JP2010196073A - Water-based ink composition for capless ball-point pen and ball-point pen storing the same ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink composition for a capless ball-point pen excellent in dry-up resistance without causing an excessive rise in ink viscosity even after evaporation of water from the ink, providing comfortable writing just after writing is started or after an elapsed time, exhibiting stable writing performance continuously without causing any inconvenience such as blur or sag and providing good handwriting continuously; and to provide a capless ball-point pen storing the same ink composition. <P>SOLUTION: The water-based ink composition for the capless ball-point pen at least comprises a colorant, water, a shear-thinning tackifier and a thickening inhibitor selected from an oligomer of N-vinyl-2-pyrrolidone with a degree of polymerization of 2-20, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone and ε-caprolactam. The capless ball-point pen stores the same ink composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water-based ink composition for a capless ballpoint pen and a capless ballpoint pen containing the same. More specifically, the present invention relates to a water-based ink composition for a capless ballpoint pen excellent in dry-up resistance performance at the nib and a capless ballpoint pen containing the same.

In recent years, water-based ink compositions containing water as a main solvent have been widely used as ink compositions accommodated in ballpoint pens in consideration of environmental issues and safety for the human body. Of these, ink compositions having shear thinning viscosity are low. It is possible to eliminate the drawback that the handwriting of a viscous water-based ballpoint pen bleeds.
Examples of substances that impart shear thinning to the ink composition (shear thinning imparting agent) include polysaccharides such as xanthan gum (see, for example, Patent Document 1).
However, the shear thinning agent may impair dry-up performance, and attempts to improve dry-up performance by using additives such as wetting agents such as water-soluble organic solvents and solid wetting agents such as urea. However, the effect of preventing drying is insufficient, and the viscosity of the ink rises and writing defects such as fading tend to occur.
Specifically, when urea is added excessively, the moisture evaporates from the writing tip, the concentration of the water-soluble organic solvent rises, and a so-called flower bloom phenomenon occurs in which solid content is deposited on the writing tip. Appearance deteriorates and blurring occurs. Furthermore, when a large amount of a water-soluble organic solvent or urea is added, when the writing tip is left faced downward in a humid environment, it is liable to cause problems such as drooping.
As described above, although there are many means for improving the dry-up resistance in the ink composition, it does not sufficiently satisfy other writing performances such as blurring or sagging of the handwriting, and especially the writing tip when not writing When used in a ballpoint pen (capless ballpoint pen) that does not require a cap in which the (ballpoint tip) is always open to the atmosphere, the dry-up resistance is an important requirement.

JP 59-74175

  The present invention solves the problems of the ink composition applied to the above-described conventional ballpoint pen that does not require a cap, that is, satisfies the dry-up resistance without impairing various writing performances. An object of the present invention is to provide a capless ballpoint pen aqueous ink composition and a capless ballpoint pen containing the same.

The present invention is an ink composition accommodated in a capless ballpoint pen in which a writing tip of a ballpoint pen refill appears and disappears from an opening at the front end of a barrel by the operation of a retracting mechanism, comprising a dye, water, a shear thinning agent, A capless comprising at least a thickening inhibitor selected from an oligomer of N-vinyl-2-pyrrolidone having a polymerization degree of 2 to 20, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, and ε-caprolactam A water-based ink composition for ballpoint pens is a requirement.
Further, the composition comprises 1 to 40% by weight of the thickening inhibitor, the shear thinning agent is a polysaccharide, and the shear thinning agent is selected from xanthan gum, welan gum, and succinoglycan. A sugar mixture comprising 40% by weight or more of 10 or more sugars; the sugar mixture is a starch saccharified product or a reduced starch saccharified product; and 0.5 to 10% by weight of the sugar mixture. It is a requirement that it contains, does not contain a water-soluble organic solvent, contains a water-soluble organic solvent, and the water-soluble organic solvent is 10% by weight or less in the total amount of the ink composition.
Further, the capless ballpoint pen is required to be contained in the ballpoint pen refill, in which the writing tip portion of the ballpoint pen refill appears and disappears from the opening at the front end of the shaft cylinder. .

