Polyester resin, fibers, and method for producing polyester resin

Abstract

To provide a polyester resin which is excellent in heat adhesion, when used as a binder fiber.SOLUTION: A polyester resin satisfies all of following (1) to (3). (1) A content of an aromatic dicarboxylic acid component is 70 mol% or more in total acid components constituting the polyester resin, and a content of an aliphatic carboxylic acid component is 30 mol% at the maximum, (2) a glycol component constituting the polyester resin contains ethylene glycol and 1,4-butane diol as main components, and a molar ratio of the ethylene glycol to the 1,4-butane diol is 90 / 10 to 30 / 70, and (3) the polyester resin contains diethylene glycol and triethylene glycol as glycol components, and a content of the triethylene glycol is more than 0.1 mol% and 5.0 mol% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to polyester resin, fibers, and a method for producing polyester resin. [Background technology]

[0002] Polyester resins, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), have excellent mechanical and chemical properties and are used in a wide range of fields (for example, fibers for clothing and industrial materials, films or sheets for packaging and magnetic tapes, hollow molded bottles, casings for electrical and electronic components, and other engineering plastic molded products). Furthermore, polyester resin is used in textiles, and hot-melt binder fibers are widely used for bonding fibers that make up pillows, bedding, or nonwoven fabrics. Among polyester binder fibers, those made of copolymerized polyester resin are known. For example, Patent Document 1 describes copolymerized polyester for binder fibers with a melting point of about 130 to 200°C. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-12693

[0004] In recent years, there has been a demand for fibers with improved heat adhesion and strength when used in nonwoven fabrics, while maintaining good operability without yarn breakage during spinning or single-fiber sticking during stretching. [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to obtain a polyester resin suitable for binder fibers that has good operability when formed into fibers, good heat adhesion, and excellent strength when used in textile products such as nonwoven fabrics. [Means for solving the problem]

[0006] As a result of diligent research to solve the above problems, the inventors of the present invention discovered that if a polyester resin satisfying a specific composition is used, fibers with excellent heat adhesion properties can be obtained with good operability, leading to the present invention.

[0007] In other words, the gist of this invention is as follows: <1> ~< 5 >That is correct. <1> (1)~( 4 A polyester resin characterized by satisfying all of the following conditions. (1) The total acid content of the polyester resin is 70 mol% or more of aromatic dicarboxylic acid components, and the content of aliphatic carboxylic acid components is at most 30 mol%. (2) The glycol component constituting the polyester resin mainly consists of ethylene glycol and 1,4-butanediol, and the molar ratio of ethylene glycol to 1,4-butanediol is 90 / 10 to 30 / 70. (3) The glycol component contains diethylene glycol and triethylene glycol, with the diethylene glycol content being 1.0 mol% or more of the total glycol component, and the triethylene glycol content being greater than 0.1 mol% and less than or equal to 5.0 mol%. (4) The sulfur content is 5 to 120 ppm. <2> The content of tetraethylene glycol in the total glycol components is 2.0 mol% or less. <1> The polyester resin described above. < 3 >Its melting point is between 150°C and 230°C. <1> or <2> The polyester resin described above. < 4 > <1> ~< 3 A fiber made of the polyester resin described in any of the above. < 5 > <1> ~< 3A method for producing a polyester resin as described in any of the above, comprising the step of adding an organic sulfonic acid compound to a polyester resin raw material. [Effects of the Invention]

[0008] The polyester resin of the present invention provides fibers that have good operability (hereinafter simply referred to as operability) when forming fibers during melt spinning or stretching, good heat adhesion (hereinafter simply referred to as heat adhesion) when used as binder fibers, and can produce fiber products such as nonwoven fabrics with excellent strength. [Modes for carrying out the invention]

[0009] The polyester resin of the present invention will be described in detail below. The polyester resin of the present invention has an aromatic dicarboxylic acid component content of 70 mol% or more, preferably 80 mol% or more, and more preferably 85 mol% or more, among the total acid components constituting the polyester. The aliphatic carboxylic acid component content is at most 30 mol%, preferably 20 mol% or less, and more preferably 15 mol% or less. The acid components constituting the polyester resin of the present invention are either composed mainly of aromatic dicarboxylic acid components with aliphatic carboxylic acid components as copolymer components, or composed entirely of aromatic dicarboxylic acid components.

[0010] Specific examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfisoisophthalic acid, phthalic anhydride, and naphthalenedicarboxylic acid. Among these, terephthalic acid is preferred because it easily allows the melting point and crystallinity of the resulting polyester resin to be within a desirable range.

[0011] The aliphatic carboxylic acid component contributes to lowering the melting point of the polyester resin of the present invention. When the proportion of the aliphatic carboxylic acid component exceeds 30 mol%, the melting point becomes too low, resulting in poor heat resistance. Moreover, during melt spinning or when making fibers such as during stretching, the operability (operability), yarn quality, etc. deteriorate, and the fibers become poor in strength, which is not preferable.

[0012] Examples of the aliphatic carboxylic acid component include aliphatic dicarboxylic acid components and aliphatic hydroxycarboxylic acid components. Specific examples of the aliphatic dicarboxylic acid component include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexadecanedioic acid, eicosanedioic acid, etc. The aliphatic hydroxycarboxylic acid component is obtained by the ring-opening reaction of an aliphatic lactone. Specific examples of the aliphatic lactone include lactones having 4 to 11 carbon atoms and homopolymers or copolymers of two or more of these. Particularly preferred aliphatic lactones include ε-caprolactone and δ-valerolactone.

[0013] On the other hand, as the glycol component in the polyester resin, it is mainly composed of ethylene glycol (hereinafter, may be abbreviated as EG) and 1,4-butanediol (hereinafter, may be abbreviated as BD). When the total amount of all glycol components is 100 mol%, the content of both components is preferably 80 mol% or more, and more preferably 90 mol% or more, of all glycol components. If the content of both components is less than 80 mol%, the resulting polyester resin may be inferior in crystallinity and heat resistance.

