Edible ink composition containing magnesium oxide

Abstract

To provide an edible ink composition containing no titanium oxide. An edible ink composition that contains magnesium oxide as a whitening agent, contains a binder and a solvent, and does not contain titanium oxide is produced. Since the edible ink composition of the present invention uses magnesium oxide, which has been used safely in the past as a pharmaceutical and poses no problems to health, as a whitening agent in place of titanium oxide, the edible ink composition is useful as a printing ink for the surfaces of solid foods and solid pharmaceutical preparations, especially capsules, tablets, and caplets.

Description

Edible ink composition containing magnesium oxide

[0001] The present invention relates to an edible ink composition. In particular, the present invention relates to an edible ink composition that contains magnesium oxide as a white pigment but does not contain titanium oxide. The present invention also relates to an edible ink composition that is suitable for printing on the surfaces of solid foods and solid pharmaceutical preparations, such as confectioneries, candies, tablets, capsules, etc. Furthermore, the present invention relates to solid foods and solid pharmaceutical preparations (e.g., tablets, caplets, capsules) printed with an edible ink composition containing magnesium oxide.

[0002] 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).

[0003] 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).

[0004] 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.

[0005] Furthermore, water-insoluble white inorganic fine powders that can be used to whiten edible ink compositions include water-insoluble calcium salts such as calcium carbonate and calcium phosphate, titanium oxide, magnesium carbonate, and shell powder (Patent Document 3). Shell powder is primarily composed of calcium carbonate.

[0006] Among these white pigments, titanium dioxide has a high refractive index and offers great hiding power and coloring strength. Therefore, it is widely used not only in white ink but also in combination with colorants of other colors. 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)

[0007] 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.

[0008] An example of replacing titanium oxide with other materials in the field of edible inks is an edible ink formulated with a yellow oil-based natural pigment, characterized by a blend of 10-15 wt% of the oil-based natural pigment, 15-40 wt% of edible oils and fats as a vehicle, and 50-70 wt% of eggshell calcium (Patent Document 4). The main component of eggshell calcium is calcium carbonate. However, no white pigment with the same whiteness and hiding power as titanium oxide, or a white pigment suitable for edible ink, has yet been reported. Furthermore, there are examples of adding magnesium oxide to a coating agent to impart light-blocking properties to the surface of a solid formulation (Patent Documents 5 and 6), but the coating agent is not utilized as an ink composition. Furthermore, Patent Document 7 describes an edible ink containing 10 to 35 parts by weight of an edible colorant, 20 to 85 parts by weight of an edible connecting material, 0 to 1 part by weight of an edible supplement, and 0.5 to 5 parts by weight of an edible nanomaterial, and lists nanoscale titanium oxide, nanoscale magnesium oxide, nanoscale calcium carbonate, etc. as examples of the nanomaterials (also called nanoparticles (particles with a diameter of 100 nm or less)). However, nanoparticle materials can be exposed to the human body via the respiratory tract, digestive tract, skin, and mucous membranes, and are therefore considered to be problematic from the standpoint of safety.

[0009] JP 47-31706 JP 2020-29537 JP 63-63363 JP 8-308533 JP 2003-300872 US Patent Publication 2014 / 0251181 Chinese Patent Publication 102942819

[0010] 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 of titanium oxide. A second object of the present invention is to provide an edible ink composition that has good adhesion to the surface of a printing substrate and good shelf life. A third object of the present invention is to provide an edible ink composition that has good hiding power and coloring power.

[0011] 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, they discovered that printing inks containing magnesium oxide enable printing with clear identifiability. Magnesium oxide is a chemical substance that has traditionally been used in pharmaceuticals as an antacid and laxative, and is also used as a food additive. Therefore, it can be safely used as a white pigment in edible ink compositions. Furthermore, edible ink compositions containing magnesium oxide satisfy the required stability and properties, and can be used for printing on the surfaces of solid pharmaceutical preparations and solid foods.

[0012] The edible ink composition of the present invention contains a binder and a solvent in addition to magnesium oxide, and can further contain plasticizers, humectants, and other additives in the usual manner, and can fully achieve its purpose as a printing ink even in the presence of these additives.

