JPH04214782A - Ink composition for water based ball-point pen - Google Patents

Abstract

PURPOSE:To provide the title composition causing no ink spill, excellent in ink deliverability, also prevented from nib cloggings due to pigment sedimentation, containing a specified amount of specific water-soluble natural polymeric polysaccharide(s) (gellan gum). CONSTITUTION:The objective composition containing 0.01-4.0 (pref. 0.05-2.0) wt.% of polymeric polysaccharide(s) of formula I and/or formula II (M is Na, K or 1/2Ca; n is 1000-3000). The other ingredients to be incorporated are e.g. water-soluble or water-dispersible colorant, surfactant, rustproofing agent, preservative, pH adjuster, viscosity regulator, dispersion stabilizer, water-soluble organic solvent and water, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition for a water-based ballpoint pen.

0002

[Prior Art and Problems to be Solved by the Invention] Water-based ballpoint pens have been widely used in recent years because they have a lighter writing feel than oil-based ballpoint pens, draw thicker lines, and do not bleed. Became. The ink of a water-based ballpoint pen must have appropriate viscosity and flowability, be free from problems such as ink running out, ink scum formation, ink leakage, etc., and have cap-off properties (the ballpoint pen can be used for a long time without the cap removed). It is necessary to have properties such as being able to be written over a wide area), drying handwriting quickly, and having excellent metal corrosion resistance and storage stability.

[0003] Water-based ink compositions utilize water-releasing gel-forming polymeric substances (polymer substances that dissolve in water or form a hydrogel when added with water and heated if necessary) such as polyvinyl alcohol and carrageenan. A method for doing so is disclosed in Japanese Patent Application Laid-Open No. 56-74164. However, although this ink composition is suitable for writing instruments that utilize capillary action such as water-based marking pens and felt-tip pens, it has problems such as ink leakage and poor cap-off properties in cartridge-type water-based ballpoint pens. was there.

[0004] As another example of a water-based ink composition, one using xanthan gum, which is a water-soluble polymeric polysaccharide with a molecular weight of about 5 million to 10 million, has been disclosed (
For example, JP-A-59-74175 and JP-A-62-
(See Publication No. 48777). This conventional technology has achieved properties that water-based ballpoint pen inks should have, such as having appropriate viscosity and flowability through the use of xanthan gum, and being free from problems such as ink running out, ink scum formation, and ink leakage. It is possible to provide a water-based ballpoint pen with the following features.

[0005] However, xanthan gum has the property of making pigment dispersion somewhat unstable, so if xanthan gum is used in a pigment dispersion system for a long period of time, the pigment may gradually settle due to dispersion destruction. In this case, there was a problem that the use of pigments was restricted.

An object of the present invention is to provide an ink composition for a water-based ball-point pen that does not cause ink leakage even when used in a cartridge-type water-based ball-point pen, and that causes almost no pigment sedimentation even when used in a pigment dispersion system.

[0007]

[Means for Solving the Problems] The present inventor conducted research while taking into account the problems of the prior art described above, and as a result, the water-based ink composition containing welan gum was further improved as an ink for ballpoint pens. The inventors have discovered that this effect can be achieved and have completed the present invention.

That is, the present invention relates to an ink composition for a water-based ballpoint pen having the following general formula:

[0009]

embedded image [wherein M represents an alkali metal or alkaline earth metal selected from sodium, potassium and 1/2 calcium, and n is 1000 to 3000. ] An aqueous ballpoint pen ink composition comprising 0.01 to 4.0% by weight of a polymeric polysaccharide represented by the following.

[0010] The water-soluble natural polymeric polysaccharide represented by the above general formula (1) used in the present invention (common name: welan gum)
has pseudoplastic properties, stringability and lubricity. Therefore, by using the polymeric polysaccharide,
The ink composition has pseudoplastic properties and is given appropriate viscosity and flowability. That is, since the ink viscosity is high in the ink tank, the ink does not leak from the pen tip, but when writing, shearing force is applied by the rotation of the ball and the ink viscosity decreases, so the ink flows out easily. Examples of the high molecular weight polysaccharide include K1A
96 (manufactured by Sansho Co., Ltd.) and the like can be used. The amount of the polymeric polysaccharide used is 0.01 to 4.0% by weight, preferably 0.05 to 4.0% by weight in the ink composition.
The amount is 2.0% by weight. The amount of polymer polysaccharide used is 0.01
If it is less than 4.0% by weight, the viscosity of the ink will be low and the ink will easily leak from the pen tip;
If the ink exceeds this value, the viscosity becomes too high and the outflow of ink from the pen tip tends to be inhibited.

