JP3232810B2 - Film-forming external preparation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to cosmetics, external medicines,
It relates to an external preparation composition used for dermatological products, quasi-drugs, etc., and more specifically, to form a film by applying it on skin, mucous membranes, etc., and to effectively apply the active ingredient to the skin. The present invention relates to a film forming type external preparation characterized by the following. This can be applied to antiperspirants, insect repellents, antibacterials, anti-inflammatory analgesics, etc. by changing the active ingredient. The present invention also relates to a film-forming external preparation which is inexpensive, easily available with a safe solvent such as water, can be easily removed with a safe solvent, and is safe in human and animal skin and body, and the formed film is water-soluble.

[0002]

2. Description of the Related Art Conventionally, external preparations for skin application include liquid coatings, ointments and patches, which are more efficient means of administration than oral administration. Have been. However, as mentioned above,
Although external preparations have advantages, they have various problems due to their physical properties and the like. For example, in the case of a liquid coating composition, the penetration of the medicinal component into the skin is insufficient, and it has been difficult to continuously release the medicinal component to the skin surface. In ointments, the release of the medicinal component from the base is low, and the ointment adheres to the clothes, etc. due to contact with clothing etc. during operation, so the medicinal component decreases, the medicinal effect often decreases, and sustainability Was not enough. In the case of patches such as cataplasms and plasters, adhesive and elastic properties, such as areas where the skin expands and contracts due to the movement of joints, and areas where the shape is complex, do not adhere sufficiently to the skin surface and easily peel off. In addition, there have been cases where skin diseases such as rash occur due to long-term use.

[0003] In recent years, in order to solve such a drawback, a film-forming external preparation using a resin which forms a film by drying after application in a liquid or gel state at the time of application has been proposed. For example, JP-A-51-75745 discloses a polymer bandage composition comprising an acrylic copolymer and a plasticizer. However, since this composition is based on an acrylic copolymer, it lacks water resistance, and when used under high temperature and high humidity such as in summer, a large amount of sweat on the skin surface (especially salts therein) causes cohesive strength. As a result, the adhesion of the coating to the skin is reduced. In addition, although these polymers have low skin irritation, the problem of toxicity of the residual monomer still remains. When applied to the skin or the like, the skin irritation of the residual monomer occurs even if the adhesion to the skin is good. In addition, this film-forming type external preparation uses a water-soluble resin as a film-forming resin, and has a poor drying property because of a solvent mainly composed of water, and it takes time to form a film.

On the other hand, Japanese Patent Application Laid-Open Nos.
No. 145512 discloses a film-forming resin made of a water-insoluble polymer. These are excellent in water resistance, but can not be easily removed when removing the film from the skin,
In particular, when the composition is repeatedly applied, the applied substance remains and the absorbability of the drug is reduced. In addition, all of the above-mentioned compounds had low affinity with the drug, and were inferior in the release property of the drug from the coating and the skin absorbability.

[0005]

Under such circumstances, the present invention solves the above-mentioned problems of the prior art, and maintains a good film even in the presence of water, sweat, etc., because it dries quickly and is not sticky. An object of the present invention is to provide a film-forming external preparation which can be easily removed with water, forms a water-soluble film having high safety and high drug transferability.

[0006]

The present inventors have made intensive studies and as a result, have found that the N-vinylacetamide polymer or its copolymer is substantially used as a film-forming resin, and the formed film is water-soluble. It has been found that a film-forming type external preparation characterized by the fact that it exhibits good film-forming ability and solves the above problems.

That is, the present invention relates to the following matters. (1) A film-forming type, characterized in that a homopolymer of N-vinylacetamide or a copolymer thereof with a copolymerizable monomer is used as a film-forming resin, and that the formed film is water-soluble. External preparation. (2) The film-forming resin has the general formula (1)

Embedded image (Wherein, R ₁ represents hydrogen or a methyl group, and X represents CO
OM (M is an alkali metal), COOC _n H _{2n + 1} (n = 0
8 _{integer), COOC n H 2n OH (} n = 1~5 _{integer), COOC n H 2n C m} H 2m + 1 (n = 1~3 integer, m
= An integer of 1 to _{4), OC n H 2n + 1} (n = 1~8 integer), OCOC _n H _2n + 1 indicating the (n = 1 to 3 integer). A) a copolymer of one or more ethylenic monomers and N-vinylacetamide, wherein the total of said ethylenic monomers and N-vinylacetamide is 50 % Or more of the copolymer.

