is 30 MPa or less.
[Selection] Figure 1

Description

  The present invention relates to a water-based ink composition for a writing instrument.

  Dyes and pigments are known as coloring components of water-based inks used for writing instruments such as water-based sign pens and water-based ballpoint pens.

  The ink using a dye has a defect that the written character / drawing line becomes unclear because the dye / water is so soluble that the character / drawing line is blotted or disappeared with sweat or water, and so-called water resistance is poor. In addition, since the dye itself is inferior in light resistance, there is a problem that characters and drawn lines are deteriorated over a long period of time. On the other hand, inks using pigments have no problem with respect to water resistance or light resistance. However, since the material, size, specific gravity, and the like differ depending on the type of pigment, there is a problem that different dispersion treatments are required for each pigment. In particular, when pigments having different hues are mixed and toned in order to obtain a desired hue, the stability of the ink is often impaired due to the difference in properties. In order to solve such a problem, various inks in which a resin is colored using a dye or a pigment or microencapsulated have been proposed.

  Patent Document 1 discloses a water-based ink composition characterized by using colored polyacrylic acid derivative microspheres having a particle size of 10 μm or less as a colorant. In Patent Document 1, this coloring is performed by dyeing microspheres of a polyacrylic acid derivative with an acid dye or a basic dye.

  Patent Document 2 discloses an ink for a writing instrument, which is an aqueous dispersion in which a polyester particle containing an ionic group in a range of 20 to 1000 eq / ton colored with a dye or pigment is used as a dispersoid. ing. In Patent Document 2, this coloring is performed by a high temperature disperse dyeing method.

  In Patent Document 3, an aqueous dispersion of colored resin fine particles for water-based ink is disclosed. Here, this dispersion is prepared by emulsion polymerization of a vinyl monomer having an acidic functional group in which a water-soluble basic dye is dissolved in the presence of a polymerizable surfactant.

  Patent Document 4 discloses a water-based marking pen ink for a writing board having a composition containing a colorant, a resin, an erasability imparting agent, and water. In this water-based marking pen ink for writing board, this colorant is a microcapsule encapsulating a colorant formed by dispersing or dissolving a dye or a dye selected from an oil-soluble dye, a disperse dye and a pigment in an oily medium, The microcapsules are dispersed in an aqueous medium. Patent Document 4 discloses that methyl ethyl ketone is used as an oil medium contained in microcapsules.

Japanese Patent Laid-Open No. Sho 62-225578 JP 7-34023 A JP-A-10-259337 JP-A-10-292146

  In the application of ink for writing instruments, a hiding power (color power) by color may be required. However, the inks described in Patent Documents 1 and 3 cannot achieve a desired color strength, and / or water-soluble dyes in or on the surface of particles ooze out into an aqueous medium such as water, thereby Robustness may be partially impaired.

  Moreover, when it is set as the aspect which dyes a dye to particle | grains like patent document 1 and 2, since a dye cannot be made to contain abundantly in particle | grains, desired color strength may not be implement | achieved.

  Further, when the water-based marking pen ink for a writing board described in Patent Document 4 is used particularly for writing on paper, the desired scratch resistance of drawn lines may not be obtained.

  Therefore, there is a need to provide a water-based ink composition for a writing instrument that can obtain a desired color strength and is excellent in scratch resistance of drawn lines written on paper.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows:
<1> containing microspheres having water, a matrix composed of a polymer, and a water-insoluble dye;
The water-insoluble dye is present more densely inside the matrix than the surface of the matrix, and the 10% strength of the microsphere according to a micro compression test is 30 MPa or less.
A water-based ink composition for writing instruments.
<2> The aqueous ink composition for a writing instrument according to <1>, wherein the microsphere has a circularity coefficient measured by an image analysis method of 0.6 to 1.0.
<3> The water-based ink composition for a writing instrument according to <1> or <2>, wherein the content of the water-insoluble dye in the microsphere is 10% by mass to 45% by mass.
<4> The writing instrument according to any one of <1> to <3>, wherein the microsphere has an average particle size of 0.3 to 3.0 μm when measured by a laser diffraction method. A water-based ink composition.
<5> The microsphere according to any one of the above items <1> to <4>, containing at least two types,
One matrix of the microspheres and another matrix of the microspheres are made of the same polymer, and one water-insoluble dye of the microspheres, and the microspheres Different from other kinds of water insoluble dyes,
A water-based ink composition for writing instruments.
<6> It has at least an ink storage unit, a writing unit, and a holding unit,
The water-based ink composition for a writing instrument according to any one of the above items <1> to <5> is stored in the ink storage unit.
Writing instrument.

