JP2016113597A - Aqueous ink composition for writing instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink composition for writing instrument having clear stopping, tapering-off and bent-back strokes and hardly generating defects of written lines.SOLUTION: There is provided an aqueous ink composition containing at least polyvinyl alcohol, at least one kind selected from boric acid and a salt thereof or diglyceryl borate, a resin dispersion type pigment and a self dispersion type pigment.SELECTED DRAWING: None

Description

  The present invention relates to a water-based ink composition for a writing instrument that has clear tome, splash, and fold, and does not cause a loss of writing lines.

  Conventionally, as a water-based ink composition for a writing instrument in which tome, shine, and harpoon are clarified, the present applicant has 1) containing at least water and a colorant and having a dierant fluid property in at least a part of a specific shear rate. An aqueous ballpoint pen ink composition (see, for example, Patent Document 1), 2) containing polyvinyl alcohol having a polymerization degree of 50 to 2000, boric acid and at least one of its salts, and having an ink viscosity A water-based ballpoint pen ink composition having a certain range is proposed (for example, see Patent Document 2).

These water-based ink compositions for ballpoint pens containing polyvinyl alcohol are characterized by little blurring of drawn lines, and the tome, splash, and halo are clear.
However, water-based ballpoint pens containing these polyvinyl alcohols use polyvinyl alcohol and the cohesiveness of boric acid, etc., so that bleeding and feathering are less likely to occur, but the edges of the drawn lines are not flat. However, it may be partially missing. This phenomenon is presumed to be due to the fact that polyvinyl alcohol agglomerates on the ball surface to generate an area where no ink exists, and as a result, the ink is transferred in a deficient state.

On the other hand, an aqueous ink composition containing a semipolar boron compound such as diglyceryl borate is known as an aqueous ink composition used for inkjet printers, stationery, and various printing applications (see, for example, Patent Document 3). ing.
However, this water-based ink composition provides a water-based ink composition that has a good balance of surface tension, wettability, and drying property and can improve image quality in ink jet recording and the like even with a simple composition. In addition, the present invention is different from the present invention in the purpose of use and the problems, and there is no description or recognition about the synergistic action of the specific physical properties of polyvinyl alcohol and the specific pigment.

JP 2014-95070 A (Claims, Examples, etc.) JP 2014-95071 A (Claims, Examples, etc.) JP-A-10-324830 (Claims, Examples, etc.)

  The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to solve this problem, and has a high performance that clearly shows the tome, splash, and fold that are the characteristics of a water-based ink composition for a writing instrument containing a polyvinyl alcohol. An object of the present invention is to provide a water-based ink composition for a writing instrument that does not cause a loss of writing lines while achieving both.

  As a result of intensive studies in view of the above-described conventional problems, the present inventors have found that at least one selected from polyvinyl alcohol, boric acid and salts thereof, or diglyceryl borate, and two specific pigments. The inventors have found that the water-based ink composition for a writing instrument can be obtained by including at least the above object, and have completed the present invention.

That is, the present invention resides in the following (1) to (3).
(1) A water-based ink composition for a writing instrument, comprising at least one selected from polyvinyl alcohol, boric acid and salts thereof, or diglyceryl borate, and at least a resin-dispersed pigment and a self-dispersed pigment.
(2) The water-based ink composition for a writing instrument as described in (1) above, wherein the mass ratio of the resin dispersed pigment / self-dispersed pigment is 1/2 to 5/1.
(3) A writing instrument comprising the water-based ink composition for a writing instrument described in (1) or (2) above.

  According to the present invention, there is provided an aqueous ink composition for a writing instrument that has clear tome, sag, and fold, and does not cause a loss of writing lines.

Hereinafter, embodiments of the present invention will be described in detail.
The water-based ink composition for a writing instrument of the present invention comprises at least one selected from polyvinyl alcohol, boric acid and salts thereof, or diglyceryl borate, and a resin-dispersed pigment and a self-dispersed pigment. Is.

