Method for producing polyester-based resin fibers

Abstract

This invention provides a method for manufacturing polyester resin fibers using a resin composition obtained with a modifier. The manufacturing method includes: step 1, melt-blending a polyester resin with a modifier to obtain a polyester resin composition; and step 2, winding the polyester resin composition obtained in step 1 at a winding speed of 400 m / min or more.

Description

Technical Field

[0001] This invention relates to a method for manufacturing polyester resin fibers. Background Technology

[0002] Polyester resins deteriorate and their physical properties decrease during each processing step (such as melt mixing), for example, due to factors like heat causing the resin's molecular chains to shorten. Resin with degraded physical properties has limited processing applications or may be unprocessable compared to resin before processing.

[0003] As a technique for increasing the melt viscosity of polyester resins that have decreased due to processing, it is known to melt-blend polyester resins with chain extension agents (sometimes also called "viscosity improvers" or "Melt viscosity improver: MVI") (e.g., Patent Documents 1 to 3).

[0004] Patent Document 1: International Publication No. 2004 / 039887

[0005] Patent Document 2: International Publication No. 2004 / 041934

[0006] Patent Document 3: International Publication No. 2007 / 040041 Summary of the Invention

[0007] However, in the manufacture of polyester resin fibers using polyester resin compositions obtained with conventional chain extenders (modifiers), it is sometimes impossible to wind the resin composition at high speeds (e.g., speeds of 400 m / min or higher). In other words, the existing technology is insufficient from a productivity point of view, and there is room for further improvement.

[0008] One embodiment of the present invention was made in view of the above-mentioned problems, and its object is to provide a novel manufacturing method for polyester resin fibers that can be manufactured with high productivity even when using modifiers.

[0009] In order to solve the above-mentioned problems, the inventors conducted in-depth research and as a result completed this invention.

[0010] That is, one embodiment of the present invention relates to a method for manufacturing polyester resin fibers, comprising:

[0011] Step 1 involves melt-blending a polyester resin with a modifier to obtain a polyester resin composition, and

[0012] Step 2 involves winding the polyester resin composition obtained in Step 1 at a winding speed of 400 m / min or higher.

[0013] According to one embodiment of the present invention, the following effect is achieved: a method for manufacturing polyester resin fibers that can produce polyester resin fibers with high productivity even when using modifiers is provided. Detailed Implementation

[0014] The following describes one embodiment of the present invention, but the invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included within the technical scope of the present invention. Moreover, new technical features can be formed by combining the technical means disclosed in each embodiment. It should be noted that all academic and patent documents described in this specification are cited as references in this specification.

[0015] In this specification, unless otherwise stated, the structural unit contained in the polymer, copolymer, or resin is referred to as "structural unit from monomer X," "structural unit from compound X," or "structural unit from acid X." In this specification, "monomer X" may sometimes be abbreviated as "X."

[0016] [1. Implementation Method 1]

[0017] [1-1. Manufacturing method of polyester resin fiber]

[0018] One embodiment of the present invention (Embodiment 1) relates to a method for manufacturing polyester resin fibers, comprising:

[0019] Step 1 involves melt-blending a polyester resin with a modifier to obtain a polyester resin composition, and

[0020] Step 2 involves winding the polyester resin composition obtained in Step 1 at a winding speed of 400 m / min or higher.

[0021] In this specification, "polyester resin composition" is sometimes referred to as "resin composition", "method of manufacturing polyester resin fiber" is sometimes referred to as "manufacturing method", and "method of manufacturing polyester resin fiber according to Embodiment 1" is sometimes referred to as "this manufacturing method 1".

[0022] Because of the above-described structure, this manufacturing method 1 has the advantage of being able to manufacture polyester resin fibers with high productivity even when using a modifier. Furthermore, in a preferred embodiment of this manufacturing method 1, it has the advantage of providing a polyester resin fiber that possesses the same physical properties (e.g., heat shrinkage, maximum elongation, elongation at break, and Young's modulus) as polyester resin fibers obtained using virgin polyester resin.

[0023] The following section will first describe the raw materials (polyester resin and modifiers, etc.), and then describe the specific processes.

[0024] [Polyester-based resins]

[0025] The polyester resin used in this manufacturing method 1 is not particularly limited, and can be, for example, a polyester resin commonly used as a raw material for polyester resin fibers.

[0026] Polyester resins can also be aromatic polyesters having a structure formed by linking aromatic dicarboxylic acids or their ester derivatives with diols such as aliphatic or alicyclic diols through an esterification reaction. These polyester resins can also be obtained by polycondensation of aromatic dicarboxylic acids or their ester derivatives with diols such as aliphatic or alicyclic diols using known methods.

[0027] As an aromatic dicarboxylic acid, there are no particular limitations; examples include phthalic acid, terephthalic acid, isophthalic acid, and phthalic acid. As an aromatic dicarboxylic acid, only one type can be used, or two or more types can be used in combination.

[0028] As an aliphatic diol, there are no particular limitations; examples include ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, decanethylenediol, bisphenol A ethylene oxide addition diol, polyethylene oxide diol, and polyethylene oxide diol. As an alicyclic diol, there are no particular limitations; examples include 1,4-cyclohexanediethanol, 4,4-dicyclohexylhydroxymethane, and 4,4'-dicyclohexylhydroxypropane. As a diol component, only one type can be used, or two or more can be used in combination.

[0029] The aforementioned polyester resin can also be a polymer formed by copolymerizing aromatic dicarboxylic acids or their ester derivatives, aliphatic diols, and other dicarboxylic acids or their ester derivatives, or other diols as the main components. There are no particular limitations on the other dicarboxylic acids; examples include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 4,4'-dicyclohexyldicarboxylic acid.

[0030] The aforementioned polyester resins may also contain structural components derived from monomers with three or more functions, such as glycerol, trimethylolpropane, pentaerythritol, trimellitic acid, and pyromellitic acid.

[0031] Specific examples of polyester resins are not particularly limited, but include polyethylene terephthalate (PET), polyethylene terephthalate, polyethylene butylene terephthalate, and glycol-modified polyethylene terephthalate. Glycol-modified polyethylene terephthalate refers to a copolymer of terephthalic acid, ethylene glycol, and glycols other than ethylene glycol.

[0032] From the viewpoint of molding processability and mechanical properties, the polyester resin (i) preferably comprises one or more selected from polypropylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, polybutylene naphthalate, polycyclohexanedimethyl terephthalate and polyester / polyether, or may be composed of only one or more selected from this group, (ii) more preferably comprises one or more selected from polyethylene terephthalate and polybutylene terephthalate, or may be composed of only one or more selected from this group.

[0033] Polyester-based resins can also be used as polymer alloys obtained from polymer mixtures containing various polyester-based resins. Examples of polymer alloys include polycarbonate / polyethylene terephthalate, polyethylene terephthalate / diol-modified polyethylene terephthalate, and polyethylene terephthalate / copolymer polyethylene terephthalate.

[0034] The polyester resin may include recycled polyester resin or may consist only of recycled polyester resin. When the polyester resin includes recycled polyester resin, this manufacturing method 1 may also be called "manufacturing method of recycled polyester resin fiber", and the polyester resin fiber obtained by this manufacturing method 1 may also be called "recycled polyester resin fiber".

[0035] In this specification, "recycled polyester resin" refers to polyester resins and / or polyester resin compositions obtained by regenerating the following (Ai) and / or (Aii):

[0036] (Ai) Polyester resins, polyester resin compositions and / or polyester resin molded articles that have been commercialized as polyester resins, polyester resin compositions and / or polyester resin molded articles, and which have been used and / or discarded.

[0037] (Aii) Polyester resins, polyester resin compositions and / or polyester resin molded articles that are expelled or discarded during the manufacture of polyester resins, polyester resin compositions and / or polyester resin molded articles.

[0038] As a method of recycling, well-known recycling methods can be used, without particular limitation, such as material recycling.

[0039] Here, the required melt viscosity (IV value) of polyester resins used as raw materials for molded articles such as fibers may vary depending on the type of molded article. This is because (i) the required melt viscosity varies depending on the type of molded article and the molding method, and / or, (ii) the required strength of the molded article (product) varies depending on its specifications. For example, polyester resins used as raw materials for plastic bottles require a higher melt viscosity. Furthermore, polyester resins used as raw materials for sheets and films, while requiring a lower melt viscosity than those used for plastic bottles, still require a relatively high melt viscosity. On the other hand, polyester resins used as raw materials for fibers, while not requiring a high melt viscosity, do require a certain melt viscosity (e.g., 0.50 or higher and 0.75 or lower).

[0040] Typically, during the recycling process, moisture is added to the resin (resin composition) and / or the resin (resin composition) is heated (melt mixing). Due to the addition of moisture and / or heating, the molecular weight of the recycled polyester resin tends to be lower than that of the polyester resins, polyester resins constituting the polyester resin composition and / or molded articles described above (Ai) and / or (Aii), and the melt viscosity tends to decrease along with the decrease in molecular weight. Furthermore, the molecular weight of the polyester resin constituting the polyester resin composition and / or molded article tends to decrease due to the passage of time and heating, and the melt viscosity tends to decrease along with the decrease in molecular weight. Therefore, in the past, recycled polyester resins were mostly used for applications requiring lower melt viscosity than the original polyester resins. For example, recycled polyester resins obtained from plastic bottles are mostly used for sheet, film, or fiber applications, and recycled polyester resins obtained from sheets and / or films are mostly used for fiber applications. In other words, in the past, a large quantity of recycled polyester resins have been circulating for fiber applications where lower melt viscosity is permissible.

[0041] However, in recent years, the demand for horizontal recycling—from plastic bottle to plastic bottle, or from sheet and / or film to sheet and / or film—has increased, leading to a decrease in the circulation of recycled polyester resins for fiber applications. Consequently, in the field of resin fibers, the demand for horizontal recycling from polyester resin fibers to polyester resin fibers is also increasing. As mentioned above, there is a trend towards recycled polyester resins obtained from the recycling of polyester resin fibers having a melt viscosity (e.g., 0.45 or higher and 0.70 or lower) that is lower than the melt viscosity (e.g., 0.50 or higher and 0.75 or lower) of the polyester resin used as a raw material for polyester resin fibers. Therefore, it is sometimes difficult to manufacture polyester resin fibers directly using the recycled polyester resin obtained from the recycling of polyester resin fibers as a raw material.

[0042] When using recycled polyester resins, it is known that techniques exist for adding viscosity modifiers to the recycled polyester resins to improve the melt viscosity of resin compositions containing recycled polyester resins to a certain extent (e.g., Patent Documents 1 to 3). However, the inventors attempted to manufacture polyester resin fibers using resin compositions containing conventional viscosity modifiers, and independently discovered that sometimes it was impossible to wind the melt-blended resin composition at high speeds (e.g., speeds of 400 m / min or higher). In other words, there is a tendency that resin compositions obtained by melt-blending recycled polyester resins with conventional viscosity modifiers cannot be used to manufacture polyester resin fibers with high productivity.

[0043] However, the modifier used in this manufacturing method 1 (in other words, the modifier according to one embodiment of the present invention) has the following advantages: by melt-blending with recycled polyester resin, the melt viscosity of the recycled polyester resin can be increased, providing a resin composition with high melt viscosity, and the resulting resin composition can be wound at high speeds (e.g., speeds of 400 m / min or higher). Furthermore, surprisingly, the resin composition obtained by mixing the modifier according to one embodiment of the present invention with recycled polyester resin also has the advantage of being reusable, particularly as long fibers (filament fibers). Therefore, this manufacturing method 1 can provide high-productivity polyester resin fibers (particularly long fibers) even when using recycled polyester resin, especially recycled polyester resin obtained from the regeneration of polyester resin fibers. That is, this manufacturing method 1 has the advantage of being able to regenerate horizontally. Therefore, the polyester resin used as a raw material in this manufacturing method 1 can be derived from waste polyester resin fibers. That is, the polyester resin composition in (Ai) and (Aii) above can be a polyester resin composition for polyester resin fibers, and the polyester resin molded body can be a polyester resin fiber.

[0044] When the polyester resin includes recycled polyester resin, this manufacturing method 1 can significantly reduce the amount of plastic waste generated and the amount of plastic used in manufacturing. Therefore, this manufacturing method 1 can contribute to achieving Sustainable Development Goals (SDGs), such as Goal 12, "Ensuring sustainable consumption and production patterns."

[0045] In this specification, polyester resins that have never been commercialized are sometimes referred to as "virgin polyester resins". "Recycled polyester resins" in this specification also includes mixtures formed by mixing recycled polyester resins with "virgin polyester resins".

[0046] As described above, in step 1 of this manufacturing method 1, a resin composition having a higher melt viscosity than the polyester resin used as a raw material can be obtained. Therefore, as a result, this manufacturing method 1 can provide a polyester resin fiber that possesses the same physical properties (e.g., heat shrinkage, maximum elongation, elongation at break, and Young's modulus) as polyester resin fibers obtained using virgin polyester resin. In other words, this manufacturing method 1 is suitable for horizontal regeneration from polyester resin fibers to polyester resin fibers. In this manufacturing method 1, as in obtaining polyester resin (regenerated polyester resin) by regenerating waste polyester resin fibers, it is preferable to use a polyester resin with a melt viscosity lower than the melt viscosity required by the polyester resin used as a raw material for polyester resin fibers. The melt viscosity (IV value) of the polyester resin used in this manufacturing method 1 varies depending on the fiber production conditions and applications, and is generally preferably 0.45 or higher and 0.75 or lower, more preferably 0.50 or higher and 0.75 or lower, even more preferably 0.55 or higher and 0.75 or lower, further preferably 0.60 or higher and 0.75 or lower, and particularly preferably 0.60 or higher and 0.70 or lower.

[0047] The melt viscosity of the resin or resin composition is negatively correlated with the melt flow rate (MFR) of the resin or resin composition. The MFR of the polyester resin used in this manufacturing method 1, measured at a temperature of 270°C and a load of 2.16 kgf, is preferably 10 g / 10 min or more and 120 g / 10 min or less, more preferably 20 g / 10 min or more and 100 g / 10 min or less, more preferably 35 g / 10 min or more and 90 g / 10 min or less, further preferably 40 g / 10 min or more and 80 g / 10 min or less, and particularly preferably 45 g / 10 min or more and 70 g / 10 min or less. In this specification, the MFR of the resin or resin composition is set as the value obtained by the method described in the following examples.

[0048] [Modifier]

[0049] The modifier used in this manufacturing method 1 is not particularly limited as long as it is a reagent capable of altering the physical properties of the polyester resin used as a raw material (e.g., increasing its melt viscosity). In other words, the modifier used in this manufacturing method 1 is not particularly limited as long as it is a reagent capable of obtaining a polyester resin composition in step 1 that has physical properties different from those of the raw polyester resin (e.g., a higher melt viscosity than the raw polyester resin). In this specification, "melt viscosity of the polyester resin" and "melt viscosity of the polyester resin composition" refer to values ​​obtained by the methods described in the following examples.

[0050] (Polymer (A))

[0051] The modifier is preferably a polymer (A) comprising units containing reactive functional groups and units not containing reactive functional groups.

[0052] (Units containing reactive functional groups)

[0053] In this specification, "reactive functional group" means a functional group that can react with the terminal functional groups of polyester resins. In this specification, "unit containing reactive functional group" means a structural unit having a reactive functional group, and is a structural unit derived from a monomer having a reactive functional group (hereinafter, sometimes referred to as "monomer containing reactive functional group").

[0054] In step 1 of this manufacturing method 1, a polyester resin and a modifier are melt-blended. During this melt-blending process, it is presumed that the reactive functional groups (e.g., epoxy groups) of the polymer (A) contained in the modifier react with the terminal functional groups (e.g., hydroxyl or carboxyl groups) of the polyester resin, and that this reaction elongates the molecular chains of the polyester resin. That is, the polymer (A) contained in the modifier may have the function of elongating the molecular chains of the polyester resin; in other words, the polymer (A) contained in the modifier may act as a chain extender (or viscosity improver) for the polyester resin. Furthermore, it is presumed that since the modifier contains the aforementioned polymer (A), in step 1, more specifically during the melt-blending of the modifier and the polyester resin, the modifier and the polyester resin are mixed more uniformly, i.e., the dispersibility of the modifier is improved. It is presumed that due to the improved dispersibility of these modifiers and the elongation of the molecular chains of the polyester resin, the melt viscosity (IV value) of the polyester resin used as a raw material can be increased, resulting in a resin composition with a melt viscosity higher than that of the polyester resin used as a raw material. Furthermore, it is presumed that, as a result, polyester resin fibers can be manufactured using the resin composition obtained by manufacturing method 1 of this invention. It should be noted that the present invention is not limited to these presumptions.

[0055] As described above, in step 1 of this manufacturing method 1, the reactive functional groups (e.g., epoxy groups) of the units containing reactive functional groups in the polymer (A) contained in the modifier can react with the terminal functional groups (e.g., hydroxyl or carboxyl groups) of the polyester resin. Therefore, in the modifier, which is a raw material before melt mixing, the units containing reactive functional groups exist in a state where they can react with the terminal functional groups of the polyester resin. On the other hand, in the modifier constituting the obtained resin composition, that is, in the structural units from the modifier in the resin composition, the units containing reactive functional groups can at least partially exist in a state where they are covalently bonded to the terminals of the structural units from the polyester resin in the resin composition.

[0056] The reactive functional group is not particularly limited as long as it is a functional group that can react with the terminal functional group of the polyester resin. For example, it can be at least one functional group selected from epoxy, oxetyl, hydroxyl, amino, imide, carboxylic acid and carboxylic anhydride.

