JP2007145969A - Water-based ink composition for ballpoint pen and ballpoint pen incorporating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a water-based ink composition for a ballpoint pen, which hardly accelerates ball corrosion with time, keeps excellent lubricating performance in writing and has an excellent condition of pen and to provide a ballpoint pen having the water-based ink composition incorporated therein. <P>SOLUTION: The water-based ink composition for a ballpoint pen comprises at least a colorant, water, a lubricant and an α-lipoic acid. The amount of the α-lipoic acid added is 0.05-5 wt.% in the total of the ink composition. The ballpoint pen has the water-based ink composition for ballpoint pen incorporated therein. In the ballpoint pen, a cemented carbide composed of at least tungsten carbide and a binder is applied to the writing tip part. <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 that has excellent ball corrosion resistance and high writing performance, and a ballpoint pen incorporating the same.

Conventionally, as balls for ballpoint pens, balls such as silicon carbide balls, zirconia balls, cemented carbide balls, etc., containing silicon carbide, zirconia, tungsten carbide, etc. as the main component and a binder composed of metal as the other component, have been used. in use.
Since the balls mainly use metals such as cobalt, chromium, titanium, and nickel as binders, when used in water-based ballpoint pens, the binders may deteriorate over time due to corrosive components such as dissolved oxygen in the ink. When the binder is lost from the ball, the crystal particles such as silicon carbide, zirconia, and tungsten carbide, which are the main components, drop off, or the eluted binder becomes a metal oxide and becomes insoluble. There may be a so-called corrosion state such as adhesion to the ball surface. Since the corrugation on the surface of the ball becomes large due to the corrosion, the rotation of the ball is obstructed and the writing feel becomes heavy, and the smooth outflow of the ink is obstructed and the handwriting is blurred.
In particular, among the cemented carbide balls mainly composed of tungsten carbide, balls using metals such as cobalt and nickel as binders have a disadvantage that they are easily corroded over time due to the high binder content. Have.
Therefore, as a method for preventing the above-described corrosion over time, a method of adding a sulfide compound into the ink is disclosed (for example, see Patent Document 1).
JP 2004-115684 A

  However, when the sulfide compound is added, it may cause odor or may precipitate over time, so that it is difficult to obtain a sufficient corrosion-inhibiting effect, resulting in poor writing quality and faint writing. It was not enough to prevent problems.

  The present invention provides a water-based ink composition for a ballpoint pen that has good writing quality and that can maintain excellent lubrication performance during writing, and a ballpoint pen incorporating the same.

The water-based ink composition for ballpoint pens of the present invention is required to contain at least a colorant, water, a lubricant, and α-lipoic acid.
Furthermore, it is required that the α-lipoic acid is added in a range of 0.05 to 5% by weight based on the total amount of the ink composition.
Furthermore, the ball-point pen incorporating the water-based ink composition for ball-point pens and the ball-point pen are required to apply a cemented carbide ball made of at least tungsten carbide and a binder to the writing tip.

  According to the present invention, in water-based ballpoint pens, it is possible to suppress corrosion phenomena such as elution of binding materials and adhesion of insoluble materials to the ball surface for a long period of time, and maintain high lubricating performance during writing. An ink composition for a water-based ballpoint pen that can maintain a smooth writing feeling without causing line skipping and a ballpoint pen incorporating the ink composition can be provided.

  Even when the present invention is applied to a ballpoint pen comprising a cemented carbide ball at the tip of writing by containing α-lipoic acid in the water-based ink composition for ballpoint pens, the corrosion phenomenon of the ball surface is prolonged. It can be suppressed.

