Liquid crystal polyester chip-shaped article, recycled liquid crystal polyester molded body, and method for producing same

Abstract

Provided is a liquid crystal polyester chip-shaped article containing a recovered liquid crystal polyester molded body as at least part of a raw material. This liquid crystal polyester chip-shaped article is a chip-shaped article containing a recovered liquid crystal polyester molded body as a raw material, and having a bulk density of 0.15-1.20 g / mL, wherein the average value of the maximum length of the chip-shaped article is 3-30 mm.

Description

Liquid crystal polyester chips, recycled liquid crystal polyester moldings, and methods for producing them Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2023-177123, filed on October 12, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a liquid crystal polyester chip material formed using a recovered liquid crystal polyester molded product as at least a part of a raw material, and a method for producing the same, and further relates to a recycled liquid crystal polyester molded product formed from the liquid crystal polyester chip material, and a method for producing the same.

[0003] In recent years, society has been demanding the development of products and manufacturing methods that have a low environmental impact. For example, in the textile industry, there has been a push to collect and recycle commercially available clothing textiles such as polyester and nylon. However, high-performance fibers with high strength, heat resistance, and chemical resistance are difficult to recycle even after collection, and recycling has not progressed substantially.

[0004] As a technology relating to the recycling of high-performance fibers, for example, Patent Document 1 (JP 2004-100066 A) discloses a method for reusing used heat-resistant, high-performance yarn products, in which used heat-resistant, high-performance yarn products are washed and crushed, and a nonwoven fabric is formed from the resulting cotton-like material.

[0005] Furthermore, Patent Document 2 (Japanese Patent Laid-Open Publication No. 2005-105491) discloses a recycled spun yarn obtained by using 5 to 95 mass % of short fibers obtained by recycling used high-performance fiber products.

[0006] JP 2004-100066 A JP 2005-105491 A

[0007] However, in both Patent Documents 1 and 2, the fiber shape derived from used fibers is utilized as is, and there is no technical idea of ​​reshaping and processing the fibers, and it cannot be said that there is a high degree of freedom in recycling fibers.

[0008] Therefore, an object of the present invention is to provide a liquid crystal polyester chip-like material formed using a recovered liquid crystal polyester molding as a raw material, and a method for producing the same. Another object of the present invention is to provide a recycled liquid crystal polyester molding formed from the liquid crystal polyester chip-like material, and a method for producing the same.

[0009] The present inventors have conducted extensive research to solve the problems of the prior art described above, and as a result, have discovered a new problem: when recycled as a raw material from recovered liquid crystal polyester molded bodies, when melt-molded in an extruder, the shape of the body affects the feedability when fed into the extruder, the ability to be meshed with the extruder screw, the melt-kneading ability in the extruder, etc., and recycling may be difficult simply by using the recovered liquid crystal polyester molded body as a raw material. Further research has revealed that when the chip-like material formed from the recovered liquid crystal polyester molded body has a bulk density of 0.15 to 1.20 g / mL and an average maximum length of 3 to 30 mm, not only can the chip-like material be transported to the kneading section of the cylinder without causing the extruder screw to idle, but also that the recycled product formed from the chip-like material becomes a high-quality recycled liquid crystal polyester molded body, leading to the completion of the present invention.

[0010] That is, the present invention can be configured in the following aspects. [Aspect 1] A chip-like material containing a recovered liquid crystalline polyester molded product as a raw material, the chip-like material having a bulk density of 0.15 to 1.20 g / mL (preferably 0.30 to 1.15 g / mL, more preferably 0.55 to 1.10 g / mL, even more preferably 0.65 to 1.08 g / mL, and most preferably 0.85 to 1.05 g / mL) and an average maximum length of the chip-like material of 3 to 30 mm (preferably 3.5 to 20 mm, more preferably 5 to 15 mm). [Aspect 2] The liquid crystalline polyester chip-like material according to Aspect 1, wherein the ketone bond content of the liquid crystalline polyester is 0.050 mol% or less (preferably 0.045 mol% or less, more preferably 0.040 mol% or less). [Aspect 3] The liquid crystal polyester chip material according to Aspect 1 or 2, wherein the total amount of carboxyl terminals of the liquid crystal polyester is 20 meq / kg or less (preferably 15 meq / kg or less, more preferably 10 meq / kg or less). [Aspect 4] The liquid crystal polyester chip material according to any one of Aspects 1 to 3, wherein the total amount of one terminal of the liquid crystal polyester is 2 to 100 meq / kg (preferably 3 to 100 meq / kg, more preferably 5 to 100, even more preferably 10 to 100 meq / kg, still more preferably 20 to 100 meq / kg, particularly preferably 50 to 100 meq / kg, even more particularly preferably 55 to 99 meq / kg, and still more particularly preferably 60 to 85 meq / kg).[Aspect 5] A method for producing a liquid crystal polyester chip material, comprising at least the steps of: preparing a recovered liquid crystal polyester molded body as a raw material molded body; integrating the raw material molded body, or, if necessary, a preform obtained by cutting or pulverizing the raw material molded body, to form an integrated body; and cutting the integrated body to produce chip-like products having a bulk density of 0.15 to 1.20 g / mL (preferably 0.30 to 1.15 g / mL, more preferably 0.55 to 1.10 g / mL, even more preferably 0.65 to 1.08 g / mL, and most preferably 0.85 to 1.05 g / mL) and an average maximum length of 3 to 30 mm (preferably 3.5 to 20 mm, more preferably 5 to 15 mm). [Aspect 6] A method for producing a liquid crystal polyester chip material according to Aspect 5, wherein the integrating step is performed by thermoforming. [Aspect 7] A method for producing the liquid crystal polyester chip material according to Aspect 5 or 6, wherein a degassing treatment is carried out in the integration step. [Aspect 8] A recycled liquid crystal polyester molded product comprising, as a raw material, at least the liquid crystal polyester chip material according to any one of Aspects 1 to 4. [Aspect 9] The recycled liquid crystal polyester molded product according to Aspect 8, which is a recycled liquid crystal polyester fiber structure. [Aspect 10] The recycled liquid crystal polyester molded product according to Aspect 9, which comprises recycled liquid crystal polyester fibers having a single fiber fineness of 50 dtex or less (preferably 15 dtex or less, more preferably 10 dtex or less, and even more preferably 7 dtex or less). [Aspect 11] A method for producing a recycled liquid crystal polyester molded product, comprising the steps of: preparing, as a raw material, the liquid crystal polyester chip material according to at least any one of Aspects 1 to 4; and melt-extruding the liquid crystal polyester chip material.

[0011] 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.

[0012] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention.

[0013] In the present invention, even when recovered liquid crystal polyester moldings are used as raw materials, by forming the chip-like material into chips having specific bulk density and dimensions, it is possible to efficiently melt-knead the chip-like material in an extruder, and various recycled moldings (e.g., recycled liquid crystal polyester fibers) can be obtained.

[0014] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and explanation purposes only and should not be used to define the scope of the present invention, which is defined by the appended claims.

[0015] 1 is a schematic perspective view illustrating a method for measuring the maximum length of a chip-like material of one embodiment. FIG. 2 is a schematic perspective view illustrating a method for measuring the maximum length of a chip-like material of one embodiment. FIG. 3 is a photograph of the chip-like material obtained in Example 1.

