JP2019099958A - Heat adhesive composite fiber - Google Patents

Abstract

To provide a heat adhesive composite fiber, more precisely, a heat adhesive hollow composite fiber having both bulkiness and flexibility, for use in a nonwoven fabric.SOLUTION: The heat adhesive hollow composite fiber comprises: a core part being a first component containing a polyester resin; and a sheath part being a second component containing a polyolefin resin having a melting point that is 30°C lower than the melting point of the polyester resin. The first component includes one hollow part continuous in a fiber axis direction, a hollowness thereof is 12% or more and 35% or less, a center point of the hollow part is the center point of a sheath component, a hollow shape is a triangular shape, and a composite ratio of the first component to the second component is 60 mass% or more/40 mass% or less to 40 mass% or more/60 mass% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat-adhesive composite fiber. More particularly, the present invention relates to a heat-adhesive hollow composite fiber used for non-woven fabric.

  Since it is easy to obtain a non-woven fabric excellent in bulkiness and flexibility, a heat-adhesive composite fiber that can be molded by heat fusion using hot air or heat energy of a heating roll is conventionally a diaper, It is widely used for sanitary materials such as napkins and pads, or industrial materials such as household goods and filters. Hygiene materials, in particular, touch human skin directly, so their bulkiness and flexibility are extremely important. In order to obtain bulkiness, a method using a resin with high rigidity and a method using a thick fiber with fineness are typical, but in that case, the obtained non-woven fabric has reduced flexibility and physical irritation to the skin. Become stronger. On the other hand, when priority is given to flexibility in order to suppress skin irritation, the resulting nonwoven fabric is significantly reduced in bulkiness, particularly its cushioning ability to weight. Therefore, many methods have been proposed to obtain fibers and non-woven fabrics capable of achieving both bulkiness and flexibility.

Patent Document 1 proposes a thermobonded composite fiber comprising a high melting point thermoplastic resin and a low melting point resin having a melting point lower than that by 30 ° C., and having a hollow fiber cross section of 3 to 50%. .
In patent document 2, it is comprised by the core component which consists of a high melting point polymer which has a continuous hollow part, and the sheath component which consists of low melting polymers which have a 20 degreeC or more melting point lower than this core component, Proposes a heat-adhesive hollow composite fiber eccentric from the center point of the core.

  In Patent Document 3, the melting point of two polymers having a difference of 20 ° C. or more in the melting point, the high melting point polymer forms a hollow core, and the low melting point polymer forms a sheath. A heat-adhesive composite fiber is proposed in which the center point of the hollow portion is offset from the center points of the core and the sheath.

  Patent Document 4 proposes a heat-adhesive hollow composite fiber comprising a sheath of low melting point and a core of high melting point, and the hollow part is formed across the core and the sheath.

  However, in any case, the hollow section is easily crushed in the stretching nip process and the crimp application process in fiber production, and the fiber opening process in nonwoven fabric production, so that the fiber cross section is deformed and sufficient bulkiness is obtained in the obtained nonwoven fabric And there is a problem that flexibility can not be obtained.

  Moreover, although the polyester hollow fiber which made the hollow part hard to be crushed by making a hollow part into triangle shape is proposed by patent document 5, it is a fiber for clothing, It was not applicable to a nonwoven fabric.

Unexamined-Japanese-Patent No. 1-213452 Japanese Patent Application Laid-Open No. 62-299514 JP-A-2-191718 Japanese Patent Application Laid-Open No. 3-69614 JP-A-6-228815

  Therefore, an object of the present invention is to solve the problems in the prior art described above, and to provide a heat-adhesive hollow conjugate fiber which can provide a nonwoven fabric having both bulkiness and flexibility.

  The present inventors set the composite form to be an eccentric core-sheath hollow type and to make the shape of the hollow part triangular in order to obtain a heat-adhesive hollow composite fiber used for a non-woven fabric having both bulkiness and flexibility. In the conventional method, the heat is used to suppress the deformation of the hollow fiber section and the deformation of the fiber cross section due to mechanical stress or the like in the stretching nip process and crimp application process in fiber production and the fiber opening process in nonwoven fabric production. An adhesive hollow composite fiber was found and reached the present invention.

  That is, the present invention is intended to achieve the above object, and adopts the following configuration.

