Method for producing polyester resin and method for reducing tetrahydrofuran in polyester resin, as well as molded article and method for producing the same, and method for reducing tetrahydrofuran in molded article.

Abstract

To provide a polyester resin with a reduced THF content and a method for producing the same. [Solution] The polyester resin includes a first copolymer having acid components containing terephthalic acid at 50 mol% or more of the total amount of acid components and dimer acid at 2 to 50 mol% and alcohol components containing 1,4-butanediol at 50 mol% or more of the total amount of alcohol components, and the reduction rate of the THF outgassing generation, as shown in the following mathematical formula (1), is 99.78% or more. Reduction rate of THF outgassing amount (%) = {(THF outgassing amount before heat treatment - THF outgassing amount after heat treatment) / THF outgassing amount before heat treatment} × 100 (1) In the formula, "the amount of THF outgassing before heat treatment" and "the amount of THF outgassing after heat treatment" are values ​​measured by headspace gas chromatography after the resin was sealed in a bottle before and after 12 hours of heat treatment at 120°C under a pressure of 280 Pa and kept at 150°C for 1 hour.

Description

Related Application

[0001] This application claims the priority of Japanese Patent Application No. 2023-140521 filed on August 30, 2023, and incorporates by reference all the descriptions contained in the Japanese application.

Technical Field

[0002] The present disclosure relates to a method for producing a polyester resin and method for reducing tetrahydrofuran in polyester resin , as well as a molded body and a method for producing the same, and Method for reducing tetrahydrofuran in molded products relates to.

Background Art

[0003] Polybutylene terephthalate (which may be referred to as "PBT" in the present disclosure) and polybutylene naphthalate (which may be referred to as "PBN" in the present disclosure) are used in various applications such as members for electric and electronic devices, members for automobiles, packaging materials, and the like.

[0004] When producing PBT and PBN, tetrahydrofuran (which may be referred to as "THF" in the present disclosure) remains as a by-product in the produced resin. The remaining THF is generated as outgas. The generated THF outgas has an adverse effect on the processing of members for electric and electronic devices, reduces the durability of members for automobiles, contaminates the packaged goods, and also harms the health of workers.

[0005] In the automotive interior parts described in Patent Document 1, the amount of THF outgas generated is reduced by mixing a copolymer of ethene and (2-ethyl) hexyl acrylate with PBT.

[0006] Patent Document 2 aims to reduce the amount of THF outgas generated by using a biaxially stretched film containing modified PBT obtained by copolymerizing polytetramethylene glycol with PBT and polyethylene terephthalate.

Prior Art Documents

[0007] [Patent Document 1] Special Publication No. 2022-543761 [Patent Document 2] International Publication No. 2011 / 162198 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the method described in Patent Document 1, the THF content in PBT cannot be reduced. In the modified PBT described in Patent Document 2, THF outgassing of 220 μg / g or more occurs, and the reduction of THF content is insufficient.

[0009] Therefore, there is a need for polyester resins with reduced THF content. [Means for solving the problem]

[0010] According to the first perspective of this disclosure, A method for producing polyester resin comprising: a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components; and a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. It will be provided. The amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour after heat treatment is 0.5 μg or less per gram of the first copolymer. .

[0011] History of this disclosure 2 From one perspective, it contains an acid component comprising 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acid components, and an alcohol component comprising 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components. after heat treatment The first copolymer comprises 10% to 70% by mass, an acid component containing 80 mol% or more of terephthalic acid relative to the total amount of the acid component, and at least one alcohol component selected from the group consisting of 1,4-butanediol and polytetramethylene glycol. after heat treatment A molded article containing 30% to 90% by mass of a second copolymer is provided. The amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 50 μg or less per gram of the molded article.

[0012] History of this disclosure 3 From one perspective, the process involves a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% terephthalic acid and 10 mol% to 40 mol% dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components; a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours; and the acid component A method for producing a molded article is provided, comprising: a third step of preparing a second copolymer having an acid component containing 80 mol% or more of terephthalic acid relative to the total amount, and at least one alcohol component selected from the group consisting of a 1,4-butanediol component and a polytetramethylene glycol component; and a fourth step of forming a molded article by melt-extruding a mixture of 10% to 70% by mass of the first copolymer and 30% to 90% by mass of the second copolymer at a temperature of 200°C or higher. The amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 50 μg or less per gram of the molded article. History of this disclosure 4 From one perspective, the process involves a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% terephthalic acid and 10 mol% to 40 mol% dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components; a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours; and the first copolymer after heat treatment. Ko A method for producing a molded article is provided, comprising a third step of forming a molded article by melt-extruding a polymer at a temperature of 200°C or higher. The amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 0.5 μg or less per gram of the molded article.

[0013] History of this disclosure 5From one perspective, a method for reducing tetrahydrofuran in a polyester resin is provided, comprising: a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components; and a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. The amount of tetrahydrofuran generated when the first copolymer after heat treatment is heated at 150°C for 1 hour is 0.5 μg or less per gram of the first copolymer.

[0014] History of this disclosure 6 From one perspective, the process involves a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% terephthalic acid and 10 mol% to 40 mol% dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components; a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours; and the first copolymer after heat treatment. Ko A method for reducing tetrahydrofuran in a molded article is provided, comprising a third step of forming a molded article by melt-extruding a polymer at a temperature of 200°C or higher. The amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 0.5 μg or less per gram of the molded article. History of this disclosure 7According to the viewpoint, a first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid component and 10 mol% to 40 mol% of dimer acid component with respect to the total amount of the acid component, and an alcohol component containing 80 mol% or more of 1,4-butanediol component with respect to the total amount of the alcohol component; a second step of heat-treating the first copolymer at a pressure of 4,000 Pa or less and a temperature of 66 °C or higher and lower than the melting point of the first copolymer for 12 hours to 100 hours; a third step of preparing a second copolymer having an acid component containing 80 mol% or more of terephthalic acid component with respect to the total amount of the acid component, and at least one alcohol component selected from the group consisting of 1,4-butanediol component and polytetramethylene glycol component; and a fourth step of melt-extruding a mixture of 10% by mass to 70% by mass of the first copolymer and 30% by mass to 90% by mass of the second copolymer at a temperature of 200 °C or higher to form a molded body are provided. The tetrahydrofuran generated when the molded body is heated at 150 °C for 1 hour is 50 μg or less per 1 g of the molded body.

Advantages of the Invention

[0015] The polyester resin of the present disclosure has a low THF residue amount. Therefore, the amount of THF outgas to which an operator is exposed when using the polyester resin of the present disclosure can be reduced. Further, deterioration of the quality of the applied product due to the generation of THF outgas from the polyester resin can be suppressed.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a flowchart showing a method for producing the polyester resin of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing a method for producing the molded body of the present disclosure.