  ADVANTAGE OF THE INVENTION According to this invention, the desired color strength can be obtained and the water-based ink composition for writing instruments which was excellent in the abrasion resistance of the drawn line written on paper can be provided.

FIG. 1 is a schematic cross-sectional view of a microsphere in the aqueous ink composition for a writing instrument of the present invention.

<< Water-based ink composition for writing instruments >>
The aqueous ink composition for a writing instrument of the present invention contains water and microspheres. The microsphere has a matrix composed of a polymer and a water-insoluble dye. This water-insoluble dye is present more densely inside the matrix than on the surface of the matrix. The 10% strength of the microsphere measured by a micro compression test is 30 MPa or more.

  The inventors of the present invention have the above-described constitution of a water-based ink composition for a writing instrument, whereby a desired color strength can be obtained, and when used for writing on paper, the drawn line has excellent scratch resistance. I found out that Although not wishing to be bound by theory, as the above 10% strength decreases, the microspheres deform when written on paper and tend to sink between the fibers on the surface of the paper, and as a result, It is considered that the scratch resistance is improved.

  The inventors have further found that the 10% strength is preferably 5 MPa or more from the viewpoint of stabilizing the outflow of ink. Although not wishing to be bound by theory, it is considered that the shape stability of the microspheres improves as the 10% strength increases, and as a result, the ink can flow out stably.

  That is, it is considered that good initial writing properties and good scratch resistance of drawn lines can be harmonized when the 10% strength is 5 to 30 MPa.

  The aqueous ink composition for a writing instrument of the present invention may contain at least two kinds of microspheres. In this case, it is preferable that one kind of matrix of the microspheres and the other kind of matrix of the microspheres are made of the same kind of polymer. In addition, one type of water-insoluble dye in the microsphere may be different from another type of water-insoluble dye in the microsphere.

  By configuring the microsphere matrix with the same type of polymer, the material, size, specific gravity, etc. of the microspheres are approximately the same, thereby facilitating uniform dispersion of the microspheres in the aqueous ink composition for writing instruments. As a result, a desired hue can be easily obtained by color mixing.

  The content of the microsphere in the aqueous ink composition for writing instruments of the present invention can be 5% by mass or more, 7% by mass or more, or 10% by mass or more, and 45% by mass or less, 40% by mass or less, Or it can be 35 mass% or less. If it is less than 5% by mass, the color strength may be insufficient, and if it exceeds 45% by mass, the fluidity of the ink may be reduced.

  Below, each component of the water-based ink composition for writing instruments of this invention is demonstrated.

<water>
The water can be ion exchange water, distilled water, and the like.

<Microsphere>
The microsphere has a matrix and a water-insoluble dye.

  As shown in FIG. 1, the water-insoluble dye (4) is present more densely inside the matrix (2) than the surface of the matrix (2). Since the matrix (2) is exposed on the surface of the microsphere (10), the properties of the surface of each microsphere (10) can be made uniform, and as a result, the dispersion becomes more stable.

  The 10% strength measured by the micro compression test of the microsphere is 30 MPa or less. Here, the micro compression test can be performed using, for example, MCT-510 manufactured by Shimadzu Corporation. In this case, it can be set as an average value of five particles.

This 10% intensity can be calculated by the following equation.
C (x) = (2.48 × P) / (π × d ² )
C (x): 10% strength (MPa)
P: Test force at 10% displacement of particle diameter (N)
d: Particle diameter (mm)

  When the 10% strength is 30 MPa or less, 25 MPa or less, or 20 MPa or less, it is possible to obtain good scratch resistance of the drawn line of the aqueous ink composition for a writing instrument of the present invention.

  In addition, the 10% strength is preferably 5 MPa or more, 6 MPa or more, or 7 MPa or more in order to further obtain a good initial writing property of the aqueous ink composition for a writing instrument of the present invention.