The core part is composed of a first component containing a polyester-based resin, and a sheath component contains a second component containing a polyolefin-based resin having a melting point lower by 30 ° C. or more than the melting point of the polyester-based resin. A heat-adhesive hollow composite fiber having a hollow portion in which the core portion is continuous with the fiber axis direction.
(A) The hollow ratio is 12% or more and 35% or less.
(B) The center point of the hollow portion is the center point of the sheath component.
(C) The hollow shape is a triangle, and each of the line segment ag / line segment af, the line segment bi / line segment bh and the line segment ce / line segment cd is 1.00 or more and 1.25 or less.
However, three triangular vertices are respectively point a, point b and point c, the intersection of a perpendicular drawn from point c to line segment ab and line segment ab is point d, and the intersection point with the hollow wall is point e There is an intersection point of a perpendicular drawn from the point b to the line segment ac and the line segment ac, and an intersection point between the perpendicular line and the hollow wall is a point i. Is the point f, and the point of intersection with the hollow wall is the point g.
(D) The composite ratio of the first component and the second component is 60% by mass or more / 40% by mass or less and 40% by mass or more / 60% by mass or less.
(E) Arrange the core sheath so that the centers of gravity of both components do not overlap at one point.

  The non-woven fabric using the heat-adhesive hollow composite fiber of the present invention is excellent in bulkiness and flexibility, and is suitably used for sanitary materials such as diapers, napkins and pads, or industrial materials such as household goods and filters.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the core part which has a hollow part in the heat bondable hollow conjugate fiber of this invention. BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic of the heat bondable hollow conjugate fiber of an Example. Cross-sectional schematic of the heat bondable hollow conjugate fiber of each comparative example.

  Next, the embodiment of the heat-bonded hollow conjugate fiber of the present invention and the method for producing the same will be specifically described.

  The first component constituting the core component of the heat-adhesive hollow conjugate fiber of the present invention contains a polyester resin. As the polyester resin, polyethylene terephthalate is preferably used in consideration of the raw material cost, the thermal stability of the obtained fiber, and the like. The polyethylene terephthalate is a polyester obtained with terephthalic acid as a main acid component and ethylene glycol as a main glycol component, and may be a homopolymer, but 90 mol% or more of the repeating units of ethylene terephthalate are It may be a copolymer containing a copolymer component capable of forming another ester bond in a proportion of 10 mol% or less. Examples of the copolymerizable compound include, as an acid component, dicarboxylic acids such as isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, dimeric acid and sebacic acid, and as a glycol component, for example, ethylene glycol, diethylene glycol, butane and the like. Diol, neopentyl glycol, cyclohexane dimethanol, polyethylene glycol and polypropylene glycol can be mentioned.

  The intrinsic viscosity of polyethylene terephthalate is preferably 0.60 to 0.75. The intrinsic viscosity is more preferably 0.62 to 0.72. If the intrinsic viscosity is less than 0.60, the crimp retention of the fiber may be reduced, and a fiber structure having a sufficient bulk may not be obtained. On the other hand, when the intrinsic viscosity exceeds 0.75, the melt viscosity may be high, which may make it difficult to produce fibers.

  In addition to aromatic polyesters containing aromatics in the structural unit such as polyethylene terephthalate, aliphatic polyesters can also be used, and preferred aliphatic polyester resins include polylactic acid and polybutylene succinate.

  Inorganic particles may be added to the core component (first component) or the sheath component (second component) in order to impart functions such as anti-smearing and matting. As the inorganic particles, silica sol, silica, alkyl coated silica, alumina sol titanium oxide and calcium carbonate etc. may be mentioned, but it is sufficient if they are chemically stable when added to polyester, especially chemical stability and aggregation From the viewpoint of properties and cost, titanium dioxide is preferably used. The concentration of the inorganic particles may be adjusted according to the target function, but it is preferably 0.01 to 20.0% by mass, and 0.05 to 8.0% by mass with respect to the polyester fiber mass. It is more preferable from the viewpoints of spinning operation, higher-order processability, and cost of fiber.

