JP2020041228A - Polyester composite fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester-based composite fiber having yellowing resistance and excellent in strength retention under an alkaline solution environment and under ultraviolet irradiation. SOLUTION: This is a composite fiber composed of a component A which is a polyester resin and a component B which is a thermoplastic resin, and is characterized by satisfying the following (1) to (3). fiber. (1) In the dicarboxylic acid component of the polyester resin (component A), 50 mol% or more of the total dicarboxylic acid component is terephthalic acid, and 0 to 50 mol% of the total dicarboxylic acid component is a dicarboxylic acid component other than terephthalic acid. It is a polyester resin composed of (I) and having a diol component of cyclohexanedimethanol (2) the polyester resin (component A) contains an antioxidant (3) fibers of the polyester-based composite fiber. In the cross section, the B component is the core, and the A component covers the entire circumference of the B component. [Selection diagram] None

Description

  The present invention relates to a polyester composite fiber having alkali resistance and light resistance. More specifically, the present invention relates to a polyester-based composite fiber containing a specific copolymer component, having yellowing resistance, and having excellent strength retention in an alkaline solution environment and under ultraviolet irradiation.

  Polyester fibers, especially polyethylene terephthalate fibers, are highly crystalline and have a high melting point, exhibiting not only mechanical properties such as strength and elongation, but also excellent properties such as heat resistance and chemical resistance. Widely used in the product field. However, it is known that polyethylene terephthalate fibers undergo hydrolysis in an aqueous alkaline solution, resulting in erosion of the fiber surface. Many improvements and reforming methods have been proposed to improve the disadvantages of hydrolysis in an aqueous alkaline solution. As a typical method, Patent Document 1 discloses a polyester fiber having terephthalic acid as a main acid component and cyclohexane dimethanol as a main diol component, wherein 0 to 40 mol% of all dicarboxylic acid components constituting the polyester are contained. A dicarboxylic acid component (A) other than terephthalic acid, and 0 to 30 mol% of a diol component constituting the polyester are replaced by a diol component (B) other than cyclohexanedimethanol; Modified polyester fibers wherein the total amount of component (A) and diol component (B) is in the range of 5 to 40 mol% of the total dicarboxylic acid component are mentioned. However, although the fiber obtained in Patent Document 1 has sufficient resistance to an aqueous alkali solution, reduction in strength after alkali treatment has not been studied. Furthermore, the light resistance of the fibers was not studied, and there was a problem of yellowing due to ultraviolet irradiation of the obtained fibers and a problem of a decrease in strength after the treatment. Therefore, in application fields such as food-related uniforms, durability in industrial washing is required, and it is difficult to achieve both the strength retention under an alkaline solution environment and the strength retention under ultraviolet irradiation. there were.

JP-A-8-92816

  An object of the present invention is to provide a polyester-based composite fiber having yellowing resistance and excellent strength retention in an alkaline solution environment and under ultraviolet irradiation in view of the above-mentioned current situation.

  The present inventors have conducted intensive studies to solve the above problems, and as a result, a polyester-based conjugate fiber, in which the fiber surface is coated with a polyester containing an antioxidant, and the main component of the dicarboxylic acid component of the polyester is terephthalic acid. As a component, by using cyclohexane dimethanol as the diol component, it was found that a polyester-based composite fiber having yellowing resistance and having excellent strength retention under an alkaline solution environment and under ultraviolet irradiation was obtained, and completed the present invention. I let it.

That is, the polyester-based conjugate fiber of the present invention has the following configuration.
A conjugate fiber composed of a component A which is a polyester resin and a component B which is a thermoplastic resin, characterized by satisfying the following (1) to (3).
(1) In the dicarboxylic acid component of the polyester resin (A component), 50 mol% or more of all dicarboxylic acid components are terephthalic acid, and 0 to 50 mol% of all dicarboxylic acid components are dicarboxylic acid components other than terephthalic acid. (1) Polyester resin wherein the diol component is cyclohexanedimethanol (2) The polyester resin (Component A) contains an antioxidant (3) Fiber of the polyester-based composite fiber In the cross section, the B component becomes the core, and the A component covers the entire circumference of the B component.

