JPH11246812A - Oil-based ink for ball-point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink extremely slightly causing the flopping down of the ink and good in writing quality by including polyvinylpyrrolidone and a specified compound therein and regulating the pH to a specific value or below. SOLUTION: This ink is obtained by including (A) polyvinylpyrrolidone and (B) a compound having >=2 phenolic hydroxyl groups based on one benzene nucleus (e.g. ethyl gallate, gallic acid or tannic acid) and regulating the pH to <=7.5 with oleic acid, etc. An organic solvent such as ethylene glycol monophenyl ether or benzyl alcohol in an amount of preferably 30-70 wt.% based on the total amount of the ink, a colorant, a resin, etc., such as a ketone resin in an amount of preferably 10-45 wt.% based on the total amount of the ink can be contained in the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-based ink for a ball-point pen, and more particularly to an oil-based ink for a ball-point pen in which dripping phenomenon (hereinafter referred to as "ink spot") peculiar to the ball-point pen is suppressed as much as possible.

[0002]

2. Description of the Related Art A conventional oil-based ink for a ball-point pen is generally composed of an organic solvent, a coloring agent, a resin and the like, and uses a relatively tacky ink having a viscosity of 7000 to 15000 cps to prevent ink leakage.

[0003] In this case, since the ink has high adhesiveness, the ink sticks to the ball at the time of writing, a part of the ink on the ball remains without being transferred to the paper surface, and the ink is thickly deposited on the rotating ball. . The accumulated ink accumulates in the opening of the tip of the ball-point pen tip, and drops to the paper surface at a stage where the ink accumulates to some extent, forming an ink spot. This phenomenon of ink bottling not only impairs the aesthetics of the handwriting, but also causes the problem that the ink attached to the paper surface by the ink bottling is remarkably harder to dry than the ink in the handwriting portion, and contaminates other touched objects. There was a drawback called "botte" peculiar to oil-based ballpoint pens.

Conventionally, in order to suppress ink spots,
(1) Various combinations of resins, surfactants and the like are added,
A method of improving the transferability of ink from a rotating ball to the paper surface by increasing the adhesiveness to the paper surface or improving the wettability on the paper surface. (2) Make the ink spinnable,
Some of them have improved ability to follow ink transferred onto paper.

[0005]

In the above-mentioned conventional oil-based ink for ball-point pens, specific additives (1) include oil-soluble polymers such as ketone resin, rosin and rosin-modified maleic resin, and oleic acid. And surfactants such as polyoxyethylene alkyl ethers and sorbitan fatty acid esters, but these were not satisfactory. As a specific method of (2), there is a method in which a spinnability imparting substance such as polyvinylpyrrolidone having a high molecular weight is added. However, if a large amount is added, writing taste is deteriorated. There was a drawback that it could not be added.

According to JIS (S6039), the partial handwriting width is 3 to 3 times that of a normal handwriting (handwriting without ink spots).
What is about four times the size is used as a sample of the size of the ink bottle. Specifically, from the figure in the material, 0.3m
Part of the m-width handwriting has a maximum width of 0.5 cm over 5.5 cm.
Those having a length of 8 mm are shown. The conventional technology was able to eliminate such large bosses, but 0.3m
Part of the handprint of m width is 0.5m maximum width over 2cm
It was not something to write a small bot that was about m without compromising the taste. An object of the present invention is to obtain an oil-based ink for a ball-point pen having an extremely small number of ink spots.

[0007]

Therefore, in the present invention, it is supposed that an ink having extremely small ink spots and good writing taste can be obtained by controlling the spinning property which is too strong by utilizing the anti-bottom effect of polyvinylpyrrolidone. We continued our research. As a result, it has been found that by changing polyvinylpyrrolidone to a complex of polyvinylpyrrolidone, it is possible to reduce the spinnability and maintain a good writing taste while maintaining the anti-battery effect, and completed the present invention. That is, the gist of the present invention is to provide an oil-based ink for a ball-point pen, comprising polyvinylpyrrolidone and a compound having two or more phenolic hydroxyl groups per benzene nucleus and having a pH of 7.5 or less. I do.

