Liquid crystalline polyester fiber and fiber structure

Abstract

Provided is a liquid crystalline polyester fiber that has sufficient mechanical properties while being imparted with traceability. The liquid crystalline polyester fiber has a bio-based content ratio of 1% or more, and contains a liquid crystalline polyester which includes a structural unit derived from at least one aromatic hydroxy carboxylic acid, and in which: the total content of structural units derived from non-fully aromatic monomers and structural units derived from non-linear aromatic monomers is less than 5 mol% of the total content of all structural units; and the content of structural units derived from heterocyclic aromatic monomers is less than 3 mol% of the total content of all structural units.

Description

Liquid crystal polyester fibers and fiber structures Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-104198, filed on June 27, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a liquid crystal polyester fiber and a fiber structure at least partially comprising the liquid crystal polyester fiber.

[0003] Liquid crystal polyester fibers are synthetic fibers made of liquid crystal polyesters with rigid molecular structures, and have high strength and high elastic modulus due to the highly oriented molecular chains. In addition to the characteristics of high strength and high elastic modulus, liquid crystal polyester fibers also have excellent dimensional stability, and are therefore used in various industrial material applications such as ropes and nets.

[0004] In recent years, there has been an increasing demand for bioplastics made from biomass-derived raw materials with the aim of reducing environmental impact. The use of biomass-derived monomers is also being promoted in liquid crystalline polyesters, which are the raw material for liquid crystalline polyester fibers. For example, Patent Document 1 (WO 2013 / 092667) discloses a wholly aromatic liquid crystalline furandicarboxylic acid-based polyester obtained from a monomer mixture containing 2,5-furandicarboxylic acid, p-hydroxybenzoic acid, an aromatic diol, and 5 to 40 mol % of an aromatic monocarboxylic acid selected from vanillic acid, ferulic acid, salicylic acid, and syringic acid, or a combination thereof.

[0005] Patent Document 2 (JP 2012-122023 A) discloses a liquid crystal polyester comprising a dicarboxylic acid component (A), a glycol component (B), and an aromatic hydroxycarboxylic acid component (C), in which the copolymerization amount of (C) is 40 to 90 mol % and the copolymerization amount of 2,5-furandicarboxylic acid is 5 to 30 mol % relative to 100 mol % in total of (A), (B), and (C).

[0006] Patent Document 3 (JP 2006-63316 A) discloses a rigid polymer characterized by being composed of a homopolymer made of any one of a biologically-derived rigid compound having two or more reactive functional groups and being polymerizable, a derivative of the biologically-derived rigid compound, a hydrolysate of the biologically-derived rigid compound, a derivative of the hydrolysate, or a substance extracted from a bioresource, or a copolymer made of any two or more of the above.

[0007] Patent Document 4 (Japanese Patent Laid-Open Publication No. 2004-250700) discloses a bio-liquid crystal polymer that is made from a biological compound or a derivative thereof, exhibits liquid crystallinity under certain conditions, and is characterized by being biocompatible.

[0008] International Publication No. 2013 / 092667 Japanese Patent Application Laid-Open No. 2012-122023 Japanese Patent Application Laid-Open No. 2006-63316 Japanese Patent Application Laid-Open No. 2004-250700

[0009] On the other hand, liquid crystal polyester fibers are used as materials for fishing nets, marine ropes, etc. used in the ocean, but fishing nets, marine ropes, etc. are often released into the environment as marine plastic waste, accounting for a large proportion of marine plastic waste and becoming a major problem. Recently, efforts such as recycling discarded fishing nets have been expanding, and there is a growing momentum to reduce fishing waste such as fishing nets and marine ropes that are released into the environment as marine plastic waste.

[0010] In order to build a system to reduce fishing waste, it is necessary to hold manufacturers and users of fishing nets, marine ropes, etc. responsible for their collection. To achieve this, it is thought that providing traceability to fishing nets, marine ropes, etc. will be effective in making it possible to identify manufacturers and users from fishing waste.

[0011] Methods for imparting traceability to fishing nets, marine ropes, etc. include methods for distinguishing them by giving unique characteristics to the product form, such as their weave or rope structure, or by attaching labels such as tags. However, these methods have the risk of making them impossible to distinguish if they break and separate during use. Therefore, methods for imparting traceability to the liquid crystalline polyester fiber itself that constitutes the fishing nets, marine ropes, etc. have been considered, but no effective method for imparting traceability to liquid crystalline polyester fiber has been proposed to date.

[0012] One method of imparting traceability to liquid crystalline polyester fibers is to color them by mixing them with pigments, etc., but mixing pigments, etc., reduces mechanical properties such as strength. Therefore, the present inventors focused on the biobased content, which allows one to determine the extent to which biomass-derived monomers are used in synthesis, as a method of imparting traceability without changing conventional additives.

[0013] Although Patent Documents 1 to 4 describe liquid crystalline polyesters using biomass-derived monomers, they do not measure the biobased content, and there is no technical idea of ​​using the biobased content as traceability information for liquid crystalline polyester fibers. Furthermore, the liquid crystalline polyesters using biomass-derived monomers described in Patent Documents 1 to 4 are difficult to synthesize, and even if they could be synthesized, the fibers obtained using them have inferior mechanical properties compared to conventional liquid crystalline polyester fibers used as high-strength fibers, making them of little practical use.

[0014] The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystalline polyester fiber that has sufficient mechanical properties while being provided with traceability.

[0015] As a result of intensive research to achieve the above-mentioned object, the inventors of the present invention have found that by using a biomass-derived monomer to set the biobased content within a specific range and by using a liquid crystalline polyester having specific structural units, the resulting liquid crystalline polyester fiber has sufficient mechanical properties and the biobased content can be used as traceability information, which led to the completion of the present invention.

[0016] That is, the present invention can be configured in the following aspects. [Aspect 1] A liquid crystal polyester fiber comprising a liquid crystal polyester containing structural units derived from at least one aromatic hydroxycarboxylic acid, in which the total content of structural units derived from non-wholly aromatic monomers and structural units derived from non-linear aromatic monomers is less than 5 mol% relative to the total content of all structural units, and the content of structural units derived from heterocyclic aromatic monomers is less than 3 mol% relative to the total content of all structural units, and having a bio-based content of 1% or more (preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, particularly preferably 50% or more). [Aspect 2] A liquid crystal polyester fiber according to Aspect 1, in which the nitrogen content of components contained other than the liquid crystal polyester is 5 to 500 μg / g (preferably 5 to 300 μg / g, more preferably 5 to 250 μg / g) relative to the weight of the liquid crystal polyester fiber. [Aspect 3] The liquid crystal polyester fiber according to Aspect 1 or 2, having a tensile strength of 18 cN / dtex or more (preferably 20 cN / dtex or more, more preferably 22 cN / dtex or more, and even more preferably 23 cN / dtex or more). [Aspect 4] The liquid crystal polyester fiber according to any one of Aspects 1 to 3, wherein the liquid crystal polyester contains structural units derived from 4-hydroxybenzoic acid, at least a portion of which are biomass-derived structural units. [Aspect 5] The liquid crystal polyester fiber according to any one of Aspects 1 to 4, wherein the content of particulate matter inside the fiber is 1.0 wt% or less (preferably 0.3 wt% or less, more preferably 0.1 wt% or less, and even more preferably 0.01 wt% or less). [Aspect 6] A fiber structure at least partially comprising the liquid crystal polyester fiber according to any one of Aspects 1 to 5. [Aspect 7] The fiber structure according to Aspect 6, which is a fishing tackle, a fishing gear, a marine rope, or a covering material for a submarine cable. [Aspect 8] A method for measuring the biobased content of a liquid crystalline polyester fiber and using the biobased content as traceability information.

[0017] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly dictates otherwise. As used herein, the terms "and / or," "at least one," and "one or more" include any and all combinations of the associated listed items.

