JP2001115335A - Moisture-absorbing polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polyester fibers that can develop a soft fabric hand and retains excellent moisture absorption by adjusting the alkali-reduction rate of the fiber in the practically untroublesome range and effecting uniform thinning treatment. SOLUTION: The objective polyester fiber is made of a poly(alkylene terephthalate) copolymers including the following subsidiary components, respective: 3-30 wt.% of a polyether or a polyether derivative of which solubility is <=30 wt.% in water at 20 deg.C; 0.5-3 mol.% of a sulfonate salt group-bearing compound; and 0.5-5 mol.% of dimmer acids based on the whole acid components, respectively. These polyester copolymer fibers have an alkali- reduction rate of <=1.5 wt.%/min. and the moisture absorption of >=4 wt.% under the atmosphere of 34 deg.C and 90% RH.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester fiber capable of exhibiting a soft touch and having excellent hygroscopicity.

[0002]

2. Description of the Related Art Polyester fibers, especially those mainly composed of polyethylene terephthalate (hereinafter abbreviated as PET), have high crystallinity and a high softening point, so that not only mechanical properties such as strength and elongation, but also It exhibits excellent properties such as heat resistance and chemical resistance, and is widely used in the field of industrial materials and clothing.

[0003] However, since polyester fibers are hydrophobic, they have extremely low hygroscopicity, so that they are used in the field where they are directly in contact with the skin or are worn close to the skin, such as innerwear, inner garments and sports clothing. When used, sweating from the skin causes stuffiness, stickiness, and the like, and is extremely inferior to natural fibers in terms of comfort, and its use in the field of clothing is greatly restricted.

Hitherto, various attempts have been made to impart hydrophilicity and hygroscopicity to polyester fibers. For example,
JP-A-62-267352 proposes a polyester composition containing 50 to 70% by weight of a polyalkylene glycol. However, the fiber made of such a composition has poor chemical resistance, and has a disadvantage that the rate of weight loss due to alkali is particularly high.

[0005] In general, polyester fibers exhibit a soft texture by being subjected to alkali weight reduction processing. However, in the case of a fiber whose weight loss rate due to alkali is high, uniform weight reduction processing is performed by controlling the weight loss rate. Therefore, there was a problem that fibers having a soft texture could not be obtained.

As means for solving such a problem, for example, Japanese Patent Application Laid-Open No. 2-99612 discloses that a core is formed of a hygroscopic polymer having a moisture absorption of 10% by weight or more at room temperature and a sheath is formed of polyester. Core-sheath type composite fibers have been proposed. However, in such fibers, the water-absorbing polymer in the core part swells greatly due to hot water during alkali weight reduction processing, causing cracks to occur on the surface of the composite fiber, and the core polymer, which has high water solubility, flows out to the outside. There was a problem of doing.

In Japanese Patent Application Laid-Open No. 9-228157, an intermediate layer of a hygroscopic polymer containing a polyether compound is compounded between an outer layer and an inner layer made of polyester, and a hollow three-dimensional structure having a hollow portion is provided. Layer conjugate fibers have been proposed. Such a fiber has a high solubility in water without causing cracks on the surface of the conjugate fiber due to deformation of the hollow portion even when the hygroscopic polymer in the intermediate layer swells due to hot water during alkali weight reduction processing. Since the polymer of the intermediate layer is prevented from flowing out, it is possible to perform a certain amount of alkali reduction processing. However, since the cross-sectional shape of the fiber is complicated, there is a problem in that the stability of the yarn production is inferior and the operability is significantly deteriorated.

