DOUBLE-LAYER SEAMLESS CAPSULE CONTAINING WATER-SOLUBLE COMPOSITION

Abstract

The present invention addresses the problem of providing a double-layer seamless soft capsule having a water-soluble composition as its fill, and by preparing a capsule shell from an ultraviolet-curing resin composition, a double-layer seamless capsule is made which consists of a capsule shell and a water-soluble composition as a fill and where volatility of the fill due to permeation through the shell is low.

Claims

1. A double-layer seamless capsule consisting of a capsule shell provided from an ultraviolet-curing resin composition and water or a water-soluble composition as a fill.

2. The seamless capsule according to claim 1, wherein a viscosity of the ultraviolet-curing resin composition is 20 to 2000 mPa.Math.s.

3. The seamless capsule according to claim 1, wherein the ultraviolet-curing resin composition is an acrylic resin composition, an epoxy-based resin composition, or a silicone resin composition.

4. The seamless capsule according to claim 1, wherein the acrylic resin composition comprises an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator.

5. The seamless capsule according to claim 1, wherein the water-soluble composition comprises water, a water-soluble flavor, a water-soluble alcohol, glycerol, or propylene glycol.

6. The seamless capsule according to claim 1, wherein a shell thickness of the thinnest part of the capsule shell, as measured using a three-dimensional X-ray microscope, is 100 μm or more.

7. The seamless capsule according to claim 1, wherein the seamless capsule has a diameter of 1 to 6 mm.

8. The seamless capsule according to claim 1, wherein the seamless capsule has a mass decrease of less than 5% after stored at 20° C. for 60 days.

9. The seamless capsule according to claim 1, wherein the seamless capsule is enclosed in a filter of a cigarette.

10. A method for making a double-layer seamless capsule comprising a fill and a shell for covering the fill, the method comprising the following steps (a) to (c): (a) a step of providing water or a water-soluble composition as the fill; (b) a step of providing an ultraviolet-curing resin composition as a capsule-shell solution; and (c) a step of discharging, into a forming liquid, the capsule-shell solution from an outer nozzle and the water or the water-soluble composition from an inner nozzle by use of a concentric double nozzle to form a double-layer droplet, and irradiating the double-layer droplet with ultraviolet rays to cure the capsule-shell solution and thereby give a capsule shell.

11. The method for making a seamless capsule according to claim 10, wherein a viscosity of the ultraviolet-curing resin composition is 20 to 2000 mPa.Math.s.

12. The method for making a seamless capsule according to claim 10, wherein the ultraviolet-curing resin composition is an acrylic resin composition, an epoxy-based resin composition, or a silicone resin composition.

13. The method for making a seamless capsule according to claim 12, wherein the acrylic resin composition comprises an acrylic oligomer, an acrylic monomer, and a photopolymerization initiator.

14. The method for making a seamless capsule according to claim 10, wherein the water-soluble composition comprises water, a water-soluble flavor, a water-soluble alcohol, glycerol, or propylene glycol.

15. The method for making a seamless capsule according to claim 10, wherein a shell thickness of the thinnest part of the capsule shell, as measured using a three-dimensional X-ray microscope, is 100 μm or more.

16. The method for making a seamless capsule according to claim 10, wherein the seamless capsule has a diameter of 1 to 6 mm.

17. The method for making a seamless capsule according to claim 10, wherein the seamless capsule has a mass decrease of less than 5% after stored at 20° C. for 60 days.

18. The method for making a seamless capsule according to claim 10, wherein the seamless capsule is enclosed in a filter of a cigarette.

Description

EXAMPLES

Example 1

[0055] Ultraviolet-curing resins used in the following examples are shown in Table 1.

TABLE-US-00001 TABLE 1 Type of shell- solution composition Viscosity (mPa .Math. s) Main component Ultraviolet-curing 500 Acrylic resin resin A Ultraviolet-curing 40 Silicone resin resin B Ultraviolet-curing 4600 Acrylic resin resin C *Viscosity: B-type viscometer (manufactured by TOKIMEC INC.)

[0056] (Water-Encapsulated Capsule)

[0057] Using, as an ultraviolet-curing resin composition, an acrylate resin composition obtained from an ultraviolet-curing resin A listed in Table 1 and comprising an acrylate oligomer, an acrylate monomer, acrylic acid and a photopolymerization initiator, a capsule shell was provided, and using water as a fill, making of a double-layer seamless capsule was carried out.

[0058] Using a concentric double nozzle (manufactured by FUJI CAPSULE CO., LTD.), the acrylate resin composition was discharged from an outer nozzle, and water was discharged from an inner nozzle, thereby forming a double-layer droplet. The movement speed of the double-layer droplet in a forming liquid having been adjusted to a viscosity of 10 mPa.Math.s (25° C., B-type viscometer) was set to 5 cm/s.

