JP2020139086A - Aqueous ink composition for writing instruments, and writing instrument using the same - Google Patents

Abstract

To provide an aqueous ink composition for writing instruments that has excellent handwriting water resistance and handwriting fixability while having excellent dry-up resistance, and a writing instrument using the same.SOLUTION: An aqueous ink composition for writing instruments contains a polyester resin, α glucan or an α glucan derivative, a colorant, and water. There is also provided a writing instrument using the same.SELECTED DRAWING: None

Description

The present invention relates to a water-based ink composition for a writing instrument and a writing instrument using the same.

When the pen tip of a writing instrument is exposed to the atmosphere for a while, the solvent in the ink contained in the writing instrument body evaporates from the pen tip, and the ink dries and solidifies, causing the writing marks to fade. In some cases, it became impossible to use it as a writing instrument, such as being unable to write. Therefore, in a water-based ink composition for a writing instrument and a writing instrument using the same, it is an issue to prevent the ink from drying and to obtain excellent dry-up resistance.
Therefore, in order to solve the above problems, an ink composition having improved dry-up resistance by adding a polyhydric alcohol solvent such as ethylene glycol or glycerin and various moisturizers such as urea or a urea derivative has been proposed. Has been done. (Patent Documents 1, 2, etc.)
However, depending on the type of moisturizer to be added and the amount of the moisturizer added, good dry-up resistance can be obtained, but if water droplets adhere to the obtained handwriting, the handwriting will be blurred and it will be difficult to see the handwriting. In addition, the fixability of the handwriting to the writing surface is lowered, and when the handwriting is scratched, the handwriting may become dirty, which may cause problems in the water resistance and fixability of the handwriting.
Therefore, there is a demand for a water-based ink composition for writing instruments and a writing instrument that can obtain excellent handwriting water resistance and handwriting fixability while having excellent dry-up resistance.

Japanese Unexamined Patent Publication No. 8-127746 Japanese Unexamined Patent Publication No. 2004-217730

An object of the present invention is to solve the above-mentioned problems, to provide a water-based ink composition for writing instruments having excellent dry-up resistance, handwriting water resistance, and handwriting fixability, and further. , To provide a writing instrument using it.

In order to solve the above problems, the present invention
"1. A water-based ink composition for writing instruments, which comprises a polyester resin, an α-glucan or an α-glucan derivative, a colorant, and water.
2. 2. The water-based ink composition for writing instruments according to item 1, wherein the polyester resin is a saturated copolymerized polyester resin.
3. 3. The water-based ink composition for writing instruments according to item 1 or 2, wherein the α-glucan or α-glucan derivative is α1,4-1,6 glucan or α1,4-1,6 glucan derivative.
4. The writing instrument according to any one of items 1 to 3, wherein the content of the polyester resin is 0.001% by mass to 5% by mass based on the total mass of the water-based ink composition for writing instruments. Water-based ink composition.
5. Item 1 of Item 1 to Item 4, wherein the content of the α-glucan or the α-glucan derivative is 0.001% by mass to 1% by mass based on the total mass of the water-based ink composition for writing instruments. A water-based ink composition for writing instruments according to.
6. A writing instrument comprising the water-based ink composition for a writing instrument according to any one of paragraphs 1 to 5. ".

According to the present invention, even if the pen tip is exposed to the atmosphere for a while, it is possible to form a better handwriting than at the beginning of writing, and the obtained handwriting is less likely to bleed even when water droplets adhere to it. A water-based ink composition for writing instruments with excellent dry-up resistance, handwriting water resistance, and handwriting fixability, which produces handwriting with excellent water resistance and fixability that does not easily get dirty even when rubbed, and writing instruments using the same. Can be provided.

Hereinafter, embodiments of the present invention will be described in detail. In the present specification, "part", "%", "ratio", etc. indicating the composition are based on mass unless otherwise specified, and the content rate is a constituent component based on the mass of the ink composition. Is the mass% of.

<Aqueous ink composition for writing instruments>
The water-based ink composition for writing instruments according to the present invention (hereinafter, referred to as an ink composition in some cases) is characterized by containing a polyester resin, an α-glucan or an α-glucan derivative, a colorant, and water. Is what you do.
In the present invention, it is important to use an α-glucan or an α-glucan derivative in combination with a polyester resin, and by using these in combination, excellent dry-up resistance, excellent handwriting water resistance and handwriting fixing property are exhibited. Can be done.
This is because the excellent film-forming ability of polyester resin and the excellent water-retaining ability and film-forming ability of α-glucan or α-glucan derivative are used to form a film with water-retaining ability and moderate flexibility on the pen tip. It is considered that this is because the film can sufficiently suppress the evaporation of water from the pen tip. Further, it is considered that a film is formed on the surface of the obtained handwriting, the handwriting is firmly fixed on the writing surface by the film, and the handwriting is imparted with water resistance by the film.
Therefore, the ink composition of the present invention and the writing instrument using the same can leave a good handwriting resistance because the ink is hard to dry and solidify even when the pen tip is left in an air-exposed state for a while. It has excellent dry-up performance. Further, the obtained handwriting is hard to bleed even when water droplets or the like are attached, and the handwriting is hard to be soiled even if it is rubbed, and the handwriting is excellent in water resistance and handwriting fixability.
From the above, the ink composition of the present invention is satisfactory in all of the contradictory performances of dry-up resistance, handwriting water resistance, and handwriting fixability.
Further, by using the polyester resin and the α-glucan or the α-glucan derivative, the addition amount of each can be reduced due to the synergistic effect, so that the ink viscosity can be suppressed low. Therefore, it is easy to adjust the ink viscosity to a desired value for the writing instrument to be used, stable ink ejection property can be obtained while maintaining excellent dry-up resistance, and good handwriting can be left.
Hereinafter, the constituent components of the ink composition of the present invention will be described in detail.

