JP2011252047A - O/w type emulsion ink composition for ballpoint pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an O/W type emulsion ink composition for ballpoint pens, which avoids a show-through effect of writing and is excellent in water resistance and in writing sensation.SOLUTION: The O/W type emulsion ink composition for ballpoint pens comprises at least an oil-soluble ink component (A) comprising at least an oil-soluble dye as a colorant and an organic solvent which dissolves the dye and has solubility in 100 g water at 20°C of ≤5 g, an emulsifier component (B) comprising at least a nonionic surfactant having an HLB of ≤8, a sodium salt of a ≥8C acyl lactic acid, and a 14-24C higher alcohol, and water having conductivity at 25°C of 0.05-100 μS/cm, wherein the oil-soluble ink component (A) is emulsified and dispersed in the water.

Description

  The present invention relates to an O / W emulsion ink composition for ballpoint pens that has excellent water resistance of handwriting, no show-through, excellent writing drying, and good temperature stability.

  Conventionally, water-based ballpoint pen inks and water-based gel ballpoint pen inks that use water-soluble dyes have the characteristics that the handwriting is vivid and the writing feeling is good, but have the drawback that the water resistance of the handwriting is inferior. Aqueous pigment gel ballpoint pen inks in which a colorant is used as a pigment to improve water resistance have a high ink viscosity and poor writing quality in order to improve writing density and prevent sedimentation. Oil-based ballpoint pen ink in which an oil-soluble dye is dissolved in an organic solvent has good water resistance because the dye has water resistance, but if the viscosity is lowered to improve the writing quality, a show-through in which the organic solvent penetrates into paper occurs. For this reason, the viscosity is increased to prevent show-through, but the writing quality becomes heavy.

  Therefore, with an O / W emulsion ballpoint pen ink in which an oil phase component composed of an oil-soluble dye as a colorant and an organic solvent is emulsified and dispersed in water using an emulsifier, the writing quality of the aqueous phase and the water resistance of the oil-soluble dye are improved. It is thought that both can be achieved.

  However, when a nonionic surfactant having a relatively high HLB of about 8-18, which is usually used for preparing an O / W emulsion, is mixed into an emulsion ink, the surfactant is added to the handwriting on the paper together with the colorant. Therefore, when the handwriting gets wet with water, re-emulsification occurs, and there is a problem that the handwriting flows into the water even though the oil-soluble dye is used. In order to solve this problem, the present inventor has a combination of a polyglycerol fatty acid ester having an HLB of 8 or less and a specific sodium acyl lactate (Patent Document 1), a sucrose fatty acid ester having an HLB of 8 or less and a specific acyl lactic acid. It has been found that an O / W emulsion ink can be prepared in combination with sodium (Patent Document 2) and has excellent water resistance. It has also been found that an O / W emulsion ink having good water resistance can be obtained by combining sodium acyl lactate, which has almost no emulsifying ability alone, with a specific alkyl glyceryl ether. (Patent Document 3)

JP 2009-173920 A Japanese Patent No. 4433094 JP 2010-53232 A

  These O / W emulsion inks have sufficient water resistance. However, when placed in a certain high temperature environment, the emulsion may be broken and aggregated or separated into an oil phase and an aqueous phase.

  In particular, if the alkyl group in the fatty acid part of polyglycerin fatty acid ester or sucrose fatty acid ester is unsaturated or has a branched structure, the melting point is low, and if it is pasty or liquid at room temperature, high-temperature stability may be insufficient. It was.

The present invention provides a stable emulsion ink that has sufficient water resistance regardless of the structure of the nonionic surfactant having an HLB of 8 or less, has heat resistance, has good temperature stability, and is not easily destroyed. The object of the present invention is to obtain an O / W type emulsion ink having no show-through and fast handwriting dryness.

  The present invention relates to an oil-based ink component (A) containing at least an oil-soluble dye as a colorant and an organic solvent having a solubility in 100 g of water of 5 g or less at 20 ° C., and a nonionic resin having an HLB of 8 or less. An emulsifier component (B) containing at least a surfactant, an acyl lactate having 8 or more carbon atoms, and a higher alcohol having 14 to 24 carbon atoms, and water having a conductivity at 25 ° C. of 0.05 to 100 μS / cm. The gist is an O / W emulsion ink composition for ballpoint pens which is contained at least and the oil-based ink component (A) is emulsified and dispersed in water.