(3) N-vinylacetamide and the ethylenic monomer represented by the general formula [1] are mixed in a mass ratio of 95: 5.
The film-forming external preparation according to the above (2), which is copolymerized at a ratio of from 10 to 90:90. (4) The ethylenic monomer represented by the general formula [1]
The film-forming external preparation according to the above (2) or (3), which is (meth) acrylic acid and / or a salt thereof.

The film-forming external preparation of the present invention is generally said to have weak acidity because the N-vinylacetamide polymer or copolymer used is substantially nonionic. When the polymer or copolymer is coated on the anionic surface of the skin to be formed to form a film, the skin adhesion is considered to be higher than that of the ionic film-forming resin, and the presence of water and salt Since the cohesive force can be maintained without the polymer chain expanding and contracting due to the interaction of ions even under,
The decrease in the shape retention and the like of the film can be suppressed, and the film can be prevented from swelling, collapsing and falling off, and this is particularly effective for athlete's foot medicine, a soothing medicine and the like which are used for a part which is easy to sweat. Further, since the polymer or copolymer has nitrogen and oxygen atoms, the polarity of the formed film is increased, and the solubility of the drug is improved, so that the drug can be prevented from being precipitated as crystals, In addition, skin adhesion can be improved. Therefore, the film-forming external preparation of the present invention is excellent in drug release from the film and skin absorption.
In addition, since the polymer or copolymer is water-soluble, the hydrophilicity of the coating is improved, and it absorbs the water secreted on the skin surface. It is obtained and equilibrium is established with the water vapor in the outside world, thereby preventing skin unevenness and rash. N-vinylacetamide has low toxicity such as skin irritation.

The ethylenic monomer represented by the general formula (1) used in the present invention has a polymer flexibility and / or
Alternatively, it is added for the purpose of improving the viscosity. In addition, as the monomer represented by the general formula (1), specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, vinyl acetate, vinyl propionate, vinyl methyl ether, vinyl ethyl ether, hydroxyethyl (meth) acrylate, 2
-Hydroxypropyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth)
Acrylate, propylethyl (meth) acrylate,
Butoxyethyl (meth) acrylate, (meth) acrylic acid, sodium (meth) acrylate, potassium (meth) acrylate, and the like.
More than one species can be used.

The film-forming type external preparation of the present invention contains N-vinylacetamide and a compound of the general formula (1) as long as the film to be formed is water-soluble and does not impair the performance as a film-forming resin.
A monomer other than the ethylenic monomer represented by the formula (1) can be used in an amount of 0 to 50% by weight based on the total amount of the monomers. Examples of monomers that can be copolymerized include functional monomers such as itaconic acid, maleic acid, maleic anhydride, crotonic acid, and acrylonitrile, and vinyl monomers, but are not limited thereto.

Further, other polymers can be similarly added as a film-forming resin, and those which are sufficiently compatible with the copolymer or compatible with the copolymer to the extent that they become cloudy are preferable. . For example, these polymers include silicone rubber, polyisobrengon, styrene-block copolymer rubber, acrylic rubber, guar gum, locust bean gum, rubber-based thickening substances such as natural rubber, polyvinyl alkyl ether, polyvinyl alcohol, and poly (vinyl alcohol). Vinyl acetate, vinyl ether, polyvinylpyrrolidone, carboxyvinyl polymer, vinylpyrrolidone, vinylpyrrolidone vinylalkylaminoacrylic acid copolymer, metacarboxybetaine metacarboxyester copolymer, styrene maleic acid copolymer, ethylene-vinyl acetate copolymer Coal, vinyl-based thickening substance such as vinyl acetate-polyvinyl alcohol copolymer, starch, pullulan, ethyl cellulose, cellulose acetate, hydroxyethyl cellulose, hydroxymethyl cellulose. Loin, hydro waist methyl cellulose, hydroxypropyl cellulose, hydroxypropyl cellulose phthalate methyl cellulose, carboxymethyl such cellulosic adhesive material methylcellulose, (meth) thickening material mainly composed of acrylic acid alkyl ester (meth) acrylate,
Examples include polyether-based thickening substances such as polyethylene oxide, which are added to such an extent that the hydrophilicity of the film-forming external preparation is not affected.