[0008]

The object of the present invention is to solve the above-mentioned problems, to make the alkali weight loss rate of the fiber within a range where there is no practical problem, and to realize a soft texture by performing uniform weight loss processing. It is an object of the present invention to provide a polyester fiber which is capable of exhibiting excellent hygroscopicity.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention has a solubility in water of 20 ° C. of 30.
3% to 30% by weight of a polyether compound or a polyether compound derivative which is not more than 0.5% by weight, a sulfonic acid group-containing compound is 0.5 to 3% by mole based on the total acid component, and a dimer acid is 0.5% based on the total acid component. -5 mol%, each fiber comprising a copolymerized polyalkylene terephthalate, wherein the alkali weight loss rate is 1.5 wt% / min or less;
The present invention also provides a hygroscopic polyester fiber having a moisture absorption of 4% by weight or more in an atmosphere at a temperature of 34 ° C. and a humidity of 90% RH.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As the polyalkylene terephthalate forming the hygroscopic polyester fiber of the present invention, specifically, PET, polybutylene terephthalate, polypropylene terephthalate and the like are suitable. The polyalkylene terephthalate needs to contain 3 to 30% by weight of a polyether compound or a polyether compound derivative having a solubility in water at 20 ° C. of 30% by weight or less.

If the solubility of the polyether compound or the polyether compound derivative in water exceeds 30% by weight, this component tends to elute to the outside during alkali weight reduction processing, and as a result, the alkali weight loss of the polyester fiber containing the same. It is not preferable because the speed increases.

Examples of such polyether compounds or polyether compound derivatives include the following. For ordinary polyalkylene oxides, high molecular weight polyethylene glycol having an average molecular weight of 18000 or more is suitable. Those in which part or all of the terminal of the polyalkylene oxide is crosslinked by reacting with an isocyanate compound or the like are also preferable, and examples of commercially available products include "Aqua Coke" manufactured by Sumitomo Seika Co., Ltd. Polyetheresteramide comprising a polyether component and a polyamide component is also suitable, and as a commercially available product, "Pelestat" manufactured by Sanyo Chemical Industries, Ltd.
And the like. Also, a copolymer of propylene oxide and ethylene oxide having an average molecular weight of 9000 or more has low solubility in water and can be used in the present invention.However, in order not to impair the hygroscopicity, propylene oxide Those having a copolymerization ratio of 20 to 80 mol% are preferred.

When the content of the polyether compound or the polyether compound derivative is less than 3% by weight, sufficient hygroscopicity is not exhibited, and when the content exceeds 30% by weight, the degree of polymerization of the polyester is hardly increased, so that the fiber properties are not improved. And the operability is remarkably reduced.

The polyalkylene terephthalate forming the fiber of the present invention must have a sulfonic acid group-containing compound copolymerized in an amount of 0.5 to 3 mol% based on all acid components. The sulfonic acid group-containing compound has an effect of hydrophilizing polyalkylene terephthalate, and specifically, isophthalic acid having a sulfonic acid group such as 5-sodium isophthalic acid is preferable.

The copolymerization ratio of the sulfonate group-containing compound is
When the amount is less than 0.5 mol%, the effect of improving the hygroscopicity of the fiber may be insufficient, and when the amount exceeds 3 mol%, the yarn quality characteristics may be reduced or the alkali weight loss rate may be increased, which is not preferable. .

Further, the polyalkylene terephthalate forming the fiber of the present invention requires that dimer acid be copolymerized in an amount of 0.5 to 5 mol% based on all acid components.
The dimer acid is a dimer of an aliphatic monocarboxylic acid having 10 or more carbon atoms, and can be obtained, for example, by coupling oleic acid in the presence of nickel by a pressure system. Commercial products of dimer acid include Empole 10 manufactured by Emery Corporation.
08 and so on.

Dimer acid has a bulky molecular structure.
It has the effect of reducing the rate of weight loss due to alkali. Further, when dimer acid is copolymerized in polyalkylene terephthalate, the content of dialkylene glycol (hereinafter abbreviated as DAG) increases due to the acid catalytic effect of the carboxyl group, so that the increase in hydrophobicity due to dimer acid is reduced. It is possible to increase the hygroscopicity without increasing the content of the polyether compound or the polyether compound derivative or the copolymerization amount of the sulfonate group-containing compound, and the physical properties of the fiber are reduced by the increase of these components. Can be prevented.

If the copolymerization ratio of dimer acid is less than 0.5 mol%, the effect of reducing the rate of weight loss by alkali may be insufficient. If it exceeds 5 mol%, the physical properties of the fiber such as a decrease in melting point may be reduced. This is not preferable because it significantly decreases.