  Usually, a nonionic surfactant having an HLB of 8 or less, which is used for making a W / O type emulsion, is combined with an acyl lactate having 8 or more carbon atoms and a higher alcohol having 14 to 24 carbon atoms. O / W emulsion with excellent water resistance and heat resistance regardless of the structure of the nonionic surfactant by forming an O / W emulsion in water having a conductivity of 0.05 to 100 μS / cm Is obtained.

  The nonionic surfactant used in the present invention is an ethylene glycol fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene glycerin fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, polyoxy having an HLB of 8 or less. Ethylene sorbitan fatty acid ester, polyoxyethylene sorbite fatty acid ester, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil fatty acid ester, polyethylene glycol fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl Ether, sucrose fatty acid ester, polyoxyethylenetrimethylolpropane fatty acid ester, etc. .01 was 10.00% by weight% by weight, more preferably from 5% to 0.1 wt%. The required HLB optimum for emulsification varies depending on the type and amount of oil-soluble dye and the type and amount of organic solvent, so it can be selected as appropriate so that the optimum HLB can be obtained. A mixture of activators can also be used.

  The acyl lactic acid sodium salt used in the present invention desirably has 8 or more carbon atoms, and those having less than 8 carbon atoms have poor performance as an emulsifier, and a good emulsifier composition cannot be obtained. Further, it is preferably a sodium salt, and acyl lactic acid and its calcium salt, magnesium salt, etc. may cause precipitation or aggregation of oil-soluble dyes, particularly oil-soluble salt-forming dyes, and the emulsion may be destroyed. Examples of the sodium salt of acyllactic acid used in the present invention include caproyl lactate sodium salt, 2-ethylhexanoyl lactate sodium salt, lauroyl lactate sodium salt, myristoyl lactate sodium salt, palmitoyl lactate sodium salt, stearoyl lactate sodium salt, Isostearoyl lactate sodium salt, oleoyl lactate sodium salt, 12-hydroxystearoyl lactate sodium salt, ricinooleyl lactate sodium salt, and the like may be used, and a mixture of these may be used. The amount of the acyl lactic acid sodium salt is preferably 0.1 wt% or more and 10 wt% or less.

  The higher alcohols having 14 to 24 carbon atoms used in the present invention are myristyl alcohol, cetyl alcohol, stearyl alcohol, nonadecanol, aralkyl alcohol, henycosanol, behenyl alcohol, tricosanol, carnerville alcohol, hexyldecanol, isostearyl alcohol, octyldodecanol. Oleyl alcohol, elaidyl alcohol and the like, and normal temperature solid saturated monohydric alcohols are preferred. These have almost no surface activity, but are presumed to be oriented at the interface between the water phase and the oil phase together with the nonionic surfactant because they have a long-chain alkyl group and a hydrophilic alcohol-OH group. Since these do not have a cloud point like a nonionic surfactant and have a high melting point, they have a function of retaining the interface even when the emulsion is at a high temperature and can improve the heat resistance of the emulsion. Moreover, since it does not melt | dissolve in water, it precipitates on oil-based ink on the paper surface, and it is thought that drying property can be improved. These can be used in an amount of 0.2% to 10.0% by weight, preferably 0.5% to 5% by weight, and 0.5 to 5 times the total amount of the nonionic surfactant is precipitated. High stability at high temperatures is preferable. If the addition amount is small, the effect of improving the heat resistance is not observed, and if it is too large, the entire amount cannot be dissolved on the oil phase side and is precipitated on the water phase side. If the higher alcohol has a carbon number of less than 14, it dissolves in water and does not orient at the interface, or even if it does not dissolve, there is a greater tendency to dissolve on the water phase side at high temperatures and destroys the interface of the water phase oil phase. Resulting in. Further, when the number of carbon atoms is 24 or more, only a very small amount dissolves on the oil phase side, precipitates in the oil phase, does not orient at the interface, and heat resistance is not improved.

  These higher alcohols having 14 to 24 carbon atoms can be used alone, but it is particularly preferable to use two or more kinds having different carbon numbers in combination because precipitation at low temperature storage can be prevented. The combination of cetyl alcohol and stearyl alcohol, and behenyl alcohol and stearyl alcohol is particularly good at low temperature stability.

