JPH1183769A - Method for evaluating performance of surfactant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate performance by measuring correlation time of surfactant molecules by a nuclear magnetic resonance(NMR) analysis, thereby measuring an interaction of the molecules having correlation with performance such as foaming power, cleaning power or the like of the surfactant. SOLUTION: Correlation time of surfactant molecules is measured by an NMR analysis, a molecular motion of the surfactant is analyzed from the measured value, and performance of the surfactant is evaluated. That is, a pulse-like electromagnetic wave is emitted to surfactant water solution. And, magnitude of an interaction of the molecules is measured from time dependence or frequency dependence of the wave absorbed or reflected in the solution. For example, the wave is emitted to the solution of an equilibrated state to apply disturbance thereto, and a deviation from the equilibrated state is brought about. And, alleviating time and nuclear Overhauser effect of the molecules when the system is returned to the equilibrated state by the internal motion of the system are measured, thereby obtaining the state of the interaction of the molecules.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for evaluating the performance of a surfactant based on the correlation time of a surfactant molecule.
Specifically, the state of the interaction of the surfactant molecules, which is useful information for examining the composition and additives of the surfactant,
The present invention relates to a method for evaluating the performance of a surfactant by analyzing the correlation time of the surfactant.

[0002]

2. Description of the Related Art A surfactant aqueous solution is a system that changes with time, and its performance such as foaming power and detergency depends on the molecular structure and composition of the surfactant in the water. to differ greatly. Determining the composition of a mixed system requires sufficient knowledge, experience, and trial and error. Usually, performance such as foaming power and detergency has been actually measured to evaluate the surfactant molecule or the composition. At this time, if the correlation between the molecular structure or the functional group of the surfactant and the performance is clear, it is expected that the number of surfactant molecules to be newly synthesized can be narrowed down and that the determination of the composition is labor-saving.

[0003] Further, in actual surfactant systems (eg, detergents for clothes, detergents for dishes, shampoos, rinses, cement dispersants, lotions, emulsions, etc.), two or more different surfactant aqueous solutions are used. Surfactants are used in mixed form and because they are thermodynamically unstable systems,
The mixed state and interaction state prepared at the time of manufacture,
This is one of the important characteristics for achieving high performance. When producing an aqueous solution of a surfactant, an optimum additive, especially the surfactant to be used, has been studied so as to have as high a performance as possible and to provide a stable system. Therefore, in order to maximize the performance of the surfactant aqueous solution, it is necessary to evaluate the interaction between the surfactant molecules.

As a value indicating the interaction of such surfactant molecules, an interaction parameter β has been conventionally measured (Rosen, MJ and XYHua, J. Colloid Interfa
ceSci., 86, 164 (1982)). However, the analysis of the interaction parameters had to take into account the assumption that the solution was a regular solution, and required a method of evaluating performance by a measurement method without any direct assumption.

As described above, it is difficult to accurately grasp the situation at the time of use, even if the interaction parameter β is evaluated, as known information for selecting a molecular structure and determining a composition in an aqueous surfactant solution. Met. At present, high-performance materials are actually screened in many combinations. However, these methods need to be sampled and performed manually.

[0006] Therefore, the correlation between the molecular structure of the surfactant and the performance such as foaming power and detergency has been clarified, and a method for evaluating the performance of the surfactant has been established. It is thought that product development can be planned.

Accordingly, an object of the present invention is to measure the interaction of surfactant molecules, which is correlated with the performance of the surfactant such as foaming power and detergency, and is considered as an axis for evaluating those performances. Another object of the present invention is to provide a method for directly evaluating the performance of a surfactant.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the correlation time indicating the mobility of a surfactant molecule has been reduced by the correlation time between surfactant molecular interactions. Focusing on reflecting the difference, analyze the correlation time of surfactant molecules by NMR analysis, examine the correlation with surfactant performance such as foaming power, detergency, etc. Find out how to evaluate the performance of surfactants that can directly evaluate the performance such as detergency at the molecular level,
The present invention has been completed.

