JP2008248401A - Method for producing elastic fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an elastic fiber having excellent elastic recovery and stress relaxation characteristics. <P>SOLUTION: The method for producing the elastic fiber includes subjecting an elastic fiber composed of a polyether-ester block copolymer having (a) an aromatic dicarboxylic acid unit, (b) a 1,4-butanediol unit and/or 1,3-propanediol unit, and (c) a long-chain diol unit consisting essentially of a polyoxytrimethylene glycol to heat treatment and/or heat relaxing treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an elastic fiber, and more particularly, to a method for producing an elastic fiber comprising a specific polyetherester block copolymer having excellent stress relaxation characteristics and elastic recovery properties.

  The polyether ester block copolymer is a polymer copolymerized mainly using polybutylene terephthalate as a hard segment and polyoxyalkylene glycol ester as a soft segment. This copolymer has characteristics of rubber elastic bodies (silence, impact resistance, impact resilience, low temperature resistance, bending fatigue, etc.) and engineering plastic characteristics (durability, heat resistance, oil resistance, chemical resistance, It is a substance that has both ozone resistance and moldability). Various physical properties can be controlled by controlling the ratio of the hard segment and soft segment, so automobile parts, industrial parts, precision machine parts, electrical / electronic parts, textiles, films, household goods, etc. Widely used.

  In general, as a polyoxyalkylene glycol used in a polyetherester block copolymer, polyoxytetramethylene glycol (hereinafter sometimes abbreviated as “PTMG”) has been widely used. However, heat resistance, low temperature resistance and the like were not always satisfactory. In order to improve these problems, by selecting and combining each segment, polyoxytetramethylene glycol ester is used as a soft segment having a property of returning to its original state as an elastic body when pulled, that is, a good elastic recovery property. The polyether ester block copolymer used is disclosed (see Patent Document 1).

  In addition, by using polybutylene terephthalate as a hard segment, polyoxytrimethylene glycol ester as a soft segment, and a polyether ester block copolymer containing 60 to 90% by mass of the soft segment, the above-described elastic recovery is excellent. (See Patent Document 2).

As described in Patent Documents 1 and 2, the polyether ester block copolymer exhibits relatively good elasticity and can be melt-spun or molded. Industrial materials, automobiles, electrical applications, etc. are expected. In particular, a polyether ester block copolymer using polybutylene terephthalate as a hard segment and a polyoxytrimethylene glycol ester as a soft segment described in Patent Document 2 exhibits good elasticity, and thus is useful for elastic fibers. Material.
Japanese Patent No. 3164168 JP 2005-507967 A

  However, these polyetherester block copolymers have inferior stress relaxation properties (high stress relaxation) compared to conventional elastic fibers. For this reason, in order to put the polyether ester block copolymer of Patent Document 2 into practical use as an elastic fiber, it is required to improve stress relaxation characteristics (to reduce stress relaxation).

  Then, this invention makes it a subject to provide the manufacturing method of the elastic fiber excellent in the elastic recovery property and the stress relaxation characteristic.

  The inventors of the present invention have significantly improved stress relaxation characteristics by melt-spinning a polyether ester block copolymer using polybutylene terephthalate and polyoxytrimethylene glycol ester, and then performing heat treatment and / or heat relaxation treatment. It has been found that it can be improved, and the present invention has been completed.

  That is, the first embodiment of the present invention comprises (a) an aromatic dicarboxylic acid unit, (b) a 1,4-butanediol unit and / or a 1,3-propanediol unit, and (c) polyoxytrimethylene glycol. An elastic fiber comprising a polyetherester block copolymer having a main long-chain diol unit as a main component is subjected to a heat treatment and / or a thermal relaxation treatment, and provides a method for improving the stress relaxation characteristics of the elastic fiber, which is described above. It solves the problem.

  In addition, the second aspect of the present invention includes (a) an aromatic dicarboxylic acid unit, (b) 1,4 butanediol unit and / or 1,3-propanediol unit, and (c) polyoxytrimethylene glycol. A step of melt-spinning a polyetherester block copolymer having a long-chain diol unit mainly composed of an elastic fiber to obtain an elastic fiber, and a step of improving the stress relaxation characteristics of the elastic fiber by heat treatment and / or heat relaxation treatment The above-mentioned problems are solved by providing a method for producing an elastic fiber.

  In these embodiments, it is preferable to perform a thermal relaxation treatment after the heat treatment.

  In these embodiments, the heat treatment temperature is preferably 100 ° C. or higher and 220 ° C. or lower, and the thermal relaxation temperature is preferably 80 ° C. or higher and 200 ° C. or lower.

  In these embodiments, the elastic fiber is preferably melt-spun by containing a crystal nucleating agent. In this case, the crystal nucleating agent content ratio is 100% by mass of the polyether ester block copolymer. The content is more preferably 0.01% by mass or more and 20% by mass or less.

  According to a third aspect of the present invention, there is provided a fiber product using elastic fibers produced by using the methods of the first and second aspects of the present invention (including preferred embodiments) to solve the above problems. To do.