As the colorant, dyes conventionally used in oil-based ballpoint pen inks can be used without limitation. As the dye, acid dyes, basic dyes, metal complex dyes, salt-forming dyes, azine dyes, anthraquinone dyes, phthalocyanine dyes, triphenylmethane dyes and the like can be used. Specifically, Bali First Yellow # 3104, Bali First Yellow # 3105, Bali First Yellow # 1105, Bali First Yellow AUM, Orient Spirit Black AB, Bali First Black # 3804, Bali First Black # 3806, Bali First Black # 1802, Bali First Black # 1805, Bali First Yellow # 1109, Bali First Orange # 2210, Bali First Red # 1320, Bali First Blue # 1605, Bali First Violet # 1701, Orient Oil Scarlet # 3 8. Nigrosine Base EX-BP (Oil Chemical Dye, Orient Chemical Co., Ltd.), Spiron Black GMH Special, Spiron Yellow C-2GH, Spiron Red C-GH, Spiron Red C-BH, Spiron Blue BPNH, Spiro Blue C-RH, Spiron Violet C-RH, S. P. T.A. Orange 6, S. P. T.A. Blue-111 (oil dye manufactured by Hodogaya Chemical Co., Ltd.), Rhodamine B base (CI. 45170B, oil dye manufactured by Sumitomo Chemical Co., Ltd.), Victoria Blue F4R, Nigrosine Base LK (Germany) Country, manufactured by BASF), methyl violet 2B base (manufactured by National Anil Div.), Etc. can be used.

  These may be used alone or in combination. The O / W emulsion oily component must be at least an ink component obtained by dissolving an oil-soluble dye as a colorant in an organic solvent, and the amount of the oil-soluble dye added is from 5% to 50% by weight of the oily component, preferably 10 wt% or more and 45 wt% or less can be used. If the amount used is small, the handwriting density becomes thin when it is made into an emulsion, and if it is too large, the oil component part becomes unstable because it does not dissolve in the organic solvent, and the thermal stability of the emulsion may deteriorate.

  Moreover, an acid dye, a direct dye, a basic dye, etc. can be used as a conventionally well-known aqueous dye for an aqueous phase for color tone adjustment. Pigments can also be used in both aqueous and oil phases. Specific examples of pigments include organic pigments such as azo pigments, nitroso pigments, nitro pigments, basic dye pigments, acidic dye pigments, built dye pigments, mordant dye pigments, and natural dye pigments. Examples thereof include inorganic pigments such as pigment, ocher, barium yellow, ultramarine, bitumen, cadmium red, barium sulfate, titanium oxide, dial, iron black, carbon black, and the like, and these can be dispersed with a conventionally known dispersant. .

  As a solvent that can be used for the oil-based ink component of the emulsion ink composition, it has been conventionally used in oil-based ballpoint pens, can dissolve oil-soluble dyes, and has a solubility in 100 g of water at 20 ° C. of substantially 5 g or less in water. An organic solvent that does not dissolve can be used. For example, ethylene glycol monohexyl ether, ethylene glycol mono 2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monoether ether solvent such as ethylene glycol monobenzyl ether, diethylene glycol monohexyl ether, diethylene glycol mono 2-ethylhexyl ether, diethylene glycol mono Diethylene glycol monoether solvents such as phenyl ether, propylene glycol monophenyl ether, dipropylene glycol mononormal propyl ether, propylene glycol monoether solvents such as dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, benzyl alcohol, β -Phenylethyla Alcohol solvents call or the like can be used. These may be used alone or in combination of two or more. In order to make the handwriting density deep and clear, it is preferable that the oil-soluble dye can be dissolved by 30% by weight or more. The amount is 1% by weight or more and 90% by weight or less based on the oil phase of the emulsion ink composition.

  Moreover, arbitrary auxiliary | assistant solvents can be included as a solvent which can be used for the oil-based ink component of an emulsion ink composition other than said main solvent. For example, a solvent selected from alcohols, polyhydric alcohols, polyhydric alcohol derivatives such as glycol ethers, hydrocarbons, ester solvents, ether solvents can be used, but a solvent having high solubility in water is an emulsion. Becomes unstable, and coalescence and separation are likely to occur. Also, solvents with low solubility of oil-based dyes should not be used in large quantities because dye precipitation may occur. About 10% or less of the total solvent of the oil-based ink component is preferable.

