JP2007099869A - Oily ink composition for writing instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oily ink composition for writing instruments having excellent resistance to drying-up and excellent in ink stability free from deposits with time. <P>SOLUTION: The oily ink composition at least comprises a colorant, an organic solvent, a resin, and a fatty acid ester represented by the general formula (1): R<SB>1</SB>COOR<SB>2</SB>, wherein R<SB>1</SB>denotes a 21C linear saturated alkyl group; and R<SB>2</SB>denotes a 1-6C linear or branched saturated alkyl group. The content of the fatty acid ester in the total amount of the ink composition is 0.1-10 wt.%. The writing instrument retains the above oily ink composition for writing instruments. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an oil-based ink composition for writing instruments. More specifically, an oil-based ink composition for writing instruments with excellent dry-up resistance (cap-off performance) that suppresses the occurrence of blurring or inability to write due to drying of the nib that occurs when left for a long time with the cap removed. Related to things.

Conventionally, oil-based inks for writing instruments have the advantage that the handwriting dries quickly, while the pen tip dries when left with the cap removed, and the resin and colorant in the ink dries and cures. There is a problem that defects are likely to occur.
Therefore, in order to solve the above problems, addition of various compounds has been studied, and techniques for adding polyglycerol fatty acid esters, sorbitan fatty acid esters, higher fatty acid esters and the like have been disclosed (for example, see Patent Documents 1 to 3).
Japanese Examined Patent Publication No. 62-34352 Japanese Patent Laid-Open No. 1-87777 JP 2001-207100 A

However, when polyglycerin fatty acid ester or sorbitan fatty acid ester is added to the oil-based ink, with the evaporation of the solvent from the nib, the compound forms a film on the nib surface and imparts dry-up resistance. In winter when the environmental temperature is low, the compound may be precipitated in the ink.
In addition, when a higher fatty acid ester is added, the solubility in solvents is very low, so there is a possibility that it may easily precipitate in the ink or cause problems such as difficulty in obtaining sufficient dry-up performance. .

  The present invention provides an oil-based ink composition for a writing instrument that solves the above-described problems, exhibits excellent dry-up resistance, and has excellent ink stability that does not generate precipitates over time. Is.

The oil-based ink composition for writing instruments of the present invention is required to contain at least a colorant, an organic solvent, a resin, and a fatty acid ester given by the following general formula (1).
R ₁ COOR ₂ (1)
[R ₁ in the formula (1) is a linear saturated alkyl group of 21 carbon atoms, R ₂ is a straight-chain or branched saturated alkyl group having 1 to 6 carbon atoms. ]
Furthermore, it is a requirement that the fatty acid ester is contained in an amount of 0.1 to 10% by weight in the total amount of the ink composition.
Furthermore, the writing instrument which incorporates the oil-based ink composition for writing instruments is a requirement.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an oil-based ink composition for a writing instrument that has excellent dry-up resistance and has excellent ink stability that does not generate precipitates over time, and a writing instrument that incorporates the oil-based ink composition.

The fatty acid ester of the general formula (1) applied to the present invention is an ester composed of behenic acid and a lower to intermediate alcohol having 1 to 6 carbon atoms, and the melting point of the lower to intermediate alcohol is low. It precipitates in a state.
By adding it to the oil-based ink composition, as the solvent evaporates from the nib, it precipitates in a wax state, forms a film on the nib, gives excellent dry-up resistance, and has high solubility. Thus, there is no risk of precipitation over time.
Therefore, compared with the conventional higher fatty acid ester which forms a crystalline solid film, it is excellent in stability over time and continuously suppresses evaporation of the solvent.

The fatty acid ester is added to the ink in an amount of 0.1 to 10% by weight, preferably 0.1 to 5% by weight.
If it is less than 0.1% by weight, it becomes difficult to provide desired dry-up resistance. Although a large amount can be added, the desired effect can be sufficiently obtained at 10% by weight or less.