  Further, the dicarboxylic acid component (I) is preferably isophthalic acid.

  Further, it is preferable that the antioxidant is at least one or more antioxidants selected from the group consisting of a hindered phenol antioxidant, a phosphorus antioxidant, and a sulfur antioxidant.

  In the polyester composite fiber, the content of the antioxidant in the component A is preferably 0.01 to 1.0% by mass based on the mass of the resin of the component A.

  Further, it is preferable that the composite ratio (mass ratio) of the component A and the component B is A: B = 50: 50 to 20:80.

  Further, it is preferable that the thermoplastic resin (component B) is at least one or more thermoplastic resins selected from the group consisting of polyester resins, polyamide resins, and olefin resins.

  Further, it is preferable that the single fiber fineness of the polyester-based composite fiber is 0.3 to 300 dtex.

  Furthermore, it is a fabric constituted by using the polyester-based composite fiber of the present invention.

  In the present invention, it is possible to provide a polyester-based composite fiber having yellowing resistance and excellent strength retention in an alkaline solution environment and under ultraviolet irradiation.

The polyester-based conjugate fiber of the present invention is a conjugate fiber composed of an A component which is a polyester resin and a B component which is a thermoplastic resin. It is possible to obtain a polyester-based composite fiber which has yellowing and has excellent strength retention in an alkaline solution environment and under ultraviolet irradiation.
(1) In the dicarboxylic acid component of the polyester resin (A component), 50 mol% or more of all dicarboxylic acid components are terephthalic acid, and 0 to 50 mol% of all dicarboxylic acid components are dicarboxylic acid components other than terephthalic acid. (1) Polyester resin wherein the diol component is cyclohexanedimethanol (2) The polyester resin (Component A) contains an antioxidant (3) Fiber of the polyester-based composite fiber In the cross section, the B component becomes the core, and the A component covers the entire circumference of the B component.

  The polyester fiber in the present invention needs to be a conjugate fiber having the B component, which is a thermoplastic resin, as a core from the viewpoint of fiber strength and light resistance.

(A component)
According to the present invention, the polyester resin used for the component A of the polyester-based composite fiber is such that, in the dicarboxylic acid component, 50 mol% or more of the total dicarboxylic acid component is terephthalic acid, and 0 to 50 mol% of the total dicarboxylic acid component. It is important that the polyester resin is composed of a dicarboxylic acid component (I) other than terephthalic acid, and the diol component is cyclohexanedimethanol.

  The “dicarboxylic acid (I) other than terephthalic acid” in the present invention is not particularly limited, but is isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid. Aromatic dicarboxylic acids such as 4,4'-diphenylisopropylidene dicarboxylic acid, 1,2-diphenoxyethane-4 ', 4 "-dicarboxylic acid, anthracene dicarboxylic acid, 2,5-pyridine dicarboxylic acid, and diphenyl ketone dicarboxylic acid Acids: aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid and sebacic acid; alicyclic dicarboxylic acids such as decalin dicarboxylic acid and cyclohexanedicarboxylic acid; In addition, two or more types may be used.

  In particular, when isophthalic acid is used as the dicarboxylic acid (I), sufficient crystallinity can be maintained and a decrease in the glass transition temperature can be kept to a minimum even if the melting point is lowered by increasing the copolymerization amount. Since the spinning stability can be improved and the cost is low, it is preferable to use isophthalic acid as the dicarboxylic acid (I).

  The copolymerization amount of the above-mentioned dicarboxylic acid (I) is in the range of 0 to 50 mol%, particularly preferably in the range of 5 to 45 mol%, based on all dicarboxylic acid components constituting the polyester. If the copolymerization amount exceeds 50 mol%, the melting point and crystallinity of the polyester may decrease, and the alkali resistance of the conjugate fiber may decrease.

