JP2007177023A - Water-based ink composition for ballpoint pen and ballpoint pen having the same therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink composition for ballpoint pens, which exhibits an excellent anti-hanging performance without inhibiting a dry-up resistant property and exhibits high ink dispersion stability for a low viscosity ink, and to provide a ballpoint pen having the same therein. <P>SOLUTION: This water-based ink composition for the ballpoint pens comprises a colorant, a water-soluble organic solvent, water and an acrylic resin emulsion having an average particle diameter of ≤0.1 μm, and has an ink viscosity of 1 to 20 mPa s at 20°C and a shear-thinning index of 0.9 to 1. The glass transition point (Tg) of the acrylic resin emulsion is ≥30°C. The ballpoint pen has the water-based ink composition for the ballpoint pens therein. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water-based ink composition for ballpoint pens. Furthermore, the present invention relates to a water-based ink composition for ballpoint pens and a ballpoint pen that exhibits excellent sag-preventing performance without impairing dry-up resistance at the nib.

Conventionally, as a ballpoint pen containing a water-based ink composition, an ink supply member (pen core) that adjusts the amount of ink supplied from the ink containing portion to the pen tip, or one end directly or via a relay member Some ink is stored directly in an ink storage tube fitted with a ballpoint pen tip.
Among them, in ballpoint pens using ink supply members, air enters and exits along with changes in the internal pressure of the ink container due to ink consumption and temperature changes. May sag.
Also, in the ballpoint pen that contains ink directly in the ink containing tube, when the viscosity of the ink to be stored is high, it becomes difficult to obtain a good writing feeling or line breakage in the handwriting, conversely, when the viscosity of the ink is low, The ink is excellent in ink discharge property and gives a good writing feeling, but the ink may hang down when left in the pen point downward state.
In particular, when a ballpoint pen is used that does not have a cap, etc. and the pen tip is always exposed to the outside air and is housed in the shaft cylinder, moisture evaporation from the pen tip is significant and writing is impossible in a short time. Therefore, it is necessary to add an additive to the ink for the purpose of improving the dry-up resistance. However, when a large amount of a water-soluble organic solvent, a wetting agent such as polyhydric alcohol, urea, or the like is added as the additive in order to satisfy dry-up resistance, the ink viscosity is increased and writing defects are likely to occur. In some cases, there are problems such as that the liquid does not dry for a long time, or that the pen tip easily hangs down when left in the pen tip downward state (see Patent Document 1).
Japanese Patent Publication No. 5-54875

  The present invention solves the above-mentioned conventional problems, that is, exhibits excellent sag-preventing performance without impairing dry-up resistance, and has high ink dispersion stability even with low-viscosity inks. A water-based ink composition for a ballpoint pen that exhibits properties and a ballpoint pen incorporating the same are provided.

The water-based ink composition for a ballpoint pen of the present invention includes at least a colorant, a water-soluble organic solvent, water, and an acrylic resin emulsion having an average particle size of 0.1 μm or less, and has an ink viscosity of 1 to 20 ° C. The requirement is 20 mPa · s and the shear thinning index is 0.9 to 1.
Furthermore, the glass transition point (Tg) of the acrylic resin emulsion is 30 ° C. or higher, and the minimum film forming temperature of the acrylic resin emulsion is 40 ° C. or lower.
Furthermore, the ball-point pen containing the water-based ink composition for ball-point pens is a requirement, and the ball-point pen stores ink directly in an ink storage tube in which a ball-point pen tip is attached directly or via a relay member, and with ink consumption. It is required that the ink backflow prevention body to be followed is closely arranged at the rear end of the ink, and that the ballpoint pen is of a capless type in which the ballpoint pen tip is projected and retracted from the front end opening portion of the shaft cylinder by the operation of the retracting mechanism.

  According to the present invention, even in a water-based ink composition having a low ink viscosity, it is possible to exhibit excellent ink sag-preventing performance without impairing the dry-up resistance of the nib and to prevent the ink from sinking or the like. It is excellent in stability.

