JP4943771B2 - Polyester staple fiber - Google Patents

Description

  The present invention relates to a polytrimethylene terephthalate polyester short fiber.

  Polytrimethylene terephthalate polyester staple fiber maintains the excellent dimensional stability, light resistance, low moisture absorption, and heat setting properties that are inherent to polyester, and is excellent in low elastic modulus, elastic recovery rate, and easy dyeability. The production technology of polytrimethylene terephthalate polyester short fibers has been studied from various angles with the aim of putting them into practical use for stuffed cotton, non-woven fabrics, spun yarn fabrics and the like.

  Patent Document 1 (Japanese Patent Laid-Open No. 11-189938) proposes a polytrimethylene terephthalate short fiber having a crimp that defines an elongation elastic recovery rate, a bending recovery rate, and the like. The short fiber is made of polyethylene terephthalate. Compared to the crimped fibers, the settling resistance is improved.

However, in the process of passing through the card, the crimps of the crimped fibers are stretched and lost. With such a fiber, if the card spinning speed is increased in order to increase productivity, the sliver breaks, the web droops, the process becomes defective, and it is impossible to obtain a high-quality spun yarn. is there.
JP-A-11-189938

  The present invention provides a polytrimethylene terephthalate polyester short fiber having excellent crimping performance that does not cause sliver breakage or web drooping in a high-speed card having a sliver spinning speed of 120 m / min or more. It is in.

The present invention comprises a polytrimethylene terephthalate polyester, has a fiber length of 3 to 200 mm, a primary crimp number of 10 to 30 peaks / 25 mm, and a crimp degree of 10 to 25%. The rate is 80% or more, and the primary crimp number X and the secondary crimp number Y shown in FIGS. 1A and 1B satisfy all the following expressions (1) to (2) at the same time. It is related with the polyester short fiber characterized.
50 ≦ (X + 20Y) ≦ 80 (1)
10 ≦ X ≦ 30 (2)

  The polytrimethylene terephthalate-based polyester short fiber having secondary crimp of the present invention does not cause sliver breakage or web dripping in a high-speed card, and can improve productivity and obtain a high-quality spun yarn. It becomes possible.

  The polytrimethylene terephthalate-based polyester referred to in the present invention is a polyester having a trimethylene terephthalate unit as a main repeating unit and does not impair the object of the present invention, for example, 15 mol% or less based on the acid component, preferably Polyester obtained by copolymerizing the third component at 5 mol% or less may be used.

  As the third component preferably used, for example, acid components such as isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, metal sulfoisophthalic acid, 1,4-butanediol, 1,6 hexanediol Various components such as glycol components such as cyclohexanediol and cyclohexanedimethanol can be used, and may be appropriately used in consideration of spinnability and the like.

  The polytrimethylene terephthalate polyester used in the present invention preferably has an intrinsic viscosity (o-chlorophenol, 35 ° C.) of 0.7 to 1.3 dL / g, more preferably 0.8 to 1.2 dL / g. It is a range. When the intrinsic viscosity is less than 0.7 dL / g, the mechanical strength of the finally obtained fiber becomes insufficient. On the other hand, when it exceeds 1.3 dL / g, the handleability is lowered, which is not preferable.

  In addition, the polyester used in the present invention has various additives as necessary, for example, matting agents, heat stabilizers, antifoaming agents, color modifiers, flame retardants, antioxidants, ultraviolet absorbers, An infrared absorber, a fluorescent brightening agent, a coloring pigment, and the like can be added as necessary.

  The polyester short fiber of the present invention is required to have a fiber length of 3 to 200 mm, and more preferably 10 to 150 mm. Polytrimethylene terephthalate-based polyester short fibers may come off slightly from the fiber ends in the course of high-order processing, and if the fiber length is short, the rate of coming out is undesirably high. On the other hand, when the length is too long, the processability including the spinning process becomes poor, which is not preferable.

  In the present invention, the crimped polyester short fiber of the present invention is not only a crimped short fiber composed of the above-mentioned polytrimethylene terephthalate-based polyester, but the fiber satisfies the number of crimps and the degree of crimp described below. It is important to have a two-dimensional crimp and that the crimp elastic modulus simultaneously satisfies the requirements described later. Thereby, it is possible to obtain a polytrimethylene terephthalate-based polyester raw cotton having good high-speed card passing properties and excellent crimp-proof set resistance.

That is, the polyester staple fiber of the present invention needs to have a primary crimp number of 10 to 30 peaks / 25 mm, and more preferably 15 to 25 peaks / 25 mm. If the number of crimps is less than 10 peaks / 25 mm, the entanglement between the fibers is low, and the web is easily cut. On the other hand, if the number of crimps exceeds 30 peaks / 25 mm, the entanglement between the fibers becomes too high, and the card passing property is deteriorated and nep and slab are frequently generated.
The number of primary crimps can be easily adjusted by changing the stuffing pressure of the crimper box.

