Edible ink composition

Abstract

Provided is an edible ink composition which does not contain titanium oxide.　According to the present invention, an edible ink composition which does not contain titanium oxide and has a high drying rate is produced by using magnesium carbonate, magnesium hydroxide, or the like as a whitening agent, and mixing an alcohol-soluble binder, an alcohol that serves as a solvent, and optional additives.　Since this edible ink composition uses, as a white pigment, magnesium carbonate or the like, which has been safely used in the past as a pharmaceutical product and is free of health issues, in place of titanium oxide, the edible ink composition can be used in solid foods or in solid pharmaceutical preparations. This edible ink composition is particularly useful as an ink when printing is performed on the surfaces of capsules, tablets and caplets by means of offset printing.

Description

Edible ink composition

[0001] The present invention relates to an edible ink composition that does not contain titanium oxide. The present invention relates to an edible ink composition that contains a whitening agent and a white pigment selected from the group consisting of magnesium carbonate (including basic magnesium carbonate, light magnesium carbonate, and heavy magnesium carbonate), magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, tricalcium phosphate, carnauba wax, dolomite, bentonite, agar, activated clay, and mixtures thereof, and further contains an alcohol-soluble film-forming polymer (hereinafter referred to as an alcohol-soluble binder) as a binder and alcohol as a solvent.

[0002] The present invention relates to an edible ink composition containing a white pigment, particularly magnesium carbonate, as a whitening agent. The present invention also relates to an edible ink composition suitable for printing, particularly offset printing, on the surfaces of solid foods and solid pharmaceutical preparations, such as confectioneries, candies, tablets, and capsules, and a method for producing the same. The present invention also relates to a method for offset printing using the edible ink composition containing the above-mentioned whitening substance, and solid foods and solid pharmaceutical preparations (e.g., tablets, caplets, and capsules) printed with the edible ink composition.

[0003] Solid foods such as candies and confectioneries, and solid pharmaceutical preparations such as tablets, caplets, and capsules, are usually printed with symbols, letters, and / or patterns on their surfaces for product identification, etc. In particular, printing on solid pharmaceutical preparations is widely used as a means of conveying various information, such as product names, code numbers, and company names (e.g., their logos).

[0004] Conventionally, printing on these solid foods and solid pharmaceutical preparations has generally been carried out using edible printing inks in which pigments such as titanium oxide, ferric oxide, and aluminum lake food coloring are mixed or dispersed in a vehicle in which shellac is dissolved in an alcohol-based organic solvent (Patent Documents 1 and 2).

[0005] Shellac is a harmless thermosetting resin produced by the lac insect, and is used in many countries as a binder for edible inks because it adheres to the surface to which it is applied.

[0006] To make edible ink compositions white, water-insoluble calcium salts such as calcium phosphate and calcium carbonate, and white pigments such as titanium oxide are used, and titanium oxide has a high refractive index and excellent hiding power and coloring power, so it is widely used not only as a white pigment but also in combination with colorants of colors other than white.

[0007] However, in the European Union (EU), titanium dioxide was designated as a "carcinogen category 2" in 2020, and its use will be banned in the European food market from 2022. (https: / / www.jetro.go.jp / biznews / 2022 / 08 / 817e100825b5eb14.html)

[0008] Furthermore, the EU is expected to ban the use of titanium oxide in pharmaceuticals by around 2025. Therefore, there is an urgent need for the development of an edible white ink composition that does not contain titanium oxide in the food and pharmaceutical fields.

[0009] As an example of replacing titanium oxide with other materials in the field of edible inks, Patent Document 3 describes an edible ink containing a yellow oil-based natural pigment material, characterized in that the ink is a blend of 10 to 15% by weight of the oil-based natural pigment material, 15 to 40% by weight of edible oil or fat as a vehicle, and 50 to 70% by weight of eggshell calcium. The main component of the eggshell calcium is calcium carbonate.

[0010] Patent Document 4 describes an edible screen printing ink composition containing water, alcohols, stabilizers, sugars and / or surfactants, and an edible, water-insoluble inorganic fine powder with hiding power. Examples of water-insoluble white inorganic fine powders used in the ink include inorganic calcium salts, titanium oxide, magnesium carbonate, and shell powder. The stabilizers used in this ink composition include a thickener and, if necessary, a resin and an edible polymeric substance. These stabilizers are water-soluble and act as binders or property-improving aids in the ink, allowing the composition of the invention to exhibit the necessary properties as a screen printing ink. However, because this ink composition contains water as a solvent, it dries slowly and is not suitable for high-speed offset printing.