  Examples of the method of addition include a method in which the powder of inorganic fine particles is directly added to the core component and the sheath component, or a method in which inorganic fine particles are kneaded into a resin and made into a master batch and added. Although it is most preferable to use the same resin as the core component and the sheath component as the resin used for master batching, it is not particularly limited as long as it satisfies the requirements of the present invention, and resins different from the core component and the sheath component are used. It is also good.

  The second component constituting the sheath portion of the heat-adhesive hollow composite fiber of the present invention contains a polyolefin resin. The polyolefin resin is polyethylene (low density polyethylene, high density polyethylene, ultra high molecular weight polyethylene), polypropylene, polybutene-1, polyhexene-1, polyoctene-1, poly 4-methylpentene-1, polymethylpentene, 1, 2 Polybutadiene, 1,4-polybutadiene and the like can be used. Further, α-olefins such as ethylene, propylene, butene-1, hexene-1, octene-1 or 4-methylpentene-1 may be contained in such polymers in a small amount as a copolymerization component.

  As the polyolefin resin used in the present invention, high density polyethylene is preferably used. The melt mass flow rate of high density polyethylene is not particularly limited as long as it can be spun, but the measured value at a temperature of 190 ° C. with a load of 2.16 kg is measured by a measuring method according to JIS K 6922-2. 8 to 25 g / 10 min is preferable, and more preferably 10 to 20 g / 10 min.

  Next, the heat-adhesive hollow conjugate fiber of the present invention preferably has one hollow portion continuous with the fiber axial direction.

  The hollow ratio is 12% or more and 35% or less, preferably 15% or more and 30% or less. When it is less than 12%, the softness of the non-woven fabric becomes poor, and when it exceeds 35%, the hollow portion is crushed in the fiber manufacturing process and the non-woven fabric manufacturing process, the fiber cross-sectional shape is deformed, and the bulkiness and flexibility of the non-woven fabric are not obtained sufficiently . Here, the hollow percentage refers to the area of the hollow portion relative to the total area (including the hollow portion) of the heat-adhesive hollow composite fiber.

  The hollow portion is preferably disposed at the center point of the sheath component, ie, at the center point of the fiber cross section. That is, the fact that the hollow portion is at the center in the fiber cross section means that the hollow portion is not substantially eccentric. If the hollow part is not located in the center of the fiber but is unevenly distributed, the hollow part collapses from the thin part in the fiber manufacturing process and the nonwoven fabric manufacturing process, and the fiber cross-sectional shape is deformed, and sufficient bulk and flexibility of the nonwoven fabric are obtained. Absent.

  The shape of the hollow portion is preferably substantially triangular. FIG. 1 is a view showing the shape of the hollow portion of the heat-bonded hollow conjugate fiber of the present invention, and the substantially triangular shape means a triangular shape constituted by curves as shown in FIG. The three apexes of the triangular shape of the hollow part of the hollow fiber are respectively a, b and c, and the three sides of the triangle connecting the three points by straight lines are ab, bc and ca. The perpendicular line cd is drawn from the point c to the side ab, and the point of intersection with the hollow portion wall on the extension of the perpendicular line cd is e. From the point a and the point b, perpendicular lines are drawn also to the side bc and the side ca, respectively, and points f, g, h and i are determined as shown. The hollow part of the heat-bonded hollow composite fiber of the present invention is triangular, more preferably an equilateral triangle, and the values of line segment ag / line segment af, line segment bi / line segment bh, line segment ce / line segment cd Is preferably in the range of 1.00 to 1.25, more preferably 1.00 to 1.20. If it is less than 1.00, the hollow rate becomes low and the softness of the non-woven fabric can not be obtained. If it exceeds 1.25, the hollow portion is easily crushed in the fiber production process or the nonwoven fabric production process, and the fiber cross-sectional shape is deformed, and sufficient bulkiness or flexibility of the nonwoven fabric can not be obtained.

  The composite ratio of the heat-bonded hollow conjugate fiber of the present invention in which the core part is a polyester resin (first component) and the sheath part is a polyolefin resin (second component) is (mass ratio 1) / (mass ratio 2) Component) = 60/40 to 40/60. More preferably, the ratio by mass is (first component) / (second component) = 55/45 to 45/55.

  When the content of the core component exceeds 60% by mass, the composition of the polyester resin becomes high, the flexibility of the non-woven fabric is deteriorated, and the composition of the sheath component which is the heat adhesive component becomes low. Do. On the contrary, if the sheath component exceeds 60% by mass, the constitution of the core component becomes small, which causes a problem in the mechanical strength of the non-woven fabric.

