JP2005036156A - Aqueous ink composition for use in writing instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous ink composition for use in a writing instrument that is superior in so-called cap-off performance (dry up resistance), that is, the performance not to cause slight touching or unwritability due to dry up of a pen tip when left to stand capped off for a long period, and does not cause reduction in an ink performance such as a local change in viscosity or pH even under high humidity. <P>SOLUTION: This ink composition comprises at least water, a colorant and a polyurethane polyol. A ballpoint pen containing the ink composition is supplied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water-based ink composition for writing instruments. In more detail, even when left for a long time with the cap removed, the water for writing instruments has excellent dry-up resistance (cap-off performance) that suppresses the occurrence of blurring and inability to write due to drying of the nib. The present invention relates to an ink composition.

  Conventionally, water-soluble organic solvents, urea and / or urea derivatives, and the like have been used as pen tip drying inhibitors for water-based inks for writing instruments (see, for example, Patent Document 1). In recent years, in order to improve the fastness of handwriting, ink compositions for writing instruments using pigments as colorants have been widely used. However, pigment-based inks dry faster at the nib than dye-based inks. Also, there is a drawback that the writing property does not recover even when the cap is attached after drying.

  In the field of water-based ballpoint pens, there are many so-called “gel ballpoint pens” on the market that have a structure in which shear-thinning ink is directly stored in an ink storage tube and an ink backflow prevention body is provided at the rear end of the ink. Inks used for various ballpoint pens are shear thinning agents such as gums such as xanthan gum and succinoglycan, cross-linked acrylic acid polymers, nonionic surfactants having an HLB value of 8 to 12, and associative urethanes. Etc. have been proposed and put to practical use. However, any of these shear thinning agents can easily form a strong dry film when the water evaporates at the pen tip, and thus the dry-up resistance may be significantly deteriorated.

Therefore, the shear-thinning water-based ballpoint pen ink requires further improvement in dry-up resistance, and attempts have been made to increase the amount of the water-soluble organic solvent, urea and / or its derivatives.
Japanese Patent Publication No. 5-54875

However, for example, water-soluble organic solvents represented by polyhydric alcohols such as glycerin and ethylene glycol require a large amount of addition in order to obtain sufficient dry-up resistance, resulting in high-speed writing due to an increase in ink viscosity. Various problems such as poor ink following ability, poor drying of handwriting, bleeding of handwriting, and the like occur.
Although urea and / or urea derivatives have some improvement in dry-up resistance, they are decomposed by storage in a high-temperature environment to generate ammonia, increase the pH of the ink, and perform solid analysis at the nib It may cause performance deterioration of the writing instrument, such as inducing outage.

  In addition, the water-soluble organic solvent, urea and / or urea derivatives, etc. have high water-absorbing performance, and they exhibit dry-up resistance. When the writing instrument is left under a high humidity condition, the pen tip portion locally absorbs moisture. For this reason, particularly when such ink is applied to a ballpoint pen, the viscosity of the ink is lowered due to local water absorption at the pen tip portion, and a phenomenon such as drooping or dropping of the pen tip occurs.

  The present invention solves the above problems, that is, provides a water-based ink composition capable of giving excellent handwriting without bleeding and imparting dry-up resistance without changing the viscosity of the ink. To do. Furthermore, even when incorporated in a ballpoint pen, it is possible to provide a water-based ink composition for writing that can maintain dry-up resistance while preventing dripping or dripping of ink that occurs when the pen tip is left for a long time.

  The ink composition for a writing instrument of the present invention is required to contain at least water, a colorant, and a polyurethane polyol. Furthermore, it is a requirement that the ink composition for a writing instrument is an ink composition for a ballpoint pen.

  The polyurethane polyol used in the present invention is a water-soluble polyol having a plurality of urethane groups in the main skeleton and having a bifunctional or higher functional hydroxyl group, and in particular, the main skeleton is composed of a saturated aliphatic urethane. Used. By adding the water-soluble polyurethane polyol to the ink, excellent dry-up resistance can be imparted.