[0057] The unit containing the reactive functional group can be a structural unit from a monomer containing a cyclic ester or a structural unit from a monomer containing a cyclic amide.

[0058] In this specification, sometimes "a monomer containing a reactive functional group having an X group as a reactive functional group" is referred to as "a monomer containing an X group", and sometimes "a structural unit derived from a monomer containing a reactive functional group having an X group as a reactive functional group", that is, "a structural unit having an X group as a reactive functional group" is referred to as "a unit containing an X group".

[0059] Specific examples of monomers containing epoxy groups include glycidyl methacrylate, 4-hydroxybutyl methacrylate glycidyl ether, 3,4-epoxycyclohexyl (meth)acrylate, allyl glycidyl ether, β-methyl glycidyl methacrylate, and 4-vinylbenzyl glycidyl ether, which are vinyl monomers containing glycidyl groups. Among these, from a reactivity point of view, glycidyl methacrylate and 4-hydroxybutyl methacrylate glycidyl ether are preferred as monomers containing epoxy groups, glycidyl methacrylate and 4-hydroxybutyl methacrylate glycidyl ether are more preferred, and glycidyl methacrylate is even more preferred. In this specification, "(meth)acrylate" means "acrylate and / or methacrylate".

[0060] Specific examples of monomers containing oxetyl groups include (vinyloxyalkyl)alkyloxetane, (meth)acryloyloxyalkyloxetane, and [(meth)acryloyloxyalkyl]alkyloxetane. In this specification, "(meth)acryloyl" means "acryloyl and / or methacryloyl".

[0061] Specific examples of monomers containing hydroxyl groups include (a) straight-chain hydroxyalkyl methacrylates such as (a) 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate (particularly preferred are straight-chain hydroxyC1-6 alkyl methacrylates); (b) caprolactone-modified hydroxyalkyl methacrylates; (c) branched-chain hydroxyalkyl methacrylates such as methyl α-(hydroxymethyl)(meth)acrylate and ethyl α-(hydroxymethyl)(meth)acrylate; (d) hydroxyl-containing (meth)acrylates such as mono(meth)acrylates of polyester glycols (particularly preferred are saturated polyester glycols) obtained from dicarboxylic acids (phthalic acid, etc.) and diols (propylene glycol, etc.); and (e) maleic esters containing hydroxyl groups. It should be noted that "straight-chain C1-6 alkyl" means a straight-chain alkyl group having one or more but less than six carbon atoms. In this specification, "(meth)acrylate" means "acrylic acid and / or methacrylic acid".

[0062] Specific examples of monomers containing amino groups include N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide, 2-vinylpyridine, 4-vinylpyridine, and monomers containing H... ＋ X - The compounds with structures obtained by neutralizing them with acids, etc.

[0063] Specific examples of monomers containing an imide group include maleimide, phenyl maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N-cyclohexylmaleimide, N-chlorophenylmaleimide, N-methylphenylmaleimide, N-bromophenylmaleimide, N-naphthylmaleimide, N-laurylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-nitrophenylmaleimide, and N-benzylmaleimide.

[0064] Specific examples of monomers containing a carboxylic acid group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid. From a reactivity point of view, monocarboxylic acids are preferred as monomers containing a carboxylic acid group.

[0065] Specific examples of monomers containing carboxylic anhydride groups include maleic anhydride.

[0066] As a reactive functional group unit in polymer (A), it may be composed of only (i) a reactive functional group unit from any one of the aforementioned reactive functional group monomers, or it may be composed of (ii) a combination of any two or more reactive functional group units from any two or more of the aforementioned reactive functional group monomers.

[0067] From the viewpoint of the reactivity of the terminal functional groups generated by the decomposition and deterioration of polyester resins with the modifier, the units containing reactive functional groups in polymer (A) (i) preferably include one or more units selected from units containing epoxy groups, units containing hydroxyl groups, units containing carboxylic acid groups, and units containing carboxylic anhydride groups, or may be composed of only one or more units selected from this group; (ii) more preferably include one or more units selected from (meth)acrylate units containing epoxy groups, maleate units containing hydroxyl groups, monocarboxylic acid units, dicarboxylic acid units, and units containing carboxylic anhydride groups, or may be composed of only one or more units selected from this group; (iii) more preferably include one or more units selected from (meth)acrylate units containing epoxy groups, maleate units containing hydroxyl groups, acrylic acid units, methacrylic acid units, maleic acid units, and maleic anhydride units, or may be composed of only one or more units selected from this group; (iv) particularly preferably include (meth)acrylate units containing epoxy groups, or may be composed of only (meth)acrylate units containing epoxy groups.

[0068] From the viewpoint of the polymerization productivity of monomers containing reactive functional groups, which are the source of units containing reactive functional groups, the units containing reactive functional groups in polymer (A) preferably include one or more selected from glycidyl methacrylate units, 4-hydroxybutyl methacrylate glycidyl ether units, 3,4-epoxycyclohexyl (meth)acrylate units, and β-methyl glycidyl methacrylate units, or may be composed of only one or more selected from this group; (ii) more preferably include one or more selected from glycidyl methacrylate units, 4-hydroxybutyl methacrylate glycidyl ether units, and 3,4-epoxycyclohexyl (meth)acrylate units, or may be composed of only one or more selected from this group; (iii) further preferably include one or more selected from glycidyl methacrylate units and 4-hydroxybutyl methacrylate glycidyl ether units, or may be composed of only one or more selected from this group; (iv) most preferably include glycidyl methacrylate units, or may be composed of only glycidyl methacrylate units.

[0069] The content of reactive functional group units in polymer (A) is not particularly limited, but is preferably 10% to 60% by weight or more in 100% by weight of polymer (A). The upper limit of the above content can be 55% by weight, 50% by weight, 45% by weight, or 40% by weight, and the lower limit can be 15% by weight, 20% by weight, 25% by weight, or 30% by weight. As long as the content of reactive functional group units in polymer (A) is within the above range, the modifier can effectively improve the melt viscosity of the resin composition. As a result, the following advantages are achieved: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are superior. In this specification, "superior formability of polyester resin fibers" means that the fiber thickness distribution of the polyester resin fibers is more uniform.

[0070] The content of epoxy-containing units in polymer (A) is not particularly limited, but is preferably 10% to 60% by weight or more in 100% by weight of polymer (A). The upper limit of the above content can be 55% by weight, 50% by weight, 45% by weight or 40% by weight, and the lower limit can be 15% by weight, 20% by weight, 25% by weight or 30% by weight. As long as the content of epoxy-containing units in polymer (A) is within the above range, the modifier can be more effective in improving the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity, and (ii) the formability and strength of the polyester resin fibers are further improved.

[0071] (Units that do not contain reactive functional groups)

[0072] In this specification, "units without reactive functional groups" refers to structural units derived from monomers that do not have reactive functional groups capable of reacting with the terminal functional groups of polyester resins (hereinafter, sometimes also referred to as "monomers without reactive functional groups"). In other words, the units without reactive functional groups contained in the polymer (A) of the modifier cannot react with the terminal functional groups of the polyester resin. Alternatively, the units without reactive functional groups in polymer (A) may also be structural units derived from monomers capable of copolymerizing with monomers containing reactive functional groups in polymer (A).

[0073] There is no particular limitation on the monomer without reactive functional groups that serves as the source of the non-reactive functional group unit in polymer (A). Examples of such non-reactive functional group monomers include (meth)acrylate monomers, cyanide vinyl compounds, and aromatic vinyl compounds.

[0074] Specific examples of (meth)acrylate monomers that do not contain reactive functional groups include (meth)acrylic acid and (meth)acrylate esters that do not contain reactive functional groups. "(Meth)acrylate esters that do not contain reactive functional groups" means "(meth)acrylate esters (esters of (meth)acrylic acid) that do not have reactive functional groups and are substituted or unsubstituted by functional groups other than reactive functional groups." Specific examples of (meth)acrylate esters that do not contain reactive functional groups include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, and other alkyl (meth)acrylate esters that have alkyl groups with 1 or more but less than 22 carbon atoms, and which do not contain reactive functional groups.

[0075] The number of carbon atoms of the alkyl group in the (meth)acrylate unit without reactive functional groups is not particularly limited. From the viewpoint of the polymerizability of the monomer from which the structural unit is derived, the number of carbon atoms of the alkyl group in the (meth)acrylate unit without reactive functional groups is preferably 22 or less. Furthermore, from the viewpoint of compatibility with polyester resins, the number of carbon atoms of the alkyl group in the (meth)acrylate unit without reactive functional groups is more preferably 12 or less, further preferably 8 or less, and particularly preferably 1 or more and 4 or less.

[0076] From the viewpoint of the dispersibility of the modifier in step 1, in polymer (A), as a unit without reactive functional groups, (i) more preferably includes (meth)acrylate units without reactive functional groups, or may be composed only of (meth)acrylate units without reactive functional groups; (ii) more preferably includes (meth)acrylate alkyl ester units without reactive functional groups, or may be composed only of (meth)acrylate alkyl ester units without reactive functional groups; (iii) preferably includes (meth)acrylate alkyl ester units without epoxy groups, or may be composed only of (meth)acrylate alkyl ester units without epoxy groups; (iv) more preferably includes one or more units selected from (meth)acrylate, (meth)acrylate, (meth)acrylate, and (meth)acrylate; or may be composed only of one or more units selected from this group; (v) further preferably includes one or more units selected from (meth)acrylate and (butyl acrylate); or may be composed only of one or more units selected from this group; (vi) most preferably includes (meth)acrylate units, or may be composed only of (meth)acrylate units.

[0077] The content of non-reactive (meth)acrylic units in polymer (A) is not particularly limited, but is preferably 40% to 90% by weight or more out of 100% by weight of polymer (A). The upper limit of the above content can be 85%, 80%, 75%, or 70% by weight, and the lower limit can be 45%, 50%, 55%, or 60% by weight. As long as the content of non-reactive (meth)acrylic units in polymer (A) is within the above range, the dispersibility of the modifier in step 1 is improved. Furthermore, as long as the content of non-reactive (meth)acrylic units in polymer (A) is within the above range, by restricting the branched structure during crosslinking to fewer directions, the elongation of the resin (resin composition) in step 2 described later can be made more uniform. Thus, the modifier can effectively improve the melt viscosity of the resin composition without impairing processability. As a result, the following advantages are achieved: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are superior.

[0078] Specific examples of cyanide vinyl compounds that do not contain reactive functional groups include acrylonitrile and methacrylonitrile.

[0079] Specific examples of aromatic vinyl compounds that do not contain reactive functional groups include styrene monomers and 1-vinylnaphthalene, which do not contain reactive functional groups. In this specification, "styrene monomers that do not contain reactive functional groups" means "styrene that does not have reactive functional groups and is substituted or unsubstituted by functional groups other than reactive functional groups." Specific examples of styrene monomers that do not contain reactive functional groups include styrene, vinyltoluene, α-methylstyrene, 4-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 4-ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 3-(tert-butyl)styrene, 2,4-dichlorostyrene, and 2,6-dichlorostyrene.

[0080] As a non-reactive functional group unit in polymer (A), it may be composed of only (i) a non-reactive functional group unit from any one of the aforementioned non-reactive functional group monomers, or it may be composed of (ii) a combination of any two or more non-reactive functional group units from any two or more of the aforementioned non-reactive functional group monomers.

[0081] From the viewpoint of the polymerization productivity of monomers as the source of structural units, in polymer (A), as units without reactive functional groups, (i) preferably include aromatic vinyl compound units without reactive functional groups, or may be composed only of aromatic vinyl compound units without reactive functional groups, (ii) preferably include styrene units without reactive functional groups, or may be composed only of styrene units without reactive functional groups, (iii) preferably include one or more units selected from 4-methylstyrene units, 3-methylstyrene units, α-methylstyrene units and styrene units, or may be composed only of one or more units selected from this group, (iv) more preferably include one or more units selected from 4-methylstyrene units, α-methylstyrene units and styrene units, or may be composed only of one or more units selected from this group, (v) further preferably include one or more units selected from α-methylstyrene units and styrene units, or may be composed only of one or more units selected from this group, (vi) most preferably include styrene units, or may be composed only of styrene units.

[0082] The content of aromatic vinyl compound units without reactive functional groups in polymer (A) is not particularly limited, but is preferably 40% to 90% by weight or more in 100% by weight of polymer (A). The upper limit of the above content can be 85% by weight, 80% by weight, 75% by weight, or 70% by weight, and the lower limit can be 45% by weight, 50% by weight, 55% by weight, or 60% by weight. As long as the content of aromatic vinyl compound units without reactive functional groups in polymer (A) is within the above range, it has the advantage of improved dispersibility of the modifier in step 1.

[0083] The total content of non-reactive functionalized styrene units and non-reactive functionalized (meth)acrylic units in polymer (A) is not particularly limited. The total content of non-reactive functionalized styrene units and non-reactive functionalized (meth)acrylic units in polymer (A) is preferably 40% to 90% by weight or more per 100% by weight of polymer (A). The upper limit of the above content can be 85% by weight, 80% by weight, 75% by weight, or 70% by weight, and the lower limit can be 45% by weight, 50% by weight, 55% by weight, or 60% by weight. As long as the total content of non-reactive functionalized styrene units and non-reactive functionalized (meth)acrylic units in polymer (A) is within the above range, it has the advantage that the transparency derived from the polyester resin is not impaired after melt blending with the polyester resin in step 1 through optimization of the refractive index. That is, it has the advantage that a resin composition with higher transparency can be obtained in step 1.

[0084] The total content of non-reactive functional group units in polymer (A), excluding the non-reactive alkyl (meth)acrylate units, is not particularly limited. The content of non-reactive functional group units in polymer (A), excluding the non-reactive alkyl (meth)acrylate units, is preferably 0% to 10% by weight or less per 100% by weight of polymer (A). The upper limit of the above content can be 8% by weight or 5% by weight, and the lower limit can be 2% by weight or 4% by weight. As long as the total content of non-reactive functional group units in polymer (A), excluding the non-reactive alkyl (meth)acrylate units, is within the above range, it has the advantage of improving productivity.

[0085] The total content of non-reactive functional group units in polymer (A) is not particularly limited, but is preferably 40% to 90% by weight or more in 100% by weight of polymer (A). The upper limit of the above content can be 85% by weight, 80% by weight, 75% by weight, or 70% by weight, and the lower limit can be 45% by weight, 50% by weight, 55% by weight, or 60% by weight. As long as the total content of non-reactive functional group units in polymer (A) is within the above range, the dispersibility of the modifier in step 1 is improved, and therefore the modifier has a good effect on improving the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are superior.

[0086] Furthermore, from the viewpoints of (i) the compatibility of the modifier with the polyester resin in step 1 and the dispersibility of the modifier, and (ii) the productivity of the modifier itself, polymer (A) preferably comprises the structural units represented by (i) and (ii) below:

[0087] (i) An epoxy-containing (meth)acrylate unit is used as the above-mentioned unit containing a reactive functional group;

[0088] (ii) One or more structural units selected from styrene-based units and (meth)acrylic-based units that do not contain reactive functional groups are used as the above-mentioned units that do not contain reactive functional groups.

[0089] When the number average content of reactive functional groups in polymer (A) is high, the reactivity of polymer (A) with the terminal functional groups of the polyester resin is enhanced in step 1. As a result, the increase in molecular weight and the increase in melt viscosity of the polyester resin are more significant. From this viewpoint, each molecule of polymer (A) preferably has 2 or more, more preferably 3 or more, and even more preferably 4 or more reactive functional groups on average. Each molecule of polymer (A) may have 5 or more, 6 or more, or 7 or more reactive functional groups on average. In this specification, the "number average content of reactive functional groups" per molecule of polymer is a value measured by conventionally known methods. For example, in this specification, the "epoxy group content" is a value calculated based on the epoxy equivalent measured by titration as described in JIS K 7236. In this specification, the "hydroxyl content" is calculated based on the hydroxyl value determined by the titration method described in JIS K 0070 and JIS K 1557-1. In this specification, the "amino content" is calculated based on the total amine value determined by the titration method described in JIS K 7237. In this specification, the "carboxylic acid group content" is calculated based on the acid value determined by the titration method described in JIS K 0070 and JIS K 1557-5. The content of reactive functional groups can also be calculated based on the saponification value and iodine value determined by the titration method described in JIS K 0070.

[0090] On the other hand, when the number average content of reactive functional groups in polymer (A) is below a certain amount, the branching degree of the structural units from the polyester resin in the resin composition obtained in step 1 will not be too high, and entanglement of the structural units from the polyester resin is prevented or reduced. Therefore, there is no concern about the resin composition having excessive rigidity. As a result, in step 2 described later, there is no concern about the resin composition breaking or producing broken fibers due to the stress applied during winding. That is, by setting the number average content of reactive functional groups in polymer (A) below a certain amount, it is advantageous to improve the stability in the manufacture of polyester resin fibers and to manufacture polyester resin fibers more stably. From this point of view, each molecule of polymer (A) preferably has 10 or less, more preferably 9 or less, more preferably 8 or less, further preferably 7 or less, and particularly preferably 6 or less reactive functional groups on average. Furthermore, when the upper and lower limits of the content (number average) of reactive functional groups per molecule of polymer (A) are both within the above-mentioned preferred range, the melt viscosity of the resin composition can be appropriately increased without causing gelation and without impairing the mechanical properties, heat resistance, rheological properties, etc. of the polyester resin fiber.