Moreover, the crimp degree of the polyester staple fiber of this invention needs to be 10-25%, and it is more preferable that it is 13-20%. If the degree of crimp is less than 10%, the entanglement between the fibers is low, the card passing property is deteriorated, and sufficient bulkiness cannot be obtained. On the other hand, if the degree of crimp exceeds 25%, the entanglement property becomes too high, and not only the entanglement occurs but the card passing property is lowered, and the obtained web and spun yarn are not uniform.
This crimping degree can be easily adjusted by changing the stuffing pressure of the crimper box or changing the thread temperature (tow temperature) entering the crimper box.

Furthermore, the crimped elastic modulus of the polyester short fiber of the present invention needs to be 80% or more, and preferably 85% or more. The closer to 100%, the less the settling of the crimp and the better the cardability. When the crimp elastic modulus is less than 80%, the crimp sag is large, so the card passing property is extremely poor, it is easy to wind up on the cylinder and the roller, there is a lot of cotton falling, and the web is broken. . As a result, productivity is extremely low and the quality of the sliver to be spun is insufficient. In addition, the settling resistance of the raw cotton is significantly reduced. In particular, trimethylene terephthalate-based polyester fiber has a lower modulus and lower crystallinity than polyethylene terephthalate fiber.
This crimped elastic modulus can be increased by cooling as soon as possible after crimping.

Specifically, the polyester staple fiber of the present invention has two frequencies having a frequency in the range of 8 mm to 13 mm overlapping with the primary crimp in addition to the primary crimp having a frequency in the range of 0.7 mm to 2.5 mm. Has next crimp. The number of secondary crimps is preferably 1 to 4 peaks / 25 mm, and more preferably 2 to 3 peaks / 25 mm. The polyester staple fibers of the present invention having secondary crimps have good card passability because primary crimps are sufficiently retained in the process of opening the fibers with a card.
That is, the polyester staple fiber of the present invention has a high degree of secondary crimp, and the primary crimp number X and the secondary crimp number Y shown in FIGS. It is necessary to satisfy all of (2) at the same time.
50 ≦ (X + 20Y) ≦ 80 (1)
10 ≦ X ≦ 30 (2)

  Here, in the above formula (1), when (X + 20Y) is less than 50, when the raw cotton is spread and applied to the card, primary crimps are stretched at the stage of opening, and as a result, the degree of entanglement of the web is Since it becomes small and a web break occurs, it is not preferable. On the contrary, if (X + 20Y) exceeds 80, the entanglement between the fibers is too strong at the stage of opening, which is not preferable because it does not pass through the opening process and becomes a pill. This (X + 20Y) can be adjusted by the distance between the doctor blades of the crimper box, the filament temperature (tow temperature) when crimping, and the stuffing pressure.

  As described above, in the above formula (2), when X is less than 10, the web is not connected and the card passing property is poor. On the other hand, if X exceeds 30, the entanglement between the fibers is too strong, and a nep is generated at the time of sliver creation, which is not suitable. In order to make X into the range of 10-30, it can set by adjusting the tow temperature which enters into a crimper box, and the stuffing pressure of a crimper box suitably.

  The polyester short fiber of the present invention has a strength of preferably 2.5 to 3.5 cN / dtex, more preferably 2.6 to 3.4 cN / dtex, and an elongation of preferably 40 to 80%, More preferably, it is 50 to 70%. If the strength is less than 2.5 cN / dtex, the strength as spun yarn or nonwoven fabric is not obtained, which is not suitable. On the other hand, when it exceeds 3.5 cN / dtex, the fiber becomes hard and the texture which is the goodness of the polytrimethylene terephthalate fiber is lost. If the elongation is less than 40%, the texture and stretchability of spun yarn and nonwoven fabric cannot be exhibited. On the other hand, if the elongation exceeds 80%, the strength of the polytrimethylene terephthalate fiber that should originally be reduced is lowered. It is not practical. Both the strength and elongation can be easily adjusted by adjusting the draw ratio.

The crimped polyester staple fiber of the present invention described above can be produced, for example, by the following method.
That is, a polytrimethylene terephthalate-based polymer is melted, and a cooling airflow having a flow velocity of 1.0 m / second or more is blown onto the yarn immediately after being discharged from the die surface, and taken up at 350 to 2,500 m / min. Thus, an undrawn yarn is obtained. Next, the undrawn yarn is more preferably stretched in two steps with warm water at 50 to 95 ° C. and stretched 1.2 to 3.5 times. Next, the tow preheated to 65 to 90 ° C. is crimped with a crimper and cut into short fibers to obtain crimped short fibers excellent in card passage.

  Here, in order to impart crimp to the polyester short fiber of the present invention, it is necessary to set the tow temperature entering the indentation type crimper (hereinafter referred to as a crimper) to 65 ° C. to 90 ° C., more preferably. 70 ° C to 85 ° C. If the tow temperature is less than 65 ° C., sufficient secondary crimp cannot be imparted. On the other hand, if it exceeds 90 ° C., secondary crimping can be imparted, but it is not suitable because the primary crimp exceeds 30 peaks / 25 mm.

