JPH0140003B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an aerosol pack agent, and more particularly to an aerosol pack agent containing a copolymer of a vinyl alcohol monomer and an alkyl vinyl monomer in a specific ratio and a propellant. [Prior art and its problems] Film-forming pack agents (hereinafter simply referred to as "pack agents") are desirably ones that can form a uniform and thin paste-like layer from the viewpoints of how to use them and drying time of the film. be done. For this reason, the film forming agent is
They are required to have various properties, and the compounds that can be used are extremely limited. Conventionally, water-soluble gel substances, particularly polyvinyl alcohol polymers, have been used as film-forming agents in packs. However, when water-soluble polymers are incorporated into face packs at high concentrations, their viscosity increases, making it difficult to spread when applied to the skin.
It becomes difficult to obtain a thin uniform layer. Therefore, it has disadvantages in that it does not feel good during use and takes a long time to dry. On the other hand, to reduce the viscosity,
When the film forming agent is blended at a low concentration, the moisture content increases and drying becomes difficult. Therefore, it is possible to incorporate a solvent such as ethanol in order to improve the drying property, but it is not desirable to use more than 15% of the solvent because it may cause skin irritation. Furthermore, if the viscosity of the pack agent is lowered, it will tend to drip when it is applied to the skin, making it inconvenient to use. Furthermore, conventional masking agents that use such film-forming agents cannot be overcoated or corrected during use, are difficult to apply evenly, and typically take 20 minutes to dry.
There were drawbacks such as the time it took ~30 minutes. On the other hand, changes in the formulation of the pack itself are also being considered. That is, it is known that if a face pack is used in the form of a fast-breaking foam using an aerosol, the foam disappears quickly when applied to the skin, and a thin paste layer is easily formed. However, with conventional film-forming agents such as polyvinyl alcohol, it has been difficult to form rapidly breaking fine foams using ordinary propellants. [Means for Solving the Problems] Under these circumstances, the present inventors have developed a polyvinyl alcohol polymer as a film forming agent.
It was discovered that a vinyl alcohol/alkyl vinyl ether copolymer (PVA/AVE) in which the acetate ester is an alkyl ether has excellent film-forming ability, and a patent application was previously filed (Japanese Patent Application No. 1983-
No. 202273, Japanese Unexamined Patent Publication No. 60-94904). The present inventors further investigated the properties of the above copolymer and found that the viscosity of its aqueous solution was
It has been found that compared to PVA-based polymers, it is possible to form fine foams that are extremely low and break quickly using commonly used propellants. Therefore, the present invention mainly consists of a copolymer consisting of 98 to 80 mol% of vinyl alcohol monomer units and 2 to 20 mol% of linear or branched alkyl vinyl ether monomer units having 1 to 6 carbon atoms, and a propellant. The present invention provides an aerosol pack containing the present invention as an ingredient. The copolymer (PVA/AVE), which is one of the main components of the cosmetic composition of the present invention, can be represented by the following general formula (). (In the formula, R represents a linear or branched alkyl group having 1 to 6 carbon atoms, n represents the number of moles of the vinyl alcohol monomer, m represents the number of moles of the alkyl vinyl ether monomer, and the molar ratio n/m is 98 /2～80/
20). The copolymer used in the present invention
PVA/AVE, for example, is produced by copolymerizing vinyl acetate and alkyl vinyl ether according to a known method.
It is produced by a method such as substantially complete saponification. Examples of R in PVA/AVE represented by the general formula () include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n
Examples include alkyl groups such as -amyl, isoamyl, and n-hexyl, with n-butyl being particularly preferred in terms of the strength and flexibility of the resulting film. When R is H, the copolymer becomes the same copolymer as fully saponified PVA, and the aqueous solution turns into a gel, making it undesirable as a pack agent. On the other hand, when R has 7 or more carbon atoms, the solubility in water deteriorates, which is not preferable. In the present invention, the PVA/AVE used is
By changing the molar ratio n/m of vinyl alcohol monomer and alkyl vinyl ether monomer, it is possible to appropriately adjust the strength and flexibility of the resulting film, and various packs can be produced. In the present invention, n/m is 98/2
The range of ~80/20 is preferable, especially 95/5~85/
An extremely flexible film can be obtained within the range of 15. If (m/m+n)×100 is less than 2, it is not preferable because gelation of the aqueous solution occurs. on the other hand,
If (m/m+n)×100 exceeds 20, it is not preferable because the solubility in water becomes extremely poor. When the average molecular weight of PVA/AVE used in the present invention exceeds 200,000, the aqueous solution becomes cloudy, which is undesirable.On the other hand, when the average molecular weight is less than 30,000, it is soluble in water but has film-forming properties. This is not preferable because it results in a lack of Further, the propellant used in the present invention is not particularly limited in type, and examples thereof include compressed gases such as nitrogen gas, nitrous oxide gas, carbon dioxide gas, argon gas, dichlorodifluoromethane, trichloromonocarbon gas, etc. Fluoromethane, dichlorotetrafluoromethane, liquefied petroleum gas, etc. are used. These propellants can be used alone or in combination. To prepare the aerosol pack of the present invention,
A pack composition prepared from the above-mentioned PVA/AVE and optional ingredients described below may be filled into a pressure-resistant container, and a propellant may be enclosed and mixed therein. The amount of propellant is determined when the pressure at the time of spraying the aerosol pack is 20℃.
1 to 8 Kg/cm ² , preferably 2 to 7 Kg/cm ²
All you have to do is make it so that If this pressure is less than 1 kg/cm ^{2 ,} the pack agent composition will not foam and will be difficult to come out of the aerosol can. Also, the pressure is 8Kg/cm ²
If it exceeds the limit, the can will erupt violently, making it difficult to pick up and at the same time increasing the danger. Also,
The aerosol can used is preferably a double aerosol can in order to keep the pressure constant during ejection. In addition to the above-mentioned essential ingredients PVA/AVE and propellant, the aerosol pack agent of the present invention includes various commonly added ingredients such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, coating agents such as various gums, glycerin, Propylene glycol, polyethylene glycol, ethylene glycol, 1,3-butylene glycol,
Moisturizers such as dipropylene glycol, diglycerin, hexylene glycol; kaolin, talc, titanium oxide, iron oxide, zinc white, silicic anhydride,
Powders such as magnesium carbonate; oily ingredients such as olive oil, squalane, liquid paraffin, lanolin, and petrolatum; alcohol and purified water; and, if necessary, surfactants, medicinal agents, preservatives, fragrances, colorings, etc. may be appropriately blended. Can be done. Preferred compositions of the aerosol pack composition of the present invention include the following.

