JP4847693B2 - Ink composition for pressure ballpoint pen - Google Patents

Description

  The present invention relates to a pressure ballpoint pen ink composition.

  Conventionally, a pressure pen is sealed in an ink containing cylinder, the space inside the ink containing pipe is compressed by the pressure of the pressurized gas or a knocking operation, etc., and a ballpoint pen filled in the ink containing cylinder by the pressure of this compression A pressure-type ballpoint pen that presses the ink for the tip toward the tip is well known. Such a pressurized ballpoint pen is liable to cause ink leakage from the tip of the tip or the fitting part of the ballpoint pen tip, and the ink viscosity is set to a high value of 100,000 to 200,000 mPa · s (20 ° C.). The reality was that sacrificing writing quality.

In view of these problems, in Japanese Patent Application Laid-Open No. 2002-205484 “Ball Pen Refill”, an ink having a pressure of 0.15 MPa to 0.4 MPa and an ink viscosity of 10,000 to 50,000 mPa · s (25 ° C.) The pressure is set to be equal to or higher than atmospheric pressure (0.1 MPa) and lower than or equal to 5 atmospheric pressure (0.5 MPa), as in the ink imparted with structural viscosity to this ink and Japanese Patent Application Laid-Open No. 10-236065 “ballpoint pen”. A valve that is filled with ink having shear thinning viscosity using water of 000 to 40,000 mPa · s (23 ° C.) as a main solvent, and an elastic body that always presses the ball forward in the axial direction in the chip. A structure with a mechanism is disclosed.
"JP 2002-205484 A" "Japanese Patent Laid-Open No. 10-236065"

  Certainly, the writing quality is improved by lowering the ink viscosity, but it is also true that the lower the ink viscosity, the easier the ink leakage from the tip of the tip. In particular, in a pressure ballpoint pen, since pressure was applied, ink leakage was more likely to occur.

  Further, the pressure for pressing the ink of the pressure ballpoint pen becomes smaller at the end of the time when the ink amount is small compared to the initial state where the ink amount is accommodated in the ink accommodating cylinder. This is because the space in which the pressurized gas is sealed increases as the ink is consumed.

  Therefore, as the amount of ink to be stored increases, the pressure change between the initial state where the ink amount is large and the end of the time when the ink amount is small is large, and it is necessary to increase the pressure applied to the initial state. Ink leakage from the ink tends to occur.

  By the way, in a conventional ballpoint pen, the ink capacity of a gel ink ballpoint pen containing shear-thinned ink (hereinafter referred to as gel ink) is 2 to 3 times that of an oily ballpoint pen containing oily ballpoint pen ink. Many are accommodated. This is for the purpose of making the total writing distance equal between the gel ink ballpoint pen and the oil-based ballpoint pen when the ball diameter is the same.

  In view of these problems, the present invention provides an ink composition for a pressurized ballpoint pen that has good writing quality and does not leak and sag from the tip of a chip.

The present invention
“1. Coloring agent, shear thinning agent, organic solvent containing ethylene glycol monophenyl ether and / or benzyl alcohol , resin, and polymer fine particles having a particle size of 0.02 to 1.0 μm. And the polymer fine particles are styrene acrylic fine particles, impart non-Newtonian viscosity by the shear thinning agent and structural viscosity by the polymer fine particles, and have a shear rate of 0.19 sec ⁻¹ (20 ° C.). An ink composition for a pressurized ballpoint pen, wherein the ink viscosity is 50,000 mPa · s or more and the ink viscosity at a shear rate of 500 sec ⁻¹ (20 ° C.) is 30,000 mPa · s or less.
2. The ink composition for pressurized ball-point pens according to item 1 , wherein the acrylic fine particles are styrene-methacrylate cross-linked fine particles.
3. 3. The pressure ballpoint pen ink composition according to item 2, wherein the styrene-methacrylic ester-based crosslinked fine particles are fine particles obtained by internally crosslinking 10 to 50% of styrene and an acrylic monomer. Is.

