JP7514488B2 - Bristle material for cosmetic brushes and cosmetic brushes using said bristle material - Google Patents

Description

The present invention relates to hair materials for cosmetic brushes, hair material assemblies for cosmetic brushes, and cosmetic brushes.

Conventionally, natural animal hair such as squirrel hair, horse hair, and goat hair has been used as the hair material for cosmetic brushes.
Natural animal hair is said to have good absorption and release properties for liquid or powdered cosmetics, a soft bristles, and a pleasant feel on the skin, making it popular with many users. In particular, squirrel hair and goat hair cosmetic brushes are highly regarded by consumers as the highest quality animal hair cosmetic brushes. However, although natural animal hair has many advantages, it is a natural resource and therefore there is a limit to the amount that can be supplied, and it is becoming increasingly difficult to obtain it from the perspective of animal welfare and global ecology protection. Therefore, in recent years, cosmetic brush bristles made from synthetic fibers have been proposed as an alternative to natural animal hair.

For example, Patent Document 1 proposes a brush bristle material for cosmetic brushes and the like that is mainly composed of polypropylene terephthalate and exhibits a specific bending recovery rate. It is specifically disclosed that brush bristle material made only of polypropylene terephthalate, even if it has a tapered tip, is more durable than brush bristle material made only of polybutylene terephthalate, and is more flexible and softer than conventional brush bristle materials (see Patent Document 1).
Patent Document 2 proposes a brush bristle material in which a tapered portion is formed at one end of a synthetic resin monofilament. It specifically discloses that the cross-sectional shape of the tapered portion is circular and the cross-sectional shape of the main body other than the tapered portion is eight-lobed, which provides excellent application performance for liquid cosmetics and a usability comparable to that of natural animal hair, making it suitable for use as a cosmetic brush (see Patent Document 2).

JP 2003-245133 A JP 2009-201794 A

Natural animal hair is slightly crimped, and therefore the tip of the applicator spreads when the hairs are bundled, making it particularly suitable for applying powdered cosmetics such as blusher and eye shadow in a blurred state. On the other hand, brush hair materials made of synthetic fibers are themselves straight, and therefore the tip of the applicator does not spread and remains straight when the hairs are bundled, making them suitable for applying solid, paste, or liquid cosmetics such as eyeliner and lipstick, but are known to be unsuitable for applying powdered cosmetics.
Therefore, an object of the present invention is to provide a bristle material for a cosmetic brush made of a synthetic resin, which is suitable for applying both powdered and liquid cosmetic materials, and more specifically has good catch-and-release properties for powdered or liquid cosmetic materials, a bristle material assembly for a cosmetic brush, and a cosmetic brush using the same.

As a result of extensive research conducted by the inventors to solve the above problems, they discovered that in cosmetic brush hair material consisting of S-twisted or Z-twisted core-sheath composite monofilament having a specific cross-sectional shape, by making the core and sheath into a two-layer structure consisting of different materials, a good balance between softness and resilience can be achieved, resulting in cosmetic brush hair material with extremely excellent catch and release properties for powdered or liquid cosmetics, thereby solving the above problems.

Specifically, the present invention relates to the following items.
1. The core is made of synthetic resin A and the sheath is made of synthetic resin B, which is different from synthetic resin A, and the monofilament is S-twisted or Z-twisted.
A cosmetic brush bristle material, characterized in that the cross section of the core-sheath composite monofilament in the direction perpendicular to the fiber axis is cocoon-shaped.
2. The cosmetic brush hair material according to 1., wherein the core-sheath composite monofilament has a tapered portion.
3. The cosmetic brush bristle material according to 2., wherein the tapered portion is branched.
4. The cosmetic brush bristle material according to any one of items 1 to 3, wherein the synthetic resin A and the synthetic resin B are each a polyester resin.
5. The bristle material for a cosmetic brush according to 4., wherein each of the synthetic resin A and the synthetic resin B is one selected from the group consisting of polytrimethylene terephthalate, polyethylene terephthalate, and polybutylene terephthalate.
6. The fiber is made of a mixed assembly of S-twisted and Z-twisted core-sheath composite monofilaments, each having a core made of synthetic resin A and a sheath made of synthetic resin B of a different type from synthetic resin A.
A bristle assembly for a cosmetic brush, characterized in that the cross sections of the core-sheath composite monofilament in a direction perpendicular to the fiber axis are similar to each other in cocoon-shaped form.
7. A cosmetic brush, characterized in that the cosmetic brush hair material according to any one of items 1. to 5. or the cosmetic brush hair material assembly according to item 6. is used in at least a portion thereof.

The hair material for cosmetic brushes of the present invention has three specific three-dimensional shapes, namely twisting, a specific cross-sectional shape, and a core-sheath structure. By making the core and sheath have a two-layer structure made of different materials, it is possible to express the individual characteristics of the two different materials. Depending on how these different materials are combined, the softness, elasticity, and tactile sensation can be adjusted, and by being able to adjust the softness, elasticity, and tactile sensation, it is possible to make a hair material for cosmetic brushes suitable for either powdered or liquid cosmetics. In other words, the hair material for cosmetic brushes of the present invention, which has a two-layer structure of a core and sheath made by combining two different materials, has a good balance between softness and resilience, and can be made similar to or superior to a cosmetic brush made of natural animal hair in terms of both softness and elasticity that are excellent in tactile sensation to the skin. In addition, the combination of the three specific three-dimensional shapes exerts an effect that is more than additive, and realizes performance that is superior to natural animal hair in terms of catch and release properties for powdered or liquid cosmetics. Furthermore, by providing a tapered tip portion, it is possible to provide a cosmetic brush hair material that has a feel comparable to that of natural animal hair, as well as elasticity and softness.

