JPH0463845B2 - - Google Patents

Description

[Detailed description of the invention]

A Technical Field of the Invention This invention relates to a novel cosmetic additive made of modified polyvinyl alcohol containing an alkyl sulfoxide group in the molecule, and more specifically to shampoos, conditioners, lotions, hair sprays, hair creams, etc. When added to cosmetics and treated with hair, it exhibits an outstanding hair finishing effect with excellent moisturizing feeling and good curl retention. This case relates to additives for cosmetics that give a moisturizing and smooth feel. B. Prior Art and its Problems Conventionally, many additives have been used or proposed in cosmetics for the purpose of imparting appropriate moisture to the hair or skin. For example, higher alcohols, lanolin, higher fatty acid esters,
Protein decomposition product, glycerin, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, hydroxyethylcellulose, sodium polyacrylate, carboxymethylcellulose,
Examples include polyisobutylene. However, these additives are not necessarily effective in terms of affinity for hair and skin and imparting moisture, and there is a desire for cosmetic additives that have greater affinity and provide a higher degree of moisture. C Structure, purpose, and effects of the present invention As a result of intensive research to develop a water-soluble polymer that can be blended into cosmetics and provide an excellent feeling of use, the present inventors discovered that an alkyl sulfoxide group has been incorporated into the molecule. The content of modified polyvinyl alcohol, especially alkyl sulfoxide groups (content of units containing alkyl sulfoxide groups based on the total amount of constituent units of the modified polyvinyl alcohol; hereinafter referred to as degree of modification) is 5 to 80 mol%, preferably 10 to 50 The present inventors have discovered that a cosmetic additive made of modified polyvinyl alcohol with a mol% content of 10% by mole is excellent for this purpose, and have completed the present invention. Conventionally, the concept of blending and using polyvinyl alcohol modified with an alkyl sulfoxide group in cosmetics has not been known at all. However, when the degree of modification of the alkyl sulfoxide group is high, especially when the degree of modification is 5 to 5,
It is said that a cosmetic containing a cosmetic additive consisting of 80 mol%, more preferably 10 to 50 mol% of modified polyvinyl alcohol has excellent moisturizing properties, has excellent affinity for the skin, and has good adhesive properties. Something unique was discovered. Furthermore, the additive for cosmetics of the present invention has both the excellent film-forming properties inherent to modified PVA and the ability to impart suspension and dispersion stability to cosmetics. Furthermore, even if the cosmetic additive of the present invention is regularly used on the skin,
It does not cause any adverse effects such as irritation. D More detailed description of the present invention The modified polyvinyl alcohol containing an alkyl sulfoxide group in the molecule of the present invention has the general formula

[Formula] Group (R ₁ is a lower hydrocarbon group, preferably an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms.)
Modified polyvinyl alcohol containing a group represented by, the corresponding alkyl vinyl sulfoxide is polyvinyl alcohol (hereinafter abbreviated as PVA)
It can be produced by an addition reaction on the hydroxyl groups of , or by saponifying a copolymer obtained by copolymerizing an alkyl vinyl sulfoxide with a vinyl ester such as vinyl acetate. Regarding these manufacturing methods, a patent application filed in 1983 related to the invention by the present inventors has been published.
-94669 and Japanese Patent Application No. 58-29956, among these methods, the latter method is more preferred because highly modified PVA with a high degree of polymerization can be easily obtained. First, alkyl vinyl sulfoxide
A method for causing an addition reaction to the hydroxyl groups of PVA will be explained. What is PVA used in the present invention?

