Titanate compounds as catalysts in polyester manufacturing methods

Abstract

The present invention relates to a method for producing polyester in a polycondensation reaction catalyzed by aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof. The present invention also relates to a composition containing aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof as a catalyst for polyester production in a polycondensation reaction. Furthermore, the present invention relates to the use of aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof as heterogeneous polycondensation catalysts. Aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof are amorphous mixed oxides of aluminum oxide (and / or barium oxide, and / or calcium oxide, and / or zinc oxide) with titanium oxide. These titanate compounds have been found to be excellent heterogeneous catalysts in polycondensation reactions for producing polyesters such as polyethylene terephthalate.

Description

[Technical Field]

[0001] Technical field of inventions This invention relates to a method for producing polyester by a polycondensation reaction using one or more titanate compounds selected from aluminum titanate compounds (AlTi), barium titanate compounds (BaTi), calcium titanate compounds (CaTi), and zinc titanate compounds (ZnTi) as a catalyst. Furthermore, this invention relates to a composition containing one or more titanate compounds as a catalyst for polyester production in a polycondensation reaction. Moreover, this invention relates to the use of one or more titanate compounds as a heterogeneous polycondensation catalyst. [Background technology]

[0002] Polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polyethylene furanoate (PEF), and polybutylene terephthalate (PBT) are important industrial polymers. They are widely used in thermoplastic fibers, films, and molding applications.

[0003] Several major reactions occur when producing high molecular weight acyclic polyesters such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), and polyethylene naphthalate (PEN).

[0004] The first major reaction is esterification. In this reaction, the polyacid and polyol are esterified to produce monomers suitable for the subsequent polycondensation reaction. During the esterification reaction, undesirable byproducts such as 1,3-dioxolane, 2-methyl-1,3-dioxolane, 1,4-dioxane, and vinyl alcohol may be formed. The latter tautomerize to acetaldehyde.

[0005] The second major reaction is polycondensation. This reaction is important for increasing the molecular weight of polyesters. Polycondensation can involve two phases: a molten phase and a solid phase (SSP).

[0006] Polycondensation reactions are generally catalyzed by catalysts. However, esterification reactions can also be catalyzed by catalysts. Preferably, they are catalyzed by the same catalyst used for polycondensation reactions.

[0007] Antimony(III) compounds are often used as catalysts for both esterification and polycondensation reactions. However, antimony catalysts are facing increasing environmental pressure and regulatory controls, particularly in food contact and textile applications. Antimony catalysts can also cause gray discoloration. Tin compounds can also be used in esterification and polycondensation reactions, but they have similar toxicity and regulatory concerns as antimony.

[0008] Titanium-based catalysts are used alone or in combination with other compounds in the production of polyesters, as described in U.S. Patents 4,482,700, 4,131,601, 5,302,690, 5,744,571, 5,905,136, and WO97 / 45470. U.S. Patent Publication 2005 / 0009687 specifically describes the use of titanium alkoxide catalysts in the polymerization of cyclic esters. As described in U.S. Patent Publication 2005 / 0215425, there have been concerns that when titanium-based catalysts are used in esterification and polycondensation reactions, they tend to undergo hydrolysis upon contact with water, forming glycol-insoluble oligomer species and losing catalytic activity. Esters and polyesters produced using certain titanium compounds as catalysts may also suffer from yellowing issues, as described in U.S. Patents 4,131,601 and 4,482,700.

[0009] To address these issues, much research has been conducted on alternatives to antimony compounds in polyester polycondensation reactions using titanium compounds as catalysts.

[0010] Reference CN102391490A discloses a method for preparing a titanium-based polyester catalyst modified with tributyl phosphate supported on activated carbon. By dissolving isopropyl titanate, tributyl phosphate, aluminum chloride, and activated carbon in an organic solvent such as ethylene glycol, and adding water, a black powder with a low specific surface area is obtained. The molar ratio of aluminum chloride to titanate is 1:19. This catalyst improves catalytic performance and reduces yellowing in the final product.

[0011] Patent application CN103289069A discloses an aluminum-titanium composite catalyst for polyester polycondensation, intended to replace existing antimony-based catalysts used in the polyester industry. This catalyst is prepared by adding dissolved tetrabutyl titanate to a sodium aluminate solution. The resulting white powder has a molar ratio of titanium to aluminum of 1:2 to 20:1 and does not contain heavy metal compound elements.

[0012] U.S. Patent Application Publication No. 2002 / 193555 (Reference US2002193555(A1)) describes the preparation and use of titanium halide hydrolysates. The synthesized titanium oxyhydrate is stabilized by the addition of basic components (ammonia, magnesium oxide).

[0013] In catalyst systems for the synthesis of polyesters, particularly PET and its copolymers, there is a need to improve catalytic activity while minimizing or eliminating any impact on the properties of the polyester, resulting in polyesters that do not yellow or have reduced yellowing, and that have reduced toxicity concerns.