Polyvinyl alcohol (hereinafter simply abbreviated as “PVA”) used in the present invention is represented by the general formula: — [CH ₂ —CH (OH)] m— [CH ₂ —CH (OCOCH ₃ ] n—. The saponification degree {[m / (m + n)] × 100} is preferably 50 mol% or more, and more preferably 75 mol, from the viewpoints of ink stability over time and viscosity imparting property. % Or more is desirable.
In addition, in the PVA having the above saponification degree, the degree of polymerization (m + n) is preferably 50 or more, and more preferably, from the viewpoint of enhancing the beautiful character feeling such as tome, honey, and hari without impairing the writing feeling and coloring property. Is preferably 100 to 3000, particularly preferably 200 to 2000.
Specific examples of PVA that can be used include commercially available A-type GOHSENOL series, G-type GOHSENOL series, and K-type GOHSENOL series (trade names manufactured by Nippon Synthetic Chemical Industry Co., Ltd.). ), J-Povar series (trade name, manufactured by Nippon Vinegar-Poval), KURARAY POVAL PVA series (product name, manufactured by Kuraray) manufactured by Kuraray.
PVA which has these saponification degrees and polymerization degrees may be used individually by 1 type, and may use 2 or more types together.

Moreover, modified PVA, Preferably modified PVA which becomes the said polymerization degree range and saponification degree can also be used for PVA of this invention. Examples of modified PVA that can be used include those in which the hydroxyl group or acetic acid group of PVA is modified with a modifying group such as a carboxyl group, a sulfonic acid group, or an ethylene oxide group, or those having the above-mentioned modifying group in the side chain of PVA. Can be mentioned. A PVA / acrylic acid / methyl methacrylate copolymer obtained by copolymerizing partially saponified PVA with acrylic acid and methyl methacrylate can also be used as the modified PVA of the present invention.
Specific examples of modified PVA that can be used include the commercially available Gosennex L series manufactured by Nippon Synthetic Chemical Industry Co., Ltd., the Gosennex WO series (trade name manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and anion modified by Nihon Vineyard & Poval. PVA (A series) (Nippon Vinegar-Povar product name), Kuraray Exval 1713 (Kuraray product name), and the like. Examples of the PVA / acrylic acid / methyl methacrylate copolymer include POVACOAT (trade name, manufactured by Daido Kasei Kogyo Co., Ltd.).
These modified PVA may be used individually by 1 type, and may use 2 or more types together.

The total content of such PVA and modified PVA is 0.1 to 10% by mass (hereinafter simply abbreviated as “%”), preferably 0.3, with respect to the total amount of the aqueous ink composition for writing instruments. It is desirable that it is ˜7%, particularly preferably 0.5 to 5%.
If the content is less than 0.1%, the viscosity imparting performance is not sufficient, and the resistance to blurring of drawn lines decreases. On the other hand, if the content exceeds 10%, the viscosity is too high and the ink follow-up performance decreases. It is not preferable.

At least one selected from boric acid and a salt thereof, or diglyceryl borate used in the present invention is contained from the viewpoint of clarifying tome, honey, and halai by interaction with PVA.
Examples of boric acid and salts thereof that can be used include boric acid, alkali metal salts of boric acid (lithium, sodium, potassium, rubidium), ammonium salts of boric acid, and the like, for example, boric acid (H ₃ BO ₃ ), Diboric acid triborate (B ₂ O ₃ ), sodium metaborate (NaBO ₂ ), sodium diborate (Na ₄ B ₂ O ₅ ), sodium tetraborate (Na ₂ B ₄ O ₇ ), pentaboron Sodium phosphate (NaB ₅ O ₈ ), sodium hexaborate (Na ₂ B ₆ O ₁₀ ), sodium octaborate (NaB ₈ O ₁₃ ), ammonium borate [(NH ₄ ) ₂ O · 5B ₂ O ₃ ], In addition, these hydrates and the like can be mentioned. These may be used alone or in combination of two or more.
Preferably, it is desirable to use sodium tetraborate, ammonium borate, or diboric acid triborate from the viewpoint of solubility in ink components and versatility.