[0016] [Liquid Crystal Polyester] The liquid crystal polyester constituting the liquid crystal polyester chip material is a polyester that exhibits optical anisotropy (liquid crystallinity) in the molten phase. This can be confirmed, for example, by placing a sample on a hot stage, heating it under a nitrogen atmosphere, and observing the transmitted light through the sample with a polarizing microscope. The liquid crystal polyester may be a polyester mainly composed of structural units containing aromatic groups in the main chain, and the bonds between the structural units are mainly ester bonds. However, a wholly aromatic liquid crystal polyester in which all structural units contain aromatic groups in the main chain is preferred. The liquid crystal polyester may be composed of structural units derived from, for example, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxycarboxylic acids, etc., and the structural units derived from aromatic diols, aromatic dicarboxylic acids, and aromatic hydroxycarboxylic acids are not particularly limited in terms of their chemical structure, as long as the effects of the present invention are not impaired. Furthermore, the liquid crystal polyester may be a liquid crystal polyester amide containing structural units derived from aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids, as long as the effects of the present invention are not impaired. For example, preferred structural units include the examples shown in Table 1.

[0017]

[0018] In the structural units in Table 1, m is an integer of 0 to 2, and Y in the formula, in the range of 1 to the maximum number that can be substituted on an aromatic ring or a cycloring, each independently represents a hydrogen atom, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group (e.g., an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, etc.), an alkoxy group (e.g., a methoxy group, an ethoxy group, an isopropoxy group, a n-butoxy group, etc.), an aryl group (e.g., a phenyl group, a naphthyl group, etc.), an aralkyl group (e.g., a benzyl group (phenylmethyl group), a phenethyl group (phenylethyl group), etc.), an aryloxy group (e.g., a phenoxy group), an aralkyloxy group (e.g., a benzyloxy group, etc.), etc.

[0019] More preferred structural units include the structural units described in Examples (1) to (20) shown in the following Tables 2, 3, and 4. When the 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 structural units that constitute the polymer.

[0020]

[0021]

[0022]

[0023] In the structural units of Tables 2, 3 and 4, n is an integer of 1 or 2, and each structural unit n=1 and n=2 may exist alone or in combination; Y １ and Y ２ may each independently be a hydrogen atom, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group (e.g., an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, etc.), an alkoxy group (e.g., a methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, etc.), an aryl group (e.g., a phenyl group, a naphthyl group, etc.), an aralkyl group (e.g., a benzyl group (phenylmethyl group), a phenethyl group (phenylethyl group), etc.), an aryloxy group (e.g., a phenoxy group), an aralkyloxy group (e.g., a benzyloxy group), etc. Of these, a hydrogen atom, a chlorine atom, a bromine atom, or a methyl group is preferred.

[0024] Examples of Z include substituents represented by the following formulas.

[0025]

[0026] In one embodiment, the liquid crystal polyester may contain a structural unit derived from a hydroxycarboxylic acid as a main component. The liquid crystal polyester may preferably contain 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 preferably be 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.

[0027]

[0028]

[0029] The liquid crystal polyester may contain a structural unit derived from 4-hydroxybenzoic acid (structural unit (A)) and / or a structural unit derived from 6-hydroxy-2-naphthoic acid (structural unit (B)), and the total content of the structural unit (A) and the structural unit (B) relative to the total amount of all structural units may be 40 mol% or more, preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more.

[0030] For example, the melting point of the liquid crystalline polyester may be 250° C. or higher, preferably 260° C. or higher, and more preferably 280° C. or higher. On the other hand, when recovered and thermoformed into chips or from the viewpoint of melt moldability, the melting point of the liquid crystalline polyester may be 380° C. or lower, preferably 360° C. or lower, and more preferably 340° C. or lower.

[0031] 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 7121:2012 test method. Specifically, 4 to 6 mg of a sample is placed in an aluminum pan and sealed in a DSC apparatus. Then, nitrogen is flowed as a carrier gas at a flow rate of 200 mL / min, and the endothermic peak is measured when the temperature is increased from room temperature (e.g., 25°C) at a rate of 10°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 increase the temperature at a rate of 10°C / min to measure the endothermic peak.

[0032] The liquid crystal polyester chip material may contain, within the scope of not impairing the effects of the present invention, a thermoplastic resin such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, etc. Furthermore, it may contain various additives such as inorganic substances such as titanium oxide, kaolin, silica, barium oxide, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers, light stabilizers, etc.

[0033] The liquid crystal polyester chip material may contain 50% by weight or more of the liquid crystal polyester, preferably 80% by weight or more, more preferably 90% by weight or more. From the viewpoint of improving the recycling rate, a liquid crystal polyester chip material having a high purity of the liquid crystal polyester is preferred, and it is more preferred that the liquid crystal polyester contains 95% by weight or more, and even more preferred that the liquid crystal polyester contains 98% by weight or more.

[0034] [Method for producing liquid crystal polyester chip material] The liquid crystal polyester chip material of the present invention can be a raw material molded product obtained by recovering used liquid crystal polyester molded products, or defective products and plastic waste (e.g., offcuts, residue, burrs, etc.) generated during the manufacturing process of liquid crystal polyester molded products. Examples of molded products include fibers, films, and various molded products. From the recovered plastic waste, etc., a sorting process such as classification may be carried out to obtain chip-like products having a bulk density of 0.15 to 1.20 g / mL and an average maximum length of 3 to 30 mm.

[0035] For example, when liquid crystal polyester fiber is used as a raw material molded body, used liquid crystal polyester fiber products (for example, untreated yarn, heat-treated yarn in which the untreated yarn is heat-treated to promote solid-state polymerization of the liquid crystal polyester and improve mechanical properties such as tensile strength, or fiber structures processed from these), residual yarns and waste yarns of liquid crystal polyester fiber generated during the manufacturing process (for example, residual yarns of liquid crystal polyester fiber remaining in a paper tube or bobbin), etc. can be collected and used as raw materials. Commercially available liquid crystal polyester fibers include Vectran UM (trademark) manufactured by Kuraray Co., Ltd., Vectran HT (trademark) manufactured by Kuraray Co., Ltd., Scivelas (trademark) manufactured by Toray Industries, Inc., and Zexion (trademark) manufactured by KB Seiren Co., Ltd.

[0036] The residual yarn or waste yarn of the liquid crystal polyester fiber generated during the production process may be any of a discharged yarn obtained immediately after spinning, an untreated yarn before solid-state polymerization treatment, or a heat-treated yarn after solid-state polymerization, but it is preferable to use an untreated yarn before processing into a fiber structure because it is less susceptible to adhesion or inclusion of dirt or foreign matter. The untreated yarn can be obtained by recovering the residual yarn from a processing plant when untreated yarn is processed into a fiber structure, or by recovering the untreated yarn (raw spun yarn) remaining when transferred to a heat treatment step during the process of producing a liquid crystal polyester fiber.

[0037] Furthermore, when liquid crystal polyester film is used as a raw material, it is often used as an insulating material for circuit boards due to its low moisture absorption, heat resistance, chemical resistance, and excellent electrical properties. Metal-clad laminates, in which metal foil is laminated on a liquid crystal polyester film, are also used as materials for manufacturing circuit boards. Therefore, scraps generated during the film manufacturing process, metal-clad laminate manufacturing process, and circuit board manufacturing process can be collected as raw materials for liquid crystal polyester film. Alternatively, when a film is processed into a metal-clad laminate, film may remain on the film core. The remaining film can be collected from the processing plant, or the remaining pre-heat-treated film (raw film) left over during the heat treatment process during the film manufacturing process can be collected.

[0038] The molding step into chip-like products can be appropriately determined depending on the shape of the liquid crystal polyester molded product (hereinafter sometimes abbreviated as raw material molded product) as a raw material.

[0039] (I) Crushing and / or Cutting Treatment When the maximum length of the raw material compact exceeds 30 mm, the raw material compact is subjected to a crushing treatment, a cutting treatment, or a combination of these treatments. When the bulk density of the granules obtained by the crushing and / or cutting treatment is 0.15 to 1.20 g / mL and the maximum length is 3 to 30 mm, the granules may be used as chips as they are, or the granules obtained by the crushing and / or cutting treatment may be further subjected to an integration treatment as a preform. For the crushing and / or cutting treatment, for example, scissors, a press cutter, a slitter, a pulverizer, or the like can be selected depending on the shape of the raw material compact.