[0091] The number-average molecular weight of polymer (A) is not particularly limited, but is preferably less than 10,000 Da, more preferably 8,000 Da or less, further preferably 7,000 Da or less, and particularly preferably 6,000 Da or less. Furthermore, the lower limit of the number-average molecular weight of polymer (A) is not particularly limited, but is preferably 1,000 Da or more, more preferably 3,000 Da or more, further preferably 4,000 Da or more, further preferably 5,000 Da or more, and particularly preferably 6,000 Da or more. When the number-average molecular weight of polymer (A) is within the above-mentioned preferred range, the modifier has a good effect on increasing the melt viscosity of the resin composition. As a result, the following advantages are achieved: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are superior. In addition, when the number-average molecular weight of polymer (A) is within the above-mentioned preferred range, it also has the advantage of a good balance between the thermal stability of the modifier and productivity. In this specification, the "number-average molecular weight" of the polymer refers to the value obtained by the method described in the following examples.

[0092] The weight-average molecular weight of polymer (A) is not particularly limited, but is preferably 80,000 Da or less, more preferably 70,000 Da or less, even more preferably 60,000 Da or less, and particularly preferably 50,000 Da or less. Furthermore, the lower limit of the weight-average molecular weight of polymer (A) is not particularly limited, but is preferably 3,000 Da or more, more preferably 5,000 Da or more, even more preferably 6,000 Da or more, even more preferably 7,000 Da or more, and particularly preferably 8,000 Da or more. When the weight-average molecular weight of polymer (A) is within the above-mentioned preferred range, it has the advantages of raising the softening point of the resin composition to prevent agglomeration, good workability when added to polyester resin, and less likely to adversely affect the strength and / or properties of the fiber. In this specification, the "weight-average molecular weight" of the polymer is a value obtained by the method described in the following examples.

[0093] The polydispersity index of polymer (A) is preferably 2.0 or higher and 10.0 or lower, more preferably 2.0 or higher and 8.0 or lower, even more preferably 2.0 or higher and 6.0 or lower, and particularly preferably 2.0 or higher and 4.0 or lower. Using this configuration provides the advantages of being less prone to unexpected side effects in terms of quality and exhibiting high quality stability. In this specification, the "polydispersity index" of the polymer is a value obtained by the method described in the following examples.

[0094] Modifiers may also contain monomers. For example, in the presence of monomers not consumed in polymerization from the monomers used in the manufacture of polymer (A) and / or polymer (B) described later, the resulting modifier may contain monomers from those monomers. In this specification, the monomers contained in the modifier are sometimes referred to as "monomer residues." As monomer residues, the modifier may contain residues of monomers containing reactive functional groups (i.e., "monomer residues containing reactive functional groups"). In this specification, the total amount of monomer residues that may be contained in the modifier is sometimes collectively referred to as "total monomer residues."

[0095] The lower the total monomer residue content in the modifier, the better. Based on the weight of the modifier, the total monomer residue content is preferably less than 2000 ppm, more preferably less than 500 ppm, further preferably less than 100 ppm, and particularly preferably less than 100 ppm. The total monomer residue content is particularly preferably below the detection limit of the instrument used to determine the monomer residue in the modifier, i.e., it is particularly preferable that the total monomer residue is not detected. Using this composition, especially in food contact applications, has the advantage of a low risk of monomer migration into food. Furthermore, the lower the content of monomer residue containing reactive functional groups in the modifier, the better. Based on the weight of the modifier, the content of monomer residue containing reactive functional groups is preferably less than 1000 ppm, more preferably less than 500 ppm, further preferably less than 100 ppm, and even more preferably less than 100 ppm, and particularly preferably less than 50 ppm. The content of monomer residues containing reactive functional groups in the modifier is particularly preferably below the detection limit of the instrument used to determine the monomer residues containing reactive functional groups in the modifier, that is, it is particularly preferably that the monomer residues containing reactive functional groups are not detected. If this configuration is adopted, it has the advantage of a low risk of monomers containing reactive functional groups migrating into food, especially in food contact applications. It should be noted that the lower limit values ​​for both the total monomer residue content and the monomer residue content containing reactive functional groups in the modifier are 0 ppm. In this specification, the "total monomer residue content" and "monomer residue content containing reactive functional groups" in the modifier are values ​​obtained by the methods described in the following examples.

[0096] The epoxy equivalent of polymer (A) is preferably 100 g / eq or more and 3000 g / eq or less, more preferably 350 g / eq or more and 2500 g / eq or less, even more preferably 500 g / eq or more and 2500 g / eq or less, and particularly preferably 1000 g / eq or more and 2000 g / eq or less. This configuration provides the advantage of good processability during the fiber stretching process.

[0097] In this specification, the epoxy equivalent of a polymer refers to the molecular weight of each epoxy group contained in the polymer, specifically the value calculated using the following formula:

[0098] The epoxy equivalent of a polymer (g / eq) = the number average molecular weight of the polymer (Mn) / the number of epoxy groups per molecule of the polymer (average number).

[0099] It should be noted that the epoxy equivalent can also be determined according to JIS K7236.

[0100] In this specification, the epoxy equivalent of polymer (A) is a value calculated by the method detailed in the examples below.

[0101] Polymer (A) is preferably a non-rubber polymer. A non-rubber polymer is a polymer whose molecular chains do not have cross-linking structures. By making polymer (A) a non-rubber polymer, the reaction between the reactive functional groups (e.g., epoxy groups) of polymer (A) and the terminal functional groups of the polyester resin is more efficient, and the melt viscosity of the resin composition is easily increased.

[0102] (Method for manufacturing polymer (A))

[0103] The polymerization method for polymer (A) is not particularly limited, and known methods can be used. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., can be used as polymerization methods for polymer (A), with emulsion polymerization being preferred.

[0104] In the manufacture of polymer (A), polymerization is preferably carried out in the presence of a chain transfer agent in order to control the molecular weight. A chain transfer agent is preferably used in the manufacture of polymer (A). The polymer obtained using a chain transfer agent may contain structural units derived from the chain transfer agent. In other words, polymer (A) preferably contains structural units derived from the chain transfer agent.

[0105] There are no particular limitations on chain transfer agents, but examples include primary thiol chain transfer agents such as n-butylthiol, n-octylthiol, n-hexadecylthiol, n-dodecylthiol, and n-tetradecylthiol; secondary thiol chain transfer agents such as sec-butylthiol and sec-dodecylthiol; tertiary thiol chain transfer agents such as tertiary dodecylthiol; thiols; 2-ethylhexylthioacetate, ethylene glycol dimercaptoacetate, trimethylolpropane tris(thioacetate), pentaerythritol tetra(thioacetate); thiophenol; tetraethylthiuram disulfide; pentaphenylethane; acrolein; methacrolein; allyl alcohol; carbon tetrachloride; vinyl bromide; styrene oligomers such as α-methylstyrene dimer; and terpinene oils. A single chain transfer agent can be used, or two or more can be used in combination. The amount of chain transfer agent used should be appropriately set according to the desired number-average molecular weight of polymer (A).

[0106] There are no particular limitations on emulsifiers (dispersants) that can be used in emulsion polymerization, and examples include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Additionally, dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives can also be used. An emulsifier (dispersant) can be used alone or in combination of two or more.

[0107] When using emulsion polymerization, thermally decomposable initiators can be used as free radical polymerization initiators. Examples of such thermally decomposable initiators include 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0108] Redox initiators can also be used as free radical polymerization initiators. These redox initiators are initiators that combine (a) peroxides such as organic and inorganic peroxides with (b) reducing agents such as sodium formaldehyde sulfoxylate or glucose, as needed, transition metal salts such as ferric sulfate (II), chelating agents such as disodium ethylenediaminetetraacetate, as needed, and phosphorus-containing compounds such as sodium pyrophosphate, as needed. Examples of organic peroxides include tert-butyl peroxyisopropyl carbonate, terpene hydrogen peroxide, cumene hydroperoxide, dicumene peroxide, tert-butyl hydrogen peroxide, di-tert-butyl peroxide, and tert-hexyl peroxide. Examples of inorganic peroxides include hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0109] When using a redox initiator, polymerization can be carried out even at low temperatures where the peroxides do not substantially undergo thermal decomposition, and the polymerization temperature can be set over a wide range. Therefore, it is preferable to use a redox initiator. Among the redox initiators, organic peroxides such as cumene hydroperoxide, dicumene peroxide, terpene hydroperoxide, and tert-butyl hydroperoxide are preferred as redox initiators for peroxides. The amount of the initiator used, as well as the amounts of the reducing agent, transition metal salt, and chelating agent used when using a redox initiator, can be used within known ranges.

[0110] Well-known surfactants can also be used when polymerizing polymer (A).

[0111] When polymer (A) is manufactured using emulsion polymerization, a latex containing polymer (A) (e.g., an aqueous latex) can be obtained. Polymer (A) can be obtained by separating polymer (A) from the latex containing polymer (A). The obtained polymer (A) can be used as a modifier. There are no particular limitations on the method for separating polymer (A) from the latex containing polymer (A); examples include salting out polymer (A) using acids and metal salts, or precipitating polymer (A) using organic solvents. The polymer (A) separated from the latex containing polymer (A) can be washed or further dried. By separating polymer (A) from the latex containing polymer (A), washing, and further drying, a powder of polymer (A) (also called "powder") can be obtained. Alternatively, a powder of polymer (A) can also be obtained by spray drying the latex containing polymer (A). The powder of polymer (A) obtained in this way can be used as a modifier.

[0112] (Polymer (B))

[0113] In addition to polymer (A), the modifier may or may not contain polymer (B). The polymer component in the modifier may consist only of polymer (A), or only of polymer (A) and polymer (B), or of polymer (A), polymer (B), and other polymers.

[0114] The case where the modifier comprises polymer (A) and polymer (B) (hereinafter also referred to as "Case A") will be described. In Case A, it is preferable to polymerize polymer (B) in the presence of polymer (A) after polymerizing polymer (A). In Case A, when polymer (A) is obtained by, for example, emulsion polymerization, it is particularly preferable to manufacture (polymerize) polymer (B) in a latex containing polymer (A) after the manufacture (polymerization) of polymer (A). When polymer (B) is manufactured (polymerized) in a latex containing polymer (A), a composite consisting of polymer (A) and polymer (B) (or containing polymer (A) and polymer (B)) can be obtained. In this composite, polymer (B) may cover a portion of polymer (A). Therefore, in this composite, polymer (A) can be referred to as the core and polymer (B) as the shell. The composite may have a core-shell structure with polymer (A) as the core and polymer (B) as the shell. In other words, when polymer (B) is manufactured (polymerized) in a latex containing polymer (A), a composite consisting of polymer (A) and polymer (B) can be obtained, which is a core-shell structure in which polymer (A) forms the core and polymer (B) forms the shell. In the composite, polymer (B) can cover the entirety of polymer (A), and at least a portion of polymer (B) can be impregnated into the interior of the particulate polymer (A).

[0115] When the modifier contains polymer (A) and polymer (B), and the composite formed by polymer (A) and polymer (B) has a core-shell structure in which polymer (A) forms the core and polymer (B) forms the shell, it has the advantage of improved productivity.

[0116] There are no particular limitations on polymer (B). The composition of the structural units of polymer (B) may be the same as or different from that of polymer (A). In other words, the composition of monomer mixture (B) may be the same as or different from that of monomer mixture (A).

[0117] In case A, polymer (B) is particularly preferably configured to have the function of dispersing polymer (A) more uniformly in polyester resin, in other words, to act as a carrier so that polymer (A) which functions as a chain extender can react more uniformly with polyester resin during melt mixing of modifier and polyester resin.

[0118] Polymer (B) is particularly preferred to have a composition that improves granulation properties when manufacturing the modifier. If polymer (A) is polymerized alone and formed into powder (powdering), it becomes micronized powder, which is sometimes difficult to handle. In this case, compared to such polymer (A), a modifier with excellent processability can be obtained by polymerizing polymer (B) with polymer (A) together with polymer (A) and simultaneously separating polymers (A) and (B).

[0119] Polymer (B) may contain units with reactive functional groups or may not contain units with reactive functional groups. Polymer (B) may be composed only of units with reactive functional groups or only of units without reactive functional groups. Polymer (B) preferably contains both units with and without reactive functional groups. When polymer (B) contains both units with and without reactive functional groups, the softening point of the modifier (complex) is increased, and defects such as agglomeration are less likely to occur. As a result, there is the advantage of increased productivity. In addition, when polymer (B) contains both units with and without reactive functional groups, the dispersibility of the modifier (complex) is improved, thus also having the advantage of improved dispersibility of polymer (A).

[0120] Specific examples of units containing reactive functional groups in polymer (B) are the same as those described in the section on (units containing reactive functional groups) of the above-mentioned item (Polymer (A)), therefore, that description is cited and will not be repeated here. Preferred embodiments of units containing reactive functional groups in polymer (A) are also preferred embodiments of units containing reactive functional groups in polymer (B). Specific examples of units without reactive functional groups in polymer (B) are the same as those described in the section on (units without reactive functional groups) of the above-mentioned item (Polymer (A)), therefore, that description is cited and will not be repeated here. Preferred embodiments of units without reactive functional groups in polymer (A) are also preferred embodiments of units without reactive functional groups in polymer (B).

[0121] The case where polymer (B) contains units with reactive functional groups will be described. In this case, the unit containing the reactive functional group preferably contains an epoxy-containing (meth)acrylate unit, and more preferably contains a glycidyl methacrylate unit. In other words, in polymer (B), the unit containing the reactive functional group preferably contains an epoxy-containing (meth)acrylate unit, and more preferably contains a glycidyl methacrylate unit. With this configuration, there are advantages in terms of good compatibility between the modifier and the polyester resin and good dispersibility of the modifier in step 1.

[0122] The case where polymer (B) contains units containing reactive functional groups will be described. In this case, polymer (B) preferably contains more than 2.5% to less than 10.0% by weight of units containing reactive functional groups in 100% by weight of polymer (B), more preferably more than 2.5% to less than 9.0% by weight, further preferably more than 3.0% to less than 8.0% by weight, and particularly preferably more than 4.0% to less than 6.0% by weight.

[0123] Polymer (B) preferably comprises one or more structural units selected from styrene-based units and (meth)acrylate-based units. The term "styrene-based unit" includes both structural units derived from styrene monomers containing reactive functional groups (e.g., 4-vinylbenzyl glycidyl ether) and structural units derived from styrene monomers without reactive functional groups. The term "(meth)acrylate-based unit" includes both structural units derived from (meth)acrylate monomers containing reactive functional groups and structural units derived from (meth)acrylate monomers without reactive functional groups. Specific examples of (meth)acrylate monomers containing reactive functional groups can be appropriately referenced from the description in the section on "Units Containing Reactive Functional Groups" of the above-mentioned (Polymer (A)) item. Specific examples of styrene monomers without reactive functional groups and (meth)acrylate monomers without reactive functional groups are the same as those described in the section on "Units Without Reactive Functional Groups" of the above-mentioned (Polymer (A)) item, and therefore, this description is referenced and omitted here.

[0124] For polymer (B), (i) more preferably, it comprises one or more structural units selected from styrene-based units and alkyl (meth)acrylate-based units without reactive functional groups, or it may be composed of only one or more units selected from this group; (ii) more preferably, it comprises one unit selected from styrene units, (meth)acrylate units containing reactive functional groups, (meth)acrylate methyl acrylate units without reactive functional groups, (meth)acrylate ethyl acrylate units without reactive functional groups, (meth)acrylate propyl acrylate units without reactive functional groups, and (meth)acrylate butyl acrylate units without reactive functional groups. The structural units on the surface may be composed of only one or more units selected from the group, (iii) more preferably, they include one or more structural units selected from styrene units, glycidyl methacrylate units, methyl methacrylate units, ethyl methacrylate units and butyl methacrylate units, and may be composed of only one or more units selected from the group, (iv) more preferably, they include one or more structural units selected from styrene units, glycidyl methacrylate units, methyl methacrylate units and butyl methacrylate units, and may be composed of only one or more units selected from the group.

[0125] The total content of styrene-based units and (meth)acrylic units in polymer (B) is not particularly limited, but is preferably 40% to 99% by weight or more out of 100% by weight of polymer (B). The upper limit of the above content can be 99% by weight, 90% by weight, 80% by weight, or 70% by weight, and the lower limit can be 40% by weight, 50% by weight, 60% by weight, or 70% by weight. As long as the total content of styrene-based units and (meth)acrylic units in polymer (B) is within the above range, gelation of the modifier (complex) can be prevented or reduced, thereby improving the dispersibility of the modifier (complex) and resulting in good productivity of polymer (B).

[0126] Preferably, the number-average molecular weight of polymer (B) is different from that of polymer (A). More preferably, the number-average molecular weight of polymer (B) is greater than that of polymer (A). According to this configuration, the softening point of the modifier (complex) is increased, and it is less prone to defects such as agglomeration. As a result, it has the advantage of increased productivity.

[0127] The number-average molecular weight of polymer (B) is preferably 8000 Da or more and 300000 Da or less, more preferably 10000 Da or more and 200000 Da or less, even more preferably 12000 Da or more and 150000 Da or less, and particularly preferably 15000 Da or more and 100000 Da or less. According to this configuration, the softening point of the modifier (complex) is increased, and defects such as agglomeration are less likely to occur. As a result, it has the advantage of improved productivity. Furthermore, when the number-average molecular weight of polymer (B) is within the above-mentioned range, due to the high softening point of polymer (B), the initiation rate of the crosslinking reaction is slowed down when it is added to the polyester resin. Therefore, vigorous reactions during addition can be avoided, preventing or reducing gel formation. As a result, preventing or reducing gel formation also has the advantage of reducing breakage points in processes such as fiber stretching, thereby improving fiber productivity.

