Depilation Method

The present invention relates to a depilation method to remove hair without pain.

A depilatory agent is practically used in the form of a wax or a cream containing a depilatory medicine.

In the case of a depilatory cream, hair is removed by applying the cream to a position to be depilated, allowing it to stand for a predetermined time, and then wiping off the cream.

In the above method, however, care must be taken in that the cream does not attach to clothes and so on until the effect of the depilatory medicine is exhibited after coating the depilatory cream. In wiping the cream, unpleasant odor due to decomposition of hair by the medicine is generated. Moreover, the skin irritation tends to occur by strongly rubbing.

In the case of wax, hair is removed physically and there is the problem that a strong pain is involved.

Accordingly, one object of the present invention is to provide a depilation method which can remove hair without pain and generation of unpleasant odor in a short period of time.

Another object of the present invention is to provide a depilation method which can sufficiently remove hair from the root portion thereof by forming a depilatory agent into a film and peeling off the film.

The depilation method according to the present invention comprises coating a depilatory agent containing an aqueous solution or emulsion of a polymer compound having a film forming ability, and a depilatory medicine on a portion where hair is removed, drying the resulting coating to form a film, and then peeling off the film.

More specifically, the depilatory method of the present invention includes the following embodiments.

One embodiment is a depilatory method comprising applying a depilatory agent containing an aqueous solution (including a paste and gel) or emulsion of a polymer compound having a film forming ability, a depilatory medicine and, if necessary, a film reinforcing agent onto a depilatory portion, naturally drying the resulting coating to remove the moisture, thereby forming a film, and peeling off the film.

Another embodiment is characterized by a drying means to convert a depilatory agent coated on a depilatory portion into a film. This drying treatment includes a heat treatment using hot air, a treatment utilizing the water absorption capability of a water absorbing sheet, and a heat treatment using hot air after adhering a water absorbing sheet.

Further embodiment is characterized by a peeling manner of a depilatory agent in the form of a film. This includes a method comprising bonding a pressure-sensitive adhesive sheet to the surface of the film of the depilatory agent and peeling off the adhesive sheet together with the film.

The depilatory agent which is used in the present invention contains an aqueous solution or emulsion of a polymer compound having a film forming ability, a depilatory medicine and a film reinforcing agent which is compounded, if necessary. In addition, if necessary, suitable amounts of additives such as an alkali agent, a hair swelling accelerating agent, a filler, a perfume and a coloring agent are compounded.

The depilatory agent using an aqueous polymer compound solution comprises 1 to 70 wt%, preferably 2 to 50 wt%, more preferably 5 to 30 wt%, of at least one water-soluble polymer substance selected from the group of polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid and its salts, polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, gelatin, alginic acid salts, polyethylene glycol, gum arabic, polyvinyl methyl ether and the like, 1 to 15 wt%, preferably 3 to 12 wt%, more preferably 3 to 20 wt%, of at least one depilatory medicine selected from the group of thioglycolic acid or its salts, strontium sulfate, sodium sulfide, potassium sulfide and the like, and the remainder composed of water and the above described other additives, and is designed such that the viscosity is 0.1 to 1,000 poises (at 30.degree. C.), preferably 0.2 to 100 poises (at 30.degree. C.). To adjust the viscosity to such range, a small amount (about 0.1 to 10 wt%) of a viscosity increasing agent can be used. For example, the above described water-soluble high molecular material can be used as the viscosity increasing agent.

The depilatory agent using an emulsion of a polymer compound comprises 1 to 70 wt%, preferably 20 to 60 wt%, more preferably 30 to 55 wt%, of at least one water-insoluble polymer substance selected from the group of rubbers such as natural rubber and synthetic rubber, polyvinyl acetate, ethylenic copolymers, wax, homo- or copolymers of (meth)acrylic esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate and decyl (meth)acrylate, and copolymers of polar monomers having a functional group such as an amino group, and amido group, a hydroxyl group, a carboxyl group and an epoxy group, or polar monomers not having a functional group such as (meth)acrylonitrile, vinyl acetate, styrene, vinyl pyrrolidone and vinyl ether, and the above descried (meth)acrylic acid esters, 1 to 15 wt%, preferably 3 to 12 wt%, more preferably 3 to 10 wt%, of the above described depilatory medicine, and the remainder composed of water and the above described other additives, and is designed such that the viscosity is 0.1 to 1,000 poises (at 30.degree. C.) and preferably 0.2 to 100 poises (at 30.degree. C.).

