Polyester resin and hollow molded bodies formed therefrom, and methods for manufacturing these.

Abstract

A polyester resin and hollow molded body are provided that maintain polymerization activity while reducing catalyst cost, cyclic trimer, and aluminum-based foreign matter. A polyester resin is characterized by containing an aluminum compound and a phosphorus compound, wherein the polyester resin satisfies the following (1) to (3): (1) The aluminum content in the polyester resin is 9 to 19 ppm by mass; (2) The phosphorus content in the polyester resin is 22 to 40 ppm by mass; (3) The molar ratio of phosphorus to aluminum in the polyester resin is 1.55 to 1.85 or more.

Description

Technical Field

[0001] This invention relates to a polyester resin, a hollow molded body formed therefrom, and a method for manufacturing the same. The polyester resin and the hollow molded body formed therefrom reduce the amount of catalyst containing aluminum compounds and phosphorus compounds, the amount of cyclic trimers and aluminum-based foreign matter in the polyester resin and the hollow molded body, while simultaneously improving thermal stability and reducing catalyst costs. Background Technology

[0002] Polyester resins, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), possess excellent mechanical and chemical properties. Depending on their specific characteristics, these resins are used in a wide range of applications, including fibers for clothing and industrial materials, packaging, magnetic tapes, optical films and sheets, bottles as hollow molded products, housings for electrical and / or electronic components, and other engineering plastic molded products. In particular, bottles made from saturated polyester resins such as PET are widely used for filling beverages such as juices, carbonated drinks, and soft drinks, as well as containers for eye drops and cosmetics, due to their excellent mechanical strength, heat resistance, transparency, and gas barrier properties.

[0003] For polyester resins that are representative polyester resins and whose main components are units derived from aromatic dicarboxylic acids and alkylene glycols, such as PET, oligomer mixtures such as bis(2-hydroxyethyl) terephthalate are produced by esterification or transesterification of terephthalic acid or dimethyl terephthalate and ethylene glycol, and then melt-polymerized using a catalyst under high temperature and vacuum.

[0004] Antimony compounds or germanium compounds have long been widely used as catalysts for polyester polymerization, particularly in the polymerization of polyester resins like these. Antimony trioxide, an example of an antimony compound, is inexpensive and possesses excellent catalytic activity. However, when used as a main component—that is, added in an amount sufficient to achieve a practical polymerization rate—it causes the precipitation of metallic antimony during polymerization, resulting in black spots and foreign matter on the polyester resin, contributing to surface defects in the film. Furthermore, when used as a raw material for hollow molded products, it is difficult to obtain hollow molded products with excellent transparency. For these reasons, polyester resins that are completely antimony-free or do not contain antimony as a main catalyst component are desirable.

[0005] Germanium compounds have been put into practical use as catalysts with excellent catalytic activity, other than antimony compounds, and without causing the aforementioned problems to polyester resins. However, germanium compounds have drawbacks, such as being very expensive and the tendency for them to distill out of the reaction system during polymerization, leading to changes in the catalyst concentration and making polymerization control difficult. Therefore, their use as the main component of a catalyst is problematic.

[0006] Polymerization catalysts that can replace antimony or germanium compounds have been studied, and titanium compounds, represented by tetraalkoxytitanate, have been proposed. However, polyester resins made using titanium compounds are prone to thermal degradation during melt molding, and there is also the problem of significant coloration of the polyester resin.

[0007] For these reasons, there is a desire for polymerization catalysts that use metals other than antimony, germanium, and titanium as the main metal component of the catalyst, and that produce polyester resins with excellent catalytic activity, excellent color and thermal stability, and excellent transparency of the molded product.

[0008] Catalyst systems formed from aluminum and phosphorus compounds have been disclosed and have attracted attention as novel polymerization catalysts (see, for example, Patent Documents 1 and 2).

[0009] By using the above-mentioned polymerization catalyst, polyester resins with good color tone, transparency, and thermal stability can be obtained. However, this method suffers from the problem of increased catalyst cost due to the large amount of catalyst added and the high cost of the phosphorus compounds used.

[0010] In addition, in order to obtain high-grade polyester resin while maintaining high polymerization activity, it is necessary to increase the amount of aluminum and phosphorus compounds used as catalysts, which results in the problem of increased catalyst cost.

[0011] Existing technical documents

[0012] Patent documents

[0013] [Patent Document 1] International Publication No. 2007 / 032325

[0014] [Patent Document 2] Japanese Patent Application Publication No. 2006-169432 Summary of the Invention

[0015] [The problem the invention aims to solve]

[0016] The present invention addresses the issues of the prior art described above and provides a polyester resin and a hollow molded body. Although a polymerization catalyst composed of aluminum and phosphorus compounds with metals other than antimony, germanium, and titanium as the main metal components is used, the catalyst cost can be reduced while maintaining polymerization activity, and there are fewer cyclic trimers and aluminum-based foreign matter.

[0017] [Technical means to solve the problem]

[0018] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that a method was provided to reduce the amount of aluminum in polyester resin and to achieve an appropriate molar ratio of phosphorus to aluminum, thus achieving the objective of the present invention.

[0019] When using polymerization catalysts such as antimony compounds and germanium compounds in polyester polymerization, the polymerization activity is usually proportional to the amount of catalyst added. However, for polymerization catalysts composed of aluminum and phosphorus compounds, the polymerization activity is not directly related to the amount of catalyst added because the complexation reaction between aluminum and phosphorus compounds affects the polymerization activity.

[0020] Here, the inventors analyzed the factors affecting the activity of a polymerization catalyst composed of aluminum and phosphorus compounds. The results showed that by reducing the amount of aluminum in the polyester resin and maintaining an appropriate molar ratio of phosphorus to aluminum, it is possible to reduce the amount of cyclic trimers and aluminum-based foreign matter in the polyester resin while suppressing catalyst costs, thus achieving excellent polymerization activity, and thus completing this invention.

[0021] That is, the present invention consists of the following components.

[0022] [1] A polyester resin, characterized in that it contains an aluminum compound and a phosphorus compound, wherein the polyester resin satisfies the following (1) to (3).

[0023] (1) The aluminum content in the polyester resin is 9 to 19 ppm by mass.

[0024] (2) The phosphorus content in the polyester resin is 22-40 ppm by mass.

[0025] (3) The molar ratio of phosphorus to aluminum in the polyester resin is more than 1.55 and less than 1.85.

[0026] [2] According to the polyester resin described in [1], wherein the content of aluminum element in the polyester resin, which is equivalent to aluminum-based foreign matter, is less than 1650 ppm by mass.

[0027] [3] The polyester resin according to [1] or [2] has an intrinsic viscosity (IV) of 0.56 dl / g or higher.

[0028] [4] The polyester resin according to any one of [1] to [3], wherein the phosphorus compound has a phosphorus element and a phenol structure in the same molecule.

[0029] [5] The polyester resin according to any one of [1] to [4], wherein the amount of cyclic trimer is 5000 ppm or less.

[0030] [6] A method for manufacturing a polyester resin according to any one of [1] to [5], comprising a first step of synthesizing a polyester or an oligomer thereof as an intermediate condensation polymer,

[0031] The second step of melt polymerization of the intermediate and

[0032] The third step involves solid-state polymerization of the melt-polymerized polyester.

[0033] After step 1 and before step 2, a solution A1 containing dissolved aluminum compound and a solution B1 containing dissolved phosphorus compound are added to the intermediate, wherein the amounts of solution A1 and solution B1 added satisfy the following conditions (4) to (6).

[0034] (4) The amount of aluminum added relative to the generated polyester resin is 9 to 19 ppm by mass.

[0035] (5) The amount of phosphorus added relative to the generated polyester resin is 25-50 ppm by mass.

[0036] (6) The molar ratio of the amount of phosphorus added in (5) to the amount of aluminum added in (4) is more than 2.00 and less than 2.40.

[0037] [7] According to the method for manufacturing polyester resin described in [6], the melt polymerization is carried out until the intrinsic viscosity (IV) is 0.56 to 0.65 dl / g, and then the solid-state polymerization is carried out until the intrinsic viscosity (IV) is 0.70 to 0.85 dl / g.

[0038] [8] In the method for manufacturing polyester resin according to [6] or [7], wherein the solution A1 is a diol solution and the maximum absorption wavelength of the solution A1 is 562.0 to 572.0 nm.

[0039] [9] According to the method for manufacturing polyester resin described in [8], wherein the solution B1 is a diol solution and the maximum absorption wavelength of the solution B1 is 460.0 to 463.0 nm.

[0040]

[10] According to the method for manufacturing polyester resin described in [9], wherein the diol solution B1 is prepared by heat-treating a phosphorus compound in a diol solution at 170 to 196°C for 125 to 240 minutes.

[0041]

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

[10] , wherein the solution A1 and the solution B1 are diol solutions, and the maximum absorption wavelength of the mixture of the diol solution A1 and the diol solution B1 is 559.5 to 560.8 nm.

[0042]

[12] A hollow molded body, characterized in that it is formed from a polyester resin containing an aluminum compound and a phosphorus compound, wherein the hollow molded body satisfies the following (7) to (9).

[0043] (7) The aluminum content in the hollow molded body is 9-19 ppm by mass.

[0044] (8) The phosphorus content in the hollow molded body is 22-40 ppm by mass.

[0045] (9) The molar ratio of phosphorus to aluminum in the hollow molded body is between 1.55 and 1.85.

[0046]

[13] According to the hollow molded body described in

[12] , the content of aluminum element in the hollow molded body, which is equivalent to aluminum-based foreign matter, is less than 1650 ppm by mass.

[0047]

[14] According to the hollow molded body described in

[12] or

[13] , wherein the phosphorus compound has a phosphorus element and a phenol structure within the same molecule.

[0048]

[15] The hollow molded body according to any one of

[12] to

[14] , wherein the amount of cyclic trimer is 6000 ppm or less.