The diglyceryl borate to be used is a kind of semipolar boron compound having plus (+) and minus (−) polarities in the molecule, which is synthesized from two molecules of glycerin and one molecule of boric acid and represented by the following formula. It is.

The total content of at least one selected from the boric acid and salts thereof or diglyceryl borate is 0.1 to 5%, preferably 0.5 to 3%, based on the total amount of the aqueous ink composition for writing instruments. Is desirable.
If the content is less than 0.1%, interaction with PVA may not occur. On the other hand, if the content exceeds 5%, the ink may not be completely dissolved, which is not preferable.

In the present invention, the pigment used as the coloring material is a resin-dispersed pigment or a self-dispersed pigment.
The reason why these resin-dispersed pigments and self-dispersed pigments are used is to exhibit the function as a coloring material without causing the loss of drawn lines.
In the present invention, the “resin dispersed pigment” refers to a pigment that can be dispersed by a dispersant (resin dispersion). A dispersant such as a resin (polymer) used for the resin-dispersed pigment will be described later.
The “self-dispersing pigment” refers to a pigment that can be dispersed or dissolved in an aqueous medium without a dispersant. For example, without using a dispersant for dispersing the pigment, A pigment in which a hydrophilic group is bonded (grafted) to the surface of the pigment by performing a physical treatment or a chemical treatment. Examples of the hydrophilic group, for _{example, -COOM, -SO 3 M, -SO} 2 M, -CO -, - OM, -SO 2 NH 2, -RSO 2 M, -PO 3 HM, -PO 3 M 2, One or more hydrophilic groups selected from —SO ₂ NHCOR, —NH ₃ , and —NR ₃ are preferable. Note that M in these formulas independently represents a hydrogen atom, an alkali metal, ammonium, a phenyl group which may have a substituent, or organic ammonium. R in these formulas independently represents an alkyl group having 1 to 12 carbon atoms or a naphthyl group which may have a substituent.
Examples of the physical treatment include vacuum plasma treatment, and chemical treatment includes, for example, a wet oxidation method in which oxidation is performed with an oxidizing agent in water, or by bonding p-aminobenzoic acid to the pigment surface. Examples thereof include a method of bonding a carboxyl group through a phenyl group.

The resin-dispersed pigment that can be used is not particularly limited as long as it is a pigment contained in the above-mentioned resin-dispersed pigment, and examples thereof include inorganic pigments such as carbon black, general organic pigments, and titanium oxide. Can do.
The self-dispersing pigment that can be used is not particularly limited as long as it is a pigment contained in the above-mentioned self-dispersing pigment, and examples thereof include self-dispersing carbon black and self-dispersing organic pigments. .
Examples of commercially available products include Microjet series manufactured by Orient Chemical Industry Co., Ltd., CAB-O-JET series manufactured by Cabot Corporation, and the like.
These resin-dispersed pigments and self-dispersed pigments can be used alone or in admixture of two or more.

The total content of these resin-dispersed pigment and self-dispersed pigment is preferably in the range of 2 to 10%, particularly preferably in the range of 4 to 8%, with respect to the total amount of the aqueous ink composition for writing instruments. It is desirable to do.
When the content is less than 2%, the function as a coloring material is not sufficient. On the other hand, when the content exceeds 10%, the stability of the ink is impaired, which is not preferable.
In the present invention, the content ratio of the resin-dispersed pigment / self-dispersed pigment is preferably in the range of 1/2 to 5/1 by mass ratio, particularly preferably in the range of 1/1 to 3/1. It is desirable to make it contain.
By making this content ratio ½ or more, there is no loss of drawn lines. On the other hand, by setting it to 5/1 or less, no bleeding occurs in drawn lines, and the effect of the present invention is made more highly favorable. Will be able to.