[0014] Therefore, an object of the present invention is to provide a polycondensation catalyst for polyester production. This catalyst has activity equivalent to conventionally used antimony-based catalyst systems and imparts equivalent color properties to polyester, but with reduced toxicity and regulatory concerns.

[0015] Furthermore, an object of the present invention is to provide a catalyst that generates fewer by-products, such as acetaldehyde, during the processing of polyester, particularly PET, compared to commonly used titanium alcoholate catalyst systems. An example of by-product generation is the generation of acetaldehyde, which is produced during resin manufacturing and regenerated during processing.

[0016] Furthermore, another object of the present invention is to provide a catalyst that enables the substitution of antimony in a polyester polycondensation reaction without adversely affecting the manufacturing process and / or the properties of the final product.

[0017] Another object of the present invention is to provide a catalyst for polyester polycondensation reactions that yields reaction rates (molten phase and solid phase) equivalent to those of conventional antimony-based catalysts.

[0018] Furthermore, an object of the present invention is to provide a method for producing polyester, which includes a catalyst that enables the substitution of at least a portion of antimony in a polyester polycondensation catalyst composition that does not adversely affect the manufacturing process and the properties of the final product, or minimizes such adverse effects. [Overview of the project]

[0019] Detailed explanation The above objective is achieved by the present invention, namely by providing a polyester polycondensation reaction composition comprising one or more catalysts, at least one polyacid, and at least one polyol, wherein at least one of the catalysts is a titanate compound or a mixture of titanate compounds, and the titanate compound or mixture of titanate compounds is in crystalline form.

[0020] Titanate compounds are selected from the group consisting of aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and zinc titanate compounds. Mixtures of titanate compounds are selected from the following group: - A mixture of an aluminum titanate compound and a barium titanate compound, - A mixture of an aluminum titanate compound and a calcium titanate compound, - A mixture of an aluminum titanate compound and a zinc titanate compound, - A mixture of a barium titanate compound and a calcium titanate compound, - A mixture of a barium titanate compound and a zinc titanate compound, - A mixture of a calcium titanate compound and a zinc titanate compound, - A mixture of an aluminum titanate compound, a barium titanate compound, and a calcium titanate compound, - A mixture of an aluminum titanate compound, a barium titanate compound, and a zinc titanate compound, - A mixture of a barium titanate compound, a calcium titanate compound, and a zinc titanate compound, and - A mixture of an aluminum titanate compound, a barium titanate compound, a calcium titanate compound, and a zinc titanate compound.

[0021] Generally, the compositions of the present invention can be used to produce polyesters. In a typical method for producing polyesters, at least one polyacid and at least one polyol are esterified to produce a monomer (also called a prepolymer), and then the monomer is polycondensed to form a polyester.

[0022] Suitable polyacids include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, and long-chain branched acids such as trimesic acid, trimellitic acid, and their anhydrides. Terephthalic acid is a preferred polyacid.

[0023] Suitable polyols include ethylene glycol, cyclohexanedimethanol, 1,3-propanediol, 2,2-dimethylpropanediol, 1,4-butanediol, isosorbide; aromatic polyols such as resorcinol and hydroquinone; and long-chain branched polyols such as trimethylolpropane, glycerol, and pentaerythritol. Ethylene glycol is a preferred polyol.

[0024] The advantage of using aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds compared to using conventional titanium compounds is that the latter are highly reactive with water because they undergo hydrolysis to produce catalytically inert titanium species. Water is then produced as the unavoidable main product of the esterification and polycondensation reactions. Advantageously, the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds according to the present invention are less reactive with water. Therefore, the catalyst composition described in the claim can further contain water without the risk of the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds being deactivated or otherwise adversely affected by water. This also results in the advantage that the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds can be directly added to the reaction composition at the start of the polyester polycondensation process.

[0025] For aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds used in accordance with the present invention, it is essential that the compound is in a crystalline form. Here, "crystalline form" means that the aluminum titanate compound, barium titanate compound, calcium titanate compound, and / or zinc titanate compound is not amorphous but has at least a polycrystalline or quasicrystalline structure. A polycrystalline or quasicrystalline structure is typically characterized by a multitude of crystals held together by layers of amorphous solid material of the compound.

[0026] The inventors discovered that using aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds in crystalline form rather than amorphous form resulted in superior catalytic performance.

[0027] The superior catalytic performance of crystalline aluminum titanate, barium titanate, calcium titanate, or zinc titanate is thought to be due to the fact that titanium has only one free coordination site within the crystal structure of aluminum titanate, barium titanate, calcium titanate, or zinc titanate. Compounds that have no free coordination sites for titanium atoms are completely incapable of catalyzing polycondensation reactions. However, aluminum titanate, barium titanate, calcium titanate, and / or zinc titanate compounds in structural forms in which titanium atoms have multiple free coordination sites are thought to tolerate side reactions that produce undesirable byproducts, such as in the case of amorphous forms of aluminum titanate, barium titanate, calcium titanate, and / or zinc titanate compounds.

