Method for predicting safety of surfactant, method for predicting safety of cosmetics, and method for producing cosmetics

Abstract

To provide a method for predicting safety of a surfactant, capable of improving reliability in prediction of safety for a surfactant, a method for predicting safety of cosmetics and a method for producing cosmetics.SOLUTION: A method for predicting safety of a surfactant performs a prediction based on predetermined reference information defined for a substance or substance group whose safety information is known, and hydrophobicity information derived from the hydrophobicity of the surfactant.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for predicting the safety of surfactants, a method for predicting the safety of cosmetics, and a method for manufacturing cosmetics.

Background Art

[0002] Conventionally, in the cosmetics industry and the like, for cosmetics, medical products, etc. whose safety has not been clarified, safety evaluations have been carried out by actually using them on humans. However, not only is it sometimes difficult to obtain the consent of the subjects, but there is also a limit to the number of human specimens. For this reason, tests that can evaluate safety without relying on tests on humans have been studied. In addition, although there are animal experiments as tests that do not rely on humans for cosmetics, medical products, etc., in recent years, due to the progress of regulations and the like, alternative methods have attracted attention.

[0003] On the other hand, for example, in Patent Document 1, in order to predict the safety of a test substance in a predetermined safety test, it has been proposed to specify a prediction range such as a high safety range based on the value of the Hansen Solubility Parameter (HSP).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding surfactants formulated in cosmetics, medical products, etc., highly reliable safety prediction results are particularly desired for both existing and newly developed surfactants in the future.

[0006] The present invention has been made in view of the above actual situation, and an object thereof is to provide a method for predicting the safety of a surfactant and the like that can improve the reliability in predicting the safety of a surfactant. [Means for Solving the Problems]

[0007] As a result of intensive efforts, the present inventors, when using information determined for substances or groups of substances for which information on safety is known, use information determined for the overall properties of surfactants for which safety has not been clarified or information derived from the hydrophilicity of surfactants. It was first found that a more reliable result can be obtained when evaluating safety by focusing on hydrophobic information derived from the hydrophobicity of the surfactant than when evaluating safety based on the relationship of affinity such as solubility. Through further repeated studies, the present invention has been completed.

[0008] That is, the present invention comprises the following means. [1] A method for predicting the safety of a surfactant, which predicts the safety of the surfactant based on predetermined reference information determined for a substance or group of substances for which information on safety is known and hydrophobic information derived from the hydrophobicity of the surfactant.

[0009] [2] The method for predicting the safety of a surfactant according to the above item [1], which predicts the safety of the surfactant by determining the affinity with the surfactant using the predetermined reference information and the hydrophobic information.

[0010] [3] The method for predicting the safety of a surfactant according to the above item [2], wherein the determination of the affinity is made based on information indicating the polarity of each of the predetermined reference information and the hydrophobic information.

[0011] [4] The method for predicting the safety of a surfactant according to the above item [3], wherein the determination of the affinity is made based on information on the dispersion force term, the dipole-dipole force term, and the hydrogen bonding force term in the Hansen solubility parameter of each of the predetermined reference information and the hydrophobic information.

[0012] [5] The predetermined reference information is a method for predicting the safety of the surfactant according to any one of items [1] to [4] above, which is determined based on information on safety and information indicating polarity for a plurality of types of substances.

[0013] [6] The predetermined reference information is a method for predicting the safety of the surfactant according to item [5] above, which is determined based on information on safety and information on the dispersion force term, dipole-dipole force term, and hydrogen bonding force term in the Hansen solubility parameter for a plurality of types of substances.

[0014] [7] The determination of safety is a method for predicting the safety of the surfactant according to any one of items [1] to [6] above, which is a determination of irritation to the skin.

[0015] [8] The determination of irritation to the skin is a method for predicting the safety of the surfactant according to item [7] above, which is a determination related to primary skin irritation.

[0016] [9] The surfactant is an ionic surfactant, which is a method for predicting the safety of the surfactant according to any one of items [1] to [8] above.

[0017]

[10] A method for predicting the safety of cosmetics, which predicts the safety of cosmetics containing a surfactant based on the method for predicting the safety of the surfactant according to any one of items [1] to [9] above.

