JPS63305182A - Water-based ink composition for ball point pen - Google Patents

Abstract

PURPOSE:To obtain a water-based nonblotting ink excellent in lubricity and good in water resistance, by using a solution in a water-containing water-soluble organic solvent of a polymeric colorant which is a specified copolymer rendered water-insoluble by dyeing with an acid dye as a component. CONSTITUTION:A water-based ink composition comprising a solution in a water/ water-soluble solvent mixture of a polymeric colorant which is a copolymer comprising at least 40mol.% hydroxylated monomer and at least 5mol.% monomer having acid dye-dyeable dye sites and rendered water-insoluble by dyeing with an acid dye. Examples of said hydroxylated monomer include hydroxyethyl acrylate and hydroxypropyl methacrylate. Examples of said monomer having acid dye-dyeable dye sites include monomers having amine salts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water-based ink composition for ballpoint pens. More specifically, the present invention relates to a water-based ink for ballpoint pens that has excellent lubricity, is effective in preventing wear between the ball and tip, is free from bleeding, and has good water resistance.

[Conventional technology]

Traditionally, inks for ballpoint pens include oil-based inks made by dissolving oil-soluble dyes and oil-soluble resins in oil-based solvents such as phenyl cellosolve and benzyl alcohol, direct dyes,
There is a water-based ink made by dissolving a water-soluble dye such as an acid dye or a basic dye in an aqueous solution of a glycol-based, cellosolve-based, or glycol ether ester-based water-soluble solvent.

[Problem that the invention seeks to solve]

Oil-based ink is oil-based and highly viscous, so it has good water resistance and allows you to obtain handwriting without smearing. However, it has a hard writing feel and requires high pressure when writing to obtain clear handwriting. It had some disadvantages, such as a flop at the end. Water-based ink solves this problem, but since water-based ink is water-based and has low viscosity, it has poor water resistance and handwriting smudges.Furthermore, the ink has poor lubricity, so there is a problem between the ball and the cheer 1. There was a problem that there was a lot of wear and the initial soft writing feeling was lost.

For this reason, attempts have been made to add water-bath cutting oil or water-soluble resin to the water-based ink.

In the former, the abrasion resistance and writing feel are improved, but there is a problem that the handwriting tends to smear.In the latter, simply thickening with a water-soluble resin improves the smearing, but the abrasion resistance is not. It is enough. Furthermore, with both methods, water resistance cannot be improved at all.

On the other hand, attempts have been made to create water-based inks in which fine particles of pigment are dispersed in water using a surfactant. However, although this method improves water resistance, there are new problems in that the pigment particles tend to settle or adsorb, and the pigment particles cause a large amount of wear between the ball and the chia 1.

As described above, conventional water-based inks for ballpoint pens have their own problems with respect to water resistance of handwriting, bleeding, and lubricity of the ink.

[Means for solving problems]

In order to solve these problems with conventional water-based inks for ballpoint pens, as a result of intensive research, we developed a solution that thickens a copolymer made of a specific monomer composition using a polymer colorant dyed with an acid dye. water-based ink for ballpoint pens,
It has been found to have excellent lubricity, prevent wear on the ball and tip, not bleed, and have good water resistance.
We have arrived at the present invention.

That is, a copolymer consisting of 40 mol% or more of one or more monomers having a hydroxyl group and 5 mol% or more of one or more monomers having dicite dyeable with acid dyes. However, the objective was achieved with a water-based ink composition for a ballpoint pen, which is made of a polymer coloring material dyed with an acidic dye and made water-insoluble, and a mixed solvent of water and a water-soluble organic solvent.

The present invention will be explained in more detail below.

The polymer coloring material in the present invention can be produced by copolymerizing a monomer having a hydroxyl group and a monomer having dicite dyeable with an acid dye, and then dyeing the copolymer with an acid dye.

Examples of monomers having a hydroxyl group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropylethyl acrylate, and hydroxypropyl methacrylate.

diethylene glycol monoacrylate, diethylene glycol monomethacrylate, triethylene glycol monoacrylate), iJ ethylene glycol monomethacrylate, polyethylene glycol monoacrylate,
Examples include polyethylene glycol monomethacrylate.

