JP5109312B2 - Water-based ink for ballpoint pens - Google Patents

Description

  The present invention relates to an ink having properties expressed by non-Newtonian viscosity, shear thinning viscosity, etc., and reduces foaming due to the stirring effect due to rotation of the ball as much as possible during writing, and prevents breaks in handwriting when written later. The present invention relates to a water-based ink for a ballpoint pen.

In recent years, ballpoint pens in which ink storage tubes are directly filled with pruning deviscous ink are known. The shearing thinning ink uses a shear thinning agent for the purpose of ink leakage from the pen tip and obtaining an appropriate ink discharge amount. This shear thinning agent has a relatively high viscosity when not writing, suppresses ink leakage from the pen tip, and when writing, the viscosity decreases due to the rebounding force of the rotating ball, so-called shearing thinning reduces the ink smoothly. Can be discharged.
However, in the shear thinning ink, not all of the discharged ink becomes a handwriting. Of the ink adhering to the ball, the portion in contact with the paper surface becomes handwriting, but the ink that is not in contact with the ink is drawn by the capillary action of the paper surface even though the viscosity is reduced by the rotation of the ball. It has not reached. Therefore, a part of the water accumulates in the forehead and causes a blur, and a part of the ink returns to the inside of the nib.
On the other hand, in the case of a water-filled ballpoint pen with a low-viscosity ink or a direct liquid-type water-based ballpoint pen with a bellows structure, the discharged ink is strongly affected by the capillary action of the paper because it has a low viscosity, and it touches the paper surface. Most ink that is not printed is also handwritten. Therefore, almost no ink returns to the inside of the nib.
In addition, when a surfactant is contained as a pigment dispersant in the ink, bubbles are generated due to the stirring effect associated with the rotation of the ball. These bubbles are caught inside the nib together with the ink. If it continues to be used as it is, no particular problem will occur. However, after that, when writing without writing for a long period of time, there was a case in which the ink was temporarily interrupted, resulting in a blurring phenomenon.
As pigment dispersants used in shear thinning ink, Patent Documents 1 to 4 disclose polyoxyethylene polyoxypropylene alkyl ethers as examples.
JP 08-209055 (paragraph number (0011)) Japanese Patent Laid-Open No. 08-302267 (paragraph number (0016)) JP-A-10-166780 (paragraph number (0016)) JP 2000-007975 A (paragraph number (0020))

The polyoxyethylene polyoxypropylene alkyl ethers described in Patent Documents 1 to 4 are preferably used because they are excellent as a dispersant for pigment, and C ₁₂ lauryl, C ₁₄ milstil (tetradecyl) as an alkyl group, Although C ₁₆ palmityl (cetyl) C ₁₈ stearyl and the like are known, they have a problem in that a large foaming.
In the ballpoint pen, when writing, the ink is agitated and bubbled with the rotation of the ball, and some of the bubbles break, but the ink containing bubbles that do not break returns to the inside of the pen tip. The returned ink becomes highly viscous again inside the nib, so that the entrained bubbles cannot move and remain in the ballpoint pen tip.
After that, if left standing for a long period of time, a number of small bubbles entrained become one large bubble, and the ink is temporarily interrupted at that portion, resulting in a smudged state.

That is, it is preferable that the pigment dispersant does not easily foam due to the stirring effect accompanying the rotation of the ball.
It is an object of the present invention to provide a water-based ink for a ballpoint pen that reduces foaming due to the stirring effect associated with the rotation of the ball at the time of writing and prevents breakage of handwriting caused by bubbles.

  The gist of the present invention is a water-based ink for ballpoint pens containing at least a pigment, water, and polyoxyethylene polyoxypropylene decyl ether.

The polyoxyethylene polyoxypropylene decyl ether contained in the water-based ink for ballpoint pens of the present invention has a hydrophobic group having a short number of C groups and a short hydrophobic group length. Is taken into the network structure of the shear thinning agent contained in the ink, so that problems with time such as aggregation and sedimentation are eliminated.
On the other hand, the bubble is a state in which air is covered with a foam film. When air is present in the solution, the surfactant molecules form bubbles by directing the hydrophobic group to the hydrophobic air side and the hydrophilic group to the solution side. The strength of the foam increases as the surfactant molecules are more closely adsorbed and the foam film is thicker.
Since the polyoxyethylene polyoxypropylene decyl ether of the present invention has a short hydrophobic group, it easily becomes familiar with water and hardly forms stable bubbles. Therefore, it is difficult to form bubbles even with stirring accompanying the rotation of the ball. Therefore, the ink that has returned to the inside of the nib does not contain countless small bubbles, so even if it is left for a long period of time, it does not become one large bubble. It is considered that no interruption occurs.