Embodiments for Carrying Out the Invention

[0017] According to the preferred embodiment of the first viewpoint described above, when the first copolymer, which has not been subjected to heat treatment at 50°C or higher, is heated at 150°C for 1 hour, the amount of tetrahydrofuran generated is 1 μg or less per gram of copolymer.

[0018] According to the preferred embodiment of the first viewpoint described above, the amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour is 0.5 μg or less per gram of copolymer.

[0019] According to the preferred embodiment of the first viewpoint described above, the acid component consists of a terephthalic acid component and a dimer acid component, or a 2,6-naphthalenedicarboxylic acid component and a dimer acid component. The alcohol component consists of a terephthalic acid component or a 2,6-naphthalenedicarboxylic acid component and a dimer acid component.

[0020] According to the preferred form of the first viewpoint described above, the number of carbon atoms in the dimer acid component is at least one selected from the group consisting of 44 and 36.

[0021] According to the preferred embodiment of the second viewpoint described above, the heat treatment is performed for 6 to 100 hours.

[0022] According to a preferred embodiment of the second viewpoint described above, the second step is performed before heating the first copolymer to 50°C or higher.

[0023] According to the preferred embodiment of the second viewpoint described above, the acid component consists of a terephthalic acid component and a dimer acid component, or a 2,6-naphthalenedicarboxylic acid component and a dimer acid component. The alcohol component consists of a 1,4-butanediol component.

[0024] According to the preferred form of the second viewpoint described above, the number of carbon atoms in the dimer acid component is at least one selected from the group consisting of 44 and 36.

[0025] According to the preferred embodiment of the fourth viewpoint described above, the amount of tetrahydrofuran generated when the second copolymer is heated at 150°C for 1 hour is 150 μg to 600 μg per gram of polyester resin.

[0026] According to a preferred embodiment of the fourth viewpoint described above, the molded body has at least one shape selected from a sheet shape, a film shape, and a container shape.

[0027] According to preferred embodiments of the third and fourth viewpoints described above, electrical and electronic equipment components are provided, including molded bodies of the third and fourth viewpoints.

[0028] According to preferred embodiments of the third and fourth viewpoints described above, an automotive component including the molded articles of the third and fourth viewpoints is provided.

[0029] According to preferred embodiments of the third and fourth viewpoints described above, a packaging material is provided that includes the molded articles of the third and fourth viewpoints.

[0030] According to a preferred embodiment of the fifth viewpoint described above, in the third step, the mixture is formed into at least one shape selected from a sheet shape, a film shape, and a container shape.

[0031] In this specification and in the claims, each acid component and each alcohol component may also include derivatives thereof. For example, an acid component may also include a derivative of the acid component (e.g., an ester).

[0032] A polyester resin according to the first embodiment of this disclosure will be described. The polyester resin referred to in this disclosure also includes molded articles thereof (e.g., polyester films, containers, packaging, etc.). In this disclosure, polymers may also include copolymers composed of two or more monomer components, and crosspolymers.

[0033] The polyester resin of this disclosure can take various forms. For example, the polyester resin of this disclosure can be in the form of pellets, sheets, films, containers, packaging, etc.

[0034] Pellet refers to a material created by cutting stranded polyester resin into granular pieces. The mass of 100 pellets can be, for example, 2g to 3g.

[0035] In this disclosure, "sheet" refers to a molded article having a shape in which the thickness is thin compared to the dimensions in other directions. In this disclosure, "film" refers to a molded article having a shape in which the thickness is made extremely thin by heat stretching a sheet.

[0036] In the following, the total amount of a component may mean the total number of moles of the monomers that form the basis of that component.

[0037] The polyester resin according to the first embodiment is a first copolymer obtained by polymerizing (A) an acid component and (B) an alcohol component. The polyester resin according to the first embodiment has PBT or PBN as its main structure.

[0038] In this disclosure, (A) the acid component may include polycarboxylic acid components which are compounds having multiple carboxyl groups and / or derivatives thereof. In addition, (B) the alcohol component may include polyol components which are compounds having multiple hydroxyl groups (polyhydroxy compounds) and / or derivatives thereof.

[0039] [(A) Acid component] (A) The acid component includes aromatic dicarboxylic acid components and dimer acid components. Examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, 2,5-franzicarboxylic acid, 2,4-franzicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and 9,9-bis(2-carboxyethyl)fluorene. Among these, terephthalic acid or 2,6-naphthalenedicarboxylic acid are particularly preferred.

[0040] The aromatic dicarboxylic acid component can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, relative to the total amount of component (A). If the aromatic dicarboxylic acid component is less than 50 mol%, the properties of the resulting polyester resin will be lost. The aromatic dicarboxylic acid component can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less, relative to the total amount of component (A).

[0041] Dimer acids are dicarboxylic acid compounds obtained by dimerizing unsaturated fatty acids having 10 to 30 carbon atoms. Dimer acids are at least one selected from the group consisting of dimerized dicarboxylic acids with 36 and 44 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms, such as oleic acid and linoleic acid, and unsaturated fatty acids with 22 carbon atoms, such as erucic acid, and their ester-forming derivatives. Dimer acids in which the unsaturated double bond remaining after dimerization is saturated by hydrogenation are called hydrogenated dimer acids. Hydrogenated dimer acids can be suitably used in terms of reaction stability, flexibility, and impact resistance. Dimer acids are usually obtained as a mixture of compounds having linear-branched structures, alicyclic structures, etc., and although the content of these varies depending on the manufacturing process, the content of these is not particularly limited. Among these, dimer acids with 44 carbon atoms are preferred because they can reduce the amount of THF outgassing more significantly.

[0042] The dimer acid component can be, for example, 2 mol% or more, 5 mol% or more, 8 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, or 35 mol% or more, relative to the total amount of component (A). If the dimer acid component is less than 2 mol%, the amount of THF outgassing from the polyester resin will increase. Preferably, the dimer acid component is 50 mol% or less, relative to the total amount of component (A). The dimer acid component can be, for example, 45 mol% or less, 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, 10 mol% or less, or 5 mol% or less, relative to the total amount of component (A). If the dimer acid component exceeds 50 mol%, the heat resistance of the polyester resin will decrease.

[0043] (A) The acid component may contain acid components other than aromatic dicarboxylic acid components and dimer acid components, to the extent that it does not alter the essential properties of the polyester resin of this disclosure. Examples of other acid components include aliphatic dicarboxylic acid components such as succinic acid, glutaric acid, adipic acid, pyremic acid, suberic acid, azelaic acid, and sebacic acid; and alicyclic dicarboxylic acid components such as 1,2-,1,3-,1,4-cyclohexanedicarboxylic acid and 1,4-,1,5-,2,6-,2,7-decahydronaphthalenedicarboxylic acid. These acid components may be used individually or in combination of two or more types.