Monomers having acid dye dyeable dicite that copolymerize with one or more of these monomers include monomers having amine salts, such as acroyloxyethyltrimethylammonium chloride, methacroyloxyethyltrimethyl Monomers having a quaternary ammonium base such as ammonium chloride, methacrylamide propyltrimethylammonium chloride, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate, diethylaminoethyl acrylate.

Salts of monomers having amine groups such as diethylaminoethyl methacrylate, tert-butylaminoethyl acrylate, tert-butylaminoethyl methacrylate, and vinylpyridine, such as hydrochloride, sulfate, N acid group, lactate, etc. Can be done.

The copolymerization ratio of a monomer having a dicite having a hydroxyl group and a monomer having an acid dye-dyeable dicite is determined to be 40% per unit of the monomer having a hydroxyl group based on the solubility of the obtained polymer coloring material as an ink and the color density of 0. If the monomer unit having acid dye-dyeable dicite is 5 mol % or more, satisfactory physical properties can be obtained as a base material for the aqueous ink of the present invention. If the monomer unit having a hydroxyl group is less than 40 mol %, the amount of the water-soluble organic solvent used becomes large and problems such as blurring and set-off of handwriting occur, which is not preferable. Furthermore, if the monomer unit containing acid dye dyeable dicite is less than 5 mol %, sufficient color density cannot be obtained as an ink, which is not preferable.

The method for polymerizing monomers having these hydroxyl groups and monomers having dicite dyeable with acid dyes is, for example, in a solvent such as water, at a polymerization temperature of 100°C or less, with an ordinary polymerization initiator, each monomer is added in bulk and partially. Alternatively, it can be carried out by continuously introducing it into a polymerization vessel.

Examples of the polymerization initiator used include persulfates such as potassium persulfate and ammonium persulfate, organic peroxides such as cumene hydroperoxide and t-butyl hydroperoxide, or 2-azobis(2-amidinopropane). ) dibasic acids etc. can be used.

The molecular weight of the resulting copolymer depends on the concentration of each monomer present in the polymerization system, the amount of polymerization initiator used, the polymerization temperature, etc.

The monomer concentration can be selected arbitrarily, but is generally 5 to 5.
It can be carried out at 50% by weight. Polymerization at a high concentration is not preferable because the viscosity of the polymerization system becomes high and it becomes difficult to remove the heat of polymerization, and polymerization at a too low concentration is not preferable because it becomes economically disadvantageous. When the amount of the agent used is increased, the molecular weight of the polymer tends to decrease, and when the amount is decreased, the molecular weight tends to increase.

Although the molecular weight of the copolymer thus obtained is not particularly limited, it affects the viscosity of the ink composition.

When the content of the polymer colorant in the ink composition is high, if the molecular weight of the copolymer is too large, the viscosity of the ink composition tends to become too high and the ink discharge rate tends to decrease. A weight average molecular weight of 1,000,000 or less, preferably 500,000 or less is good. Furthermore, if the molecular weight of the copolymer is too small, effects such as lubricity and bleeding prevention will not be significant, so a weight average molecular weight of 10,000 or more is preferred.

The present invention is not limited in any way by the method for producing such a copolymer.

Next, the copolymer obtained in step 1 is dyed with an acidic dye. Any dye may be used, and in addition to ordinary acid dyes, direct dyes, acidic mordant dyes, and the like can also be suitably used.

The dyeing method is not particularly limited, but is basically achieved by, for example, contacting an aqueous solution of an acidic dye with an aqueous solution of the copolymer of the present invention.

The copolymer of the present invention itself is water-soluble, but when dyed, the dicite and acid dye in the copolymer form ionic bonds and become hydrophobic, making the dyed copolymer water-insoluble. and is precipitated from the dyeing system.

The dyeing treatment conditions are not particularly limited, but from room temperature to 1
It can be carried out at 00°C, usually 40 to 90°C.

After such dyeing treatment, the dyed product of the copolymer of the present invention, that is, the polymer coloring material, is separated from the dyeing solution by a method such as filtration.

The present invention is not limited in any way by such dyeing treatment method or separation method.