  According to the method of the present invention, the stress relaxation of the elastic fiber obtained from the specific polyetherester block copolymer can be greatly reduced, and the elastic recoverability can be improved. Therefore, the obtained elastic fiber can be used as, for example, textile products such as clothing fibers, industrial fibers and various filters, and is also useful as a textile product used for automobile interiors. .

  Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  The elastic fiber produced in the present invention comprises (a) an aromatic dicarboxylic acid unit, (b) 1,4 butanediol unit and / or 1,3-propanediol unit, and (c) polyoxytrimethylene glycol. It is obtained by melt spinning a polyether ester block copolymer (hereinafter also simply referred to as copolymer) containing a main long-chain diol unit.

  Generally, a polyetherester block copolymer is composed of a hard segment having crystallinity and a soft segment rich in molecular mobility as compared with the hard segment. In the present invention, the unit represented by the following formula (1) is a hard segment, and the unit represented by the following formula (2) is a soft segment in order to more clearly distinguish the hard segment and the soft segment. Yes.

（式（１）及び（２）中、Ｒ^１は各々独立に、ベンゼン核を持つ炭素環式化合物及び／又は非ベンゼノイド芳香族化合物由来の化学構造を表し、Ｒ^２は、トリメチレン基及び又はテトラメチレン基を表し、ｎは、１以上１０００以下の整数を表す。なお、ここで「ベンゼン核」とは、芳香族性を持つ炭素六員環を表し、「非ベンゼノイド芳香族化合物」とは、アズレンや芳香族性を示す複素環式化合物等の、ベンゼン核を持たないが芳香族性を示す化合物を表す。）

(In the formulas (1) and (2), each R ¹ independently represents a chemical structure derived from a carbocyclic compound having a benzene nucleus and / or a non-benzenoid aromatic compound, and R ² represents a trimethylene group and / or a tetra Represents a methylene group, and n represents an integer of 1 to 1,000, wherein “benzene nucleus” represents a carbon six-membered ring having aromaticity, and “non-benzenoid aromatic compound” (Represents compounds that do not have a benzene nucleus but exhibit aromaticity, such as azulene and aromatic compounds that exhibit aromaticity.)

The hard segment represented by the above formula (1) is a polyester comprising (a) an aromatic dicarboxylic acid unit and (b) 1,4-propanediol and / or 1,3-butanediol unit. The soft segment represented by the above formula (2) is a polyether ester composed of (a) an aromatic dicarboxylic acid unit and (c) a long-chain diol unit mainly composed of polyoxytrimethylene glycol. In addition, in some known documents, a soft segment is represented only by a long-chain diol unit that is a main component.
Hereinafter, the raw material and manufacturing method of the elastic fiber will be described in detail.

1. Polyetherester block copolymer raw material (a) Aromatic dicarboxylic acid unit
The raw material for the aromatic dicarboxylic acid unit (a) (hereinafter referred to as “(a ′) aromatic dicarboxylic acid component”) of the present invention is generally used as a raw material for polyester, particularly as a raw material for a polyether ester block copolymer. For example, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, isophthalic acid, phthalic acid, di Examples include phenoxyethanedicarboxylic acid and 5-sulfoisophthalic acid. Among these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferable, and terephthalic acid is more preferable. These aromatic dicarboxylic acids are usually used alone, but two or more kinds may be used in combination. Moreover, when using the alkyl ester of aromatic dicarboxylic acid, dimethyl ester, diethyl ester, etc. of said aromatic dicarboxylic acid are used, for example. Of these, dimethyl terephthalate and 2,6-dimethyl naphthalene dicarboxylate are particularly preferred.

(B) 1,3-propanediol and / or 1,4-butanediol unit The raw material of the (b) 1,3-propanediol and / or 1,4-butanediol unit of the present invention (hereinafter referred to as “(b ′ )) 1,3-propanediol and / or 1,4-butanediol component)), it is usual to use 1,3-propanediol or 1,4-butanediol alone. You may use together. Among these, it is preferable to use 1,4-butanediol alone.

(C) Long-chain diol unit (c) A raw material of a long-chain diol unit (hereinafter referred to as “(c ′) long-chain diol component”) which is a part of the constituent unit of the soft segment in the polyetherester block copolymer of the present invention For example, polyoxytrimethylene glycol having the chemical structural formula of the following formula (3) is used.

（上記式（３）中、ｎは１以上１０００以下の整数を表す。）

(In the above formula (3), n represents an integer of 1 or more and 1000 or less.)

  The number average molecular weight (Mn) of the polyoxytrimethylene glycol used in the present invention is usually 400 or more, more preferably 1000 or more, further preferably 1500 or more, most preferably 2000 or more, and usually 6000 or less, preferably It is 4000 or less, more preferably 3500 or less. When this number average molecular weight is less than 400, the melting point drop becomes severe and the heat resistance may be adversely affected. On the other hand, when the number average molecular weight exceeds 6000, the viscosity of the polyoxytrimethylene glycol increases, so that phase separation in the polyetherester block copolymer using the polyoxytrimethylene glycol becomes remarkable, and the physical properties of the copolymer molded product deteriorate. There is a case.