FIG. 2 is a schematic cross-sectional view of a cocoon-shaped core-sheath composite monofilament in the hair material for a cosmetic brush of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a cocoon shape of the present invention. 1A to 1C are schematic cross-sectional views not included in the present invention. 1 is a graph showing the evaluation results of "Evaluation 4 of the usability of a cosmetic brush" in the examples.

The present invention relates to a hair material for a cosmetic brush, which is composed of an S-twisted or Z-twisted core-sheath composite monofilament having a core composed of a synthetic resin A and a sheath composed of a synthetic resin B of a type different from that of synthetic resin A, and which has a cocoon-shaped cross section perpendicular to the fiber axis of the core-sheath composite monofilament, a hair material assembly for a cosmetic brush, and a cosmetic brush.
The present invention will be described in detail below.

The cosmetic brush hair material of the present invention is made of S-twisted or Z-twisted core-sheath composite monofilament. That is, it has a helical structure of either "S-twisted hair material (right-handed twist)" or "Z-twisted hair material (left-handed twist)", and unlike straight fibers or wavy fibers, it has a three-dimensional spread in the direction perpendicular to the helical axis.
The volume occupied by a single bristle having such a helical structure by twisting is larger than that of a bristle having a planar zigzag structure formed by the conventionally known gear crimp method, and a bristle assembly for a cosmetic brush and a cosmetic brush made of the bristle material for a cosmetic brush of the present invention have a large amount of voids inside, as overlapping and adhesion between the bristle materials is suppressed even when left stationary, and the bristle material has a fluffy and voluminous feel. Furthermore, a combination of S-twist and Z-twist is preferable because it increases the number of voids inside and enhances the three-dimensional effect.

The twist number of the hair material for a cosmetic brush of the present invention is preferably set within the range of 30 T/m (twist/m) to 100 T/m (twist/m) inclusive, in either S-twist or Z-twist, and more preferably within the range of 40 T/m (twist/m) to 90 T/m (twist/m) inclusive, in order to form gaps between adjacent hair materials for holding powdered or liquid cosmetics when the hair material is made into a hair material assembly for a cosmetic brush or a cosmetic brush. If the twist number is within the above range, a helical structure can be imparted in the length direction of the fiber with a wavelength width of more than 10 mm and not more than 35 mm.
Normally, to give a three-dimensional effect to a monofilament, it is necessary to use a strong twist to shorten the wavelength width, but in the cosmetic brush hair material of the present invention, the number of twists is reduced (loose twist) to lengthen the wavelength width. By reducing the number of twists in this way, it is possible to obtain a brush hair material with a more three-dimensional effect, and after twisting several monofilaments together, the fibers can be easily opened by combing, which has the effect of improving manufacturing efficiency. Furthermore, strong twists tend to make the hair material stiff and uncomfortable to the skin.
On the other hand, if the wavelength width exceeds 35 mm, the twist becomes loose and the hair material becomes closer to a straight line, so that the three-dimensional spread of the hair material is reduced, and the gaps between the hair materials are reduced, so that the amount of powdered or liquid cosmetic material collected and retained is likely to decrease. Also, if the wavelength width is less than 10 mm, the hair materials are likely to become entangled, and the manufacturing efficiency is reduced. The wavelength width of the hair material for cosmetic brushes of the present invention is preferably in the range of 11 mm to 25 mm, more preferably 12 mm to 20 mm.

The cosmetic brush hair material of the present invention is an S-twisted or Z-twisted core-sheath composite monofilament having a cocoon-shaped cross section perpendicular to the fiber axis.
The cross-sectional shape of the hair material for a cosmetic brush of the present invention will be described with reference to Figures 1 to 3. Figures 1 and 2 are schematic diagrams of the cross-sectional shape of the hair material for a cosmetic brush of the present invention. Figures 3(A) to (C) are schematic diagrams of the cross-sectional shape that is not included in the present invention.
The cocoon-shaped cross section of the sheath-core composite monofilament in the present invention means a long, bale-shaped cross section with a gentle constriction in the central part (body part) like the cocoons made by silkworms as shown in Fig. 1, and does not include a cross section with no constriction in the central part (body part) as shown in Fig. 3(A). The cocoon-shaped cross section of the sheath-core composite monofilament in the present invention also includes one with a large constriction in the central part (body part) as shown in Fig. 2, but does not include one with a constriction like an acute groove as shown in Fig. 3(B) and (C).
The cocoon-shaped cross section of the sheath-core composite monofilament in the present invention is characterized in that, as shown in Figures 1 and 2, the "angle" formed by two tangents (dotted lines) along the gentle neck, starting from the center of the neck, is greater than 90 degrees and smaller than 180 degrees. In the cocoon-shaped cross section of the sheath-core composite monofilament in the present invention, this "angle" is preferably 100 degrees or more, more preferably 120 degrees or more, and even more preferably 130 degrees or more. In an embodiment not included in the present invention, as shown in Figure 3(B), the "angle" formed by two tangents (dotted lines) along the neck, starting from the center of the neck, is less than 90 degrees, forming acute-angled longitudinal grooves.
In the present invention, the cross section of the core portion perpendicular to the fiber axis is elliptical.
The present inventors have confirmed that cosmetic brush bristle materials have improved catch (hold) properties for powdered or liquid cosmetics when longitudinal grooves are present in the fiber length direction. However, the present inventors have now found for the first time that when the longitudinal grooves have an acute angle (within 90 degrees), the powdered or liquid cosmetics contained in the cosmetic brush bristle materials are retained in the longitudinal grooves, resulting in reduced release (discharge) properties. That is, the present inventors have found that the cosmetic brush bristle materials of the present invention exhibit excellent catch and release properties for powdered or liquid cosmetics, particularly excellent release (discharge) properties, by forming the cross section of the core-sheath composite monofilament of the present invention into a gentle streamlined shape, i.e., a cocoon-shaped shape with a constriction with an angle of more than 90 degrees and less than 180 degrees, and have thus completed the present invention.