<Polyester resin>
Polyester resin is a polymer having an ester bond in its structure.
The polyester resin can form a film having excellent water resistance and fixability, can form a film on the pen tip, and can effectively suppress water evaporation from the pen tip.
In addition, the film formed on the pen tip becomes moderately flexible with water retention ability by using α-glucan or α-glucan derivative in combination. Therefore, the coating film can sustainably and sufficiently suppress the evaporation of water, but can be easily destroyed by the impact of writing at the time of writing. Therefore, good ink ejection property can be obtained from the beginning of writing, good handwriting can be left, and excellent dry-up resistance can be achieved.
In addition, the polyester resin can also form a film on the surface of the obtained handwriting. The coating firmly fixes the colorant on the writing surface, and the resulting handwriting is less likely to be soiled even if scratched. In addition, since the film imparts water resistance to the handwriting, even if water droplets adhere to the handwriting later, the outflow of the colorant can be prevented and the handwriting bleeding can be suppressed. Therefore, the ink composition of the present invention has excellent handwriting fixability and handwriting water resistance.

The polyester resin in the present invention is not particularly limited as long as it is a polymer having an ester bond, but in the present invention, the polyester resin is preferably a saturated copolymerized polyester resin, and has excellent dry-up resistance and brush fixing. It is possible to obtain properties and handwriting water resistance. Further, from the viewpoint of the stability of the ink over time, it is preferable to use a saturated copolymerized polyester resin which does not contain a double bond in the structure.
Furthermore, a saturated copolymerized polyester resin containing terephthalic acid as a main component is more preferable.

Further, in the present invention, considering that the polyester resin is stably present in the ink, has excellent stability over time, and the effect of the polyester resin can be sufficiently and efficiently obtained, the polyester resin has a hydrophilic group. preferable.
Examples of the hydrophilic group include a COOH group (carboxyl group), an SO ₃ Na group (sodium sulfonate group), and an OH group (hydroxy group). In the present invention, it is preferable to use a polyester resin having an SO ₃ Na group (sodium sulfonate group), which has excellent dry-up resistance, excellent handwriting water resistance and handwriting fixability.

The weight average molecular weight of the polyester resin is preferably 1000 to 30000, and more preferably 1000 to 30000. Considering that the handwriting fixability is further improved while having excellent dry-up resistance, it is more preferably 1000 to 20000, and particularly preferably 1500 to 20000. This means that if the weight average molecular weight is within the above numerical range, a strong film that can suppress water evaporation can be formed on the pen tip, and a strong film that is not easily scraped even if scratched can be formed on the handwriting surface. I guess it's because.

The softening point of the polyester resin is preferably 70 ° C. to 250 ° C., more preferably 80 ° C. to 200 ° C. Considering further improvement in handwriting water resistance while being excellent in dry-up resistance, it is more preferably 100 ° C to 180 ° C, particularly preferably 100 ° C to 150 ° C, and 105 ° C to 130 ° C. Is most preferable.

The minimum film-forming temperature (Tg) of the polyester resin is preferably −30 ° C. to 120 ° C., more preferably 0 ° C. to 120 ° C., and even more preferably 30 ° C. to 70 ° C. , 40 ° C. to 55 ° C. is particularly preferable.

Examples of polyester resins include the Plus Coat series manufactured by GOO CHEMICAL CO., LTD.

The content of the polyester resin in the ink composition of the present invention is preferably 0.001 to 5% by mass based on the total mass of the ink composition. If it is 0.001% by mass or more, both the effect of suppressing water evaporation by forming a film on the pen tip and the effect of imparting fixability to the handwriting and imparting water resistance by forming a film on the surface of the handwriting can be obtained. Cheap. This is because when it is 5% by mass or less, the solubility in the ink is stable and the effect brought about by the polyether ester resin can be easily obtained. Further, it is more preferably 0.005 to 1% by mass. This can sufficiently obtain the excellent film forming effect of the polyester resin without affecting the stability over time of the ink, and can impart excellent dry-up resistance, handwriting water resistance, and handwriting fixability to the ink composition. This is because the viscosity of the ink composition can be kept low, excellent ink ejection properties can be maintained, and good handwriting can be left. Further, considering that the dry-up resistance, the water resistance of the handwriting and the fixing property of the handwriting are improved in a well-balanced manner, it is more preferably 0.01 to 0.5% by mass, and 0.03 to 0.1% by mass. Is particularly preferable.
The polyester resin can also be used as one kind or a mixture of two or more kinds.