  The “number average molecular weight (Mn)” used herein means that the hydroxyl group at the end of polyoxyalkylene glycol such as polyoxytrimethylene glycol is esterified with phthalic anhydride and unreacted phthalic anhydride is decomposed into phthalic acid. The hydroxyl value was determined by reverse titration (terminal group titration method) with an alkali such as an aqueous sodium hydroxide solution, and was calculated from the value.

The polyoxytrimethylene glycol can be synthesized by dehydrating condensation polymerization of 1,3-propanediol or ring-opening polymerization of trimethylene oxide, but the latter method is expensive because trimethylene oxide as a raw material is expensive. Therefore, it is preferable to synthesize by the dehydration condensation polymerization of 1,3-propanediol in the former method. The dehydrated polycondensation product of 1,3-propanediol is, for example, as disclosed in JP-A-2004-182974, 1,3
-It can be synthesized by a known method such as a dehydration condensation reaction of propanediol in the presence of a catalyst comprising an acid and a base.

  The long-chain diol component (c ′) of the present invention is mainly composed of the polyoxytrimethylene glycol, but may be partially substituted with other polyoxyalkylene glycol as necessary. Examples of the polyoxyalkylene glycol used for such substitution include polyoxyethylene glycol, polyoxy (1,2-propylene) glycol, polyoxytetramethylene glycol, block or random copolymer of ethylene oxide and propylene oxide, and ethylene oxide and THF. A block or random copolymer, polyoxy (2-methyl-1,3-propylene) glycol, polyoxypropylene diimide diacid and the like can be mentioned. However, in the present invention, since the polyoxytrimethylene glycol is mainly used as the (c ′) long-chain diol component, the polyoxytrimethylene glycol is included in the total mass of the (c ′) long-chain diol component. Regarding the content of trimethylene glycol, the lower limit is usually 60% by mass or more, preferably the lower limit is 70% by mass or more, more preferably the lower limit is 80% by mass or more, and the upper limit is usually 100% by mass or less. If the content of the polyoxytrimethylene glycol is too smaller than the above, the effects of improving the elastic recovery and stress relaxation characteristics of the present invention may not be exhibited.

2. Production and Physical Properties of Polyether Ester Block Copolymer Polyether ester block copolymer can be produced by any known method, for example, a conventional method for producing a copolyester can be employed. Specifically, (a ′) aromatic dicarboxylic acid component, excess (b ′) 1,3-propanediol and / or 1,4-butanediol component and (c ′) long-chain diol component are used as catalyst. A method of transesterification in the presence and then polycondensing the reaction product obtained under reduced pressure, or (a ′) an aromatic dicarboxylic acid component and (b ′) 1,3-propanediol and / or 1, A method in which a 4-butanediol component and (c ′) a long-chain diol component are esterified in the presence of a catalyst, and then the resulting reaction product is polycondensed under reduced pressure, or a short-chain polyester (for example, polybutylene) Terephthalate), add other aromatic dicarboxylic acid component and (c ') long chain diol component to polycondensate, add other copolyester using twin screw extruder etc. Este Any method may be used.

  Examples of the common catalyst for the transesterification reaction or the esterification reaction and the copolymerization reaction include, for example, tetra (isopropoxy) titanate, tetraalkyl titanates represented by tetra (n-butoxy) titanate, these tetraalkyl titanates and alkylene glycols. Preferred is a Ti-based catalyst such as a reaction product, a partial hydrolyzate of tetraalkyl titanate, a metal salt of titanium hexaalkoxide, a carboxylate of titanium, a titanyl compound, mono-n-butyl monohydroxytin oxide, Mono-n-butyltin triacetate, mono-n-butyltin monooctylate, monoalkyltin compounds such as mono-n-butyltin monoacetate, di-n-butyltin oxide, di-n-butyltin diacetate, diphenyltin oxide, Phenyl tin diacetate, di -n- butyl tin Geo lactylate etc. dialkyl (or diaryl) tin compounds. In addition, metal compounds such as Mg, Pb, Zr, Zn, Sb, Ge, and P are useful. These catalysts may be used alone or in combination of two or more. In particular, when used alone, tetraalkyl titanate is preferred. Moreover, when using in combination, it is preferable to use tetraalkyl titanate and magnesium acetate. These catalysts may be added at the start of the transesterification or esterification reaction and then added again during the copolymerization reaction.

  The amount of the catalyst to be added is usually 0.0005% by mass or more, preferably 0.001% by mass or more, and more preferably 0.003% by mass or less, based on the polyether ester block copolymer to be produced. The upper limit is usually 0.5% by mass or less, and preferably the upper limit is 0.3% by mass or less. At this time, if the amount of the catalyst to be added is less than the above lower limit, the reaction may not easily proceed and the productivity may be deteriorated. If the amount exceeds the above upper limit, the produced polyetherester block copolymer may be colored or co-polymerized. There are cases where the surface appearance of the polymer is deteriorated due to bumps or the like.

