JP2001192599A - Oil-based ink composition for ballpoint pens - Google Patents

Abstract

(57) [Summary] A resin having, as a main solvent, one or more solvents having a vapor pressure of 1 mmHg or more at 20 ° C. and a solubility of 7% by weight or less in ethanol at 25 ° C.,
A pressurized ballpoint pen ink containing more than a resin having a solubility in ethanol at 25 ° C. of more than 7% by weight. [Effect] A ballpoint pen which can obtain a line which cannot be falsified with an easily available solvent such as ethanol or methanol and which has an excellent line drying property is provided. Conventionally, ballpoint pen inks using highly volatile solvents have been proposed, but by supplying them as inks for pressurized ballpoint pens using members having excellent gas permeability, ballpoint pens with high storage stability were obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition for a pressurized ballpoint pen, and more particularly, a writing line is easily dried.
Also, the present invention relates to an oil-based ink for ballpoint pens which has excellent fastness of writing lines and is excellent in preventing tampering of drawing lines.

[0002]

2. Description of the Related Art In recent years, inks for pressurized ballpoint pens are obtained by dissolving or dispersing dyes and pigments and resins using glycols, glycol ethers and alcohols such as benzyl alcohol as a main solvent. Oil-based ballpoint pens, including pressurized ballpoint pens, are used to obtain dark lines with a small amount of ink, or to prevent ink dropping, and to obtain sufficient lubricity between the ball and the ball holder at the pen tip. A large amount of pigments and resins must be dissolved. Therefore, the pigment dispersant, dye and resin used are selected from those which are easily dissolved in these solvents. Those which are easily dissolved in alcohols such as glycols, glycol ethers and benzyl alcohol are generally easily dissolved in ethanol and methanol. Ethanol and methanol are solvents that are easily available for disinfection and fuel use, and they can be used to alter the drawing of oil-based ballpoint pens.

[0003] In addition, current ballpoint pens have poor drying properties when written on a writing surface such as coated paper, which has a low ink absorbing power, and the drawing lines may be significantly stained by a slight rubbing. In addition, when writing characters with plain paper, the drawing lines may be rubbed by hand and the writing surface may be significantly stained.

[0004]

Ethanol and methanol are commonly available organic solvents. If a line which is hardly soluble in these solvents can be obtained, it can be said that it is very effective in preventing the falsification of the line. In general, pigment dispersants, dyes, and resins that do not dissolve in methanol or methanol are hardly soluble in alcohols such as glycols, glycol ethers, and benzyl alcohol. JP-A-11-
In 21491, a solvent having a solubility parameter of 5 to 15 was used, and mainly glycol ethers, glycol ether acetates, esters and derivatives thereof,
An ink for writing implements containing a resin having a solubility in water and ethanol of 7% by weight or less is disclosed. In the present invention, the dyes and pigments are preferably 25% by weight or less,
In the case of oil-based ballpoint pen inks, the content of dyes and pigments in oil-based ballpoint pen inks with sufficient drawing line fastness (light fastness, water resistance, acid resistance, alkali resistance, etc.) is generally a pigment content based on the total amount of the ink. In the case of a dye, it is 15 to 30% by weight, and in the case of a dye, it is 25 to 40% by weight. Further, in the case of an oil-based ink for a ballpoint pen, polyvinylpyrrolidone, polyethylene glycol having a high degree of polymerization, or the like is used as a measure against dropping of the ink, which is a problem peculiar to a ballpoint pen. Also, the resin used as a dispersant for the pigment is often easily soluble in ethanol. If a large amount of such a resin which is easily soluble in ethanol is contained, even if a resin which is hardly soluble in ethanol is used, it is not possible to obtain the robustness to ethanol or methanol of the drawn line. For this reason, an oil-based ballpoint pen ink having excellent overall performance cannot be obtained only by the technique disclosed in JP-A-11-21491.

Also, when writing a horizontal character string from the left with the left hand, writing a horizontal character string from the right with the right hand (such as Arabic), and writing characters in normal vertical writing on paper with little ink absorption. In such cases, the drawn lines may be rubbed by hand to stain the drawn lines, but this is a problem that can be prevented if the drying property of the ink is improved.

There is a need for a ballpoint pen that is stable as an ink and hardly dissolves writing lines in a readily volatile solvent such as ethanol or methanol. Further, ideally, an ink having a quick-drying property that does not stain a writing line by rubbing is desired.