The cross-sectional shape of the bristle material for a cosmetic brush of the present invention will be described in more detail with reference to Fig. 1. In Fig. 1, the shaded area represents the sheath portion of the bristle material for a cosmetic brush of the present invention, and the dotted area represents the core portion of the bristle material for a cosmetic brush of the present invention.
In Figure 1, a means the long diameter of the sheath portion of the present invention (hereinafter referred to as sheath long diameter a), b means the width of the depression of the sheath portion (hereinafter referred to as sheath long diameter b), c means the short diameter of the sheath portion (hereinafter referred to as sheath short diameter c), d means the diameter of the depression of the sheath portion (hereinafter referred to as sheath short diameter d), e means the long diameter of the core portion of the present invention (hereinafter referred to as core long diameter e), and f means the short diameter of the core portion (hereinafter referred to as core short diameter f).
In the cosmetic brush hair material of the present invention, the sheath length diameter a is in the range of 100 μm or more and 200 μm or less, preferably in the range of 105 μm or more and 170 μm or less, and more preferably in the range of 110 μm or more and 160 μm or less. The sheath recess width b is in the range of 40% or more and 75% or less of the sheath length diameter a, the sheath minor diameter c is in the range of 10 μm or more and 100 μm or less, and the sheath recess diameter d is in the range of 40% or more and 95% or less of the sheath minor diameter c. The aspect ratio (a/d) of the sheath length diameter a to the sheath recess diameter d is preferably in the range of 1 to 3. In addition, the ratio (d/c) of the sheath recess diameter d to the sheath minor diameter c is preferably in the range of 0.4 to less than 1.0.
In the hair material for cosmetic brushes of the present invention, the ratio of the core length diameter e to the sheath length diameter a (e/a) is preferably in the range of 0.5 to 0.9, more preferably in the range of 0.6 to 0.8, and the ratio of the core minor diameter f to the sheath minor diameter c (f/c) is preferably in the range of 0.5 to 0.9, more preferably in the range of 0.6 to 0.8.
When the sheath long diameter a, sheath recess width b, sheath short diameter c, sheath recess diameter d, core long diameter e, and core short diameter f are within the above ranges, excellent performance is exhibited in terms of catch and release properties for powdered or liquid cosmetics.

The cosmetic brush hair material of the present invention has an S-twist or Z-twist structure, a cocoon-shaped cross section, and a two-layer structure with a core and sheath made of different materials. The combination of these three specific three-dimensional shapes exerts a synergistic effect, providing a good balance between softness and resilience, and providing both softness and elasticity that is excellent in tactile sensation to the skin. Furthermore, the material exhibits excellent initial release properties in terms of catch-and-release properties for powdered or liquid cosmetics, particularly in terms of release properties (discharge properties) for powdered or liquid cosmetics.

The hair material for cosmetic brushes of the present invention is made of a core-sheath composite monofilament having a core made of synthetic resin A and a sheath made of synthetic resin B of a different type from synthetic resin A.
Here, "different types" in the present invention means that the types of synthetic resins constituting synthetic resin A and synthetic resins constituting synthetic resin B are slightly different. In the examples described later, for example, the core in Example 1 is made of polybutylene terephthalate, and the sheath is made of polytrimethylene terephthalate. In this manner, the embodiment in which the synthetic resin A constituting the core, which is polybutylene terephthalate, and the synthetic resin B constituting the sheath, which is polytrimethylene terephthalate, are different types is specified in the present invention as "the core is made of synthetic resin A, and the sheath is made of synthetic resin B, which is a different type from synthetic resin A."
Similarly, in Example 2, the core is composed of polybutylene terephthalate and the sheath is composed of polytrimethylene terephthalate and polybutylene terephthalate, which is also a specific example showing an embodiment in which the synthetic resin A constituting the core and the synthetic resin B constituting the sheath are of different types.
The synthetic resin A and the synthetic resin B may be one or more of polyamide resins, polyolefin resins, polyester resins, etc., or may be used in combination, but it is important that the synthetic resin A and the synthetic resin B are different in type. Among these, it is preferable that the synthetic resin A and the synthetic resin B are selected from polyester resins, since they have appropriate rigidity and durability as bristle materials for cosmetic brushes and are excellent in extrusion processing, twisting processing, taper processing, etc. Among these, it is preferable that the synthetic resin A and the synthetic resin B are each one selected from polyester resins such as polytrimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, and polylactic acid. In particular, it is more preferable that the synthetic resin A and the synthetic resin B are each one selected from polytrimethylene terephthalate (PTT), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT), in terms of having appropriate flexibility and elasticity. The core-sheath composite monofilament of the present invention may contain conventional additives such as heat stabilizers, weather stabilizers, plasticizers, colorants, etc., so long as the object of the present invention is not impaired.