[0014] And the molar ratio (EG / BD) of the two is 90 / 10 to 30 / 70, preferably 80 / 20 to 40 / 60, and more preferably 70 / 30 to 40 / 60. Outside this range, the melting point of the polyester resin becomes high. Therefore, sufficient heat adhesiveness (heat adhesiveness) when made into fibers cannot be obtained, so it is necessary to apply a high temperature during heat adhesion, and the strength of the product where thermal decomposition may occur decreases.

[0015] The polyester resin of the present invention contains diethylene glycol and triethylene glycol as glycol components other than ethylene glycol and 1,4-butanediol, and the content of triethylene glycol in the total glycol components must be greater than 0.1 mol% and less than or equal to 5.0 mol%. Preferably, the content of triethylene glycol in the total glycol components is between 0.3 mol% and 4.0 mol%, and more preferably between 0.4 mol% and 3.0 mol%. If the content is less than 0.1 mol%, the operability and heat adhesion will be poor. On the other hand, if it exceeds 5.0 mol%, the crystallinity will be low, and the heat resistance and yarn quality will be reduced.

[0016] Furthermore, it is preferable to include tetraethylene glycol as a glycol component. In this case, the total content of triethylene glycol and tetraethylene glycol in the total glycol component is preferably 7.0 mol% or less, more preferably 6.0 mol% or less, even more preferably 0.6 mol% to 4 mol%, and particularly preferably 0.8 mol% to 3 mol%. If it exceeds 7.0 mol%, the heat resistance will decrease, and the operability and yarn quality will be inferior. On the other hand, if it is less than 0.6 mol%, the operability and heat adhesion may be inferior.

[0017] The content of tetraethylene glycol in the total glycol components is preferably 0.0 to 2.0 mol%, more preferably 0 to 1.0 mol%, and even more preferably 0.0 to 0.5 mol%. If it exceeds 2.0 mol%, the heat resistance and weather resistance may decrease.

[0018] The diethylene glycol content is preferably 1.0 mol% or more, more preferably 2.0 mol% or more, and even more preferably 2.5 mol% or more of the total glycol components. By setting the diethylene glycol content within this range, operability and heat adhesion can be further improved. The upper limit of the diethylene glycol content is preferably 10 mol%, for example, in order to further improve the yarn quality when it is made into fibers.

[0019] To adjust the respective content of diethylene glycol, triethylene glycol, and tetraethylene glycol, for example, an organic sulfonic acid compound may be used as a polymerization catalyst in the polyester resin manufacturing method described later, the amount of organic sulfonic acid compound added may be set to a preferred range, the molar ratio of glycol component (G) to acid component (A) (G / A) may be set to a preferred range, or a step for etherification reaction may be included and its temperature or time adjusted.

[0020] The polyester resin of the present invention may contain glycol components other than those listed above. Specific examples include 1,2-propylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, dimergol, ethylene oxide adducts of bisphenol S, ethylene oxide adducts of bisphenol A, and the like.

[0021] The polyester resin of the present invention preferably has a melting point of 150°C to 230°C, and more preferably 160°C to 210°C. By setting the melting point within the above range, the melting point becomes lower than that of general polyester resins, allowing for a lower heat treatment temperature when used as a binder fiber, and also resulting in good heat adhesion, which further enhances the strength when used as a nonwoven fabric or the like.

[0022] The polyester resin of the present invention preferably has an intrinsic viscosity of 0.45 dl / g or higher, more preferably 0.5 dl / g or higher, and even more preferably 0.6 to 0.8 dl / g. If the intrinsic viscosity is less than 0.45 dl / g, sufficient yarn properties may not be obtained when the resin is made into fibers. In this invention, the intrinsic viscosity is measured at a temperature of 20°C using an equimassive mixture of phenol and tetrachloroethane as the solvent.

[0023] The polyester resin of the present invention may contain any polymer, antistatic agent, defoaming agent, dyeability improver, dye, pigment, matting agent, fluorescent whitening agent, stabilizer, antioxidant, colorant, flame retardant, or other additives, as long as they do not impair the effects of the present invention. Examples of antioxidants include aromatic amine-based and phenol-based antioxidants. Examples of stabilizers include phosphorus-based such as phosphoric acid or phosphate ester-based stabilizers, sulfur-based stabilizers, and amine-based stabilizers.

[0024] The polyester resin of the present invention may contain organic, inorganic, or organometallic toners, or fluorescent whitening agents, etc., to the extent that they do not impair the effects of the present invention. This can further suppress discoloration such as yellowing of the polyester resin. Alternatively, other resins such as polyethylene, or inorganic nucleating agents such as talc may be added to improve crystallinity.

[0025] Furthermore, organic, inorganic, or organometallic fillers may be added to the polyester resin of the present invention, to the extent that they do not impair the effects of the present invention. By containing fillers, the polyester resin of the present invention can reduce friction between fibers made of this polyester resin (F / F friction) and friction between fibers made of this polyester resin and metal (F / M friction), thereby suppressing single-fiber breakage and other problems caused by frictional resistance of fibers during the fiber manufacturing process.

[0026] The polyester resin of the present invention may have a cobalt compound added for purposes such as improving color tone, as long as it does not impair the effects of the present invention. The cobalt compound is not particularly limited, but examples include cobalt acetate, cobalt nitrate, cobalt chloride, cobalt acetylacetonate, cobalt naphthenate, and their hydrates. Among these, cobalt acetate tetrahydrate is particularly preferred. The amount of cobalt compound added is preferably 10 ppm or less, more preferably 5 ppm or less, and even more preferably 3 ppm or less, as cobalt atoms relative to the polyester resin.