[0011] Patent Document 5 describes an edible ink formulation comprising a solvent, a binder, and scalenohedral calcium carbonate particles, wherein the solvent comprises one or more C2 to C6 alcohols selected from the group consisting of isopropanol, 1-propanol, ethanol, 1-butanol, 3-methyl-1-butanol, 2-butanol, hexanol, and combinations thereof, and wherein the scalenohedral calcium carbonate particles are present in an amount of about 15% to about 35% by weight, and wherein when prepared as a dry film, the ink formulation exhibits a reflectance of about 30% to about 75% over a wavelength range of about 440 nm to about 700 nm, and when the dry film is prepared from a wet film having a thickness of about 13 μm or less, the ink formulation exhibits a lightness L* value of at least about 40 under CIE standard illuminant D65. Also, Patent Document 6 describes an edible ink formulation containing scalenohedral calcium carbonate particles, alcohol, and an aqueous solvent, which has a print durability score of less than 70 when applied as a film. These documents relate to edible inks that use scalenohedral calcium carbonate particles as a white pigment to replace titanium oxide, and do not disclose other white pigments.

[0012] Patent Document 7 describes an ink composition containing a polymer and a coloring component that can be incorporated into edible materials, as well as a solvent or dispersion medium, and lists examples of the polymer such as hydroxypropyl cellulose, polyvinylpyrrolidone, hydroxypropyl methylcellulose, etc., examples of the coloring component such as calcium carbonate, magnesium carbonate, magnesium oxide, magnesium stearate, calcium stearate, etc., and examples of the solvent such as one or more solvents selected from water, ethanol, and acetone. However, this ink composition is for forming a transfer layer in a laser transfer film, and is not related to offset printing ink.

[0013] Patent Document 8 describes an inkjet printer ink containing a resin and a pigment, the resin being 15 to 50 parts by weight per 1 part by weight of the pigment, the resin including shellac, the pigment including a charcoal powder dye, and the pigment being 0.05 to 0.7% by weight, the ink having a pencil hardness of 2B to 4H after drying, and a reflection density of 0.1 to 0.3, and examples of other pigments include titanium oxide and calcium carbonate. Patent Document 9 describes a printed tablet having a surface printed with dots, the print consisting of a dried coating of inkjet ink containing, as essential ingredients, a dye, hydroxypropyl cellulose having a molecular weight of 10,000 to 150,000, ethanol, and a solvent including water, and each printed dot having a concave shape, and examples of the dye include titanium oxide. These documents do not disclose any white pigments other than titanium oxide and calcium carbonate, and all of them are specialized for ink compositions for inkjet printers and cannot be used for offset printing.

[0014] Japanese Patent Publication No. 47-31706 Japanese Patent Publication No. 2020-29537 Japanese Patent Publication No. 8-308533 Japanese Patent Publication No. 63-63363 U.S. Patent Publication No. 2023 / 0217950 U.S. Patent Publication No. 2021 / 259275 Japanese Patent Publication No. 2015-091647 Japanese Patent Publication No. 2014-240386 Japanese Patent Publication No. 2015-218144

[0015] A first object of the present invention is to provide an edible ink composition that is suitable for printing on the surfaces of solid foods and solid pharmaceutical preparations and that does not have the carcinogenicity problem associated with titanium oxide. A second object of the present invention is to provide a fast-drying edible ink composition that is compatible with high-speed printing by offset printing.

[0016] The present inventors conducted extensive research to find a new edible colorant that can be used in white inks to replace titanium oxide, and as a result, discovered that printing inks containing magnesium carbonate as a whitening agent enable printing with clear identifiable features. Magnesium carbonate has traditionally been used as a pharmaceutical additive in oral and topical medications, and is also a chemical substance used in various foods to supplement or fortify the essential mineral magnesium. Therefore, it can be safely used as a whitening agent, particularly as a white pigment, in edible ink compositions.

[0017] Furthermore, the present inventors have discovered that, similar to magnesium carbonate, a group of whitening agents, namely, magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, carnauba wax, tricalcium phosphate, dolomite, bentonite, agar, and activated clay, can also produce prints with clear distinctiveness. The present inventors have also discovered that by using an alcohol-soluble film-forming polymer as the alcohol-soluble binder in an edible ink composition containing these whitening agents and using alcohol as the ink solvent, an ink composition with a fast drying speed suitable for offset printing can be prepared. These edible ink compositions enable high-speed offset printing on the surfaces of solid pharmaceutical formulations and solid foods.

[0018] The edible ink composition of the present invention contains a binder and a solvent in addition to the white pigment described above, and can further contain optional additives such as a humectant (drying speed regulator), a dispersant, etc. Even in the presence of these additives, the composition can sufficiently achieve its purpose as an ink for offset printing.

