Water-filled capsule and method for producing the same

Abstract

To provide a water-filled seamless capsule technology that can encapsulate and retain the moisture of a content liquid in a capsule over a long period of time.SOLUTION: A water-filled capsule comprises a water-containing core containing water, and an encapsulating layer disposed outside the water-containing core. The encapsulating layer is made of a lipophilic composition having a specific gravity adjusted to be in a specific range, and the film thickness of the encapsulating layer is maintained in a range greater than or equal to a specific film thickness, so that the moisture of the water-containing core can be encapsulated and retained in the capsule over a long period of time.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-filled capsule having a water-containing core and an encapsulating layer disposed on the outside of the water-containing core, and a method for producing the same. [Background technology]

[0002] Conventionally, water-filled capsules have been known that include a water-containing core containing water, an inner layer disposed on the outside of the water-containing core, and an outer layer disposed on the outside of the inner layer, where the inner layer is made of a lipophilic material and the outer layer is made of a hydrophilic material in which lipophilic particles or water-insoluble particles are dispersed, and have excellent resistance to water evaporation (Patent Document 1).

[0003] Also known is a filter element for use in tobacco articles, which comprises at least one filter body, a core material containing a liquid medium, and a capsule having a water vapor-impermeable polymerized shell, wherein the liquid medium of the core material contains at least one surfactant (Patent Document 2).In addition, a method for producing easily breakable raw capsules useful for incorporation into tobacco products has been proposed (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6250211 [Patent Document 2] Special Publication No. 2020-527953 [Patent Document 3] Special Publication No. 2011-512122 Summary of the Invention [Problem to be solved by the invention]

[0005] Well-known content liquids that can be formulated into soft capsules include oils, oil-soluble substances, and emulsions (lipophilic + hydrophilic). On the other hand, even if it is possible to encapsulate water or a content liquid primarily composed of water, the water evaporates through the capsule shell soon after encapsulation, making it impossible to retain the moisture of the content liquid for a long period of time. Therefore, as far as the applicant knows, no capsule products encapsulating water or an aqueous solution are currently available in the market. Therefore, an object of the present invention is to provide a technology for a water-sealed seamless capsule that is capable of encapsulating and retaining the moisture of the content liquid for a long period of time and is water-resistant. [Means for solving the problem]

[0006] The inventors have conducted extensive research to solve the above problems, and have found that in a water-filled capsule comprising a water-containing core and an encapsulation layer arranged on the outside of the water-containing core, by making the encapsulation layer comprise a lipophilic composition having a specific gravity within a specific range and by maintaining the encapsulation layer at a thickness above a certain range, it is possible to encapsulate and retain the water in the water-containing core within the capsule for a long period of time, and that by adding a viscosity additive that imparts viscosity to the water in the water-containing core, the formulation properties of the capsule can be improved, which led to the completion of the present invention.

[0007] That is, the present invention is as specified by the following invention-specifying matters. [1] A water-filled capsule comprising a water-containing core and an encapsulation layer disposed on the outside of the water-containing core, wherein the encapsulation layer is made of a lipophilic composition having a specific gravity of 0.79 to 1.05, and the thinnest part of the encapsulation layer is 80 μm or more. [2] The water-filled capsule according to [1] above, wherein the water-containing core contains a viscosity additive that imparts viscosity to the water. [3] The water-filled capsule according to the above [1], wherein the lipophilic composition contains a specific gravity adjuster that adjusts the specific gravity of the lipophilic composition to 0.79 to 1.05. [4] The water-filled capsule according to [1] above, wherein the lipophilic composition has a melting point of 16°C or higher. [5] The water-filled capsule according to [1] above, wherein the lipophilic composition contains a solid oil having a melting point of 30 to 70°C. [6] The water-filled capsule according to [1] above, wherein the lipophilic composition contains a liquid oil having a melting point of less than 20°C. [7] The water-sealed capsule according to [1] above, characterized in that a coating layer is further provided on the outside of the encapsulation layer. [8] The water-filled capsule according to [7] above, wherein the water content of the shell layer is 20% or more. [9] The water-filled capsule according to [7] above, wherein the water content of the shell layer is less than 20%.

[0008] The present invention is also defined by the following invention-specific matters.

[10] A method for producing a water-filled capsule according to any one of [1] to [9] above, characterized in that a concentric triple nozzle is used, a water-containing core is discharged from the inner nozzle, an encapsulating layer is discharged from the middle nozzle, and a coating layer is discharged from the outer nozzle to form three-layer droplets, and the three-layer droplets are brought into contact with a cooling solvent to form a water-filled pre-capsule.

[11] The manufacturing method described in

[10] above, characterized in that before drying the water-filled precapsules, the coating layer is peeled off and removed, leaving two layers: a water-containing core containing water and an encapsulation layer placed on the outside of the water-containing core.

[12] The method for producing water-filled capsules according to

[10] above, characterized in that three-layer water-filled raw capsules are prepared without drying the water-filled pre-capsules.

