JPH02245075A - Water-based ink for writing utensil - Google Patents

Abstract

PURPOSE:To prepare a water-based ink for a writing utensil which gives a good rewriting property even after it is left uncapped for a long time, prevents blooming, and improves the appearance of written lines by compounding a water-soluble dye, a specified amt. of glycerin, a specified amt. of diethylene glycol, and a specific copolymer as components of said ink. CONSTITUTION:A water-based ink for a writing utensil is prepd. by compounding a water-soluble dye, at least 3% glycerin, at least 5% diethylene glycol, and at least 0.1% ethylene oxide-propylene oxide copolymer into an ink compsn. The writing utensil using the resulting ink enables a good rewriting even after being left uncapped for a long time, prevents blooming, can sufficiently follow a high-speed writing, and gives an improved appearance of written lines without oozing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water-based ink for writing instruments, particularly for use in sign pens for plotters and ballpoint pens.

(Prior art) Writing instruments used in plotters do not deteriorate, such as lines being blurred, and do not become impossible to write on, even after a user leaves them without a cap for several days to a month. , to be able to write in the same state as before leaving it,
In other words, it is required to have good rewriting properties, and it is also required that the phenomenon in which dyes and additives in the ink solidify or crystallize and precipitate at the tip of the pen nib (hereinafter referred to as "hanasaki phenomenon") does not occur. be done. Conventionally, for this purpose, a large amount of a water-soluble organic solvent (hereinafter referred to as "non-drying solvent") such as ethylene glycol or propylene glycol has been added to the ink composition. Furthermore, conventionally, in order to improve the drawing quality, fluorine-based or fatty acid-based surfactants have been added.

(Problems to be Solved by the Invention) However, ink containing a large amount of the non-drying solvent described above has problems such as increased viscosity and loss of fluidity, making it difficult to follow high-speed writing, and causing blurring in drawn lines. Moreover, if the type of non-drying solvent is selected incorrectly, the blooming phenomenon cannot be suppressed even if a large amount is added. Further, when the above-mentioned surfactant is added, the surface tension of the ink decreases, resulting in a tendency for drawn lines to smear or a blooming phenomenon to occur.

Therefore, the present invention eliminates the above-mentioned disadvantages by suppressing the amount of non-drying solvent added, improves the rewriting properties of the writing instrument after being left without a cap for a long period of time, and prevents the blooming phenomenon. The purpose of the present invention is to provide a water-based ink for writing instruments that can improve the quality of drawn lines.

(Means for Solving the Problems) In order to achieve the above object, the water-based ink for writing instruments of the present invention contains a water-soluble dye, 3% or more glycerin, and 5% or more diethylene glycol in the ink composition. , 0.011% or more of ethylene oxide/propylene oxide copolymer.

That is, in the present invention, glycerin and diethylene glycol are used in combination as non-drying solvents.

The amount of glycerin added should be the minimum amount that can prevent the blooming phenomenon, and should be 3% or more, but preferably 10% or less. Further, the amount of diethylene glycol added is required to be 5% or more in order to improve rewriting properties, but it is preferably 30% or less. In addition, in the present invention, an ethylene oxide/propylene oxide copolymer is used in place of the conventional surfactant in order to improve the line drawing quality, but it is preferable that this has a molecular weight in the range of about 1000 to 2000, and its addition The amount must be 0.1% or more. Moreover, acidic dyes are preferable as the water-soluble dyes used in the present invention.

(Function) Glycerin used as one of the non-drying solvents in the present invention has a high boiling point, high hygroscopicity, and good solubility of dyes, so it has the effect of preventing the blooming phenomenon. Glycerin also has the effect of suppressing bleeding of ink lines. However, since glycerin has a high viscosity, it has the disadvantage of increasing the viscosity of the ink. Also,
Diethylene glycol, the other non-drying solvent used in the present invention, has the effect of significantly improving rewriting properties after being left without a cap for a long period of time, and also has a relatively low viscosity among non-drying solvents, so it It has the effect of suppressing the increase in viscosity. On the other hand, ink using diethylene glycol has the disadvantage that it easily bleeds and the quality of drawn lines tends to deteriorate. Therefore, by using glycerin and diethylene glycol together, the blooming phenomenon can be prevented and good rewriting properties can be obtained, and the disadvantages of one are offset by the advantages of the other, so problems such as increased ink viscosity and bleeding can be avoided. is resolved. In addition, ethylene oxide/propylene oxide copolymer has the effect of improving the quality of drawn lines, but since it has a small effect on the ink surface tension, there is no problem of blurring of drawn lines, and there is no risk of flower blooming. Since it is liquid at room temperature, it will not adversely affect rewriting performance even if it is left without a cap for a long time.

(Example) Example 1 (% by weight) Dye (Food Blue No. 1)2. O Dye (Food Yellow No. 4) 2.0 Diethylene glycol 20.0 Glycerin 5.0 Ethylene oxide/propylene oxide copolymer 0.1 Sodium Gamadine 10% aqueous solution 0.1 Water
70.8 Example 2 (wt%) Dye (Food Yellow No. 5) 1.5 Dye (Food Red No. 104) 0.5 Eosin 2.5 Diethylene glycol 22.0 Glycerin
3゜O ethylene oxide/propylene oxide copolymer O8l sodium omazine 10%
Aqueous solution 0,1 water
7o, 3 Comparative Example 1 Dye (Food Blue No. 1) Dye (Food Yellow No. 4) Sodium ethylene glycol decyl benzene sulfonate sodium omadine 10% aqueous solution (wt%) 2.0 2.0 30.0 0.1 65.8 Comparative Example 2 Dye (Food Yellow No. 5) Dye (Food Red No. 104) Sodium Eosin Ethylene Glycold Decylbenzenesulfonate Sodium Omazine 10% Aqueous Solution (wt%) 1.5 0.5 2.5 3 0 .0 0.1 0.1 65.3 The compositions of each of the above Examples and Comparative Examples were each stirred at room temperature for 3 hours and then filtered to obtain test inks. still,
The ethylene oxide/propylene oxide copolymer used in each example had a molecular weight of about 2000 and a 50% ethylene oxide ratio in the molecule. This test ink was filled into a felt-tip pen equipped with a pen tip obtained by extrusion molding polyacetal, and its followability to high-speed writing (60cm/5ec) with a plotter was tested in the initial state, and then in an environment of 25°C and 60% humidity. Below, the pen was left without a cap for one month, and the presence or absence of a blooming phenomenon of the pen tip and rewriting properties were examined, and the followability to high-speed writing was again tested. The results are shown in Table 1.

Table 1 (Effects of the Invention) As mentioned above, the writing instrument using the ink of the present invention has good rewriting properties even after being left without a cap for a long period of time, does not cause the blooming phenomenon, and is sufficient for high-speed writing. This has the effect of not blurring the drawn lines and improving the quality of the drawn lines.

Patent applicant: Mitsubishi Pencil Co., Ltd.

Claims (1)

[Claims] 1. The ink composition contains a water-soluble dye, 3% or more of glycerin, 5% or more of diethylene glycol, and 0.1% or more of diethylene glycol.
% or more of an ethylene oxide/propylene oxide copolymer. 2. The aqueous ink for writing instruments according to claim 1, wherein an acid dye is used as the dye. 3. The aqueous ink for writing instruments according to claim 1, wherein the ethylene oxide/propylene oxide copolymer has a molecular weight of about 2,000.