The cosmetic brush of the present invention is characterized in that the cosmetic brush uses the cosmetic brush hair material of the present invention or the cosmetic brush hair material assembly of the present invention at least in part. More specifically, the cosmetic brush of the present invention preferably contains the cosmetic brush hair material of the present invention or the cosmetic brush hair material assembly of the present invention in an amount of 10% by weight or more of the entire cosmetic brush hair material, more preferably 20% by weight or more, even more preferably 25% by weight or more, and particularly preferably 30% by weight or more.
The cosmetic brush of the present invention contains the cosmetic brush bristle material of the present invention or the cosmetic brush bristle assembly of the present invention in an amount ranging from 10% by weight to 100% by weight of the entire cosmetic brush bristle material, thereby enabling the cosmetic brush of the present invention to exhibit superior performance in terms of catch and release properties for powdered or liquid cosmetics compared to cosmetic brushes using natural animal bristle, and also to resemble a cosmetic brush using natural animal bristle in terms of combining softness and elasticity that provides excellent tactile sensation to the skin. In particular, a cosmetic brush of the present invention that contains 30% by weight or more of the cosmetic brush bristle material of the present invention or the cosmetic brush bristle assembly of the present invention in the entire cosmetic brush bristle material can fully exhibit the effects of the present invention.
The cosmetic brush of the present invention can use cosmetic brush bristles made of synthetic fibers such as nylon fibers and polyester fibers, other than the cosmetic brush bristles or the cosmetic brush bristles of the present invention.
In the cosmetic brush of the present invention, the tip of the core-sheath composite monofilament is preferably processed to have a tapered tip portion. More preferably, the tapered tip portion is processed to branch. By processing the tip portion in this manner, the feel on the skin during application of cosmetics is improved, and an excellent feel closer to that of natural animal hair is obtained.

<Method of manufacturing hair material for cosmetic brushes>
Next, an example of the method for producing the cosmetic brush hair material of the present invention will be described.
To produce a sheath-core composite monofilament for cosmetic brush hair, synthetic resin pellets or powder of synthetic resin A for the core and synthetic resin B for the sheath, which is a different type from synthetic resin A, are prepared, and these, along with additives as necessary, are fed into a composite melt spinning machine and co-extruded from a core-sheath composite nozzle that corresponds to the cross-sectional shape of the hair material of the present invention. The core-sheath composite monofilament is then cooled and solidified, and heated and drawn to spin the monofilament into a cocoon-shaped cross-section.
After twisting the core-sheath composite monofilament with the above-mentioned number of twists, the twisted core-sheath composite monofilament is heated at a temperature below the melting point of the synthetic resin to be heat-set. The heat-setting time depends on the temperature, but is, for example, about 5 minutes at 185°C dry heat. This fixes the twisted structure and makes the shape stable without being affected by the usage environment. The heat-set core-sheath composite monofilament is then cut to a predetermined length, for example, 25 mm or more, preferably 50 mm to 100 mm.

The cut core-sheath composite monofilament may have a tapered tip at the tip, if necessary. To do this, the cut core-sheath composite monofilament is immersed from the tip to the center in a strong alkaline solution (e.g., aqueous sodium hydroxide solution) containing a catalyst for promoting hydrolysis and maintained at a constant temperature. After immersion for a predetermined time, the core-sheath composite monofilament is pulled up, and the tip of the core-sheath composite monofilament becomes tapered and a sharp tip is formed. The core-sheath composite monofilament obtained by this method has a nearly beautiful tapered tip. In addition, by appropriately setting the immersion time, the cocoon-shaped constricted portion of the cross section of the core-sheath composite monofilament dissolves, and the tip of the tip is branched into two and sharpened, resulting in a cosmetic brush hair material. This method is preferable because it allows the easy formation of a cosmetic brush hair material with a branched tip. The length of the tip may be in the range of 1 to 30 mm depending on the purpose and application, and the length of the branched portion may be in the range of 0.1 to 20 mm.