[13] The method for producing a water-filled capsule according to

[10] above, further comprising a step of drying the water-filled pre-capsules to prepare a three-layer water-filled dry capsule. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a three-layer water-filled seamless capsule or a two-layer water-filled seamless capsule that shows little change in water encapsulation rate over time when left open at room temperature, is capable of encapsulating and maintaining the moisture of the content liquid (water-containing core) within the capsule for a long period of time, and has excellent water resistance. Furthermore, the physical properties of the encapsulation layer can be set to suit the application of the water-filled capsule. Furthermore, the physical properties of the encapsulation layer disposed on the outside of the water-containing core can be set to be hard or soft depending on the oily substance that constitutes it. For example, if the encapsulation layer is set to be soft, the two-layer capsule can be designed to be easy to crush with fingers and use as a water-filled raw capsule, which can be used for cosmetics, quasi-drugs, etc. DETAILED DESCRIPTION OF THE INVENTION

[0010] The water-filled capsule of the present invention is a water-filled capsule having a water-containing core and an encapsulation layer arranged on the outside of the water-containing core, wherein the encapsulation layer is made of a lipophilic composition having a specific gravity of 0.79 to 1.05, and the thinnest part of the encapsulation layer has a thickness of 80 μm or more.There are no particular restrictions on the water-filled capsule, and suitable examples include two-layer water-filled capsules and three-layer water-filled capsules, but multi-layer water-filled capsules with four or more layers are also acceptable.

[0011] The above-mentioned hydrous core is not particularly limited as long as it contains water, and may be composed of only water, but it is preferable that it contains a viscosity additive that imparts viscosity to water, and it may also contain various other active ingredients and various additives.

[0012] Examples of the viscosity-imparting agent include alginic acid, alginates such as sodium alginate, alginate esters such as propylene glycol alginate, celluloses such as methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose, gelatin, carrageenan, agar, starch, modified starch, dextran, dextrin, pullulan, glucomannan, gum arabic, furcellaran, and tragacanth. Examples of suitable sugars include guar gum, locust bean gum, gellan gum, xanthan gum, polyvinylpyrrolidone, polyvinyl alcohol, glucosamine, Eucheuma algae, soybean water-soluble polysaccharides, welan gum, cassia gum, Agrobacterium succinoglycan, guar gum enzymatic hydrolysate, ghatti gum, arabinogalactan, curdlan, karaya gum, tamarind seed gum, psyllium seed gum, tara gum, amas seed gum, konjac flour (from potato), hydroxypropylated guar gum, and pectin.

[0013] In the encapsulation layer, the oily substance constituting the lipophilic composition can be, first, an oily substance having a melting point of 20°C or higher (hereinafter referred to as "solid fats and oils"). Specific examples include hydrogenated oils (liquid animal and vegetable fats with a melting point increased by hydrogenation), partially hydrogenated oils (hydrogenated oils obtained by hydrogenating only a portion of liquid animal and vegetable fats or a mixture of non-hydrogenated fats and hydrogenated oils), and waxes. Specific examples of solid fats and oils include hydrogenated castor oil, hydrogenated soybean oil, hydrogenated rapeseed oil, hydrogenated coconut oil, cocoa butter, butter, hydrogenated palm kernel oil, tallow oil, lard, lard hydrogenated oil, beeswax (beeswax), candelilla wax (candelilla wax), rice bran wax (rice wax), carnauba wax (carnauba wax), Japan wax (urushi wax), etc., or mixtures thereof.

[0014] Secondly, examples of oily substances constituting the lipophilic composition include liquid oily substances (hereinafter referred to as "liquid oils") having a melting point of less than 20°C. Specific examples include animal and vegetable oils such as safflower oil, linseed oil, sesame oil, olive oil, soybean oil, mustard oil, rapeseed oil, corn oil, castor oil, evening primrose oil, palm kernel oil, jojoba oil, cottonseed oil, coconut oil, peanut oil, EPA, DHA, DPA, squalane, shark liver oil, and cod liver oil, as well as medium-chain triglycerides (MCTs) and liquid paraffin.

[0015] The oily substance constituting the lipophilic composition may also include surfactants such as glycerin fatty acid esters, sucrose fatty acid esters, and fatty acid acyl esters that are highly lipophilic (for example, those with an HLB value of less than 7 or less than 10). In this case, among the surfactants, those that are solid at 20°C can be used as solid oils and fats, and oily substances that are liquid at temperatures below 20°C can be used as liquid oils and fats. The lipophilic composition that can be used in the present invention may be a mixture of one or more types appropriately selected from solid oils and liquid oils. Commercially available products that can be used include the "GELUCIRE" series manufactured and sold by Gattefosse, Nissin MCT Oil, Kao "Excel" series, Kao "Econa" series, Kao "Emanone" series, and Kao "Leodor" series.

[0016] The oily substance constituting the lipophilic composition can also be various oily functional ingredients (oil-based components having various functions such as nutritional function, flavoring function, pigment function, etc.). Examples of oily nutritional functional ingredients that can be used in the present invention include omega fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, docosapentaenoic acid, oily substances such as prostaglandins, oil-soluble vitamins such as vitamin A, vitamin E, vitamin D, vitamin K, etc., and oils and fats containing these. Examples of oily components with fragrance-like properties include natural essential oils such as orange oil, lemon oil, perilla oil, ambrette seed oil, orris root oil, cananga oil, mustard oil, caraway oil, carrot seed oil, grapefruit oil, ginger oil, hop oil, myrtle oil, rose oil, and rosemary oil, as well as synthetic or natural flavorings such as eugenol, ethyl caprylate, geraniol, menthol, citral, citronellal, and borneol. Examples of oily components with pigment-like properties include oil-based colorants such as annatto pigment, carotene, and oleoresin. Naturally, these can be used alone or in combination.