[0013] The present invention was completed based on the above findings and includes the following aspects. [1] An edible ink composition containing magnesium oxide, a binder, and a solvent, wherein the magnesium oxide is produced at a baking temperature of at least 700°C and does not contain titanium oxide. [2] The edible ink composition according to [1], wherein the magnesium oxide is produced at a baking temperature of at least 800°C. [3] The edible ink composition according to [1] or [2], wherein the magnesium oxide has a D90 value of 20 μm or less. [4] The edible ink composition according to any one of [1] to [3], wherein the magnesium oxide has a particle size distribution with a D90 value of 1 to 15 μm. [5] The edible ink composition according to any one of [1] to [4], wherein the magnesium oxide has a particle size distribution with a D10 value of 0.1 μm or more. [6] The edible ink composition according to any one of [1] to [5], wherein the amount of magnesium oxide in the ink after drying of the edible ink composition is 99% by mass or less, preferably 60 to 99% by mass, relative to the weight of the ink after drying of the edible ink composition. [7] The edible ink composition according to any one of [1] to [6], wherein the solids content of the edible ink composition relative to the weight of the edible ink composition is 65% by mass or less, preferably 20 to 65% by mass. [8] The edible ink composition according to any one of [1] to [7], wherein the solvent volatilizes or evaporates after drying of the edible ink composition and does not essentially remain in the ink. [9] The edible ink composition according to any one of [1] to [8], wherein the solvent is alcohol or a mixture of alcohol and water, preferably the alcohol is ethanol, propanol, or butanol, more preferably ethanol or butanol, and even more preferably the alcohol is ethanol.

[10] The binder is preferably an edible film-forming non-thermosetting polymer or shellac, the binder is soluble in alcohol, and when the binder is a non-thermosetting polymer, the binder is hydroxypropyl cellulose, polyvinylpyrrolidone, or a mixture thereof; or the edible ink composition according to any one of [1] to [9].

[11] The edible ink composition according to any one of [1] to

[10] , which contains a moisture-proof coating agent.

[12] The edible ink composition according to

[11] , wherein the moisture-proof coating agent is a higher fatty acid ester that is soluble or miscible in alcohol but insoluble in water, an alcohol having 16 or more carbon atoms, a fatty acid having 12 or more carbon atoms, a glyceride, or a mixture thereof, or a surfactant with an HLB of 6 or less.

[13] The edible ink composition according to

[11] or

[12] , wherein the moisture-proof coating agent is stearic acid, beeswax such as white beeswax, resin such as rosin, Japan wax, spermaceti, lanolin, lanolin alcohol, cetyl alcohol, stearyl alcohol, cetanol / polyethylene glycol monostearate mixed wax, cetanol / polysorbate 60 mixed wax, cetostearyl alcohol, isopropyl myristate, isopropyl linoleate, isopropyl palmitate, oleic acid, or a vegetable oil such as olive oil or castor oil.

[14] The edible ink composition according to any one of

[11] to

[13] , wherein the amount of the moisture-proof coating agent added is 0.1 to 20%, preferably 0.1 to 10%, based on the total weight of the magnesium oxide and the binder.

[15] The edible ink composition according to any one of [1] to

[14] , further comprising a colorant having a color other than white.

[16] The edible ink composition comprises one or more additives commonly used in printing inks, such as a drying speed regulator, a plasticizer, a humectant, an adhesion promoter, an ink gloss agent, a thixotropy-imparting agent, or a fragrance, and the additives are glycerin, triethyl citrate (TEC), triacetin, ethylene glycol, propylene glycol, a resin, a wax, a polyglycerin fatty acid ester, a glycerin fatty acid ester, a sucrose fatty acid ester, a sorbitan fatty acid ester, lecithin, an enzymatically decomposed lecithin, a polysorbate, or silicon dioxide (SiO). ２

[17] A printing substrate printed with the edible ink composition according to any one of [1] to

[16] , 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.

[18] A method for producing an edible ink composition, the method comprising a step of mixing magnesium oxide, a binder, a solvent, and optional additives, which are components of the edible ink composition, to provide the edible ink composition according to any one of [1] to

[16] and an edible ink composition containing the components thereof.

[19] A method for printing an edible ink composition onto a printing substrate, using the edible ink composition according to any one of [1] to

[16] and a printing substrate.

[0014] The components of the edible ink composition of the present invention will be described in more detail below.

[0015] (Magnesium oxide, MgO) In the present invention, heavy magnesium oxide is used as the white pigment for the edible ink. Heavy magnesium oxide is industrially produced by thermal decomposition of magnesium carbonate or magnesium hydroxide. Magnesium oxide calcined at a calcination temperature of 600°C to 900°C during production is called "caustic calcined magnesia" or "light-burned magnesia," and has higher chemical reactivity than so-called hard-burned magnesium produced at a calcination temperature of 1000°C to 1500°C.