  The polyurethane polyol is blended in an amount of 1 to 40% by weight, preferably 2 to 20% by weight, based on the total amount of the ink composition. If it is less than 1% by weight, it is difficult to obtain the effect of dry-up resistance, and if it exceeds 40% by weight, the viscosity of the ink increases, which may cause crying or blurring, and may reduce cap-off performance.

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 exemplified below.
As an acid dye,
New coccin (CI. 16255),
Tartrazine (C.I. 19140),
Acid Blue Black 10B (C.I. 20470),
Guinea Green (C.I.42085),
Brilliant blue FCF (C.I.42090),
Acid Violet 6BN (C.I. 43525),
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) or the like is used.

As basic dye,
Chrysoidine (C.I. 11270),
Methyl violet FN (C.I. 42535),
Crystal violet (C.I. 42555),
Malachite green (C.I. 42000),
Victoria Blue FB (C.I. 44045),
Rhodamine B (C.I. 45170),
Acridine orange NS (C.I. 46005),
Methylene blue B (C.I. 52015) or the like is used.

As a direct dye,
Congo Red (C.I. 22120),
Direct Sky Blue 5B (C.I. 24400),
Violet BB (C.I. 27905),
Direct deep black EX (CI 30235),
Caillas Black G Conch (C.I. 35225),
Direct Fast Black G (C.I. 35255),
Phthalocyanine blue (C.I. 74180) or the like is used.

In addition to inorganic pigments such as carbon black and ultramarine blue, and organic pigments such as copper phthalocyanine blue and benzidine yellow, the pigments have already been finely and stably dispersed in an aqueous medium using a surfactant or a water-soluble resin. Water-dispersed pigment products are used, for example, as water-dispersed pigments using surfactants,
C. I. Pigment Blue 15: 3B [trade name: Sandye SuperBlue GLL, pigment content 24%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Red 146 [trade name: Sandye Super Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Yellow 81 [trade name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Red 220/166 [trade name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
In addition, as a water-dispersed pigment using a water-soluble resin,
C. I. Pigment Black 7 (trade name: WA color Black A250, pigment content 15%, manufactured by Dainichi Seika Kogyo Co., Ltd.),
C. I. Pigment Green 7 [trade name: WA-S color Green, pigment content 8%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Violet 23 [trade name: Micropigmo WMVT-5, pigment content 20%, manufactured by Orient Chemical Co., Ltd.]
C. I. Pigment Yellow 83 [trade name: Emacol NS Yellow 4618, pigment content 30%, manufactured by Sanyo Color Co., Ltd.].

As fluorescent pigments, synthetic resin fine particle fluorescent pigments in which various fluorescent dyes are formed into a solid solution in a resin matrix can be used. Other examples include pearl pigments, metal powder pigments, phosphorescent pigments, white pigments such as titanium dioxide, silica and calcium carbonate, capsule pigments encapsulating thermochromic compositions, capsule pigments encapsulating perfumes and perfumes.
The metallic luster pigment is a metallic luster pigment such as aluminum or brass, and a metallic luster pigment in which the surface of natural mica, synthetic mica, glass piece, alumina, or transparent film piece is coated with a metal oxide such as titanium oxide as a core substance. (Pearl pigment), a metallic luster pigment in which a metal vapor deposition film is formed on a transparent or colored transparent film, and a metallic luster pigment having an iris property obtained by finely cutting an iris film in which a plurality of transparent resin layers are laminated.
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.

  Moreover, when a pigment is used as the colorant, a pigment dispersant can be added as necessary. Examples of the pigment dispersant include surfactants such as anions and nonions, anionic polymers such as polyacrylic acid and styreneacrylic acid, and nonionic polymers such as PVP and PVA.

Furthermore, a water-soluble organic solvent can be added as needed.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and ethylene glycol monomethyl. Ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2- Pyrrolidone, and the like.
The water-soluble organic solvent may be used alone or in combination of two or more, and is used in the range of 3 to 30% by weight.