The ink viscosity was measured at a temperature of 20 ° C. using a CSL rheometer manufactured by Calime, UK. Ink viscosity during writing, the shear rate 500 sec ^-1, the ink viscosity at rest, as an approximation of the shear rate 0 sec ^-1, and the ink viscosity shear rate 0.19sec ^-1.

A first aspect of the present invention, shear rate 0.19sec ^-1 (20 ℃) ink viscosity is 50,000 mPa · s or more at the ink viscosity is below 30,000 mPa · s at a shear rate 500sec ^-1 (20 ℃) It is to make the ink which gave the shear thinning viscosity.

When the ink viscosity at a shear rate of 0.19 sec ⁻¹ (20 ° C.) is less than 50,000 mPa · s, ink leakage from the tip end and the tip fitting portion cannot be prevented when pressure is applied. In addition, when the ink viscosity at a shear rate of 500 sec ⁻¹ (20 ° C.) is higher than 30,000 mPa · s, the writing quality is not good.

  The second feature is that polymer fine particles having a particle diameter of 0.02 to 1.0 μm are contained in the ink composition for a pressurized ballpoint pen.

  As described above, the ink is provided with shear thinning viscosity, and the ink viscosity at rest is 50,000 mPa · s or more, so that ink leakage from the tip end of the chip is less likely to occur. The product contains polymer fine particles with a particle size of 0.02 to 1.0 μm, and the structure viscosity of the ink is increased by the interaction between the resin and solvent of the ink for pressure ballpoint pen and the surface of the polymer fine particles. By applying, ink leakage from the tip end can be prevented more completely.

  The shape of the polymer fine particles is preferably a spherical shape with a small particle diameter, which is easy to be discharged from the gap between the ball and the tip of the chip, but when the particle size exceeds 1.0 μm, it is difficult to be discharged from the gap of the tip of the chip. If it is less than 0.02 μm, the effect of preventing ink leakage at the tip of the chip is thin, so the particle diameter is 0.02 to 1.0 μm, preferably 0.02 to 0.5 μm.

  Further, when the content of the polymer fine particles is less than 0.5% by mass, the effect of preventing ink leakage at the tip of the chip is thin, and when it exceeds 5.0%, the handwriting density becomes thin. It is preferable to set it as mass%-5.0 mass%.

  Examples of the polymer fine particles include acrylic fine particles, polystyrene particles, benzoguanamine / formaldehyde condensates, and silicone fine particles. Among them, acrylic fine particles are preferable because they are excellent in stability over time. Among them, styrene acrylic fine particles are preferable because they have a high dispersibility in a high boiling point solvent such as ethylene glycol monophenyl ether or benzyl alcohol generally used in oil-based ballpoint pens and are uniformly dispersed in the ink. Further, among the styrene acrylic fine particles, the fine particles obtained by crosslinking the styrene methacrylate are made to have an internal structure so that the particle shape does not change in the organic solvent, and the change in the particle shape in the heated state is small.

  Further, the styrene-methacrylic ester-based crosslinked fine particles are preferable because the amount of styrene is 10 to 50%, preferably 20 to 30%, because they are uniformly dispersed in the ink and stable in the organic solvent. If the amount of styrene is less than 10%, the amount of acrylic is too large, so that the particle size distribution of the fine particles is wide, and not only fine particles with a uniform particle size are obtained, but also the solvent dispersion stability deteriorates, and the fine particles are It causes sedimentation and causes poor writing. If the amount of styrene exceeds 50%, it becomes difficult to produce fine particles, and the degree of swelling when dispersed in a solvent is high, and the particle shape is likely to change in an organic solvent.

  The ink composition for a pressurized ballpoint pen of the present invention prevents ink leakage from the tip of the chip by the synergistic effect of the ink viscosity setting described above, the non-Newtonian viscosity due to the shear thinning agent, and the structural viscosity due to the polymer fine particles. It can be surely prevented.