[0028] According to the present invention, the amount of aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound in crystalline form in the composition is preferably 10% by weight or more relative to the total amount of one or more catalysts. More preferably, the amount of aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound in crystalline form is 50% by weight or more relative to the total amount of one or more catalysts. Most preferably, the amount of aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound in crystalline form is 80% by weight or more, or 100% by weight, relative to the total amount of one or more catalysts. In the case of a mixture of two, three, or four titanate compounds, the above weight percentage amounts apply to the mixture of two, three, or four titanate compounds.

[0029] According to the present invention, the amount of titanium in the composition in the form of aluminum titanate compound, barium titanate, calcium titanate compound and / or crystalline zinc titanate compound is preferably 1 ppm to 100 ppm by weight, preferably 4 ppm to 50 ppm by weight, and more preferably 8 ppm to 30 ppm by weight, based on the total weight of at least one polyacid and at least one polyol in the composition, or the polyester formed by the polyester polycondensation reaction.

[0030] Aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds may, but do not necessarily, be in a pure crystalline form. Typically, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds are in a polycrystalline or quasicrystalline form. Preferably, the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds used according to the present invention have at least 90% by weight crystallinity, preferably at least 95% by weight, and more preferably at least 98% by weight crystallinity.

[0031] When aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds are used as catalysts in the compositions of the present invention, they may not contain any rare earth elements. Furthermore, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds may not contain organic groups.

[0032] The same applies to any further catalysts that may be included in the composition of the present invention. Accordingly, catalysts containing rare earth elements may be excluded from one or more catalysts in the composition, and / or catalysts containing organic groups, such as organometallic catalysts, may be excluded from one or more catalysts in the composition.

[0033] According to the present invention, it is preferable that the polyester polycondensation reaction composition does not contain an antimony compound, in particular, does not contain an antimony-containing catalyst, or contains only a small amount of an antimony compound, i.e., less than 200 ppm, preferably less than 100 ppm.

[0034] The aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds present in the compositions of the present invention can be characterized as mixed oxides comprising aluminum oxide and / or barium oxide and / or calcium oxide and / or zinc oxide together with titanium dioxide. Optionally, crystal water may be present in the mixed oxide. As a preferred alternative, the aluminum titanate compounds, barium titanate compounds, or calcium titanate compounds according to the present invention consist of aluminum atoms, titanium atoms, and oxygen atoms; or barium atoms, titanium atoms, and oxygen atoms; or calcium atoms, titanium atoms, and oxygen atoms; or zinc atoms, titanium atoms, and oxygen atoms. Optionally, crystal water may be further present. However, typically, the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds present in the compositions of the present invention are characterized by not containing crystal water. Preferably, the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds present in the compositions of the present invention are mixed oxides consisting of aluminum oxide and titanium dioxide, or consist of aluminum atoms, titanium atoms, and oxygen atoms.

[0035] Aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and / or zinc titanate compounds can be prepared by at least two different routes: 1) Dry method: comprising mixing crystalline oxides or carbonates of aluminum, barium, calcium, or zinc with titanium oxide; 2) Wet chemical method: comprising reacting soluble aluminum, barium, calcium, or zinc compounds with soluble titanium compounds in a solvent.

[0036] Dry method According to 、 Aluminum titanate compounds include crystalline Al2O3 (e.g., corundum) and crystalline TiO2 (e.g., rutile), or mixtures thereof. 、The mixture is then prepared by sintering. Optionally, and to reduce the average primary particle size of the crystalline oxides before sintering, crystalline Al2O3 and / or crystalline TiO2 may be ground before the mixing or sintering steps. Grinding may also be performed before both steps.

[0037] Preferably, the mixture used for sintering contains or consists of crystalline Al2O3 and crystalline TiO2 in a molar ratio of 1:1.

[0038] Barium titanate compounds 、 A mixture containing crystalline BaCO3 and crystalline TiO2 (e.g., rutile), or a mixture consisting of these, is mixed and then the mixture is sintered. Dry method It can be prepared (see, for example, J. Mat. Sci. Technol. (2007), pp. 655-658). Optionally, and to reduce the average primary particle size of the crystalline oxide before sintering, crystalline BaCO3 and / or crystalline TiO2 can be ground before the mixing or sintering process. Grinding can also be performed before both processes.

[0039] Preferably, the mixture used for sintering contains or consists of crystalline BaCO3 and crystalline TiO2 in a molar ratio of 1:1.

[0040] Calcium titanate compounds 、 A mixture containing or consisting of crystalline CaCO3 and crystalline TiO2 (e.g., rutile), followed by sintering the mixture, Dry method It can be prepared (see, for example, Mat. Res. Bulletin (2003), 38(7), pp. 1203-1213). Optionally, and to reduce the average primary particle size of the crystalline oxide before sintering, crystalline Al2O3 and / or crystalline TiO2 can be ground before the mixing or sintering process. Grinding can also be performed before both processes.