[0027] The polyester resin of the present invention may be mixed with waste resin generated during the manufacturing process or recycled polyester resin recovered from the market (for example, PET bottles, etc.).

[0028] <Method for manufacturing polyester resin> The present invention relates to a method for producing polyester resin, which involves adding an organic sulfonic acid compound to a polyester resin raw material and then carrying out a polycondensation reaction.

[0029] Furthermore, in this invention, an etherification reaction may be carried out under specific conditions before or simultaneously with the polycondensation reaction. This makes it easier to adjust the content of diethylene glycol and triethylene glycol to a specific range. As a result, a polyester resin with even better operability and thermal adhesion can be obtained.

[0030] Examples of raw materials for polyester resins include glycol components containing ethylene glycol as the main component, dicarboxylic acid components, and esterified products as lower-order condensates consisting of glycol components and dicarboxylic acid components.

[0031] As a method for obtaining the above esterified product, for example, when producing polyethylene terephthalate as a polyester resin, terephthalic acid, ethylene glycol, and other copolymer components as needed are reacted directly, water is removed by distillation, and the product is esterified to obtain an esterified product as a raw material for polyester resin. Alternatively, dimethyl terephthalate, ethylene glycol, and other copolymer components as needed are reacted, methyl alcohol is removed by distillation, and the product is transesterified to obtain an esterified product.

[0032] The following describes the method for preparing esterified products. A slurry containing preferably 1.02 to 2.5 moles, more preferably 1.03 to 1.8 moles, of ethylene glycol per mole of dicarboxylic acid or its ester derivative is prepared, and this slurry is continuously supplied to an esterification reactor to obtain an esterified product.

[0033] Esterification reactions are carried out under reflux conditions of ethylene glycol, while removing the water or alcohol produced by the reaction from the system using a rectification column. Esterification reactions can also be carried out using a multi-stage apparatus consisting of multiple esterification reactors connected in series.

[0034] The temperature of the first esterification reaction is preferably 150-270°C, and more preferably 245-265°C. The pressure is 0.2-3 kg / cm². 2 It is preferably G, and 0.5-2 kg / cm³ 2 It is more preferable that it be G.

[0035] The temperature of the final esterification reaction is preferably 150-290°C, and more preferably 255-275°C. The pressure is 0-1.5 kg / cm². 2 It is preferably G, and 0-1.3 kg / cm³ 2 It is more preferable that it be G.

[0036] When the reaction is carried out in three or more stages, the reaction conditions for the intermediate esterification reaction are preferably between the reaction conditions for the first stage and the reaction conditions for the final stage. In multi-step esterification reactions, it is preferable to increase the reaction rate smoothly at each step. Ultimately, the esterification reaction rate should preferably reach 90% or higher, and more preferably 93% or higher. These esterification reactions yield esterified products with a preferred molecular weight of approximately 500 to 5000.

[0037] When terephthalic acid is used in an esterification reaction, the reaction proceeds due to the catalytic action of terephthalic acid as an acid.

[0038] To the esterified product obtained as described above, 1,4-butanediol and an aliphatic dicarboxylic acid or aliphatic lactone are added, and a depolymerization reaction is carried out. Then, an organic sulfonic acid compound is added as a polymerization catalyst, and a polycondensation reaction is carried out to obtain the polyester resin of the present invention.

[0039] (Depolymerization reaction) The depolymerization reaction is described below. To 150 to 220 parts by mass of the esterified product (ethylene terephthalate oligomer) obtained by the esterification reaction, 20 to 120 parts by mass of 1,4-butanediol and, if necessary, at most 30 parts by mass of aliphatic dicarboxylic acid or aliphatic lactone are added while stirring so that the molar ratio of total glycol components to total acid components is 1.2 to 3.0.

[0040] The reaction conditions for depolymerization are not particularly limited, but the temperature is preferably 240-290°C, and more preferably 250-280°C. The depolymerization reaction is preferably carried out under atmospheric pressure or under pressure, with a pressure of 0-3.0 kg / cm². 2 G is preferable.