[0018]

[11] A method for manufacturing cosmetics, which manufactures cosmetics using a surfactant whose safety has been determined by the method for predicting the safety of the surfactant according to any one of items [1] to [9] above.

Advantages of the Invention

[0019] According to the method for predicting the safety of the surfactant in [1], it becomes possible to enhance the reliability in predicting the safety of the surfactant.

[0020] According to the method for predicting the safety of surfactants from [2] to [9], it becomes possible to further enhance the reliability in predicting the safety of surfactants.

[0021] According to the method for predicting the safety of cosmetics in

[10] , it becomes possible to enhance the reliability in predicting the safety of cosmetics.

[0022] According to the method for manufacturing cosmetics in

[11] , it is possible to obtain cosmetics with high reliability regarding safety.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0024] Embodiments of the present invention will be described below with examples.

[0025] The method for predicting the safety of a surfactant according to one embodiment predicts the safety of a surfactant based on predetermined reference information determined for a substance or group of substances for which information regarding safety is known, and hydrophobic information derived from the hydrophobicity of the surfactant.

[0026] (Surfactant) As the surfactant whose safety is to be predicted, it is an amphiphilic molecule having both a hydrophilic moiety (hydrophilic group) and a lipophilic moiety (hydrophobic group) in the molecule. Examples thereof include ionic surfactants such as anionic surfactants, cationic surfactants, and amphoteric surfactants, and nonionic surfactants. Among them, it is preferably an ionic surfactant in that the reliability of safety prediction when focusing on the hydrophobic group is more likely to be improved compared to the case of focusing on the entire surfactant.

[0027] (Safety) The safety predicted in the safety prediction method is not particularly limited. For example, a human patch test (a test for judging skin irritation, which artificially causes percutaneous absorption by applying a composition containing a surfactant to the skin and evaluates whether artificial contact dermatitis occurs) can be mentioned. This human patch test includes a human patch test for judging skin primary irritation performed by single application of the surfactant to the skin, a human patch test for judging continuous irritation performed by multiple applications of the surfactant to the skin, and the like. Note that all human patch test methods are known, and skin transient irritation is preferably evaluated by a human patch test known, for example, as a method for evaluating skin transient irritation of a cosmetic preparation. The evaluation may be made based on the ratio of subjects in whom redness is confirmed in the human patch test, or may be made based on a predetermined skin irritation index grasped by the human patch test.

[0028] The method for predicting the safety of surfactants predicts safety using predetermined reference information determined for substances or groups of substances for which safety-related information is known, and information regarding the properties of surfactants for which safety-related information is not clear. Here, substances or groups of substances for which safety-related information is known in order to determine the former information, the predetermined reference information, are substances or groups of substances for which safety-related information obtained as a result of performing a safety evaluation such as a human patch test (such as a skin transient irritation human patch test) is known. The substances used in determining the predetermined reference information are one or more types, and from the viewpoint of enhancing the reliability of prediction, it is preferably two or more types, more preferably five or more types, and even more preferably ten or more types. The substances for which safety-related information is known are not particularly limited, and may be those used as raw materials for cosmetics, or may be of types other than surfactants. The predetermined reference information may be information determined for substances or groups of substances known to have safety such as skin transient irritation higher than a predetermined standard, but it is preferably information determined for substances or groups of substances known to have safety such as skin transient irritation lower than a predetermined standard.

[0029] In the method for predicting the safety of surfactants, as described above, safety is predicted using hydrophobicity information derived from the hydrophobicity in surfactants for which safety-related information is not clear. Instead of using information on the properties of the entire surfactant, or information derived from the hydrophilicity in the surfactant, by using hydrophobicity information related to the hydrophobicity in the surfactant, the reliability in predicting safety can be enhanced. Here, the hydrophobicity information derived from the hydrophobicity in the surfactant is not information determined only by the type of hydrophobic group in the surfactant, but is rather information derived from the hydrophobicity premised on the surfactant (information in which information derived from the hydrophilicity that affects the polarity of the surfactant is not omitted).