[0011] In particular, when the amount of high molecular weight polysaccharide used is 0.05~
When the content is within the preferred range of 2.0% by weight, satisfactory properties will be exhibited as a water-based ballpoint pen, regardless of the combination of materials, composition, and structure of the pen.

[0012] As for the components other than the above-mentioned polymeric polysaccharide in the aqueous ballpoint pen ink composition of the present invention, the same components as those of known aqueous ballpoint pen inks can be used. That is, the ink composition of the present invention contains, for example, 0.01 to 4.0% by weight of the polymeric polysaccharide of general formula (1), 0.1 to 15% by weight of a water-soluble or water-dispersible colorant, and a surfactant. , 0.01 to 10% by weight of appropriate additives such as rust preventives, preservatives, pH adjusters, viscosity modifiers, and dispersion stabilizers, and 5 to 10% by weight of water-soluble organic solvents.
It is composed of 40% by weight and/or the balance water.

Examples of water-soluble or water-dispersible colorants include known water-dispersible pigments and/or water-soluble dyes, and one or more of the following may be used. If the amount used is too small, color development will be small, and if it is too large, precipitation will easily occur in the case of pigments, and it will be difficult to dissolve in the case of dyes.

As the water-dispersible pigment, dispersion-stable pigments treated with a polymer made of a monomer containing both a hydrophilic group and a hydrophobic group in one molecule can be suitably used, and titanium oxide, carbon Inorganic pigments such as black, carmine 6B, C.I.
I. Pigment Red 112, C. I. Pigment Blue 15, C. I. Examples include organic pigments such as Pigment Green 7. As water-soluble dyes, C.I. I
．． Acid Red 18, 87, 92, C. I. Acid Orange 56, C. I. Acid Yellow 28, Acid Blue 7, Acid Yellow 9, C. I. acid violet 4
9.C. I. Acidic dyes such as Acid Black 2, C.I. I
．． Direct Orange 6, C. I. Direct Yellow 44, Direct Yellow 87, C. I. Direct black 19, same 7
Examples include direct dyes such as No. 1, No. 88, and No. 154.

As surfactants, polyethylene glycol alkyl ether, polyethylene glycol alkyl phenyl ether, polyethylene glycol polypropylene glycol ether, ethylene oxide adduct of 2,4,7,9-tetramethyl-5-alkyl-4,7-diol are used. , nonionic surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl phosphates, polyether-modified silicone oil; and anionic surfactants such as naphthalene sulfonic acid formalin condensates, perfluoroalkyl ethylene oxide adducts, etc. I can give an example.

Examples of the rust preventive include benzotriazole, tolyltriazole, dicyclohexylammonium nitrate, and the like.

Examples of preservatives include potassium sorbate, sodium benzoate, sodium pentachlorophenol, sodium dehydroacetate, and 1,2-benzisothiazolin 3-one.

Examples of the fungicidal agent include 2,3,5,6-tetrachloro-4(methylsulfonyl)pyridine and benzimidazole compounds.

As the pH adjuster, sodium hydroxide,
Examples include sodium carbonate.

[0020] Examples of the viscosity modifier include gum arabic, dextrin, polyvinyl alcohol, and xanthan gum.

Examples of the dispersion stabilizer include styrene acrylic resins, styrene maleic acid resins, acrylic methacrylic acid resins, and the like.

The water-soluble organic solvent acts as a solvent and a wetting agent, and one or more of the following are used. If the amount of the water-soluble organic solvent used is too small, the storage stability and cap-off properties of the ink composition will be reduced, and if it is too large, the viscosity will increase and bleeding may occur.

Examples of water-soluble organic solvents include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,8-propanediol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, and 2,3-butanediol. Butylene glycol, neopentyl glycol, hexylene glycol,
Dihydric alcohols such as thiodiglycol; polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, 3-methylpentane-1,3,5-triol, diglycerin, sorbitol; ethylene glycol monomethyl ether, ethylene glycol mono Glycol ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; pyrrolidone; N-methyl-2-pyrrolidone, dimethylformamide, and the like.