Examples of the alkali agents are the ammonium salt or metal salt of organic dicarboxylic acid, potassium hydroxide, calcium hydroxide, and sodium hydroxide. The alkali agent can be compounded in an amount of 0.1 to 5 wt%, preferably 0.5 to 3 wt%, based on the weight of the depilatory agent.

Examples of the film reinforcing agent are natural, synthetic or inorganic short fibers having a length of 0.1 to 14 mm, preferably 1 to 10 mm and a diameter of 1 to 50 .mu.m, preferably 1 to 10 .mu.m. The amount of the film reinforcing agent compounded is 1 to 30 wt% and preferably 2 to 15 wt% based on the weight of the depilatory agent. For the purpose of increasing the film reinforcing effect, 1 to 35 wt% of silicon dioxide, calcium carbonate, clay, kaolin, aluminum hydroxide or the like can be used. These compounds also act as fillers.

An example of the hair swelling accelerating agent is urea. Furthermore, for the purpose of increasing the flexibility of the film, in the case of a water-soluble depilatory agent, polyvalent alcohols such as glycerin can be used in an amount of 1 to 15 wt% based on the weight of the depilatory agent, and in the case of an emulsion type depilatory agent, a plasticizer comprising phthalic acid derivatives such as dioctyl phthalate and dibutyl phthalate can be used in an amount of 1 to 15 wt% based on the weight of the depilatory agent.

The thus compounded depilatory agent is coated usually in an amount (thickness) of 0.01 to 3 mm, preferably 0.1 to 1 mm, although the amount of the depilatory agent varies depending on the applied portion such as a hand and a leg.

A predetermined amount of the depilatory agent is coated, and under conditions that the moisture is dissipated at a high temperature, for example, in the summer season, the resulting coating is allowed to dry in the natural atmosphere to thereby form a film. Upon peeling off the film, hair the root of which has been weakened by the depilatory medicine can be sufficiently removed, not leaving any film at the depilatory portion.

In peeling off the film of the depilatory agent, when the depilatory agent is the emulsion type, the film becomes transparent with decreasing water due to evaporation of moisture and, therefore, the dry condition can be relatively easily determined visually and the depilation operation can be carried out without an error.

Film formation of the depilatory agent coated on a portion to be depilated can be accelerated by, as well as the above natural drying method, an additional drying means. It can be understood from the explanation as described hereinafter that the additional drying means facilitates the depilation operation in addition to the film formation.

One of such drying means is a heat treatment with hot air. This heat treatment is preferably conducted after allowing to stand the depilatory agent for several minutes after coating, thereby impregnating the depilatory medicine in the depilatory agent in the hair. Usually the drying is carried out at 50.degree. to 200.degree. C. for 1 to 10 minutes. The heat source is sufficient to be a home drier.

The film thus formed can be peeled off as such to achieve the depilation. If, in this case, a pressure-sensitive adhesive sheet is bonded to the surface of the film and peeled off together with the film, the film can be peeled off without leaving any pieces because the film and the pressure-sensitive sheet are strongly bonded.

Suitable pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet which is prepared by coating a film-like substrate having flexibility and pliability, such as a plastic film, paper, nonwoven fabric and cloth, each having a thickness of about 5 to 100 .mu.m, with an adhesive substance made mainly of rubber and/or synthetic resin and having pressure-sensitive adhesiveness at ordinary temperature (30.degree. C.) in a thickness of about 5 to 200 .mu.m. More preferred sheet is a sheet which has an adhesive force to a bakelite plate of about 20 to 2,000 g/cm (180.degree. peeling adhesive force at 25.degree. C., tensile speed: 300 mm/min). The size of the sheet is not critical, and the sheet may be equal to or larger or smaller than the film of the dipilatory agent. If the sheet has a larger area than the film, the depilation operation is simplified because a portion extending from the edge of the film forms a part for the separation. When the sheet has a smaller surface area than the film, it is convenient to form a pick up portion of the film by peeling off a part of the film.

Another drying means is as follows. A water absorption sheet is bonded to the depilatory agent coated and, if necessary, heat treatment is applied from the side of the water absorption sheet bonded.

In accordance with this drying means, the water absorption sheet absorbs the water contained in the depilatory agent coated in a short period of time to form a film, the film is peeled off together with the sheet to achieve the depilation or only the sheet is peeled off from the film and then the above pressure-sensitive adhesive sheet is bonded to the film and the film is peeled off together with the sheet to remove hair. In this way, the film can be removed without leaving any piece on a portion to be depilated. When, in this case, heating is applied in combination, the drying time for forming the coating can be shortened.