[0049]

[16] A method for manufacturing a hollow molded body according to any one of

[12] to

[15] , characterized in that the hollow molded body is manufactured by molding the polyester resin according to any one of [1] to [5].

[0050] [Invention Effects]

[0051] The polyester resin of the present invention is a polyester resin obtained using a polymerization catalyst composed of aluminum compounds and phosphorus compounds, with metals other than antimony, germanium, and titanium as the main metal components. This polyester resin, in addition to possessing good color and thermal stability, maintains polymerization activity while suppressing the formation of cyclic trimers and aluminum-based foreign matter. Furthermore, it also addresses the problem of high catalyst cost, one of the issues in the manufacturing method of polyester resins formed using polymerization catalysts composed of aluminum compounds and phosphorus compounds.

[0052] Furthermore, the hollow molded body of the present invention is formed from a polyester resin obtained using a polymerization catalyst composed of aluminum compounds and phosphorus compounds, with metals other than antimony, germanium, and titanium as the main metal components. The hollow molded body of the present invention, in addition to possessing good color and thermal stability, maintains polymerization activity while suppressing the formation of cyclic trimers and aluminum-based foreign matter. Furthermore, it can also alleviate the problem of high catalyst cost, one of the issues in the manufacturing method of polyester resin formed using a polymerization catalyst composed of aluminum compounds and phosphorus compounds. Attached Figure Description

[0053]

【 Figure 1 The graph shows the relationship between the residual molar ratio of phosphorus to aluminum, the amount of aluminum-based foreign matter, and the polymerization time, obtained from the results of the examples and comparative examples.

[0054]

【 Figure 2 The graph shows the relationship between the maximum absorption wavelength of the mixture of phosphorus-containing ethylene glycol solution and aluminum-containing ethylene glycol solution and the amount of aluminum foreign matter and polymerization time, obtained from the results of the examples and comparative examples. Detailed Implementation

[0055] The present invention will now be described in detail.

[0056] The polyester resin of the present invention contains aluminum compounds and phosphorus compounds. Furthermore, the polyester resin satisfies the following (1) to (3):

[0057] (1) The aluminum content in the polyester resin is 9 to 19 ppm by mass.

[0058] (2) The phosphorus content in the polyester resin is 22-40 ppm by mass.

[0059] (3) The molar ratio of phosphorus to aluminum in the polyester resin is between 1.55 and 1.85.

[0060] It should be noted that in this instruction manual, ppm refers to 10 -4 The meaning of % (percentage of mass).

[0061] The polyester resin of the present invention comprises a polyester resin composed of at least one selected from polycarboxylic acids and their ester-forming derivatives and at least one selected from polyols and their ester-forming derivatives.

[0062] As the polyester resin of the present invention, the main polycarboxylic acid component is preferably dicarboxylic acid.

[0063] Polyester resins whose main polycarboxylic acid component is dicarboxylic acid refer to polyester resins that, relative to the total polycarboxylic acid components, preferably contain 70 mol% or more of dicarboxylic acid, more preferably 80 mol% or more, and even more preferably 90 mol% or more. It should be noted that when two or more dicarboxylic acids are used, their total content is preferably within the above-mentioned range.

[0064] Examples of dicarboxylic acids include saturated aliphatic dicarboxylic acids or their ester-forming derivatives, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, tetradecanedicarboxylic acid, hexadecanedicarboxylic acid, 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and dimer acids; and fumaric acid, maleic acid, and icariin. Unsaturated aliphatic dicarboxylic acids or their ester-forming derivatives, such as acids; aromatic dicarboxylic acids or their ester-forming derivatives, such as phthalic acid, isophthalic acid, terephthalic acid, 5-(alkali metal)sulfonyl isophthalic acid, biphenyl dicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, papoic acid, anthracene dicarboxylic acid, etc.

[0065] More preferably, the main polycarboxylic acid component is terephthalic acid or its ester-forming derivative, or naphthalic acid or its ester-forming derivative. Examples of naphthalic acid or its ester-forming derivative include 1,3-naphthalic acid, 1,4-naphthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 2,7-naphthalic acid, or their ester-forming derivatives.

[0066] The polyester resin whose main polycarboxylic acid component is terephthalic acid or its ester-forming derivatives or naphthalic acid or its ester-forming derivatives refers to a polyester resin that preferably contains 70 mol% or more of terephthalic acid or its ester-forming derivatives and naphthalic acid or its ester-forming derivatives relative to the total amount of all polycarboxylic acid components, more preferably contains 80 mol% or more of polyester resin, and even more preferably contains 90 mol% or more of polyester resin.

[0067] Particularly preferred are terephthalic acid, 2,6-naphthalenedicarboxylic acid, or their ester-forming derivatives. Other dicarboxylic acids may also be used as constituents if desired.

[0068] As polycarboxylic acids other than these dicarboxylic acids, polycarboxylic acids with three or more nucleotides or hydroxycarboxylic acids may be used in small quantities, preferably polycarboxylic acids with three to four nucleotides. Examples of polycarboxylic acids include ethanetricarboxylic acid, propanetricarboxylic acid, butanetetracarboxylic acid, pyromellitic acid, trimellitic acid, 3,4,3',4'-biphenyltetracarboxylic acid, and their ester-forming derivatives. The polycarboxylic acid with three or more nucleotides is preferably 20 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, relative to the total polycarboxylic acid composition. It should be noted that when two or more polycarboxylic acids with three or more nucleotides are used, their total amount is preferably within the above-mentioned range.

[0069] Examples of hydroxycarboxylic acids include lactic acid, citric acid, malic acid, tartaric acid, glycolic acid, 3-hydroxybutyric acid, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, 4-hydroxycyclohexanecarboxylic acid, or their ester-forming derivatives. The hydroxycarboxylic acid content is preferably 20 mol% or less relative to the total polycarboxylic acid composition, more preferably 10 mol% or less, and even more preferably 5 mol% or less. It should be noted that when two or more hydroxycarboxylic acids are used, their total content is preferably within the above-mentioned range.

[0070] Examples of ester-forming derivatives of polycarboxylic acids or hydroxycarboxylic acids include their alkyl esters, acyl chlorides, acid anhydrides, etc.

[0071] As the polyester resin of the present invention, the main polyol component is preferably a diol.

[0072] Polyester resins whose main polyol component is a diol refer to polyester resins that, relative to the total polyol component, preferably contain 70 mol% or more of a diol, more preferably 80 mol% or more, and even more preferably 90 mol% or more. It should be noted that when using two or more diols, their total content is preferably within the above range.

[0073] Examples of diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, triethylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,4-cyclohexyldiethanol, 1,4-cyclohexyldiethanol, 1,10-decanediol, and 1,12-decanediol. Alkylene glycols, such as dialkyldiols; aliphatic glycols, such as polyethylene glycol, polypropylene glycol, and polybutanediol; and aromatic glycols, such as hydroquinone, 4,4'-dihydroxybisphenol, 1,4-bis(β-hydroxyethoxy)benzene, 1,4-bis(β-hydroxyethoxyphenyl)sulfone, bis(p-hydroxyphenyl) ether, bis(p-hydroxyphenyl)sulfone, bis(p-hydroxyphenyl)methane, 1,2-bis(p-hydroxyphenyl)ethane, bisphenol A, bisphenol C, 2,5-naphthalenediol, and glycols to which ethylene oxide has been added.

[0074] Among these diols, alkylene glycols are preferred, and ethylene glycol, 1,3-propanediol, 1,4-butanediol, or 1,4-cyclohexanediol are more preferred. Furthermore, the molecular chain of the alkylene glycol may contain substituents or alicyclic structures, and two or more types may be used simultaneously.

[0075] As for polyols other than these diols, if in small quantities, polyols with 3 or more nucleotides may be used in combination, preferably polyols with 3 to 4 nucleotides. Examples of polyols with 3 or more nucleotides include trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, glycerol, and hexanetriol.

[0076] Relative to the total polyol composition, the polyols with three or more nucleotides are preferably 20 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less. It should be noted that when using two or more polyols with three or more nucleotides, their total amount is preferably within the above-mentioned range.

[0077] Furthermore, cyclic esters are also permitted to be used simultaneously. Examples of cyclic esters include ε-caprolactone, β-propiolactone, β-methyl-β-propiolactone, δ-valerolactone, glycolide, and lactide. Additionally, examples of ester-forming derivatives of polyols include esters of polyols with lower aliphatic carboxylic acids such as acetic acid.

[0078] The cyclic esters are preferably 20 mol% or less, more preferably 10 mol% or less, and even more preferably 5 mol% or less, relative to the sum of all polycarboxylic acid components and all polyol components. It should be noted that when two or more cyclic esters are used, their total amount is preferably within the above range.

[0079] The polyester resin of the present invention is preferably a polymer composed of only one monomer selected from polyethylene terephthalate, butylene terephthalate, propylene terephthalate, 1,4-cyclohexanedimethyl terephthalate, polyethylene naphthalate, butylene naphthalate, or propylene naphthalate, or a copolymer composed of two or more of the above monomers. The polyester resin of the present invention is more preferably a copolymer composed of at least one of the above monomers other than polyethylene terephthalate or polyethylene terephthalate, and particularly preferably polyethylene terephthalate. The copolymer composed of at least one of the above monomers other than polyethylene terephthalate preferably contains 70 mol% or more of a component derived from polyethylene terephthalate monomer, more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0080] For hollow molded bodies requiring transparency, the copolymer composed of at least one of the monomers other than polyethylene terephthalate and polyethylene terephthalate may also be a copolymer composed of isophthalic acid, neopentyl glycol, 1,4-cyclohexanediol, and polyethylene glycol, which are copolymer components capable of reducing the crystallinity of polyester.

[0081] <Polymerization Catalyst>

[0082] The polyester resin of the present invention comprises a catalyst amount derived from aluminum compounds and phosphorus compounds. That is, the polyester resin of the present invention is manufactured using a polymerization catalyst composed of aluminum compounds and phosphorus compounds.