[Formula] (R ₂ is H or a methyl group, preferably H.) A polymer having units such as homopolymers, ordinary copolymers, block copolymers, graft polymers, formals, butyralized polymers, etc. This includes all polymers such as post-reacted polymers. Among these, PVA obtained by polymerizing and saponifying vinyl esters such as vinyl acetate, or copolymerizing vinyl esters such as vinyl acetate with comonomers such as ethylene, alkyl vinyl ether, methyl acrylate, itaconic acid, maleic anhydride, etc. , PVA obtained by saponification is preferred. Since the unsaponified residual vinyl ester units of PVA consume the alkali compound of the catalyst used in the reaction with the alkyl vinyl sulfoxide, it is preferable that the degree of saponification of the vinyl ester units is high, and is 50 mol% or more, preferably 80 mol. % or more is desirable. Also these PVA
Alternatively, the degree of polymerization of PVA is not particularly limited, but is 200 to 4000, preferably 300 to 3000. There is no particular restriction on the form of PVA when reacting with alkyl vinyl sulfoxide; it may be in solution form, molten form,
Any material such as powder, film, fiber, foam, etc. may be used. Preferred examples of the alkyl vinyl sulfoxide include alkyl vinyl sulfoxides having an alkyl group having 1 to 10 carbon atoms, such as methyl vinyl sulfoxide, ethyl vinyl sulfoxide, butyl vinyl sulfoxide, cyclohexyl vinyl sulfoxide, and benzyl vinyl sulfoxide. Among them, lower alkyl vinyl sulfoxides having 1 to 4 carbon atoms such as methyl, ethyl, and butyl are preferred because of their good reactivity. The reaction between PVA and alkyl vinyl sulfoxide can be done in any manner as long as both substances can undergo a contact reaction.
There are no particular restrictions. However, usually a solution method involves reacting PVA with an alkyl vinyl sulfoxide in an aqueous solution, or, if PVA is water-insoluble, contacting it by immersing PVA in an aqueous solution containing an alkyl vinyl sulfoxide.
Regarding the reaction method, an aqueous reaction is preferable because the reaction rate is high. In addition, polar solvents such as dioxane, tetrahydrofuran, diethyl ether, acetone, dimethyl sulfoxide, dimethylformamide, and formamide can also be used. Other solvents can also be used as long as they do not inhibit the reaction. In the reaction between PVA and alkyl vinyl sulfoxide, an alkali, usually an alkali metal hydroxide, is used as a reaction catalyst, and sodium hydroxide and potassium hydroxide are particularly preferred. Also, the alkali concentration is
The molar ratio to the hydroxyl group of PVA is preferably 0.005 to 5, preferably 0.01 to 3. If the molar ratio is less than 0.005, the reaction rate will be low, and if the amount of alkali is too large, side reactions such as polymer decomposition or coloring will occur, which is not preferable. The reaction temperature and time are determined as appropriate, taking into consideration the desired reaction rate, shape retention of the reactants, etc., but from the viewpoint of an appropriate reaction rate and side reactions such as decomposition and coloring of the polymer, the reaction temperature should be set at 20 - 20°C. 100℃, preferably
30~85℃, reaction time 1 minute~10 hours, preferably
The duration is 30 minutes to 5 hours. After the reaction, the unreacted alkyl vinyl sulfoxide, catalyst, etc. are usually separated and purified by washing, etc., and then post-treated by drying. The amount of alkyl sulfoxide groups introduced can be controlled by adjusting the reaction conditions described above. Next, a method for saponifying a copolymer obtained by copolymerizing an alkyl vinyl sulfoxide and a vinyl ester such as vinyl acetate will be described. First, vinyl esters such as vinyl acetate are given the general formula