[0019] (Definitions) As used herein, the term "edible ink composition" refers to a liquid composition containing a white pigment, a binder, a solvent, and optional additives, all of which are edible. The edible ink composition may also be referred to herein as an "ink composition" or simply as "ink." The solid remaining after drying of the edible ink composition, i.e., after the volatile components have evaporated, is generally referred to herein as "dry edible ink" or simply "dry ink." Unless otherwise specified, "wt. %" herein refers to the percentage of the contained components relative to the weight of the edible ink composition (i.e., wet ink). Unless otherwise specified, the unit "um" is the same as the unit "μm," meaning "micrometer." As used herein, "room temperature" refers to 20 to 25°C. Regarding propane-1,2,3-triol, the three common names glycerol, glycerine, and glycerin are all used synonymously herein.

[0020] The present invention was completed based on the above findings and includes the following aspects. Aspect [1] An edible ink composition for use in offset printing, comprising a whitening agent, an alcohol-soluble binder, and a solvent, wherein the edible ink composition does not contain titanium oxide, the whitening agent is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, carnauba wax, tricalcium phosphate, dolomite, bentonite, agar, activated clay, and mixtures thereof, the alcohol-soluble binder is hydroxypropyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, or mixtures thereof, and the solvent is alcohol. Aspect [2] The edible ink composition of Aspect [1], wherein the whitening agent is magnesium carbonate, a white pigment. Aspect [3] The edible ink composition according to Aspect [1] or [2], wherein the amount of whitening agent in the dried ink after drying of the edible ink composition is 30 to 90 wt %, preferably 50 to 80 wt %, relative to the dry weight of the edible ink composition. Aspect [4] The edible ink composition according to any of Aspects [1] to [3], wherein the solids content of the edible ink composition relative to the weight of the edible ink composition is 10 to 90 wt %, preferably 20 to 50 wt %. Aspect [5] The edible ink composition according to any of Aspects [1] to [4], wherein the solvent volatilizes or evaporates as the edible ink composition dries, and essentially does not remain in the edible ink after drying. Aspect [6] The edible ink composition according to any of Aspects [1] to [5], wherein the alcohol solvent is selected from the group consisting of ethanol, propanol, isopropanol, and butanol, and preferably the solvent is ethanol or butanol, and even more preferably ethanol. Aspect [7] The edible ink composition according to any one of Aspects [1] to [6], further comprising a colorant having a color other than white as a component.Aspect [8] The edible ink composition according to any one of Aspects [1] to [7], further comprising an additive selected from the group consisting of sorbitol, glycerin, propylene glycol, sucrose, glucose, galactose, fructose, xylitol, maltose, maltitol, trehalose, lactose, alcohol-soluble oligosaccharides, cationic or anionic surfactants, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, and nonionic surfactants such as sucrose fatty acid esters, polycarboxylic acid-type polymer dispersants, phosphates such as polyphosphates and hexametaphosphates, clay minerals having a zeta potential, such as kaolin, halloysite, montmorillonite, and allophane, and silicic anhydride, and / or combinations thereof. Aspect [9] A printing substrate offset-printed with the edible ink composition according to any one of Aspects [1] to [8], wherein the printing substrate is preferably a solid food or a solid pharmaceutical preparation, and the solid pharmaceutical preparation is preferably a hard capsule, a soft capsule, a tablet, or a caplet. Aspect

[10] A method for producing the edible ink composition according to any one of Aspects [1] to [8], comprising the step of mixing the whitening agent, binder, solvent, and optional further component that are components of the edible ink composition, thereby providing the edible ink composition. Aspect

[11] A printing method comprising the step of offset-printing the edible ink composition according to any one of Aspects [1] to [8] onto a printing substrate.

[0021] The components of the edible ink composition of the present invention will be described in more detail below.

[0022] (Whitening Agent) In the present invention, magnesium carbonate can be used as a whitening agent, i.e., a white pigment. Magnesium carbonate includes basic magnesium carbonate, heavy magnesium carbonate, and light magnesium carbonate. A precipitate formed by adding sodium carbonate or potassium carbonate to an aqueous magnesium salt solution is called basic magnesium carbonate (mMgCO3-Mg(OH)2-nH2O), which is often referred to as magnesium carbonate. The composition ratio of basic magnesium carbonate varies depending on the manufacturing method, with MgCO3 to Mg(OH)2 being 3-5, i.e., m being 3-5, and H2O being 3-7, i.e., n being 3-7. Heavy magnesium carbonate is a pentahydrate with a molar mass of 485.65 g / mol. Light magnesium carbonate is a tetrahydrate, and is called light because it is lighter in composition than heavy magnesium carbonate. Its molar mass is 467.64 g / mol.