  In addition to the above components, pH adjusters such as inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium as necessary Rust inhibitor such as nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, coalic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, paraoxybenzoic acid Preservatives or antifungal agents such as propyl, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, metal soap, polyalkylene glycol, fatty acid ester, ethylene oxide addition type cationic activator, phosphoric acid-based activity Agent, Thioka Lubricants such as bamate and dimethyldithiocarbamate, wetting agents such as urea and sodium pyrophosphate, fluorine surfactants that improve ink permeability, nonionic, anionic and cationic surfactants, dimethyl An antifoaming agent such as polysiloxane, a dispersing agent or the like may be used.

The water-based ink composition for a writing instrument of the present invention is of a type in which a ballpoint pen tip is directly attached to the tip or directly in an ink containing tube attached via a connecting member, and an ink backflow preventer is disposed at the rear end of the ink. When applied to a ballpoint pen, if gas is mixed in the ink, the gas gathers over time and bubbles are generated, which adversely affects the ink discharge during writing and makes writing impossible if bubbles exist at the writing tip. Ascorbic acid, ascorbic acid derivative, α-tocopherol, catechin, catechin derivative, synthetic polyphenol, phosphonate, phosphinate, sulfite, sulfoxylate, dithionate, thiosulfate, dioxide It is preferable to chemically remove bubbles by adding thiourea, formamidinesulfinic acid, glutathione, etc.
Furthermore, if necessary, a shear thinning agent can be added to give the ink an appropriate viscosity for practical use. The shear thinning agent used can be appropriately selected from conventionally known ones. Specific examples thereof include polysaccharides such as xanthan gum, succinoglycan and carrageenan, polyacrylic acid, cross-linked acrylic acid, and polyvinyl acetamide. , Nonionic surfactants, anionic surfactants, associative urethane emulsions, and the like.

  Examples of the ink backflow preventer include base oils composed of conventionally known non-volatile liquids or hardly volatile liquids such as polybutene, α-olefin oligomers, silicone oils, and refined mineral oils, silica, aluminum silicate, swellable mica, fatty acids. What added thickeners, such as an amide, is applied. Polybutene or silicone oil is preferably used as the base oil, and fatty acid amide or silica is preferably used as the thickener.

  The structure and shape of the writing instrument itself that fills the water-based ink composition for a writing instrument of the present invention is not particularly limited, and conventional ones can be applied, for example, fiber tips, felt tips, plastic tips, etc. The ink occlusion body consisting of fiber bundles housed in the shaft cylinder is impregnated with ink, and the ink is supplied to the tip of the writing. A structure in which an ink flow rate adjusting member consisting of a member or a fiber bundle is interposed, a marking pen having a structure in which ink is directly stored in the shaft cylinder and a predetermined amount of ink is supplied to the writing tip portion by a valve mechanism, or in the shaft cylinder An ink containing tube filled with the ink composition, the ink containing tube communicating with a tip having a ball mounted on the tip, and an ink back for preventing backflow on the rear end surface of the ink; Ballpoint pens and the prevention body is closely, writing unit is housed in the barrel in a state of being exposed to the air, knock-type, rotary, ball-point pen or the like having a retractable mechanism sliding the like.

  In particular, when the water-based ink composition for a writing instrument of the present invention is incorporated in a ballpoint pen that is housed in a shaft cylinder with the pen tip exposed to the outside air, it exhibits high dry-up resistance and It also has an effect of preventing ink dripping or dripping that has been generated in the past when the tip is left facing for a long time with the tip exposed.

  The present invention eliminates problems such as ink viscosity increase and handwriting bleeding that have occurred due to the addition of compounds used to improve cap-off properties, and has good stability and excellent cap-off properties. A water-based ink composition for writing can be provided. Furthermore, even when it is built in a ballpoint pen, it can be used for writing that can maintain dry-up resistance while preventing dripping or dripping of ink that occurs when the pen tip is left facing the outside air for a long time with the pen tip facing down. A water-based ink composition can be provided.