  The 10% strength can be adjusted by adjusting the content of the polymer constituting the matrix and adding an auxiliary monomer or auxiliary prepolymer during the production of the matrix.

  The circularity coefficient of the microsphere measured by the image analysis method may be 0.6 to 1.0. Here, the image analysis method can be performed using, for example, Mactech's Mac-View. In this case, the average value of 500 particles is used.

This circularity coefficient can be calculated by the following formula: (4π × area of microsphere on image) / (peripheral length of microsphere on image) ² . The circularity coefficient calculated by this equation approaches 1 as the shape of the microsphere on the image approaches a perfect circle. When the shape of the microsphere on the image is a perfect circle, the circularity coefficient becomes 1. .

  This circularity factor can be 0.6 or more, 0.8 or more, or 0.9 or more, and can be 1.00 or less, 0.98 or less, or 0.95 or less. When the circularity coefficient is in the above range, desired initial writing properties and writing quality of the aqueous ink composition for a writing instrument of the present invention can be realized.

  The circularity coefficient can be adjusted by adjusting the content of the polymer constituting the matrix and adjusting the amount of the organic solvent in which the water-insoluble dye is dissolved.

  The dispersity coefficient of the microsphere measured by the laser diffraction method may be 1.0 to 1.8. Here, the laser diffraction method can be measured using a particle size distribution analyzer HRA9320-X100 (manufactured by Nikkiso Co., Ltd.) under the condition of a refractive index of 1.8.

  This dispersity coefficient can be calculated by the formula of volume average diameter of microspheres / number average diameter of microspheres. In the case of monodisperse particles having the same particle size, the dispersity coefficient is 1, and as this value increases, the variation in particle diameter increases.

  The dispersity coefficient can be 1.0 or more, 1.1 or more, or 1.2 or more, and can be 1.8 or less, 1.5 or less, or 1.3 or less. When the dispersity coefficient is in the above range, it is possible to prevent the degree of filling of the microspheres from being excessively increased, and as a result, it is possible to improve the initial writing property.

  The dispersity coefficient can be adjusted by adjusting the content of the polymer constituting the matrix and adjusting the temperature and polymerization time during polymerization.

  According to the configuration of the aqueous ink composition for a writing instrument of the present invention, a large amount of a water-insoluble dye can be contained in the microsphere. More specifically, the content of the water-insoluble dye in the microsphere can be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and 45% by mass or less, 40% by mass or less, Or it can be 35 mass% or less. This content rate can be calculated by (mass part of water-insoluble dye) / (mass part of water-insoluble dye + mass part of polymer) × 100.

  The average particle diameter of the microspheres when measured by the laser diffraction method is 0.3 μm or more, 0.5 μm or more, or 1.0 μm or more. And from the viewpoint of preventing the phenomenon of color loss on the back side of the paper, and preferably from 3.0 μm or less, 2.5 μm or less, or 2.0 μm or less from the viewpoint of preventing blurring of the handwriting. The average particle diameter here is a value of D50 calculated on a volume basis in the laser diffraction method.

  Here, the measurement of the average particle diameter by the laser diffraction method can be performed using, for example, a particle diameter distribution analyzer HRA9320-X100 manufactured by Nikkiso Co., Ltd.

{matrix}
The matrix is composed of a polymer.

(polymer)
The polymer constituting the matrix can be, for example, an epoxy polymer, a melamine polymer, an acrylic polymer, a urethane polymer, or a urea polymer, or a combination thereof.

{Water-insoluble dye}
The water-insoluble dye is a dye that is insoluble in water at room temperature. For example, a salt-forming dye, a disperse dye, an oil-soluble dye, or the like can be used, but a salt-forming dye is preferably used from the viewpoint of color development.

  Examples of the salt-forming dye include dyes having chemical structures of azo, metal complex azo, anthraquinone, and metal phthalocyanine. For example, Valifast (registered trademark) Black 1807, Varifast (registered by Orient Chemical Industry Co., Ltd.) Trademarks) Blue 2620, Varifast (registered trademark) Brown 2402, Varifast (registered trademark) Green 1501, Varifast (registered trademark) Orange 2210, Varifast (registered trademark) Pink 2310, Registered trademark Red13 (registered trademark) Red13 VIOLET 1701, Varifast (registered trademark) Yellow 1101, or the like can be used.