[0018] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification is included in the present invention, and in particular any combination of two or more of the claims described in the claims is included in the present invention.

[0019] The liquid crystalline polyester fiber of the present invention can utilize the bio-based content as traceability information, and has sufficient mechanical properties.

[0020] [Liquid Crystal Polyester Fiber] The liquid crystal polyester fiber contains structural units derived from at least one aromatic hydroxycarboxylic acid, and the total content of structural units derived from non- wholly aromatic monomers and structural units derived from non-linear aromatic monomers is less than 5 mol% relative to the total content of all structural units, and the content of structural units derived from heterocyclic aromatic monomers is less than 3 mol% relative to the total content of all structural units, and the bio-based content is 1% or more. In the present invention, by using a liquid crystal polyester containing a predetermined amount of biomass-derived structural units and structural units derived from aromatic hydroxycarboxylic acid, and having a composition in which the contents of structural units derived from non- wholly aromatic monomers, structural units derived from non-linear aromatic monomers, and structural units derived from heterocyclic aromatic monomers are reduced, it has been found that not only can the bio-based content be used as traceability information for the liquid crystal polyester fiber, but also that the fiber has sufficient mechanical properties for various industrial material applications such as ropes and nets.

[0021] In this specification, the term "biobased content" refers to an index that indicates the proportion of biomass-derived raw materials, and is determined by measuring radiocarbon ( １４Biomass, which is a renewable organic resource such as plants, absorbs carbon dioxide from the atmosphere through photosynthesis during its growth, and this carbon dioxide contains radioactive carbon ( １４ C) is present in a certain proportion, so it is contained in biomass. １４ C exists in a certain proportion. １４ Since C has a half-life of 5730 years, it is not found in fossil fuels that are formed underground over a long period of time. １４ Almost no carbon remains. Therefore, the biobased content can be adjusted by adjusting the ratio of biomass-derived raw materials to fossil fuel-derived raw materials, and the liquid crystal polyester fiber can be traced based on this value. The biobased content of the liquid crystal polyester fiber can be recognized as traceability information if it is 1% or more. Furthermore, from the viewpoint of reducing the environmental load by using biomass-derived raw materials, which are renewable organic resources such as plants, it may be preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 50% or more. The upper limit of the biobased content is not particularly limited, and may be 100% or less.

[0022] The liquid crystal polyester is a polyester that exhibits optical anisotropy in a molten state, and may be a polyester that is mainly composed of structural units containing aromatic groups in the main chain, and the bonds between each structural unit are mainly composed of ester bonds, but is preferably a wholly aromatic liquid crystal polyester in which all structural units contain aromatic groups in the main chain. The liquid crystal polyester contains structural units derived from at least one aromatic hydroxycarboxylic acid, but may also contain structural units derived from aromatic dicarboxylic acids, aromatic diols, etc. Furthermore, within the scope of the present invention, the liquid crystal polyester may contain amide bonds or the like as bonds between each structural unit in addition to ester bonds, and may contain structural units derived from, for example, aromatic diamines, aromatic hydroxyamines, aromatic aminocarboxylic acids, etc.

[0023] If the content of structural units derived from non-totally aromatic monomers or non-linear aromatic monomers in liquid crystal polyesters is too high, the introduction of flexible chains or substituents may cause disturbance in the crystalline structure of the liquid crystal polyester, and therefore the mechanical properties of liquid crystal polyester fibers containing such liquid crystal polyesters may be reduced.

[0024] Furthermore, if the content of structural units derived from heterocyclic aromatic monomers in the liquid crystal polyester is too high, the heat resistance is low and a thermal degradation reaction may occur during the melt polymerization reaction in the production of the liquid crystal polyester, and therefore such a liquid crystal polyester may not be produced or the mechanical properties of the liquid crystal polyester fiber may be deteriorated.

[0025] In this specification, the term "wholly aromatic monomer" refers to a monomer in which polycondensable functional groups are directly bonded to two aromatic ring carbons of an aromatic group, and two aromatic ring carbons per aromatic ring are substituted, and the term "non-wholly aromatic monomer" refers to a monomer that does not fall under the category of wholly aromatic monomers. A wholly aromatic monomer may be a monomer consisting only of an aromatic group and a polycondensable functional group.

[0026] The term "aromatic group" refers to a group having one or more aromatic rings and bonded to an aromatic ring carbon, such as a phenylene group, naphthylene group, biphenylylene group, or terphenylene group. The term "aromatic ring" refers to a cyclic chemical structure having aromaticity, such as a benzene ring or a naphthalene ring, and a fused ring such as a naphthalene ring is considered to be one aromatic ring. Aromatic groups in which aromatic rings are linked by bonds, such as a biphenylylene group or a terphenylene group, are considered to be aromatic groups having multiple aromatic rings. For example, a biphenylylene group is an aromatic group having two aromatic rings substituted on two aromatic ring carbons per aromatic ring (i.e., two aromatic rings substituted with a polycondensable functional group and a single bond). Examples of polycondensable functional groups include a carboxy group, a hydroxy group, an amino group, and derivatives thereof.

[0027] Examples of non-totally aromatic monomers include non-aromatic monomers and partially aromatic monomers. Non-aromatic monomers are monomers that do not have an aromatic group, such as ethylene glycol and succinic acid. Examples of partially aromatic monomers include monomers in which three or more aromatic ring carbons are substituted per aromatic ring, such as vanillic acid, syringic acid, ferulic acid, caffeic acid, and phenylhydroquinone; and monomers in which a polycondensable functional group is not directly bonded to an aromatic ring carbon, such as coumaric acid, phloretic acid, ferulic acid, and caffeic acid. Furthermore, the partially aromatic monomer may be a monomer having a chemical structure other than the aromatic group and the polycondensable functional group, and examples of the chemical structure other than the aromatic group and the polycondensable functional group include halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms; alkyl groups such as methyl groups and ethyl groups; alkoxy groups such as methoxy groups and ethoxy groups; monovalent groups such as vinyl groups, and alkylene groups such as methylene groups and ethylene groups; ether bonds; sulfide bonds; and divalent groups not related to polycondensable functional groups, such as ketone bonds.

[0028] In this specification, the term "linear aromatic monomer" refers to a monomer in which the bonds between two aromatic ring carbons and the polycondensable functional group are parallel or the angle formed by extending from the polycondensable functional group toward the aromatic ring carbon is an obtuse angle, and the term "non-linear aromatic monomer" refers to a monomer that does not fall under the category of linear aromatic monomers. Examples of linear aromatic monomers include, for example, when the aromatic group is a phenylene group, a monomer in which the polycondensable functional groups are substituted at the meta or para positions; when the aromatic group is a naphthylene group, a monomer in which the polycondensable functional groups are substituted at the 2,6-positions, 2,7-positions, 1,3-positions, 1,4-positions, 1,5-positions, or 1,6-positions; and when the aromatic group is a biphenylene group, a monomer in which the polycondensable functional groups are substituted at the 4,4'-positions, 3,4'-positions, or 2,2'-positions. Examples of non-linear aromatic monomers include salicylic acid, 1-hydroxy-2-naphthoic acid, 8-hydroxy-2-naphthoic acid, and 2,4'-biphenol.

[0029] In the liquid crystal polyester, the total content of the constitutional unit derived from non-totally aromatic monomer (non-aromatic monomer and partially aromatic monomer) and the constitutional unit derived from non-linear aromatic monomer can be preferably less than 1 mol%, more preferably less than 0.1 mol%, and even more preferably 0 mol% with respect to the total content of all constitutional units.In addition, the content of the constitutional unit derived from the monomer corresponding to both non-totally aromatic monomer and non-linear aromatic monomer is not overlapped as the content of the constitutional unit derived from one kind of monomer, and is judged by adding it to the total content of the constitutional unit derived from non-totally aromatic monomer and the constitutional unit derived from non-linear aromatic monomer.

