JPH03113070A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To obtain a fiber having grooved fiber surface and wool-like feeling by producing a conjugate fiber having a sheath composed of a polymer produced by adding a specific glycol to a polyester containing a specific acid component and a core component composed of a common polyester and thinning the conju gate fiber with an alkali. CONSTITUTION:The conjugate fiber to be used as the starting material contains (A) a sheath component composed of a polymer produced by adding 0.5-3 pts.wt. of a polyalkylene glycol having a molecular weight of 1,000-20,000 to 100 pts.wt. of a polyester containing 2.5-7.5mol% (based on the total acid component) of a 5-alkali metal sulfoisophthalate at a ratio (A:B) of 1:4 to 4:1. The fiber is treated with an aqueous solution of preferably potassium hydroxide until >=3wt.% of the fiber is dissolved to effect the thinning treatment of the fiber and obtain a polyester fiber having grooved fiber-surface structure crossing the fiber axis at right angle. The woven or knit fabric of the fiber is resistant to the slippage of the fiber and has a wool-like soft feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention relates to a method for producing polyester fibers, and more particularly, to polyester fibers having a grooved fiber surface structure perpendicular to the fiber axis and similar to low-density woven wool. The present invention relates to a method for producing polyester fibers that have a wool-like feel without yarn slipping even under loose weaving and knitting standards.

b. Prior Art Polyester fibers have many excellent properties and are therefore widely used as synthetic fibers. However, compared to natural fibers such as wool, polyester has a flat fiber surface and a low coefficient of friction, so even if it is made to a standard with a loosely woven fabric such as wool Etermin or Viera, the threads will still remain inside the fabric. It can easily slip and cause misalignment.

For this reason, there are considerable limitations when specifying standards for woven and knitted materials.

In particular, it was difficult to produce those with a low degree of weave.

Therefore, there were drawbacks such as a hard texture.

Studies have been made to create a structure similar to wool scale on the surface of polyester fibers, but this is still completely unsatisfactory.

Furthermore, attempts to roughen the surface of polyester fibers were made, for example, in Japanese Patent Publication No. 11709/1983. Special Public Service No. 59-24233
It is known for such things. The former is surface roughening caused by plasma, and although a rough surface can be formed on the surface of the fibers existing on the surface of the fabric, a rough surface is not formed on the surface of the fibers existing inside the fabric. Since a rough surface is not formed near the contact points where the two intersect, the effect of suppressing thread slippage in the fabric is very poor. The latter is a method in which polyester fibers containing fine particles are treated with an alkali to elute the fine particles and polyester at the same time, forming a rough surface.
In this case, a fine roughened structure can naturally be formed on the entire surface of the fiber. However, the order of the roughened structure is too fine, resulting in a satin effect, and there is almost no effect of increasing the coefficient of friction '1fit.

Also known is a method of forming a rough surface by incorporating polyethylene glycol into polyester and treating it with an alkali. However, in this case, polyethylene glycol 2>f is dispersed in the polyester fiber in a streak-like manner oriented in the fiber direction, and the fiber surface after alkali treatment is only streaked along the fiber axis. This streak-like unevenness along the fiber axis has no effect at all in suppressing the movement of the yarn due to slip at the intersection of the warp and weft yarns.

Also, as described in Japanese Patent Application Laid-Open No. 1158-169512 (technique for improving color development and imparting building resistance by using a rough surface structure having a ring-shaped eroded area, or Japanese Patent Application Laid-Open No. 61-10241)
There are techniques for imparting opacity through a rough surface structure with bases and valleys, as shown in No. 5, but even with these roughened surfaces, the coefficient of friction is not high enough to create a loose woven or knitted fabric like wool.

In this way, various roughened fibers have been investigated in order to create loosely woven or knitted fabrics such as wool, but their effects have been quite unsatisfactory.

C1 Problems to be Solved by the Invention The present invention aims to provide a polyester fiber that does not cause thread slip even in loose fabrics such as wool and has a texture similar to wool.

61 Means for solving the problem, that is, the present invention, is based on "100 parts by weight of a polyester containing a 5-alkali metal sulfoisophthalic acid component as 2,5 to 7,5 moles of 96 constituent units.
Contains 0.5 to 3.0 parts by weight of 00 polyalkylene glycol, *! The sheath component is J-mer, the polyester fiber is used as the middle component, and the ratio of the sheath component to the core component is 1=4 to 4:
1. A method for producing polyester fiber, which comprises treating the composite fiber referred to in No. 1 with an aqueous solution of an alkaline compound to elute 3% by weight or more thereof. ”.

The polyester used in the present invention contains terephthalic acid as a main acid component and at least one type of glycol.