  Examples of disperse dyes include C.I. I. Disperse Yellow 198, C.I. I. Disperse Yellow 42, C.I. I. Disperse Red 92, C.I. I. Disperse Violet 26, C.I. I. Disperse Violet 35, C.I. I. Disperse Blue 60, and C.I. I. At least one dye selected from Disperse Blue 87 can be used.

  Examples of the oil-soluble dyes include Oil Black 860, Oil Blue 613, Oil Brown BB, Oil Green 530, Oil Orange 201, Oil Pink 312, Oil Red 5B, Oil Scallet 318, Oil Yell 318, Oil Y 318 Can be used.

<Other ingredients>
The water-based ink composition for writing instruments of the present invention contains various additives such as rust preventives, antiseptics, pH adjusters, lubricants, humectants, resins, thickeners such as natural polysaccharides, and the like. May be.

《Writing instrument》
The writing instrument of the present invention includes at least an ink storage unit, a writing unit, and a holding unit. In the ink storage section, the above-described aqueous ink composition for writing instruments is stored. The writing instrument of the present invention may be a sign pen or a ballpoint pen.

  Here, “sign pen” in the present specification means a pen having a mechanism for supplying ink stored in an ink storage unit to a resin writing unit by capillary action. Also included are pens referred to as “marking pens”. Further, in this specification, the “ball pen” means a pen having a mechanism for causing the ink stored in the ink storage unit to bleed by the rotation of the ball provided in the writing unit.

<Ink storage section>
The ink storage unit stores the above-described aqueous ink composition for writing instruments.

  As the ink storage unit, any material can be used as long as it can store ink and supply ink to the writing unit.

<Writing part>
The writing unit may be made of an optional material depending on the use of the writing instrument. When the writing instrument of the present invention is a sign pen, examples of the writing unit include a fiber core and a plastic core. When the writing instrument of the present invention is a ballpoint pen, the writing unit can be a writing unit provided with a ballpoint pen tip at the tip.

<< Method for Producing Aqueous Ink Composition for Writing Instruments >>
The method for producing a water-based ink composition for a writing instrument according to the present invention can include a microsphere preparation step and an ink composition preparation step.

<Microsphere creation process: Emulsion polymerization method>
The microsphere preparation step by the emulsion polymerization method includes the steps of preparing an oil phase, preparing an aqueous phase, and mixing the oil phase and the aqueous phase to emulsify the components of the oil phase, followed by polymerization.

{Oil phase}
The oil phase contains an organic solvent, a water-insoluble dye, and a monomer or prepolymer. A plurality of these organic solvents may be contained.

  This oil phase is prepared by adding a water-insoluble dye and stirring while warming the organic solvent to a predetermined temperature, then adding a monomer or prepolymer, and optionally adding another organic solvent. Can do.

(Organic solvent)
The solubility of the organic solvent in water at 25 ° C. can be 0.1 g / 100 g or more, 1 g / 100 g or more, 3 g / 100 g or more, or 5 g / 100 g or more, and 40 g / 100 g or less, 35 g / 100 g. Hereinafter, it can be 30 g / 100 g or less, or 25 g / 100 g or less.

  The solubility is preferably 0.1 g / 100 g or more, 1 g / 100 g or more, 3 g / 100 g or more, or 5 g / 100 g or more from the viewpoint of satisfactorily dispersing the dye, and 15 g / 100 g or less, 14 g / 100 g or more. It is preferable that it is 100 g or less, 13 g / 100 g or less, or 10 g / 100 g or less from the viewpoint of suppressing the precipitation of the dye and the resin and obtaining a preferable circularity.

  As the organic solvent whose solubility satisfies the above range, for example, phenyl glycol, benzyl alcohol, ethylene glycol monobenzyl ether, ethyl acetate and the like can be used.

  Moreover, as an organic solvent, you may use separately the organic solvent whose solubility to water in 25 degreeC is less than 0.1 g / 100g. Examples of such an organic solvent include alkyl sulfonic acid phenyl ester, ethyl hexyl phthalate, tridecyl phthalate, ethyl hexyl trimellitic acid, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, and liquid xylene resin.