[0128] Preferably, the weight-average molecular weight of polymer (B) is different from that of polymer (A). More preferably, the weight-average molecular weight of polymer (B) is greater than that of polymer (A). According to this configuration, the softening point of the modifier (complex) is increased, and it is less prone to defects such as agglomeration. As a result, it has the advantage of increased productivity.

[0129] The weight-average molecular weight of polymer (B) is preferably 80,000 Da or more and 500,000 Da or less, more preferably 100,000 Da or more and 300,000 Da or less, even more preferably 120,000 Da or more and 250,000 Da or less, and particularly preferably 140,000 Da or more and 200,000 Da or less. According to this configuration, the softening point of the modifier (complex) is increased, making it less prone to defects such as agglomeration. As a result, it has the advantage of increased productivity. Furthermore, when the weight-average molecular weight of polymer (B) is within the above range, it also has the advantage of improved dispersibility of polymer (A) due to the improved dispersibility of the modifier (complex). Moreover, when the weight-average molecular weight of polymer (B) is within the above range, due to the high softening point of polymer (B), the initiation rate of the crosslinking reaction is adjusted to a very slow direction when added to the polyester resin. Therefore, vigorous reactions during addition can be avoided, preventing or reducing gel formation. As a result, preventing or reducing gel formation also has the advantage of reducing breakage points and improving fiber productivity during processes such as fiber stretching.

[0130] Preferably, the number average content of reactive functional groups in polymer (B) differs from the number average content of reactive functional groups in polymer (A). More preferably, the number average content of reactive functional groups in polymer (B) is greater than the number average content of reactive functional groups in polymer (A). This configuration offers the advantage of improving the dispersibility of the modifier (complex) by preventing or reducing gelation.

[0131] When polymer (B) contains reactive functional groups, polymer (B) preferably has an average of 2 or more and 35 or less reactive functional groups per molecule, more preferably 15 or more and 35 or less. The lower limit of the number average content of reactive functional groups in polymer (B) can be 5 or more, 10 or more, 20 or more, or 25 or more, and the upper limit can be 33 or less. When the number average content of reactive functional groups in polymer (B) is within the above range, the melt viscosity of the resin composition can be appropriately increased without gelation and without impairing the mechanical properties, heat resistance, rheological properties, etc. of the polyester resin fiber.

[0132] The epoxy equivalent of polymer (B) is preferably different from that of polymer (A). The epoxy equivalent of polymer (B) is preferably larger than that of polymer (A). This configuration has the advantage of improving the dispersibility of the modifier (complex) by preventing or reducing gelation of the modifier (complex).

[0133] The epoxy equivalent of polymer (B) is preferably 6000 g / eq or more and 50000 g / eq or less, more preferably 6500 g / eq or more and 45000 g / eq or less, further preferably 7000 g / eq or more and 40000 g / eq or less, and particularly preferably 8000 g / eq or more and 35000 g / eq or less. With this configuration, polymer (B) has the advantage of not hindering the compatibility of the modifier (polymer (A)) with the polyester and not adversely affecting the physical properties. In this specification, the epoxy equivalent of polymer (B) is a value calculated using the method detailed in the examples below.

[0134] Polymer (B) is preferably a non-rubber polymer. With this configuration, the reaction between the reactive functional groups of polymer (B) and the terminal functional groups of the polyester resin proceeds more efficiently, and the melt viscosity of the resin composition is easily increased. In case A, (i) it is preferred that polymer (A) is a non-rubber polymer, or polymer (B) is a non-rubber polymer, and more preferably both polymer (A) and polymer (B) are non-rubber polymers (e.g., the modifier (complex) as a whole is a non-rubber polymer).

[0135] Polymer (A) and polymer (B) may differ from one or more of the following: composition of structural units, number-average molecular weight, weight-average molecular weight, content of reactive functional groups per molecule (number-average), and epoxy equivalent.

[0136] In Case A above, the content ratio of polymer (A) and polymer (B) in the modifier is not particularly limited. In Case A, for example, from the viewpoint of improving the softening point of the modifier (complex) and thus improving the productivity of the modifier (complex), the modifier preferably contains 15% to 70% by weight of polymer (A) and 30% to 85% by weight of polymer (B) in 100% by weight of the modifier; more preferably, it contains 20% to 70% by weight of polymer (A) and 30% to 80% by weight of polymer (B); even more preferably, it contains 30% to 60% by weight of polymer (A) and 40% to 70% by weight of polymer (B); and particularly preferably, it contains 40% to 50% by weight of polymer (A) and 50% to 60% by weight of polymer (B). In addition, in case A, for example from the viewpoint of the production cost of the modifier, the modifier preferably contains 50% or more and 90% or less of polymer (A) and 10% or more and 50% or less of polymer (B) in 100% by weight of the modifier, more preferably contains 70% or more and 90% or less of polymer (A) and 10% or more and 30% or less of polymer (B), and particularly preferably contains 80% or more and 90% or less of polymer (A) and 10% or more and 20% or less of polymer (B).

[0137] (Method for manufacturing polymer (B))

[0138] The polymerization method for polymer (B) is not particularly limited, and known methods can be used. For example, bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc., can be used as polymerization methods for polymer (B), with emulsion polymerization being preferred.

[0139] In manufacturing polymer (B), polymerization is preferably carried out in the presence of a chain transfer agent in order to control the molecular weight. In other words, polymer (B) preferably contains structural units derived from the chain transfer agent.

[0140] Regarding polymer (B), in addition to the foregoing, the description of [polymer (A)] may be appropriately cited.

[0141] (Physical properties of the modifier)

[0142] The weight-average molecular weight of the modifier is preferably 20,000 Da or more and less than 200,000 Da, more preferably 25,000 Da or more and less than 150,000 Da, further preferably 30,000 Da or more and less than 120,000 Da, and particularly preferably 40,000 Da or more and less than 100,000 Da. With this configuration, the modifier can better improve the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the rollability of the polyester resin composition in step 2 is further improved, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are further improved.

[0143] [Other resins]

[0144] In this manufacturing method 1, resins other than polyester resins may be used, or they may not be used. For example, in step 1, polyester resins, resins other than polyester resins, and modifiers may be melt-blended.

[0145] Resins other than polyester resins are not specifically limited, and examples include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, polyoxymethylene, polycarbonate, modified polyphenylene ether, polyamide, cyclic polyolefins, etc.

[0146] In this manufacturing method 1, the amount of resin other than polyester resin used is not particularly limited. For example, relative to 100 parts by weight of polyester resin, it can be more than 0 parts by weight and less than 60 parts by weight. The upper limit can be any one of 50 parts by weight or less, 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, 5 parts by weight or less, and 1 part by weight or less.

[0147] [Other additives]

[0148] Other additives may also be used in this manufacturing method 1. For example, in step 1, polyester resin, modifier, any resin other than polyester resin, and other additives may be melt-blended.

[0149] Other additives are not specifically limited, but can include flame retardants, flame retardant additives, anti-dripping agents, reinforcing agents, fillers, antioxidants, pigments, dyes, conductivity imparting agents, hydrolysis inhibitors, thickeners, plasticizers, lubricants, ultraviolet absorbers, antistatic agents, flow improvers, release agents, compatibilizers, and heat stabilizers.

[0150] [Process 1]

[0151] In step 1, raw materials comprising at least a polyester resin and a modifier, and further comprising any resin other than the polyester resin and / or other additives, are melt-blended. Through the melt blending of the polyester resin and the modifier in step 1, the reactive functional groups (e.g., epoxy groups) of the polymer (A) contained in the modifier can react with the terminal functional groups (e.g., hydroxyl or carboxyl groups) of the polyester resin, causing the molecular chains of the polyester resin to elongate. As a result, step 1 yields a polyester resin composition comprising structural units from the polyester resin and structural units from the modifier. Therefore, step 1 can also be referred to as the step of reacting the polyester resin with the modifier.

[0152] In the melt blending of raw materials containing polyester resins and modifiers, a blending machine such as a single-shaft or twin-shaft extruder, a Banbury mixer, a pressure kneader, or a mixing roller can be used.

[0153] In step 1, before melt-blending the raw materials containing polyester resin and modifier, all of the raw materials can be mixed to obtain a mixture, which is then melt-blended. Alternatively, a portion of the raw materials can be mixed to obtain a mixture, which is then melt-blended with the remaining raw materials. For example, a Henschel mixer or a drum mixer can be used for mixing all or part of the raw materials.

[0154] In step 1, the amount of modifier used relative to the amount of polyester resin used (hereinafter also simply referred to as "the amount of modifier used") is not particularly limited. The amount of modifier used can be determined based on the desired melt viscosity (IV value) of the resulting resin composition. For example, the amount of modifier used can be set to an amount that makes the melt viscosity (IV value) of the resulting resin composition comparable to the melt viscosity (IV value) of the virgin polyester resin. The amount of modifier used can be determined based on the melt viscosity (IV value) of the polyester resin and the type of modifier (e.g., the content (number average) of reactive functional groups in the polymer (A) contained in the modifier).

[0155] In this manufacturing method 1, the amount of modifier used in step 1 relative to the amount of polyester resin used (the amount of modifier used) can be 0.3 parts by weight or more and 3.0 parts by weight or less, 0.1 parts by weight or more and 5.0 parts by weight or less, 0.05 parts by weight or more and 7.0 parts by weight or less, or 0.01 parts by weight or more and 10.0 parts by weight or less.

[0156] (Physical properties of polyester resin compositions)

[0157] As described above, in step 1, the modifier reacts with the polyester resin, causing the molecular chains of the polyester resin to lengthen, thereby increasing the melt viscosity (IV value) of the polyester resin. In other words, it has the advantage that the melt viscosity of the resin composition obtained through step 1 is higher than the melt viscosity of the polyester resin used as a raw material.

[0158] The melt viscosity (IV value) of the resin composition is preferably 0.50 or higher and 0.75 or lower, more preferably 0.53 or higher and 0.75 or lower, even more preferably 0.56 or higher and 0.75 or lower, further preferably 0.60 or higher and 0.70 or lower, and particularly preferably 0.63 or higher and 0.70 or lower. When the melt viscosity (IV value) of the resin composition is within the above range, it has the advantage of excellent processability when the resin composition is formed into polyester resin fibers. In this specification, the melt viscosity (IV value) of the resin or resin composition is set as a value obtained by the method described in the following examples.

[0159] The MFR value of the resin composition obtained through step 1 is lower than the MFR value of the polyester resin used as a raw material. The MFR of the resin composition measured at 270°C and a load of 2.16 kgf is not particularly limited, but is preferably 5 g / 10 min or more and 150 g / 10 min or less, more preferably 15 g / 10 min or more and 120 g / 10 min or less, further preferably 30 g / 10 min or more and 80 g / 10 min or less, and particularly preferably 40 g / 10 min or more and 70 g / 10 min or less. When the MFR of the resin composition is 5 g / 10 min or more, it has the advantages of good flowability and superior processability when the resin composition is formed into polyester resin fibers. When the MFR of the resin composition is 150 g / 10 min or less, it has the advantages of excellent drape and excellent processability.

[0160] [Process 2]

[0161] This manufacturing method 1 includes a step 2 in which the polyester resin composition obtained in step 1 is wound at a winding speed of 400 m / min or more. Through step 2, a fibrous polyester resin composition (or polyester resin), i.e., polyester resin fiber, can be obtained.

[0162] In step 2, there is no particular limitation on the method of winding the polyester resin composition. Whether it is POY (Partially Oriented Yarn) or FDY (Fully Drawn Yarn), the well-known winding method commonly used in the manufacture of polyester resin fibers can be adopted.

[0163] In step 2, the winding speed of the polyester resin composition is a high speed of 400 m / min or more. When the winding speed is high, the amount of polyester resin composition wound per unit time increases, that is, the production quantity of polyester resin fibers increases. Therefore, by achieving a winding speed of 400 m / min or more, polyester resin fibers can be manufactured with high productivity.

[0164] [Cooling process, cutting process, and drying process]

[0165] In this manufacturing method 1, a cooling step may be further included after step 1 to cool the melt-mixed resin composition obtained in step 1. In step 1, for example, the melt-mixed resin composition is extruded in a linear fashion from a die provided with a mixing mill. In the cooling step, for example, the melt-mixed resin composition extruded in a linear fashion from the die provided with a mixing mill is passed through a water tank, thereby cooling the melt-mixed resin composition in the water tank (water cooling).

[0166] After step 1 or the cooling step, a cutting step of cutting the resin composition may be further included. In the cutting step, the linear resin composition is cut into any shape (e.g., particle or granular shape).

[0167] This manufacturing method 1 may further include a drying step of drying the resin composition (e.g., a resin composition in granular shape after a cutting process).

[0168] When this manufacturing method 1 further includes a cooling step and / or a drying step after step 1, the resin composition can be melted before step 2, and the melted resin composition can be wound up in step 2.

[0169] In this manufacturing method 1, the resin composition can be melted using apparatus such as a single-spindle extruder and a twin-spindle extruder. In this manufacturing method 1, the resin composition is melted by heating it to, for example, 240°C or higher and 270°C or lower, 270°C or higher and 300°C or lower, or 300°C or higher and 320°C or lower.

[0170] (Dispensing process)

[0171] This manufacturing method 1 may further include an ejection step prior to step 2, in which molten resin composition is ejected from a perforated nozzle. In the ejection step, the molten resin composition ejected from the nozzle may be (i) a melt-mixed compound of the resin composition obtained in step 1, or (ii) a resin composition obtained by melting a resin composition obtained after step 1 through a cooling step and / or a drying step.

[0172] The nozzle only needs to form one or more holes. There is no particular limit to the number of holes on the nozzle, nor is there any particular limit to the arrangement of the holes on the nozzle.

[0173] The cross-sectional area of ​​each orifice of the nozzle is not particularly limited. From the viewpoint that it is easy to obtain undrawn yarns with a fineness, such as undrawn yarns with a single fiber fineness of 60 dtex or less, preferably 30 dtex or less, the cross-sectional area of ​​each orifice of the nozzle is preferably 0.200 mm². 2 The preferred value is 0.130mm. 2 Hereinafter, 0.060mm is further preferred. 2 The lower limit of the cross-sectional area of ​​each orifice in the nozzle is not particularly limited; for example, from the viewpoint of preventing orifice clogging, it can also be 0.008 mm. 2 above.

[0174] In this specification, the “fineness” of a fiber (filament or resin composition) refers to the thickness of the fiber (filament or resin composition), defined by mass per unit length. Mass (g) per 10,000 m is expressed in units (dtex).

[0175] The shape of the nozzle orifice is not particularly limited and can be selected according to the required properties of the multifilament for drawing (such as appearance, fineness, strength, cross-sectional shape, etc.). Examples of nozzle orifice shapes include circular (including perfect circle, approximately circular, elliptical, and approximately elliptical concepts).

[0176] [Stretching process]

[0177] This manufacturing method 1 may further include a stretching step after step 2, in which the wound polyester resin fibers are stretched. When this manufacturing method 1 further includes a stretching step, the fiber strength of the polyester resin fibers can be improved. In other words, when this manufacturing method 1 further includes a stretching step, polyester resin fibers with higher fiber strength can be obtained.

[0178] In the stretching process, the method 1 for stretching the polyester resin fibers obtained in step 2 (the fibers wound in step 2) is not particularly limited. For example, known methods 1 for stretching fibers, such as hot stretching with heating, can be used. When the above-mentioned hot stretching is used in the stretching process, known means such as heating rollers, heating plates, steam jet devices, and warm water baths can be used as the heating means for hot stretching, and these means can also be used in appropriate combinations.

[0179] The fineness of the stretched polyester resin fiber can be adjusted by the fineness of the wound polyester resin fiber obtained in step 2 above, as well as the stretching conditions such as the stretching ratio in the stretching process. Here, the suitable fineness of the polyester resin fiber varies depending on the intended use of the polyester resin fiber. Therefore, the suitable stretching conditions in the stretching process can be appropriately adjusted according to the intended use of the polyester resin fiber and the fineness of the polyester resin fiber itself obtained in step 2. It should be noted that the fineness of the polyester resin fiber itself obtained in step 2 can be adjusted according to the manufacturing conditions in step 2, such as the winding speed. Furthermore, when a dispensing process is further included, the fineness of the polyester resin fiber can also vary depending on the conditions of the dispensing process.

[0180] In the stretching process, the stretching ratio of the polyester resin composition is not particularly limited. However, from the viewpoint of fiber strength, it is preferably 1.1 times or more and 5.0 times or less, more preferably 1.5 times or more and 4.5 times or less, and particularly preferably 2.0 times or more and 4.0 times or less.

[0181] The polyester resin fibers obtained in step 2 and the stretching step can be long fibers. "Long fibers" are sometimes also called "filaments" or "filament / fibers". In other words, both step 2 and the stretching step can be referred to as processes that process the polyester resin composition into long fibers. Furthermore, by cutting the long fibers of the polyester resin fibers obtained in step 2 and the stretching step, short fibers of polyester resin fibers can be manufactured. "Short fibers" are sometimes also called "staple fibers" or "staple fiber / fibers".

[0182] [2. Implementation Method 2]

[0183] Hereinafter, another embodiment of the present invention (Embodiment 2) will be described.

[0184] The fineness, or fineness, of polyester resin fibers varies depending on the intended use of the final product. Similarly, the preferred range of mechanical properties of polyester resin fibers also varies depending on the intended use of the final product. For example, the mechanical properties of polyester resin fibers can be adjusted by inducing oriented crystallinity. In the manufacture of polyester resin fibers, to adjust the fineness and / or to induce oriented crystallinity and thus adjust mechanical properties, it is sometimes necessary to stretch the polyester resin or polyester resin composition at a high ratio (e.g., more than 2 times).