[0023] The more strongly the particles reflect light, the whiter the ink becomes, and this reflectance can be characterized by the refractive index. Whitening agents, especially white pigments, are preferably substances with a refractive index close to that of titanium dioxide (2.3-2.8, depending on the crystal system). Magnesium carbonate has a refractive index of 1.52-1.63, making it one of the highest among white pigments suitable for use in food and pharmaceutical applications.

[0024] The desirable particle size of the pigment is 0.1 μm to 30 μm, preferably 0.1 μm to 20 μm, and more preferably 0.1 μm to 10 μm, from the viewpoint of preventing clogging of the fine logo engraved on the offset roll of the printing press and increasing the amount of light reflection. From the viewpoint of particle shape that enhances light reflection, flat particles with a high aspect ratio have superior whiteness to block or spherical particles that scatter reflected light.

[0025] Furthermore, the present inventors have discovered other compounds that have a strong white color and can be used as suitable whitening agents in addition to magnesium carbonate. These include magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium (calcium oxide; CaO), calcium stearate, tricalcium phosphate (Ca3(PO4)2), dolomite (a double salt of CaCO3 and MgCO3 in a 1:1 molar ratio), carnauba wax, bentonite, agar, and activated clay. Calcined calcium refers to calcium oxide. It is produced by washing and crushing shells, then calcining them at a high temperature of 1000°C or higher for a long period of time, and then grinding them into fine particles. It can also be obtained by calcining CaCO3 or Ca(OH)2. These whitening agents can be used alone or in combination. Therefore, the whitening agent is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, carnauba wax, tricalcium phosphate, dolomite, bentonite, agar, activated clay, and mixtures thereof. Preferably, the whitening agent is a white pigment and is magnesium carbonate.

[0026] In addition to these whitening agents, the edible ink composition of the present invention can also contain an edible white pigment other than titanium oxide (e.g., magnesium oxide; MgO) that is edible and can impart sufficient whiteness to the ink. Thus, a further embodiment of the whitening agent is a combination of magnesium carbonate and magnesium oxide.

[0027] The particle size of the white pigment used in the present invention can be measured by laser diffraction at a detection wavelength of 650 nm and an emission wavelength of 405 nm. Preferably, the measurement is carried out using an aqueous dispersion of the white pigment. The measurement is preferably carried out at 24°C. The measurement of the particle size distribution is carried out as follows. The following is an explanation using the example of magnesium oxide as a white pigment, but a person skilled in the art can apply this procedure to any of the whitening agents of the present invention.

[0028] Preparation of magnesium oxide aqueous dispersion: Measurement samples were prepared by adding an appropriate amount of magnesium oxide to an aqueous solution of sodium hexametaphosphate (0.2 wt%) (Wako Pure Chemical Industries, Ltd.) and dispersing the solution in an external ultrasonic bath. The dispersion was then placed in a particle size distribution analyzer, and the particle size distribution was measured while ultrasonically treating the sample using the ultrasonic devices built into the particle size distribution analyzer. Measurement equipment: Laser diffraction / scattering particle size distribution analyzer Partica LA-960V2 (Horiba, Ltd.) Measurement unit: Wet Measurement temperature: Room temperature Light source: LD (laser diode, 650 nm) and LED (light-emitting diode, 405 nm) Particle size standard: Volume Particle refractive index: 1.76 (real part), 0.00 (imaginary part) Solvent: 0.2 wt% aqueous solution of sodium hexametaphosphate Solvent refractive index: 1.333

[0029] In one embodiment, the edible ink composition does not include the white colorant titanium oxide (TiO2). In one embodiment, the edible ink composition does not include TiO2. In one embodiment, the edible ink composition does not include the white colorant calcium carbonate (CaCO3). In one embodiment, the edible ink composition does not include CaCO3. In one embodiment, the edible ink composition does not include the white colorant TiO2, nor does it include the white colorant CaCO3. In one embodiment, the edible ink composition does not include TiO2, nor does it include CaCO3. In one embodiment, the edible ink composition does not include the white colorant calcium oxide (CaO). In one embodiment, the edible ink composition does not include CaO. In one embodiment, the edible ink composition does not include the white colorant TiO2, nor does it include the white colorant CaO. In one embodiment, the edible ink composition does not include TiO2, nor does it include CaO. In one embodiment, the edible ink composition does not include any white colorant (also referred to as a white colorant) other than the whitening agent of the present invention and MgO. In one embodiment, the edible ink composition does not include any white colorant (also referred to as a white colorant) other than the whitening agent of the present invention.