(Water-insoluble dye)
As the water-insoluble dye, the water-insoluble dyes mentioned for the microsphere can be used.

(Monomer or prepolymer)
Various monomers or prepolymers constituting the polymer are selected according to the purpose. For example, melamine monomer or prepolymer, epoxy monomer or prepolymer, acrylic monomer or prepolymer, isocyanate monomer or prepolymer can be used.

  As the melamine monomer or prepolymer, melamine, melamine cyanurate, ethylene dimelamine, methylol melamine or the like can be used.

  As the epoxy monomer or prepolymer, allyl glycidyl ether, bisphenol A-epichlorohydrin prepolymer, or the like can be used.

  Examples of the acrylic monomer or prepolymer include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, pentyl (meth) acrylate, hexyl ( A (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. can be used.

  As the isocyanate monomer or prepolymer, for example, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, isocyanate prepolymer and the like can be used.

  As the isocyanate prepolymer, it is preferable to use a trimer such as the above-mentioned isocyanate triol adduct or a modified isocyanurate from the viewpoint of curing the microspheres favorably by polymerization. Further, by using a dimer such as the above-mentioned isocyanate allophanate as an auxiliary prepolymer together with the above trimer, the circularity coefficient can be reduced and the strength can be reduced by 10%. It may be preferable.

{Water phase}
The aqueous phase can be prepared by mixing water and a dispersant. As the dispersant, for example, polyvinyl alcohol can be used, but is not limited thereto.

{Emulsification and polymerization process}
The step of emulsifying and further polymerizing the components of the oil phase can be carried out by introducing the oil phase into the aqueous phase and emulsifying and mixing while heating to a predetermined temperature using a homogenizer or the like.

{Other processes}
The microsphere creation step may include another step, for example, a step of classifying the microsphere.

<Microsphere creation process: Phase separation method>
The microsphere preparation step by the phase separation method includes preparing a dye-containing solution, preparing a protective colloid agent-containing solution, and polymerizing a monomer or a prepolymer.

{Preparation of dye-containing solution}
The dye-containing solution can be prepared by heating and dissolving a water-insoluble dye in an organic solvent. As the water-insoluble dye and the organic solvent, those mentioned for the microsphere preparation step by emulsion polymerization can be used.

{Preparation of protective colloid agent-containing solution}
The protective colloid agent-containing solution can be prepared by dissolving the protective colloid agent in water.

  As the protective colloid agent, for example, methyl vinyl ether-maleic anhydride copolymer can be used.

{Polymerization of monomer or prepolymer}
In the polymerization of the monomer or prepolymer, the dye-containing solution is added to the protective colloid agent-containing solution heated to a predetermined temperature and dispersed in oil droplets, and the monomer or prepolymer is added thereto to maintain the temperature. And stirring. According to this, the water-insoluble dye is included in the polymer obtained by polymerizing the monomer or the prepolymer.

  As the monomer or prepolymer, those mentioned for the microsphere preparation step by emulsion polymerization can be used.

<Ink composition preparation process>
The ink composition preparation step can be performed by a conventionally known method while mixing the prepared microspheres and other components constituting the water-based ink composition for writing instruments using a stirring device such as a disper.

  The present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these.

<< Preparation of water-based ink composition for writing instruments >>
<Production of microspheres>
{Microsphere A}
(Preparation of oil phase solution)
While heating 12.5 parts by mass of ethyl acetate as an organic solvent to 60 ° C., 3.5 parts by mass of oil-soluble black dye (Oil Black 860, Orient Chemical Industry Co., Ltd.) as a water-insoluble dye is sufficiently added. Dissolved in. Next, 8 parts by mass of isocyanurate-modified hexamethylene diisocyanate (TLA-100, Asahi Kasei Chemicals) as a prepolymer was added thereto to prepare an oil phase solution.

(Preparation of aqueous phase solution)
While heating 200 parts by mass of distilled water to 60 ° C., 15 parts by mass of polyvinyl alcohol (PVA-205, Kuraray Co., Ltd.) as a dispersant was dissolved therein to prepare an aqueous phase solution.