[0044] In the acid component of the first copolymer, the total amount of the aromatic dicarboxylic acid component and the dimer acid component can be 100 mol% relative to the total amount of component (A).

[0045] [(B) Alcohol content] (B) The alcohol component contains 1,4-butanediol.

[0046] The 1,4-butanediol component is 50 mol% or more, preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more, relative to the total amount of component (B). The 1,4-butanediol component can be 95 mol% or less, 90 mol% or less, or 85 mol% or less, relative to the total amount of component (B). The 1,4-butanediol component can be 100 mol% of the total amount of component (B). If the 1,4-butanediol component is less than 50 mol%, the properties of PBT or PBN will be lost.

[0047] (B) The alcohol component may include components other than the 1,4-butanediol component, to the extent that it does not alter the essential properties of the polyester resin of this disclosure. Examples of other alcohol components include ethylene glycol, 1,4-cyclohexanedimethanol, propylene glycol, hexanediol, octanediol, decanediol, ethylene oxide-added bisphenol A, ethylene oxide-added bisphenol S, trimethylolpropane, and the like. These alcohol components may be used individually or in combination of two or more types.

[0048] The polyester resin of this disclosure may contain known additives, to the extent that they do not alter the essential properties of the polyester resin of this disclosure. Examples of additives include polymerization catalysts, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, mold release agents, antioxidants, lubricants, plasticizers, pigments, dyes, and the like.

[0049] In the first embodiment, the amount of THF outgassing from the polyester resin is 1 μg or less (1 ppm or less) per 1 g of polyester resin when heated at 150°C for 1 hour in a state where the polyester resin has not undergone melt treatment after manufacturing, for example, in a pellet state, preferably 0.8 μg or less, more preferably 0.5 μg or less, even more preferably 0.4 μg or less, particularly preferably 0.3 μg or less, even more preferably 0.2 μg or less, and even more preferably 0.1 μg or less.

[0050] The amount of THF outgassing from the polyester resin according to the first embodiment is even lower in the molded state, such as a sheet formed by extrusion melting of pellets, or a film formed by heat stretching of a sheet, than in the pellet state. For example, when heated at 150°C for 1 hour, the amount of THF outgassing from the molded article can be 0.2 μg or less (0.2 ppm or less), preferably 0.1 μg or less (0.1 ppm or less), and more preferably below the detection limit, per gram of the molded article.

[0051] The amount of THF outgassing generated from the polyester resin of this disclosure can be measured, for example, by the headspace method.

[0052] The polyester resin disclosed herein reduces the amount of THF outgassing. This helps to suppress environmental pollution and reduce adverse effects on workers' health. Furthermore, it helps to suppress quality degradation of products to which the polyester disclosed herein is applied due to THF outgassing.

[0053] For example, when the polyester resin of this disclosure is used as a release agent in semiconductor manufacturing, the amount of THF outgassing is reduced, which improves the adhesion between the substrate film and the release layer. Furthermore, it can reduce the disruption of the soldering process caused by THF outgassing in the semiconductor manufacturing process. In addition, it can reduce the adverse effects of THF outgassing on the quality of the semiconductor itself.

[0054] The polyester resin disclosed herein exhibits low bleed-out, excellent long-term stability, and superior moldability. Therefore, the polyester resin disclosed herein can be widely used in various molded materials, such as components for electrical and electronic equipment, automotive components, or packaging materials.

[0055] The polyester resin disclosed herein has excellent transparency and flexibility, as well as high heat resistance.

[0056] The polyester resin according to the first embodiment can be mixed with other polyester resins and used as a modifier to reduce THF outgassing. For example, as shown in the third and fourth embodiments described later, the amount of THF outgassing from the molded article can be reduced by molding a mixture of a THF-containing polyester resin and the polyester resin according to the first embodiment.

[0057] In the polyester resins disclosed herein, the molecular structure, crystal structure, etc., may be unknown, and it may be impossible or impractical to directly identify the polyester resins disclosed herein by their composition, structure, properties, etc. In such cases, the polyester resins disclosed herein should be permitted to be identified by their manufacturing method.

[0058] As a second embodiment of this disclosure, a method for producing polyester resin according to the first embodiment will be described. Figure 1 shows a flowchart of the method for producing polyester resin according to the second embodiment.

[0059] A method for producing a polyester resin according to the second embodiment may include a first step (S11) of preparing a first copolymer, and a second step (S12) of heat-treating the first copolymer obtained in the first step under reduced pressure.

[0060] The first copolymer prepared in the first step may be a commercially available polyester resin having the composition shown in the first embodiment. Below, a method for producing the first copolymer (polyester resin) as the first step will be described.

[0061] The first step is a step of polymerizing the monomer, that is, a step of polycondensation of an acid and an alcohol. Polymerization in the first step is not particularly limited and can be carried out by known polymerization methods using known catalysts. The method for producing the polyester resin before the second step may be either a method of direct esterification using an unsubstituted polycarboxylic acid as a starting material, or a method of carrying out a transesterification reaction using an esterified product such as a dimethyl ester as a starting material. In direct esterification, the temperature at which the polymerization reaction is carried out becomes high, resulting in a large amount of 1,4-butanediol decomposition and THF outgassing, so it is preferable to carry out a transesterification reaction using an esterified product of a polycarboxylic acid. When producing the polyester resin before the second step, in order to obtain a sufficient reaction rate, it is desirable to carry out a transesterification reaction under atmospheric pressure using a known catalyst as the first step, and then carry out a polycondensation reaction under reduced pressure using a known catalyst as the second step.

[0062] The acids and alcohols used as raw materials for the polyester resin can be any of the compounds mentioned above. The amounts of acid and alcohol used can be appropriately set according to the acid and alcohol content ratios mentioned above.

[0063] A transesterification reaction can be carried out, for example, by charging each compound used as a polymerization raw material and other copolymer components used as needed into a reaction vessel equipped with a heating device, a stirrer, and a distillation tube, adding a reaction catalyst, and raising the temperature while stirring under an inert gas atmosphere at atmospheric pressure, while distilling off by-products such as methanol produced by the reaction. The reaction temperature can be 150°C to 230°C, preferably 160°C to 220°C. The reaction time can be about 3 to 7 hours.

