Ink composition for oil-based ballpoint pen and oil-based ballpoint pen

Abstract

To provide an ink composition for an oily ball point pen which can improve stability of an ink discharge amount of an oily ball point pen when reduced in viscosity, and can suppress emulsification even when containing water.SOLUTION: An ink composition for an oily ball point pen contains an organic solvent containing a water-soluble organic solvent, a resin, a coloring agent and water, wherein a percentage content of the water in the ink composition for the oily ball point pen is 3 to 10 mass%, the resin contains at least one of a ketone resin and a maleic resin, and viscosity at 25°C and a shear rate of 7.5 / sec is less than 700 mPa s.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an ink composition for an oil-based ballpoint pen and an oil-based ballpoint pen. [Background technology]

[0002] Ink compositions used in oil-based ballpoint pens generally have a high viscosity of 7,000 to 15,000 mPa·s at 25° C. For this reason, oil-based ballpoint pens using such ink compositions tend to write with a heavy feel, requiring a high writing pressure to transfer the ink to paper.

[0003] For this reason, in recent years, ink compositions with reduced viscosity have been proposed in order to achieve a light writing feel when using an oil-based ballpoint pen.

[0004] For example, Patent Document 1 below discloses an oil-based ballpoint pen ink composition containing an organic solvent, a colorant, a resin, and water, with the water content being 0.3% by weight or more and less than 3.0% by weight, and with a viscosity of 1000 to 7000 mPa·s at a shear rate of 5 / sec and at 25°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4270628 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the oil-based ballpoint pen ink composition described in the above-mentioned Patent Document 1 has the following problems.

[0007] That is, the oil-based ballpoint pen ink composition described in Patent Document 1 still has a high viscosity, and therefore, in order to pursue an even lighter writing feel, it was necessary to further reduce the viscosity.

[0008] However, further lowering the viscosity of the oil-based ballpoint pen ink composition may result in a decrease or increase in the amount of ink discharged when the oil-based ballpoint pen is used for an extended period of time, resulting in a decrease or increase in the amount of ink discharged from the oil-based ballpoint pen, and in some cases, it may not be possible to sufficiently improve the line drawing performance. Furthermore, depending on the type of resin contained in the oil-based ballpoint pen ink composition, the ink composition may become in an emulsion state when water is added.

[0009] Therefore, there has been a demand for an ink composition for an oil-based ballpoint pen that can improve the stability of the ink ejection amount from an oil-based ballpoint pen even when the viscosity is reduced, and that can suppress emulsification even when it contains water.

[0010] The present invention has been made in view of the above circumstances, and aims to provide an ink composition for an oil-based ballpoint pen, and an oil-based ballpoint pen, which can improve the stability of the ink ejection amount of an oil-based ballpoint pen even when the viscosity is reduced, and which can suppress emulsification even when water is contained. [Means for solving the problem]

[0011] As a result of extensive research to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using an organic solvent containing a water-soluble organic solvent as the organic solvent, setting the water content within a specific range, and using a specific resin as the resin.

[0012] That is, the present invention provides an ink composition for an oil-based ballpoint pen, which comprises an organic solvent including a water-soluble organic solvent, a resin, a colorant, and water, wherein the content of the water in the ink composition for an oil-based ballpoint pen is 3 to 10 mass %, the resin includes at least one of a ketone resin and a maleic resin, and the viscosity of the ink composition at 25°C and a shear rate of 7.5 / sec is less than 700 mPa·s.

[0013] The ink composition for oil-based ballpoint pens of the present invention can improve the stability of ink ejection amount even when the viscosity is reduced, and can suppress emulsification even when it contains water.

[0014] The present inventors speculate as follows about the reason why the ink composition for oil-based ballpoint pens of the present invention provides the above-mentioned effects.

[0015] In other words, in the present invention, by adding 3 to 10% by mass of water, even if the viscosity of the ink composition at 25°C and a shear rate of 7.5 / sec is reduced to less than 700 mPa·s, water molecules are adsorbed to the ball seat or the ball inside the tip, reducing contact between the ball seat and the ball, making it possible to reduce or suppress an increase in the amount of ink composition discharged from an oil-based ballpoint pen when the oil-based ballpoint pen is used for an extended period of time, and improving the stability of the ink discharge rate from the oil-based ballpoint pen.Furthermore, by using a resin containing at least one of a ketone resin and a maleic resin, the solid content of the resin is more easily soluble in organic solvents and water, and it is thought that emulsification of the ink composition is suppressed. From the above, the present inventors speculate that the above effects can be obtained by the ink composition for oil-based ballpoint pens of the present invention.