The corrosion phenomenon is caused by substances that generate active oxygen species contained in water-based inks, such as dyes used as colorants, resin particles containing dyes, phenols used as additives, compounds having phenolic hydroxyl groups, and naphthalene derivatives. Active oxygen species are generated by photosensitizing action on acridine derivatives, benzothiazole derivatives, benzophenone derivatives, naphthoquinone derivatives, anthraquinone derivatives, etc., and action of reducing substances on dissolved oxygen in ink. Is presumed to act on the ball at the tip of the writing.
Therefore, by adding the α-lipoic acid to the ink, the α-lipoic acid acts on the active oxygen species to suppress ball corrosion.
The active oxygen species refers to singlet oxygen, superoxide anion radical, hydrogen peroxide, hydroxy radical, alkyl radical, hydroperoxide radical, and the like.

The α-lipoic acid can be 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 it is added in excess of 5% by weight, no improvement in corrosion inhibition effect is observed, so no further addition is required.

  As the lubricant, a general-purpose lubricant can be used as long as it suppresses seat wear during writing and can provide lubrication performance. Specifically, metal soap, polyalkylene glycol fatty acid ester, ethylene oxide addition type cationic surfactant, phosphate ester surfactant, thiocarbamate, dimethyldithiocarbamate, N-acylamino acid, N-acylmethyltaurine Etc. can be illustrated.

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.

Further, if necessary, a conventional general-purpose water-soluble organic solvent compatible with water can be used. Specifically, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol mono Examples include ethyl 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, as necessary, inorganic salts such as sodium carbonate, sodium phosphate, sodium acetate, pH adjusters such as organic basic compounds such as water-soluble amine compounds, rust preventives such as benzotriazole, tolyltriazole, 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) pyridine Preservatives or antifungal agents such as urea, nonionic surfactants, sorbitol, mannitol, sucrose, glucose, reduced starch hydrolyzate, wetting agents such as sodium pyrophosphate, antifoaming agents, ink permeability A fluorine-based surfactant or a nonionic surfactant to be improved 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 is applied after adjusting the pH to a weakly acidic to alkaline region of 5 to 13, preferably from about 6 to 10 neutral to weakly alkaline region.
By adjusting to the pH, α-lipoic acid can efficiently suppress ball corrosion due to active oxygen species.

Furthermore, an ink backflow preventer (liquid stopper) can be disposed at the rear end of the ink composition filled in the ink containing tube.
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 water-based ink composition for ballpoint pens has a more effective general-purpose mechanism than before, and a ball in which the vicinity of the tip end of a metal pipe is pressed and deformed inward from the outer surface. A chip formed by holding a ball in the holding part, a chip formed by holding a ball in a ball holding part formed by cutting a metal material with a drill or the like, or a metal pipe or metal material A ball or the like held by a chip formed by cutting can be applied forward by a spring body.

The ball is obtained by sintering a group 4a, 5a, 6a metal or a carbide thereof together with a metal such as cobalt or nickel as a binder, and is made of a cemented carbide that is hard and difficult to wear. Applies.
In particular, a cemented carbide ball using tungsten carbide (tungsten carbide), which is chemically stable and has high hardness, among the metals of Group 4a, 5a, and 6a or carbides thereof, is preferably used.
In addition, titanium, vanadium, chromium, tantalum or a carbide thereof may be included as a metal of 4a, 5a, or 6a group.
Among the binders, particularly cobalt is easily eluted in the water-based ink, so that the ball surface becomes rough, and further, tungsten carbide falls off due to the elution of cobalt, and the ball surface becomes even rougher. As a result, if the ball rotates while in contact with the ball seat, the wear of the seat becomes severe, so the writing feeling is impaired, and the gap between the ball and the ball holding portion in the axial direction (clearance) increases, causing ink outflow. Increasing the amount tends to cause problems such as thick handwriting and line skipping.
The balls having a diameter in the range of 0.1 mm to 2.0 mm are preferably used.

For example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate is preferably used as the shaft cylinder that accommodates the water-based ink composition in terms of low ink evaporation and productivity.
In addition to directly connecting the tip to the shaft tube, the shaft tube and the chip may be connected via a connecting member.
When the ink composition is low in viscosity, the ink composition accommodated in the shaft cylinder includes a method of mounting an ink retaining member at the front of the shaft cylinder and storing the ink composition directly in the shaft cylinder, Examples of the method include impregnating the ink composition into a material body or a fiber processed body.
In addition, the said shaft cylinder may accommodate the said refill in a shaft cylinder as a form of the refill for ball-point pens.