[0041] (catalyst) In the present invention, by using an organic sulfonic acid compound as a polymerization catalyst, the content of triethylene glycol and tetraethylene glycol in the resulting polyester resin can be set to a specific range. Examples of organic sulfonic acid compounds include benzenesulfonic acid, m- or p-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, o-, m- or p-sulfobenzoic acid, benzaldehyde-o-sulfonic acid, acetophenone-p-sulfonic acid, acetophenone-3,5-disulfonic acid, o-, m- or p-aminobenzenesulfonic acid, sulfanilic acid, 2-aminotoluene-3-sulfonic acid, phenylhydroxylamine-3-sulfonic acid, phenylhydrazine-3-sulfonic acid, 1- Nitronaphthalene-3-sulfonic acid, thiophenol-4-sulfonic acid, anisole-o-sulfonic acid, 1,5-naphthalenedisulfonic acid, o-, m- or p-chlorobenzenesulfonic acid, o-, m- or p-bromobenzenesulfonic acid, o-, m- or p-nitrobenzenesulfonic acid, nitrobenzene-2,4-disulfonic acid, nitrobenzene-3,5-disulfonic acid, nitrobenzene-2,5-disulfonic acid, 2-nitrotoluene-5-sulfonic acid, 2-nitrotoluene-4-sulfonic acid, 2- Nitrotoluene-6-sulfonic acid, 3-nitrotoluene-5-sulfonic acid, 4-nitrotoluene-2-sulfonic acid, 3-nitro-o-xylene-4-sulfonic acid, 5-nitro-o-xylene-4-sulfonic acid, 2-nitro-m-xylene-4-sulfonic acid, 5-nitro-m-xylene-4-sulfonic acid, 3-nitro-p-xylene-2-sulfonic acid, 5-nitro-p-xylene-2-sulfonic acid, 6-nitro-p-xylene-2-sulfonic acid, 2,4-dinitrobenzenesulfonic acid, 3,5-dinitroben Zensulfonic acid, o-, m- or p-fluorobenzenesulfonic acid, 4-chloro-3-methylbenzenesulfonic acid, 2-chloro-4-sulfobenzoic acid, 5-sulfosalicylic acid, 4-sulfophthalic acid, 2-sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, 4-methyl-2-sulfobenzoic anhydride, 5-methoxy-2-sulfobenzoic anhydride, 1-sulfonaphthoic anhydride, 8-sulfonaphthoic anhydride, 3,6-disulfophthalic anhydride, 4,6-disulfisophthalic anhydride, 2,Examples include 5-disulfoterephthalic anhydride, methanesulfonic acid, ethanesulfonic acid, methionic acid, cyclopentanesulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,2-ethanedisulfonic anhydride, 3-propanedisulfonic acid, β-sulfopropionic acid, isethionic acid, nithionic acid, nithionic anhydride, 3-oxy-1-propanesulfonic acid, 2-chloroethanesulfonic acid, phenylmethanesulfonic acid, β-phenylethanesulfonic acid, α-phenylethanesulfonic acid, ammonium chlorosulfonate, methyl benzenesulfonate, ethyl p-toluenesulfonate, ethyl methanesulfonate, dimethyl 5-sulfosalicylate, trimethyl 4-sulfophthalate, and salts thereof. In particular, from the perspective of versatility, examples include 2-sulfobenzoic anhydride, o-sulfobenzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, 5-sulfosalicylic acid, benzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, p-aminobenzenesulfonic acid, p-toluenesulfonic acid, p-methyl p-toluenesulfonate, 5-sulfoizophthalic acid, and their salts.

[0042] When a metal-based catalyst is not used as the polymerization catalyst, the amount of metal components derived from the metal-based catalyst in the resulting polyester resin of the present invention can be reduced. A high content of metal components not only increases the environmental burden, but can also result in poor transparency and the generation of foreign matter during melt processing. The content of metal components derived from the metal catalyst is preferably 1 ppm or less, more preferably 0.5 ppm or less, and even more preferably 0 ppm. Examples of metal catalysts include compounds such as antimony, germanium, tin, titanium, zinc, aluminum, iron, magnesium, potassium, calcium, sodium, manganese, nickel, and cobalt.

[0043] Organic sulfonic acid compounds can be added, for example, in solid form, slurry form, or as a solution dissolved in water, glycol, etc.

[0044] The addition amount of the organic sulfonic acid compound depends on its type, but is preferably 0.5×10 -4 ~10×10 -4 mol per 1 mol of all acid components constituting the polyester resin, and more preferably 2.0×10 -4 ~6.0×10 -4 mol. If the addition amount is less than the above range, it may not be possible to obtain a polyester resin with a high degree of polymerization in a short time, or the content of diethylene glycol or triethylene glycol may not be within a specific range. On the other hand, if it exceeds the above range, the content of triethylene glycol may not be within a specific range, or it may cause the generation of side reaction products (e.g., tetrahydrofuran, etc.) or the coloring of the polyester resin, or it may not be possible to obtain a resin with the target degree of polymerization.

[0045] By setting the addition amount of the organic sulfonic acid compound within the above range, the sulfur component content of the obtained polyester resin can be preferably 5 to 120 ppm, more preferably 8 to 100 ppm. If the sulfur component content is less than 5 ppm, the yarn quality characteristics may be inferior. On the other hand, if it exceeds 120 ppm, it may cause the generation of side reaction products (e.g., tetrahydrofuran, etc.) or the coloring of the polyester.

[0046] (Polycondensation reaction) Examples of the polycondensation reaction include a melt polycondensation reaction. The polycondensation reaction may be carried out in one step or divided into multiple steps.

[0047] The polycondensation reaction conditions are not particularly limited, but the temperature of the first-stage polycondensation reaction is preferably 250 to 290°C, more preferably 260 to 280°C. The pressure is preferably 500 to 20 hPa, more preferably 200 to 30 hPa.

[0048] In the case of a multi-stage reaction, the temperature of the final polycondensation reaction is preferably 265 to 300°C, and more preferably 275 to 295°C. The pressure is preferably 10 to 0.1 hPa, and more preferably 5 to 0.5 hPa. When the reaction is carried out in three or more stages, the reaction conditions of the intermediate stages are preferably those between the reaction conditions of the first and final stages. It is preferable to smoothly increase the degree of polymerization in each of these stages.

[0049] (Etherification reaction) The etherification reaction may be carried out simultaneously with the esterification or polycondensation reaction. Alternatively, the etherification reaction may be carried out after the addition of an organic sulfonic acid compound. By adding an organic sulfonic acid compound as a polymerization catalyst and allowing the etherification reaction to proceed through dehydration, diethylene glycol and triethylene glycol are more readily produced.

[0050] The temperature for the etherification reaction is preferably 200°C or higher, more preferably 220-300°C, even more preferably 230-280°C, and particularly preferably 240-260°C. Below 200°C, the reaction does not proceed sufficiently, and the content of diethylene glycol and triethylene glycol may not be within the specified range, which may result in insufficient thermal adhesion. Above 300°C, decomposition of the esterified product proceeds during the reaction, which may reduce operability and yarn properties.

[0051] By adjusting the etherification reaction time, it becomes easier to control the content of diethylene glycol and triethylene glycol within a specific range. While there are no particular limitations on the etherification reaction time, it is preferably 5 to 120 minutes, and more preferably 10 to 60 minutes. If the reaction time exceeds 120 minutes, the etherification reaction may proceed too far, resulting in the content of diethylene glycol and triethylene glycol not being within the specific range, or the decomposition of the esterified product progressing during the reaction, which can lead to a decrease in operability and yarn properties.