[0064] It is desirable to use at least one metal compound as a catalyst for the transesterification reaction. Preferred metal elements include sodium, potassium, calcium, titanium, lithium, magnesium, manganese, zinc, tin, and cobalt. Among these, titanium compounds are preferred because they are highly reactive and produce a good color tone for the resulting resin. The amount of transesterification catalyst used is preferably 5 ppm to 1,000 ppm, and more preferably 10 ppm to 100 ppm, relative to the polyester resin produced.

[0065] Furthermore, it is desirable to add an equimolar or greater amount of a phosphorus compound with the transesterification catalyst after the transesterification reaction is completed to further proceed with the esterification reaction. For example, it is desirable to produce a polyester resin by carrying out a transesterification reaction using an ester compound of terephthalic acid and 1,4-butanediol, and then adding erucic acid together with a phosphorus compound to further proceed with the esterification reaction. Examples of phosphorus compounds include phosphoric acid, phosphorous acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trimethyl phosphite, triethyl phosphite, and tributyl phosphite. Of these, trimethyl phosphate is particularly preferred. The addition rate of the phosphorus compound can be 5 ppm to 1,000 ppm, preferably 20 ppm to 100 ppm, relative to the polyester resin produced.

[0066] Following the transesterification reaction, a polycondensation reaction can be carried out until the desired molecular weight is achieved. The polycondensation reaction can be carried out, for example, by adding a polymerization catalyst to a reaction vessel containing the product after the transesterification reaction, and then gradually increasing the temperature and reducing the pressure inside the reaction vessel. The pressure inside the vessel can be reduced from atmospheric pressure to 0.4 kPa or less, preferably 0.2 kPa or less. The temperature inside the vessel can be increased from 220°C to 230°C, and finally to 220°C to 240°C, preferably 228°C to 235°C, and after reaching a predetermined torque, the reaction product can be extruded from the bottom of the vessel and recovered. Typically, the reaction product can be extruded into water in a strand shape, cooled, and then cut to obtain a pellet-shaped polyester resin.

[0067] It is desirable to use at least one type of metal compound as a catalyst for the polycondensation reaction. Preferred metal elements include titanium, germanium, antimony, and aluminum. Among these, titanium compounds and germanium compounds are particularly preferred when producing optical resins because they are highly reactive and produce resins with excellent transparency and color. In particular, titanium compounds are highly reactive and less expensive than germanium compounds. Furthermore, since titanium is not classified as a heavy metal, titanium compounds can reduce the environmental impact. The addition rate of the polymerization catalyst is preferably 30 ppm to 1,000 ppm, and more preferably 50 ppm to 500 ppm, relative to the polyester resin produced.

[0068] The polyester resin disclosed herein may contain various additives as appropriate, depending on the application and molding purpose, such as antioxidants, heat stabilizers, lubricants, antistatic agents, plasticizers, UV absorbers, and pigments. These additives may be added at any stage, either the polymerization reaction step or the processing and molding step. Examples of antioxidants include hindered phenol antioxidants, phosphorus antioxidants, and sulfur antioxidants, with hindered phenol antioxidants being particularly suitable, and a content of approximately 100 ppm to 5,000 ppm is desirable. Furthermore, when forming a melt-extruded film, metal salts such as magnesium acetate, calcium acetate, and magnesium chloride may be added to stabilize the electrostatic adhesion of the cooling roll.

[0069] A solid-phase polymerization reaction may be carried out after the polycondensation reaction. The solid-phase polymerization reaction can increase the intrinsic viscosity of the polyester resin.

[0070] Next, in the second step, the polyester resin obtained in the first step is heat-treated under reduced pressure.

[0071] The pressure during the heat treatment is preferably 4,000 Pa or less, more preferably 3,000 Pa or less, even more preferably 2,000 Pa or less, even more preferably 1,000 Pa or less, particularly preferably 500 Pa or less, even more preferably 400 Pa or less, even more preferably 300 Pa or less, most preferably 200 Pa or less, and most preferably 100 Pa or less.

[0072] The heat treatment temperature is preferably 66°C or higher, and more preferably 70°C or higher. The heat treatment temperature can be 80°C or higher, 90°C or higher, 100°C or higher, or 110°C or higher. The heat treatment temperature is preferably below the melting point of the polyester resin, and more preferably below 150°C. If the heat treatment temperature exceeds the melting point of the polyester resin, fusion of the polyester resin will occur.

[0073] The heat treatment time can be, for example, 6 hours or more, 10 hours or more, 20 hours or more, 30 hours or more, 40 hours or more, or 50 hours or more. The heat treatment time can be, for example, 100 hours or less, 90 hours or less, 80 hours or less, 70 hours or less, 60 hours or less, 50 hours or less, 40 hours or less, 30 hours or less, or 20 hours or less.

[0074] When the heat treatment temperature in the second step is less than 100°C, the heat treatment time is 20 hours or more, preferably 30 hours or more, more preferably 40 hours or more, and even more preferably 50 hours or more. When the heat treatment temperature in the second step is 100°C or higher, the heat treatment time is 6 hours or more, preferably 8 hours or more, and more preferably 10 hours or more.

[0075] The second step can be performed by heat-treating the polyester resin in the form of pellets obtained in the first step, or by heat-treating the polyester resin in the form of a molded article such as a film. Preferably, the second step is performed in the form of pellets, continuously from the first step. By performing the heat treatment in the initial stage, the risk of workers being exposed to THF outgassing can be reduced, and the decrease in mechanical strength and hydrolysis of the polyester resin due to THF outgassing can be suppressed. Furthermore, when the polyester resin of this disclosure is blended with resins that have low resistance to THF outgassing, such as polypropylene or polycarbonate, the adverse effects on the blended resin can be reduced.

[0076] A method for manufacturing the polyester film described herein will be explained.

[0077] The polyester film of this disclosure can be manufactured according to a general method for manufacturing polyester films. For example, a method may be used in which a non-oriented polyester, obtained by melting a polyester resin and extruding it into a sheet, is stretched in the direction of travel using the speed difference of the rolls at a temperature above the glass transition temperature, then stretched in the width direction with a tenter, and then heat-treated. The thickness of the non-oriented polyester before stretching can be set considering the desired final thickness of the polyester film, the stretching ratio, the retardation of the resulting polyester film, etc.

[0078] According to the method for producing polyester resin of the second embodiment, it is possible to produce a polyester resin with a low amount of THF outgassing during molding. In particular, the THF content in the polyester resin can be reduced before molding. This reduces the adverse effects of THF outgassing on workers handling the polyester resin of this disclosure. It also reduces the adverse effects of THF outgassing on products to which the polyester resin of this disclosure is applied.

[0079] A molded body according to a third embodiment of this disclosure will be described.

