Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/40—Compounds of aluminium
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/06—Treatment with inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/16—Writing inks
  • C09D11/17—Writing inks characterised by colouring agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/16—Writing inks
  • C09D11/18—Writing inks specially adapted for ball-point writing instruments

Definitions

• the present invention relates to an ink composition containing platelet alumina.
• ink compositions containing, for example, a colorant and a solvent such as an organic solvent or water are known, and pigment inks containing a pigment as the colorant are widely used.
• pigment inks containing a pigment as the colorant are widely used.
• inks using titanium oxide as a white pigment, which has excellent hiding power and clarity, are widely used.
• alumina may be added together with a colorant such as titanium oxide (Patent Documents 1 and 2).
• a ballpoint pen tip has a ball and a ball holder, and by adding alumina, it is possible to reduce wear on the ball seat (referring to the contact point between the ball and the ball holder) caused by friction generated by the rotation of the ball during writing.
• the frictional force between the ball and the ball seat is smaller than the frictional force between the paper surface and the ball, preventing skipping of the line.
• alumina has low hiding power, and when added as an additive there is a risk that it will reduce the inherent hiding power of the ink composition.
• Non-Patent Document 1 shows that plate-like NaNbO 3 of the submicron order has high hiding power, but even when alumina is similarly made to the submicron order, the improvement in hiding power is insufficient.
• the objective of the present invention is to provide an ink composition containing alumina particles that can achieve high hiding power.
• the present invention is as follows.
• alumina particles of a specific particle size and thickness by surface treating alumina particles of a specific particle size and thickness, it is possible to provide an ink composition that achieves high hiding power.
• the ink composition of the present invention is characterized in that it contains alumina particles having a specific particle size and aspect ratio, and the alumina particles have a metal oxide layer on the surface thereof.
• the D50 of the alumina particles is 1 ⁇ m or more and 5 ⁇ m or less, and more preferably 1.1 ⁇ m or more and 4 ⁇ m or less.
• the D50 is within the above range, the dry hide effect is easily exhibited when a metal oxide layer described later is provided, and the hiding power of the ink coating film can be improved.
• D100 of the alumina particles there are no particular limitations on the D100 of the alumina particles, but it is preferable that D100 is 15 ⁇ m or less. If D100 is 15 ⁇ m or less, the proportion of coarse alumina particles is reduced, and a uniform and vivid color can be obtained when the ink is applied to the ink film.
• D50 and D100 refer to values calculated from the volume-based cumulative particle size distribution measured using a laser diffraction particle size distribution analyzer.
• the aspect ratio which is the ratio of the average particle diameter (D50) to the thickness of the alumina particles, is from 10 to 50, preferably from 12 to 45, and more preferably from 15 to 40.
• D50 average particle diameter
• the aspect ratio of the alumina particles is within the above range, good hiding performance can be obtained when the alumina particles are made into an ink coating.
• the alumina particles are aluminum oxide and may be transition alumina of various crystal forms, such as gamma, delta, theta, and kappa, or may contain alumina hydrate in transition alumina, but the alpha crystal form (alpha type) is generally preferred because of its superior stability.
• the alumina particles may further contain molybdenum, and may also contain impurities derived from the raw materials or shape control agents, as long as the effects of the present invention are not impaired.
• the alumina particles used in the present invention may be produced by any method that satisfies the requirements for D50 and aspect ratio, and may be produced by known, commonly used production methods such as the hydrothermal method and the flux method.
• a method for more simply obtaining the desired alumina particles includes the method described in JP 2016-222501 A, in which an aluminum compound is fired in the presence of a molybdenum compound and a shape control agent.
• the metal oxide layer contained in the alumina particles is preferably one or more of zinc oxide, silicon dioxide, zirconium dioxide, and titanium oxide. Silicon dioxide is particularly preferable because it forms a porous structure and contains air on the surface of the alumina, thereby increasing the difference in refractive index between the binder and the metal oxide layer.
• the metal oxide layer is preferably a single layer.
• a single layer provides superior hiding power due to the difference in refractive index. Note that a single layer means that it is made of one type of component, and indicates that there are not two types of layers, for example, a zinc oxide layer and a silicon dioxide layer.
• the metal oxide layer may be formed on at least a portion of the surface of the alumina particle, but is more preferably formed on the entire surface of the alumina particle.
• the surface of the alumina particle means the outside of the surface of the alumina particle. Therefore, it is clearly distinguished from the surface layer containing mullite or germanium that is formed on the inside of the surface of the alumina particle.
• the thickness of the metal oxide layer is not particularly limited, but from the standpoint of hiding power and cost, it is 0.1 nm or more, but is thin enough that it cannot be measured in an SEM image.