The polyalkylene terephthalate is
As long as the essential properties are not impaired, other copolymer components may be contained in small amounts. Examples of these copolymer components include aromatic dicarboxylic acid components such as isophthalic acid, phthalic anhydride and naphthalenedicarboxylic acid, and adipine. Acid, aliphatic dicarboxylic acid component such as sebacic acid, glycol component such as 1,4-cyclohexanedimethanol, 4-hydroxybenzoic acid, ε
And hydroxycarboxylic acid components such as caprolactone.

Further, the fiber of the present invention has an alkali weight loss rate.
It is necessary that it is not more than 1.5% by weight / minute. If the alkali weight loss rate exceeds 1.5% by weight / minute, the progress of weight loss is so fast that it is difficult to control the weight loss rate and uniform weight loss processing cannot be performed.

The value of the alkali weight loss rate is a value measured by the following method. The fiber is knitted in a tube and treated with a 5% by weight aqueous solution of sodium hydroxide at 70 ° C. for 40 minutes at a bath ratio of 1:50. Weight loss rate (% by weight / min) = [(XY) / X] × 100 /
40 where X is the weight before weight loss and Y is the weight after weight loss.

Further, the fiber of the present invention has a temperature of 34 ° C. and a humidity of 34 ° C.
It is necessary that the moisture absorption under an atmosphere of 90% RH is 4% by weight or more. When the moisture absorption is less than 4% by weight, sufficient moisture absorption cannot be obtained as compared with natural fibers such as cotton, and unpleasant sensation is likely to be caused when worn as clothing.

The value of the moisture absorption refers to a value measured by the following method. The fiber is knitted in a tube, and the fiber is humidified at 25 ° C. and 60% RH to measure the weight W ₀ . Next, this tubular knitted fabric is
After drying at 80 ° C. for 6 hours under reduced pressure and leaving it in a thermo-hygrostat set at 34 ° C. and 90% RH for 6 hours, the weight W ₁ is measured.
Then, the moisture absorption is determined by the following equation. Moisture absorption (% by weight) = [(W ₁ −W ₀ ) / W ₀ ] × 100

The fiber of the present invention can be produced, for example, by the following method. Esterification of terephthalic acid and diol directly or transesterification of lower alkyl ester of terephthalic acid with diol to synthesize polyester oligomer, and then polyether compound or polyether compound derivative and sulfonic acid group-containing compound and A polycondensation reaction is performed by adding dimer acid or the like. The polycondensation reaction is usually performed in the presence of a metal compound such as antimony, germanium, tin, titanium, zinc, aluminum, or cobalt under a reduced pressure of about 0.12 to 12 hPa at a temperature of 220 to 290 ° C. and an intrinsic viscosity of 0.5 or more. It is preferable to perform until it becomes.

In addition, as long as the effects of the present invention are not impaired, antioxidants such as hindered phenol compounds, color improving agents such as cobalt compounds, fluorescent agents and dyes, pigments such as titanium dioxide and the like. An additive such as a light-proofing agent such as cerium oxide may be contained.

Next, the obtained polyester is dried by a conventional method, supplied to a usual melt-spinning machine stand, and melt-spun at a temperature higher than the melting point of the polyester by 20 ° C. or more.
At a speed of 1 min, unwound or semi-undrawn yarn, or 1.5 times without winding.
Draw up to 3.5 times and heat-treat at 80 to 180 ° C to obtain the desired fiber.

In addition, a composite fiber with other components may be used as long as the effects of the present invention are not impaired. Furthermore, the form of the polyester fiber may be either a long fiber or a short fiber,
If necessary, it can be used after being subjected to post-processing such as crimping, false twisting, and treatment with a chemical solution.

[0028]

The present inventors presume the reason why the polyester fiber of the present invention can be uniformly subjected to alkali weight reduction processing and has excellent hygroscopicity as follows. In order to impart hygroscopicity to polyester, it is necessary to contain a polyether compound or a polyether compound derivative having a certain segment length.For example, in the case of polyethylene glycol, it is preferable that the average molecular weight is not more than about 4000. No hygroscopicity is obtained. However, such high-molecular-weight polyether compounds generally have poor compatibility with polyesters, so that all of them are not copolymerized with polyesters, and some of them are in a state of being dispersed in polyesters. When alkali weight reduction processing is performed on fibers made of such polyester,
First, a polyether compound or a polyether compound derivative that is not copolymerized is eluted by water to increase the surface area of the fiber, and as a result, hydrolysis of the polyester by alkali proceeds rapidly.