[0052] The etherification reaction is preferably carried out under atmospheric pressure, pressurized pressure, or reduced pressure, with the pressure being 0 to 3.0 kg / cm². 2 It is preferable that the pressure be G or 1000 to 0.1 hPa.

[0053] The amount of triethylene glycol and tetraethylene glycol produced in the polyester resin can be adjusted by adjusting the molar ratio (G / A) of the glycol component (G) to the acid component (A) in the raw materials subjected to the etherification reaction. A G / A ratio of 1.05 to 3.00 is preferred, and a ratio of 1.10 to 2.00 is more preferred. To adjust the G / A ratio, additional glycol components such as ethylene glycol may be added to the polyester raw material as needed. If the G / A ratio is less than 1.05, the amount of triethylene glycol and tetraethylene glycol produced tends to be low, while if it exceeds 3.00, the amount of triethylene glycol and tetraethylene glycol produced tends to be high.

[0054] (Uses of polyester resin) The polyester resin of the present invention is applicable to a variety of uses and can be suitably used in, for example, fibers, molded articles, films, and the like.

[0055] In the case of molded articles containing the polyester resin of the present invention, they can be manufactured, for example, by applying various molding methods such as press molding, extrusion molding, pressure molding, and blow molding using raw materials containing the polyester resin of the present invention. This makes it possible to provide containers and various other parts.

[0056] The polyester resin of the present invention can be used to produce the fibers of the present invention. The fibers of the present invention can be manufactured by a conventional melt spinning method, such as a method in which spinning and drawing are performed in two steps, or a method in which they are performed in one step. Furthermore, the fibers of the present invention can be crimped, heat-set, or cut into staples (short fibers) or short-cut fibers of a desired length by a cutting process. Needless to say, the fibers can also be wound directly without going through a cutting process to become continuous fibers (long fibers).

[0057] The fiber form of the present invention may be a fiber with an irregular cross-section, a hollow cross-section fiber, a composite fiber formed by compounding with the same type of resin or other resins, or a dope-dyed fiber. Furthermore, the fiber of the present invention may be used to produce a processed yarn by employing known yarn processing methods such as blending or spinning.

[0058] The fibers of the present invention may use the polyester resin of the present invention in part. For example, when using binder fibers, in addition to fully melted binder fibers using only the polyester resin of the present invention, core-sheath type binder fibers may be used in which the polyester resin of the present invention is used only in the sheath portion. Furthermore, the polyester resin of the present invention may be used in only one of the two components of a composite fiber bonded side by side. The other component in such a composite fiber may be appropriately selected according to the required fiber properties and applications.

[0059] Examples of the characteristic values ​​of the fibers of the present invention include those having a single fiber fineness of 0.5 to 25.0 dtex, a strength of 0.1 to 6.0 cN / dtex, and an elongation of 10 to 200%.

[0060] The fibers of the present invention can be used to make various textile products. For example, the fibers of the present invention can be mixed with other fibers as a binder to make spun yarn or nonwoven fabric.

[0061] The nonwoven fabric may be a dry-laid nonwoven fabric or a wet-laid nonwoven fabric. The basis weight of the nonwoven fabric is not particularly limited. The method of forming the nonwoven fabric involves using the polyester resin (polyester resin of the present invention) that constitutes the fibers of the present invention as a heat-bonding component, and forming a nonwoven fabric by heat bonding the fibers together. The constituent fibers may be three-dimensionally entangled before heat bonding.

[0062] The nonwoven fabric may contain fibers other than the fibers of the present invention. Examples of such fibers include fibers made of polyester resin with a melting point higher than that of the polyester resin of the present invention.

[0063] An example of a method for manufacturing nonwoven fabric is given. When mixing the fibers of the present invention with other fibers, the other fibers are prepared and weighed in any proportion. The proportion of the fibers of the present invention when mixing can be appropriately selected according to the required characteristics of the nonwoven fabric, and is preferably about 10 to 90% by mass.

[0064] Subsequently, when manufacturing a dry nonwoven fabric, the weighed constituent fibers are fed into a carding machine and defibrated to produce a dry web. The obtained web is then subjected to a heat bonding treatment in a continuous heat treatment machine that applies hot air at a temperature at which the polyester resin of the present invention melts or softens, thereby obtaining a dry nonwoven fabric in which the constituent fibers are integrated by heat bonding.

[0065] When manufacturing a wet-laid nonwoven fabric, the weighed raw material is stirred and defibrated using a pulp dissociator, and then a wet-laid web is produced using a paper machine. The obtained web is then subjected to a heat bonding treatment in a continuous heat treatment machine that applies hot air at a temperature at which the polyester resin of the present invention melts or softens, thereby obtaining a wet-laid nonwoven fabric in which the constituent fibers are integrated by heat bonding. [Examples]

[0066] The present invention will be described in detail below based on examples, but the present invention is not limited thereto. Measurement and evaluation were performed by the following methods.

[0067] (1) Intrinsic viscosity The measurement was performed at 20°C using an equimassive mixture of phenol and tetrachloroethane as the solvent.

[0068] (2) Composition of aromatic dicarboxylic acid components, aliphatic carboxylic acid components, and glycol components 20 mg of the sample was dissolved in 0.6 mL of a mixed solvent of deuterated chloroform / deuterated trifluoroacetic acid = 11 / 1 (volume ratio). 1H-NMR was measured using a JEOL nuclear magnetic resonance spectrometer (JNM-ECZ), and the molar ratios of the dicarboxylic acid component, aliphatic hydroxycarboxylic acid component, triethylene glycol component, and tetraethylene glycol component, as well as the molar ratios of the other glycol components, were calculated from the integrated proton peak intensities of each component in the resulting chart.

