JPH11189938A - Polypropylene terephthalate staple fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polypropylene terephthalate staple fiber suitably usable in a material for clothes such as inners or sports or material applications such as waddings or nonwoven fabrics and having a high stretch elastic recovery ratio and a high flexing recovery ratio, and to provide a method for producing the staple fiber. SOLUTION: This polypropylene terephthalate staple fiber is produced by a method for heat-treating a fiber substantially composed of polypropylene terephthalate, then applying crimps at 5-35% crimp ratio thereto and cutting the crimped fiber to 3-200 mm fiber length. The resultant staple fiber has 190% elastic recovery ratio at 10% extension and >=80% flexing recovery ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene terephthalate staple fiber and a method for producing the same, and more particularly, it is suitably used as a material for clothing made of spun yarn, such as inner materials for sports and the like, filling, and nonwoven fabric. The present invention relates to a polypropylene terephthalate short fiber which can be produced and a method for producing the same.

[0002]

2. Description of the Related Art Polyester fibers typified by polyethylene terephthalate have excellent mechanical strength, chemical resistance, heat resistance and the like, and are therefore widely used mainly for clothing and industrial purposes. However, polyethylene terephthalate fibers have not been suitably used for inner or sports applications where stretchability is required due to their low elongation elastic recovery and low bending recovery.

[0003] On the other hand, polypropylene terephthalate fibers have excellent elongation elastic recovery, low Young's modulus, good dyeability, and are chemically stable.
It has been known for a long time, as shown in Japanese Patent Application Laid-Open No. Hei.

Japanese Patent Publication No. Sho 49-21256 discloses a technique of an elastic crimped polyester fiber comprising a terephthalate ester of butanediol and propanediol having at least 70% flexural resilience. Although heat treatment was performed, crimping was performed, but elongation elastic recovery and bending recovery did not increase, and the characteristics of polypropylene terephthalate were not fully utilized.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the problems of the prior art and to provide a method for producing polypropylene terephthalate staple fibers having a high elongation elastic recovery rate and a high flexural recovery rate. .

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat treatment of a fiber consisting essentially of polypropylene terephthalate, followed by applying a crimp having a degree of crimp of 5 to 35% and a fiber length of 3 to 35%. A polypropylene terephthalate short fiber having a 10% elongation elastic recovery rate of 90% or more and a flexural recovery rate of 80% or more can be obtained by a method for producing a polypropylene terephthalate short fiber characterized by being cut into a length of 200 mm. it can.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The polypropylene terephthalate (PPT) of the present invention is a polyester obtained using terephthalic acid as a main acid component and 1,3 propanediol as a main glycol component. However, 20 mol%, more preferably 1 mol%
It may contain a copolymer component capable of forming another ester bond in a proportion of 0 mol% or less. As copolymerizable compounds, for example, dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, and sebacic acid; on the other hand, as glycol components, for example, ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, Examples thereof include, but are not limited to, cyclohexanedimethanol, polyethylene glycol, and polypropylene glycol.

[0008] Titanium dioxide as a matting agent, fine particles of silica or alumina as a lubricant, hindered phenol derivatives, coloring pigments and the like as antioxidants can be added as required.

The PPT used in the present invention is obtained by the following method. That is, dimethyl terephthalic acid and 1,
3-Propanediol was charged into a reaction vessel at a molar ratio of 1: 2, and transesterification was performed while distilling methanol at 140 ° C. to 230 ° C. using tetrabutyl titanate as a catalyst. It is obtained by carrying out polymerization at a constant temperature.

The intrinsic viscosity of PPT is 0.5 or more.
It is preferably 2 or less. If it is less than 0.5, it may be difficult to stably spin the fiber due to unevenness of fineness and thread breakage during spinning, or even if obtained, it may be inferior in practical aspects such as tensile strength and bending wear resistance. . When the intrinsic viscosity is 1.2 or more, the melt viscosity becomes too high, so that the measurement performance of a gear pump or the like is inferior, and it becomes difficult to perform stable spinning due to poor discharge, or the texture of the obtained fiber tends to be hard. May be undesirable. More preferably, the intrinsic viscosity of PPT is 0.8 or more and 1.0 or less.

