JP2013044070A - Latent crimpable polyester conjugate fiber and nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a latent crimpable polyester conjugate fiber that is excellent in surface properties and processability, suitable for use in obtaining a nonwoven fabric that is easy to cut and has excellent elongation property, longation recovery property and a soft feeling.SOLUTION: There is provided a conjugate fiber that has a copolymerized polyethylene terephthalate (A) in which 2-7 mol% of 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane and 5-13 mol% of isophthalic acid are copolymerized and a polyethylene terephthalate (B) that includes 0.5 mol% or less of 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane and 1 mol% or less of isophthalic acid conjugated together in a side-by-side state. The latent crimpable polyester conjugate fiber has a single fiber elongation at break of 30% or less, a toughness of 17-23 cN/dtex (%), the number of crimps developed at 180°C of 30-50/25 mm. The mass ratio of the aforementioned (A) and (B) is (A)/(B)=10/90-40/60.

Description

  The present invention relates to a latent crimpable polyester composite fiber and a nonwoven fabric containing the latent crimpable polyester composite fiber.

  Polyester fibers are excellent in mechanical properties, thermal stability, washability, and the like, and are therefore used in a very wide range of fields such as clothing, industrial materials, and interiors. Among these uses, in the use of living materials, in particular, the application of adhesive substrates, fibers that are rich in stretchability and elastic recovery are demanded due to demands for functionality and fit.

  Conventionally, as a method for imparting stretchability to a polyester fiber, a method using a polyester composite fiber having latent crimping ability is known.

  For example, a latently crimpable polyester composite fiber using a polyester mainly composed of ethylene terephthalate units obtained by copolymerizing 3 to 6 mol% of a structural unit having a metal salt sulfonate group has been proposed (see Patent Document 1). However, as such a composite component polymer, a composite fiber using a polyester copolymerized with a structural unit having a metal sulfonate group has a problem that heavy metals generally used as a polymerization catalyst for the polymer are deposited on the fiber surface. It was. Furthermore, in the case of a sanitary material coated with a drug, this conjugate fiber also has a problem that the drug and the metal sulfonate group react to impair the drug efficacy.

  Separately, there is a composite fiber using a polyester mainly composed of ethylene terephthalate unit obtained by copolymerizing 2-7 mol% of 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane and 5-13 mol% of isophthalic acid. It has been proposed (see Patent Document 2). However, this proposal has a problem that the shrinkage ratio of the fiber during heat treatment is large and the texture becomes hard.

  Furthermore, a composite fiber using a polyester based on ethylene terephthalate units, in which 4 to 12 mol% of isophthalic acid and 3 to 6 mol% of isophthalic acid having a metal salt sulfonate group are copolymerized with respect to the acid component, is proposed. (See Patent Document 3), and it has been shown that the use of this polyester optimizes the elongation and strength of the fiber and improves the cutting ability. However, since a structural unit having a metal sulfonate group is included, there is a problem of the surface properties described above, and it is unsuitable for use in sanitary materials.

JP 62-78214 A JP-A-7-54216 JP 2003-89928 A

  However, in the above-mentioned conventional composite fiber, the composite fiber using a copolymer component that does not impair the medicinal effect has a problem that the strength and elongation are large, so that the cutting property of the nonwoven fabric processing is not good and the texture is hard. was there.

  Therefore, the object of the present invention is to eliminate the disadvantages of the above-mentioned prior art, that is, the hardening of the texture, the loss of medicinal effect, the cutting failure after the nonwoven fabric processing, the excellent stretchability and the stretch recovery property, and the good cutability and softness. An object of the present invention is to provide a latent crimpable polyester composite fiber excellent in surface properties and processability, which is suitable for obtaining a fabric such as a nonwoven fabric and a woven or knitted fabric having a good texture.

  As a result of investigations to solve the above-mentioned problems, the inventors of the present invention can obtain a soft texture by suppressing the mass ratio of the copolymerized polyester component, and can suppress the strength and elongation, and can be within an appropriate range. As a result, they have reached the present invention.