[0016] In the ink composition for an oil-based ballpoint pen, it is preferable that the colorant contains a dye, and the content of the water-soluble organic solvent in the organic solvent is 15% by mass or more and 80% by mass or less.

[0017] In this case, the water content can be increased compared to when the content of the water-soluble organic solvent in the organic solvent is less than 15% by mass, and the stability of the ink ejection amount can be further improved. Also, compared to when the content of the water-soluble organic solvent in the organic solvent is more than 80% by mass, the solubility of the dye contained in the colorant in the organic solvent is increased, and a state in which the dye is less likely to precipitate, settle, or become non-uniform in the composition can be maintained, allowing for continued ease of writing and making it less likely to produce undissolved solids.

[0018] The present invention also provides an oil-based ballpoint pen containing the ink composition for an oil-based ballpoint pen described above.

[0019] This oil-based ballpoint pen contains the ink composition for an oil-based ballpoint pen described above, which can improve the stability of the ink ejection volume of the oil-based ballpoint pen even when the viscosity of the ink composition for an oil-based ballpoint pen is reduced. Therefore, the oil-based ballpoint pen of the present invention can improve the stability of the ink ejection volume while realizing a light writing feel during use. Furthermore, the ink composition contained in the oil-based ballpoint pen can suppress emulsification, thereby suppressing color unevenness in the written lines. [Effects of the Invention]

[0020] According to the present invention, an ink composition for an oil-based ballpoint pen and an oil-based ballpoint pen are provided which can improve the stability of the ink ejection amount of an oil-based ballpoint pen even when the viscosity is reduced, and which can suppress emulsification even when the ink contains water. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail.

[0022] <Oil-based ballpoint pen ink composition> The ink composition for oil-based ballpoint pens of the present invention (hereinafter sometimes simply referred to as the "ink composition") contains an organic solvent including a water-soluble organic solvent, a resin, a colorant, and water. The water content in the ink composition is 3 to 10% by mass, and the resin contains at least one of a ketone resin and a maleic resin. The ink composition has a viscosity of less than 700 mPa·s at 25°C and a shear rate of 7.5 / sec.

[0023] The ink composition of the present invention can improve the stability of the ink ejection amount from an oil-based ballpoint pen and improve line drawing performance even when the ink composition has a low viscosity. Furthermore, the ink composition of the present invention can suppress emulsification even when it contains water.

[0024] The ink composition will be described in detail below.

[0025] (A) Organic solvent (organic solvent) The organic solvent includes a water-soluble organic solvent, which is an organic solvent in which the solubility of water at 25°C is 10 g / 100 g or more and which is used to increase the water content in the ink composition.

[0026] Examples of such water-soluble organic solvents include alcohols such as 3-methoxy-3-methyl-1-butanol, ethoxytriglycol, ethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, ethanol, methanol, t-butyl alcohol, isopropyl alcohol, 1-propanol, and 2-propanol; and ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, dipropylene glycol methyl ether, dipropylene glycol monoethyl ether, diethylene glycol monobutyl ether, and tripropylene glycol methyl ether, with 3-methoxy-3-methyl-1-butanol being preferred. When the water-soluble organic solvent is 3-methoxy-3-methyl-1-butanol, the ink composition can further improve the stability of the ink ejection volume from an oil-based ballpoint pen.

[0027] (non-water-soluble organic solvent) A water-insoluble organic solvent refers to an organic solvent whose solubility in water at 25°C is less than 10 g / 100 g.

[0028] Examples of such water-insoluble organic solvents include aromatic alcohols such as benzyl alcohol and phenyl glycol; aliphatic alcohols having 8 or more carbon atoms such as octanol; aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; aliphatic hydrocarbon solvents such as n-hexane, n-heptane, isoheptane, n-octane, and isooctane; and cycloparaffin solvents such as methylcyclohexane and ethylcyclohexane. These can be used alone or in combination of two or more. Among these, aromatic alcohols are preferred from the viewpoint of improving the solubility of the dye. Of the aromatic alcohols, benzyl alcohol is preferred. In this case, the ink composition can further improve the stability of the ink ejection volume from an oil-based ballpoint pen.