  The content of the long-chain diol unit mainly composed of polyoxytrimethylene glycol in the polyether ester block copolymer obtained by polymerization is generally 50% by mass or more, Preferably it is 60 mass% or more, More preferably, it is 65 mass% or more, Most preferably, it is 70 mass% or more, Usually, 90 mass% or less, Preferably it is 85 mass% or less, More preferably, it is 80 mass% or less. At this time, if the content of (c) is below the lower limit, the properties as an elastic body derived from the soft segment of the copolymer may be reduced. On the other hand, if the content of (c) exceeds the upper limit, the crystallinity of the copolymer is lowered and the copolymer strand cannot be cut during the production of the copolymer, so that the pellet may not be obtained. .

  The inherent viscosity of the polyetherester block copolymer is usually 0.80 dl / g or more, preferably 1.00 dl / g or more, usually 4.00 dl / g or less, preferably 3.00 dl / g or less. It is. At this time, if the inherent viscosity is lower than the lower limit, the fiber physical properties may be remarkably lowered. On the other hand, if the upper limit of the inherent viscosity is exceeded, the fluidity of the copolymer is lowered, and thus melt molding may be difficult.

Here, the inherent viscosity is obtained by dissolving the copolymer in a solvent in which phenol and 1,1,2,2-tetrachloroethane are mixed at a ratio of 1: 1, and the natural viscosity of the relative viscosity (η _rel ) at 30 ° C. of this solution. A value obtained by dividing the logarithm by the solution concentration (C) as in the following formula (I).
η _inh = (ln η _rel ) / C Formula (I)

  Further, the terminal carboxyl group amount (AV) of the polyetherester block copolymer is usually 70 eq / ton or less, preferably 60 eq / ton or less, more preferably 50 eq / ton or less, and most preferably 40 eq / ton or less. . At this time, if AV exceeds the upper limit, long-term stability such as hydrolysis resistance may be remarkably reduced.

  Depending on the production conditions, the copolymer of the present invention may be produced as a copolymer, and then the crystallization rate is low, so that the strands are fused, so that cutting cannot be performed. Detrimental effects such as fusion may occur. Also, when spinning as will be described later, since the crystallization speed is slow, there are cases in which yarn breakage occurs during molding, or the fibers stick together and become difficult to unravel. Therefore, in the present invention, it is preferable to add a crystal nucleating agent.

  The type of crystal nucleating agent used is not limited, but examples include talc, kaolinite, montmorillonite, synthetic mica, clay, zeolite, silica, zinc oxide, magnesium oxide, titanium oxide, boron nitride, and silicon oxide. Inorganic compounds: sodium benzoate, potassium benzoate, calcium benzoate, sodium stearate, potassium stearate, calcium stearate, sodium montanate, potassium montanate, calcium montanate, sodium palmitate, potassium palmitate, calcium palmitate Organic carboxylic acid metal salts such as stearic acid amide, palmitic acid amide, erucic acid amide, and the like; low density polyethylene, high density polyethylene, polyolefin such as polypropylene, and the like Polyolefin wax containing olefins; polyesters such as semi-aromatic polyesters (polybutylene terephthalate, etc.), aliphatic polyesters, and oligomers; sodium or potassium salts of ethylene- (meth) acrylic acid copolymers; benzylidene sorbitol and its derivatives; sodium -Phosphate metal salts such as -2,2'-methylenebis (4,6-di-t-butylphenyl) phosphate; “(Meth) acrylic acid” refers to methacrylic acid and / or acrylic acid.

  Among them, as the crystal nucleating agent, organic carboxylic acid metal salts such as sodium stearate and sodium montanate, polyethylene, polypropylene, polyethylene wax, polypropylene wax and the like are preferable.

  The compounding amount of the crystal nucleating agent is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and usually 20% by mass or less, preferably 15% by mass or less. More preferably, it is the range of 10 mass% or less. If the blending amount of the crystal nucleating agent is too small, the effect of promoting the crystallization speed may not be obtained. Conversely, if the blending amount of the crystal nucleating agent is too large, the fiber surface may be roughened as a foreign substance, or the mechanical properties may be deteriorated. It may be damaged.

  The timing of introducing the crystal nucleating agent is arbitrary. For example, it may be charged together with the raw material during the production of the copolymer, or may be arbitrarily charged in the middle of the reaction. In addition, after the copolymer is produced, it is kneaded using an extruder or the like, or introduced into a molding machine together with the copolymer pellets and mixed together during the melt spinning described later. Also good.

  As other additional components, polyfunctional components such as polycarboxylic acids, polyfunctional hydroxy compounds, and oxy acids may be copolymerized as a part of dicarboxylic acid or diol. The polyfunctional component effectively acts as a thickening component, and the content in the copolymer is preferably 0 mol% or more and 3 mol% or less. When there is too much content of a polyfunctional component, the polyether ester block copolymer to produce | generate may gelatinize and is unpreferable. Examples of such polyfunctional components include trimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, butanetetracarboxylic acid, glycerin, trimethylolpropane, pentaerythritol and esters thereof, acid An anhydride etc. can be mentioned. Any one of these may be used alone, or two or more may be used in any combination and ratio.