That is, the present invention is characterized in that the correlation time of a surfactant molecule is measured by NMR analysis, and the molecular motion of the surfactant is analyzed from the measured value to evaluate the performance of the surfactant. The present invention provides a method for evaluating the performance of a surfactant.

[0010]

Embodiments of the present invention will be described below in detail.

The present invention relates to a detergent for clothes, a detergent for dishes,
It was made by finding that there is a relationship between the foaming power and detergency of surfactant solutions such as shampoos, rinses, cement dispersants, lotions, and emulsions, and the state of molecular interaction. .

In the present invention, the aqueous solution of the surfactant
Irradiation with a pulsed electromagnetic wave is performed, and the magnitude of the interaction of the surfactant molecules is measured from the time dependence or frequency dependence of the electromagnetic wave absorbed or reflected in the surfactant aqueous solution.
The state of the interaction between the surfactant molecules is determined by, for example, irradiating an aqueous solution of the surfactant in an equilibrium state with electromagnetic waves to cause a disturbance from the equilibrium state. Can be determined by measuring the relaxation time T ₁ of the surfactant molecule and the NOE (nuclear Overhauser effect) when returning to.

More specifically, a nuclear magnetic resonance apparatus (NM)
R: Nuclear Magnetic Resonance), and particularly in the present invention, ¹³ C-
It is preferable to use NMR. That is, the nuclear magnetic relaxation time T ₁ and NOE are measured by ¹³ C-NMR analysis, and the correlation time of the surfactant molecule is determined from the measured value, so that a detergent for clothes, a detergent for dishes, a shampoo, a rinse, The performance such as foaming power and detergency of a surfactant used for a cement dispersant, a lotion, an emulsion and the like is evaluated.

In the present invention, the concentration of the aqueous surfactant solution used for ¹³ C-NMR analysis is preferably from several mM to several hundred mM. The surfactant measured by the method of the present invention is not particularly limited, and may be any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. Specifically, alkyl sulfates,
Sulfates such as alkylamide sulfates and polyoxyethylene alkyl sulfates or salts thereof; amine oxides such as alkylamine oxide and alkylamidopropylamine oxide; quaternary ammonium salts such as alkylamidopropyltrimethylammonium chloride; Surfactants such as ethylene alkyl ethers and mixtures thereof.

The principle of the method using the nuclear magnetic resonance apparatus of the present invention will be described in more detail. Using a nuclear magnetic resonance apparatus, the relaxation time T ₁ of the surfactant is measured by the inversion recovery method. Further, using a nuclear magnetic resonance apparatus, the surfactant NO
E (nuclear Overhauser effect) is measured. From these measurements, the average relaxation time and relaxation efficiency of the surfactant can be determined.

First, a relaxation time T ₁ of a surfactant is determined by an inversion-recovery method in ordinary NMR analysis. The NOE measurement is performed in two modes: a measurement mode (decoupling mode) in which the magnetic field applied to the hydrogen atoms is suppressed and the number of hydrogen atoms is not considered, and a normal measurement mode (double-level decoupling mode). Measurement is required.

In order to calculate the ratio of the peak height between the signal in the decoupling mode and the signal in the double-level decoupling mode, the following conditions were unified. 1) Irradiation pulse time (45 ° pulse) (time until irradiation of radio wave for reversing magnetization direction): 1/4 of irradiation time for reversing magnetization 2) Pulse delay time (at the end of data capture) Time until the start of the next measurement): About 5 times the expected T ₁ 3) Receiver gain (value of the receiver that captures data): Automatically set value in decoupling mode 4) Normalized gain (of the capture signal 5) Y-axis gain (scale at which the signal is plotted out): optimal height in decoupling mode.