Preferably, polyesters whose main glycol component is at least one kind of fullylene glycol selected from ethylene glycol, triethylene glycol, and tetramethylene glycol are targeted.

In addition, a polyester in which a part of the terephthalic acid component is replaced with another difunctional acid component may also be used.
It may also be a polyester in which a part of the glycol component is replaced with the above-mentioned glycol other than the main component or another diol component.

Examples of difunctional carboxylic acids other than terephthalic acid used here include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, β-hydroxyethoxybenzoic acid, p-oxybenzoic acid M, 5 -Aromatic, aliphatic, and alicyclic difunctional carbonic acids such as sodium sulfoisophthalic acid, adipic acid, sebacic acid, and 1,4-cyclohexanedicarboxylic acid. Examples of diol compounds other than the above-mentioned glycols include cyclohexane-1,
Examples include aliphatic, alicyclic, and aromatic diol compounds such as 4-dimetatool, neopentyl glycol, bisphenol A, and bisphenol S, and polyoxyalkylene glycols.

Furthermore, polycarboxylic acids such as trimellitic acid and pyromellitic acid, and polyols such as glycerin and trimethylolpropane pentaerythritol may be used as long as the polyester is substantially linear.

Such polyesters may be synthesized by any method. For example, when explaining polyethylene terephthalate, it is usually a direct esterification reaction between terephthalic acid and ethylene glycol, a transesterification reaction between a lower alkyl ester of terephthalic acid such as dimethyl terephthalate and ethylene glycol, or a transesterification reaction between terephthalic acid and ethylene glycol. The first step is to react an acid with ethylene oxide to produce a glycol ester of terephthalic acid and/or its low polymer, and the reaction product of the first step is heated under reduced pressure to achieve the desired degree of polymerization. It is produced by a second step of polycondensation reaction until it becomes .

Among the compounds used as the 5-alkali metal sulfoisophthalic acid component, particularly preferred examples include 3
, 5-di(carbomethoxy)benzenesulfonate (or potassium or lithium), 3,5-di(ethoxycarbonylphbenzenesulfonate (or potassium or lithium) in β-hydro),
3.5-di(β-human p-xybutoxybutylenebenzene sulfonate, sodium (or potassium or lithium), etc.).

In order to produce a copolymerized polyester obtained by copolymerizing such a 5-alkali metal sulfoisophthalic acid component, the process may be carried out at any stage before the synthesis of the polyester described above is completed, preferably at any stage before the first stage reaction is completed. It is preferable to add the above-mentioned 5-alkali metal sulfoisophthalic acid compound at the step.

At this time, it is preferable to use a weak acid salt of an alkali metal such as sodium acetate or sodium carbonate as an ether formation inhibitor.

The polyalkylene glycol used in the present invention includes polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., and random or block copolymers of two or more of these, and even if these are copolymerized into polyester. , or those which have lost their copolymerizability due to terminal blocking may also be used.

An antioxidant may also be used in combination with the polyalkylene glycol. As these antioxidants, hindered phenol-based antioxidants are preferably used, but it is also preferable to use other types of antioxidants, such as phosphite-based antioxidants. Examples of hindered phenol antioxidants include octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propione), 1,6-hexanesiol bis-3-L3,5-
di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis (3-(
3,5-di-tert-butyl-4-hydroxyphenyl) propionate], but is not limited thereto. Examples of the phosphite type include, but are not limited to, bisstearyl-pentaerythritol di-phosphite and tris-(nonylphenyl)-phosphite.

The method of adding the polyalkylene glycol and antioxidant can be arbitrarily selected at any stage from the start of synthesis to the spinning of the polymer. It is more preferable to inject the polyalkylene glycol into the piping from the extruder to the spinning head during spinning, and it is even more preferable to mix and spin using a static mixer. However, if the polyalkylene glycol is not actively mixed with the polyester. In case of polymerization,
Needless to say, it must be added during polymer synthesis. It is preferable that the polyalkylene glycol and the antioxidant are mixed and added at the same time. It goes without saying that it is preferable to sufficiently dry and deoxidize the material before adding it.

The sheath component polymer used in the present invention includes:

5-Alkali metal sulfoisophthalic acid component: 2.5 to 7
A polymer containing 0.3 to 3.0 parts by weight of polyalkylene glycol having a molecular weight of 1,000 to 20,000 per 100]i parts of the polyester contained as a 5 mol% structural unit is desirable.

If the 5-alkali metal sulfoisophthalic acid component is less than 2.5 mol%, the fiber surface after treatment with an aqueous alkali compound becomes streaked along the fiber axis, reducing the effect of the present invention. The thickening effect during melting is large, making it difficult to form composite fibers during spinning.

The cost will be high. Preferably 4.5 mol% to 5.
It is 5 mol%.