[0030] In the method for predicting the safety of a surfactant, the safety of the surfactant is predicted by evaluating the affinity with hydrophobicity in the surfactant for a substance or group of substances for which information on safety is known, using predetermined reference information and hydrophobicity information. Here, for example, when the information determined for a substance or group of substances known to have a safety lower than a predetermined standard is used as the predetermined reference information, if the affinity with the surfactant is high, it is predicted that the safety is low, and if the affinity with the surfactant is low, it is predicted that the safety is high. Further, regarding the affinity, not only the presence or absence thereof may be evaluated, but also the degree (high affinity or low affinity) may be evaluated.

[0031] The affinity is mainly the affinity of the hydrophobic group portion in the surfactant for a substance or group of substances for which information on safety is known, and is not particularly limited, but for example, it is preferably evaluated based on mutual solubility. For example, regarding the evaluation of solubility, known solubility parameters for a substance or group of substances for which information on safety is known are adopted as the predetermined reference information, and solubility parameters mainly for the hydrophobic group portion in the surfactant are adopted as the hydrophobicity information, and the determination of solubility is made based on these solubility parameters as the predetermined reference information and the solubility parameters as the hydrophobicity information. The determination based on such solubility parameters can be made based on at least one of the three parameters in the value of the Hansen Solubility Parameter (HSP). The three parameters of the HSP value are the three of "δd", "δp", and "δh". Among these parameters, "δd" is the dispersion force term, which is a parameter of non-polar interaction generated from the van der Waals interaction possessed by almost all substances. "δp" is the dipole-dipole force term, which is a parameter based on dipole-dipole interaction. "δh" is the hydrogen bond force term, which is a parameter based on the interaction by hydrogen bond. Among the three parameters in the HSP value, it is preferable to evaluate solubility based on two of the dipole-dipole force term and the hydrogen bond force term, which are information indicating polarity, and it is more preferable to evaluate solubility using all three parameters.

[0032] Note that the acquisition of HSP values is not particularly limited, and it may be obtained as information known for each substance or information obtained by a known specific method. As a method for calculating HSP values, for example, a method for calculating solubility parameters using solubility evaluation, a method for calculating solubility parameters using physical property values, and a method for calculating solubility parameters by the group contribution method can be preferably used. As a method for calculating solubility parameters using solubility evaluation, there is a method using the Hansen Solubility Sphere method. As solubility parameters using physical property values, there are methods using a calculation method using heat of vaporization ΔH, a calculation method using surface tension, a calculation method using refractive index, and a calculation method using activation energy of viscosity. As a method for calculating solubility parameters by the group contribution method, there are the Fedors' calculation method, the van Kreveren & Hoftyzer's calculation method, the Hoy's calculation method, and the Stefanis & Panayiotou's calculation method.

[0033] In this method for predicting the safety of surfactants based on HSP values, the HSP values determined for substances or groups of substances for which information on safety is known are used as predetermined reference information, the HSP values derived from the hydrophobicity in surfactants for which information on safety is not clear are used as hydrophobicity information, and the safety is predicted using the predetermined reference information and the hydrophobicity information. For example, for a surfactant for which safety prediction is to be performed, when the position coordinates (corresponding to "hydrophobicity information") determined by the HSP values derived from the hydrophobicity in the surfactant are within the range of the position coordinate range (corresponding to "predetermined reference information") of the HSP values determined for substances or groups of substances known to have a safety lower than a predetermined standard, it is predicted that the safety is low, and when it is outside the range of the position coordinate range of the HSP values that are the predetermined reference information, it is predicted that the safety is high. Note that the position coordinates of HSP values may be two-dimensional position coordinates determined by δp (dipole-dipole force term) and δh (hydrogen bonding force term) which are information indicating polarity, or may be three-dimensional position coordinates determined including δd (dispersion force term).

