JPS6155175A - Water-based pigment ink - Google Patents

Abstract

PURPOSE:To improve smoothness in writing, dispersion stability, etc., by blending benzotriazole (derivative) in a specified weight ratio with a water-based pigment ink comprising a pigment, a dispersant, a water-soluble org. solvent, water, etc. and adjusting the pH to a value within a specified range. CONSTITUTION:A pigment (e.g. carbon black), a dispersant (e.g. methacrylate resin emulsion), a water-soluble org. solvent (e.g. ethylene glycol), water and 0.1-5wt% (based on the entire quantity of ink) benzotriazole (derivative) are mixed together. The pH of the mixture is adjusted to 7-10 with sodium hydroxide or monoethanolamine to obtain the desired water-based pigment ink. The ink is suitable for use as ball point ink and can also be used as ink for writing utensils and an ink jet printer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water-based pigment ink, and more particularly to a water-based ink for ballpoint pens that has excellent writing feel.

(Prior Art) Conventionally, water-based inks for ball bearings have generally used dyes as colorants, but they have had problems such as poor water resistance. On the other hand, recently, water-based pigment ink using pigment as a coloring agent (Special Publication Publication No. 55-3
5454゜Japanese Patent Publication No. 1986-80 '368, % No. 1983
-141256), water-based pigment inks are now being used as inks for ballpoint pens.

(Problems to be Solved by the Invention) However, when conventional water-based pigment inks are used in ballpoint pens, the pole does not rotate smoothly, resulting in blurred handwriting or the pen tip getting caught on the paper surface when writing. The problem is that the taste is often impaired.

The use of surfactants may be considered as a solution to this problem, but if they are added in the amount necessary to obtain the effect, new problems arise such as destruction of the pigment dispersion system and smearing of tracks. Also, polymer carboxylic acids, higher alcohol esters,
It is also possible to use metal soap, but this also causes problems such as destruction of the pigment dispersion system and blurring of handwriting.

None of these have led to a satisfactory solution to the problem.

(Means for Solving the Problems) Therefore, 1. The inventors of the present invention have conducted extensive research in order to solve the above problems.
It was discovered that by adding J amount of IJ azole and/or its derivative to adjust the pH of the ink to 7 to 10 Kp, a water-based pigment ink with excellent writing quality can be obtained when used in a ballpoint pen. It is a completed invention.

That is, 2 the present invention comprises a pigment, 1 a dispersant, a water-soluble organic solvent,
Add benzotriazole and/or its derivatives to an aqueous pigment ink consisting of at least water at 0% based on the total amount of the ink.
．． The gist of this invention is a water-based pigment ink characterized by containing 1 to 5.0% by weight of the pigment and having the PI of the ink adjusted to 7 to 10.

(Function) It is not clear why the aqueous pigment ink of the present invention has excellent writing quality when used with a ballpoint pen, but it is speculated as follows.

The hydrogen atoms of benzo) IJ azoles and/or their 84 forms are active, and the formation of salts with metals, especially copper, is known. Ballpoint pen tips require precision machining, so free-cutting alloys are used. Free-cutting alloys include ferritic or martensitic stainless steel, nickel silver, brass, etc., and the main ball material is tungsten carbide (carbide), so the copper content and benzotriazole in these alloys and/or its derivative force; Reaction (slight reaction with both iron and cobalt components) It is thought that the hydrophobic groups in one molecule of the iron face outward, providing a lubricating effect between the ball and the tip. Also, by adjusting the pH of the ink to 7-10.

Preventing the ionization of benzotriazole and/or its derivatives in a strongly alkaline region, and at the same time allowing the benzotriazole and/or its derivatives to fully exhibit their effects,
It is presumed that this prevents agglomeration due to destruction of the pigment dispersion system in an acidic region and precipitation of dispersants such as resins, resulting in a better writing feel when used in a ballpoint pen.

(Structure of the Invention) Next, each component of the aqueous pigment ink of the present invention will be explained.

The pigment is used as a coloring agent, and all conventionally known organic and inorganic pigments can be used.

To give specific examples, azo pigments, condensed polyazo pigments, phthalocyanine pigments, dioxane pigments, perinone/perylene pigments, quinacridone pigments, carbon black pigments, etc. can be used, and the amount used is the total amount of the ink. 1 to 2% by weight, preferably 3 to 10% by weight.

As the dispersant, commonly used dispersants can be used, and specific examples include acrylic acid, methacrylic acid resin emulsions, vinyl acetate resin emulsions,
Natural resin dispersant.

Examples include nonionic or anionic surfactants.

As the solvent, in addition to water, water-soluble organic solvents used in dye-type water-based inks can be used; specific examples include glycol solvents, glycol ether solvents, and glycol ether ester solvents. , glycerin, pyrrolidone, etc.

Benzotriazole and/or its derivatives are used for the purpose of imparting lubricity to the ink, and the amount used is 01 to 5.0% by weight based on the total amount of the ink. If it is less than 0.1, it will not be effective, and if it is more than 5.0, pigment aggregation will be likely to occur.