  Since the present invention contains a thickening inhibitor such as an oligomer of N-vinyl-2-pyrrolidone, the ink viscosity does not increase excessively even when water in the ink evaporates. Capless, with excellent performance, good initial and time-lapse writing, stable writing performance without causing problems such as blurring or sagging of handwriting, and continuous good handwriting A water-based ink composition for a ballpoint pen and a capless ballpoint pen containing the same are obtained.

（ｎは２〜２０の整数を示す。）
Ｎ−ビニル−２−ピロリドンのオリゴマーの重合度が大きい（例えば、２０を越えるような場合）と、インキ中で固体状態で存在する傾向が強くなるため、所望の耐ドライアップ性能を満足させ難い。 Examples of the thickening inhibitor include oligomers of N-vinyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, and ε-caprolactam, and particularly N-vinyl-2-pyrrolidone. These oligomers are preferably used.
The thickening inhibitor absorbs moisture in the air under high humidity like urea and does not sag or drop, and when the moisture evaporates from the writing tip, the ink viscosity increases significantly. It is possible to prevent the handwriting from fading or becoming unwritable.
In the present invention, in the system containing the shear thinning agent and the thickening inhibitor in the ink, the viscosity when the water in the ink is evaporated by 40% by weight with respect to the total amount of the ink / the initial ink viscosity (EMD type) A water-based ink composition having a numerical value (x) indicated by a viscometer (measured at 1 rpm and 20 ° C.) of 2 or less, preferably 0.01 or more and 2 or less is used.
If the value exceeds 2, the change in the viscosity when the water in the ink is evaporated by 40% by weight and the initial ink viscosity are large, and therefore, the increase in viscosity tends to cause blurring and inability to write.
The thickening inhibitor used in the present invention is used in the range of 1 to 40% by weight, preferably 3 to 30% by weight, more preferably 3 to 15% by weight, based on the total amount of the ink. If the amount is less than 1% by weight, the effect of dry-up resistance is small. If the amount is more than 40% by weight, the shear thinning agent is in a poorly swelled state in the ink from the beginning, and the desired ink viscosity is hardly exhibited.
In addition, the oligomer of N-vinyl-2-pyrrolidone suitable as the thickening inhibitor is a compound represented by the general formula (1), and those having a polymerization degree (n) of 2 to 20, preferably Those having 2 to 10, more preferably 2 to 6 are used, and a plurality of oligomers of N-vinyl-2-pyrrolidone having different degrees of polymerization may be added to the ink.

(N represents an integer of 2 to 20)
If the degree of polymerization of the oligomer of N-vinyl-2-pyrrolidone is large (for example, when it exceeds 20), the tendency to exist in a solid state in the ink becomes strong, so that it is difficult to satisfy the desired dry-up resistance. .

As the colorant, a dye that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are illustrated 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.
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.

Furthermore, a conventional general-purpose water-soluble organic solvent compatible with water can be used.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, hexylene glycol, 1,3-butanediol, neoprene glycol, Polyethylene glycol, propylene glycol, butylene glycol, 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 monomethyl ether, propylene glycol monoethyl ether And propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone and the like.
In addition, the said water-soluble organic solvent can also use 1 type (s) or 2 or more types together, It is preferable to use in the range of 10 weight% or less with respect to the ink composition whole quantity.
The capless ballpoint pen water-based ink composition of the present invention contains the above-described thickening inhibitor, so that it is not necessary to actively improve the anti-drying-up performance by adding a water-soluble organic solvent. Sufficient performance can be achieved by adding no organic solvent or adding 10% by weight or less.
In addition, since the amount of water-soluble organic solvent added is less than that of conventional ink compositions, ink accumulates (droops) at the writing tip due to the water absorption of the water-soluble organic solvent, and the formation of good handwriting is impaired. Can prevent defects that contaminate clothing.