When the molecular weight of polyalkylene glycol is less than 100, compatibility with polyester is too good and a rough surface structure is difficult to develop. Also, if the molecular weight exceeds 20,000, the heat resistance of the polyalkylene glycol itself.

It is unfavorable because the light resistance is low.

The amount of polyalkylene glycol added to Zara is 0.
．． If it is less than 3 parts by weight, it will be difficult to develop a rough surface structure after treatment with an alkali compound, and if it exceeds 3 parts by weight, the optical properties will deteriorate, which is not desirable. Preferably it is 1.5 parts by weight to 2.5 parts by weight.

Further, the ratio of the core component to the sheath component is preferably 4 to 4:1.

If the proportion of the core component is less than 20% by weight, the processing efficiency of spinning, drawing, etc. of the composite fiber will be seriously deteriorated.

If the core component exceeds 80% by weight, the sheath component will be completely eluted and removed as the weight reduction treatment with an aqueous alkali compound solution progresses, resulting in the disadvantage that the rough surface structure formed on the fiber surface becomes unclear. Preferably, the ratio is approximately 1:2 to 2:1.

The spinning method in the present invention can be any arbitrary method, and the key is to form a core-sheath composite fiber, and the spinning speed etc. should be arbitrarily selected depending on the purpose. Further, it may be circular, have an irregular cross section, have one core, or have multiple cores. Even if the raw yarn obtained by spinning is drawn and then false twisted,
Alternatively, a method may be used in which the fibers are drawn and false-twisted using a draw-false-twisting machine, or a method in which the fibers are spun at high speed and the drawing is omitted and false-twisted is performed.

In order to form a structure on the surface of the polyester composite fiber obtained in this way, it may be subjected to stretching heat treatment or false twisting as necessary, or may be further processed into a woven or knitted fabric. This can be easily carried out by treatment with an aqueous solution of the compound.

Examples of the alkali compound used here include sodium hydroxide, potassium hydroxide, sodium tetramethylammonium hydroxide dicarbonate, potassium carbonate, and the like. Among these, sodium hydroxide and potassium hydroxide are particularly preferred. Further, alkaline weight loss accelerators such as cetyltrimethylanthenium bromide, lauryldimethylbenzylammonium chloride, etc. can be used as appropriate.

The concentration of the aqueous solution of the alkali compound varies depending on the type of alkali compound, treatment method, etc., but is usually 0.01 to
It is carried out in the range of 40ffijt%, especially 0.1 to 30%.
A range of % is preferred. The treatment temperature is usually in the range of room temperature to 160°C, and the treatment time is usually in the range of 30 seconds to 4 hours.

The amount reduced by treatment with the aqueous solution of the alkali compound is 3% or more by weight based on the weight of the fiber. 3
If the weight loss is less than % by weight, a satisfactory fiber surface structure will not be formed.

Note that the step of the alkali weight loss treatment described above may be performed independently as a single step, or may be performed in combination with other steps. In the latter case, washing of the dye and alkali reduction may be carried out simultaneously, for example in a reduction washing step or a sorbing step after dyeing with a disperse dye and/or a cationic dye.

The cause of the roughening of the fiber surface formed after treatment with an aqueous solution of an alkali compound is still not fully understood. The surface roughening form differs slightly depending on the spinning conditions, drawing conditions, false twisting conditions, etc., and if drawing is carried out within a short period of time immediately after spinning, the structure may not be developed (or even the spun yarn may be We believe that this is a phenomenon that is closely related to changes over time, as there is little structural development even when the material is stretched after being stored at low temperatures.

The environment in which the structure is likely to develop is that the spinning atoms are heated at 25°C.
From the viewpoint of reproducibility or structure development, it is preferable to stretch or in-draw within 96 hours after leaving the film at a relative humidity of 65% for 72 hours, but this is not necessarily limited. In addition, the reason why groove-like recesses are formed in the direction perpendicular to the fiber axis is that the sheath component has inferior stretchability and indrawability compared to the core component. It is thought that cracks occur in the direction of the fibers, and that the cracks are preferentially eluted by the aqueous solution of the alkaline compound, resulting in the formation of a groove-like structure perpendicular to the fiber axis. Copolymerization of 5-alkali metal sulfoiphthalic acid and addition of polyalkylene glycol are considered to be effective as components that quickly accelerate changes over time.

Generally speaking, the yarn cross-sectional shape of the core-sheath composite yarn of the present invention is not limited to a round shape, but conventionally considered irregular shapes such as triangular, triangular, T-shaped, oblate, and dock pawn can also be used.

Note that the polyester fiber of the present invention may contain optional additives 1, such as catalysts and color inhibitors, if necessary.

Heat resistant agent, heat retardant, optical brightener, erasing agent 1 coloring agent.