In the film-forming resin used in the present invention, N-
Vinylacetamide and the ethylenic monomer represented by the general formula (1) are copolymerized to such an extent that the water solubility of the film-forming resin is not impaired, and the total is 50 to 100 of the total amount of the monomer.
%, Preferably 80 to 100% by weight.
If the amount is less than 50% by weight, the ability to form a film and the affinity for alcohol are remarkably reduced, and stickiness, stringing and the like occur. Further, the weight ratio is preferably in the range of 95: 5 to 10:90, and if it exceeds this range, the solubility with the plasticizer, the alcohol-philicity and the salt resistance are remarkably reduced. More desirably, the ratio is 90:10 to 30:70, and the effect is remarkable in this range.

The polymer or copolymer can be produced by polymerizing or copolymerizing a desired monomer by a known technique using an initiator. For example, it is produced by aqueous solution polymerization, precipitation precipitation polymerization, reverse phase suspension polymerization and the like. At the end of the polymerization, a viscous liquid, agar-like or powdery product is obtained. The polymer or copolymer obtained here was found to have extremely good solubility in water and alcohols, and an extremely excellent film-forming resin was obtained. In particular, since it is alcohol-philic, it is possible to produce a film-forming external preparation that can form a water-soluble film without using water as a solvent, so it is more dry than a conventional film-forming external preparation that uses a water-soluble polymer. Excellent in nature. The film-forming external preparation obtained by the present invention has a simple composition of only a film-forming resin and a plasticizer and / or a low-boiling solvent, has a high film-forming ability, can be prepared at extremely low cost, and is formed. Because the coating is water soluble, it can be quickly and completely removed with water.

Examples of the plasticizer used in the present invention include polyhydric alcohols, polyether polyols, isopropyl myristate, diethyl sebacate, diethyl phthalate, diisopropyl adipate, glycerin monooleate, polyethylene glycol, and polypropylene glycol. However, among these, a polyhydric alcohol is particularly desirable. As the polyhydric alcohol, propylene glycol,
Ethylene glycol, diethylene glycol, triethylene glycol, butylene glycol (dihydric alcohol), glycerin, trioxyisobutane (trihydric alcohol), erythrit, pentaerythritol (tetrahydric alcohol), xylit, adnit (pentahydric alcohol), allozurcit, Sorbit (hexahydric alcohol)
Etc., but not limited to this. It is known that polyhydric alcohols enhance the transdermal absorbability of a medicinal component by increasing the solubility of the medicinal component in the skin and the moisturizing property on the skin. In addition, propylene glycol has an antiseptic action, and glycerin and 1,3-butanediol have an action to alleviate the skin irritation of ethanol. This allows
It can be said that by using a polyhydric alcohol as the plasticizer, the composition of the film-forming external preparation of the present invention can be simplified.

The film-forming external preparation is also alcohol-philic, so that alcohols such as ethanol and isopropyl alcohol can be blended. Ethanol and isopropyl alcohol have a disinfecting and disinfecting effect on the skin surface, and if these can be incorporated into a film-forming external preparation, it is expected to be effective in preventing skin irritation due to bacterial growth and disinfecting and disinfecting wounds. Furthermore, since it is lipophilic and nonionic, it also absorbs alcohol solutions such as disinfectants, perspiration containing salt, body fluids, etc., and keeps its adhesion to the skin without lowering its adhesion to the skin.

To prepare the film-forming external preparation of the present invention, it is necessary to mix a film-forming resin or an aqueous solution or solvent solution thereof with a plasticizer, if desired, in the presence of water and / or a low-boiling solvent. If present, heat to dissolve.
The resulting film-forming external preparation is applied to the skin, nails and the like using a brush, fingertip, spray or the like, and immediately forms a film as the low-boiling solvent evaporates.

The low-boiling solvent used above is not particularly limited as long as it has a low boiling point and is volatile, but alcohols such as methanol, ethanol, butanol, isobutanol and propanol, acetone, methyl ethyl ketone, methyl isobutyl ketone and the like can be used. Water-miscible organic solvents such as ketones, cellosolve, dioxane, dimethylformamide, and N-methylpyrrolidone, as well as water-immiscible organic solvents such as ethyl acetate. Of these, propanol and ethanol are particularly preferred from the viewpoint of smell after coating and drying. These can be used alone or in combination of two or more kinds. When a water-miscible solvent such as a lower alcohol is used, purified water can be added as necessary. The compounding ratio of the solvent is determined in view of the viscosity of the composition, the solubility of the compound, the storage stability of the solution, the drying property, and the like.