[0041] Preferably, the mixture used for sintering is 、It contains crystalline CaCO3 and crystalline TiO2 in a molar ratio of 1:1, or consists of crystalline CaCO3 and crystalline TiO2 (molar ratio 1:1).

[0042] Zinc titanate compounds 、 By mixing crystalline ZnO and crystalline TiO2 (e.g., rutile) or a mixture thereof, and then sintering the mixture, Prepared by dry method This is possible (see, for example, Ceramics International (2004), 30(8), pp. 2183–2189).

[0043] After the mixing step, or after any grinding step, the mixture is sintered to obtain an aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound used in the present invention.

[0044] After sintering, the aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound preferably has an average primary particle size in the range of 100 nm to 500 μm, more preferably 300 nm to 100 μm, even more preferably 400 nm to 50 μm, and most preferably 500 nm to 2000 nm. To obtain the desired average primary particle size of the crystalline oxide, the sintered aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound can be pulverized before use according to the present invention.

[0045] The average primary particle size (in the μm range) of aluminum titanate, barium titanate, calcium titanate, and zinc titanate compounds obtained by the dry method was measured by optical microscopy under transmitted light. For this purpose, a Keyence VHX-1000 digital microscope system and a VH-Z250R zoom lens were used. A 2.5% suspension of the solid to be examined in ethylene glycol was placed on a microscope slide and covered with a coverslip.

[0046] The average primary particle size in the nanometer range was measured by dynamic light scattering (DLS) using an Anton Paar Litesizer 100. The above solid was measured in a cuvette at a 0.1% suspension in ethylene glycol.

[0047] The total amount of one or more catalysts contained in the composition of the present invention is 0.1 ppm to 400 ppm, preferably 1 ppm to 200 ppm, and more preferably 2 ppm to 120 ppm, based on the weight of at least one polyacid and at least one polyol.

[0048] wet chemical method According to the report, aluminum titanate compounds are prepared by a wet chemical process that includes the steps of reacting an aluminum compound with a titanium compound in a solvent, precipitating the reaction product, calcining the precipitated reaction product, and obtaining the aluminum titanate compound.

[0049] For the wet chemical process, aluminum alcoholate, aluminum acetate, aluminum nitrate, or aluminum citrate can be used as the aluminum compound. For the titanium compound, titanium alcoholate, titanium acetate, titanium halide, or titanium citrate can be used. The aluminum compound and the titanium compound are reacted using the sol-gel method. An example of the synthesis of powdered aluminum titanate using sol-gel technology is described by HG Riella et al., Trans. Tech. Publ. 416 (2003) 519-524.

[0050] Barium acetate can be used as the barium compound in the wet chemical process. Isopropoxytitanium can be used as the titanium compound. The barium compound and the titanium compound are reacted using the sol-gel method. A typical example of the synthesis of barium titanate compounds using sol-gel technology is described in J. Mat. Chem (1992), 2, pp. 591-94.

[0051] Calcium acetate can be used as the calcium compound in the wet chemical process. Isopropoxytitanium can be used as the titanium compound. The calcium compound and the titanium compound are reacted using the sol-gel method. A typical example of the synthesis of calcium titanate compounds using sol-gel technology is described in Chem. Mat. (1994), 6, pp. 58-62.

[0052] Zinc acetate can be used as the zinc compound in the wet chemical process. Butylated titanium can be used as the titanium compound. The zinc compound and the titanium compound are reacted using the sol-gel method. A typical synthesis method of zinc titanate compounds using sol-gel technology is described in J. of Crystal Growth (2002), 243(2), pp. 319-326.

[0053] The above precipitate reaction product is calcined to obtain an aluminum titanate compound, a barium titanate compound, a calcium titanate compound, or a zinc titanate compound by a wet chemical process. After that, the aluminum titanate compound, barium titanate compound, calcium titanate compound, or zinc titanate compound can have an average primary particle diameter of less than 100 nm, preferably less than 50 nm, and most preferably less than 25 nm.

[0054] When aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, or zinc titanate compounds are prepared by a wet chemical process, their average primary particle size is measured by the following method: A colloidal dispersion of AlTi (or a colloidal dispersion of other titanate compounds such as BaTi, CaTi, ZnTi, or any mixture of two, three, or four types of AlTi, BaTi, CaTi, or ZnTi) prepared by a known method is diluted (e.g., 0.025 wt%) and the solution is dropped onto a 3 mm copper grid coated with a 200 mesh carbon film. Similarly, drops of the colloidal dispersion are dropped onto a 3 mm Au grid coated with a porous carbon film. The grids are placed on a paper sheet that has absorbed the liquid passing through the perforated membrane, and the samples are dried in air before being stored in a plastic container sealed with Parafilm before electron microscopy analysis. SEM analysis is performed on randomly selected areas at 300 kV and 40,000x magnification. The sample distribution of electron micrographs is determined using appropriate software such as ImageJ. The size distribution is measured at 1 nm intervals. The Gaussian distribution is shown by the solid line in the graph. The above method follows the procedure described in C. Shin et al 2019, ECS J. Solid State Sci. Technol. 8, p. 3195-3200.