<Alpha glucan or α glucan derivative>
α-glucan is a polymer in which a large number of glucoses are linked by α-bonds, and is classified into α1,3 glucans, α1,4 glucans, α1,6 glucans, α1,4-1,6 glucans, etc. depending on the binding mode. Glucan.
Specifically, α1,3 glucan includes mutan, α1,4 glucan includes amylose, α1,6 glucan includes dextran, and α1,4-1,6 glucan includes glycogen, amylopectin, and pullulan.
The α-glucan derivative is not limited as long as it is a substance derived from α-glucan obtained by chemically modifying the above-mentioned α-glucan.

The α-glucan or α-glucan derivative has an excellent water-retaining ability and further has a film-forming property. Since the α-glucan or the α-glucan derivative has an excellent water-retaining power, it can effectively act as a moisturizer and suppress the drying and solidification of the ink at the pen tip.
In addition, since α-glucan or α-glucan derivative also has film-forming properties, it also has the effect of forming a film on the pen tip and suppressing water evaporation. However, when used in combination with a polyester resin, the film becomes more water-forming. A film having a high evaporation suppressing effect and excellent durability can be obtained.
Therefore, the ink composition of the present invention using the polyester resin and α-glucan or α-glucan derivative has water retention at the pen tip and can sufficiently suppress water evaporation, but at the time of writing, it is written. It is possible to form a film that can be easily broken by the impact of.
Therefore, the ink composition of the present invention can obtain better ink ejection property than at the time of writing even when the pen tip is exposed to the atmosphere in an environment where the pen tip is in a strong dry state for a long period of time, and the handwriting can be obtained. It can leave good handwriting without blurring and has excellent dry-up resistance.
Further, the α-glucan or the α-glucan derivative does not adversely affect the film-forming property of the polyester resin on the handwriting surface, and forms a good film together with the polyester resin. Therefore, it is possible to provide excellent handwriting water resistance and handwriting fixability while obtaining excellent dry-up resistance.

The α-glucan or α-glucan derivative used in the present invention is not particularly limited, but in the present invention, it is preferably α1,4-1,6 glucan or α1,4-1,6 glucan derivative. , Excellent dry-up resistance, handwriting fixability, and handwriting water resistance can be obtained.
Further, considering the improvement of the above effects, it is preferable to use pullulan and pullulan derivatives.

Pullulan has maltotriose as a constituent unit in which three molecules of glucose are linked by α-1,4 bonds as shown by the following formula (1), and maltotrioses are linked via α-1,6 bonds. It is a water-soluble high molecular weight polysaccharide having a structure. It is a compound that is easily dissolved in water and is non-toxic, non-irritating, tasteless and odorless to the human body. Although the origin and production method of pullulan are not limited, a method of culturing a microorganism capable of producing pullulan and collecting the pullulan-containing substance from the culture is usually preferably used. Examples of such microorganisms include aureobasidium pulllance.

式中、ｎは整数を表す。

In the formula, n represents an integer.

The pullulan derivative is not limited as long as it is a substance derived from pullulan obtained by chemically modifying the pullulan. Examples thereof include dialaldehyde pullulan, aminoalkylated pullulan, carboxylated pullulan, crosslinked pullulan, sulfate ester derivatives of pullulan, and pullulan-sterol derivatives such as cholesterol pullulan.

The average molecular weight of the pullulan is excellent in terms of stability over time in the ink composition, and while sufficiently exhibiting a water retention effect, it can form a good film together with the polyester resin and effectively suppress water evaporation. The one having an average molecular weight of 5,000 to 500,000 is preferable, and one having an average molecular weight of 50,000 to 400,000 is more preferably used.

Further, as the plan derivative, a pullulan-sterol derivative is preferable, and it is more preferable to use a pullulan-cholesterol derivative which is a compound obtained by introducing cholesterol into a chemical bond into pullulan. It is considered that this is because the pullulan-cholesterol derivative is easily adsorbed on a metal or synthetic resin and easily forms a good film on the pen tip. Further, considering the availability and the stability of the compound over time, the pullulan-cholesterol derivative is preferably cholesteryl pullulan hexyldicarbamic acid (cholesterol pullulan), which is a compound obtained by adding cholesterol to pullulan with hexamethylene diisocyanate. .. Examples of the cholesteryl pullulan hexyl dicarbamate include compounds represented by the following formula (2), and excellent dry-up resistance can be obtained by using cholesteryl pullulan hexyl dicarbamic acid.

式中、ｎは整数を表す。

In the formula, n represents an integer.

Therefore, in the present invention, pullulan or cholesteryl pullulan hexyldicarbamate (cholesterol pullulan), which can easily obtain excellent dry-up resistance, excellent handwriting fixing property and handwriting water resistance, is preferably used.

As examples of commercially available pullulan, for example, pharmaceutical grade pullulan manufactured by Hayashibara Co., Ltd. (trade name "Japanese Pharmacy Pullulan"), cosmetic grade pullulan (trade name "cosmetic pullulan") and food additives Examples thereof include physical grade pullulan (trade name “food additive pullulan”), which can be preferably used.