The polymer or copolymer as the film-forming resin of the present invention is further used for percutaneous absorption and transmucosal for the purpose of exhibiting its properties more or for improving the processability, moldability and quality. When used as a drug for absorption, it can be arbitrarily selected from drugs acceptable as drugs for the purpose of improving the dispersibility and stability of the drug. These include medicines, stabilizers, fillers, UV absorbers, fragrances, coloring agents, usability improvers, preservatives, preservatives, plasticizers, antioxidants, softeners, surfactants, deterioration inhibitors, etc. There is. These are arbitrarily added within a range that does not affect the properties of the obtained film-forming external preparation.

In order to use the formulations according to the invention as vehicles for the administration of drugs, the drugs can be included in the solution stage (or in the gel suspension stage). There are a number of drugs that can be administered in this manner, including, for example, glycol salicylate, methyl salicylate, piroxicam, triamcinolone, hydrocortisone acetate, indomethacin, ketoprofen, ibufenac, loxoprofen, tiapofen, planoprofen, fempfen, diclofenac, ferpinac, Ketronac,
Anti-inflammatory analgesics such as vermoprofen, napmetone, naproxen, flurbiprofen, fluocinonide, clobetasol propionate, clotrimazole, tolnaftate, econazole nitrate, omoconazole nitrate, thioconazole nitrate, ketoconazole nitrate, miconazole nitrate, isoconazole nitrate, virolnitrin Antifungals such as bimafucin; antibiotics such as tetracycline hydrochloride and chloramphenicol; antihistamines such as diphenhydramine and chlorpheniramine maleate; antiperspirants such as diethylamide and camphor; angina pectoris treatment such as nitroglycerin and isosorbide dinitrate. Drugs, lidocaine, local anesthetics such as dibucaine, hormonal drugs, veterinary drugs, sleeping pills,
Antidepressants, sedatives, circulatory agents, cerebral metabolism enhancers, bactericides, vitamins, enzyme preparations, keratosis treatments, antirheumatic, antigout, antihypertensive, anticoagulants, etc. However, the present invention is not limited thereto, and two or more of these drugs can be used in combination as needed.
In addition, adjuvants for promoting the absorption of these drugs can be added. Examples of the absorption promoter include ethyl alcohol, isopropyl alcohol, butanol, 1,3-butanediol, propylene glycol, polyethylene glycol # 400, glycerin, Crotamiton, benzyl alcohol, phenylethyl alcohol, propylene carbonate, hexyldecanol, propanol, salicylic acid, urea, allantoin, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, diisopropyl adipate, diethyl sebacate, ethyl laurate, lanolin, aison and nonionic There are substances such as ionic surfactants, and one or more kinds can be added as needed. The amount to be added is determined in consideration of the balance between the film forming property and the adhesive force to the skin.

The present invention is also used for a peelable eyeliner and a pack, and a cosmetic containing a perfume, an antiperspirant and the like can be produced.

[0022]

EXAMPLES Next, the usefulness of the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1 A 1-liter three-neck separable flask was equipped with a thermometer and a nitrogen inlet tube, and N-vinylacetamide 9 was added thereto.
An aqueous solution in which 5 g of sodium acrylate and 5 g of sodium acrylate were dissolved in 740 g of deionized water was charged. After the dissolved oxygen was expelled by introducing nitrogen gas, the liquid temperature was adjusted to 30 ° C., and 10 g of a 1% aqueous solution of 2,2′-azobis-2-amidinopropane dihydrochloride was added as a polymerization initiator. For 7 hours. The resulting polymer was shredded, dehydrated in an acetone solution, and then dried under vacuum to obtain a dried polymer. 50 g of the N-vinylacetamide copolymer obtained above was dissolved in 60 g of propylene glycol, 50 g of Eudraggid E100 (EUDRAGID-E100 Rohm Pharma Co.), 3 g of indomethacin and 20 g of water, and then an appropriate amount of ethanol was added thereto. To obtain a film-forming external preparation.