Hereinafter, the present invention will be described in detail. The present invention is characterized in that polyvinylpyrrolidone and a compound having two or more phenolic hydroxyl groups for one benzene nucleus are arranged, but a compound having two or more phenolic hydroxyl groups for one benzene nucleus is It has the property of forming a stable complex with polyvinylpyrrolidone. "Complex"
"A bond other than a covalent bond behaves as if it were a single substance." Examples of compounds having two or more phenolic hydroxyl groups per benzene nucleus that form a complex with polyvinylpyrrolidone include tannic acid, gallic acid, methyl gallate, ethyl gallate,
Propyl gallate, octyl gallate, lauryl gallate, oleyl gallate, stearyl gallate, gallocatechin gallate, gallocarboxylic acid, 3, 5, 7, 3 ',
4'-pentaoxyflavan, pyrogallol, nordihydroguaiaretic acid, protocatechuic acid, ethyl protocatechuate, phloroglucinol, and the like.
Next, the complex of these compounds and polyvinylpyrrolidone may be used after being mixed with an ink solvent in advance, or may be used after adding another composition of the ink. Further, a method of producing the ink of the present invention by adding these compounds little by little with stirring to an ink comprising components other than these compounds to form a composite in the ink. These compounds can be used alone or in combination of several types depending on the mixing property and compatibility with other components of the ink. However, since the complex of polyvinylpyrrolidone and these compounds is unstable as the pH of the ink becomes stronger as the alkali becomes stronger, it is necessary to adjust the pH of the ink from neutral to acidic to a pH of 7.5 or less. In order to adjust the ink from neutral to acidic, oleic acid, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid,
An organic acid such as an acidic phosphoric acid ester can be appropriately selected and used.

Materials other than the polyvinylpyrrolidone complex of the present invention for oil-based inks for ballpoint pens, that is, organic solvents, coloring agents, resins, etc. can be used without any particular limitation. That is, in the present invention, the organic solvent can be used without particular limitation as long as it is conventionally used for oil-based ink for ballpoint pens, for example, ethylene glycol monophenyl ether, benzyl alcohol, propylene glycol, dipropylene glycol,
1,3-butylene glycol, hexylene glycol,
Tetralin, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether acetate, tripropylene glycol monomethyl ether, N-methyl-2-pyrrolidone and the like These can be appropriately selected and used alone or in combination, and the amount used is 30 to
70% by weight is preferred.

As the coloring agent, dyes conventionally used in oil-based inks for ball-point pens are used, but pigments can also be used in combination for improving toning and handwriting characteristics. A specific example of the dye is Balifast Yellow # 3.
104 (CI. 13900A), Balifast Yellow # 3105 (CI. 18690), Orient Spirit Black AB (CI. 50415), Balifast Black # 3804 (CI. 12195),
Bali First Yellow # 1109, Bali First Orange # 2210, Bali First Red # 1320,
Balifast Blue # 1605, Balifast Violet # 1701, Orient Oil Scarlet # 308, Nigrosine-based EX-BP (these are oil dyes manufactured by Orient Chemical Co., Ltd.), Spiron Black GMH Special, Spiron Yellow C-2GH ,
Spiron Red C-GH, Spiron Red C-BH, Spiron Blue BPNH, Spiron Blue C-RH, Spiron Violet C-RH, P. T. Orange 6,
S. P. T. As Blue-111, an oil-based dye manufactured by Hodogaya Chemical Industry Co., Ltd.) and Rhodamine B base (C.I.
I. 45170B) Sumitomo Chemical Co., Ltd. oil-based dye),
Victoria Blue F4R (CI. 42563B)
(Manufactured by BASF, Germany) and the like.