  In the present invention, a specific acrylic resin emulsion is added to a low-viscosity water-based ink composition for ballpoint pens, so that the emulsion particles form a dry film on the nib. It can provide excellent ink sag performance without deteriorating the properties.

As the acrylic resin emulsion, those having an average particle size of 0.1 μm or less, that is, 0.01 to 0.1 μm are used because of high dispersion stability in ink. When the average particle size is larger than 0.1 μm, the emulsion tends to settle in the low-viscosity ink, so that it is difficult to maintain the ink dispersion stability.
The acrylic resin emulsion used in the present invention preferably has a glass transition point (Tg) of 30 ° C. or higher (that is, a range of 30 to 100 ° C.). Furthermore, it is preferable that the minimum film forming temperature is 40 ° C. or less. As a result, the film formation at the nib is performed promptly, so that the drooping of ink can be more reliably suppressed.

The acrylic resin emulsion can be added in an amount of 0.5 to 10% by weight, preferably 0.5 to 5% by weight in the ink composition.
If it is less than 0.5% by weight, it is difficult to obtain the desired effect, and even if it is added in excess of 10% by weight, no improvement in ink dripping prevention performance 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 will be exemplified 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 (CI. 16255), Tartrazine (CI. 19140), Acid Blue Black 10B (CI. 20470), Guinea Green (CI. 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 blue, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water-dispersed pigments that are finely and stably dispersed in an aqueous medium in advance using a surfactant or the like. Products are used, for example
C. I. Pigment Blue 15: 3B [Product Name: S.P. S. Blue GLL, pigment content 22%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Red 146 [Product Name: S.P. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Color Co., Ltd.]
C. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Red220 / 166 [Product name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
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.
Other examples include pearl pigments, gold and silver metallic pigments, luminous pigments, white pigments such as titanium dioxide used in correction pens, metal powders such as aluminum, fragrances, and fragrance capsule pigments.

  The colorant may be used alone 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.

Specific 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. Examples include monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone.
In addition, the said water-soluble organic solvent can be used 1 type or in combination of 2 or more types, and is used in 2 to 60 weight%, Preferably it is 5 to 35 weight%.

  Furthermore, a water-soluble resin can be added in order to impart adhesion and viscosity to the paper surface. 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.

  In addition, pH adjusters such as inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, metal soaps, polyalkylene glycols, phosphate esters, ethylene oxide as necessary Lubricants such as addition-type cationic activators and phosphate activators, rust preventives such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, carboxylic acid, 1,2-benzthiazoline 3-one Preservatives or antifungal agents such as sodium salt, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, urea, nonion Surfactant, sorbit Mannits, sucrose, glucose, reduced starch hydrolysates, wetting agents such as sodium pyrophosphate, antifoaming agents, fluorine surfactants and silicone surfactants that improve ink permeability may be used. .

A shear thinning agent can also be added to the ink composition.
As the shear thinning agent, a water-soluble or dispersible substance is effective, and xanthan gum, welan gum, and succinoglycan whose constituent monosaccharide is an organic acid-modified heteropolysaccharide of glucose and galactose (average molecular weight) About 1,000 to 8 million), guar gum, locust bean gum and derivatives thereof, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 based on alkyl esters of methacrylic acid, glucomannan, agar and carrageenan Carbohydrates having gelling ability extracted from seaweed such as benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymers, inorganic fine particles, nonionic surfactants having an HLB value of 8 to 12, dialkylsulfosuccinic acid Metal salts and nets Can be exemplified a salt, further, be added in combination in the ink composition N- alkyl-2-pyrrolidone and anionic surfactant can have stable shear thinning.