[0016] The inventors initially developed an edible ink composition using magnesium oxide baked at 600°C. However, when this magnesium oxide was dispersed in a solvent with a binder, the viscosity of the edible ink composition increased over time, eventually solidifying and rendering it unusable. It is speculated that when lightly baked magnesium (baked at 600°C) was used, it reacted with even a small amount of moisture to convert to magnesium hydroxide over time, causing the particles to coalesce and form clumps. However, by switching to magnesium oxide baked at temperatures above 600°C, the inventors surprisingly found that this phenomenon was suppressed, enabling the production of an ink with excellent stability over time. The magnesium oxide used in the present invention is preferably produced at a bake temperature of 700°C or higher, preferably 800°C or higher, more preferably 900°C or higher, and even more preferably 925°C. In specific embodiments, the bake temperatures are 950°C and 1300°C.

[0017] Preferably, the magnesium oxide content of the edible ink composition is 65% by weight or less, preferably 20 to 65% by weight, more preferably 20 to 50% by weight, based on the weight of the edible ink composition.

[0018] Preferably, the edible ink composition does not contain nanoparticles. Preferably, the ink obtained after drying of the edible ink composition does not contain nanoparticles. More preferably, the edible ink composition does not contain nanoparticles, and the ink obtained after drying of the edible ink composition does not contain nanoparticles.

[0019] The magnesium oxide used in the present invention has a particle size suitable for ink application. The particle size distribution of magnesium oxide can be characterized by the D10 and / or D90 values. The D10 / D90 value indicates that 10% / 90% of the particles have a particle size smaller than the D10 / D90 value. Within the meaning of the present invention, the % units of any D10 / D90 value refer to cumulative volume percentages. In one embodiment, the magnesium oxide has a particle size distribution with a D10 value of 2 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less. The magnesium oxide has a particle size distribution with a D90 value of 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, particularly 2 μm or less, more particularly 1.5 μm or less, and even more particularly 0.8 μm or less.

[0020] The magnesium oxide used in the present invention may have a maximum particle size of 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, particularly 2 μm or less, more particularly 1.5 μm or less, and even more particularly 0.8 μm or less.

[0021] The larger the size of the magnesium particles, the more difficult it is to keep them suspended without settling. Settled magnesium particles tend to roughen the surface of printed matter, causing inconsistencies in print quality and impairing print quality. For example, if the D90 value of the particle size distribution exceeds 20 μm, magnesium oxide is more likely to precipitate in the edible ink composition. From the perspective of product value, it is preferable to exclude nanoparticles for health reasons. Therefore, in one embodiment, the magnesium oxide has a particle size distribution with a D10 value of 0.1 μm or more, or a minimum particle size of 0.1 μm or more. Therefore, the magnesium oxide preferably has a particle size distribution with a D10 value of 0.1 to 2 μm, more preferably 0.1 to 1.5 μm, and even more preferably 0.1 to 1.0 μm. In particular, the magnesium oxide has a particle size distribution with a D10 value of 2 μm or less and a minimum particle size of 0.1 μm. More particularly, the magnesium oxide has a D10 value of 1.5 μm or less and a minimum particle size of 0.1 μm, or even a D10 value of 1 μm or less and a minimum particle size of 0.1 μm. In another embodiment, the magnesium oxide has a particle size distribution with a D10 value greater than 0.1 μm, or alternatively, a minimum particle size greater than 0.1 μm. Thus, preferably, the magnesium oxide has a particle size distribution with a D10 value of more than 0.1 μm to 2 μm, preferably more than 0.1 μm to 1.5 μm, more preferably more than 0.1 μm to 1 μm. Even more preferably, the magnesium oxide has a particle size distribution with a D10 value of 2 μm or less and a minimum particle size greater than 0.1 μm. In particular, the magnesium oxide has a D10 value of 1.5 μm or less and a minimum particle size greater than 0.1 μm, more particularly, a D10 value of 1 μm or less and a minimum particle size greater than 0.1 μm.

[0022] The particle size and particle size distribution values ​​of magnesium oxide described herein can be measured by laser diffraction at a detection wavelength of 650 nm and an emission wavelength of 405 nm. Preferably, the measurements are performed using an aqueous dispersion of magnesium oxide. The measurements are preferably performed at room temperature. In this specification, the term "room temperature" means 24°C.

[0023] In the present invention, particle size distribution analysis was performed as follows. (Preparation of aqueous magnesium oxide dispersion) An appropriate amount of magnesium oxide sample was placed in an aqueous solution of sodium hexametaphosphate (0.2 wt %, manufactured by Wako Pure Chemical Industries, Ltd.) and dispersed in an ultrasonic bath. Next, the dispersion was placed in a particle size distribution analyzer, and the particle size distribution was measured while ultrasonically treating the sample using each ultrasonic device built into the particle size distribution analyzer. Measuring device: Laser diffraction / scattering particle size distribution analyzer Partica LA-960V2 (Horiba, Ltd.) Measuring unit: Wet type Measuring 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

[0024] (Binder) Preferably, the binder is an edible film-forming polymer and a non-thermosetting polymer, and the binder is soluble in alcohol. Even more preferably, the binder is hydroxypropyl cellulose (HPC), polyvinylpyrrolidone (PVP), or a mixture thereof. 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, or 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, there are no safety issues when these are used as binders for edible inks. Shellac, an alcohol-soluble edible ink binder, can also be used.