Further, as an example of a commercially available product containing cholesteryl pullulan hexyldicarbamic acid (cholesterol pullulan), Meduseeds series (manufactured by NOF CORPORATION) and the like can be mentioned, and specifically, Meduseds-C1 and Meduseeds. -CP and the like can be mentioned. The Meduseeds-CP contains cholesteryl pullulan hexyldicarbamic acid, water, butylene glycol, methylparaben, and phenoxyethanol.

The content of α-glucan or α-glucan derivative in the ink composition of the present invention is preferably 0.001 to 1% by mass based on the total mass of the ink composition. If it is 0.001% by mass or more, sufficient water retention and film-forming ability of α-glucan or α-glucan derivative can be obtained, and excellent dry-up resistance can be easily obtained. If it is 1% by mass or less, it is in the ink. The solubility in the pen is stable, and good ink ejection property from the pen tip is maintained, and it is easy to leave a good handwriting. Further, it is more preferably 0.005 to 0.5% by mass, and particularly preferably 0.01 to 0.1% by mass.
The α-glucan or α-glucan derivative can also be used as one kind or a mixture of two or more kinds.

Further, in the ink composition of the present invention, the content ratio of the polyester resin (polyester resin / α-glucan or α-glucan derivative) to the α-glucan or α-glucan derivative may be 0.1 to 20 times based on the mass. preferable. Further, it is more preferably 0.1 to 5 times, and particularly preferably 0.5 to 2 times. This is because when the content ratio is within the above numerical range, the film formed on the pen tip is likely to be a film that can sufficiently obtain the effect of suppressing water evaporation, but is easily broken at the time of writing. Further, the film formed on the surface of the handwriting also tends to sufficiently impart excellent handwriting fixing property and handwriting water resistance.
Therefore, dry-up resistance, handwriting water resistance, and handwriting fixability can be improved in a well-balanced manner.

<Colorant>
The colorant used in the present invention is not particularly limited, but pigments, dyes and the like used in the water-based ink composition for writing instruments can be used.

The pigment is not particularly limited as long as it can be dispersed in a solvent. For example, inorganic pigments, organic pigments, processed pigments, etc. are mentioned, and specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, and slene. Examples thereof include system, triphenylmethane type, perinone type, perylene type, dioxazine type, aluminum pigment, pearl pigment, fluorescent pigment, phosphorescent pigment and the like. In addition, colored resin particles obtained by coloring resin particles with a dye or the like, or a colored body obtained by dispersing a coloring material in a medium are encapsulated in a shell made of a resin wall film forming substance by a known microencapsulation method or the like. A solid-solubilized microcapsule pigment may be used.
As the pigment, an aqueous dispersion pigment product or the like finely and stably dispersed in an aqueous medium using a pigment dispersant may be used. Examples of the pigment dispersant include water-soluble resins, nonionic surfactants, anionic surfactants, and cationic surfactants.
Further, a self-dispersing pigment that can be dispersed in an aqueous medium without using a pigment dispersant can also be used.

The dye is not particularly limited as long as it can be dissolved in a solvent. For example, direct dyes, acid dyes, basic dyes, gold-containing dyes, various salt-forming type dyes, and the like can be adopted.
These pigments and dyes may be used as one or a mixture of two or more.

In the present invention, it is preferable to use a pigment. It is possible to leave a handwriting with excellent color development and a handwriting with even better water resistance.
However, unlike dyes, pigments are dispersed in ink in an insoluble state. Therefore, when a pigment is used, if the pen tip is exposed to the atmosphere for a while and the ink dries and solidifies, and the pen tip and the ink flow path are clogged, the ink that is followed later causes this. It is very difficult to clear the clogging, and there is a high possibility that you will not be able to write even though there is ink remaining. Therefore, the ink using the pigment needs to have particularly excellent dry-up resistance. As described above, by using the polyester resin in combination with α-glucan or α-glucan derivative, it is possible to suppress the evaporation of water in the ink and prevent the ink from drying and solidifying. Therefore, in the present invention, even when a pigment is used, the dry-up resistance is excellent, and therefore, using a pigment in the present invention is particularly effective.

Further, in the present invention, when a pigment is used, a self-dispersing pigment is preferably used.
The self-dispersing pigment means a pigment that can be dispersed in an aqueous medium without using a pigment dispersant for dispersing the pigment. For example, the pigment is physically or chemically treated. Therefore, those having a hydrophilic functional group (hydrophilic group) on the surface of the pigment can be mentioned.
Since the self-dispersing pigment does not contain a dispersant component, it is easy to obtain handwriting with good color development. However, on the other hand, it also has an aspect that is difficult to firmly settle on the writing surface. For this reason, when the handwriting is rubbed, the handwriting becomes dirty, and when water droplets adhere to the obtained handwriting, the handwriting is blurred, and problems tend to occur in the handwriting water resistance and the handwriting fixability.
The ink composition of the present invention can impart excellent water resistance and fixability by forming a film on the handwriting and firmly fixing the colorant on the writing surface. Therefore, in the present invention, the use of a self-dispersing pigment is effective because it can leave a handwriting having excellent water resistance and fixability while having excellent color development.
Further, the self-dispersing pigment does not adversely affect the film of the pen tip formed of the polyester resin and the α-glucan or the α-glucan derivative. Therefore, it is easy to maintain the excellent dry-up resistance obtained by the coating film, and therefore, in the present invention, it is most effective to use the self-dispersing pigment.
Further, by using the self-dispersing pigment, the dispersion stability of the ink can be improved, excellent ink ejection property can be obtained, and it is easy to leave a uniform and good handwriting. From this point as well, the self-dispersing pigment can be used. It is effective to use.