[0040] (II) Cleaning Treatment Prior to the integration treatment, the raw material molded body or preformed body may be subjected to a cleaning treatment to increase the purity of the liquid crystalline polyester. The cleaning treatment can remove, for example, additives (e.g., oils and adhesives) adhering to the raw material molded body or preformed body, and other components (e.g., metal foil) adhering to the raw material molded body or preformed body. In the cleaning treatment, the type of cleaning solution and the contact time between the cleaning solution and the raw material molded body or preformed body can be adjusted within a range that suppresses deterioration of the liquid crystalline polyester.

[0041] The cleaning solution can be selected depending on the material to be removed, and may be any of an acidic solvent, an alkaline solvent, an organic solvent, and an aqueous solvent. These cleaning solutions may be used alone or in combination. Furthermore, various solvents may contain a cleaning agent such as a surfactant, if necessary.

[0042] For example, various etching solutions may be used to remove metal components, and organic solvents or aqueous solvents containing surfactants and / or solvents may be used to efficiently remove dirt and oils.

[0043] The cleaning treatment may be carried out by immersing the raw material compact or preform in a cleaning solution, or by spraying the cleaning solution onto the raw material compact or preform. When immersing, the cleaning solution may be used in a static bath (e.g., a drawing bath) or a rotating bath (e.g., an industrial washing machine).

[0044] The pulverization and / or cutting treatment may be performed in combination with the washing treatment. In this case, the order of the two treatments is not particularly limited, but it is preferable that the washing treatment is performed after the pulverization and / or cutting treatment.

[0045] (III) Integration Treatment The raw material compact or preform may be subjected to an integration treatment. In the integration treatment, a compact (hereinafter sometimes referred to as an integrated body) can be obtained by thermoforming and / or adhesion-molding the raw material compact or preform. The integrated body may be a one-dimensional compact such as a string-like compact, or a two-dimensional compact such as a sheet-like compact.

[0046] In thermoforming, the raw material compact or preform can be integrated by heat treatment. The heating temperature can be appropriately set depending on the melting point of the raw material compact or preform used. When the melting point of the raw material compact or preform is Tm, the heating temperature may be, for example, Tm-5 to Tm+40°C, preferably Tm to Tm+30°C, and more preferably Tm+5 to Tm+25°C.

[0047] Before thermoforming, if necessary, a melting point determination step may be performed to determine the melting point of the material to be heated, and a sorting step may be performed to separate the material according to the determined melting point and select material having a similar melting point as the material to be heated. The melting point of the material to be heated is a value measured by the method described in the Examples below.

[0048] In the thermoforming process, a raw material compact or preform may be used whose moisture content has been reduced in advance; for example, the moisture content of the raw material compact or preform may be 500 ppm or less, preferably 400 ppm or less, more preferably 300 ppm or less, more preferably 200 ppm or less, more preferably 100 ppm or less, and more preferably 50 ppm or less.

[0049] In addition, during thermoforming, a heat press treatment may be performed as necessary. By performing the heat press treatment, the liquid crystal polyester resin may be fused and integrated. The heat press treatment may be a sheet-type method or a roll-to-roll method. Specifically, a method of pressing into a sheet using a hot plate, a method of pressing into a sheet using a hot roll, a method of sandwiching between wire mesh or a metal belt and heat pressing into a sheet, etc. may be mentioned.

[0050] The pressing pressure in the heat pressing treatment may be, for example, 0.5 to 20 MPa, preferably 1 to 15 MPa, and more preferably 1.5 to 10 MPa, in terms of surface pressure. The pressing time may be, for example, 1 to 10 minutes, preferably 1.5 to 8 minutes, and more preferably 2 to 7 minutes. In the case of a roll-to-roll method, a value obtained by converting the linear pressure into surface pressure may be used. The heat pressing treatment may be performed in a single treatment, or may be performed after a degassing treatment, if necessary.

[0051] If necessary, degassing pressing may be performed as the degassing treatment, and the degassing pressing may be performed at the above-mentioned surface pressure, for example, 3 to 20 times, preferably 5 to 15 times, for a single pressing time of, for example, 1 to 30 seconds, preferably 2 to 25 seconds, more preferably 3 to 20 seconds.

[0052] In thermoforming, it is preferable to bring the raw material molded body or preform into contact with a release-treated device in order to prevent the molten liquid crystal polyester resin from adhering to the device used. For example, the metal plate or heat roll used in the heat press treatment is preferably subjected to a release treatment such as a fluorine coating or silicone coating. The press treatment may also be performed via a release material such as a fluorine sheet, a silicone sheet, or a polyimide film. The degassing and thermoforming are preferably performed in an inert gas or vacuum atmosphere.

[0053] When the raw material molded body is in a fibrous shape, the resulting chip-like material may have at least a part of a shape derived from the liquid crystal polyester fiber. For example, when the raw material molded bodies are aligned in approximately one direction or randomly arranged and subjected to a heat press treatment, the integrated body after the heat press treatment and the chip-like material obtained from the integrated body may have a part (for example, an outer edge portion) of a shape derived from the liquid crystal polyester fiber.

[0054] For example, the fibrous material to be thermoformed may be thermoformed in a pre-aligned state. For example, aligned fibers may be twisted together, and the twisted fiber bundle may be thermoformed into a rod shape in a hot air oven. Alternatively, when the raw material molded product is in a fibrous form, aligned fibers may be twisted together as needed to form a fiber bundle, which may then be covered with a thermoplastic resin sheet (e.g., a liquid crystal polyester sheet, the above-mentioned thermoplastic resin miscible with liquid crystal polyester, etc.), and the covering may be heated to melt the thermoplastic resin, thereby integrating the entire product. The thermoplastic resin sheet may have the same melting point as the raw material molded product, but preferably has a melting point lower than that of the raw material molded product.

[0055] In one embodiment of the integration process, when the raw material molded body is in the form of a long fiber or film, twisting may be performed to form a twisted string, and then the twisted string may be compressed to form a crimped twisted string as an integrated body. Heating may also be performed before and / or after twisting (e.g., during compression), and softening by heating may facilitate twist formation and / or crimping. For example, a raw material molded body in the form of a continuous fiber may be twisted to form a continuous twisted yarn, which may then be molded by hot pressing to form an integrated body, and chips of predetermined dimensions may be formed by the cutting process described below. The formation of the twisted yarn, the formation of the integrated body, and the cutting process may be performed using the same device or different devices.

[0056] For example, in one embodiment of this integration process, a twisted string manufacturing apparatus may be used that includes a supply section that serves as the starting point for twisting the long raw material compacts, and a rotary compression section that rotates the raw material compacts sent from the supply section to impart twist and point-pressure to form a crimped twisted string with concave indentations. The rotary compression section may include a rotating section and a compression section installed within the rotating section. In the supply section, the raw material compacts are clamped to form the starting point for twisting, and the raw material compacts are twisted by rotation in the rotating section. In the compression section, the raw material compacts are clamped between a pair of compression rollers with a predetermined pressure, thereby forming a crimped twisted string. In this case, a heating section and an intermediate feed section may be provided between the supply section and the rotary compression section (in this case, the intermediate rollers of the intermediate feed section serve as the starting point for twisting the raw material compacts). The cutting process described below can also be performed using a chip-like material manufacturing apparatus that further includes a cutting section that cuts the crimped twisted string sent from the rotary compression section to a predetermined length.

[0057] In adhesion molding, the raw material compacts or pre-molded bodies can be integrated using an adhesive such as a bundling agent. After adhesion molding, the above-mentioned thermoforming may be further carried out as necessary.