[0025] (Solvent) Preferably, the solvent essentially volatilizes or evaporates and does not remain in the ink after the edible ink composition has dried. Preferably, the solvent is an alcohol or a mixture of alcohol and water, more preferably the alcohol is ethanol, propanol, or butanol, preferably ethanol or butanol. Even more preferably, the alcohol is ethanol. The alcohol and water mixture preferably has an alcohol content of at least 80% by volume, more preferably at least 85% by volume, and even more preferably at least 90% by volume. In an embodiment, the alcohol and water mixture is 99% or 95% by volume of alcohol, such as, for example, 99% or 95% by volume of hydrous ethanol.

[0026] The edible ink composition may be diluted by adding the necessary amount of alcohol or water during the capsule printing process itself. Highly polar solvents such as glycerin, ethylene glycol, and propylene glycol are also compatible with alcohol and can be mixed in appropriate amounts. The higher the carbon number, the lower the vapor pressure of the alcohol, so mixing an appropriate amount can slow the drying speed of the edible ink composition.

[0027] If the edible ink composition dries too quickly, an appropriate amount of glycerin, ethylene glycol, propylene glycol, urea, or any sugar soluble in the solvent, such as sorbitol or fructose, can be added to the composition. By using these methods, the ink concentration and drying speed can be adjusted according to the temperature and humidity of the printing room.

[0028] (Other Additives) The edible ink composition may contain an additional colorant having a color other than white. Magnesium oxide has two effects: whitening and opacifying. Therefore, magnesium oxide acts as both a white colorant and an opacifying agent, and either or both of these effects can be expected. Therefore, when an edible ink composition contains only magnesium oxide as a colorant, the ink becomes opaque and white after drying. Even when a color other than white is desired, either or both of the two effects of magnesium oxide are necessary. The white color of magnesium oxide can further lighten (also known as lightening or brightening) the color of a colorant other than white. Therefore, it acts as both a whitening agent and a lightening or brightening agent. Furthermore, its opacity can contribute to the opacity of a non-white colorant, and if the non-white colorant itself does not have opacity, magnesium oxide may even be the sole source of opacity. Preferably, the colorant contained in the edible ink composition has a color other than white. In one embodiment, the edible ink composition contains titanium oxide (TiO), a white colorant. ２ In one embodiment, the edible ink composition does not contain TiO ２ In one embodiment, the edible ink composition does not contain calcium carbonate (CaCO ), which is a white colorant. ３ In one embodiment, the edible ink composition does not contain CaCO ３ In one embodiment, the edible ink composition does not contain a white colorant, TiO ２ does not contain the white colorant CaCO ３ In one embodiment, the edible ink composition does not contain TiO ２ Does not contain CaCO ３ In one embodiment, the edible ink composition does not include any whitening agent (also called a white colorant) other than magnesium oxide.

[0029] If a color ink other than white is required, a colorant (pigment or dye, or solvent-soluble natural dye or tar dye) such as ferric oxide, aluminum lake, or other food coloring can be added to the edible ink composition in an appropriate amount, or a portion of the magnesium oxide can be replaced with these. Other colorants may be used as long as they are suitable for use in the pharmaceutical or food fields. Examples of such colorants include laked tar dyes, water-soluble tar dyes and natural dyes, caramel, cochineal pigment, lac pigment, riboflavin, sodium iron chlorophyllin, sodium copper chlorophyllin, copper chlorophyll, carbon powder, black iron oxide, and squid ink pigment. To impart pearly luster, an appropriate amount of pearl pigments made from fish scale foil, shellfish nacre or mica, fine powder of silicon dioxide, etc., can be used.

[0030] The magnesium oxide-containing edible ink composition may contain one or more additives typically used in printing inks, such as moisture-proof coating agents, drying speed regulators, plasticizers, humectants, adhesion enhancers, ink gloss enhancers, thixotropy-imparting agents, and flavorings, and preferably all of the additives are edible additives. Even in the presence of these additives, the ink composition can still fully achieve its purpose as an edible printing ink.

