阅读说明：本技术 人工毛发纤维 (Artificial hair fiber ) 是由 宫田浩司 堀端笃 园田一仁 武井淳 于 2017-03-21 设计创作，主要内容包括：可防止芯部和鞘部的剥离,可提供具有和人发相似的良好触感,且卷曲维持性优良的人工毛发纤维。根据本发明,可获得一种人工毛发纤维,其特征在于,具有由芯部以及覆盖所述芯部的鞘部构成的芯/鞘结构,所述芯部由含有聚酯的芯部树脂组合物构成,所述鞘部由含有聚酰胺的鞘部树脂组合物构成,所述芯部及所述鞘部的芯/鞘质量比为40/60～90/10,所述芯部树脂组合物的聚酯的熔融粘度a与所述鞘部树脂组合物的聚酰胺的熔融粘度b的粘度比a/b为0.5～2.5。(Can prevent the peeling of the core part and the sheath part, and can provide the artificial hair fiber which has good touch similar to human hair and has excellent curl maintaining performance. According to the present invention, there is provided an artificial hair fiber having a core/sheath structure comprising a core part and a sheath part covering the core part, wherein the core part is composed of a core part resin composition containing a polyester, the sheath part is composed of a sheath part resin composition containing a polyamide, the core/sheath mass ratio of the core part and the sheath part is 40/60 to 90/10, and the viscosity ratio a/b of the melt viscosity a of the polyester of the core part resin composition to the melt viscosity b of the polyamide of the sheath part resin composition is 0.5 to 2.5.)

1. An artificial hair fiber characterized in that,

the core-sheath structure comprises a core part and a sheath part covering the core part, wherein the core part is composed of a core part resin composition containing polyester, the sheath part is composed of a sheath part resin composition containing polyamide, the core/sheath mass ratio of the core part and the sheath part is 70/30-90/10, the viscosity ratio a/b of the melt viscosity a of the polyester of the core part resin composition to the melt viscosity b of the polyamide of the sheath part resin composition is 0.5-2.5,

the polyester of the core resin composition is composed of polyethylene terephthalate and polybutylene terephthalate, or is composed of polyethylene terephthalate and polytrimethylene terephthalate.

2. The artificial hair fiber according to claim 1,

the core resin composition contains at least one brominated flame retardant selected from the group consisting of benzyl brominated acrylate, brominated phenol, polydibromophenyl ether, brominated polystyrene, ethylenebistetrabromophthalimide, decabromodiphenylethane, brominated epoxy groups, brominated phenoxy groups, brominated polycarbonate, and triazine compounds containing bromine.

3. The artificial hair fiber according to claim 1 or 2,

the sheath resin composition contains at least one brominated flame retardant selected from the group consisting of benzyl brominated acrylate, brominated phenol, polydibromophenyl ether, brominated polystyrene, ethylenebistetrabromophthalimide, decabromodiphenylethane, brominated epoxy groups, brominated phenoxy groups, brominated polycarbonate, and triazine compounds containing bromine.

4. The artificial hair fiber according to claim 2,

the core resin composition is added in an amount of 3 to 30 parts by mass per 100 parts by mass of the polyester.

5. The artificial hair fiber according to claim 3,

the sheath resin composition is added in an amount of 3 to 30 parts by mass per 100 parts by mass of the polyamide.

6. The artificial hair fiber according to claim 1 or 2,

the core resin composition contains 0.5 to 3 parts by mass of a compatibilizer per 100 parts by mass of a polyester.

7. The artificial hair fiber according to claim 1 or 2,

the sheath resin composition contains 0.5 to 3 parts by mass of a compatibilizer per 100 parts by mass of polyamide.

8. The artificial hair fiber according to claim 1 or 2,

the polyamide of the sheath resin composition is composed of nylon 66 and nylon 6, and the mass ratio of the nylon 66 to the nylon 6 is 70/30-95/5.

Technical Field

The present invention relates to a fiber (hereinafter, simply referred to as "artificial hair fiber") used for artificial hair such as a wig which can be worn on the head.