Furthermore, by using a transparent, colored transparent, or translucent molded body as the ink containing tube, the ink color, the remaining amount of ink, and the like can be confirmed.
The ink storage tube may be configured as a ballpoint pen refill, in which the refill is stored in a shaft tube, or the shaft tube with a tip attached to a tip is used as an ink storage body in the shaft tube. You may fill ink directly.

Examples will be described below, but the present invention is not limited to these examples.
The composition of the water-based ink for ballpoint pens of Examples and Comparative Examples is shown in the following table. In addition, the numerical value of a composition in a table | surface shows a weight part.

The contents of the raw materials in the table will be described along the note numbers.
(1) Product name: Acid Blue PG, manufactured by Sumitomo Chemical Co., Ltd.
(2) Hodogaya Chemical Co., Ltd., trade name: Phloxine (3) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL
(4) Made by Sanki Co., Ltd., trade name: Leozan (5) Diethylhydroxylamine (6) Made by Toyo Fermentation Co., Ltd., trade name: α-lipoic acid (7) Sodium dimethyldithiocarbamate

Preparation of Ink Add ingredients other than shear thinning agent to water, mix and stir, then add those containing shear thinning agent, and stir at 25 ° C with a disper at 400 rpm for 1 hour. Each ink was prepared by filtration.

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.

Production of Ballpoint Pen A A stainless steel chip holding the WC-Co type cemented carbide ball A having a diameter of 0.3 mm is formed from a polypropylene pipe (inner diameter 3). (8 mm) was filled in a ballpoint pen refill, and the ink backflow preventer was disposed at the rear end thereof. Then, the ballpoint pen refill was assembled into a shaft tube to prepare a sample ballpoint pen A.

Production of Ballpoint Pen B The ink composition of Example 3 and Comparative Examples 4 and 5 was accommodated in a shaft cylinder, and a stainless steel chip holding a WC-Co cemented carbide ball A having a diameter of 0.5 mm was written. A sample ballpoint pen B was produced by incorporating a comb-like ink retaining member (pen core) attached to the tip.

The following tests were conducted using the ink composition and the sample ballpoint pen.
Ball Corrosion Test 5 g of each prepared ink was transferred to a sample bottle, and two kinds of cemented carbide balls (A: WC-Co type, B: WC-Ni type) were dipped and capped. It was left for 30 days in an environment of ° C. Then, the state of each ball | bowl surface was confirmed with the optical microscope (1000-times multiplication factor) at room temperature.

Written test Written feeling when a sample ballpoint pen that has been confirmed to be writable is left in a 50 ° C environment for 60 days in a horizontal position and then handwritten on a JIS P3201 writing paper A. And the handwriting state by visual observation was confirmed.
The results of the test are shown in the following table.

The evaluation of the test results is as follows.
Ball corrosion test ○: No change from the initial stage.
(Triangle | delta): The glossiness was lost compared with the initial stage.
X: The surface is rough compared with the initial stage, or there is precipitation or deposits.
Writing test ○: Writing was smooth and good handwriting was shown.
(Triangle | delta): There exists a feeling of being caught at the time of writing, and a slight blur and a line jump are seen in a handwriting.
X: Written feeling is poor, and many blurs and line jumps are seen in the handwriting, or writing is impossible.

Claims (4)

  A water-based ink composition for ballpoint pens comprising at least a colorant, water, a lubricant, and α-lipoic acid.   The water-based ink composition for ballpoint pens according to claim 1, wherein the α-lipoic acid is added in an amount of 0.05 to 5% by weight based on the total amount of the ink composition.   A ballpoint pen incorporating the water-based ink composition for ballpoint pens according to claim 1 or 2.   4. The ballpoint pen according to claim 3, wherein the ballpoint pen applies a cemented carbide ball made of at least tungsten carbide and a binder to the writing tip.