[0069] (3) Determination of triethylene glycol and tetraethylene glycol components Polyester resin was hydrolyzed in a 0.75 N potassium hydroxide / methanol solution, and then neutralized with terephthalic acid. Next, the filtrate obtained by filtration was measured by gas chromatography, and the molar ratio of triethylene glycol to tetraethylene glycol was calculated using a pre-prepared calibration curve. From these molar ratios and the results of the aforementioned 1H-NMR measurements (the molar ratio of the total amount of triethylene glycol and tetraethylene glycol to the molar ratio of each other glycol component), the content of triethylene glycol and tetraethylene glycol in the total glycol components was calculated.

[0070] (4) Melting point (Tm), glass transition temperature (Tg) Measurements were taken using a PerkinElmer DIAMOND DSC differential scanning calorimeter in a nitrogen atmosphere, within a temperature range of -50 to 240°C, and at a heating rate of 20°C / min.

[0071] (5) Sulfur content Polyester resin was melt-molded at 300°C to form a disc-shaped molded plate with a diameter of 3 cm and a thickness of 1 cm. Quantitative analysis was performed using the calibration curve method with a Rigaku ZSX PRIMUS X-ray fluorescence analyzer.

[0072] (6) Operability (cut thread, single thread adhesion) If the number of filament breaks during 24 hours of continuous melt spinning was 3 or less per day / spindle, and there was no adhesion between individual filaments during the drawing process, it was marked as "○". Otherwise, it was marked as "×".

[0073] (7) Strength and elongation of long fibers The obtained long fibers were measured using a Tensilon RTC-1210 (manufactured by Orientec Co., Ltd.) in accordance with JIS L 1013.

[0074] (8) Strong non-woven fabric The obtained nonwoven fabric was cut into samples of 150 mm in the MD direction and 50 mm in the CD direction. The MD strength of the nonwoven fabric was measured using an Autograph (Shimadzu AG-50KNI) under conditions of a tensile speed of 100 mm / min and a chuck distance of 100 mm. The sample size was N=5. Furthermore, for both the dry-laid and wet-laid nonwoven fabrics obtained in the examples, those with a nonwoven fabric strength of 4000 cN or higher were considered to have good thermal adhesion.

[0075] Example 1 [Polyester resin] A slurry of terephthalic acid (TPA) and ethylene glycol (EG) (molar ratio 1 / 1.6) was continuously supplied to an esterification reaction vessel, and the reaction was carried out under conditions of a temperature of 250°C and a pressure of 0.2 MPa, with a residence time of 8 hours to obtain esterified product A (terephthalic acid:ethylene glycol = 100:111 (molar ratio)). The heated and molten esterified product A was placed in a polycondensation reaction vessel heated to 280°C. Following the addition of ε-caprolactone (εCl) and 1,4-butanediol (BD) in the amounts shown in Table 1, a depolymerization reaction was carried out for 1 hour. Then, 6.0 × 10⁻⁶ of 5-sulfosalicylic acid dihydrate (SS) was added as a polycondensation catalyst. -4 The molar ratio of the acid component was increased. Next, while maintaining the temperature of the reaction vessel at 280°C, the pressure of the system was gradually reduced to below 0.5 hPa after 60 minutes. Under these conditions, the polycondensation reaction was carried out with stirring for 3 hours to obtain a polyester resin.

[0076] [Manufacturing of short fibers] A 225-pore, 0.5mm-diameter spinneret was used to form the core of polyethylene terephthalate with an intrinsic viscosity of 0.70 dl / g and the resulting polyester resin into the sheath. Melt spinning was performed at a spinning temperature of 280°C and a spinning speed of 776 m / min, with a discharge rate of 1771 g / min, a core-to-sheath mass ratio of 50 / 50, and a spinning temperature of 280°C. The obtained undrawn yarn was gathered to form a tow of 115 ktex and drawn at a drawing temperature of 76°C and a draw ratio of 4.0 times. Then, mechanical crimping was applied using a push-type crimper, and the fibers were cut to a length of 51 mm to obtain heat-adhesive core-sheath composite staple fibers with a fineness of 4.4 dtex.

[0077] [Preparation of dry-laid nonwoven fabric] The regular polyester fiber "121" (1.7T51) manufactured by Unitika Corporation was blended at a ratio of 70% by mass to 30% by mass of the resulting heat-adhesive core-sheath type composite fiber. After heat treatment, the basis weight of the nonwoven fabric was 50 g / m². 2 To achieve this, fibers were fed into a carding machine (Yamato Kiko, SC-500DI3HC) to create a web. Subsequently, a continuous heat treatment machine (Tsujii Dyeing Machine Industry, NFD-500E2) was used to process the web at an airflow of 57 m³. 3 Dry-laid nonwoven fabric was prepared by heat treatment at 200°C for 1 minute.

[0078] [Manufacturing of long fibers] A spinneret with 24 holes and a hole diameter of 0.4 mm was used to form the core of polyethylene terephthalate with an intrinsic viscosity of 0.74 dl / g and the sheath of the polyester resin obtained in Example 1. The mass ratio of the core to the sheath was set to 60 / 40, and melt spinning was performed at a spinning temperature of 288°C and a spinning speed of 3000 m / min. The obtained partially drawn yarn was stretched under conditions of a stretching temperature of 73°C, a heat setting temperature of 131°C, and a stretching ratio of 1.9 times to obtain a heat-adhesive core-sheath type composite long fiber with a fineness of 54 dtex.