[0030] (Alcohol-Soluble Binder) The alcohol-soluble binder, also referred to herein as "binder," is an edible film-forming polymer that is soluble in alcohol. Examples of binders include hydroxypropyl cellulose (HPC), polyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), hydroxyethyl cellulose (HEC), or a mixture thereof. Preferably, the binder is hydroxypropyl cellulose (HPC), polyvinylpyrrolidone (PVP), or a mixture thereof. From the standpoint of print quality, the preferred film-forming polymer is hydroxypropyl cellulose. Hydroxypropyl cellulose is a nonionic cellulose ether obtained by treating naturally occurring cellulose (pulp) with sodium hydroxide and then reacting it with an etherifying agent such as propylene oxide. It is used as a pharmaceutical additive, such as a lubricant, coating agent, disintegrant, and binder for tablets, caplets, and granules. Polyvinylpyrrolidone is also used as a coating agent for pharmaceutical tablets in the European Union (EU) and in the pharmaceutical field in Japan. Therefore, when these are used as binders for edible inks, no safety issues arise.

[0031] (Solvent) The solvent essentially volatilizes or evaporates as the edible ink composition dries, and does not remain in the dried ink after the edible ink composition has dried, particularly after the edible ink composition has been printed. In the present invention, an alcohol is used as the solvent to make the edible ink composition quick-drying. Adding a large amount of alcohol to the edible ink composition reduces the solids concentration, thereby increasing the drying speed of the edible ink composition. The alcohol is preferably selected from the group consisting of ethanol, propanol, isopropanol, and butanol, and more preferably the solvent is ethanol or butanol, and even more preferably ethanol.

[0032] Offset printing is performed at higher speeds than screen printing; for example, the printing speed on hard capsules can reach 300,000 units per hour. Therefore, the ink composition used in offset printing requires a drying time that is significantly shorter than that of screen printing ink. Specifically, the ink is required to dry within 5 seconds after printing. Since the vapor pressure of alcohol is much higher than the vapor pressure of water, the ink composition of the present invention dries quickly, which is advantageous for use in high-speed offset printing.

[0033] The edible ink composition of the present invention may contain one or more of the following additional components. (Humectant) The drying speed of an edible ink composition is affected by environmental humidity. When the air is dry, the edible ink composition begins to dry on the printing plate and blanket, which can cause ink smearing defects in the printed result. To prevent this and adjust the drying speed of the edible ink composition, a humectant can be added to the edible ink composition as an additional component. Examples of humectants that can be used include sorbitol, glycerin, propylene glycol, sucrose, glucose, galactose, fructose, xylitol, maltose, maltitol, trehalose, lactose, and alcohol-soluble oligosaccharides. The amount of humectant added is adjusted while observing the printed results. Typical amounts of humectants added are 0 to 3 wt % for sugars and 0 to 20 wt % for other humectants. The weight percentages are based on the weight of the edible ink composition.

[0034] (Dispersant) In the edible ink composition, a dispersant may be added as an additional component to stably disperse the pigment in the binder solution. Examples of dispersants include charged cationic or anionic surfactants, nonionic surfactants such as glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters, polycarboxylic acid-type polymer dispersants, phosphates such as polyphosphates and hexametaphosphates, and zeta-type clay minerals such as kaolin, halloysite, montmorillonite, and allophane. Dispersion stabilization can be achieved using thixotropants such as silicic anhydride. These dispersants can also be used in combination. The amount of dispersant added is 0 to 10 wt %. The weight percentage is based on the weight of the edible ink composition.

[0035] (Coloring Agent) If a color other than white is required, a coloring agent other than white can be added to the edible ink composition in the required amount, or a portion of the white pigment of the present invention can be replaced. Usable coloring agents include pigments and dyes known to those skilled in the art that are suitable as components of edible compositions. Usable coloring agents include insoluble coloring pigments such as aluminum lake tar-based dyes, yellow ferric oxide, red ferric oxide, black ferric oxide, and carbon black, as well as alcohol-soluble or uniformly dispersible dyes such as squid ink.

[0036] The edible ink composition may contain one or more additives used in conventional printing inks, such as a plasticizer, an adhesion promoter, an ink glossing agent, and a flavoring, as additional components, and preferably all of the additional components are edible additives. Even in the presence of these additives, the ink composition can still fully serve as an edible printing ink.

[0037] (Weight Ratio of Components) The preferred amount of solvent in the edible ink composition is 20 to 89 wt %, more preferably 60 to 80 wt %, based on the weight of the edible ink composition. The preferred amount of binder in the edible ink composition is 1 to 60 wt %, more preferably 2 to 20 wt %, and even more preferably 3 to 10 wt %, based on the weight of the edible ink composition. The typical amount of whitening agent (such as magnesium carbonate) in the edible ink composition is 10 to 60 wt %, more preferably 12 to 40 wt %, and even more preferably 15 to 30 wt %, based on the weight of the edible ink composition. The preferred range for the weight ratio of pigment to binder (pigment / binder) in the edible ink composition is 1 to 10.