[0080] A molded article according to the third embodiment of this disclosure is a molded article comprising a first copolymer, which is a polyester resin according to the first embodiment, and a second copolymer. The molded article may have at least one shape selected from, for example, a sheet shape, a film shape, and a container shape.

[0081] The above description applies to the polyester resin according to the first embodiment.

[0082] The second copolymer is a polyester resin having (C) an acid component and (D) an alcohol component. Component (D) includes at least one selected from the group consisting of a 1,4-butanediol component and a polytetramethylene glycol component.

[0083] In this disclosure, (C) the acid component may include polycarboxylic acid components which are compounds having multiple carboxyl groups and / or derivatives thereof. Furthermore, (D) the alcohol component may include polyol components which are compounds having multiple hydroxyl groups (polyhydroxy compounds) and / or derivatives thereof.

[0084] [(C) Acid component] (C) The acid component comprises at least one selected from the group consisting of terephthalic acid components and 2,6-naphthalenedicarboxylic acid components.

[0085] If terephthalic acid is the main component of component (C), the amount of terephthalic acid can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of component (C). If the amount of terephthalic acid is less than 50 mol%, the properties of polybutylene terephthalate will be lost. The amount of terephthalic acid can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less relative to the total amount of component (C). Component (C) can be 100 mol% terephthalic acid.

[0086] If the 2,6-naphthalenedicarboxylic acid component is the main component of component (C), the amount of the 2,6-naphthalenedicarboxylic acid component can be, for example, 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more relative to the total amount of component (C). If the amount of the 2,6-naphthalenedicarboxylic acid component is less than 50 mol%, the properties of polybutylene naphthalate will be lost. The amount of the naphthalenedicarboxylic acid component can be, for example, 98 mol% or less, 95 mol% or less, 92 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, or 65 mol% or less relative to the total amount of component (C). Component (C) can be 100 mol% of the 2,6-naphthalenedicarboxylic acid component.

[0087] (C) The acid component may contain acid components other than terephthalic acid and 2,6-naphthalenedicarboxylic acid, to the extent that it does not alter the essential properties of the polyester resin of this disclosure. Examples of other acid components include aromatic dicarboxylic acid components such as isophthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and 9,9-bis(2-carboxyethyl)fluorene; aliphatic dicarboxylic acid components such as succinic acid, glutaric acid, adipic acid, pyremic acid, suberic acid, azelaic acid, and sebacic acid; and alicyclic dicarboxylic acid components such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decahydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, and 2,7-decahydronaphthalenedicarboxylic acid. These acid components may be used individually or in combination of two or more types.

[0088] (C) The acid component may consist of at least one of the terephthalic acid component and the 2,6-naphthalenedicarboxylic acid component, with the total amount of other acid components being 100 mol%.

[0089] [(D) Alcohol content] (D) The alcohol component comprises at least one selected from the group consisting of 1,4-butanediol components and polytetramethylene glycol components.

[0090] The 1,4-butanediol component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more, relative to the total amount of component (D). The 1,4-butanediol component can be 95 mol% or less, 90 mol% or less, or 85 mol% or less, relative to the total amount of component (D). The 1,4-butanediol component can be 100 mol%, relative to the total amount of component (D). If the 1,4-butanediol component is less than 80 mol%, the properties of PBT or PBN will be lost.

[0091] The polytetramethylene glycol component may be present in an amount of 5 mol% or more, 10 mol% or more, or 15 mol% or more relative to the total amount of component (D). The polytetramethylene glycol component may be present in an amount of 30 mol% or less, 25 mol% or less, 20 mol% or less, 15 mol% or less, or 10 mol% or less relative to the total amount of component (D).

[0092] If component (D) contains a polytetramethylene glycol component, the remaining component (D) may be a 1,4-butanediol component.

[0093] (D) The alcohol component may include other alcohol components other than the 1,4-butanediol component and the polytetramethylene glycol component, to the extent that they do not alter the essential properties of the polyester resin of this disclosure. Examples of other alcohol components include the ethylene glycol component, the 1,4-cyclohexanedimethanol component, the propylene glycol component, the hexanediol component, the octanediol component, the decanediol component, the ethylene oxide-added bisphenol A component, the ethylene oxide-added bisphenol S component, the trimethylolpropane component, and the like. These other alcohol components may be used individually or in combination of two or more types.

[0094] Examples of the second copolymer include polybutylene terephthalate, polybutylene naphthalate, polybutylene terephthalate copolymerized with isophthalic acid, polybutylene terephthalate copolymerized with polytetramethylene glycol, and polyethylene terephthalate copolymerized with polytetramethylene glycol.

[0095] The amount of THF outgassing from the second copolymer can be 100 μg or more or 200 μg or more per 1 g of the second copolymer, provided that the second copolymer (polyester resin) has not been subjected to heat treatment above 50°C since its manufacture and is in its state before mixing with the first copolymer, for example, when the second copolymer is in a pellet state. The amount of THF outgassing from the second copolymer can be 3,000 μg or less or 2,000 μg or less per 1 g of the second copolymer, provided that the second copolymer (polyester resin) has not been subjected to heat treatment above 50°C since its manufacture and is in its state before mixing with the first copolymer, for example, when the second copolymer is in a pellet state. Preferably, the amount of tetrahydrofuran generated when the second copolymer is heated at 150°C for 1 hour is 150 μg to 600 μg per gram of the second copolymer.

[0096] In the molded article according to the third embodiment, the first copolymer may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, relative to the mass of the molded article according to the third embodiment. The first copolymer may be 70% by mass or less, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, or 10% by mass or less, relative to the mass of the molded article according to the third embodiment.

[0097] In the molded article according to the third embodiment, the second copolymer may be 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more, relative to the mass of the molded article according to the third embodiment. The second copolymer may be 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, or 50% by mass or more, relative to the mass of the molded article according to the third embodiment.

[0098] In the molded article according to the third embodiment, the total amount of the first copolymer and the second copolymer can be 100% by mass.

[0099] The amount of THF outgassing from the molded body according to the third embodiment is 50 μg or less (50 ppm or less) per gram of the molded body when the molded body is heated at 150°C for 1 hour, preferably 40 μg or less, more preferably 30 μg or less, even more preferably 20 μg or less, particularly preferably 10 μg or less, even more preferably 5 μg or less, and most preferably below the detection limit.

[0100] The molded article according to the third embodiment may contain known additives to the extent that they do not alter the essential properties of the molded article according to the third embodiment. Examples of additives that can be used include polymerization catalysts, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, mold release agents, antioxidants, lubricants, plasticizers, pigments, dyes, and the like.