  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 Nitrite, diisopropylammonium nitrite, rust inhibitor such as 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 activity Agent, Thioka Lubricants such as bamate, dimethyldithiocarbamate, ascorbic acid, ascorbic acid derivative, α-tocopherol, catechin, catechin derivative, synthetic polyphenol, phosphonate, phosphinate, sulfite, sulfoxylate, dithionite Antioxidants such as salt, thiosulfate, thiourea dioxide, formamidinesulfinic acid, glutathione, urea, nonionic surfactants, sorbit, mannitol, sucrose, glucose, reduced starch hydrolysate, sodium pyrophosphate, etc. Wetting agents, fluorine surfactants that improve ink permeability, nonionic, anionic, and cationic surfactants, antifoaming agents such as dimethylpolysiloxane, and dispersants may be used.

The shear thinning of the ink composition is a rheological characteristic that has a property of being extremely high viscosity and difficult to flow in a static state or when the stress is low, and showing a good fluidity by decreasing the viscosity when the stress increases. It means liquidity also called thixotropic property or pseudoplasticity. Therefore, the ink composition is temporarily destroyed in the three-dimensional structure under high shear stress at the time of writing and the viscosity of the ink is lowered, and the ink at the tip of the writing becomes a low-viscosity ink suitable for writing and transferred to the paper surface. The When not writing, the viscosity of the ink becomes high, so that leakage of the ink can be prevented, and separation and backflow of the ink can be prevented. Also, the ink physical properties can be kept stable over time.
In particular, a ballpoint pen with a ball held at the tip of the writing has a low viscosity suitable for writing under high shear stress during writing, and the gap between the ball and the ball house moves by capillary force to move the paper surface. It is necessary to have ink characteristics that can be transferred to, and when not writing, the viscosity of all inks, including the vicinity of the ball, must be increased to prevent ink leakage, ink separation, and backflow. An ink composition having an ink viscosity at 100 rpm by an E-type rotational viscometer of 20 to 200 mPa · s (25 ° C.) and a shear thinning index of 0.1 to 0.8 is suitable.
The shear thinning index n can be obtained by assigning a numerical value to the empirical formula T = Kj ⁿ (T: shear stress value, j: shear rate, K is a calculated constant).

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) The main component is gum, guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, methacrylic acid alkyl ester, which are composed of glucose, glucuronic acid, fucose and rhamnose. A polymer having a molecular weight of 100,000 to 150,000, a thickening polysaccharide having gelling ability extracted from seaweed such as glucomannan, agar and carrageenan, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid heavy Coalescence, inorganic fine particles, Nonionic interfaces having an HLB value of 8 to 12, such as liglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether / polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, fatty acid amide Examples include activators, salts of dialkyl or dialkenyl sulfosuccinic acid, and the like, which can be used alone or in combination.
The shear thinning agent can be used in the range of 0.1 to 20% by weight in the ink composition.
In the combined system of the shear thinning agent and the thickening inhibitor, when the moisture in the ink is reduced, the shear thinning agent is in a semi-swelled state, and apparently the ink viscosity hardly increases.
As the shear thinning agent, xanthan gum, welan gum, succinoglycan is preferably used, and the ink stability is excellent.

  In addition, one or more water-soluble resins such as acrylic resin, styrene maleic acid copolymer, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin may be added within a range that does not impair drying resistance.

The water-based ink composition for capless ballpoint pens of the present invention preferably contains a sugar mixture containing 40% by weight or more of saccharides of 10 sugars or more, and satisfies the ink dripping prevention performance as well as the anti-drying performance. it can.
Monosaccharides and disaccharides do not form a dry film sufficiently, and have high water absorption. Therefore, when applied to a ballpoint pen, dripping tends to occur if the writing tip is left facing downward. In addition, in the case of about 3 to 8 sugars, the water absorption is lower than that of monosaccharides and disaccharides, but sufficient sag prevention performance is not obtained.
Since the saccharide has a lower hygroscopicity as the molecular weight increases and it becomes easier to form a dry film, the use of a saccharide of 10 sugars or more can prevent the ink from dripping while maintaining the cap-off performance.
As the saccharide of 10 sugars or more, a starch saccharified product obtained by enzymatic decomposition of starch or a reduced starch saccharified product obtained by reducing the terminal group of the starch saccharified product can be used.
In addition, when starch is decomposed, saccharides having various degrees of polymerization are generated. Therefore, it is technically difficult to completely isolate only saccharides having 10 or more sugars, and manufacturing costs are also increased. Therefore, in a saccharide mixture containing 9 or less saccharides, the performance can be sufficiently expressed by containing 40% by weight or more of the 10 or more saccharides.
The sugar mixture is blended in the range of 0.5 to 10.0% by weight, preferably 1.0 to 8.0% by weight, based on the total amount of the ink composition. If the amount is less than 0.5% by weight, it is difficult to obtain a drooping prevention effect. If the amount exceeds 10.0% by weight, the viscosity of the ink may increase, causing crying or blurring, and ink followability during writing may be impaired.