[0030] In this specification, the term "heterocyclic aromatic monomer" refers to a monomer having an aromatic group containing at least one heteroatom (e.g., nitrogen atom, oxygen atom, sulfur atom, etc.) as an atom constituting an aromatic ring and two or more polycondensable functional groups. Examples of heterocyclic aromatic monomers include furandicarboxylic acid, pyrrole dicarboxylic acid, and pyridine dicarboxylic acid. In the liquid crystal polyester, the constituent units derived from heterocyclic aromatic monomers may be preferably less than 1 mol%, more preferably less than 0.1 mol%, and even more preferably 0 mol%, relative to the total content of all constituent units. The content of constituent units derived from non-totally aromatic monomers and / or non-linear aromatic monomers and heterocyclic aromatic monomers is determined by adding the total content of constituent units derived from non-totally aromatic monomers and non-linear aromatic monomers, and the content of constituent units derived from heterocyclic aromatic monomers.

[0031] From the viewpoint of fully exhibiting the mechanical properties of the liquid crystal polyester fiber, the liquid crystal polyester may contain more than 95 mol%, preferably 98 mol% or more, more preferably 99.9 mol% or more, and even more preferably 100 mol% of structural units derived from a carbocyclic linear wholly aromatic monomer, based on the total content of all structural units. In this specification, the term "carbocyclic linear wholly aromatic monomer" refers to a monomer that is both a wholly aromatic monomer and a linear aromatic monomer, and in which the aromatic group is an aromatic group in which the aromatic ring is a carbon ring (a carbocyclic aromatic group). In the carbocyclic linear wholly aromatic monomer, the carbocyclic aromatic group is preferably at least one selected from the group consisting of a 1,4-phenylene group, a 1,3-phenylene group, a 2,6-naphthylene group, and a 4,4'-biphenylene group.

[0032] The liquid crystal polyester preferably contains, as the structural unit derived from an aromatic hydroxycarboxylic acid, a structural unit derived from 4-hydroxybenzoic acid and / or a structural unit derived from 6-hydroxy-2-naphthoic acid.

[0033] The content of the structural units derived from aromatic hydroxycarboxylic acid in the liquid crystal polyester may be 50 mol % or more, preferably 53 mol % or more, and more preferably 60 mol % or more, based on the total amount of all structural units.

[0034] The liquid crystal polyester preferably contains a structural unit derived from 4-hydroxybenzoic acid as a structural unit derived from an aromatic hydroxycarboxylic acid, at least a portion of which is a biomass-derived structural unit. The biomass-derived structural unit contained in the liquid crystal polyester is not particularly limited as long as a biomass-derived monomer corresponding to such a structural unit can be prepared, and may be a structural unit derived from not only aromatic hydroxycarboxylic acid but also aromatic dicarboxylic acid or aromatic diol, etc. However, 4-hydroxybenzoic acid is easily obtained as a biomass-derived monomer, for example, it can be produced from cellulose or the like by a bioprocess using various bacteria, or it can be obtained by chemically treating lignin contained in plant biomass. In addition, biomass-derived monomers generally contain different impurities than fossil fuel-derived monomers due to differences in their preparation method, etc., and therefore, similar to the case of using a fossil fuel-derived monomer, the mechanical properties of the resulting liquid crystal polyester fiber can be fully exhibited, which is preferable.

[0035] The liquid crystal polyester may be (i) a liquid crystal polyester containing a structural unit (structural unit (I)) represented by the following formula (I), or (ii) a liquid crystal polyester containing a structural unit (structural unit (I)) represented by the following formula (I), a structural unit (structural unit (II)) represented by the following formula (II), a structural unit (structural unit (III)) represented by the following formula (III), and a structural unit (structural unit (IV)) represented by the following formula (IV): -O-Ar １ -CO- (I) -CO-Ar ２ -CO- (II) -O-Ar ３ -O- (III) -O-Ar ４ -NH- (IV) (wherein, Ar １ , Ar ２ , Ar ３ and Ar ４ are each independently at least one selected from the group consisting of a phenylene group, a naphthylene group, and a biphenylylene group.

[0036] For example, the liquid crystal polyester may contain, relative to the total amount of all structural units, 40 to 100 mol % of the structural unit (I), 0 to 30 mol % of the structural unit (II), and 0 to 30 mol % of at least one structural unit selected from the group consisting of the structural unit (III) and the structural unit (IV).

[0037] The structural unit (I) is a structural unit derived from an aromatic hydroxycarboxylic acid, and Ar １ However, structural units which are 1,4-phenylene groups (structural units derived from 4-hydroxybenzoic acid) and structural units which are 2,6-naphthylene groups (structural units derived from 6-hydroxy-2-naphthoic acid) are preferred.

[0038] The structural unit (II) is a structural unit derived from an aromatic dicarboxylic acid, and Ar ２ However, a structural unit which is a 1,4-phenylene group (a structural unit derived from terephthalic acid), a structural unit which is a 1,3-phenylene group (a structural unit derived from isophthalic acid), and a structural unit which is a 2,6-naphthylene group (a structural unit derived from 2,6-naphthalenedicarboxylic acid) are preferred.

[0039] The structural unit (III) is a structural unit derived from an aromatic diol, and Ar ３ However, structural units that are 1,4-phenylene groups (structural units derived from hydroquinone) and structural units that are 4,4'-biphenylylene groups (structural units derived from 4,4'-dihydroxybiphenyl) are preferred.

[0040] The structural unit (IV) is a structural unit derived from an aromatic hydroxyamine, and Ar ４ However, a structural unit which is a 1,4-phenylene group (a structural unit derived from 4-aminophenol) and a structural unit which is a 4,4'-biphenylylene group (a structural unit derived from 4-amino-4'-hydroxybiphenyl) are preferred.

[0041] The liquid crystal polyester (i) above preferably contains a structural unit (A) derived from hydroxybenzoic acid and a structural unit (B) derived from hydroxynaphthoic acid. For example, the structural unit (A) may be a structural unit derived from 4-hydroxybenzoic acid (formula (A) below), and the structural unit (B) may be a structural unit derived from 6-hydroxy-2-naphthoic acid (formula (B) below). From the viewpoint of improving melt moldability, the ratio of the structural unit (A) to the structural unit (B) may be preferably in the range of 9 / 1 to 1 / 1, more preferably 7 / 1 to 1 / 1, and even more preferably 5 / 1 to 1 / 1.

[0042]

[0043]

[0044] When the liquid crystal polyester (i) contains both the structural unit (A) and the structural unit (B), the content of the structural unit derived from 4-hydroxybenzoic acid may be 50 mol% or more, preferably 53 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and even more preferably 70 mol% or more, relative to the total amount of all structural units. The upper limit of the content of the structural unit derived from 4-hydroxybenzoic acid in the liquid crystal polyester is not particularly limited, but may be, for example, 90 mol% or less, preferably 88 mol% or less, and more preferably 85 mol% or less.

[0045] When the liquid crystal polyester (i) contains both the structural unit (A) and the structural unit (B), the content of the structural unit derived from 6-hydroxy-2-naphthoic acid may be 4 to 45 mol% relative to the total amount of all structural units.

[0046] The content of the structural unit (I) in the liquid crystal polyester (ii) may be 40 to 95 mol %, preferably 50 to 90 mol %, and more preferably 60 to 85 mol %, based on the total amount of all structural units.

[0047] The content of the structural unit (II) in the liquid crystal polyester (ii) may be 2.5 to 30 mol %, preferably 5 to 25 mol %, and more preferably 7.5 to 20 mol %, based on the total amount of all structural units.