Background

Vinyl chloride is proposed as a material constituting artificial hair fibers in patent document 1. This is because vinyl chloride has excellent processability for artificial hair fibers and is low in cost.

However, in the artificial hair fiber made of vinyl chloride, since the glass transition temperature of vinyl chloride is around 80 ℃, it is not preferable for the heat resistance of hair clippers, and when curling is performed using hair clippers whose temperature is 100 ℃ or higher, fusion and curling of the fiber occur. As a result, the fibers may be damaged or broken.

Patent document 2 describes artificial hair fibers made of polyester, which have improved heat resistance against hair clippers. However, the artificial hair fiber using polyester as a material has a problem that the touch feeling is harder than that of vinyl chloride fiber. Further, patent document 3 describes that the touch feeling of artificial hair fibers made of polyamide is improved, but the moisture absorption of polyamide lowers the elastic modulus, and the curl retention is deteriorated with time from the initial state of curling.

Patent document 4 describes an artificial hair fiber having a core/sheath structure in which a core portion is made of polyester and a sheath portion is made of polyamide, and solves the conventional problems to some extent while satisfying both the curl retention property of the artificial hair fiber and the feeling close to human hair.

[ Prior Art ] A method for producing a semiconductor device

[ patent document ]

[ patent document 1 ] Japanese patent laid-open No. 2004-156149

[ patent document 2 ] Japanese patent laid-open No. 2006 and 144211

[ patent document 3 ] Japanese patent application laid-open No. 2011-246843

[ patent document 4 ] Japanese patent application laid-open No. 3-185103

Disclosure of Invention

[ problem to be solved by the invention ]

However, the technique of patent document 4 has a problem that the core portion and the sheath portion are easily peeled off.

The present invention has been made in view of such circumstances, and provides an artificial hair fiber which improves the problem of peeling between a core portion and a sheath portion, has a good touch similar to human hair, and is excellent in curl retention.

[ MEANS FOR solving PROBLEMS ] A method for solving the problems

The inventors of the present invention have studied the cause of peeling between the core portion and the sheath portion and found that when the difference in melt viscosity between the polyester of the core portion and the polyamide of the sheath portion is large, the applied force during stretching differs and a difference in orientation degree occurs, as a result, the contraction sizes of the core portion and the sheath portion differ, and heating in curling by a gear oven, a hair clipper, or the like causes peeling between the core portion and the sheath portion. Based on this, the present inventors have found that the above problems can be solved by using an artificial hair fiber having the following structure, and have completed the present invention.

In other words, the present invention solves the above problems by the following means.

(1) An artificial hair fiber having a core/sheath structure comprising a core part and a sheath part covering the core part, wherein the core part is composed of a core resin composition containing a polyester, the sheath part is composed of a sheath resin composition containing a polyamide, the core/sheath mass ratio of the core part and the sheath part is 40/60 to 90/10, and the viscosity ratio a/b of the melt viscosity a of the polyester of the core resin composition to the melt viscosity b of the polyamide of the sheath resin composition is 0.5 to 2.5.

(2) The artificial hair fiber according to item (1), wherein the core resin composition contains at least one brominated flame retardant selected from the group consisting of benzyl bromide acrylate, brominated phenol, polydibromophenyl ether, brominated polystyrene, ethylenebistetrabromophthalimide, bis (pentabromophenyl) ethane, brominated epoxy groups, brominated phenoxy groups, brominated polycarbonate, and triazine compounds containing bromine.

(3) The artificial hair fiber according to the item (1) or (2), wherein the sheath resin composition contains at least one bromine-based flame retardant selected from the group consisting of benzyl bromide acrylate, brominated phenol, polydibromophenyl ether, brominated polystyrene, ethylenebistetrabromophthalimide, bis (pentabromophenyl) ethane, brominated epoxy group, brominated phenoxy group, brominated polycarbonate, and a triazine compound containing bromine.

(4) The artificial hair fiber according to (2) or (3), wherein the core resin composition contains the brominated flame retardant in an amount of 3 to 30 parts by mass based on 100 parts by mass of the polyester.