Heavy water is used as the measuring solvent, and the test tube has a diameter of
A 10 mm NMR test tube was used. Samples are cleaned with an ultrasonic cleaner
Aging was performed by stirring for 15 minutes and allowing to stand for at least one day.

The measurement conditions such as the pulse waveform length range are as follows:
For example, it is as follows. The following four devices were used for NMR measurement.・ JNM-GX-400 made by JEOL ・ JNM-EX-270WB made by JEOL ・ AC-200P made by Bruker ・ FX-90 made by JEOL Measurement core: ¹³ C 90 ° pulse (PW ₁ ) = 5 to 30 μs 180 ° pulse (PW ₂ ) = PW ₁ × 2 Pulse delay (PD) = 10 to 30 s In the above range, the value of PW ₁ is, for example, 5, 6, 7
... Change at regular intervals, such as 30 μs, to determine the peak height of each spectrum, plot the relationship between the logarithmic value of the peak height of each spectrum and the PD value at that time, and draw a straight line. Get it.

In NMR analysis, when PW ₁ is changed, the obtained spectrum intensity changes. Then, when these are plotted, a straight line is obtained. The slope of the line is
Depends on the type of surfactant.

A heavy aqueous solution is used as an aqueous surfactant solution for NMR analysis, and the total concentration is adjusted to 200 mM.
The nuclear magnetic relaxation time T ₁ and NOE of the surfactant aqueous solution thus prepared are measured, and then the correlation time is obtained by calculation, and the relationship between the foaming power, detergency, etc. of the surfactant and the correlation time is determined. Find out.

To calculate the correlation time from T ₁ and NOE obtained from the NMR measurement and the motion model, FORTRA
N used a self-made program. In addition, BASIC (N88BASI
This was performed using the self-made program created in C).

The analysis of molecular motion by correlation time using NMR as described above is performed as follows. Nuclear magnetic relaxation generally occurs due to magnetic interactions that create a fluctuating magnetic field at the location of the observed nucleus. The efficiency of relaxation depends on the nature of the interaction, which is the mechanism of the relaxation, and the molecular motion that accepts the energy released during the relaxation. Therefore, the nuclear magnetic relaxation times T ₁ and NOE (nuclear overhauser effect) are measured. This gives information about molecular motion. Normal NM
Mitigation subject to nuclear ¹³ C of R is dominated by the magnetic dipole-dipole interaction between the ¹³ C- ¹ H.

In general, in the analysis of molecular motion from T ₁ and NOE, a spectral density function J (ω) is determined based on a molecular motion model, and T ₁ and NOE are calculated and compared with measured values. Determine the suitability of the assumed model.

A model including a plurality of correlation times is used to explain the relaxation time and NOE reflecting the molecular motion of a complex surfactant. Among these models, it is necessary to select and use an optimal model according to the molecule to be handled. A commonly used model for discussing the mobility of aqueous surfactant solutions is the step model approach (O.
Soderman, H. Walderhaug, U. Henrikkson and P. Stilbs,
J. Phys. Chem., 89, 3693 (1985)).

Measurement of the longitudinal relaxation time T ₁ of ¹ H or ¹³ C is frequently used to obtain information on the mobility of a surfactant molecule. However, it is necessary to measure the frequency is changed because some can lead to sometimes erroneous conclusion when discussing the molecular mobility only by T ₁ measured at a certain single frequency.
T ₁ and NOE of ¹³ C to which ¹ H is bonded are represented by the following formulas.

[0027]

(Equation 1)

In general, in the analysis of molecular motion from T ₁ and NOE, a density function J (ω) is determined based on a molecular motion model, and the obtained T ₁ and NOE are compared with measured values. The suitability of the assumed molecular motion model is determined.

In the micelle system, the relations of equations (1) and (2) are established between T ₁ , NOE and the measurement frequency, so that the measurement is performed with the NMR measurement frequency changed, and the measured value is fitted with the relational expression. Thus, the correlation time can be obtained. In practice, the resonance frequency cannot be continuously changed over several digits due to the limitations of the apparatus, so it is necessary to use a relational expression using some model.