  As the colorant employed in the present invention, dyes and / or pigments are used. As the dye, alcohol-soluble dyes, oil-soluble dyes, direct dyes, acid dyes, basic dyes, metal-containing dyes, various salt-forming dyes, and the like conventionally used in oil-based ballpoint pens can be used. These colorants may be used alone or in combination of two or more. As for content, 20-40 mass% is desirable with respect to the ink composition whole quantity. Examples of the pigment include organic, inorganic, and processed pigments such as carbon black, phthalocyanine, azo, quinacridone, quinophthalone, selenium, and triphenylmethane. These colorants may be used alone or in combination of two or more. The content is desirably 1 to 20% by weight based on the total amount of the ink composition.

  The organic solvent is used as a solvent and a dispersion medium for the ink component. Specifically, alcohols such as benzyl alcohol, propylene glycol, butylene glycol and glycols, glycol ethers such as ethylene glycol monophenyl ether, nitrogen-containing solvents such as N-methylpyrrolidone, and the like can be used. These may be used alone or in combination of two or more. The content is preferably 10 to 60% by mass based on the total amount of the ink composition.

  Resin is contained as an ink viscosity modifier. Examples of the resin include phenolic resin, maleic resin, amide resin, xylene resin, hydrogenated rosin resin, ketone resin, terpene resin, butyral resin, and the like. These are also effective as a fixing agent and a fixing agent on the paper surface. These may be used alone or in combination of two or more.

  In addition, a spinnability imparting agent can be used in a timely manner in order to improve crying and cutting performance. Examples of additives include polyvinyl pyrrolidone, polyethylene oxide, hydroxypropyl cellulose, rubber polymer compounds, and the like. These may be used alone or in combination of two or more. As other additives, surfactants, rust inhibitors, dispersants, lubricants, dye dissolution stabilizers, and the like can be selected and added as appropriate.

  The ink composition for a pressurized ballpoint pen of the present invention has good writing quality and can prevent ink leakage and dripping from the tip of the tip due to the synergistic effect of the shear thinning agent and the polymer fine particles.

  Next, examples of the ink composition for a pressurized ballpoint pen of the present invention will be described, but the present invention is not limited to the following examples.

  The pressure ballpoint pen ink composition first employs benzyl alcohol and ethylene glycol monophenyl ether as organic solvents, weighs a predetermined amount and heats to 60 ° C., and then disperses the polymer fine particles using a disper stirrer. As a result, styrene acrylate cross-linked fine particles having a particle size of 0.8 μm (Microgel manufactured by Nippon Paint Co., Ltd.) were uniformly dispersed. Next, oleic acid as a lubricant, polyvinylpyrrolidone K-90 (manufactured by Wako Pure Chemical Industries, Ltd.) as a spinnability imparting agent, and Hilac 110H (Hitachi Chemical Co., Ltd.) as an ink viscosity modifier (oil-soluble viscosity adjusting resin) Company-made ketone resin), fatty acid amide wax as shear thinning agent, dye-based spiron black GMH-Special (Hodogaya Chemical Co., Ltd.) and Bali First Violet 1701 (Orient Chemical Co., Ltd.) Was dissolved using a disper stirrer to obtain a black pressure ballpoint ink composition. Specific blending amounts are as follows.

Colorant (Spiron Black GMH-Special) 15.0% by mass
Colorant (Vari First Violet 1701) 15.0% by mass
Organic solvent (benzyl alcohol) 17.7% by mass
Organic solvent (ethylene glycol monophenyl ether) 26.6% by mass
Shear thinning agent (fatty acid amide wax) 1.2% by mass
Polymer fine particles (styrene acrylate cross-linked fine particles) 2.0% by mass
Ink viscosity modifier (Hilac 110H) 20.0% by mass
Spinnability imparting agent (polyvinylpyrrolidone K-90) 0.5% by mass
Lubricant (oleic acid) 2.0% by mass

Examples 2-4
A pressure ballpoint ink composition was obtained in the same manner as in Example 1 except that each pressure ballpoint ink composition was blended as shown in Table 1.

