JP2008013722A - Aqueous ink composition for ballpoint pen and ballpoint pen including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous ink composition for a ballpoint pen, hardly causing progress of ball corrosion with time, maintaining the excellent smooth properties at writing and providing good writing condition, and to provide the ballpoint pen including the ink. <P>SOLUTION: The aqueous ink composition for the ballpoint pen at least contains a coloring matter, water and a 4-8C organic acid free from a hydroxy group, and has a pH within a range of 2-7. The organic acid is preferably at least one kind selected from glutaric acid, tricarballylic acid, adipic acid and 1,2,3,4-butanetetracarboxylic acid. The ballpoint pen includes the aqueous ink composition for the ballpoint pen. <P>COPYRIGHT: (C)2008,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., which contain silicon carbide, zirconia, tungsten carbide, etc. as a main component and a metal binder as another 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 in an acidic medium or over a long period of time, so that it is difficult to sufficiently obtain a corrosion inhibiting effect, resulting in poor writing quality and handwriting. It was insufficient to prevent problems such as fading.

  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 a ballpoint pen of the present invention contains at least a colorant, water, and an organic acid having 4 to 8 carbon atoms that does not have a hydroxy group, and is required to have a pH in the range of 2 to 7. And
Furthermore, it is a requirement that the organic acid is at least one selected from glutaric acid, tricarballylic acid, adipic acid, and 1,2,3,4-butanetetracarboxylic acid.
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.

  In the present invention, a water-based ink composition for ballpoint pens having a pH of 2 to 7 is added with an organic acid having 4 to 8 carbon atoms having no hydroxyl group, so that the tip of the writing is super hard. Even when applied to a ballpoint pen having an alloy ball, the corrosion phenomenon of the ball surface can be suppressed for a long period of time.

As the organic acid, one having no hydroxyl group and having 4 to 8 carbon atoms (preferably having 5 to 8 carbon atoms) is used, and effectively exhibits a corrosion inhibiting effect in an acidic atmosphere.
Specific examples of the organic acid include butyric acid, succinic acid, maleic acid, glutaric acid, tricarballylic acid, adipic acid, 1,2,3,4-butanetetracarboxylic acid, and the like. Of these, glutaric acid is optimal because a high effect can be obtained by adding a small amount.

The organic acid can be added in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the total amount of the ink composition.
If it is less than 0.1% 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 corrosion inhibition effect 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 and are stable under acidic conditions can be used.
Examples of the dye include chrysoidine (C.I. 11270), methyl violet FN (C.I. 42535), crystal violet (C.I. 42555), malachite green (C.I. 42000), Victoria Blue FB (C Basic dyes such as rhodamine B (C.I. 45170), acridine orange NS (C.I. 46005), and methylene blue B (C.I. 52015) are preferably used.
Also, discoloration or discoloration with reducing agents such as methine dyes, trimethylmethane dyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, cyanine dyes, azo dyes, anthraquinone dyes, cyanine dyes Dyes can also be used.
As the pigment, in addition to inorganic pigments and organic pigments, water-dispersed pigment products that are finely and stably dispersed in an aqueous medium in advance using a surfactant or the like are used, as well as pearl pigments, gold-colored and silver-colored pigments. Metallic pigments, luminous pigments, white pigments such as titanium dioxide used for correction pens, metal powders such as aluminum, fragrances or fragrance capsule pigments can be 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.

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 use together 1 type, or 2 or more types, It is 2 to 60 weight%, Preferably it is used in 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, in order to adjust the pH of the ink to the acidic region (pH 2 to 7), formic acid, acetic acid, propionic acid, lactic acid, oxalic acid, succinic acid, malic acid, citric acid, tartaric acid, malonic acid, phosphoric acid, phosphorous acid Acids, carbonic acid, sulfonic acids such as paratoluenesulfonic acid, and acidic substances such as glycolic acid, gluconic acid, hydrochloric acid, sulfuric acid, and nitric acid can be used in combination.

  Furthermore, in order to adjust the pH of the ink after the addition of the acidic substance to a desired range, an alkaline substance can be added, and those that exhibit weak alkalinity are particularly preferably used. Examples of the alkaline substance include phosphates such as disodium hydrogen phosphate and trisodium phosphate, carbonates such as sodium carbonate and sodium hydrogen carbonate, alkanolamines such as ammonia and triethanolamine, sodium hydroxide, water Examples thereof include hydroxides such as potassium oxide.