The ink composition has a viscosity at 20 ° C. of 1 to 20 mPa · s and a shear thinning index of 0.9 to 1, preferably 0.91 to 0.99.
The shear thinning index is an empirical formula derived from rheological measurement of shear stress value (T) and shear rate (j) value by a viscometer (T = Kj ^n, where K and n were calculated. N value calculated by applying (constant).

Furthermore, when the ink composition is filled in the ink container such as the shaft cylinder, an ink backflow prevention body (liquid stopper) can be disposed at the rear end of the ink composition.
As the ink backflow preventer, either liquid or solid can be used, and examples of the liquid ink backflow preventer include non-volatile media such as polybutene, α-olefin oligomer, silicone oil, and refined mineral oil. If desired, silica, aluminum silicate, swellable mica, fatty acid amide and the like can be added to the medium. Moreover, a resin molding is mentioned as a solid ink backflow prevention body. The liquid and solid ink backflow preventers can be used in combination.

The structure of the writing tip portion (tip) of the ballpoint pen filled with the ink composition has been effective in a conventional mechanism, and 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 chip formed by holding a ball on a chip, or a chip formed by holding a ball on a ball holding part formed by cutting a metal material with a drill or the like, or by cutting a metal pipe or metal material A ball or the like that is held by the formed chip and biased forward by a spring body can be applied.
The balls may be made of cemented carbide, stainless steel, ruby, ceramic, resin, etc., and those having a diameter in the range of 0.10 mm to 2.0 mm are used.

  As the shaft cylinder containing the ink composition, either metal or resin can be used, but a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, etc. has low ink evaporation and productivity. In terms of surface. Further, by using a transparent, colored transparent, or translucent material as the molded body, it is possible to confirm the ink color, the remaining amount of ink, and the like. In that case, discoloration of the ink in the shaft cylinder when not in use can be suppressed by providing an ultraviolet absorbing layer on the outer surface of the shaft cylinder or forming the shaft cylinder with a material to which an ultraviolet absorber is added.

In addition to directly connecting the tip to the shaft tube, the shaft tube and the chip may be connected via a connecting member.
In the case where the ink composition accommodated in the shaft cylinder has a low viscosity, a method of mounting an ink holding member on the front of the shaft cylinder and storing the ink composition directly in the shaft cylinder, A method of impregnating the ink composition into a fiber processed body and storing it is mentioned.
The shaft cylinder has a shaft cylinder itself with a tip attached to the tip as an ink container, and in addition to a structure in which ink is directly filled into the shaft cylinder, the refill is also a shaft cylinder ( The structure may be accommodated in the exterior. At this time, as the ballpoint pen, a cap type or a capless type in which the ballpoint pen tip is projected and retracted from the front end opening portion of the shaft cylinder by the operation of the retracting mechanism can be applied.

Examples will be described below, but the present invention is not limited to these examples.
Table 1 shows compositions of water-based inks for ballpoint pens of Examples and Comparative Examples. In addition, the numerical value of a composition in a table | surface shows a weight part. The ink viscosity was measured at 20 ° C. and 60 rpm using a BL type rotational viscometer [manufactured by Tokyo Keiki Co., Ltd.].