[0048] The total content of the structural units (III) and (IV) in the liquid crystal polyester (ii) above may be 2.5 to 30 mol %, preferably 5 to 25 mol %, and more preferably 7.5 to 20 mol %, based on the total amount of all structural units.

[0049] The molar ratio of the content of structural unit (II) to the total content of structural units (III) and (IV), expressed as (II) / [(III)+(IV)], may be from 90 / 100 to 100 / 90, preferably from 95 / 100 to 100 / 95, more preferably from 98 / 100 to 100 / 98, and even more preferably 100 / 100.

[0050] The liquid crystal polyester may contain two or more of each of the structural units (I) to (IV). The above content of each structural unit represents the content of all structural units corresponding to that structural unit. For example, when the liquid crystal polyester contains structural units derived from 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the content of structural unit (I) represents the total content thereof.

[0051] The liquid crystal polyester may have a total content of the structural units (I) to (IV) of 95 mol% or more, preferably 98 mol% or more, more preferably 99.9 mol% or more, and even more preferably 100 mol%, based on the total amount of all structural units.

[0052] Preferred combinations of structural units include combinations of structural units described in examples (1) to (14) shown in Tables 1 and 2 below. The liquid crystal polyester may consist of only a combination of structural units of any of the following formulas (1) to (14). When a structural unit in the formula is a structural unit that can exhibit multiple structures, two or more of such structural units may be combined and used as a structural unit that constitutes the liquid crystal polyester.

[0053]

[0054]

[0055] In the structural units in Tables 1 and 2, n is an integer of 1 or 2, and the structural units n=1 and n=2 may be present alone or in combination.

[0056] The melting point of the liquid crystal polyester (hereinafter referred to as Mp ０ The melting point (sometimes referred to as "melting point") is preferably in the range of 200 to 380°C, more preferably 250 to 370°C, and even more preferably 260 to 360°C. In this specification, the melting point is the main absorption peak temperature observed when measured using a differential scanning calorimeter (DSC) in accordance with the JIS K 7121 test method. Specifically, 1 to 10 mg of a sample is placed in an aluminum pan in a DSC apparatus, and nitrogen is flowed as a carrier gas at a flow rate of 100 mL / min. The endothermic peak is measured when the temperature is increased from room temperature (e.g., 25°C) at a rate of 20°C / min. If a clear peak does not appear in the first run of DSC measurement due to the type of polymer, it is advisable to increase the temperature at 50°C / min to a temperature 50°C higher than the expected flow temperature, completely melt the polymer at that temperature for 3 minutes, then decrease the temperature to 50°C at a rate of 80°C / min, and then measure the endothermic peak at a rate of 20°C / min.

[0057] The liquid crystal polyester may be mixed with a thermoplastic polymer such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, etc., within the range that does not impair the effects of the present invention. Furthermore, various additives such as inorganic substances such as titanium oxide, kaolin, silica, barium oxide, etc., colorants such as carbon black, dyes, and pigments, antioxidants, ultraviolet absorbers, and light stabilizers may also be mixed.

[0058] The liquid crystal polyester fiber may be a mixed spun fiber obtained by mixing and spinning the liquid crystal polyester with the thermoplastic polymer and various additives, or may be a conjugated spun fiber obtained by simultaneously spinning different components of the liquid crystal polyester and the thermoplastic polymer from separate spinnerets, as long as the effects of the present invention are not impaired. The liquid crystal polyester fiber may be a non-conjugated spun fiber or a conjugated spun fiber.

[0059] The liquid crystal polyester fiber may contain the liquid crystal polyester in an amount of 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, even more preferably 95% by weight or more, and still more preferably 98% by weight or more.

[0060] The liquid crystal polyester fiber may have a nitrogen content of components other than the liquid crystal polyester (hereinafter, sometimes referred to as the "nitrogen impurity content") of 5 to 500 μg / g based on the weight of the liquid crystal polyester fiber. Examples of nitrogen-containing components other than the liquid crystal polyester include impurities contaminated in biomass-derived monomers. Unlike fossil fuel-derived monomers, the use of biomass-derived monomers increases the nitrogen impurity content. The inventors have found that the nitrogen content derived from such impurities hinders further improvement of the mechanical properties of the liquid crystal polyester fiber. By setting the nitrogen impurity content at or below the upper limit, mechanical properties (e.g., tensile strength) can be further improved. On the other hand, if the nitrogen impurity content is too low, excessive purification is required, which may result in reduced yield and other adverse effects on productivity. Therefore, from the perspective of adjusting the desired biobased content using biomass-derived monomers, it is preferable to set the nitrogen impurity content at or above the lower limit. From the perspective of further improving mechanical properties, the nitrogen impurity content may be preferably 5 to 300 μg / g, more preferably 5 to 250 μg / g. In this specification, the nitrogen impurity content is calculated as C = A - B, where A is the amount of nitrogen element in the liquid crystal polyester fiber and B is the amount of nitrogen element contained in the chemical structure of the liquid crystal polyester, in order to grasp the amount of nitrogen element derived from components such as impurities contained in components other than the liquid crystal polyester (when no nitrogen atom is contained in the chemical structure of the liquid crystal polyester, B = 0). The nitrogen impurity content is the amount of nitrogen element in the components constituting the fiber itself, excluding components such as oils attached to the fiber surface. Specifically, the nitrogen impurity content is a value measured by the method described in the Examples below.

[0061] In order to prevent deterioration of mechanical properties, the liquid crystal polyester fiber may have a particulate content of 1.0 wt% or less, preferably 0.3 wt% or less, more preferably 0.1 wt% or less, and even more preferably 0.01 wt% or less. In this specification, "particulate matter" refers to components that are dispersed and not compatible with the liquid crystal polyester fiber, and "particulate matter inside the fiber" refers to components that are dispersed among the components that constitute the fiber itself, excluding components attached to the fiber surface such as oils. Examples of particulate matter include the above-mentioned inorganic substances such as titanium oxide, kaolin, silica, and barium oxide, and colorants such as carbon black and pigments.

[0062] The liquid crystal polyester fiber may have a tensile strength of 18 cN / dtex or more, preferably 20 cN / dtex or more, more preferably 22 cN / dtex or more, and even more preferably 23 cN / dtex or more. The upper limit of the tensile strength is not particularly limited, but may be, for example, about 40 cN / dtex. In this specification, the tensile strength of the liquid crystal polyester fiber is a value measured by the method described in the examples below.

[0063] The liquid crystal polyester fiber may have a modulus of elasticity of 500 cN / dtex or more, preferably 530 cN / dtex or more, and more preferably 550 cN / dtex or more. The upper limit of the modulus of elasticity is not particularly limited, but may be, for example, about 1500 cN / dtex. In this specification, the modulus of elasticity of the liquid crystal polyester fiber refers to the slope of the line connecting the two points of elongation of 0.25% and 1.00% on the strength-elongation curve, and is a value measured by the method described in the examples below.

[0064] The melting point of the liquid crystal polyester fiber may be 220 to 380°C, preferably 270 to 380°C, and more preferably 300 to 380°C. The melting point of the liquid crystal polyester fiber is increased from the melting point of the raw spinning yarn by solid-state polymerization. In this specification, the melting point of the liquid crystal polyester fiber is a value measured by the method described in the examples below.

[0065] The single fiber fineness of the liquid crystal polyester fiber can be appropriately selected depending on the application, etc., and may be, for example, 0.01 to 50 dtex, preferably 0.5 to 35 dtex, more preferably 1.0 to 15 dtex, and even more preferably 1.5 to 10 dtex. In this specification, the single fiber fineness is a value measured by the method described in the Examples below.

[0066] The liquid crystal polyester fiber may be a monofilament or a multifilament. In the case of a multifilament, the number of filaments can be appropriately selected depending on the application, etc. For example, the number of filaments may be 2 to 5,000, preferably 3 to 4,000, and more preferably 5 to 3,000.