Therefore, an "isotropic rotation model", a "2τ model" or a "3τ model" is considered depending on the number of molecular motion modes. What is important here is the density function J (ω) based on the molecular motion model. Here, the density function J (ω) of the 2τ model is shown. τ _s and τ _f are two different types of correlation time, and θ is an angle indicating a deviation from the most stable three-dimensional structure of a molecule due to molecular motion.

J (ω) = (1−S ² ) J _f (ω) + S ² J _S (ω) (3) J (ω) is a function indicating the attenuation of the correlation time, and differs depending on the assumed model. The correlation time is the time that the molecule can stay at that position, and a larger value indicates a lower mobility. In order to verify whether the obtained correlation time is appropriate, T ₁ is measured while changing the observation frequency, and plotted against the observation frequency.

This model considers a fast motion of a molecular chain characterized by a correlation time τ _f and a slow motion due to rotation and diffusion in a whole micelle characterized by τ _s . According to this model, J (ω) is given by equation (3)
Is divided into a density function J _f (ω) representing a fast motion mode and a density function J _S (ω) representing a slow motion mode, and contains an order parameter S representing the order of orientation of molecules in micelles. It is represented by Also order parameter S
And T ₁ , NOE are shown as follows: θ is an angle indicating a deviation from the most stable three-dimensional structure of a molecule due to molecular motion.

[0033]

(Equation 2)

Here, when the relationship of ωτ≪1 is established in the 2τ model, J _f (ω) can be approximated as J _f (ω) = 2τ _f (5), and J _S (ω) is

[0035]

(Equation 3)

It is expressed as follows. Therefore J (ω) is

[0037]

(Equation 4)

It is transformed as follows. When considering another slow motion mode, the 3τ model uses J _S (ω)

[0039]

(Equation 5)

It is shown that the above equation can be applied. So J (ω) is

[0041]

(Equation 6)

Is as follows.

The correlation time is the time during which the molecule stays at that position, and the larger the value, the slower the molecular motion. Therefore, in general, the larger the interaction of the surfactant molecules in the aqueous surfactant solution, the larger the value of the correlation time. This is considered to be because the stronger the molecular interaction, the more lattice systems that relax the spin system generated by nuclear magnetic resonance.

Accordingly, the nuclear magnetic relaxation time T _{1 of the} aqueous surfactant solution for which molecular interaction is to be known.
If the correlation time is determined by measuring the NOE and NOE by NMR analysis and calculating from the obtained values, the interaction of the surfactant molecules can be immediately known.

In the present invention, the relationship between the correlation time of the surfactant obtained in this way and the performance of the surfactant, for example, foaming power and detergency, was examined. In particular, it was found that the longer the correlation time of the hydrophilic part of the surfactant molecule, that is, the lower the molecular mobility of the hydrophilic part, the better the foaming power and detergency.

Therefore, the nuclear magnetic relaxation time T ₁ and the NOE of a surfactant whose performance such as foaming power and detergency are to be measured are measured by NMR analysis, and the obtained values are simulated by a computer. Correlation time τ _f
Of the surfactant, the performance such as the detergency and foaming power of the surfactant can be evaluated from the correlation time, and the knowledge on the correlation time of the surfactant as a means of detecting the performance of the surfactant is very low. It was found to be effective.

[0047]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 (Relationship between foaming power of surfactant aqueous solution and correlation time) As surfactants, lauryl amethylene methylene sulfate sodium salt (sample 1), lauryl sulfate sodium salt (sample 2) and lauryl polyoxy were used. Ethylene (E
O = 3) A surfactant aqueous solution was prepared using a sulfate sodium salt (sample 3) so that the surfactant concentration became 200 mM. In addition, when the foaming power of these surfactant aqueous solutions was evaluated by measuring the foaming height of the sample stirred for a certain period of time, the order was as follows: sample 1> sample 2> sample 3.

