JPS5865010A - Polyester fiber - Google Patents

Abstract

PURPOSE:Polyester fiber that is composed of tetramethylene terephthalate units, has specific optical birefringence, density and X-ray diffraction intensity ratio, and shows a small dry heat shrinkage and high dimensional stability, thus giving woven or knitted fabrics with good touch and drapability. CONSTITUTION:A polyester substantially composed of tetramethylene terephthalate units is subjected to melt spinning at 260-290 deg.C and drawn to give the objective fiber with an optical birefringence (DELTAn) of higher than 125X10<-3>, a density (rho) of more than 1.310g/cm<3> and an intensity ratio of X-ray diffraction (I21.2/I23) of less than 0.3. Preferably the crystal size of this fiber is larger than 60Angstrom , its initial modulus is lower than 400kg/mm.<2> and the dry heat shrinkage is less than 13%, when it is treated at 180 deg.C for 20min.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyester fibers consisting essentially of polytetramethylene terephthalate, particularly fibers consisting of dry heat polytetramethylene terephthalate, which have been known for a long time, such as those disclosed in JP-A No. 48-22738. 2% 1977
-55916 publication, JP-A-49-55920 publication,
A specific method for producing the fiber is disclosed in JP-A-4I No. 51-64019 and the like. However, the polytetramethylene terephthalate fibers known so far, as described in JP-A No. 56-63066,
The dry heat shrinkage rate is extremely high, which causes major problems during heat setting in the finishing stage after knitting, making it extremely difficult to design fabrics with sufficient texture and drape properties, and making it difficult to design fabrics with sufficient texture and drape properties. This severely limited the scope of its use as a fiber.

The present inventor analyzed that the large dry heat shrinkage rate of such polytetramethylene terephthalate fibers is derived from its unique crystal structure, and found that In order to obtain a polytetramethylene terephthalate fiber having a dry heat shrinkage rate comparable to that of the fiber (fiber fathom), the present invention was achieved through extensive research.

That is, the present invention is made of a polyester consisting essentially of tetramethylene terephthalate units, and has a birefringence (Δ=125×10"-" or more and a density (ρ) of 1.s
1o (y/aI) or more, and the X-ray diffraction intensity ratio (■2□, 2/I23) is 0.3 or less.

In the present invention, "polyester consisting essentially of tetramethylene terephthalate units" means a polyester whose main component is a linear polyester obtained by condensing 1,4-butanediol and terefucuric acid, A copolymer mainly composed of polytetramethylene terephthalate, in which 15 moles or less of the salt component or acid component is replaced with another copolymerizable component. These polyesters may be blended with less than 15% by weight of molecular substances.Also, these polyesters may be supplemented with organic or inorganic substances such as flame retardants, pigments, fillers, etc.

It is known that polytetramethylene terephthalate has an α-type and a β-type crystal structure (Tadokoro st I
Ll, Macromolecules + Yu126
6 (1976)). It is thought that the α type consists of a methylene group having a fluorine formation of GGTGG, and the β type consists of TSTST, with the β type consisting of a fully extended main chain. On the other hand, @tomo of α type crystal is 1.404 (1
! At), the density of the / type crystal is 1.283 (g shoulder)
, and the amorphous density (ρa) is 1.27 to 1.28 (
C).

However, no research has yet been conducted to clarify the relationship between the crystal structure and the actual fiber manufacturing process. The present inventors have found that the unique shrinkage behavior of polytetramethylene terephthalate is related to the transformation of this crystal structure. (That is, conventional polytetramethylene ethylene terephthalate) LiEM has a large dry heat shrinkage rate because the molecular chains are stretched when subjected to large tension during the spinning process, especially the drawing process. In other words, the main component is β-type crystals, and in such a state, no matter how much heat treatment is performed, the molecular chains are not stabilized and the heat fixation effect is not enhanced. On the other hand, the birefringence (8n) is 125X1G or more, and the density (ρ) is 1.310.
(,9 shoulder) or more, X-ray diffraction intensity ratio (I2□, 2/”!3
) is 0.3 or less, that is, polytetramethylene terephthalate fibers that have undergone oriented crystallization to a certain extent and whose crystal structure contains α-type to a certain extent have a low It shows the dry heat shrinkage rate.