  The heat-bonded hollow conjugate fiber of the present invention is preferably core-sheath-arranged so that the centers of gravity of the core and the sheath do not overlap at one point in the fiber cross section. When the centers of gravity of both parts overlap at one point, no structural difference crimp can be obtained, and the bulk of the non-woven fabric can not be obtained.

The single fiber fineness of the heat-bonded hollow conjugate fiber of the present invention is preferably 1.0 to 10.0 dtex, more preferably 1.5 to 6.0 dtex. When the single fiber fineness is less than 1.0 dtex, since the fineness is small, the card processability in the non-woven fabric production process is reduced, and the texture of the obtained non-woven fabric is deteriorated. When it exceeds 10.0 dtex, the rigidity of the fiber is increased because the fineness is increased, and the flexibility of the non-woven fabric is not obtained. The crimp number of the heat-bonded hollow conjugate fiber of the present invention is preferably 10 to 20 peaks / 25 mm. More preferably, it is 12-18 mountain / 25 mm. When the number of crimps is less than 10 peaks / 25 mm, the entanglement of the fibers is reduced, so that the card processability in the nonwoven fabric manufacturing process is reduced, and the texture of the obtained nonwoven fabric is deteriorated. When it exceeds 20 piles / 25 mm, the entanglement property of the fiber is strong, and the openability of the fiber is deteriorated, so that the card processability in the non-woven fabric manufacturing process is reduced, and the texture of the obtained non-woven fabric is deteriorated.

  The crimp rate of the heat-bonded hollow conjugate fiber of the present invention is preferably 10 to 25%, more preferably 14 to 20%. When the crimp rate is less than 10%, the entanglement of the fibers is reduced, so that the card processability in the non-woven fabric manufacturing process is reduced, and the texture of the obtained non-woven fabric is deteriorated. If it exceeds 25%, the entanglement of the fibers is strong, and the openability of the fibers is deteriorated, so that the card processability in the non-woven fabric manufacturing process is reduced, and the texture of the obtained non-woven fabric is deteriorated.

  The dry heat shrinkage ratio at 140 ° C. treatment of the heat-bonded hollow conjugate fiber of the present invention is preferably 0.3 to 3%, more preferably 0.5 to 2.5%. In order to obtain a fiber having a dry heat shrinkage of less than 0.3%, the drying temperature condition is to be increased, and as a result, it is difficult to stably obtain a fiber because polyethylene is likely to be melt-bonded. Fibers having a dry heat shrinkage of more than 2.5% have poor dimensional stability of the non-woven fabric in the heat bonding step, and a stable product can not be obtained.

  Next, a method of producing the heat-bonded hollow conjugate fiber used in the present invention will be specifically described by exemplifying one embodiment.

  The heat-bonded hollow conjugate fiber of the present invention is melt spun so that the core component is a polyester resin and the sheath component is a polyolefin resin so as to form an eccentric core-sheath hollow shape to obtain an undrawn yarn, which is heat drawn. It manufactures by applying a crimp using a crimper such as a staffer box type crimper through a tension heat treatment process. This will be described in more detail below.

  First, a polyester resin and a polyolefin resin are melted, and a polymer is discharged from an eccentric core / sheath hollow die having discharge holes preferably 300 to 600 holes. In order to obtain a triangular hollow shape, it is preferable to use a die in which three slits are arranged.

  The polymer is produced in a uniflow type in which the wind is blown from only one side of the yarn, or in an annular type in which the wind is uniformly blown toward the inner circumference from all directions of the outer circumference of the yarn.