[0029] The content of the water-soluble organic solvent in the organic solvent is not particularly limited and is usually less than 25% by mass. The content of the water-soluble organic solvent in the organic solvent is preferably 15% by mass or more and 80% by mass or less. In this case, the water content can be increased compared to when the content of the water-soluble organic solvent in the organic solvent is less than 15% by mass, thereby further improving the stability of the ink ejection volume. Furthermore, compared to when the content of the water-soluble organic solvent in the organic solvent is more than 80% by mass, the solubility of the dye in the organic solvent is increased, making it possible to maintain a state in which the dye is less likely to precipitate, settle, or become non-uniform in the composition, thereby maintaining a state in which writing is easy and reducing the generation of undissolved solids. Furthermore, pigment dispersibility can be improved.

[0030] (B) Resin The resin contains at least one of a ketone resin and a maleic resin. When the resin contains at least one of a ketone resin and a maleic resin, emulsification can be suppressed even when the ink composition contains water.

[0031] The maleic resin is a resin containing structural units derived from maleic acid or maleic anhydride, and may be a homopolymer or a copolymer.

[0032] The ketone resin is a resin having a ketone group.

[0033] The content (unit: mass %) of the ketone resin or maleic resin in the resin is not particularly limited, but is preferably 70 mass % or more.

[0034] In this case, the robustness of the written lines and the adhesion to the writing surface are improved compared to when the content of ketone resin and maleic resin in the resin is less than 70% by mass.

[0035] The resin content in the ink composition is not particularly limited, but is typically 20% by mass or less. The resin content in the ink composition is preferably 3% by mass or more. In this case, the viscosity of the ink composition increases more than when the resin content in the ink composition is less than 3% by mass, thereby preventing the ink composition from dripping when used with an oil-based ballpoint pen. Furthermore, the resin content in the ink composition is preferably 15% by mass or less. In this case, the viscosity of the ink composition is prevented from increasing too much compared to when the resin content in the ink composition exceeds 15% by mass, thereby enabling a lighter writing feel when used with an oil-based ballpoint pen.

[0036] (C) Colorant The colorant includes at least one of a pigment and a dye. (pigment) The pigment is not particularly limited, and examples of the pigment include organic pigments and inorganic pigments, which can be used alone or in combination of two or more.

[0037] Examples of organic pigments include insoluble azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, and diketopyrrolopyrrole pigments.

[0038] Examples of inorganic pigments include carbon black, titanium oxide, and metal powder.

[0039] The content of the pigment in the colorant is not particularly limited and may be determined appropriately depending on the desired color state. However, in the present invention, particularly excellent pigment dispersibility is exhibited when the content of the pigment in the colorant is 1 to 15 mass %.

[0040] (dye)

[0041] Examples of dyes include SPIRIT BLACK 61F, VALIFAST VIOLET 1701, VALIFAST VIOLET 1704, VALIFAST YELLOW 1109, VALIFAST YELLOW 1151, VALIFAST YELLOW 1171, OIL YELLOW 107, VALIFAST BLUE 1605, VALIFAST BLUE 1621, VALIFAST BLUE 1623, VALIFAST BLUE 2620, OIL BLUE 613, VALIFAST RED 1308, VALIFAST RED 1320, VALIFAST RED 1364, VALIFAST RED 2320, VALIFAST BLACK 3830, and VALIFAST BLACK 3870 (all manufactured by Orient Chemical Industries Co., Ltd.), Aizen Spilon BLACK GHM Special, and Aizen Spilon VIOLET C-RH, Aizen Spilon YELLOW C-GH new, Aizen Spilon BLUE C-RH, Aizen Spilon SPTBLUE-111, Aizen Spilon SPTBLUE-121 (all manufactured by Hodogaya Chemical Co., Ltd.), etc. These may be used alone or in combination of two or more.

[0042] The content of the dye in the colorant is not particularly limited and may be determined appropriately depending on the desired color state.

[0043] (D)Water The water may be either tap water or ion-exchanged water, but ion-exchanged water is preferred because it contains fewer impurities.

[0044] The water content in the ink composition is 3 to 10% by mass. In this case, the stability of the ink ejection amount can be further improved compared to when the water content is less than 3% by mass. Furthermore, compared to when the water content exceeds 10% by mass, the ink composition can solubilize water in a liquid mixture of solvent, dye, resin, etc., thereby maintaining a state in which dye precipitation, sedimentation, non-uniformity, etc. are less likely to occur in the composition, allowing for continued ease of writing and reducing the generation of undissolved solids.

[0045] The water content in the ink composition is preferably 4% by mass or more, which can further improve the stability of the ejection amount of the ink composition compared to when the water content in the ink composition is less than 4% by mass.

[0046] The water content in the ink composition is more preferably 5% by mass or more.