[0101] According to the molded article of the third embodiment, even when a second copolymer containing a large amount of THF is mixed in, the amount of THF outgassing is reduced. The second copolymer, which contains at least one selected from the group consisting of 1,4-butanediol and polytetramethylene glycol, will contain by-product THF when manufactured by conventional methods. However, when the first copolymer and the second copolymer are mixed and molded, the THF can be removed during molding. This makes it possible to reduce the amount of THF outgassing from the molded article of the third embodiment.

[0102] The molded article according to the third embodiment can be used, for example, as a component for electrical and electronic equipment, a component for automobiles, or a packaging material.

[0103] Examples of electrical and electronic equipment components include release films used in the manufacturing of various electrical and electronic equipment components; protective films used in various electrical and electronic equipment components; and various molded electrical and electronic equipment products such as switches, touch panels, sensors, and connectors.

[0104] Examples of automotive components include interior parts such as instrument panels, consoles, door trims, headrests, toolboxes, luggage boxes, and sun visors; exterior parts such as bumpers, rear spoilers, front lids, and fenders; decorative films for interior and exterior parts; and protective films for interior and exterior parts.

[0105] Examples of packaging materials include various packaging films such as container packaging materials, food packaging, pharmaceutical packaging, industrial chemical packaging, precision electronic component packaging, and pesticide packaging.

[0106] As a fourth embodiment of this disclosure, a method for manufacturing a molded article according to the third embodiment will be described. A method for producing a molded article according to the fourth embodiment of this disclosure includes a first step of preparing a first copolymer obtained by polymerizing an acid component containing 50 mol% or more of an aromatic dicarboxylic acid component and 2 mol% to 50 mol% of a dimer acid component relative to the total amount of the acid component, and an alcohol component containing 50 mol% or more of a 1,4-butanediol component relative to the total amount of the alcohol component, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher and below the melting point of the first copolymer. The method includes a third step of forming a mixture of the first copolymer in an amount of 5% to 95% by mass and the second copolymer in an amount of 5% to 95% by mass.

[0107] The first and second steps are the same as the first and second steps in the method for producing polyester resin according to the second embodiment. The second copolymer is a polyester resin containing at least one alcohol component selected from the group consisting of 1,4-butanediol components and polytetramethylene glycol components.

[0108] As the molding method in the third step, known molding methods such as injection molding, blow molding, extrusion molding, and lamination can be used. The molded article may have at least one shape selected from, for example, a sheet shape, a film shape, and a container shape.

[0109] Preferably, the amount of tetrahydrofuran generated when the molded body obtained in the third step is heated at 150°C for 1 hour is 50 μg or less per gram of the molded body. Preferably, the amount of tetrahydrofuran generated when the second copolymer is heated at 150°C for 1 hour is 150 μg to 600 μg per gram of the second copolymer.

[0110] Figure 2 shows a flowchart of the manufacturing method for the molded article according to the fourth embodiment.

[0111] The method for manufacturing a molded article according to the fourth embodiment may include the steps of: preparing a first copolymer (S21); heat-treating the first copolymer under reduced pressure (S22); preparing a second copolymer (S23); and mixing the first copolymer and the second copolymer (S24). That is, the method for manufacturing a molded article according to the fourth embodiment may include the step of mixing the first copolymer, which is a polyester resin according to the first embodiment, with the second copolymer. The order of S21 to S23 is not important.

[0112] For the method of producing the first copolymer, the method for producing polyester resin according to the second embodiment will be used with reference.

[0113] The second copolymer can be produced by known manufacturing methods depending on its composition. Alternatively, the second copolymer may be a commercially available product.

[0114] The process may include a step of heating and melting a mixture of the first copolymer and the second copolymer at a temperature of, for example, 200°C or higher, or 220°C or higher, to produce a molded article. Examples of molded articles include sheets, films, containers, and the like.

[0115] According to the method for manufacturing a molded article of the fourth embodiment, even if the second copolymer contains THF, the THF can be removed during the molding of the mixture with the first copolymer. As a result, even when using a polyester resin with a high THF content as the base, a molded article with low THF outgassing can be manufactured. [Examples]

[0116] The polyester resin and its manufacturing method, as well as the molded article and its manufacturing method, described below with examples. However, the polyester resin and its manufacturing method, as well as the molded article and its manufacturing method, are not limited to the following examples. The NMR analysis of the polyester resin composition was performed by the following method.

[0117] <Method for Analyzing Polyester Resin Composition by NMR> Using an FT-NMR apparatus (DPX400 type) manufactured by Bruker BioSpin, the polyester resin was dissolved in deuterated chloroform, mixed with tetramethylsilane as a standard, and the proton NMR spectrum was measured. The resin composition was calculated from the NMR spectrum.

[0118] [Test Examples 1 - 10] In Test Examples 1 - 10, as the acid, 100 mol% of dimethyl terephthalate or a mixture of dimethyl terephthalate and dimer acid which is a dimer of C22 erucic acid (manufactured by Croda, Pripol 1004) or dimer acid which is a dimer of C18 unsaturated fatty acid (manufactured by Croda, Pripol 1009) in a total of 100 mol%, and as the alcohol, a mixture containing 100 mol% of 1,4 - butanediol was charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser. After dissolving the mixture in a solvent at 190 °C, 35 ppm of tetra - n - butoxytitanium was added, and the temperature was raised from 190 °C to 225 °C over 3 hours while distilling the generated methanol out of the system to conduct a transesterification reaction. After the transesterification reaction was completed, the temperature was gradually raised from 225 °C to 235 °C over 60 minutes, and the pressure was gradually reduced from normal pressure to 0.2 kPa to end the reaction at a predetermined viscosity. Then it was extruded into cooling water and pelletized using a strand cutter. Tables 1 and 2 show the charged compositions of each test example and the polyester resin compositions analyzed by NMR. The intrinsic viscosity of the obtained polymer was 0.65 - 2.0 dl / g.

[0119] [Test Examples 11 - 13] In Test Examples 11 - 13, a polyester resin obtained by copolymerizing polybutylene terephthalate with polytetramethylene glycol was prepared. The manufacturing method was the same as that of Test Examples 1 - 10 except for the different compositions. Table 3 shows the charged compositions of each test example and the polyester resin compositions analyzed by NMR.

[0120] [Test Examples 14 - 21] In Test Examples 14 to 21, the manufacturing method was the same as in Test Examples 1 to 10, except that 100 mol% in total of dimethyl 2,6-naphthalenedicarboxylate and dimer acid (manufactured by Croda, Pripol 1004), which is a dimer of erucic acid C22, was used. Table 4 shows the charged composition of each test example and the polyester resin composition analyzed by NMR.