[0185] However, in the manufacture of polyester resin fibers using polyester resin compositions obtained with conventional chain extenders (modifiers), it is sometimes impossible to stretch the resin composition at a high ratio (e.g., more than 2 times), requiring multiple low-ratio stretching operations. In other words, the existing technology is insufficient from a productivity standpoint, and there is room for further improvement.

[0186] Embodiment 2 was made in view of the above-mentioned problems, and its purpose is to provide a novel manufacturing method for polyester resin fibers that can be manufactured with high productivity even when using a modifier.

[0187] In order to solve the above-mentioned problems, the inventors conducted in-depth research and as a result completed Embodiment 2.

[0188] The method for manufacturing polyester resin fiber according to Embodiment 2 includes: a step (A) of melt-blending polyester resin with a modifier to obtain a polyester resin composition, and a step (B) of stretching the polyester resin composition obtained in the above step (A) at a stretching ratio of 2 times or more.

[0189] According to Embodiment 2, the following effect is achieved: a method for manufacturing polyester resin fibers that can produce polyester resin fibers with high productivity even when using a modifier is provided.

[0190] [2-1. Manufacturing method of polyester resin fiber]

[0191] Another embodiment of the present invention (Embodiment 2) relates to a method for manufacturing polyester resin fibers, comprising: a step (A) of melt-blending a polyester resin with a modifier to obtain a polyester resin composition, and a step (B) of stretching the polyester resin composition obtained in step (A) at a stretching ratio of 2 times or more.

[0192] In this specification, the "method of manufacturing polyester resin fiber according to Embodiment 2" is sometimes referred to as "this manufacturing method 2".

[0193] Because this manufacturing method 2 has the above-described structure, it has the following advantages: polyester resin fibers can be manufactured with high productivity even when a modifier is used, especially in the spinning and stretching processes (process (B)). Furthermore, this manufacturing method 2 also has the following advantages: because the resin composition is stretched at a high ratio (e.g., more than 2 times), the stretching characteristics are excellent, and polyester resin fibers with the desired fineness can be provided. Additionally, this manufacturing method 2 also has the following advantages: because the resin composition is stretched at a high ratio (e.g., more than 2 times), the resulting polyester resin fibers can be imparted with oriented crystallinity, resulting in polyester resin fibers with the desired mechanical properties. Furthermore, when using a polyester resin composition obtained using a conventional chain-extending agent (modifier) ​​to manufacture resin fibers, polyester resin fibers with high shrinkage rates can be obtained even with low stretching ratios. However, in the preferred embodiment of manufacturing method 2, there is also the advantage that, even when the resin composition is stretched at a high ratio (e.g., more than 2 times), polyester resin fibers with a low shrinkage rate (e.g., having the same shrinkage rate as polyester resin fibers obtained using virgin polyester resin) can be provided. Furthermore, in the preferred embodiment of manufacturing method 2, there is also the advantage that a polyester resin fiber with the same physical properties (e.g., heat shrinkage rate, maximum elongation, elongation at break, and Young's modulus) as polyester resin fibers obtained using virgin polyester resin can be provided.

[0194] Hereinafter, Embodiment 2 will be described, and except for the matters detailed below, the description of [1. Embodiment 1] may be appropriately cited. Hereinafter, regarding Embodiment 2, the raw materials (polyester resin and modifier, etc.) will be described first, and then the specific process will be described.

[0195] [Polyester-based resins]

[0196] The polyester resin used in this manufacturing method 2 is not particularly limited, and can be, for example, a polyester resin that is commonly used as a raw material for polyester resin fibers.

[0197] The polyester resin used in this manufacturing method 2 can be the same as the polyester resin used in Embodiment 1, i.e., this manufacturing method 1. The specific manner in which the polyester resin used in this manufacturing method 2 is used can also be the same as the specific manner in which the polyester resin used in Embodiment 1, i.e., this manufacturing method 1, is used. The preferred manner in which the polyester resin used in this manufacturing method 2 is used can also be found in the description of the [Polyester Resin] section of [1. Embodiment 1] above.

[0198] The inventors attempted to manufacture polyester resin fibers using resin compositions containing conventional viscosity modifiers, and independently discovered the following problem: sometimes it is impossible to stretch the melt-blended resin composition at a high ratio (e.g., more than 2 times). That is, there is a tendency that resin compositions obtained by melt-blending conventional viscosity modifiers and recycled polyester resins cannot be used to manufacture polyester resin fibers with high productivity.

[0199] However, the modifier used in this manufacturing method 2 (in other words, the modifier involved in Embodiment 2) has the following advantages: by melt-blending with recycled polyester resin, the melt viscosity of the recycled polyester resin can be increased, providing a resin composition with high melt viscosity, and stretching of the obtained resin composition at a high ratio (e.g., more than 2 times). Furthermore, surprisingly, the resin composition obtained by mixing the modifier involved in Embodiment 2 with recycled polyester resin also has the advantage of being reusable, particularly as long fibers (filament fibers). Therefore, this manufacturing method 2 can provide highly productive polyester resin fibers (particularly long fibers) even when using recycled polyester resin, especially recycled polyester resin obtained from the regeneration of polyester resin fibers. That is, this manufacturing method 2 has the advantage of being able to regenerate horizontally. Therefore, the polyester resin used as a raw material in this manufacturing method 2 can be derived from waste polyester resin fibers. That is, the polyester resin composition in (Ai) and (Aii) above can be a polyester resin composition for polyester resin fibers, and the polyester resin molded body can be a polyester resin fiber.

[0200] The polyester resin used in this manufacturing method 2 preferably includes a polyester resin with a melt viscosity (IV value) of 0.45 or more and 0.75 or less, and more preferably a polyester resin with a melt viscosity (IV value) of 0.45 or more and 0.75 or less (composed only of a polyester resin with a melt viscosity (IV value) of 0.45 or more and 0.75 or less).

[0201] [Modifier]

[0202] The modifier used in this manufacturing method 2 is not particularly limited as long as it is a reagent capable of altering the physical properties of the polyester resin used as a raw material (e.g., increasing melt viscosity). In other words, the modifier used in this manufacturing method is not particularly limited as long as it is a reagent capable of obtaining a polyester resin composition in step (A) that has physical properties different from those of the raw polyester resin (e.g., a higher melt viscosity than the raw polyester resin).

[0203] The modifier used in this manufacturing method 2 can be the same as the modifier used in Embodiment 1, i.e., this manufacturing method 1. The specific methods relating to the modifier used in this manufacturing method 2 can also be the same as those relating to the modifier used in Embodiment 1, i.e., this manufacturing method 1. The preferred methods relating to the modifier used in this manufacturing method 2 can also be the same as those relating to the modifier used in Embodiment 1, i.e., this manufacturing method 1. The specific methods relating to the modifier used in this manufacturing method 2 can also refer to the description in the [Modifier] section of [1. Embodiment 1] above.

[0204] The content of reactive functional group units in polymer (A) is not particularly limited and can be within the numerical range described in the section on (polymer (A)) of the [modifier] in [Embodiment 1] above. As long as the content of reactive functional group units in polymer (A) is within the above range, the modifier can effectively improve the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the polyester resin composition in process (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity; and (ii) the polyester resin fibers have better formability and strength.

[0205] The content of epoxy-containing units in polymer (A) is not particularly limited and can be within the numerical range described in the section on (polymer (A)) of [modifier] in [1. Embodiment 1] above. As long as the content of epoxy-containing units in polymer (A) is within the above range, the modifier can be more effective in improving the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the polyester resin composition in step (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity, and (ii) the formability and strength of the polyester resin fibers are further improved.

[0206] The content of (meth)acrylic acid units without reactive functional groups in polymer (A) is not particularly limited and can be within the numerical range described in the section on (polymer (A)) of [modifier] in [1. Embodiment 1] above. As long as the content of (meth)acrylic acid units without reactive functional groups in polymer (A) is within the above range, the dispersibility of the modifier in step (A) is improved. Furthermore, as long as the content of (meth)acrylic acid units without reactive functional groups in polymer (A) is within the above range, by restricting the branched structure during crosslinking to fewer directions, the elongation of the resin (resin composition) in the subsequent step (B) can be homogenized. As a result, the modifier can effectively improve the melt viscosity of the resin composition without impairing processability. As a result, there are the following advantages: (i) the polyester resin composition in step (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity, and (ii) the polyester resin fibers have better formability and strength.

[0207] The total content of units without reactive functional groups in polymer (A) is not particularly limited and can be within the numerical range described in the section on [modifier] (polymer (A)] of [1. Embodiment 1] above. As long as the total content of units without reactive functional groups in polymer (A) is within the above range, the dispersibility of the modifier in step (A) is improved, and therefore the modifier has a good effect on improving the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the polyester resin composition in step (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity, and (ii) the polyester resin fibers have better formability and strength.

[0208] When the number average content of reactive functional groups in polymer (A) is below a certain amount, the branching degree of the structural units from the polyester resin in the resin composition obtained in step (A) will not be too high, and the entanglement of the structural units from the polyester resin will be suppressed. Therefore, there is no need to worry about the resin composition being too rigid. As a result, in the subsequent step (B), there is no need to worry about the resin composition breaking due to the stress applied during stretching, resulting in filament breakage. That is, by setting the number average content of reactive functional groups in polymer (A) below a certain amount, it is advantageous to improve the stability in the manufacture of polyester resin fibers and to manufacture polyester resin fibers more stably. From this point of view, each molecule of polymer (A) preferably has 10 or less, more preferably 9 or less, more preferably 8 or less, further preferably 7 or less, and particularly preferably 6 or less reactive functional groups on average. Furthermore, when the upper and lower limits of the content (number average) of reactive functional groups per molecule of polymer (A) are both within the above-mentioned preferred range, the melt viscosity of the resin composition can be appropriately increased without causing gelation and without impairing the mechanical properties, heat resistance, rheological properties, etc. of the polyester resin fiber.

[0209] The number-average molecular weight of polymer (A) is not particularly limited, but is preferably within the range described in the section on [modifier] (polymer (A)] of [1. Embodiment 1] above. When the number-average molecular weight of polymer (A) is within the above-mentioned preferred range, the modifier has a good effect on increasing the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the polyester resin composition in step (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity, and (ii) the polyester resin fibers have better formability and strength. In addition, when the number-average molecular weight of polymer (A) is within the above-mentioned preferred range, it also has the advantage of a good balance between the thermal stability of the modifier and productivity.

[0210] The weight-average molecular weight of the modifier is not particularly limited, but is preferably within the range of values ​​described in the section on "Modifier" (physical properties of the modifier) ​​of [1. Embodiment 1] above. Using this configuration, the modifier can better improve the melt viscosity of the resin composition. As a result, there are the following advantages: (i) the polyester resin composition in step (B) has higher tensile strength, enabling the production of polyester resin fibers with high productivity; and (ii) the formability and strength of the polyester resin fibers are further improved.

[0211] [Process (A)]

[0212] In step (A), a raw material comprising at least a polyester resin and a modifier, and further comprising any resin other than a polyester resin and / or other additives, is melt-blended. Step (A) may also be referred to as the step of reacting the polyester resin with the modifier.

[0213] Step (A) in this manufacturing method 2 can also be the same as step 1 in Embodiment 1, i.e., manufacturing method 1. The specific manner related to step (A) in this manufacturing method 2 can also be the same as the specific manner related to step 1 in Embodiment 1, i.e., manufacturing method 1. The preferred manner related to step (A) in this manufacturing method 2 can also be the same as the preferred manner related to step 1 in Embodiment 1, i.e., manufacturing method 1. The specific manner related to step (A) in this manufacturing method 2 can also refer to the description of [Step 1] in [1. Embodiment 1] above.

[0214] The resin composition obtained through step (A) can be identical to that of virgin polyester resin in terms of physical properties other than melt viscosity (IV value) and MFR, such as heat shrinkage after stretching. Here, for example, the resin composition obtained in step (A) can be a resin composition that satisfies the following requirement (1), a resin composition that satisfies the following requirement (2), or a resin composition that satisfies both requirements (1) and (2):

[0215] (1) The polyester resin fiber obtained by stretching the above polyester resin composition under a stretching ratio of 2 times has a heat shrinkage rate of less than 2.0% at 180°C and a heat shrinkage rate of less than 3.0% at 200°C.

[0216] (2) The polyester resin fiber formed by stretching the above polyester resin composition under a stretching ratio of 3 times has a heat shrinkage rate of 10.0% or less at 180°C and a heat shrinkage rate of 12.0% or less at 200°C.

[0217] In the post-processing steps after stretching, polyester fibers are usually reprocessed at high temperatures. Therefore, fibers with high shrinkage rates may exhibit defects due to shrinkage in the subsequent processes. The higher the heat shrinkage rate, the more difficult it is to process into fibers, making them practically unusable. Therefore, the lower the heat shrinkage rate, the wider the range of applications for fiber processing, and the easier it is to handle in various applications. Currently, virgin polyester resins are mostly used in the manufacture of polyester fibers. Consequently, the manufacturing processes for polyester fibers are mostly set based on the shrinkage rate of virgin polyester resins. Therefore, the shrinkage rate of the polyester resin fibers obtained in this manufacturing method 2 is preferably not significantly different from that of virgin polyester resins. "Polyester resin fibers obtained by stretching the polyester resin composition obtained in step (A) at a stretch ratio of 2" or "Polyester resin fibers obtained by stretching the polyester resin composition obtained in step (A) at a stretch ratio of 3" can both be considered as the polyester resin fibers involved in Embodiment 2.

[0218] The polyester resin fiber obtained from the polyester resin composition in step (A) and stretched at a stretch ratio of 2 times has a heat shrinkage rate of 180°C of preferably 2.0% or less, more preferably 1.5% or less, and even more preferably 1.0% or less. With this configuration, the shrinkage rate is suppressed to a low level, thus having the advantage of suppressing quality and production-related defects during fiber reprocessing.

[0219] The polyester resin fiber obtained from the polyester resin composition in step (A) and stretched at a stretch ratio of 2 has a heat shrinkage rate of 3.0% or less at 180°C, more preferably 2.5% or less, even more preferably 2.0% or less, and even more preferably 1.5% or less. With this configuration, the shrinkage rate is suppressed to a low level, thus having the advantage of suppressing quality and production-related defects during fiber reprocessing.

[0220] The polyester resin fiber obtained from the polyester resin composition in step (A) and stretched at a stretch ratio of 3 times has a heat shrinkage rate of 180°C of preferably 10.0% or less, more preferably 9.5% or less, even more preferably 9.0% or less, further preferably 8.5% or less, and particularly preferably 8.0% or less. With this configuration, the shrinkage rate is suppressed to a low level, thus having the advantage of suppressing quality and production-related defects during fiber reprocessing.

[0221] The polyester resin fiber obtained from the polyester resin composition in step (A) and stretched at a stretch ratio of 3 times has a heat shrinkage rate of 12.0% or less at 200°C, more preferably 11.5% or less, even more preferably 11.0% or less, further preferably 10.5% or less, and particularly preferably 10.0% or less. With this configuration, the shrinkage rate is suppressed to a low level, thus having the advantage of suppressing quality and production-related defects during fiber reprocessing.

[0222] [Process (B)]

[0223] This manufacturing method 2 includes a step (B) in which the polyester resin composition obtained in step (A) is stretched at a stretch ratio of 2 times or more. Through step (B), a fibrous polyester resin composition (or polyester resin), i.e., polyester resin fiber, can be obtained.

[0224] As described above, step (A) in manufacturing method 2 can also be the same as step 1 in manufacturing method 1. Therefore, manufacturing method 2 can also include step (B) of stretching the polyester resin composition obtained in step 1 at a stretch ratio of 2 times or more. In this case, fibrous polyester resin composition (or polyester resin), i.e., polyester resin fiber, can also be obtained through step (B).

[0225] In step (B), the method for stretching the polyester resin composition obtained in step (A) is not particularly limited as long as the stretching ratio is 2 times or more. The stretching of the resin composition in step (B) can be performed using known methods of stretching fibers, such as hot stretching with heating. When the above-mentioned hot stretching is used in step (B), known means of heating such as heating rollers, heating plates, steam jet devices, and warm water baths can be used as the heating means for hot stretching, and these means can also be used in appropriate combinations.

[0226] The fineness of the final polyester resin fiber can be adjusted by the stretching conditions, such as the draw ratio, in step (B) described above. Here, the suitable fineness of the polyester resin fiber varies depending on its intended use. Therefore, the suitable stretching conditions in step (B) can be appropriately adjusted according to the intended use of the final polyester resin fiber. It should be noted that the fineness of the final polyester resin fiber can also vary depending on the extrusion conditions in the extrusion step described later and the stretching conditions (e.g., draw ratio) in step (B).

[0227] A higher stretching ratio in step (B) allows for processing under a wider range of conditions in subsequent steps, thus broadening the product selection. Therefore, the stretching ratio in step (B) is preferably greater than 2 times, and more preferably greater than 3 times.

[0228] The smaller the stretching ratio in step (B), the higher the production volume and the better the productivity in the stretching process. Therefore, the stretching ratio in step (B) is preferably less than 4 times, and more preferably less than 3 times.

[0229] [Cooling process, cutting process, and drying process]

[0230] In this manufacturing method 2, a cooling step may be further included after step (A) to cool the melt-mixed resin composition obtained in step (A). In step (A), for example, the melt-mixed resin composition is extruded in a linear fashion from a die provided with a mixing mill. In the cooling step, for example, the melt-mixed resin composition extruded in a linear fashion from the die provided with a mixing mill is passed through a water tank, thereby cooling the melt-mixed resin composition in the water tank (water cooling).