Example 2 A 1-liter three-neck separable flask was equipped with a thermometer and a nitrogen inlet tube, and N-vinylacetamide 1 was added thereto.
An aqueous solution in which 0 g and 90 g of acrylic acid were dissolved in 740 g of deionized water was charged. After the dissolved oxygen was expelled by introducing nitrogen gas, the liquid temperature was adjusted to 30 ° C., and 10 g of a 1% aqueous solution of 2,2′-azobis-2-amidinopropane dihydrochloride was added as a polymerization initiator. For 7 hours. The resulting polymer was shredded, dehydrated in an acetone solution, and then dried under vacuum to obtain a dried polymer. 40 g of the N-vinylacetamide copolymer obtained above was heated and dissolved in 50 g of 1,3-butanediol, 1 g of miconazole nitrate, 0.1 g of zinc oxide and 20 g of water,
Then, an appropriate amount of isopropyl alcohol was added and mixed uniformly to obtain a film-forming external preparation.

Example 3 A 1-liter three-neck separable flask was equipped with a thermometer, a nitrogen inlet tube, and a stirring rod, and 450 g of water was charged. Next, stirring was started, and the polymerization initiator 2,
2'-azobis-2-aminodipropane dihydrochloride 80m
g in water and dissolved at once, 147 g of N-vinylacetamide, 63 g of methoxyethyl acrylate,
A mixed solution consisting of 40 g of water was quantitatively dropped over 1 hour to react, and the mixture was aged for 3 hours. During this time, the reaction system was 7
It was kept at 0 ° C. 90 g of polyethylene oxide, 10 g of isosorbide dinitrate, 10 g of 1,3-butanediol, and 210 g of water were added to this solution and uniformly dissolved to obtain a film form external preparation.

Example 4 A 1-liter three-neck separable flask was equipped with a thermometer, a nitrogen inlet tube, and a stirring rod, and 450 g of water was charged. Next, stirring was started, and the polymerization initiator 2,
2'-azobis-2-aminodipropane dihydrochloride 80m
g of N-vinylacetamide and 30 g of hydroxyethyl methacrylate.
g and 40 g of water were quantitatively added dropwise over 1 hour to react, and the mixture was aged for 3 hours. During this time, the reaction system was kept at 70 ° C. 70 g of polyethylene oxide, 5 g of fragrance, and 210 g of water were added to this solution and uniformly dissolved to obtain a film-forming external preparation.

Example 5 A 1-liter three-neck separable flask was equipped with a thermometer, a nitrogen inlet tube, and a stirring rod, and 450 g of water was charged. Then, stirring was started, and the polymerization initiator 2,
2'-azobis-2-aminodipropane dihydrochloride 80m
g of water at a time and dissolved therein, and a mixed solution consisting of 20 g of N-vinylacetamide, 40 g of methyl acrylate, 40 g of hydroxyethyl methacrylate and 40 g of water was quantitatively dropped over 1 hour and reacted. Aged for hours. During this time, the reaction system was kept at 70 ° C. 90 g of polyethylene oxide, 50 g of N-methylpyrrolidone and 20 g of hydroxypropyl cellulose were added to this solution.
And 210 g of water were added and uniformly dissolved to obtain a film-forming external preparation.

Example 6 A 1-liter three-neck separable flask was equipped with a thermometer, a nitrogen inlet tube, and a stirring rod, and 450 g of water was charged. Next, stirring was started, and the polymerization initiator 2,
2'-azobis-2-aminodipropane dihydrochloride 80m
g in water and dissolved at once, and a mixed solution consisting of 40 g of N-vinylacetamide, 30 g of methyl acrylate, 30 g of vinyl acetate, and 40 g of water was dropped quantitatively over 1 hour and reacted for 3 hours. Matured. During this time, the reaction system was kept at 70 ° C. 90 g of polyethylene oxide, 50 g of clotrimazole and water 2
10 g was added and uniformly dissolved to obtain a film-forming external preparation.

Comparative Example 1 30 g of Eudragit E100, 1 g of polyethylene glycol (# 1000) and 3 g of ketoprofen were dissolved in a mixed solution of 98 g of ethyl alcohol and 2 g of benzyl alcohol to obtain a film-forming external preparation.