The latent crimpable polyester composite fiber of the present invention comprises 2 to 7 mol% of 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane (hereinafter sometimes abbreviated as BHPP) and isophthalic acid (hereinafter referred to as BHPP). The copolymer polyethylene terephthalate (A) obtained by copolymerizing 5 to 13 mol% and 0.5 mol of 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane are sometimes abbreviated as IPA. %, And polyethylene terephthalate (B) having an isophthalic acid content of less than 1 mol% is a composite fiber bonded side-by-side, and the single fiber has a cut elongation of 30% or less and is obtained by the following formula (1): fiber toughness ^{17~23cN / dtex · (%) 1/2} , expressed crimps speed during no-load heat treatment at a temperature of 180 ° C. is 30 to 50 U / 25 mm, before A latent crimpable polyester composite fiber characterized in that a mass ratio of the copolymerized polyethylene terephthalate (A) and the polyethylene terephthalate (B) is (A) / (B) = 10/90 to 40/60. is there.
Toughness (cN / dtex · (%) ^1/2 ) = Cut strength (cN / dtex) × Cut elongation (%) ^1/2 (1)
Further, the nonwoven fabric of the present invention is a nonwoven fabric containing 70 mass% or more of the latent crimpable polyester composite fiber of the present invention, and has an elongation rate of 60% and an elongation recovery rate of 55% or more. It is a nonwoven fabric.

  INDUSTRIAL APPLICABILITY According to the present invention, a latent bag having excellent workability and surface properties suitable for obtaining a fabric such as a nonwoven fabric or a woven or knitted fabric having a soft texture and good cutability, and having excellent stretchability and stretch recovery properties. A polyester composite fiber having compressibility is obtained. And using this latent crimpable polyester composite fiber of the present invention, it is possible to obtain a nonwoven fabric and a woven or knitted fabric having a soft texture and good cutability as described above and excellent in stretchability and stretch recovery properties. .

  Next, the latent crimpable polyester composite fiber of the present invention will be described in detail.

  The latent crimpable polyester composite fiber of the present invention is composed of a highly shrinkable copolymer polyethylene terephthalate (A) and a low shrinkage polyethylene terephthalate (B) compared to the copolymerized polyethylene terephthalate (A). Less than 0.5 mol% of copolymerized polyethylene terephthalate (A) obtained by copolymerizing ˜7 mol% and IPA 5 to 13 mol%, and 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane Polyethylene terephthalate (B) having an acid content of less than 1 mol% is a polyester conjugate fiber bonded side-by-side, and is a latent crimpable conjugate fiber that develops spiral crimps by relaxation heat treatment.

  The copolymerized polyethylene terephthalate (A) used in the present invention is a copolymerized polyethylene terephthalate having an ethylene terephthalate unit as a main constituent, and BHPP or an ester-forming derivative thereof (hereinafter also including an ester-forming derivative) is used as a copolymerization component. And copolymer polyethylene terephthalate modified with IPA. The ethylene terephthalate unit referred to here is a unit obtained by subjecting one equivalent of terephthalic acid and ethylene glycol to a dehydration condensation reaction.

  In the present invention, the copolymerization ratio of BHPP in the copolymerized polyethylene terephthalate (A) is 2 to 7 mol%, and among them, the copolymerization ratio is preferably 4 to 6 mol%. When the copolymerization ratio of BHPP is less than 2 mol%, the shrinkage properties are insufficient, and when it is made into a nonwoven fabric, its stretch rate and stretch recovery rate are small, and a sufficient stretch function cannot be obtained. On the other hand, when the copolymerization ratio of BHPP exceeds 7 mol%, the melting point of the polymer is lowered and the strength of the fiber is significantly lowered, so that it is not suitable for nonwoven fabric applications.

  Moreover, in this invention, the copolymerization ratio of IPA in copolymer polyethylene terephthalate (A) shall be 5-13 mol%, and it is preferable that a copolymerization ratio shall be 7-11 mol% especially. When the copolymerization ratio of IPA is less than 5 mol%, substantially large crimps cannot be obtained. On the other hand, when the copolymerization ratio of IPA exceeds 13 mol%, the melting point of the polymer is lowered, so that the thermal stability is reduced. Damaged.

  The polyethylene terephthalate (B) used in the present invention is a polyethylene terephthalate having a BHPP of less than 0.5 mol% and an IPA of less than 1 mol%.

  As described above, the polyethylene terephthalate (B) is obtained by copolymerizing less than 0.5 mol% of BHPP, and the copolymerization ratio is preferably less than 0.25 mol%, most preferably zero (0) mol. %.

  Further, as described above, the polyethylene terephthalate (B) is obtained by copolymerizing less than 1 mol% of IPA, and the copolymerization ratio is preferably less than 0.5 mol%, and most preferably zero (0) mol. %.