Titanium oxide may contain no particulates, etc.

A matting agent such as barium sulfate may also be used in combination.

The rough surface structure formed on the fiber surface by these configurations becomes more pronounced as the 5-alkali metal sulfoiphthalic acid component increases, as the amount of polyalkylene glycol added increases, and as the alkali weight loss rate increases up to 35% by weight. A sharp groove-like structure is formed. The length of the groove in the fiber circumferential direction is mostly 0.2 to 10 μm, and the width of the groove in the fiber axial direction is mostly 0.05 to 1 μm. The number of grooves is 5 to 100 in a 10μ square. Under conditions where the structure becomes clear, the length of the groove in the circumferential direction and the width in the fiber axis direction are roughly expanded from the above ranges.

The present invention will be briefly described below with reference to Examples.

Example 1 5-sodium sulfoisophthalic acid was polymerized in an amount of 5 mol% based on the total acid components, and the molecule fHtooo was heated to 120°C to form polyethylene terephthalate with an intrinsic viscosity of 0.45.
2 parts by weight of polyethylene glycol were added thereto, mixed with stirring, and extruded into water to form chips.

This polymer was used as a sheath component, and polyethylene terephthalate with an intrinsic viscosity of 0.64 was used as a core component, using a concentric core-sheath composite spinning device at a spinning temperature of 290°C so that the ratio of the core component to the sheath component was 1=1. Melt-spun at 25℃, 6
After being left at 5RH% for 72 hours, the stretching ratio was 3.
It was stretched 5 times to obtain a composite fiber of 75 denier/24 filaments.

This composite fiber was woven into a plain weave fabric with a basis weight of 60 y/rd.

After refining and presetting according to the usual method, 40 g/7? Treated at 95°C in an aqueous sodium hydroxide solution with a weight loss rate of 20
% fabric was obtained.

When the fiber surface of this fabric was observed with a scanning electron microscope at 5000x magnification, the length in the circumferential direction perpendicular to the fiber axis was 0.5μ.
There were about 50 groove-like structures in a 10-μ square area with a width of about 0.1-0.4 μ in the fiber axis direction.

Also, both warp and weft yarns are 25% higher than the average weaving standard density.
Despite the low weave density, the fabric after 20% alkali weight loss had no slippage at all, and its texture was soft and felt crisp. When this rough fabric was treated with a common fabric softener, it had the texture of loose wool fabric.

Of course, as mentioned above, if regular polyester is made with this weaving standard, it will have severe slippage, and the fabric will be too thick to be used.

Example 2 Using the combination of polymers used in Example 1, two types of concentric core-sheath composite yarns were collected by changing the spinning speed. 6 at 20℃
After standing at 5RH% for 80 hours, these two types of yarns were subjected to indoor a-false twisting while being stretched to 1.6 times at a heater temperature of 170°C to obtain structured yarns having yarn length differences. This structured yarn was twisted a total of 300 times/meter to weave a fill fabric with a weave standard that was softer than the standard polyester standard, and processed in the same manner as in Example 1.

When the fiber surface of this fabric was observed using a scanning electron microscope with a magnification of 5000 times, the length of the fiber in the circumferential direction was 0.2 to 10 μm.

Approximately 30 groove-like structures having a width of 0.1 to 1 μm in the fiber axis direction were present in a 10 μm square. In addition, there was no occurrence of sagging, etc., even though the weave density was 20% lower than the conventional standard for both warp and weft yarns, and the fabric had a soft texture with a crisp feel. When a texture modifier used in wool fabrics was applied to the sara, it became a soft, slimy texture unique to wool.

Comparative Example 1 A woven fabric produced in exactly the same manner as in Example 2 except that 2 mol% of 5-sodium sulfoisophthalic acid was polymerized based on the total acid component and polyethylene terephthalate having an intrinsic viscosity of 0.49 was used. The surface structure was unclear and slippage occurred.

Comparative Example 2 A trial production was carried out in the same manner as in Example 2 except that the amount of polyethylene glycol added was 4 parts by weight (7 parts by weight).

Although the texture of this fabric was similar to that of Example 2, the light fastness after dyeing with a cationic dye was insufficient at 2-3 grade.

Claims (1)

[Claims] 5-Alkali metal sulfoisophthalic acid component: 2.5 to 7
．． A polymer containing 0.5 to 3.0 parts by weight of polyalkylene glycol with a molecular weight of 1,000 to 20,000 in 100 parts by weight of polyester containing 5 mol% as a constituent unit is used as a sheath component, polyester is used as a core component, and the ratio of the sheath component to the core component A method for producing polyester fibers, which comprises treating a composite fiber with a ratio of 1:4 to 4:1 with an aqueous solution of an alkaline compound to elute 3% by weight or more.