JP2020075962A - Water-based ink composition for writing instrument - Google Patents

Abstract

To provide a water-based ink composition for writing instrument, in which the ink does not solidify even when the pen tip is in a state of exposure for a long period of time, and that has an excellent pen tip drying resistance.SOLUTION: Provided is a water-based ink composition for writing instrument characterized in at least containing carnitine by 0.1 to 10 mass% per total amount of ink composition. Preferably, the carnitine is any of L-carnitine, D-carnitine, a DL-carnitine salt, a DL-carnitine derivative, and a salt thereof.SELECTED DRAWING: None

Description

The present invention relates to a water-based ink composition for writing instruments containing carnitines.

When the pen tip of a writing instrument using an aqueous ink is exposed for a certain period of time, the ink component of the pen tip may be dried and solidified due to evaporation of water, and the writing performance may be deteriorated. As a means for solving the drying with these nibs, an aqueous ink composition containing a dextrin compound (for example, see Patent Document 1) is disclosed.

Although the aqueous ink composition for a writing instrument containing the dextrin of Patent Document 1 is excellent in drying resistance, the effect may not be sufficient in the writing instrument of a specific mode. It is speculated that the dextrin coating formed by volatilization of water has a high fracture strength, and it is considered that the coating cannot be completely destroyed by an underline marker having a large ejection area.

WO98 / 31755

In view of the above-mentioned problems of the prior art, the present invention is intended to solve this, and provides a water-based ink composition for a writing instrument which is excellent in dryness of the nib, regardless of what type of writing instrument is used. The purpose is to do.

The present inventors have conducted intensive studies in view of the above conventional problems, and as a result, by containing a specific amount of carnitines, it was found that an aqueous ink composition for a writing instrument for the above purpose can be obtained, and the present invention is achieved. It was completed.

That is, the present invention resides in the following (1) to (3).
(1) A water-based ink composition for a writing instrument, which contains at least 0.1 to 10% by mass of carnitines with respect to the total amount of the ink composition.
(2) The aqueous ink composition for a writing instrument as described in (1) above, wherein the carnitine is any one of L-carnitine, D-carnitine, a DL-carnitine salt, a DL-carnitine derivative and these salts. ..
(3) A writing instrument comprising the aqueous ink composition for a writing instrument as described in (1) or (2) above.

According to the present invention, there is provided an aqueous ink composition for a writing instrument which has excellent resistance to drying at the nib regardless of the type of the writing instrument.

Hereinafter, embodiments of the present invention will be described in detail.
The aqueous ink composition for a writing instrument of the present invention is characterized by containing at least 0.1 to 10% by mass of carnitines.

Carnitine is a derivative of an amino acid that is biosynthesized from the amino acids lysine and methionine, has a quaternary ammonium in the direct molecular structure, and has a betaine structure.
Examples of carnitines used in the present invention include L-carnitine, which is a basic skeleton, D-carnitine, salts thereof, derivatives thereof, salts of the above derivatives, and the like.

Specific examples of the salt of L (D) -carnitine include tartrate, citrate, succinate, fumarate and hydrochloride.

Specific examples of the L (D) -carnitine derivative include acetylcarnitine, palmitoylcarnitine and lauroylcarnitine.

Specific examples of the salt of the carnitine derivative include glycine propionylcarnitine hydrochloride, acetylcarnitine dihydrochloride, taurine acetylcarnitine hydrochloride and the like.
Among these, it is preferable to use L-carnitine, DL-carnitine hydrochloride, and acetylcarnitine because of their excellent safety, availability, and stability over time in the ink composition.

The content of carnitines needs to be 0.1 to 10% by mass, preferably 0.5 to 8% by mass, and more preferably 1 to 5% by mass, based on the total amount of the ink composition. Is desirable.
If the content is less than 0.1% by mass, a sufficient drying resistance effect cannot be obtained, and conversely, if it exceeds 10% by mass, the effect does not change, which is not preferable.

The aqueous ink composition for a writing instrument of the present invention may contain, in addition to the above-mentioned carnitines, materials constituting the aqueous ink composition for a writing instrument.