As the pigment, PRINTEX 95, 7
5, 45, P, XE2, (manufactured by Degussa Japan KK), # 2400B, # 1000, # MCF8
8, MA100, MA7, MA11, # 50, # 40,
# 30, CF9, # 20B (Mitsubishi Kasei Kogyo Co., Ltd.), RAVEN7000, 2000, 12
Carbon blacks such as 00, 1000, 500, 410, and 14 (all manufactured by Columbia Carbon Japan Co., Ltd.), titanium oxides such as P25 (manufactured by Nippon Aerosil Co., Ltd.), black iron oxide, and yellow iron oxide Inorganic pigments such as red iron oxide, ultramarine blue, cobalt blue, chrome green, and chromium oxide, Hansa Yellow 10G, 5G, 3G, 4, GR, A, permanent yellow NCG, permanent orange, permanent brown FG, Permanent Red 4R (manufactured by Hoechst AG, Germany, organic pigment), Chromophtal Yellow 2G, Chromophtal Scarlet A2G, Oralis Lis Red PR,
Risol Red RS, Fanal Pink B, G Supra, Chromophtal Blue 4G, Chromophtal Blue A3R, Chromophtal Green GF (
Monochrome First Orange 3G, Monolite First Red B, Monolite First Scarlet R
B, Monolight First Carmin B, Monolight First Red LF, Monolight First
Bordeaux 2R, Rubin Toner 2B, Monolight Red D, Rubin Toner 4B, Firstel Violet R Supra, Firstel Blue B Supra,
Organic pigments such as Monolight First Brown 3GV and Monolight First Black BX (manufactured by ICI Corporation, UK, organic pigment). The above-mentioned coloring agents can be used alone or in combination with others. The amount of the coloring agent used varies depending on the color tone and the like, but is preferably from 10 to 45% by weight based on the total amount of the oil-based ink for ball-point pens. Dyes and pigments can also be used as a mixture.

As the resin to be added to increase the ink viscosity or to improve the fixability of handwriting, any resin used in oil-based inks for ballpoint pens can be appropriately selected and used. For example, ketone resin, xylene resin, polyethylene oxide, rosin resin, terpene resin, coumarone-indene resin, polyvinyl butyral, polyvinyl pyrrolidone, vinyl pyrrolidone-vinyl acetate copolymer, polymethacrylate, polyacrylic acid poly And methacrylic acid copolymers.

In the oil-based ink for a ballpoint pen of the present invention, various additives and surfactants can be used, if necessary, in addition to the above components. Examples include antioxidants, ultraviolet absorbers, rust inhibitors, writability, various surfactants used for improving brushability, such as fatty acid salts, higher alcohol sulfate salts, fatty acid sulfate salts, Anionic surfactants such as alkyl allyl sulfonates, decaglycerin fatty acid ester, hexaglycerin fatty acid ester, polyoxyethylene alkyl ethers, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxy Ethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether
And nonionic surfactants such as ter, polyoxyethylene hydrogenated castor oil and the like.

[0014]