The bundle of core-sheath composite monofilaments is then washed with water and dried, and combed and twisted to form a single cosmetic brush hair material.
The hair material for cosmetic brushes thus obtained has a cocoon-shaped cross section perpendicular to the fiber axis of the monofilament, and has a specific cross-sectional shape and helical structure due to the traces of the thermally set twist. By carrying out an alkali treatment, a hair material for cosmetic brushes with a branched tip can be obtained.
Furthermore, a dyeing treatment may be carried out as necessary. A disperse dye may be used as the dye, but one having a weather fastness of grade 5 or higher is preferred because it is less likely to discolor or fade when the cosmetic brush is used. A known dye carrier may be used in combination with the dye, but high-pressure dyeing that does not require a dye carrier is preferred. Carbon black and various pigments may also be added to the raw materials for producing the monofilament. This is preferred because not only can the dye be saved during dyeing, but dyeing is not necessary depending on the application.

<Cosmetic brush hair assembly>
The cosmetic brush hair assembly of the present invention is a mixed assembly of S-twisted and Z-twisted cosmetic brush hairs. When a cosmetic brush is made using an assembly of cosmetic brush hairs containing a mixture of S-twisted and Z-twisted cosmetic brush hairs, the flow of the hairs at the tip of the application part becomes random, and the amount of powdered or liquid cosmetic material collected and held becomes uniform, which is preferable. Depending on the user's usage and usage habits, cosmetic brushes can be twisted in a certain direction and the application part can become kinked, but by mixing S-twisted and Z-twisted hairs, this kinking is less likely to occur, and the durability of the cosmetic brush is further improved, which is preferable.
In the cosmetic brush hair assembly of the present invention, it is preferable that the S-twisted cosmetic brush hairs and the Z-twisted cosmetic brush hairs are mixed in a ratio of 4:6 to 6:4. By using a cosmetic brush hair assembly mixed in a ratio of 4:6 to 6:4 in the application part of a cosmetic brush, the application part has more internal voids and has a three-dimensional feel, and is more similar to an applicator using natural animal hair, allowing for uniform application of powdered or liquid cosmetics. Furthermore, it is preferable that the S-twisted cosmetic brush hairs and the Z-twisted cosmetic brush hairs are mixed almost uniformly. This "mixed almost uniformly" means that the S-twisted cosmetic brush hairs and the Z-twisted cosmetic brush hairs are not clumped together and localized, but are dispersed. For example, this refers to a state in which S-twisted cosmetic brush hairs and Z-twisted cosmetic brush hairs are arranged almost alternately over almost the entire application part of the cosmetic brush, such that Z-twisted cosmetic brush hairs are arranged next to S-twisted cosmetic brush hairs, and conversely, S-twisted cosmetic brush hairs are arranged next to Z-twisted cosmetic brush hairs. By mixing the S-twisted cosmetic brush hairs and the Z-twisted cosmetic brush hairs almost uniformly, adjacent cosmetic brush hairs are prevented from sticking to each other and becoming crowded, making it easier for gaps to form between the cosmetic brush hairs, and a fluffy, voluminous cosmetic brush can be formed.
Furthermore, the application part of the cosmetic brush, which is an almost uniform mixture of S-twisted cosmetic brush hair material and Z-twisted cosmetic brush hair material, preferably has a bristle density of 0.3 g/cm ³ to 0.5 g/cm ^3. If the bristle density of the application part of the cosmetic brush is within the above-mentioned range, the application part will have a three-dimensional feel and the tip of the application part will widen and have a sense of volume, making it similar to an applicator that uses natural animal hair and suitable for applying powdered or liquid cosmetics.

<Method of manufacturing cosmetic brushes>
An example of a method for producing a cosmetic brush using the cosmetic brush hair material or the assembly of cosmetic brush hair materials of the present invention obtained by the above-mentioned production method will be described.
The cosmetic brush hair material or cosmetic brush hair material assembly of the present invention is contained in at least a portion of the entire cosmetic brush hair material, preferably at 10% by weight or more, more preferably at 20% by weight or more, even more preferably at 25% by weight or more, and particularly preferably at 30% by weight or more, and is placed in a pot for forming the brush tip, and a tip portion with a raised center is formed according to the internal shape of the pot while being vibrated, and the formed tip portion is then inserted into a cylindrical nozzle provided at the end of the cosmetic brush handle to form a cosmetic brush.

The cosmetic brush of the present invention is suitable for uniformly applying powder or liquid cosmetics, and can be used as various cosmetic brushes, for example, liquid brushes, lip brushes, nail care brushes, foundation brushes, powder brushes, eyeshadow brushes, blush brushes, highlight brushes, concealer brushes, etc. In particular, it is suitable for the method of applying powder cosmetics while spreading it thinly on the skin surface, so-called blending, and exhibits excellent performance when used as a face brush, blush brush, highlight brush, or shadow brush for eye shadow, etc., which frequently uses such application methods.

The present invention will be explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

<Production examples of the cosmetic brush hair material and cosmetic brush of the present invention>
Example 1 (Cosmetic Brush 1)
60 core-sheath composite fibers (core component: polybutylene terephthalate, sheath component: polytrimethylene terephthalate, fineness 80 decitex) having a cocoon-shaped cross section were twisted in an S-twist direction (S-twist) and in a Z-twist direction (Z-twist) at a twisting rate of 80 T/m (twist/m) using a twisting machine. The twists were then fixed by dry heat treatment at 185°C for 5 minutes to obtain S-twisted and Z-twisted cosmetic brush hair assemblies with a wavelength width of 11 mm.
Next, the S-twist and Z-twist of the cosmetic brush hair material assembly were mixed and aligned in a 1:1 ratio to create a fiber bundle with a diameter of 4 cm, which was then wrapped with paper for protection. This fiber bundle was cut to a length of 8 cm to create a roller with a diameter of 4 cm and a length of 8 cm. Furthermore, an aqueous solution of 100 g/L sodium hydroxide and 6 g/L quaternary amine (manufactured by Ipposha Yushi Kogyo Co., Ltd., product name "DYK-1125") was prepared, and the tapered fiber bundle was dyed. The twist was then combed with a comb and the bristles were placed in a concave pot with the bristles facing down and vibrated to create a cosmetic brush 1 with the bristles shaped.