  In the Uniflow type cooling, immediately after polymer spinning, the air temperature is 10 to 25 ° C., the air volume is 70 to 130 m / min, the cooling length is 30 to 60 mm, and after cooling the yarn, the air volume is 120 to 170 m / min, the cooling length 500 to Further cool the yarn at 900 mm. Even if the cooling air temperature is less than 10 ° C., the hollow ratio can not be further improved, leading to deterioration of the energy consumption rate. If the temperature exceeds 25 ° C., it becomes difficult for the polymer to solidify, and a target hollow percentage can not be obtained. If the air volume immediately after polymer spinning is less than 70 m / min, it becomes difficult to solidify the polymer and a target hollow ratio can not be obtained. When it exceeds 130 m / min, thread breakage occurs and the spinning operability deteriorates. In addition, if the cooling length is less than 30 mm, the cooling is insufficient, and the target hollow ratio can not be obtained. When it exceeds 60 mm, thread breakage occurs and the spinning operability deteriorates. If the air volume in the next cooling step is less than 120 m / min, it becomes difficult to solidify the polymer, and the hollow rate decreases. When it exceeds 170 m / min, thread breakage occurs and the spinning operability deteriorates.

  In the annular type cooling, immediately after polymer spinning, the yarn is cooled with an air temperature of 10 to 25 ° C., an air volume of 70 to 170 m / min, and a cooling length of 200 to 500 mm. Even if the cooling air temperature is less than 10 ° C., no further improvement in the hollowness ratio can be obtained, leading to deterioration of the energy consumption rate. When the temperature exceeds 25 ° C., the hollow rate decreases. If the air volume immediately after polymer spinning is less than 70 m / min, it becomes difficult to solidify the polymer, and the hollow ratio decreases. Even if it exceeds 170 m / min, the hollow ratio improvement can not be obtained more and it leads to deterioration of energy unit consumption. If the cooling length is less than 200 mm, the cooling will be insufficient and the hollow rate will decrease. Even if it exceeds 500 mm, the hollow ratio improvement can not be obtained more than that, and the energy consumption unit leads to deterioration.

The cooled yarn is applied with a spinning oil, preferably taken up at a speed of 900 to 1500 m / min, to obtain an undrawn yarn.
Next, the undrawn yarn tow thus obtained is preferably drawn at a draw ratio of 2.0 to 4.0 times using a liquid bath at a temperature of 80 to 100 ° C. and subjected to tensile heat treatment at 80 to 115 ° C. If the tension heat treatment temperature is less than 80 ° C., the crimpability appears in the subsequent fiber drying step, whereby the card processability in the non-woven fabric manufacturing step is reduced, and the texture of the obtained non-woven fabric is deteriorated. When the temperature exceeds 115 ° C., the polyethylene melts in the fiber production process because it approaches the melting point of polyethylene.

  Next, a target crimp is applied using a crimp application device such as a staffer box, and cut to a specified length after drying at a temperature of 100 to 115 ° C.

  The heat-bonded hollow conjugate fiber obtained in this manner is opened and then carded to form a web, and a polyester resin constituting the core part at a temperature higher than the melting point of the second component containing the polyolefin resin constituting the sheath part Heat treatment at a temperature lower than that of the first component, including the above, to melt bond the sheath portion and process it into a non-woven fabric. As a heat treatment method, a method such as a hot air drier, a suction drum drier, an emboss roll or the like can be used, but in order to obtain a non-woven fabric having bulkiness and flexibility, an air suction type drier is preferable.

  The heat-adhesive hollow composite fiber of the present invention is, for example, sanitary materials (absorbent articles) such as diapers, napkins, incontinence pads, medical hygiene materials such as gowns, surgical clothes, etc., sheet for walls, shoji paper, floor materials, etc. Interior materials, cover cloths, wipers for cleaning, life related materials such as garbage covers, disposable toilets, toiletry products such as toilet covers, pet sheets, pet diapers, pet supplies such as pet towels, wiping materials, filters , Industrial materials such as cushioning materials, oil adsorbents, adsorbents for ink tanks, general medical materials, bedding materials, nursing care products, etc. for various fiber products that require bulkiness and compression resistance be able to.

  Next, the heat-adhesive hollow conjugate fiber of the present invention will be described in detail using examples. The measuring methods of physical properties etc. are as follows.

(Single fiber fineness, number of crimps, crimp rate, fiber length)
Fiber physical properties were measured according to JIS L1015 (2010).

(Hollow rate)
The cross section of the obtained heat-bonded hollow conjugate fiber is photographed using a microscope at a magnification of 400 times, and the cross-sectional photograph is doubled and copied. The cross section of the fiber part was cut off from the copied paper, the mass was measured by an electronic balance, and the hollow ratio was calculated by averaging N = 20.