[0083] <Aluminum Compounds>

[0084] There are no restrictions on the aluminum compounds constituting the above-mentioned polymerization catalyst, as long as they are soluble in solvents; known aluminum compounds can be used without limitation. Examples of aluminum compounds include, for instance, carboxylates such as aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, aluminum lactate, aluminum citrate, aluminum tartrate, and aluminum salicylate; inorganic acid salts such as aluminum chloride, aluminum hydroxide, aluminum hydroxychloride, aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, and aluminum phosphonate; aluminum alkoxides such as aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum isopropoxide, aluminum n-butoxide, and aluminum tert-butoxide; chelates such as aluminum acetylacetone, aluminum ethyl acetoacetate, and aluminum diisopropoxide of ethyl acetoacetate; organoaluminum compounds such as trimethylaluminum and triethylaluminum, as well as their partial hydrolysis products, reaction products of aluminum alkoxides or aluminum chelates with hydroxycarboxylic acids, alumina, ultrafine alumina, aluminum silicate, and complex oxides of aluminum with titanium, silicon, zirconium, alkali metals, or alkaline earth metals. Among these, preferably at least one is selected from carboxylates, inorganic acid salts, and chelates; more preferably at least one is selected from aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxychloride, and aluminum acetylacetonate; even more preferably at least one is selected from aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxychloride, and aluminum acetylacetonate; particularly preferably at least one is selected from aluminum acetate and basic aluminum acetate; and most preferably basic aluminum acetate.

[0085] The aluminum compound described above is preferably an aluminum compound soluble in solvents such as water and glycols. Solvents that can be used in this invention include water and alkylene glycols. Examples of alkylene glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, trimethylene glycol, di(trimethylene glycol), tetramethylene glycol, di(tetramethylene glycol), neopentyl glycol, etc. Preferably, it is selected from at least one of ethylene glycol, trimethylene glycol, and tetramethylene glycol, more preferably ethylene glycol. The effects of this invention can be significantly achieved by using a solution in which the aluminum compound is dissolved in water or ethylene glycol, and is therefore preferred.

[0086] The aluminum content in the polyester resin of the present invention needs to be 9 to 19 ppm by mass, preferably 10 to 19 ppm by mass, more preferably 10 to 17 ppm by mass, and even more preferably 12 to 17 ppm by mass. If the aluminum content is less than 9 ppm by mass, the polymerization activity may not be fully realized. On the other hand, if it is greater than 19 ppm by mass, it may not only increase the amount of aluminum-based foreign matter, but also increase the cost of the catalyst, and is therefore not preferred.

[0087] <Phosphorus compounds>

[0088] There are no particular limitations on the phosphorus compounds constituting the polymerization catalysts described above. However, the use of phosphonic acid compounds or phosphonophosphonic acid compounds is preferred as they significantly enhance the catalyst activity. Among these, the use of phosphonic acid compounds is even more preferred because it provides a particularly significant enhancement to the catalyst activity.

[0089] Among the aforementioned phosphorus compounds, phosphorus compounds having both phosphorus and phenol structures within the same molecule are preferred. There is no particular limitation as long as the phosphorus compound has both phosphorus and phenol structures within the same molecule. If one or more compounds selected from the group consisting of phosphonic acid compounds and hypophosphonic acid compounds having both phosphorus and phenol structures within the same molecule are used, the enhancement effect on catalyst activity is significant, and therefore preferred. If one or more phosphonic acid compounds having both phosphorus and phenol structures within the same molecule are used, the enhancement effect on catalyst activity is very significant, and therefore even more preferred.

[0090] In addition, as a phosphorus compound containing both phosphorus and phenolic elements within the same molecule, an example is P(=O)R. 1 (OR 2 (OR) 3 ) or P(=O)R 1 R 4 (OR 2 Compounds represented by ) etc. R 1 R represents a hydrocarbon group with 1 to 50 carbon atoms containing a phenolic portion, a hydrocarbon group containing a hydroxyl or halogen group, an alkoxy or amino substituent, or a hydrocarbon group with 1 to 50 carbon atoms in the phenolic structure. 4 R represents hydrogen, a hydrocarbon group with 1 to 50 carbon atoms, or a hydrocarbon group with 1 to 50 carbon atoms containing substituents such as hydroxyl, halogen, alkoxy, or amino groups. 2 R 3 Each of these groups independently represents hydrogen, a hydrocarbon group with 1 to 50 carbon atoms, or a hydrocarbon group with 1 to 50 carbon atoms containing substituents such as hydroxyl or alkoxy groups. The hydrocarbon group may also contain branched structures, alicyclic structures such as cyclohexyl, or aromatic ring structures such as phenyl or naphthyl. R 2 and R 4 The ends can be bonded together.

[0091] Examples of phosphorus compounds having both a phosphorus element and a phenolic structure within the same molecule include, for example, p-hydroxyphenylphosphonic acid, dimethyl p-hydroxyphenylphosphonate, diethyl p-hydroxyphenylphosphonate, diphenyl p-hydroxyphenylphosphonate, bis(p-hydroxyphenyl)phosphonic acid, methyl bis(p-hydroxyphenyl)phosphonate, phenyl bis(p-hydroxyphenyl)phosphonate, p-hydroxyphenylphosphonic acid, methyl p-hydroxyphenylphosphonate, phenyl p-hydroxyphenylphosphonate, and 3,5-di-tert-butyl-4-hydroxybenzylphosphonate dialkyl ester as shown in Formula 1. Among phosphorus compounds having both a phosphorus element and a phenolic structure within the same molecule, phosphorus compounds having a hindered phenolic structure are particularly preferred, especially 3,5-di-tert-butyl-4-hydroxybenzylphosphonate dialkyl ester as shown in Formula 1.

[0092]

Chemistry 1

[0093]

[0094] In (Formula 1), X 1 X 2 These represent hydrogen atoms and alkyl groups having 1 to 4 carbon atoms, respectively.

[0095] The above X 1 X 2 The alkyl group preferably has 1 to 4 carbon atoms, more preferably 1 to 2. In particular, the ethyl ester with 2 carbon atoms is preferred because it is readily available from commercially available Irganox 1222 (manufactured by BASF).

[0096] It should be noted that the phosphorus compound used in this invention is preferably the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester shown in Formula 1 above. Alternatively, modified versions containing 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester may also be used. Details regarding the modified versions are described below.

[0097] The phosphorus content in the polyester resin of the present invention is 22-40 ppm by mass, preferably 23-35 ppm by mass, and more preferably 24-32 ppm by mass. If the phosphorus content is less than 22 ppm by mass, there is a possibility that the catalyst activity may not be fully utilized, or that the amount of aluminum-based foreign matter or cyclic trimer may increase. On the other hand, if it is greater than 40 ppm by mass, there is a possibility that the polymerization activity may decrease and the amount of phosphorus compound added may increase, thus increasing the catalyst cost.

[0098] <Molar ratio of phosphorus to aluminum in polyester resin>

[0099] In the polyester resin of the present invention, controlling the molar ratio of phosphorus to aluminum (hereinafter referred to as the "residual molar ratio of phosphorus to aluminum" to distinguish it from the "added molar ratio of phosphorus to aluminum" described later) is also important, and it needs to be 1.55 to 1.85, preferably 1.57 to 1.82, and more preferably 1.59 to 1.77. As described above, the aluminum and phosphorus elements in the polyester resin of the present invention are derived from aluminum compounds and phosphorus compounds used as polymerization catalysts for the polyester resin, respectively. By using these aluminum compounds and phosphorus compounds in a specific ratio, a catalytically active complex can be functionally formed in the polymerization system, thereby achieving sufficient polymerization activity. If the residual molar ratio of phosphorus to aluminum is less than 1.55, the thermal stability and thermal oxidative stability decrease, and there is a possibility of poor coloring of the polyester resin, an increase in the amount of aluminum-based foreign matter, and an increase in the amount of cyclic trimers. On the other hand, if the residual molar ratio of phosphorus to aluminum is greater than 1.85, not only may the polymerization activity decrease, but the amount of phosphorus compound added becomes excessive, increasing the catalyst cost.

[0100] In this invention, in addition to the aforementioned aluminum and phosphorus compounds, other polycondensation catalysts such as antimony compounds, germanium compounds, and titanium compounds may also be used, provided that no problems arise in the properties, processability, color, and other aspects of the polyester resin obtained by the manufacturing method of this invention.

[0101] The antimony content in the polyester resin is preferably below 30 ppm by mass, the germanium content is preferably below 10 ppm by mass, and the titanium content is preferably below 3 ppm by mass. For the purposes of this invention, it is preferable to avoid using the other polycondensation catalysts mentioned above as much as possible.

[0102] For the polyester resin of the present invention, the content of aluminum element, which is equivalent to aluminum-based foreign matter, in the polyester resin is preferably 1650 ppm by mass or less, more preferably 1200 ppm by mass or less, further preferably 1100 ppm by mass or less, and even more preferably 1000 ppm by mass or less. Aluminum-based foreign matter refers to foreign matter derived from aluminum compounds used as polymerization catalysts, which are insoluble in the polyester resin of the present invention. If the content of aluminum-based foreign matter exceeds the above range, insoluble fine foreign matter will be generated in the polyester resin, which may lead to a deterioration in the quality of fibers, films, and molded products. In addition, it is also accompanied by the problem of increased filter clogging during the condensation process and the film-forming process when filtering polyester. The lower limit of the content of aluminum element, which is equivalent to aluminum-based foreign matter, is preferably 0 ppm by mass, but due to technical difficulties, it is about 200 ppm by mass.

[0103] It should be noted that, as can be seen from the aluminum content measured by the measurement method described later in the embodiments in this specification, this index is only used to relatively evaluate the amount of aluminum-based foreign matter, and does not represent the absolute value of the amount of aluminum-based foreign matter contained in the polyester resin.