• the amount of metal oxide in the metal oxide layer relative to the amount of alumina in the alumina particles is not particularly limited, but is preferably 5% by mass or less, more preferably 3% by mass or less, and more preferably more than 0% by mass. Being within the above range is preferable because it provides excellent hiding power when made into an ink composition.
• the method for forming the metal oxide layer is not particularly limited and may be a known method.
• a porous silicon dioxide layer can be formed by adding a solution of sodium silicate, adjusting the pH with a strong acid, and then drying.
• the content of the alumina particles having metal oxide may be set appropriately depending on the application, but is preferably 1 to 15% by mass, and more preferably 3 to 12% by mass, based on the total mass of the ink composition. Being within the above range is preferable because it provides both excellent hiding power and color development.
• the ink composition of the present invention may further contain titanium oxide particles.
• the titanium oxide particles are not particularly limited, and either rutile type or anatase type may be used, but it is preferable that the average particle size is 0.01 ⁇ m or more.
• known titanium oxides such as Bayertitan R-FD-1, R-KB-3, and R-CK-20 (all manufactured by Bayer), TIPAQUE R-630, R-615, R-830, and LPT series (all manufactured by Ishihara Sangyo Kaisha, Ltd.), Unitane OR-342 (manufactured by ACC), Ti-pure R-900 and R-901 (manufactured by Chemours), and Luxelene Silk series (manufactured by Sumitomo Chemical Co., Ltd.) may be used.
• the amount added is preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.005% by mass or more and 5% by mass or less, and particularly preferably 0.02% by mass or more and 4% by mass or less, based on the total mass of the ink composition. If it is within the above range, the resulting coating film will have excellent hiding power and L value, and will also have excellent ink ejection performance, which is preferable.
• the ink composition of the present invention may contain an organic solvent, for example, aromatic hydrocarbon solvents such as toluene, xylene, ethylbenzene, etc., aliphatic hydrocarbon solvents such as n-hexane, n-heptane, isoheptane, n-octane, isooctane, etc., cycloparaffin solvents such as methylcyclohexane, ethylcyclohexane, etc., ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, etc., glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, glycerin, etc., glycol ether solvents such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, etc., which may be used alone or in combination of two or more.
• the amount of organic solvent contained is not particularly limited, but from the viewpoint of the drying speed of the ink coating, it is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total mass of the ink composition.
• the ink composition of the present invention may contain a resin, and examples thereof include polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, terpene resin, alkyd resin, phenoxy resin, polyvinyl acetate resin, polyvinylpyrrolidone resin, ethylene oxide polymer, acrylic resin, styrene-acrylic resin, styrene-maleic acid resin, and the like. These may be used alone or in combination of two or more kinds.
• the resin content is preferably 0.05 to 30% by mass, and particularly preferably 0.1 to 25% by mass, based on the total mass of the ink composition.
• the ink composition of the present invention may contain a dispersant, and examples thereof include nonionic surfactants such as glycerin fatty acid esters, polyoxyethylene methyl ether, polyoxyethylene lanolin alcohol, polyoxyethylene alkylamines, and polyoxyethylene fatty acid amides; anionic surfactants such as alkyl sulfates, N-acylamino acid salts, polyoxyethylene alkyl ether acetates, and alkyl phosphates; cationic surfactants such as alkylamine salts and quaternary ammonium salts; amphoteric surfactants such as alkyl betaines, alkyl amine oxides, and phosphatidylcholines; and polymeric surfactants such as acrylics.
• nonionic surfactants such as glycerin fatty acid esters, polyoxyethylene methyl ether, polyoxyethylene lanolin alcohol, polyoxyethylene alkylamines, and polyoxyethylene fatty acid amides
• the amount of dispersant contained is determined appropriately depending on the solvent and other components used, but from the standpoint of dispersion stability and ink viscosity, it is preferably 0.1 to 30 mass% of the total mass of the ink composition, and particularly preferably 0.5 to 20 mass%.
• additives such as colorants such as organic pigments, inorganic pigments, acid dyes, basic dyes, and direct dyes; rust inhibitors such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, metal salt compounds, and phosphate compounds; preservatives such as carbolic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, and 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine; silicone-based, mineral oil-based, polyether-based, and fluorine-based defoamers; antioxidants; stabilizers; inorganic salts such as sodium carbonate, sodium phosphate, and sodium acetate, and organic basic compounds such as water-soluble amine compounds, and the like, may also benzotriazole, tolyltri
• the ink composition of the present invention can be produced by a known method without any particular limitation.
• the ink composition can be produced by mixing the above-mentioned components in appropriate amounts and mixing them with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill.
• various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill.
• a disperser such as a bead mill or a paint conditioner.
