JPS625882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sunscreen. This sunscreen contains certain ammonium cinnamates. The agent can also be used in methods of protecting the skin from harmful ultraviolet radiation.

The above ammonium cinnamate has the general formula [Wherein, R is monoethanolamine, diethanolamine, triethanolamine, bis(2-
hydroxypropyl)amine or tris(hydroxymethyl)-ammonium ion of aminomethane].

The salts in the formula are exposed to the sun's erythematous ultraviolet radiation (i.e.
between 280μ and 320μ). In other words, it protects living epidermal cells from these rays.

Salts of the formula can be used as sunscreens.

Preferred salts of the formula are tris(hydroxymethyl)-methylammonium p-methoxy-cinnamate and especially diethanolammonium p-methoxy-cinnamate.

Salts of the above formula have considerable water solubility.
As a result, it is particularly suitable for incorporation into aqueous solutions or aqueous/alcoholic solutions or phases of cosmetic bases. Furthermore, the salts in the formula are neutral substances, so they do not irritate the skin at all.

Additionally, salts of the formula, especially diethanolammonium p-methoxy-cinnamate and tris(hydroxymethyl)methylammonium p-
Because of the low melting point of methoxy-cinnamate, it can be easily incorporated into cosmetic formulations. This is very advantageous from a technical point of view.

As noted above, within the scope of this invention are sunscreen agents which contain as an essential sunscreen component a salt of the formula.

A method for producing a sunscreen is to add a salt of the formula to a cosmetic base.

To provide the sunscreens of the invention, salts of the above formula can be mixed with conventional cosmetic bases having desirable physical and cosmetic properties. The sunscreen can take the form of a cream, lotion, emulsion, ointment, gel, solution, spray, stick, etc., for example. Of course, the light blocking activity depends on the cosmetic base used. The efficacy of the light-blocking activity also depends on the concentration of the salt of formula in the light-blocking agent. A suitable concentration is, for example, 1% to 6%, preferably 3%.
% to 5%.

Salts of the formula can also be used in combination with other conventional sunscreens, in which case a synergistic effect (ie synergistic effect) of the sunscreen activity may also occur.

monoethanolamine, diethanolamine,
Triethanolamine, bis(2-hydroxypropyl)amine or tris(hydroxymethyl)
Salts of the formula are prepared by converting p-methoxy-cinnamic acid into a salt using aminomethane.

It is preferable to use pure starting materials. Salt formation is preferably carried out by mixing equimolar amounts of each component together. Furthermore, the neutralization point can be determined, for example, by measuring PH using a glass electrode.

Salt formation is preferably carried out in a solvent. for example,
Suitable solvents are alkanols containing 2 to 7 carbon atoms, such as ethanol, n-propanol and preferably isopropanol.

Salt formation is preferably carried out at elevated temperatures (eg the boiling point of the solvent). At this temperature, as concentrated a solution of the components as possible is produced, after which the reaction mixture is cooled to precipitate the desired salt in crystalline form.

If necessary, the salts can be purified by recrystallization, and conventional decolorizing agents can also be used.

A 1% aqueous solution of the salt obtained by precise neutralization of the acid with an amine has a pH value of 6.8 to 7.

The following example is an example of the preparation of ammonium cinnamate used in the present invention.

Production example (A) 89.9 g (0.5 mol) of pure dry p-methoxysilica skin, 52.6 g (0.5 mol) of distilled diethanolamine and 188 ml of isopropyl alcohol,
Place in a round bottom flask equipped with a stirrer, reflux condenser and thermometer. The mixture is heated at reflux temperature for 1 hour. The mixture is filtered hot and cooled to room temperature with stirring, thereby causing crystallization. After 12 hours, the mixture is further cooled to 0°C and filtered. Wash the crystals with a small amount of cold isopropyl alcohol and
Dry in a vacuum drying facility at °C. There is thus obtained 125.6 g of diethanolamine ammonium p-methoxy-cinnamate (white crystals) having a melting point of 88°C to 88.5°C.

(B) by carrying out the method described in the previous paragraph using equimolar amounts of monoethanolamine, triethanolamine, bis(2-hydroxypropyl)amine or tris(hydroxymethyl)-aminomethane in place of diethanolamine. ,
monoethanol ammonium p-methoxy-cinnamate, each having a melting point of 154°C to 155°C;
Triethanolammonium p-methoxy-cinnamate, melting point 96°C to 96.5°C, melting point 73°C
bis(2-hydroxypropyl)ammonium p-methoxy-cinnamate at 74°C and tris(hydroxymethyl)methylammonium p-methoxy-cinnamate at 153.5°C to 154°C.

In the following examples, representative sunscreens containing salts of the formula are illustrated.

Example (a) A sunscreen gel may have the following composition: g diethanolammonium p-methoxy-cinnamate 5 Carbopol 940 (polyacrylic acid resin) 2 triethanolamine 3.5 distilled water 77 d-panthenol 0.5 95% Alcohol 12 Fragrances and solubilizers Sufficient amount (0.5 + 0.9) Preservatives Sufficient amount (0.2) (b) A nutritious cream (gel) with light-blocking activity may have the following composition: g diethanolammonium p-methoxy-cinnamate 3 Carbopol 940 1 Triethanolamine 1.9 d-panthenol 0.2 Distilled water 85.9 Amerchol L101 (lanolin derivative) 8 Flavoring agent and solubilizer Sufficient amount (0.3 + 0.9) Preservative Sufficient amount (0.2) (c) Rod-shaped with light-shielding activity The insect repellent may have the following composition: g diethanolammonium p-methoxy-cinnamate 3 stearic acid 4 palmitic acid 4 myristic acid 2 propylene glycol 37.6 Me´tadelphe´ne (m-toluic acid diethylamide) 20 Satol (oleyl alcohol) 3.7 Sodium hydroxide pellets (97%) 1.7 Distilled water 22 Flavor 2 Colorant Sufficient amount Preservative Sufficient amount The present invention includes the following embodiments.

A sunscreen as claimed in any of the claims, wherein the salt of formula (1) is present in an amount of from about 1% to about 6% by weight.

(2) diethanolammonium p- to the salt of formula
A sunscreen according to the claims, which is a methoxy-cinnamate.

Claims (1)

[Claims] 1. As an essential light-shielding component, the general formula (wherein R is monoethanolamine, diethanolamine, triethanolamine, bis(2-
A sunscreen comprising a salt having an ammonium ion of tris(hydroxypropyl)amine or tris(hydroxymethyl)-aminomethane).