[0058] The proportion of adhesive used in adhesion molding may be within a range that allows control of the bulk density of the chip-like material, and may be, for example, 0.1 to 10% by weight, preferably 0.5 to 8% by weight, in terms of solid content of the adhesive based on the total weight.

[0059] The adhesive may be applied to the raw material compact or preform by immersion, coating, or spraying. In particular, when the raw material compact is in the form of fibers, the sizing agent may be applied to the aligned fibers by immersion, coating, or spraying to integrate them.

[0060] The adhesive is not particularly limited as long as it can integrate the raw material molded body or pre-molded body, but examples include known or commonly used adhesives such as polyurethane-based adhesives, polysiloxane-based adhesives, polyamide-based adhesives, polyolefin-based adhesives, and epoxy-based adhesives.

[0061] (IV) Cutting Treatment The integrated body after integral molding may be subjected to cutting treatment as needed. The cutting treatment is not particularly limited as long as it does not impair the effects of the present invention, and can be performed using, for example, scissors, a push cutter, a fan cutter, a slitter, etc. By cutting, chip-like products formed to a predetermined size can be obtained.

[0062] [Liquid Crystal Polyester Chip Material] The liquid crystal polyester chip material of the present invention is formed from a recovered liquid crystal polyester molded product and has specific bulk density and dimensions. The bulk density of the liquid crystal polyester chip material of one embodiment is 0.15 to 1.20 g / mL, preferably 0.30 to 1.15 g / mL, more preferably 0.55 to 1.10 g / mL, even more preferably 0.65 to 1.08 g / mL, and most preferably 0.85 to 1.05 g / mL.

[0063] When the bulk density of the liquid crystal polyester chip material is 0.15 g / mL or more, the chip material has excellent feedability when fed into an extruder, excellent bite into the extruder screw, and good melt-kneading properties in the extruder. When the bulk density is 1.20 g / mL or less, the chip material is less likely to be contaminated with foreign matter, and the physical properties of the molded product obtained from the chip material tend to be improved.

[0064] Here, the bulk density of the liquid crystal polyester chip material is calculated with reference to JIS Z 2504 by pouring the liquid crystal polyester chip material into a measuring container without using a funnel, and then measuring the weight of the chip material in the measuring container with an electronic balance without compressing the chip material in the measuring container by tapping or the like, and calculating the bulk density per internal area of ​​the measuring container.

[0065] The dimensions of the liquid crystal polyester chip material of one embodiment may be such that the average maximum length is 3 to 30 mm, preferably 3.5 to 20 mm, and more preferably 5 to 15 mm. When the average maximum length is 3 mm or more, the chip material has excellent feedability when fed into a melt extruder and excellent biteability into the extruder screw. Even when the average maximum length is 30 mm or less, the chip material has excellent feedability when fed into a melt extruder and excellent biteability into the extruder screw.

[0066] The maximum length of one embodiment of the liquid crystal polyester chip material can be measured by measuring the longest length from one end to the other end of the projected area when the chip material is placed on a flat surface. A simple method can be measured using an electronic caliper, a scale-equipped stereomicroscope, an automatic shape measuring instrument, etc. For example, in the chip material shown in Figure 1, the longest part of the chip material is placed parallel to the Y direction in the vertical direction (X direction), horizontal direction (Y direction), and height direction (Z direction), and the length in the Y direction is measured as the length of the longest side. In addition, in the chip material having a square surface shown in Figure 2, the longest side is the length of the diagonal of the square.

[0067] In addition, the dimensions of one embodiment of the liquid crystal polyester chip material may be such that the average minimum length is 0.1 to 10 mm, preferably 0.1 to 8 mm, and more preferably 0.3 to 5 mm. The minimum length of the liquid crystal polyester chip material can be measured by measuring the shortest length from one end to the other end of the projected area when the chip material is placed on a flat surface, and can be measured simultaneously with the measurement of the maximum length. For example, the chip material shown in FIG. 1 is placed so that the length in the Y direction is the maximum length of the chip material, and in this case, the length in the Z direction is measured as the minimum length of the chip material. Furthermore, in the rectangular chip material shown in FIG. 2, the shortest side is the height of the rectangular parallelepiped (length in the Z direction). However, when the longest point of the chip material is placed parallel to the Y direction, the shortest length is not necessarily the length parallel to the X direction or the Z direction, and the shortest point is determined separately.

[0068] The ketone bond amount of the liquid crystal polyester in one embodiment of the liquid crystal polyester chip material is preferably 0.050 mol% or less, more preferably 0.045 mol% or less, and even more preferably 0.040 mol% or less. In this specification, the ketone bond amount means the ratio of the molar amount of ketone bonds to the total molar amount of ester bonds and ketone bonds (molar amount of ketone bonds / (molar amount of ester bonds + molar amount of ketone bonds)), and is a value measured by the method described in the Examples below. The lower limit of the ketone bond amount is not particularly limited, but may be about 0.001 mol%.

[0069] Ketone bonds are heterogeneous bonds formed by a side reaction from ester bonds during the production of liquid crystal polyester molded articles. The amount of ketone bonds also increases with thermal degradation of the liquid crystal polyester, and can therefore be an indicator of thermal degradation of chip-shaped materials. For example, when chip-shaped materials are obtained by thermoforming, chip-shaped materials with reduced thermal degradation can be obtained by lowering the molding temperature during thermoforming. The obtained chip-shaped materials can be treated as equivalent to virgin liquid crystal polyester chips, and high-quality molded products can be produced.

[0070] In one embodiment of the liquid crystal polyester chip material, from the viewpoint of suppressing the amount of gas generated during heat melting, the total amount of carboxy terminals of the liquid crystal polyester (hereinafter referred to as the total CEG amount) may be, for example, 20 meq / kg or less, preferably 15 meq / kg or less, more preferably 10 meq / kg or less. The lower limit of the total CEG amount is not particularly limited, but may be 1 meq / kg or more.

[0071] The total CEG amount is a value measured by the method described in the Examples below, and is the amount of carboxy groups present at the molecular terminals of the molecules constituting the liquid crystal polyester chip material in 1 kg of chip material. For example, the carboxy groups present at the polymer terminals in the liquid crystal polyester are formed by structural units derived from monomers having a carboxy group, such as aromatic hydroxycarboxylic acid or aromatic dicarboxylic acid, and may be carboxy groups remaining unreacted in such structural units present at the polymer terminals.

[0072] In one embodiment of the liquid crystal polyester chip material, the total amount of single terminals of the liquid crystal polyester may be, for example, 2 to 100 meq / kg, preferably 3 to 100 meq / kg, more preferably 5 to 100, even more preferably 10 to 100 meq / kg, and even more preferably 20 to 100 meq / kg. From the viewpoint of melt moldability, the total amount of single terminals of the liquid crystal polyester chip material may be 50 to 100 meq / kg, preferably 55 to 99 meq / kg, and more preferably 60 to 85 meq / kg. The total amount of single terminals indicates the number of polymer chains and is used as an index for evaluating molecular weight. The larger the total amount of single terminals, the smaller the molecular weight, and the smaller the total amount of single terminals, the larger the molecular weight tends to be. Considering that it is difficult to quantify all types of terminals in a liquid crystal polyester due to its composition, in this specification, the total amount of single terminals is defined as a value obtained by dividing the total amount (meq / kg) of carboxyl group terminals derived from hydroxycarboxylic acid and terminals from which carbon dioxide has been released by a decarboxylation reaction that may occur as a side reaction in carboxyl groups derived from hydroxycarboxylic acid per 1 kg of liquid crystal polyester chip material by the molar ratio of structural units derived from hydroxycarboxylic acid in the liquid crystal polyester, and is a value measured by the method described in the examples below.