[0034] When adopting Hansen solubility spheres based on HSP values determined for a group of substances with low safety as specified reference information, for example, obtain the HSP values of a plurality of substances for which information on the level of safety is known, and include a plurality of substances known to have a safety level lower than a predetermined standard while excluding a plurality of substances known to have a safety level higher than the predetermined standard, and identify a virtual minimum sphere (Hansen solubility sphere) in the three-dimensional space of HSP values at the position coordinates. (Accordingly, the center coordinates of the sphere can be obtained.) Further, use the radius (interaction radius) of the Hansen solubility sphere thus determined as a reference value for the distance of the position coordinates in the three-dimensional space of HSP values to predict safety. More specifically, it is preferable to predict safety based on whether a substance is located inside the Hansen solubility sphere in the three-dimensional space of HSP values. When the concentration of the substance is different, although the HSP value of the substance itself does not change, it will affect the prediction of safety due to changes in the radius of the Hansen solubility sphere, etc.

[0035] Note that the method for obtaining the above-mentioned Hansen solubility sphere is known, and the technique is also disclosed in the following literature. □C. M. Hansen et al., Prog. Org. Coating, 51, 109 - 112, (2004), Polymer additives and solubility parameters □C. M. Hansen et al., Carbon, 42, 1591 - 1597, (2004), Using Hansen solubility parameters to correlate solubility of C60 fullerene in organic solvents and in polymers □C. M. Hansen, Hansen Solubility Parameters: A User’s Handbook; CRC Press: 1999

[0036] When using Hansen solubility spheres as the above hydrophobicity information, after identifying the Hansen solubility sphere based on the information derived from the hydrophilicity in the surfactant and the Hansen solubility sphere based on the information derived from the hydrophobicity as the hydrophobicity information, the δd, δp, and δh that are the center of the Hansen solubility sphere based on the latter hydrophobicity information are adopted.

[0037] Incidentally, the methods for obtaining the above two Hansen spheres (the Hansen solubility sphere based on the information derived from hydrophilicity and the Hansen solubility sphere derived from hydrophobicity) are well-known, and for example, the techniques are also disclosed in the following literature. S. Abbott, C. M. Hansen, and H. Yamamoto, Hansen Solubility Parameters in Practice Complete with eBook, software and data 5th Edition, 2015. □Agata Y, Yamamoto H (2018) Determination of Hansen solubility parameters of ionic liquids using double-sphere type of Hansen solubility sphere method. Chem Phys □Manuel Diaz de los Rios, Extending Microsoft excel and Hansen solubility parameters relationship to double Hansen’s sphere calculation

[0038] As described above, the safety of a surfactant is predicted by determining its affinity with a surfactant using predetermined reference information and hydrophobicity information. When using HSP values, the predetermined reference information corresponds to the Hansen solubility sphere described above, and the hydrophobicity information corresponds to δd, δp, and δh, which are the centers of the Hansen solubility spheres based on hydrophobicity described above. Then, the prediction of the safety of the surfactant by determining its affinity is that if the center of the Hansen solubility sphere, which is the hydrophobicity information, is within the range of the Hansen solubility sphere of the predetermined reference information, a high affinity and low safety are predicted, and if the center of the Hansen solubility sphere, which is the hydrophobicity information, is outside the range of the Hansen solubility sphere of the predetermined reference information, a low affinity and high safety are predicted. In this case, it is preferable to determine the affinity and predict the safety based on the information indicating polarity (the dipole-dipole force term δp and the hydrogen bonding term δh), and it is more preferable to determine the affinity and predict the safety based on the dipole-dipole force term δp, the hydrogen bonding term δh, and the dispersion force term δd.

[0039] The method for predicting the safety of the surfactant according to the above-described embodiment predicts using physical properties such as HSP values derived from the hydrophobicity of the surfactant and physical properties such as HSP values of substances with known safety. Therefore, prediction is possible without relying on human tests or animal experiments, and the reliability of the prediction can be enhanced.

[0040] Alternatively, instead of the method for predicting the safety of a surfactant, based on the above-described method for predicting the safety of a surfactant, the safety of a cosmetic containing a surfactant whose safety has been predicted may be predicted. Specifically, for a cosmetic containing a surfactant predicted to have high safety, it may be predicted that the safety is high, or for a cosmetic containing a surfactant predicted to have low safety, it may be predicted that the safety is low. Examples of such cosmetics include hair treatment agents such as shampoos and treatments.