[0031] For example, for the purpose of moisture-proof coating, strengthening adhesive strength, glossing the ink, or adjusting the ink hardness, resins or waxes such as rosin that are soluble in this solvent, polyglycerin fatty acid esters, glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, lecithin, enzymatically decomposed lecithin, or polysorbates may be added. In particular, the addition of a moisture-proof coating agent improves ink adhesion and increases reflectance and whiteness. Examples of moisture-proof coating agents that can be used in inks include fatty acid esters that are soluble or miscible in alcohol but not in water, alcohols with 16 or more carbon atoms, fatty acids with 12 or more carbon atoms, glycerides, or mixtures thereof, or surfactants with an HLB of 6 or less. Specific examples of moisture-proof coating agents include stearic acid, beeswax such as white beeswax, resins such as rosin, Japan wax, spermaceti, lanolin, lanolin alcohol, cetanol, stearyl alcohol, cetanol monostearate polyethylene glycol mixed wax, cetanol polysorbate 60 mixed wax, cetostearyl alcohol, isopropyl myristate, isopropyl linoleate, isopropyl palmitate, oleic acid, and vegetable oils such as olive oil and castor oil. Stearic acid and beeswax are particularly preferred examples of moisture-proof coating agents. The amount of moisture-proof coating agent added is 0.1 to 20 wt %, preferably 0.1 to 10 wt %, based on the total weight of magnesium oxide and binder (e.g., HPC or PVP).

[0032] To reduce the hardness of the ink, a plasticizer soluble in the solvent, such as glycerin, triethyl citrate (TEC), or triacetin, may be added. Therefore, additives that can be used include glycerin, triethyl citrate (TEC), triacetin, ethylene glycol, propylene glycol, resin, wax, polyglycerin fatty acid ester, glycerin fatty acid ester, sucrose fatty acid ester, sorbitan fatty acid ester, lecithin, enzymatically decomposed lecithin, polysorbate, silicon dioxide (SiO ２), starch, alcohol-insoluble celluloses, fragrances, and / or combinations thereof. To improve ink adhesion, any polymeric thickener, thickening stabilizer, or adhesive that is soluble in the solvent may be added, such as zein, rosin, or wood rosin glycerin ester.

[0033] (Weight Ratio of Components) The typical amount of solvent in the edible ink composition is 35 to 80 wt %, more preferably 40 to 75.5 wt %, based on the weight of the edible ink composition. The typical amount of binder in the edible ink composition is 0.5 to 25 wt %, more preferably 0.5 to 22.5 wt %, and even more preferably 0.5 to 20 wt %, based on the weight of the edible ink composition. The typical amount of magnesium oxide in the edible ink composition is 10 to 60 wt %, more preferably 15 to 55 wt %, and even more preferably 20 to 50 wt %, based on the weight of the edible ink composition. The typical range of the magnesium oxide / binder weight ratio in the edible ink composition is 1.9 to 105. Preferably, the amount of magnesium oxide in the ink after drying of the edible ink composition is 99 wt % or less, preferably 60 to 99 wt %, based on the weight of the ink after drying of the edible ink composition. The solids content of the edible ink composition, i.e., the weight of the ink after drying of the edible ink composition, is preferably 65 wt % or less, and more preferably 20 to 65 wt % of the weight of the edible ink composition. The typical amount of additives, particularly plasticizers, in the edible ink composition is 0 to 5 wt %, and this wt % is based on the weight of the edible ink composition. The preferred blending ratios of binder, solvent, magnesium oxide, and plasticizer in the edible ink composition are as follows: Binder: 0.5 to 20 wt % MgO: 20 to 50 wt % Evaporative solvent: 40 to 75.5 wt % Plasticizer: 0 to 5 wt % The above wt % are based on the weight of the edible ink composition.

[0034] (Method for Producing an Edible Ink Composition) A further subject of the present invention is a method for producing an edible ink composition, the method comprising mixing the components of the edible ink composition, which may be magnesium oxide, a binder, a solvent, and optional ingredients such as additives, to provide an edible ink composition. This also applies to the edible ink composition and its components as defined herein, and all embodiments thereof. The mixing of the components can be carried out in any order. Depending on the properties of the magnesium oxide, the method may also comprise dispersing the magnesium oxide in a solvent. In one embodiment, the method for producing an edible ink composition comprises the following steps: (i) mixing magnesium oxide with a binder, (ii) adding a solvent to the mixture provided by (i), and (iii) dispersing the magnesium oxide in the solvent.

[0035] (Printing Method) A further subject of the present invention is a method for printing an edible ink composition onto a printing substrate using the edible ink composition and printing substrate defined herein, as well as all embodiments thereof. There are no particular limitations on the method for printing onto a printing substrate such as a solid food product or a solid pharmaceutical preparation using an edible ink containing magnesium oxide, and the method can be carried out according to a conventionally known method. For example, printing onto capsules can be carried out using a gravure / offset printing machine by diluting the printing ink concentrate with the above-mentioned solvent as necessary.