(5) The artificial hair fiber according to (3) or (4), wherein the amount of the brominated flame retardant added to the sheath resin composition is 3 to 30 parts by mass per 100 parts by mass of the polyamide.

(6) The artificial hair fiber according to any one of (1) to (5), wherein the core resin composition contains 0.5 to 3 parts by mass of a compatibilizer per 100 parts by mass of the polyester.

(7) The artificial hair fiber according to any one of (1) to (6), wherein the sheath resin composition contains 0.5 to 3 parts by mass of a compatibilizer per 100 parts by mass of the polyamide.

(8) The artificial hair fiber according to any one of (1) to (7), wherein the polyester of the core resin composition comprises polyethylene terephthalate and polybutylene terephthalate, and the mass ratio of the polyethylene terephthalate to the polybutylene terephthalate is 40/60 to 90/10.

(9) The artificial hair fiber according to any one of (1) to (7), wherein the polyester of the core resin composition comprises polyethylene terephthalate and polytrimethylene terephthalate, and the mass ratio of the polyethylene terephthalate to the polytrimethylene terephthalate is 40/60 to 90/10.

(10) The artificial hair fiber according to any one of (1) to (9), wherein the polyamide of the sheath resin composition is composed of nylon 66 and nylon 6, and the mass ratio of the nylon 66 to the nylon 6 is 70/30 to 95/5.

[ Effect of the invention ]

According to the present invention, separation of the core part and the sheath part can be prevented, and an artificial hair fiber having a good touch similar to human hair and excellent curl retention can be provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

1. Artificial hair fiber

The artificial hair fiber of the present invention has a core/sheath structure comprising a core part and a sheath part covering the core part, wherein the core part is composed of a core part resin composition containing a polyester, the sheath part is composed of a sheath part resin composition containing a polyamide, the core/sheath mass ratio of the core part and the sheath part is 40/60-90/10, the viscosity ratio a/b of the melt viscosity a of the polyester of the core part resin composition to the melt viscosity b of the polyamide of the sheath part resin composition is 0.5-2.5, and a bromine-based flame retardant and a compatibilizer are appropriately contained.

(1) Mass ratio of core portion to sheath portion

The core/sheath mass ratio of the core part and the sheath part is preferably 40/60-90/10, 0/50-85/15. When the core/sheath mass ratio is less than 40/60, the polyamide in the sheath portion absorbs moisture in the atmosphere, the elastic modulus decreases, and the curl retention property deteriorates with time from the initial state in which the curl is applied. When the thickness exceeds 90/10, the polyamide layer at the sheath part is thin, and a good touch feeling similar to human hair cannot be obtained.

(2) Melt viscosity

The melt viscosity of the polyester or polyamide is a value measured under the following conditions, namely: the polyester pellets or the polyamide pellets were subjected to dehumidification drying so that the moisture absorption rate was 100ppm or less, and the sample amount was 20cc, the set temperature was 285 ℃, the piston speed was 200mm/min, the microtube length was 20mm, and the microtube diameter was 1 mm. The melt viscosity was measured by using Capirograph1D manufactured by Toyo Seiki Seisaku-Sho.

The ratio of the melt viscosity a of the polyester in the core part to the melt viscosity b of the polyamide in the sheath part, i.e., the ratio of a/b, is 0.5 to 2.5, preferably 0.8 to 2.2. When the viscosity ratio is less than 0.5, the melt viscosity of the core is low during spinning, and thus yarn breakage occurs during spinning, which causes problems such as easy separation of the core portion and the sheath portion. When the viscosity ratio exceeds 2.5, a problem arises in the core portion and the sheath portion.

1-1. core part

The core is composed of a core resin composition containing a polyester. The kind of the polyester is not particularly limited, and at least one resin selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate is preferable.

The polyester may be a resin obtained by mixing polyethylene terephthalate and polybutylene terephthalate, and the mass ratio is preferably 40/60 to 90/10, more preferably 50/50 to 70/30. When the mass ratio of the polyethylene terephthalate in the core portion is less than 40/60, the heat resistance tends to be low, and when it is more than 90/10, the effect of improving the touch feeling cannot be obtained.