As the water absorption sheet, any sheet-shaped material can be used so long as it is capable of absorbing water. For example, when a porous sheet material (preferably having a thickness of 5 to 100 .mu.m) such as hydrophilic nonwoven fabrics, paper, cloth and foamed sheets is used, the sheet material is integrally combined by placing it on the depilatory agent coated which is still in a wet condition and then slightly pressing, and by drying the assembly in that state, the film is peeled off together with the water absorption sheet to remove the hair.

Preferred examples of other water absorption sheets are as follows. A film or sheet of a high water absorption polymer having a water absorption ratio of 10 to 1,000 times (by weight) the weight thereof which is prepared by introducing suitable intramolecular cross-linking into a water-soluble polymer having a hydrophilic group such as a hydroxyl group, a carboxyl group or its salt, and which is insoluble in water, such as a polymer prepared by graft polymerization of (meth)acrylic acid, (meth)acrylonitrile, and maleic anhydride onto starch, cross-linked product of a copolymer of .alpha.-olefin having 2 to 12 carbon atoms and maleic anhydride or its derivative, or alkali neutralized product, and polyacrylic acid salt; and nonwoven fabrics, paper and foamed products and so forth in the inside or on the surface of which the above high water absorption polymer is dispersed or laminated. The water absorption sheet made of such a high water absorption polymer absorbs water in the depilatory agent due to the water absorption capability and a coating having the desired physical strength can be formed.

The water content of the depilatory agent formed into a film by the drying treatment is controlled so as to be 0.1 to 10 wt% when the heating treatment is applied in combination, or to be 10 to 40 wt% when the heating treatment is not applied, so that the physical pain at the time of depilation can be reduced and the depilatory effect can be exhibited.

The depilation method of the present invention has the following advantages. Unpleasant odor is not generated because the odor due to decomposition of hair by a depilatory medicine is masked with a polymer compound having a film forming ability. Serious pain is not felt by the medical action of the depilatory medicine. Hair can be removed without leaving any residue by using a pressure-sensitive sheet or a water absorption sheet in combination.

The present invention is described in greater detail by reference to the following examples. Unless otherwise indicated, all percents, parts, ratios and the like are by weight.

A composition consisting of the above components was dissolved in water to prepare a uniform aqueous polymer compound solution (100 poises at 30.degree. C.). This depilatory agent was coated 50 to 300 .mu.m and allowed to stand for about 5 minutes and the portion was heated with a drier. In 5 minutes, a film (water content: 4 to 5 wt%) was formed and hair was in the condition that it was trapped in the film. Since the strength of hair was reduced or the hair was dissolved by the effect of the depilatory medicine, pain was not caused when the film was peeled off from the skin and residue was not left on the portion.

A composition consisting of the above components and a small amount of polyvinyl pyrrolidone as a viscosity increasing agent was mixed to prepare a uniform emulsion (30 poises at 30.degree. C.). This depilatory agent was coated on a portion to be depilated in a thickness of about 200 to 400 .mu.m in the same manner as in Example 1 and allowed to stand for about 5 minutes, and the portion was heated with a drier. A film (water content: 1 to 3 wt%) which was substantially transparent was formed, and by peeling off the film, the hair was removed without any pain.

The depilatory agent of Example 1 was uniformly coated on a portion to be depilated in a size of about 5.times.10 cm in a thickness of about 300 .mu.m and allowed to stand for about 5 minutes, and the portion was then heated with a drier. In 5 minutes, a film was formed, and hair was trapped in the film. A pressure-sensitive adhesive sheet piece having a width of 5 cm and a length of 11 cm (adhesive force to a bakelite sheet: 100 g/cm), with a polyisobutylene pressure-sensitive adhesive layer (thickness: 50 .mu.m) provided on the surface thereof was bonded to the above film. The sheet was peeled off together with the film by picking up the edge of the sheet not bonded to the film to remove the hair. Since the strength of the hair was reduced or the hair was dissolved by the effect of the depilatory medicine, the film could be removed together with the sheet without any pain, and furthermore the hair was completely removed without leaving any film residue on the portion.

A composition consisting of the above components and a small amount of polyvinyl pyrrolidone was mixed to prepare a uniform emulsion (30 poises at 30.degree. C.). This depilatory agent was coated on a portion to be depilated in a size of about 5.times.10 cm in a thickness of about 200 .mu.m in the same manner as in Example 3 and allowed to stand for about 5 minutes, and the portion was heated with a drier to form a nearly transparent film (water content: 1 to 2 wt%). After making the film transparent, the same pressure-sensitive adhesive sheet as used in Example 3 was bonded. When peeling off the sheet together with the shet, hair was completely removed without any pain, and furthermore a film residue was not left.