  In the aqueous ink composition for a writing instrument of the present invention, the polyvinyl alcohol, at least one selected from boric acid and salts thereof, or diglyceryl borate, a resin-dispersed pigment and a self-dispersed pigment are contained, and the remainder In addition to water (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as a solvent, each component usually used for a dispersant and a writing instrument, for example, a water-soluble organic solvent, the above PVA , Boric acid and its salts, viscosity modifiers other than diglyceryl borate, color materials other than the above-mentioned resin dispersed pigments and self-dispersed pigments, lubricants, rust preventives, antiseptics or fungicides, pH adjusters, etc. It can contain suitably in the range which does not impair the effect of this invention.

Examples of the dispersant that can be used include styrene- (anhydride) maleic acid copolymer and salts thereof, styrene-acrylic acid copolymer and salts thereof, α-methylstyrene-acrylic acid copolymer and salts thereof, and the like. Examples thereof include at least one of polyacrylic acid and polymethacrylic acid copolymer.
The content of these dispersants may be an amount that can favorably disperse the resin-dispersed pigment, and is preferably 10 to 40% by mass ratio with respect to the pigment component to be dispersed. desirable.

Examples of water-soluble organic solvents that can be used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, and glycerin, ethylene glycol monomethyl ether, and diethylene glycol monomethyl. Examples include glycol ethers such as ether, and these can be used alone or in admixture of two or more.
The content of these water-soluble organic solvents is preferably 3 to 30% with respect to the total amount of the water-based ink composition for writing instruments.

As the viscosity modifier that can be used, for example, at least one selected from the group consisting of synthetic polymers and cellulose is desirable. Specifically, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, starch glycolic acid and its salts, propylene glycol alginate, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylic acid and its salts, carboxyvinyl polymer, polyethylene oxide, acetic acid Examples include vinyl / polyvinylpyrrolidone copolymers, cross-linked acrylic acid polymers and salts thereof, non-cross-linked acrylic acid polymers and salts thereof, and styrene-acrylic acid copolymers and salts thereof.
Lubricants include nonionics such as fatty acid esters of polyhydric alcohols, higher fatty acid esters of sugars, polyoxyalkylene higher fatty acid esters, alkyl phosphate esters, etc., which are also used as pigment surface treatment agents, phosphate esters, and higher fatty acid amides. Anionic compounds such as alkyl sulfonates and alkyl allyl sulfonates, polyalkylene glycol derivatives, fluorine-based surfactants, polyether-modified silicones, and the like.
In addition, as rust preventives, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, saponins, etc., as antiseptics or fungicides, phenol, sodium omadin, sodium benzoate, benzimidazole compounds, etc. Can be mentioned.
Examples of pH adjusters include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide, amine compounds such as triethanolamine, diethanolamine, monoethanolamine, dimethylethanolamine, morpholine and triethylamine, ammonia, etc. Is mentioned.
Further, as a colorant other than the resin-dispersed pigment and the self-dispersed pigment, for example, a general water-soluble dye or an activator-dispersed pigment may be supplementarily contained within a range not impairing the effects of the present invention. it can.

  In order to produce this water-based ink composition for writing instruments, a conventionally known method can be employed, for example, polyvinyl alcohol, at least one selected from boric acid and salts thereof, or diglyceryl borate, A resin-dispersed pigment, a self-dispersing pigment, and a dispersant are included, and a predetermined amount of each component in water is blended and obtained by stirring and mixing with a stirrer such as a homomixer or a disper. Further, if necessary, coarse particles in the ink composition may be removed by filtration or centrifugation, and may be prepared while defoaming, heating and cooling.

