JPH0254735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for measuring the degree of hair damage.

(Technical background of the invention and its problems) The characteristics of hair, such as strong hair that is resistant to damage by hair styling agents, shampoos, etc., and weak hair that is easily damaged, are: It has a strong correlation with the cross-sectional area of the hair, and conventionally the thickness of the hair has been measured using a diameter gauge or the like. However, as shown in Figure 1, the cross-sectional shape of hair is often not a perfect circle but an ellipse, which has the disadvantage that the measured thickness varies greatly depending on the measurement location. It has the disadvantage that it is easily deformed when force is applied, and the measurement accuracy varies, making accurate measurements impossible. Additionally, there was a device that measured the strength and elongation of hair by applying a load to it, but it had the drawback that it was unable to maintain continuous numerical measurements up to the time of cutting, making it difficult to analyze hair characteristics. Ta. moreover,
There is no way to measure the extent of hair damage, and it has not been possible to provide objective measurement data for hair care advice or product recommendations such as hair conditioners.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and an object of the invention is to provide a measuring method that can accurately and stably measure the degree of damage as a characteristic of hair. There is a particular thing.

(Summary of the Invention) The present invention relates to a method for measuring the degree of hair damage.
The elastic limit point and the first cutting point are determined, the second elastic limit point and the second cutting point are determined from the elongation vs. strength characteristics at a position away from the tip or the hair root, and The degree of damage to the hair is measured from the relationship between the second elastic limit point and the first and second cutting points.

(Embodiments of the Invention) In the present invention, as shown in FIG. 2, both ends of the hair 1 are held by holding members 2 and 3, and the degree of damage to the hair 1 is measured. The holding member 2 is fixed to the main body via a swinging member 5, and the other holding member 3 is moved at a constant speed in the N direction in the drawing by a moving mechanism (not shown). or,
The swinging member 5 is provided with a load detector, for example, a strain gauge 4, for measuring the load applied to the holding member 2 via the hair 1. Then, the holding member 3 is placed under a load of 0 between the hair 1 and the holding member 2.
By moving in the N direction at a constant speed from the position P, the relationship between elongation and strength as shown in FIG. 3 can be obtained. That is, from a position P where no load is applied to the hair 1, the holding member 3 is moved at a constant speed N.
As you move in the direction, the strength (load) initially increases in proportion to the distance traveled, that is, the elongation, but when it reaches a certain elongation E1, the strength does not increase much, and the elongation increases to E2. From the relaxed position, the strength also increases proportionally and finally reaches the cutting point C where the hair 1 is cut, and the measurement operation ends. In such elongation vs. strength characteristics, the first point of change where Hook's law ends is the elastic limit point (A) of Hook, the next point of change is the transition point (B), and the last hair 1 is The point at which the hair is cut is the cutting point (C), and the properties of the hair can be determined by measuring these elastic limit point A, transition point B, and cutting point C.

Here, since hair grows from the root and becomes longer, the tissue of the hair gradually ages towards the tip of the hair, and the hair tissue in the direction of the hair grows older due to brushing, hair styling, environmental changes, etc. than the hair root. The hair has been damaged, and its characteristics are different between the hair root and the hair tip. Then, as shown in Figure 4, the cutting point C is first cut between the less damaged hair base and the more damaged hair tip.
occurs as a change in properties, and then the elastic limit point A
It has been confirmed that the elastic limit point A and cutting point C of the hair base are compared with the elastic limit point A and cutting point C of the hair at or near the hair tip, or at a position away from the hair source. The degree of hair damage can be determined by: Figure 4 shows that the degree of hair damage increases in the order of It is possible to determine a relatively large level of damage based on the fluctuation.