The polyester may be a resin obtained by mixing polyethylene terephthalate and polypropylene terephthalate, and the mass ratio is preferably 40/60 to 90/10, more preferably 50/50 to 70/30. When the mass ratio of the polyethylene terephthalate in the core portion is less than 40/60, the heat resistance tends to be low, and when it is more than 90/10, the effect of improving the touch feeling cannot be obtained.

In the core resin composition, the resin component is preferably only polyester, but may contain other resins. The mass ratio of the polyester to the whole resin component in the core resin composition is preferably 0.8 or more, more preferably 0.9 or more, and still more preferably 1.

1-2 sheath part

The sheath part is composed of a sheath part resin composition containing polyamide. The type of the polyamide is not particularly limited, and at least 1 resin selected from the group consisting of nylon 6, nylon 66, nylon 46, nylon 12, nylon 610, nylon 612, polyamide 6T, polyamide 9T, polyamide 10T, and modified polyamide 6T, modified polyamide 9T, and modified polyamide 10T obtained by copolymerizing these with a modifying monomer is preferable, and nylon 66 and nylon 6 are particularly preferable.

The polyamide used for the sheath portion of the present invention can provide a good touch feeling more similar to human hair by a resin obtained by mixing nylon 66 and nylon 6.

The mass ratio of the nylon 66 to the nylon 6 in the sheath portion is preferably 70/30 to 95/5, and more preferably 80/20 to 90/10. When the mass ratio of the nylon 66 in the sheath portion is less than 70/30, the heat resistance tends to be low, and when it is more than 95/5, the effect of improving the touch feeling cannot be obtained.

In the sheath resin composition, the resin component preferably contains only polyamide, but may contain other resins. The mass ratio of the polyamide/the whole resin component in the sheath resin composition is preferably 0.8 or more, more preferably 0.9 or more, and still more preferably 1.

1-3 flame retardant

At least one (preferably both) of the core resin composition and the sheath resin composition may contain a flame retardant. When the flame retardant is added to at least one of the core resin composition and the sheath resin composition, the flame retardant is dispersed at the interface between the polyester in the core and the polyamide in the sheath, thereby improving the peeling resistance and imparting flame retardancy. As the flame retardant, there are a bromine-based flame retardant, a phosphorus-based flame retardant, a nitrogen-based flame retardant, a hydrated metal compound and the like, but a combination of a bromine-based flame retardant and a flame retardant auxiliary agent is preferable because the effect of flame retardancy is high.

Examples of the bromine-based flame retardant include: brominated polystyrene flame retardants, ethylene bistetrabromophthalimide flame retardants, bis (pentabromophenyl) ethane flame retardants, brominated epoxy flame retardants, brominated phenoxy flame retardants, brominated benzyl acrylate flame retardants, brominated phenol flame retardants, polydibromophenylether flame retardants, and the like. Among them, a brominated epoxy-based resin or a brominated phenoxy-based resin is preferable in view of the balance of flame retardancy, processability, yarn transparency, and the like.

The amount of the bromine-based flame retardant to be added is preferably 3 to 30 parts by mass, more preferably 5 to 25 parts by mass, based on 100 parts by mass of the polyester in the core portion or the polyamide in the sheath portion. When the amount is less than 3 parts by mass, flame retardancy cannot be obtained, and when the amount is more than 30 parts by mass, poor dispersion with the resin occurs, resulting in poor spinnability.

The bromine-based flame retardant may be used in combination with a flame retardant aid for the purpose of improving flame retardancy. Examples of the flame retardant aid include: antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, zinc borate and sodium stannate. Among them, antimony trioxide is preferable in view of the balance between the drip resistance and the transparency of the yarn.

The amount of the flame retardant auxiliary added is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the polyester in the core portion or the polyamide in the sheath portion. When the amount is less than 0.1 part by mass, the effect of the flame retardant aid is low, and when the amount is more than 10 parts by mass, yarn breakage due to poor dispersion occurs, and stable spinning is difficult to obtain.