Further, in the present invention, it is preferable to use an anionic self-dispersing pigment as the self-dispersing pigment. The reason for this is not clear, but the polyester resin used in the present invention tends to form an excellent film on the surface of the anionic self-dispersing pigment, further providing water resistance and fixability to the handwriting. This is because it is easy to give.
Further, as will be described later, the ink composition of the present invention may be used for a writing instrument using a fiber tip, a felt tip, or a plastic tip for a pen tip, or a writing instrument using a comb groove structure for an ink flow rate adjusting body. It is easy to adjust to low-viscosity inks and even ultra-low-viscosity inks, but in this case, using self-dispersing pigments is more effective. Since the self-dispersing pigment can improve the dispersibility without using a pigment dispersant, the ink viscosity can be suppressed to a lower level, good ink ejection property can be obtained from the beginning of writing, and a uniform and good handwriting is left. Because it is easy.

The self-dispersing pigment that can be used in the present invention is not particularly limited. For example, commercially available products include Microjet series manufactured by Orient Chemical Industry Co., Ltd., CAB-O-JET series manufactured by Cabot Corporation, and Tokai. Examples include the Aqua-Black series manufactured by Carbon Co., Ltd. and the Fuji-JET Black series manufactured by Fuji Pigment Co., Ltd.

The content of the colorant in the ink composition of the present invention is preferably 0.1 to 30% by mass, more preferably 0.1 to 10% by mass, based on the total mass of the ink composition. preferable.

<Water>
The water is not particularly limited, and for example, tap water, ion-exchanged water, ultrafiltered water, distilled water, or the like can be used.

<Other additives>
The ink composition of the present invention may contain any additive, if necessary. The additives that can be used will be described below.

In the present invention, it is preferable that the water-soluble organic solvent is further contained. As the water-soluble organic solvent, those used in conventional water-based ink compositions for writing instruments can be used.
For example, (i) glycols such as ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, (ii) methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol. , Propagil alcohol, allyl alcohol, 3-methyl-1-butin-3-ol, ethylene glycol monomethyl ether, alcohols such as acetate and other higher alcohols, and (iii) ethylene glycol monomethyl ether, ethylene glycol monoethyl ether. , 3-methoxybutanol, or glycol ethers such as 3-methoxy-3-methylbutanol. These can be used as one kind or a mixture of two or more kinds.

In the present invention, among the water-soluble organic solvents, it is preferable to use a polyhydric alcohol solvent, and the dry-up resistance can be further improved. This is because the moisture absorbing effect of the polyhydric alcohol solvent can be imparted to the ink composition, and evaporation suppression by forming a film having a water-retaining ability of the polyester resin and α-glucan or α-glucan derivative and polyhydric alcohol This is because the synergistic effect of suppressing evaporation due to the moisture absorption effect of the solvent can effectively suppress the evaporation of water in the ink from the pen tip. Therefore, even if the pen tip is exposed to the atmosphere for a long period of time or in an environment where the dry state is particularly strong, the ink is smoothly ejected from the writing and a uniform handwriting without blurring can be left. Further, it can be suitably used for a writing instrument such as a haunting writing instrument, which will be described later, in particular, which needs to be considered in terms of dry-up resistance.

Further, among the polyhydric alcohol solvents, it is preferable to select and use one or more from ethylene glycol, diethylene glycol, butylene glycol and glycerin, and in consideration of improvement of handwriting water resistance and handwriting fixability, diethylene glycol and glycerin Is more preferable, and diethylene glycol is particularly preferable.

The content of the water-soluble organic solvent is preferably 0.1 to 40% by mass based on the total mass of the ink composition.
Considering that dry-up resistance, handwriting water resistance, and handwriting fixability are improved in a well-balanced manner, the content is preferably 0.5 to 40% by mass, more preferably 0.5 to 10% by mass, 1 It is more preferably ~ 5% by mass.

In addition, the ink composition of the present invention may contain various additives such as a pH adjuster, a rust preventive, a preservative, a chelating agent, and a moisturizer for the purpose of improving the physical properties and functions of the ink.

Examples of the pH adjuster include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate and sodium hydroxide, basic organic compounds such as sodium acetate, triethanolamine and diethanolamine, lactic acid and citric acid, and inks. Considering the stability over time of the composition, it is preferable to use a basic organic compound, and more considering it, it is preferable to use triethanolamine which is weakly basic. These pH adjusters may be used as one type or a mixture of two or more types.