Polyoxyethylene polyoxypropylene decyl ether is used for dispersing the pigment and reducing the foaming property of the ink. The amount used is most effective at 20% to 40% with respect to the pigment, and does not settle and solidify even in the state of the pigment dispersion. If it is 20% or less, the pigment may precipitate during long-term storage of the pigment dispersion. However, if it is used after dispersing the pigment, it can be written without blurring even after a long period of time due to the effect of the shear thinning agent. On the other hand, if it is 40% or more, the foaming property becomes large, and there is a case where it is blurred by writing after aging.
Specific examples thereof include pegnol D · 206, pegnol D · 208, pegnol D · 210, pegnol D · 218, pegnol D · 223, pegnol D · 410, pegnol D · 206H (manufactured by Toho Chemical Co., Ltd.), and the like. Can be mentioned.

  Examples of the pigment used include conventionally known carbon black and organic pigments. These can be used alone or in combination.

The shear thinning agent is used for the purpose of preventing sedimentation of the pigment and imparting shear thinning to the ink.
Specific examples include Kelzan, Kelzan S, Kelzan F, Kelzan AR, Kelzan M, Kelzan D (above, manufactured by Sanki Co., Ltd.), Kojin, Kojin F, Kojin T, Kojin K (above, Kojin Co., Ltd.) Xanthan gum such as Lexan (manufactured by Sanki Co., Ltd.), succinoglucan such as K1A96 (manufactured by Sanki Co., Ltd.), lanthanum gum such as K1A112, K7C2433 (manufactured by Sanki Co., Ltd.) Guaguas such as Jaguar 8111, 8600, HP-8, HP-60, CP-13 (manufactured by Sanki Co., Ltd.), Pullulan (manufactured by Hayashibara Co., Ltd.), Zeta Seagum (Hakuto Co., Ltd.) Water-soluble polysaccharides).
And the usage-amount of the shear thinning agent in this invention has preferable 0.1-2.0 weight% with respect to the ink whole quantity. If it is less than 0.1% by weight, the ink viscosity is too low and the ink tends to leak. On the other hand, when the amount exceeds 2.0% by weight, the viscosity becomes too high, and thus ink discharge from the pen tip portion tends to be poor.

Water is used as the main solvent.
In addition to the above components, various additives used in conventional water-based ink compositions can be used.
A water-soluble organic solvent can be used for the purpose of preventing ink drying at the pen tip, preventing the ink from freezing at low temperatures, and the like. Specific examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, hexylene glycol, 1,3-butylene glycol, thiodiethylene glycol, glycerin, 2-pyrrolidone, N-methyl-2-pyrrolidone, Examples include triethanolamine. These water-soluble organic solvents can be used alone or in combination. The amount used is preferably 10 to 60% by weight based on the total amount of the ink composition.
Furthermore, wetting agents such as urea, ethylene urea and thiourea, antiseptics such as benzothiazoline and omadin, rust inhibitors such as benzotriazole, and styrene-acrylic copolymers for fixing pigments to the writing surface And alkali salts thereof, emulsions such as vinyl acetate, acrylic and styrene-acrylic resins, pH adjusters such as sodium hydroxide, 2,2-aminomethyl-1,3-propanediol, diethanolamine, silicone emulsions Various additives such as an antifoaming agent can be used as necessary.

In producing the ink composition of the present invention, various conventionally known methods can be employed.
For example, after adding water and a thickener to a stirrer such as a Henschel mixer having high shearing force and stirring and dissolving, add the pigment and other remaining components dispersed by a disperser such as a ball mill, a bead mill, and a roll mill, and further mix and stir. Can be easily obtained. You may perform the removal of the foam by a defoamer, filtration of the coarse thing by a filter, etc. as needed.

  Hereinafter, it demonstrates still in detail based on an Example and a comparative example. In each example, “part” simply means “part by weight”.

(Pigment adjustment example 1)
Carbon black 20.0 parts Water 65.0 parts Pegnol D · 218 (polyoxyethylene polyoxypropylene decyl ether,
HLB14.3, manufactured by Toho Chemical Co., Ltd.) 5.0 parts Diethylene glycol 10.0 parts The above components were dispersed for 24 hours in a ball mill.

(Pigment adjustment example 2)
Pigment Red 170 25.0 parts Water 64.0 parts Pegnol D / 210 (polyoxyethylene polyoxypropylene decyl ether, H
LB12.9, manufactured by Toho Chemical Co., Ltd.) 6.0 parts Diethylene glycol 10.0 parts The above components were subjected to 6-pass dispersion treatment in a bead mill.