The flame retardant aid preferably has an average particle diameter in the range of 0.5 to 10 μm, and more preferably in the range of 1 to 8 μm, from the viewpoint of transparency and processability of the yarn. When the particle diameter is less than 0.5. mu.m, dispersion failure occurs due to aggregation, and when the particle diameter is more than 10 μm, white turbidity occurs.

1-4. compatibilizer

At least one (preferably both) of the core resin composition and the sheath resin composition may contain a compatibilizer. By adding a compatibilizer to at least one of the core resin composition and the sheath resin composition, the peeling resistance at the interface between the core and the sheath is increased, and ironing and winding can be performed at a higher temperature.

Examples of the compatibilizer include: maleic anhydride modified polymer, ethylene/butyl acrylate maleic anhydride modified product, polyvalent carbodiimide, carbodiimide modified isocyanate, styrene-acrylonitrile-glycidyl methacrylate random copolymer, epoxy-styrene-acrylonitrile copolymer microgel, styrene-acrylonitrile-maleic anhydride acid copolymer, LLDPE-maleic anhydride graft polymer, polyolefin-glycidyl methacrylate graft polymer, modified polyolefin, styrene/maleic acid half ester copolymer, styrene/maleic anhydride copolymer, styrene/maleic acid half ester copolymer. Among them, a maleic anhydride-modified polymer is preferable because the terminal carboxyl group of the polyester in the core portion and the terminal amino group of the polyamide in the sheath portion react with each other via a compatibilizer to suppress interfacial separation between the core portion and the sheath portion.

The amount of the compatibilizer is preferably 0.5 to 3 parts by mass based on 100 parts by mass of the polyester in the core part or the polyamide in the sheath part. When the amount is less than 0.5 parts by mass, the effect of improving the peeling resistance is small, and when the amount is more than 3 parts by mass, the viscosity of the polyester in the core portion or the polyamide in the sheath portion is remarkably decreased or the viscosity is remarkably decreased, which is not preferable from the viewpoint of processability.

The polyester used in the core of the present invention is a resin obtained by mixing polyethylene terephthalate and polybutylene terephthalate or polytrimethylene terephthalate, and can provide a good touch feeling more similar to human hair.

1-5. other ingredients

At least one (preferably both) of the core resin composition and the sheath resin composition may contain additives such as a heat stabilizer, a light stabilizer, a fluorescent agent, an antioxidant, an antistatic agent, a pigment, a dye, a plasticizer, and a lubricant, as required. By incorporating a colorant such as a pigment or a dye, a pre-colored fiber (so-called as-spun fiber) can be obtained.

2. Method for producing artificial hair fiber

An example of the process for producing artificial hair fibers will be described below, but the present invention is not limited thereto.

The method for producing the artificial hair fiber having the core/sheath structure of the present invention is not particularly limited as long as it is a method for producing an artificial hair fiber having a core/sheath structure. For example, it can be obtained by using a melt compounding extruder composed of two extruders for core molding and sheath molding.

(1) Melt spinning step

The core resin composition pellet and the sheath resin composition pellet are obtained by dry-mixing a thermoplastic resin such as a polyester and a polyamide in the core and additives such as the flame retardant, the compatibilizer, and the pellets at a predetermined ratio, and then melt-kneading them using a kneader. As the melt kneading apparatus, various ordinary kneading machines can be used. Examples of the melt-kneading include a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, and a kneader. Among these, the twin-screw extruder is preferable because of adjustment of the kneading degree and ease of operation.

The core resin composition pellet and the sheath resin composition pellet obtained by melt kneading are dried independently of each other. The polymer can be dried by appropriately selecting a known apparatus such as a vacuum dryer, a hopper dryer, or the like. In the case of the core resin composition pellet, the moisture content of the pellet is preferably 100ppm or less (100mg/kg or less). In the case of the sheath resin composition pellet, the moisture content of the pellet is preferably 1000ppm or less (1000mg/kg or less). When the water content of the core resin composition particles and the sheath resin composition particles is relatively high, there is a possibility that the viscosity at the time of spinning is lowered or the molecular weight is lowered due to hydrolysis. As described above, by using a material in which the water content of the pellets is maintained at a certain value or less, the spinning workability can be further improved.