As the colorant, general-purpose dyes and pigments conventionally applied to oil-based inks are appropriately used.
Examples of the dye include organic solvent-soluble dyes classified as solvent dyes in the color index.
Specific examples of the solvent dye include Balifast Black 3806 (CI Solvent Black 29), 3807 (Trimethylbenzylammonium salt of the dye of CI Solvent Black 29), Spirit Black SB (C.I. Solvent Black 5), Spiron Black GMH (CI Solvent Black 43), Bali Fast Red 1308 (Salt Form of Dye of CI Basic Red 1 and Dye of CI Acid Yellow 23), Bali Fast Yellow AUM (Salt of CI Basic Yellow 2 dye and CI Acid Yellow 42 dye), Spiron Yellow C2GH (organic acid salt of CI Basic Yellow 2 dye) Ron Violet CRH (CI Solvent Violet 8-1), Balifu Strioviolet 1701 (salt salt of CI Basic Violet 1 and CI Acid Yellow 42 dyes), Spiron Red CGH (organic acid salt of CI Basic Red 1 dye), Spiron Pink BH (C.I. CI Solvent Red 82), Nigrosine Base EX (CI Solvent Black 7), Oil Blue 613 (CI Solvent Blue 5), Neozapon Blue 808 (CI Solvent Blue 70) and the like. It is done.
Examples of the pigment include inorganic pigments such as carbon black, ultramarine, and titanium dioxide pigment, azo pigments, phthalocyanine pigments, indigo pigments, thioindigo pigments, selenium pigments, quinacridone pigments, anthraquinone pigments, selenium pigments, diketopyrrolo Organic pigments such as pyrrole pigments, dioxazine pigments, perylene pigments, perinone pigments, isoindolinone pigments, aluminum pigments, metal pigments whose surfaces are treated with colored resins, transparent or colored transparent films such as aluminum Metallic pigment, gold, silver, platinum, copper, with a thickness of 0.01 to 0.1 μm, obtained by peeling a metallic vapor deposited film such as aluminum formed on a substrate such as a metallic luster pigment, film, etc. Colloidal particles with an average particle size selected from 5 to 30 nm, fluorescent pigments, luminous pigments, thermal discoloration Pigments, natural mica as a core material, synthetic mica, glass pieces, alumina, pearl pigment and the like to the surface of the transparent film pieces were coated with a metal oxide such as titanium oxide.
The colorant may be used alone or in combination of two or more, and is used in the range of 3 to 40% by weight in the ink composition.

Examples of the organic solvent include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, tert-amyl alcohol, benzyl alcohol, ethylene glycol, diethylene glycol, Propylene glycol, benzyl glycol, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether, diethylene glycol monophenyl ether, propylene Glycolmo Methyl ether, propylene glycol monoethyl ether, propylene glycol monophenyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monophenyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monophenyl ether, n -Heptane, n-octane, isooctane, methylcyclohexane, ethylcyclohexane, toluene, xylene, ethylbenzene, methyl isobutyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, di-n-propyl ketone, n-butyl formate, isobutyl formate Methyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, propionate Le, n- butyl propionate, methyl butyrate, ethyl butyrate, dimethyl carbonate, diethyl carbonate, propyl carbonate, etc. can be exemplified.
The organic solvent may be used singly or in combination of two or more, and is used in the range of 40 to 90% by weight in the ink composition.

The resin is not particularly limited as long as it is soluble in an organic solvent that is usually used in an oil-based ink composition, and is intended to impart handwriting blur suppression, fixability improvement, fastness, and the like. Can be added to the ink.
Specifically, ketone resin, amide resin, alkyd resin, rosin modified resin, rosin modified phenol resin, phenol resin, xylene resin, polyvinyl butyral resin, terpene resin, coumarone-indene resin, polyvinyl pyrrolidone, polyethylene oxide, polymethacryl Examples include acid esters, ketone-formaldehyde resins, α- and β-pinene / phenol polycondensation resins, polyvinyl butyral resins, acrylic resins, and polyacrylic acid-polymethacrylic acid copolymers.
These resins may be used singly or in combination of two or more, and are used in the range of 0.5 to 40% by weight, preferably 1 to 35% by weight in the ink composition. If the amount is less than 0.5% by weight, sufficient effects such as suppression of handwriting on paper, improvement of fixing property, imparting fastness and the like cannot be exerted. If the amount exceeds 40% by weight, the solubility of the resin in the solvent decreases. In addition, the fluidity of the ink decreases.