  Water having a conductivity of 0.05 to 100 μS / cm at 25 ° C. is used as an essential component of the O / W emulsion ink composition. In order to obtain a predetermined conductivity, ion exchange, distillation, reverse osmosis membrane filtration and the like can be performed, and a plurality of these means can be performed. Preferably, the conductivity at 25 ° C. is 0.05 to 10 μS / cm, and it is desirable to use ion-exchanged water or water obtained by performing ion exchange and distillation.

  If the oil-soluble dye used as a coloring material has moisture or inorganic salts, the solubility in a solvent may change, or precipitation of the dye or gelation of the oil component may occur. Especially during the aging at high temperatures, even if a small amount of inorganic salts dissolves in the oil phase, the oil component tends to become unstable, and the concentration of inorganic salts in the aqueous phase in the initial state must be sufficiently reduced. The emulsion particle size increases or the water phase oil phase is separated. In addition, water with high electrical conductivity is water with many impurities, such as inorganic salts.

  In addition to these essential components, conventionally known viscosity modifiers, dye dissolution accelerators, various resins and resin emulsions as fixing agents, antioxidants, ultraviolet absorbers, antiseptics, rust inhibitors, antifoaming agents, A pH adjuster and a lubricant for preventing ball seat wear and improving brushing performance can be used as appropriate in both the oil phase and the water phase. Especially when the pH of the emulsion ink is high, the structure of salt-forming dyes, etc. becomes unstable and the precipitation of the dye occurs, and when the pH is low, the corrosion of the ballpoint pen tip occurs. It is preferable to maintain the pH at about 4.5 to 9.5. At this time, it is desirable to use an organic acid or an organic amine in order not to increase the amount of the inorganic salt in the aqueous phase.

  In particular, it is desirable to mix a water-soluble organic solvent or a polyhydric alcohol with an aqueous component in order to prevent drying or freezing of the ink. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, Water-soluble organic solvents such as polyethylene glycol, polypropylene glycol, 1,3-butylene glycol, thiodiethylene glycol, glycerin, diglycerin, triglycerin, and tetraglycerin, and polyhydric alcohols such as sorbitol, maltitol, and fructose can be used. Is preferably 50% by weight or less of the entire aqueous component.

  In order to impart desirable viscosity and rheological performance as a ballpoint pen ink, conventionally known thickeners such as polymer polysaccharides, water-soluble acrylic resins, and inorganic minerals can be used as the aqueous component.

The oil component containing the oil-soluble dye with respect to the total amount of the O / W emulsion ink is preferably 10% by weight to 50% by weight, and the aqueous component is preferably 20% by weight to 75% by weight.

  The method of emulsification and dispersion for preparing the O / W emulsion ink is not particularly limited, and can be prepared by stirring at an appropriate temperature with a stirrer, homomixer, homogenizer or the like. Moreover, in order to make the produced emulsion further finer, it can also be subjected to a high-pressure homogenizer treatment, and can also be subjected to filtration or centrifugal treatment to make the emulsion particle size uniform or to remove insoluble matter.

  In order to dissolve a low HLB nonionic surfactant having a HLB of 8 or less or a higher alcohol sufficiently in the oil phase and prepare an emulsion in a liquid state, the temperature is preferably set to 70 ° C. or higher at the initial stage of emulsification. .

Adjustment of water conductivity The conductivity of tap water before ion exchange was measured with a conductivity meter ES-51 manufactured by Horiba, Ltd., and the conductivity at 25 ° C was 135.6 µS / cm.

  The tap water was ion-exchanged, distilled once, cooled, and measured for conductivity. The conductivity at 25 ° C. was 0.86 μS / cm.