The dried pellets of the core resin composition are fed to an extruder for constituting the core, and the dried pellets of the sheath resin composition are fed to an extruder for constituting the sheath. The core resin composition pellet and the sheath resin composition pellet are respectively melted and kneaded by an extruder, introduced into a spinneret so that the core resin composition becomes a core and the sheath resin composition becomes a sheath, and melt-spun from a core/sheath composite nozzle. In the melt spinning, for example, melt spinning is performed with the temperature of a melt spinning device such as an extruder, a gear pump, a head or the like set to 270 to 310 ℃, air cooling is performed by using a cooling air duct, cooling and solidification are performed to below the glass transition point, cooling and solidification are performed, and then a spinning finish is applied by using an oiling assisting device. The temperature and length of the cooling tower, the temperature and spray amount of the cooling tower, the cooling time, and the drawing speed can be appropriately adjusted according to the discharge amount and the number of holes of the head. In another cooling method, the spun yarn is cooled in a water tank containing water for cooling, and the fineness of the spun yarn can be controlled. Thereafter, the fiber is wound by a winding machine, and a core/sheath type undrawn yarn can be obtained. The winding speed is not particularly limited, but is preferably in the range of 50 to 300 m/min.

(2) Drawing step

The obtained undrawn yarn is drawn with a drawing machine in order to increase the tensile strength of the fiber. The stretching conditions are not particularly limited, and the stretching magnification is 2.5 to 5.0 times, the stretching speed is 10 to 500m/min, and the temperature is 25 to 150 ℃, so that the artificial hair fiber with the target core/sheath structure can be obtained. The drawing method is not particularly limited, and any of a 2-step method of winding an undrawn yarn around a bobbin and drawing the yarn in a step other than the melt spinning step, and a direct spinning and drawing method of continuously drawing the yarn from the melt spinning step without winding the yarn around a bobbin. The stretching treatment may be performed by a 1-stage stretching method in which the stretching is performed at once to a target stretching ratio, or a multistage stretching method in which the stretching is performed 2 or more times to obtain a target stretching ratio. In the case of the hot stretching treatment, a heating roller, a hot plate, a steam jet device, a warm water tank, or the like may be used as heating means, and may be used in combination as appropriate.

(3) Heat treatment Process

The fiber subjected to the stretching treatment generates a residual force upon stretching, and it is preferable to remove the residual force caused by the heat treatment while ensuring the quality of the artificial hair as a final product. In some cases, the drawn yarn heat treatment may be performed simultaneously with the above heat treatment by about 1 to 30%.

The temperature condition for this heat treatment is preferably carried out in an atmosphere at an atmospheric temperature of 150 to 250 ℃. Although the atmosphere gas used for the heat treatment is not particularly limited, an inert gas other than the atmosphere may be used. The inert gas may be nitrogen, argon, or the like, but in view of cost, it is preferable to use the atmosphere.

In this step, the undrawn yarn is thermally drawn and heat-treated, and the fineness is preferably 10 to 100 dtex. The lower limit value of the fineness of the artificial hair fiber having the core/sheath structure is more preferably 20dtex or more, and still more preferably 35dtex or more. The upper limit value of the fineness of the artificial hair fiber having the core/sheath structure is more preferably 90dtex or less, and still more preferably 80dtex or less.

In the method for producing artificial hair fibers according to the present technology described above, conventionally known techniques related to melt spinning, for example, techniques related to various nozzle cross-sectional shapes, techniques related to cooling, techniques related to stretching treatment, techniques related to heat treatment, and the like can be freely combined and used as necessary.

The artificial hair fiber produced can be coated with a treatment agent containing an oil agent such as silica gel, thereby improving the touch feeling and the like. The coating treatment agent may be used at any stage before, during, or after the artificial hair fiber is processed into a hair product, but the coating during the processing into a hair product is more suitable in view of workability, coating uniformity, and the like.