[0073] [Recycled Liquid Crystal Polyester Molded Product] A recycled liquid crystal polyester molded product of one embodiment can be produced using the liquid crystal polyester chip material of the present invention as a material. Examples of recycled liquid crystal polyester molded products include pellets, fibers, films, and various injection-molded products, which can be obtained by known or conventional production methods. The production method for recycled liquid crystal polyester molded products includes a step of preparing at least a chip material as a raw material and a step of melt-extruding the chip material.

[0074] The melt-extrusion process of the chip-like material can be carried out by a known or conventional method depending on the desired recycled liquid crystal polyester molding. For example, when forming pellets, a pelletizing process is carried out. In the pelletizing process of the chip-like material, in order to suppress the thermal deterioration of the liquid crystal polyester resin melted in the extruder, it is preferable to melt-knead the melting kneading temperature at a temperature equal to or lower than the melting point Tm of the liquid crystal polyester resin + 30 ° C. Here, the melt-kneading temperature means the temperature when the resin is melt-kneaded by the screw of the extruder, specifically the set temperature of the extruder.

[0075] Furthermore, in order to perform degassing during melt-kneading, it is preferable to provide a vent in the extruder and remove air from the cylinder of the extruder using a vacuum pump. For example, the extruder may be divided into a solid zone, a solid / melt mixing zone, and a melt zone, and vacuum degassing may be performed at a vent port disposed in any of the zones at a pressure of, for example, 0 to 90 kPa (preferably 0 to 80 kPa, more preferably 0 to 70 kPa). Of these, it is preferable to perform degassing at least in the melt zone, and preferably vacuum degassing may be performed at all of the vent ports.

[0076] The melt-kneaded resin is discharged from the extruder and then cut into pellets of a predetermined size by known or conventional means such as a strand cut method or a hot cut method.

[0077] For fibers, films, and various injection-molded articles, the melt-kneading temperatures described above for the pelletizing treatment can be used. During melt-kneading, degassing may be performed using the vent described above, if necessary.

[0078] In the process of melt-extruding the chip-like material, chip-like material whose moisture content has been reduced in advance may be used. For example, the moisture content of the chip-like material may be 500 ppm or less, preferably 400 ppm or less, more preferably 300 ppm or less, more preferably 200 ppm or less, more preferably 100 ppm or less, and more preferably 50 ppm or less.

[0079] The recycled liquid crystal polyester molded article of one embodiment may contain, in addition to the liquid crystal polyester chips, various thermoplastic resins such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, etc. Furthermore, it may contain various additives such as inorganic substances such as titanium oxide, kaolin, silica, barium oxide, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers, light stabilizers, etc., within the scope of the present invention.

[0080] The recycled liquid crystal polyester molding of one embodiment may contain virgin liquid crystal polyester resin, and the proportion of virgin liquid crystal polyester resin in the recycled liquid crystal polyester molding may be 5 to 97% by weight, preferably 10 to 96% by weight, and more preferably 20 to 95% by weight.

[0081] The ketone bond amount of the recycled liquid crystal polyester molded article of one embodiment is preferably 0.050 mol% or less, more preferably 0.045 mol% or less, and even more preferably 0.040 mol% or less, from the viewpoint of the physical properties of the molded article. The lower limit of the ketone bond amount is not particularly limited, but may be, for example, 0.0001 mol% or more.

[0082] In one embodiment, the cut surface of the recycled liquid crystalline polyester molding may have at least one atom selected from the group consisting of phosphorus atoms and sulfur atoms uniformly distributed. These atoms may be contained as a component to be attached to the surface of an oil or the like. For example, phosphorus atoms are applied to the surface of a raw material molding as a component of a general antistatic agent, so that in the raw material molding, the phosphorus atoms are distributed locally on the surface rather than inside the molding. On the other hand, in the recycled liquid crystalline polyester molding, if these atoms derived from the recovered raw material molding are mixed into the chip-like material, the recycled liquid crystalline polyester molding formed from the chip-like material has these atoms uniformly distributed not only on the surface but also inside the molding, so the distribution of these atoms on the cut surface can be used as traceability for the recycled liquid crystalline polyester molding. The distribution of these atoms in the fiber cross section can be examined by time-of-flight secondary ion mass spectrometry (TOF-SIMS).

[0083] (Recycled Liquid Crystal Polyester Fiber) One embodiment of the recycled liquid crystal polyester molded article may be a recycled liquid crystal polyester fiber. The recycled liquid crystal polyester fiber may be a single fiber consisting of one component of a liquid crystal polyester chip material, as long as the effects of the present invention are not impaired. Alternatively, the recycled liquid crystal polyester fiber may be a mixed spun fiber obtained by mixing a liquid crystal polyester chip material with a virgin liquid crystal polyester resin, various thermoplastic resins, and various additives and spinning the mixture.

[0084] The recycled liquid crystal polyester fiber of one embodiment may be a non-conjugated spun fiber or a conjugated spun fiber. The conjugated spun fiber may be a conjugated spun fiber obtained by simultaneously spinning a liquid crystal polyester chip material, various thermoplastic resins, and various additives from a separated spinneret. Such conjugated spun fibers may be various conjugated spun fibers, such as an islands-in-sea type, a sheath-core type, or a side-by-side type. Furthermore, in the sheath-core type or the side-by-side type, each component may further form a sea-island structure, if necessary.

[0085] For example, the method for producing recycled liquid crystal polyester filaments may include at least a step of melt-spinning liquid crystal polyester chips to obtain raw spun yarn.

[0086] In the spinning process, the liquid crystal polyester chips are fed into an extruder and melt-kneaded in the extruder. The melt-kneaded liquid crystal polyester is then transported to a spinning head and extruded from a nozzle. The resulting yarn is wound up to obtain a spun raw yarn. During winding, an oil may be applied to prevent static electricity.

[0087] As the extruder, known extruders such as a single-screw extruder and a multi-screw extruder (two or more screws) can be used, and a twin-screw extruder is preferred from the viewpoint of improving the intermeshing property, kneading property and degassing property.

[0088] The chip-like material may be fed into the extruder through a hopper, or any known feeding method may be used, such as a volumetric feeder, a gravimetric feeder, or a method of air feeding. From the viewpoint of metering, it is preferable to use a gravimetric feeder.

[0089] The melt spinning can be carried out by a known or conventional method, and the molten mixture is discharged from the nozzle of a spinning head and wound up by a godet roller or the like to obtain a raw spun yarn.

[0090] The ketone bond amount of the liquid crystal polyester in the recycled liquid crystal polyester filament as the raw spinning yarn may be preferably 0.050 mol % or less, more preferably 0.045 mol % or less, and even more preferably 0.040 mol % or less.

[0091] The recycled liquid crystal polyester long fiber used as the raw spinning yarn may have a total CEG content of the liquid crystal polyester of, for example, 20 meq / kg or less, preferably 15 meq / kg or less, and more preferably 10 meq / kg or less. The lower limit of the total CEG content is not particularly limited, but may be 1 meq / kg or more. Although the relationship between the carboxyl groups present at the molecular terminals of the liquid crystal polyester and the reaction in solid-state polymerization is not clear, by heat-treating a raw spinning yarn having a total CEG content within such range, a heat-treated yarn having excellent mechanical properties can be obtained by heat-treating at a low temperature for a short time.

[0092] The recycled liquid crystalline polyester filament as a raw spinning yarn may have a total amount of liquid crystalline polyester ends on one side of the fiber, for example, of 50 to 100 meq / kg, preferably 55 to 99 meq / kg, and more preferably 60 to 85 meq / kg. By subjecting a raw spinning yarn having a total amount of ends on one side within such a range to a heat treatment, solid-state polymerization proceeds, and the total amount of ends on one side can be reduced (i.e., the molecular weight can be increased).