The water having the conductivity of 0.86 μS / cm was stirred while measuring the conductivity, and tap water was added dropwise little by little to obtain water having a conductivity of 36.2 μS / cm at 25 ° C.
Example 1 (emulsion ink)
Spiro violet C-RH (Coloring agent: manufactured by Hodogaya Chemical Co., Ltd.) 4.5% by weight
Spiro Yellow C-GNH (Colorant: Hodogaya Chemical Co., Ltd.) 2.0% by weight
Spiron Red C-GH (colorant: manufactured by Hodogaya Chemical Co., Ltd.) 1.0% by weight
Benzyl alcohol 12.5% by weight
EMALEX 602 (polyoxyethylene (2) stearyl ether HLB = 4.0: manufactured by Nippon Emulsion Co., Ltd.) 0.8% by weight
Stearyl alcohol 0.4% by weight
Behenyl alcohol 0.6% by weight
Sodium stearoyl lactate 0.2% by weight
Triethanolamine 0.2% by weight
Glycerin 5.0% by weight
Water (conductivity at 25 ° C. 0.86 μS / cm) 72.8% by weight
Components other than the above glycerin and water are heated and stirred at 85 ° C. for 3 hours to prepare A liquid. Glycerin and water are stirred at 20 ° C. for 1 hour to prepare solution B. The liquid A was added to the liquid B at 80 ° C. and stirred for 10 minutes with a magnetic stirrer, and then further subjected to 3 passes while cooling to 20 ° C. with a high-pressure homogenizer to prepare a black emulsion ink.
Example 2 (emulsion ink)
A black emulsion ink was prepared in the same manner as in Example 1 except that water having a conductivity of 0.86 μS / cm at 25 ° C. was changed to water having a conductivity of 36.2 μS / cm at 25 ° C.
Example 3 (Emulsion ink)
Spiro Yellow C-GNH 1.0 wt%
Spiron Red C-GH 1.5% by weight
Spiron Red C-BH (Coloring agent: Hodogaya Chemical Co., Ltd.) 1.5% by weight
Ethylene glycol monophenyl ether 8.0% by weight
Ethylene glycol monohexyl ether 3.0% by weight
Decagulin 5-SV (decaglyceryl pentastearate, HLB = 3.5: manufactured by Nikko Chemicals Co., Ltd.) 1.2% by weight
Stearyl alcohol 0.6% by weight
Isostearoyl sodium lactate 0.3% by weight
Triethanolamine 0.1% by weight
Ethylene glycol 10.0% by weight
Ion-exchanged water (conductivity 36.2 μS / cm) 72.8% by weight
Components A other than ethylene glycol and ion-exchanged water are heated and stirred at 80 ° C. for 2 hours to prepare solution A. While stirring ethylene glycol and water heated to 80 ° C with a homogenizer, solution A was added dropwise, treated for 5 minutes, cooled in an ice bath, and further processed in 3 passes while cooling to 20 ° C with a high-pressure homogenizer to create a red emulsion ink. did.
Example 4 (Emulsion ink)
Spiron Blue C-RH (Colorant: manufactured by Hodogaya Chemical Co., Ltd.) 2.0% by weight
Benzyl alcohol 8.0% by weight
Ethylene glycol monophenyl ether 15.0% by weight Cosmelike S-50 (sucrose stearate ester HLB = 6: Daiichi Kogyo Seiyaku Co., Ltd. 30% monoester or more 70% diester) 1.5% by weight
Myristyl alcohol 2.0% by weight
Sodium stearoyl lactate 0.5% by weight
Triethanolamine 0.3% by weight
Ethylene glycol 5.0% by weight
Water (conductivity at 25 ° C. 36.2 μS / cm) 65.2% by weight
Components other than ethylene glycol and water are heated and stirred at 85 ° C. for 3 hours to prepare A liquid. Glycerin and water are stirred at 20 ° C. for 1 hour to prepare solution B. The liquid A was added to the liquid B at 80 ° C. and stirred for 10 minutes with a magnetic stirrer, and further treated for 3 passes while cooling to 20 ° C. with a high-pressure homogenizer to prepare a blue emulsion ink.
Example 5 (emulsion ink)
Spiro Yellow C-GNH 4.0 wt%
Benzyl alcohol 6.0% by weight
BO-2V (polyoxyethylene (2) oleyl ether, HLB = 7.5: manufactured by Nikko Chemicals Co., Ltd.) 2.5% by weight
Cetyl alcohol 0.2% by weight
Stearyl alcohol 0.1% by weight
Sodium stearoyl lactate 0.4% by weight
Triethanolamine 0.1% by weight
Ion-exchanged water (conductivity 0.86 μS / cm) 86.7% by weight
Components A other than water are heated and stirred at 80 ° C. for 2 hours to prepare Liquid A. Liquid A was added dropwise while stirring water heated to 80 ° C. with a homogenizer, treated for 5 minutes, cooled in an ice bath, and further subjected to 3 passes while cooling to 20 ° C. with a high-pressure homogenizer to prepare a yellow emulsion ink.
Comparative Example 1 (oil-based ink)
Spiro violet C-RH 4.5 wt%
Spiro Yellow C-GNH 2.0% by weight
Spiron Red C-GH 1.0 wt%
Benzyl alcohol 12.5% by weight
Ethylene glycol monophenyl ether 72.7% by weight
EMALEX 602 0.8% by weight
Stearyl alcohol 0.4% by weight
Behenyl alcohol 0.6% by weight
Sodium stearoyl lactate 0.2% by weight
Triethanolamine 0.2% by weight
Glycerin 5.0% by weight
PVP K-90 (Polyvinylpyrrolidone: manufactured by ISP Japan Co., Ltd.) 0.1% by weight
The above components were heated and stirred at 80 ° C. for 3 hours to dissolve the dye to prepare a black oil-based ink.
Comparative Example 2 (water-based ink)
Water black # 108-L (14% aqueous solution of CI DIRECT BLACK19, manufactured by Orient Chemical Co., Ltd.) 40.0% by weight
Kelzan AR 0.2% by weight
Ethylene glycol 10.0% by weight
Triethanolamine 0.1% by weight
Ion-exchanged water (conductivity 0.86 μS / cm) 49.7% by weight