The pH value of the ink composition is preferably 11 or less. This is because when the pH value is 11 or less, the stability of the polyester resin and the α-glucan and the α-glucan derivative with time can be easily obtained, and the effects of these can be sufficiently obtained. Further, considering the improvement of the stability of the ink composition over time and the suppression of corrosion of the metal member with which the ink composition comes into contact, the pH value is preferably 6 or more, and therefore the pH value of the ink composition is set to 6. It is more preferably 6 to 11, and even more preferably 7 to 10. In the present invention, the pH value indicates a value measured at 20 ° C. using an HM-30R type pH meter.

Preservatives include phenol, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, 2-pyridinethiol-1- Examples thereof include sodium oxide, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, orthophenylphenol or a salt thereof. ..

Examples of the rust preventive include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrate, diisopropylammonium nitrate, sodium thiosulfate, saponin, dialkylthiourea and the like.

Examples of the chelating agent include ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), glycol etherdiaminetetraacetic acid (GEDTA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), and dihydroxyethylglycine (DHEG). ), Diethylenetriaminetetraacetic acid (DTPA), triethylenetetraminehexacetic acid (TTHA) and alkali metal salts, ammonium salts or amine salts thereof.

In the present invention, a moisturizer other than α-glucan, α-glucan derivative, and polyhydric alcohol solvent may be further contained. For example, N, N, N-trialkyl amino acids such as urea, sorbitol, dextrin, and trimethylglycine, hyaluronic acids, and the like can be preferably used.
Since N, N, N-trialkylamino acids have high hygroscopicity, even better dry-up resistance can be obtained by using a polyester resin in combination with α-glucan or α-glucan derivative. Further, while maintaining excellent dry-up resistance, it is easy to adjust as a low-viscosity ink composition or ultra-low-viscosity ink as described later, and it is also easy to improve handwriting fixability. Therefore, in the present invention, it is particularly effective to further contain N, N, N-trialkyl amino acids.

As R _{1 to} R ₃ in the formula (3), a linear or branched alkyl group can be widely used. That is, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group and the like are exemplified. Note that R _{1 to} R ₃ may be the same or different.
Specific examples thereof include n = 1 trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, n = 2 trimethyl-β-alanine, and n = 3 trimethyl-γ-aminobutyric acid.
It is preferable to use trimethylglycine in consideration of improvement in dry-up resistance and storage stability of the ink composition.

Further, as the resin emulsion, an emulsion containing an acrylic resin, a urethane resin, a styrene-butadiene resin, a polyester resin, a vinyl acetate resin, or the like can be added.

Furthermore, nonionic surfactants, anionic surfactants, cationic surfactants, surfactants having an acetylene bond in the structure, silicone-based surfactants, fluorine-based surfactants, etc. may be added. it can.
Since these improve the wettability to the ink storage body and the ink flow rate adjusting body, good handwriting can be obtained by smooth ink ejection.
It is also possible to add an antifoaming agent such as dimethylpolysiloxane. Further, a lubricant such as a phosphoric acid ester-based surfactant or a fatty acid can also be added.
Further, in the present invention, a shear thinning agent can be added to impart appropriate viscosity to the ink for practical use. The shear thinning agent used can be appropriately selected from conventionally known agents. Specific examples thereof include polysaccharides such as xanthan gum, succinoglycan and carrageenan, synthetic polymer nonionic surfactants such as polyacrylic acid, crosslinked polyacrylic acid and associative urethane, and anionic surfactants. It can be used as one kind or a mixture of two or more kinds.

<Manufacturing method of ink composition>
The ink composition according to the present invention can be produced by any conventionally known method. Specifically, the required amounts of each of the above components are blended and mixed with various stirrs such as a magnet hot stirrer, a propeller stirrer, a homogenizer stirrer, a homodisper, a homomixer, and a planetary stirrer, and various dispersers such as a bead mill. , Can be manufactured.

<Writing instruments>
The structure and shape of the writing instrument itself for filling the water-based ink composition for writing instruments of the present invention is not particularly limited, and conventional general-purpose ones can be applied, and marking using a fiber tip, a felt tip, or a plastic tip as a pen tip. It can be used for various writing instruments such as a pen (sign pen), a ballpoint pen with a ballpoint pen tip as a pen tip, and a fountain pen with a metal pen tip.

As the material of the pen tip of the writing tool, for ballpoint pens and fountain pens, metals such as superhard alloys, stainless steel and gold, and ceramics such as silicon carbide can be exemplified, and for marking pens (sign-tip pens), polyester, nylon, polyurethane, polyethylene, etc. Examples thereof include synthetic resins such as polypropylene and acrylic.
The ink composition of the present invention containing a polyester resin and an α-glucan or an α-glucan derivative tends to be easily adsorbed on a metal for unknown reasons. Therefore, a film is easily formed on the pen tip made of metal, and the film is easily maintained over time. Therefore, the ink composition of the present invention can be suitably used for writing instruments in which the material of the pen tip is metal, and excellent dry-up resistance can be obtained.
Further, the polyester resin and the α-glucan or the α-glucan derivative have good film forming properties on metals such as stainless steel, gold-plated stainless steel, 14-karat gold, 18-karat gold, and 22-karat gold, and improve dry-up resistance. Easy to make. Therefore, it is effective to use the ink composition of the present invention for a writing instrument using the above metal.
Fountain pens often have a nib made of the above metal. Further, as compared with other writing instruments, the pen tip is exposed to the outside air, the ink of the pen tip is easily evaporated, and it is necessary to improve the dry-up resistance of the pen tip. Since the ink composition of the present invention works effectively on a pen tip made of metal as described above and can impart excellent dry-up resistance, it is particularly recommended to use the ink composition of the present invention for a fountain pen. It is effective and suitable.