[0104] The intrinsic viscosity (IV) of the polyester resin of the present invention is preferably 0.56 dl / g or higher, more preferably 0.65 to 0.80 dl / g, and even more preferably 0.70 to 0.75 dl / g. When the intrinsic viscosity of the polyester resin is less than the above range, the mechanical strength and impact resistance of the molded article may become insufficient. On the other hand, when the intrinsic viscosity of the polyester resin is greater than the above range, it is not preferred due to reduced economic efficiency.

[0105] The content of cyclic trimer (CT) in the polyester resin of the present invention is preferably 5000 ppm by mass or less, more preferably 4500 ppm by mass. The lower limit is not particularly limited, but due to technical difficulties, it is preferably 2700 ppm by mass or more. When the content of cyclic trimer is greater than 5000 ppm by mass, mold contamination during molding may increase.

[0106] [Method for manufacturing the polyester resin of the present invention]

[0107] As a method for manufacturing the polyester resin of the present invention, apart from using a polyester polymerization catalyst formed from aluminum compounds and phosphorus compounds as a catalyst, and adding a polymerization catalyst as described in (4) to (6) below, it can be carried out by a method with known steps.

[0108] As a method for manufacturing the polyester resin of the present invention, it is preferable to have a first step of synthesizing a polyester or an oligomer thereof as an intermediate condensate (lower-order condensate) and a second step of further condensing the intermediate, and more preferably a third step of having the first step, the second step and a solid-phase polymerization of the melt-polymerized polyester.

[0109] Furthermore, it is preferable to add a solution A1 containing dissolved aluminum compounds and a solution B1 containing dissolved phosphorus compounds to the intermediate after the first step and before the second step, as described in (4) to (6) below. Since the polycarboxylic acids and their ester-forming derivatives, the hydroxycarboxylic acids and their ester-forming derivatives that can be added in small amounts, and the cyclic esters that can be added in small amounts do not distill off the reaction system during polymerization, and remain as catalyst systems in the polyester resin produced by polymerization at almost 100% of the initially added amount, the mass of the "generated polyester resin" can be calculated based on the amount of these added.

[0110] (4) The amount of aluminum added relative to the generated polyester resin is 9 to 19 ppm by mass.

[0111] (5) The amount of phosphorus added relative to the generated polyester resin is 25 to 50 ppm by mass.

[0112] (6) The molar ratio of the amount of phosphorus added in (5) to the amount of aluminum added in (4) (hereinafter referred to as the "molar ratio of phosphorus to aluminum") is 2.00 or more and 2.40 or less.

[0113] The method for manufacturing polyester or its oligomers, which are used as low-order condensates (oligopolymers) in this invention, is not particularly limited.

[0114] The method for manufacturing the polyester resin of the present invention can be carried out using methods with conventionally known processes, except that it uses a polyester polymerization catalyst formed from aluminum and phosphorus compounds as a catalyst and adjusts the content of aluminum, phosphorus, and the molar ratio of phosphorus to aluminum in the polyester resin of the present invention to a specific range. For example, when manufacturing polyethylene terephthalate, it can be carried out by a direct esterification method, in which terephthalic acid and ethylene glycol and other desired copolymers are directly reacted, water is distilled off for esterification, and polycondensation is carried out under normal or reduced pressure; or by a transesterification method, in which dimethyl terephthalate and ethylene glycol and other desired copolymers are reacted, methanol is distilled off for transesterification, and polycondensation is carried out under normal or reduced pressure. Melt polymerization can be a batch polymerization method or a continuous polymerization method. Solid-state polymerization can be omitted, but it is preferred to do so. When solid-state polymerization is carried out, in order to promote crystallization before solid-state polymerization, the melt-polymerized polyester can be heated to crystallize after absorbing moisture, or water vapor can be directly blown onto the polyester fragments to heat and crystallize them. It should be noted that the amount (mass) of the generated polyester resin can be calculated based on the amount (mass) of the polycarboxylic acids, such as dicarboxylic acids, used as raw materials.

[0115] In any of these methods, the esterification or transesterification reaction can be carried out in one stage or in multiple stages. In the melt polymerization reaction, the number and size of the reactors, as well as the manufacturing conditions of each process, are not limited and can be appropriately selected. It can be carried out in one stage or in multiple stages, preferably in 2 to 5 stages, more preferably in 3 to 4 stages, and even more preferably in 3 stages. The melt polymerization reaction is preferably carried out in a continuous reaction apparatus. A continuous reaction apparatus refers to a method in which the reaction vessels for the esterification or transesterification reaction and the melt polymerization reaction vessel are connected by piping, and raw materials are continuously added to each reaction vessel without leaving them empty, transported through piping to the melt polymerization reaction vessel, and resin is extracted from the melt polymerization reaction vessel. It should be noted that in this case, continuous does not necessarily mean that raw materials are added and extracted continuously at all times; it can also be a small, sequential, intermittent operation, such as adding and extracting raw materials in amounts approximately 1 / 10 of the reaction vessel's capacity. When the polyester resin of the present invention is manufactured by multi-stage esterification or transesterification reaction and by continuous polymerization, it is preferable to add a solution A1 containing dissolved aluminum compounds and a solution B1 containing dissolved phosphorus compounds to the transport line between the final reaction tank (final esterification tank or final esterification tank) and the initial polymerization tank.

[0116] When the polymerization unit consists of three or more reactors in a continuous polymerization process (a three-stage polymerization method comprising an initial stage, an intermediate stage, and a final stage), the first stage is designated as the initial stage, the final stage as the final stage, and the stage from the second stage to the stage preceding the final stage is designated as the intermediate stage. The reaction conditions for the polymerization reaction in the intermediate stage are preferably between the reaction conditions of the initial stage and the reaction conditions of the final stage. It is preferable to smoothly distribute the increase in intrinsic viscosity achieved in each of these polymerization reaction steps.

[0117] Solid-phase polymerization method

[0118] To increase intrinsic viscosity, polyester resin manufactured by melt polymerization can be solid-phase polymerized. Solid-phase polymerization can be a batch polymerization method or a continuous polymerization method, but solid-phase polymerization is preferably carried out in a continuous apparatus, just like melt polymerization.

[0119] As a method for reducing CT levels in this invention, it is preferable to further polymerize the polyester resin manufactured by melt polymerization using solid-state polymerization. Solid-state polymerization is carried out by preparing the polyester obtained through the second step (melt polymerization) into a powder or granular form. The powder or granular form refers to polyester in fragment, granule, flake, or powder form, preferably fragment or granule.

[0120] The solid-state polymerization described above involves cooling granular polyester to below its melting point by heating under a flow of inert gas or under reduced pressure. The solid-state polymerization process can be carried out in one stage or in multiple stages.

[0121] The granular polyester supplied to the solid-state polymerization process can also be pre-crystallized by heating it to a temperature lower than that during solid-state polymerization before being supplied to the solid-state polymerization process.

[0122] Such pre-crystallization processes are typically carried out by heating the granular polyester in a dry state at a temperature of 120–200°C, preferably 130–180°C, for 1 minute to 4 hours. Alternatively, the granular polyester can be heated in a water vapor atmosphere, or in an inert gas atmosphere containing water vapor, or in an air atmosphere containing water vapor, at a temperature of 120–200°C for more than 1 minute.

[0123] As described, melt-polymerized polyester, for example, is fragmented and transported via conveying piping to a storage silo or solid-state polymerization process. When such fragments are transported, for example, using a forced low-density air conveying method, the surface of the melt-polymerized polyester fragments is subjected to significant impact forces due to collisions with the piping, resulting in a large amount of debris and film. Such debris and film promote polyester crystallization, and when present in large quantities, the transparency of the resulting molded article becomes very poor. Therefore, one preferred embodiment is to add a process for removing these debris and film.

[0124] There is no limitation on the method for removing the aforementioned debris and film. For example, methods such as vibrating screen processes, airflow classification processes, and gravity classification processes can be used as intermediate processes between the solid-phase polymerization process and the subsequent process set after the solid-phase polymerization process.

[0125] <Properties of Intermediates>

[0126] In this invention, the concentration of acid-terminated groups in the intermediate (lower-order condensate) prepared by the first step is preferably 400–1500 eq / ton, more preferably 500–1200 eq / ton. By setting the concentration of acid-terminated groups of the oligomer within the above range, the activity of the polymerization catalyst can be sufficiently initiated.

[0127] Furthermore, in this invention, the ratio (OH%) of the hydroxyl terminus to the total terminal group concentration of the aforementioned intermediate is preferably 45-70 mol%, more preferably 55-65 mol%. If the hydroxyl terminus ratio of the oligomer is less than 45 mol%, the polycondensation activity becomes unstable, and the amount of aluminum-based foreign matter may increase. On the other hand, if the hydroxyl terminus ratio of the oligomer is greater than 70 mol%, the polycondensation activity may decrease.

[0128] In the method for manufacturing the polyester resin of the present invention, melt polymerization is preferably carried out to an intrinsic viscosity of 0.56 to 0.65 dl / g, followed by solid-state polymerization to an intrinsic viscosity of 0.70 to 0.85 dl / g. More preferably, melt polymerization is carried out to an intrinsic viscosity of 0.58 to 0.62 dl / g, and solid-state polymerization is carried out to an intrinsic viscosity of 0.70 to 0.75 dl / g.

[0129] When the intrinsic viscosity after melt polymerization is less than 0.56 dl / g, a large amount of debris may be generated during air transport of the polyester resin due to friction between polyester resin particles or with the air transport pipes. On the other hand, when the intrinsic viscosity after melt polymerization is greater than 0.65 dl / g, economic efficiency may be reduced. When the intrinsic viscosity after solid-state polymerization is less than 0.70 dl / g, the CT amount may not be sufficiently reduced, and the formability of the hollow molded part may deteriorate. On the other hand, when the intrinsic viscosity after solid-state polymerization is greater than 0.85 dl / g, injection molding of the bottomed preform may become difficult.