[0079] Example 2 [Production of polyester resin, short fibers, dry-laid nonwoven fabrics, and long fibers] A slurry of terephthalic acid and ethylene glycol (molar ratio 1 / 1.6) was continuously supplied to an esterification reaction vessel, and the reaction was carried out under conditions of a temperature of 250°C and a pressure of 0.2 MPa, with a residence time of 8 hours to obtain esterified product A (terephthalic acid:ethylene glycol = 100:111 (molar ratio)). The heated and molten esterified product was placed in a polycondensation reaction vessel heated to 280°C. Following the addition of ε-caprolactone and 1,4-butanediol in the amounts shown in Table 1, a depolymerization reaction was carried out for 1 hour. Then, 6.0 × 10⁻⁶ 5-sulfosalicylic acid dihydrate (SS) was added as a polycondensation catalyst. -4 Moles of acid component were added, and the etherification reaction was carried out at atmospheric pressure at 280°C for 10 minutes. Next, while maintaining the temperature of the reaction vessel at 280°C, the pressure of the system was gradually reduced to 0.5 hPa or less after 60 minutes. Under these conditions, a polycondensation reaction was carried out with stirring for 3 hours to obtain a polyester resin. Furthermore, heat-adhesive core-sheath composite short fibers, dry nonwoven fabric, and core-sheath composite long fibers were obtained in the same manner as in Example 1, except that the polyester resin obtained in Example 2 was placed in the sheath portion.

[0080] Examples 3-9, Comparative Examples 1-5 [Production of polyester resin, short fibers, dry-laid nonwoven fabrics, and long fibers] Polyester resin was obtained by performing the same procedure as in Example 2, except that the amounts of ε-caprolactone, 1,4-butanediol, and 5-sulfosalicylic acid dihydrate (SS) added, and the etherification reaction conditions were changed as shown in Table 1. Furthermore, heat-adhesive core-sheath composite short fibers, dry nonwoven fabrics, and heat-adhesive composite long fibers were obtained in the same manner as in Example 1, except that the polyester resin obtained in each example was placed in the sheath portion.

[0081] Example 10 A polyester resin was obtained by performing the same procedure as in Example 2, except that isophthalic acid (IPA) was added in the amount shown in Table 1 instead of ε-caprolactone. Furthermore, a heat-adhesive core-sheath composite short fiber, a dry nonwoven fabric, and a heat-adhesive core-sheath composite long fiber were obtained in the same manner as in Example 1, except that the polyester resin obtained in Example 10 was placed in the sheath portion.

[0082] Example 11 A polyester resin was obtained by performing the same procedure as in Example 2, except that adipic acid (AD) was added in the amount shown in Table 1 instead of ε-caprolactone. Furthermore, a heat-adhesive core-sheath composite short fiber, a dry nonwoven fabric, and a heat-adhesive core-sheath composite long fiber were obtained in the same manner as in Example 1, except that the polyester resin obtained in Example 11 was placed in the sheath portion.

[0083] Example 12 A polyester resin was obtained by performing the same procedure as in Example 2, except that ε-caprolactone was not added as an acid component, and the amounts of 1,4-butanediol and 5-sulfosalicylic acid dihydrate (SS) added, and the etherification reaction conditions were changed as shown in Table 1. Furthermore, a heat-adhesive core-sheath composite short fiber, a dry nonwoven fabric, and a heat-adhesive core-sheath composite long fiber were obtained in the same manner as in Example 1, except that the polyester resin obtained in Example 12 was placed in the sheath portion.

[0084] Example 13 [Manufacturing of short-cut fibers] A 560-pore, 0.35mm-diameter spinneret was used to form the core of polyethylene terephthalate with an intrinsic viscosity of 0.70 dl / g and the sheath of the polyester resin obtained in Example 12. Melt spinning was performed at a spinning temperature of 272°C and a spinning speed of 790 m / min, with a discharge rate of 312 g / min, a core-to-sheath mass ratio of 50 / 50, and a spinning temperature of 272°C. The obtained undrawn yarn was gathered to form a 50ktex tow, which was then drawn at a drawing temperature of 74°C and a draw ratio of 3.4 times. Next, after applying an oil, the tow was squeezed to reduce its moisture content to approximately 18% by mass, and cut into 5mm lengths using a drum cutter to obtain a heat-adhesive core-sheath type composite short-cut fiber with a fineness of 2.2 dtex. [Preparation of wet-laid nonwoven fabrics] Next, the obtained heat-adhesive core-sheath type composite short-cut fiber is used as a binder fiber, and the main fiber is a short-cut fiber made of polyethylene terephthalate with a single fiber fineness of 1.6 dtex and a length of 5 mm (manufactured by Unitika Corporation). <n801>Using 1.6T5), the binder fibers / main fibers (mass ratio) were dispersed in water at a ratio of 40 / 60, and a paper-making web was obtained using a cylinder paper machine. Subsequently, a continuous heat treatment machine (Tsujii Dyeing Machine Industry, NFD-500E2) was used, with an airflow of 57 m³. 3 Wet-laid nonwoven fabric was prepared by heat treatment at 200°C for 1 minute.

[0085] Example 14 [Manufacturing of short fibers, production of dry-laid nonwoven fabrics] Using the polyester resin obtained in Example 12, melt spinning was performed using a spinneret with 120 pores and a pore diameter of 0.6 mm, under the conditions of a discharge rate of 210 g / min, a spinning temperature of 270°C, and a spinning speed of 850 m / min. The obtained undrawn yarn was gathered to form an 80ktex tow and drawn at a drawing temperature of 60°C and a draw ratio of 4.0 times. Then, mechanical crimping was applied using a push-type crimper, and the fibers were cut to a length of 51 mm to obtain heat-adhesive composite staple fibers with a fineness of 5.5 dtex. Using the obtained heat-adhesive composite short fibers, a dry nonwoven fabric was prepared in the same manner as described in Example 1.