  It is important that the diol component of the polyester resin (component A) in the present invention is cyclohexanedimethanol. The cyclohexane dimethanol includes three kinds of positional isomers of 1,2-cyclohexane dimethanol, 1,3-cyclohexane dimethanol, and 1,4-cyclohexane dimethanol, and one of these isomers is used. Also, a mixture of two or more kinds may be used. The position isomer is not particularly limited, but 1,4-cyclohexanedimethanol is particularly preferred. Further, each of the positional isomers has cis and trans stereoisomers, and either one of them or a mixture thereof may be used.

  The polyester resin (A component) in the present invention can be copolymerized with the third component as long as the object of the present invention is not impaired. Such third components include hydroxycarboxylic acids such as β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, hydroxypropionic acid and hydroxyacrylic acid; or hydroxycarboxylic acids derived from ester-forming derivatives thereof, ε-caprolactone And other aliphatic lactones. These third components can be used alone or in combination of two or more.

  Further, the polyester resin (A component) of the present invention may include a polycarboxylic acid such as trimellitic acid, trimesic acid, pyromellitic acid, and tricarballylic acid within a range where the polyester molecular chain is substantially linear; And polyhydric alcohols such as trimethylolethane, trimethylolpropane, and pentaerythritol.

  The polyester used in the polyester resin (A component) of the present invention is prepared by subjecting cyclohexane dimethanol, terephthalic acid and dicarboxylic acid component (I) to esterification or transesterification to prepare a low polymer thereof. After that, a polycondensation reaction is performed at 230 to 300 ° C. under reduced pressure using a condensation polymerization catalyst such as tetraalkoxytitanium, antimony oxide, or germanium oxide to adjust the viscosity to a desired value. After the polymerization in the liquid phase as described above, the degree of polymerization may be further increased by solid phase polymerization to increase the intrinsic viscosity.

  It is important that the polyester resin (component A) of the present invention contains an antioxidant from the viewpoint of improving the yellowing resistance of the conjugate fiber. The antioxidant is preferably at least one selected from the group consisting of hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants.

  In general, polyester resins are easily oxidized under high-temperature conditions such as polycondensation reactions and melt-spinning conditions or under an ultraviolet irradiation environment, and may cause inconveniences such as a decrease in the degree of polymerization and coloring of fibers. It is preferable to add an antioxidant in order to obtain a fiber having a good quality. Antioxidants can be classified into chain initiation inhibitors, radical chain inhibitors, peroxide decomposers, etc. according to their mechanism of action, but antioxidants classified as radical chain inhibitors are superior in terms of effect, and among them, However, hindered phenolic antioxidants are suitable. Such a hindered phenolic antioxidant is a phenolic compound having a sterically hindered substituent at both or one of two carbon atoms adjacent to the carbon atom having a phenolic hydroxyl group, and Irganox 1010 (manufactured by BASF). And Irganox 1330 (manufactured by BASF) can be used.

  The hindered phenolic antioxidants may be used alone or in combination of two or more. Further, it may be used in combination with other antioxidants, and is particularly classified as a peroxide decomposer such as a phosphorus antioxidant such as triphenyl phosphite and a sulfur antioxidant such as dilauryl dithiopropionate. When an antioxidant is used in combination, a higher antioxidant effect may be obtained due to a synergistic effect with a hindered phenolic antioxidant, and a composite excellent in yellowing resistance and strength retention under ultraviolet irradiation. Fiber can be obtained. Therefore, it is particularly preferable to use a hindered phenol-based antioxidant together with a phosphorus-based antioxidant and / or a sulfur-based antioxidant.

  The compounding amount of these antioxidants is not particularly limited, but may be 0.01 to 1.0% by mass based on the mass of the resin of component A from the viewpoint of exhibiting the effect of the antioxidants and spinnability. Preferably, it is in the range of 0.05 to 0.5% by mass.