Further, the writing instrument on which the ink composition of the present invention can be used may have a structure in which the ink composition is directly filled, and an ink container or an ink occlusion capable of filling the ink composition. It may have a body. Further, the ink container or the ink storage body may be an ink cartridge type writing instrument and a converter type writing instrument having a structure that can be detachably replaced with the writing instrument main body.

In addition, writing instruments that can use the ink composition of the present invention include cap-type writing instruments having a cap that covers the pen tip, and infestations that can accommodate the pen tip in a shaft cylinder such as a knock type, a rotary type, or a slide type. A type writing instrument can be mentioned.
Since the ink composition of the present invention containing a polyester resin and an α-glucan or an α-glucan derivative has excellent dry-up resistance, it can be used as a haunting writing instrument in which the pen tip is constantly exposed to the atmosphere. It can be preferably used.

Further, the supply mechanism of the writing tool to which the ink composition of the present invention can be used is not particularly limited, and for example, an ink guide portion made of (mechanism 1) a fiber convergent or the like is provided as an ink flow rate adjusting member. A mechanism for supplying the ink composition to the pen tip, (mechanism 2) a mechanism for supplying the ink composition to the pen tip by interposing a comb groove-shaped ink flow rate adjusting member, and (mechanism 3) ink by a valve mechanism. Examples thereof include a mechanism provided with a flow rate adjusting member and supplying the ink composition to the pen tip, and (mechanism 4) a mechanism for directly supplying the ink composition to the pen tip without the ink flow rate adjusting member.
In particular, the ink composition of the present invention containing a polyester resin and an α-glucan or an α-glucan derivative has an ink viscosity of 50 mPa · s or less at a shear rate of 380 sec ^-1 while maintaining excellent dry-up resistance. Since it is possible to adjust not only such a low-viscosity ink composition but also an ultra-low-viscosity ink composition having a shear rate of 380 sec ^-1 of 2 mPa · s or less, the ink viscosity is high due to the characteristics of the supply mechanism. It can be suitably used for a writing tool provided with the supply mechanisms of (Mechanism 1), (Mechanism 2), and (Mechanism 3) such that the ink composition within the range of the low-viscosity ink composition is mainly filled and used. it can.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Raw materials other than the coloring material were mixed by propeller stirring with the following raw materials and blending amounts to obtain a base liquid. Then, a colorant was added to the base liquid and mixed by stirring with a propeller to obtain a water-based ink composition for writing instruments.
The viscosity of the obtained ink composition was measured with a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd., sample volume 20 ml). Specifically, the viscosity at 20 ° C. and a rotation speed of 60 rpm was 1.7 mPa · s. The surface tension of the obtained ink composition was measured by a surface tension measuring instrument (platinum plate, vertical plate method, manufactured by Kyowa Interface Science Co., Ltd. under a 20 ° C. environment) and found to be 51 mN / m. Further, as a result of measuring the pH of the ink composition at 20 ° C. using a pH meter (manufactured by DKK-TOA CORPORATION), the pH was 9.6.
-Polyester resin A 0.20% by mass
(25% aqueous solution of polyester resin, weight average molecular weight: 16000, softening point: 115 ° C to 125 ° C, Tg (minimum film formation temperature): 47 ° C, hydrophilic group: SO ₃ Na group)
-Α-glucan or α-glucan derivative 0.03% by mass
(Pullulan)
・ Colorant 20.0% by mass
(20% aqueous dispersion of anionic self-dispersing pigment (self-dispersing carbon black))
・ Water-soluble organic solvent 2.0% by mass
(Diethylene glycol)
-Trimethylglycine 2.0% by mass
・ PH adjuster 2.0% by mass
(Triethanolamine)
・ Preservative 0.05% by mass
(1,2-Benz isothiazolin-3-one)
・ Water 73.72% by mass

<Examples 2 to 11, Comparative Examples 1 to 3>
Examples 2 to 11 and Comparative Examples 1 to 3 are the same as those of Example 1 except that the types and blending amounts of the components contained in the ink composition are changed to the compositions shown in Tables 1 and 2. A water-based ink composition for writing instruments was obtained in the same manner.

<Test and evaluation>
The obtained ink composition was tested and evaluated by the following method. The results obtained are shown in Tables 1 and 2.

The water-based ink composition for writing instruments of Examples 1 to 11 and Comparative Examples 1 to 3 was injected into a polyethylene ink cartridge, and the ink cartridge had a gold-plated stainless steel nib and was combed. A knock-type infestation writing instrument (Fountain pen manufactured by Pilot Corporation, FCN-1MR-BM) equipped with a groove-shaped ink flow rate adjusting member was attached to prepare a fountain pen.
The prepared fountain pen was used as a test writing instrument, and the following tests and evaluations were conducted.
JIS P3201 writing paper A was used as the test paper for the dry-up resistance test, the handwriting water resistance test, and the handwriting fixing property test.