[0093] The method for producing recycled liquid crystalline polyester filaments may further include a step of heat-treating the obtained raw spun yarn. By subjecting the raw spun yarn to heat treatment, solid-state polymerization of the liquid crystalline polyester proceeds, and mechanical properties (e.g., tensile strength) can be improved. The heat treatment method in the heat treatment step is not particularly limited, and may be, for example, a batch-type heat treatment or a continuous heat treatment by conveying.

[0094] For example, in a batchwise heat treatment, the material may be wound around a bobbin in a packaged state, or in a skein or tow state, and the heat treatment is preferably performed in a packaged state in terms of simplifying the equipment and improving productivity. The bobbin must be able to withstand the temperature of solid-state polymerization, and is preferably made of a metal such as aluminum, brass, iron, or stainless steel.

[0095] In the case of continuous heat treatment by conveyance, the conveyance method may be either contact conveyance (for example, a conveyor system, a support roll system, or a heat treatment system using heated rollers) or non-contact conveyance (a roll-to-roll system). The treatment path does not have to be straight, and heat treatment may be performed by appropriately changing the length, angle, curvature, etc. of the treatment path by arranging return rollers or guides within the device.

[0096] The heat treatment step can be carried out by a known method, such as atmospheric heating or contact heating. The atmosphere is preferably air, an inert gas (e.g., nitrogen, argon), or a combination thereof. The heat treatment may also be carried out under reduced pressure.

[0097] In the method for producing recycled liquid crystalline polyester filaments, for example, an oil may be applied before the heat treatment step in order to improve the bundling ability of the fibers 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 recycled liquid crystalline polyester filaments.

[0098] The recycled liquid crystal polyester long fiber of one embodiment 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 1,000, preferably 3 to 600, more preferably 4 to 300, and even more preferably 5 to 100.

[0099] The single fiber fineness of the recycled liquid crystal polyester long fiber of one embodiment can be appropriately selected depending on the application, etc. For example, the single fiber fineness may be 50 dtex or less, preferably 15 dtex or less, more preferably 10 dtex or less, but in order to obtain a fiber structure with flexibility, a small fineness is preferred, for example, 7 dtex or less. The lower limit of the single fiber fineness is not particularly limited, but may be, for example, 0.01 dtex. The single fiber fineness is a value measured by the method described in the Examples below.

[0100] The total fineness of the recycled liquid crystal polyester long fiber of one embodiment can be appropriately selected depending on the application, etc. For example, the total fineness may be 2000 dtex or less, preferably 1000 dtex or less, more preferably 600 dtex or less, and even more preferably 300 dtex or less. In order to obtain a flexible fiber structure, it is preferable to make the fiber diameter of the conductive yarn small, and a fine fineness is preferable. In addition, the lower limit of the total fineness is not particularly limited, but it may be, for example, about 1 dtex.

[0101] The tensile strength of the recycled liquid crystal polyester long fiber of one embodiment may be 6 cN / dtex or more in the case of an untreated yarn, preferably 7 cN / dtex or more, more preferably 8 cN / dtex or more, and in the case of a heat-treated yarn, may be 16 cN / dtex or more, preferably 17 cN / dtex or more, more preferably 18 cN / dtex or more.

[0102] Inorganic particles may be uniformly distributed on the cut surface of one embodiment of the recycled liquid crystal polyester fiber. For example, liquid crystal polyester fibers generally contain inorganic particles as a component of an oil agent applied to the surface. When inorganic particles derived from a recovered raw material molded body are mixed into chip-like materials, the inorganic particles are uniformly distributed not only on the surface but also inside the recycled liquid crystal polyester fiber formed from the chip-like materials. Therefore, the distribution of inorganic particles on the cut surface can be used as traceability for identifying the recycled liquid crystal polyester fiber. Examples of inorganic particles include minerals, metal hydroxides such as magnesium hydroxide, metal oxides such as silica and alumina, carbonate compounds such as calcium carbonate and barium carbonate, sulfate compounds such as calcium sulfate and barium sulfate, and carbon black. Examples of minerals include silicate minerals, and particularly phyllosilicates with a layered structure. Examples of phyllosilicates include kaolinite, halloyite, serpentine, garnierite, smectite, pyrophyllite, talc, and mica. Among these, talc and mica are preferred due to their ease of availability.

[0103] (Recycled Liquid Crystal Polyester Fiber Structure) The recycled liquid crystal polyester molding may be a recycled liquid crystal polyester fiber structure containing recycled liquid crystal polyester fiber. Examples of the recycled liquid crystal polyester fiber structure include, in addition to the above-mentioned recycled liquid crystal polyester long fiber, linear materials such as staple fiber, short-cut fiber, filament yarn, spun yarn, string-like material, twisted material, and rope; and sheet-like materials such as woven and knitted fabrics and nonwoven fabrics. Such fiber structures can be produced using the recycled polyester long fiber of the present invention by a known method.

[0104] The recycled liquid crystal polyester fiber structure of one embodiment may be a combination of recycled liquid crystal polyester fiber and other fiber, for example, a composite fiber using recycled liquid crystal polyester fiber and other fiber (for example, a mixed yarn in which recycled liquid crystal polyester fiber is mixed with other fiber), or a composite cloth using recycled liquid crystal polyester fiber and other fiber (for example, a mixed cloth in which recycled liquid crystal polyester fiber is mixed with other fiber, or a laminate of a cloth made of recycled liquid crystal polyester fiber and a cloth made of other fiber).

[0105] For example, the recycled liquid crystal polyester fiber may be used as a reinforcing fiber or a matrix component in a composite material containing a reinforcing fiber and a matrix component. When used as a matrix component, the recycled liquid crystal polyester fiber is used to form a composite fabric with the reinforcing fiber, and then the recycled liquid crystal polyester fiber is melted by heat treatment to produce a fiber structure. When the fiber structure is used to produce a composite material, the fiber structure may be a composite fiber or a composite fabric containing fused fibers that form the matrix of the composite material as other fibers.

[0106] The recycled liquid crystalline polyester fiber structure of the present invention can be used for various applications such as electrical and electronic parts materials, general industrial materials, various reinforcing materials, and protective clothing.

[0107] 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.

[0108] (Bulk density) Referring to JIS Z 2504, the chip-like material was first placed in a 500 mL beaker, then the beaker was tilted and the chip-like material was poured into a 500 mL measuring container with an inner diameter of 85 mm by free fall. When the chip-like material filled the measuring container and began to overflow, the inflow of the measurement sample was immediately stopped. Then, the chip-like material was scraped flat along the top edge of the measuring container in one operation, taking care not to compress the chip-like material or shake or vibrate the measuring container. Then, the weight of the liquid crystal polyester chip-like material in the measuring container was measured with an electronic balance, and the bulk density (g / mL) per 500 mL was calculated.

[0109] (Average value of maximum length, average value of minimum length) The chip-like product was placed on a flat surface, and the length of the longest part of the chip-like product was measured using an electronic caliper, and this was taken as the maximum length (mm). Similarly, the length of the shortest part of the chip-like product was measured, and this was taken as the minimum length (mm). The maximum length and minimum length of each of 10 chip-like products were measured, and the respective average values ​​were calculated.

[0110] (Melting Point of Resin) Measurement was performed using a differential scanning calorimeter (DSC; "DSC60A Plus" manufactured by Shimadzu Corporation) in accordance with the JIS K 7121:2012 test method, and the observed main absorption peak temperature was taken as the melting point. Specifically, 4 to 6 mg of a sample was placed in an aluminum pan and sealed in the DSC apparatus. Nitrogen was then flowed as a carrier gas at a flow rate of 200 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 10°C / min.