Furthermore, the oil-based ink composition for a writing instrument of the present invention contains, in addition to the above components, an antioxidant, an ultraviolet absorber, a rust inhibitor, a lubricant, a viscosity modifier, a release agent, a pigment dispersant, an anti-oxidant, as necessary. Various additives such as a foaming agent, a shear thinning agent, and a surfactant can be used.
For example, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, etc. can be used as a rust inhibitor.
As the antioxidant, dibutylhydroxyl toluene, nordihydroxytoluene, flavonoids, butylhydroxyanisole, ascorbic acid derivatives, α-tocopherol, catechins and the like can be used.
As UV absorbers, 2- (2'-hydroxy-3'-t-butyl 5'-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-methylphenyl) Benzotriazole, p-benzoic acid-2-hydroxybenzophenone, and the like can be used.
As the antifoaming agent, dimethylpolysiloxane or the like can be used.
The additive is a so-called conventional additive, and can be appropriately used from known compounds as needed.

  When the oil-based ink composition of the present invention is applied to a ballpoint pen, a higher fatty acid such as oleic acid, a nonionic surfactant having a long-chain alkyl group, a polyether-modified silicone oil, a thiophosphite tri (alkoxycarbonyl) A lubricant such as a thiophosphite triester such as a methyl ester) or a thiophosphite triester (alkoxycarbonylethyl ester) can be added if necessary. Particularly, a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether Use of phosphoric acid monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid diester, or their metal salts, ammonium salts, amine salts, alkanolamine salts, etc., will prevent wear of the ball seat. Excel

Furthermore, by adding a shear thinning agent, ink leakage from the gap between the ball and the tip when not in use is prevented, or the ink flows backward when the writing tip is left facing upward (upright state). Can be prevented.
When a shear thinning agent is added, the ink viscosity at a shear rate of 3.84S ⁻¹ by an E-type viscometer at 20 ° C. is 10 mPa · s (20 ° C.) or more, preferably 10 to 10,000 mPa · s. s and the shear thinning index is preferably adjusted to a range of 0.3 to 0.99. By showing the above-described viscosity range and the shear thinning index, ink leakage is further caused and ink backflow is reduced. Can be prevented.
Moreover, when a pigment is used in combination as a colorant, aggregation and sedimentation of the pigment can be suppressed.
When the ink viscosity is less than 10 mPa · s, the effect of shear thinning is not appropriate, and ink ejection properties and handwriting performance may be hindered.
The shear thinning index (n) is expressed by an empirical formula T = Kj ⁿ (K is a non-Newtonian viscosity coefficient) obtained from rheological measurement by a viscometer such as a shear stress value (T) and a shear rate value (j). It is a value calculated by fitting.

  As the shear thinning agent, a conventionally known compound can be used. For example, a crosslinkable acrylic resin, a crosslinkable acrylic resin emulsion type, a crosslinkable N-vinylcarboxylic acid amide polymer, or a copolymer Non-crosslinked N-vinylcarboxylic acid amide polymer or copolymer Non-crosslinked N-vinylcarboxylic acid amide polymer or copolymer aqueous solution, hydrogenated castor oil, fatty acid amide wax, polyethylene oxide wax, etc. , Fatty acid metal salts such as aluminum stearate, aluminum palmitate, aluminum octylate, aluminum laurate, dibenzylidene sorbitol, dextrin fatty acid ester, N-acyl amino acid compound, smectite inorganic compound, montmorillonite inorganic compound, bentonite Inorganic compound , Hectorite inorganic compound, silica and the like.