A polyvinyl ester copolymer can be obtained by mixing vinyl sulfoxide represented by the formula and a polymerization initiator and polymerizing the mixture. The polymerization method may be either a batch method or a continuous method, but in the case of a batch method, the monomer composition changes with the polymerization rate according to the comonomer reactivity ratio (γ ₁ , γ ₂ ). It is well known that the so-called semi-batch method, in which one or both monomers are added so that the monomer composition remains constant, is the best way to achieve a uniform copolymer composition. Desirable for obtaining polymers. In the case of continuous multi-column copolymerization, for the same reason, it is desirable to add monomers to the second and subsequent columns so that the monomer composition in each column is constant. As a polymerization initiator, 2,
2'-azobisisobutyronitrile (AIBN), 1,
1'-azobis-(cyclohexane-1-carbonitrile), 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile) ), 2,
2'-azobis-(2-amidinopropane) dibasic acid, benzoyl peroxide, potassium persulfate, ammonium persulfate, t-butyl hydroperoxide,
Known radical polymerization initiators such as peroxide di-t-butylcumene hydroperoxide and so-called redox initiators consisting of a peroxide and a reducing agent can be used. An appropriate temperature for the polymerization reaction is selected depending on the type of initiator, but 40 to 80°C is usually selected.
Further, a degree of polymerization regulator such as acetaldehyde or alkyl mercaptan can also be added to the polymerization system. The polymerization rate of the monomers is appropriately determined depending on the purpose, such as economical efficiency and adjustment of the degree of polymerization. In the present invention, bulk polymerization without using a solvent is preferred because of its high polymerization rate, but other methods such as solution polymerization, suspension polymerization, and emulsion polymerization can also be used. After the copolymerization is completed, if vinyl ester monomers such as vinyl acetate remain in the reaction solution, they must be separated and removed by distillation or the like. Even if vinyl sulfoxide remains, it is preferable to remove it, but in normal cases, the copolymerizability (γ ₂ ) of vinyl sulfoxide is higher than the copolymerizability (γ ₁ ) of vinyl ester monomers such as vinyl acetate. , the amount of vinyl sulfoxide remaining in the polymerization system is small. In carrying out such polymerization, in addition to vinyl ester monomers such as vinyl acetate and vinyl sulfoxide, other unsaturated monomers copolymerizable with these monomers, such as α- Olefin; Unsaturated acids such as (meth)acrylic acid, crotonic acid, maleic anhydride, fumaric acid, and itaconic acid or their alkyl ester salts; Unsaturated amides such as (meth)acrylamide and N-methylolacrylamide; 2-acrylamide- It is free to coexist with a sulfonic group-containing monomer such as 2-methylpropanesulfonic acid or a salt thereof in an amount that does not impair the properties of the modified PVA of the present invention. Next, modified PVA is produced by the following method. That is, it can be obtained by saponifying a polyvinyl ester copolymer such as modified polyvinyl acetate obtained by the above method using a conventional method. It is usually advantageous to carry out the saponification reaction as a solution of the copolymer in alcohol, especially in methanol. Not only anhydrous alcohols but also those containing a small amount of water can be used depending on the purpose, and organic solvents such as methyl acetate and ethyl acetate may be optionally contained. As the saponification catalyst, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alcoholates such as sodium methylate and potassium methylate, alkaline catalysts such as ammonia, or acidic catalysts such as hydrochloric acid and sulfuric acid can be used. Industrially, alkaline catalysts, especially sodium hydroxide, are also desirable. The saponification temperature is usually selected from the range of 10 to 50°C. Regarding the modified PVA obtained in this way, the content of alkyl sulfoxide groups (degree of modification) is 5 to 80.
A mole %, preferably 10 to 50 mole % is desirable. 5
If the amount is less than mol%, the resulting cosmetic containing the cosmetic additive will not have sufficient wettability. The degree of modification is more preferably 10 mol% or more. On the other hand, if the degree of modification is too high, a cosmetic containing the resulting cosmetic additive may have a sticky feel, so it is more desirable that the degree of modification is 80 mol% or less, preferably 50 mol% or less. There are no particular restrictions on the polymerization degree and saponification degree (vinyl alcohol units/(vinyl alcohol units + vinyl ester units)) of modified PVA, but a polymerization degree of 200 or higher is preferable from the viewpoint of film-forming properties in cosmetics. In the case of dispersion type cosmetics such as, it is desirable to use partially saponified products with a low degree of saponification. Usually the degree of polymerization is 200 to 4000, preferably 300.
~3000, desirably a saponification degree of 50 mol% or more. In addition, in addition to the alkyl sulfoxide group-containing unit, vinyl alcohol unit, and vinyl ester group, the modified PVA of the present invention may contain other ionic hydrophilic groups, hydrophobic groups, etc. to improve the effect of the cosmetic additive of the present invention. There is no problem as long as it does not disappear. In particular, it is preferable to coexist a small amount of a cationic group since this can impart adsorption properties to the skin and hair as a cosmetic additive. The additive for cosmetics made of modified PVA of the present invention is dissolved in water or a mixed solvent of water and alcohol, and then incorporated into cosmetics to provide an excellent feeling of use and finish. The reason why such performance is exhibited has not been fully elucidated, but due to the action of the alkyl sulfoxide group in the modified PVA that constitutes the present invention, it has a high affinity for hair and skin when used as a cosmetic. to have,