[0055] Examples of titanate compounds prepared and / or used for use in the present invention include Al2TiO5 as an aluminum titanate compound, BaTiO3 as a barium titanate compound, CaTiO3 as a calcium titanate compound, and ZnTiO3, Zn2TiO4, or Zn2Ti3O8 as zinc titanate compounds.

[0056] The present invention also relates to a method for producing polyester using one or more catalysts. The method of the present invention includes the following steps: A step of supplying a reaction mixture containing at least one polyacid and at least one polyol; A step of esterifying at least one polyacid and at least one polyol in a reaction mixture in the presence of optionally one or more catalysts to produce monomers; A process of forming a polyester by polymerizing monomers in a reaction mixture by polycondensation in the presence of one or more catalysts; Here, at least one catalyst is an aluminum titanate compound containing aluminum, titanium, and oxygen atoms, or a barium titanate compound containing barium, titanium, and oxygen atoms, or a calcium titanate compound containing calcium, titanium, and oxygen atoms, or a zinc titanate compound containing zinc, titanium, and oxygen atoms, or a mixture of two, three, or four of the titanate compounds containing titanium and oxygen atoms together with the respective atoms of aluminum, barium, calcium, and / or zinc; Here, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures of titanate compounds are in crystalline form.

[0057] For details of the method and / or preferred embodiments of the present invention, particularly one or more catalysts, at least one polyacid, at least one polyol, monomer, aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof of titanate compounds and methods for producing the same, please refer to the above description relating to the composition of the invention applicable to the polyester production method. Details are as follows.

[0058] Typically, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, or zinc titanate compounds, or mixtures thereof, are added to the reaction mixture in an amount such that titanium is present in a concentration of 1 ppm to 100 ppm, preferably 5 ppm to 50 ppm, and most preferably 10 ppm to 30 ppm, based on the total weight of at least one polyacid and at least one polyol in the composition, or on the resulting polyester.

[0059] According to the present invention, it is recommended that 10% by weight or more of one or more catalysts used in the polycondensation step and optionally in the esterification step be aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds in crystalline form. Preferably, 30% by weight or more, more preferably 50% by weight or more of one or more catalysts used in the polycondensation step and optionally in the esterification step are aluminum titanate compounds in crystalline form. However, most preferably, 80% by weight or more, or 100% by weight or more of one or more catalysts used in the condensation polymerization step and optionally in the esterification step are aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds in crystalline form.

[0060] As described above, the aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof used in the esterification and / or polycondensation steps do not need to contain rare earth elements and / or organic groups.

[0061] The same applies to any further catalysts that may be used in the method of the present invention. Accordingly, catalysts containing rare earth elements can be excluded from one or more catalysts used in the esterification step and / or polycondensation step, and / or catalysts containing organic groups can be excluded from one or more catalysts used in the esterification step and / or polycondensation step.

[0062] Furthermore, in the esterification and / or polycondensation steps, the antimony compound can be used in an amount of less than 200 ppm, preferably less than 100 ppm. Most preferably, the antimony compound is not used in the method of the present invention for producing polyester.

[0063] A preferred polyester formed by the method of the present invention is polyethylene terephthalate.

[0064] In an advantageous variation of the method of the present invention, the method further comprises adding recycled polyethylene terephthalate in an amount equal to the sum of at least one polyacid and at least one polyol, or 10 to 100% by weight, preferably 30 to 100%, more preferably 50 to 100% by weight, and most preferably 80 to 100% by weight, based on the polyester to be produced, before or during the esterification step and / or before or during the polycondensation step.

[0065] Aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds can be used in both the molten and solid phases of the polycondensation reaction at concentrations of 1 to 250 ppm, preferably 1 to 100 ppm, and most preferably 5 to 75 ppm by weight, based on the total amount of at least one polyacid and at least one polyol provided, or the polyester ultimately formed.

[0066] Furthermore, the aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof used in the catalyst composition of the present invention have good stability against hydrolysis. This makes it possible to use the catalyst as an esterification catalyst to catalyze the esterification reaction. The aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof may be in powder form. The aluminum titanate powder, barium titanate powder, calcium titanate powder, zinc titanate powder, or mixed powders thereof may be added to the polyacid and polyol (these suspensions are also referred to herein as “paste”) before the esterification reaction. The catalyst-containing suspension may be added directly to the esterification reaction or directly to the polycondensation reaction. The catalyst operates under similar temperature and pressure conditions to antimony-based catalysts typically described in the prior art.