(Emulsion polymerization)
The oil phase solution was added to the 60 ° C. aqueous phase solution and stirred for 6 hours with a homogenizer to emulsify and complete the polymerization. Microspheres were collected by centrifuging the obtained dispersion, and microsphere A was obtained.

{Microsphere B}
Microsphere B was obtained in the same manner as microsphere A except that 8 parts by mass of the isocyanurate-modified hexamethylene diisocyanate was changed to 6 parts by mass.

{Microsphere C}
Microsphere D was obtained in the same manner as Microsphere A, except that 8 parts by mass of the isocyanurate-modified hexamethylene diisocyanate was changed to 15 parts by mass.

{Microsphere D}
3.5 parts by mass of water-insoluble dye (Oil Black 860, manufactured by Orient Chemical Co., Ltd.) is 2.8 parts by mass of water-insoluble dye (Valifast Red 1355, manufactured by Orient Chemical Co., Ltd.), and 12.5 parts by mass of ethyl acetate is ethylene. Dimethylmethane diisocyanate (3 mol) adduct of trimethylolpropane (1 mol) with 11.5 parts by mass of glycol monobenzyl ether and 8 parts by mass of isocyanurate-modified hexamethylene diisocyanate (TLA-100, Asahi Kasei Chemicals) (D -109, Mitsui Chemicals Co., Ltd.) was changed to 7.2 parts by mass, and Microsphere D was obtained in the same manner as Microsphere A.

{Microsphere E}
Microsphere E was obtained in the same manner as Microsphere D, except that 7.2 parts by mass of trimethylolpropane (1 mol) adduct of diphenylmethane diisocyanate (3 mol) was changed to 9.6 parts by mass.

{Microsphere F}
Except for changing 7.2 parts by weight of the isocyanate compound to 1.2 parts by weight and further adding 6.0 parts by weight of an allophanate modified product of hexamethylene diisocyanate (D-178NL, Mitsui Chemicals) as an auxiliary prepolymer, In the same manner as Microsphere D, Microsphere F was obtained.

{Microsphere G}
(Preparation of dye-containing solution)
2.4 parts by mass of a water-insoluble dye (Varifast Blue 2620, Orient Chemical Industry Co., Ltd.) is dissolved in 9.6 parts by mass of benzyl alcohol as an organic solvent while stirring at 70 ° C. to prepare a dye-containing solution. did.

(Preparation of protective colloid agent-containing solution)
40 parts by mass of methyl vinyl ether-maleic anhydride copolymer (Gantretz AN-179, ISP Co.) as a protective colloid agent is dissolved in water, the pH is adjusted to 4 with sodium hydroxide, and the total is 200 parts by mass. A solution containing a protective colloid agent was prepared so that

(Polymer polymerization)
While the protective colloid agent-containing solution is heated and stirred at 70 ° C., the dye-containing solution is added thereto and dispersed in the form of oil droplets, and then methylolmelamine as a monomer (Nical Resin S-260, manufactured by Nippon Carbide Industries, Ltd.) 7 .6 parts by mass were gradually added, the temperature was maintained, and this was heated and stirred for 50 minutes to polymerize methylol melamine to obtain a microsphere dispersion. The dispersion was cooled to room temperature, acid addition, filtration, washing with water, and drying using a spray dryer, to obtain Microsphere G.

{Microsphere H}
Microsphere H is obtained in the same manner as microsphere G except that 7.6 parts by mass of methylolmelamine is changed to 9.6 parts by mass and benzyl alcohol is changed from 9.6 parts by mass to 20 parts by mass. It was.

{Microsphere I}
Microsphere I was obtained in the same manner as Microsphere H, except that 7.6 parts by mass of methylolmelamine was changed to 12.8 parts by mass.

{Microsphere J}
2.4 parts by mass of water-insoluble dye (Valifast Blue 2620, Orient Chemical Industries) is 4 parts by mass of water-insoluble dye (Valifast Yellow 1101, Orient Chemical Industry), and 9.6 parts by mass of benzyl alcohol is 16 parts by mass of phenyl glycol. In addition, Microsphere J was obtained in the same manner as Microsphere G, except that 7.6 parts by mass of methylolmelamine was changed to 8.4 parts by mass.