  In the polyethylene terephthalate (B) used in the present invention, when the copolymerization ratio of BHPP and IPA is increased, the thermal shrinkage difference with the copolymerized polyethylene terephthalate (A) becomes insufficient, and the resulting composite fiber is a non-woven fabric. Its elongation rate and elongation recovery rate are small and a sufficient expansion / contraction function cannot be obtained.

  Further, the copolymerized polyethylene terephthalate (A) component and the polyethylene terephthalate (B) component used in the present invention may contain other copolymerization components within a range not impairing the effects of the present invention.

  Examples of other copolymerizable components include dicarboxylic acids such as succinic acid and cyclohexadicarboxylic acid, and diols such as diethylene glycol, trimethylene glycol, butanediol, neopentyl glycol, and polyethylene glycol. . The copolymerization ratio of these other copolymerization components to ethylene terephthalate (A) and polyethylene terephthalate (B) is preferably 15 mol% or less, more preferably 10 mol% or less, and still more preferably. 5% or less.

  Polyethylene terephthalate (B) has a component that greatly inhibits crystallinity, BHPP, IPA, and sulfonate group compounds in order to make heat shrinkage lower than copolymerized polyethylene terephthalate (A). Etc. are preferably contained as little as possible.

  In the latent crimpable polyester composite fiber of the present invention, the intrinsic viscosity of the copolymerized polyethylene terephthalate (A) used is preferably 0.55 to 0.70 from the viewpoint of smoothly performing melt spinning. The intrinsic viscosity of the polyethylene terephthalate (B) used in the present invention is preferably 0.45 to 0.60 from the viewpoint of smoothly performing melt spinning. Further, from the viewpoint of ensuring sufficient crimp expression and not impairing the spinning stability, the intrinsic viscosity of the copolymerized polyethylene terephthalate (A) is preferably higher than the intrinsic viscosity of the polyethylene terephthalate (B). The difference in intrinsic viscosity between these two kinds of polymers is preferably 0.25 or less, more preferably 0.02 or more. If the difference in intrinsic viscosity is larger than 0.25, the yarn bends during spinning, making it difficult to spin stably. If the difference in intrinsic viscosity is smaller than 0.02, sufficient crimp expression cannot be obtained.

  Furthermore, in the latent crimpable polyester composite fiber of the present invention, various properties imparting agents such as a flame retardant, an antibacterial agent, a fragrance, a pigment and ceramics are added to the copolymerized polyethylene terephthalate (A) and / or polyethylene terephthalate (B). And additives can be optionally blended. As other spinning conditions, conventional spinning conditions of polyester composite fibers can be adopted.

  The mass ratio of copolymerized polyethylene terephthalate (A) and polyethylene terephthalate (B) is (A) / (B) = 10/90 to 40/60, and the mass ratio is particularly 20/80 to 30/70. It is desirable. When the mass ratio exceeds this range and the copolymerized polyethylene terephthalate (A) decreases, sufficient latent crimp cannot be expressed. Moreover, when the mass ratio exceeds this range and the copolymerized polyethylene terephthalate (A) increases, the crimps that develop are excessive and the texture becomes hard.

  In addition, by setting the mass ratio of the copolymerized polyethylene terephthalate (A) component to 40% or less, the elongation and strength of the resulting composite fiber can be kept within an appropriate range, and a composite fiber having an appropriate cutting property can be obtained. it can. When the copolymerized polyethylene terephthalate (A) is compounded in excess of 40%, the strength and elongation of the resulting composite fiber are increased, and a nonwoven fabric having an appropriate cutting property cannot be obtained.

  The structure of the latent crimpable polyester fiber of the present invention is a side-by-side structure in which the copolymerized polyethylene terephthalate (A) and the polyethylene terephthalate (B) are bonded in parallel in the longitudinal direction by an interface crossing the cross section of the fiber. The cross-sectional shape may be either hollow or solid.

  Moreover, it is preferable that the single fiber fineness of the latent crimpable polyester fiber of this invention is 0.5-10 dtex. When the single fiber fineness is less than 0.5 dtex, the yarn-making property is poor or the card passing property is poor, which is not preferable because the nonwoven fabric is poor. Moreover, when the single fiber fineness exceeds 10 dtex, a non-woven fabric with a soft texture tends to be obtained. The single fiber fineness is preferably 1 dtex to 5 dtex in terms of card passing properties and use of mixed cotton with other materials.