  The water-based ink composition for a writing instrument of the present invention is obtained by adding a colorant and a polyurethane polyol to an aqueous medium, and further adding an additive when the additive is blended, and heating and stirring as necessary. Thus, it is prepared in a dissolved or dispersed state, and is used by filling a writing instrument in the form of a marking pen such as a ballpoint pen, a sign pen or a felt pen, a fountain pen or a brush pen.

  The following table shows examples and comparative examples. However, the present invention is not limited to these examples. In addition, the numerical value in a table | surface represents a weight part. The ink viscosity was measured at 20 ° C. and 1 rpm using an E-type rotational viscometer [manufactured by Tokyo Keiki Co., Ltd.].

The raw materials (1) to (9) in Table 1 will be described below.
(1) Fuji Dye Co., Ltd., trade name: Fuji SP Blue 625, pigment content (copper phthalocyanine blue) 27.5%, diethylene glycol 8%, anionic surfactant 4%, water residue (2) Fuji Dye Co., Ltd. Product name: Fuji SP Black 8922, pigment content (carbon black) 20%, diethylene glycol 15%, anionic surfactant 6%, water residue (3) manufactured by Orient Chemical Industries, C.I. I. Direct Black 19, trade name: Water Black 100-L (20% aqueous solution)
(4) Product name: Flexorez UD320-100, hydroxyl value 350, manufactured by King Industry
(5) Product name: Flexorez UD350, 88% aqueous solution, hydroxyl value 325, manufactured by King Industries
(6) Product name: Primal ASE-60, manufactured by Rohm & Haas Japan
(7) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf A212C, phosphate ester surfactant (8) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Hytenol N08, anionic surfactant ( (Polyoxyethylene nonylphenyl ether ammonium sulfate salt)
(9) Product name: Proxel XL-2, 1,2-benzothiazolin-3-one manufactured by Avicia

Preparation of ink Each raw material other than the alkali-thickened acrylic emulsion or xanthan gum was mixed in the above-mentioned blending amount, stirred for 2 hours with a disper (20 ° C., 2000 rpm) and dissolved, and then the alkali-thickened acrylic emulsion or xanthan gum was further added. The ink for writing instruments was obtained by adding and stirring for 1 hour with a disper (20 degreeC, 6000 rpm).

Preparation of Ink Backflow Preventer Body Into 98 parts of polybutene as a base oil, 2 parts of fatty acid amide as a thickener was added, and then kneaded with three rolls to obtain an ink backflow preventer body.

Preparation of a sample ballpoint pen Each of the ink compositions was held in a 0.7 mm diameter ball, and a stainless steel tip with a spring inside that pressed the ball forward was a polypropylene pipe (inner diameter 3.8 mm). A sample ballpoint pen was manufactured by filling a ballpoint pen refill fitted at one end, placing the ink backflow preventer at the rear end, and then centrifuging to incorporate the ballpoint refill into the shaft tube.

The following tests were conducted with the sample ballpoint pens.
Cap-off test After assembling, a sample ball-point pen that was confirmed to be writable was left in a room (20 ° C.) and a constant temperature bath at 50 ° C. for 30 days with the pen tip exposed, and then JIS P3201. Twelve consecutive circles were written on writing paper A by hand, and it was confirmed how many circles could be written normally.
Sagging test After assembling, the sample ballpoint pen, which was confirmed to be writable, was held downward (inverted) with the pen tip exposed and the pen tip (ballpoint pen tip) not in contact, with a temperature of 20 ° C. and a relative humidity of 65 %, And the appearance of the nib was visually observed.
The results of the test are shown in the following table.

The evaluation of the test results is as follows.
Cap-off test ○: Writing is smoother than writing.
Δ: Can be written within 5 circles.
×: Cannot write within 1 line, or cannot write.
Sag test ○: No abnormality.
Δ: Ink droplets are observed at the tip of the chip.
X: A large ink droplet is observed at the tip of the chip, or ink drops from the tip of the chip occur.

Claims (2)

  A water-based ink composition for a writing instrument, comprising at least water, a colorant, and a polyurethane polyol.   The water-based ink composition for a writing instrument according to claim 1, wherein the water-based ink composition for a writing instrument is a water-based ink composition for a ballpoint pen.