[0017] The lipophilic composition can contain an oil-insoluble component. Any component that is miscible with the oil component can be used as the oil-insoluble component. Examples of oil-insoluble components that can be miscible with the oil component include inorganic powders such as titanium dioxide, calcium carbonate, magnesium carbonate, magnesium oxide, calcium stearate, magnesium stearate, (fine) silicon dioxide, and aluminum oxide.

[0018] A specific gravity adjuster can be used to adjust the specific gravity of the lipophilic composition to a predetermined range. Such a specific gravity adjuster is a substance that can be dissolved or mixed with the lipophilic composition and has a specific gravity different from that of the lipophilic composition before the addition of the specific gravity adjuster. Suitable specific gravity adjusters include oily substances with a specific gravity of 1 or more, such as SAIB (Sucrose Acetate Isobutylate), wood rosin glycerin ester, and sucrose octaacetate. Inorganic powders such as titanium dioxide, calcium carbonate, magnesium carbonate, magnesium oxide, calcium stearate, magnesium stearate, (fine) silicon dioxide, and aluminum oxide can also be used as specific gravity adjusters if they can adjust the specific gravity by mixing with the lipophilic composition before addition. Furthermore, animal and vegetable oils, synthetic oils, ester oils, mineral oils, and the like that are acceptable for the intended use of the present invention can also be used as specific gravity adjusters if they can adjust the specific gravity by adding them to the lipophilic composition before addition.

[0019] The specific gravity of the encapsulation layer in the present invention can be preferably 0.79 to 1.05, 0.79 to 1.03, 0.79 to 1.0, 0.795 to 1.05, 0.795 to 1.03, 0.795 to 1.0, 0.8 to 1.05, 0.8 to 1.03, 0.8 to 1.0, 0.83 to 1.05, 0.83 to 1.03, 0.83 to 1.0, 0.85 to 1.05, 0.85 to 1.03, 0.85 to 1.0, and particularly preferably 0.80 to 1.0. Furthermore, it was confirmed that it is possible to formulate water-filled capsules using a low-density lipophilic composition (e.g., a mixture of the above-mentioned squalane and hydrogenated oil, with a density of 0.795 for the encapsulation layer) and a high-density lipophilic composition (e.g., a mixture of the above-mentioned SAIB and hydrogenated oil, with a density of 1.03 for the encapsulation layer) as the encapsulation layer.

[0020] Regarding the thickness of the encapsulation layer, what is important is the thickness of the thinnest part (thinnest part thickness), and as long as it is kept at a minimum level, for example, 80 μm or more, preferably 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, 150 μm or more, 180 μm or more, 210 μm or more, 240 μm or more, 270 μm or more, 300 μm or more, 350 μm or more, 400 μm or more, 450 μm or more, or 500 μm or more, the thickness may vary.

[0021] A three-layer water-filled capsule can also be formed by providing an additional shell layer on the outer side of the encapsulating layer. Such a shell layer may be any commonly used shell for seamless capsules, including, for example, a shell layer containing, as a base, gelatin, casein, zein, pectin and its derivatives, alginic acid or its salts, agar, gellan gum, tragacanth gum, guar gum, locust bean gum, carrageenan, tamarind, mannan, hemilose, starch, chitosan, etc. Furthermore, the shell layer may contain, in addition to the base, plasticizers such as glycerin, sorbitol, propylene glycol, polyethylene glycol, etc., pH adjusters such as sodium phosphate, chelating agents such as trisodium citrate and sodium metaphosphate, gelation promoters such as calcium lactate and potassium chloride, surfactants such as polyglycerol fatty acid esters and lecithin, sweeteners, flavorings, preservatives, colorants, etc. Furthermore, the shell layer may contain additives such as natural pigments, synthetic pigments, various sweeteners, preservatives, water activity reducers, pH adjusters, etc. Three-layer water-sealed capsules can also be classified into dry capsules and raw capsules depending on the water content of the shell layer.

[0022] The coating liquid used for the coating layer preferably has a viscosity of 300 mPa·s or less at 85°C measured with a C-type viscometer (Toki Sangyo Co., Ltd., VISCOMETER TVC-7) using rotor No. 1 (upper limit 500 mPa·s).

[0023] The method for producing the water-filled capsules of the present invention is not particularly limited as long as it involves using a concentric triple nozzle, ejecting the water-containing core from the inner nozzle, the encapsulating layer from the middle nozzle, and the coating layer from the outer nozzle to form three-layer droplets, and then contacting these three-layer droplets with a cooling solvent set at, for example, 0 to 25°C to form water-filled pre-capsules.Examples of the cooling solvent include cooling oils such as MCT composed of fatty acids such as capric acid and caprylic acid, liquid paraffin, vegetable oils such as sunflower oil and safflower oil, or mixtures of these, as well as low-temperature gases such as air, helium, nitrogen, and argon.

[0024] If the coating layer is peeled off and removed before the water-filled pre-capsules dry, a two-layer water-filled capsule can be produced, consisting of two layers: a water-containing core containing water and an encapsulation layer placed on the outside of the water-containing core.Since the coating layer is soft, it can be easily peeled off using a simple tool such as a finger or a medicine spoon to peel off and remove the water-filled pre-capsules before they dry.