(B component)
Next, as the thermoplastic resin used for the component B of the polyester-based conjugate fiber of the present invention, from the viewpoint of the strength of the conjugate fiber, at least one or more selected from the group consisting of a polyester-based resin, a polyamide-based resin, and an olefin-based resin. It is preferably a thermoplastic resin.

  As the polyester resin used for the thermoplastic resin (component B), aromatic polyester resins such as poly C2-4 alkylene arylate resin (polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.) In particular, polyethylene terephthalate resin such as PET is preferable. Polyethylene terephthalate-based resins include, in addition to ethylene terephthalate units, other dicarboxylic acids (e.g., isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, 4,4'-diphenylcarboxylic acid, bis (carboxyphenyl) ethane , Sodium 5-sulfoisophthalate, etc.) and diols (eg, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, (Polyethylene glycol, polytetramethylene glycol, etc.) at a ratio of 20 mol% or less.

  Examples of the polyamide resin used for the thermoplastic resin (component B) include aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 12, and polyamide 6-12 and copolymers thereof, and aromatic dicarboxylic acids. Semi-aromatic polyamides synthesized from aliphatic diamines and the like are preferred. These polyamide resins may also contain other copolymerizable units.

  As the polyolefin-based resin used for the thermoplastic resin (component B), polypropylene, polyethylene, and the like are preferable, and these polyolefin-based resins may also contain other copolymerizable units.

(Method of manufacturing composite fiber)
As long as the combination of the component A and the component B is determined, the polyester-based composite fiber of the present invention can be converted into a fiber using a conventionally known composite spinning apparatus. It can be produced by any spinning method such as a method of drawing after melt-spinning at low and medium speeds, a method of direct spinning at high speed, and a method of performing drawing and false twist simultaneously or successively after spinning.

  The polyester-based conjugate fiber of the present invention can be appropriately set according to the application. For example, it can be in the range of 0.3 to 300 dtex (preferably 0.3 to 200 dtex). It is possible to use fine fibers having a fineness of 0.3 to 10 dtex, preferably 0.3 to 5 dtex.

  In the polyester-based composite fiber of the present invention, the composite ratio of the component A and the component B is preferably such that A: B is 50:50 to 20:80 (mass ratio), more preferably 50:50 to 25:75. (Mass ratio), and the ratio between the two may be adjusted according to the fiber shape. If the ratio is out of this range, the composite ratio becomes unbalanced, causing problems such as bending of the discharged yarn after the nozzle discharge, and the spinnability may be poor.

  In order to obtain a conjugate fiber having excellent alkali resistance and yellowing resistance in the cross section of the polyester conjugate fiber of the present invention, it is necessary to cover the entire B component with the A component. If the thermoplastic resin, which is the component B, is exposed on the fiber surface, hydrolysis is caused by the alkaline aqueous solution, and as a result, the strength of the composite fiber is reduced. The composite form of the present invention is not particularly limited as long as the entire B component is covered with the A component, and may be a concentric type, an eccentric type, or a multi-core type. Further, the fiber cross-sectional shape of the B component may be a circular cross-sectional shape, or may be an irregular cross-sectional shape such as a triangular, flat, or multi-lobed shape. Further, a hollow portion can be provided inside the component B, and various cross-sectional shapes such as a hollow shape such as a single-hole hollow, a two-hole hollow or a multi-hole hollow can be used. Among these, the composite fiber preferably has a core-in-sheath composite structure having a concentric circular cross-sectional shape in which the B component is a core component and the A component is a sheath component.

  The polyester-based composite fiber of the present invention may further contain conventional additives such as stabilizers (heat stabilizers such as copper compounds, ultraviolet absorbers, light stabilizers, etc.), fine particles, coloring agents, fluorescent brighteners, It may contain an inhibitor, a flame retardant, a deodorant, a plasticizer, a lubricant, a crystallization rate retarder, and the like. These additives can be used alone or in combination of two or more. These additives may be contained in the fiber or may be carried on the surface of the fiber aggregate.