[0047] Furthermore, the water content of the ink composition is preferably 9% by mass or less, which allows water to be solubilized in a liquid mixture of solvent, dye, resin, etc., and thus improves stability over time compared to when the water content of the ink composition exceeds 9% by mass.

[0048] The water content in the ink composition is more preferably 8% by mass or less.

[0049] The water content in the ink composition can be measured, for example, by a Karl Fischer moisture meter.

[0050] (E) Other ingredients In addition to the above (A) to (D), the ink composition may contain known additives such as dispersants, spinnability imparting agents, lubricants, anti-stiffening agents, and anti-rust agents, as needed, within the range that does not impair the properties of the ink composition.

[0051] (F) Viscosity of the ink composition The viscosity of the ink composition at 25°C and a shear rate of 7.5 / sec is less than 700 mPa·s.

[0052] In this case, the viscosity of the ink composition can be reduced, and a light writing feel can be achieved when using an oil-based ballpoint pen. Furthermore, even if the viscosity of the ink composition is reduced to less than 700 mPa s at 25°C and a shear rate of 7.5 / sec, the ink composition of the present invention can further improve the stability of the ink ejection volume from an oil-based ballpoint pen.

[0053] The viscosity of the ink composition is more preferably less than 650 mPa·s, which allows for a further reduction in the viscosity of the ink composition and allows for a lighter writing feel when using an oil-based ballpoint pen.

[0054] However, the viscosity of the ink composition is preferably 100 mPa·s or greater, which can better prevent ink from dripping when using an oil-based ballpoint pen and improve the writing feel, compared to ink compositions with a viscosity of less than 100 mPa·s.

[0055] <Oil-based ballpoint pen> Next, the oil-based ballpoint pen of the present invention will be described. The oil-based ballpoint pen of the present invention contains the ink composition described above.

[0056] This oil-based ballpoint pen contains the ink composition for an oil-based ballpoint pen described above, and even if the ink composition for an oil-based ballpoint pen described above has a low viscosity, it can improve the stability of the ink ejection amount of the oil-based ballpoint pen. Therefore, the oil-based ballpoint pen of the present invention can improve the stability of the ink ejection amount while realizing a light writing feel. Furthermore, even if the ink composition contained in the oil-based ballpoint pen contains water, it can suppress emulsification, thereby suppressing color unevenness in the written line. [Example]

[0057] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0058] The organic solvents, resins, colorants, dispersants, water, lubricants, spinnability imparting agents and anti-stiffening agents used in the examples and comparative examples are specifically as follows.

[0059] <Organic solvents> (non-water-soluble organic solvent) benzyl alcohol Phenoxyethanol (Water-soluble organic solvent) 3-Methoxy-3-methyl-1-butanol Propylene glycol monomethyl ether Ethoxytriglycol

[0060] <Resin> Ketone resin (product name "TEGO (registered trademark) VariPlus SK", manufactured by Evonik Industries Co., Ltd.) Maleic acid resin (product name "Marquid No. 33", manufactured by Arakawa Chemical Industries, Ltd.) Terpene phenol resin (product name "YS Polystar K125", manufactured by Yasuhara Chemical Co., Ltd.)

[0061] <Coloring agent> (dye) VALIFAST VIOLET 10 (product name, manufactured by Orient Chemical Industries Co., Ltd.) VALIFAST BLACK 3830 (product name, manufactured by Orient Chemical Industries Co., Ltd.) VALIFAST RED3311 (product name, manufactured by Orient Chemical Industries Co., Ltd.) VALIFAST RED1308 (product name, manufactured by Orient Chemical Industries Co., Ltd.) OIL YELLOW107 (product name, manufactured by Orient Chemical Industries Co., Ltd.) (pigment) Carbon Black (Pigment Black 7) Organic pigment (Pigment Red 254)

[0062] <Dispersant> (fatty acid) oleic acid (Aliphatic amines) Oleylamine

[0063] <Water> Ion-exchanged water

[0064] <Lubricant> Phosphate ester (product name "Plysurf A207H", manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0065] <Spinnability imparting agent> Polyvinylpyrrolidone (trade name "PVP K-90", manufactured by Nippon Shokubai Co., Ltd.) Butyral Resin

[0066] <Anti-stiffening agent> Modified castor oil fatty acid ester (product name "Riccizer GR301", manufactured by Ito Oil Mills Co., Ltd.)

[0067] (Examples 1 to 11 and Comparative Examples 1 to 8) An ink composition was obtained by mixing an organic solvent, a resin, a colorant, a dispersant, water, a lubricant, and a stringiness-imparting agent in the content ratios shown in Tables 1 and 2 while heating at 50 Hz for 5 hours at 60°C using a reciprocating rotary mixer, Ajiter (manufactured by Shimazaki Engineering Co., Ltd.).