[0025] When the water-filled capsules of the present invention are double-layered water-filled capsules, they can be roughly divided into solid capsules and raw capsules based on the hardness of the encapsulation layer, with those with a hard encapsulation layer being solid capsules and those with a soft encapsulation layer being raw capsules. However, since the boundary between the two types of capsules in terms of physical properties is unclear, we decided to use a new rheometer to measure the hardness of each encapsulation layer formulation and compare their maximum loads. Therefore, in this invention, for the sake of convenience, we will classify capsules formed with an encapsulation layer whose maximum load when the adapter is pressed 3 mm into the rheometer using the following [measurement equipment] and [measurement method] as double-layered water-filled raw capsules (double-layered raw capsules) and those formed with an encapsulation layer whose maximum load exceeds 5 kg as double-layered water-filled solid capsules (double-layered solid capsules).

[0026] [Measurement method] 150 g of the encapsulation layer was prepared in a 200 mL glass beaker, dissolved in a water bath at 60°C (75°C if hydrogenated oil e was included), and stirred thoroughly. 50 g of the solution was placed in a plastic polyethylene bottle, refrigerated for at least 3 hours to solidify, and then left to return to room temperature. The maximum load was measured using a rheometer when the adapter was pressed 3 mm into the center of the polyethylene bottle.

[0027] [Measurement equipment] SUN RHEO METER CR-3000 EX-L (Sun Scientific) Mode: MODE1(Depth) Adapter: No.1φ10mm REAL / HOLD: HOLD Approach distance: 3.0mm Compression / Tension: PRESS Table movement speed: 20.0 mm / min Load cell maximum force: 200N

[0028] To prepare a double-layered solid capsule, a solid oil or a solid oil and a liquid oil is used as an example of the lipophilic composition of the encapsulation layer, and the melting point (measured value) of the encapsulation layer is, for example, 37°C or higher, and the specific gravity of the encapsulation layer is, for example, 0.82 to 1.05. On the other hand, to prepare a double-layered raw capsule, a mixed oil of a solid oil and a liquid oil is used as an example of the lipophilic composition of the encapsulation layer, and the melting point (measured value) of the encapsulation layer is, for example, 16 to 36.8°C, and the specific gravity of the encapsulation layer is, for example, 0.79 to less than 0.82. In addition, double-layered raw capsules are usually easily disintegrating capsules. It has been found that the melting point of the encapsulation layer, which is a mixed oil of a solid oil and a liquid oil, shows an almost single peak, rather than a double peak of the melting points of the solid oil and the liquid oil.

[0029] The melting point was measured using a differential scanning calorimeter "DSC7020" (manufactured by Hitachi High-Tech Science Corporation), starting at 0°C and increasing at a rate of 5°C / min, with the endothermic peak being the measured melting point.

[0030] The melting point of the oily substance constituting the lipophilic composition is not particularly limited, but when the water-filled capsule is a two-layer capsule, it can be roughly classified into solid capsules and raw capsules depending on the properties of the lipophilic composition. That is, in the case of a two-layer solid capsule, the lipophilic composition has a melting point of 20°C or higher, preferably 30°C or higher, and preferably has a melting point of 100°C or lower, preferably 80°C or lower, more preferably 70°C or lower, and among them, a lipophilic composition having a melting point of 30°C to 70°C can be preferably exemplified. The lipophilic composition can also be appropriately adjusted by mixing multiple oily substances such as hydrogenated oils with different melting points, or by adding liquid animal and vegetable oils. On the other hand, when the properties of the water-filled capsule are raw capsules, for example, a mixture of the above-mentioned solid oil and liquid oil with a melting point of less than 20°C is used. For example, in the case of a water-filled capsule in which the melting point of the mixed oil in the encapsulating layer is 16°C, even though it is liquid at room temperature, it remains semi-raw under refrigerated conditions, and if distribution and use under refrigerated conditions are considered, it can also be considered a two-layer raw capsule.

[0031] On the other hand, when the water-filled capsule is a three-layer capsule, it can be roughly classified as either a raw capsule or a dry capsule, mainly depending on the properties of the shell. In the case of a three-layer water-filled raw capsule (three-layer raw capsule), the above-mentioned concentric triple nozzle is used, and the water-containing core is discharged from the inner nozzle, the encapsulation layer is discharged from the middle nozzle, and the shell layer is discharged from the outer nozzle to form three-layer droplets, and the three-layer droplets are brought into contact with a cooling solvent to form water-filled pre-capsules, which are then prepared into three-layer raw capsules without undergoing a shell drying process. The above-mentioned "without undergoing a shell drying step" (step) refers to the production of three-layered water-filled capsules without using known capsule drying methods such as spray drying, freeze drying, air drying, vacuum drying, static drying, and vacuum vibration drying. However, for convenience, this can also include stopping the drying step (drying stop step) before the water content of the shell of the water-filled pre-capsules becomes, for example, less than 20%, less than 25%, less than 30%, less than 45%, less than 70%, or less than 90%. The water content of the shell of a three-layered raw capsule can be 20% or more, preferably 25% or more, more preferably 30% or more, more preferably 45% or more, even more preferably 70% or more, and even more preferably 90% or more.

[0032] The three-layered capsule shells that do not undergo the above-mentioned shell drying process are characterized by their softness, and the moisture content of the shell can be measured using, for example, an infrared moisture meter FD-720 (manufactured by Kett Electric Laboratory) under the conditions of 1 g of shell / 105°C / 15 minutes.