[0130] When aluminum and phosphorus compounds are used as catalysts, they are preferably added in the form of suspensions or solutions, more preferably in solutions dissolved in solvents such as water or glycols, even more preferably in solutions dissolved in water and / or glycols, and most preferably in solutions dissolved in ethylene glycol.

[0131] In this invention, preferably after the esterification reaction or transesterification reaction is completed, a solution A1 containing dissolved aluminum compound and a solution B1 containing dissolved phosphorus compound are added such that the content (residual amount) of aluminum and phosphorus elements in the polyester resin meets the range of (1) to (3) above.

[0132] By adding solutions A1 containing dissolved aluminum compounds and B1 containing dissolved phosphorus compounds, such that the content (residual amount) of aluminum and phosphorus elements in the polyester resin meets the ranges of (1) to (3) above, a complex with catalytic activity can be functionally formed in the polymerization system, thus achieving sufficient polymerization activity. In addition, the formation of aluminum-based foreign matter can also be suppressed.

[0133] It should be noted that, even when the polymerization of the polyester resin is carried out under reduced pressure, almost 100% of the aluminum element in the aluminum compound that functions as a catalyst remains in the polyester resin produced through polymerization. That is, since the amount of aluminum compound hardly changes before and after polycondensation, when the amount of aluminum added relative to the intermediate is 9 to 19 ppm by mass, the aluminum content in the polyester resin is also 9 to 19 ppm by mass.

[0134] Furthermore, phosphorus compounds, which function as catalysts along with aluminum compounds, are discharged from the polyester resin during polymerization under reduced pressure, as part of the initial amount added to the catalyst system (approximately 10-40%). This removal ratio varies depending on the molar ratio of phosphorus to aluminum, the alkalinity or acidity of the added aluminum-containing glycol solution or phosphorus-containing glycol solution, and the method of adding the aluminum-containing and phosphorus-containing solutions (added after liquefaction or added separately). Therefore, it is preferable to appropriately set the amount of phosphorus compound added so that the phosphorus content in the polyester resin formed by the final product satisfies the above-mentioned (2).

[0135] In this invention, it is preferable to simultaneously add a solution A1 containing dissolved aluminum compounds and a solution B1 containing dissolved phosphorus compounds. A more preferred embodiment is to pre-mix the solutions A1 and B1 at the ratio to be added to the intermediate to prepare a mixture, and then add the liquefied mixture to the intermediate. This method allows for a more stable application of the effects of the invention. Examples of pre-liquefaction include mixing the solutions in a tank or merging the pipelines containing the catalyst during transport.

[0136] It should be noted that when adding to the reaction vessel, it is preferable to increase the stirring speed of the reaction vessel. When adding to the piping between reaction vessels, it is preferable to use an in-line mixer or similar equipment to ensure that the added catalyst solution is mixed quickly and uniformly.

[0137] Adding solutions A1 (containing dissolved aluminum compounds) and B1 (containing dissolved phosphorus compounds) separately can lead to the formation of more foreign matter caused by aluminum compounds, a decrease in crystallization temperature upon heating, an increase in crystallization temperature upon cooling, and insufficient catalyst activity. Simultaneous addition of aluminum and phosphorus compounds allows for the rapid and efficient formation of a complex that enhances polymerization activity. In contrast, separate additions result in insufficient complex formation, and aluminum compounds that fail to form a complex with the phosphorus compound may precipitate as foreign matter.

[0138] Furthermore, the solutions A1 containing dissolved aluminum compounds and B1 containing dissolved phosphorus compounds are preferably added after the esterification or transesterification reaction is completed, and more preferably added to the intermediate after the first step and before the second step. If added before the esterification or transesterification reaction is completed, the amount of aluminum-based foreign matter may increase.

[0139] When the polyester resin of the present invention is composed of at least one selected from polycarboxylic acids and their ester-forming derivatives and at least one selected from polyols and their ester-forming derivatives, the solution A1 in which the aluminum compound is dissolved is preferably a diol solution in which the aluminum compound is dissolved (hereinafter referred to as aluminum-containing diol solution A1), and the solution B1 in which the phosphorus compound is dissolved is preferably a diol solution in which the phosphorus compound is dissolved (hereinafter referred to as phosphorus-containing diol solution B1).

[0140] The maximum absorption wavelengths of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1 will be explained below. By controlling the maximum absorption wavelengths of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1 within a specific range, the polymerization activity can be stabilized, and a polyester resin of stable quality can be obtained. By controlling the maximum absorption wavelengths of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1 within a specific range, the Lewis acid / base characteristics of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1 can be controlled within a specific range. It is speculated that these Lewis acid / base characteristics will affect the complexation reaction between the aluminum compound and the phosphorus compound, and this complexation reaction will affect the polymerization activity.

[0141] <Maximum absorption wavelength of aluminum-containing glycol solution A1>

[0142] The aluminum-containing glycol solution A1 preferably has a maximum absorption wavelength of 562.0–572.0 nm, more preferably 569.0–572.0 nm. The maximum absorption wavelength of the aluminum-containing glycol solution A1 is obtained by measuring the absorption spectrum of the sample solution using a UV-Vis spectrophotometer after adding the acid dye Mordant Blue 13 to the aluminum-containing glycol solution A1. The detailed measurement method is described below.

[0143] Aluminum compounds and phosphorus compounds functionally form complexes with catalytic activity. To exert polymerization activity, the alkalinity of the aluminum compounds contained in the aluminum-containing glycol solution A1 is preferably within a specific range.

[0144] The maximum absorption wavelength of the aluminum-containing glycol solution A1 can be affected by the type and amount of aluminum compound used, the type of glycol, and the temperature, pressure, and time during the preparation of the glycol solution. For example, preferred embodiments include using an aluminum compound with an aluminum content within a specific range, or processing the aqueous glycol solution in the aluminum-containing glycol solution A1 under reduced pressure or vacuum.

[0145] When the maximum absorption wavelength of the aluminum-containing glycol solution A1 is less than the above-mentioned range, the alkalinity of the aluminum compound in the solution decreases, making it unable to fully form a complex with the phosphorus compound, potentially leading to reduced polymerization activity and an increase in the amount of aluminum-based foreign matter. On the other hand, when the maximum absorption wavelength is greater than the above-mentioned range, there are technical difficulties.

[0146] <Maximum absorption wavelength of phosphorus-containing diol solution B1>

[0147] The maximum absorption wavelength of the phosphorus-containing glycol solution B1 is preferably 458.0–465.0 nm, more preferably 460.0–463.0 nm, and even more preferably 461.0–462.0 nm. The maximum absorption wavelength of the phosphorus-containing glycol solution B1 is obtained by measuring the absorption spectrum of the sample solution using a UV-Vis spectrophotometer after adding an aqueous solution of the basic dye Bismarck Brown to the phosphorus-containing glycol solution B1. Detailed measurement methods are described below.

[0148] Phosphorus compounds and aluminum compounds functionally form complexes with catalytic activity. To maximize polymerization activity, the acidity of the phosphorus compounds contained in the phosphorus-containing glycol solution B1 is preferably within a specific range.

[0149] The maximum absorption wavelength of the phosphorus-containing glycol solution B1 is affected by the type and amount of phosphorus compound used, the type of glycol, and the temperature, pressure, and time during solution preparation. When the maximum absorption wavelength of the phosphorus-containing glycol solution B1 is greater than the above range, the acidity of the phosphorus compound decreases, preventing it from fully forming a complex with the aluminum compound. This causes the phosphorus compound to distill out of the polymerization system, leading to an increase in aluminum-based foreign matter, which is not preferable. Conversely, when the maximum absorption wavelength is less than the above range, the acidity of the phosphorus compound increases, resulting in stronger bonds with the aluminum compound, potentially leading to a significant decrease in polymerization activity.

[0150] <Heat Treatment of Phosphorus Compounds>

[0151] Furthermore, the phosphorus compound used in this invention is preferably a product that has undergone heat treatment in a solvent. The solvent used is not limited to any solvent selected from the group consisting of water and alkylene glycols. As for the alkylene glycol, a solvent in which the phosphorus compound has been dissolved is preferred, and glycols such as ethylene glycol, which are components of the polyester resin of this invention, are more preferably used. The heat treatment in the solvent is preferably performed from the point where the phosphorus compound dissolves, although incomplete dissolution is acceptable.

[0152] The heat treatment conditions described above are preferably a heat treatment temperature of 170–196°C, more preferably 175–185°C, and even more preferably 175–180°C. The heat treatment time is preferably 125–240 minutes, more preferably 140–210 minutes.

[0153] The concentration of phosphorus compound during the above heat treatment is preferably 3 to 10% by mass.

[0154] The above heat treatment can ensure that the acidity of the phosphorus compound in the glycol solution is constant. By using it in combination with aluminum compound, the polymerization activity can be improved while the amount of aluminum foreign matter generated by the polymerization catalyst can be reduced.

[0155] When using the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester of the phosphorus compound shown in (Formula 1) as the phosphorus compound, the structure of a portion of the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester of the phosphorus compound shown in (Formula 1) changes during the aforementioned heat treatment. For example, changes occur in the departure of the tert-butyl group, hydrolysis of the ethyl ester group, and the hydroxyethyl transesterification structure (transesterification structure with ethylene glycol). Therefore, in this invention, the phosphorus compound includes not only the 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester shown in (Formula 1) but also phosphorus compounds with structural changes. It should be noted that the departure of the tert-butyl group occurs significantly at the high temperature of the polymerization process.

[0156] The following examples illustrate nine phosphorus compounds in which a portion of diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate undergoes structural changes. The amounts of each phosphorus compound whose structure has changed in the diol solution can be quantified by P-NMR spectroscopy of that solution.

[0157]

Chemistry 2

[0158]

[0159] Therefore, the phosphorus compounds in this invention include, in addition to 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester, nine modified versions of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid dialkyl ester as shown in the above chemical formula.