<Preparation of ink composition>
{Examples 1-8 and Comparative Examples 1 and 2}
Microspheres (15 parts by mass), xanthan gum (KESLAN S, Sanki Co., Ltd., 0.18 parts by mass) as a thickener, phosphate ester (Price Surf A219B, Daiichi Kogyo Seiyaku Co., Ltd., 0.5 Mass parts), preservatives (Bioden 421, Daiwa Chemical Industry Co., Ltd., 0.2 parts by mass), benzotriazole (0.3 parts by mass) as a rust inhibitor, and aminomethylpropanol (0.1 100 parts of the aqueous ink compositions for ballpoint pens of Examples 1 to 8 and Comparative Examples 1 and 2 using 100 parts by mass), propylene glycol (15 parts by mass) as a solvent, and ion-exchanged water (68.72 parts by mass). A mass part was produced.

{Examples 9 to 11}
Microsphere (15 parts by mass), preservative (Bioden 421, Daiwa Chemical Industry Co., Ltd., 0.2 parts by mass), aminomethylpropanol (0.1 parts by mass) as a pH adjuster, propylene glycol as a solvent (3 parts by mass) and ion-exchanged water (81.7 parts by mass) were used to prepare 100 parts by mass of the water-based ink composition for sign pens of Examples 9-11.

{Examples 12 and 13}
Example 1 except that microsphere G (12 parts by mass) and microsphere J (6 parts by mass) were used as the microspheres, and that the mass part of ion-exchanged water was changed to 65.72 parts by mass. Similarly, 100 parts by mass of the aqueous ink composition for ballpoint pens of Example 12 was produced.

  As Example 9, except that microsphere G (12 parts by mass) and microsphere J (6 parts by mass) were used as microspheres, and that the mass part of ion-exchanged water was changed to 78.7 parts by mass. Similarly, 100 parts by mass of the water-based ink composition for sign pens of Example 13 was produced.

<Evaluation>
<Evaluation of microsphere>
{10% strength}
About the produced microsphere, 10% intensity | strength was calculated | required using Shimadzu Corporation MCT-510.

{Circularity factor}
About the produced microsphere, the circularity coefficient was calculated | required by the image-analysis method using Mactech's Mac-View.

{Dispersion coefficient}
About the produced microsphere, the dispersity coefficient was measured by the laser diffraction method on condition of refractive index 1.8 using the particle diameter distribution analyzer HRA9320-X100 of Nikkiso Co., Ltd.

<Evaluation of water-based ink composition for writing instruments>
{Creating writing instruments}
(Making water-based ballpoint pen)
Examples 1 to 5 were used for a refill comprising a polypropylene ink storage tube (inner diameter 4.0 mm, length 113 mm), a stainless steel tip (hard metal ball, ball diameter 0.5 mm), and a joint connecting the storage tube and the tip. 8 and 12, and the aqueous ink compositions for writing instruments of Comparative Examples 1 and 2 were filled. Next, an ink follower made of polybutene was loaded at the rear end of the ink. This refill was loaded on the shaft of a ballpoint pen (Signo UM-100, Mitsubishi Pencil Co., Ltd.) to prepare an aqueous ballpoint pen.

(Making marking pen)
PM-120T manufactured by Mitsubishi Pencil Co., Ltd. (trade name “Prockey”, pen core: extra fine core (POM resin core) and fine round core (PET fiber core), the same applies hereinafter) to the pen body of Examples 9 to 11 and 13. A sign pen was prepared by filling a water-based ink composition for a writing instrument. The following evaluation on the sign pen was performed using a thin circular core.

{Evaluation of scratch resistance}
Write 20 pens with a diameter of about 2cm in spiral shape on high-quality paper with a pen body of 64g / m ² (manufactured by Nippon Paper Industries Co., Ltd.). After 1 minute, Kimwipe (Japan) The paper was made by Cressia Co., Ltd., and rubbed 5 times with a 500 g weight. This test was performed in an environment of 25 ° C. and 60% RH. The evaluation criteria are described below.
Evaluation criteria:
A: There is no change before rubbing.
◯: A portion where the drawn line is thinner than that before rubbing is slightly recognized.
(Triangle | delta): The part where the drawn line became thin compared with before abrasion is recognized.
X: The drawn line is thin over the entire drawn line as compared to before rubbing.