The ink composition is put into practical use by filling a marking pen or ballpoint pen with a tip attached to the writing tip.
When filling the marking pen, the structure and shape of the marking pen itself are not particularly limited. For example, a fiber tip, felt tip, plastic tip is attached to the writing tip, and the fiber bundle contained in the shaft cylinder is used. The ink occlusion body is impregnated with ink, the ink is supplied to the tip of the writing, the ink is directly stored inside the shaft cylinder, and the ink flow rate adjustment member consisting of a comb groove-like ink flow rate adjustment member or fiber bundle is interposed Examples include a marking pen having a structure in which ink is directly stored in the shaft cylinder and a predetermined amount of ink is supplied to the writing tip portion by a valve mechanism.
When filling the ball-point pen, the structure and shape of the ball-point pen itself are not particularly limited. For example, an ink occlusion body composed of a fiber bundle housed in the shaft tube is impregnated with ink and supplied to the writing tip. Structure, ink is stored directly inside the shaft cylinder, and there is an ink storage tube filled with the ink composition in the shaft cylinder, with a comb groove-shaped ink flow control member and an ink flow control member consisting of fiber bundles interposed The ink storage tube communicates with a tip having a ball attached to the tip, and a ballpoint pen having a structure in which an ink follower such as a liquid stopper or a solid stopper is in close contact with the end face of the ink to prevent backflow it can.

  The oil-based ink composition for a writing instrument of the present invention is prepared by adding a colorant, a resin, a fatty acid ester, and various additives as required in an organic solvent, further heating and stirring as necessary, and dissolving and dispersing. It is used by filling a writing instrument in the form of a ballpoint pen, a sign pen, a felt pen, a brush pen or the like.

The ink compositions of Examples and Comparative Examples are shown in the following table.
In addition, the numerical value of a composition in a table | surface shows a weight part.

The contents of the raw materials in the table are explained according to the note numbers.
(1) Clariant Japan Co., Ltd. product name: Renol Black R-HW30
(2) Product name: Bali Fast Black 3810, manufactured by Orient Chemical Industry Co., Ltd.
(3) Product name: Bali Fast Red 1308, manufactured by Orient Chemical Co., Ltd.
(4) Arakawa Chemical Industries, Ltd., trade name: Marquide No. 33
(5) Nikko Chemicals Co., Ltd., trade name: Nikkor SS-10

Preparation of ink Each raw material was mixed by the compounding amount of the said Example and a comparative example, and the oil-based ink composition for writing instruments was obtained by stirring with a disper for 1 hour in a heated state.

Production of Marking Pen An oil-based marking pen was obtained by filling the obtained ink composition into a commercially available marking pen (manufactured by Pilot Corporation; M-10EF).

Ink Stability Test The ink compositions prepared in each Example and Comparative Example were allowed to stand at 20 ° C. for 24 hours, and then the ink state was observed with a microscope.

Dry-up resistance test Using each marking pen, leave the pen tip in a horizontal position in an environment of 20 ° C and 60% humidity, then write on the paper every hour, causing blurring in the handwriting. The time was measured.
The test results are shown in the following table.

The contents of the symbols in the table will be described below.
Ink stability test ○: No precipitate is observed.
X: Precipitates are observed.
Dry-up resistance test The numerical values in the table represent the time (h) that the blur was generated on the handwriting for the first time.

Claims (3)

An oil-based ink composition for a writing instrument comprising at least a colorant, an organic solvent, a resin, and a fatty acid ester given by the following general formula (1).
R ₁ COOR ₂ (1)
[R ₁ in the formula (1) is a linear saturated alkyl group of 21 carbon atoms, R ₂ is a straight-chain or branched saturated alkyl group having 1 to 6 carbon atoms. ]   The oil-based ink composition for a writing instrument according to claim 1, comprising 0.1 to 10% by weight of the fatty acid ester in the total amount of the ink composition.   A writing instrument comprising the oil-based ink composition for a writing instrument according to claim 1 or 2.