  The conjugate fiber of the present invention obtained as described above can be used as various fiber aggregates (fibrous structures). Here, examples of the fiber aggregate include various woven and knitted fabrics and nonwoven fabrics.

  The polyester-based composite fiber of the present invention can be used as long fibers such as monofilaments and short fibers such as staples. From such fibers, various fiber aggregates (fibrous structures) including yarns can be formed. it can. Examples of the fiber aggregate include multifilament yarns, spun yarns, and yarns such as mixed fibers of the fibers of the present invention with natural fibers, semi-synthetic fibers, and other synthetic fibers, mixed spun yarns, and plied yarns; Fabrics such as knits and nonwoven fabrics; synthetic papers; resin moldings, and the like. These fibers and fiber aggregates may be subjected to any processing such as false twist crimping and entanglement as required. Further, the fiber product of the present invention may be any of fiber products such as knitted and woven fabrics, nonwoven fabrics, final garments, towels and the like made of such fibers and yarns.

  In addition, the cloth made of the polyester-based conjugate fiber may be formed of the conjugate fiber of the present invention alone, but a woven or knitted fabric or a nonwoven fabric partially using the conjugate fiber of the present invention, for example, a natural fiber, Orthogonal woven fabric with other fibers such as chemical fiber and synthetic fiber, or blended yarn, woven or knitted fabric used as blended yarn, or blended nonwoven fabric may be used. For example, when used in combination with other fibers, the proportion of the conjugate fiber of the present invention in the woven or knitted fabric or the nonwoven fabric may be, for example, 14% by mass or more, preferably 15% by mass or more, more preferably 18% by mass. %, More preferably 23% by mass or more. When used as a blended yarn or a blended yarn, the ratio of the conjugate fiber of the present invention in the yarn may be, for example, 14 to 95% by mass, preferably 20 to 95% by mass, more preferably 30 to 95% by mass. It is 95% by mass, more preferably 40 to 95% by mass.

  The fabric thus obtained can be used for various purposes, industrial materials, and clothing. In particular, it is particularly useful in applications where it is exposed to alkali during the manufacturing process or during practical use.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In addition, each physical property value in an Example was measured by the following method.

(Spinnability)
The spinnability was evaluated according to the following criteria.
A: Continuous spinning was performed for 24 hours, and no breakage occurred during spinning.
：: Continuous spinning was performed for 24 hours, and the number of times of yarn breakage during spinning was from 1 to less than 3.
X: Continuous spinning was performed for 24 hours, and three or more breaks occurred during spinning.

(Fineness, strength, elongation of polyester composite fiber)
It was determined in accordance with JIS L 1013.

(Alkali resistance)
3 g of each of the polyester-based composite fibers was weighed, and the weight was measured after being treated in an aqueous solution of 40% NaOH at 98 ° C. for 40 minutes. The greater the weight loss during the alkali treatment, the lower the alkali hydrolysis resistance.
Alkali treatment weight loss rate (%) = (weight before alkali weight loss-weight after alkali weight loss) / weight before weight loss × 100

Further, the strength (cN / dtex) of the fiber subjected to the same treatment as before and after the treatment was measured in accordance with JIS L 1013, and the retention was determined by the following equation.
Strength retention (%) = strength after alkali reduction treatment / strength before treatment × 100

(Yellowing resistance)
After a circular knitted fabric was produced from the obtained polyester-based composite fiber using a circular knitting machine (28 gauge), the discoloration caused by irradiation with a fade meter for 60 hours was determined in a gray scale in accordance with JIS L 1096. .

