JP2011068702A - Water-based ink composition for writing utensil, and writing utensil built-in with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink composition for a writing utensil capable of exhibiting a sufficient ink exchange property even in an ink tank comprising a hydrophobic synthetic resin material and maintaining the sufficient ink exchange property without generating permeation of handwriting and thickening of the ink even in the ink tank having a small inner diameter in the form of a cartridge or the like. <P>SOLUTION: The water-based ink composition applied to the writing utensil in which the ink is directly built-in in the ink tank comprising the hydrophobic synthetic resin includes at least a coloring agent, water, a water-soluble organic solvent, and an oligomer ester of polyglycerol and a dicarboxylic acid. The water-based ink composition is built-in in the writing utensil. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water-based ink composition for a writing instrument and a writing instrument incorporating the same. Specifically, the present invention relates to a writing instrument that directly fills an ink tank made of a hydrophobic synthetic resin material and a water-based ink composition applied thereto.

For writing instruments that contain free ink, such as direct liquid water-based ballpoint pens, marking pens, and fountain pens, the pen tip (temporary ink storage member such as a comb-like member) is used to adjust the ink flow rate. A structure in which an ink tank made of a synthetic resin material that stores ink in the shaft cylinder is generally attached to the end of the shaft cylinder.
This type of writing instrument is used for writing from a storage state such as a horizontally placed state (a state placed on a desk or a drawer) or a pen point upward state (a state where it is locked to a pen stand or a pocket of clothes). Therefore, by setting the pen tip downward, the water-based ink in the ink tank flows along the inner wall of the tank and flows down in the pen tip direction so that writing can be performed (this ink movement is called ink changeability).
Further, the ink tank may be a shaft cylinder itself or may be applied as a separate cartridge, and in any form, polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride General-purpose synthetic resin materials such as polyester are used.
Since all of the resin materials are hydrophobic, the ink tank inner wall surface is poorly wetted by the ink, and when water-based ink with high surface tension is contained, the ink flows down even if the writing instrument is in the writing state (pointed downward). It tends to stay in the original position without. In particular, due to the relationship with the diameter of the shaft cylinder, the above-mentioned tendency becomes stronger in the writing instrument using the cartridge type ink tank in which the size of the inner diameter is remarkably restricted. For this reason, ink is not sufficiently supplied to the pen tip during writing, and the handwriting is blurred.
In view of this, there has been proposed an ink that improves the ink changeability by adding a surfactant to lower the surface tension of the water-based ink (see, for example, Patent Document 1).

  The water-based ink reduces the surface tension of the ink by blending a nonionic surfactant such as polyoxyethylene nonylphenyl ether. Will flow down to the pen tip side, so there will be no blurring of handwriting. However, if the surface tension of the ink is low, the penetrability when writing on the paper surface will be high and handwriting bleeding will occur.

Apart from this, water-based inks to which gelatin, methylcellulose and the like are added have been proposed in order to improve ink wettability to a writing instrument member made of a hydrophobic synthetic resin material (see, for example, Patent Document 2).
The ink of Patent Document 2 gives wettability to the hydrophobic synthetic resin material without lowering the surface tension, and thus hardly causes handwriting bleeding. However, the additive is a water-soluble resin having a relatively large molecular weight. For this reason, the ink viscosity is greatly increased by adding a small amount, and there may be a problem that the ink followability at the time of writing, the dry-up resistance of the pen tip, and the like are deteriorated.

Japanese Patent Laid-Open No. 10-219172 JP-A-9-217036

The present invention provides a water-based ink composition for a writing instrument that exhibits good ink alternation even in an ink tank made of the above-described hydrophobic synthetic resin material.
Further, the present invention provides a water-based ink composition for a writing instrument that can maintain good ink changeability without causing handwriting bleeding or ink thickening even in an ink tank having a small inner diameter such as a cartridge form.