As the colorant that can be used in the present invention, all dyes, inorganic and organic pigments that are dissolved or dispersed in water, resin particles colored with a dye or pigment, and the like can be used without limitation.
Examples of the dye include acid dyes, direct dyes and basic dyes.
Examples of inorganic pigments include carbon black and metal powder.
Examples of organic pigments include azo lakes, insoluble azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dye lakes, nitro pigments, and nitroso pigments. Specifically, phthalocyanine blue (C.I.74160), phthalocyanine green (C.I.74260), Hansa yellow 3G (C.I. 11670), disazo yellow GR (C.I. 21100), permanent red 4R. (C.I. 12335), brilliant carmine 6B (C.I. 15850), quinacridone red (C.I. 46500) and the like can be used.
The content of the colorant is preferably about 0.1 to 30% with respect to the total amount of the ink composition.

As the water-soluble solvent that can be used in the present invention, for example, glycols such as ethylene glycol, diethylene glycol, propylene glycol and glycerin, ethylene glycol monomethyl ether and diethylene glycol monomethyl ether can be used alone or in combination. The content of this water-soluble solvent is preferably 5 to 40% of the total amount of the aqueous ink composition for writing instruments.

The aqueous ink composition for a writing instrument of the present invention includes carnitine, a colorant, a water-soluble solvent, and water as a balance solvent (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) A dispersant, a lubricant, a pH adjuster, a rust preventive, an antiseptic, a thickener and the like may be appropriately contained within a range not impairing the effects of the invention.

When a pigment is used, it is preferable to use a dispersant. This dispersant has a function of adsorbing to the surface of the pigment, improving the affinity with water, and stably dispersing the pigment in water, and nonionic, anionic surfactants and water-soluble resins are used. A water-soluble polymer is preferably used.

As the lubricant, nonionic fatty acid esters of polyhydric alcohols, higher fatty acid esters of sugars, polyoxyalkylene higher fatty acid esters, alkyl phosphates, etc., which are also used as surface treatment agents for pigments, and alkyl sulfonic acids of higher fatty acid amides. Examples thereof include salts, anionic systems such as alkylallyl sulfonates, polyalkylene glycol derivatives, fluorochemical surfactants, and polyether-modified silicones.

As the pH adjuster, ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, an alkali metal salt of carbonic acid or phosphoric acid such as sodium carbonate, an alkali metal hydrate such as sodium hydroxide, etc. And so on.

Examples of the rust preventive agent include benzotriazole, tolyltriazole, dicyclohexyl ammonium nitrite, saponins and the like.

Examples of the preservatives include phenol, sodium omazine, sodium benzoate, and thiazoline compounds.

The aqueous ink composition for a writing instrument of the present invention is a homomixer, a homogenizer or a disperser, in which carnitines, a water-soluble solvent, and other components are appropriately combined according to the use of the ink for a writing instrument (for ballpoint pen, marking pen, etc.). An aqueous ink composition for a writing instrument can be prepared by stirring and mixing with a stirrer such as the above, and further removing coarse particles in the ink composition by filtration or centrifugation if necessary.

The pH (25 ° C.) of the aqueous ink composition for a writing instrument of the present invention is 5 to 10 depending on a pH adjuster or the like from the viewpoints of usability, safety, stability of the ink itself, and matching property with a member constituting the writing instrument. It is preferable to adjust to, and more preferably 6 to 9.5.

The aqueous ink composition for a writing instrument of the present invention is mounted on a ballpoint pen having a pen tip portion such as a ballpoint pen tip, a fiber tip, a felt tip, and a plastic tip, a marking pen, and the like.

The ballpoint pen of the present invention contains the aqueous ink composition for a writing instrument of the above composition in an ink container for a ballpoint pen (refill), and is incompatible with the aqueous ink composition housed in the ink container, and A substance having a small specific gravity with respect to the water-based ink composition, such as polybutene, silicone oil, or mineral oil, is contained as an ink follower.

Examples of the marking pen according to the present invention include one in which the aqueous ink composition for a writing instrument having the above composition is housed in a porous body called an ink storage body, and various writing members are connected to the tip thereof.

The structure of the ball-point pen and the marking pen is not particularly limited, and for example, a collector structure (ink holding mechanism) in which the shaft cylinder itself is used as an ink container and the water-based ink composition for a writing instrument having the above-described structure is filled therein is used. It may be a direct liquid type ballpoint pen or a marking pen provided.