Example 2 (Makeup Brush 2)
Cosmetic brush 2 was produced in the same manner as in the manufacturing example of Example 1 above, except that 60 core-sheath composite fibers (core component: polybutylene terephthalate, sheath component: polytrimethylene terephthalate + polybutylene terephthalate, fineness 80 decitex) having a cocoon-shaped cross-sectional shape were used, with a twisting machine twisting the fibers in an S-shaped direction (S-twist) and in a Z-shaped direction (Z-twist) at a twisting number of 80 T/m (twist/m).

Example 3 (Makeup Brush 3)
A cosmetic brush 3 was produced in the same manner as in the manufacturing example of Example 1 above, except that 60 core-sheath composite fibers (core component: polyethylene terephthalate elastomer, sheath component: polytrimethylene terephthalate, fineness 80 decitex) having a cocoon-shaped cross-sectional shape were used, with a twisting machine twisting the fibers in an S-shaped direction (S-twist) and in a Z-shaped direction (Z-twist) at a twisting number of 80 T/m (twist/m).

Example 4 (Makeup Brush 4)
A cosmetic brush 4 was produced in the same manner as in Example 1, except that the fibers produced in Example 1 and untwisted fibers of Example 1 were mixed in a 1:1 ratio.

Example 5 (Makeup Brush 5)
A cosmetic brush 5 was produced in the same manner as above, except that the fibers produced in Example 2 and untwisted fibers of Example 2 were mixed in a 1:1 ratio.

Example 6 (Makeup Brush 6)
A cosmetic brush 6 was produced in the same manner as above, except that the fibers produced in Example 3 and untwisted fibers of Example 3 were mixed in a 1:1 ratio.

Comparative Example 1 (Comparative Cosmetic Brush 1)
Comparative cosmetic brush 1 was produced in the same manner as in Example 1, except that 60 core-sheath composite fibers (core component: polyethylene terephthalate elastomer, sheath component: polytrimethylene terephthalate, fineness 100 decitex) having a circular cross-sectional shape were used, with one twisted in an S-shaped direction (S-twist) and the other twisted in a Z-shaped direction (Z-twist) at a twisting machine with a number of 80 T/m (twist/m).

Comparative Example 2 (Comparative Cosmetic Brush 2)
Comparative cosmetic brush 2 was produced in the same manner as in Example 1, except that 60 core-sheath composite fibers (core component: polyethylene terephthalate elastomer, sheath component: polytrimethylene terephthalate, fineness 80 decitex) having a circular cross-sectional shape were used, with one twisted in an S-direction (S-twist) and the other twisted in a Z-direction (Z-twist) at a twisting machine with a number of 80 T/m (twist/m).

Comparative Example 3 (Comparative Cosmetic Brush 3)
Comparative cosmetic brush 3 was produced in the same manner as in Example 1, except that 60 core-sheath composite fibers (core component: polyethylene terephthalate elastomer, sheath component: polybutylene terephthalate, fineness 80 decitex) having a circular cross-sectional shape were used, with one twisted in an S-direction (S-twist) and the other twisted in a Z-direction (Z-twist) at a twisting machine with a number of 80 T/m (twist/m).

Comparative Example 4 (Comparative Cosmetic Brush 4)
Comparative cosmetic brush 4 was produced in the same manner as in Example 1, except that 60 core-sheath composite fibers (core component: polyethylene terephthalate elastomer, sheath component: polybutylene terephthalate + polytrimethylene terephthalate, fineness 80 decitex) having a circular cross-sectional shape were used, with one twisted in an S-direction (S-twist) and the other twisted in a Z-direction (Z-twist) at a twisting machine with a number of 80 T/m (twist/m).

Comparative Examples 5 to 7 (Comparative Cosmetic Brushes 5 to 7)
Comparative cosmetic brushes 5 to 7 were prepared in the same manner as Comparative Examples 2 to 4, except that the fineness of the brush was changed to 60 dtex.