The structure and shape of the capless ballpoint pen containing the water-based ink composition for a capless ballpoint pen of the present invention are not particularly limited, and the writing tip provided on the ballpoint pen refill is exposed to the outside air in the shaft cylinder. The writing tip protrudes from the shaft tube opening by the operation of the retracting mechanism.
Examples of the operation method of the retracting mechanism include a knock type, a rotary type, and a slide type.
The knock type has a knock portion on the rear end portion of the shaft tube and the side surface of the shaft tube, and by pressing the knock portion, the writing tip portion of the ballpoint pen refill is projected and retracted from the front end opening portion of the shaft tube, or on the shaft tube. A configuration in which the writing tip portion of the ballpoint pen refill is projected and retracted from the front end opening portion of the shaft cylinder by pressing the provided clip portion can be exemplified.
The rotary type has a rotating part at the rear part of the shaft cylinder, and can be exemplified by a configuration in which the writing tip part of the ballpoint pen refill is projected and retracted from the front end part of the shaft cylinder by turning the rotating part.
The slide type has a slide part on the side surface of the shaft cylinder, and the sliding tip of the writing point of the ballpoint pen refill is projected and retracted from the front end opening of the shaft cylinder by operating the slide, or the clip part provided on the shaft cylinder is slid. By doing so, it is possible to exemplify a configuration in which the writing tip of the ballpoint pen refill is projected and retracted from the opening at the front end of the shaft cylinder.
The capless ballpoint pen may be a composite type capless ballpoint pen in which a plurality of ballpoint pen refills are accommodated in a shaft cylinder.
The ink storage tube and the shaft cylinder constituting the ballpoint pen refill may be made of resin or metal.

The back end of the ink stored in the ballpoint pen refill can be filled with an ink backflow prevention body.
The ink backflow prevention body composition is composed of a non-volatile liquid or a hardly volatile liquid.
Specifically, petroleum jelly, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Examples thereof include polyether-modified silicone oil and fatty acid-modified silicone oil, and one or more can be used in combination.

It is preferable to add a gelling agent to the nonvolatile liquid and / or the hardly volatile liquid to increase the viscosity to a suitable viscosity. The surface of the silica is hydrophobized, the surface is methylated fine particle silica, and aluminum silicate. , Swellable mica, hydrophobic thickeners such as bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide modified Examples include dextrin compounds such as polyethylene wax, hydrogenated castor oil, fatty acid dextrin, and cellulose compounds.
Furthermore, the liquid ink backflow prevention body composition and a solid ink backflow prevention body composition can be used in combination.

The following table shows the formulation of the water-based ink composition for capless ballpoint pens.
In addition, the numerical value in a table | surface shows weight%.

The contents of the raw materials in the table are explained according to the note numbers.
(1) Made by Orient Chemical Industry Co., Ltd., trade name: Water Black 100-L, dye content 20%
(2) Eisen Co., Ltd., trade name: Phloxine (3) Sanki Co., Ltd., trade name: Kelzan (4) Degree of polymerization (n) = 2-6
(5) Product name: NV-2P / RC, manufactured by IPS Japan Co., Ltd.
(6) Product name: CHP, manufactured by IPS Japan Ltd.
(7) Ube Industries, Ltd., trade name: Caprolactam (8) Ethanolamine salt of polyoxyethylene octyl ether phosphate, Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf M208B
(9) Sugar mixture containing 73.5% or more starch saccharified product of 10 sugars or more, manufactured by Hayashibara Shoji Co., Ltd., trade name: SANDEC 30

  A water-based ink composition for a capless ball-point pen is obtained by stirring the composition shown in each Example and Comparative Example with a mixer for 1 hour while heating at 60 ° C., and then cooling and filtering.

Production of Caps Ballpoint Pen Each of the ink compositions is filled with an ink containing tube fitted with one end of a polypropylene pipe with a stainless steel tip that holds a ball having a diameter of 0.4 mm. A ballpoint pen refill was obtained by intimately filling the ink backflow prevention body.
The ballpoint pen refill was incorporated into a shaft tube to obtain a capless ballpoint pen.
The capless ballpoint pen is housed in the shaft cylinder with the writing tip provided on the ballpoint pen refill exposed to the outside air, and a cap mechanism (knock mechanism) provided at the rear end of the shaft cylinder. This is a structure in which the writing tip protrudes from the axial tube opening by operation.

Dry-up test After the capless ballpoint pen obtained as described above was left standing at 25 ° C. for 60 days in an inverted state (the writing tip was downward), the writing tip was protruded from the shaft tube opening by the operation of the retracting mechanism. The handwriting was visually observed.
Sagging test The capless ballpoint pen obtained as described above was left in an inverted state (the tip of the writing was facing down) in an atmosphere at a temperature of 25 ° C. and a relative humidity of 90% for 20 hours, and then the appearance of the writing tip was visually observed. Observed.
Each x value of the ink composition [viscosity when water in the ink is evaporated by 40% by weight with respect to the total amount of ink / initial ink viscosity (measured at EMD viscometer, 1 rpm, 20 ° C.)) and dry-up resistance Test results and sag test results are shown in the following table.

The determination results in the table are as follows.
Dry-up resistance test A: A good handwriting that is uniform and not blurred is obtained.
○: Handwriting without blur is obtained.
X: A blur is seen in a handwriting.
Dripping test A: No ink leakage (dripping) is observed.
○: A slight drop of ink is observed at the tip of the chip.
X: Large ink droplets are observed at the tip of the chip, or ink leaking from the tip of the chip is falling.

Claims (11)

  An ink composition that is contained in a capless ballpoint pen where the writing tip of the ballpoint pen refill appears and disappears from the opening at the front end of the barrel by the operation of the intrusion mechanism, and includes a dye, water, a shear thinning agent, and a polymerization degree Is an aqueous solution for capless ballpoint pens comprising at least a thickening inhibitor selected from oligomers of N-vinyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, and ε-caprolactam Ink composition.   The water-based ink composition for capless ballpoint pens according to claim 1, comprising 1 to 40% by weight of the thickening inhibitor.   The water-based ink composition for capless ballpoint pens according to claim 1 or 2, wherein the shear thinning agent is a polysaccharide.   The water-based ink composition for capless ballpoint pens according to claim 3, wherein the shear thinning agent is selected from xanthan gum, welan gum, and succinoglycan.   The water-based ink composition for capless ball-point pens according to any one of claims 1 to 4, comprising a sugar mixture containing 40% by weight or more of 10 or more sugars.   The water-based ink composition for capless ball-point pens according to claim 5, wherein the sugar mixture is a starch saccharified product or a reduced starch saccharified product.   The water-based ink composition for capless ballpoint pens according to claim 5 or 6, comprising 0.5 to 10% by weight of the sugar mixture.   The water-based ink composition for capless ball-point pens according to any one of claims 1 to 7, which does not contain a water-soluble organic solvent.   The water-based ink composition for capless ball-point pens according to any one of claims 1 to 7, comprising a water-soluble organic solvent, wherein the water-soluble organic solvent is 10% by weight or less based on the total amount of the ink composition.   The water-based ink composition for a capless ballpoint pen according to any one of claims 1 to 9 is accommodated in a ballpoint pen refill, and a writing tip portion of the ballpoint pen refill appears and disappears from the front end opening of the shaft cylinder by operation of a retracting mechanism. Capless ballpoint pen.   The capless ball-point pen according to claim 10, wherein an ink backflow prevention body that follows the ink consumption is disposed at a rear end of the water-based ink composition for the capless ball-point pen.