[0033] In other words, the three-layered raw capsule can be produced and stored by a method comprising the following steps (a) to (c): (a) forming a triple-layer droplet using a concentric triple nozzle by discharging a water-containing core from an inner nozzle, an encapsulating layer from a middle nozzle, and a coating layer from an outer nozzle; (b) contacting the trilayer droplets with a cooling solvent to form water-encapsulated precapsules; (c) immersing the water-encapsulated precapsules in a capsule preservative solution; The three-layer water-sealed capsule can be washed with detergent or running water as needed to remove the cooling solvent adhering to the periphery.

[0034] The capsule preservative solution can be an aqueous solvent containing at least one water selected from tap water, well water, distilled water, purified water, ion-exchanged water, ultrapure water, deep ocean water, mineral water, etc. Because the capsule has a high water content, preservatives such as phenoxyethanol or antibacterial agents such as 1,3-butylene glycol can be added to the capsule or preservative solution to prevent spoilage of the capsule, especially when used in cosmetics. The resulting three-layered raw capsules can be immersed in a preservative solution for transport, and are advantageous in that they can retain the encapsulated water and water-soluble ingredients within the capsules for long periods of time, even during storage and transport. Therefore, one example of applications for the three-layered raw capsules is their incorporation or dispersion into water-rich products, which can be used in a wide variety of fields, including foods, pharmaceuticals, quasi-drugs, cosmetic compositions such as cosmetics, topical skin preparations, beverages, pet food, and luxury items.

[0035] On the other hand, the above-mentioned water-filled pre-capsules can be dried using known capsule drying methods such as spray drying, freeze drying, air drying, vacuum drying, static drying, vacuum vibration drying, etc. to prepare capsules as triple-layered dry water-filled capsules (triple-layered dry capsules). The water content of the shell of the triple-layered dry capsules can be less than 20%, preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less.

[0036] In other words, the three-layer dry capsule can be produced by a method comprising the following steps (a) to (c): (a) forming a triple-layer droplet by using a concentric triple nozzle to eject a water-containing core from an inner nozzle, the encapsulating layer from a middle nozzle, and the coating layer from an outer nozzle; (b) contacting the trilayer droplets with a cooling solvent to form water-encapsulated precapsules; (c) drying the water-filled pre-capsules to produce three-layer dry capsules;

[0037] In the case of the above-mentioned three-layer dry capsule, assuming a fragile capsule used for tobacco, for example, the hardness of the capsule shell is 0.5 to 40 N, preferably 0.5 to 20 N, from the viewpoints of manufacturability and fragility, and the thickness of the capsule shell is 20 to 500 μm, preferably 40 to 200 μm, from the viewpoints of ease of gripping and content volume, and the diameter of the capsule is 0.5 to 15 mm, preferably 1 to 8 mm, and the capsule shell ratio is 5 to 30%, for example.

[0038] The three-layer dry capsules can be easily broken by hand, and the snapping sound and feel that occur when the capsule breaks are pleasant. Therefore, if a capsule containing a flavoring or the like is embedded inside a filter that comes with cigarettes or a filter to be attached to cigarettes, the sound, feel, and aroma of the capsule being crushed can be obtained by crushing it with the fingers during smoking. Also, if a capsule containing a flavoring is placed inside a greeting card, the recipient can crush the capsule and enjoy the sound, feel, and aroma. Other applications include pharmaceuticals, health foods, foods, cosmetics, cleaning supplies, and other daily necessities. The three-layer dry coated capsules may include not only the easily breakable capsules used for tobacco applications as described above, but also capsules suitable for oral intake.

[0039] An example of a method for determining the water encapsulation stability of the capsules of the present invention is to measure the change in water encapsulation rate over time by measuring the mass of a capsule left open at 22°C and 18 to 45% RH (or 70% RH at 5°C, or 8% RH at 25°C), in the case of a double-layered solid capsule. After 4 weeks, the water encapsulation stability is determined to be 75% or more, preferably 85% or more, and more preferably 90% or more. After 8 weeks, the water encapsulation stability is determined to be 50% or more, preferably 75% or more, more preferably 78% or more, even more preferably 80% or more, and particularly preferably 90% or more.

[0040] In the case of the above-mentioned three-layer dry capsule, which is a fragile capsule used for tobacco applications, if the sound and feel when crushed with fingers is good even one month (1M) after the capsule has dried, and the sound and feel of the capsule breaking can be enjoyed, it can be determined that the moisture and water-soluble components in the hydrous core have not migrated to the coating side and that the capsule is stable in water sealing.

[0041] An example of a method for evaluating the water resistance of the capsules of the present invention is to visually check for pigment transfer to the hydrous core when the water-filled capsules are immersed in a preservative solution and stored. When the water and water-soluble components of the hydrous core are sealed and stably maintained in the raw capsule, the preservative solution remains colorless and does not change in color, but when the water or water-soluble components in the hydrous core migrate to the preservative solution through the shell, the preservative solution turns blue, and instability can be visually confirmed.