[0007]

Means for Solving the Problems The inventors of the present invention have improved the above-mentioned drawbacks and have changed the technical idea of Japanese Patent Application Laid-Open No. 11-21491.
Other excellent line fastness, less dripping of the ink, shorter bleeding at the start of writing, excellent stability over time, etc. Therefore, even if a resin that is easily soluble in ethanol is used, the amount of the easily soluble resin is smaller than that of the hardly soluble resin, and the amount of the easily soluble resin is limited to 5% or less of the total amount. Succeeded in developing oil-based ballpoint pen inks with excellent performance. In addition, some resins that are hardly soluble in ethanol are easily soluble in glycol ethers, etc., and the use of glycol ether, which has relatively high volatility, as the main solvent can improve the drying characteristics of the writing lines of ballpoint pens. I found that it was possible. Further, the pressurized ballpoint pen has a structure in which ink is mainly extruded by gas pressure, and is premised on using a member having low gas permeability. Therefore, the present invention has been completed in view of the fact that the ink has a suitable property as an ink container using a highly volatile solvent used in the present invention.

An invention similar to the present invention is disclosed in Japanese Patent Application Laid-Open No. H4-1392.
73 and JP-A-4-168169. The present invention uses highly volatile propylene glycol ethers or aliphatic alcohols having 4 or less carbon atoms as main solvents,
Use more than one kind of resin. The use of a highly volatile main solvent and the use of two or more resins having different properties are similar to the present invention. However, in order to improve the sticking property of the drawing line of the oil-based marking pen,
A strong resin and a flexible resin are used so as not to be compatible with each other, which is different from the object and the purpose of the present invention. The resin which is easily soluble in ethanol in the present invention is used for improving the performance as a ballpoint pen, and is used at a minimum in order to prevent dropping of the ink and to ensure the lubricity of the ball and the dispersion stability of the pigment. In addition, a resin that is hardly soluble in ethanol is used as a main resin in order to obtain an effect of preventing falsification of a drawing line. In the present invention, the respective resins may be completely compatible with each other, and are not distinguished by the degree of oxidation of the resins.

In the present invention, the vapor pressure of the main solvent of the ink is specified, but the dissolving ability is slightly different for each solvent. For this reason, as a coloring agent used in the ink composition, it is necessary to sufficiently confirm the stability of dissolution or dispersion of the dye and / or the pigment, but it is not limited that a specific material cannot be used. It is preferable that the dispersant of the dye or the pigment does not dissolve in ethanol, but the gist of the present invention is to improve the water resistance and the alcohol resistance with the added resin. There is an improvement in alcoholicity. When using these coloring agents, they can be used alone or in appropriate combination. The amount of the coloring agent is in the range of 10 to 50% by weight based on the total weight of the ink, and is preferably 15% by weight.
To 40% by weight. When the colorant is a dye, the content is most preferably 25 to 40% by weight, and when the colorant is a pigment, the content is most preferably 15 to 30% by weight. Even coloring agents that have both coloring power and fastness like carbon black
When it is less than 5% by weight, the drawing feels thin and 10% by weight
If it is below, it is not practical. When the content of the colorant exceeds 40% by weight, the solid content in the ink increases, and the solubility of the resin which is hardly soluble in ethanol of the present invention is uneasy. Precipitates out.

The main solvent used in the present invention has a vapor pressure of 1 mmHg or more at 20 ° C., and it can be said that the main solvent has a considerably higher volatility than solvents usually used for ballpoint pens. Organic solvents usually used for ballpoint pens include high-boiling alcohols such as benzyl alcohol, glycols such as ethylene glycol, and high-boiling glycol ethers such as ethylene glycol monophenyl ether. Benzyl alcohol and glycols are not used as the main solvent in the present invention even though they may be used supplementarily from the viewpoint of dissolving power. The present invention aims at a quick-drying ink, and in principle uses an ink having a high vapor pressure near normal temperature as a main solvent. Suitable as the main solvent are glycol ethers and glycol ether acetates. Alcohols may also be used from the viewpoint of quick-drying, but from the viewpoint of another purpose of the present invention, "tamper prevention using lower alcohol", to add a large amount of "a resin that is hardly soluble in ethanol". However, it is difficult to use them as main solvents from the viewpoint of their dissolution stability. Although not verified in Examples of the present invention, the use of a hydrocarbon-based solvent or a ketone-based solvent to form an ink does not depart from the gist of the present invention.