  Further, an antioxidant can be added at any time during or after the production of the polyetherester block copolymer. In particular, when polyoxytrimethylene glycol is exposed to high temperatures, for example, when it enters a copolymerization reaction, in order to prevent oxidative degradation of polyoxyalkylene glycol, the copolymerization reaction is not inhibited and the function of the catalyst is impaired. Unless otherwise, it is desirable to add an antioxidant. These antioxidants include, for example, phosphoric acid, phosphorous acid aliphatic, aromatic or alkyl group-substituted aromatic esters, hypophosphorous acid derivatives, phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonate, dialkyl. Sulfur such as phosphorus compounds such as pentaerythritol diphosphite and dialkylbisphenol A diphosphite, phenol derivatives such as hindered phenol compounds, thioethers, dithiosates, mercaptobenzimidazoles, thiocarbanilides, thiodipropionates, etc. Including compounds, tin compounds such as tin malate and dibutyltin monoxide, and the like can be used. Any one of these may be used alone, or two or more may be used in any combination and ratio.

  These antioxidants are used in an amount of usually 0.001 parts by mass or more, preferably 0.01 parts by mass or more, and usually 3 parts by mass or less, preferably 2 with respect to 100 parts by mass of the polyetherester block copolymer. It is below mass parts. At this time, if the amount of the antioxidant used is less than the lower limit, the effect of the antioxidant may be difficult to be exhibited. If the amount exceeds the upper limit, the produced polyetherester block copolymer is colored. In some cases, the surface appearance of the copolymer molded product may be deteriorated due to irregularities.

3. Production of elastic fiber by melt spinning The obtained copolymer is made into an elastic fiber by melt spinning. There is no restriction | limiting in particular in the method of melt spinning, A well-known melt spinning method can be used.

  FIG. 1 is a schematic view showing an embodiment of a melt spinning apparatus 100 used in the present invention. The pelletized copolymer is discharged from the nozzle 11 after being melted by heating. The fibrous copolymer exiting from the nozzle 11 is rapidly cooled and solidified by passing through the cooling tower 12. Thereafter, the oil is applied with oil by the oiling roller 13, passes through the first guide roller 14, the godet roller 15, and the second guide roller 16, and is wound around the winder roller 18.

  The spinning temperature (nozzle temperature) in the above step is preferably set to the melting point of the copolymer + 20 ° C. to 70 ° C. If the melting point is lower than + 20 ° C, the breaking elongation of the fiber is low, and if it is 70 ° C or higher, it is difficult to wind the fiber. The spinning speed is preferably 200 m / min to 1500 m / min. If it is less than 200 m / min, the elastic recoverability deteriorates, and if it exceeds 1500 m / min, the elongation at break becomes low.

  The stretch ratio of the obtained elastic fiber is appropriately changed by changing the rotation speeds of the godet roller 15 and the winder roller 18. In the present invention, the film is usually stretched so that the stretching ratio is 1.0 to 4.0, preferably 1.0 to 2.0. When this range is exceeded, the elongation at break, elastic recovery, and stress relaxation may deteriorate.

4). Heat treatment and heat relaxation treatment of elastic fiber The elastic fiber obtained in the melt spinning step is sent to a step of heat treatment and / or heat relaxation treatment. By undergoing the heat treatment and / or the thermal relaxation treatment, the stress relaxation of the elastic fiber can be reduced.

  FIG. 2 is a schematic diagram showing an embodiment of the unwinding heat treatment apparatus 200 used for heat treatment and / or heat relaxation treatment. The elastic fiber wound around the winder roller 18 in the melt spinning process is attached to the sample holder 21, and the elastic fiber is sent out by setting the friction roller 22. The sent elastic fiber passes through the first feed roller 23 and then passes through the second feed roller 24 and the third feed roller 26. A heater 25 is provided between the second feed roller 24 and the third feed roller 26, and heat treatment or thermal relaxation treatment is performed when the elastic fiber passes through the heater 25. The elastic fiber coming out of the heater 25 is wound around the winder roller 27.

  In the present invention, the term “heat treatment” refers to applying heat to an elastic fiber in a state that does not apply tension during stretching or conversely bend, and an unwinding heat treatment apparatus as shown in FIG. In the case of using 200, the heater 25 is passed through the elastic fiber while keeping the speeds of the second feed roller 24 and the third feed roller 26 the same.

  On the other hand, in the present invention, “thermal relaxation treatment” refers to applying heat in a state where tension is released (slightly bent) when the elastic fiber passes through the heater 25, as shown in FIG. In the case where the unraveling heat treatment apparatus 200 is used, it means that the heater 25 is passed through the elastic fiber in a state where the speed of the second feed roller 24 is faster than the speed of the third feed roller 26. The relaxation rate was determined by the ratio between the rotation speed of the sample holder 21 and the rotation speed of the sample holder 21 when wound around the winder roller 27. The relaxation rate is preferably 10% or more, more preferably 20% or more, and 60% or less, more preferably 50% or less. If it is smaller than the above range, the elastic recoverability may not be improved, and if it is larger than the above range, it may be difficult to wind the fiber.