The pH of the ink needs to be adjusted to 7-10. P H
When is larger than 10, benzotriazole and/or its derivatives are anionized, making it difficult to exert their effects,
When PI-I is less than 7, the pigment dispersion system is destroyed, and aggregation of pigments and precipitation of dispersants such as resins are likely to occur.

In addition, L)r (as the adjusting alkali, ammonia,
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Suitable examples include alkali metal salts such as potassium carbonate, water-soluble alkanolamines such as monoethanolamine, jetanolamine, and triethanolamine.

In addition to the above-mentioned components, additives such as surfactants for adjusting the surface tension of the preservative 1, dyes for complementary colors, etc. can be used as appropriate.

Also, as an ink for writing instruments, the surface tension is 25 to 45 dy.
It is preferable to adjust it to n/(4).

Next, regarding the method for producing the aqueous pigment ink of the present invention, the above-mentioned components are mixed using two conventional dispersing machines, 9 examples, a ball mill, a roll mill, and a Santo mill.

It can be obtained by mixing, grinding, and dispersing using a super mill, a dyno mill water attritor, or the like.

(Example) The present invention will be described in more detail below with reference to Examples, where "parts" in the examples indicate "parts by weight."

Example 1 Carbon Book 100 parts Ethylene Glycol 200 parts Shellac GSN (shellac.

Gifu Shellac Factory Membrane) 60 parts caustic soda 02 parts urea
100 parts benzotriazole
° i, Q part water
55.8 parts of each of the above ingredients,
Dissolve caustic soda in water, then dissolve shellac GSN, and sequentially add ethylene glycol, urea, benzotriazole, and carbon black to this solution and stir to premix. After 1 hour, it was ground in a ball mill for 20 hours, and then filtered to remove coarse particles.
A black ink was obtained.

Comparative example 1-1 Example 1 except for benzotriazole.

P was prepared in the same manner as in Example 1 except that only the amount of water was added.
A black ink of H9 was obtained.

Comparative Example 1-2 The pH was adjusted to 6 in the same manner as in Example 1, except that the amount of caustic soda was reduced to 0.05 part and water was added.
A black ink was obtained.

Comparative Example 1-6 The pH was adjusted in the same manner as in Example 1, except that the amount of caustic soda was increased to 1.0 parts and the amount of water was reduced accordingly.
No. 11 black ink was obtained.

Example 2 Copper phthalocyanine blue a, o parts Ethylene glycol 10.0 parts Propylene glycol 5.0 parts Jurimer ET-41
0 (acrylic resin emulsion, manufactured by Bhon Junyaku ■) 20.0 parts Monoethanolamine 05 parts Benzotriazole 2.0 parts Emulgen A-60
(Nonionic surfactant, manufactured by Kao Soap) 0.1 part water
54.4 parts P by adding each of the above ingredients in the same manner as in Example 1
A blue ink of H8.8 was obtained.

Comparative example 2 In Example 2, excluding benzotriazole.

A blue ink with pH 8.8 was obtained in the same manner as in Example 2 except that the same amount of water was added.

Example 3 Brilliant Fast Scarlet 100 parts Ethylene glycol 10.0 parts Diethylene glycol 10.0 parts Shellac GBN (
Shellac, manufactured by Gifu Shellac Manufacturing Co., Ltd.) 2.0 parts ET-530 (acrylic resin emulsion, manufactured by Nippon Pure Chemical Industries, Ltd.) 100 parts Triethanolamine 1.0 parts Demol N (anionic surfactant).

(manufactured by Kao Soap) 0.2 part Broxel GXL (preservative.

(manufactured by IOI) 0.4 parts benzotriazole 0.5 parts water
50
．． 9 parts P l(9
, 4 red ink was obtained.

Comparative Example 3 A red ink with a pH of 9.4 was obtained in the same manner as in Example 3, except that benzotriazole was removed and water was added in the same amount.

(Effects) The inks obtained in the Examples and Comparative Examples were filled into a metal tip ballpoint pen, and a ball sinking test and a writing taste test were conducted immediately after the ink was prepared and after two months at 50°C.The results are shown in the table below. Shown in 1.

Table-1 *1 Writing taste test Judgments were made by hand writing on paper.

*2 Marking angle 70° and marking speed 7C4/36C using ball sinking test marking machine
The water-based pigment ink of the present invention has excellent dispersion stability over time, and when used in a ballpoint pen, It has good lubricity and abrasion resistance, giving it an excellent writing feel. It is ideal for ballpoint pens.

In addition to ballpoint pens, it is also suitable for other writing instruments and inkjet printers.

Claims (1)

[Claims] A water-based pigment ink consisting of at least a pigment, a dispersant, a water-soluble organic solvent, and water contains benzotriazole and/or
or a derivative thereof in an amount of 0.1 to 5.0% by weight based on the total amount of the ink, and the pH of the ink is adjusted to 7 to 10.