If the main solvent is selected from those having high volatility, a quick-drying ink can be prepared even if a small amount of a high boiling point solvent or a fatty acid is added. In particular, unsaturated fatty acids such as oleic acid and linoleic acid not only reduce the friction between the ball of the pen tip and the ball holder, but also have a strong This is a preferred additive because it is effective in preventing the formation of solids and maintaining smoothness at the time of next writing. In addition, solvents used in traditional ballpoint pens, such as benzyl alcohol and ethylene glycol monophenyl ether, also have strong dissolving power, improving the stability over time of inks, and, like fatty acids, have the effect of preventing writing stutter during writing. is there. However, as a matter of course, as the amount added increases, the quick-drying property also deteriorates. The standard of the amount of the fatty acid to be added is within 5%, preferably within 3%, but it is preferable to use a small amount of the fatty acid because 0.1% has an effect of addition, rather than not being used at all. In addition, a high boiling auxiliary solvent is also used.
0% or less, preferably 10% or less is good. If the main solvent has sufficient dissolving power, it may not be used. The main solvent may be used singly or as a mixture of two or more kinds. The compounding amount is preferably in the range of 20 to 70% by weight based on the total amount of the composition. More preferably, it is 40 to 60% by weight. If the content is 20% by weight or less, the solubility of the dye or the resin for preventing dropping may be insufficient. In order to sufficiently obtain stable solubility over time, the content is preferably 40% by weight or more. Also, in order to satisfy various performances as ink for ballpoint pens, the amount of vehicle will be inevitable if necessary components such as coloring agents, resin for preventing dropping, lubricants, other dispersants and aging stabilizers are added. It becomes 70% by weight or less. Further, when the amount of the additive is increased in order to obtain sufficient coloring properties and fastness of drawing lines in the ink, the content becomes 60% by weight or less.

[0012] The resin in the oil-based ballpoint pen ink is
As described above, it is necessary mainly to prevent ink dripping and to ensure lubricity between the ball of the pen point and the ball holder. In the present invention, the solubility of these resins is more important than the structure. In the present invention, “a resin having a solubility in ethanol at 25 ° C. of 7% by weight or less” and “a resin having a solubility in ethanol at 25 ° C. of 7% by weight” are used.
Although it is expressed as "resin larger than% by weight", it means "resin which is hardly soluble in ethanol" and "resin which is easily soluble in ethanol". Since the resin is determined to be easily soluble or hardly soluble at the stage of designing the molecule, it is mostly divided into a resin that dissolves only 5% or less and a resin that dissolves 10% or more. Since the technical concept of JP-A-11-214912 was further improved as an oil-based ballpoint pen ink, 7% which is the criterion in JP-A-11-21491 was used.
Was defined as the boundary.

The ink for pressurized ballpoint pens of the present invention includes polyvinylpyrrolidone, polyethylene glycol having a molecular weight of 10,000 or more, acrylic resin, phenolic resin, ketone resin, polyvinyl acetal, styrene acrylic acid resin, acrylic betaine resin, styrene Maleic acid resin,
It is desirable to contain at least one resin selected from resins easily soluble in ethanol such as a polyester modified resin.
Polyvinylpyrrolidone, polyethylene glycol having a molecular weight of 10,000 or more, acrylic resin, phenolic resin, ketone resin, and polyvinyl acetal (of high molecular weight) are particularly effective in preventing ink dropping. In addition, polyvinyl acetal (of low molecular weight), styrene acrylate resin, acryl betaine resin, styrene maleate resin, and polyester modified resin are excellent in the effect of stabilizing pigment dispersion.

The resin which is hardly soluble in ethanol in the present invention includes rosin-modified phenolic resin, rosin-modified maleic acid resin, rosin-modified acrylic acid resin, hydroxy-modified vinyl acetate, carboxy-modified vinyl acetate, polyester-modified resin, and acrylic-modified resin. Resin, fluorine resin, phenol resin, and ketone resin. Polyester modified resin, acrylic resin, fluorine resin, phenolic resin, and ketone resin are easily or slightly soluble in ethanol. Both performances to ensure the lubrication of the receiving holder are exhibited.

The total amount of the resin used in the present invention is preferably in the range of 5 to 30% by weight with respect to the total amount of the ink composition, regardless of whether the resin is hardly soluble or readily soluble in ethanol. If the content is less than 5% by weight, the effect of preventing dropping and the improvement of lubricity are not recognized,
When the content is 30% by weight or more, adverse effects such as an increase in writing quality and an increase in sharpness at the start of writing occur.