[0231] After step (A) or the cooling step, a cutting step of cutting the resin composition may be further included. In the cutting step, the linear resin composition is cut into any shape (e.g., particle or granular shape).

[0232] This manufacturing method 2 may further include a drying step of drying the resin composition (e.g., a resin composition in granular shape after a cutting process).

[0233] When this manufacturing method 2 further includes a cooling step and / or a drying step after step (A), the resin composition can be melted before step (B). Step (B) can also be a step of stretching the molten resin composition obtained by melting the resin composition obtained after the cooling step and / or drying step by more than 2 times.

[0234] In this manufacturing method 2, the resin composition can be melted using apparatus such as a single-spindle extruder and a twin-spindle extruder. In this manufacturing method 2, the resin composition is melted by heating it to, for example, 240°C or higher and 270°C or lower, 270°C or higher and 300°C or lower, or 300°C or higher and 320°C or lower.

[0235] [Dispensing process]

[0236] This manufacturing method 2 may further include an ejection step before step (B) in which the molten resin composition is ejected from a perforated nozzle. The ejection step may be performed between step (A) and step (B), for example, it may be a step in which a molten compound of the resin composition obtained in step (A) is ejected from the nozzle. The ejection step may be performed between step (B) and a cooling and / or drying step performed after step (A), for example, it may be a step in which a molten resin composition obtained by melting the resin composition obtained after the cooling and / or drying steps is ejected from the nozzle. When this manufacturing method 2 further includes an ejection step, the stretching step can be combined with the ejection step, thereby providing the advantage of excellent productivity.

[0237] When this manufacturing method 2 further includes an ejection step after step (A), step (B) may also be a step of stretching the resin composition ejected from the nozzle in the ejection step to more than twice its original size.

[0238] The nozzle used in the ejection process of manufacturing method 2 can be the same as the nozzle used in the ejection process of embodiment 1, i.e., manufacturing method 1. The specific configuration of the nozzle used in the ejection process of manufacturing method 2 can also be the same as the specific configuration of the nozzle used in the ejection process of embodiment 1, i.e., manufacturing method 1. The preferred configuration of the nozzle used in the ejection process of manufacturing method 2 can also be the same as the preferred configuration of the nozzle used in the ejection process of embodiment 1, i.e., manufacturing method 1. The specific configuration of the nozzle used in the ejection process of manufacturing method 2 can also refer to the description in the (ejection process) section of [1. Embodiment 1] above.

[0239] [Winding process]

[0240] This manufacturing method 2 may further include a winding step for winding the resin composition before the aforementioned step (B). The winding step may be performed between step (A) and step (B), for example, it may be a step for winding the melt-mixed resin composition obtained in step (A). The winding step may be performed between a cooling step and / or a drying step performed after step (A) and step (B), for example, it may be a step for winding the molten resin composition obtained by melting the resin composition obtained after the cooling step and / or drying step. The winding step may be performed between a discharge step performed after step (A) and step (B), for example, it may be a step for winding the resin composition discharged from the nozzle in the discharge step.

[0241] In the winding process, there is no particular limitation on the method of winding the polyester resin composition. Whether it is POY (Partially Oriented Yarn) or FDY (Fully Drawn Yarn), the well-known winding method commonly used in the manufacture of polyester resin fibers can be adopted.

[0242] There is no particular limitation on the winding speed of the polyester resin composition in the winding process. The higher the winding speed, the greater the amount of polyester resin composition wound per unit time, that is, the greater the amount of polyester resin fiber produced. Therefore, the winding speed is preferably 200 m / min or more, more preferably 300 m / min or more, and even more preferably 400 m / min or more.

[0243] When this manufacturing method 2 further includes a winding process after step (A), step (B) may also be a process of stretching the resin composition wound in the winding process to more than twice its original length.

[0244] The polyester resin fibers obtained in step (B) can be long fibers. "Long fibers" are sometimes also called "filaments" or "filament / fibers". In other words, step (B) can also be called the step of processing the polyester resin composition into long fibers.

[0245] By cutting the long fibers of the polyester resin fiber obtained in process (B), short fibers of polyester resin fiber can be manufactured. "Short fiber" is sometimes also called "short fiber" or "short fiber / fiber".

[0246] Short fibers of polyester resin fibers can be manufactured by curling and cutting the polyester resin fibers obtained in process (B).

[0247] There are no particular limitations on the crimping method for polyester resin fibers; any crimping method commonly used in the manufacture of polyester resin fibers can be employed. Known devices such as gear crimping machines, embossing rollers, and stuffing box crimping machines can be used for crimping polyester resin fibers.

[0248] The winding process in this manufacturing method 2 can be the same as process 1 in Embodiment 1, i.e., manufacturing method 1. The specific manner of the winding process in this manufacturing method 2 can also be the same as the specific manner of process 1 in Embodiment 1, i.e., manufacturing method 1. The preferred manner of the winding process in this manufacturing method 2 can also be the same as the preferred manner of process 1 in Embodiment 1, i.e., manufacturing method 1. The specific manner of the winding process in this manufacturing method 2 can also refer to the description in the [Process 1] section of [1. Embodiment 1] above.

[0249] In one embodiment of the present invention, step 1 or step (A) may be performed, followed by step 2, and then step (B).

[0250] [3. Physical properties of polyester resin fibers]

[0251] The polyester resin fibers manufactured by both manufacturing methods 1 and 2 have the following advantages: they possess the same physical properties (e.g., heat shrinkage, maximum elongation, elongation at break, and Young's modulus) as polyester resin fibers obtained using virgin polyester resin. In this specification, the methods for determining the heat shrinkage, maximum elongation, elongation at break, and Young's modulus of the polyester resin fibers are not particularly limited, and the methods described in the examples can be used. The polyester resin fibers manufactured by manufacturing methods 1 and 2 also constitute an embodiment of this invention.

[0252] [4. Applications]

[0253] According to Method 1 and Method 2, the following advantages are available: even when a modifier is used, a method for manufacturing polyester resin fibers with high productivity can be provided. Therefore, Method 1 and Method 2 are applicable to the field of polyester resin fibers, particularly recycled polyester resin fibers using recycled polyester resin. Furthermore, the polyester resin fibers obtained using Method 1 and Method 2 are suitable for various applications such as clothing and interior decoration.

[0254] One embodiment of the present invention may be configured as shown in [1] to

[19] .

[0255] [1] A method for manufacturing polyester resin fiber, comprising:

[0256] Step 1: Polyester resin and modifier are melt-blended to obtain a polyester resin composition;

[0257] Step 2 involves winding the polyester resin composition obtained in Step 1 at a winding speed of 400 m / min or higher.

[0258] [2] The method for manufacturing polyester resin fiber according to [1] further includes step (B), in which the polyester resin composition obtained in step 1 is stretched at a stretching ratio of more than 2 times.

[0259] [3] The method for manufacturing polyester resin fibers according to [1] further includes a stretching step, wherein the polyester resin fibers obtained in step 2 are stretched.

[0260] [4] A method for manufacturing polyester resin fiber according to any one of [1] to [3], wherein the polyester resin is polyethylene terephthalate (PET).

[0261] [5] A method for manufacturing polyester resin fiber according to any one of [1] to [4], wherein the modifier comprises polymer (A), which comprises units containing reactive functional groups and units not containing reactive functional groups.

[0262] [6] The method for manufacturing polyester resin fibers according to [5], wherein the modifier further comprises polymer (B).

[0263] [7] The method for manufacturing polyester resin fibers according to [6], wherein the epoxy equivalent of the polymer (B) is 6000 g / eq or more and 50000 g / eq or less.

[0264] [8] The method for manufacturing polyester resin fibers according to [6] or [7], wherein the polymer (B) contains more than 2.5% by weight and less than 10.0% by weight of units containing reactive functional groups per 100% by weight of the polymer (B).

[0265] [9] The method for manufacturing polyester resin fiber according to [8], wherein the polymer (B) comprises glycidyl methacrylate unit as the unit containing the reactive functional group.

[0266]

[10] A method for manufacturing polyester resin fiber according to any one of [6] to

[11] , wherein the modifier comprises, in 100% by weight, 15% or more and 70% or less of the polymer (A) and 30% or more and 85% or less of the polymer (B).

[0267]

[11] A method for manufacturing polyester resin fiber according to any one of [6] to

[10] , wherein the modifier comprises, in 100% by weight, 50% or more and 90% or less of the polymer (A) and 10% or more and 50% or less of the polymer (B).

[0268]

[12] A method for manufacturing polyester resin fibers according to any one of [5] to

[11] , wherein each molecule of the polymer (A) has an average of 2 or more and 10 or less reactive functional groups.

[0269]

[13] A method for manufacturing polyester resin fiber according to any one of [1] to

[12] , wherein the weight average molecular weight of the modifier is 20,000 Da or more and less than 200,000 Da.

[0270]

[14] A method for manufacturing polyester resin fibers according to any one of [5] to

[12] , wherein the number average molecular weight of the polymer (A) is less than 10,000 Da.

[0271]

[15] A method for manufacturing polyester resin fibers according to any one of [5] to

[12] and

[14] , wherein the polydispersity index of the polymer (A) is 2.0 or more and 10.0 or less.

[0272]

[16] A method for manufacturing polyester resin fibers according to any one of [5] to

[12] ,

[14] and

[15] , wherein, in the polymer (A),

[0273] (i) As the aforementioned unit containing reactive functional groups, it comprises (meth)acrylate units containing epoxy groups, and,

[0274] (ii) As the above-mentioned unit without reactive functional groups, it includes one or more structural units selected from styrene-based units without reactive functional groups and (meth)acrylic-based units without reactive functional groups.

[0275]

[17] A method for manufacturing polyester resin fibers according to any one of [6] to

[11] , wherein the polymer (B) comprises one or more structural units selected from styrene units and (meth)acrylic units.

[0276]

[18] A method for manufacturing polyester resin fibers according to any one of [6] to

[11] and

[17] , wherein the weight-average molecular weight of the polymer (B) is 80,000 Da or more and 500,000 Da or less.

[0277]

[19] A method for manufacturing polyester resin fiber according to any one of [1] to

[18] , wherein the modifier has less than 50 ppm of monomer residue containing reactive functional groups and less than 100 ppm of total monomer residue based on the weight of the modifier.

[0278] One embodiment of the present invention may be configured as shown in [1'] to [18'].

[0279] [1'] A method for manufacturing polyester resin fiber, comprising:

[0280] Step 1: Polyester resin and modifier are melt-blended to obtain a polyester resin composition;

[0281] Step 2 involves winding the polyester resin composition obtained in Step 1 at a winding speed of 400 m / min or higher.

[0282] [2'] The method for manufacturing polyester resin fibers according to [1'] further includes a stretching step, wherein the polyester resin fibers obtained in step 2 are stretched.

[0283] [3'] The method for manufacturing polyester resin fiber according to [1'] or [2'], wherein the polyester resin is polyethylene terephthalate (PET).

[0284] [4'] A method for manufacturing polyester resin fiber according to any one of [1'] to [3'], wherein the modifier comprises a polymer (A), which comprises units containing reactive functional groups and units not containing reactive functional groups.

[0285] [5'] The method for manufacturing polyester resin fibers according to [4'], wherein the modifier further comprises polymer (B).

[0286] [6'] In the method for manufacturing polyester resin fiber according to [5'], the epoxy equivalent of the polymer (B) is 6000 g / eq or more and 50000 g / eq or less.

[0287] [7'] The method for manufacturing polyester resin fibers according to [5'] or [6'], wherein the polymer (B) contains more than 2.5% by weight and less than 10.0% by weight of units containing reactive functional groups per 100% by weight of the polymer (B).

[0288] [8'] The method for manufacturing polyester resin fiber according to [7'], wherein the polymer (B) comprises glycidyl methacrylate unit as the unit containing the reactive functional group.

[0289] [9] A method for manufacturing polyester resin fiber according to any one of [5] to [8], wherein the modifier comprises, in 100% by weight, 15% or more and 70% or less of the polymer (A) and 30% or more and 85% or less of the polymer (B).

[0290] [10'] A method for manufacturing polyester resin fiber according to any one of [5'] to [9'], wherein the modifier comprises, in 100% by weight, 50% or more and 90% or less of the polymer (A) and 10% or more and 50% or less of the polymer (B).

[0291] [11'] A method for manufacturing polyester resin fibers according to any one of [4'] to [10'], wherein each molecule of the polymer (A) has an average of 2 or more and 10 or less reactive functional groups.

[0292] [12'] A method for manufacturing polyester resin fiber according to any one of [1'] to [11'], wherein the weight-average molecular weight of the modifier is 20,000 Da or more and less than 200,000 Da.

[0293] [13'] A method for manufacturing polyester resin fibers according to any one of [4'] to [12'], wherein the number average molecular weight of the polymer (A) is less than 10,000 Da.

[0294] [14'] A method for manufacturing polyester resin fibers according to any one of [4'] to [13'], wherein the polydispersity index of the polymer (A) is 2.0 or more and 10.0 or less.

[0295] [15'] A method for manufacturing polyester resin fibers according to any one of [4'] to [14'], wherein, in the polymer (A) described above,

[0296] (i) As the aforementioned unit containing reactive functional groups, it comprises (meth)acrylate units containing epoxy groups, and,

[0297] (ii) As the above-mentioned unit without reactive functional groups, it includes one or more structural units selected from styrene-based units without reactive functional groups and (meth)acrylic-based units without reactive functional groups.

[0298] [16'] A method for manufacturing polyester resin fibers according to any one of [5'] to [10'], wherein the polymer (B) comprises one or more structural units selected from styrene units and (meth)acrylic units.

[0299] [17'] A method for manufacturing polyester resin fiber according to any one of [5'] to [10'], wherein the weight-average molecular weight of the polymer (B) is 80,000 Da or more and 500,000 Da or less.

[0300] [18'] A method for manufacturing polyester resin fiber according to any one of [1'] to [17'], wherein the modifier has less than 50 ppm of monomer residue containing reactive functional groups and less than 100 ppm of total monomer residue based on the weight of the modifier.

[0301] One embodiment of the present invention may be configured as shown in [1´´] to [19´´].

[0302] [1´´] A method for manufacturing polyester resin fiber, comprising: step (A), melt-blending polyester resin with a modifier to obtain a polyester resin composition; step (B), stretching the polyester resin composition obtained in step (A) at a stretching ratio of more than 2 times.

[0303] [2] The method for manufacturing polyester resin fiber according to [1], wherein the polyester resin is polyethylene terephthalate (PET).

[0304] [3] The method for manufacturing polyester resin fibers according to [1] or [2], wherein the polyester resin comprises a polyester resin with a melt viscosity (IV value) of 0.45 or more and 0.75 or less.

[0305] [4''] A method for manufacturing polyester resin fibers according to any one of [1''] to [3''], wherein the polyester resin composition obtained in step (A) satisfies the following requirements (1) and (2):

[0306] (1) The polyester resin fiber obtained by stretching the above polyester resin composition under a stretching ratio of 2 times has a heat shrinkage rate of less than 2.0% at 180°C and a heat shrinkage rate of less than 3.0% at 200°C.

[0307] (2) The polyester resin fiber formed by stretching the above polyester resin composition under a stretching ratio of 3 times has a heat shrinkage rate of 10.0% or less at 180°C and a heat shrinkage rate of 12.0% or less at 200°C.

[0308] [5] A method for manufacturing polyester resin fiber according to any one of [1] to [4], wherein the modifier comprises a polymer (A) comprising units containing reactive functional groups and units not containing reactive functional groups.

[0309] [6´´] The method for manufacturing polyester resin fibers according to [5´´], wherein the modifier further comprises polymer (B).

[0310] [7] The method for manufacturing polyester resin fibers according to [6], wherein the epoxy equivalent of the polymer (B) is 6000 g / eq or more and 50000 g / eq or less.

[0311] [8] The method for manufacturing polyester resin fibers according to [6] or [7], wherein the polymer (B) contains more than 2.5% and less than 10.0% by weight of units containing reactive functional groups per 100% by weight of the polymer (B).

[0312] [9] According to the method for manufacturing polyester resin fiber described in [8], wherein the polymer (B) comprises glycidyl methacrylate unit as the unit containing the reactive functional group.

[0313]

[10] A method for manufacturing polyester resin fiber according to any one of [6] to [9], wherein the modifier comprises, in 100% by weight, 15% or more and 70% or less of the polymer (A) and 30% or more and 85% or less of the polymer (B).

[0314] [11´´] A method for manufacturing polyester resin fiber according to any one of [6´´] to [10´´], wherein the modifier comprises, in 100% by weight, 50% or more and 90% or less of the polymer (A) and 10% or more and 50% or less of the polymer (B).

[0315] [12´´] A method for manufacturing polyester resin fibers according to any one of [5´´] to [11´´], wherein each molecule of the polymer (A) has an average of 2 or more and 10 or less reactive functional groups.

[0316] [13´´] A method for manufacturing polyester resin fiber according to any one of [1´´] to [12´´], wherein the weight-average molecular weight of the modifier is 20,000 Da or more and less than 200,000 Da.

[0317]

[14] A method for manufacturing polyester resin fiber according to any one of [5] to

[13] , wherein the number average molecular weight of the polymer (A) is less than 10,000 Da.

[0318]

[15] A method for manufacturing polyester resin fiber according to any one of [5] to

[14] , wherein the polydispersity index of the polymer (A) is 2.0 or more and 10.0 or less.

[0319] [16´´] A method for manufacturing polyester resin fibers according to any one of [5´´] to [15´´], wherein, in the polymer (A) above,

[0320] (i) As the aforementioned unit containing reactive functional groups, it comprises (meth)acrylate units containing epoxy groups, and,

[0321] (ii) As the above-mentioned unit without reactive functional groups, it includes one or more structural units selected from styrene-based units without reactive functional groups and (meth)acrylic-based units without reactive functional groups.

