JPS63145381A - Water-based black ink composition for writing utensil - Google Patents

Abstract

PURPOSE:To obtain a black ink having excellent blackness and hiding power, by blending a black pigment with a dispersant, an aq. medium and further white resin particles. CONSTITUTION:An ink compsn. is obtd. by incorporating white resin particles in a water-based ink compsn. consisting of a black pigment, a dispersant and an aq. medium. The white resin particles must be those which diffuse light by refractive index and particle size and are apparently white. Thus, the white resin particles must have a particle size of 0.1-1.0mu and a refractive index of 1.4-1.6. Examples of the white resin particles are polystyrene, polymethyl methacrylate, polyvinyl chloride, polyamide resin and resins obtd. by emulsion- polymerizing or suspension-polymerizing an alpha,beta-monoethylenically unsaturated monomer. As the black pigment, carbon black is particularly preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a black water-based ink composition for writing purposes, and more specifically, the present invention relates to a black water-based ink composition for writing purposes. By incorporating white resin particles which are insoluble in the aqueous medium, a black aqueous writing ink composition having excellent blackness and hiding power is obtained.

(Prior Art) Conventionally, various water-based inks have been used for writing instruments such as sign pens, plastic pens, ballpoint pens, felt pens, fountain pens, drafting pens, etc. For general writing purposes, black water-based ink containing black pigment is often used.

(Problem that the invention is trying to solve) Note: Carbon black pigment is used as the black pigment in black ink, but when the pigment content is increased, the black pigment separates and settles, or the pen tip It cannot be used as a water-based ink for writing instruments due to clogging, etc. In addition, separation and sedimentation of pigments can be prevented to some extent by increasing the viscosity of the liquid, but high viscosity water-based inks are not suitable for use in rivers.

Therefore, the density of the black pigment has to be lowered to /11, so the hiding power of the ink image is low, which is sufficient for writing images.
There is a problem that it is not possible to increase the chromaticity.

From this point of view, the present inventors have decided to respond to the request described in L.
・3. As a result of research, by adding small white resin particles with a ratio of 1 rC to a pigment aqueous ink composition for writing that contains a black pigment, a water-based ink composition for writing instruments with a small amount of black pigment of 11 tons has a high hiding power. It has become an excellent product. ! 1. '-chromaticity, and found that it could fully meet the requirements stated in (2), and completed the present invention.

(Steps for Solving the Problems) That is, the present invention provides a writing device characterized in that a water-based ink composition for a writing instrument comprising a black pigment, a dispersant, and an aqueous medium further contains white resin particles. (This is a black water-based ink composition.

The 11-color pigment used in the present invention may be any conventionally known black rn pigment, but a particularly preferred one is a carphone black pigment. If the amount of black pigment used is too large, the stability of the water-based ink and the ejection performance at the pen tip will be affected, and if it is too small, the blackness of the water-based ink will be insufficient, so the preferred range is In the composition about 0.
The range is 5 to 20 times the day.

As the dispersant used in the present invention, any conventionally known pigment dispersant can be used, but particularly preferred are polymer dispersants. Particularly suitable are polymeric dispersants consisting of the following parts:

Structurally, such polymer dispersants can be roughly divided into condensation polymers and force-strength former R polymers, and any of the existing ones can be used, but condensation polymers are preferred, for example. , JP-A No. 60-26070, and examples of addition polymer dispersants include addition polymers of monomers having α,β-ethylenically unsaturated groups.

Particularly preferred are addition polymer based dispersants, which are derived from monomers forming the lipophilic portion and monomers forming the hydrophilic portion.

The above-mentioned addition polymer-based polymer dispersant can be prepared by appropriately mixing hydrophilic and lipophilic polymers, and by any conventional mixed polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, etc. It can also be obtained by a polymerization method. Known additives such as polymerization regulators may also be used if necessary. The polymerization medium used in this case may be water or a hydrophilic solvent that can be used as an aqueous medium for ink, and the mixture may be used as a medium for aqueous ink. jk separated into layers of polymer from solution
It can also be used after being dissolved in M degree.

The polymer dispersant obtained by combining 1 in this way is not particularly defined by its molecule h1, but 1,
The polymer content in the solution, the viscosity of the solution and the viscosity of the pigment aqueous ink composition using it, the quality of the recorded material such as the fastness, etc. It is preferable because

The use of the above-mentioned dispersant in the aqueous ink composition of the present invention cannot be generally defined, since it depends on the type of pigment and the brand of each pigment. For about 3~3001Rj
; 1 part, preferably about 5 to 100 parts.

Further, the aqueous medium constituting the pigment aqueous ink composition of the present invention is an aqueous solution of a hydrophilic organic solvent. for example,
methanol, ethanol, propatool, butanol,
Ethylene glycol, ethyl cellosolve, butyl cellosolve, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, chrycerin, sedaricerin, methyl calhitol, ethyl calpitol, butyl calhitol, etc. per 100 parts of water. An aqueous solution mixed and dissolved in a proportion of ~200 parts is preferred.