The same depilatory agent as used in Example 1 was coated on a portion to be depilated in a size of about 5.times.20 cm in a thickness of about 100 to 300 .mu.m, and a rayon nonwoven fabric having a width of 6 cm and a length of 12 cm was bonded thereto, followed by allowing to stand for about 5 minutes, and the portion was heated with a drier. In 5 minutes, a film was formed, and the hair was trapped in the film. This film was peeled off together with the nonwoven fabric by pulling the edge of the nonwoven fabric remaining unbonded to the film. Since the strength of the hair was reduced or the hair was dissolved by the effect of the depilatory medicine, the film could be removed together with the nonwoven fabric without any pain, and the hair could be removed without leaving any residue on the portion.

A composition consisting of the above components and a small amount of polyvinyl pyrrolidone was mixed to prepare a uniform emulsion (30 poises at 30.degree. C.). This depilatory agent was coated on a portion to be depilated in a size of about 5.times.10 cm in a thickness of about 300 to 500 .mu.m in the same manner as in Example 5, and a cotton cloth having a width of 6 cm and a length of 12 cm was then bonded thereto. The portion was heated for about 4 minutes with a drier to form a film (water content: 3 to 4 wt%). When peeling off the film together with the cotton cloth, the hair could be removed completely without any pain, and furthermore any film residue was not left.

A composition consisting of the above components was dissolved in water to prepare an aqueous dispersion of depilatory agent (20 poises at 30.degree. C.).

This depilatory agent was coated on an underarm hair of each of 10 paneller (female adults) in an amount of about 700 g/m.sup.2. A water absorbing paper was adhered to the surface of the film and was allowed to stand for about 15 minutes. The water absorbing paper was peeled off and the film (water content: about 10 wt%) was then peeled off to remove the hair.

Any unpleasant odor due to the decomposition of the hair by the depilatory treatment was not substantially generated, and visual observation confirmed that skin irritation was not substantially produced.

A film was prepared in the same manner as in Example 7 except that the amount of the depilatory agent was reduced to about 200 g/m.sup.2. To this film was bonded a pressure-sensitive adhesive sheet comprising a 30 .mu.m thick polyethylene film and the same pressure-sensitive adhesive layer as in Example 3 provided on the polyethylene film to conduct the depilation treatment. The same good results as in Example 1 were obtained.

A water-soluble depilatory agent (80 poises at 30.degree. C.) consisting of 7% sodium thioglycolate, 1% of caustic soda and 77% of purified water was prepared.

This depilatory agent was coated on an underarm portion of each of 10 panellers in an amount of about 500 g/m.sup.2. A high water absorption polymer comprising a polyurethane foam (thickness: 0.8 mm) with a polyacrylic acid salt dispersed therein was bonded to the coated surface and was allowed to stand for about 10 minutes. The assembly was peeled off to remove the hair. The film contained about 30 wt% of water and the depilation effect was good as in Example 1.

A water-soluble depilatory agent (100 poises at 30.degree. C.) consisting of 5% calcium thioglycolate, 20% polyvinyl pyrrolidone, 2% calcium hydroxide, 1% silicon dioxide and 72% of distilled water was prepared.

This depilatory agent was coated on an underarm hair of each of 10 panellers in an amount of about 500 g/m.sup.2. A nonwoven fabric with a high water absorption polymer layer made of a starch/acrylic acid graft copolymer and having a thickness of 1,000 .mu.m formed on the surface thereof was bonded through a polymer layer and was allowed to stand for about 8 minutes. The assembly was peeled off to remove the hair. The film contained about 30 wt% of water, and the depilatory effect was good as in Example 1.

A composition consisting of the above components and a small amount of polyvinyl pyrrolidone was mixed with water to form a uniform polymer compound-containing emulsion (35 poises at 30.degree. C.). This depilatory agent was coated on a portion to be depilated in a thickness of about 100 to 300 .mu.m and allowed to stand for about 5 minutes, and the portion was treated by heating with a drier. In 5 minutes, a film was formed, and the hair was trapped in the film. Since the hair was reduced in strength or dissolved by the effect of the depilatory medicine, the film could be removed without any pain. Furthermore, the hair could be completely removed without leaving any residue.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.