[0322] [17´´] A method for manufacturing polyester resin fibers according to any one of [6´´] to [11´´], wherein the polymer (B) comprises one or more structural units selected from styrene-based units and (meth)acrylic-based units.

[0323]

[18] A method for manufacturing polyester resin fiber according to any one of [6] to

[11] , wherein the weight-average molecular weight of the polymer (B) is 80,000 Da or more and 500,000 Da or less.

[0324]

[19] A method for manufacturing polyester resin fiber according to any one of [1] to

[18] , wherein the modifier has less than 50 ppm of monomer residue containing reactive functional groups and less than 100 ppm of total monomer residue, based on the weight of the modifier.

[0325] Example

[0326] The present invention will be described in more detail with reference to the embodiments and comparative examples shown below, but the present invention is not limited thereto. Embodiments obtained by appropriately combining the technical means disclosed in the various embodiments are also included within the scope of the present invention.

[0327] [Measurement and Evaluation Methods]

[0328] 1. Particle size of the complex

[0329] The particle size of the polymer or composite was determined using a Microtrac UPA (manufactured by Nikkiso Corporation) and obtained by calculating the volume average particle size.

[0330] 2. Polymerization conversion rate

[0331] The polymerization conversion rate is set as the ratio (%) of the actual solids content to the solids content at the ideal conversion rate.

[0332] 3. Number-average molecular weight and weight-average molecular weight

[0333] The number-average and weight-average molecular weights of polymer (A), polymer (B), and the weight-average molecular weight of the modifier were calculated by GPC determination. A Tosoh apparatus was used for the GPC. The analytical conditions are as follows.

[0334] Column 1 (Low Molecular Weight Column)

[0335] First pillar: TSKgel SuperH5000

[0336] Second column: TSKgel SuperH4000

[0337] Third column: TSKgel SuperH3000

[0338] Fourth column: TSKgel SuperH2000

[0339] Column 2 (Polymer Column)

[0340] First column: TSKgel SuperHZM-H

[0341] Second column: TSKgel SuperHZM-H

[0342] Sample introduction method: syringe metering

[0343] Injection loop capacity: 100 μL

[0344] Pre-introduction amount: 150 μL

[0345] Air capacity: 3.5μL

[0346] Automatic cleaning capacity: 1.0mL

[0347] syringe speed

[0348] Sampling rate: 10 μL / s

[0349] Cleaning speed: 100 μL / s

[0350] Metering rate: 5 μL / s

[0351] Sample flow rate: 0.350 mL / min

[0352] Reference flow rate ratio: equal multiple

[0353] Flow rate control: Ineffective

[0354] Flow rate increase: 0.35 mL / min

[0355] Flow rate reduction: 0.35 mL / min

[0356] Pressure limit

[0357] Column 1

[0358] Upper limit of sample pressure: 12.0 MPa

[0359] Lower limit of sample pressure: 0.2 MPa

[0360] Upper limit of reference pressure: 25.0 MPa

[0361] Lower limit of reference pressure: 0.2 MPa

[0362] Column 2

[0363] Upper limit of sample pressure: 25.0 MPa

[0364] Lower limit of sample pressure: 0.2 MPa

[0365] Upper limit of reference pressure: 12.0 MPa

[0366] Lower limit of reference pressure: 0.2 MPa

[0367] flow

[0368] Column 1

[0369] Sample flow rate: 0.600 mL / min

[0370] Reference flow rate ratio: 1 / 2

[0371] Column 2

[0372] Sample flow rate: 0.350 mL / min

[0373] Reference flow rate ratio: equal multiple

[0374] Flow rate control: Ineffective

[0375] Flow rate increase: 0.35 mL / min / min

[0376] Flow rate reduction rate: 0.35 mL / min / min

[0377] Pressure limit

[0378] Column 1

[0379] Upper limit of sample pressure: 12.0 MPa

[0380] Lower limit of sample pressure: 0.2 MPa

[0381] Upper limit of reference pressure: 25.0 MPa

[0382] Lower limit of reference pressure: 0.2 MPa

[0383] Peak detection conditions

[0384] RI

[0385] Detection sensitivity (front side): 3.000 mV / min

[0386] Detection sensitivity (back side): 3.000 mV / min

[0387] Baseline determination value: 1.000 mV / min

[0388] Exclusion area: 10.000mVs

[0389] Exclusion height: 0.000mV

[0390] Excluding half-peak width: 0.000s

[0391] UV / EXT

[0392] Detection sensitivity (front side): 3.000 mV / min

[0393] Detection sensitivity (back side): 3.000 mV / min

[0394] Baseline determination value: 1.000 mV / min

[0395] Exclusion area: 10.000mVs

[0396] Exclusion height: 0.000mV

[0397] Excluding half-peak width: 0.000s

[0398] It should be noted that polystyrene was used as the reference material. Specifically, GPC was performed on polystyrene with known number-average and weight-average molecular weights under the conditions described above to obtain a standard curve. Then, GPC was performed on the samples (polymer (A), polymer (B), and modifier) ​​under the conditions described above, and the number-average and weight-average molecular weights of each sample were calculated based on the standard curve. It should be noted that the number-average and weight-average molecular weights of the modifier were calculated using volumetric calculations based on the GPC measurements described above.

[0399] 4. Epoxy equivalent and epoxy group content

[0400] The epoxy equivalent of the modifier was determined according to JIS K7236:2001. Specifically, the modifier was accurately weighed and dissolved in chloroform. Acetic acid and tetraethylammonium acetate solution were added to the resulting solution. The resulting solution was used as a sample and titrated using a 0.1 mol / L perchloric acid-acetic acid standard solution. During the potentiometric titration, as the perchloric acid-acetic acid standard solution was added, perchloric acid reacted with tetraethylammonium bromide to generate hydrogen bromide. The generated hydrogen bromide reacted with epoxy groups. The endpoint was set when all epoxy groups had reacted and hydrogen bromide was in excess. The epoxy equivalent (g / eq) of the modifier was calculated using this potentiometric titration. In addition, relative to the determined epoxy equivalent (g / eq) of the modifier, and based on the proportion (concentration) of the epoxy-containing monomer relative to all monomers used in the manufacture of each polymer (A) and (B), the number of epoxy groups per molecule of each polymer (A) and (B) (average number) is calculated. Based on the number-average molecular weight (Mn) of each polymer (A) and (B) and the following formula, the epoxy equivalent (g / eq) of each polymer (A) and (B) is calculated.

[0401] The epoxy equivalent of a polymer (g / eq) = the number average molecular weight of the polymer (Mn) / the number of epoxy groups per molecule of the polymer (average number).

[0402] 5. Content of monomer residues containing reactive functional groups and total monomer residues.

[0403] Using the modifier as the object, gas chromatography (GC) was performed under the conditions shown below to determine the content of monomer residues containing reactive functional groups and total monomer residues in the modifier. Specifically, 0.1 g and 0.15 g of precisely weighed modifier and a stir bar were added to a 20 ml screw tube. 3 ml of dichloromethane containing an internal standard was added to the screw tube, and the contents of the screw tube were stirred for more than 30 minutes to dissolve the modifier in the dichloromethane to obtain a solution. GC was performed on the obtained solution (sample). Based on the chromatogram obtained by GG, the peak area corresponding to each monomer in the sample and the area corresponding to CB (chlorobenzene) were calculated. The content of each monomer residue was quantified (calculated) using the following formula (1) according to the internal standard method. The total of the monomer residues belonging to the monomer residues containing reactive functional groups in the above monomer residues was taken as the content of monomer residues containing reactive functional groups. In addition, the total content of each monomer residue is taken as the total content of monomer residue.

[0404] Mo concentration (ppm) = (Mo area / CB area) × Mo factor × internal standard (μg) / sample amount (g) ... Equation (1)

[0405] In formula (1), Mo represents the monomer residue containing reactive functional groups and / or total monomer residue as the test object, and the concentration of Mo is the concentration when the solid content of the modifier is set to 100% by weight (unit: ppm).

[0406] (GC determination conditions)

[0407] Apparatus: Gas chromatograph GC-2014 (manufactured by Shimadzu Corporation)

[0408] Column: Capillary column

[0409] Mobile phase: Gas chromatography

[0410] Internal standard: Chlorobenzene (CB)

[0411] Detector: FID

[0412] Area measurement method: internal standard method.

[0413] In the manufacturing examples described below, butyl acrylate (BA), styrene (ST), and glycidyl methacrylate (GMA) were used as monomers. GMA is a monomer containing reactive functional groups. Table 1 below shows the results for each monomer residue of each modifier. In the results for each monomer residue, "N.D." indicates that the monomer (Mo) is below the detection limit (Not Detection), meaning that no peak of the monomer (Mo) was detected. It should be noted that the detection limits for the apparatus used (gas chromatograph GC-2014 (manufactured by Shimadzu Corporation)) are 13.5 ppm for BA, 20.8 ppm for ST, and 9.7 ppm for GMA. The result for each monomer residue, "N.D.", means that BA is less than 13.5 ppm, ST is less than 20.8 ppm, and GMA is less than 9.7 ppm.

[0414] 6. Melt viscosity (IV value) of the resin composition

[0415] The IV value of the resin composition was determined according to JIS K 7367-5. Specifically, the resin composition was dissolved in an equal weight mixture of phenol and tetrachloroethane to prepare a solution with a concentration of 0.5 g / dL, which was then used as the sample. The relative viscosity of the solution at 25°C was measured using an Ubbelohde viscometer, and the intrinsic viscosity was calculated.

[0416] 7. Melt Flow Rate (MFR) of the Resin Composition

[0417] The polyester resin compositions obtained in each example and comparative example were placed in a thermostat at 120°C and dried for 5 hours. The melt flow index (MFR) of the dried resin compositions was measured using a melt flow index tester (manufactured by Yasuda Seiki Co., Ltd.) at a temperature of 270°C and a load of 2.16 kg.

[0418] 8. Fineness

[0419] The fineness (unit: dtex) of the polyester resin fibers was measured using a DC-21 micrometer manufactured by SEARCH Corporation. It should be noted that in this embodiment, the polyester resin fibers may include both unstretched and stretched polyester resin fibers.

[0420] 9. Heat shrinkage rate (heat shrinkage rate at 180℃ and heat shrinkage rate at 200℃)

[0421] The dry heat shrinkage rate of the fibers in the examples and comparative examples was measured as follows. The fibers were cut into lengths L1 (300 mm), and the fibers of length L1 were dried in a dryer at temperatures of 180°C or 200°C for 30 minutes. Then, the length L2 of the fibers dried at each temperature was measured using vernier calipers. The dry heat shrinkage rate was calculated using the following formula:

[0422] Dry heat shrinkage rate (%) = ((L1-L2) / L1) × 100 (%).

[0423] 10. Maximum elongation, elongation at break, and Young's modulus

[0424] The tensile strength and elongation of filaments were determined using an INTESCO Model 201 (manufactured by INTESCO Corporation). The specific steps are as follows: A 40mm long filament was taken and clamped 10mm from both ends with backing paper (thin paper) coated with adhesive double-sided tape. The filament was air-dried overnight to prepare a 20mm long specimen. The specimen was mounted on the testing machine and tested at a temperature of 24°C, humidity below 80%, a load of 1 / 30 gf × denier, and a tensile speed of 20 mm / min. The maximum elongation, elongation at break, and Young's modulus were measured. The test was repeated 10 times under the same conditions, and the average value was taken as the maximum elongation, elongation at break, and Young's modulus of the filament.

[0425] [Material]

[0426] <Polyester Resins>

[0427] Polyester Resin 1: Virgin polyester resin (manufactured by Teijin Corporation, product name: TRN-MTJ, melt flow rate (MFR) = 111.2, melt viscosity (IV value) = 0.53)

[0428] Polyester Resin 2: Virgin polyester resin (manufactured by UNITIKA, product name: MA-2101M, melt flow rate (MFR) = 66.0, melt viscosity (IV value) = 0.62)

[0429] <Modifier>

[0430] Modifier 1: The modifier obtained in Manufacturing Example 1 below

[0431] Modifier 2: The modifier obtained in manufacturing example 2 below.

[0432] Modifiers 1 and 2 are modifiers involved in one embodiment of the present invention.

[0433] [Manufacturing Example]

[0434] <Manufacturing Example 1: Preparation of Modifier 1>

[0435] (Preparation of polymer (A))

[0436] First, add pure water (180 parts by weight), sodium ethoxyalkylated alkyl phosphate (1.5 parts by weight), ethylenediaminetetraacetic acid (EDTA) (0.0075 parts by weight), ferric sulfate hexahydrate (0.3 parts by weight), and tert-butyl hydroperoxide (0.1 parts by weight) to the reactor.

[0437] Then, a monomer mixture (a1) consisting of styrene (ST) (68 parts by weight), a monomer without reactive functional groups, glycidyl methacrylate (GMA) (12 parts by weight), a monomer containing reactive functional groups, and n-octylthiol (1.5 parts by weight), a chain transfer agent, was added to the reactor described above for 150 minutes to obtain mixture (b1). Here, in the monomer mixture (a1), of the total 100% by weight of ST and GMA, ST accounted for 85% by weight and GMA accounted for 15% by weight.

[0438] Next, while stirring the mixture (b1) in the reactor, the temperature of the mixture (b1) was raised to 75°C, and nitrogen bubbling was performed on the mixture (b1) for 30 minutes. After nitrogen bubbling, sodium ethoxyalkylated alkyl phosphate (0.2 parts by weight) and tert-butyl hydroperoxide (0.03 parts by weight) as a polymerization initiator were added to the mixture (b1) in the reactor to obtain mixture (c1).

[0439] Next, the monomers in the mixture (c1) are reacted until the polymerization conversion exceeds 90%, yielding reactant (a1). Then, the temperature of reactant (a1) is lowered to 65°C, and reactant (a1) is placed at 65°C for 30 minutes. Through this operation, polymer (a1) is obtained as polymer (A).

[0440] (Preparation of polymer (B) and modifier 1)

[0441] Next, a monomer mixture (d1) consisting of butyl acrylate (BA) (5 parts by weight), GMA (1 part by weight), and ST (14 parts by weight) is added to the reactor containing the polymer (a1) to obtain a mixture (e1). Here, in the monomer mixture (d1), BA accounts for 25% by weight, GMA accounts for 5% by weight, and ST accounts for 70% by weight out of a total of 100% by weight of BA, GMA, and ST.

[0442] Next, sodium ethoxyalkylated alkyl phosphate (0.2 parts by weight) and tert-butyl hydroperoxide (0.03 parts by weight) as a polymerization initiator were added to the mixture (e1) in the reactor to obtain mixture (f1).

[0443] Next, the monomers in the mixture (f1) are reacted until the reaction rate exceeds 98%, yielding polymer (b1) as polymer (B). As a result, latex 1 comprising a composite 1 consisting of polymer (a1) and polymer (b1) is obtained. Composite 1 can be referred to as a modifier. Polymer (b1) contains 5% by weight of GMA units as reactive functional groups in 100% by weight of polymer (b1).

[0444] The particle size of complex 1 in latex 1 was determined using the method described above, and the result was 1100 Å. Furthermore, in complex 1, polymer (a1) as polymer (A) can be considered as forming the core, and polymer (b1) as polymer (B) can be considered as forming the shell. That is, complex 1 (i.e., the modifier) ​​can be considered to have a core-shell structure. Complex 1 (i.e., the modifier) ​​comprises 80 wt% polymer (a1) and 20 wt% polymer (b1) per 100 wt% of complex 1. The number-average molecular weight and weight-average molecular weight of complex 1 were determined using the method described above. As a result, complex 1 has two number-average molecular weights (Mn): polymer (a1) has a number-average molecular weight of 9000 Da, and polymer (b1) has a number-average molecular weight of 13000 Da. Additionally, complex 1 has two weight-average molecular weights (Mw): polymer (a1) has a weight-average molecular weight of 50000 Da, and polymer (b1) has a weight-average molecular weight of 120000 Da. The weight-average molecular weight of complex 1 (i.e., the modifier) ​​is 55,000 Da. Furthermore, the polydispersity index (PMI) of polymer (a1) is 3.0, and that of complex 1 is 4.0. The average number of reactive functional groups per molecule of polymer (a1) is 7, that of polymer (b1) is 3, and that of complex 1 is 6. The epoxy equivalent of polymer (a1) is 1500 g / eq, and that of polymer (b1) is 8400 g / eq.

[0445] To recover compound 1 as a powder from latex 1, the obtained latex 1 was rapidly added to a 5% calcium chloride aqueous solution while stirring, resulting in a mixture (g1). The mixture (g1) was heated to 70°C using steam heating and maintained at 70°C. Next, the temperature of the mixture (g1) was increased to 85°C, forming an aggregate of compound 1. The mixture (g1) was then dehydrated, yielding the aggregate of compound 1 from the mixture (g1). The obtained aggregate of compound 1 was dried to obtain a powder of compound 1. The powder of compound 1 was then sieved through an 18-mesh sieve, yielding a white powder that passed through the 18-mesh sieve. Hereinafter, the obtained white powder is referred to as "modifier 1".

[0446] <Manufacturing Example 2: Preparation of Modifier 2>

[0447] (Preparation of polymer (A))

[0448] Except for the items shown below (i), perform the same operations as described in the (Preparation of Polymer (A)) column of Manufacturing Example 1 to prepare polymer (a2) as polymer (A).