[0042] The present invention will be specifically explained below by way of examples, but the present invention is not limited to these examples in any way. [Example]

[0043] [Preparation of water-filled capsules] Using a concentric triple nozzle (manufactured by Fuji Capsule Co., Ltd.), a coating liquid having the composition shown in Table 1 was ejected from the outermost nozzle, a water-containing core liquid having the composition shown in Tables 2 and 3 was ejected from the innermost nozzle, and an encapsulation layer liquid having the composition shown in Tables 2 and 3 was ejected from the middle nozzle to form three-layer droplets.These three-layer droplets were then brought into contact with a cooling solvent consisting of MCT to harden the coating liquid, thereby producing three-layer water-encapsulated precapsules comprising a water-containing core, an encapsulation layer encapsulating the water-containing core, and a coating layer encapsulating the encapsulation layer.

[0044] The outermost gelatin shell layer was removed from the three-layer water-filled pre-capsules without a drying process to produce two-layer water-filled capsules. It was confirmed that water can be sealed in as long as the sealing layer of these two-layer water-filled capsules is present as the outer layer, and that the gelatin shell layer is not necessarily required.

[0045] [Table 1]

[0046] [Table 2]

[0047] [Table 3]

[0048] [Examples 1 to 7] In the water-containing cores of Examples 1 to 6, water was thickened with sodium alginate, Chimica Algin IL-2 (manufactured by Chimica Co., Ltd.), to improve filling properties. The encapsulation layer was based on four types of solid fats and oils, and the thickness of the encapsulation layer exceeded 70 μm, enabling water encapsulation. In Examples 3, 4, and 4-1, a specific gravity adjuster, SAIB (manufactured by Eastman Chemical Co.), was added to the solid fats to improve filling properties.

[0049] The water entrapment rate test shown in Table 2 measured the change in water entrapment rate over time after 4 weeks, 8 weeks, 12 weeks, and 16 weeks of exposure to temperatures of 22°C and 18 to 45% RH (or 70% RH at 5°C and 8% RH at 25°C). As a reference and target evaluation standard for the water entrapment rate, 100% water was enclosed in Comparative Example 1 [polyethylene bag: made of low-density polyethylene resin, thickness 0.06 mm] and Comparative Example 2 [rubber balloon (water balloon): made of natural rubber, thickness 0.10 mm], and the change in water entrapment rate over time was measured. Comparative Example 1 was superior to Comparative Example 2 in terms of water entrapment rate, and Examples 1 to 7 had water entrapment rates that were roughly equivalent to or superior to Comparative Example 1.

[0050] In Example 4, the capsules of Example 4-1 were obtained by seamless filling with three layers, and then the outer gelatin shell layer was peeled off without going through the shell drying process to form two-layer water-encapsulated capsules. Water encapsulation is possible as long as the encapsulation layer is present as the outer layer, and the shell layer (gelatin) is not necessarily required. The presence or absence of a shell layer can be appropriately selected depending on the product application. Furthermore, the results of the change in water encapsulation rate over time in Examples 4 and 4-1 show that there is no difference in water encapsulation rate between the two-layer and three-layer structures.

[0051] [Examples 8 to 12] In Examples 8 to 12 and Comparative Example 3, in order to determine the minimum thickness of the encapsulation layer capable of encapsulating water, two-layer capsules were prepared in which the minimum thickness of the encapsulation layer was varied from 700 to 70 μm, and the changes in the water encapsulation rate over time were measured after leaving the capsules open at 22°C and 18 to 45% RH for 4, 8, 12, and 16 weeks. To measure the thickness of the thinnest part of the encapsulation layer, a high-resolution 3D X-ray microscope "NANO3DX" (manufactured by Rigaku Corporation) was used to take non-destructive cross-sectional images and confirm the film thickness.

[0052] On the other hand, when the thinnest film thickness of the encapsulation layer was 70 μm (Comparative Example 3), the water encapsulation rate dropped significantly and was unsuitable for water-encapsulated capsules, but when the thinnest film thickness was greater than that, a good water encapsulation rate was maintained.

[0053] Each water-filled capsule was prepared according to the formulation shown in Table 4 below.

[0054] [Table 4]

[0055] [Rheometer measurement equipment] SUN RHEO METER CR-3000 EX-L (Sun Scientific) Mode: MODE1(Depth) Adapter: No.1φ10mm REAL / HOLD: HOLD Approach distance: 3.0mm Compression / Tension: PRESS Table movement speed: 20.0 mm / min Load cell maximum force: 200N

[0056] Examples 13 and 14 In the water-filled capsules of Examples 13 and 14, the encapsulation layer was made of an oily substance containing a mixture of solid oil and squalane, a liquid oil said to have a melting point of -38°C, and the specific gravities of the encapsulation layer were set to low values ​​of 0.795 and 0.815, respectively. Furthermore, the maximum load measured with a rheometer was 0.75 kg in Example 13 and 3.42 kg in Example 14, indicating that two-layered raw water capsules with soft encapsulation layers were obtained. Data from the water-filled rate time-dependent change test after 8 weeks showed that both capsules maintained a water encapsulation rate superior to that of Comparative Example 2 (rubber balloon (water balloon)). Therefore, it was confirmed that two-layered raw capsules with an encapsulation layer specific gravity of 0.795 to 0.815 maintained an excellent water encapsulation rate.

[0057] Examples 15 and 16 In the water-filled capsules of Examples 15 and 16, the encapsulating layer was made of an oily substance, a mixture of solid oil and liquid oil squalane, and the specific gravity of the encapsulating layer was set to a slightly high level of 0.825 or 0.835. The maximum load measured with a rheometer was 5.81 kg in Example 15 and 7.18 kg in Example 16, resulting in two-layer water-filled solid capsules with a relatively hard encapsulating layer.