  The latent crimpable polyester composite fiber of the present invention has a single fiber cut elongation of 30% or less, particularly preferably 15 to 30%. When the cut elongation of the single fiber exceeds 30%, the nonwoven fabric made of the composite fiber of the present invention is not easily cut because the fibers are stretched, and fluff is generated on the cut surface of the nonwoven fabric.

In addition, in the present invention, the toughness of the latent crimpable polyester composite fiber obtained by the following formula (1) is 17 to 23 cN / dtex · (%) ^1/2 . The toughness is particularly preferably 19 to 22 cN / dtex · (%) ^1/2 .
Toughness (cN / dtex · (%) ^1/2 ) = Cut strength (cN / dtex) × Cut elongation (%) ^1/2 (1)
When the toughness is less than 17 cN / dtex · (%) ^1/2 , the fiber is cut at the time of processing the nonwoven fabric, which causes a nonwoven fabric defect due to flying cotton. Moreover, when toughness exceeds 23 cN / dtex * (%) ^1/2 , the intensity | strength of the nonwoven fabric obtained will become high too much and cutting property will worsen.

In order to set the cut elongation of the composite fiber of the present invention to 30% or less and the toughness to 17 to 23 cN / dtex · (%) ^1/2 , the mass ratio of the copolymerized polyethylene terephthalate (A) component is set to 40% or less. At the same time, it can be achieved by quenching using a quenching apparatus (hereinafter referred to as sub-chimney) installed directly below the base and increasing the orientation of the polymer in the fiber. Simply increasing the draw ratio increases the strength of the fibers, making it impossible to obtain fibers with moderate toughness.

  Furthermore, in the latent crimpable polyester composite fiber of the present invention, in order to obtain a nonwoven fabric having a soft texture, stretchability, and stretch recovery, the number of crimps developed during no-load heat treatment at a temperature of 180 ° C. is 30 to 30. 50 co / 25 mm. When the number of crimps is less than 30/25 mm, the stretchability is remarkably lowered and the stretch recovery property is low. Moreover, when the number of crimps exceeds 50 co / 25 mm, the texture when made into a non-woven fabric tends to be hard. In order to obtain a nonwoven fabric having an optimum texture and stretchability, the number of crimps expressed is preferably 35 to 45 co / mm.

  In order to set the expression crimp number of the composite fiber of the present invention to 30 to 50/25 mm, the mass ratio of the copolymerized polyethylene terephthalate (A) to the polyethylene terephthalate (B) is (A) / (B) = 10/90. It can achieve by setting it to -40/60.

  The latent crimpable polyester composite fiber of the present invention can be produced by the following spinning method.

  After the copolymerized polyethylene terephthalate (A) and the polyethylene terephthalate (B) are melted and made into a composite flow at a predetermined mass ratio using a composite melt spinning apparatus, the discharge holes having a pore diameter of 0.3 to 0.6 mm are made 150 to Through a spinneret having 700 holes, melt spinning is performed at a spinning temperature 20 to 40 ° C. higher than the melting point, and the fiber spun from the die is rapidly cooled by air at a temperature of 10 to 25 ° C. at a temperature of 10 to 25 ° C. Then, after cooling by blowing air at a temperature of 10 to 25 ° C. with a flow of 40 to 100 m / min, a spinning oil agent is applied, and it is unstretched by temporarily placing it in a can at a take-up speed of 900 to 1500 m / min. Get a thread toe.

  Next, the obtained undrawn yarn tow was stretched at a draw ratio of 2.5 to 4.0 times using a liquid bath at a temperature of 75 to 95 ° C. and fixed at a temperature of 30 to 130 ° C. Apply heat treatment, apply a crimp of preferably 12-20 piles / 25 mm using a crimper, apply a finishing oil solution by spraying, dry at a temperature of 60-150 ° C. for 15-30 minutes, length 20 A latent crimpable polyester composite fiber having a single fiber fineness of 0.5 to 10 dtex can be produced by cutting to ˜80 mm.

In addition, the latent crimpable polyester composite fiber of the present invention is preferably pressed by an indentation pressure of 2 to 3 kg / min. It is preferable to use raw cotton to which mechanical crimps of 12 to 20/25 mm are given by cm ² G.