<Dry-up resistance test>
The pen tip of the test writing instrument using the ink compositions of Examples 1 to 11 and Comparative Examples 1 to 3 was extended, and the pen tip was exposed to the atmosphere and placed horizontally at 20 ° C., 65. After leaving it for 0.5 hours under the condition of% RH, the letter "V" (the size of the letter is about 8 mm in length and width) is put on the test paper (high quality paper (Shiraoi 4 / 6T) made by Nippon Paper Co., Ltd.). ) Was continuously written, the number of characters until the handwriting was restored to a recognizable level was counted, and the dry-up resistance was evaluated according to the following evaluation criteria. The obtained evaluation results are summarized in Tables 1 and 2.
⊚: The number of characters until the return was less than 2 characters.
◯: The number of characters until the return was 2 or more and less than 10 characters.
Δ: The number of characters until the return was 10 characters or more and less than 20 characters.
X: The handwriting was not restored even after returning 20 characters.

<Handwriting water resistance test>
Using a test writing instrument using the ink compositions of Examples 1 to 11 and Comparative Examples 1 to 3, a test paper (high-quality paper manufactured by Nippon Paper Co., Ltd. (Shiraoi 4 / 6T)) was used. Write the word Ei, leave it for 5 minutes, then drop a drop of ion-exchanged water on the handwriting with a dropper, visually observe the state of the handwriting one day later, compare it with the initial handwriting, and follow the evaluation criteria below. Water resistance was evaluated. The obtained evaluation results are summarized in Tables 1 and 2.
⊚: No bleeding or change in color tone was observed in the handwriting.
◯: Slight bleeding of handwriting and change in color tone were observed, but there was no problem in practical use.
Δ: Some bleeding of handwriting and changes in color tone were observed, but it was at a practical level.
×: Large changes in handwriting bleeding and color tone were observed.

<Handwriting fixability test>
Using a test writing instrument using the ink compositions of Examples 1 to 11 and Comparative Examples 1 to 3, a test paper (high-quality paper manufactured by Nippon Paper Co., Ltd. (Shiraoi 4 / 6T)) was used. After writing the word Ei and leaving it for 1 hour, the handwriting was rubbed with JK Wiper 150-S (manufactured by Nippon Paper Crecia Co., Ltd.), and the state of the handwriting was observed, and the handwriting fixability was evaluated according to the following criteria. .. The obtained evaluation results are summarized in Tables 1 and 2.
⊚: The handwriting was not soiled, and a good handwriting remained.
◯: The handwriting was only slightly soiled, and there was no problem in practical use.
Δ: The handwriting was partially soiled, but it was at a practical level.
X: The handwriting was very dirty.

As shown in Tables 1 and 2, the ink compositions of Examples 1 to 11 had good levels of dry-up resistance, handwriting water resistance, and handwriting fixability. On the other hand, since the ink compositions of Comparative Examples 1 to 3 do not use a polyester resin and α-glucan or α-glucan derivative, the ink composition can satisfy all of dry-up resistance, handwriting water resistance, and handwriting fixability. There wasn't.

Further, the ink compositions of Examples 1 to 10 using the self-dispersing pigment are superior in dispersion stability and excellent ink ejection as compared with the ink composition of Example 11 not using the self-dispersing pigment. It had the property, and a uniform and good handwriting was obtained.

Based on the above, the water-based ink composition for writing instruments containing a polyester resin, α-glucan or α-glucan derivative, a colorant, and a solvent has excellent dry-up resistance, and the pen tip is exposed to the atmosphere for a while. Good handwriting can be obtained even in the state of being scratched, and the obtained handwriting is hard to bleed even when water droplets adhere to it, and the handwriting is hard to get dirty even if it is rubbed, and it also has water resistance and handwriting fixability. It was found that the writing instrument using the water-based ink composition for writing instruments was also excellent as a writing instrument.

The ink composition of the present invention can be used for various writing tools such as ballpoint pens, marking pens, perennial pens, handwriting pens, and calligraphy pens, and the writing tools containing the ink composition have excellent dry-up resistance. However, it is also excellent as a writing tool because it has excellent handwriting water resistance and handwriting fixing property, and can bring about good handwriting.

Claims (6)

A water-based ink composition for writing instruments, which comprises a polyester resin, an α-glucan or an α-glucan derivative, a colorant, and water. The water-based ink composition for writing instruments according to claim 1, wherein the polyester resin is a saturated copolymerized polyester resin. The water-based ink composition for writing instruments according to claim 1 or 2, wherein the α-glucan or α-glucan derivative is α1,4-1,6 glucan or α1,4-1,6 glucan derivative. The writing instrument according to any one of claims 1 to 3, wherein the content of the polyester resin is 0.001% by mass to 5% by mass based on the total mass of the water-based ink composition for writing instruments. Aqueous ink composition. The item according to any one of claims 1 to 4, wherein the content of the α-glucan or the α-glucan derivative is 0.001% by mass to 1% by mass based on the total mass of the water-based ink composition for writing instruments. The water-based ink composition for writing instruments described. A writing instrument comprising the water-based ink composition for a writing instrument according to any one of claims 1 to 5.