Therefore, in the present invention, the characteristics of the less damaged hair root and the more damaged hair tip are measured for one hair sample, and the damage is evaluated by comparing the measurement results. . That is, as shown in Figure 5, the characteristics of the hair root and the hair tip are determined using the method explained in Figure 2, and the elastic limit point Ao of the hair root and the cutting point Co of the hair root are used as standards. The degree of damage to the hair is evaluated by comparing the characteristics of the elastic limit point Ax and the cutting point Cx of the hair tip. Figure 6 shows an example of the evaluation method.If the cutting point Cx at the tip of the hair is greater than 105% of the cutting point Co at the root,
In other words, if Co(1+0.05)<Cx, it is abnormal, so the evaluation is performed again as an error.
Furthermore, if the cutting point Cx at the tip of the hair is within ±5% of the cutting point Co at the root of the hair, it is evaluated as state 1 indicating no degree of damage. That is, state 1 is a case where Co(1-0.05)≦Cx≦Co(1+0.05). Then, the cutting point Cx is the cutting point Co of the hair base.
If it is more than 70% and less than 95%, that is, Co(1
−0.3)≦Cx<Co(1−0.05), the material is divided into three ranks depending on the elastic limit point Ax. In other words,
If the elastic limit point Ax is Ao (1 + 0.1) < Ax, it is abnormal and evaluated as an error, and the elastic limit point Ax
If Ao (1-0.1)≦Ax≦Ao (1+0.1), it is evaluated as slightly damaged state 2, and the elastic limit point
If Ax is Ax<Ao (1-0.1), it is evaluated as state 3, where the damage is greater than that.

On the other hand, if the cutting point Cx varies greatly with respect to the cutting point Co at the hair root, the degree of damage is large;
In that example, 70% and 50% of the cutting point Co at the hair base are used to distinguish between 70% and 50%. And the cutting point Cx is Co(1-0.5)≦
When Cx<Co(1-0.3), it is divided into two ranks according to the elastic limit point Ax, and state 4 where Ao(1-0.5)≦Ax or state 5 where Ax<(Ao(1-0.5))
Evaluate as. Furthermore, the cutting point Cx is Cx<Co(1
-0.5), the degree of damage is extremely large6
Evaluate as. 6 obtained as above
For states 1 to 6, which are rank evaluations, products with low treatment effects can be recommended for hair with a low degree of damage, and products with high treatment effects can be recommended for hair with a high degree of damage. It provides great reference material for hair care, product recommendations, usage, etc.

In addition, in the above-mentioned example, the numerical values evaluated against the standard data are classified into 5%, 30%, and 50% of the cutting point Co, and 10% and 50% of the elastic limit point Ao. The classification value can be set arbitrarily. Further, the number of evaluation ranks can also be set arbitrarily.

(Effects of the Invention) As described above, according to the hair damage measurement method of the present invention, the reference elastic limit point and the standard cutting point are determined from the elongation versus strength characteristics at the hair base where the hair is less damaged, and the hair is easily damaged. Since the evaluation is performed by determining the elastic limit point and cutting point of the hair tip and comparing it with the standard value, it is possible to accurately and stably measure the degree of hair damage. It will be a great reference material when purchasing, using, etc.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the cross-sectional shape of hair.
Fig. 2 is a diagram showing how the method of this invention is carried out, Figs. 3 and 4 are characteristic diagrams for explaining the principle of the method of this invention, and Figs. 5 and 6 are diagrams of the method of this invention. FIG. 2 is a diagram for explaining an example. 1... Hair, 2, 3... Holding member, 4... Strain gauge, 5... Swinging member.

Claims (1)

[Claims] 1 From the elongation vs. strength characteristics at the source of the hair, the first
The elastic limit point and the first cutting point are determined, and the second elastic limit point and the second cutting point are determined from the elongation versus strength characteristics at a position away from the tip or the hair source, and the second elastic limit point and the second cutting point are determined from the The ratio of the characteristics of the second cutting point to the characteristics of the first cutting point, or the ratio of the characteristics of the second elastic limit point to the characteristics of the first elastic limit point as a reference; A method for measuring the degree of hair damage, characterized in that the degree of damage to the hair is measured by: