JP2018016925A - Sea-island type composite fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite fiber formed of a polypropylene resin and a dyeable thermoplastic resin which obtains a polyolefin composite fiber that has good peeling resistance, spinning stability and heat resistance and less uneven dyeing without a special drawing method, and can be used as a long fiber.SOLUTION: A sea-island type composite fiber is formed of a sea part and two or more island parts, where a joint surface of the sea part and the island parts has a continuous sea-island structure in a fiber length direction, and satisfies the followings (a) to (d): (a) the island component is a polypropylene resin containing polypropylene as a main component; (b) the sea component is a dyeable thermoplastic resin; (c) an area ratio of the sea part in a fiber cross section is 30% or more and 70% or less; and (d) the smallest thickness in the sea part on the fiber cross section is 1 μm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sea-island type composite fiber that is excellent in dyeability and heat resistance using a polypropylene resin and a thermoplastic resin.

Polyolefin fibers are widely used in industrial applications because they are excellent in light weight and water repellency. Among them, polypropylene fibers are often used. However, since polypropylene fibers are difficult to be dyed with dyes, it is difficult to apply them to clothing applications.
In order to improve dyeability, Patent Document 1 proposes a polyester composite fiber that can be dyed with a disperse dye as a core component and a polypropylene composite fiber in which a polypropylene resin is arranged as a sheath component. It is described that by using such a structure, the fiber can be dyed in a dark color, and a polypropylene fiber having good light fastness and chlorine fastness can be obtained.
On the other hand, fibers made of a polyolefin resin and a thermoplastic resin such as a polyester resin or a polyamide resin are low in compatibility, so that they are easily peeled off at the joint surface of the resin, resulting in deterioration of yarn-making stability and dyeability, and handling. There was a problem that it was difficult.
Therefore, in Patent Document 2, a polypropylene resin is disposed as the core component, and a polyester resin is disposed as the sheath component, so that the melt flow rate (MFR) of the polypropylene resin exceeds 28 g / min and is less than 60 g / min. Therefore, it is described that a core-sheath type composite fiber that can be stably spun without yarn breakage and has good dyeability can be obtained. Further, this document describes that the core component and the sheath component are prevented from being peeled off under a mild stretching condition such as wet heat stretching in a relatively low temperature hot water bath.

JP 2008-261070 A JP 2012-193484 A

However, although the fiber described in Patent Document 1 can be dyed, core-sheath peeling is likely to occur, so that there is a problem in the yarn production stability and color spots are likely to occur. In addition, the woven or knitted fabric is usually subjected to a dry heat treatment such as a preset or final set. Fibers using polypropylene resin have a lower melting point than fibers using polyester resin or polyamide resin, and fusion occurs during dry heat treatment. For this reason, combined use with polyester fiber, nylon fiber, etc. was difficult.
Moreover, although patent document 2 describes that it is made difficult to produce core-sheath peeling of a fiber by setting it as mild extending | stretching conditions, such as performing wet heat processing at low temperature, Specifically, a nonwoven fabric and a spun yarn The use with long fibers is not described.
Therefore, the present invention is a composite fiber composed of a polypropylene resin and a dyeable thermoplastic resin, and without taking a special stretching method, the peel resistance, the yarn production stability and the heat resistance are good, and there are few dyeing spots. The object is to obtain a polyolefin composite fiber that can be used as a long fiber.

That is, the gist of the present invention consists of a sea part and two or more island parts, and has a sea-island structure in which a joint surface between the sea part and the island part is continuous in the fiber length direction, and the following (a) to (d) ) Is a sea-island type composite fiber.
(A) Polypropylene resin whose island component is polypropylene as a main component (b) Thermoplastic resin capable of dyeing sea component (c) The sea area ratio in the fiber cross section is 30% or more and 70% or less (d) Fiber crossing The minimum thickness of the sea portion on the surface is 1 μm or more. Among them, the dyeable thermoplastic resin is preferably a polyester resin or a polyamide resin. Moreover, it is preferable that the said fiber does not have melt | fusion and fusing after dry heat processing in 170 degreeC dry-heat atmosphere. Furthermore, the single yarn fineness of the fiber is preferably 1 dtex or more.

  According to the sea-island type composite fiber of the present invention, it is possible to provide a polyolefin composite fiber that can be used as a long fiber, having excellent peeling resistance, yarn-making stability, heat resistance and dyeability, without taking a special stretching method. The sea-island composite fiber of the present invention can be used in combination with thermoplastic resin fibers such as polyester fibers and polyamide fibers.

FIG. 1 shows an example of the cross-sectional shape of the sea-island composite fiber of the present invention. FIG. 2 shows an example of the cross-sectional shape of a sea-island type composite fiber outside the scope of the present invention. FIG. 3 shows an example of the cross-sectional shape of a sea-island composite fiber outside the scope of the present invention.

  In the present invention, the sea-island type composite fiber refers to a sea-island type composite fiber composed of a sea part composed of a sea component and an island part composed of an island component.

  The sea-island type composite fiber of the present invention is composed of a thermoplastic resin capable of dyeing sea components and an island component made of polypropylene resin.

  In the sea-island composite fiber of the present invention, the sea component polypropylene resin refers to a resin mainly composed of polypropylene (PP). It may be a propylene homopolymer or a copolymer containing other components as repeating units. Examples of the copolymer include a copolymer of propylene and one or more kinds of ethylene, butene-1, hexene-1, and the like.

  In the present invention, the melting point of the resin means a value indicated by the peak top of the endothermic peak when the temperature is raised to 300 ° C. at 10 ° C./min in a nitrogen atmosphere using a differential scanning calorimeter (DSC). .

  The melting point of the polypropylene is preferably 145 ° C or higher and 250 ° C or lower. When the melting point is lower than 145 ° C., sufficient heat resistance tends to be not obtained. When the melting point is higher than 250 ° C., in melt spinning, it tends to be difficult to combine the sea component with the thermoplastic resin, and it is difficult to obtain sea-island type composite fibers. That is, in the above range, when a fiber structure is formed by mixing fibers made of a thermoplastic resin such as a polyester resin or a polyamide resin, a dry heat treatment in post-processing such as a preset or final set is usually performed ( For example, it is easy to obtain one having sufficiently good heat resistance for performing a heat treatment at 120 to 190 ° C. and a dyeing treatment (for example, a wet heat treatment at 100 to 135 ° C.). A more preferable melting point of polypropylene is 160 ° C. or higher and 235 ° C. or lower.

  The melt frate (MFR) at 230 ° C. and a load of 2.16 kg of the polypropylene is preferably 9 g / 10 min or more and 30 g / 10 min or less. That is, if the MFR is 9 g / 10 min or more, there is a tendency that an agglomeration due to the fusion of the island portions does not easily occur, and therefore the sea portion and the island portion are hardly separated. As a result, the spinning stability in the spinning process and the drawing process becomes good, and there is a tendency that dyeing spots such as a whitening phenomenon do not easily occur after dyeing. Moreover, it is preferable that MFR is 30 g / 10min or less from the point which maintains the mechanical strength of a fiber favorably. Therefore, when the MFR is within the above range, the island portions hardly merge with each other, the sea portion and the island portion do not peel off, and a fiber having good mechanical strength can be easily obtained. Especially, MFR is preferably 9 g / 10 min or more, and preferably 20 g / 10 min or less. More preferably, it is 9 g / 10 min or more and 15 g / 10 min or less.

  In the sea-island composite fiber of the present invention, the sea component is not particularly limited as long as it is a dyeable thermoplastic resin. Specific examples include polyester resin, polyamide resin, and polyvinyl alcohol resin. Among these, polyester resins and polyamide resins are preferable from the viewpoints of heat resistance and mechanical properties.

The thermoplastic resin preferably has a melting point of 180 ° C. or higher and 280 ° C. or lower.
In the present invention, the island part is covered with sea components of the sea part, and has good heat resistance with no problem even in dry heat treatment in post-processing such as a normal preset or final set. When the melting point of the sea component is too low, the sea part is melted by dry heat treatment, and the texture tends to be hard. Moreover, when too high, there exists a tendency for the composite spinning with a sea component to become difficult. Therefore, the above range is preferable from the viewpoints of heat resistance, stable yarn production, and easy suppression of peeling between the sea and the island. The melting point of the thermoplastic resin is more preferably 210 ° C. or higher and 270 ° C. or lower, and further preferably 220 ° C. or higher and 265 ° C. or lower.

The sea component or the island component may be modified by adding an additive within a range not impairing the effects of the present invention. Examples of the additive include a compatibilizer, a heat stabilizer, an antioxidant, a fluorescent whitening agent, an infrared shielding agent, and an infrared absorber. Moreover, an additive may be used independently and may be used together.
Examples of the infrared absorber include antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO). In the case of antimony-doped tin oxide, the content is preferably 1% by mass or more, and more preferably 2% by mass or more with respect to polypropylene.
Examples of the infrared shielding agent include lanthanum hexaboride (LaB ₆ ), cesium tungsten oxide (CWO), large particle diameter titanium oxide (large particle diameter TiO ₂ ), and the like. In the case of titanium oxide having a large particle diameter, it is preferable to contain 5% by mass or more of titanium oxide having a weight average particle diameter of 0.8 to 1.8 μm with respect to polypropylene. More preferably, it is 8 mass% or more.

  The polyester resin may be a linear saturated polyester produced by a polycondensation reaction using a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative as raw materials. Polyethylene terephthalate (PET), polytrimethylene terephthalate, Examples include, but are not limited to, polybutylene terephthalate, polyethylene naphthalate, and polylactic acid. In particular, those mainly composed of polyethylene terephthalate are preferable, and may be a homopolyester or a copolyester. Examples of copolymer components include adipic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, diphenyldicarboxylic acid, 5-sodium sulfoisophthalic acid, diphenylsulfone dicarboxylic acid, p-oxyethoxybenzoic acid, etc. Those containing dicarboxylic acids or ester-forming derivative components thereof, or polyalkylene glycol components such as polyethylene glycol, polytetramethylene glycol, polyhexanemethylene glycol and the like are preferable. The polyalkylene glycol may contain a diol such as diethylene glycol, propylene glycol, neopentyl glycol, polyoxyalkylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, or an ester-forming derivative component thereof. These copolymerization components may be used one by one, or two or more types may be used.

  Examples of the polyamide resin include, but are not limited to, single polymers or copolymers such as polyamide 6, polyamide 10, polyamide 12, and polyamide 66.

  The cross-sectional shape of the sea-island composite fiber of the present invention will be described below.

  The sea-island type composite fiber of the present invention is a composite fiber having a sea-island structure in which one or more sea parts and two or more island parts are continuously formed in the length direction. Moreover, it is preferable that the joint surface of a sea part and an island part has a sea-island structure formed without a break in the fiber length direction.

  In the sea-island type composite fiber of the present invention, sea components are exposed on the fiber surface. That is, in the fiber cross section (fiber cross section perpendicular to the fiber length direction), the sea is exposed on the outer periphery.

FIG. 1 is a diagram showing an example of a cross-sectional shape of a fiber cross section of a sea-island type composite fiber of the present invention. In this example, 19 islands b having a round cross section are arranged in the sea part a of the fiber having a round cross section so as to be close to the center of the fiber. Further, the minimum thickness of the sea portion is 1 μm or more. Here, the minimum thickness of the sea is the shortest distance between the outer periphery of the fiber and the outer periphery of the island, and when the normal of the outer periphery of the fiber (a straight line passing through one point of the outer periphery of the fiber and perpendicular to the tangent at this point) is drawn. Indicates the distance to the outer periphery of the nearest island. For example, in the sea-island type composite fiber of FIG. 1, the normal line is drawn from the point p on the outer periphery of the fiber, and the intersection point with the outer periphery of the island part b is defined as q. In the fiber cross section, the shortest length X of the line segment p-q connecting the points p and q is the minimum thickness of the sea part.
When the minimum thickness of the sea part is less than 1 μm, the sea component and the island component are easily separated in the stretching process, the weaving and knitting process, and the dyeing process. For this reason, dyeing spots such as deterioration of yarn-making stability and whitening phenomenon are likely to occur. In addition, the islands are melted by the dry heat treatment, and the texture tends to be hard.

  In the fiber cross section of the sea-island composite fiber of the present invention, the number of island portions is preferably 40 or less. If the number of island portions is 40 or less, it becomes easy to stably obtain sea-island type composite fibers that are less likely to cause separation between the sea portion and the island portion having an appropriate strength. On the other hand, when the number of islands exceeds 40, the density of the islands in the fiber increases, and the islands are easily fused to form an agglomerate during the spinning process, causing separation between the sea and the islands. It tends to be easier. Further, the number of island portions to be arranged is more preferably 20 or less from the viewpoint of ensuring the formation of a more stable fiber cross section. By controlling the number of island portions to such a number, it becomes easier to suppress aggregation between the island portions. In addition, the number of island portions to be arranged is preferably 3 or more, more preferably 10 or more, from the viewpoint of preventing separation while increasing the joint area between the sea portion and the island portion.

  In the fiber cross section of the sea-island composite fiber of the present invention, the area ratio of the sea part to the entire fiber cross section is configured to be 30% or more. That is, in the fiber cross section, when the area ratio of the sea part is less than 30%, the thickness of the sea part between the island part and the island part becomes thin, the island parts merge, and the sea part and the island part peel off. It becomes easy. Moreover, since there is a tendency to become pale after dyeing, the area ratio is preferably 35% or more, more preferably 40% or more.

  In the fiber cross section of the sea-island type composite fiber of the present invention, the area ratio of the island part to the entire fiber cross section is preferably 70% or less. The area ratio of the islands may be appropriately set in consideration of the balance between lightness and dyeability.

  In the fiber cross section of the sea-island type composite fiber of the present invention, it is preferable that the island portion is disposed in the center portion in such a range that the island portions do not merge with each other. For example, in the fiber cross section, when the fiber radius is r, it is preferable to arrange the island portion in a range of [radius r × 0.90] or less from the fiber center point, more preferably [radius r × 0.85]. It is to arrange the island part in the following range. Thereby, it is easy to make the minimum thickness of the sea part 1 μm or more, and there is a tendency to easily suppress dyeing spots such as deterioration in yarn-making stability and whitening phenomenon.

  In the sea-island type composite fiber of the present invention, the total fineness is preferably 40 dtex or more and 200 dtex or less from the viewpoint of yarn production stability. More preferably, it is 40 dtex or more and 150 dtex or less, More preferably, it is 40 dtex or more and 100 dtex or less.

  In the sea-island composite fiber of the present invention, the single yarn fineness is preferably 1 dtex or more. If the single yarn fineness is less than 1 dtex, it tends to be difficult to maintain the minimum thickness of the sea at 1 μm or more, and dyeing spots such as deterioration in yarn-making stability and whitening phenomenon tend to occur. Moreover, the single yarn fineness is preferably 5 dtex or less from the viewpoint of the texture when it is made into a fabric. If it exceeds 5 dtex, the texture tends to be hard when it is made into a fabric. More preferably, it is 4 dtex or less, More preferably, it is 3 dtex or less.

  In the sea-island composite fiber of the present invention, the strength is preferably 2.0 cN / dtex or more and 5.5 cN / dtex or less from the viewpoint of post-processing. More preferably, it is 2.5 cN / dtex or more and 5.0 cN / dtex or less.

  In the sea-island composite fiber of the present invention, the elongation is preferably 20% or more and 45% or less from the viewpoint of post-processing. More preferably, it is 25% or more and 40% or less.

The density of the sea-island type composite fiber of the present invention will be described. Island component polypropylene has a density of about 0.91 g / cm ³ and is excellent in lightness. On the other hand, in the present invention, the sea component is made of a dyeable thermoplastic resin. Therefore, the density of the sea-island type composite fiber of the present invention changes according to the area ratio of the island part in the fiber cross section. A larger area ratio of island components made of a polypropylene resin having a lower density is better from the viewpoint of lightness, but a larger area ratio of island components made of a thermoplastic resin having a higher density than polypropylene is preferred from the viewpoint of dyeability. Considering these balances, the lower limit of the sea area ratio in the fiber cross-section is 30%, preferably 35%, more preferably 40%. The upper limit of the sea area ratio is 70%, preferably 65%, more preferably 60%. If it is such a range, it will become easy to obtain the sea-island type composite fiber excellent in both lightness and dyeability.

  In the present invention, heat resistance will be described. It is preferable that the sea-island type composite fiber of the present invention is one that does not cause melting / fusion by a dry heat treatment at 170 ° C. Usually, a woven or knitted fabric needs to be subjected to a dry heat treatment such as a preset or final set. In the case of a fabric using polyester fiber or polyamide fiber, heat treatment is usually performed at 120 ° C to 180 ° C. In this case, if fibers with low heat resistance are used together, the fibers will be fused or melted during dry heat treatment, resulting in a fabric with a hard texture or a hole, and used for clothing and industrial materials. Can not be. In this respect, the higher the heat resistance, the better, and it is preferable that no melting or fusion occurs in a dry heat treatment at 170 ° C.

  The sea-island type composite fiber of the present invention can be used in the form of staple, spun yarn, filament and the like. The sea-island type composite fiber of the present invention is less likely to cause separation between the sea part and the island part without taking a special stretching method, and can suppress the whitening phenomenon. Furthermore, since it has sufficient strength and elongation, it can be suitably used as a long fiber.

Various fiber structures can be obtained by using the sea-island composite fiber of the present invention. Examples of the fiber structure include yarn bundles such as twisted yarns and braids, processed yarns such as false twisted yarns and taslan processed yarns, spun yarns, various mixed yarns, fabrics such as woven and knitted fabrics and nonwoven fabrics, and stuffed cotton. be able to.
In particular, if the fiber structure is a fabric such as a woven or knitted fabric / nonwoven fabric woven / knitted / woven with a fiber made of a thermoplastic resin such as polyester fiber or polyamide fiber, the dyeability, heat resistance, lightness, etc. It is preferable in that the features can be utilized by being used as appropriate.

  Next, the suitable example of the method of manufacturing the sea-island type composite fiber of this invention is demonstrated.

First, the island component polypropylene resin and the sea component thermoplastic resin are prepared.
The prepared sea component and island component are separately melted, discharged from the spinneret so as to have the above-mentioned cross-sectional shape, cooled, and then stretched to obtain the sea-island composite fiber of the present invention.

  The spinning temperature is preferably 220 ° C. or higher and 300 ° C. or lower, more preferably 250 ° C. or higher and 290 ° C. or lower, from the viewpoints of heat resistance and spinnability of the polypropylene resin and the thermoplastic resin. The spinning speed is preferably 800 m / min or more and 4500 m / min or less, and more preferably 1000 m / min or more and 3800 m / min or less.

  In the sea-island type composite fiber of the present invention, it is preferable that the sea part and the island part are joined to each other without interruption in a state where the sea part and the island part are continuous in the fiber length direction. In this case, the sea part and the island part are hardly separated in the drawing process, the weaving and knitting process, the dyeing process, and the like, and it is easy to suppress the deterioration of the yarn production stability and the whitening phenomenon. On the other hand, if the resin in the island portion is interrupted in the length direction of the fiber, it is not preferable because it tends to be difficult to suppress dyeing spots such as deterioration of yarn-making stability and whitening phenomenon.

  The drawing temperature is preferably 90 ° C. or higher and 120 ° C. or lower, more preferably 95 ° C. or higher and 110 ° C. or lower, from the viewpoint of yarn production stability. The draw ratio is preferably about 2.0 times or more and 3.5 times or less from the viewpoint of stably obtaining the cross-sectional shape of the sea-island composite fiber.

  In producing the sea-island type composite fiber of the present invention, any method such as a method of drawing after melt spinning and then winding up, or a method of direct spinning and drawing after melt spinning and then drawing without winding up is used. Can be adopted.

  In this manner, the sea-island type composite fiber of the present invention can be obtained which has no peeling between the sea part and the island part and has good yarn-making stability.

  The sea-island type composite fiber of the present invention thus obtained has good yarn production stability and good heat resistance, so that each step such as drawing step, false twisting step, weaving step, refining step, dyeing step, etc. However, it is difficult to peel off and is excellent in handling in each process. In particular, since dyeing spots such as a whitening phenomenon do not occur at the time of dyeing, dyeing can be performed in a dark color.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the following examples illustrate the present invention and do not limit the present invention. Various physical properties were measured and evaluated as follows.

(1) Melting point Using a differential scanning calorimeter (DSC) (“DSC 8230” manufactured by Rigaku), the temperature is raised to 300 ° C. at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere, and the peak top of the endothermic peak is thermoplastic. The melting point of the resin.

(2) Yarn Stability The yarn making stability was evaluated based on the average number of yarn breakage when a 10 kg yarn was produced, and B or higher was determined to be acceptable according to the following criteria.
A: When thread breakage is less than 1 B: When thread breakage is 1 or more and less than 3 C: When thread breakage is 3 or more

(3) Confirmation of island state (fusion / peeling) and minimum thickness of sea part Two arbitrary parts of the obtained sea-island type composite fiber were cut perpendicular to the length direction, and the cut surface was magnified 1500 times with an electron microscope Observed and confirmed the state of fusion / detachment of the islands. Those in which these defects did not occur were evaluated as “good”. Moreover, the minimum thickness of the sea part was measured with the same cut surface.

(4) Strength and elongation of fiber According to JIS L1013, a tensile test using an autograph AGS manufactured by Shimadzu Corporation was performed, and the fiber was broken under the conditions of a measurement length: 200 mm and a tensile speed: 200 mm / min. The breaking strength and the breaking elongation were measured 5 times, and the average value was obtained.

(5) Lightness The density of the obtained sea-island type composite fiber was calculated by the density gradient tube method according to JIS K7112 D method. An immersion liquid prepared using a zinc chloride aqueous solution as a heavy liquid and ethanol as a light liquid was prepared in a density gradient tube, and allowed to stand for 24 hours at a constant temperature bath at 23 ° C. The sample was placed in a density gradient tube and allowed to stand for 1 hour, and then the floating state was confirmed. The lightness was evaluated based on the following criteria.
A: It has excellent light weight with a specific gravity of less than 1.1 g / cm ³ .
B: It has good light weight with a specific gravity of 1.1 g / cm ³ or more and less than 1.2 g / cm ³ .
C: The specific gravity is 1.2 g / cm ³ or more and does not have light weight.

(6) Evaluation of heat resistance After the tubular knitted fabric produced with the obtained sea-island type composite fiber was opened, it was fixed with a frame of 20 cm x 25 cm and subjected to dry heat treatment with hot air at 170 ° C for 1 minute. The fabric after the dry heat treatment was observed at 1000 times with an electron microscope and evaluated according to the following criteria.
○: When there is no yarn fusion or fusing and the texture is not hard ×: When there is yarn fusion or fusing and the texture is hard

(7) Evaluation of dyeability The cylindrical knitted fabric produced from the obtained sea-island type composite fiber is refined at 70 ° C. for 20 minutes, washed with water and air-dried to obtain a disperse dye (Dianix (registered trademark) Blue ACE). 0% o. w. f, bath ratio 1:50, after high-pressure dyeing at 130 ° C. for 1 hour, reduction washing was carried out by a conventional method and evaluated according to the following criteria.
○: When there is no whitening phenomenon ×: When there is whitening phenomenon

(8) Thermal storage color retention evaluation 5 mm space is provided on the back of the cylindrical knitted fabric made of the obtained sea-island type composite fiber and the reference fiber knitted fabric, black paper is placed, and the central portion of the black paper is placed. A thermocouple temperature sensor was attached, and a 500 W reflex lamp was irradiated for 10 minutes from 50 cm above the sample surface. A temperature difference from the standard fiber knitted fabric was measured and evaluated according to the following criteria.
○: When the temperature difference is + 5 ° C or more after 10 minutes of irradiation and the temperature difference is + 3 ° C or more after 1 minute of light extinction ×: The temperature difference is less than + 5 ° C after 10 minutes of irradiation, or the temperature difference is less than + 3 ° C after 1 minute of light emission in the case of

(9) Evaluation of heat shielding property A thermocouple temperature sensor is attached to the center of the cylindrical knitted fabric made of the sea-island type composite fiber and the standard fiber knitted fabric, and a 500 W reflex lamp is placed 30 cm above the sample surface. Irradiated for 1 minute. A temperature difference from the standard fiber knitted fabric was measured and evaluated according to the following criteria.
○: When the temperature difference after 30 minutes of irradiation is less than −2 ° C. ×: When the temperature difference after 30 minutes of irradiation is −2 ° C. or more

[Example 1]
Polypropylene (“SA01A (registered trademark)” manufactured by Nippon Polypro, MFR 9 g / 10 min, melting point 164 ° C.) is used as the island component, polyethylene terephthalate (melting point 258 ° C.) is used as the sea component, and the area ratio of sea part: island part is 40:60. As shown in FIG. 1, 19 island components are spun at 288 ° C. from a die arranged at the center of the fiber, drawn at a draw ratio of 2.5 times, and wound at a speed of 3000 m / min. A 66 dtex / 24 f sea-island type composite fiber was obtained. The minimum thickness of the sea part in the fiber cross section of the obtained sea-island type composite fiber was 1.1 μm, and no peeling was observed at the interface between the sea part and the island part, and the yarn-making stability was good. Even after a dry heat treatment at 170 ° C. for 1 minute, there was no fusion or fusing, and the heat resistance was excellent. As for the dyeability, no whitening phenomenon occurred and the lightness was excellent. The obtained results are shown in Table 1.

[Example 2]
A sea-island type composite fiber was produced in the same manner as in Example 1 except that the area ratio of sea part: island part was 60:40. The minimum thickness of the sea part in the fiber cross section of the obtained sea-island type composite fiber was 1.5 μm, and no peeling was observed at the interface between the sea part and the island part, and the yarn-making stability was good. Even after a dry heat treatment at 170 ° C. for 1 minute, there was no fusion or fusing, and the heat resistance was excellent. As for the dyeability, no whitening phenomenon occurred and the lightness was good. The obtained results are shown in Table 1.

Example 3
A sea-island type composite fiber was produced in the same manner as in Example 1 except that a base in which seven island components were arranged was used. In the obtained sea-island type composite fiber, the minimum thickness of the sea part was 1.2 μm, peeling at the interface between the sea part and the island part was not observed, and the spinning stability was good. Even after a dry heat treatment at 170 ° C. for 1 minute, there was no fusion or fusing, and the heat resistance was excellent. As for the dyeability, no whitening phenomenon occurred and the lightness was excellent. The obtained results are shown in Table 1.

Example 4
A sea-island composite fiber was produced in the same manner as in Example 1 except that 2% by mass of antimony-doped tin oxide (ATO) was added as an infrared absorber to polypropylene. The minimum thickness of the sea part in the obtained sea-island type composite fiber was 1.2 μm, and no peeling at the interface between the sea part and the island part was observed, so that the yarn production stability was good. Even after a dry heat treatment at 170 ° C. for 1 minute, there was no fusion or fusing, and the heat resistance was excellent. The dyeability was good with no whitening phenomenon. Moreover, the heat storage heat retention evaluation on the basis of Example 1 was also favorable. The obtained results are shown in Table 1.

Example 5
A sea-island composite fiber was produced in the same manner as in Example 1 except that 8% by mass of titanium oxide having a weight average particle size of 1.0 μm was added as an infrared shielding agent to polypropylene. The minimum thickness of the sea part in the obtained sea-island type composite fiber was 1.1 μm, and no peeling at the interface between the sea part and the island part was observed, so that the yarn production stability was good. Even after a dry heat treatment at 170 ° C. for 1 minute, there was no fusion or fusing, and the heat resistance was excellent. The dyeability was good with no whitening phenomenon. Further, the heat shielding property based on Example 1 was also good. The obtained results are shown in Table 1.

[Comparative Example 1]
A composite fiber was produced in the same manner as in Example 1 except that a base serving as a normal core-sheath thread (single core) was used. The resulting composite fiber was peeled at the interface between the core component and the sheath component. In addition, a whitening phenomenon occurred after dyeing. The obtained results are shown in Table 2.

[Comparative Example 2]
A sea-island composite fiber was produced in the same manner as in Example 1 except that a base in which 19 island components were uniformly arranged over the entire fiber as shown in FIG. 2 was used. Some islands of the obtained sea-island type composite fiber were exposed to the surface. Further, peeling was observed at the interface between the sea part and the island part, the spinning stability was poor, and a whitening phenomenon occurred after dyeing. The heat resistance was not good because fusing or fusing occurred in a dry heat treatment at 170 ° C. for 1 minute. The obtained results are shown in Table 2.

[Comparative Example 3]
A sea-island type composite fiber was produced in the same manner as in Example 1 except that a base having a petal shape as shown in FIG. 3 and an island component exposed to the fiber surface was used. Since the thermoplastic resin is exposed on the fiber surface, the yarn-making stability is poor, and composite fibers could not be obtained. The obtained results are shown in Table 2.

[Comparative Example 4]
A sea-island type composite fiber was produced in the same manner as in Example 1 except that the area ratio of sea part: island part was 25:75. The obtained sea-island type composite fiber was a core-sheath type fiber having a single core in which the island components were fused. A whitening phenomenon occurred after dyeing. The obtained results are shown in Table 2.

  The sea-island type composite fibers obtained in Examples 1 to 5 were excellent in peel resistance, dyeability and heat resistance, but the sea-island type composite fibers obtained from Comparative Examples were peel resistance, dyeability and heat resistance. At least one of the sexes was bad.

  The sea-island type composite fiber of the present invention can be made into various fiber structures and can be suitably used not only for clothing such as inner and sportswear, but also for industrial materials such as outdoor goods such as umbrellas and tents. it can.

a Sea part b Island part p Contact point on the outer periphery of the fiber q Intersection of the normal line on the outer periphery of the fiber and the outer periphery of the island part X Minimum thickness of the sea part

Claims (4)

A sea-island type composite fiber composed of a sea part and two or more island parts, having a sea-island structure in which a joint surface between the sea part and the island part is continuous in the fiber length direction and satisfying the following (a) to (d).
(A) Polypropylene resin whose island component is polypropylene as a main component (b) Thermoplastic resin capable of dyeing sea component (c) The sea area ratio in the fiber cross section is 30% or more and 70% or less (d) Fiber crossing Minimum thickness of sea part on the surface is 1μm or more The sea-island composite fiber according to claim 1, wherein the dyeable thermoplastic resin is a polyester resin or a polyamide resin. The sea-island type composite fiber according to claim 1 or 2, wherein there is no fusing and fusing after a dry heat treatment in a dry heat atmosphere at 170 ° C. The sea-island type composite fiber according to any one of claims 1 to 3, wherein the single yarn fineness is 1 dtex or more.

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