[0067] The total fineness of the liquid crystal polyester fiber can be appropriately selected depending on the application, etc., and may be, for example, 10 to 50,000 dtex, preferably 15 to 30,000 dtex, and more preferably 25 to 10,000 dtex.

[0068] The method for producing a liquid crystal polyester fiber may include at least a step of melt-spinning the liquid crystal polyester to obtain a raw spun yarn, and a step of heat-treating the obtained raw spun yarn.

[0069] Liquid crystal polyesters can be synthesized by known polycondensation methods. As monomers to be subjected to polycondensation, the above-mentioned various aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines, etc. may be used, and carboxylic acid derivatives such as acylated products of hydroxyl groups, esterified products of carboxyl groups, acid halides, and acid anhydrides, in which the terminals of these monomers are activated, may also be used. In this specification, the structural units derived from various compounds include not only the compounds themselves but also structural units obtained by polycondensation of derivatives in which the terminals of the compounds are activated.

[0070] By using a predetermined amount of at least one biomass-derived monomer as the above-mentioned monomer, the biobased content of the resulting liquid crystal polyester can be adjusted within a specific range. The biomass-derived monomer used is not particularly limited as long as it can be prepared from biomass. Examples include 4-hydroxybenzoic acid, terephthalic acid, and their derivatives. However, 4-hydroxybenzoic acid and its derivatives are preferred from the viewpoints of ease of availability and suppression of deterioration in mechanical properties. 4-hydroxybenzoic acid as a biomass-derived monomer can be produced from cellulose or the like by bioprocesses using various bacteria, or can be obtained by chemical treatment of lignin. Impurities remaining during the production process can minimize deterioration in the mechanical properties of the resulting liquid crystal polyester fiber, thereby enabling the fiber to exhibit mechanical properties equivalent to those obtained when 4-hydroxybenzoic acid is used as a fossil fuel-derived monomer. Furthermore, as described above, adjusting the nitrogen impurity content derived from such impurities can improve mechanical properties to the same or even higher levels. The biomass is not particularly limited as long as the desired biomass-derived monomer can be obtained using various processes. For example, plant-based biomass from which lignin, a natural aromatic polymer, can be extracted includes plant-derived raw materials such as the trunks, stalks, leaves, and fruits of various plant materials (for example, coconut shells, coffee beans, tea leaves, straw, rice husks, rice, wheat, sugarcane, corn, fruits (mandarin oranges, bananas, etc.), broad-leaved trees, conifers, bamboo, ferns, mosses, algae, and other plant materials), with coconut shells being preferred from the standpoint of stable production.

[0071] The polycondensation may be carried out in the presence of various polymerization catalysts, such as organotin catalysts (dialkyltin oxides, etc.), antimony catalysts (antimony trioxide, etc.), titanium catalysts (titanium dioxide, etc.), alkali metal salts or alkaline earth metal salts of carboxylic acids (potassium acetate, etc.), Lewis acid salts (BF ３ etc.), organic compound catalysts (N,N-dimethylaminopyridine, 1-methylimidazole, etc.), etc.

[0072] The melt spinning can be carried out by a known method, for example, by melting the liquid crystal polyester in an extruder, discharging it from a nozzle at a predetermined spinning temperature, and winding it up with a godet roller or the like to obtain a spun raw yarn. The liquid crystal polyester may contain the above-mentioned thermoplastic polymer and various additives within a range that does not impair the effects of the present invention.

[0073] By subjecting the spun raw yarn to heat treatment, solid-phase polymerization of the liquid crystal polyester proceeds, thereby improving mechanical properties such as tensile strength. The heat treatment method in the heat treatment step is not particularly limited, and may be, for example, a batch-type heat treatment or continuous heat treatment by conveyance. In the batch-type heat treatment, for example, the heat treatment may be performed in a state where the yarn is wound around a bobbin in a packaged form, or in a skein or tow form. In terms of simplifying the equipment and improving productivity, it is preferable to perform the heat treatment in a packaged form. In the case of continuous heat treatment by conveyance, the conveyance method may be contact conveyance (for example, a conveyor system, a support roll system, or a heat treatment system using a heated roller) or non-contact conveyance (a roll-to-roll system).

[0074] The heat treatment step can be carried out by a known method, such as atmospheric heating, contact heating, etc. The atmosphere is preferably air, an inert gas (e.g., nitrogen, argon), or a combination thereof.

[0075] The heat treatment temperature may be lower than the melting point (Mp) of the raw spun yarn subjected to the heat treatment step to prevent melting, and may be, for example, Mp-50°C or higher and lower than Mp°C, preferably Mp-40°C or higher and lower than Mp°C, and more preferably Mp-30°C or higher and lower than Mp°C.

[0076] In the method for producing a liquid crystal polyester fiber, the strength ratio of the liquid crystal polyester fiber before and after the heat treatment step may be 1.5 times or more, preferably 1.8 times or more, and more preferably 2.0 times or more. The upper limit of the strength ratio of the liquid crystal polyester fiber before and after the heat treatment step is not particularly limited, but may be, for example, 10 times or less. Here, the strength ratio before and after the heat treatment step refers to the value obtained by dividing the strength of the liquid crystal polyester fiber after the heat treatment step by the strength of the liquid crystal polyester fiber (raw spinning yarn) before the heat treatment step.

[0077] In the method for producing a liquid crystal polyester fiber, for example, an oil may be applied before the heat treatment step in order to improve the bundling property of the fiber or to prevent fusion during the heat treatment. Furthermore, after the heat treatment, a finishing oil may be applied as appropriate depending on the application of the liquid crystal polyester fiber.

[0078] [Textile Structures] The liquid crystal polyester fibers can be used in various applications as textile structures containing the liquid crystal polyester fibers at least in part. Textile structures containing the liquid crystal polyester fibers can be used in any fiber form, such as staple fibers, short-cut fibers, filament yarns, spun yarns, strings, ropes, etc. Furthermore, the liquid crystal polyester fibers can also be used as various fabrics, such as nonwoven fabrics, woven fabrics, and knitted fabrics. Such fibers and fabrics can be produced using the liquid crystal polyester fibers by known methods.

[0079] The fiber structure may be a combination of a liquid crystal polyester fiber and another fiber, as long as the effects of the present invention are not impaired. For example, a composite yarn using a liquid crystal polyester fiber and another fiber (e.g., a mixed yarn (filament yarn) in which a liquid crystal polyester fiber is mixed with another fiber, or a mixed yarn (spun yarn) in which a liquid crystal polyester fiber is mixed with another fiber) can be used. Also, composite fabrics using a liquid crystal polyester fiber and another fiber (e.g., a mixed fabric in which a liquid crystal polyester fiber is mixed with another fiber, or a laminate of a fabric made of a liquid crystal polyester fiber and a fabric made of another fiber) can be used.

[0080] Liquid crystal polyester fibers can be used in the form of various fiber structures for a variety of applications, such as general industrial materials, civil engineering and construction materials, various reinforcing materials, electrical and electronic component materials, and various textile products. For example, they can be used in advanced processed products such as tension members (electric wires, optical fibers, umbilical cables, heater wire core threads, earphone cords, and other electrical cords), sailcloth, ropes (marine, mountain climbing, crane, yacht, tug, and other), ropes, land nets (safety nets, golf driving range nets, and other), slings, lifelines, fishing lines, fishing nets, longlines, sewing thread, screen cords, geogrids, protective gloves, ripstop protective clothing and outdoor clothing, rider suits, sports rackets, guts, reinforcing materials for medical catheters, sutures, screen gauze, filters, base fabrics for printed circuit boards, exterior materials for electronic devices, mesh conveyor belts, papermaking belts, dryer canvas, airships, balloons, airbags, speaker cones, reinforcing materials for various hoses and pipes, and reinforcing materials for rubber and plastic materials such as tires and conveyor belts.