[0041] In addition, when manufacturing cosmetics, the surfactants whose safety has been determined by the above surfactant safety prediction method may be used to manufacture cosmetics. Specifically, the surfactants predicted to have high safety by the surfactant safety prediction method may be used to manufacture cosmetics.

Examples

[0042] Examples related to the present invention will be described in detail below.

[0043] (Evaluation of Skin Primary Irritation by Known HSP Values and Human Patch Tests Based on Known Literature) The following Table 1 shows the "presence or absence of skin primary irritation" and the known "HSP values".

Table 1

[0044] Regarding the "presence or absence of skin primary irritation" in Table 1 above, those with a positive reaction rate of 5% or more in the human patch tests described in the following References 1 to 5 were evaluated as "present", and those with a positive reaction rate of less than 5% were set as "absent" (note that the evaluation criteria for determining the "presence" or "absence" of skin primary irritation can be arbitrarily set. In this example, 5% is used as the standard, but for example, when 10% is used as the standard, the safety estimation is lower compared to 5% or 6%. This is because even a positive rate of 5% or 6% results in a judgment of "absence" of skin primary irritation). The known HSP values are the values possessed by the known HSP value analysis software.

[0045] References 1 to 5 (described below in the order of author, title, journal, volume number, page, publication year, data description page) Reference 1: Tarō Kawamura, 3rd Patch Test Research Society, Allergy, 17(8), 676 - 691, 1968, 678 - 679 Reference 2: Takeshi Hashimoto, On the Clinical Significance of the Patch Test, Skin, 12(1), 23 - 26, 1970, 24 Literature 3: Ministry of Health, Labour and Welfare, Research Report on the Collection of Medical Findings Related to Occupational Diseases, Target Disease 1: Diseases for Which Continued Information Collection Was Required at the Special Committee on Article 35 of the Enforcement Regulations of the Labour Standards Act, Material 2, 1-239, Unknown Year, 40 (Public URL "https: / / www.mhlw.go.jp / content / 11201000 / 000748736.pdf") Literature 4: Ritsuko Hayakawa, Human Close Patch Test, Skin, 26(5), 1119-1127, 1975, 1121-11222 Literature 5: Ida Duarte, Rosana Lazzarini, Roberta Buense, Interference of the position of substances in an epicutaneous patch test battery with the occurrence of false-positive results, American Journal of Contact Dermatitis 13(3),125-132,2002,129

[0046] ((Specified Hansen lysing sphere of samples determined to have "positive" skin primary irritation in the specified reference information)) For each sample with a known HSP value, it was plotted on a three-dimensional coordinate at the HSP value, and a sphere on the three-dimensional coordinate that encloses all samples with "positive" skin primary irritation found by the human patch test and does not include samples with "negative" skin primary irritation found by the human patch test was specified as the Hansen lysing sphere serving as the evaluation criterion.

[0047] The Hansen lysing sphere serving as the evaluation criterion is shown in Figure 1. In Figure 1, samples with "positive" skin primary irritation are shown as round plots, and samples with "negative" skin primary irritation are shown as square plots. Also, the HSP coordinates at the center of the Hansen lysing sphere are shown as round plots. The HSP coordinates at the center of the Hansen lysing sphere were calculated by the above-described Hansen lysing sphere method. The HSP values and the like, which are the center coordinates of the Hansen lysing sphere serving as the evaluation criterion, are shown in Table 2 below. Note that the units of δd, δp, and δ are MPa 1 / 2It is also. R0 means the interaction radius which is the radius of the Hansen solubility sphere serving as the evaluation criterion. [Table 2]