The white resin particles used in the present invention are insoluble in the 11η water-based ink medium, do not form a film, have a particle diameter of 0.1 to 1.0 μm, and a refractive index of 1.4 to 1.0 μm. 6 and are white resin particles with relatively uniform particle diameters, and are generally referred to as plastic pigments.

Such white resin particles include polystyrene, polymethyl methacrylate, polyvinyl chloride, henzoguanamine resin, epoxy resin, melamine resin, polyamide resin, or α,β-monoethylenically unsaturated monomers, which are commercially available or suspended in emulzidine. Examples include those obtained by turbid polymerization.

The white resin particles in the present invention must be able to diffuse light and appear white due to their refractive index and particle size. Therefore, the particle size of the white resin particles is 0.1 to 1.0 u.
m and the refractive index must be in the range of 1.4 to 1.6.

Therefore, the maximum light diffusion value (the range that looks whitest) and the particle size of each white resin particle are closely related (for example, the particle size range showing the maximum light diffusion value of polystyrene particles is 0.4~
Similarly, polymethyl methacrylate particles range from 0.6 to 0.9 μm and polyvinyl chloride particles range from 0.5 to 0.7 μm.

By adding the resin particles, which appear white when used alone, to a pigment aqueous ink containing a black pigment as described above, even if the amount of the black pigment is relatively small, 11J
The water-based ink produced has excellent dispersion stability while maintaining high hiding power, and the surface of the written image has a fine unevenness due to the presence of white resin particles, making it matte and extremely black. Therefore, characters and images formed with tri-aqueous ink have high hiding power and a bright blackness.

Of course, the hiding power and blackness of general water-based inks and paints can be improved by adding a conventionally known black pigment such as carbon black to water-based inks and paints, but this method provides high hiding power and excellent blackness. This requires the addition of relatively large amounts of black pigment, for example about 10 to 30 parts by weight of black pigment per 100 parts by weight of aqueous base.

However, in the case of water-based inks for writing instruments, if such a large amount of black pigment is added, the ink itself becomes unusable for writing instruments, as mentioned above.

On the other hand, in the present invention, by adding the above-mentioned white resin particles, the amount of black pigment used can be relatively reduced, and the dispersion stability of the pigment can be improved. In the water-based ink, a stable dispersion state can be maintained without separating from the liquid medium, and it can maintain sufficient dispersion stability as a water-based ink for writing instruments with excellent blackness.

In the water-based ink composition of the present invention! 11. If the content of white brush particles is too low, it will not be possible to obtain the dispersion stability and blackness comparable to that of a water-based ink, whereas if it is too large, the blackness or F of the water-based ink will be low. Therefore, a preferable range is a proportion of 0.5 to 20 Irj i1t% in the water-based ink.

In the present invention, the above-mentioned polymer dispersant can be used as it is as a binder for the black pigment and white resin particles in the water-based ink, but the polymer dispersant alone is insufficient as a binder, and the abrasion resistance of written materials, etc. (-If not, other water-soluble resins may be added as necessary.

Examples of such water-soluble resins include acrylic resins, styrene-maleic anhydride resins, and maleic anhydride resins.
, alkali metals such as ininated polybutadiene, maleated alkyd resins, maleated petroleum resins, maleated rosin esters, and polyvinylpyrrolidone, ammonia, amine salts, etc. are preferred, and are used in amounts that do not excessively increase the viscosity of the water-based ink. Ru.

Furthermore, conventionally known additives, humectants, rust preventives, auxiliary agents,
A dispersant, a lubricant, etc. are added as necessary.

The black aqueous ink composition for writing according to the present invention is composed of the constituent components and formulations listed above, and can be produced by any of the following methods. For example, a method of blending the above-mentioned waste ingredients and mixing and grinding the mixture using a conventionally known dispersing machine such as a whole mill, homomixer, sand grinder, speed line mill, or roll mill, or a method of mixing and grinding the above-mentioned waste ingredients with a conventionally known dispersing machine such as a whole mill, a homomixer, a sand grinder, a speed line mill, and a roll mill; A typical method is to prepare dispersions separately and mix them in an appropriate ratio.

(Action/Effect) Although the black aqueous ink composition for writing instruments of the present invention obtained as described above contains a black pigment, it does not survive long-term storage and preservation, nor is it susceptible to transportation, display, etc. The quality is stable even under various conditions, and virtually no phenomena such as aggregation or sedimentation of pigment particles or white resin particles are observed.

Therefore, it can be stably used as a water-based ink for writing instruments such as Sign Ben, Plastic Ben, Felt Ben, etc., and can provide characters and images with extremely excellent hiding power and high blackness.