{Evaluation of initial writing properties}
Evaluation of “first writing property” is performed by first confirming that writing is possible by handwriting, and using an automatic writing tester compliant with ISO standard 14145-1 one day after handwriting is completed. Speed: 4.5 m / min, writing angle: 60 ° (marking pen is 65 °) writing load: 100 g (marking pen is 50 g) The distance from the start of the writing test to the smooth recording of drawn lines The measurement was performed by taking the average value of the measurement results of five writing instruments. The evaluation criteria are shown below.
Evaluation criteria:
A: The distance from the start of the writing test to the smooth recording of drawn lines was within 2 mm.
○: The distance from the start of the writing test to the smooth recording of the drawn line was within 5 mm.
Δ: The distance from the start of the writing test to the smooth recording of drawn lines was within 10 mm.
X: The distance from the start of the writing test to the smooth recording of drawn lines was 10 mm or more.

{Evaluation of writing quality}
On a commercial PPC paper, “VENENO” was written, and the writing quality was evaluated according to the following criteria.
Evaluation criteria:
A: Very smooth.
○: Smooth.
Δ: Feels a little heavy.
X: Heavy.

  The results are shown in Tables 1-3. In Table 1, “the content of the dye in the microsphere” is calculated by (mass part of water-insoluble dye) / (mass part of water-insoluble dye + mass part of polymer component) × 100.

  From Table 1, when comparing the microspheres A to C, increasing the content of the polymer component increases the strength by 10%, brings the circularity coefficient closer to 1.0, and reduces the dispersion coefficient. You can understand that you can. Moreover, the same tendency can also be confirmed between the microspheres D to E and the microspheres G to I.

  Further, when comparing the microspheres D and F, when most of the trimethylolpropane (1 mol) adduct of diphenylmethane diisocyanate (3 mol) is replaced with an allophanate modified product of hexamethylene diisocyanate as an auxiliary prepolymer, 10% It can be seen that the strength and circularity are reduced. From this it can be seen that the 10% strength and circularity factor can also be adjusted by adding auxiliary monomers or prepolymers.

  Further, from Table 2, for ballpoint pens, the greater the 10% strength and / or the closer the circularity coefficient is to 1.0, the better the initial writing properties and the dispersity coefficient. It can be understood that the lower the value, the better the writing quality, and the smaller the 10% strength, the better the scratch resistance. In addition, it can be understood from Table 3 that the same tendency is observed for the marking pen. Furthermore, when the results of both are combined, even if the compositions are different, the same results are obtained if the microspheres are of the same type, so that the microspheres are directly related to initial writing properties, writing quality and scratch resistance. You can see that it contributes. It can be seen from Table 4 that this applies even when the matrix is composed of the same type of polymer and a plurality of types of microspheres containing different water-insoluble dyes.

2 Matrix 4 Water-insoluble dye 10 Microsphere

Claims (6)

Containing microspheres with water, a matrix composed of a polymer, and a water-insoluble dye;
The water-insoluble dye is present in the matrix more densely than the surface of the matrix, and the 10% strength of the microsphere by a micro compression test is 30 MPa or less.
A water-based ink composition for writing instruments.   The aqueous ink composition for a writing instrument according to claim 1, wherein the microsphere has a circularity coefficient measured by an image analysis method of 0.6 to 1.0.   The water-based ink composition for a writing instrument according to claim 1 or 2, wherein the content of the water-insoluble dye in the microsphere is 10% by mass to 45% by mass.   The water-based ink composition for writing instruments as described in any one of Claims 1-3 whose average particle diameter of the said microsphere when it measures by a laser diffraction method is 0.3-3.0 micrometers. Containing at least two microspheres according to any one of claims 1 to 4,
One type of matrix of the microspheres and another type of matrix of the microspheres are made of the same type of polymer, and one type of water-insoluble dye of the microspheres, and the microspheres Different from other kinds of water insoluble dyes,
A water-based ink composition for writing instruments. At least an ink storage unit, a writing unit and a holding unit;
The water-based ink composition for a writing instrument according to any one of claims 1 to 5 is stored in the ink storage unit.
Writing instrument.