  The difference between the heat treatment using the unraveling heat treatment apparatus 200 and the thermal relaxation process is only the difference between the speed of the second feed roller 14 and the speed of the third feed roller 26. By doing so, both heat treatment and thermal relaxation treatment can be performed. Therefore, when both the heat treatment and the thermal relaxation treatment are performed, the two heat treatment apparatuses 200 may be arranged side by side to perform the heat treatment and the heat relaxation treatment continuously, or one of the treatments is performed to perform the winder roller 27. The other processing may be performed by returning the elastic fiber wound up to the sample holder 21 and changing the speed of the second feed roller 24 and / or the third feed roller 26 to pass the fiber through the heater 25 again.

  In the present invention, in order to reduce the stress relaxation of the elastic fiber, only heat treatment may be performed, or only thermal relaxation treatment may be performed. When both treatments are performed, either treatment may be performed first. However, in the present invention, it is preferable to perform the thermal relaxation treatment after the heat treatment because the stress strain in the fiber can be eliminated step by step and the stress relaxation characteristics can be further improved. Further, the heat treatment step and the heat relaxation step may be performed by unwinding the wound fiber after melt spinning to obtain the fiber, or continuously without winding the fiber by performing melt spinning. May be applied. In that case, after extending | stretching a fiber, you may install a heater in the way until a fiber is wound, and may perform heat processing or a heat relaxation process. Further, heat treatment or thermal relaxation may be performed by bringing the fiber into contact with a heatable godet roller.

  In the present invention, the heat treatment temperature is preferably 100 ° C. or higher and 220 ° C. or lower, while the thermal relaxation treatment temperature is preferably 80 ° C. or higher and 200 ° C. or lower. When the temperature is lower than the above range, the effect of improving the stress relaxation characteristics tends to be small. On the other hand, if the temperature exceeds the above range, the fiber may be softened and thread breakage may occur.

  The elastic fiber made of a polyetherester block copolymer having improved stress relaxation properties using the method of the present invention as described above has low stress relaxation and excellent elastic recovery. It can be used as textile products such as industrial fibers, industrial fibers and various filters, and is also useful as a textile product used in automobile interiors.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples unless the gist of the present invention is exceeded. In addition, in the following description, the description of “parts” all represents “parts by mass”, and the description of “Mn” represents “number average molecular weight”.

In addition, the inherent viscosity (η _inh ) of the copolymer shown in the production example is a value obtained by the following procedure using an Ubbelohde viscometer (Automatic Viscometer DT552 manufactured by Centec Co., Ltd.).
That is, a mixed solvent of phenol / tetrachloroethane (mass ratio 1/1) was used, and a copolymer to be measured was dissolved therein to prepare a solution (polymer solution) having a concentration of 0.5 g / dl. At 30 ° C., the dropping time of the polymer solution having a concentration of 0.5 g / dl and the falling time of the solvent alone were measured, and the solution viscosity (η _inh ) was determined by the following formula (I).
η _inh = (ln η _rel ) / C Formula (I)
However, η _rel = (Polymer solution dropping seconds) / (Solvent dropping seconds)
C = Solution concentration

[I. Production of copolymer]
(Production Example 1: Production of polyoxytrimethylene ether glycol)
Distilled and purified 1,3-propanediol (50 g) was charged into a 100 ml four-necked flask equipped with a distillation tube, a nitrogen introduction tube, a thermometer and a stirrer while supplying nitrogen at 100 Nml / min. To this was added 0.0348 g of sodium carbonate, and then 0.678 g of concentrated sulfuric acid (95%) was slowly added with stirring. The flask was immersed in an oil bath and heated to 162 ° C. The liquid temperature was adjusted to 162 ° C. ± 2 ° C. and allowed to react for an arbitrary time, and then the flask was removed from the oil bath and allowed to cool to room temperature. Water produced during the reaction was distilled off accompanying nitrogen. The reaction solution cooled to room temperature was transferred to a 300 ml eggplant type flask using 50 g of tetrahydrofuran, 50 g of demineralized water was added thereto, and the mixture was gently refluxed for 1 hour to hydrolyze the sulfate ester. After cooling to room temperature and cooling, the lower layer (water tank) separated into two layers was removed. After adding 0.5 g of calcium hydroxide to the upper layer (oil layer) and stirring at room temperature for 1 hour, 50 g of toluene was added and heated to 60 ° C., and tetrahydrofuran, water and toluene were distilled off under reduced pressure. The obtained oil layer was dissolved in 100 g of toluene and filtered through a 0.45 μm filter to remove insoluble matters. The filtrate was heated to 60 ° C. and vacuum-dried for 6 hours to obtain the desired polyoxytrimethylene glycol (PO3G). The molecular weight was adjusted by changing the time of the dehydration condensation reaction, and two types of PO3G ((A): Mn = 2166, (B): Mn = 3390) were obtained.

(Production Example 2: Polymerization of polyetherester block copolymer 1)
65% by mass of polyoxytrimethylene glycol (PO3G (A), Mn = 2166)
The contained polyetherester block copolymer 1 was produced in the following manner.