• the viscosity of the ink composition is not particularly limited, but the ink viscosity at 20°C and a shear rate of 5 sec -1 (at rest) is preferably 30,000 mPa ⁇ s or less, and more preferably 25,000 mPa ⁇ s or less. When it is equal to or less than the upper limit, it is preferable in terms of excellent ink dischargeability and writing comfort. From the viewpoint of suppressing ink leakage, it is preferably 500 mPa ⁇ s or more, and more preferably 1,000 mPa ⁇ s or more.
• the structure of the writing implement to which the ink composition of the present invention is applied is not particularly limited.
• the ink composition of the present invention is not only highly opaque, but is also expected to exhibit low abrasion effects due to the use of alumina, and is therefore suitable for use as an ink for a ballpoint pen having a ball and a ball seat.
• By using the writing implement of the present invention it is possible to stably draw lines while maintaining opaqueness.
• the obtained light blue powder was dispersed in 150 mL of 0.5% ammonia water, and the dispersion solution was stirred at room temperature (25-30°C) for 0.5 hours, after which the ammonia water was removed by filtration, and the molybdenum remaining on the particle surface was removed by washing with water and drying, yielding 47 g of light blue powder.
• the obtained powder was confirmed to have a plate-like shape by SEM observation. Furthermore, when X-ray diffraction (XRD) measurement was performed, sharp peak scattering due to ⁇ -alumina was observed, and no alumina crystal system peaks other than the ⁇ crystal structure were observed, confirming that the particles were plate-like alumina particles with a dense crystal structure.
• the ⁇ conversion rate was 99% or more (almost 100%).
• the obtained light blue powder was dispersed in 150 mL of 0.5% ammonia water, and the dispersion solution was stirred at room temperature (25-30°C) for 0.5 hours, after which the ammonia water was removed by filtration, and the molybdenum remaining on the particle surface was removed by washing with water and drying, yielding 47 g of light blue powder.
• the obtained powder was confirmed to have a polygonal plate shape by SEM observation. Furthermore, when X-ray diffraction (XRD) measurement was performed, sharp peak scattering due to ⁇ -alumina was observed, and no alumina crystal system peaks other than the ⁇ crystal structure were observed, confirming that the particles were plate-shaped alumina particles with a dense crystal structure.
• the ⁇ conversion rate was 99% or more (almost 100%).
• the resulting light blue powder was then dispersed in 150 mL of 0.5% aqueous ammonia, and the dispersion was stirred at room temperature (25-30°C) for 0.5 hours.
• the aqueous ammonia was then removed by filtration, and the molybdenum remaining on the particle surface was removed by washing with water and drying, yielding 33.5 g of light blue powder.
• SEM observation of the resulting powder confirmed that it was plate-like in shape, with very few aggregates.
• XRD measurement revealed sharp peak scattering due to ⁇ -alumina, and no alumina crystal peaks other than the ⁇ crystal structure were observed, confirming that the particles were plate-like alumina particles with a dense crystal structure.
• the ⁇ conversion rate was 99% or more (almost 100%).
• titanium oxide particles (Typaque R-830, manufactured by Ishihara Sangyo Kaisha, Ltd.) were prepared (T-1).
• Aspect ratio D50/D particle diameter D50 of plate-like alumina particles / average thickness D of plate-like alumina particles
• the plate-like alumina particles were placed on a measurement sample holder with a depth of 0.5 mm, packed flat under a constant load, and then set in a wide-angle X-ray diffraction apparatus (Rigaku Corporation, Rint-Ultma) and measured under conditions of Cu/K ⁇ radiation, 40 kV/30 mA, a scan speed of 2 degrees/min, and a scan range of 10 to 70 degrees.
• the ⁇ conversion rate was calculated from the ratio of the strongest peak heights of ⁇ -alumina and transition alumina.
• the fillers used in the examples and comparative examples are as shown in Table 1.
• the obtained white ink composition was applied to a colored drawing paper (Koikura, manufactured by PLUS Corporation) to form a coating film using a bar coater RDS20.
• the coating film was dried at room temperature for one day and night, and the hiding power of the coating surface was evaluated by the L value.
• the L value was measured using a spectro-guide 45/0 gloss (manufactured by BYK-Gardner GmbH).
• An L value of 89 or more was evaluated as ⁇ , indicating that the coating sufficiently concealed the coating surface and was good, and an L value below that was evaluated as ⁇ , indicating that the hiding power was insufficient.
• Examples 1 and 2 and Comparative Example 1 confirmed that forming a metal oxide layer on alumina particles of a specific particle size provides good hiding power.
• Examples 1 and 2 and Comparative Example 2 confirmed that forming a metal oxide layer improves hiding properties.
• Examples 1 and 2 and Comparative Example 3 confirmed that alumina particles with a metal oxide layer formed thereon have better hiding power than titanium oxide particles alone.

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• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)

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• 2024
  • 2024-02-29 WO PCT/JP2024/007464 patent/WO2024190432A1/ja not_active Ceased
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