[0058] Example 17 The specific gravity of the lipophilic composition in the encapsulation layer was set to a high specific gravity of 0.99 using SAIB as a specific gravity adjuster, and a two-layer solid capsule was prepared as Example 17. Data after 8 weeks of the water encapsulation rate time-dependent change test showed that the water encapsulation rate remained superior to that of Comparative Example 2 (rubber balloon (water balloon)).

[0059] [Preparation of three-layer water-filled dry capsules] Examples 18 and 19 For Example 18, a triple-layered dry capsule with a gelatin-based film was prepared with a high specific gravity of 0.99. For Example 19, a triple-layered dry capsule with a gelatin-based film was prepared with an even higher specific gravity of 1.03.

[0060] In both Examples 18 and 19, the data after 4 weeks of the aging test showed a water inclusion rate of 75% or more, and the data after 8 weeks of the water inclusion rate aging test showed a water inclusion rate of 50% or more, maintaining a water inclusion rate superior to that of Comparative Example 2 (rubber balloon (water balloon)).

[0061] (Comparative Examples 4 and 5) The specific gravity of the lipophilic composition in the encapsulation layer was set to a low specific gravity of 0.775 and 0.785 using squalane as a specific gravity adjuster in Comparative Examples 4 and 5, respectively, but both were difficult to formulate into three-layer capsules. For formulation, a specific gravity of 0.79 or higher is required.

[0062] (Comparative Examples 6 and 7) The specific gravity of the lipophilic composition in the encapsulation layer was set to a high specific gravity of 1.065 using SAIB as a specific gravity adjuster, resulting in Comparative Example 6 (two-layer capsule) and Comparative Example 7 (three-layer capsule). When the specific gravity was greater than 1.05, capsule formulation was poor, but capsules could still be produced. However, the water encapsulation rate decreased over time to about 2% after 8 weeks, resulting in a very poor water encapsulation rate. In both cases, the data after 4 weeks and 8 weeks of the water encapsulation rate change test showed a lower water encapsulation rate than Comparative Example 2 (rubber balloon (water balloon)), and the capsules could not be said to have excellent water encapsulation stability.

[0063] [Study on three-layer dry capsules] It is known that capsules containing flavorings and the like are embedded in cigarette filters and broken when smoking to enjoy the aroma, or the sound and feel of the capsule breaking. However, oil-soluble flavorings, which are easy to encapsulate, have generally been used as the flavorings used. When water-soluble flavorings are used, even if encapsulation is possible, problems have been pointed out, such as the moisture and water-soluble components in the water-soluble flavoring quickly migrate to the capsule shell, softening the shell, making it impossible to enjoy the sound and feel of the capsule breaking. Therefore, we decided to conduct further research to solve these problems.

[0064] The three-layer water-filled pre-capsules prepared according to the procedure described above in [Preparation of water-filled capsules] were dried using a tumbler-type rotating air dryer (manufactured by Fuji Capsule Co., Ltd.) to prepare three-layer dry capsules according to the formulation shown in Table 5 below.

[0065] In the water-containing core, water, propylene glycol, and / or ethanol and / or glycerin were used as components of the water-soluble fragrance, and hydroxypropyl cellulose was used as a viscosity additive instead of sodium alginate.

[0066] In the encapsulation layer, SAIB was used as a specific gravity adjuster, and the specific gravity of the encapsulation layer was set to a relatively high level of 0.94 or 0.945.

[0067] For the coating layer, a carrageenan-based coating formulation containing carrageenan and water, a gelatin-based coating formulation containing gelatin and water, or an agar-based coating formulation containing agar and water was used, which can be used for cigarette filter embedding capsules and mask cartridges.

[0068] [Table 5]

[0069] (Confirmation of water sealing stability) (Examples 20 to 25) The six types of three-layer dry capsules in Examples 20 to 25 all had thinnest membrane thicknesses in the range of 130 μm to 300 μm. Furthermore, the specific gravity of the encapsulation layer, which used a solid oil with a melting point of 44.2°C and a specific gravity adjuster SAIB, was 0.940 to 0.945, but the physical properties of the encapsulation layer were hard, resulting in three-layer dry water-encapsulated capsules. Regardless of whether the shell layer was carrageenan-based, gelatin-based, or agar-based, the capsules could be easily cracked with fingers, and the snapping sound and feel when the capsules were cracked were pleasant and satisfactory. Even one month (1M) after the capsules dried, the sound and feel when crushed with fingers were still good, and the sound and feel of the capsule cracking were enjoyable. Therefore, it was confirmed that three-layer dry capsules with a thinnest membrane thickness of 130 μm or more have high water-encapsulation stability.

[0070] The moisture content of the shell layer of the six types of dry capsules was measured using an infrared moisture meter FD-720 (Kett Electric Laboratory) under the conditions of 1 g of shell / 105°C / 15 minutes, and was in the range of 8 to 15%. The thickness was 40 to 200 μm, the hardness was 0.5 to 20 N, the shell ratio was 5 to 30%, and the capsule diameter was 1 to 8 mm.