[0111] (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).

[0112] (Tensile strength) With reference to JIS L 1013:2010 8.5.1, a tensile test was carried out 10 times for one yarn sample using an autograph "AGS-100B" manufactured by Shimadzu Corporation under conditions of a test length of 20 cm and a tensile speed of 10 cm / min, and the average tensile strength (N) was divided by the total fineness (dtex) measured by the above-mentioned method to calculate the tensile strength (cN / dtex).

[0113] (Ketone Bond Amount) The ketone bond amount was calculated by the pyrolysis gas chromatography method described in Polymer Degradation and Stability, 76, 85-94 (2002). Specifically, a liquid crystal polyester chip material or a liquid crystal polyester fiber sample was heated in the presence of tetramethylammonium hydroxide (TMAH) using a pyrolysis apparatus (manufactured by Frontier Labs, Inc., "PY2020iD") to generate gas by pyrolysis / methylation. This gas was analyzed using gas chromatography (manufactured by Agilent Technologies, Inc., "GC-6890N"), and the ketone bond amount (mol%) was calculated from the peak area derived from the ketone bond and the peak area derived from the ester bond.

[0114] (Total CEG Amount) A liquid crystal polyester chip or liquid crystal polyester fiber sample was freeze-pulverized to a d90 of 100 μm or less, and a large excess of n-propylamine was added to the pulverized sample. The sample was then heated and stirred at 40°C for 90 minutes to decompose the sample. In this case, the ester bonds present inside the polymer chain were decomposed into carboxylic acid n-propylamide and hydroxy groups, and the carboxy groups (CEG) and hydroxy groups present at the ends of the polymer chain remained as carboxy groups and hydroxy groups. Therefore, the decomposition products were separated by HPLC, and the peak areas of the decomposition products containing carboxy groups were compared with calibration curves prepared by HPLC analysis of each sample to quantify the amount of carboxy terminals (meq / kg) derived from each monomer. The measurement device and measurement conditions for the HPLC method are as follows:

[0115] For example, the amount of CEG derived from monocarboxylic acids such as 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid can be determined by quantifying 4-hydroxybenzoic acid or 6-hydroxy-2-naphthoic acid as is, while the amount of CEG derived from dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid can be determined by quantifying substances in which one carboxy group is amidated, such as terephthalic acid mono-n-propylamide, isophthalic acid mono-n-propylamide, and 2,6-naphthalenedicarboxylic acid mono-n-propylamide. The sum of all the amounts of carboxy termini contained in each sample was taken as the total amount of carboxy termini (total CEG amount) for that sample.

[0116] (Total Amount of Single Terminals) In the same manner as in the measurement of the total CEG amount described above, a liquid crystal polyester chip or liquid crystal polyester fiber sample was decomposed using n-propylamine, and the total amount (meq / kg) of carboxyl terminals derived from hydroxycarboxylic acids and the total amount of terminals resulting from the decarboxylation of the terminal carboxy groups derived from hydroxycarboxylic acids was quantified. For example, the amount of terminals derived from 4-hydroxybenzoic acid was determined by quantifying 4-hydroxybenzoic acid and phenol, and the amount of terminals derived from 6-hydroxy-2-naphthoic acid was determined by quantifying 6-hydroxy-2-naphthoic acid and 2-naphthol. In order to take into account the amount of terminals derived from diols and dicarboxylic acids other than hydroxycarboxylic acids, the total amount of terminals derived from hydroxycarboxylic acids was divided by the molar ratio of the hydroxycarboxylic acid-derived structural units in the liquid crystal polyester of the sample, and the value was used as the total amount of single terminals for the sample.

[0117] Example 1 Virgin chips of a liquid crystal polyester (melting point: 278°C) composed of 4-hydroxybenzoic acid-derived structural units and 6-hydroxy-2-naphthoic acid-derived structural units in a 73 / 27 (mol%) ratio were dried with hot air at 120°C for at least 4 hours. The chips were then placed in a Φ15mm twin-screw extruder (manufactured by Technovel Corporation) and melt-kneaded, and the molten mixture was supplied to a spinning head. The spinning head was equipped with a nozzle having a hole diameter of 0.10 mmφ and 50 holes, and the spinning head temperature was set to 320°C. The molten mixture was discharged at a discharge rate of 28 g / min and wound onto a bobbin at a take-up speed of 1000 m / min, yielding 10 5 kg liquid crystal polyester fiber spinning yarns (untreated yarns).

[0118] The obtained spinning yarn was subjected to a heat treatment at 270°C for 16 hours in a nitrogen atmosphere, and 4 kg of spinning yarn was unwound from each bobbin to obtain 10 bobbins each having 1 kg of residual yarn. The residual yarn was cut on the bobbin using a cutter knife, and liquid crystal polyester fibers having a length of about 10 cm were collected and used as the collected raw material molded body.

[0119] Next, a polyimide film was placed on the metal plate as a heat-resistant release material, and a metal frame (12 cm long, 12 cm wide, 1.5 mm thick) was placed on the polyimide film. Liquid crystal polyester fibers were aligned as a raw material molded body and placed in a metal frame, a polyimide film was placed on top of it, and the recovered liquid crystal polyester fibers were heat-pressed 10 times at 300 ° C. and 2.2 MPa for 10 seconds using metal hot plates arranged above and below. This was then degassed and heat-pressed for 3 minutes. Following the heat press, the liquid crystal polyester was transferred together with the metal frame to a cooling press and cooled to obtain a sheet-like material made from the recovered liquid crystal polyester fibers. The obtained sheet was cut using a cutter to obtain square prism-shaped chips with a thickness of about 1.5 mm, long sides of about 10 mm, and short sides of about 3 mm. The average maximum length of the chips was 10.4 mm, and the bulk density was 0.80 g / mL. A photograph of the obtained chips is shown in Figure 3. As shown in FIG. 3, the chip-like material has a shape at the outer edge that originates from the fibers.

[0120] The obtained chip-like material was dried with hot air at 120°C for 4 hours or more, and then charged into a Φ15 mm twin-screw extruder (manufactured by Technovel Co., Ltd.). The extruder's screws did not spin freely, and the charged chip-like material was melt-kneaded at 300°C, and the molten kneaded material was supplied to the spinning head. The spinning head was equipped with a nozzle with a hole diameter of 0.10 mmφ and 50 holes, and the spinning head temperature was set to 330°C. The molten kneaded material 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 spun raw yarn of recycled liquid crystal polyester filament.

[0121] Furthermore, 500 m of the spinning yarn obtained here was wound at a winding density of 0.6 g / cm ３ The recycled liquid crystalline polyester filament was rewound onto an aluminum bobbin so that the fiber was 100% polyester, and then heat-treated in a closed oven at 300°C for 16 hours under a nitrogen atmosphere to obtain a heat-treated yarn of recycled liquid crystalline polyester filament. The physical properties of the recycled liquid crystalline polyester fiber and the chip-like material used are shown in Table 5.

[0122] [Reference Example] In the same manner as in Example 1, virgin chips (average maximum length of chip-like material: 0.63 mm, bulk density: 0.67 g / mL) of a liquid crystal polyester (melting point: 278°C) composed of 73 / 27 (mol%) of constitutional units derived from 4-hydroxybenzoic acid and constitutional units derived from 6-hydroxy-2-naphthoic acid were melt-spun, and the resulting spun raw yarn was wound at a winding density of 0.6 g / cm. ３ The fiber was rewound onto an aluminum bobbin so that the fiber was 100% polyester, and the fiber was heat-treated in a closed oven at 270°C for 16 hours under a nitrogen atmosphere to obtain a heat-treated liquid crystalline polyester filament. The physical properties of the obtained liquid crystalline polyester fiber and the chip-like material used are shown in Table 5.