In the above components, Kelzan AR and water were stirred for 30 minutes with a lab mixer and dissolved uniformly to prepare a Kelzan aqueous solution. The remaining components were added thereto, and the mixture was further stirred for 2 hours to prepare a black dye aqueous ink.
Comparative Example 3 (emulsion ink)
A black emulsion ink was prepared in the same manner as in Example 1 except that water having a conductivity of 0.86 μS / cm at 25 ° C. was changed to tap water having a conductivity of 135.6 μS / cm at 25 ° C.
Comparative Example 4 (emulsion ink)
A black emulsion ink was prepared in the same manner as in Example 1 except that Emalex 602 was replaced with Emalex 620 (polyoxyethylene (20) stearyl ether HLB = 13: manufactured by Nippon Emulsion Co., Ltd.).
Comparative Example 5 (emulsion ink)
In Example 1, except that the total amount of sodium stearoyl lactate was changed to water having a conductivity of 0.86 μS / cm at 25 ° C., it was treated with a high-pressure homogenizer in the same manner as in Example 1, but when left at room temperature for about 10 minutes, It separated into two layers of a phase and an oil phase, and an emulsion ink could not be obtained.
Comparative Example 6 (emulsion ink)
A red emulsion ink was prepared in the same manner as in Example 3 except that the total amount of stearyl alcohol in Example 3 was changed to water having a conductivity of 36.2 μS / cm at 25 ° C.
Comparative Example 7 (emulsion ink)
A blue emulsion ink was prepared in the same manner as in Example 4 except that the total amount of myristyl alcohol in Example 4 was decyl alcohol having 10 carbon atoms.
Comparative Example 8 (emulsion ink)
A blue emulsion ink was prepared in the same manner as in Example 4 except that the total amount of myristyl alcohol in Example 4 was changed to myosyl alcohol having 30 carbon atoms.
Initial state observation Drop 1 drop of emulsion ink into 10g of ion-exchanged water and stir lightly. When emulsion ink drops are separated from water, W / O type emulsion. When uniformly dispersed in water, O / W type. It was determined as an emulsion.
Particle size measurement The particle sizes of the emulsions were O / W type emulsion inks of Examples 1 to 5 and Comparative Examples 1, 3, 4, using a laser diffraction particle size distribution analyzer SALD-7100 manufactured by Shimadzu Corporation. 6 to 8 were diluted with ion-exchanged water, the particle size distribution was measured at 20 ° C., and the median diameter was adopted as the average particle diameter.
Particle size measurement after heat resistant aging at 50 ° C. for 24 hours 10 g of inks of Examples 1 to 5 and Comparative Examples 1, 3, 4, and 6 to 8, which are O / W emulsion inks, were screwed glass bottles with lids (19 × 70 mm, The product was placed in Nidec Rika Glass Co., Ltd., placed at 50 ° C. for 24 hours, and allowed to stand at 20 ° C. for 5 hours, and then the particle size was measured after aging in the same manner as the particle size measurement.
Particle size measurement after heat aging at 50 ° C. for 3 weeks O / W emulsion ink Examples 1 to 5 and Comparative Examples 1, 3, 4, and 6 to 8 g of ink were added to a screw cap glass bottle with a lid (19 × 70 mm). And then placed at 50 ° C. for 3 weeks and allowed to stand at 20 ° C. for 5 hours, and then the particle size after aging was measured in the same manner as the particle size measurement.
The ink of Comparative Example 8 was not subjected to particle size measurement because a white precipitate was visually observed after the lapse of time and the entire ink gelled and lost fluidity and could not be diluted for particle size measurement.
Preparation of test sample for writing test It has a ball-point pen nib which held each of the ink compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 4 and 6 to 8 with a carbide ball having a diameter of 0.5 mm. 1.7 g of the ink storage tube of a knock type ballpoint pen (knock type energel, product code BLN75, manufactured by Pentel Co., Ltd.) was filled to obtain a test ballpoint pen sample.
Handwriting Water Resistance Test Each ball-point pen test sample is handwritten on JIS P3201 writing paper A by hand with 15 continuous circles having a diameter of about 2 cm twice, left for 1 hour, and then immersed in ion-exchanged water for 1 hour. Then, it took out from water and determined the degree of fading with a gray scale (JIS L-0804). The gray scale is from 1 to 5, and the larger the number, the smaller the density difference between the handwriting before and after the test, indicating water resistance. In addition, what was judged to be located in the middle of each number was expressed as a numerical value obtained by adding 0.5 to the lower number.
Handwriting show-through test Write 15 consecutive circles with a diameter of about 2cm by hand on JIS P3201 writing paper A twice for each ballpoint pen test sample, and leave it for one day in an environment of 30 ° C and 60% RH. The back side was observed.