[0067] Aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof are insoluble in water and also insoluble in most organic solvents. The solvents in this invention are polar and nonpolar liquid organic molecules having a carbon-based structure and a boiling point of less than 250°C, and can be used to dissolve reactants such as polyacids, polyols, or antimony compounds. Examples of organic solvents include linear, branched, or cyclic alkanols; linear, branched, or cyclic alkanes; linear, branched, or cyclic alkenes; linear, branched, or cyclic ethers; linear, branched, or cyclic esters; molecules having an aromatic ring structure (e.g., benzene, toluene, xylene); and combinations thereof.

[0068] According to the present invention, one or more catalysts used in the above composition or method include an aluminum-titanium compound, a barium titanate compound, a calcium titanate compound, a zinc titanate compound, or a mixture thereof of these titanate compounds, and may further include one or more catalysts, which may be homogeneous catalysts. Examples of homogeneous catalysts for polycondensation and / or esterification reactions include titanium-containing compounds other than germanium-containing compounds, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of the above titanate compounds (e.g., titanium alcoholates), or antimony(III)-containing compounds such as antimony oxide, antimony acetate, and antimony glycolate. Antimony(III) compounds used in polycondensation reactions using catalysts improve selectivity and reaction rate. Furthermore, compared to, for example, conventional titanium alcoholates and other homogeneous catalysts, the content of undesirable decomposition products such as acetaldehyde in the treated polyester is also lower.

[0069] Furthermore, the reaction rates of the two reaction steps in polycondensation (the molten phase and SSP) depend not only on temperature but also on the diffusion of volatile reaction products such as ethylene glycol and acetaldehyde.

[0070] In the present invention, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, or mixtures thereof of these titanate compounds used as catalysts can be used in the form of a fixed-bed catalyst or a catalyst powder. If the catalyst is in powder form, it can be added directly to the catalyst composition before the esterification reaction. Preferably, the re-aggregation of fine particles can be avoided by suspending the catalyst powder before adding it to a reaction component containing at least one polyacid and at least one polyol. Additional antimony catalyst can be dissolved in a suitable polyol such as ethylene glycol. The antimony catalyst-containing solution can be added directly to the paste, and then the paste is added to the esterification or polycondensation step.

[0071] The additional antimony(III) catalyst can be present in an amount of 50 to 350 ppm by weight, preferably 150 to 300 ppm by weight, and most preferably 200 to 300 ppm by weight, based on the elemental antimony in the final polymer.

[0072] The final product of polyester production using the above catalyst, particularly PET production, can be further processed to provide PET bottles. PET bottles are manufactured by stretch blow molding a PET preform. Here, "preform" refers to an injection molded product intended to be molded into a bottle by stretch blow molding, and the material for both the preform and the bottle is preferably PET.

[0073] The crystallization behavior of PET produced using the catalyst composition of the present invention is similar to that of PET catalyzed with conventional antimony(III) catalysts. In antimony-catalyzed products, elemental antimony nanoparticles act as crystal nuclei, inducing crystallization within the PET. In PET products catalyzed with catalyst compositions containing aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof, the heterogeneous catalyst itself acts as a crystal nucleus.

[0074] The final product of a catalytic polycondensation reaction using a catalyst containing aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds can be food-grade polyester. In particular, food-grade PET can be obtained by using up to 100% by weight of recycled PET as a raw material. Beneficially, the use of recycled PET reduces the need for virgin PET, contributing to closing the loop in the circular economy. Preferably, the food-grade PET contains 1 to 100% by weight, more preferably 10 to 100% by weight, and most preferably 25 to 100% by weight of recycled polyethylene terephthalate as a raw material for the final PET production. Here, the catalyst containing the aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof of these titanate compounds of the present invention is used.

[0075] The final product of the catalyst-assisted polycondensation reaction, PET, may contain up to 25% by weight, preferably up to 50% by weight, and most preferably up to 100% by weight, recycled PET used for thermoforming applications such as beverage bottle manufacturing or film packaging.

[0076] The amount of aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof of these titanate compounds is calculated based on the amount of elemental titanium required for the catalytic reaction. For example, 57 ppm of aluminum titanate compound as a catalyst corresponds to 15 ppm of elemental titanium (73 ppm of barium titanate compound corresponds to 15 ppm of elemental titanium; 43 ppm of calcium titanate compound corresponds to 15 ppm of elemental titanium; 51 ppm of zinc titanate compound corresponds to 15 ppm of elemental titanium). In preferred embodiments, if one or more catalysts used in the catalyst composition consist only of the aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or mixtures thereof of these titanate compounds of the present invention, the catalyst contains a total amount of elemental titanium of 1 to 100 ppm, more preferably 5 ppm to 50 ppm, and most preferably 10 ppm to 20 ppm, based on at least one polyacid and at least one polyol, or the resulting polyester.

[0077] Polymerization catalysts increase the polymerization rate of monomers, but these catalysts initiate the degradation of polyesters (e.g., PET), thus negatively impacting the thermal stability of the polymer. Thermally stable polyesters are those that have low acetaldehyde content, minimal discoloration, and high molecular weight retention after subsequent heat treatment or processing. Acetaldehyde formation is an undesirable consequence of degradation, especially in the food and beverage industry, as even trace amounts negatively affect the flavor of bottled products. Furthermore, polymer degradation typically causes discoloration and yellowing, which is undesirable in most applications. Therefore, high concentrations and high activity of catalysts should be avoided.