[0121] Next, the obtained pellets were heat-treated under the conditions shown in Tables 1 to 4. The heating in Test Example 6 was carried out under atmospheric pressure in a nitrogen atmosphere. The melting point of the polyester resin before the heat treatment was measured as follows. Also, the amount of THF outgas generated was measured as follows, and the reduction rate of the amount of THF outgas generated was calculated as follows.

[0122] <Measurement of melting point> Using 10 mg of the polyester resin, the melting point Tm was determined from the DSC curve measured at a heating rate of 10 °C / min using a scanning differential calorimeter DSC (manufactured by Perkin Elmer, DSC7).

[0123] <Measurement of the amount of THF outgas generated and calculation of the reduction rate of the amount of THF outgas generated> The amount of THF outgas generated was measured for the polyester resin before the heat treatment and the heat-treated polyester resin. The heat-treated polyester resin was not the polyester resin itself for which the amount of THF outgas generated was measured before the heat treatment, but the polyester resin of the same lot as before the heat treatment. The polyester resin was cryogenically pulverized to a powder of 30 to 50 mesh, 20 mg was sealed in a 25 ml vial, and held at 150 °C for 1 hour. Using a gas chromatograph GC-14A manufactured by Shimadzu Corporation, the amount of THF outgas generated was measured by headspace gas chromatography. The detection limit of the amount of THF outgas generated is 0.1 μg (0.1 ppm) per 1 g of the polyester resin.

[0124] The reduction rate of the amount of THF outgas generated was calculated by the following formula. The percentage reduction in THF outgassing is calculated as follows: (%) = {(THF outgassing before heat treatment - THF outgassing after heat treatment) / THF outgassing before heat treatment} × 100

[0125] The abbreviations used in Tables 1 to 5 are as follows: TPA: Terephthalic acid component DA(C44): Dimer acid component with 44 carbon atoms DA(C36): Dimer acid component with 36 carbon atoms NDCA:2,6-Naphthalenedicarboxylic acid component BD: 1,4-butanediol component PTMG: Polytetramethylene glycol component

[0126] [Table 1]

[0127] [Table 2]

[0128] [Table 3]

[0129] [Table 4]

[0130] From the results in Tables 1 to 4, in Test Example 1, where neither dimer acid nor polytetramethylene glycol was used as a monomer, the reduction in THF outgassing was small. Similarly, in Test Examples 11 to 13, where polytetramethylene glycol was used as a monomer, the reduction in THF outgassing was also small. On the other hand, in Test Examples 2 to 10, where dimer acid was used as a monomer, the amount of THF outgassing was significantly reduced. In particular, heating under reduced pressure reduced the amount of THF outgassing to near the detection limit. In Test Example 6, where heat treatment was performed under atmospheric pressure, the heating time was 10 times that of Test Example 3, but the amount of THF outgassing could not be reduced to the same extent as in Test Example 3. In Test Examples 4 to 5, the amount of THF outgassing could be reduced even at a heating temperature of 70°C. Dimer acid with 44 carbon atoms was able to reduce THF outgassing more effectively than dimer acid with 36 carbon atoms. Furthermore, in Test Examples 15-21, which used 2,6-naphthalenedicarboxylic acid and dimer acid as monomers, the amount of THF outgassing was significantly reduced, similar to Test Examples 2-10.

[0131] [Test Examples 22-25] The polyester resins from Test Examples 3 and 8 in pellet form were heat-treated and then molded into 100 mm thick sheets, and the amount of THF outgassing was measured. The sheet molding method involved using a T-die extruder, a common method for manufacturing polyester sheets, to melt-extrude the material at the molding temperatures shown in Table 5, and then winding it onto a cast roll heated to 20°C to obtain a sheet-like molded body. The method for measuring the amount of THF outgassing was the same as in Test Examples 1 to 21. In Table 5, "Not detectable" indicates that the amount was below the detection limit.

[0132] [Table 5] The results in Table 5 show that THF outgassing was not observed from the film-form polyester resin, regardless of the molding temperature.

[0133] [Test Examples 26-47] Sheets were formed by mixing the copolymers from Test Examples 2, 3, 7, 8, and 11-13 (referred to as "First Copolymer" in Table 6) after heat treatment with the polybutylene terephthalate from Test Example 1 (referred to as "Second Copolymer" in Table 5) after heat treatment. The amount of THF outgassing generated from the formed sheets was measured. No heat treatment above 50°C was performed after molding before measurement. Table 6 shows the mixing ratio (mass ratio) of the first copolymer and the second copolymer and the amount of THF outgassing generated.

[0134] For sheet molding, the first copolymer and the second copolymer were mixed in the mass ratio shown in Table 6, and the mixture was melt-extruded at a temperature of 250°C using a T-die extruder, a common method for manufacturing polyester sheets. The mixture was then wound onto a cast roll heated to 20°C to obtain a sheet-like molded body. In test examples where the two copolymers were not mixed, sheet formation was performed similarly using a single copolymer.

[0135] [Table 6]

[0136] As shown in Table 6, in Test Example 26, polybutylene terephthalate alone did not reduce THF outgassing even when formed into a sheet. Furthermore, in Test Examples 39-47, the amount of THF outgassing remained high even in mixtures of polyester resin containing polytetramethylene glycol and polybutylene terephthalate. On the other hand, in Test Examples 27-38, forming a sheet with polyester resin containing dimer acid significantly reduced THF outgassing. Even with polybutylene terephthalate containing 50% or more by mass of THF, the amount of THF outgassing during sheet molding could be reduced.

[0137] [Test Examples 48-63] Sheets were formed by mixing the copolymers from Test Examples 15-21 after heat treatment (referred to as "First Copolymer" in Table 7) with the polybutylene naphthalate from Test Example 14 after heat treatment (referred to as "Second Copolymer" in Table 7). The amount of THF outgassing generated from the formed sheets was measured. No heat treatment above 50°C was performed after molding before measurement. Table 7 shows the mixing ratio (mass ratio) of the first copolymer and the second copolymer and the amount of THF outgassing generated.

[0138] [Table 7]

[0139] As shown in Table 7, in Test Example 48, polybutylene naphthalate alone could not reduce THF outgassing even when formed into a sheet. Furthermore, in Test Examples 49-63, forming a sheet using polyester resin containing dimer acid components significantly reduced THF outgassing. Even with polybutylene naphthalate containing 50% or more THF by mass, THF outgassing could be reduced during sheet molding.

[0140] The polyester resin and method for producing the same described herein are explained based on the above embodiments and examples, but are not limited to the above embodiments and examples. Within the scope of the present invention and based on the fundamental technical concept of the present invention, various modifications, changes, and improvements can be made to each disclosed element (including the elements described in the claims, specification, and drawings). Furthermore, within the scope of the claims of the present invention, various combinations, substitutions, or selections of each disclosed element are possible.