(Light fastness)
The strength (cN / dtex) of the fiber that had been subjected to the same treatment as the yellowing resistance before and after the treatment was measured in accordance with JIS L 1013, and the retention was determined by the following equation.
Intensity retention (%) = intensity after irradiation treatment with fade meter for 60 hours / intensity before treatment × 100

(Example 1)
From a dicarboxylic acid raw material composed of 40 mol% of isophthalic acid and 60 mol% of terephthalic acid and 1,4-cyclohexanedimethanol (cis / trans = 32/68), a molar ratio of a diol raw material to a dicarboxylic acid raw material is 1.2. : 1, a slurry is formed, and the slurry is subjected to an esterification reaction under pressure (absolute pressure: 2.5 kg / cm ² ) at a temperature of 250 ° C until the esterification ratio becomes 95%. A polymer was produced. Next, 350 ppm of tetraisopropyl titanate was added as a catalyst, and melt polycondensation was performed at 280 ° C. for 1.5 hours under a reduced pressure of 1 Torr absolute to produce a polyester having an intrinsic viscosity of 0.75 dl / g. 0.05% by mass of a mixture of a hindered phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant was mixed with the polyester, extruded from a nozzle into a strand, and cut to obtain a 2.8 mm diameter. A 3.2 mm long cylindrical tip was produced.

  The above polyester chips are crystallized at 180 ° C. under vacuum to obtain a sheath component (component A), and polyethylene terephthalate (component B) containing a core component containing 0.5% by mass of titanium oxide having an average particle diameter of 0.4 μm. At a spinning temperature of 290 ° C. and a single hole discharge rate of 1.22 g / min under a condition that the compounding ratio (mass ratio) of the mixture is 25:75, a temperature of 25 ° C. and a humidity of 60% The cooling air is sprayed onto the spun yarn at a speed of 0.4 m / sec to reduce the temperature of the spun yarn to 60 ° C. or lower. Then, the length is 1.0 m, which is placed 1.2 m below the spinneret, and the entrance guide system is 8 mm. After being introduced into a tube heater (inner temperature: 185 ° C.) with an exit guide system of 10 mm and an inner diameter of 30 mm and stretched in the tube heater, the yarn coming out of the tube heater is supplied with oil by an oiling nozzle and passed through two take-off rollers. 40 Winding was performed at a speed of 00 m / min to obtain a composite fiber of 84 dtex / 24 filaments. This polyester-based composite fiber had no problem in the process-passing property even in the long-term fiberization. Using this composite fiber, a tubular knitted fabric was produced. Using this tubular knitted fabric, alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Examples 2 to 8)
The core / sheath mass ratio, the amount of the antioxidant added, the amount of the isophthalic acid of the component A, and the polymer of the component B were changed, and spun at a ratio shown in Table 1 in the same manner as in Example 1 to obtain 84 dtex / 24 filaments. Was obtained. This polyester-based composite fiber had no problem in the process-passing property even in the long-term fiberization. Further, a tubular knitted fabric was produced using the composite fiber, and alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Example 9)
From a dicarboxylic acid raw material composed of 30 mol% of 1,4-cyclohexanedicarboxylic acid (cis / trans = 55/45) and 70 mol% of terephthalic acid, and 1,4-cyclohexanedimethanol (cis / trans = 32/68) A slurry was formed by adjusting the molar ratio of the diol raw material: dicarboxylic acid raw material to 1.2: 1, and the slurry was esterified at a temperature of 250 ° C. under pressure (2.5 kg / cm ² absolute pressure). The esterification reaction was carried out until the rate became 95%, to produce a low polymer. Next, 350 ppm of tetraisopropyl titanate was added as a catalyst, and melt polycondensation was performed at 280 ° C. for 1.5 hours under a reduced pressure of 1 Torr absolute to produce a polyester having an intrinsic viscosity of 0.75 dl / g. 0.05% by mass of a mixture of a hindered phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant was mixed with the polyester, extruded from a nozzle into a strand, and cut to obtain a 2.8 mm diameter. A 3.2 mm long cylindrical tip was produced.