The present invention relates to a water-based ink composition applied to a writing instrument in which ink is directly incorporated in an ink tank made of a hydrophobic synthetic resin, and includes at least a colorant, water, a water-soluble organic solvent, polyglycerin, and dicarboxylic acid And an oligomeric ester.
Furthermore, the dicarboxylic acid constituting the oligomer ester is at least one selected from eicoic acid diacid, tetradecanedioic acid, and sebacic acid, and the oligomer ester is 0.05 to 5% by weight in the total amount of the ink composition. It is a requirement that it is included in the range and the surface tension is in the range of 38 to 70 mN / m.
Furthermore, a writing instrument comprising any one of the above water-based ink compositions is required.

  According to the present invention, the wettability to the inner wall of the ink tank made of a hydrophobic synthetic resin material can be improved without lowering the surface tension of the ink, so that a good ink replacement can be achieved without causing an increase in ink viscosity or handwriting bleeding. It becomes the water-based ink composition for writing instruments which can provide property.

  The present invention contains an oligomer ester of polyglycerin and dicarboxylic acid as a water-based ink applied to a writing instrument in which ink is directly incorporated in an ink tank made of a hydrophobic synthetic resin, without reducing the surface tension of the ink. It becomes possible to obtain good ink changeability.

The oligomer ester is obtained by randomly copolymerizing polyglycerin and various dicarboxylic acids, and as the dicarboxylic acid, eicoic acid diacid, tetradecanedioic acid, and sebacic acid are applied.
The mechanism by which the oligomer ester improves the hydrophilicity (wetting property) of the surface of the synthetic resin without causing a decrease in surface tension in the aqueous ink is not clear, but is presumed as follows. The oligomer ester structure is composed of a hydrophilic group in the polyglycerin part and a hydrophobic group in the unsaturated fatty acid part, and is considered to have a surface-active effect. However, the bulk of the hydrophobic group prevents the orientation to the water-air interface. The surface tension does not decrease. Further, it is considered that the hydrophilicity is improved because the hydrophobic group is adsorbed on the surface of the synthetic resin with the hydrophilic group facing outward.

The oligomer ester is added in an amount of 0.05 to 5% by weight, preferably 0.1 to 3% by weight, based on the total amount of the ink composition.
If it is less than 0.05% by weight, it is difficult to obtain the desired effect, and even if added over 5% by weight, no improvement in wettability is observed, so no further addition is required.

As the colorant, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are illustrated below.
As the dye, an acid dye, a basic dye, a direct dye, or the like can be used.
Examples of the acid dye include New Coxin (C.I. 16255), Tartrazine (C.I. 19140), Acid Blue Black 10B (C.I. 20470), Guinea Green (C.I. 42085), Brilliant Blue FCF (CI.42090), Acid Violet 6B (C.I.42640), Soluble Blue (C.I.42755), Naphthalene Green (C.I.44025), Eosin (C.I.45380), Phloxin (C.I. 45410), erythrosine (C.I. 45430), nigrosine (C.I. 50420), acid flavin (C.I. 56205) and the like are used.
Examples of basic dyes include chrysoidine (C.I. 11270), methyl violet FN (C.I. 42535), crystal violet (C.I. 42555), malachite green (C.I. 42000), Victoria blue FB ( CI 44045), rhodamine B (C.I. 45170), acridine orange NS (C.I. 46005), methylene blue B (C.I. 52015) and the like are used.
As direct dyes, Congo Red (C.I. 22120), Direct Sky Blue 5B (C.I. 24400), Violet BB (C.I. 27905), Direct Deep Black EX (C.I. 30235), Kaya Las Black G Conch (C.I. 35225), Direct Fast Black G (C.I. 35255), Phthalocyanine Blue (C.I. 74180) and the like are used.