[0160] <Maximum absorption wavelength of the mixture of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1>

[0161] The maximum absorption wavelength of the mixture of aluminum-containing glycol solution A1 and phosphorus-containing glycol solution B1 (hereinafter referred to as the "mixture") is preferably 559.0–560.9 nm, more preferably 559.5–560.8 nm, and even more preferably 559.7–560.6 nm. The maximum absorption wavelength of the mixture is obtained by measuring the absorption spectrum of the sample solution using a UV-Vis spectrophotometer after adding the acid dye Mordant Blue 13 to the mixture. Detailed measurement methods are described below.

[0162] By ensuring the maximum absorption wavelength of the mixture is within the aforementioned range, it is preferable to maintain a state that simultaneously enhances polymerization activity and suppresses aluminum-based foreign matter in the complexation reaction of the aluminum and phosphorus compounds. On the other hand, when the maximum absorption wavelength is greater than the aforementioned range, the alkalinity of the mixture increases. Since the polymerization system of polyester resin is acidic, if the mixture is added to the polymerization system, the aluminum compounds will neutralize and become foreignized with the carboxyl termini of the polyester resin, potentially increasing the amount of aluminum-based foreign matter. Conversely, when the maximum absorption wavelength is less than the aforementioned range, the alkalinity of the mixture is too low, the complexation of the aluminum and phosphorus compounds becomes too stable, and the polymerization activity may decrease.

[0163] [molded body]

[0164] The polyester resin of the present invention can be formed into hollow bodies, films, sheets, fibers, other bodies, etc. using conventional melt molding methods, or into coatings that can be applied to other substrates by melt extrusion.

[0165] Stretching the sheet formed from the polyester resin of the present invention in at least the uniaxial direction can improve its mechanical strength.

[0166] The stretch film formed from the polyester resin of the present invention is formed by forming a sheet obtained by injection molding or extrusion molding using any stretching method commonly used for PET stretching, such as uniaxial stretching, successive biaxial stretching, or simultaneous biaxial stretching. Alternatively, it can be formed into a cup or disc shape by air forming or vacuum forming.

[0167] In particular, the polyester resin of the present invention is suitable for use in hollow molded articles.

[0168] <Hollow Molded Body>

[0169] The hollow molded body of the present invention is a product formed from a polyester resin containing aluminum compounds and phosphorus compounds, preferably formed from the polyester resin of the present invention described above.

[0170] The hollow shaped body satisfies the following (7) to (9).

[0171] (7) The aluminum content in the hollow molded body is 9-19 ppm by mass.

[0172] (8) The phosphorus content in the hollow molded body is 22-40 ppm by mass.

[0173] (9) The molar ratio of phosphorus to aluminum in the hollow molded body is between 1.55 and 1.85.

[0174] In the molding process of the hollow molded body, the content of aluminum, the content of phosphorus, and the content of aluminum equivalent to aluminum-based foreign matter remain unchanged. That is, the hollow molded body and the polyester resin used to mold the hollow molded body have the same content of aluminum, phosphorus, and aluminum equivalent to aluminum-based foreign matter. The various physical properties of the hollow molded body, such as the content of aluminum, the content of phosphorus, the residual molar ratio of phosphorus to aluminum, and the content of aluminum equivalent to aluminum-based foreign matter, are preferably within the preferred range of the polyester resin of the present invention described above.

[0175] However, the amount of cyclic trimer (CT) increases only through the molding process of the hollow molded body. Therefore, the content of cyclic trimer in the hollow molded body of the present invention is preferably 6000 ppm by mass or less, more preferably 5500 ppm by mass or less. The content of cyclic trimer in the hollow molded body is preferably as low as possible, but due to technical difficulties, around 3000 ppm by mass is the limit. If the amount of CT in the hollow molded body increases, the mold surface becomes contaminated. Due to repeated molding, the contaminant accumulates on the mold surface, which may cause defects such as fogging of the resulting hollow molded body. To avoid these defects, it is necessary to increase the cycle of cleaning the mold, which reduces productivity.

[0176] This application claims priority to Japanese Patent Application No. 2020-156455, filed on September 17, 2020. The entire contents of the description of Japanese Patent Application No. 2020-156455, filed on September 17, 2020, are incorporated herein by reference.

[0177]

Example

[0178] The present invention will be described below through embodiments, but the present invention is not limited to these embodiments. It should be noted that the evaluation methods used in each embodiment and comparative example are as follows.

[0179] [Evaluation Method]

[0180] (1) Maximum absorption wavelength of aluminum-containing ethylene glycol solution a1

[0181] Add 4 mL of ethylene glycol and 0.3 mL of 1 mmol / L Mordant Blue 13 aqueous solution to a 6 mL sample vial, then add 0.1 mL of the aluminum-containing ethylene glycol solution a1 (described later). Cover the vial and shake to mix for 10 seconds until the solution is homogeneous. After allowing it to stand at room temperature (23°C) for 10 minutes, use a UV-Vis spectrophotometer to measure the absorption spectrum of the sample solution under the following conditions, and determine the maximum absorption wavelength of the aluminum-containing ethylene glycol solution a1. It should be noted that in this determination, room temperature refers to 15–30°C, and all operations were performed indoors within this temperature range.

[0182] Apparatus: Shimadzu UV-1800 UV-Vis spectrophotometer (manufactured by Shimadzu Corporation)

[0183] Spectral bandwidth: 1nm

[0184] Sample slot: Square slot (Material: Polymethyl methacrylate (PMMA), Optical path length: 10mm)

[0185] Control solution: ethylene glycol

[0186] Scan range: 400–700 nm

[0187] Scan speed setting: 0.05 sec

[0188] Scanning pitch: 0.2nm

[0189] Number of scans: 1

[0190] (2) Maximum absorption wavelengths of phosphorus-containing ethylene glycol solutions b1 and b1'

[0191] Add 4 mL of ethylene glycol and 0.3 mL of 1 mmol / L aniline brown aqueous solution to a 6 mL sample vial, then add 0.1 mL of phosphorus-containing ethylene glycol solution b1. Cover the vial and shake to mix for 10 seconds until the solution is homogeneous. After allowing it to stand at room temperature (23℃) for 10 minutes, use a UV-Vis spectrophotometer to measure the absorption spectrum of the sample solution under the following conditions, and determine the maximum absorption wavelength of the phosphorus-containing ethylene glycol solution b1. It should be noted that in this determination, room temperature refers to 15–30℃, and all operations were performed indoors within this temperature range.

[0192] Apparatus: Shimadzu UV-1800 UV-Vis spectrophotometer (manufactured by Shimadzu Corporation)

[0193] Spectral bandwidth: 1nm

[0194] Sample slot: Square slot (Material: PMMA, Optical path length: 10mm)

[0195] Control solution: ethylene glycol

[0196] Scan range: 400–700 nm

[0197] Scan speed setting: 0.05 sec

[0198] Scanning pitch: 0.2nm

[0199] Number of scans: 1

[0200] In addition, except for changing the phosphorus-containing ethylene glycol solution b1 to the phosphorus-containing ethylene glycol solution b1', the maximum absorption wavelength of the phosphorus-containing ethylene glycol solution b1' was determined using the same evaluation method as described above.

[0201] (3) The maximum absorption wavelength of the mixture of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1 or b1'

[0202] Add 4 mL of ethylene glycol and 0.3 mL of 1 mmol / L Mordant Blue 13 aqueous solution to a 6 mL sample vial. Then add 0.1 mL of a mixture of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1 or b1'. Cover the vial and shake to mix for 10 seconds until the solution is homogeneous. After standing at room temperature (23°C) for 10 minutes, use a UV-Vis spectrophotometer to measure the absorption spectrum of the sample solution under the following conditions and determine the maximum absorption wavelength. The mixing ratio of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1 or b1' in the above mixture is the same as the mixing ratio of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1 or b1' in each example. It should be noted that in this determination, room temperature refers to 15–30°C, and all operations are performed indoors within this temperature range.

[0203] Apparatus: Shimadzu UV-1800 UV-Vis spectrophotometer (manufactured by Shimadzu Corporation)

[0204] Spectral bandwidth: 1nm

[0205] Sample slot: Square slot (Material: PMMA, Optical path length: 10mm)

[0206] Control solution: ethylene glycol

[0207] Scan range: 400–700 nm

[0208] Scan speed setting: 0.05 sec

[0209] Scanning pitch: 0.2nm

[0210] Number of scans: 1

[0211] (4) Intrinsic viscosity (IV) of polyester resin

[0212] The polyester resins after melt polymerization and solid-phase polymerization were dissolved in a mixed solvent of p-chlorophenol / 1,1,2,2-tetrachloroethane (3 / 1 by mass) and measured at 30°C.

[0213] (5) The aluminum content in polyester resin

[0214] Polyester resin was weighed in a platinum crucible, carbonized in an electric furnace, and then ashed in a muffle furnace at 550°C for 8 hours. The ashed sample was dissolved in 1.2M hydrochloric acid to prepare a sample solution. The concentration of aluminum in the solid-state polymerized polyester resin was determined by high-frequency inductively coupled plasma atomic emission spectrometry.

[0215] Device: SPECTRO CIROS-120

[0216] Plasma power: 1400W

[0217] Plasma gas: 13.0 L / min

[0218] Assist gas: 2.0 L / min

[0219] Atomizer: Cross Atomizer

[0220] Fog chamber: Cyclone chamber

[0221] Measurement wavelength: 167.078nm

[0222] (6) The phosphorus content in polyester resin

[0223] The solid-state polymerized polyester resin was wet-decomposed under sulfuric acid, nitric acid, and perchloric acid, and then neutralized with ammonia. Ammonium molybdate and hydrazine sulfate were added to the adjusted solution, and the absorbance at 830 nm was measured using a UV-Vis spectrophotometer (Shimadzu UV-1700). The phosphorus concentration in the solid-state polymerized polyester resin was determined using a pre-prepared calibration curve.