The contents of the raw materials in the table will be described along the note numbers.
(1) Product name: FISCO BLACK 886, manufactured by Orient Chemical Industry Co., Ltd.
(2) Eisen Hodogaya Co., Ltd., trade name: Phloxine (3) Sumitomo Chemical Co., Ltd., trade name: Acid Blue PG
(4) Johnson Polymer Co., Ltd., trade name: Jonkrill 734 (average particle size: 0.08 μm, glass transition point: 30 ° C., film forming temperature: 5 ° C., nonvolatile content: 42%)
(5) Made by Johnson Polymer Co., Ltd., trade name: Jonkrill 7600 (average particle size: 0.09 μm, glass transition point: 35 ° C., film forming temperature: 10 ° C., nonvolatile content: 47%)
(6) Johnson Polymer Co., Ltd., trade name: Jonkrill 352 (average particle size: 0.10 μm, glass transition point: 56 ° C., film forming temperature: 10 ° C., nonvolatile content: 45%)
(7) Johnson Polymer Co., Ltd., trade name: Jonkrill 7001 (average particle size: 0.08 μm, glass transition point: 12 ° C., film forming temperature: 5 ° C., nonvolatile content: 42%)
(8) Johnson Polymer Co., Ltd., trade name: Jonkrill 61J (glass transition point: 70 ° C., nonvolatile content: 30.5%)
(9) Product name: Polysol P-4 (average particle size: 0.50 μm, film-forming temperature: 0 ° C., nonvolatile content: 50%), manufactured by Showa Polymer Co., Ltd.
(10) manufactured by Johnson Polymer Co., Ltd., trade name: Jonkrill PDX7111B (average particle size: 0.2 μm, glass transition point: 19 ° C., film forming temperature: 24 ° C., nonvolatile content: 55%)
(11) Product name: Sankara 634, manufactured by Taiyo Kagaku Co., Ltd.
(12) 1,2-benzisothiazolin-3-one, manufactured by Zeneca Corporation, trade name: Proxel XL-2
(13) Phosphate ester surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL

Preparation of ink Add components other than λ-carrageenan and polyvinylpyrrolidone to water, mix and stir for 1 hour, add an aqueous solution of λ-carrageenan and polyvinylpyrrolidone, and stir with a disper at 20 ° C for 15 minutes. It was prepared with.

Preparation of Ink Backflow Preventer Body In 85 parts of polybutene as a base oil, 15 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 ballpoint pen 1 g of each ink composition is filled in a ballpoint pen refill in which a stainless steel chip holding a 0.7 mm diameter cemented carbide ball is fitted to one end of a polypropylene pipe, and the rear end is filled. After the ink backflow preventer was disposed, the ballpoint pen refill was incorporated into a shaft tube to prepare a sample ballpoint pen.

The following tests were conducted using the sample ballpoint pen.
Sagging test The sample ball-point pen is held downward (inverted) in a non-contact state with the pen tip (tip) and left in an atmosphere at a temperature of 20 ° C. and a relative humidity of 95% for 20 hours, and then the appearance of the pen tip is visually observed. did.
Ink stability test Each ink composition was allowed to stand at 20 ° C and 50 ° C for 7 days, and then the state of the ink was visually observed.
The results of the test are shown in the following table.

The evaluation of the test results is as follows.
Sagging test ○: No sagging of ink is observed.
Δ: A small ink droplet is observed at the tip of the chip.
X: A large ink droplet is observed at the tip of the chip, or ink leaking from the tip of the chip is falling.
Ink stability test ○: No change compared to before standing.
X: Floating or sedimentation of resin emulsion is observed.

Claims (6)

  It contains at least a colorant, a water-soluble organic solvent, water, and an acrylic resin emulsion having an average particle diameter of 0.1 μm or less, an ink viscosity at 20 ° C. of 1 to 20 mPa · s, and a shear thinning index of 0.1. A water-based ink composition for ballpoint pens, which is 9-1.   The water-based ink composition for ballpoint pens according to claim 1 whose glass transition point (Tg) of said acrylic resin emulsion is 30 ° C or more.   The water-based ink composition for ballpoint pens according to claim 1 or 2 whose minimum film forming temperature of said acrylic resin emulsion is 40 ° C or less.   The ball-point pen which incorporated the water-based ink composition for ball-point pens in any one of the said Claims 1 thru | or 3.   5. The ballpoint pen according to claim 4, wherein the ink is stored directly in an ink storage tube to which a ballpoint pen tip is attached directly or via a relay member, and an ink backflow prevention body that follows as the ink is consumed is closely arranged at the rear end of the ink. .   The ballpoint pen according to claim 5, wherein the ballpoint pen is a capless type in which a ballpoint pen tip is projected and retracted from a front end opening portion of the shaft cylinder by operation of a retracting mechanism.