Comparative Example 2 1 g of clotrimazole in 89 g of isopropyl alcohol
Was added, and 5 g of diethyl sebacate and 5 g of polyvinylpyrrolidone were added, followed by heating and dissolution to obtain a film-shaped external preparation.

Comparative Example 3 1.5 g of indomethacin was placed in a mixture of 4 g of crotamiton, 6 g of propylene glycol and 60 g of ethanol. Heat to 60 ° C and dissolve to form an alcohol layer.
20 g of water is heated to 60 ° C., 6 g of hydroxypropylcellulose is added, and the resin is dispersed and maintained at 60 ° C. to form an aqueous layer. The alcohol layer was poured into the water layer at a stretch and dissolved with good stirring, and the total amount was made up to 100 g with water, and then cooled to room temperature to obtain a film-type external preparation.

Comparative Example 4 10 g of pullulan was added to 100 g of N-methylpyrrolidone.
After dissolution at 0 ° C., O. -75 g of bistrimethylsilyl acetamide and 100 g of toluene were added and heated,
The mixture was stirred and reacted at 140 ° C. for 5 hours. After cooling, the reaction solution was diluted with 800 g of toluene, poured into methanol after stirring,
The polymer was separated by filtration. The obtained polymer was further redissolved in toluene, precipitated with methanol, filtered twice, and dried at 60 ° C. under vacuum. 5 g of the polymer obtained above was treated with 45 g of octamethylcyclotetrasiloxane and 8 g of decamethylcyclopentasiloxane.
Heated and dissolved in. To this solution was added indomethacin 0.5
g, 30 g of isopropyl myristate and 15 g of dextrin fatty acid ester were added and mixed to obtain a film-forming external preparation.

Evaluation Test Example Each of the film-forming external preparations obtained in Examples and Comparative Examples was applied to a bakelite plate with a thickness of 50 μm using an applicator, and the state of film formation was observed. Table 1 shows the results.

[0034]

[Table 1]

[0035]

From the above results, the present invention has the following effects. 1) It is excellent in water solubility, film forming property and sticking property, and can be prepared at extremely low cost. 2) When adhered to the skin, it forms a film with excellent uniformity, so it does not lose its appearance, and has no irritation and high safety. 3) Since it has an affinity for alcohol, it is possible to prepare a film-forming external preparation with a solvent mainly composed of alcohol, so that it is excellent in drying property. 4) Adhesion is not reduced by sweat or body fluid, and can be easily removed with water. 5) Because it is a film-forming external preparation with hydrophilicity and alcohol-affinity, it has high affinity for both drugs and absorption enhancers, especially when used for medical use, and has high safety without swelling, irritation and rash. A coating is formed.

Continuation of the front page (72) Inventor Kazuhiko Oga 5-1 Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Denko KK Chemical Research Laboratory (58) Field surveyed (Int. Cl. ⁷ , DB name) A61K 9 / 70,7 / 00

Claims (4)

(57) [Claims] 1. A film characterized in that a homopolymer of N-vinylacetamide or a copolymer with a monomer copolymerizable therewith is used as a film-forming resin, and the film formed is water-soluble. Formable external preparation. 2. A film forming resin according to the general formula (1): ## STR1 ## (Wherein, R ₁ represents hydrogen or a methyl group, and X represents CO
OM (M is an alkali metal), COOC _n H _{2n + 1} (n = 0
8 _{integer), COOC n H 2n OH (} n = 1~5 _{integer), COOC n H 2n C m} H 2m + 1 (n = 1~3 integer, m
= An integer of 1 to _{4), OC n H 2n + 1} (n = 1~8 integer), OCOC _n H _2n + 1 indicating the (n = 1 to 3 integer). A) a copolymer of one or more ethylenic monomers and N-vinylacetamide, wherein the total of said ethylenic monomers and N-vinylacetamide is 50 The film-forming external preparation according to claim 1, which is a copolymer occupying at least 1% by weight. 3. A weight ratio of N-vinylacetamide to an ethylenic monomer represented by the general formula [1] of 95: 5 to 10:
The film-forming external preparation according to claim 2, wherein the external preparation is copolymerized at 90. 4. The film-forming external preparation according to claim 2, wherein the ethylenic monomer represented by the general formula [1] is (meth) acrylic acid and / or a salt thereof.