  The above polyester chips are crystallized at 180 ° C. under vacuum to obtain a sheath component (component A), and polyethylene terephthalate (component B) containing a core component containing 0.5% by mass of titanium oxide having an average particle diameter of 0.4 μm. At a spinning temperature of 290 ° C. and a single hole discharge rate of 1.22 g / min under a condition that the composite ratio (mass ratio) is 25:75, a temperature of 25 ° C. and a humidity of 60% The cooling air is sprayed onto the spun yarn at a speed of 0.4 m / sec to reduce the temperature of the spun yarn to 60 ° C. or lower. Then, the length is 1.0 m, which is placed 1.2 m below the spinneret, and the entrance guide system is 8 mm. After being introduced into a tube heater (inner temperature: 185 ° C.) with an exit guide system of 10 mm and an inner diameter of 30 mm and stretched in the tube heater, the yarn coming out of the tube heater is lubricated with an oiling nozzle and passed through two take-off rollers. 40 Winding was performed at a speed of 00 m / min to obtain a composite fiber of 84 dtex / 24 filaments. This polyester-based composite fiber had no problem in the process-passing property even in the long-term fiberization. Using this composite fiber, a tubular knitted fabric was produced. Using this tubular knitted fabric, alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Comparative Example 1)
From a dicarboxylic acid raw material composed of 30 mol% of 1,4-cyclohexanedicarboxylic acid (cis / trans = 55/45) and 70 mol% of terephthalic acid, and 1,4-cyclohexanedimethanol (cis / trans = 32/68) A slurry was formed by adjusting the molar ratio of the diol raw material: dicarboxylic acid raw material to 1.2: 1, and the slurry was esterified at a temperature of 250 ° C. under pressure (2.5 kg / cm ² absolute pressure). The esterification reaction was carried out until the rate became 95%, to produce a low polymer. Next, 350 ppm of tetraisopropyl titanate was added as a catalyst, and melt polycondensation was performed at 280 ° C. for 1.5 hours under a reduced pressure of 1 Torr absolute to produce a polyester having an intrinsic viscosity of 0.75 dl / g. This polyester was extruded from a nozzle into a strand without an antioxidant and cut to produce a cylindrical chip having a diameter of 2.8 mm and a length of 3.2 mm.

  The above polyester chip was crystallized at 180 ° C. under vacuum, and spun at 275 ° C. at a spinning speed of 1000 m / min using a spinneret having 36 circular spinning holes having a diameter of 0.25 mm. A drawn yarn was obtained. This was subjected to a drawing heat treatment at a drawing speed of 1000 m / min using a heating roller at 75 ° C. and a plate heater at 150 ° C., to obtain a drawn yarn of 84 dtex / 24 filament fiber. Using this fiber, a tubular knitted fabric was produced. Using this tubular knitted fabric, alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Comparative Example 2)
The dicarboxylic acid component of the component A was changed to isophthalic acid, the amount of the isophthalic acid of the component A and the amount of the antioxidant added were changed to the ratios shown in Table 1, and spun by the same method as in Comparative Example 1 to 84 dtex / 24. Filament fibers were obtained. Further, a tubular knitted fabric was produced using the fibers, and alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Comparative Examples 3 to 6 and 8)
The core / sheath mass ratio, the amount of the antioxidant added, the dicarboxylic acid component and the diol component of the A component were changed to the ratios shown in Table 1, and the mixture was spun in the same manner as in Example 1 to produce a composite of 84 dtex / 24 filaments. Fiber was obtained. Further, a tubular knitted fabric was produced using the composite fiber, and alkali resistance and light resistance were evaluated. Table 1 shows the results.

(Comparative Example 7)
Spinning was performed in the same manner as in Example 1 except that the molar ratio of terephthalic acid and isophthalic acid was changed as shown in Table 1, and 1,4-cyclohexanedimethanol was changed to ethylene glycol. Fiber was obtained. Further, a tubular knitted fabric was produced using the fibers, and alkali resistance and light resistance were evaluated. Table 1 shows the results.

  Here, in Table 1, PET means polyethylene terephthalate, PBT means polybutylene terephthalate, Ny6 means nylon 6, and PP means polypropylene.