The water-based ink composition for a writing instrument of the present invention can be mounted on various writing instruments such as a marking pen, a sign pen, and a ballpoint pen, and the ballpoint pen can be mounted on a ballpoint pen having a pen tip such as a metal chip or a resin chip for use. it can.
A ballpoint pen that can be used is one that is equipped with a water-based ink composition for writing instruments having the above composition, and preferably a ballpoint pen tip that rotatably holds a metal ball or the like is inserted directly or via a relay member. It is desirable that the ink containing tube made of a pipe or a pipe-shaped molded article is filled with the ink composition having the above characteristics, and an ink follower is disposed on the rear end surface of the ink composition. As the ink follower, a substance that is not compatible with the water-based ink composition for writing instruments stored in the ink storage tube and has a low specific gravity with respect to the ink composition for water-based ballpoint pens, such as polybutene, silicone oil, Mineral oil etc. are mentioned.
The structure of the ballpoint pen is not particularly limited. For example, the ballpoint pen has a collector structure (ink holding mechanism) in which the shaft cylinder itself is used as an ink container and is filled with the water-based ink composition for a writing instrument having the above-described configuration. It may be a liquid ballpoint pen.

The reason why the water-based ink composition for a writing instrument of the present invention configured as described above expresses the function of clear tome, honey, and fold, and no loss of writing lines can be estimated as follows. it can.
That is, the water-based ink composition for a writing instrument of the present invention includes at least one selected from polyvinyl alcohol, boric acid and salts thereof, or diglyceryl borate, and a resin-dispersed pigment and a self-dispersed pigment. In the range where the writing speed and writing pressure in the tome, sag, and halai portions fluctuate, it is estimated that suitable ink flow characteristics are exhibited and the ink easily diffuses on the paper surface. The
The water-based ink composition for a writing instrument of the present invention is extremely excellent in the sustaining effect that exerts the effect of the present invention, and has a long onset period and duration of the effect, and is water-soluble, so that it is stable over time. It is also excellent in properties.

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

[Examples 1 to 9 and Comparative Examples 1 to 4]
According to the formulation shown in Table 1 below, water-based ink compositions for writing instruments were prepared by a conventional method.
About each obtained water-based ink composition for writing tools (100 mass% of whole quantity), an aqueous ball-point pen was produced as a writing tool by the following method, and the following each evaluation method was carried out, and the blotting and blurring of a tome, a splash, a halai, initial writing performance, and a drawn line. , And evaluated for missing strokes.
Table 1 below shows the formulation of Examples 1 to 9 and Comparative Examples 1 to 4 and their respective evaluation results.

(Writing instrument: Production of water-based ballpoint pen)
Using a shaft of a ballpoint pen [Mitsubishi Pencil Co., Ltd., trade name: Signo UM-100], an polypropylene ink container having an inner diameter of 4.0 mm and a length of 113 mm and a stainless tip (a cemented carbide ball, a ball diameter of 0.1 mm). 7 mm) and a refill made of a joint connecting the receiving tube and the tip was filled with each ink, and an ink follower made of polybutene was loaded at the rear end of the ink to produce an aqueous ballpoint pen.

(Tome evaluation method)
Using each of the water-based ballpoint pens prepared above, “Ei” was written freehand on the writing test paper, and the blotting of the first stroke and the state of the edge were visually evaluated according to the following evaluation criteria.
Evaluation criteria:
○: There is almost no bleeding and mottling.
Δ: Slight bleeding or blur
X: Bleeding and blurring are severe, and the drawn lines are ugly.

(How to evaluate honey)
Using the water-based ballpoint pens prepared above, the character “Ei” was written freehand on the writing test paper, and the condition of the splash at the end of the second stroke was visually evaluated according to the following evaluation criteria.
Evaluation criteria:
○: The drawn line at the end of the brush is very thin, without blurring, and a beautiful drawn line can be expressed.
(Triangle | delta): The drawn line is somewhat blurred and the drawn line density is light.
X: The drawn line is severely blurred and the drawn line is ugly.

(Halai evaluation method)
Using each of the water-based ballpoint pens prepared above, the letter “Ei” was written freehand on the writing test paper, and the quality of the fifth stroke was visually evaluated according to the following evaluation criteria.
Evaluation criteria:
○: There are no broken lines, and beautiful lines can be expressed.
Δ: There are some cracks in the drawn lines, and the drawn line density is light.
X: The drawing line is broken and the drawing line is ugly.