3. Hair ornament

The artificial hair fiber can be used alone in hair products (head ornament products), or can be used in combination with human hair or other artificial hair. The hair products include wigs, hair pieces, leaves, extension hair, doll hair, etc., and the use of the artificial hair fiber is not particularly limited. Moreover, it can be used for artificial beard, eyelash, eyebrow, etc. other than hair products.

[ examples ] A method for producing a compound

Next, examples of the artificial hair fiber of the present invention will be described in detail by comparing the table with comparative examples. The embodiment of the present invention will be described more specifically based on examples, but the present invention is not limited thereto.

< example 1 >

1. Drying of materials

The pellets of the core resin composition shown in table 1 were subjected to dehumidification and drying at 120 ℃ for 12 hours from a constant temperature state using a hopper dryer (CHALLENGER III, manufactured by yoda corporation) so that the moisture content thereof was 100ppm or less (100mg/kg or less). The pellets of the sheath resin compositions shown in Table 1 were dried by dehumidification at 80 ℃ for 12 hours in the same manner so that the moisture content thereof was 1000ppm or less (1000mg/kg or less).

2. Spinning step

Two melt spinning extruders having a diameter of 20mm (GM Engineering, Full Flight Screen (compression ratio: 2.3)) were used in combination. The mold used a core/sheath type composite nozzle (number of holes 36, hole diameter 1 mm). As the setting conditions of the extruders constituting the core portion and the sheath portion, the cylinder temperature of the extruder constituting the core portion was set to 295 ℃, and the cylinder temperature of the extruder constituting the sheath portion was set to 315 ℃. After the nozzle temperature was adjusted to 300 ℃ and the steady state was reached, the screw rotation speed and gear pump rotation speed of the two extruders were determined so that the discharge amount became 30g/min and the core/sheath structure ratio became 50/50. The strands were melt-spun in a vertical direction from a die head, and the undrawn yarn was wound at a predetermined speed by a drawing machine disposed at a position 2m directly below the nozzle. At this time, the temperature and air volume of the cooling tower and the drawing speed of the drawing machine were adjusted so that the fineness of the undrawn yarn was about 210 d.

3. Drawing step

The stretching is carried out by a hot water stretching 1-stage stretching method, and the stretching is carried out by 3.5 times under the condition that the temperature of a warm water tank is 90 ℃.

4. Heat treatment Process

The drawn yarn having a core/sheath structure was heat-treated at 190 ℃ for 5 minutes using a hot air annealing bath to obtain an artificial hair fiber having a fineness of 60 d.

< examples 2 to 19, comparative examples 1 to 4 >

Examples 2 to 19 and comparative examples 1 to 4 were prepared in the same manner as in the above examples, using the formulations shown in tables 1 to 3.

The processability and the obtained artificial hair fiber were evaluated for the releasability, the touch and the curling property according to the evaluation methods and criteria described later.

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

The following are the materials used in tables 1 to 3.

< polyester >

PET 1: polyethylene terephthalate (melt viscosity 65 Pa. s, manufactured by this Co., Ltd.)

PET 2: polyethylene terephthalate (available from Mitsui chemical Co., Ltd., J125S, melt viscosity 145 Pa. s)

PET 3: polyethylene terephthalate (melt viscosity 204 Pa. s, manufactured by this Co., Ltd.)

PET 4: polyethylene terephthalate (available from Mitsui chemical Co., Ltd., J055, melt viscosity 450 Pa. s)

PET 5: polybutylene terephthalate (S600F 20, melt viscosity 118 Pa. S, manufactured by DuPont)

PET 6: polytrimethylene terephthalate (SoronaEP 3301NC010, melt viscosity 132 Pa. s, manufactured by DuPont)

< Polyamide >

PA 1: polyamide 66 (AMILAN CM3001-N, melt viscosity 66 Pa. s, manufactured by Toray corporation)

PA 2: polyamide 66 (Zytel 101, 140 Pa. s, manufactured by DuPont)

PA 3: polyamide 66 (Zytel 42A, 249 Pa. s, manufactured by DuPont)

PA 4: polyamide 6 (56 Pa. s, test product of the same Co., Ltd.)