[0081] The liquid crystal polyester fiber has traceability using the bio-based content as an index, and is therefore effective for identifying production lines and for applications where traceability is often required for outdoor use. For example, the fiber can be suitably used for fishing gear such as fishing nets and longlines, fishing tackle such as fishing lines, marine ropes, and covering materials for submarine cables.

[0082] As described above, traceability can be imparted to liquid crystalline polyester fibers using the biobased content as an index, and therefore, a method of measuring the biobased content of liquid crystalline polyester fibers and using the biobased content as traceability information can be adopted as a method of tracking various products containing liquid crystalline polyester fibers. The biobased content can be adjusted by the ratio of biomass-derived raw materials to fossil fuel-derived raw materials, so that various biobased content percentages can be assigned to liquid crystalline polyester fibers depending on the manufacturer or user. Furthermore, even the same manufacturer can assign various biobased content percentages to identify production lines. The biobased content can be measured, as described above, by radiocarbon (１４ The bio-based content can be calculated by measuring the concentration of C) using a radiocarbon dating method. The above method may be applied to liquid crystalline polyester fibers having a bio-based content of 1% or more.

[0083] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0084] (Melting Point of Resin Chips and Fibers) Measurement was performed using a differential scanning calorimeter (DSC; "DSC60A Plus" manufactured by Shimadzu Corporation) in accordance with JIS K 7121, and the observed main absorption peak temperature was taken as the melting point. Specifically, 1 to 10 mg of the sample was placed in an aluminum pan and sealed in the DSC device. Nitrogen was then flowed as a carrier gas at a flow rate of 100 mL / min, and the endothermic peak derived from the liquid crystal polyester was measured when the temperature was raised from 25°C at a rate of 20°C / min.

[0085] (Melt Viscosity) The melting point Mp of the liquid crystal polyester resin chip measured above was measured using a melt viscosity measuring device (Capillograph 1C manufactured by Toyo Seiki Co., Ltd.) with a capillary of 1.00 mmφ×10 mm. ０ For MP ０ Under temperature conditions of +30°C, shear rate 1216 sec －１ The melt viscosity (Pa·s) was measured at 100°C.

[0086] (Total fineness, single fiber fineness) Based on JIS L 1013:2010 8.3.1 A method, using a measuring instrument "Wrap Reel by Motor Drive" manufactured by Daiei Scientific Instruments Co., Ltd., the liquid crystal polyester fiber was wound around a reel of 1 m per turn x 100 turns (total 100 m), and the weight (g) was multiplied by 100, and measurements were carried out twice per level, and the average value was taken as the total fineness (dtex) of the obtained liquid crystal polyester fiber. In addition, the quotient obtained by dividing this value by the number of filaments was taken as the single fiber fineness (dtex).

[0087] (Tensile Strength, Elastic Modulus) Ten tensile tests were conducted for each yarn sample using an autograph "AGS-100B" manufactured by Shimadzu Corporation, with a test length of 20 cm and a tensile speed of 10 cm / min, in accordance with JIS L 1013:2010 8.5.1. The average value of the tensile strength (N) at break was divided by the total fineness (dtex) measured by the above-mentioned method to calculate the tensile strength (cN / dtex). In addition, the average value of the slope of the line connecting the two points of elongation of 0.25% and 1.00% on the strength-elongation curve obtained in the tensile test was divided by the total fineness (dtex) measured by the above-mentioned method to calculate the elastic modulus (cN / dtex).

[0088] (Bio-based content) According to the method described in ASTM D6866, the radiocarbon ( １４ The concentration of carbon dioxide (C) was measured, and the amount of biomass-derived carbon was calculated based on the principles of radiocarbon dating. The ratio of this to the total carbon amount was taken as the biobased ratio (%).

[0089] (Nitrogen impurity content) Oil removal as pretreatment for nitrogen content analysis A liquid crystal polyester fiber sample in an amount of 100 g or less was placed in an aqueous solution prepared by dissolving 2 g of a nonionic surfactant (Actinol F-9, manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) in 1 L of ion-exchanged water, and the temperature was adjusted to 60 to 90°C, followed by shaking for 40 minutes. The liquid crystal polyester fiber sample was removed and rinsed twice for 40 minutes with 1 L of ion-exchanged water adjusted to 60 to 90°C. The liquid crystal polyester fiber sample was removed and dried in an air atmosphere at 80°C for 3 hours or more using a hot air dryer "DN63HI" manufactured by Yamato Scientific Co., Ltd., to obtain a liquid crystal polyester fiber sample from which the oil had been removed.

[0090] Nitrogen impurity content When the amount of nitrogen element in the liquid crystal polyester fiber measured by the following method is A and the amount of nitrogen element contained in the chemical structure of the liquid crystal polyester is B, the nitrogen impurity content is calculated as C = A - B.

[0091] Amount A of Nitrogen Element in Liquid Crystal Polyester Fiber: The amount A of nitrogen element in the liquid crystal polyester fiber was measured by a chemiluminescence method using a trace nitrogen analyzer (TN-5000V manufactured by Nitto Seiko Analytech Co., Ltd.) with reference to the method described in JIS K 2609:1998.

[0092] Amount of nitrogen element contained in the chemical structure of liquid crystal polyester B Polymer Degradation and Stability, 76, 85-94 (2002) With reference to the method described, a 25% tetramethylammonium hydroxide (TMAH) methanol solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and reactive pyrolysis gas chromatography was performed, and each component was detected using a quadrupole mass spectrometer (MS) and a flame ionization detector (FID), and the composition ratio was calculated. In this case, components with peak detection intensities equal to or less than the background peak observed during blank measurement were not considered to be components derived from the chemical structure of the liquid crystal polyester and were excluded. The aromatic amine and aromatic amide components detected here were considered to be components derived from the chemical structure of the liquid crystal polyester, and the amount of nitrogen element contained in the chemical structure of the liquid crystal polyester was calculated from the composition ratio.

[0093] [Experimental Example 1] Scraps (wood powder with a major axis of less than 2 mm) generated when sawing the endocarp of palm trees were mixed with ion-exchanged water at a powder weight / water weight ratio of 6 / 25, and the mixture was placed in an autoclave. The powder weight was measured after drying by exposing the mixture to air at 120°C for 3 hours. Subcritical water treatment was performed in the autoclave at 200°C and 1.5 MPa for 40 minutes, heating was stopped, the autoclave was cooled, and the reaction liquid was opened when it reached 60°C. The resulting suspension after treatment was filtered to obtain a filtrate. The resulting filtrate was then acidified with hydrochloric acid and allowed to stand overnight, and the precipitated pale yellow solid was recovered by filtration. The recovered solid components were then separated into a heavy solvent, DMSO-d ６ Using １ Analysis by H-HMR revealed that the main component was 4-hydroxybenzoic acid, and therefore this solid is hereinafter referred to as "biomass-derived crude HBA." The nitrogen impurity content of the biomass-derived crude HBA was 955 μg / g.

[0094] [Experimental Example 2] The biomass-derived crude HBA obtained in Experimental Example 1 was recrystallized with methanol to obtain white 4-hydroxybenzoic acid (hereinafter referred to as "biomass-derived purified HBA"). The recovered weight of biomass-derived purified HBA was in the range of 0.5 to 1.5 wt% relative to the weight of the raw material palm kernel powder. The nitrogen impurity content of the biomass-derived purified HBA was 22 μg / g.