The water-based ink composition for ballpoint pens of the present invention can be obtained by dissolving the polymer colorant thus obtained in a mixed solvent solution of water and a water-soluble organic solvent, but the content of the polymer colorant is It is desirable that the ink composition contains 10 to 50% by weight, preferably 15 to 40% by weight.

If the content of the polymeric coloring material is too large, the viscosity of the ink composition becomes too high, which is undesirable. If the content is too small, the color density becomes low, which is not preferable.

The content of the mixed solvent solution of water and a water-soluble organic solvent used in the present invention is 50 to 90% by weight in the ink composition,
Preferably, it can be contained in an amount of 60 to 85% by weight.

The content of the water-soluble organic solvent in the mixed solvent solution is usually 10
It is desirable to contain up to 60% by weight, preferably 20 to 50% by weight. If the content of the water-soluble organic solvent is too large, problems such as blurring and set-off of handwriting may occur, which is not preferable.

The water-soluble organic solvent is represented by the following general formula [1], and includes, for example, ethylene carbonate, propylene carbonate, r-butyrolactone, r-methylbutyrolactone,
2-pyrrolidone, N-methyl-2-pyrrolidone, 1.3
-dimethylimidazolidinone and the like.

General formula [1] (R represents H or 04; X represents NH, NOH, or 0; Y represents CHl or 0). The colorant can be selected depending on the content of the polymeric colorant in the product and other additive components, but since the colorant is a polymer, the viscosity is higher than the several centipoise (cps) of conventional water-based ink for ballpoint pens, and it is usually 500 centipoise (cps). -800 aptss, preferably 1000-5000 ape.

If the viscosity of the ink composition is too high, the amount of ink ejected tends to decrease, and if the viscosity is too low, handwriting may bleed, which is undesirable.

The ink composition of the present invention can be used by itself as a water-based ink for ballpoint pens, but if necessary, additive components used in ordinary water-based inks for ballpoint pens may be added, such as glycomyl-based inks such as ethylene glycol, propylene glycol, and diethylene glycol. Solvents, cellosolve solvents such as methyl cellosolve and ethyl cellosolve, evaporation inhibitors such as glycol ether ester solvents such as ethylene glycol monoethyl ether acetate, potassium sorbitanate, sodium benzoate, sodium pentachlorophenol, sodium dehydroacetate, etc. Preservative,
Rust inhibitors such as benzotriazole and tolyltriazole,
Alternatively, nonionic and anionic surfactants can be added, and water-soluble resins such as alginic acid, carboxymethylcellulose, methylcellulose, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol, and polyvinylpyrrolidone can also be added. .

[Action of the invention]

The reason why the water-based ink composition for ballpoint pens of the present invention has excellent lubricity is not clear, but it is because the polymer coloring material of the present invention has dye molecules dyed in a copolymer. It is thought that the presence of hydroxyl groups in the polymer chain and the thickening effect of the polymer are involved.

Also, why is the water resistance of handwriting so good? □
This is because the polymer coloring material of the present invention is insoluble in water itself, and has excellent affinity with water because it has a hydroxyl group and an ionic bonding group. This is thought to be because O can be dissolved in a mixed solvent solution of water and a water-soluble organic solvent. The scope is not limited in any way by the example. Note that "parts" and "%" used below are based on weight unless otherwise specified.

The polymer coloring material of the present invention was manufactured by the method described below.

In addition, it was determined by conducting elemental analysis using the yari υkenzoku haibetsu 楢jinheatan νpu.

Production Example 1 389.5 parts of water, 70 parts of 2-hydroxyethyl methacrylate, and methacrylate D were placed in a nitrogen-substituted polymerization flask.
315 parts of MO-80 (methacryloid oxyethyltrimethylammonium chloride, purity 80%, manufactured by Sanyo Chemical Industries, Ltd.) was charged, the temperature was raised to 90° C. with stirring, and 3 parts of ammonium persulfate was added to initiate polymerization. Subsequently, stirring was continued, and polymerization was carried out at 90° C. for 5 hours.

The monomer composition ratio in the obtained copolymer was 79 mol% of 2-hydroxyethyl methacrylate.

