JP5379076B2 - Composite synthetic fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain synthetic fiber which has both anti-transparency and cool feeling. <P>SOLUTION: A synthetic fiber comprises a thermoplastic resin which comprises at least 2 to 10 mass% of white pigment A having an average particle diameter of 0.2 &mu;m or more to less than 0.8 &mu;m and 2 to 10 ppm of black pigment, and the synthetic fiber is characterized in that it contains 3 mass% or more of white pigment B having an average particle diameter of 0.8 &mu;m to 1.8 &mu;m. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

The present invention relates to a composite synthetic fiber made of a thermoplastic resin.

  Conventionally, synthetic fibers such as polyester fibers have been widely used for inner use and outer use such as sportswear, uniforms, blouses, swimwear and underwear.

  In recent years, light-colored fabrics such as white, light pink, beige, blue, yellow, and green are visible through the inner line when worn on the outer side, Since there is a problem that the state can be seen through, there is a demand for a material that is excellent in preventing see-through.

  In addition, when used for outer applications and the like, a temperature rise in clothes is unavoidable especially in summer when the temperature is high, and therefore, there is a demand for a fiber with a refreshing feeling that reduces the temperature rise in clothes.

  Patent Document 1 contains 1.0 to 5.0 wt% of a matting agent in a synthetic polymer that forms a core component, a fluorescent whitening agent in a synthetic polymer that forms a sheath component, and a core component part. It is described that a fabric having good anti-slipping property and light fastness can be obtained by using a fabric composed of a core-sheath composite yarn having a rotationally symmetrical cross section.

  Patent Document 2 is composed of an opaque white polymer layer containing 5 to 30% by weight of a white pigment and a transparent polymer layer containing 0 to 2% by mass of the white pigment, and the transparent polymer layer is divided into three or more layers by the opaque white polymer layer. In addition, it is described that when the transparent polymer layer is a composite fiber having a fiber cross section that occupies 50% or more of the fiber surface, opacity, color developability, and heat shielding properties can be obtained.

JP-A-8-60485 JP-A-5-247723

  However, although the thing of patent document 1 is not sufficient, although a certain see-through prevention property is recognized, it does not describe at all about a refreshing feeling, and sufficient cooling feeling cannot be obtained. Moreover, although the thing of patent document 2 can obtain fixed heat-shielding property, it cannot obtain sufficient cool feeling and see-through prevention.

  Accordingly, an object of the present invention is to obtain a synthetic fiber that is excellent in anti-slipping property and coolness.

  In order to solve the above-mentioned problem, the present inventors do not prevent the transmitted light by using only the reflection / scattering phenomenon of the transmitted light by the white pigment, but transmit the transmitted light and the reflected / scattered light from the white pigment to the white pigment. Adding a small amount of carbon black to be absorbed improves the anti-slipping performance significantly, and by incorporating a white pigment with a particle size that reflects a large amount of infrared rays that greatly contributes to thermal energy, coolness is improved. Focusing on the improvement, the present invention has been reached.

That is, the present invention is a core-sheath type composite synthetic fiber in which a core part and a sheath part are composited, and one of the core part and the sheath part is 3% by mass of white pigment B having an average particle diameter of 0.8 to 1.8 μm. A core-sheath type composite synthesis comprising a thermoplastic resin comprising the thermoplastic resin comprising the above, and the other comprising 2 to 10% by weight of white pigment A having an average particle diameter of 0.2 μm or more and less than 0.8 μm and 2 to 10 ppm of black pigment. The gist is that it is a fiber . Also, 2 thermoplastic pigments containing 3% by mass or more of white pigment B having an average particle diameter of 0.8 to 1.8 μm in the core and 2 white pigment A having a sheath part having an average particle diameter of 0.2 μm or more and less than 0.8 μm. The gist is that it is a core-sheath type composite synthetic fiber made of a thermoplastic resin containing 10 to 10% by mass and 2 to 10 ppm of a black pigment .

  In the fiber cross section, the joining ratio of the core part and the sheath part is preferably 4: 1 to 2: 3 (area ratio), and the ratio of the core part exposed to the fiber surface is more preferably 50% or less. .

Also it is preferable that the black pigment of the present invention is carbon black, it is preferable to fluorescent whitening agent is 0.01 to 0.05 wt% Dressings containing. Further, it is preferable to fluorescent whitening agent in the sheath portion is 0.01 to 0.05 wt% Dressings containing.

  The present invention can provide a synthetic fiber having sufficient anti-slipping properties and coolness. In particular, it can be suitably used for light-colored fabrics including white.

FIG. 1 shows an example of the cross-sectional shape of the synthetic fiber of the present invention.

  The present invention will be described in detail below.

The present invention is a composite synthetic fiber made of a thermoplastic resin.

  The thermoplastic resin (polymer) of the present invention means all polymers having fiber-forming ability that can be synthesized by a polymerization reaction. Specifically, nylon 6, nylon 66, nylon 12, polyamides such as poly-p-phenylene terephthalamide, poly-m-phenylene isophthalamide, polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polylactic acid, Examples thereof include polyolefins such as polyethylene and polypropylene, and polyacryls such as polyacrylonitrile. Of course, it is not limited to these, and other types of polymers can be used. Each polymer is not limited to a homopolymer, and may be a blend, a copolymer, or the like.

  Among these polymers, nylon 6, polyethylene terephthalate, and polytrimethylene terephthalate are most widely used. In the present invention, these polymers can be preferably used.

  Moreover, since this invention reflects the infrared rays of sunlight so that it may mention later, when a suitable use application is considered, polyester is preferable and a polyethylene terephthalate is preferable from the point of a price and versatility.

  The synthetic fiber of the present invention includes at least two types of white pigment A, white pigment B, and black pigment having different average particle diameters.

  The average particle diameter of the present invention can be determined by taking a photograph using a transmission electron microscope and measuring the volume-based horizontal equivalent diameter using an automatic image processing analyzer.

  The white pigment A has an average particle size of 0.2 μm or more and less than 0.8 μm.

  It is preferable that the particle diameters of the individual particles of the white pigment A are continuously connected and distributed, and if the particle diameter distribution is close to a normal distribution having a certain width, visible light can be reflected efficiently. Therefore, it is preferable.

  The white pigment A is not particularly limited, and examples thereof include titanium oxide, zinc oxide, magnesium oxide, barium sulfate, and silica. Of these, titanium oxide is preferably used.

  The white pigment B has an average particle size larger than that of the white pigment A, and the average particle size is 0.8 to 1.8 μm.

  Considering that the particle size distribution of the white pigment B is 0.8 to 3 μm and 2.2 μm in the infrared region having a wavelength of 3 μm or less, and that the visible light wavelength region is 0.4 μm in width. It is preferable to have a wide distribution.

  The standard deviation of the average particle diameter of the white pigment B is preferably about 0.2 or more. The standard deviation of the average particle size of the white pigment B is preferably 2 or more.

  Although it does not specifically limit as said white pigment B, Alumina, zinc oxide, a silica etc. can be mentioned. Of these, titanium oxide is preferable, and in particular, rutile type titanium oxide is preferable.

  Specific examples of the black pigment include carbon black pigments, aniline black pigments, and iron oxide black pigments. In view of versatility and cost, carbon black (CB) is most preferable.

  An example of the cross-sectional shape of the synthetic fiber of the present invention is shown in FIG.

  1A shows a cross section of a single yarn, and FIGS. 1B to 1D show cross sections of a composite yarn. 1 is a core part and 2 is a sheath part.

  In addition, in FIG. 1, although the round cross section was illustrated as an external shape of a cross-sectional shape, shapes, such as a polygon and a flat shape, can also be changed.

  The synthetic fiber of the present invention is preferably a core-sheath type composite synthetic fiber (hereinafter, the composite synthetic fiber may be referred to as a composite fiber).

  The preferred embodiments of the core-sheath type composite synthetic fiber will be described in more detail below.

  Preferred examples of the core-sheath type composite synthetic fiber of the present invention include those made of a thermoplastic resin composed of white pigment B in the core part and a thermoplastic resin containing white pigment A and black pigment in the sheath part.

  The thermoplastic resin for the core and sheath may be the same polymer or different polymers. However, in the case of the same polymer combination, the core part and the sheath part are less likely to peel off, and defective products such as thread breakage are less likely to occur. Therefore, the core part and the sheath part are preferably made of the same polymer.

  The core part will be described below.

  It is preferable that the said core part consists of a thermoplastic resin containing the white pigment B (average particle diameter of 0.8-1.8 micrometers). The white pigment B is preferably contained in an amount of 3% by mass or more.

  The average particle diameter is more preferably 0.8 to 1.5 μm, and even more preferably 0.9 to 1.2 μm.

  Further, the content of the white pigment B is preferably 3% by mass or more, and more preferably 6% by mass or more. The upper limit is preferably about 20% by mass in consideration of spinning operability and fiber quality.

  The white pigment B is not particularly limited, but titanium oxide is preferably used. The titanium oxide contained in the core preferably has a rutile crystal structure.

Usually, a white pigment (titanium oxide) used as a matting agent in a synthetic fiber has an average particle size of about 0.3 μm, but the average particle size of the white pigment B used in the present invention is 0.8 μm to 1. by increasing the 8 [mu] m, for reflecting easily converted into thermal energy infrared rays (wavelength 0.8～3Myuemu), it can exhibit a heat shielding effect, have good coolness can be obtained. Most preferably, it is 0.8-1.5 micrometers.

  If the average particle diameter of the titanium oxide is too large, it reflects a long wavelength rather than a wavelength of 3 μm or less, which is an infrared wavelength that is easily converted into thermal energy, and a sufficient heat shielding effect cannot be obtained. If the average particle diameter of titanium oxide is too small, infrared rays of 3 μm or less that are easily converted into thermal energy will not be reflected, and visible light having a shorter wavelength will be reflected, and the heat shielding effect will not be sufficient. It is preferable to do. Within this range, a heat shielding effect can be efficiently obtained, a cool feeling can be obtained, and a refreshing feeling can be easily obtained.

  In addition, the distribution of the particle size of the white pigment B is wide when considering that the infrared region having a wavelength of 3 μm or less is 0.8 μm to 3 μm and 2.2 μm, and the width of the visible light wavelength region is 0.4 μm. It is preferable to have

  The standard deviation of the average particle diameter of the white pigment B is preferably about 0.2 or more.

  The sheath is described below.

  It is preferable that the said sheath part consists of a thermoplastic resin containing the white pigment A (average particle diameter of 0.2 micrometer or more and less than 0.8 micrometer).

  The white pigment A in the sheath is preferably contained in an amount of 2 to 10% by mass from the viewpoint of preventing see-through and handling of fibers. Preferably, it is 3-10 mass%, More preferably, it is 3-8 mass%. That is, when there is too little content of the white pigment A, there exists a possibility that anti-slipping performance may not be enough. If the content is too large, the unevenness of the fiber surface tends to be prominent, and the spinnability and the wear of parts such as spinning and processing machines in subsequent processes may be accelerated. Within this range, it is easy to obtain a fiber that is flexible and has a good feel while having anti-slipping properties.

In consideration of the balance between see-through prevention, spinning operability and post-processability, the average particle size of the white pigment A used is preferably 0.2 μm or more and less than 0.8 μm, and more preferably 0.2 μm to 0.5 μm.
Examples of the white pigment A include titanium oxide, zinc oxide, magnesium oxide, barium sulfate, and silica. Of these, titanium oxide is preferably used.
Some titanium oxides have anatase and rutile crystal systems, and among them, anatase has lower hardness and can be suitably used for the sheath from the viewpoint of wear of spinning machines, processing machines and the like.

  As a method for adding the white pigment to the thermoplastic resin, a method of adding at any stage of producing the fiber can be mentioned. The addition method is not particularly limited, but may be a method of adding during polymerization or a method of kneading after polymerization. The method most often used is a method of spinning a master chip to which a white pigment is added at a high concentration in advance and a normal chip. Even a normal chip contains a small amount of white pigment.

  It is preferable that the thermoplastic resin of the said sheath part contains 2-10 ppm of black pigments from the point suitable for a see-through prevention property or a white or light-colored-type fabric.

  By including a black pigment, the fiber see-through preventing effect is significantly improved. By making the amount of the black pigment 2 ppm or more, the see-through preventing effect is improved. If the amount of the black pigment is 10 ppm or less, the blackness (darkness) of the yarn is not noticeable, and it is suitable for applications where a bright yarn such as white or light color is required. Considering the balance between the thread shedding prevention effect and the whiteness, the content of the black pigment is more preferably 2 to 6 ppm.

  Although there is no restriction | limiting in particular in the method of containing a black pigment in a thermoplastic resin, The method of mixing a master chip | tip which added the black pigment in high concentration previously and a normal chip | tip and spinning this is often used. There is also a method in which chips and black pigment are mixed and used for spinning.

  It is preferable that the thermoplastic resin of the said sheath part contains a fluorescent whitening agent. This is because a fiber containing a fluorescent brightening agent is superior in light resistance and fastness to dyeing than whitening by post-dying.

  The fluorescent whitening agent means an original fluorescent whitening agent added to the synthetic polymer at the time of fiber production, and is preferably one that does not hinder spinnability and stretchability. Examples thereof include sulpenic fluorescent brighteners, imidazole fluorescent brighteners, imidazolone fluorescent brighteners, triazole fluorescent brighteners, thiazole fluorescent brighteners, and oxazole fluorescent brighteners.

  The content of the fluorescent brightening agent is arbitrary, but in order to obtain a white effect, it is preferable to contain at least 0.01% by mass. On the other hand, if the fluorescent whitening agent is present in a large amount, self-quenching occurs and the whitening effect is diminished, so 0.05% by mass is sufficient.

  There is no particular limitation on the method of containing the optical brightener. Often used is a method of mixing a master chip to which a fluorescent whitening agent has been added at a high concentration in advance and a normal chip, and spinning them. There is also a method in which a chip and a fluorescent brightening agent are mixed and used for spinning.

  The fiber cross section of the core-sheath type composite synthetic fiber will be described below.

  In the fiber cross section of the above-described core-sheath type composite synthetic fiber, the bonding ratio between the core part and the sheath part is preferably an area ratio of 4: 1 to 2: 3, more preferably 4: 1 to 1: 1. It is. That is, when the ratio of the core part is too large, the ratio of the sheath part is too small and the effect of preventing see-through is reduced. If the ratio of the sheath portion is too large, the portion containing titanium oxide having a large average particle diameter decreases, the portion that does not reflect the infrared wavelength of 3 μm or less, which tends to become thermal energy, increases, and the heat shielding effect is small. Therefore, the above range is preferable in terms of prevention of see-through and coolness. Within this range, the spinning operability and the handleability of the fibers in the subsequent process are good, and the fibers are easy to touch.

As a suitable example of the cross section of the said core-sheath-type composite synthetic fiber, (b)-(d) of FIG. 1 can be illustrated. As shown in FIG. 1B, the core is not exposed on the fiber surface in the cross section of the fiber from the viewpoint of easily exhibiting the effects of the present invention such as see-through prevention and coolness while maintaining the handleability and yarn quality of the fiber. those are particularly preferred of.

  In addition, the surface exposure degree of the core part of the core-sheath type composite synthetic fiber of the present invention is preferably within 50%, more preferably within 30%, and further preferably a shape in which the core part is completely exposed without being exposed to the sheath part. It is. When the surface exposure of the thermoplastic resin containing the white pigment B is small, it is easy to obtain good spinning maneuverability, fiber handling properties in the subsequent process, etc., and it is easy to obtain a good touch when used as a fabric. .

  As the preferred core-sheath composite synthetic fiber of the present invention, the thermoplastic resin containing the white pigment B in the core part and the thermoplastic resin containing the white pigment A and the black pigment in the sheath part have been exemplified and described. It can also be set as the composite synthetic fiber which replaced the thermoplastic resin of the part and compounded.

  That is, by making a composite synthetic fiber (b) whose core part is made of a thermoplastic resin (a) containing a white pigment A and a black pigment and whose sheath part is made of a thermoplastic resin containing a white pigment B, it is also possible to prevent see-through / Cool feeling can be obtained.

  From the viewpoint of see-through prevention and coolness, a composite fiber in which a thermoplastic resin (a) containing a white pigment A and a black pigment and a thermoplastic resin (b) containing a white pigment B are combined may be used.

  In addition, synthetic fibers such as single fibers made of a thermoplastic resin containing the white pigment A and the black pigment in the sheath, or composite synthetic fibers in which the thermoplastic resin in the sheath is combined with other components, the entire synthetic fiber Even if it contains 3% by mass or more of white pigment B, it is possible to obtain transparency prevention and heat shielding properties.

  The synthetic fiber of the present invention is composed of at least a white pigment A and a thermoplastic resin containing a black pigment. However, the synthetic fiber may contain white pigment B. In the case of a single fiber composed entirely of this thermoplastic resin, white pigment B, white pigment A and black pigment are contained by adding to the same thermoplastic resin. Easy to get effect.

From the viewpoint of see-through prevention, the thermoplastic resin containing the white pigment A and the black pigment is preferably 25% or more of the fiber cross section with respect to the synthetic fiber.
From the viewpoint of coolness, the white pigment B having a large particle size is preferably contained in the synthetic fiber in an amount of 3% by mass or more.

From the viewpoint of handling property, Itoshitsu-tactile fiber, white pigments B, the surface exposure value of the fiber cross section is preferably 70% or less, more preferably 50% or less, there is no exposed to the fiber surface It is more preferable.

In addition, there is no restriction | limiting in particular in the spinning method for obtaining the synthetic fiber of this invention, The spinning method of a well-known single fiber and composite synthetic fiber can be utilized. The fiber may be in the form of either a filament or a staple, and can be produced according to the application.
Moreover, it is arbitrary to add various additives to the synthetic fiber of the present invention for the purpose of improving fiber properties and functionalization. Examples of such additives include antistatic agents, light-proofing agents, and flame retardants. Further, ordinary polymers are slightly colored due to the presence of a metal component which is a polymerization catalyst. A small amount of dye / pigment may be added in order to reduce the coloration caused by such a catalyst. In the case of a core-sheath composite synthetic fiber, these addition amounts may be added to either the core component (core part) or the sheath component (sheath part), or may be added to both components.
The synthetic fiber of this invention may be used independently and may be used as one component of a mixed fiber. For example, it can be used as an outer thread of a covering thread.
Moreover, when making into a fabric, you may mix and use with another fiber. Specifically, there are methods such as knitting and weaving. When mixed with other fibers, it is preferable to take into account that the use of other fibers offsets the see-through prevention performance and the cool feeling performance of the present invention.

  In addition, the synthetic fiber of the present invention can be false twisted to further improve the anti-slipping property and the cool feeling.

The fiber of the present invention exhibits sufficient color developability when subjected to normal dyeing. Dyeing may be appropriately selected according to the type of polymer used for the raw material. For example, in the case of a polyester resin, it is carried out at high temperature and high pressure using a disperse dye. Such dyed fabric also has sufficient see-through prevention and coolness.

  Further, the fibers of the present invention can be used as they are as “white fibers (fabrics)” without being dyed, and even if light-colored dyeing is performed, they can exhibit sufficient anti-slipping properties and heat shielding properties.

  Since the fabric made of the synthetic fiber of the present invention has excellent anti-transparency and heat-shielding properties and has a cool feeling, it can be used for sports applications such as swimwear and leotards, outer uses, inner uses, etc. It can be used suitably. In addition, since it has excellent color development, it can be used for design with design.

Hereinafter, although an example is given and the present invention is explained, the present invention is not limited to this example.
Measurement and evaluation of each physical property was as follows.
(Whiteness, see-through prevention)
(Dry evaluation)
The fiber was uniformly wound around a white board (L value 91.5) and a blackboard (L value 4.6), and the L value was measured. When the L value of the sample wound on the white board is Lw, the L value of the sample wound on the blackboard is Lb, and the difference between them is ΔL, the smaller the ΔL is, the better the anti-slipping property is. .

  If Lw is 90 or more, it is very good as a white fiber, and if it is 85 or more, it is good. If ΔL is 9 or less, the fabric is excellent in preventing see-through when made into a fabric.

[Wet evaluation]
Evaluation was performed in the same manner as in the dry evaluation except that a sample wrapped around a white plate and a sample wound around a blackboard was dipped with 1 ml of water droplets.
(Cool feeling)
A normal semi-dal polyester yarn 56dtex / 24f was used for the warp yarn, and a two-drawn yarn obtained by aligning the two polyester yarns obtained for the weft yarn was woven in a plain weave to obtain a sample (product of the present invention). : 110 pieces / 2.54 cm, latitude density: 77 pieces / 2.54 cm). A control product was obtained by weaving in the same manner except that two normal semi-dal polyester yarns 56 dtex / 24f were used as weft yarns. Next, hold the sample on about 5 mm of black drawing paper at a test room temperature of 20 ° C., and irradiate the lamp light (Iwasaki Electric Eye Lamp PRS100V500W) at a distance of 50 cm from the sample side to the temperature at the center of the back side Was measured with a thermocouple, and the temperature difference after 30 minutes was determined.
(Average particle size)
A photograph was taken using a transmission electron microscope (transmission electron microscope JEM-1230 manufactured by JEOL Ltd.), and the volume-based horizontal equal diameter was measured with an automatic image processing analyzer (Nikore LUZEX AP). .
(Spinning operability)
In the fiber manufacturing process, the occurrence of yarn breakage during production, the ratio of defective products such as single yarn breakage and fluffing, and other troubles were observed. In order from the best result, “◯”, “Δ”, and “X” were assigned. Example 1
Polyethylene terephthalate (hereinafter sometimes referred to as PET) resin containing 2% by mass of titanium oxide having an average particle size of 0.3 μm (anatase type), 2 ppm of carbon black (CB), and 0.05% by mass of a fluorescent brightening agent Was used as the raw material M1 of the sheath component (sheath portion) of the composite fiber.

  Titanium oxide with an average particle size of 1.0 μm (rutile type, particle size distributed in a substantially normal distribution in the range of 0.5 to 2.0 μm, standard deviation of particle size distribution 0.34, σ = 3.1 ) Was used as the raw material M2 of the core component (core part) of the composite fiber.

  Each of the above-mentioned resins is melted at 295 ° C. with an extruder, combined from a core-sheath type composite die in such a combination that M1 becomes a sheath portion and M2 becomes a core portion, and is discharged from the discharge hole of the die, 1500 m An undrawn yarn with a winding of 24 f was obtained at / min.

The obtained undrawn yarn was drawn by applying heat at 85 ° C. to obtain an 84 dtex / 24 f core-sheath type composite fiber. The composite ratio of the core part and the sheath part was 2: 1 (area ratio).

  The obtained fibers were evaluated in terms of dryness, whiteness, see-through prevention, coolness, and spinning operability as shown in Table 1.

(Examples 2 to 12)
Except that the contents of titanium oxide having an average particle diameter of 1.0 μm, titanium oxide having an average particle diameter of 0.3 μm, and CB are as shown in Examples 2 to 12 of Table 1, A mold composite fiber was obtained. As in Example 1, the dryness evaluation of whiteness / translucency, coolness and spinning operability were evaluated and are shown in Table 1.

(Comparative Example 1)
The resin of the sheath part was obtained with a composition containing no carbon black with respect to Example 1, and a core-sheath type composite fiber was evaluated in the same manner as in Example 1 and evaluated in the same manner as in Example 1 and shown in Table 1.