[0095] The non-biomass-derived raw materials used were 4-hydroxybenzoic acid (petrochemical-derived HBA; manufactured by Tokyo Chemical Industry Co., Ltd.), 6-hydroxy-2-naphthoic acid (HNA; manufactured by Tokyo Chemical Industry Co., Ltd.), terephthalic acid (TA; manufactured by Tokyo Chemical Industry Co., Ltd.), isophthalic acid (IA; manufactured by Tokyo Chemical Industry Co., Ltd.), 2,5-furandicarboxylic acid (FDCA; manufactured by Tokyo Chemical Industry Co., Ltd.), 4,4'-biphenol (BP; manufactured by Tokyo Chemical Industry Co., Ltd.), 4-aminophenol (PAP; manufactured by Tokyo Chemical Industry Co., Ltd.), and ethylene glycol (EG; manufactured by Tokyo Chemical Industry Co., Ltd.).

[0096] In addition, acetic anhydride (Ac ２ O; Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) and potassium acetate (KOAc; Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent) were used.

[0097] Example 1 A reaction vessel equipped with a stirring blade, a distillation pipe, and a reaction solution discharge pipe was charged with HBA, HNA, and Ac. ２O and KOAc were added to give a molar ratio of 73 / 27 / 105 / 0.005. At this time, HBA was used in a molar ratio of 10 / 90, consisting of the biomass-derived crude HBA and petrochemical-derived HBA of Experimental Example 1. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and the reaction solution was stirred while the liquid temperature was raised from room temperature to 160 ° C. at 2 ° C. / min, and refluxed at 160 ° C. for 3 hours. Next, the temperature was raised from 160 ° C. to 320 ° C. at 2 ° C. / min while distilling the evaporated liquid, and stirring was carried out at 320 ° C. for 1 hour. Next, the pressure in the reaction vessel was reduced to 100 Pa over 1.5 hours, and stirring was continued. When the reaction solution reached a molten resin of a predetermined viscosity, stirring was stopped and nitrogen was introduced into the reaction vessel. The reactor was then pressurized to 3 atmospheres with nitrogen, and the resin was taken out as strands with a diameter of 2 mm from the discharge pipe at the bottom of the reactor, and pelletized with a rotary cutter to obtain liquid crystal polyester resin chips.

[0098] The resin chips were dried with hot air at 120 ° C for more than 4 hours, and then melt-extruded using a Φ15 mm twin-screw extruder at a heater temperature of 300 ° C. The resin melt was supplied to the spinning head while being metered using a gear pump. The spinning head was equipped with a spinneret with a hole diameter of 0.125 mm and 50 holes, and the resin melt was discharged at a discharge rate of 28 g / min and wound onto a bobbin at a winding speed of 1000 m / min to obtain a liquid crystal polyester fiber spun yarn. At this time, a 2 wt% aqueous solution of sodium dodecyl phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) was applied to the spun yarn from an oiling guide located directly below the spinneret. The amount of this aqueous solution applied was 1.4 g / min, and the calculated adhesion ratio of sodium dodecyl phosphate to the spun yarn was 0.1 wt%.

[0099] Next, 4 kg of the obtained raw spun yarn was rewound onto an aluminum bobbin and heat-treated in a closed oven under a nitrogen atmosphere at a temperature of the melting point of the raw spun yarn -10°C for 16 hours to obtain a heat-treated liquid crystalline polyester fiber. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0100] [Example 2] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 1, except that the biomass-derived crude HBA and petrochemical-derived HBA of Experimental Example 1 were used in a molar ratio of 50 / 50. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0101] [Example 3] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 1, except that the biomass-derived crude HBA and petrochemical-derived HBA of Experimental Example 1 were used in a molar ratio of 90 / 10. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0102] [Example 4] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 1, except that the biomass-derived purified HBA of Experimental Example 2 and petrochemical-derived HBA were used in a molar ratio of 100 / 0. The analysis results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0103] [Example 5] A reaction vessel equipped with a stirring blade, a distillation pipe, and a reaction solution discharge pipe was charged with HBA, TA, IA, BP, Ac, and ２ O and KOAc were added to give a molar ratio of 60 / 15 / 5 / 20 / 105 / 0.005. At this time, HBA was used in a molar ratio of 50 / 50, consisting of the biomass-derived crude HBA and petrochemical-derived HBA of Experimental Example 1. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and the reaction solution was stirred while the liquid temperature was raised from room temperature to 160 ° C. at 2 ° C. / min, and refluxed at 160 ° C. for 3 hours. Next, the temperature was raised from 160 ° C. to 350 ° C. at 2 ° C. / min while distilling the evaporated liquid, and stirring was carried out at 350 ° C. for 1 hour. Next, the pressure in the reaction vessel was reduced to 100 Pa over 1.5 hours, and stirring was continued. When the reaction solution reached a molten resin of a predetermined viscosity, stirring was stopped and nitrogen was introduced into the reaction vessel. The reactor was then pressurized to 3 atmospheres with nitrogen, and the resin was taken out as strands with a diameter of 2 mm from the discharge pipe at the bottom of the reactor, and pelletized with a rotary cutter to obtain liquid crystal polyester resin chips.

[0104] The resin chips were dried with hot air at 120 ° C for more than 4 hours, and then melt-extruded using a Φ15 mm twin-screw extruder at a heater temperature of 370 ° C. The resin melt was supplied to the spinning head while being metered using a gear pump. The spinning head was equipped with a spinneret with a hole diameter of 0.125 mm and 50 holes, and the resin melt was discharged at a discharge rate of 28 g / min and wound onto a bobbin at a winding speed of 1000 m / min to obtain a liquid crystal polyester fiber spun yarn. At this time, a 2 wt% aqueous solution of sodium dodecyl phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako First Grade) was applied to the spun yarn from an oiling guide located directly below the spinneret. The amount of this aqueous solution applied was 1.4 g / min, and the calculated adhesion ratio of sodium dodecyl phosphate to the spun yarn was 0.1 wt%.

[0105] Next, 4 kg of the obtained raw spun yarn was rewound onto an aluminum bobbin and heat-treated in a closed oven under a nitrogen atmosphere at a temperature of −40° C. (the melting point of the raw spun yarn) for 16 hours to obtain a heat-treated liquid crystalline polyester fiber. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0106] [Example 6] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 5, except that the biomass-derived crude HBA of Experimental Example 1 and petrochemical-derived HBA were used in a molar ratio of 90 / 10. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0107] [Example 7] A reaction vessel was charged with HBA, TA, IA, BP, PAP, and Ac. ２ A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 5, except that O and KOAc were added to give a molar ratio of 60 / 15 / 5 / 17 / 3 / 105 / 0.005, and the HBA used was a mixture of the biomass-derived crude HBA and petrochemical-derived HBA of Experimental Example 1 in a molar ratio of 50 / 50. The analysis results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0108] [Example 8] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 7, except that the biomass-derived crude HBA of Experimental Example 1 and petrochemical-derived HBA were used in a molar ratio of 90 / 10. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 3.

[0109] [Comparative Example 1] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 1, except that only petrochemical-derived HBA was used as the HBA. The analysis results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 4.

[0110] [Comparative Example 2] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 5, except that only petrochemical-derived HBA was used as the HBA. The analysis results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 4.

[0111] [Comparative Example 3] A heat-treated liquid crystalline polyester fiber was obtained in the same manner as in Example 7, except that only petrochemical-derived HBA was used as the HBA. The analysis results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 4.

[0112] Comparative Example 4 A reaction vessel equipped with a stirring blade, a distillation pipe, and a reaction solution discharge pipe was charged with HBA, FDCA, TA, BP, Ac, and the like. ２ O and KOAc were added to give a molar ratio of 60 / 10 / 10 / 20 / 105 / 0.005. At this time, the HBA used was a mixture of biomass-derived crude HBA and petrochemical-derived HBA from Experimental Example 1 in a molar ratio of 10 / 90. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and the reaction solution was stirred while the liquid temperature was raised from room temperature to 160 ° C. at 2 ° C. / min, and refluxed at 160 ° C. for 3 hours. At this point, the reaction solution was a white suspension. Next, the temperature was raised from 160 ° C. to 300 ° C. at 2 ° C. / min while distilling off the evaporated liquid. The reaction solution began to turn brown when it reached 240 ° C., and when it reached 300 ° C., it became a dark brown suspension. This reaction liquid was brittle at room temperature, and in the molten state it had low viscosity and was not spinnable. Therefore, it appears that heating up to 300°C caused significant thermal degradation, and spinning was not possible.