[0449] (i) Instead of monomer mixture (a1), monomer mixture (a2) is used, which is a mixture of ST (56 parts by weight), GMA (24 parts by weight) and n-octylthiol (1.9 parts by weight). Here, in the monomer mixture (a2) above, ST accounts for 70% by weight and GMA accounts for 30% by weight out of a total of 100% by weight of ST and GMA.

[0450] (Preparation of polymer (B) and modifier 2)

[0451] Instead of the reactor containing polymer (a1), a reactor containing polymer (a2) was used. However, the same operations as described in the section on (Preparation of Polymer (B) and Modifier) ​​of Manufacturing Example 1 were performed to obtain polymer (b2) as polymer (B). As a result, latex 2 comprising a composite 2 composed of polymer (a2) and polymer (b2) was obtained. Composite 2 can be referred to as a modifier. In polymer (b2), 100% by weight contains 5% by weight of GMA units as units containing reactive functional groups.

[0452] The particle size of complex 2 in latex 2 was determined using the method described above, and the result was 1100 Å. Furthermore, in complex 2, polymer (a2), which is polymer (A), can be considered to form the core, and polymer (b2), which is polymer (B), can be considered to form the shell. That is, complex 2 (i.e., the modifier) ​​can be considered to have a core-shell structure. Complex 2 (i.e., the modifier) ​​comprises 80 wt% polymer (a2) and 20 wt% polymer (b2) in 100 wt% of complex 2. The number-average molecular weight and weight-average molecular weight of complex 2 were determined using the method described above. As a result, complex 2 has two number-average molecular weights (Mn): polymer (a2) has a number-average molecular weight of 6000 Da, and polymer (b2) has a number-average molecular weight of 10000 Da. Additionally, complex 2 has two weight-average molecular weights (Mw): polymer (a2) has a weight-average molecular weight of 20000 Da, and polymer (b2) has a weight-average molecular weight of 100000 Da. The weight-average molecular weight of complex 2 (i.e., the modifier) ​​is 80,000 Da. Furthermore, the polydispersity index (PMI) of polymer (a2) is 3.0, and that of complex 2 is 4.0. The average number of reactive functional groups per molecule of polymer (a2) is 9, that of polymer (b2) is 3, and that of complex 2 is 8. The epoxy equivalent of polymer (a2) is 700 g / eq, and that of polymer (b2) is 8400 g / eq.

[0453] Latex 2 was used instead of latex 1. Otherwise, the powder of compound 2 was obtained from latex 2 using the same method as that used in manufacturing example 1 to recover compound 1 as powder from latex 1. Then, the powder of compound 2 was sieved through an 18-mesh sieve to obtain white powder that passed through the 18-mesh sieve. Hereinafter, the obtained white powder will be referred to as "modifier 2".

[0454] The content of monomer residues containing reactive functional groups and the total monomer residues contained in modifiers 1 and 2 obtained in Manufacturing Examples 1 and 2 were calculated using the method described above. Specifically, the content of monomer residues contained in modifiers 1 and 2, namely styrene (ST) residues, glycidyl methacrylate (GMA) residues, and butyl acrylate (BA) residues, was calculated. The results are shown in Table 1 below. It should be noted that the monomer residues listed above that belong to monomer residues containing reactive functional groups are GMA residues.

[0455]

[0456] As shown in Table 1, the contents of each monomer residue contained in modifiers 1 and 2, namely ST residue, GMA residue and BA residue, are all below the detection limit (N.D.; Not Detection).

[0457] [Examples and reference examples related to Implementation Method 1: Example A, Reference Example A]

[0458] [Example A1]

[0459] (Step 1: Preparation of polyester resin composition)

[0460] The polyester resin 1 was placed in a thermostat (ESPEC, Perfect Oven PVH-332) at 120°C for 24 hours to dry it.

[0461] Dry polyester resin 1 and modifier 1 were dry-mixed to obtain a mixture. The resulting mixture was then melt-blended using a twin-screw extruder (TECHNOVEL, 25mm, L / D=40) at a barrel temperature of 240°C to 270°C, a feed rate of 20 kg / h, and a screw speed of 400 rpm. At this point, the amount of modifier 1 used was 3.0% by weight out of a total of 100% by weight of polyester resin 1 and modifier 1. The melt-blended mixture extruded from the die was then cooled in a water bath and cut using a granulator. This process yielded a polyester resin composition, i.e., resin granules, containing structural units from the polyester resin and structural units from the modifier. The resulting resin granules were designated as "Polyester Resin Composition A1".

[0462] The MFR and IV values ​​of the obtained polyester resin composition A1 were determined using the method described above. The results are shown in Table 3.

[0463] (Preparation of polyester resin fibers)

[0464] (Dispensing process)

[0465] The polyester resin composition A1 was placed in the aforementioned thermostat at 120°C for 24 hours to obtain dried granules. The dried granules were then fed into a multifilament manufacturing apparatus using a 40mm single-shaft extruder for multifilament production. The nozzle of the multifilament manufacturing apparatus had the following specifications: orifice diameter φ0.9, die lip length 3.2L, and number of orifices 400H. The resin extrusion rate was set at 15 kg / hour during multifilament production.

[0466] (Process 2)

[0467] Next, the obtained multifilaments were wound onto a paper tube at a speed of 400 m / min for at least 10 minutes using a winding device. The wound filaments were designated as "polyester resin fiber A1 before stretching". The fineness of polyester resin fiber A1 before stretching was measured using the method described above. The fineness of polyester resin fiber A1 before stretching was 13.8 (dtex).

[0468] (Stretching process: stretching of polyester resin fibers)

[0469] Before stretching, polyester resin fiber A1 is fed to a stretching device and stretched at a stretch ratio of 2, 3, or 4 times according to the conditions described in Table 2 below. The fiber is then wound in a winding machine for at least 15 minutes. The stretched and wound polyester resin fiber is referred to as "stretched polyester resin fiber A1".

[0470]

[0471] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber A1 were determined using the methods described above. The results are shown in Table 4.

[0472] [Example A2]

[0473] Modifier 2 is used instead of modifier 1, and the amount of modifier 2 used is set to 1.0% by weight in a total of 100% by weight of polyester resin 1 and modifier 2. Otherwise, the same operation as step 1 of Example A1 is performed. Through this operation, a polyester resin composition containing structural units from polyester resin and structural units from modifier is obtained, namely polyester resin composition A2.

[0474] The MFR and IV values ​​of the obtained polyester resin composition A2 were determined using the method described above. The results are shown in Table 3.

[0475] Next, polyester resin composition A2 was used instead of polyester resin composition A1, and the same operations as described in the (extrusion step) and (step 2) of Example 1 (Preparation of Polyester Resin Fiber) were performed to obtain polyester resin fiber A2 before stretching. The fineness of the polyester resin fiber A2 before stretching was measured by the above method. The fineness of the polyester resin fiber A2 before stretching was 13.8 (dtex).

[0476] Next, polyester resin fiber A2 before stretching was used instead of polyester resin fiber A1 before stretching. Except for this, the polyester resin fiber A2 before stretching was stretched according to the same method and conditions as described in the section on (Stretching process: stretching of polyester resin fiber) of Example 1. Through this stretching, the stretched polyester resin fiber A2 was obtained.

[0477] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber A2 were determined using the methods described above. The results are shown in Table 4.

[0478] [Reference Example A1]

[0479] Compared to Examples A1 and A2, in Reference Example A1, polyester resin 2 was used instead of polyester resin 1, and no modifier was used.

[0480] The MFR and IV values ​​of polyester resin 2 were determined using the method described above. The results are shown in Table 3.

[0481] Next, polyester resin 2 was used instead of polyester resin composition A1, and the same operations as described in the (expansion step) and (step 2) of Example 1 (Preparation of Polyester Resin Fiber) were performed to obtain polyester resin fiber A3 before stretching. The fineness of the polyester resin fiber A3 before stretching was measured by the above method. The fineness of the polyester resin fiber A3 before stretching was 13.9 (dtex).

[0482] Next, polyester resin fiber A3 before stretching was used instead of polyester resin fiber A1 before stretching. Except for this, the polyester resin fiber A3 before stretching was stretched according to the same method and conditions as described in the section on (Stretching process: stretching of polyester resin fiber) of Example 1. Through this stretching, the stretched polyester resin fiber A3 was obtained.

[0483] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber A3 were determined using the methods described above. The results are shown in Table 4.

[0484]

[0485]

[0486] [Examples and reference examples related to Implementation Method 2: Example B, Reference Example B]

[0487] [Example B1]

[0488] (Process (A): Preparation of polyester resin composition)

[0489] The polyester resin 1 was placed in a thermostat (ESPEC, PerfectOvenPVH-332) at 120°C for 24 hours to dry it.

[0490] Dry polyester resin 1 and modifier 1 were dry-mixed to obtain a mixture. The resulting mixture was then melt-blended using a twin-screw extruder (TECHNOVEL, 25mm, L / D=40) at a barrel temperature of 240°C to 270°C, a feed rate of 20 kg / h, and a screw speed of 400 rpm. At this point, the amount of modifier 1 used was 3.0% by weight out of a total of 100% by weight of polyester resin 1 and modifier 1. The melt-blended mixture extruded from the die was then cooled in a water bath and cut using a granulator. This process yielded a polyester resin composition, i.e., resin granules, containing structural units from the polyester resin and structural units from the modifier. The resulting resin granules were designated as "Polyester Resin Composition B1".

[0491] The MFR and IV values ​​of the obtained polyester resin composition B1 were determined using the method described above. The results are shown in Table 6.

[0492] (Preparation of polyester resin fibers)

[0493] (Dispensing process)

[0494] The polyester resin composition B1 was placed in the aforementioned thermostat at 120°C for 24 hours to obtain dried granules. The dried granules were then fed into a multifilament manufacturing apparatus using a 40mm single-spindle extruder for multifilament production. The nozzle of the multifilament manufacturing apparatus had the following specifications: orifice diameter φ0.9, die lip length 3.2L, and number of orifices 400H. The resin extrusion rate was set at 15 kg / hour during multifilament production.

[0495] (Winding process)

[0496] Next, the obtained multifilament is wound onto a paper tube at a winding speed of 200 m / min or 400 m / min for at least 10 minutes using a winding device. The wound filament is designated as "polyester resin fiber B1 before stretching". The fineness of the polyester resin fiber B1 before stretching is measured using the method described above. The fineness of the polyester resin fiber B1 before stretching, wound at a winding speed of 200 m / min, is 28.3 dtex, and the fineness of the polyester resin fiber B1 before stretching, wound at a winding speed of 400 m / min, is 13.8 dtex. In Example B1, the multifilament can be wound for at least 10 minutes (including exactly 10 minutes) at both winding speeds of 200 m / min and 400 m / min without any breakage of the filament (resin composition).

[0497] (Process (B))

[0498] Polyester resin fibers B1, before stretching, were fed into a stretching device for stretching. Specifically, polyester resin fibers B1 wound at a take-up speed of 200 m / min were stretched at a stretch ratio of 2, 3, 4, or 5 times, and polyester resin fibers B1 wound at a take-up speed of 400 m / min were stretched at a stretch ratio of 2, 3, or 4 times, respectively, and wound in a winding machine for at least 15 minutes. The stretched polyester resin fibers are referred to as "stretched polyester resin fibers B1". In Example 1, polyester resin fibers B1 wound at a take-up speed of 200 m / min were wound at a stretch ratio of 2, 3, 4, or 5 times for at least 15 minutes, and the polyester resin fibers did not break. In Example B1, polyester resin fibers B1 obtained at a winding speed of 400 m / min are wound at a stretch ratio of 2, 3, or 4 times for more than 15 minutes, and the polyester resin fibers do not break.

[0499]

[0500] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber B1 were determined using the methods described above. The results are shown in Table 4.

[0501] [Example B2]

[0502] Modifier 2 is used instead of modifier 1, and the amount of modifier 2 used is set to 1.0% by weight in a total of 100% by weight of polyester resin 1 and modifier 2. Otherwise, the same operation as step (A) of Example B1 is performed. Through this operation, a polyester resin composition comprising structural units from polyester resin and structural units from modifier is obtained, namely polyester resin composition B2.

[0503] The MFR and IV values ​​of the obtained polyester resin composition B2 were determined using the method described above. The results are shown in Table 6.

[0504] Next, polyester resin composition B2 was used instead of polyester resin composition B1, and the same operations as described in the (extraction process) and (winding process) of Example B1 (Preparation of Polyester Resin Fiber) were performed to obtain polyester resin fiber B2 before stretching. The fineness of the polyester resin fiber B2 before stretching was measured by the above method. The fineness of the polyester resin fiber B2 before stretching wound at a winding speed of 200 m / min was 27.2 (dtex), and the fineness of the polyester resin fiber B2 before stretching wound at a winding speed of 400 m / min was 13.8 (dtex). In Example B2, regardless of the winding speed of 200 m / min or 400 m / min, the multifilament could be wound for more than 10 minutes (including exactly 10 minutes) without the filament (resin composition) breaking.

[0505] Next, polyester resin fiber B2 before stretching was used instead of polyester resin fiber B1 before stretching. Except for this, the same operation as described in step (B) of Example B1 was performed to obtain stretched polyester resin fiber B2. In Example B2, the polyester resin fiber B2 obtained at a take-up speed of 200 m / min was taken at a stretch ratio of 2, 3, 4, or 5 times for at least 15 minutes, and the polyester resin fiber did not break. In Example B2, the polyester resin fiber B2 obtained at a take-up speed of 400 m / min was taken at a stretch ratio of 2, 3, or 4 times for at least 15 minutes, and the polyester resin fiber did not break.

[0506] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber B2 were determined using the methods described above. The results are shown in Table 4.

[0507] [Reference Example B1]

[0508] Compared to Examples B1 and B2, in Reference Example B1, polyester resin 2 is used instead of polyester resin 1, and no modifier is used.

[0509] The MFR and IV values ​​of polyester resin 2 were determined using the method described above. The results are shown in Table 6.

[0510] Next, polyester resin 2 was used instead of polyester resin composition B1, and the same operations as described in the (extraction step) and (winding step) of (Preparation of polyester resin fiber) in Example B1 were performed to obtain polyester resin fiber B3 before stretching. The fineness of the polyester resin fiber B3 before stretching was measured by the above method. The fineness of the polyester resin fiber B3 before stretching wound at a winding speed of 200 m / min was 27.5 (dtex), and the fineness of the polyester resin fiber B3 before stretching wound at a winding speed of 400 m / min was 13.9 (dtex).

[0511] Next, polyester resin fiber B3 before stretching is used instead of polyester resin fiber B1 before stretching. Otherwise, the same operation as described in step (B) of Example 1 is performed to obtain polyester resin fiber B3 after stretching.

[0512] The fineness, drying shrinkage, maximum elongation, elongation at break, and Young's modulus of the stretched polyester resin fiber B3 were determined using the methods described above. The results are shown in Table 7.

[0513]

[0514]

[0515] Industrial availability

[0516] According to one embodiment of the present invention, polyester resin fibers can be manufactured with high productivity even when using modifiers. Therefore, one embodiment of the present invention is applicable to the field of polyester resin fibers, particularly recycled polyester resin fibers using recycled polyester resins. Furthermore, the polyester resin fibers obtained using one embodiment of the present invention are applicable to various fields such as clothing and interior decoration.

Claims

1. A method for manufacturing polyester resin fibers, comprising: Step 1 involves melt-blending a polyester resin with a modifier to obtain a polyester resin composition, and Step 2 involves winding the polyester resin composition obtained in Step 1 at a winding speed of 400 m / min or higher.

2. The method for manufacturing polyester resin fibers according to claim 1, wherein, The process further includes step (B), in which the polyester resin composition obtained in step 1 is stretched at a stretching ratio of more than 2 times.

3. The method for manufacturing polyester resin fibers according to claim 1, wherein, The process further includes a stretching step, in which the polyester resin fibers obtained in step 2 are stretched.

4. The method for manufacturing polyester resin fibers according to any one of claims 1 to 3, wherein, The polyester resin is polyethylene terephthalate, i.e., PET.

5. The method for manufacturing polyester resin fibers according to any one of claims 1 to 3, wherein, The modifier comprises polymer A, which contains units with reactive functional groups and units without reactive functional groups.

6. The method for manufacturing polyester resin fibers according to claim 5, wherein, The modifier further comprises polymer B.

7. The method for manufacturing polyester resin fibers according to claim 6, wherein, The epoxy equivalent of polymer B is above 6000 g / eq and below 50000 g / eq.

8. The method for manufacturing polyester resin fibers according to claim 6, wherein, The polymer B contains more than 2.5% by weight and less than 10.0% by weight of units containing reactive functional groups in 100% by weight of polymer B.

9. The method for manufacturing polyester resin fibers according to claim 8, wherein, In the polymer B, the unit containing the reactive functional group includes glycidyl methacrylate units.

10. The method for manufacturing polyester resin fibers according to claim 5, wherein, Each molecule of polymer A has an average of more than 2 and less than 10 reactive functional groups.

11. The method for manufacturing polyester resin fibers according to any one of claims 1 to 3, wherein, The weight-average molecular weight of the modifier is greater than 20,000 Da and less than 200,000 Da.

12. The method for manufacturing polyester resin fibers according to claim 5, wherein, The number-average molecular weight of polymer A is less than 10,000 Da.

13. The method for manufacturing polyester resin fibers according to claim 6, wherein, The weight-average molecular weight of polymer B is above 80,000 Da and below 500,000 Da.

14. The method for manufacturing polyester resin fibers according to any one of claims 1 to 3, wherein, The modifier, based on its weight, has less than 50 ppm of monomer residue containing reactive functional groups and less than 100 ppm of total monomer residue.

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