In the water-based ink composition for a writing instrument of the present invention configured as described above, by containing carnitine in an amount of 0.1 to 10% by mass based on the total amount of the ink composition, dry-up with a pen tip is performed. Thus, a water-based ink composition for a writing instrument, which is suppressed and has excellent resistance to drying the nib, can be obtained.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples and the like.

(Colorant 1)
A 2 liter flask was equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen gas inlet tube, and a 1000 ml separatory funnel for charging a monomer, which was set in a warm water tank, and 500 g of distilled water and a polymerizable surfactant [manufactured by ADEKA CORPORATION "Adecaria Soap SE-10N"] 50 g and ammonium persulfate 3 g were charged, and the internal temperature was raised to 50 ° C while introducing nitrogen gas.

On the other hand, in 500 g of a mixed monomer consisting of 300 g of 2-methacryloyloxyethyl phthalate (acrylic ester PA manufactured by Mitsubishi Rayon Co., Ltd.) and 200 g of n-butyl methacrylate, a water-soluble basic dye [Hodogaya Chemical Industry ( Co., Ltd., "AIZEN CATHILON RED BLH 200%"] was mixed to prepare a liquid.
This prepared liquid was added from the separating funnel to the flask kept at a temperature of about 50 ° C. for 3 hours with stirring to carry out emulsion polymerization. After further aging for 5 hours to complete the polymerization, a dispersion liquid of colored resin fine particles for aqueous ink (colorant 1: solid content 40% by mass) was obtained.

[Examples 1-10 and Comparative Examples 1-2]
It was prepared by mixing and stirring a predetermined amount of the aqueous ink composition for each writing instrument with the composition shown in Table 1 below, specifically, the composition such as coloring agent and carnitine, and filtering with a 10 μm bag filter.

With respect to the water-based ink compositions for writing instruments obtained in Examples 1 to 10 and Comparative Examples 1 and 2, water-based ballpoint pens and marking pens were prepared by the following method, and the nib dry resistance was evaluated by the following evaluation method. It was
The results are shown in Table 1 below.

(Preparation of water-based ballpoint pen)
An aqueous ballpoint pen was produced using each of the ink compositions obtained above. Specifically, using a ball-point pen [Mitsubishi Pencil Co., Ltd., trade name: CIGNO UM-100], an inner diameter of 4.0 mm, a length of 113 mm, an ink container made of polypropylene and a stainless steel tip (a cemented carbide ball, A ball refill having a ball diameter of 0.7 mm) and a joint connecting the containing tube and the tip is filled with each of the above water-based inks, and an ink follower containing mineral oil as a main component is loaded at the rear end of the ink to prepare an water-based ballpoint pen. did.

(Creating a marking pen)
A marking pen was produced using each of the ink compositions obtained above. Specifically, a marking pen (manufactured by Mitsubishi Pencil Co., Ltd., trade name: Propas Window PUS-102T, pen point, thick: sintered PE resin core, fine: PET fiber core) is loaded with each of the above aqueous ink compositions. Then, a marking pen was produced.

[Evaluation method of pen tip dry resistance]
Under a condition of 25 ° C. and 60% RH, each pen was left sideways for 1 month with the cap removed, and then a straight line was written on a writing paper conforming to the ISO standard and evaluated according to the following evaluation criteria.
Evaluation criteria:
A: You can write without problems from the beginning.
B: The line density at the beginning of writing was low, but it returned immediately.
C: Cannot write

As is clear from the results of Table 1 above, the aqueous ink compositions for a writing instrument of Examples 1 to 10 according to the present invention have a higher nib dry resistance than Comparative Examples 1 and 2 which are outside the scope of the present invention. It turned out to be excellent.

A water-based ink composition for a writing instrument suitable for a writing instrument such as an aqueous ball-point pen or marking pen can be obtained.

Claims (3)

A water-based ink composition for a writing instrument, which contains at least 0.1 to 10% by mass of carnitines with respect to the total amount of the ink composition. The aqueous ink composition for a writing instrument according to claim 1, wherein the carnitine is any one of L-carnitine, D-carnitine, a salt of DL-carnitine, a DL-carnitine derivative and salts thereof. A writing instrument comprising the aqueous ink composition for a writing instrument according to claim 1 or 2.