The short PPT fiber of the present invention must have a 10% elongation elastic recovery of 90% or more and a flex recovery of 80% or more. If the 10% elongation elastic recovery is less than 90%, the stretchability is poor, and it may not be suitable for sports or the like which is one of the intended uses of the present invention.
On the other hand, if the bending recovery rate is less than 80%, there is a case where it is not suitable because it lacks resilience when used for wadding or the like and is easy to set.

Further, in order to impart a soft feeling, the Young's modulus is preferably 35 g / d or less.

The PPT short fiber of the present invention has a fiber length of 3 to 2
It needs to be 00 mm, more preferably 10 to 150 mm. The PPT short fiber may come off from the fiber end slightly in the course of the high-order processing, and when the fiber length is short, the rate of coming out increases, which is not preferable. On the other hand, if it is too long, the processability including the spinning process will be poor, which is not preferable.

It is necessary that the degree of crimp be 5 to 35%, more preferably 8 to 30%. If the degree of crimp is less than 5%, the entanglement between short fibers is low, the card passing property and the spinning property are deteriorated, and it is difficult to exhibit sufficient bulkiness. On the other hand, when the degree of crimp exceeds 35%, the entanglement becomes too high, entanglement occurs, the card passing property is reduced, and the spun yarn has poor uniformity.

[0015] The cross-sectional shape of the single yarn of the PPT short fiber of the present invention is not particularly limited, and may be appropriately selected from circular, triangular, flat, and hexagonal shapes according to the purpose of use.

Next, the method for producing PPT short fibers of the present invention will be described. The PPT short fibers of the present invention need to be heat-treated, and are preferably heat-treated under constant length or tension. The present inventors have conducted intensive studies for the purpose of improving the physical properties of PPT, and as a result, have found that elongation elastic recovery and bending recovery can be further improved by performing a heat treatment again on a PPT fiber obtained by spinning and drawing. Was.

The heat treatment may be either wet heat or dry heat treatment. The wet heat treatment has a temperature of 100 to 160 ° C. for a time of 0.01 to 90 minutes. The dry heat treatment has a temperature of 100 to 300 ° C.
The time is preferably 0.01 to 20 minutes, and more preferably, the wet heat treatment is performed at a temperature of 120 to 150 ° C. for a time of 1 to 1.
60 minutes, dry heat treatment temperature 150-250 ° C, time 1-1
5 minutes. Above this range, yarn breakage and fusion may easily occur during the heat treatment, and below the above range, the heat treatment may not be effective and the elongation elastic recovery and bending recovery may not be improved.

[0018]

The present invention will be described in more detail with reference to the following examples. In addition, each characteristic value in an Example was calculated | required by the following method. A. Intrinsic viscosity [η] 0.10 g of sample per 10 ml of orthochlorophenol
Was dissolved and measured at 25 ° C. using an Ostwald viscometer.

B. Strong elongation, Young's modulus The strong elongation, Young's modulus were measured using Orientec Tensilon UCT-100 according to JIS L1015.

C. Elongation elastic recovery rate The sample was measured for 20 m with a 1/30 g initial load per denier using a constant-speed extension type tensile tester with a self-recording device.
m, and set the pulling speed to 1
Stretch to a predetermined elongation to 0%. Immediately, from the stress-strain curve recorded by removing the weight at the same speed, a constant elongation up to a predetermined elongation was α, and a recovery elongation when the stress was reduced until the stress became equal to the initial load was β. Elongation elastic recovery (%) = β / α × 100

D. Flex recovery rate Fiber before cutting, width 30 × length 40 mm, thickness 40μ
The fiber is wound five times so that the fiber does not overlap with an initial load of 1/30 g per denier applied to the m plate, and a 1 kg load is applied to the bent portion of the fiber. After 30 seconds, the load is removed, the fiber is cut at the center of the plate, the recovery angle after 10 minutes is measured, and the recovery rate is calculated.