<Evaluation of cosmetic brush usability 1: Evaluation of powder catchability>
A test was carried out to evaluate the powder catchability (holdability) of the cosmetic brush of the present invention. In the present invention, the powder catchability (holdability) refers to the adhesion of powdered cosmetic material to the cosmetic brush.
(Test specimen)
In addition to the cosmetic brushes 1 to 6 and comparative cosmetic brushes 1 to 7 manufactured according to the above manufacturing examples, a commercially available goat hair (Soukouho) cosmetic brush that is highly regarded by consumers as the highest quality animal hair cosmetic brush was used as the evaluation standard to evaluate the powder catchability (holdability) of a powder cosmetic material (Integrate Mineral Glow Pressed Powder, manufactured by Shiseido Co., Ltd.) using a surface property tester (Trinity Lab Co., Ltd., product name: Trilab Handy Lab Tester Type: TL701).
(Test method)
A circular container (diameter: 5.5 cm) filled with a powdered cosmetic material was attached to the contact of the surface property tester with double-sided tape approximately perpendicularly. Each test specimen was attached to a rotating table so that the tip of the cosmetic brush contacted the surface of the powdered cosmetic material at approximately a right angle, and fixed horizontally to the test table.
The tip of the cosmetic brush was swept over the surface of the powdered cosmetic ten times (speed: 6 rpm, rotation radius: 100 mm, rotation angle: 90 degrees) to allow the tip of the cosmetic brush to pick up the powdered cosmetic.
The powder catchability of each test specimen was evaluated by measuring the weight of the cosmetic brush before and after the test, and the weight difference was expressed as the amount of powder caught 10 times (hereinafter referred to as "powder catch amount").
In addition, for an unused cosmetic brush, the surface of the powdered cosmetic was swept 10 times using the above-mentioned test method to collect the powdered cosmetic, and then the cosmetic brush was swept across tissue paper until no more powdered cosmetic adhered to the tissue, and this was used as a test specimen.
The test was carried out twice, and the average value of each test sample was compared with the "pickup amount" of the animal hair cosmetic brush and evaluated according to the following criteria. The results are summarized in Table 1 below.
[Evaluation criteria]
1: 1x or more the amount of makeup contained in an animal hair makeup brush 2: 0.8x or more and less than 1x the amount of makeup contained in an animal hair makeup brush 3: Less than 0.8x the amount of makeup contained in an animal hair makeup brush

As shown in Table 1 below, it was confirmed that the cosmetic brushes 1 to 6 made of the cosmetic brush hair material of the present invention had about 1.1 to 1.6 times more powder catch than a commercially available cosmetic brush made of goat hair. Also, it was confirmed that the cosmetic brushes 1 to 6 had about 1.2 to 2.2 times more powder catch than the comparative brushes 1 to 7 made of core-sheath composite monofilament having a circular cross-sectional shape.
The evaluation results made clear that the hair material for cosmetic brushes of the present invention exerts a synergistic effect by combining three specific three-dimensional shapes: twisting, a specific cross-sectional shape, and a core-sheath structure, and can be used to create a cosmetic brush with excellent powder-catching (holding) properties.

<Evaluation of cosmetic brush usability 2: Evaluation of color development and spreadability>
(Test specimen)
In addition to the same cosmetic brushes 1 to 6 and comparative cosmetic brushes 1 to 7 as in "Evaluation 1 of the usability of cosmetic brushes," a commercially available cosmetic brush made of goat hair (Soukouho), which is highly regarded by consumers as the highest quality animal hair cosmetic brush, was used as the evaluation standard, and a powder cosmetic (Integrate Mineral Glow Pressed Powder, manufactured by Shiseido Co., Ltd.) was used to evaluate.
(Test method)
The cosmetic brush, which is a test specimen, was rotated three times on the surface of the powdered cosmetic, and the tip of the cosmetic brush was made to pick up the powdered cosmetic, which was then rotated ten times on tissue paper. The color development and spread of the cosmetic on the tissue paper were evaluated by 10 panelists (adult females) according to the following evaluation criteria, and the most common evaluations are summarized in Table 1 below as evaluation results. In addition, A and B in the following evaluation criteria are practically acceptable as a cosmetic brush, and C and D are practically problematic as a cosmetic brush.
[Evaluation criteria]
A: The color is the same as with a animal hair cosmetic brush, and the product spreads evenly.
B: Color development: The same as with an animal hair cosmetic brush. The spreading range is narrower than A, but the application is uniform.
C: Color: Weaker than that of an animal hair makeup brush, and spread is the same as B.
D: Color development: weaker than that of animal hair makeup brushes, and the spread range is narrower than B.

As shown in Table 1 below, it was confirmed that cosmetic brushes 1 to 6 made of the cosmetic brush hair material of the present invention are cosmetic brushes with no practical problems in terms of color development and spreading. On the other hand, it was revealed that comparative example brushes 1 to 7 made of core-sheath composite monofilament with a circular cross-sectional shape are cosmetic brushes with practical problems in terms of color development and spreading.

<Evaluation of cosmetic brush usability 3: Evaluation of feel on skin>
(Test specimen)
In addition to the same cosmetic brushes 1 to 6 and comparative cosmetic brushes 1 to 7 as in "Evaluation 1 of the usability of cosmetic brushes" above, a commercially available cosmetic brush made of goat hair (Soukouho), which is highly regarded by consumers as the highest quality animal hair cosmetic brush, was used as the evaluation standard.
(Test method)
Ten panelists (adult women) used the test specimen, a makeup brush, on their own skin and evaluated its tactile sensation according to the following evaluation criteria, with the most common evaluations being summarized in the following Table 1. In addition, evaluation criteria 1 and 2 below indicate that there is no practical problem as a makeup brush, and 3 indicates that there is a problem in practical use as a makeup brush.
[Evaluation criteria]
1: It moves flexibly on the skin surface, conforms to the skin surface as a whole, and has a good tactile sensation.
The feel is slightly inferior to that of 2:1, but this does not pose a problem in practical use.
3: Lacking appropriate tension and flexibility, the hair strands are uneven and have a poor feel.