Furthermore, it is presumed that PVA's inherent film-forming properties and moisturizing effects, or suspension and dispersion stability, work synergistically. EXAMPLES Below, examples will be used to explain cosmetics in which the cosmetic additive made of modified PVA containing an alkyl sulfoxide group of the present invention is blended into shampoos and hand creams. In addition, in the following, parts mean parts by weight. (a) Modification containing an alkyl sulfoxide group
Synthesis Example 1 of PVA 845 parts of a 5.2% aqueous solution of PVA with a degree of polymerization of 1750 and a degree of saponification of 98.2 mol % was placed in a reaction vessel equipped with a stirrer and a thermometer, and the temperature was raised to 60° C. while stirring.
Add 400 parts of a 10% sodium hydroxide aqueous solution to this (molar ratio of sodium hydroxide to the hydroxyl group of PVA is 1.0), and then add methyl vinyl sulfoxide.
After adding 90 parts, the mixture was reacted at 60° C. for 5 hours with stirring. After the reaction vessel was cooled from the outside and the reaction solution was cooled to 25° C., the reaction solution was poured into a large amount of methanol, and the precipitated modified polymer was separated. The polymer was further thoroughly washed with methanol to remove the catalyst and unreacted methyl vinyl sulfoxide, and then dried at 70°C for 5 hours. The weight of the obtained polymer was 55 parts, and the infrared absorption spectrum of this polymer showed an absorption based on sulfoxide at 1010 cm ^-1 and an absorption at 1100 cm -1.
Absorption based on the secondary alcohol of vinyl alcohol was observed in ^-1 , and this polymer was found to be modified PVA modified with methyl vinyl sulfoxide. Furthermore, when the polymer was dissolved in heavy water and subjected to proton nuclear magnetic resonance spectroscopy, it was found that the hydroxyl group of vinyl alcohol decreased, the absorption of methyl proton of methyl sulfoxide was observed at 2.5 ppm, and the vinyl group of methyl vinyl sulfoxide Since no proton signal was observed, it was found that the reaction was an addition reaction of the vinyl group of methylvinyl sulfoxide to the hydroxyl group, resulting in modified PVA with a methyl sulfoxide group introduced. According to the results of S elemental analysis, the degree of modification of the methyl sulfoxide unit is 14.3.
It was found that mol%. (b) Modification containing an alkyl sulfoxide group
Synthesis Example 2 of PVA 1000 parts of vinyl acetate and 20 parts of ethyl vinyl sulfoxide were placed in a flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser.
After replacing the inside of the system with nitrogen, the internal temperature was raised to 60°C. A solution of 13 parts of 2,2'-azobisisobutyronitrile dissolved in 100 parts of methanol was added to this system to initiate polymerization. During the polymerization time of 5 hours, 182 parts of a 25% methanol solution of ethyl vinyl sulfoxide was added dropwise at a constant rate. The solid content concentration in the system at the time of termination of polymerization was 35%. A gas inlet tube and a vacuum distillation device were attached to the flask, and methanol vapor was blown into the polymerization reaction solution under reduced pressure to drive out unpolymerized vinyl acetate monomer, and a 33% methanol solution of the copolymer was obtained. It was confirmed by nuclear magnetic resonance analysis that this copolymer contained 14 mol% of ethyl vinyl sulfoxide units and 86 mol% of vinyl acetate units.
While stirring 100 parts of this copolymer methanol solution at 40° C., 10 parts by volume of a 1N caustic soda methanol solution was added thereto, and after thorough mixing, the mixture was allowed to stand. After 30 minutes, the solidified polymer was pulverized using a pulverizer, washed with methanol, and dried to obtain a polymer powder. When this copolymer was dissolved in water and its viscosity was measured at 30°C, it was 0.2 dl/g. Proton nuclear magnetic resonance spectroscopy analysis of a heavy aqueous solution of this copolymer revealed that the ethyl vinyl sulfoxide unit was
It was analyzed to be 14 mol%. The degree of saponification of vinyl acetate units was 97 mol%. Example 1 and Comparative Examples 1 and 2 (Shampoo Composition) 100 parts of an aqueous shampoo composition for hair was prepared using the modified PVA obtained in Synthesis Example 1 and having a degree of modification of alkyl sulfoxide groups of 14.3 mol % according to the following formulation. I got it. 80.8 parts of purified water, 12 parts of sodium trioxyethylene lauryl ether sulfate,
3 parts of sodium lauryl sulfate, 2 parts of coconut oil fatty acid diethanolamide, 1.5 parts of the above-mentioned alkyl sulfoxide group-modified PVA, 0.7 parts of fragrance, and 200 ml of a sample solution prepared by diluting this shampoo aqueous composition 10 times with water. 15cm long) 5g was immersed for 2 minutes, massaged, rinsed 3 times with 200ml of water, lightly drained, and air-dried at 20℃ and 60% RH.
I observed the condition of my hair. Table 1 shows the results of evaluating the shampoo condition and hair finish. For comparison, 1.5 parts of unmodified PVA with a saponification degree of 98 mol% and a 4% aqueous solution having a viscosity of 28.0ep at 20°C was used in place of the above-mentioned modified PVA (Comparative Example 1).
Alternatively, a shampoo aqueous composition was obtained in the same manner as in Example 1, except that 2 parts of glycerin was used (Comparative Example 2), and the same evaluation was performed. The results are also shown in Table 1.