Table 1

Comparative Example 1
An ink composition for a pressure ballpoint pen was obtained in the same manner as in Example 1 except that the polymer fine particles were not added and the other blending was as described in Table 2.

Comparative Examples 2-5
An ink composition for a pressure ballpoint pen was obtained in the same manner as in Example 1 except that the composition of each ink composition was as described in Table 2.

Table 2

Test Method and Evaluation After 0.3 ml of the ink composition for pressurized ball-point pens of each Example and Comparative Example was filled in the ink containing tube, the compressed air was sealed and the ball diameter was 0 while maintaining 0.3 MPa. A pressure ballpoint pen refill equipped with a ballpoint pen tip holding a 7 mm ball was prepared, and the following test was conducted and evaluated.
1. Writing feeling (in handwritten writing)
Can be written with low writing pressure, smooth and particularly good .... ◎
Good thing …… ○
Somewhat inferior …… △
Those that cannot be written at low writing pressure and do not feel slippery are marked with ×.
2. Ink leakage: The tip of the pressurized ballpoint pen refill in each example was upright and left for 24 hours at a temperature of 30 ° C. and a humidity of 80% RH.
Ink that does not leak from the tip of the tip ...... ○
Ink leakage from the tip of the tip was recognized.

The evaluation results of each example and comparative example are as shown in Table 1 and Table 2.
Since Comparative Example 1 did not contain polymer fine particles, ink leakage occurred even when the ink viscosity at a shear rate of 0.19 sec ⁻¹ (20 ° C.) was 50,000 mPa · s or more.

In Comparative Examples 2 and 3, the ink viscosity at a shear rate of 0.19 sec ⁻¹ (20 ° C.) was too low to prevent ink leakage. In addition, the blotting of the handwriting and the show-through occurred.

Comparative Example 4, without the addition of shear thinning viscosity-imparting agent, because of the high ink viscosity at a shear rate of 0.19sec ^-1 (20 ℃), higher ink viscosity at a shear rate of 500sec ^-1 (20 ℃), ball spin Since the resistance becomes strong, the writing feeling is not good.

In Comparative Example 5, the ink viscosity at a shear rate of 0.19 sec ⁻¹ (20 ° C.) was lowered without adding a shear thinning agent, and thus ink leakage could not be prevented. Also, the ink viscosity at a speed of 500 sec ⁻¹ (20 ° C.) is high, and the ball rotation resistance becomes strong, so the writing feeling is not good.

  Further, although not shown in the table, neither the example nor the comparative example could be written in an atmospheric pressure (0.1 MPa) state where no pressure was applied.

The pressure-type ballpoint pen structure filled with the ink composition of the present invention is not particularly limited. For example, pressurized gas is sealed in the ink storage tube after ink filling, or the air in the ink storage tube is compressed by pumping. A ballpoint pen structure such as

Claims (3)

A coloring agent, a shear thinning agent, an organic solvent containing ethylene glycol monophenyl ether and / or benzyl alcohol , a resin, and polymer fine particles having a particle diameter of 0.02 to 1.0 μm, The polymer fine particles are styrene acrylic fine particles, which impart non-Newtonian viscosity by the shear thinning agent and structural viscosity by the polymer fine particles, and ink viscosity at a shear rate of 0.19 sec ⁻¹ (20 ° C.). An ink composition for a pressurized ballpoint pen, wherein the ink viscosity at a shear rate of 500 sec ⁻¹ (20 ° C.) is 30,000 mPa · s or less. The ink composition for a pressurized ballpoint pen according to claim 1 , wherein the styrene-acrylic fine particles are styrene-methacrylic ester-based crosslinked fine particles. 3. The ink composition for a pressure ballpoint pen according to claim 2 , wherein the styrene-methacrylic ester-based crosslinked fine particles are fine particles obtained by internally crosslinking 10 to 50% of styrene and an acrylic monomer.