[0068] The viscosity of the resulting ink composition was measured using a digital viscometer (product name "DV-2+PRO", manufactured by Brookfield) at 25°C and a shear rate of 7.5 / sec. The results are shown in Tables 1 and 2.

[0069] <Evaluation of Ink Composition> The ink compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 8 were evaluated for the state of the ink composition and the stability of the ink ejection amount as follows.

[0070] (1) State of ink composition The ink compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 8 were observed at a magnification of 200 times using a transmission electron microscope. The state of the ink composition was then evaluated based on the following criteria. The results are shown in Tables 1 and 2. (standard) ○ No pigment aggregation is observed (if pigment is included) and the ink composition is not in an emulsion state × Pigment aggregation is observed (if pigment is included) or the ink composition is in an emulsion state In addition, "X" in Comparative Examples 4 and 7 means that no pigment aggregation was observed but emulsification could not be suppressed, and "X" in Comparative Example 8 means that emulsification was suppressed but pigment aggregation was observed.

[0071] (3) Stability of ink ejection volume The ink compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 8 were evaluated for stability of ink ejection amount as follows.

[0072] That is, first, a stainless steel ball (tip) with a ball diameter of 0.5 mm and a ballpoint pen refill were prepared. Then, the ink compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 8 were filled into ballpoint pen refills, and five refills were prepared for each Example or Comparative Example.

[0073] Next, in a constant temperature and humidity room at a temperature of 25°C and humidity of 60%, a continuous spiral writing test was carried out over 500 m with a load of 200 g, a writing angle of 70°, and a writing speed of 4.0 m / min. The writing test was carried out while gradually rotating the ballpoint pen refill around its axis along its longitudinal direction, under the condition that the ballpoint pen refill made one rotation every 5 m.

[0074] The ink discharge amount (X) during writing from 0 to 100 m was calculated from the mass of the ballpoint pen refill measured with a precision balance after 100 m of writing and the mass of the ballpoint pen refill measured with a precision balance before writing. Similarly, the ink discharge amount (Y) during writing from 400 to 500 m was calculated from the mass of the ballpoint pen refill measured with a precision balance after 500 m of writing and the mass of the oil-based ballpoint pen measured with a precision balance after 400 m of writing, and Z (= YX) was calculated from the calculated values ​​of X and Y. The average value of "Z" for the five ballpoint pen refills was then taken as "Z'".

[0075] The stability of ink ejection volume of ballpoint pen refills using the ink compositions was evaluated based on the following criteria. The results are shown in Tables 1 and 2. (standard) ○ The absolute value of Z' is less than 5 mg × The absolute value of Z' is 5 mg or more

[0076] [Table 1]

[0077] [Table 2]

[0078] From the results shown in Tables 1 and 2, the ink compositions of Examples 1 to 11 were all rated "good" for the state of the ink composition and the stability of the ink ejection amount. On the other hand, the ink compositions of Comparative Examples 1 to 8 were rated "poor" for at least one of the state of the ink composition (suppression of emulsification) and the stability of the ink ejection amount. Furthermore, all of the ink compositions of Examples 1 to 11 had sufficiently low viscosity.

[0079] From the above, it has been confirmed that the ink composition for an oil-based ballpoint pen of the present invention can improve the stability of the ink ejection amount from an oil-based ballpoint pen even when the viscosity is reduced, and can suppress emulsification even when it contains water.

Claims

1. an organic solvent including a water-soluble organic solvent; Resin and A colorant; Water and An ink composition for an oil-based ballpoint pen, comprising: the content of the water in the ink composition for oil-based ballpoint pens is 3 to 10% by mass, the resin includes at least one of a ketone resin and a maleic resin, the organic solvent further comprises a water-insoluble organic solvent, the non-water-soluble organic solvent is an aromatic alcohol, the content of the water-insoluble organic solvent in the organic solvent is 50.00% by mass or more and 79.45% by mass or less, An oil-based ballpoint pen ink composition having a viscosity of less than 700 mPa·s at 25°C and a shear rate of 7.5 / sec.

2. 2. The ink composition for an oil-based ballpoint pen according to claim 1, wherein the colorant comprises a dye, and the content of the water-soluble organic solvent in the organic solvent is 20.55% by mass or more and 50% by mass or less.

3. An oil-based ballpoint pen comprising the ink composition for an oil-based ballpoint pen according to claim 1 or 2.

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