[0038] Preferably, the amount of whitening agent (such as magnesium carbonate) in the dried ink after drying of the edible ink composition is 30 to 90 wt %, preferably 50 to 80 wt %, based on the weight of the ink after drying. The solids content of the edible ink composition, i.e., the weight of the ink after drying of the edible ink composition, is preferably 10 to 90 wt %, more preferably 20 to 50 wt %, of the weight of the edible ink composition. The preferred total amount of additional components in the edible ink composition is 0 to 25%, preferably 0 to 10%, or even only 0 to 5%. A typical amount is 0 to 10%. The percentages represent weight % based on the weight of the edible ink composition.

[0039] The preferred blend ratios of the binder, solvent, whitening agent (such as magnesium carbonate), optional humectant, and optional dispersant in the edible ink composition of the present invention are as follows: Whitening agent: 10 to 60 wt % Binder: 1 to 60 wt % Solvent: 20 to 89 wt % Humectant: 0 to 25 wt % Dispersant: 0 to 10 wt % The above weight percentages are based on the weight of the edible ink composition.

[0040] (Method for producing an edible ink composition) A further subject of the present invention is a method for producing an edible ink composition, in particular an edible ink composition for offset printing, which method comprises the step of mixing a whitening agent (such as magnesium carbonate), a binder, a solvent, and any further ingredients that will be components of the edible ink composition, thereby providing an edible ink composition. The mixing of the ingredients can be carried out in any order. Depending on the properties of the whitening agent, in particular in the case of a white pigment, the method may also comprise the step of dispersing the whitening agent in a solvent.

[0041] In one embodiment, a method for producing an edible ink composition includes the following steps: (i) dissolving a binder in a solvent, (ii) adding a whitening agent, particularly a white pigment, to the binder solution provided by step (i), and (iii) dispersing the whitening agent, particularly a white pigment, in the binder solution.

[0042] (Printing Method) Another subject of the present invention is a printing method comprising a step of performing offset printing on a printing substrate using an edible ink composition. Offset printing is suitable as a method for printing on a printing substrate such as a solid food product or a solid pharmaceutical preparation using an edible ink composition containing a white pigment according to the present invention. For example, printing on capsules can be performed using an offset printing machine using the edible ink composition of the present invention as is, or after further diluting it with a solvent as necessary to adjust, for example, the final viscosity.

[0043] (Printed Object) Another subject of the present invention is a printing substrate offset-printed with an edible ink composition. The printing substrate is a solid food or a solid pharmaceutical preparation, and the solid pharmaceutical preparation is preferably a hard capsule, a soft capsule, a tablet, or a caplet. When the capsule is a hard capsule, the capsule base may be any known substance usable in pharmaceuticals and health foods, such as gelatin, pullulan, hydroxypropyl methylcellulose (HPMC), cellulose acetate phthalate (CAP), hypromellose acetate succinate (HPMCAS), hydroxypropyl methylcellulose phthalate (HPMCP), cellulose-based polymers such as acrylate ethyl methyl methacrylate copolymer, polyvinyl alcohol (PVA), starch-based materials, and combinations of these capsule bases, with HPMC capsules, gelatin capsules, and pullulan capsules being preferred. The capsule may be banded or sealed. The capsule shell may also be colored with known dyes, preferably natural dyes. The surface of solid foods such as confectioneries and candies can also serve as a printing substrate for the edible ink composition of the present invention.

[0044] By offset printing a printing substrate such as a tablet, capsule, or caplet using the edible ink composition containing the whitening agent of the present invention, clear white prints can be obtained at high speed. Furthermore, by adding a colorant of a color other than white to the edible ink composition, color prints can be obtained. These prints have good peel resistance and other properties. Imprints on printing substrates formed with the edible ink composition containing the whitening agent of the present invention, and printed substrates such as capsules printed with the edible ink composition containing the whitening agent of the present invention, are stable over time and in the presence of light. Furthermore, the printed capsules comply with the properties, quality, and characteristics of capsules, i.e., appearance, properties, and purity tests, as specified in the Japanese Pharmacopoeia, and can be used for pharmaceutical or food purposes in the same way as conventional capsules.

[0045] The present invention will be described in detail below based on examples, but it goes without saying that the present invention is not limited to these examples.

[0046] Ink Film Formation Test Samples of edible ink compositions having compositions shown in Table 1 in weight percent based on the weight of the edible ink composition were prepared.