(First-stroke performance evaluation method)
Using each of the water-based ballpoint pens prepared above, the character “Ei” was written freehand on the writing test paper, and the state of ink ejection performance at the point of the first stroke was visually evaluated according to the following evaluation criteria.
Evaluation criteria:
○: There is almost no blur and the dots are beautiful.
Δ: Slight blurring and light drawing.
X: Scratch is bad and the points are hardly readable.

(Evaluation method for blurring and blurring of drawn lines)
Using the water-based ballpoint pens prepared above, the character “Ei” was written freehand on the writing test paper, and the condition of the splash at the end of the second stroke was visually evaluated according to the following evaluation criteria.
Evaluation criteria:
○: The drawn line at the end of the brush is very thin, and there is no blur or blurring.
(Triangle | delta): The drawn line is somewhat blurred and the drawn line density is light. Or some blur is recognized.
X: The drawn line is severely blurred or blurred, and the drawn line is ugly.

(Evaluation method for stroke defects)
Using each of the water-based ballpoint pens prepared above, 10 circles having a diameter of about 5 cm were spirally written in a freehand on a writing test paper for 5 seconds, and the deficit state of the drawn lines was evaluated according to the following criteria.
Evaluation criteria:
○: There is no missing part.
Δ: 1 to 3 defects.
X: There are four or more defects.

* 1 to * 9 in Table 1 are as follows.
* 1: Carbon black MA-100 (Mitsubishi Chemical Corporation)
* 2: CAB-O-JET R200 (manufactured by Cabot Japan) 20% active ingredient amount
* 3: JONCRYL 61J (styrene-acrylic dispersant, manufactured by BASF JAPAN) 30% active ingredient
* 4: SMA-1440H (styrene-maleic anhydride dispersant, manufactured by Kawa Crude Chemical Co., Ltd.) 34% active ingredient
* 5: J Poval JF-05 (Nippon Vinegar-Poval), degree of saponification 98-99 mol%, degree of polymerization 500
* 6: K-type Gohsenol KH-17 (manufactured by Nippon Synthetic Chemical Industry), saponification degree 78.5-81.5 mol%, polymerization degree 1700
* 7: L-type Gohsenx L-3266 (manufactured by Nippon Synthetic Chemical Industry), saponification degree 86.5-89.0 mol%, polymerization degree 300
* 8: Phosphate ester RS-610 (manufactured by Toho Chemical Industry Co., Ltd.)
* 9: Best Side 600 (Nippon Soda Co., Ltd.)

Considering Table 1 above, Examples 1 to 9, which are within the scope of the present invention, are clear tome, splash, and fold, have no initial stroke performance, blurring or blurring of drawn lines, and no writing strokes are lost. It turned out that it becomes a water-based ink composition for writing instruments.
On the other hand, it turns out that in Comparative Examples 1-4 which become out of the range of this invention, the effect of this invention cannot be exhibited. In Comparative Examples 1 and 3, the resin dispersion type pigment is contained alone, and in Comparative Examples 2 and 4, the self dispersion type pigment is contained alone. In these cases, the resin dispersion type pigment and the self dispersion type pigment are used. Compared with Examples 1 to 9 of the present invention, the drawn lines were lost, or the drawn lines were blurred or blurred, and the effects of the present invention could not be exhibited.

  A water-based ink composition for a writing instrument suitable for a water-based ballpoint pen can be obtained.

Claims (3)

  A water-based ink composition for a writing instrument, comprising at least one selected from polyvinyl alcohol, boric acid and a salt thereof, or diglyceryl borate, and a resin-dispersed pigment and a self-dispersed pigment.   The water-based ink composition for a writing instrument according to claim 1, wherein the mass ratio of the resin-dispersed pigment / self-dispersed pigment is 1/2 to 5/1.   A writing instrument comprising the aqueous ink composition for a writing instrument according to claim 1 or 2 mounted thereon.