The lower the solubility in ethanol at 25 ° C., the better the alcohol resistance. However, although this is also an empirical value, even if a large amount of hardly soluble resin is used, if the amount of easily soluble resin is large, the drawn line will be decomposed with ethanol or methanol, and the alcohol resistance of the drawn line will be poor. I can't get it. It seems that this phenomenon occurs when a resin that is easily soluble in ethanol enters at least 5% by weight based on the total amount of ink. When the amount of the easily soluble resin is 5% by weight or less and the amount of the hardly soluble resin exceeds the amount of the hardly soluble resin, the characteristics of the easily soluble resin exceed the characteristics of the hardly soluble resin, and the alcohol resistance is improved. Is not recognized.

Next, the present invention will be described in more detail by way of examples. Each test was performed as follows. The ball-point pen used is mainly a member of a commercially available uniprinter pen pressurized oil-based ball-point pen FL, and only a pen tip (ball-point tip) is a commercially available SA-S fine print (both are Mitsubishi Pencil Co., Ltd.)
The same product name was used. The ball diameter is 0.7mm,
Nitrogen gas was sealed at 2 atm. This is called refill,
It was inserted into a shaft of a commercially available SN-101 (trade name of Mitsubishi Pencil Co., Ltd.) together with a spacer to obtain a ballpoint pen for a writing test. (Test 1) Dropping test of ink The dropping of the ink in the drawing line (300 m) is visually evaluated. Ten points were given on a 10-point scale, with no points at all, nine points with good search, and one point with conspicuous spots over almost the entire area. The best is 10 points and the worst is 1 point. (Test 2) Alcohol resistance test From the drawing lines used in Test 1, a portion with less ink dripping was selected, cut out, immersed in ethanol specified in JIS K 8101 for 1 hour, and the drawn line after natural drying was drawn before immersion. And evaluated. One line is not legible. J
2 points if it is about the first grade of the gray scale specified in IS L 0804. Class 1-2 has 3 points. Second grade is 4 points. The score was increased for each rank. (The highest is class 5 equivalent 1
(0 points) 1 point is the worst, and 10 points is the best. (Test 3) Drawing line drying test One line is drawn freehand on “Normal art paper” specified in JIS P 3105, and after approximately 20 seconds, approximately 0.98 N
Rub with your finger under the load. 10 points if there is no change in the drawing line.
There is no ink dragging, but 8 points with blurred drawing lines.
6 points with thin traces. Although traces of dragging are clearly visible, four points are readable. If the stroke color and the ink density of the trail are the same,
point. The point where the trace of the drawing line disappeared was regarded as 0 point, and each point was repeated 10 times, and the average point was evaluated. 1
0 is the best and 0 is the worst.

The resins used in this embodiment are shown below. Judgment as to whether it is easily soluble or not soluble in ethanol is performed by adding 3% by weight of resin to 93% by weight of reagent grade ethanol, stirring at room temperature for 3 hours, and then using an ultrasonic cleaner at 60 ° C. for 2 hours. After cooling to 25 ° C by ultrasonic irradiation, those that were visually dissolved were “easy to dissolve” and those in which undissolved substances were confirmed were “poorly soluble”.
It was determined. "Poorly soluble resin A" Beccasite # 1111 (rosin-modified maleic resin; Dainippon Ink and Chemicals, Inc.)
(Trade name) “Slightly soluble resin B” MM-401-1 (acrylic resin; trade name of Fujikura Kasei Co., Ltd.) “slightly soluble resin C” Solsperse 24000SC (polyester modified resin; trade name of ICI company) “Easily soluble resin A” Rubiscol K-90 (polyvinyl pyrrolidone; trade name of BASF) "Easily soluble resin B" ESREC BM-1 (polyvinyl acetal; trade name of Sekisui Chemical Co., Ltd.) "Easily soluble resin C" PEG 4 million (polyethylene glycol) ; Reagent manufactured by Wako Pure Chemical Industries, Ltd.)

The ink formulations used in the examples are described below. Example 1 Moogul-L 20% by weight (carbon black, trade name of Cabot) Easily soluble resin B4 {dipropylene glycol monopropyl ether 20} propylene glycol monomethyl ether 48.4} After kneading with a bead mill and filtering, Example 5 was added to the above, and slightly soluble resin B 5.1 {easy soluble resin C 1} oleic acid 1 {tetraglycerin distearate 0.5} was added. Example 2 Cyanine Blue 4920G (Pigment, trade name of Dainichi Seika Co., Ltd.) 25% by weight Hardly soluble resin C 6 〃 propylene glycol monobutyl ether 39 〃 polypropylene glycol 400 10 〃 Soluble resin A 17 Easily soluble resin A 2 {oleic acid 1} The above was kneaded, and then filtered, to give Example 2.