[0141] Further issues, objectives, and embodiments (including modifications) of the present invention are also evident from the entire disclosure of the present invention, including the claims.

[0142] With respect to the numerical ranges described herein, any number or range that falls within that range should be interpreted as being specifically described herein, even if not otherwise stated.

[0143] Some or all of the above embodiments may also be described as follows, but are not limited to the following descriptions. Each of these descriptions may also be combined with the claims set forth in the claims. [Note 1] A method of use comprising adding the polyester resin according to the first embodiment to a polyester resin containing at least one selected from the group consisting of 1,4-butanediol and polytetramethylene glycol as an alcohol component. [Industrial applicability]

[0144] The polyester resin and method for producing the same described herein, as well as the molded article and method for producing the same, can be applied to various molded articles, and are particularly suitable for use in electrical and electronic equipment components, automotive components, or packaging materials.

Claims

1. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. Includes, A method for producing polyester resin, wherein the amount of tetrahydrofuran generated when the first copolymer after heat treatment is heated at 150°C for 1 hour is 0.5 μg or less per gram of the first copolymer.

2. The method for producing a polyester resin according to claim 1, wherein the heat treatment is performed under a pressure of 1,000 Pa or less and at a temperature of 80°C or higher and below the melting point of the first copolymer for 20 to 100 hours.

3. A first copolymer after heat treatment comprising 10% to 70% by mass, having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid relative to the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol relative to the total amount of alcohol components, A second copolymer after heat treatment comprising 30% to 90% by mass, having an acid component containing 80 mol% or more of terephthalic acid component relative to the total amount of acid components, and at least one alcohol component selected from the group consisting of 1,4-butanediol component and polytetramethylene glycol component, A molded article comprising, A molded body in which the amount of tetrahydrofuran generated when the molded body is heated at 150°C for 1 hour is 50 μg or less per gram of the molded body.

4. The molded article according to claim 3, wherein the first copolymer has a reduction rate of 99.78% or more in the amount of tetrahydrofuran (THF) outgassing represented by the following formula (1). The percentage reduction in THF outgassing is calculated as follows: (%) = {(THF outgassing before heat treatment - THF outgassing after heat treatment) / THF outgassing before heat treatment} × 100 ... Formula (1) However, in formula (1) above, the "amount of THF outgassing before heat treatment" and the "amount of THF outgassing after heat treatment" are values ​​obtained by cryopreserving and grinding the first copolymer before and after heat treatment at 120°C under a pressure of 280 Pa, respectively, passing the powder through a 30-50 mesh, sealing 20 mg of the powder in a 25 ml vial, holding it at 150°C for 1 hour, and then measuring it by headspace gas chromatography.

5. The molded article according to claim 4, wherein the amount of THF outgassing after heat treatment of the first copolymer is 1 μg or less per gram of the first copolymer.

6. The molded article according to claim 4, wherein the amount of THF outgassing after heat treatment of the first copolymer is 0.5 μg or less per gram of the first copolymer.

7. The molded article according to claim 4, wherein the amount of THF outgassing generated by the first copolymer before heat treatment is 219 μg to 464 μg per gram of the first copolymer.

8. The molded article according to claim 3, wherein the first copolymer is at least one selected from the group consisting of dimer acid components with 44 and 36 carbon atoms.

9. The molded article according to claim 3, wherein the amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour is 0.5 μg or less per gram of the first copolymer.

10. The molded article according to claim 3, wherein the amount of tetrahydrofuran generated when the second copolymer is heated at 150°C for 1 hour is 150 μg to 600 μg per gram of the second copolymer.

11. A component for electrical and electronic equipment, an automobile part, or a packaging material, comprising a molded article according to any one of claims 3 to 10.

12. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. A third step of preparing a second copolymer having an acid component containing 80 mol% or more of terephthalic acid component relative to the total amount of acid components, and at least one alcohol component selected from the group consisting of 1,4-butanediol component and polytetramethylene glycol component, A fourth step involves forming a molded body by melt-extruding a mixture of 10% to 70% by mass of the first copolymer and 30% to 90% by mass of the second copolymer at a temperature of 200°C or higher. Includes, A method for producing a molded article, wherein the amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 50 μg or less per gram of the molded article.

13. The method for producing a molded article according to claim 12, wherein in the second step, a heat treatment is performed for 20 to 100 hours at a temperature of 80°C or higher and below the melting point of the first copolymer under a pressure of 1,000 Pa or less.

14. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. A third step involves melt-extruding the first copolymer after heat treatment at a temperature of 200°C or higher to form a molded body, Includes, A method for producing a molded article, wherein the amount of tetrahydrofuran generated when the molded article is heated at 150°C for 1 hour is 0.5 μg or less per gram of the molded article.

15. The method for producing a molded article according to claim 14, wherein in the second step, a heat treatment is performed for 20 to 100 hours at a temperature of 80°C or higher and below the melting point of the first copolymer under a pressure of 1,000 Pa or less.

16. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. Includes, A method for reducing tetrahydrofuran in polyester resin, wherein the amount of tetrahydrofuran generated when the first copolymer is heated at 150°C for 1 hour after heat treatment is 0.5 μg or less per gram of the first copolymer.

17. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. A third step involves melt-extruding the first copolymer after heat treatment at a temperature of 200°C or higher to form a molded body, Includes, A method for reducing tetrahydrofuran in a molded body, wherein the amount of tetrahydrofuran generated when the molded body is heated at 150°C for 1 hour is 0.5 μg or less per gram of the molded body.

18. A first step of preparing a first copolymer having an acid component containing 60 mol% to 90 mol% of terephthalic acid and 10 mol% to 40 mol% of dimer acid based on the total amount of acid components, and an alcohol component containing 80 mol% or more of 1,4-butanediol based on the total amount of alcohol components, A second step involves heat-treating the first copolymer under a pressure of 4,000 Pa or less at a temperature of 66°C or higher but below the melting point of the first copolymer for 12 to 100 hours. A third step of preparing a second copolymer having an acid component containing 80 mol% or more of terephthalic acid component relative to the total amount of acid components, and at least one alcohol component selected from the group consisting of 1,4-butanediol component and polytetramethylene glycol component, A fourth step involves forming a molded body by melt-extruding a mixture of 10% to 70% by mass of the first copolymer and 30% to 90% by mass of the second copolymer at a temperature of 200°C or higher. Includes, A method for reducing tetrahydrofuran in a molded body, wherein the amount of tetrahydrofuran generated when the molded body is heated at 150°C for 1 hour is 50 μg or less per gram of the molded body.

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