[0048] (Regarding the confirmation of the actual skin irritation of surfactants) In order to confirm the consistency between the actual results and the predicted results of the skin primary irritation of surfactants, for each surfactant as the test substance, the skin irritation index was calculated as follows. Specifically, the surfactant as the test substance was sealed in a state of being directly applied to the skin of the arms or backs of a plurality of test subjects, and after 24 hours, the seal was peeled off. The presence or absence of skin redness 1 to 2 hours after peeling and the presence or absence of skin redness 24 hours after peeling were visually confirmed, and the reaction with stronger redness was taken as the evaluation target. Then, those with no reaction were rated as "0 points", those with slight erythema confirmed were rated as "0.5 points", those with obvious erythema confirmed were rated as "1.0 points", those with edema or papules confirmed in addition to erythema were rated as "2.0 points", and those with small blisters confirmed in addition to erythema and edema or papules were rated as "3.0 points". As shown in the following formula, the percentage of the value obtained by dividing the sum of the scores of each test substance by the number of test subjects was used as the skin irritation index. Skin irritation index = sum of scores / number of test subjects × 100

[0049] Note that as the surfactant as the test substance, sodium lauryl sulfate, sodium tetradecene sulfonate, sodium lauryl-6-carboxylate, disodium lauryl sulfosuccinate, lauramidopropyl betaine, isostearamidopropyl betaine, sodium lauroamphoacetate, and decyl glucoside were used respectively.

[0050] (Regarding the predictability based on the overall HSP value of surfactants) Next, for each surfactant as the test substance, the HSP value in the whole surfactant was determined. Here, in order to confirm the compatibility of a substance with a known HSP value with a surfactant whose HSP value is unknown, the two were mixed and separated into a good solvent, which is a substance soluble in the surfactant, and a poor solvent, which is a substance insoluble and separated from the surfactant. Specifically, an aqueous surfactant solution was prepared by diluting the surfactant with purified water so that the pure content was 20% by weight. For 0.05 ml of this aqueous surfactant solution, 5 ml of the pure solvents of the substances with known HSP values were added respectively to examine the compatibility. Next, these substances with known HSP values were plotted on a three-dimensional coordinate in terms of HSP values, and a dissolution sphere on the three-dimensional coordinate that encloses all the substances that are good solvents and does not include the substances that are poor solvents was identified as a Hansen dissolution sphere using known HSP value analysis software. Then, the central coordinates of the Hansen dissolution sphere were determined as the HSP value of the surfactant.

[0051] Note that the substances with known HSP values used to determine the HSP value of the surfactant were the pure solvents of sodium dodecyl sulfate, hexane, acetone, ethanol, N-methyl-2-pyrrolidone (NMP), pyridine, benzyl alcohol, N-methylformamide, 1,1,2,2-tetrabromoethane, methyl isobutyl ketone (MIBK), propylene glycol monoethyl ether, aniline, nitrobenzene, 1-butanol, toluene, tetrahydrofuran (THF), salicylaldehyde, o-dichlorobenzene, 1-methylnaphthalene, dimethyl sulfoxide (DMSO), and chloroform.

[0052] Next, Ra, which is the distance between the overall HSP value of each surfactant obtained as described above and the HSP value of the central coordinates of the Hansen dissolution sphere of the above evaluation criteria, was determined by the following formula. Ra = 4×(δ d1 - δ d2 ) 2 + (δ p1 - δ p2 ) 2 + (δ h1 - δ h2 ) 2 ) 1 / 2

[0053] Furthermore, the RED obtained by dividing the distance Ra between the overall HSP value of the surfactant and the HSP value at the center coordinates of the Hansen solubility sphere of the evaluation criteria by the radius R0 of the Hansen solubility sphere of the evaluation criteria was determined. RED = Ra / R0 The fact that this RED is 1 or less indicates that the overall HSP value of the surfactant is included in the Hansen solubility sphere of the evaluation criteria.

[0054] Table 3 shows the HSP value, Ra, and RED values for the whole of each surfactant.

Table 3

[0055] The relationship between the RED for the whole of each surfactant shown in Table 3 above and the skin irritation index of each surfactant is shown in the graph of Figure 2. According to the graph of Figure 2, among the surfactants located inside the Hansen solubility sphere serving as the evaluation criteria (surfactants with an overall RED value of 1 or less), there are surfactants with a high skin irritation index (80 - 90), but there are also surfactants with a low skin irritation index (20 or less). Therefore, when using the HSP value for the whole of the surfactant, the correspondence between inside and outside the Hansen solubility sphere serving as the evaluation criteria and primary skin irritation is not confirmed.