  The nonwoven fabric of this invention contains 70 mass% or more of the above-mentioned latent crimpable polyester composite fiber of this invention. When the latent crimpable polyester composite fiber is less than 70% by mass, a nonwoven fabric excellent in the stretch rate intended in the present invention cannot be obtained.

  That is, in the nonwoven fabric of the present invention, in addition to the latent crimpable polyester composite fiber of the present invention, natural fibers such as ordinary polyester fiber, heat-adhesive binder fiber, cotton, wool and hemp are within a range of less than 30% by mass. Etc. can be blended as appropriate.

  The non-woven fabric of the present invention is obtained by applying the raw cotton (short fiber) composed of the above-described latently crimpable polyester composite fiber of the present invention alone or, if necessary, with a normal polyester fiber or a heat-bonding binder fiber, and putting it on a card. Fabricate the web, and if necessary, apply the needle punch to the resulting fiber web, then heat-treat it in a free state to reveal latent crimps, causing entanglement between fibers, and stretch recovery A very excellent nonwoven fabric can be obtained.

  The stretch rate of the nonwoven fabric of the present invention is 60% or more. When the elongation rate is less than 60%, it cannot be applied to uses requiring stretchability.

  The elongation recovery rate of the nonwoven fabric of the present invention is 55% or more. When the elongation recovery rate is less than 55%, it tends to be deformed by an external force.

The basis weight of the nonwoven fabric of the present invention is preferably 50 to 150 g / m ² . If the basis weight is less than 50 g / m ² , sufficient strength of the nonwoven fabric cannot be obtained, and if the basis weight exceeds 150 g / m ² , the intended stretchability may not be obtained. In order to obtain more appropriate strength and stretchability, the basis weight is preferably 70 to 110 g / m ² .

  The latent crimpable polyester composite fiber of the present invention can be used as a spun yarn in addition to a nonwoven fabric, and they can be used for applications that require stretchability and fit properties, for example, application to adhesive substrates, sports clothing, etc. It can be used for woven and knitted fabrics and batting.

  Next, the latent crimpable polyester composite fiber of the present invention will be described in detail by way of examples, but the present invention is not limited to only the examples.

  The measuring method of the characteristic value etc. in the present invention is as follows.

(Evaluation of raw cotton)
<Fineness>
It measured according to the method of JIS-L1015 (2010).

<Cut strength (cN / dtex) and elongation (%)>
It measured according to the method of JIS-L1015 (2010).

<Number of crimps (co / 25mm)>
It measured by the method of JIS-L1015 (2010). The number of crimps expressed was measured after subjecting the short fibers to a dry heat treatment at a temperature of 180 ° C. for 5 minutes.

(Evaluation of non-woven fabric)
<Weight (g / m ² )>
The sample weight of 20 cm × 20 cm was measured by the method of JIS-L1085 (1998) and determined as the weight per cm ² .

<Expansion rate>
About a nonwoven fabric test piece (5 cm width x about 60 cm length), one end of the test piece is fixed with an upper clamp using a tensile tester, and an initial load of 30 g is applied to the other end. Then mark 20 cm intervals and gently apply a load of 240 g. Measure the length between the marks after standing for 1 minute, and obtain the elongation percentage (%) by the following formula and express it as an average value of 3 times or more (up to one digit after the decimal point).
Elongation rate (%) = {(L ₁ −L ₀ ) / L ₀ } × 100
However, L ₀ : Length between original marks (20 cm)
L ₁ : Length (cm) between marks after applying a load of 240 g and leaving it for 1 minute
<Elongation recovery rate>
A test piece similar to that for measuring the elongation rate is attached using a constant-speed extension type tensile tester with a self-recording device so that the distance between the grips is 20 cm or 50 cm under an initial load of 30 g. It was determined at a pulling rate of 100% of the gripping interval per minute. The test piece is stretched to 80% of the elongation at a load of 240 g, the elongation recovery rate (%) at a constant load of 240 g is obtained by the following formula, and each is represented by an average value of 3 times or more.
Elongation recovery rate (%) = {(L ₁₀ −L ₁₁ ) / L ₁₀ } × 100
However, L ₁₀ : 80% elongation (cm) of elongation at a load of 240 g obtained at a 100% pulling rate at a grip interval per minute
L ₁₁ : Residual elongation (cm) after repeated loading 5 times.