Those that did not exude ink at all ... ◎
The one that had only a slight oozing… ○
Clearly exuded …… ×
It was.
Handwriting dryness test Using the above test ballpoint pen sample, write five continuous circles with a diameter of about 2 cm by hand on JIS P3201 writing paper A, and change the time after writing at intervals of 5 seconds onto the handwriting. When a filter paper (No. 2 manufactured by Advantech) with a load of 500 g was placed, the time until ink was not applied to the filter paper was determined. An ink having a short time is an ink having excellent handwriting dryness.

  The results of each test are shown in Table 1.

以上、詳細に説明したように本発明のＯ／Ｗ型エマルションインキ組成物は加熱経時後でも粒径の変化が少なく温度安定性に優れるため長期の常温経時安定性もよく、ボールペンに充填して長期間保存した場合にも、粒子沈降などの偏りによる筆跡の濃度差や、リフィル外観での色分離がなく、更に、エマルションが破壊され難いので、筆跡の裏写りや耐水性、乾燥性にも優れた性能を持つものである。

As described above in detail, the O / W emulsion ink composition of the present invention has little change in particle size even after heating, and is excellent in temperature stability. Even when stored for a long period of time, there is no difference in handwriting density due to bias such as particle sedimentation, color separation in the refill appearance, and the emulsion is difficult to break down, so the handwriting show-through, water resistance and dryness are also improved. It has excellent performance.

Claims (1)

An oil-based ink component (A) containing at least an oil-soluble dye as a colorant and an organic solvent having a solubility in 100 g of water of 5 g or less at 20 ° C., and a nonionic surfactant having an HLB of 8 or less Contains at least an emulsifier component (B) containing at least a sodium salt of acyllactic acid having 8 or more carbon atoms and a higher alcohol having 14 to 24 carbon atoms, and water having a conductivity of 25 to 100 ° C. An O / W emulsion ink composition for ballpoint pens in which the oil-based ink component (A) is emulsified and dispersed in water.