# US 10,765,194 B2 · Method of preparing dry hydrogel sheet and dry hydrogel sheet prepared by the same

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- Number: US 10,765,194 B2
- Document ID: US10765194B2
- Status: Granted
- Kind: B2
- Application number: 15/773,761
- Filed: 2016-10-27
- Published: 2018-11-15
- Granted: 2020-09-08
- Earliest claimed: 2015-11-06
- Assignees: Lotte Fine Chemical Co., Ltd.
- Applicants: Lotte Fine Chemical Co., Ltd.
- Inventors: Ji Seon Jeong; Ju Hee Shin; Sung Hwan Bang; Ju Young Jung; Kil Seuk Byun; Kyong Min Lee
- Web page: https://patentgrep.com/patent/US10765194B2

## CPC

- A45D 44/002: {Masks for cosmetic treatment of the face}
- A45D 37/00: Sachet pads specially adapted for liquid toiletry or cosmetic substances
- A45D 44/22: Face shaping devices, e.g. chin straps; Wrinkle removers, e.g. stretching the skin (skin stretchers for shaving A45D27/38)
- A61K 8/0212: {Face masks}
- A61K 8/731: {Cellulose; Quaternized cellulose derivatives}
- A61K 9/0014: {Skin, i.e. galenical aspects of topical compositions (non-active ingredients are additionally classified in A61K47/00; A61K9/0009, A61K9/0021, A61K9/7015, A61K9/7023 take precedence; cosmetic preparations A61K8/00, A61Q; preparations for wound dressings or bandages A61L26/00)}
- A61K 9/7007: {Drug-containing films, membranes or sheets (A61K9/0041, A61K9/0043, A61K9/006, A61K9/0063 take precedence)}
- A61K 9/7046: {the adhesive comprising macromolecular compounds}
- A61L 15/28: Polysaccharides or their derivatives {(A61L15/225 takes precedence)}
- A61L 15/60: Liquid-swellable gel-forming materials, e.g. super-absorbents
- A61L 26/0023: {Polysaccharides}
- A61L 26/008: {Hydrogels or hydrocolloids}
- A61Q 19/00: Preparations for care of the skin
- C08J 3/075: Macromolecular gels
- C08J 5/18: Manufacture of films or sheets
- A45D 2200/1027: Tissues, i.e. thin applicator sheets
- A45D 2200/1036: containing a cosmetic substance, e.g. impregnated with liquid or containing a soluble solid substance
- C08J 2301/28: Alkyl ethers
- A45D: HAIRDRESSING OR SHAVING EQUIPMENT (wigs, toupees or the like A41G3/00, A41G5/00; hairdressers' chairs A47C1/04; hair cutting appliances, razors B26B); EQUIPMENT FOR COSMETICS OR COSMETIC TREATMENTS, e.g. FOR MANICURING OR PEDICURING
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- A61Q: SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

The present invention relates to a method of preparing a dry hydrogel sheet including the steps of: preparing a cellulose ether dispersion solution; transferring the dispersion solution to a coater while maintaining the temperature of the dispersion solution in the range of a gelation temperature of the dispersion solution to a boiling point of a dispersion medium; applying the dispersion solution transferred to the coater as a sheet; preparing a hydrogel sheet by cooling the applied dispersion solution to induce gelation; and drying the hydrogel sheet. Since the dry hydrogel sheet prepared by the method has a low moisture content, it is possible to ensure the stability of active ingredients, quantify functional components to be applied to the dry hydrogel sheet, and ensure the uniformity of the surface appearance and thickness of the dry hydrogel sheet, which results in the improvement of the quality of a final product.

## Claims

### Claim 1

A method of preparing a dry hydrogel sheet comprising:
preparing a cellulose ether dispersion solution;
transferring the dispersion solution to a coater while maintaining a temperature of the dispersion solution in a range from a gelation temperature of the dispersion solution to a boiling point of water;
applying the dispersion solution transferred to the coater as a sheet;
preparing a hydrogel sheet by cooling the applied dispersion solution to induce gelation; and
drying the hydrogel sheet,
wherein the cellulose ether dispersion solution consisting of a cellulose ether, a gelling agent, a gelling promoter and water,
wherein the cellulose ether is any one or two or more selected from the group consisting of hydroxypropyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxymethyl cellulose, and
wherein the range from the gelation temperature of the dispersion solution to the boiling point of water is between 55 and 90° C.

### Claim 2 (depends on 1)

The method according to claim 1, further comprising deaerating the dispersion solution to remove air bubbles from the dispersion solution.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the coater is selected from the group consisting of a gravure coater, a comma coater, a slot-die coater, and a spray coater.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the cooling of the dispersion solution is carried out by any one method selected from natural cooling, cooling with a cooling tunnel, and a combination thereof.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the drying of the hydrogel sheet is carried out by any one method selected from the group consisting of hot air drying, infrared drying, and microwave drying, or a combination of two or more thereof.