The reason why the ink-based ink for ball-point pens according to the present invention significantly reduces ink spots associated with writing is considered as follows. Since the high molecular weight polyvinylpyrrolidone is well soluble in the ink solvent, the molecular chain is widely extended and dissolved. In addition, since a plurality of polyvinylpyrrolidone molecules are hydrogenated or the like to form a macromolecule, the ink has an action of imparting a large spinning property of several centimeters to several tens of centimeters to the ink. On the other hand, polyvinylpyrrolidone and a compound having two or more phenolic hydroxyl groups for one benzene nucleus form a stable complex by hydrogen bonding or the like in a neutral to acidic ink having a pH of 7.5 or less. Because the active hydrogen bonds of this complex are reduced compared to the polyvinylpyrrolidone molecule before the complex is formed, the properties of multiple complexes to form a larger and larger spinnability to the ink are greatly increased. To decline. Further, a compound having a plurality of benzene nuclei having two or more phenolic hydroxyl groups with respect to one benzene nucleus such as tannic acid may form a plurality of complex bonds with polyvinylpyrrolidone or form a plurality of bonds with polyvinylpyrrolidone. In order to form a complex therebetween, the complex forms one kind of crosslinked structure. For this reason, the spread of the molecular chains in the ink solvent is limited by the crosslinking and becomes smaller. Therefore, the property of entanglement with other polyvinylpyrrolidone and the property of imparting spinnability to the ink by binding an ink solvent or the like around its own molecular chain by hydrogen bonding or the like are further reduced. The spinnability is apparently small, but the molecular weight of the basic skeleton is not small, so the spinnability length is short, but the spinnability is not weak, and the ball surface is not weak. The thread strength at a short distance of a few millimeters from the paper to the paper surface is rather large so that the spring is thicker, and the slight ink that could not be transferred to the paper surface has a short threading distance but a strong yarn. By being pulled back to the paper surface and transferred by the action, it does not easily accumulate on the ball. As a result, it is considered that the amount of ink that could not fit into the gap where the ink was ejected at the tip end opening of the ball-point pen tip was extremely reduced, and that the oil-based ink for ball-point pens with extremely small ink spots was obtained. Furthermore, since the spinning distance of the composite is short, the ink has low adhesiveness that does not affect the spinning property even to the ink behind the ball, and does not hinder the rotation of the ball, so that an ink having good writing quality can be obtained. It is thought that it was done.

Hereinafter, the present invention will be described in detail with reference to Examples, but the term "parts" indicates parts by weight.

Preparation of Complex Liquid 1 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.97 parts Benzyl alcohol 27.98 parts Polyvinylpyrrolidone K-90 (BASF, Germany) 0.5 part Solution comprising the above components While stirring at 60 ° C., 0.15 parts of ethyl gallate was added, followed by stirring for 1 hour to obtain a solution of polyvinylpyrrolidone K-90 in ethyl gallate complex.

Preparation of Complex Solution 2 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.9 parts Benzyl alcohol 28.0 parts Polyvinylpyrrolidone K-90 (BASF, Germany) 0.6 part While stirring the solution at 60 ° C., 0.2 parts of gallic acid was added, and the mixture was stirred for 1 hour, and polyvinylpyrrolidone K was stirred.
A solution of -90 gallic acid complex was obtained.

Preparation of complex solution 3 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.8 parts Benzyl alcohol 27.9 parts Polyvinylpyrrolidone K-90 (manufactured by BASF, Germany) 0.7 parts While stirring the solution at 60 ° C., 0.1 part of tannic acid was added and stirred for 1 hour to obtain a solution of polyvinylpyrrolidone K-90 in a tannic acid complex.

Preparation of complex solution 4 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.5 parts Benzyl alcohol 27.5 parts Polyvinylpyrrolidone K-90 (manufactured by BASF, Germany) 0.7 parts While stirring the solution at 60 ° C., 0.1 part of nordihydroguaiaretic acid was added and stirred for 1 hour to obtain a solution of polyvinylpyrrolidone K-90 in a nordihydroguaiaretic acid complex.

Preparation of Complex Solution 5 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.0 parts Benzyl alcohol 27.0 parts Polyvinylpyrrolidone K-90 (BASF, Germany) 0.6 part While stirring the solution at 60 ° C., 0.15 parts of methyl gallate was added, and the mixture was stirred for 1 hour to obtain a solution of polyvinylpyrrolidone K-90 in methyl gallate complex.

Preparation of Complex Solution 6 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 28.3 parts Benzyl alcohol 28.4 parts Hexylene glycol 5.0 parts Polyvinylpyrrolidone K-90 (manufactured by BASF, Germany) 0 6.6 parts While stirring the solution comprising the above components at 60 ° C., 0.15 part of propyl gallate was added, and the mixture was stirred for 1 hour to obtain a solution of polyvinylpyrrolidone K-90 in propyl gallate complex.