[0086] Example 15 [Manufacturing of short-cut fibers, production of wet-laid nonwoven fabrics] Using the polyester resin obtained in Example 12, melt spinning was performed using a spinneret with 720 pores and a pore diameter of 0.25 mm, under the conditions of a discharge rate of 350 g / min, a spinning temperature of 275°C, and a spinning speed of 850 m / min. The obtained undrawn yarn was gathered to form a 50ktex tow, which was then drawn at a drawing temperature of 50°C and a draw ratio of 3.8 times. Next, after applying an oil, the tow was squeezed to reduce its moisture content to approximately 18% by mass, and then cut into 5mm lengths using a drum cutter to obtain a heat-adhesive core-sheath type composite short-cut fiber with a fineness of 1.7dtex. Using the obtained heat-adhesive core-sheath type composite short-cut fibers, a wet nonwoven fabric was prepared in the same manner as described in Example 13.

[0087] Comparative Example 6 A polyester resin was obtained by performing the same procedure as in Example 2, except that antimony trioxide (Sb) was used instead of 5-sulfosalicylic acid dihydrate (SS). Then, a heat-adhesive core-sheath composite short fiber and a dry-laid nonwoven fabric were obtained in the same manner as in Example 1.

[0088] Table 1 shows the manufacturing conditions for the polyester resins obtained in the examples and comparative examples, and Table 2 shows their characteristic values. Table 3 shows the evaluation of the fibers and nonwoven fabrics obtained from the polyester resins.

[0089] [Table 1]

[0090] [Table 2]

[0091] [Table 3]

[0092] As shown in Table 2, the polyester resins obtained in Examples 1 to 12 had aromatic dicarboxylic acids, aliphatic carboxylic acids, and glycol content within the range specified in the present invention. As shown in Table 3, the short fibers obtained in Examples 1 to 15 had good operability in fiber manufacturing, and the nonwoven fabrics obtained using these fibers as binder fibers had excellent thermal adhesion of the binder fibers, resulting in superior nonwoven fabric strength. Furthermore, the long fibers obtained in Examples 1 to 12 had good operability in fiber manufacturing and exhibited excellent strength and elongation.

[0093] On the other hand, in Comparative Example 1, the high content of ε-caprolactone and low content of aromatic dicarboxylic acid resulted in a resin with an excessively low melting point and poor heat resistance. As a result, the operability in the production of fibers (short fibers and long fibers) was poor. Due to the poor operability in fiber production, nonwoven fabric using the short fibers of Comparative Example 1 was not manufactured.

[0094] In Comparative Example 2, the proportion of 1,4-butanediol was too low, falling outside the scope of the present invention. While the operability in fiber (short and long fiber) production was good, and there were no problems with fiber strength and elongation, the nonwoven fabric obtained by using the resulting fibers as binder fibers had low thermal adhesion due to the high melting point of the polyester resin in Comparative Example 2, resulting in lower strength when used as a nonwoven fabric.

[0095] In Comparative Example 3, the proportion of 1,4-butanediol was excessively high, outside the scope of the present invention. While the operability in the production of fibers (short and long fibers) was good, and there were no problems with the strength and elongation of the fibers, the nonwoven fabric obtained by using the obtained fibers as binder fibers had low thermal adhesion due to the high melting point of the polyester resin in Comparative Example 3, resulting in lower strength when used as a nonwoven fabric.

[0096] In Comparative Example 4, the amount of 5-sulfosalicylic acid dihydrate (SS) added as a polymerization catalyst was insufficient, resulting in low production of triethylene glycol in the polyester resin, which fell outside the scope of the present invention. As a result, the operability in the production of fibers (short fibers and long fibers) was poor. Consequently, the resulting long fibers had low strength. Furthermore, due to the poor operability in fiber production, nonwoven fabric using the short fibers from Comparative Example 4 was not manufactured.

[0097] In Comparative Example 5, the amount of 5-sulfosalicylic acid dihydrate (SS) added as a polymerization catalyst was too high, resulting in excessive production of triethylene glycol in the polyester resin, which fell outside the scope of the present invention. As a result, the heat resistance of the resin was reduced, and the operability in the production of fibers (short fibers and long fibers) was poor. Consequently, the resulting long fibers had low strength. Furthermore, due to the poor operability in fiber production, nonwoven fabric using the short fibers from Comparative Example 5 was not manufactured.

[0098] In Comparative Example 6, antimony trioxide (Sb) was used as the polymerization catalyst instead of an organic sulfonic acid compound, resulting in reduced production of triethylene glycol, which fell outside the scope of the present invention. As a result, the operability in the production of fibers (short fibers and long fibers) was poor. Due to the poor operability in fiber production, the nonwoven fabric using the short fibers of Comparative Example 6 was not manufactured.

Claims

1. A polyester resin characterized by satisfying all of the following conditions (1) to (4). (1) The total acid content of the polyester resin is 70 mol% or more of aromatic dicarboxylic acid components, and the content of aliphatic carboxylic acid components is at most 30 mol%. (2) The glycol component constituting the polyester resin mainly consists of ethylene glycol and 1,4-butanediol, and the molar ratio of ethylene glycol to 1,4-butanediol is 90 / 10 to 30 / 70. (3) The glycol component contains diethylene glycol and triethylene glycol, with the diethylene glycol content being 1.0 mol% or more of the total glycol component, and the triethylene glycol content being more than 0.1 mol% and 5.0 mol% or less. (4) The sulfur content is 5 to 120 ppm.

2. The polyester resin according to claim 1, wherein the content of tetraethylene glycol in the total glycol components is 2.0 mol% or less.

3. The polyester resin according to claim 1 or 2, wherein the melting point is 150°C or higher and 230°C or lower.

4. A fiber made of the polyester resin described in any one of claims 1 to 3.

5. A method for producing a polyester resin according to any one of claims 1 to 3, characterized by comprising the step of adding an organic sulfonic acid compound to a raw material for a polyester resin.

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