Examples of the pigment include inorganic pigments such as carbon black and ultramarine, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water dispersion finely and stably dispersed in an aqueous medium in advance using a surfactant or resin. Pigment products and the like are used. I. Pigment Blue 15: 3B [Product name: Sandy Super Blue GLL, pigment content 24%, manufactured by Sanyo Dye Co., Ltd.], C.I. I. Pigment Red 146 [Product name: Sandy Super Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.], C.I. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.], C.I. I. Pigment Red 220/166 [Product name: TC Red FG, pigment content of about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
As the resin for dispersing the pigment, polyamide resin, polyurethane resin, polyester resin, epoxy resin, melamine resin, phenol resin, silicone resin, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, Examples thereof include polystyrene, acrylic acid resin, maleic acid resin, gum arabic, cellulose, dextran, casein, and derivatives thereof, and copolymers of the above-described resins.
As the fluorescent pigment, a fluorescent pigment in the form of fine particles of a synthetic resin in which various fluorescent dyes are formed into a solid solution in a resin matrix can be used.
In addition, white pigments such as titanium dioxide, metal powders such as aluminum, natural mica, synthetic mica, alumina, pearl pigments in which the surface of the core material is coated with a metal oxide such as titanium dioxide, cholesteric liquid crystal type glitter A functional pigment or the like can also be used.
Furthermore, a thermochromic pigment such as a microcapsule pigment encapsulating a thermochromic composition or a microcapsule pigment encapsulating a dye or a pigment together with the thermochromic composition can also be used.

The thermochromic composition includes (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction occurs. The composition is suitable and is encapsulated in microcapsules and applied as a reversible thermochromic microcapsule pigment.
Examples of the reversible thermochromic composition include those described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc., at a predetermined temperature (discoloration point). Discolored before and after, decolored state in the temperature range above the high temperature side discoloration point, color development state in the temperature range below the low temperature side discoloration point, only one specific state exists in the normal temperature range among the two states, The other state is maintained as long as the heat or cold required to develop the state is applied, but when the heat or cold is no longer applied, the hysteresis width returns to the state exhibited in the normal temperature range. A heat decolorizable microcapsule pigment in which a reversible thermochromic composition having relatively small characteristics (ΔH = 1 to 7 ° C.) is encapsulated in a microcapsule can be applied.

Furthermore, large hysteresis characteristics (ΔH _B = 8 to 50 ° C.) described in JP- _B -4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, and the like. ), That is, when the shape of the curve plotting the change in the color density due to the temperature change is lowering the temperature from the lower temperature side than the color changing temperature range, as opposed to increasing the temperature from the lower temperature side. Reversible heat with color memory in a specific temperature range when the color changes in a low temperature range below the complete color development temperature or in a high temperature range above the complete color erase temperature. A heat-decolorable microcapsule pigment in which the color-changing composition is encapsulated in microcapsules is also applicable.
Specifically, as the reversible thermochromic composition having color memory, a complete color development temperature can be obtained only in a freezing room, a cold district, etc., that is, −50 to 0 ° C., preferably −40 to − 5 ° C., more preferably −30 to −10 ° C., and complete decoloring temperature obtained from a frictional heat generated by a friction body, a heating body such as a hair dryer, that is, 50 to 95 ° C., preferably 50 to 90 ° C. More preferably, by specifying the range of 60 to 80 ° C. and specifying the ΔH value of 40 to 100 ° C., it is possible to effectively function to maintain the color exhibited in the normal state (daily life temperature range).

  The colorant can be used singly or in combination of two or more, and is used in the range of 1 to 25% by weight, preferably 2 to 15% by weight in the ink composition.

Further, as the water-soluble organic solvent, conventional general-purpose solvents compatible with water are used, and ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiol Diethylene glycol, hexylene glycol, 1,3-butanediol, neoprene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate , Propylene glycol monomethyl ether, propylene glycol Monoethyl ether, 2-pyrrolidone, N- methyl-2-pyrrolidone.
In addition, the said water-soluble organic solvent can also use 1 type, or 2 or more types together, It is 2-60 weight% in an ink composition, Preferably it is used in 5 to 35 weight%.