〔Example〕

Next, the present invention will be explained with reference to Examples and Reference Examples. Reference Example 1 Synthesis of vinyl alcohol/n-butyl vinyl ether copolymer: Vinyl acetate 172.2g (2.00 mol), n-butyl vinyl ether 15.1g (0.15 mol), methanol 56.2
g and 0.28 g of 2,2'-azobis2,4-dimethylvaleronitrile were mixed, and polymerization was carried out at 62° C. for 8 hours in an N ₂ atmosphere. Next, 749.2 g of 5% water-containing methanol and 8.0 g (0.20 mol) of caustic soda were added, and saponification was carried out at 45° C. for 2 hours. After pulverizing the reaction mixture, separate the polymer part,
Next, this was washed with 5% aqueous methanol to remove impurities such as sodium acetate. The purified polymer part is dried under reduced pressure and then crushed to produce white powdered vinyl alcohol/
n-Butyl vinyl ether (93/7 molar ratio) copolymer (hereinafter abbreviated as PVA/n-BVE) 82.5
I got g. The degree of saponification of the obtained copolymer was 99.1 mol%, the average molecular weight was 74,000, the residual sodium acetate was 0.12% by weight (hereinafter simply referred to as %), and the viscosity of the 15% aqueous solution (at 25°C) was
It was 960 cp. The average molecular weight was calculated as a polystyrene equivalent weight average molecular weight using gel permeation chromatography (GPC) after acetylating the obtained copolymer (the same applies to the synthesis examples and examples shown below). Reference Examples 2 to 5 Vinyl acetate (VAc), n-butyl vinyl ether (n-BVE), methanol, 2,2'-azobis2,4-dimethylvaleronitrile (Wako Pure Chemical V-
65), 5% aqueous methanol, caustic soda as the first
Copolymers of Reference Examples 2 to 5 listed in Table 1 were obtained in the same manner as in Reference Example 1 except that the weights shown in the table were used. However, in Reference Examples 2 and 3, the molar ratio m/n of the obtained copolymer is outside the range of the present invention, and in Reference Examples 4 and 5, the average molecular weight thereof is outside the range of the present invention.

【table】 Example 1 Aerosol pack: An aerosol pack having the following composition was prepared. (composition)

[Table] (Manufacturing method) Heat to 90°C and stir to homogenize. Then, add ,
Stir to homogenize. After cooling to about 35° C., the mixture is homogenized to obtain a composition for an aerosol pack. After filling an aerosol container with the composition obtained as above and attaching an aerosol valve,
Fill it with propellant and make it into a product. (Internal pressure 20℃,
(Adjusted to 3.5Kg/ ^cm2 ) When using product A of the present invention, the contents are quickly discharged due to the pressure of the propellant, and the foaming is sufficient, but comparative product B has a high viscosity and the contents are was difficult to spray, and the foaming was insufficient. Next, the results of examining the flow characteristics of the invention product A obtained above, the composition A' containing only the aerosol pack agent composition of the invention product A, and the comparative product B' containing only the composition of comparative product B, are shown in the first table. As shown in the figure. As is clear from these results, the product A of the present invention has low shear stress under each shear rate, little change in shear stress, and good spreadability when applied. It was also revealed that the fluidity was different from that of paste-like packs.

[Brief explanation of drawings]

Figure 1 shows inventive product A, composition A', and comparative product.
It is a drawing showing the flow characteristics of B'.

Claims (1)

[Claims] 1. Vinyl alcohol monomer units 98 to 80 mol%
and a copolymer consisting of 2 to 20 mol % of linear or branched alkyl vinyl ether monomer units having 1 to 6 carbon atoms, and an aerosol pack agent containing a propellant as main components. 2. The aerosol pack agent according to claim 1, wherein the copolymer has an average molecular weight of 30,000 to 200,000. 3 The molar ratio of vinyl alcohol monomer units and alkyl vinyl ether monomer units in the copolymer is
The aerosol pack according to claim 1, which has a molecular weight of 95/5 to 85/15. 4. The aerosol pack according to claim 1, which is filled with a propellant so that the pressure at the time of injection is 1 to 8 kg/cm ² . 5 Copolymer in composition for aerosol pack 1
The aerosol pack according to claim 1, which contains up to 40% by weight.