(Comparative Examples 2-7)
Except that the contents of titanium oxide having an average particle diameter of 1.0 μm, titanium oxide having an average particle diameter of 0.3 μm, and CB were as shown in Comparative Examples 2 to 7 in Table 1, the same as in Example 1 was carried out. Thus, a core-sheath type composite fiber was obtained. Evaluation was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Examples 1 to 12 were all excellent in see-through prevention and coolness. Since the whiteness is also high, it is easy to obtain a fabric that is excellent in anti-slipping property and has a refreshing feeling even if it is a white or light-colored fabric. The spinning operability was also good and the post-processability was also good. Further, the obtained yarn had no particles on the surface and was excellent in touch.
Comparative Examples 1 and 2 that did not contain CB were inferior in see-through preventing property as compared to the Example product. Comparative Examples 2, 3 and 5 which do not contain white pigment B were inferior in coolness to the products of the examples. In Comparative Example 4 having a large amount of CB, whiteness was inferior to that of the Example product. The comparative example 6 with few white pigments B in the sheath part was inferior in coolness compared with the example product. Comparative Example 7 with little white pigment A in the core part was inferior in whiteness as compared with the Example product.

(Example 13)
1 ml of water droplets were dropped on the dry-evaluated sample of Example 8, and wet evaluation was performed. The results are shown in Table 2.

(Comparative Example 8)
1 ml of water droplets were dropped on the dry-evaluated sample of Comparative Example 3 and wet evaluation was performed. The results are shown in Table 2.

  From Table 2, it can be seen that Example 13 is excellent in see-through preventing property even when wet.

(Example 14 )
Except for changing the core-sheath composite ratio to 4: 1, a core-sheath composite synthetic fiber was obtained in the same manner as in Example 1, and as a result of evaluating whiteness, see-through prevention, and coolness, whiteness and see-through prevention were obtained. Both good and cool.

(Example 15 )
Except for changing the core-sheath composite ratio to 1: 1, the same results as in Example 1 were obtained. As a result of obtaining the core-sheath composite synthetic fiber and evaluating the whiteness, sheering resistance, and coolness, whiteness and sheering resistance were obtained. The coolness was good.

Even when the synthetic fiber of the present invention is used in a white or light-colored fabric, it is excellent in both see-through prevention and coolness, and therefore can be suitably developed for various uses such as inner use and outer use.

1 core 2 sheath

Claims (7)

A core-sheath composite synthetic fiber in which a core part and a sheath part are composited, and one of the core part and the sheath part includes 3% by mass or more of white pigment B having an average particle diameter of 0.8 to 1.8 μm. A core-sheath type composite synthetic fiber comprising a thermoplastic resin containing 2 to 10% by mass of white pigment A having an average particle size of 0.2 μm or more and less than 0.8 μm and 2 to 10 ppm of black pigment. A thermoplastic resin containing 3% by mass or more of white pigment B having an average particle diameter of 0.8 to 1.8 μm in the core part, and 2 to 10 white pigment A having a sheath part having an average particle diameter of 0.2 μm or more and less than 0.8 μm. A core-sheath type composite synthetic fiber made of a thermoplastic resin containing 2% by mass and 2-10 ppm of a black pigment. The core-sheath type composite synthetic fiber according to claim 1 or 2 , wherein a joining ratio of the core part to the sheath part is 4: 1 to 2: 3 (area ratio) in the fiber cross section. Core-sheath composite synthetic fibers of claims 1 to 3, any one, wherein the ratio of the core part is exposed to the fiber surface is within 50%. The core-sheath type composite synthetic fiber according to any one of claims 1 to 4 , wherein the black pigment is carbon black. Core-sheath composite synthetic fiber with a fluorescent whitening agent 0.01 to 0.05 wt% including claims 1-5 any one of claims. 0.01-0.05 mass optical brighteners% including claims 2-4 core-sheath type composite synthetic fibers of any one of claims to sheath.

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