The polyester fiber of the present invention contains, as a polyether compound or a polyether compound derivative, a substantially water-insoluble material having a solubility in water at 20 ° C. of 30% by weight or less. Even if this component is dispersed in the polyester, it is suppressed that this component is eluted during alkali weight reduction processing. Further, dimer acid copolymerized with polyester has a bulky molecular structure, and thus has an effect of inhibiting hydrolysis by alkali due to steric hindrance. As a result, the alkali weight loss rate of the fiber can be set to 1.5% by weight / minute or less, which is within a range where there is no practical problem.

Further, since the polyether compound or the polyether compound derivative which is hardly soluble in water as described above has a segment of a substantially certain length,
Since the hygroscopicity is high, and the polyester itself is copolymerized with a sulfonic acid group-containing compound, the hydrophobicity is reduced. Further, when dimer acid is used as a component having an effect of improving alkali hydrolysis resistance, the DAG content in the polyester increases, so that the increase in the hydrophobicity of the polyester due to the dimer acid is suppressed. Therefore,
Without increasing the content of the polyether compound or the polyether compound derivative and the copolymerization amount of the sulfonate group-containing compound, excellent hygroscopicity can be obtained, and the decrease in fiber properties is also small. As a result, it is recognized that the fiber has a moisture absorption of 4% by weight or more, which makes it possible to obtain an excellent fiber.

[0031]

Next, the present invention will be described in detail with reference to examples. In addition, the measuring method and the evaluation method of the characteristic value in an example are as follows. (1) Dissolution rate To 100 g of water adjusted to 20 ° C., 1 g of a polyether compound or a polyether compound derivative is added and stirred for 5 minutes.
When completely dissolved, the operation of further adding 1 g of a polyether compound or a polyether compound derivative and stirring for 5 minutes was repeated, and the addition amount at the time when the solution was not completely dissolved was determined by the following formula. Dissolution rate (% by weight) = [Total added amount / (Total added amount + 100)]
× 100 (2DAG content After polyester was alkali-hydrolyzed, it was measured using a gas chromatograph GC-9A manufactured by Shimadzu Corporation. (3) Intrinsic viscosity [η]
It was measured at a temperature of 20 ° C. (4) Strong elongation Using Orientic Tensilon RTC-1210, 50
A tensile test was performed on a cm sample at a speed of 50 cm / min, and the tensile test was obtained from the stress-strain curve. (5) Alkali Weight Loss Rate The alkali weight loss rate was evaluated according to the method for measuring the alkali weight loss rate described above. (6) Moisture Absorption Rate Evaluation was made according to the above-described method for measuring the moisture absorption rate. (7) Texture Fiber is knitted in a tube and treated with a 5% by weight aqueous sodium hydroxide solution.
The treatment was carried out at 70 ° C. and a bath ratio of 1:50 so that the weight loss was 20% by weight, and the texture after the treatment was evaluated by a sensory test by 10 panelists in the following three stages. ：: More than 7 out of 10 felt soft. Δ: 4 to 6 out of 10 felt soft. ×: 3 or less out of 10 people felt soft.

Example 1 Terephthalic acid and ethylene glycol (hereinafter abbreviated as EG) were placed in an esterification reactor in which a PET oligomer was present.
Slurry at a molar ratio of 1 / 1.6 with
The esterification reaction was carried out under the conditions of 50 ° C., a pressure of 0.1 MPaG, and a residence time of 8 hours to continuously obtain a PET oligomer having a conversion of 95%.

48.0 kg of this PET oligomer was transferred to a polycondensation reactor, and 8.9 kg of polyethylene glycol having an average molecular weight of 20,000 (hereinafter abbreviated as PEG) and 2.90 kg of dimer acid were used.
9 kg and 178 g of "Irganox 245" (Ciba Specialty Chemicals, a hindered phenolic antioxidant) were added as an antioxidant, followed by stirring and mixing for 30 minutes.