Example 1
Ion-exchanged water 43.0 parts by weight Ethylene glycol 20.0 parts by weight Glycerin 10.0 parts by weight Benzotriazole 0.4 parts by weight Proxel GXL (preservative, 1,2-benzisothiazolin-3-one, ICI Japan Co., Ltd.) 0.2 parts by weight TSA739 (antifoaming agent, silicone emulsion, manufactured by GE Toshiba Silicones Co., Ltd.)
0.1 parts by weight Pigment Preparation Example 1 20.0 parts Phosphanol RB410 (20% aqueous solution of sodium hydroxide neutralized with polyoxyethylene oleyl ether phosphate, pH 8.3, manufactured by Toho Chemical Industry Co., Ltd.)
5.0 parts by weight Jonkrill J734 (styrene / acrylic resin emulsion, manufactured by Johnson Polymer Co., Ltd.) 1.0 parts by weight Zeta Seagum (manufactured by Hakuto Co., Ltd.) 0.3 parts by weight 0.3 parts by weight of Zeta Sea Gum in a Henschel mixer And 20.0 parts by weight of ion-exchanged water were stirred and dissolved at 2800 rpm for 30 minutes, and then the remaining components were added to the aqueous solution of zeta sea gum, and further mixed and stirred at 1400 rpm for 30 minutes to obtain a black ink.

(Example 2)
Ion-exchanged water 45.7 parts by weight Propylene glycol 17.0 parts by weight Glycerin 5.0 parts by weight Benzotriazole 0.4 parts by weight Proxel GXL (described above) 0.2 parts by weight TSA739 (antifoaming agent, silicone emulsion, GE Toshiba Silicone) (Made by Co., Ltd.)
0.1 part by weight Pigment Preparation Example 2 25.0 parts by weight N-oleoyl sarcosine sodium 20% aqueous solution 5.0 parts by weight Jonkrill J734 (described above) 1.0 part by weight Succinoglucan (manufactured by Sansho Co., Ltd.) 0 .6 parts by weight 0.6 parts by weight of succinoglucan and 20.0 parts by weight of ion-exchanged water were added to a Henschel mixer, and after stirring and dissolving at 1400 rpm for 30 minutes, the remaining components were added to the aqueous succinoglucan solution. Further, the mixture was stirred at 1400 rpm for 30 minutes to obtain a red ink.

(Example 3)
Ion-exchanged water 32.05 parts by weight Ethylene glycol 20.0 parts by weight Glycerol 10.0 parts by weight Benzotriazole 0.4 parts by weight Proxel GXL 0.2 parts by weight TSA739 (previously described) 0.1 part by weight Pigment Preparation Example 1 20. 0 parts by weight N-oleoyl sarcosine sodium 20% aqueous solution 5.0 parts by weight Jonkrill J734 (previously described) 1.0 part by weight zeta seagum (previously described) 0.25 parts by weight Ion exchange with 0.25 parts by weight of zeta seagum in a Henschel mixer After adding 20.0 parts by weight of water and stirring and dissolving at 2800 rpm for 1 hour, the remaining components described above were added to the aqueous solution of zeta sea gum, and further mixed and stirred at 1400 rpm for 30 minutes to obtain a black ink.

Example 4
In Example 1, the same procedure as in Example 1 was carried out except that Pegnol D · 218 in Pigment Preparation Example 1 was reduced to 3.0 parts by weight and the amount of ion-exchanged water was increased accordingly.

(Example 5)
In Example 1, the same procedure as in Example 1 was performed except that the amount of Peganol D · 218 in Pigment Preparation Example 1 was increased to 9.0 parts by weight, and the amount of ion-exchanged water was reduced accordingly.

(Comparative Example 1)
Example 1 was the same as Example 1 except that WONDERSURF RL-100 (polyoxyethylene polyoxypropylene lauryl ether, manufactured by Aoki Oils and Fats Co., Ltd.) was used instead of Pegnol D · 218 in Pigment Preparation Example 1.

(Comparative Example 2)
Example 1 was the same as Example 1 except that BLAUNON 1000R (polyoxyethylene polyoxypropylene stearyl ether, manufactured by Aoki Oils and Fats Co., Ltd.) was used instead of Pegnol D · 218 in Pigment Preparation Example 1.

  Pentel's hybrid K105 ink storage tube is connected via a ballpoint pen tip holder to a ballpoint pen tip that holds a ball with a diameter of 0.5 mm. After filling the water-based ink for ballpoint pens obtained in 1-2 above and arranging the backflow preventive composition used in K105 in layers at the ink interface, it is removed by centrifuging so that the pen tip faces the outside. The following tests were conducted using a test ballpoint pen obtained by foaming. The test results are shown in Table 1.

(written exam)
With a test ballpoint pen, write 400 characters of “Ei” on a vertical 20 × 20 manuscript paper, cap it, and leave it in a temperature-controlled room adjusted to a temperature of 50 ° C. and a humidity of 30% with the pen tip facing up. To do. After 5 days, the test ballpoint pen was taken out, cooled to room temperature, and similarly written on the original paper, and the number of blurred characters was determined.

Claims (2)

A water-based ink for ballpoint pens containing at least a pigment, water, and polyoxyethylene polyoxypropylene decyl ether. The water-based ink composition for ballpoint pens according to claim 1, further comprising a shear thinning agent.