(Hollow shape)
The cross section of the obtained heat-bonded hollow conjugate fiber is photographed using a microscope at a magnification of 400 times, and the cross-sectional photograph is doubled and copied. On the copied sheet, the line segment ag, line segment af, line segment bi, line segment bh, line segment ce, and line segment cd are measured, and line segment ag / line segment af, line segment bi / line segment bh, line The minute ce / line segment cd was calculated and N = 20 was averaged. The line segment calculated value 1.00-1.25 was evaluated as pass.

(The bulkiness of non-woven fabric)
An air-through non-woven fabric with a heat processing temperature of 150 ° C and a basis weight of 20 g / m ² was prepared using a heat-bonded hollow conjugate fiber, and the thickness of the non-woven fabric was measured at a load of 0.2 kPa according to JIS L 1913A method, N It calculated by the average value of = 10. The thickness of the nonwoven fabric evaluated that 1.5 mm or more was a pass.

(Flexibility of non-woven fabric)
Measured according to JIS L 1913 6.7 bending resistance (handle index method), and calculated using an average value of N = 3. The softness of the non-woven fabric in the flow direction (MD direction) of the card machine was evaluated as a pass of less than 65 mN.

Example 1
The heat-bonded composite fiber was manufactured by the following method. The mass ratio of a polyethylene terephthalate resin (first component) having an intrinsic viscosity of 0.650 (first component) to a high density polyethylene resin (second component) having a melt mass flow rate of 18 (first component) / (second component) = 50 / It melted so as to be 50, and was spun through an eccentric core-sheath hollow die having 400 discharge holes. In the Uniflow type cooling, immediately after polymer spinning, after cooling the yarn with an air temperature of 20 ° C, an air volume of 100 m / min, a cooling length of 40 mm, the air volume of 140 m / min, a cooling length of 600 mm further cools the yarn and takes it off An undrawn yarn was obtained at a speed of 1000 m / min.

  Next, the undrawn yarn tow thus obtained is subjected to one-step drawing at a draw ratio of 3.0 times using a liquid bath at a temperature of 85 ° C., and after tension heat treatment at 100 ° C., a staffing box crimper The mixture was crimped using the following, dried at 110 ° C. and cut. The obtained heat-adhesive hollow conjugate fiber has a single fiber fineness of 2.5 dtex, 13 crimps / 25 mm, a crimp rate of 19%, a fiber length of 38 mm, a hollow rate of 20%, line segments (lines A fiber physical property is obtained in which the ag / line segment af, the line segment bi / line segment bh, and the line segment ce / line segment cd are all 1.15). The non-woven fabric using this fiber was confirmed to be a non-woven fabric having both bulkiness and flexibility. The results are shown in Table 1.

Comparative Example 1
A heat-bonded composite fiber was produced under the same conditions as in Example 1 except that the hollow core had a round structure and was spun through a four-point supporting eccentric core sheath hollow die. The heat-adhesive composite fiber obtained has obtained fiber physical properties with a single fiber fineness of 2.5 dtex, a crimp number of 14 peaks / 25 mm, a crimp rate of 20%, and a fiber length of 38 mm. When the hollow portion was deformed in the process, the hollow portion was crushed by the deformation of the fiber cross section, and the bulkiness and flexibility of the nonwoven fabric were not obtained. The results are shown in Table 1.

Comparative Example 2
A heat-bonded composite fiber was produced under the same conditions as in Example 1 except that it was spun through a concentric core-sheath hollow die. The heat-adhesive composite fiber obtained has a single fiber fineness of 2.5 dtex, a crimp number of 14 peaks / 25 mm, a crimp rate of 17%, a fiber length of 38 mm, a hollow rate of 19% and a line segment of 1. Although the fiber physical property set to 15 was obtained, the bulkiness of the nonwoven fabric was not obtained because of the concentric core-sheath structure. The results are shown in Table 1.

Comparative Example 3
A heat-bonded composite fiber was produced under the same conditions as Example 1, except that it was spun through an eccentric core-sheath base. The heat-adhesive composite fiber obtained had a fiber physical property with a single fiber fineness of 2.5 dtex, a crimp number of 14 peaks / 25 mm, a crimp rate of 18%, and a fiber length of 38 mm. Since it did not exist, the softness | flexibility of the nonwoven fabric was not obtained. The results are shown in Table 1.