  In the present invention, it is not preferable to heat-treat the drawn yarn after drawing and before crimping. The heat treatment makes it difficult to crimp the drawn yarn. For this reason, the entanglement property of the obtained short fiber falls, process passability becomes unsatisfactory.

Examples are given below in order to make the constitution and effects of the present invention more specific, but the present invention is not limited to these Examples.
In addition, each value in an Example was calculated | required according to the following method.
1) Intrinsic Viscosity An orthochlorophenol solution having a temperature of 35 ° C. was used and determined according to a conventional method.
2) Fineness, fiber length, number of crimps, crimp rate, crimp elastic modulus Measured according to the method described in JIS-L1015.
3) Measurement of primary crimp number X and secondary crimp number Y X was measured according to JIS-L1015 as described above. Since Y may not be stretched when a load is applied, Y must be measured with no load. Specifically, a shell pillar-shaped unopened portion was taken out from the raw cotton, and the number of peaks a (mountain / 25 mm) was measured without applying a load. The recognition as a mountain was based on the primary crimp measurement method. From the average fiber length b (mm) of the unopened part, the secondary crimp number Y was calculated with the number of samples n = 10 using the calculation formula shown below.
Y = 25a / b

[Example 1]
Polytrimethylene terephthalate (inherent viscosity 0.92 dL / g, melting point 228 ° C.) was melted at 260 ° C. and discharged from a known solid round cross-section spinneret (840 holes) at a discharge rate of 600 to 700 g / min. An undrawn yarn was obtained at a winding speed of 1,300 m / min by blowing cooling air of 25 to 30 ° C. at a flow rate of 4.5 m / sec at a position 4 cm below the base surface. Next, the obtained undrawn yarn was drawn 1.7 to 2.5 times by a two-stage hot water drawing method of 50 ° C. × 90 ° C. so that it becomes a 500,000 dtex tow after drawing. The drawn yarn is heated to 65 to 90 ° C., crimped by a crimper, cut to a fiber length of 64 to 89 mm, and the obtained crimped cotton is passed through a card with a sliver spinning speed of 120 m / min. Evaluated.

[Example 2]
The same operation as in Example 1 was performed except that the temperature for heating the drawn yarn was 75 ° C.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the temperature at which the drawn yarn was heated was 60 ° C.

[Comparative Example 2]
After drawing by 1.7 to 2.5 times by a two-stage hot water drawing method of 50 ° C. × 90 ° C., the drawn yarn was heat-treated at 130 ° C. with a heat roller, and the temperature at which the drawn yarn was heated was 90 ° C. Except for this, the same operation as in Example 1 was performed.
The results are shown in Table 1.

  The polyester short fiber of the present invention is a polytrimethylene terephthalate-based polyester short fiber having secondary crimp that does not cause sliver breakage or web drooping in a high-speed card. Since it is possible to obtain a yarn, it is particularly useful for improving the quality of woven fabrics and knitted fabrics.

It is a model figure which shows the crimp of the polytrimethylene terephthalate polyester short fiber of this invention, (a) shows the primary crimp of the polyester short fiber, (b) shows the secondary crimp of the polyester short fiber. Show.

Claims (6)

It is made of polytrimethylene terephthalate polyester, has a fiber length of 3 to 200 mm, a primary crimp number of 10 to 30 crests / 25 mm, a crimp of 10 to 18.3 %, and has a crimp elastic modulus. 80% or more, and the primary crimp number X and the secondary crimp number Y shown in FIGS. 1A and 1B satisfy all the following expressions (1) to (2) at the same time. Polyester short fiber.
50 ≦ (X + 20Y) ≦ 80 (1)
10 ≦ X ≦ 30 (2)
Here, the primary crimp number X and the secondary crimp number Y are values measured as follows.
Primary crimp number X: measured in accordance with JIS-L1015.
Secondary crimped number Y: Take out the unopened portion of the scallop from raw cotton and measure the number of peaks a (mountain / 25 mm) without applying a load. From the average fiber length b (mm) of the unopened portion The secondary crimp number Y was calculated with the number of samples n = 10 using the calculation formula shown below.
Y = 25a / b   The polyester staple fiber according to claim 1, wherein the single yarn fineness is 1.0 to 7.0 dtex or less.   The polyester short fiber according to claim 1 or 2, wherein the intrinsic viscosity measured at 35 ° C in an o-chlorophenol solution is 0.7 to 1.3 dL / g.   The polyester short fiber according to any one of claims 1 to 3, which has a strength of 2.5 to 3.5 cN / dtex and an elongation of 40 to 80%. The primary crimp has a frequency in the range of 0.7 mm to 2.5 mm, and the secondary crimp has a frequency in the range of 8 mm to 13 mm, overlapping the primary crimp. Polyester short fiber. The tow-type crimping machine is set to 65-90 ° C. before being entered into the indentation type crimping machine without heat-treating the drawn tow yarn made of polytrimethylene terephthalate-based polyester before crimping. The polyester staple fiber according to any one of claims 1 to 5, wherein crimps are imparted.