[Table] Examples 2 and 3 (Shampoo composition) Shampoo was prepared in the same manner as in Example 1, except that modified PVA with a different degree of modification synthesized according to Synthesis Example 1 was used in place of the modified PVA in Example 1. A composition was obtained and evaluated. The evaluation results are also shown in Table 2.

[Table] Example 4 and Comparative Example 3 (hand cream composition) 13 parts of liquid paraffin, 2 parts of cetyl alcohol,
A hand cream composition was prepared by blending 1 part of isopropyl palmitate, 4 parts of propylene glycol, 1 part of stearic acid-triethanolamine, and 2 parts of modified PVA synthesized in Synthesis Example 2 (Example 4). For comparison, Comparative Example 1 was used instead of modified PVA.
A hand cream composition was prepared using the same formulation as in Example 4, except that the PVA used in Example 4 was used (Comparative Example 3). As a result of applying and evaluating both hand cream compositions to the skin, Comparative Example 3 had a sticky feeling, whereas Example 4 had no sticky feeling and had an excellent feeling of use in terms of moisturizing and smoothness. A sense of completion was obtained.

Claims (1)

[Scope of Claims] 1. A cosmetic additive comprising modified polyvinyl alcohol containing an alkyl sulfoxide group in the molecule. 2. The additive for cosmetics according to claim 1, wherein the modified polyvinyl alcohol containing an alkyl sulfoxide group is a modified polyvinyl alcohol obtained by addition-reacting an alkyl vinyl sulfoxide to a hydroxyl group in the polyvinyl alcohol. 3. The additive for cosmetics according to claim 1, wherein the modified polyvinyl alcohol containing an alkyl sulfoxide group is a saponified copolymer of an alkyl vinyl sulfoxide and a vinyl ester. 4. The cosmetic additive according to claim 1, wherein the content of units containing alkyl sulfoxide groups is 5 to 80 mol% based on the total constituent units of the modified polyvinyl alcohol.