E. Crimping degree The length when the initial load (2 mg / d) is applied to the sample is a,
Let b be the length when a load (300 mg / d) is applied,
The degree of crimp (%) is calculated according to the following equation. The number of tests is set to 10 and the average value is shown. Crimp rate (%) = (ba) / b × 100

Example 1 A transesterification reaction was carried out at 140 ° C. to 230 ° C. while distilling off methanol at 19.4 kg of dimethyl terephthalic acid and 15.2 kg of 1,3-propanediol using tetrabutyl titanate as a catalyst. Further, polymerization was carried out at 250 ° C. under a constant temperature for 3 hours to obtain PPT having an intrinsic viscosity [η] of 0.89.

The PPT produced by the above method was spun at a spinning temperature of 260 ° C. using a spinneret having a discharge hole diameter of 0.3 mm at a spinning take-off speed of 1800 m / min to obtain an undrawn yarn. After drawing this undrawn yarn in a liquid bath, 15
A constant-length wet heat treatment at 0 ° C. for 5 minutes was performed, and mechanical crimping was performed by a press-fitting method, followed by cutting to obtain a 2 denier, 51 mm, 15% crimped PPT short fiber. This short fiber is 10%
98% elongation elastic recovery, 92% flex recovery after 10 minutes
%, And had excellent properties as a spun yarn for sports use, and excellent resilience as wadding.

Example 2 The PPT produced in Example 1 was spun at a spinning temperature of 260 ° C. using a spinner having a discharge hole diameter of 0.3 mm at a spinning take-up speed of 1800 m / min to obtain an undrawn yarn. Was. After drawing the undrawn yarn, a constant-length dry heat treatment at 200 ° C. for 3 minutes is performed, and mechanical crimping by an indentation method is applied,
Cut, 2 denier, 51mm, 13% crimp PPT
Short fibers were obtained. The short fiber had a 10% elongation elastic recovery of 96% and a flex recovery of 10% after 90 minutes as good as 90%, and had properties such as sports use as spun yarn and excellent resilience as wadding. .

Comparative Example 1 The same operation as in Example 1 was performed except that the heat treatment was not performed.
PPT short fibers having a denier of 51 mm and a crimp degree of 15% were obtained.

This short fiber has a 10% elongation elastic recovery of 86.
%, The flex recovery rate after 10 minutes was 78%, which was inferior to the PPT short fiber of the present invention, and inferior in stretchability as a fabric and restorability as wadding.

[0028]

The PPT staple fiber obtained by the present invention has high elongation elasticity recovery property and flexural recovery property, and the inner and sports clothing made of spun yarn using the yarn have excellent stretchability. In addition, it has a dry touch texture, high color fastness and light fastness. In addition to being suitable for comfortable bedding such as sheets, futon covers, and stuffed cotton, it is suitable for nonwoven fabrics for comfortable interlining, etc., and is highly practical.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // D04H 1/06 D04H 1/06 Z

Claims (4)

[Claims] 1. A fiber consisting essentially of polypropylene terephthalate, having a 10% elongation elastic recovery of 90% or more, a flex recovery of 80% or more, and a fiber length of 3%.
A polypropylene terephthalate staple fiber having a size of from 200 to 200 mm and a degree of crimp of from 5 to 35%. 2. The method according to claim 1, wherein after the fiber substantially composed of polypropylene terephthalate is heat-treated, a crimp having a degree of crimp of 5 to 35% is applied and the fiber length is cut to a length of 3 to 200 mm. A method for producing polypropylene terephthalate short fibers. 3. The method for producing polypropylene terephthalate short fibers according to claim 2, wherein the heat treatment is a wet heat treatment at a temperature of 100 to 160 ° C. for a time of 0.01 to 90 minutes. 4. The method for producing polypropylene terephthalate short fibers according to claim 2, wherein the heat treatment is a dry heat treatment at a temperature of 100 to 300 ° C. for a time of 0.01 to 20 minutes.