[0224] (7) Aluminum-based foreign matter quantity

[0225] 30g of the solid-phase polymerized polyester resin and 250mL of a 3 / 1 (mass ratio) p-chlorophenol / tetrachloroethane mixture were transferred to a 500mL Erlenmeyer flask with a stir bar. The mixture was heated to dissolve at 100–105°C for 1.5 hours using a stirring rod. The solution was then filtered through a 47mm diameter, 1.0μm PTFE membrane filter (Advantec PTFE membrane filter, product name: T100A047A). The effective filter diameter was 37.5mm. After filtration, the filter was washed with 50mL of chloroform and then dried.

[0226] The aluminum content of the membrane filter was quantified using a scanning X-ray fluorescence spectrometer (RIGAKU, ZSX100e, Rh tube 4.0kW). Quantification was performed on the central 30mm diameter section of the membrane filter. It should be noted that the calibration curve for this X-ray fluorescence analysis was obtained using polyethylene terephthalate resin with a known aluminum content, and the apparent aluminum content is expressed in ppm. The determination was performed at X-ray power of 50kV-70mA, using pentaerythritol as the spectroscopic crystal and a PC (proportional counter) as the detector, under PHA (pulse height analyzer) conditions of 100-300, measuring the intensity of Al-Kα rays. The calibration curve was quantified using the aluminum content in the polyethylene terephthalate resin by high-frequency inductively coupled plasma atomic emission spectrometry.

[0227] (8) Quantitative analysis of cyclic trimers

[0228] The solid-phase polymerized polyester resin or the hollow molded body formed by the method described later is cryogenically pulverized or flaked, and 100 mg of sample is accurately weighed. It is dissolved in 3 mL of a hexafluoroisopropanol / chloroform mixture (volume ratio = 2 / 3), and further diluted with 20 mL of chloroform. 10 mL of methanol is added to precipitate the polymer, and the mixture is filtered. The filtrate is evaporated to dryness and then diluted to volume with 10 mL of dimethylformamide. The amount of cyclic trimer in the polyester resin or hollow molded body is then quantified by the following high-performance liquid chromatography (HPLC) method.

[0229] Device: L-7000 (manufactured by Hitachi)

[0230] Chromatographic column: μ-Bondasphere C18 5μm 100 Å 3.9mm × 15cm (Waters manufacture)

[0231] Solvent: Eluent A: 2% acetic acid / water (v / v)

[0232] Elution Buffer B: Acetonitrile

[0233] Gradient B%: 10→100% (0→55 points)

[0234] Flow rate: 0.8 mL / min

[0235] Temperature: 30℃

[0236] Detector: UV-259nm

[0237] The following describes the preparation of aluminum-containing ethylene glycol solutions and phosphorus-containing ethylene glycol solutions.

[0238] (1) Preparation of aluminum-containing ethylene glycol solution a1

[0239] An equal volume (by volume) of ethylene glycol was added to a mixing vessel along with a 20 g / L aqueous solution of basic aluminum acetate. The mixture was stirred at room temperature (23°C) for several hours, then stirred under reduced pressure (3 kPa) at 50–90°C for several hours to distill off water, thus preparing an aluminum-containing ethylene glycol solution a1 containing 20 g / L of aluminum compound. The maximum absorption wavelength of the aluminum-containing ethylene glycol solution a1 was 571.6 nm.

[0240] (2) Preparation of phosphorus-containing ethylene glycol solutions b1 and b1'

[0241] <Phosphorus-containing ethylene glycol solution b1>

[0242] Irganox 1222 (manufactured by BASF), a phosphorus compound, was added to a mixing tank along with ethylene glycol. The mixture was then heat-treated at 175°C for 150 minutes under nitrogen purging with stirring to prepare a phosphorus-containing ethylene glycol solution b1 containing 50 g / L of the phosphorus compound. The maximum absorption wavelength of the phosphorus-containing ethylene glycol solution b1 was 461.2 nm.

[0243] <Phosphorus-containing ethylene glycol solution b1'>

[0244] Except for changing the heat treatment conditions to 80°C for 60 minutes, the phosphorus-containing ethylene glycol solution b1' was prepared using the same method as the phosphorus-containing ethylene glycol solution b1. The maximum absorption wavelength of the phosphorus-containing ethylene glycol solution b1' is 470.8 nm.

[0245] Phosphorus-containing ethylene glycol solution b1' was used as Comparative Example 3. Phosphorus-containing ethylene glycol solution b1 was used in all examples and in comparative examples other than Comparative Example 3.

[0246] [Example of intermittent polymerization]

[0247] (Example 1)

[0248] <Manufacturing of Polyester Resin>

[0249] In a 10L stainless steel autoclave equipped with a stirrer, a pre-mixed polyester oligomer with an esterification rate of approximately 95% (composed of high-purity terephthalic acid and ethylene glycol) and high-purity terephthalic acid were added. The esterification reaction was carried out at 260°C to obtain an oligomer mixture. The concentration of acid-terminated groups in the resulting oligomer mixture was 750 eq / ton, and the proportion of hydroxyl-terminated groups (OH%) was 59 mol%.

[0250] A liquefied mixture containing an aluminum-containing ethylene glycol solution a1 and a phosphorus-containing ethylene glycol solution b1 prepared by the above method was added to the resulting oligomer mixture. This mixture was prepared with aluminum and phosphorus elements at 12 ppm and 32 ppm by mass, respectively, relative to the oligomer mixture. It should be noted that the amount of polyester resin produced can be calculated from the amount of terephthalic acid added. In this embodiment, the mixture was added with aluminum and phosphorus elements at 12 ppm and 32 ppm by mass, respectively, relative to the produced polyester resin.

[0251] Then, the system temperature was raised to 280°C over 1 hour, during which the system pressure was gradually reduced to 0.15 kPa. Under these conditions, a polycondensation reaction was carried out to obtain a polyester resin with an IV of 0.60 dl / g.

[0252] The obtained polyester resin was subjected to intermittent solid-state polymerization at 230°C and under reduced pressure for 7 hours to obtain a polyester resin with an IV of 0.75 dl / g.

[0253] <Manufacturing of Hollow Molded Bodies>

[0254] The solid-phase polymerized polyester resin was dried in a vacuum dryer to a moisture content of less than 100 ppm by mass. A bottomed preform was then formed using a 150C-DM injection molding machine manufactured by Meiki Manufacturing Co., Ltd., and a preform mold (mold temperature 5°C). The plasticizing conditions of the M-150C-DM injection molding machine were: feed screw speed 70%, screw speed 120 rpm, back pressure 0.5 MPa, and barrel temperatures from the hopper downstream to 250°C, with the barrel temperature including the nozzle set to 290°C. The injection pressure and holding pressure were adjusted to achieve a molded part weight of 28.4 ± 0.2 g.

[0255] Subsequently, the preform was heated and crystallized at the plug section using an NC-01 plug section crystallization device manufactured by FRONTIER Co., Ltd. Further, using a Sidel SBO LabN 1045 1Lab blow molding machine, air at a pressure of 36 bar was blown into a mold set to 160°C, and the preform was subjected to biaxial stretch blow molding at 750 bph, with a longitudinal magnification of 2.5 times and a circumferential magnification of 3.8 times, over a 30-second molding cycle, to obtain a hollow molded body.

[0256] (Examples 2-5, Comparative Examples 1-2)

[0257] Except that the aluminum-containing ethylene glycol solution a1 and the phosphorus-containing ethylene glycol solution b1 were added in the same amounts as the catalyst elements described in Table 1 relative to the polyester resin, the polyester resin was obtained by the same method as in Example 1. Furthermore, a hollow molded body was obtained by the same method as in Example 1.

[0258] (Comparative Example 3)

[0259] Except that solution b1' is used instead of solution b1 as a phosphorus-containing ethylene glycol solution, polyester resin was obtained in the same manner as in Example 1. Furthermore, hollow molded articles were obtained in the same manner as in Example 1.

[0260] The physical properties of the polyester resins obtained in Examples 1-5 and Comparative Examples 1-3 are shown in Table 1. In Table 1 and Table 2 described below, the amount of aluminum added and the amount remaining are denoted as Al, the amount of phosphorus added and the amount remaining are denoted as P, and the molar ratio of phosphorus to aluminum added and the molar ratio remaining are denoted as P / Al.

[0261] Table 1

[0262]

[0263] The polyester resins in Examples 1-5, despite having low amounts of aluminum and phosphorus, exhibit shorter polymerization times, resulting in lower aluminum-based foreign matter and total catalytic density (CT) content in the solid-state polymerized polyester resin, thus achieving higher quality. Furthermore, the lower catalyst content reduces catalyst costs. Additionally, the use of polyester resin with lower CT content in the manufacture of hollow molded bodies also reduces the CT content of the hollow molded bodies.

[0264] In Comparative Example 1, the catalyst cost is high due to the large amount of phosphorus compound added. Furthermore, while the high molar ratio of phosphorus to aluminum is desirable because it suppresses aluminum-based foreign matter, it reduces polymerization activity and is therefore not preferred. Additionally, the catalyst cost is higher.

[0265] In Comparative Example 2, the catalyst cost was low due to the low residual molar ratio of phosphorus to aluminum, but the increased amount of aluminum-based foreign matter in the polyester resin after solid-phase polymerization led to a higher CT content, resulting in poor quality of the polyester resin. Furthermore, since the hollow molded body was manufactured using polyester resin with a high CT content, the CT content of the hollow molded body was also higher.

[0266] In Comparative Example 3, the molar ratio of phosphorus to aluminum was within the range of this invention, resulting in a shorter polymerization time and lower catalyst cost. However, because the maximum absorption wavelength of the phosphorus-containing ethylene glycol solution b1' was significantly larger than in Examples 1-5, the residual molar ratio of phosphorus to aluminum decreased, leading to an increase in the amount of aluminum-based foreign matter and CT content in the polyester resin after solid-state polymerization, resulting in poor polyester resin quality. Furthermore, the hollow molded body manufactured using polyester resin with a higher CT content also had a higher CT content.