The prepared aqueous solution of the surfactant was subjected to ¹³ C using a nuclear magnetic resonance apparatus manufactured by JEOL Ltd. and Bruker.
Nuclear magnetic relaxation time T _{1 of} surfactant molecules for nuclei
And NOE were measured.

[0050] From this measurement were determined the correlation time tau _f representing the average molecular motion of the surfactant molecule by a calculation formula as shown above. FIG. 1 shows the correlation time of each sample.
The relationship between the foaming power evaluation result of each sample described above and the correlation time shown in FIG. 1 was examined. As the foaming power of the sample increased, the hydrophilic group terminal of the sample (α position of sample 1) , Sample 2
It can be seen that the correlation time of the position (EO chain of sample 3) increases. These results show that there is a good correlation between the foaming power of each sample and the correlation time.

Example 2 (Relationship between Detergency of Surfactant Aqueous Solution and Correlation Time) As surfactants, N-myristyl-N, N-dimethylamine oxide (sample 1), N-myristylamidopropyl-N, N-dimethylamine oxide (sample 2)
And N-myristylamidopropyl-N, N, N-trimethylammonium chloride (Sample 3) to prepare a surfactant aqueous solution such that the surfactant concentration became 200 mM. Incidentally, when the detergency of these surfactant aqueous solutions against oil stains was evaluated, the detergency was determined as Sample 1> Sample 2
Sample 3 was in order.

The prepared aqueous solution of the surfactant was subjected to ¹³ C using a nuclear magnetic resonance apparatus manufactured by JEOL Ltd. and Bruker.
Nuclear magnetic relaxation time T _{1 of} surfactant molecules for nuclei
And NOE were measured.

[0053] From this measurement were determined the correlation time tau _f representing the average molecular motion of the surfactant molecule by a calculation formula as shown above. FIG. 2 shows the correlation time of each sample.
The relationship between the evaluation results of the detergency of each sample shown above and the correlation time shown in FIG. 2 was examined. As the detergency of the sample increased, the correlation of the hydrophilic group terminal (N-methyl group) of the sample increased. It can be seen that the time is increasing. That is, a good correlation is shown between the detergency and the correlation time. This indicates that the method is effective as a new evaluation method for the detergency of the surfactant.

[0054]

As described above, the correlation time of surfactant molecules is measured by NMR analysis, and the molecular motion of the surfactant is analyzed based on the measured values to evaluate the performance of the surfactant. By using the method of the present invention, the performance evaluation of the conventional surfactant could be significantly shortened.

[Brief description of the drawings]

FIG. 1 is a diagram showing a correlation time of each sample prepared in Example 1.

FIG. 2 is a view showing a correlation time of each sample prepared in Example 2.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Mamada 1334 Minato 1334, Minato, Wakayama-shi, Wakayama Prefecture Researcher (72) Inventor Takaya Sakai 1334 Minato, Minato, Wakayama-shi, Wakayama Research Laboratory (72) Inventor Masakatsu Takahashi 1334 Minato, Wakayama City, Wakayama Prefecture Kao Corporation Research Center

Claims (4)

[Claims] 1. The method of claim 1, wherein the correlation time of the surfactant molecule is measured by NMR analysis, and the molecular motion of the surfactant is analyzed from the measured value to evaluate the performance of the surfactant. Performance evaluation method. 2. An NMR analysis of ¹³ C-
The evaluation method according to claim 1, which is performed by NMR measurement. 3. The evaluation method according to claim 2, wherein the correlation time between the surfactant molecules is obtained from the nuclear magnetic relaxation time T ₁ obtained from ¹³ C-NMR measurement and the NOE (nuclear Overhauser effect). 4. The foaming power or detergency of the surfactant is evaluated from the correlation time of the hydrophilic part of the surfactant molecule.
The evaluation method according to any one of the above.