<Texture>
Ten panelists ranked as very good (10 points), good (8 points), normal (5 points), and bad (0 points) by ranking the touch (feel; softness) when touched by hand. When the average score exceeds 8 points, the texture as a nonwoven fabric is very good (◎), 7 points to 8 points good (○), 4 points to less than 7 points (△), Less than 4 points were evaluated as bad (x). In the present invention, ◎ and ○ are acceptable.
<Cutability of nonwoven fabric>
Samples each having a width and length of 20 cm were prepared, the sample was punched using a circular punching machine having an inner diameter of 10 cm, and evaluation was performed according to the following criteria, using the number of single-fiber fluff protruding on the cut surface as an evaluation index. In the present invention, ◎ and ○ are acceptable.
A: Number of fluff 0 to 1 / circumference ○: Number of fluff 2 to 5 / circumference x: Number of fluff 6 or more / circumference

Example 1
As copolymerized polyethylene terephthalate (A), a copolymerized polyethylene terephthalate having ethylene terephthalate as the main component and copolymerized with 7.1 mol% of IPA and 4.4 mol% of BHPP, and polyethylene terephthalate homopolymer as polyethylene terephthalate (B). And a mass ratio (A) / (B) = 20/80 at a temperature of 300 ° C. from a round cross-section die hole by a composite melt spinning apparatus, and a discharge amount of 304 g / min, winding at a speed of 1200 m / min, A side-by-side undrawn yarn was obtained. At this time, quenching was performed by a sub-chimney attached directly under the base. After these undrawn yarns are converged, they are drawn at a draw ratio of 3.56 times and drawn at a drawing temperature of 85 ° C., subjected to heat treatment at a tension heat treatment temperature of 140 ° C., subjected to mechanical crimping with a push-type crimper, and then cut. As a result, short fibers having a crimp number of 15/25 mm, a fiber length of 51 mm, and a single fiber fineness of 2.2 dtex were obtained.

  Separately, a copolymerized polyethylene terephthalate fiber having a single fiber fineness of 4.4 dtex and a cut length of 51 mm, which was copolymerized with 40 mol% of isophthalic acid, was prepared as a thermal bonding fiber.

Next, the short fiber and the heat-bonding binder fiber obtained above are spread and mixed with an opener at a mass ratio of 95: 5, passed twice through a roller-type carding, and a fiber web having a basis weight of 120 g / m ² . Was subjected to a free shrink heat treatment in an oven at a temperature of 160 ° C. for 5 minutes, followed by a heat bonding treatment with a hot roll having a surface temperature of 160 ° C. for 1 minute to prepare a nonwoven fabric. The obtained non-woven fabric showed good results in both texture and cutting ability. Table 1 shows the characteristics of the short fibers (raw cotton) used and the evaluation results of the obtained nonwoven fabric.

(Example 2 and Example 3)
Except that the mass ratio of the copolymerized polyethylene terephthalate (A) and the polyethylene terephthalate (B) was (A) / (B) = 25/75 (Example 2) and 30/70 (Example 3), respectively. Spinning and drawing were performed under the same conditions as in Example 1, after giving mechanical crimps, cutting was performed to obtain short fibers. Next, a nonwoven fabric was prepared in the same manner as in Example 1, using the obtained short fibers and the same heat-bonding binder fibers as those used in Example 1. Example 2 having a smaller mass ratio of the copolymerized polyester component (A) showed lower toughness and better cutting properties, but in Example 3, higher elongation and elongation recovery rates were obtained. A good texture was obtained in any of the examples. Table 1 shows the characteristics of each short fiber (raw cotton) and the evaluation results of the nonwoven fabric.

Example 4
Spinning was carried out under the same conditions as in Example 3 except that copolymerized polyethylene terephthalate (A) was composed of ethylene terephthalate as the main component and copolymerized polyethylene terephthalate copolymerized with 6.0 mol% IPA and 5.4 mol% BHPP. After drawing and applying mechanical crimping, it was cut to obtain short fibers. Next, a nonwoven fabric was prepared in the same manner as in Example 1, using the obtained short fibers and the same heat-bonding binder fibers as those used in Example 1. Since the copolymerization ratio of BHPP increased as compared with Examples 1 to 3, a higher elongation rate and elongation recovery rate were exhibited, but the texture was slightly hardened. Moreover, the toughness showed a low value and the cutting property was good. Table 1 also shows the characteristics of each short fiber (raw cotton) and the evaluation results of the nonwoven fabric produced using the same as in Example 1.