Thereafter, an EG slurry having a titanium dioxide content of 0.4% by weight based on the polyester, 3 × 10 ^-4 mol of antimony trioxide per 1 mol of the total acid component and 1 mol of the total acid component were used. 1.5 mol% of ethylene glycol ester of 5-sodium sulfoisophthalic acid (hereinafter, referred to as
Abbreviated as SIPG. ), And the temperature in the polycondensation reactor is raised to 270 ° C in 30 minutes, and the pressure is gradually reduced.
After 60 minutes, the pressure was reduced to 1.2 hPa or less. While stirring under these conditions,
The polycondensation reaction was carried out for 4 hours, and was discharged and pelletized by a conventional method.

Next, the pellets were dried by a conventional method, then melt-spun at a spinning temperature of 290 ° C. using a conventional melt spinning apparatus, and undrawn yarn was wound up at a speed of 1400 m / min. This undrawn yarn is supplied to a drawing machine, preheated at 80 ° C., and then heated to a temperature of 1 ° C.
Stretch 3.5 times while contacting with 50 ℃ heat plate,
It was heat-treated and wound up to obtain a 75d / 36f filament yarn.

Examples 2 to 5 and Comparative Examples 1 to 7 Except that the kind and content of the polyether compound or polyether compound derivative and the copolymerization ratio of SIPG and dimer acid were variously changed as shown in Table 1, It carried out like Example 1. Table 1 summarizes the [η] of the polyesters obtained in Examples 1 to 5 and Comparative Examples 1 to 7 and the evaluation results of the fibers.

[0037]

[Table 1]

In Examples 1 to 5, the yarn production and the operability were good, and as is clear from Table 1, the alkali weight reduction rate of the obtained fiber was 1.5% by weight / minute or less. The range was practically no problem in performing the process, and a soft texture could be imparted to the fibers by performing the weight reduction process. Further, the moisture absorption was 4% by weight or more, and fibers having excellent moisture absorption were obtained.

On the other hand, in Comparative Example 1, since the solubility of the polyether compound in water was too high, the obtained fiber had a high alkali weight loss rate and could not be subjected to uniform weight loss processing. Could not be evaluated. In Comparative Example 2, since the content of the polyether compound was too small, the obtained fiber had insufficient moisture absorption. In Comparative Example 3, since the content of the polyether compound was too large, yarn breakage frequently occurred during spinning, and a fiber could not be obtained. In Comparative Example 4, since the copolymerization amount of SIPG was too small, the obtained fiber had insufficient moisture absorption. In Comparative Example 5, the obtained fiber had a low strength because the copolymerization amount of SIPG was too large, and the alkali weight loss rate was too high to perform uniform weight loss processing. Could not be evaluated. In Comparative Example 6, since the copolymerization amount of the dimer acid was too small, the obtained fiber had a high alkali weight loss rate and could not be subjected to uniform weight loss processing, and the texture after the weight reduction processing could be evaluated. Did not. In Comparative Example 7, since the copolymerization amount of the dimer acid was too large, yarn breakage frequently occurred during spinning, and a fiber could not be obtained.

[0040]

Since the polyester fiber of the present invention has an alkali weight loss rate within a range where there is no practical problem, by performing alkali weight reduction processing, a soft texture can be exhibited and the moisture absorption performance is excellent. Therefore, it is possible to provide clothing that can provide a comfortable wearing feeling.

Claims (1)

[Claims] 1. A polyether compound or a polyether compound derivative having a solubility in water at 20 ° C. of 30% by weight or less is contained in an amount of 3 to 30% by weight. 3 mol%, a fiber composed of polyalkylene terephthalate copolymerized with 0.5 to 5 mol% of dimer acid with respect to the total acid component, wherein the alkali weight loss rate is 1.5 wt% / min or less, and
4% by weight of moisture absorption in an atmosphere of 34 ° C and 90% RH
A hygroscopic polyester fiber characterized by the above.