[0047]

[0048] (Preparation of Edible Ink Composition) HPC (Nippon Soda, product name: Cerny SSL) and PVP (BASF: PVP90) were used as binders for the edible ink composition.

[0049] The following whitening agents were used: Basic magnesium carbonate (Kanto Chemical), heavy magnesium carbonate (Konoshima Chemical), light magnesium carbonate (Konoshima Chemical), magnesium sulfate (Kanto Chemical), magnesium hydroxide (Konoshima Chemical), magnesium chloride (Kanto Chemical), magnesium phosphate (Budenheim), magnesium stearate (Nitto Chemical), calcium carbonate (Kanto Chemical), calcium hydroxide (Kanto Chemical), tricalcium phosphate (Kanto Chemical), calcium hydrogen phosphate (Kyowa Chemical), calcined calcium (CaO, NC Corporation), calcium citrate (Fuso Chemical), calcium stearate (Nitto Chemical), calcium pantothenate (DSM), calcium gluconate (Fuso Chemical), potassium aluminum sulfate (Kosakai Chemical), anhydrous sodium sulfate (Takasugi Pharmaceutical), sodium alginate (Kimica), sodium pyrophosphate (Taihei Chemical), cluster dextrin (Glyco Nutrition Foods), cyclodextrin (Nihon Shokuhin Kako), pregelatinized starch (Asahi Kasei Chemicals), Xylitol (Xlear), glucose (Nihon Shokuhin Kako), gelatin powder (Lucero), gum arabic (Sanei Pharmaceutical Trading), carnauba wax (Freund Corporation), curdlan (Mitsubishi Corporation Life Sciences), inulin (Fuji Nippon Seito), L-glutamic acid (Ajinomoto), DL-alanine (Ajinomoto Healthy Supply), anhydrous crystalline maltose (Nagase & Co.), dolomite (Kawai Material), refined bentonite (Hojun), succinoglycan (DSP Gokyo), guar gum (DSP Gokyo), konjac potato extract (Shimizu Chemical), agar (Ina Foods), pectin (Sansho), activated clay (Mizusawa Chemicals)

[0050] HPC and PVP were completely dissolved in ethanol at room temperature to prepare an ethanol solution of the binder. If the pigment particles were large, they were crushed into fine particles using a mill or mortar, and added to the ethanol solution of the binder prepared above, followed by thorough stirring with a spoon until the dispersion was sufficiently uniform.

[0051] (Formation of ink film) Two strips of tape, each 83 μm thick, were attached to a flat glass plate in parallel with a gap between them, a small amount of the ink composition prepared above was placed in the gap between the two stripes, and a round glass rod was used to cross the gap between the two stripes and slide across the surface of the two stripes of tape to bar coat the ink composition. The thickness of the tape acted as a spacer, and a coated film of the ink composition with a uniform thickness was obtained.

[0052] (Results) When ink compositions coated on a glass plate in the form of a film were left in a room at 25°C and 45% RH, all inks dried within 10 minutes. Inks that dry within 10 minutes under these conditions can be determined to be acceptable inks for offset printing. The thickness of dried ink actually obtained by offset printing is approximately 5 μm. When attempting to print at this thickness in a laboratory, the ink dries before printing, making it difficult to evaluate the drying speed. However, empirically, it was confirmed that under the above conditions, i.e., when the ink is applied to a glass plate at a thickness of 83 μm and dries within 10 minutes at 25°C and 45% RH, there are no problems with printing on an offset press.

[0053] Evaluation of ink whiteness Whiteness development test method: An ink composition was prepared using the whitening agent described in Example 1 and HPC and PVP as binders. 3 g of white pigment was added to 7 g of a test base solution (ethanol solution of binder, weight ratio of binder to ethanol = 3.5:66.5), and the mixture was stirred well with a spoon to prepare a test solution (ink composition). The test solution was applied to a glass plate in the same manner as in Example 1. After the applied ink composition was dried at room temperature, the L value was measured using a color meter, model Ci7600, manufactured by X-Rite.

[0054] (Results) The test results are shown in Table 2 below. The higher the L value, the stronger the whiteness. Here, an L value of 70 or more was rated as pass (◯), and an L value of less than 70 was rated as fail (×).

[0055] Table 2 shows the L values ​​and evaluations of the various whitening agents tested. A commercially available titanium oxide-containing white ink, CFWhite (manufactured by San-Ei Gen F.F.I., Inc.), was used for comparison. Among the whitening agents tested, those not listed in Table 2 (magnesium sulfate, magnesium chloride, calcium hydrogen phosphate, calcium citrate, calcium pantothenate, calcium gluconate, potassium aluminum sulfate, anhydrous sodium sulfate, sodium alginate, sodium pyrophosphate, cluster dextrin, cyclodextrin, pregelatinized starch, xylitol, glucose, gelatin powder, gum arabic, curdlan, inulin, L-glutamic acid, DL-alanine, anhydrous crystalline maltose, succinoglycan, guar gum, konjac root extract, and pectin) were all rated "x." Magnesium carbonate exhibited high whiteness regardless of whether the binder was HPC or PVP.