  That is, a reactor equipped with a nitrogen inlet and a vacuum port was charged with 42.6 parts of terephthalic acid, 35.8 parts of 1,4-butanediol, and 97.5 parts of PO3G (A) as copolymerization components. There, 0.027 part of tetra-n-butyl titanate (25 ppm in terms of mass ratio in terms of titanium atom with respect to the produced copolymer) and 0.017 part of magnesium acetate tetrahydrate (magnesium atom with respect to the produced copolymer) 13 ppm in terms of mass ratio in terms of conversion, and the molar ratio of magnesium atom to titanium atom was 1.0) dissolved in a small amount of 1,4-butanediol. After substituting the inside of the system with nitrogen, the temperature was raised from 190 ° C. to 225 ° C. over 1 hour under nitrogen and maintained at 225 ° C. for 2 hours to carry out the esterification step. Thereafter, 0.053 part of tetra-n-butyl titanate (50 ppm in terms of mass ratio in terms of titanium atom to the copolymer to be produced) and 0.27 part of Irganox 1330 (antioxidant manufactured by Ciba Geigy Corporation) -It mixed with butanediol, and it shifted to the polycondensation process succeedingly.

In the polycondensation step, first, the pressure was gradually reduced from normal pressure to 0.07 kPa over 50 minutes, and at the same time, the polymerization temperature was raised to 245 ° C. Thereafter, 0.07 kPa was maintained, and when the predetermined stirring torque was reached, the reaction was terminated, and the content (the obtained polyetherester block copolymer) was taken out and pelletized. The manufactured polyether ester block copolymer 1 had an inherent viscosity (η _inh ) of 1.71 dl / g and a polymer terminal carboxyl group amount (AV) of 21 eq / ton.

(Production Example 3: Polymerization of Polyether Ester Block Copolymer 2)
Polyether ester block copolymer 2 containing 73% by mass of PO3G (A) (Mn = 2166) was obtained from Production Example 2 above with 33.9 parts of terephthalic acid, 25.9 parts of 1,4-butanediol, and A pellet was produced in the same manner as above except that 109.5 parts of PO3G (A) was charged. The manufactured polyether ester block copolymer 2 had an inherent viscosity (η _inh ) of 1.74 dl / g and a polymer terminal carboxyl group amount (AV) of 20 eq / ton.

(Production Example 4: Polymerization of Polyether Ester Block Copolymer 3)
Polyether ester block copolymer 3 containing 73% by mass of PO3G (B) (Mn = 3390) was obtained from Production Example 2 from 32.7 parts of terephthalic acid, 26.2 parts of 1,4-butanediol, and A pellet was produced in the same manner as above except that 109.5 parts of PO3G (B) was charged. The manufactured polyether ester block copolymer 3 had an inherent viscosity (η _inh ) of 1.75 dl / g and a polymer terminal carboxyl group amount (AV) of 22 eq / ton.

(Production Example 5: Polymerization of polyetherester block copolymer 4)
In the same manner as in copolymer 1 described in Production Example 2, 2 parts of the copolymer were further polymerized to produce a polyethylene wax (Accumist-B6 manufactured by Honeywell). The manufactured polyether ester block copolymer 4 had an inherent viscosity (η _inh ) of 1.70 dl / g and a polymer terminal carboxyl group amount (AV) of 20 eq / ton.

[II. Production and evaluation of elastic fiber]
After the copolymer of the production example was dried under reduced pressure, spinning was performed using a twin-screw extruder and the melt spinning apparatus 100 of FIG. 1 to obtain fibers. The specifications and operating conditions of the used twin screw extruder and melt spinning machine are shown below.
<Twin screw extruder>
・ Specifications: 15mmφ, L / D = 30
・ Screw rotation speed: 150rpm
・ Temperature condition: Melting while heating stepwise from 100 ℃ to 200 ℃ ・ Pressure condition: 8MPa (as head pressure)
-Discharge rate: 2.22 g / min <melt spinning machine>
・ Specifications: Nozzle 0.6mmφ, L / D = 6, Single hole (round section)
Godet roller 150mmφ × 300mmL (chrome plating)
Bobbin 83mmφ × 58mmL (paper tube)
Molding temperature: listed in Table 1 Cooling temperature (cooling tower): 10 ° C
Oil: Anionic surfactant aqueous solution Spinning speed (pretension roller): 750 m / min Stretch ratio: 1.3

  The fibers obtained in the spinning machine were heat-treated at the treatment temperatures shown in Table 1 as Examples 1 to 8 using the unwinding heat treatment apparatus 200 shown in FIG. Further, some of the heat-treated fibers (Examples 3 and 4) were also subjected to thermal relaxation treatment at the treatment temperatures shown in Table 1 using the unwinding heat treatment apparatus 200 of FIG. Neither heat treatment nor thermal relaxation treatment was performed on the fibers of Comparative Examples 1 to 3.