Comparative Example 4
Immediately after polymer spinning, the yarn is cooled with an air temperature of 20 ° C., an air volume of 60 m / min, and a cooling length of 40 mm, and then the air volume is 60 m / min, the yarn is further cooled with a cooling length of 600 mm and undrawn at a take-up speed of 1000 m / min. A heat-bonded composite fiber was produced under the same conditions as in Example 1 except that a yarn was obtained. The heat-adhesive composite fiber obtained has a single fiber fineness of 2.5 dtex, 13 crimps / 25 mm, a crimp rate of 19%, a fiber length of 38 mm, a hollow rate of 5%, and a line segment of 1. Although the fiber physical properties to be obtained were obtained, the flexibility of the non-woven fabric was not obtained because the hollowness ratio was low and the line segment was high. The results are shown in Table 1.

Comparative Example 5
The mass ratio of a polyethylene terephthalate resin (first component) having an intrinsic viscosity of 0.650 (first component) to a high density polyethylene resin (second component) having a melt mass flow rate of 18 (first component) / (second component) = 65 / A heat-bonded composite fiber was produced under the same conditions as in Example 1 except that it was melted to be 35. The heat-adhesive composite fiber obtained has a single fiber fineness of 2.5 dtex, a crimp number of 14 peaks / 25 mm, a crimp rate of 20%, a fiber length of 38 mm, a hollow rate of 25%, and a line segment of 1. Although the fiber physical property to be 14 was obtained, since the polyester mass was high, the softness | flexibility of the nonwoven fabric was not obtained. The results are shown in Table 1.

Comparative Example 6
The mass ratio of a polyethylene terephthalate resin (first component) having an intrinsic viscosity of 0.650 (first component) to a high density polyethylene resin (second component) having a melt mass flow rate of 18 (first component) / (second component) = 35 / A heat-bonded composite fiber was produced under the same conditions as in Example 1 except that it was melted to be 65. The heat-adhesive composite fiber obtained has a single fiber fineness of 2.5 dtex, a crimp number of 16 peaks / 25 mm, a crimp rate of 16%, a fiber length of 38 mm, a hollow rate of 15%, and a line segment of 1. Although the fiber physical property set to 23 was obtained, since the mass of polyethylene was high, the bulkiness of the nonwoven fabric was not obtained. The results are shown in Table 1.

1: Hollow part 1 ': Hollow part wall 2: Core part 3: Sheath part 4: Fiber cross section center a, b, c: Triangular apex d: normal line drawn from point c to line segment ab Point of intersection e: point of intersection between the perpendicular drawn from the point c to the line ab and the wall of the hollow part h: point of intersection between the perpendicular drawn from the point b to the line ac and the line ac i: perpendicular drawn from the point b to the line ac Intersection point f between the wall and the hollow portion wall: intersection point g of the perpendicular drawn from the point a to the line segment bc g: intersection point of the perpendicular drawn from the point a to the line segment bc and the hollow wall

Claims (1)

The core part is a first component containing a polyester resin, and the sheath part is a second component containing a polyolefin resin having a melting point lower than that of the polyester resin by 30 ° C. or more, and the following (i) to (e) The heat-adhesive hollow composite fiber, wherein the first component has one hollow portion continuous with the fiber axial direction.
(A) The hollow ratio is 12% or more and 35% or less.
(B) The center point of the hollow portion is the center point of the sheath component.
(C) The hollow shape is a triangle, and each of the line segment ag / line segment af, the line segment bi / line segment bh and the line segment ce / line segment cd is 1.00 or more and 1.25 or less.
However, three triangular vertices are respectively point a, point b and point c, the intersection of a perpendicular drawn from point c to line segment ab and line segment ab is point d, and the intersection point with the hollow wall is point e There is an intersection point of a perpendicular drawn from the point b to the line segment ac and the line segment ac, and an intersection point between the perpendicular line and the hollow wall is a point i. Is the point f, and the point of intersection with the hollow wall is the point g.
(D) The composite ratio of the first component and the second component is 60% by mass or more / 40% by mass or less and 40% by mass or more / 60% by mass or less.
(E) Arrange the core sheath so that the centers of gravity of both components do not overlap at one point.