[0113] Comparative Example 5 A reaction vessel equipped with a stirring blade, a distillation pipe, and a reaction solution discharge pipe was charged with HBA, TA, BP, EG, Ac, and the like. ２ O and KOAc were added to give a molar ratio of 56 / 22 / 6 / 16 / 105 / 0.005. At this time, HBA was used in a molar ratio of 10 / 90, consisting of the biomass-derived crude HBA and petrochemical-derived HBA from Experimental Example 1. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and the reaction solution was stirred while the liquid temperature was raised from room temperature to 160 ° C. at 2 ° C. / min, and refluxed at 160 ° C. for 3 hours. At this point, the reaction solution was a white suspension. Next, the temperature was raised from 160 ° C. to 300 ° C. at 2 ° C. / min while distilling off the evaporated liquid, and stirring was continued at 300 ° C. for 1 hour. Next, the pressure in the reaction vessel was reduced to 100 Pa over 1.5 hours, and stirring was continued. When the reaction solution reached a molten resin with a predetermined viscosity, stirring was stopped and nitrogen was introduced into the reaction vessel. The reactor was then pressurized to 3 atmospheres with nitrogen, and the resin was taken out as strands with a diameter of 2 mm from the discharge pipe at the bottom of the reactor, and pelletized with a rotary cutter to obtain liquid crystal polyester resin chips.

[0114] The resin chips were dried with hot air at 120 ° C for more than 4 hours, and then melt-extruded using a Φ15 mm twin-screw extruder at a heater temperature of 270 ° C. The resin melt was supplied to the spinning head while being metered using a gear pump. The spinning head was equipped with a spinneret with a hole diameter of 0.125 mm and 50 holes, and the resin melt was discharged at a discharge rate of 28 g / min and wound onto a bobbin at a winding speed of 1000 m / min to obtain a liquid crystal polyester fiber spun yarn. At this time, a 2 wt% aqueous solution of sodium dodecyl phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., Wako Grade 1) was applied to the spun yarn from an oiling guide located directly below the spinneret. The amount of this aqueous solution applied was 1.4 g / min, and the calculated deposition ratio of sodium dodecyl phosphate to the spun yarn was 0.1 wt%.

[0115] Next, 4 kg of the obtained raw spun yarn was rewound onto an aluminum bobbin and heat-treated in a closed oven under a nitrogen atmosphere at a temperature of the melting point of the raw spun yarn -10°C for 16 hours to obtain a heat-treated liquid crystalline polyester fiber. The analytical results of the obtained liquid crystalline polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 4.

[0116] Reference Example 1: 1.2 parts by weight of carbon black powder (CB; Thermo Scientific, acetylene, 100% compressed, 99.9%+%) was added to 98.8 parts by weight of a liquid crystal polyester resin using only petroleum-derived HBA as the HBA, and the mixture was thoroughly mixed using a shaker. The resulting blend was then dried with hot air at 120°C for at least 4 hours and melt-spun to obtain a heat-treated liquid crystal polyester fiber yarn in the same manner as in Example 1. The resulting liquid crystal polyester fiber (raw spun yarn and heat-treated yarn) was dark gray. The analysis results of the resulting liquid crystal polyester fiber (raw spun yarn and heat-treated yarn) are shown in Table 4.

[0117]

[0118]

[0119] As shown in Table 3, the liquid crystal polyester fibers of Examples 1 to 8 have traceability using the biobased content as an index by using biomass-derived monomers. These biobased content measurements are in good agreement with the biobased content calculated from the feed ratio of the biomass-derived monomers, and can be set to desired values, making them useful as traceability information. Furthermore, because the liquid crystal polyester fibers of Examples 1 to 8 have specific compositions, they have mechanical properties comparable to the liquid crystal polyester fibers of Comparative Examples 1 to 3, which have a biobased content of 0%. In particular, the liquid crystal polyester fibers of Examples 1, 2, 4, 5, and 7 have nitrogen impurity contents of 5 to 500 μg / g relative to the weight of the liquid crystal polyester fiber, and therefore have mechanical properties equivalent to the liquid crystal polyester fibers of Comparative Examples 1 to 3, which have a biobased content of 0%.

[0120] On the other hand, the liquid crystal polyester fibers of Comparative Examples 1 to 3 have a bio-based content of 0% and have no traceability to conventional liquid crystal polyester fibers.

[0121] In Comparative Example 4, during the melt polymerization reaction of the liquid crystal polyester resin, a deterioration reaction thought to be caused by thermal decomposition of FDCA, a heterocyclic aromatic monomer, progressed significantly once the temperature reached 240°C, and a liquid crystal polyester resin having spinnability could not be obtained.

[0122] The liquid crystal polyester fiber of Comparative Example 5 has traceability using the bio-based content as an index by using a biomass-derived monomer. However, because a predetermined amount of EG, a non-wholly aromatic monomer, is used, the tensile strength and elastic modulus are lower than those of the liquid crystal polyester fibers of Examples 1 to 8, and it cannot be said that the fiber has sufficient mechanical properties.

[0123] The liquid crystal polyester fiber of Reference Example 1 can be said to have traceability using color as an index by mixing carbon black into the liquid crystal polyester resin. However, the tensile strength is lower than that of the liquid crystal polyester fibers of Examples 1 to 8, possibly because the carbon black particles act as foreign matter, and it cannot be said to have sufficient mechanical properties.

[0124] The liquid crystal polyester fiber can be used in the form of various fiber structures for various applications such as general industrial materials, civil engineering and construction materials, various reinforcing materials, electrical and electronic component materials, various textile products, etc. In particular, since the liquid crystal polyester fiber has traceability using the bio-based content as an index, it can be more suitably used as, for example, fishing gear, fishing tackle, marine ropes, submarine cable covering materials, etc.

[0125] As described above, the preferred embodiment of the present invention has been described, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention, and such additions, modifications, or deletions are also included within the scope of the present invention.

Claims

1. A liquid crystal polyester fiber comprising a liquid crystal polyester containing structural units derived from at least one aromatic hydroxycarboxylic acid, in which the total content of structural units derived from non-totally aromatic monomers and structural units derived from non-linear aromatic monomers is less than 5 mol% of the total content of all structural units, and the content of structural units derived from heterocyclic aromatic monomers is less than 3 mol% of the total content of all structural units, and having a bio-based content of 1% or more.

2. The liquid crystal polyester fiber according to claim 1, wherein the nitrogen content of components contained other than the liquid crystal polyester is 5 to 500 μg / g based on the weight of the liquid crystal polyester fiber.

3. A liquid crystal polyester fiber according to claim 1 or 2, having a tensile strength of 18 cN / dtex or more.

4. A liquid crystal polyester fiber according to claim 1 or 2, wherein the liquid crystal polyester contains structural units derived from 4-hydroxybenzoic acid, at least a portion of which are biomass-derived structural units.

5. A liquid crystal polyester fiber according to claim 1 or 2, wherein the content of particulate matter inside the fiber is 1.0% by weight or less.

6. A fiber structure comprising at least a part of the liquid crystal polyester fiber according to claim 1 or 2.

7. A textile structure according to claim 6, which is a fishing tackle, fishing gear, marine rope or undersea cable covering material.

8. A method of measuring the bio-based content of liquid crystal polyester fiber and using that bio-based content as traceability information.

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