[0056] (<Reference>Regarding the Hansen solubility sphere derived from the hydrophilicity of the surfactant and the predictability based on the HSP value at the center of the sphere) Next, for each surfactant as the test substance, the Hansen solubility sphere derived from the hydrophilicity of the surfactant and the HSP value at the center of the sphere were determined using known HSP value analysis software. Here, unlike identifying the Hansen solubility sphere when obtaining the HSP values in Table 3 above, the Hansen solubility sphere derived from the hydrophilicity and the Hansen solubility sphere derived from the hydrophobicity in the surfactant were determined using known HSP value analysis software. Furthermore, the HSP value at the center of the Hansen solubility sphere derived from the hydrophilicity of the former was determined. Note that the substances with known HSP values used to obtain the HSP values of the surfactant's hydrophobicity are the same as those when obtaining the HSP values in Table 3 above.

[0057] In Fig. 3, for "sodium lauryl sulfosuccinate", which is an example of a surfactant, the Hansen solubility sphere derived from hydrophilicity is shown on the HSP coordinates. Note that in Fig. 3, the Hansen solubility sphere derived from the hydrophobicity of "sodium lauryl sulfosuccinate" is also shown simultaneously. Among the two spheres, the sphere with the larger δh value corresponds to the Hansen solubility sphere derived from hydrophilicity, and the sphere with the smaller δh value corresponds to the Hansen solubility sphere derived from hydrophobicity. This is because the interaction by hydrogen bonding is greater in the hydrophilicity-derived part than in the hydrophobicity-derived part in the surfactant, resulting in a larger δh value indicating the hydrogen bonding force term.

[0058] Furthermore, Ra, which is the distance between the HSP value derived from the hydrophilicity of each surfactant and the HSP value at the center coordinates of the evaluation standard Hansen solubility sphere, and RED, which is obtained by dividing the distance Ra by the radius R0 of the evaluation standard Hansen solubility sphere, were each determined. Table 4 shows the HSP value derived from the hydrophilicity of each surfactant, as well as the values of Ra and RED.

Table 4

[0059] The relationship between the skin irritation index of each surfactant and RED for the hydrophilicity-derived part of each surfactant shown in Table 4 above is shown in the graph of Fig. 4. According to the graph in Figure 4, for surfactants (surfactants with a RED value derived from hydrophilicity of 1 or less) that are close to the set of HSP coordinates of substances determined to have "skin primary irritation" in human patch tests and are located inside the Hansen solubility sphere serving as the evaluation criterion, the skin irritation index is low (20 or less). Also, according to the graph in Figure 4, for surfactants (surfactants with a RED value derived from hydrophilicity greater than 1) that are far from the set of HSP coordinates of substances determined to have "skin primary irritation" in human patch tests and are located outside the Hansen solubility sphere serving as the evaluation criterion, the skin irritation index is high (80 - 90). Therefore, when using the HSP value derived from the hydrophilicity of surfactants, the relationship "for surfactants whose HSP value derived from hydrophilicity is close to the set of HSP coordinates of substances determined to have'skin primary irritation' in human patch tests and is located inside the Hansen solubility sphere, the skin primary irritation value is also high" does not hold.

[0060] (Regarding predictability based on hydrophobic information (Hansen solubility sphere derived from hydrophobicity in surfactants and the HSP value of the sphere)) Furthermore, for each surfactant as the test substance, in the same manner as when obtaining the Hansen solubility sphere derived from the hydrophobicity of the above surfactants and the HSP value at the center of the sphere, the HSP value derived from the hydrophobicity in the surfactant was obtained.

[0061] As described above, in Figure 3, for "sodium lauryl sulfosuccinate", which is an example of a surfactant, the Hansen solubility sphere derived from hydrophobicity is shown on the HSP coordinates.

[0062] Furthermore, Ra, which is the distance between the HSP value derived from the hydrophobicity in each surfactant and the HSP value of the center coordinates of the evaluation criterion Hansen solubility sphere, and RED, which is obtained by dividing the distance Ra by the radius R0 of the evaluation criterion Hansen solubility sphere, were each determined. Table 5 shows the values of the HSP value derived from the hydrophobicity, Ra, and RED for each surfactant.