[0036] (Printing Object) Examples of printing substrates include solid foods and solid pharmaceutical preparations such as hard capsules, soft capsules, tablets, and caplets. When the capsules are hard capsules, the capsule base may be any known substance that can be used in pharmaceuticals and health foods, such as gelatin, pullulan, hydroxypropyl methylcellulose (HPMC), hypromellose acetate succinate (HPMCAS), hydroxypropyl methylcellulose phthalate (HPMCP), ethyl acrylate methyl methacrylate copolymer, polyvinyl alcohol (PVA), starch-based materials, and combinations of these capsule bases. HPMC capsules, gelatin capsules, and pullulan capsules are preferred. The capsules may be banded or sealed. They may also be colored with known dyes, preferably natural dyes. The surfaces of solid foods such as confectioneries and candies can also serve as printing substrates for the edible ink composition of the present invention.

[0037] By printing on substrates such as tablets, capsules, and caplets using the magnesium oxide-containing ink, clear white prints can be obtained. Furthermore, by adding a colorant of a color other than white to the edible ink composition, color prints can be obtained. Furthermore, these prints have the same peel resistance as prints obtained with conventional printing inks. Imprints on printing substrates formed with an edible ink composition containing magnesium oxide, and printed substrates such as capsules printed with an edible ink composition containing magnesium oxide, 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.

[0038] (Definitions) For propane-1,2,3-triol, the three common names glycerol, glycerine, and glycerin are all used synonymously herein. The term edible ink composition, as used herein, refers to a liquid composition containing magnesium oxide, a binder, and a solvent. After drying, i.e., after the volatile components of the edible ink composition have evaporated, the remaining solid is generally referred to herein as ink. Unless otherwise specified, the unit "um" is the same as the unit "μm," i.e., means "micrometer."

[0039] 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.

[0040] 1. Magnesium oxide The manufacturing conditions and particle size distribution of the magnesium oxide products (MS-0, MS-1, MS-2F) used in the following examples are as shown in Table 1. MS-0: Heavy magnesium oxide, food additive Tomita Pharmaceutical MS-1: Heavy magnesium oxide, food additive Imported by Japan NER Co., Ltd. MS-2F: Heavy magnesium oxide, food additive A refined version of the imported product by Japan NER Co., Ltd.

[0041]

[0042] 2. Preparation of Edible Ink Compositions Edible ink compositions (Samples 1 to 15) were prepared using the following procedure. 1) The magnesium oxide powder and HPC (Samples 1 to 13, 15) or PVP (Sample 14) were thoroughly mixed in the weight ratios shown in the table, and then placed in a 100 ml homogenizer container. 2) 95% vol. aqueous ethanol (the weight shown in the table) was added to the mixture prepared in step 1 above (room temperature). 3) The mixture prepared in step 2 above was thoroughly mixed with a glass rod. 4) The mixture was homogenized at 6,000 to 8,000 rpm for 5 minutes in a homogenizer (ACE HOMOGENIZER, AM-8) to disperse the magnesium oxide powder. 5) The dispersion procedure in step 4 above was repeated twice. 6) The prepared edible ink compositions were transferred to airtight containers to prevent solvent evaporation and stored at room temperature. Whether HPC or PVP was used as the binder, similar edible white inks were successfully prepared.

[0043]

[0044] 3. Long-term stability of ink A long-term stability test of the edible ink composition was carried out as follows. The prepared edible ink solution was placed in a polypropylene container, the container was closed, and the ink solution was stored at room temperature. After two weeks, the state of the ink solution was observed. ２ A commercially available white ink, CFWhite (San-Ei Gen F.F.I. Co., Ltd.), was used. The edible ink composition (Sample 1) using magnesium oxide (MS-0) produced at a baking temperature of 600°C solidified on the fifth day after the ink was made and became unusable. However, the comparison product and other samples (Samples 2 to 15) showed no abnormalities, particularly no solidification.

[0045]

[0046] 4. Ink Adhesion Strength Test The ink peel strength was measured using the following method. Two strips of tape, approximately 50 μm thick, were attached parallel to a gelatin sheet with a gap of approximately 1 cm between them. These 50 μm tapes served as "spacers" to obtain a 50 μm thick coating of ink. Next, ink was dropped onto the gelatin sheet in the gap between the two tapes, and the ink was quickly bar-coated using a round glass rod while crossing the gap between the two tapes. This resulted in a bar coating of ink approximately 50 μm thick on the gelatin sheet. After 10, 30, 60, 120, 180, 240, and 600 seconds, Nichiban cellophane tape was applied to the bar-coated area and immediately peeled off. The ink peel strength test was evaluated as follows: ∘: The coated ink remained on the gelatin sheet; ×: The coated ink peeled off the gelatin sheet. ∘: Pass; ×: Fail. The test results are shown in Table 4. All inks in Samples 2-15 achieved adhesion and drying speeds equal to or better than the control.