  In addition, if necessary, metal soap, polyalkylene glycol fatty acid ester, ethylene oxide addition type cationic surfactant, phosphate ester surfactant, N-acylamino acid, N-acylmethyltaurine and other lubricants, sodium carbonate, PH adjusters such as inorganic salts such as sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, rust preventives such as benzotriazole, tolyltriazole and saponin, coalic acid, 1,2-benzthiazoline 3 -Preservatives or antifungal agents such as sodium salt of -one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, Urea, nonionic surfactant, sorbit, mannit, sucrose, How sugar, reduced starch hydrolyzate, wetting agents such as sodium pyrophosphate, defoamers, may be used surfactants fluorosurfactants to improve the ink permeability and nonionic.

  In addition, a shear thinning agent can be added to the ink composition. For example, xanthan gum, welan gum, or a constituent monosaccharide that is soluble or dispersible in water is an organic acid-modified heteropolysaccharide of glucose and galactose. Succinoglycan (average molecular weight of about 1 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, Glycomannan, thickening polysaccharide with gelling ability extracted from seaweed such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymer, inorganic fine particles etc. are used alone or in combination can do.

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.
In general, those using cobalt as the binder are easily eluted in 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. However, when the water-based ink of the present invention is applied, the elution of cobalt into the ink is suppressed, and the above-described problems are hardly caused.
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.
In the case where the ink composition accommodated in the shaft cylinder has shear thinning viscosity, the ink composition is directly accommodated in the shaft cylinder, and the ink backflow preventer is in contact with the rear end of the ink composition. The method of arrange | positioning is taken. In addition, when the ink composition has a low viscosity, a method of mounting an ink retaining member on the front of the shaft cylinder and storing the ink composition directly in the shaft cylinder, the porous composition or the fiber processed body with the ink composition There are a method of impregnating and storing, and a method of storing the ink composition directly in the shaft cylinder and disposing an ink backflow preventer in contact with the rear end of the ink.
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) Made by Clariant Japan Co., Ltd., trade name: Juadine Ink Blue SLK
(2) Product name: SWT Red-4, manufactured by Hodogaya Chemical Co., Ltd.
(3) Product name: SWT Orange-1 manufactured by Hodogaya Chemical Co., Ltd.
(4) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf A212E
(5) Product name: Prisurf A217E, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
(6) Product name: PBC-34, manufactured by Nikko Chemicals Co., Ltd.
(7) Product name: S-141, manufactured by Seimi Chemical Co., Ltd.
(8) Product name: Leozan, manufactured by Sanki Co., Ltd.

Preparation of ink After adding ingredients other than the shear thinning agent to water and mixing and stirring, those containing the shear thinning agent were added and stirred at 20 ° 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 The stainless steel tip holding the WC-Co cemented carbide ball having a diameter of 0.5 mm was fitted to one end of a polypropylene pipe (inner diameter: 3.8 mm) with the ink compositions of the above examples and comparative examples. The ball pen refill was filled and the ink backflow preventer was disposed at the rear end thereof, and then the ball pen refill was incorporated into a shaft tube to prepare a sample ball pen.

The following tests were conducted using the ink composition and the sample ballpoint pen.
Ball Corrosion Test 3 g of each prepared ink was transferred to a sample bottle, a cemented carbide ball equivalent to that used for the ballpoint pen (WC-Co system) was immersed in the ink, capped, and the environment at 70 ° C. Left for 7 days and 30 days. Thereafter, the reducing agent was added to the ink at room temperature to erase the color, and the amount of cobalt eluted in the ink was confirmed using a semi-quantitative ion test paper.

Written test The sample ball-point pen that was confirmed to be writable was allowed to stand for 7 and 30 days in a 70 ° C environment with the pen tip facing down, and then a hand-written spiral circle was continuously written on JIS P3201 writing paper A. The writing feeling at the time and the handwriting state by visual observation were confirmed.
The results of the test are shown in the following table.

The evaluation of the test results is as follows.
Ball corrosion test ○: Cobalt elution amount per ball is less than 2% of the ball weight.
Δ: Cobalt elution amount per ball is 2% or more and less than 6% of the ball weight.
X: Cobalt elution amount per ball is 6% or more of the ball weight.
Writing test ○: Writing was smooth and good handwriting was shown.
Δ: Although there is a slight catching feeling at the time of writing, there is no practical problem. Or, a slight blur is seen in the handwriting, but there is no practical problem.
X: Written feeling is poor, and many blurs and line jumps are seen in the handwriting.

Claims (4)

  A water-based ink composition for ballpoint pens, comprising at least a colorant, water, and an organic acid having 4 to 8 carbon atoms having no hydroxy group and having a pH in the range of 2 to 7.   The water-based ink composition for a ballpoint pen according to claim 1, wherein the organic acid is at least one selected from glutaric acid, tricarballylic acid, adipic acid, and 1,2,3,4-butanetetracarboxylic acid.   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.