Preparation of Complex Solution 7 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 26.3 parts Benzyl alcohol 26.4 parts Butanediol 3.0 parts Polyvinylpyrrolidone K-90 (manufactured by BASF, Germany) 6 parts While stirring the solution comprising the above components at 60 ° C., 0.1 part of lauryl gallate and 0.1 part of gallic acid are added, and the mixture is stirred for 1 hour, and a complex of polyvinylpyrrolidone K-90 and lauryl gallate and gallic acid is added. Was obtained.

Preparation of complex solution 8 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.8 parts Benzyl alcohol 27.9 parts N-methyl 2-pyrrolidone 2.0 parts Oleic acid 5.0 parts Polyvinyl pyrrolidone K-90 (BASF, Germany) 0.6 part A solution of the stearyl gallate complex of polyvinylpyrrolidone K-90 was added to 0.2 parts of stearyl gallate while stirring the solution comprising the above components at 60 ° C., and stirred for 1 hour. I got

Example 1 Complex solution 1 56.6 parts Ketone resin 10.0 parts Oleic acid 2.0 parts Sorbitan sesquioleate 2.0 parts Varifast Black 3820 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20 0.0 part Varifast Violet 1701 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 parts To the complex solution 1, another formulation was added at 60 ° C. with stirring. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a black ink of PH 4.1.

Example 2 Complex solution 2 56.7 parts Ketone resin 10.0 parts Sorbitan sesquioleate 2.0 parts Varifast Black 3820 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20.0 parts Varifast Violet 1701 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 parts The other solution was added to the complex solution 2 while stirring at 60 ° C. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a black ink having a pH of 6.7.

Example 3 Complex solution 3 56.5 parts Ketone resin 10.0 parts Plysurf A212C (surfactant manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.0 part Sorbitan sesquioleate 2.0 parts Balifast Black 3820 (dye, manufactured by Orient Chemical Industry Co., Ltd.) 20.0 parts Varifast Violet 1701 (dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 parts Other compound is stirred into complex solution 3 at 60 ° C. While adding. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to have a pH of 3.7.
Of black ink was obtained.

Example 4 Complex Solution 4 55.8 parts Ketone resin 10.0 parts Oleic acid 2.0 parts Sorbitan sesquioleate 2.0 parts Varifast Black 3820 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20 0.0 part Varifast Violet 1701 (dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 parts The other solution was added to the complex solution 4 at 60 ° C. with stirring. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a black ink of PH 4.1.

Example 5 Complex solution 5 54.75 parts Ketone resin 10.0 parts Oleic acid 2.0 parts Sorbitan sesquioleate 2.0 parts Varifast Black 3820 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20 0.0 parts Varifast Violet 1701 (dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 parts To the complex solution 5, another formulation was added while stirring at 60 ° C. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a black ink of PH 4.1.

Example 6 Complex solution 6 62.45 parts Ketone resin 14.0 parts Oleic acid 2.0 parts Sorbitan sesquioleate 2.0 parts Varifast Blue 1607 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20 0.0 part The other formulation was added to complex solution 6 at 60 ° C. with stirring. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a blue ink of PH 4.7.

Example 7 Complex solution 7 56.5 parts Ketone resin 13.0 parts Oxyethylene dodecylamine 1.0 part Sorbitan sesquioleate 2.0 parts Spiron Red C-GH (Dye, manufactured by Hodogaya Chemical Industry Co., Ltd.) 12.0 parts Spiron orange (dye, Hodogaya Chemical Industry Co., Ltd.) 15.0 parts Other components were added to the complex solution 7 while stirring at 60 ° C. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a red ink having a pH of 7.5.

Example 8 Complex solution 8 63.5 parts Ketone resin 15.0 parts Oleic acid 2.0 parts Sorbitan sesquioleate 2.0 parts Carbon black 18.0 parts Other components are added to complex solution 8 It was added at 60 ° C. with stirring. After the addition, the mixture was further stirred at 80 ° C. for 5 hours to obtain a black ink of PH 4.1.