Table 5

[0063] The relationship between the skin irritation index of each surfactant and the RED derived from hydrophobicity in each surfactant shown in Table 5 above is shown in the graph of Fig. 5. According to the graph of Fig. 5, for surfactants (surfactants with a RED value derived from hydrophobicity of 1 or less) that are close to the set of HSP coordinates of substances judged to have "positive" skin primary irritation in the human patch test and are located inside the Hansen solubility sphere serving as the evaluation criterion, the skin irritation index is high (80 - 90). Also, according to the graph of Fig. 5, for surfactants (surfactants with a RED value derived from hydrophobicity greater than 1) that are far from the set of HSP coordinates of substances judged to have "positive" skin primary irritation in the human patch test and are located outside the Hansen solubility sphere serving as the evaluation criterion, the skin irritation index is low (20 or less). Therefore, when using the HSP value derived from hydrophobicity in surfactants, the relationship "for surfactants whose HSP value derived from hydrophobicity is close to the set of HSP coordinates of substances judged to have 'positive' skin primary irritation in the human patch test and whose HSP value derived from hydrophobicity is located inside the Hansen solubility sphere, the value of skin primary irritation is also high" holds. Furthermore, when using the HSP value derived from hydrophobicity in surfactants, the relationship "for surfactants whose HSP value derived from hydrophobicity is far from the set of HSP coordinates of substances judged to have 'positive' skin primary irritation in the human patch test and whose HSP value derived from hydrophobicity is located outside the Hansen solubility sphere, the value of skin primary irritation is also low" holds. From the above, a correspondence relationship is recognized between the result predicted from the relationship between the HSP value derived from hydrophobicity in surfactants and the Hansen solubility sphere serving as the evaluation criterion and the result of actual skin primary irritation.

[0064] From the above, it is difficult to predict skin primary irritation using the overall HSP value of the surfactant or the HSP value derived from hydrophilicity of the surfactant, but it has become clear that highly reliable results can be obtained for predicting skin primary irritation using the HSP value derived from hydrophobicity in the surfactant.

Claims

1. A method for predicting the safety of a surfactant, predicting the safety of the surfactant based on predetermined reference information determined for a substance or group of substances for which information on safety is known and hydrophobicity information derived from the hydrophobicity of the surfactant. A method for predicting the safety of a surfactant.

2. Predicting the safety of the surfactant by determining the affinity with the surfactant using the predetermined reference information and the hydrophobicity information. The method for predicting the safety of a surfactant according to claim 1.

3. The determination of the affinity is made based on information indicating the polarity of each of the predetermined reference information and the hydrophobicity information. The method for predicting the safety of a surfactant according to claim 2.

4. The determination of the affinity is made based on information on the dispersion force term, the dipole-dipole force term, and the hydrogen bonding force term in the Hansen solubility parameter of each of the predetermined reference information and the hydrophobicity information. The method for predicting the safety of a surfactant according to claim 3.

5. The predetermined reference information is determined based on information on safety and information indicating polarity for a plurality of types of substances. The method for predicting the safety of a surfactant according to any one of claims 1 to 4.

6. The predetermined reference information is determined based on information on safety and information on the dispersion force term, the dipole-dipole force term, and the hydrogen bonding force term in the Hansen solubility parameter for a plurality of types of substances. The method for predicting the safety of a surfactant according to claim 5.

7. The determination of the safety is a determination of irritation to the skin. The method for predicting the safety of a surfactant according to any one of claims 1 to 4.

8. The determination of the irritation to the skin is a determination regarding primary skin irritation. The method for predicting the safety of the surfactant according to claim 7.

9. The surfactant is an ionic surfactant. The method for predicting the safety of the surfactant according to any one of claims 1 to 4.

10. Predicting the safety of a cosmetic containing the surfactant based on the method for predicting the safety of the surfactant according to any one of claims 1 to 4. The method for predicting the safety of a cosmetic.

11. Manufacturing a cosmetic using the surfactant whose safety has been determined by the method for predicting the safety of the surfactant according to any one of claims 1 to 4. The method for manufacturing a cosmetic.

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