[0123] [Examples 2 and 3] The chip-like material obtained in Example 1 and the virgin chips obtained in the Reference Example were mixed in the ratios shown in Table 5, dried with hot air at 120°C for 4 hours or more, and then fed into a Φ15 mm twin-screw extruder, and the same procedure as in Example 1 was repeated to obtain a spun raw yarn and a heat-treated yarn of recycled liquid crystalline polyester long fiber. The physical properties of the obtained recycled liquid crystalline polyester fiber and the chip-like material used are shown in Table 5.

[0124] [Example 4] Ten bobbins, each containing 1 kg of the residual spinning yarn obtained in Example 1, were placed on a winding creel and unwound. The ten bobbins were then bundled together and passed through a bath containing a polyurethane-based sizing agent (Superflex 126, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). The resulting fiber bundle was then dried in a hot air oven set at 190°C to obtain a liquid crystal polyester fiber bundle containing 1% by weight of the sizing agent as a solid content. The resulting liquid crystal polyester fiber bundle was cut with a cutter to obtain chips having a thickness of approximately 2 mm, a width of approximately 5 mm, and a length of approximately 5 mm (average maximum length: 7.0 mm). A spinning yarn and a heat-treated yarn of recycled liquid crystal polyester filament were obtained in the same manner as in Example 1, except that the resulting chips were used. The physical properties of the resulting recycled liquid crystal polyester fiber and the chips used are shown in Table 5.

[0125] [Example 5] In Example 1, when the liquid crystal polyester fiber recovered by cutting the residual yarn with a cutter knife was sandwiched between metal hot plates and hot-pressed, the fiber was degassed by hot-pressing 10 times at 300°C and 2.2 MPa for 10 seconds, but the hot-pressing time was changed to 30 seconds. In the same manner as in Example 1, a spun raw yarn and a heat-treated yarn of recycled liquid crystal polyester long fiber were obtained. The physical properties of the obtained recycled liquid crystal polyester fiber and the chip-like material used are shown in Table 5.

[0126] [Example 6] The liquid crystal polyester fiber spinning raw yarn (untreated yarn) of 5 kg wound obtained in Example 1 was heat-treated at 220 ° C for 4 hours in a nitrogen atmosphere, and cut on a bobbin using a cutter knife to recover liquid crystal polyester fibers of about 10 cm in length, which was used as a recovered raw material molded body. Then, the chip-like material was produced in the same manner as in Example 1.

[0127] The resulting chip-like material was dried with hot air at 120°C for more than 4 hours and then fed into a Φ15mm twin-screw extruder (manufactured by Technovel Co., Ltd.). The extruder's screw did not spin freely, and the fed chip-like material was melt-kneaded at 300°C, allowing the molten kneaded material to be supplied to the spinning head. The spinning head was equipped with a nozzle with a hole diameter of 0.10mmφ and 50 holes. The spinning head temperature was set to 330°C, and the molten kneaded material 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 spun raw yarn of recycled liquid crystalline polyester long fiber. Thereafter, heat treatment was carried out in the same manner as in Example 1 to obtain a heat-treated yarn of recycled liquid crystalline polyester long fiber. The physical properties of the resulting recycled liquid crystalline polyester fiber and the chip-like material used are shown in Table 5.

[0128] Comparative Example 1 In Example 1, the length of the fiber when the residual yarn was cut on the bobbin with a cutter knife was changed to 20 mm, and an attempt was made to melt spin the shortened fiber to a length of 20 mm as chips in the same manner as in Example 1, but the chips did not get caught in the extruder, and it was not possible to obtain a raw spun yarn. The physical properties of the chips used in spinning are shown in Table 5.

[0129] [Comparative Example 2] Ten bobbins each containing 1 kg of the residual spun yarn obtained in Example 1 were placed on a winding creel and unwound. The ten bobbins were bundled together and passed through a bath containing a polyurethane-based sizing agent (Superflex 126, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). The resulting fiber bundle was then dried in a hot air oven set at 190°C to obtain a liquid crystal polyester fiber bundle containing 20% ​​by weight of sizing agent as a solid content. The resulting liquid crystal polyester fiber bundle was cut with a cutter to obtain chips having a thickness of approximately 2 mm, a width of approximately 5 mm, and a length of approximately 5 mm (average maximum length: 7.0 mm). The resulting chips were melt-spun in the same manner as in Example 1; however, the bulk density was too high due to the presence of the sizing agent, preventing good melt-kneading. Consequently, frequent single-fiber breakage occurred, making it impossible to obtain a spun yarn. The physical properties of the chips used for spinning are shown in Table 5.

[0130] Comparative Example 3 In Example 1, the remaining yarn cut on the bobbin using a cutter knife was pulverized in a pulverizer (mesh 8 mm), and the pulverized material was used as chips for melt spinning in the same manner as in Example 1. However, because the bulk density and average maximum length were small, the chips did not fit into the extruder, and it was not possible to obtain raw yarn for spinning. The physical properties of the chips used for spinning are shown in Table 5.

[0131] [Comparative Example 4] A sheet-like material made from recovered liquid crystal polyester fibers obtained in the same manner as in Example 1 was cut using a cutter to obtain a square chip-like material with a thickness of about 1.5 mm, a long side of about 30 mm, and a short side of about 30 mm (average maximum length: 42.3 mm). The obtained chip-like material was melt-spun in the same manner as in Example 1, but it did not get caught in the extruder, and it was not possible to obtain a spun raw yarn. The physical properties of the chip-like material used for spinning are shown in Table 5.

[0132]

[0133] As shown in Table 5, it was not possible to obtain spinning yarn from any of the chip materials of Comparative Examples 1 to 4. On the other hand, it was possible to melt-mold the recovered liquid crystal polyester from the chip materials of Examples 1 to 6. In particular, the recycled liquid crystal polyester filaments obtained from the chip materials of Examples 1 to 4 and 6 have fiber properties equivalent to those of the liquid crystal polyester filaments obtained from 100% by mass of virgin liquid crystal polyester in the Reference Example.

[0134] The recycled liquid crystalline polyester molded product of the present invention can be used for various applications such as general industrial materials, civil engineering and construction materials, various reinforcing materials, electrical and electronic component materials, etc. In particular, when the molded product is a fiber structure, it can be used as various fiber products such as tension members (electric wires, optical fibers, etc.), heater wire core threads, cords for various electrical products such as earphone cords, ropes, sling belts, ropes, lifelines, fishing lines, fishing nets, longlines, land nets (safety nets, golf driving range nets, etc.), catheters, reinforcing materials for plastics, concrete, and rubber, base fabrics for printed circuit boards, sail cloth, protective clothing, and protective gloves.

[0135] 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 method for manufacturing liquid crystal polyester chip-like materials, The process involves preparing the recovered liquid crystal polyester molded body as a raw material molded body, An integration step to form an integrated body by integrating the raw material molded body, or a pre-molded body obtained by cutting or crushing the raw material molded body as necessary, A cutting step to cut the aforementioned integrated body and produce chip-like objects having a bulk density of 0.15 to 1.20 g / mL and an average maximum length of 3 to 30 mm for the chip-like objects, A manufacturing method comprising at least the following.

2. A method for manufacturing a liquid crystal polyester chip-like material according to claim 1, wherein the integration step is performed by thermoforming.

3. A method for manufacturing a liquid crystal polyester chip-like material according to claim 1 or 2, wherein a degassing treatment is performed in the integration step.

4. The process involves preparing liquid crystal polyester chips as raw materials by a manufacturing method described in at least one of claims 1 or 2, A method for manufacturing a recycled liquid crystal polyester molded article, comprising the step of melting and extruding the liquid crystal polyester chip-like material.