The ink composition of the present invention containing the polysaccharide of general formula (1) as an essential component is not limited to the above composition, and compositions containing components other than the above are also included within the scope of the present invention. . For example, urea may be further added for the purpose of promoting dye solubility and improving cap-off properties.

The ink composition of the present invention is produced, for example, as follows. Gradually add the above-mentioned polymeric polysaccharide to water under stirring at room temperature and dissolve it completely, then add a water-soluble organic solvent, a coloring agent and appropriate additives to uniformly dissolve or disperse it, and as necessary. and filter.

The ink composition of the present invention is particularly suitable as an ink for an ink-free water-based ballpoint pen.

[0027]

As the ink composition of the present invention has pseudoplastic properties, the ink viscosity is high in the ink tank, so that the ink does not leak from the pen tip. However, during writing, the ink viscosity decreases due to the rotation of the ball, so the ink flows out easily. Furthermore, it has the advantage that ink scum does not adhere to the pen tip, handwriting dries quickly, and it has excellent storage stability. Furthermore, since it has almost no effect on pigment dispersion, water-based ballpoint pens can be used for long periods of time even when pigments are used, and clogging at the tip of the tip due to pigment settling can be reliably avoided. Became.

[0028]

[Examples] The present invention will be explained in more detail with reference to Examples and Comparative Examples below.

[0029]

[Examples 1 to 10 and Comparative Examples 1 to 4] Ink compositions were produced using the raw materials shown in Table 1, and the ink leakage, ink flowability, and dryness of handwriting were observed. Second result
Shown in the table.

[0030] The shape of the ballpoint pen used here is as shown in Figure 1, and the observation was carried out after the ballpoint pen of this shape was stood vertically with the tip facing down and left at room temperature for 2 months. Ta. . Pen nib (5): Made of nickel silver, it has an ink outlet hole with a diameter of 1.5 mm and a length of 7 mm. Ball (7)...Carbide ball with a diameter of 0.6 mm. Ink tank (9): Made of polypropylene, the inner diameter is 4 mm, and the length of the tank portion is 110 mm.

As is clear from Table 2, the ink composition of the present invention did not leak, had good ink flow properties and drying properties of handwriting, and was excellent as an ink composition for a water-based ballpoint pen. When the polymeric polysaccharide of general formula (1) is used outside the range specified in the present invention, if too little is used (
Comparative Example 4) was poor in terms of ink leakage, ink flowability, and handwriting dryness; when too much (Comparative Example 5), ink flowability and handwriting dryness were poor. In addition, ink compositions using xanthan gum (Comparative Example 1), ramsan gum (Comparative Example 2), or locust bean gum (Comparative Example 3) instead of the polymeric polysaccharide (1) have some difficulty in ink flowability. Even in Comparative Example 1 and Comparative Example 2, which obtained relatively good results, when the ink leakage and dryness of the handwriting were adjusted to a good state, the writing was slightly faded under the condition of being left at room temperature for 2 months. 1) Ink leakage: It was investigated whether ink leaked from the pen tip during normal writing. No leakage was rated as ○, and leakage was rated as ×. 2) Ink flowability after being left at room temperature for 2 months: The ink flowability was examined by hand after being left at room temperature for 2 months with the pen tip facing downward in a vertical position. 3) Dryness of handwriting: After writing the letter "V" on high-quality paper, the time required for the handwriting to dry to the touch was measured. 49 seconds or less: ○, 50
74 seconds was marked as △, and 75 seconds or more was marked as ×.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of a ballpoint pen used in Examples.

[Explanation of symbols]

1 Ballpoint pen body 3 Backflow prevention part 5 Pen tip part 7 Ball 9 Ink storage section

Claims (1)

[Claims] Claims 1: General formula [Formula 1] [wherein M represents an alkali metal or alkaline earth metal selected from sodium, potassium and 1/2 calcium, and n is 1000 to 3000. ] An aqueous ballpoint pen ink composition comprising 0.01 to 4.0% by weight of a polymeric polysaccharide represented by the following.