[0059] The double-layer droplet was introduced into a glass tube of 20 cm together with the forming liquid, then two line-type UV light sources (E110 II HD, Ushio Inc.) were installed in such a manner that the glass tube was interposed between them, and irradiation with ultraviolet rays (wavelength 365 nm) was carried out from two directions to cure the shell. Since the integrated quantity of light to cure the ultraviolet-curing resin composition was 15 kJ/m.sup.2, the flow rate of the forming liquid was adjusted so that the movement speed of the capsule might become about 5 cm/s, and irradiation was carried out at an irradiation intensity of 3 W/cm.sup.2 (work distance 5 mm) for 2 seconds or more.

[0060] (Volatility Test)

[0061] Regarding the water-encapsulated capsule, the shell thickness of the thinnest part of the capsule shell was measured using “high-resolution three-dimensional X-ray microscope Nano3DX” (manufactured by Rigaku Corporation), then five capsules in each of which the shell thickness measured value of the thinnest part of the capsule shell was 100 μm or more were collected to measure an average total mass, they were stored in a glass bottle under the conditions of 20° C., then based on the total mass measured on the 30th day and 60th day, a mass decrease ratio from the mass of the storage start date was calculated, and the results are set forth in Table 2.

TABLE-US-00002 TABLE 2 Storage period (days) 30 60 Retention (%), Water 99.0 98.6 n = 5 capsules Grapefruit flavor 99.1 98.8 aqueous solution 20% Ethanol 98.8 95.5 solution

[0062] (Results)

[0063] As is obvious from Table 2, when water was used as the fill, a capsule in which the shell thickness of the thinnest part was 100 μm or more had a mass change of less than 5% after 60 days and had low volatility, so that it is thought that the capsule was able to have sealed the fill.

[0064] (Volatility Severe Test)

[0065] Regarding volatilities of capsules in which water and the grapefruit flavor aqueous solution were each used as the fill and a capsule shell was provided using the ultraviolet-curing resin A as the ultraviolet-curing resin composition, a severe test was carried out. After the mass of each capsule was measured, the capsule was kept for 30 minutes under the vacuum conditions (50 hPa), thereafter the mass was measured, and a decrease ratio was calculated. The results are set forth in Table 3.

TABLE-US-00003 TABLE 3 Severe test (filling solution permeability evaluation) Fill permeability evaluation under vacuum (50 hPa) conditions Total mass Total mass Vacuum The before after Decrease time number of vacuum vacuum ratio (min) capsules (mg) (mg) (%) Water (control) 30 — 100 0 100 Water-encapsulated capsule 30 6 198 198 0 (shell: ultraviolet-curing resin A) Grapefruit flavor (volatile component*- 30 4 203 203 0 containing water-soluble flavor)- encapsulated capsule (shell: ultraviolet-curing resin A) Comparative Example 1 30 12 193 188 2.0* Volatile component* 10%-containing oily flavor-encapsulated capsule (shell: carrageenan) *In Comparative Example 1, the “decrease ratio” was 2%, but only 10% of the volatile component was contained in the capsule fill (diluted with MCT), and the volatilization volume of the volatile component was about 20%.

[0066] As is obvious from Table 3, a capsule with a conventional carrageenan shell (Comparative Example) had a mass decrease ratio of about 20% based on the amount of the volatile component, and it is thought that the volatile component in the flavor permeated and leaked through the shell. On the other hand, the water-encapsulated capsule and the grapefruit essence-encapsulated capsule had no mass change (0%) under the vacuum conditions, and therefore, it has been confirmed that the capsule shell of the present invention was able to have sealed the volatile component contained in the fill.

Example 2

[0067] (Water-Encapsulated Capsule-1 Using Another Resin)

[0068] Using, as an ultraviolet-curing resin composition, a silicone resin composition obtained from the ultraviolet-curing resin B listed in Table 1, a capsule shell was provided, and using water as a fill, making of a double-layer seamless capsule was carried out in the same manner as in Example 1, and as a result, a capsule was able to be normally produced.

[0069] The double-layer droplet was introduced into a colorless and transparent tube of 20 cm together with a curing liquid-forming liquid, then two line-type UV light sources (E110 II HD, Ushio Inc.) were installed in such a manner that the tube was interposed between them, and irradiation with ultraviolet rays (wavelength 365 nm) was carried out from two directions to cure the shell, and as a result, capsule formation was possible.

Comparative Example 2

[0070] (Water-Encapsulated Capsule-2 Using Another Resin)

[0071] Using, as an ultraviolet-curing resin composition, an acrylic resin composition obtained from the ultraviolet-curing resin C listed in Table 1, a capsule shell was provided, and using water as a fill, making of a double-layer seamless capsule was attempted in accordance with Example 1, but good capsule formation was unable to be carried out.

INDUSTRIAL APPLICABILITY

[0072] The seamless capsule of the present invention can be utilized as a water-soluble composition-encapsulated seamless capsule which can stably hold a hydrophilic volatile substance for a long time, in fields of medicines, quasi drugs, cosmetics, household daily necessities, industrial goods, etc.