[0267] [Example of continuous polymerization]

[0268] (Example 6)

[0269] In a continuous polyester resin manufacturing apparatus consisting of three continuous esterification reactors and three continuous polycondensation reactors, and equipped with a high-speed agitator in the transport pipeline from the third esterification reactor to the first polycondensation reactor, a slurry prepared by mixing 0.75 parts by mass of ethylene glycol with 1 part by mass of high-purity terephthalic acid is continuously supplied. The reaction is carried out at a temperature of 255°C and a pressure of 203 kPa in the first esterification reactor, a temperature of 261°C and a pressure of 102 kPa in the second esterification reactor, and a temperature of 261-263°C and a pressure of 126 kPa in the third esterification reactor, yielding oligomers. The concentration of acid-terminated groups in the oligomers exiting the third esterification reactor is 550 eq / ton, and the proportion of hydroxyl-terminated groups (OH%) is 60 mol%.

[0270] To the obtained oligomer, a liquefied mixture of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1, prepared as described above, is added to the transport pipeline from the third esterification tank to the first polycondensation reactor using a liquid continuous mixer. Specifically, as a catalyst, the aluminum-containing ethylene glycol solution a1 and the phosphorus-containing ethylene glycol solution b1, prepared as described above, are mixed relative to the obtained oligomer at amounts of 12 ppm by mass for aluminum and 32 ppm by mass for phosphorus, respectively, and added as a liquefied solution. It should be noted that the amount of polyester resin generated can be calculated based on the amount of terephthalic acid added. In this embodiment, the mixture is added at amounts of 12 ppm by mass for aluminum and 32 ppm by mass for phosphorus, respectively, relative to the generated polyester resin.

[0271] The oligomers containing the mixture were continuously fed into a continuous polycondensation unit consisting of three reactors. Polycondensation was carried out at a reaction temperature of 268°C and a pressure of 5.3 kPa in the first polycondensation reactor, a reaction temperature of 270°C and a pressure of 0.930 kPa in the second polycondensation reactor, and a reaction temperature of 274°C and a pressure of 0.162 kPa in the third polycondensation reactor, to obtain a polyester resin with an IV of 0.59 dl / g. The polyester resin was extruded in a filament, cooled in water, and then cut into granules.

[0272] The resulting polyester resin fragments were then transported to a continuous solid-state polymerization apparatus. Crystallization was performed at approximately 155°C under a nitrogen atmosphere, followed by preheating at approximately 200°C under a nitrogen atmosphere, and then fed into a continuous solid-state polymerization reactor for solid-state polymerization at approximately 207°C under a nitrogen atmosphere. Subsequently, the resin was processed using a vibrating sieving process and an air classifying process to remove debris particles and film, yielding a polyester resin with an IV of 0.75 dl / g. Additionally, hollow molded articles were obtained using the same method as in Example 1.

[0273] (Examples 7 and 8, Comparative Examples 4 and 5)

[0274] Except for the addition of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1 relative to the obtained oligomers to achieve the catalyst element addition amounts described in Table 2, the polyester resin was obtained using the same method as in Example 6. Furthermore, a hollow molded body was obtained using the same method as in Example 1.

[0275] The physical properties of the polyester resins obtained in Examples 6-8 and Comparative Examples 4 and 5 are shown in Table 2.

[0276] Table 2

[0277]

[0278] The production ratios described in Table 2 refer to the production rates of Examples 6-8 and Comparative Example 5 per hour, based on the production rate of Comparative Example 4 per hour (with the production rate of Comparative Example 4 per hour being 1.00). A production ratio higher than 1 indicates higher polymerization activity of the catalyst, while a production ratio lower than 1 indicates lower polymerization activity of the catalyst.

[0279] The polyester resins of Examples 6-8 have a larger production volume than those of Comparative Example 4. The amounts of aluminum and phosphorus added are reduced, lowering catalyst costs and improving polymerization activity. Furthermore, the amount of aluminum-based foreign matter and total calorific value (CT) in the solid-state polymerized polyester resin is also reduced, resulting in a high-quality polyester resin. Additionally, since a polyester resin with a lower CT content is used to manufacture hollow molded bodies, the CT content of the hollow molded bodies is also reduced.

[0280] In Comparative Example 5, due to the low residual molar ratio of phosphorus to aluminum, the polyester resin after solid-state polymerization contained a large amount of aluminum-based foreign matter and a high CT content, resulting in poor quality of the polyester resin. Furthermore, the hollow molded body manufactured using polyester resin with a high CT content also had a higher CT content.

[0281] Using the results from Examples 1-5 and Comparative Examples 1 and 2 in Table 1, the relationship between the residual molar ratio of phosphorus to aluminum, the amount of aluminum foreign matter, and the polymerization time was analyzed. Figure 1 The text indicates that the relationship between the maximum absorption wavelength of the mixture of aluminum-containing ethylene glycol solution a1 and phosphorus-containing ethylene glycol solution b1, the amount of aluminum-based foreign matter, and the polymerization time is... Figure 2 The Chinese side indicated that...

[0282] As can be seen from these figures, the scope of this invention is within a critical range. Furthermore, it is clarified that the amount of aluminum-based foreign matter and the polymerization time are contradictory phenomena.

[0283] [Availability in Industry]

[0284] The polyester resin and hollow molded articles of the present invention, manufactured using a polymerization catalyst composed of aluminum and phosphorus compounds, maintain color tone and thermal stability while suppressing the formation of aluminum-based foreign matter and keeping catalyst costs low. This provides a clean and high-quality polyester resin, making a significant contribution to industry.

Claims

1. A polyester resin, characterized in that, The polyester resin contains substances derived from a polymerization catalyst, which consists only of a polymerization catalyst composed of aluminum and phosphorus compounds, and the polyester resin satisfies the following (1) to (3): the amount of cyclic trimers in the polyester resin is less than 5000 ppm. (1) The aluminum content in the polyester resin is 9~19 ppm by mass. (2) The phosphorus content in the polyester resin is 22~40 ppm by mass. (3) The molar ratio of phosphorus to aluminum in the polyester resin is above 1.55 and below 1.

85.

2. The polyester resin according to claim 1, wherein, The aluminum content in the polyester resin, which is equivalent to aluminum-based foreign matter, is below 1650 ppm by mass. The aluminum-based foreign matter is a substance derived from aluminum compounds used as polymerization catalysts and is insoluble in the polyester resin.

3. The polyester resin according to claim 1 or 2, wherein the intrinsic viscosity IV is 0.56 dl / g or higher.

4. The polyester resin according to claim 1 or 2, wherein, The phosphorus compound has a phosphorus element and a phenol structure within the same molecule.

5. A method for manufacturing the polyester resin according to any one of claims 1 to 4, It has a first step of synthesizing a polyester or its oligomer as an intermediate condensation polymer. The second step of melt polymerization of the intermediate, The third step involves solid-state polymerization of the melt-polymerized polyester. After step 1 and before step 2, a solution A1 containing dissolved aluminum compound and a solution B1 containing dissolved phosphorus compound are added to the intermediate, wherein the amounts of solution A1 and solution B1 added satisfy the following (4) to (6). (4) The amount of aluminum added relative to the generated polyester resin is 9-19 ppm by mass. (5) The amount of phosphorus added relative to the generated polyester resin is 25-50 ppm by mass. (6) The molar ratio of the amount of phosphorus added in (5) to the amount of aluminum added in (4) is more than 2.00 and less than 2.

40.

6. The method for manufacturing polyester resin according to claim 5, wherein, The melt polymerization is carried out until the intrinsic viscosity IV is 0.56~0.65 dl / g, and then the solid-phase polymerization is carried out until the intrinsic viscosity IV is 0.70~0.85 dl / g.

7. The method for manufacturing polyester resin according to claim 5, wherein, The solution A1 is a diol solution, and the maximum absorption wavelength of the solution A1 is 562.0~572.0 nm.

8. The method for manufacturing polyester resin according to claim 7, wherein, Solution B1 is a diol solution, and the maximum absorption wavelength of solution B1 is 460.0~463.0 nm.

9. The method for manufacturing polyester resin according to claim 8, wherein, Diol solution B1 involves heat-treating a phosphorus compound in a diol solution at 170–196 °C for 125–240 minutes.

10. The method for manufacturing the polyester resin according to any one of claims 5 to 9, wherein, The solutions A1 and B1 are diol solutions, and the maximum absorption wavelength of the mixture of diol solutions A1 and B1 is 559.5~560.8 nm.

11. A hollow shaped body, characterized in that, It is a hollow molded body formed of polyester resin, wherein the polyester resin contains substances derived from a polymerization catalyst, and the polymerization catalyst comprises only a polymerization catalyst composed of aluminum compounds and phosphorus compounds. The hollow molded body satisfies the following conditions (7) to (9): the amount of cyclic trimer in the hollow molded body is less than 6000 ppm. (7) The aluminum content in the hollow molded body is 9~19 ppm by mass. (8) The phosphorus content in the hollow molded body is 22~40 ppm by mass. (9) The molar ratio of phosphorus to aluminum in the hollow molded body is more than 1.55 and less than 1.

85.

12. The hollow shaped body according to claim 11, wherein, The aluminum content in the hollow molded body, which is equivalent to aluminum-based foreign matter, is less than 1650 ppm by mass. The aluminum-based foreign matter is a substance derived from aluminum compounds used as polymerization catalysts and is insoluble in polyester resin.

13. The hollow molded body according to claim 11 or 12, wherein, The phosphorus compound has a phosphorus element and a phenol structure within the same molecule.

14. A method for manufacturing a hollow molded body, comprising the method for manufacturing the hollow molded body according to any one of claims 11-13, characterized in that, Hollow molded articles are manufactured from the polyester resin according to any one of claims 1 to 4.

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