The methacrylate DMO-80 was 21 mol%.Next, 102 parts of Sumirambra, RiWA (acid dye 0 air, Doppler, Ri 52, manufactured by Sumitomo Chemical ■) were mixed with 200 parts of water.
01) The obtained copolymer aqueous solution was added to the aqueous solution dissolved in Q, and stirred at 65°C for 30 minutes to precipitate the copolymer dyed product, filtered and dried to obtain the high quality polymer of the present invention. Molecular coloring material 13
I got 7 copies.

Production Example 2 20 parts of water was charged into a polymerization flask purged with nitrogen, and the temperature was raised to 90°C. 50 parts of 2-hydroxyethyl methacrylate, Premer PIC-550 (polyethylene glycol monomethacrylate, purity 93%, manufactured by NOF ■) 21
．． 5 parts of methacrylate) DMO-8037, 5 parts of water
A monomer aqueous solution dissolved in 71 parts and a polymerization initiator aqueous solution prepared by dissolving 4 parts of ammonium persulfate in 96 parts of water were added to 9
Polymerization was carried out by dropwise addition over 3 hours at 0°C. Subsequently, stirring was continued, and polymerization was carried out at 90° C. for 2 hours.

The seven-mer composition ratio in the obtained copolymer was 67 mol% of 2-hydroxyethyl methacrylate.

Premer pg-sso is a mol%, meI'? I.J.
V-to-DMO-80 was 25 mol%.

The obtained copolymer was dissolved in 2000 parts of water in an aqueous solution of KS8PT-Plastic, Ri-W-1 (acid dye ax, Doppler, Ri-1) 9, manufactured by Hodogaya Chemical Co., Ltd.) 74.4i in 2000 parts of water. An aqueous solution was added and stirred at 60°C for 30 minutes to precipitate the dyed copolymer, followed by filtration.

After drying, 138 parts of the polymeric coloring material of the present invention was obtained.

Production Example 3 20 parts of water was charged into a polymerization flask purged with nitrogen, and the temperature was raised to 90°C. An aqueous solution of 60 parts of 2-hydroxyethyl methacrylate, 1050 parts of methacrylate IIMO dissolved in 270 parts of water, and 8 parts of ammonium persulfate.
A polymerization initiator aqueous solution prepared by dissolving 3 parts of water in 92 parts of water was heated at 90°C.
It was added dropwise over a period of time to polymerize. Continue stirring until 9
Polymerization was carried out at 0°C for 2 hours.

The monomer composition ratio in the obtained copolymer was 70 mol% of 2-hydroxyethyl methacrylate.

The methacrylate DMO-80 was 30 mol%.

Next, add 9 parts and 6 parts of 5PT-Plastic, RiW-1 (acidic dye O-Kashi, Doppler, Ri-1) 9, manufactured by Hodogaya Chemical Industry ■, and 2 parts of water.
The resulting copolymer aqueous solution was added to an aqueous solution dissolved in 1,000 parts, stirred at 70°C for 30 minutes to precipitate a dyed copolymer, and filtered.

After drying, 147 parts of the polymeric coloring material of the present invention was obtained.

Example 1 40 parts of the polymer colorant obtained in Production Example 1, N-methyl-2
- Stir and dissolve 24 parts of pyrrolidone and 36 parts of water to obtain a viscosity of 2.
A water-based black ink of 200 cps (6 rpm, 25° C., Type 1 viscometer, Tokyo Keiki) was obtained.

Example 2 40 parts of polymer colorant obtained on m side 2, N-methyl-2
- Stir and dissolve 30 parts of pyrrolidone and 30 parts of water to obtain a viscosity of 4.
A water-based black ink of 800 cps (6 rpm, 25° C., B-type viscometer, Tokyo Keiki) was obtained.

Example 5 35 parts of polymer colorant obtained in Production Example 3, N-methyl-2
- Stir and dissolve 30 parts of pyrrolidone and 35 parts of water to obtain a viscosity of 1.
A water-based black ink of 1100 cps (6 rp, 25° C., B-type viscometer, Tokyo Keiki) was obtained.