As shown in Table 1, the fibers of Examples 1 to 9 had yellowing resistance, and were excellent in strength retention in an alkaline solution environment and under ultraviolet irradiation.
In Comparative Example 1, the antioxidant was not added to the fiber, and the fiber was not a composite fiber, so that yellowing resistance and strength retention under ultraviolet irradiation were insufficient. In Comparative Example 2, since it was not a conjugate fiber, yellowing resistance and strength retention under ultraviolet irradiation were insufficient. Comparative Example 3 was inferior to Examples 1 and 4 in that yellowing resistance and strength retention under ultraviolet irradiation were poor because no antioxidant was added to the sheath component. In Comparative Example 4, since no antioxidant was added to the sheath component, the yellowing resistance and the strength retention under ultraviolet irradiation were inferior to Example 2. Comparative Example 5 was inferior to Example 3 in that no antioxidant was added to the sheath component, so that yellowing resistance and strength retention under ultraviolet irradiation were poor. In Comparative Example 6, since the diol component of the sheath component polyester resin contained ethylene glycol, the strength retention in an alkaline solution environment was insufficient. The fiber of Comparative Example 7 had insufficient strength retention in an alkaline solution environment because the diol component of the polyester resin was only ethylene glycol. In Comparative Example 8, since the copolymerization amount of isophthalic acid exceeded 50 mol%, the strength retention in an alkaline solution environment was insufficient.

  The conjugate fiber of the present invention can be used as a fiber product for any use in situations where alkali resistance and light resistance are required.For example, as a specific example, a food uniform, a medical uniform, a surgical gown, a disease gown, Clothing such as white robes, work clothes, aprons, hats, gloves; daily necessities such as futons, futon covers, macula covers, beds, bedspreads, sheets, bath mats, towels, face towels, body towels, cabinet towels, tablecloths, slippers, etc. Cleaning supplies such as table towels, mop threads, and rolling wipers; various living materials such as curtains, shower curtains, nets, door knob covers, carpets, food containers, and filters for air conditioner filters, air purifiers, and water filters. Materials: Humidifier transpiration plate, wallpaper, etc. It can be used to work materials.

While the preferred embodiment of the present invention has been described above, those skilled in the art will readily envision various changes and modifications within the apparent scope upon reading this specification. Accordingly, such changes and modifications are to be construed as being within the scope of the invention as defined by the appended claims.

Claims (8)

A polyester-based composite fiber comprising a component A which is a polyester resin and a component B which is a thermoplastic resin, wherein the polyester-based composite fiber satisfies the following (1) to (3).
(1) In the dicarboxylic acid component of the polyester resin (component A), 50 mol% or more of all dicarboxylic acid components is terephthalic acid, and 0 to 50 mol% of all dicarboxylic acid components are dicarboxylic acid components other than terephthalic acid. (1) Polyester resin wherein the diol component is cyclohexanedimethanol (2) The polyester resin (Component A) contains an antioxidant (3) Fiber of the polyester-based composite fiber In the cross section, the B component becomes the core, and the A component covers the entire circumference of the B component.   The polyester-based conjugate fiber according to claim 1, wherein the dicarboxylic acid component (I) is isophthalic acid.   2. The antioxidant is at least one antioxidant selected from the group consisting of hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants. Or the polyester-based conjugate fiber according to claim 2.   The polyester-based composite fiber, wherein the content of the antioxidant in the component A is 0.01 to 1.0% by mass based on the mass of the resin of the component A. The polyester composite fiber according to any one of the above.   The polyester according to any one of claims 1 to 4, wherein a composite ratio (mass ratio) of the component A and the component B is A: B = 50: 50 to 20:80. Based composite fiber.   6. The thermoplastic resin (component B) is at least one thermoplastic resin selected from the group consisting of a polyester resin, a polyamide resin, and an olefin resin. The polyester composite fiber according to any one of the above.   The polyester-based composite fiber according to any one of claims 1 to 6, wherein the polyester-based composite fiber has a single fiber fineness of 0.3 to 300 dtex. A fabric constituted by using the polyester-based composite fiber according to any one of claims 1 to 7.