(Comparative Example 1)
Under the same conditions as in Example 1 except that spinning is performed under the same conditions as in Example 1 except that cooling by sub-chimney is not performed at the same mass ratio as in Example 3, and the draw ratio is 3.40 times. After drawing and mechanical crimping, it was cut to obtain short fibers.

  Next, the short fiber obtained in the comparative example and the same heat-bonding binder fiber as used in Example 1 were mixed at a mass ratio of 95: 5, and a nonwoven fabric was prepared in the same manner as in Example 1. Since the obtained short fiber had high elongation and high toughness, the cutability of the nonwoven fabric was worse than that of Examples 1 to 4. Table 1 shows the characteristics of the short fibers (raw cotton) used and the evaluation results of the obtained nonwoven fabric.

(Comparative Example 2)
A short fiber is obtained by spinning and stretching under the same conditions as in Example 1 except that the mass ratio of the copolymerized polyethylene terephthalate (A) and the polyethylene terephthalate (B) is (A) / (B) = 50/50. It was.

  Next, the short fiber obtained in the comparative example and the same heat-bonding binder fiber as used in Example 1 were mixed at a weight ratio of 95: 5, and a nonwoven fabric was prepared in the same manner as in Example 1. The obtained short fibers had high toughness, and the cutability of the nonwoven fabric was worse than that of Examples 1 to 4. Moreover, since the number of crimp expression was high, the texture of the nonwoven fabric became hard. Table 1 shows the characteristics of the short fibers (raw cotton) used and the evaluation results of the obtained nonwoven fabric.

(Comparative Example 3)
Spinning and stretching under the same conditions as in Comparative Example 1 except that the mass ratio of the copolymerized polyethylene terephthalate (A) and polyethylene terephthalate (B) was (A) / (B) = 50/50, and mechanical crimping was performed. After giving, it cut | disconnected and obtained the short fiber. Next, the short fiber obtained in the comparative example and the same heat-bonding binder fiber as used in Example 1 were mixed at a mass ratio of 95: 5, and a nonwoven fabric was prepared in the same manner as in Example 1. The obtained short fibers were high in elongation, toughness, and number of crimps, and the cutability and texture of the nonwoven fabric were worse than those in Examples 1 to 4. Table 1 shows the characteristics of these short fibers (raw cotton) and the evaluation results of the nonwoven fabric produced using these short fibers in the same manner as in Example 1.

(Comparative Example 4)
A short fiber was obtained by spinning and drawing under the same conditions as in Example 1 except that the polyester based on ethylene terephthalate unit copolymerized with 9.1 mol% of IPA was used for the copolymerized polyethylene terephthalate (A).

  Next, the short fibers obtained in each of the comparative examples and the same heat-bonding binder fiber as used in Example 1 were mixed at a mass ratio of 95: 5, and a nonwoven fabric was prepared in the same manner as in Example 1. The obtained short fiber was high in both elongation and toughness, and the cutting properties were worse than those in Examples 1 to 4. Table 1 shows the characteristics of the short fibers (raw cotton) used and the evaluation results of the obtained nonwoven fabric.

Claims (2)

A copolymerized polyethylene terephthalate (A) obtained by copolymerizing 2-7 mol% of 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane and 5-13 mol% of isophthalic acid, and 2,2-bis [ 4- (2-hydroxyethoxy) phenyl] propane is a composite fiber in which polyethylene terephthalate (B) having 0.5 mol% or less and isophthalic acid is 1 mol% or less is bonded side-by-side, and the breaking elongation of a single fiber Is 30% or less, and the toughness of the fiber determined by the following formula (1) is 17 to 23 cN / dtex · (%) ^1/2 , and the number of crimps developed during no-load heat treatment at a temperature of 180 ° C. is 30 to 30%. 50 co / 25 mm, and the mass ratio of the copolymerized polyethylene terephthalate (A) to the polyethylene terephthalate (B) is (A) / (B) = 1. / 90 to 40/60 a latent crimpable polyester bicomponent fibers, characterized in that.
Toughness (cN / dtex · (%) ^1/2 ) = Cut strength (cN / dtex) × Cut elongation (%) ^1/2 (1)   A nonwoven fabric comprising 70 mass% or more of the latent crimpable polyester composite fiber according to claim 1, wherein the nonwoven fabric has an elongation rate of 60% or more and an elongation recovery rate of 55% or more.