[0078] The catalyst composition may further contain a catalyst deactivator mainly composed of phosphorus in an amount of less than 5 ppm based on the weight of phosphorus. If a catalyst deactivator containing phosphorus is present, the deactivator is not added directly to the catalyst suspension.

[0079] Any stabilizer that deactivates the polymerization catalyst (and thus prevents degradation and discoloration of the polyester) is suitable as an inactivator. Generally, heat stabilizers do not react with the polymer and have low residual moisture content.

[0080] When using an aluminum titanate compound, barium titanate compound, calcium titanate compound, zinc titanate compound, or a mixture of these titanate compounds as the catalyst, it can be used under the same solvents, temperature, and general conditions as the antimony-containing catalyst. Compared to homogeneous titanium-containing catalysts, such as titanium alcoholates, the titanium-containing heterogeneous catalyst of the present invention has low reactivity towards side reactions and thus does not require a catalyst inactivator. Therefore, in a preferred embodiment of the present invention, the catalyst composition for the polyester polycondensation reaction does not contain a catalyst inactivator.

[0081] The polyester obtained by the method of the present invention has an intrinsic viscosity of 0.7 dL·g -1 or more, and is a high molecular weight acyclic polyester (molecular weight 10,000 g·mol -1 or more, preferably 20,000 g·mol -1 or more), and can be, for example, polyethylene terephthalate (PET), polyethylene furanoate (PEF), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), etc. Preferably, the polyester is PET.

[0082] Generally, the esterification step can be carried out without a catalyst (auto-catalysis), but usually, a metal compound is added to catalyze the esterification reaction. The esterification step can be carried out at a temperature of 200 °C or higher, more preferably at a temperature of 240 °C to 300 °C, and under a pressure of 1 to 10 bar.

[0083] The second step in the production of high molecular weight acyclic polyesters (e.g., PET) is the polycondensation process. Polycondensation is crucial for increasing the molecular weight of the polyester. The polycondensation reaction may involve two phases: a molten phase and a solid phase (SSP). Typically, the molten phase of the polycondensation process is carried out at a temperature range of 240°C to 300°C under reduced pressure of 4 mbar to 0.1 mbar. Typically, the SSP of the polycondensation process is carried out at a temperature of 190°C to 230°C, and may be carried out under nitrogen gas flow or under reduced pressure of 3 to 0.1 mbar.

[0084] The catalyst of the present invention, comprising an aluminum titanate compound, a barium titanate compound, a calcium titanate compound, a zinc titanate compound, or a mixture thereof, can be added to the molten phase of the polycondensation step. The amount of titanium added to the polyester polycondensation reaction as an aluminum titanate compound, a barium titanate compound, a calcium titanate compound, and / or a zinc titanate compound is 1 ppm to 100 ppm, preferably 5 ppm to 50 ppm, based on the weight of at least one polyacid and at least one polyol, or the weight of the polyester.

[0085] In preferred embodiments, aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds are added to the method of the present invention in powder form, preferably in nanopowder form with a primary particle size of less than 75 nm, more preferably less than 50 nm, and most preferably less than 25 nm. The particle size was evaluated based on SEM (scanning electron microscope) image analysis as described above. The catalyst can be added before the esterification reaction as a catalyst composition comprising an aluminum titanate compound (or barium titanate compound, or calcium titanate compound, or zinc titanate compound, or a mixture thereof) and at least one polyacid and at least one polyol.

[0086] In certain embodiments, if the catalyst contains an aluminum-titanium compound (or a barium titanate compound, or a calcium titanate compound, or a mixture thereof) and an antimony(III)-containing compound, both components can be added directly to the paste before the esterification reaction. Alternatively, the antimony catalyst may be dissolved in a suitable polyol such as ethylene glycol. The antimony catalyst-containing solution can then be added to the paste to catalyze the esterification or polycondensation reaction.

[0087] Advantageously, by adding aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof, instead of conventional titanium alcoholates (e.g., titanium tetrabutyrate), the acetaldehyde regeneration rate during processing is lower or equivalent to that of methods containing only antimony catalysts, even in the absence of inactivators (e.g., phosphoric acid or potassium acetate).

[0088] The product obtained by the method of the present invention can be further processed to obtain a PET bottle as described above. In a preferred embodiment, the product obtained by the polyester manufacturing method may be food-grade polyester.

[0089] In particular, the method of the present invention may further include a step of adding recycled polyethylene terephthalate. Preferably, 10 to 100% by weight of recycled polyethylene terephthalate based on the weight of the final polyester product can be added to the method of the present invention. More preferably, about 25 to 100% of the final polyethylene terephthalate based on the weight of the final polyester product can be replaced with recycled polyethylene terephthalate. The final product produced by the method of the present invention contains up to 100% recycled PET and is suitable for thermoforming applications such as beverage bottle manufacturing and film packaging.