Example 9 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 42.0 parts Benzyl alcohol 28.0 parts Polyvinylpyrrolidone K-30 (manufactured by BASF, Germany) 12.0 parts Tetralin 2.0 parts Sorbitan sesqui Oleate 2.0 parts Varifast Blue # 1607 12.0 parts Varifast Blue # 1621 12.0 parts Oleic acid 2.0 parts Tannic acid 2.4 parts Of the above formulation, first, phenyl cellosolve, benzyl alcohol, Tetralin and Balifast Blue # 160 were added to a solution in which polyvinylpyrrolidone K-30 was mixed.
7. Add Balifast Blue # 1621, oleic acid and stir for 5 hours, then add tannic acid and add another 80
The mixture was stirred at 5 ° C. for 5 hours to obtain a blue ink having a pH of 6.5.

Example 10 Phenyl cellosolve (solvent, ethylene glycol monophenyl ether) 27.8 parts Benzyl alcohol 27.9 parts Polyvinylpyrrolidone K-90 (manufactured by BASF, Germany) 0.7 parts Ketone resin 10.0 parts Olein Acid 2.0 parts Sorbitan sesquioleate 2.0 parts Varifast Black 3820 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 20.0 parts Varifast Violet 1701 (Dye, manufactured by Orient Chemical Industry Co., Ltd.) 10.0 Part gallocatechin gallate 0.1 part Of the above blends, first, a solution obtained by mixing phenyl cellosolve, benzyl alcohol, and polyvinylpyrrolidone K-90 was added to a ketone resin, oleic acid, sorbitan sesquioleate, Bali First Black-3820, Bali Fast Stirred for 5 hours at 80 ° C. was added a Ioretto 1701, then, after a further addition of gallocatechin gallate 8
The mixture was stirred at 0 ° C for 1 hour to obtain a black ink having a pH of 4.0.

Comparative Example 1 A black ink was obtained in the same manner as in Example 1 except that 0.15 part of ethyl gallate was omitted.

Comparative Example 2 A black ink was obtained in the same manner as in Example 2, except that 0.2 parts of gallic acid was omitted.

Comparative Example 3 A blue ink was obtained in the same manner as in Example 9 except that 2.4 parts of tannic acid were omitted.

[0037]

The oil-based inks for ballpoint pens of Examples 1 to 10 and Comparative Examples 1 to 3 were filled into a commercially available metal tip oil-based ballpoint pen body BK100 (manufactured by Pentel Co., Ltd.) in an amount of 0.25 g each. The test was performed. The results are shown in Tables 1 and 2.

Ink bottling number measurement test; writing weight 200
g, at a writing angle of 70 degrees, and at a writing speed of 7 cm / sec, after drawing a spiral on a high-quality paper at a length of 1000 m, the handwriting is written in Scale Lu.
Observation was performed by pe (manufactured by Tokai Sangyo Co., Ltd.), and the number of ink spots on the spiral handwriting was counted.

The ink fountain is about 1.5 times the area of a normal handwriting, 0.25 pieces, and about 3 times more than that, 0.50 pieces, and is equivalent to the ink stipulated in JIS S 6039. Was measured as 1.00, and the total was defined as the number of ink spots. The number of tests is n = 4 and the average value is described.

Writing taste (writing resistance value) test: A vertical surface of 100 g, a writing angle of 70 degrees, a rotation speed of 3 times / minute, a writing speed of 4 cm / sec, and a paper surface and a writing implement of 11 were written on a high-quality paper.
When writing a straight line in the direction of the line showing the angle of 0 degrees, the writing resistance value applied in the opposite direction to this writing direction is detected by a pressure sensor applied to the pen tip and measured to obtain the writing resistance value. . The number of tests n = 10 and the average value is described.

[0041]

[Table 1]

[0042] [Table 2]

As described above, the oil-based ink for a ball-point pen of the present invention has a good writing quality with extremely few ink spots.

Claims (1)

[Claims] 1. An oil-based ink for a ballpoint pen, comprising polyvinylpyrrolidone and a compound having two or more phenolic hydroxyl groups per benzene nucleus, and adjusted to a pH of 7.5 or less.