The ink formulations used in the comparative examples are described below. Comparative Example 1 Mogul-L 20% by weight (carbon black, trade name of Cabot Co.) Easily soluble resin B 5 {dipropylene glycol monopropyl ether 20} propylene glycol monomethyl ether 48.4} After kneading with a bead mill and filtering, Comparative example 1 was added by adding slightly soluble resin B 4.1 {easy soluble resin C 1} oleic acid 1 {tetraglycerin distearate 0.5}. Comparative Example 2 Cyanine blue 4920G 25% by weight Poorly soluble resin B 6 {Ethylene glycol monobutyl ether 39} Polypropylene glycol 400 10} After kneading and filtering with a bead mill and filtering, a poorly soluble resin A 17 A readily soluble resin A 2 {Oleic acid 1% or more was kneaded and then filtered to obtain Comparative Example 2.

The results are shown in Table 1.

[Table 1] Test results

Example 1 and Comparative Example 1 have slightly different ratios of the soluble resin (in ethanol) and the poorly soluble resin, and show almost the same performance. The difference was two ranks, a clear difference. This is because Comparative Example 2 contains more soluble resin than hardly soluble resin. The difference between Example 2 and Comparative Example 2 is due to the difference in vapor pressure of the main solvent. The structure of propylene glycol monobutyl ether and ethylene glycol monobutyl ether differ only in whether or not there is one methyl group, but the vapor pressure is about 1.2 mmH at 25 ° C.
g, the latter is less than 1 mmHg. This is an example that appears as a difference between whether or not the drawing line is dragged due to this difference.
Originally, if the amount of PEG400 or oleic acid was adjusted, the evaluation score of Test 3 of this example could be increased a little more even if ethylene glycol monobutyl ether was used. Since the performance such as writing taste must be taken into consideration, it is not considered that low volatile components should be easily reduced. Therefore, it is preferable that the main solvent has a vapor pressure of 1 mmHg or more at 25 ° C.

In Test 2, the ink of the present invention using a dye as a coloring agent showed the same tendency as in the present invention, such as improvement in alcohol resistance from 2 ranks to 4 ranks.

[0024]

As described above, the ink for pressurized ballpoint pens of the present invention has good drying characteristics of drawing lines at 25 ° C. by using a highly volatile solvent by making use of the gas barrier property unique to the pressurized ballpoint pen structure. By using a resin having a low solubility in ethanol, it is effective to prevent tampering of a drawn line by an easily available volatile solvent such as ethanol.

Claims (3)

[Claims] 1. The internal pressure of an ink storage section is made higher than normal pressure. Or a pressurized ballpoint pen that intentionally presses the ink toward the pen tip by the force of a spring or the like.
The total of one or more kinds of organic solvents having a vapor pressure of 1 mmHg or more is 30% by weight or more based on the total amount of the ink,
An ink for a pressurized ball-point pen, which contains a resin having a solubility in ethanol at 5 ° C of 7% by weight or less more than a resin having a solubility in ethanol at 25 ° C of more than 7% by weight. 2. The ink according to claim 1, wherein the total amount of the resins having a solubility in ethanol at 25 ° C. of more than 7% by weight is 5% by weight or less based on the total amount of the ink. 3. A resin having a solubility in ethanol at 25 ° C. of more than 7% by weight is polyvinyl acetal,
Selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol having a molecular weight of 10,000 or more, styrene acrylic acid resin, acrylic betaine resin, styrene maleic acid resin, modified polyester resin, acrylic resin, phenolic resin, and ketone resin, and ethanol at 25 ° C. Resins having a solubility in water of not more than 7% by weight are rosin-modified phenolic resin, rosin-modified maleic acid resin, rosin-modified acrylic acid resin, hydroxy-modified vinyl chloride, carboxy-modified vinyl chloride, polyester-modified resin, acrylic resin, fluorine-based resin The oil-based ink for a ball-point pen according to claim 1, which is a resin selected from the group consisting of a resin, a phenolic resin, and a ketone resin. And an ink for a pressurized ballpoint pen according to claim 2.