Example 4 30 parts of polymer colorant obtained in Production Example 3, Popal PVA
-420 (polyvinyl alcohol, Kuran) 2 parts, N
-Methyl-2-pyroIJ)”: / 3471°Water 34
Stir and dissolve 1 part to give a viscosity of 2100 cps (6 rpm, 2
A water-based black ink was obtained at 5° C. using a B-type viscometer (Tokyo Keiki).

Comparative example 1 SPT-Black W-1 (Acidic dye C air stain.

Doppler, Ri1) 9, Hodogaya Chemical Industry ■) 15i.

10 parts of polyethylene glycol (average molecular weight 20,000, manufactured by Wako Pure Chemical Industries, Ltd.), 30 parts of N-methyl-2-pyrrolidone, and 45 parts of water were stirred and dissolved to give a viscosity of 100 opa.
(6 rpm, 25°C, B-type viscometer, Tokyo Keiki) was obtained.

Comparative example 2 SPT-Pla, RiW-1 (acid dye 0 air acid plastic,
1) 9, manufactured by Hodogaya Chemical Industry ■) 15 parts.

Popal PTA-420 (polyvinyl alcohol, Kuran) 8 parts, N-methyl-2-pyrrolid 730 parts, water 4
Stir and dissolve 7 parts to obtain a viscosity of 2400 ops (6 rpm
, 25°C, B-type viscometer, ■Tokyo Keiki) water-based black ink was obtained.

The ink compositions of Examples 1 to 4 and Comparative Examples 1 to 2 above were filled into metal tip ballpoint pens (c pole diameter α5m), and the sinking of the ball, writing feel, water resistance of handwriting, and bleeding were evaluated as follows. The test was conducted and the results are shown in Table 1.

(1) Sinking of the ball Using a writing tester, the writing speed was 4m/win.

Load 1009. The ball was written for 500 m at a writing angle of 70°, and the ball protrusion before and after writing was measured using a microscope (metal specification), and the sinking of the ball was determined from the difference.

(2) Writing taste Using a writing tester, the writing speed was 4 m/win.

After writing for 500 m under the conditions of a load of 100 g and a writing angle of 70°, the writing was done freehand on high-quality paper, and the smooth writing was rated as 0, and the writing that was not smooth was rated as ×.

(31 was written freehand on water-resistant high-quality paper, and after 1 minute, it was immersed in water for 1 hour and the state of the handwriting was visually observed. 01 indicates that there is no change, and 01 indicates that most of the handwriting has flowed out.

(4) Smearing Handwriting was written freehand on high-quality paper, and the state of the handwriting was visually observed. No smearing was rated as ○, those with slight smearing were rated Δ, and those with significant smearing were rated X.

Table 1 [Effects of the Invention] The aqueous ink composition of the present invention is characterized in that a copolymer consisting of a monomer having a hydroxyl group and a monomer having an acid dye-dyeable dicite has a polymer color dyed with an acid dye. It has excellent lubricity and is effective in preventing wear between the ball and tip, providing a smooth writing experience, as well as preventing smudging of handwriting and being water resistant. It has characteristics such as:

Claims (4)

[Claims] (1) One or two monomers having a hydroxyl group
A copolymer consisting of 40 mol % or more of a species or more and 5 mol % or more of one or more acid dye-dyeable monomers having dicite is dyed with an acid dye and becomes water-insoluble. A water-based ink composition for a ballpoint pen comprising a solution of a polymer coloring material in a mixed solvent of water and a water-soluble organic solvent. (2) The monomer having a hydroxyl group is hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropylethyl acrylate, hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, triethylene glycol monoacrylate, triethylene glycol monomethacrylate, polyethylene glycol monoacrylate The aqueous ink composition for a ballpoint pen according to claim (1), which is an acrylate or a polyethylene glycol monomethacrylate. (3) Claim No. 1, wherein the acid dye-dyeable dicite-containing monomer is an amine salt-containing monomer.
The aqueous ink composition for ballpoint pens described in 2. (4) The water-based ink composition for a ballpoint pen according to claim (1), wherein the water-soluble organic solvent is represented by the following general formula [1]. General formula [1] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (R is H or CH_8; X is NH, NCH_8
or O; Y represents CH_2 or O; )