Gives the fiber mechanical properties that do not pose a practical problem,
In order to achieve oriented crystallization, the birefringence must be set to 125×10
It is necessary to do the above. In addition, in order to reduce the dry heat shrinkage rate V and improve dimensional stability, it is necessary to contain an α-type crystal structure, and therefore the density (ρ) must be 1
It is necessary to have a table of 310 (7/d) or more. If the density (ρ) is less than 1.310 (#/ci), the dry heat shrinkage rate of the fibers will be too large, making it impossible to obtain a fabric with good hand and drape properties through normal processing steps.

Fourth, X-ray diffraction intensity ratio ("21.27" 23)
must be 0.3 or less. The X-ray diffraction intensity ratio (■2□, 2/I23) is determined by the degree of crystal orientation, α structure, and β
It shows the content rate of the type structure, and when the β type is the main component, it is 05 or more, and when the α type and β type are mixed, the value is 0.3 to 05. In order to obtain the sufficient dimensional stability required by the present invention, it is necessary that it be 0.3 or less.

Polytetramethylene terephthalate fibers having the above-mentioned crystal structure have excellent dimensional stability and provide knitted fabrics with good hand and drape properties. Furthermore, if processed, it is extremely useful as a sacerary yarn.

Furthermore, the fiber of the present invention has a crystal size of go! or more, and the initial modulus is <ookg/- or less,
It is desirable to prevent roughness of the surface and improve drapability when used as a cloth. Further, in terms of improving dimensional stability, it is preferable that the dry heat shrinkage rate when dry heat treated at tSO° C. for 20 minutes is 13% or less.

In addition, the X-ray diffraction intensity ratio (■21.2/I
is the ratio of the X-ray diffraction intensity in the equatorial direction 23) at 2θ-21,2" and the X-ray diffraction intensity in the equatorial direction at 2θ-23", and for its measurement, The measurement conditions were 35 KV and 20 mA using a D-9C type X-ray diffractometer manufactured by Rigaku Corporation.

Cu-K (1 wire, Nl filter used, divergence slit 0.15 m, scattering slit 1", receiving slit 0.4 m.

Moreover, the density (ρ) was measured by the density gradient tube method.

On the other hand, the crystal size in the present invention is a value representing the size in the direction approximately perpendicular to the fiber axis of the crystal, and is determined from the (OIO) plane reflection peak half-width B from the X@ diffraction intensity curve in the equatorial direction. and apply this value to Scherrer's formula 1/(B-b
) was obtained by substituting it into aisθ.

In the above equation, b=o, o0204 radians.

K=0.94. λ=1.5421. θ is Black's angle.

The initial modulus is calculated using the following formula by performing a tensile test using an Instron tensile testing machine under the conditions of 20 scratches and a tensile speed of 20 inches per minute, reading the strength at 41% elongation within the elastic limit. did.

Initial + Shura X (k, /,) - Force JF)X &
l1cd X90, 01 Spinning temperature 260~290℃, spinning speed 4000 @ / lilυ, single yarn fineness 1.5~
What is necessary is just to spin it so that it may become 15De.

If the intrinsic viscosity [η] is outside the range of 0.6 to 1.0, the stringiness will decrease. On the other hand, if the spinning temperature is too low, the spinnability will decrease and single fiber breakage will easily occur, whereas if the spinning temperature is too high, the decrease in [η] will be large and the strength of the spun yarn will decrease, which is not desirable. Furthermore, setting the spinning speed to 4o00m/in or higher is extremely XL! and the spinning speed is 4000 @ / m
If the density (ρ) is less than 1.31o (Jl/cs
i) is smaller than "21.2/I23 is 0.
If it is larger than 3, the crystal structure of the present invention cannot be obtained. The crystal structure of the present invention cannot be obtained even when the single fiber fineness is outside the range of 1.5 to 15 De. If the fiber spun at a high speed of 4QOQ@/m or more is further drawn, the density (ρ) will decrease, making it impossible to obtain a fiber with a low dry heat shrinkage rate.

Furthermore, the fiber of the present invention has an intrinsic viscosity [η] of 0.6 to 1.0.
Spinning polytetramethylene terephthalate at a temperature of 260
After spinning at ~290°C and a spinning speed of 200 o@/m or higher to obtain a single fiber fineness of o~20 D@, the fibers are subsequently cold-stretched at a draw ratio of 1.1 to 19 times, and at the same time or later are stretched to a constant length. It can also be obtained by heat treatment or relaxation heat treatment.

In particular, the single yarn fineness should be i, o to 20De.