  In addition, if necessary, pH adjusters such as inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, rust preventives such as benzotriazole, tolyltriazole and saponin , Carboxylic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) Preservatives or antifungal agents such as pyridine, urea, sorbit, mannitol, sucrose, glucose, reduced starch hydrolyzate, wetting agents such as sodium pyrophosphate, metal soap, polyalkylene glycol, fatty acid ester, ethylene oxide addition type Cationic activator, phosphate activator, thiocarbamate, dimethyl Lubricant such as rudithiocarbamate, ascorbic acid, ascorbic acid derivative, α-tocopherol, catechin, catechin derivative, synthetic polyphenol, phosphonate, phosphinate, sulfite, sulfoxylate, dithionite, thiosulfate Antioxidants such as salts, thiourea dioxide, formamidinesulfinic acid, and glutathione, antifoaming agents, and fluorine surfactants and nonionic surfactants that improve ink permeability may be used.

  Further, a water-soluble resin can be added in order to impart adhesion to the paper surface or viscosity. Examples of the water-soluble resin include alkyd resins, acrylic resins, styrene maleic acid copolymers, cellulose derivatives, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin. The water-soluble resin can be used alone or in combination of two or more, and is used in the range of 1 to 30% by weight in the ink composition.

Furthermore, a shear thinning agent can be added.
As the shear thinning agent, water-soluble or dispersible substances are effective, and xanthan gum, welan gum, zetasy gum, dieutan gum, macrohomopsis gum, and constituent monosaccharides are organic acid-modified heterogeneous of glucose and galactose. Succinoglycan, which is a polysaccharide (average molecular weight: about 100 to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alkyl alginate, alkyl ester of methacrylic acid, molecular weight 100,000 to 150,000 Polymers, glucomannan, carbohydrates having gelling ability extracted from seaweeds such as agar and carrageenan, poly N-vinyl-carboxylic acid amide cross-linked products, benzylidene sorbitol and benzylidene xylitol or their derivatives, cross-linkable acrylic acid Coalescence Inorganic fine particles, nonionic surfactants having an HLB value of 8 to 12, can be exemplified metal salts and amine salts of dialkyl sulfosuccinate. Furthermore, N-alkyl-2-pyrrolidone and an anionic surfactant may be used in combination in the ink composition.
The shear thinning agent can be used in the range of 0.1 to 20% by weight in the ink composition.

The water-based ink constituted by the above composition is preferably applied by adjusting the surface tension to 38 mN / m or more, specifically 38 to 70 mN / m, preferably 40 to 60 mN / m.
If the surface tension of the ink is less than 38 mN / m, the ink changeability is improved, but handwriting blur occurs when writing on the paper surface.

The water-based ink composition is applied to a writing instrument having a structure in which ink is directly incorporated in an ink tank made of a hydrophobic synthetic resin material.
Examples of the writing instrument include those using a spare ink tank typified by a fountain pen. In addition, various types of tips such as marking pens and ballpoint pens with a structure in which various tips are attached to the writing tip, ink is directly built into the shaft tube, and a comb groove ink flow rate adjusting member (pen core) made of synthetic resin is interposed. It is also applied to pen-type writing instruments.

Among the chips, as the marking pen chip, for example, a fiber chip, a felt chip, a plastic chip, a brush, or the like can be applied. In particular, as a fiber chip, a nib made of a fiber processed body in which a large number of fibers are arranged in close contact with each other and a capillary gap is formed between adjacent fibers, and the outer periphery of the nib is coated with a resin. Etc. are applicable.
As a ballpoint pen tip, a tip formed by holding a ball in a ball holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from the outer surface, a ball holding formed by cutting a metal material with a drill or the like A chip formed by holding a ball in the part, a chip provided with a resin ball receiving seat inside a metal or plastic chip, or a ball held in the chip urged forward by a spring body, etc. Is applicable. In addition, the said ball | bowl can apply a cemented carbide alloy, stainless steel, a ruby, a ceramic, resin, rubber | gum, etc., and the thing of the range of diameter 0.1mm-2.0mm is used suitably.
Further, as a fountain pen-shaped tip (pen body), a metal plate such as a stainless steel plate or a gold alloy plate is cut into a taper taper shape, bent or curved, or resin-molded into a pen tip shape can be applied. . The pen body can be provided with a slit at the center or a ball at the tip.