[0047]

[0048] 5. Ink Color Analysis The color difference of the ink was measured as follows: The ink samples and the comparative product (TiO ２ The white ink (CFWhite, manufactured by San-Ei Gen F.F.I. Co., Ltd.) was bar coated using the method described in the above section "4. Ink Adhesion Strength Test." After the ink sample dried, the L value was measured using an X-Rite color meter, model Ci7600, and compared with the L value of a control product to calculate the color difference (ΔL).

[0049] The L value indicates brightness and whiteness, with a higher L value indicating a stronger whiteness. Shellac is used as the binder for CFWhite, which is pale yellow in color, so the ink is also a slightly yellowish white. On the other hand, the white inks of Samples 5 to 15 of the present invention are pure white. Therefore, it is possible to compare only the whiteness using ΔL.

[0050] 6. Adjusting the Drying Speed ​​If the solvent is only aqueous ethanol, the ink evaporates quite quickly on the printer, and depending on the printer used, the edible ink composition may dry before being transferred to the printing substrate, resulting in a decrease in print quality. In such cases, glycerin or both water and glycerin can be added to the edible ink composition to slow down the drying speed. Table 6 shows examples of samples (Samples 16 to 20) whose drying speed was adjusted with glycerin or water and glycerin.

[0051]

[0052] Samples 16 to 20 were evaluated for adhesive strength, color analysis, and long-term stability using the same methods as described above. The results are shown in Table 7. Samples 16 to 20 were evaluated using the same methods as described in sections "4. Ink adhesive strength test," "5. Ink color analysis," and "3. Long-term ink stability." The results are shown in Table 7. The addition of glycerin or glycerin and water did not affect long-term stability or whiteness, but the adhesive strength was rated as "×," meaning the ink composition remained undried, up to 120 or 180 seconds after printing. This indicates that the drying rate of the edible ink composition was slowed down by the addition of glycerin or glycerin and water, as expected.

[0053]

[0054] 7. Moisture-proof edible ink composition Manufacturing method for moisture-proof edible ink composition Ethanol was placed in a container in the weight ratio of the ink composition shown in Table 8, and stearic acid or purified beeswax (these are referred to as wax components) was added. The mixture was heated to 50°C to completely dissolve the wax components. Magnesium oxide was then added and dispersed using a homogenizer at 8000 rpm for 1.5 minutes, after which HPC was added little by little while stirring gently to completely dissolve the mixture. The mixture was further dispersed using a homogenizer at 8000 rpm for 5 minutes to obtain an ink composition.

[0055] The following products were used as components of the moisture-proof edible ink composition containing magnesium oxide: MgO (MS-2F); Nippon NER HPC (Cerny); Nippon Soda stearic acid; NOF refined beeswax; Cerarica NODA

[0056] 8. Whiteness and Adhesion of Moisture-Proof Edible Ink Composition Two strips of tape, approximately 50 μm thick, were attached parallel to a glass substrate, spaced 1 cm apart. Using both strips as spacers, the ink composition prepared above was dispensed onto the glass substrate between the tapes, and a hard rubber squeegee was used to spread the ink quickly between the tapes on the glass substrate. The spacers ensured that the ink band between the strips was approximately 50 μm thick. Because the ink's solids content was approximately 27%, peeling the tape after the ink dried yielded a single ink band approximately 15 μm thick. The L value of the dried ink color was measured using an X-Rite Colorimeter, Model Ci7600, on the same day it dried, and used as the initial value (T = 0 day). The glass substrate with the dried ink was stored at 25°C and 75% RH, and the L value was measured on days 1, 2, 5, 7, 12, and 16. The L value indicates whiteness / brightness. The difference (ΔL) between the L value after storage and the initial value is shown in Table 9.

[0057] Results: The decrease in L value of the dried ink from the ink composition containing stearic acid or beeswax is significantly lower than the decrease in L value of the dried ink without wax (Sample 21), so the whiteness of the dried ink without wax after storage for some time under humid conditions is significantly lower than that of the dried ink with wax. The dried ink from the magnesium oxide-containing ink composition with stearic acid or beeswax also had better adhesion than the one without wax. Furthermore, the dried ink had improved reflectance and whiteness (Table 10, L value at T=0).