Setting the spinning speed to 2000 m'1 mJJ or more; 1.
Even if any of these conditions is not met, such as cold stretching to 1 to 19 times and heat treatment after cold stretching, it still contains a considerable amount of the α-type crystal structure of the present invention! Fibers with zi27 I23 of 0.3 or less cannot be obtained.

The polyester fiber obtained in this way, which consists essentially of polytetramethylene terephthalate units, does not have a high dry heat shrinkage rate, has excellent dimensional stability, and can be heat-set under normal conditions without causing any trouble. It is possible to provide a knitted fabric with good hand and drape properties. Further, by subjecting the yarn to a crimping process, it is possible to provide a useful sanitary yarn.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1-3. Comparative Examples 1 to 4 Polytetramethylene terephthalate having an intrinsic viscosity of 0.82 as measured in an 0-chlorophenol solution at 35°C was melt-spun at a temperature of 270°C and wound up at various spinning speeds.

On the other hand, for comparison, a yarn was also created which was taken off at a spinning speed of 1000@/a+ and then cold drawn at a magnification of 3.0 times (Comparative Example 4).

Next, a 32-gauge tricot...-7 texture knitted fabric was made using each of the obtained yarns, and its drapeability and texture were evaluated.

The characteristic values of each yarn and the evaluation results of the fabric are shown in the table below.

From these results, the birefringence (△n) is 125Xl0-3 or more, the density is 13s o (g/cd)), and the X-ray diffraction intensity ratio (■2□2/123) is 0.3 or less. The yarns of Examples 1 to 3 have excellent dimensional stability, and when made into woven fabrics,
Fabrics with excellent drapability and texture can be obtained, or if the density is s
, a 10 (jl/d) and the X-ray diffraction intensity ratio (12□, 2/■23) exceeds 0.3 in Comparative Example 1 and Comparative Example 4. and X-ray diffraction intensity ratio (!2□, 2/I23
) exceeds 0.3 in Comparative Example 2 and Comparative Example 3, Young's modulus,
*: It can be seen that both the heat shrinkage rate is high, and when it is made into a woven eyelid, the drapability and texture are poor.

Examples 4-9. Comparative Examples 5 to 14 Polytetramethylene prephthalate having an intrinsic viscosity of 085 as measured with a 0-polyprophenol solution at 35°C was spun at a spinning temperature of 270°C, and after cold stretching with a spindle, a length of 60C1 m was obtained. The fibers were heat-treated by being run in contact with a plate heater to obtain a yarn of 20 d/15 filaments. In this case, the spinning speed, 2~cold stretching ratio, heat treatment temperature, and heat treatment relaxation rate are shown in the following table! ? :Various changes were made as shown.

Next, a 32-gauge tricot half knitted fabric was made using each of the obtained yarns, and the drapability and texture were made monovalent in the same manner as in Examples 1 to 3.

The characteristic values of each yarn and the evaluation results are shown in the following table.

In addition, those with - written in the heat treatment temperature and heat treatment relaxation rate columns are those that were not heat treated, and the heat treatment relaxation rate -5 (h) means that they were heat treated at an elongation of 5%). .

From this result, it was found that the birefringence (△n) is 125X10° or more, the density is 1.31o (g/aJ) or more, and the X-ray diffraction intensity ratio (121,2/' I 23 ) is 0.3 or less. The yarns of Examples 4 to 9 have excellent dimensional stability, and when made into a woven fabric, a woven fabric with excellent drapability and feel can be obtained, but the density is less than 1.31o (jl/aj), and X-ray diffraction Comparative Examples 5 to 8 where the intensity ratio (I21.2/■23) exceeds 0.3. and X-ray diffraction intensity ratio (”21.2/!
It can be seen that Comparative Examples 9 to 14 in which 23') exceeds 03 have a low dry heat shrinkage rate, and when made into a fabric, the drapability and feel are poor.

Claims (1)

[Claims] 1. Consists of polyester consisting essentially of tetramethylene terephthalate units, and has a birefringence index (1\n) of 1.
25X10 or more, writing scale (,9) is 1, s 1o
(#/j) or more, and the X-ray diffraction intensity ratio (“21.
2. A polyester fiber characterized in that 2/"23) is 13 or less. 2. A polyester fiber according to claim 1, which has a crystal size of 60X or more and an initial modulus of 400 (kmj) or less. The polyester fiber according to claim 1 or 2, which has a dry heat shrinkage rate of 1 s% or less when subjected to dry heat treatment at 18.0°C for 20 minutes.