During the heat treatment, the rotational speed (m / min) of each roller in the unwinding heat treatment apparatus 200 of FIG. 2 was set as shown in (X) below, and the fiber was operated so that no tension was applied to the fiber. In the following equations, S represents the sample holder 21, F1 represents the first feed roller 23, F2 represents the second feed roller 24, F3 represents the third feed roller 26, and W represents the winder roller 27.
S / F1 / F2 / F3 / W = 100/120/105/100/100 (X)

Further, during the thermal relaxation treatment, the roller rotation speed was set as (Y).
S / F1 / F2 / F3 / W = 100/120/105/60/60 (Y)

Furthermore, the relaxation rate in the thermal relaxation process was calculated as follows from the rotation speeds of the sample holder (S) and the winder roller (W) during the thermal relaxation process.
Relaxation rate (%) = (S−W) / S × 100

  About the obtained fiber, breaking strength, breaking elongation, elastic recoverability, and stress relaxation were evaluated. The evaluation method is as follows. The results are shown in Table 2.

(Breaking strength / breaking elongation)
The fiber obtained by the above procedure was subjected to a tensile test under the conditions of a sample length of 50 mm and a tensile speed of 500 mm / min using a desktop material testing machine STA-1225 manufactured by Orientec Co., Ltd. Asked.

(Elastic recovery and stress relaxation)
Measurement was performed using a desktop material testing machine STA-1225 manufactured by Orientec Co., Ltd. The fiber obtained by the above procedure was stretched to 300% at a sample length of 50 mm (E ₀ ) and a speed of 500 mm / min, and then returned to the original length at the same speed. This was repeated 5 times. Thereafter, the film was again stretched to 300% at the same speed and held at 300% for 30 seconds. The sample length (E) when the stress of this time appeared was calculated | required, and elastic recovery property was computed by following Formula.
Elastic recovery (%) = {(E−E ₀ ) / E ₀ } × 100
Moreover, the stress change for 30 seconds under 300% elongation was read, and the stress relaxation was calculated by the following formula.
Stress relaxation (%) = {(S ₀ −S) / S ₀ } × 100
(S ₀ : Stress when reaching 300% elongation S: Stress 300 seconds after reaching 300% elongation)

  As shown in Table 2, the elastic fibers of the examples having improved stress relaxation properties using the method of the present invention not only showed good results in the tensile test, but also had low stress relaxation and high elastic recovery. Showed sex. When comparing the same fibers with different heat treatment temperatures, the higher the heat treatment temperature, the smaller the stress relaxation and the better the elastic recovery. In addition, the fibers of Example 3 and Example 4 that were subjected to a thermal relaxation treatment subsequent to the heat treatment exhibited smaller stress relaxation compared to Examples 1 and 2 where the heat treatment temperature was the same. Further, Example 6 in which a crystal nucleating agent was added to the copolymer was particularly excellent in stress relaxation characteristics. On the other hand, although the fibers of Comparative Examples 1 to 3 had good elasticity recovery properties, the stress relaxation characteristics were significantly inferior.

  Although the present invention has been described with reference to the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The invention can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification, and a method for producing elastic fibers accompanying such a change is also included in the technical scope of the present invention. It must be understood as a thing.

It is a schematic diagram which shows one form of the melt spinning apparatus 100 used for this invention. It is a schematic diagram which shows one form of the unwinding heat processing apparatus 200 used for heat processing and / or a thermal relaxation process.

Explanation of symbols

11 Nozzle 12 Cooling Tower 13 Oiling Roller 14 First Guide Roller 15 Godet Roller 16 Second Guide Roller 17 Friction Roller 18 Winder Roller 21 Sample Holder 22 Friction Roller 23 First Feed Roller 24 Second Feed Roller 25 Heater 26 Third Feed Roller 27 Winder roller 100 Melt spinning device 200 Unwinding heat treatment device

Claims (8)

(A) an aromatic dicarboxylic acid unit, (b) a 1,4-butanediol unit and / or a 1,3-propanediol unit, and (c) a long-chain diol unit mainly composed of polyoxytrimethylene glycol. A method for improving stress relaxation characteristics of an elastic fiber, comprising subjecting an elastic fiber comprising a polyetherester block copolymer to a heat treatment and / or a thermal relaxation treatment. (A) an aromatic dicarboxylic acid unit, (b) a 1,4-butanediol unit and / or a 1,3-propanediol unit, and (c) a long-chain diol unit mainly composed of polyoxytrimethylene glycol. An elastic fiber comprising a step of melt spinning a polyetherester block copolymer to obtain an elastic fiber, and a step of improving the stress relaxation property of the elastic fiber by heat treatment and / or heat relaxation treatment Manufacturing method. The method according to claim 1, wherein the thermal relaxation treatment is performed after the heat treatment. The method according to claim 1, wherein a temperature of the heat treatment is 100 ° C. or higher and 220 ° C. or lower. The method according to claim 1, wherein the thermal relaxation temperature is 80 ° C. or higher and 200 ° C. or lower. The manufacturing method according to claim 1, wherein the elastic fiber is melt-spun by containing a crystal nucleating agent. The method according to claim 6, wherein the content ratio of the crystal nucleating agent is 0.01% by mass or more and 20% by mass or less with respect to 100% by mass of the polyether ester block copolymer. The textiles using the elastic fiber manufactured using the method of any one of Claims 1-7.

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