As shown in Table 1 below, it was confirmed that cosmetic brushes 1 to 6 made of the cosmetic brush hair material of the present invention have excellent or good tactile sensation and are cosmetic brushes with no practical problems. On the other hand, it was revealed that comparative example brushes 1 to 7 made of core-sheath composite monofilament with a circular cross-sectional shape are cosmetic brushes with poor tactile sensation and are problematic in practical use.

<Evaluation of cosmetic brush usability 4: Evaluation of elasticity and softness>
(Test specimen)
In addition to the cosmetic brushes 1 to 6 and comparative cosmetic brushes 1 to 7 that were the same as those in "Evaluation of the usability of cosmetic brushes 1" above, a commercially available cosmetic brush made of goat hair (Soukouho), which is highly regarded by consumers as the highest quality animal hair cosmetic brush, was used as the evaluation standard, and evaluation was performed using a surface property tester (manufactured by Trinity Lab Co., Ltd., product name: Trilab Handy Lab Tester Type: TL701).
(Test method)
Each test specimen was attached to a rotating table so that the tip of the cosmetic brush as a test specimen was in contact with the surface of the contact of the surface property tester at a substantially right angle, and was fixed horizontally to the test table.
The tip of the cosmetic brush was moved horizontally against the surface of the contact of the surface property tester (speed: 6 rpm, rotation angle: 90 degrees), and the maximum force applied in the vertical and horizontal directions was measured.
The vertical measurement value is the force with which the bristles of the makeup brush try to recover, and is evaluated as an indicator of the elasticity of the makeup brush, while the horizontal measurement value is the force with which the contacts are pressed, and is evaluated as an indicator of the softness of the makeup brush.
The measurements were carried out three times, and the average values are shown in Table 1 below and FIG.

As shown in Table 1 and Figure 4 below, it has become clear that cosmetic brushes 1 to 6 made from the cosmetic brush hair material of the present invention are cosmetic brushes that combine elasticity and softness compared to comparative example brushes 1 to 7 made from core-sheath composite monofilament having a circular cross-sectional shape.

The evaluation results of "Evaluation of cosmetic brush usability 1 to 4" are summarized in Table 1. In Table 1, "PBT" means polybutylene terephthalate, "PTT" means polytrimethylene terephthalate, and "PET" means polyethylene terephthalate.

The hair material for cosmetic brushes of the present invention has three specific three-dimensional shapes: twist, i.e., S-twist or Z-twist, a specific cross-sectional shape in the shape of a cocoon, and a core-sheath structure. The two-layer structure of the core and sheath made of different materials provides a good balance between softness and resilience, and the hair material is similar to or superior to cosmetic brushes made of natural animal hair in terms of both softness and elasticity that are excellent in tactile sensation to the skin. The combination of the three specific three-dimensional shapes also provides an effect that is greater than the additive effect, and achieves better performance than natural animal hair in terms of catch and release properties for powdered or liquid cosmetics. Furthermore, the tapered tip portion makes it possible to provide a hair material for cosmetic brushes that has a tactile sensation comparable to that of natural animal hair, as well as elasticity and softness, which is useful.

Claims (7)

The core is made of synthetic resin A and the sheath is made of synthetic resin B, which is different from synthetic resin A, and the sheath is made of S-twisted or Z-twisted core-sheath composite monofilament.
The synthetic resin A is polybutylene terephthalate or polyethylene terephthalate,
The synthetic resin B is polytrimethylene terephthalate or polytrimethylene terephthalate and polybutylene terephthalate,
A cosmetic brush bristle material, characterized in that the cross section of the core-sheath composite monofilament in the direction perpendicular to the fiber axis is cocoon-shaped. The cosmetic brush hair material according to claim 1, characterized in that the core-sheath composite monofilament has a tapered portion. The cosmetic brush bristle material according to claim 2, characterized in that the tapered portion is branched. The cosmetic brush bristle material according to any one of claims 1 to 3, characterized in that the synthetic resin A and the synthetic resin B are both polyester-based resins. The cosmetic brush bristle material according to claim 4, characterized in that the synthetic resin A and the synthetic resin B are each one selected from polytrimethylene terephthalate, polyethylene terephthalate, and polybutylene terephthalate. The fiber is made of a mixed assembly of S-twisted and Z-twisted core-sheath composite monofilaments, each of which has a core made of synthetic resin A and a sheath made of synthetic resin B of a different type from synthetic resin A.
The synthetic resin A is polybutylene terephthalate or polyethylene terephthalate,
The synthetic resin B is polytrimethylene terephthalate or polytrimethylene terephthalate and polybutylene terephthalate,
A bristle assembly for a cosmetic brush, characterized in that the cross sections of the core-sheath composite monofilament in a direction perpendicular to the fiber axis are similar to each other in cocoon-shaped form. A cosmetic brush, characterized in that at least a portion of the cosmetic brush hair material according to any one of claims 1 to 5 or the cosmetic brush hair material assembly according to claim 6 is used.