[0071] [Preparation of three-layer capsules containing fresh water] Prior art raw capsules are two-layer capsules in which an oil-soluble ingredient or lipophilic composition is encapsulated in a soft, moist shell, and are known for use in cosmetics. During use, the capsule is crushed to break the capsule shell, releasing the contents at the application site, which are then mixed in a fresh state with a liquid, cream, or semi-solid cosmetic base. However, the contents typically contain oil-soluble ingredients or lipophilic compositions, and no raw capsules containing water or water-soluble ingredients are known. Therefore, we investigated three-layer raw capsules with a water-containing core, which are intended for use as described above (Examples 26 to 30).

[0072] Following the procedure described above in [Preparation of Water-Sealed Capsules], water-sealed precapsules were prepared for each formulation shown in Table 6 below. After washing with running water, the three-layered raw capsules were immersed in a preservative solution (aqueous preservative solution / colorless) containing a preservative (phenoxyethanol) and an antibacterial agent (1,3-butylene glycol).

[0073] For the water-containing core, Blue No. 1 was added to the water as a pigment to visually confirm the pigment transfer in the water-containing core in the water resistance test, and sodium alginate was used as a viscosity additive.

[0074] In the encapsulation layer, MCT (Coconard MT, manufactured by Kao) was used as a liquid oil together with the solid oil, which resulted in a higher specific gravity of the encapsulation layer. In Examples 27 to 30, SAIB was used as a specific gravity adjuster, and the specific gravity of the encapsulation layer was set high at 1.01 and 1.00. The thinnest film thickness was 150 μm or more in all cases.

[0075] For the coating layer, a carrageenan-based coating formulation containing carrageenan and water, a gelatin-based coating formulation containing gelatin and water, or an agar-based coating formulation containing agar and water was used.

[0076] Water resistance was evaluated by visually observing pigment transfer to the hydrous core when the three-layered raw capsules were immersed in a preservative solution (aqueous preservative solution / colorless) containing a preservative (phenoxyethanol) and an antibacterial agent (1,3-butylene glycol). When the water and water-soluble components of the hydrous core were stably contained within each three-layered raw capsule, the preservative solution remained colorless and showed no change in color, confirming water resistance. On the other hand, when the water and water-soluble components in the hydrous core migrated to the preservative solution through the capsule membrane, the preservative solution turned blue, indicating instability and a lack of water resistance. The results are shown in Table 6 below.

[0077] [Table 6]

[0078] (Examples 26 to 30) (Check water resistance) The three-layer capsules of Examples 26 to 30 were all three-layered capsules containing raw water, with the thinnest membrane thickness of the encapsulation layer being 150 μm or more, and the specific gravity of the encapsulation layer using MCT as the liquid oil being 0.930 to 1.010. Furthermore, after the capsules dried, the three-layered raw capsules were immersed in a preservative solution, and even after three months (3M), no pigment migration to the preservative solution occurred, confirming their high water resistance. Furthermore, these capsules could be easily crushed by hand and used. The measured values ​​of the shell moisture content of the three-layered raw capsules were 20.4% for carrageenan-based capsules, 49.6% for gelatin-based capsules, and 97.5% for agar-based capsules. At these shell moisture contents, each capsule was deemed to be soft and suitable for raw capsules.

[0079] [Study on capsule water resistance] As shown in the following Table 7 (Examples 31 to 35), two-layer solid capsules or three-layer capsules having various thicknesses of the thinnest part of the encapsulation layer were prepared.

[0080] The water resistance of water-filled capsules prepared according to the formulations shown in Table 7 was evaluated. Specifically, water was placed in a 20 mL glass vial, and one capsule was immersed in the water. The capsule was then stored at room temperature with the cap closed. The capsule was visually inspected after 4, 8, 12, and 16 weeks to determine whether the dye in the hydrated core of the capsule had leaked out of the capsule over time.

[0081] [Table 7]

[0082] (result) As is clear from Table 7, Comparative Example 8 had a minimum thickness of 60 μm, but after 8 weeks all capsules leaked dye, failing to provide water resistance. On the other hand, Example 31 and Example 32 were two-layer solid water-sealed capsules with a minimum thickness of 200 μm or more and 500 μm or more, respectively. Even after 16 weeks, the water in the glass vial did not turn blue, demonstrating water resistance and no dye leakage. The three-layer dry capsule of Example 33, which had a minimum thickness of 500 μm or more, showed swelling of the gelatin shell over time, but no dye leakage from the aqueous core, demonstrating water resistance. Examples 34 and 35 were two-layer solid water-sealed capsules with a minimum thickness of 0.940 and 1.030, respectively, demonstrating good water resistance. [Industrial Applicability]

[0083] The water-sealed capsules of the present invention can be used as water-sealed capsules that can stably retain hydrophilic volatile substances for long periods of time in various fields, including pharmaceuticals, quasi-drugs, cosmetics, foods, beverages, dairy products, seasonings, supplements, pet food, household goods, luxury goods such as tobacco and tobacco substitutes, industrial goods such as fertilizers, feed, and cleaning agents, as well as other fields.

Claims

[Claim 1] A two-layer water-filled capsule having a water-containing core containing water and an encapsulating layer disposed on the outside of the water-containing core, the encapsulating layer is made of a lipophilic composition having a specific gravity of 0.890 to 0.945, the lipophilic composition being made of a solid oil or a mixture of a solid oil and a specific gravity adjuster; The two-layer water-sealed capsule is characterized in that the change in water encapsulation rate over time after 12 weeks when left open at 22°C and 18 to 45% RH is 92.0% or more, and the thinnest part of the encapsulation layer is 80 μm or more.

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