In addition, pigments and white resin particles may aggregate in the container or at the pen tip (1) Good writing is possible without clogging, and in addition, low-volatile to non-volatile hydrophilic organic solvents can be used. The ones that contain this will not cause clogging due to drying of the pen tip! It can be said that it is a typical water-based ink.

Furthermore, since the dye used is a water-insoluble pigment, it will not fade even after long-term exposure, and will not cause any bleeding or the like even if it gets wet with writing condensation.

Next, the present invention will be specifically explained with reference to Examples. In addition,
In the text, parts and % represent heavy fils.

Example 1 A 50% solution of water-soluble polymer dispersants (30 parts methyl methacrylate, 20 parts hydroxyethyl methacrylate,
20 parts of butyl acrylate, N.

6 parts of a solution of a copolymer of 15 parts of N-dimethylaminoethyl methacrylate and 15 parts of methacrylic acid in 50 parts of isopropyl alcohol and 50 parts of butylcarpitol, 10 parts of carbon black pigment, 55 parts of water, and 2 parts of jetanolamine. and 20 parts of polystyrene plastic pigment (manufactured by Asahi Dow, 50% aqueous dispersion, particle size 0.5 μm, refractive index 1.59) and dispersed in a ball mill for about 20 hours, resulting in a pigment concentration of 7.5%. 10 parts of ethanol, 10 parts of butyl cellosolve, 27 parts of water
1 part and 10 parts of urea were added, and the mixture was further dispersed for 30 minutes to obtain a black pigment aqueous molecule LT liquid.

Next, this pigment aqueous dispersion was subjected to an ultracentrifuge to remove poorly dispersed coarse particles t, thereby obtaining a uniform black aqueous ink.

When this was set in a signboard and the writing properties were tested, it exhibited significantly superior dispersion stability, hiding power, and remarkable blackness, and had a smooth writing feel compared to the product without the addition of white resin particles.

Actual h'tr Example 2 50% solution of water-soluble polymer dispersant (12.5 parts of ethyl acrylate, 15 parts of butyl methacrylate, 1 part of styrene)
35 parts of a copolymer of butyl cellosolve and 15 parts of methylcarpitol, consisting of 5 parts and 7.5 parts of methacrylic acid.
solution), 10 parts of carphone black pigment, 25 parts of water, 0.3 part of potassium hydroxide, and polymethyl methacrylate white resin particles (manufactured by Souken Kagaku, MP-1000).
, refractive index 1.49) was added and dispersed for 20 minutes using a paint shaker. 10 parts of butanol, 18 parts of ethylene glycol and 83 parts of water were added and dispersed for an additional 30 minutes to obtain a black aqueous pigment dispersion. .

Next, this dispersion liquid was applied to an ultracentrifuge to remove poorly dispersed coarse particles, and further added with hensitriazole 10 as a rust preventive agent.
% ethylene glycol solution was added to obtain a uniformly dispersed black water-based ink. When 1.5 g of this water-based ink was incorporated into an internal ballpoint pen and a writing test was carried out, it showed significantly superior dispersion stability, hiding power, and line image formation with significantly higher blackness than a pen without white resin particles. It was done.

Example 3 Condensation ester of highly maleated oil of 1h fatty acid and propylene oxide adduct of bisphenol A (Dehydrated castor oil)
6 parts (50% solid content of jetanolamine aqueous solution), 3.3 parts of jetanolamine, 2 parts of ethylene glycol, and 3 parts of ethylenediaminetetraacetic acid disodium salt.
20 parts of water and 10 parts of carphone black pigment were dispersed in a ball mill for about 20 hours, and 21 parts of ethylene glycol, 19.7 parts of water and 15 parts of urea were added so that the pigment concentration was 10%. The mixture was dispersed for 30 minutes to obtain a black aqueous pigment dispersion.

Next, this dispersion was applied to an ultracentrifuge to remove poorly dispersed coarse particles, and epoxy white resin particles (manufactured by Toshi, Treval BP-[]3ooo, particle size 0.5 μm, refractive index 1.
5.30! 80 parts of aqueous dispersion) were added to obtain a uniform black water-based ink. When this was set in a cartridge-type brush pen and the writing properties were tested, a line image with significantly superior dispersion stability, hiding power, and blackness was obtained compared to a pen without the addition of white resin particles. Ta.

Claims (5)

[Claims] (1) A black aqueous ink composition for a writing instrument, which is characterized in that the aqueous ink composition for a writing instrument comprises a black pigment, a dispersant, and an aqueous medium, and further contains white resin particles. (2) The black aqueous ink composition for writing instruments according to claim (1), wherein the resin particles have a particle size of 0.1 to 1.0 μm. (3) The black aqueous ink composition for a writing instrument according to claim (1), wherein the resin particles have a refractive index of 1.4 to 1.6. (4) The black aqueous ink composition for writing instruments according to claim (1), wherein the black pigment is a carbon black pigment. (5) Claim No. 1 further containing a water-soluble resin
) The black aqueous ink composition for writing instruments as described in item 1.