[0058]

[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 desired by society. Furthermore, because magnesium oxide has whiteness and hiding power, it is possible to print white and other colors clearly. Furthermore, the edible ink composition also has good adhesion to the surface of the printing substrate. Therefore, the edible ink composition of the present invention is useful as a printing ink for the surface of solid foods and solid pharmaceutical preparations, particularly capsules, tablets, and caplets, especially capsules.

Claims

1. An edible ink composition comprising magnesium oxide, a binder and a solvent, wherein the magnesium oxide is produced at a baking temperature of at least 700°C, and the ink composition does not contain titanium oxide.

2. The edible ink composition according to claim 1, wherein the magnesium oxide is produced at a baking temperature of at least 800°C.

3. The edible ink composition according to claim 1 or 2, wherein the magnesium oxide has a D90 value of 20 μm or less.

4. The edible ink composition according to any one of claims 1 to 3, wherein the magnesium oxide has a particle size distribution with a D90 value of 1 to 15 µm.

5. The edible ink composition according to any one of claims 1 to 4, wherein the magnesium oxide has a particle size distribution having a D10 value of 0.1 µm or more.

6. An edible ink composition according to any one of claims 1 to 5, wherein the amount of magnesium oxide in the ink after drying of the edible ink composition is 99 mass % or less, preferably 60 to 99 mass %, relative to the weight of the ink after drying of the edible ink composition.

7. The edible ink composition according to any one of claims 1 to 6, wherein the solid content of the edible ink composition is 65% by weight or less, preferably 20 to 65% by weight, based on the weight of the edible ink composition.

8. The edible ink composition according to any one of claims 1 to 7, wherein the solvent volatilizes or vaporizes after the edible ink composition dries and does not essentially remain in the ink.

9. The edible ink composition according to any one of claims 1 to 8, wherein the solvent is an alcohol or a mixture of alcohol and water, preferably the alcohol is ethanol, propanol or butanol, more preferably ethanol or butanol, and even more preferably the alcohol is ethanol.

10. The edible ink composition according to any one of claims 1 to 9, wherein the binder is preferably an edible film-forming non-thermosetting polymer or shellac, the binder being soluble in alcohol, and when the binder is a non-thermosetting polymer, the binder is hydroxypropyl cellulose, polyvinylpyrrolidone or a mixture thereof.

11. The edible ink composition according to any one of claims 1 to 10, which contains a moisture-proof coating agent.

12. The edible ink composition according to claim 11, wherein the moisture-proof coating agent is a higher fatty acid ester that is soluble or miscible in alcohol and insoluble in water, an alcohol having 16 or more carbon atoms, a fatty acid having 12 or more carbon atoms, a glyceride, or a mixture thereof, or a surfactant having an HLB of 6 or less.

13. The edible ink composition according to claim 11 or 12, wherein the moisture-proof coating agent is stearic acid, beeswax such as white beeswax, resin such as rosin, Japan wax, spermaceti, lanolin, lanolin alcohol, cetanol, stearyl alcohol, cetanol monostearate polyethylene glycol mixed wax, cetanol polysorbate 60 mixed wax, cetostearyl alcohol, isopropyl myristate, isopropyl linoleate, isopropyl palmitate, oleic acid, or a vegetable oil such as olive oil or castor oil.

14. The edible ink composition according to any one of claims 11 to 13, wherein the amount of the moisture-proof coating agent added is 0.1 to 20%, preferably 0.1 to 10%, based on the total weight of the magnesium oxide and the binder.

15. The edible ink composition according to any one of claims 1 to 14, further comprising a further colorant having a color other than white.

16. The ink composition may include one or more additives commonly used in printing inks, such as a drying speed regulator, a plasticizer, a wetting agent, an adhesion promoter, an ink gloss agent, a thixotropic agent, and a fragrance, and the additives may be glycerin, triethyl citrate (TEC), triacetin, ethylene glycol, propylene glycol, resins, waxes, polyglycerin fatty acid esters, glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, lecithin, enzymatically decomposed lecithin, polysorbates, silicon dioxide (SiO ２ 16. The edible ink composition according to any one of claims 1 to 15, comprising: starch, alcohol-insoluble celluloses, flavors and / or combinations thereof.

17. A printing substrate printed with the edible ink composition according to any one of claims 1 to 16, 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.

18. A method for producing an edible ink composition, comprising a step of mixing magnesium oxide, a binder, a solvent, and an optional additive, which are components of the edible ink composition, to provide an edible ink composition according to any one of claims 1 to 16.

19. A method for printing an edible ink composition on a printing substrate, using the edible ink composition according to any one of claims 1 to 16 and a printing substrate.

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