[0056] Preparation of edible ink composition containing magnesium carbonate Using the method of Example 1, an edible ink composition having the composition shown in Table 3 was prepared.

[0057]

[0058] Before adding the whitening agent, additional ingredients were added to the binder and ethanol solution, and ink compositions were prepared in the same manner as in Example 1. Each ink composition was applied to a glass substrate in the same manner as in Example 1, and then left in a room at 25°C and 45% RH. All ink compositions dried within 10 minutes. Note that ink composition 3-1 exhibited a uniform gray color due to the inclusion of squid ink pigment. Ink compositions 3-2 and 3-3 exhibited a uniform white color. The magnesium oxide in ink composition 3-1 was added as part of the white pigment. Magnesium oxide can be used as a white pigment in edible inks.

[0059] Because the edible ink composition of the present invention does not contain titanium oxide, it is possible to achieve high-value-added printing with high health safety, which is a social demand. Furthermore, the whitening agents used in the present invention, i.e., magnesium carbonate, magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, carnauba wax, tricalcium phosphate, dolomite, bentonite, agar, and activated clay, are edible and have good whiteness and hiding power, allowing for clear printing of white and other colors. Furthermore, because the edible ink composition of the present invention uses alcohol as a solvent and an alcohol-soluble binder, it dries quickly and can be used as an ink for offset printing. The edible ink composition of the present invention is useful as an ink composition for offset printing on the surface of solid foods and solid pharmaceutical preparations, particularly capsules, tablets, and caplets, especially capsules.

Claims

1. An edible ink composition for use in offset printing, comprising a whitening agent, an alcohol-soluble binder, and a solvent, wherein the edible ink composition does not contain titanium oxide, the whitening agent is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium stearate, calcium hydroxide, calcined calcium, calcium stearate, carnauba wax, tricalcium phosphate, dolomite, bentonite, agar, activated clay, and mixtures thereof, the alcohol-soluble binder is hydroxypropyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, or a mixture thereof, and the solvent is alcohol.

2. The edible ink composition of claim 1, wherein said whitening agent is magnesium carbonate, a white pigment.

3. An edible ink composition according to claim 1 or 2, wherein the amount of the whitening agent in the dried ink after drying of the edible ink composition is 30 to 90% by weight, preferably 50 to 80% by weight, based on the dry weight of the edible ink composition.

4. The edible ink composition according to any one of claims 1 to 3, wherein the solid content of the edible ink composition is 10 to 90% by weight, preferably 20 to 50% by weight, based on the weight of the edible ink composition.

5. The edible ink composition according to any one of claims 1 to 4, wherein the solvent volatilizes or evaporates as the edible ink composition dries, and does not essentially remain in the edible ink after drying.

6. The edible ink composition according to any one of claims 1 to 5, wherein the solvent alcohol is selected from the group consisting of ethanol, propanol, isopropanol or butanol, preferably the solvent is ethanol or butanol, even more preferably ethanol.

7. The edible ink composition according to any one of claims 1 to 5, further comprising a colorant having a color other than white as a further component.

8. The edible ink composition according to any one of claims 1 to 7, further comprising an additive selected from the group consisting of sorbitol, glycerin, propylene glycol, sucrose, glucose, galactose, fructose, xylitol, maltose, maltitol, trehalose, lactose, alcohol-soluble oligosaccharides, cationic or anionic surfactants, glycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, nonionic surfactants such as sucrose fatty acid esters, polycarboxylic acid type polymer dispersants, phosphates such as polyphosphates and hexametaphosphates, clay minerals having a zeta potential such as kaolin, halloysite, montmorillonite, and allophane, and silicic anhydride, and / or combinations thereof.

9. A printing substrate offset printed with the edible ink composition according to any one of claims 1 to 8, wherein the printing substrate is preferably a solid food product or a solid pharmaceutical preparation, and the solid pharmaceutical preparation is preferably a hard capsule, a soft capsule, a tablet or a caplet.

10. A method for producing an edible ink composition according to any one of claims 1 to 8, comprising the step of mixing the components of the edible ink composition, namely, a whitening agent, a binder, a solvent, and any further optional components, thereby providing an edible ink composition.

11. A printing method comprising a step of offset printing the edible ink composition according to any one of claims 1 to 8 onto a printing substrate.