  The ink tank (shaft cylinder itself or a separate cartridge form) is a molded body made of a general-purpose synthetic resin material such as polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS), polyvinyl chloride, and polyester. Yes, by using a transparent, colored transparent, or translucent molded article, the ink color, the ink remaining amount, and the like can be confirmed.

  Although the composition of the water-based ink for writing instruments of Examples and Comparative Examples is shown in the following table, the present invention is not limited to these Examples. In addition, the numerical value of a composition in a table | surface shows a weight part. The surface tension was measured using a Wilhelmy method surface tension meter (CB-VP type) manufactured by Kyowa Interface Science Co., Ltd.

The contents of the raw materials in the table will be described along the note numbers.
(1) Product name: BONJET BLACK CW-1, C.I. I. Pigment 7 aqueous dispersion, pigment content 20%
(2) Hodogaya Chemical Co., Ltd., trade name: Phloxine, C.I. I. 45410
(3) Nippon Seika Co., Ltd. product name: Neosolue-Aqna, active ingredient 60%
(4) Nikko Chemicals Co., Ltd., trade name: Nikkor NP-10

Preparation of ink Each raw material was mixed in the blending amounts of the above-mentioned Examples and Comparative Examples, stirred and dissolved at 20 ° C. for 3 hours, and then filtered to obtain a writing instrument water-based ink composition.

Preparation of ink cartridge Ink cartridge for test by filling 1 ml of the ink composition of Examples and Comparative Examples into a spare ink cartridge for fountain pen (manufactured by Pilot Corporation, IRF-12S) and fitting the packing (plug body). It was created.

The following tests were conducted using the test ink cartridge.
Ink changeability test Each ink cartridge is left in a thermostat at 50 ° C. for 24 hours and then taken out and allowed to cool to room temperature. Thereafter, the plug was opened and about half of the ink was taken out and sealed again. After standing for 24 hours at room temperature with the packing facing upward, the ink was turned upside down to measure the time for all the ink inside to flow down.

Bleeding test Each ink cartridge was mounted on a fountain pen, characters were written on a writing test paper A (former JIS P3201), and the presence or absence of bleeding was visually observed.

The results of each test are shown in the following table.

The evaluation of the test results is as follows.
Ink changeability test ○: Ink flowed down within 30 seconds.
X: Ink did not flow down even after 30 seconds.
Bleeding test ○: There is no bleeding in the handwriting.
X: Bleeding was observed in the handwriting.

Claims (5)

  An aqueous ink composition applied to a writing instrument in which ink is directly incorporated in an ink tank made of a hydrophobic synthetic resin, at least a colorant, water, a water-soluble organic solvent, an oligomer ester of polyglycerin and dicarboxylic acid A water-based ink composition for writing instruments, comprising:   The water-based ink composition for a writing instrument according to claim 1, wherein the dicarboxylic acid constituting the oligomer ester is at least one selected from eicoic acid diacid, tetradecanedioic acid, and sebacic acid.   The water-based ink composition for a writing instrument according to claim 1 or 2, wherein the oligomer ester is contained in an amount of 0.05 to 5% by weight in the total amount of the ink composition.   The water-based ink composition for a writing instrument according to any one of claims 1 to 3, wherein the surface tension is in the range of 38 to 70 mN / m.   A writing instrument comprising the water-based ink composition according to any one of claims 1 to 4.