< flame retardant >

Flame retardant 1: benzyl Bromide acrylate flame retardant (FR-1025, manufactured by ICL JAPAN)

Flame retardant 2: brominated epoxy flame retardant (edition drug manufacturing, SR-T20000)

< compatibilizer >

Maleic anhydride-modified Polymer (Fusabond, A560, DuPont Co., Ltd.)

The following are the evaluation methods and criteria for each evaluation item.

< Peel resistance >

For the evaluation of the peeling resistance, a fiber bundle sample prepared by bundling artificial hair fibers into a bundle having a length of 200mm and a mass of 1.0g was used. When the tip of the fiber bundle sample was heated with a hair pin for 10 seconds, the protrusion of the core polyester due to the difference in thermal shrinkage between the core polyester and the sheath polyamide was observed. The temperature of the hair pin generated by the thermal exfoliation was determined, and the following was used as an evaluation criterion.

Very good: the hair pin generates heat stripping under the condition of 220 ℃.

O: the hair clip did not produce thermal peeling at 200 ℃ but produced thermal peeling at 220 ℃.

X: the hair pin generates thermal stripping under the condition of 200 ℃.

< touch feeling >

For evaluation of touch feeling, a tow sample prepared by binding artificial hair fibers to a length of 250mm and a mass of 20g was used. The evaluation criteria were as follows, as judged by 10 hands of an artificial hair fiber treatment technician (experience of practice for 5 years or more).

Very good: the evaluation of 9 or more technicians was that the feeling was good

O: the evaluation of 7 or 8 technicians was that the feeling was good

X: the feeling was good as evaluated by 6 or less technicians

Crimpability

Crimpability was evaluated by using a sample of a bundle of artificial hair fibers bundled to a length of 500mm and a mass of 2.0 g. Wound around a 20mm phi aluminum cylinder with both ends fixed, and heated in a steam oven at 100 deg.C for 30 minutes. Next, the aluminum cylinder (in a state of being wound with the fiber) was placed in a thermostatic chamber at a temperature of 23 ℃ and a relative humidity of 50% for 24 hours. Thereafter, the fiber bundle was detached from the aluminum cylinder, and one end was fixed to be suspended. The length from its root to tip was divided by the full length before crimping (50 cm). The smaller the value, the larger the degree of curling, and the following is an evaluation criterion.

Very good: a value of less than 0.75

O: the value is more than 0.75 and less than 0.85

X: a value of 0.85 or more

< comparative example 1 >

In comparative example 1, the core/sheath mass ratio was too small, and the curl retention was poor.

< comparative example 2 >

In comparative example 2, the core/sheath mass ratio was too large, and the feel was poor.

< comparative examples 3 and 4 >

In comparative example 3, the viscosity ratio a/b was too large, and the peeling resistance was poor. In comparative example 4, the viscosity ratio a/b was too small, and the peeling resistance was poor.

The following is known in the examples. When the core/sheath mass ratio is 40/60 to 90/10 and the viscosity ratio a/b is 0.5 to 2.5, an artificial hair fiber having a good touch similar to human hair and excellent curl retention properties can be obtained. Further, by using a bromine-based flame retardant in combination, the bromine-based flame retardant is dispersed at the interface between the polyester in the core portion and the polyamide in the sheath portion, whereby the peeling resistance is improved and flame retardancy can be imparted. Further, by adding a compatibilizer to the polyester in the core part and the polyamide in the sheath part, the peeling resistance can be improved, and ironing and winding can be performed at a higher temperature. As for the polyester of the core, a resin obtained by blending polyethylene terephthalate and polybutylene terephthalate or polytrimethylene terephthalate has a touch closer to human hair.

[ industrial applicability ]

By using the artificial hair fiber having the core/sheath structure of the present invention, a hair product (a hair accessory product) having a good touch similar to human hair and excellent curl retention can be obtained. Thus, products such as wigs, hair pieces, leaves, extended hair, doll hair, and the like can be obtained.