[0090] The total amount of catalyst added to the polyester polycondensation reaction can be 1 ppm to 400 ppm, preferably 5 ppm to 200 ppm, and most preferably 1 ppm to 100 ppm, based on the weight of at least one polyacid and at least one polyol, or the weight of the final polyester.

[0091] According to a specific embodiment of the present invention, the above-described catalyst deactivator can be added to a polyester manufacturing method. Preferably, the catalyst deactivator is added to the polycondensation reaction.

[0092] As described above, by applying this method, it is possible to increase the polycondensation rate in the molten phase of the polycondensation reaction.

[0093] Furthermore, the present invention relates to the use of crystalline aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures thereof of these titanate compounds as heterogeneous catalysts in polyester polycondensation reactions.

[0094] When aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, zinc titanate compounds, or mixtures of these titanate compounds are used as catalysts for polycondensation reactions, yellowing of the final product is relatively less compared to when using conventional titanium-based catalysts such as titanium alkoleates, and therefore the discoloration of the final product is at a controllable level. [Examples]

[0095] PET was produced using a conventional antimony(III) catalyst or the crystalline titanium catalyst of the present invention by the following procedure: Monoethylene glycol (MEG) (242 g), 0.02 g of tetramethylammonium hydroxide (TMAH, used to suppress the formation of diethylene glycol) aqueous solution (25%), 250 ppm antimony (added as 0.6543 g of antimony glycolate), or 10, 15, or 20 ppm of titanium (added as 38, 57, or 76 ppm of crystalline aluminum titanate (AlTi), 73 ppm of crystalline barium titanate (BaTi), 43 ppm of crystalline calcium titanate (CaTi), or 51 ppm of crystalline zinc titanate (ZnTi), respectively), or crystalline magnesium titanate (MgTiO3) were placed in a glass beaker, mixed, and then added to the reactor. Under stirring, purified terephthalic acid and isophthalic acid (PTA and IPA: 500 g) were added to the glass beaker. The MEG / PTA paste was supplied to the reactor while stirring. After bringing the reactor to a complete vacuum, nitrogen gas was used to remove any trace amounts of oxygen. This procedure was repeated three times.

[0096] Esterification The reactor temperature and pressure settings for the esterification reaction were approximately 300°C and 4 bar (absolute pressure). The condensed ethylene glycol (EG) and water (at the top of the reactor) were collected in bottles. During the esterification reaction, the product temperature rose to approximately 260°C. The esterification reaction (E1) continued for approximately 120 minutes.

[0097] After esterification (E1), the pressure was reduced to 1.0 bar (absolute). The reaction mixture was stirred for a further 7.5 minutes at 1 bar (absolute) (E2), after which approximately 75% of the reaction mixture was withdrawn from the reactor.

[0098] Molten phase polycondensation The stirring speed was reduced to 30 rpm, and a reduced pressure of 40 mbar was applied for 1.5 minutes to initiate the polycondensation process. Afterward, a complete vacuum was applied.

[0099] During polycondensation, the product temperature rose to 270°C. The polycondensation was terminated when the power consumption of the electric stirrer reached a predetermined value.

[0100] Solid-phase polycondensation (SSP) The SSP reactor for Buchi products was a fixed-bed reactor manufactured by Roth. The reactor had a batch capacity of 22 g. The temperature was maintained at 210°C using a heating jacket. The dew point of the preheating nitrogen stream used was below -30°C, and it passed through the entire pellet layer from the bottom to the top of the reactor at a rate of 15 l / h.

[0101] Example 1: For conventional PET catalysts using antimony(III) (comparative example), magnesium titanium oxide (MgTiO3) (additional comparative example), and PET catalysts using 10, 15, and 20 ppm titanium (Ti, added as 38, 57, and 76 ppm AlTi, 73 ppm BaTi, 43 ppm CaTi, and 51 ppm ZnTi, respectively) according to the present invention, the reaction rate constants k for molten phase polycondensation and SSP polycondensation were individually determined per unit weight of the final polymer. The results are shown in Table 1.

[0102] [Table 1]

[0103] The results indicate that, in the case of a molten phase reaction, similar or even higher polycondensation rates can be achieved with very small amounts of Ti. The polycondensation rate of Ti-catalyzed PET in SSP is slightly lower than that of antimony-catalyzed PET.

[0104] Example 2: The color values ​​L*, a*, and b* are the average values ​​measured in polyester pellets, plaques, or other articles injection-molded or extruded from these. They are determined by the CIE (International Commission on Illumination) L*a*b* chromaticity system, where L* represents the lightness coordinate, a* represents the red / green coordinate, and b* represents the yellow / blue coordinate.

[0105] Color measurements were performed using a Konica Minolta CM-3700A spectrophotometer and SPECTRA Magic software, applying the following parameters to pellet measurements: Spectral range: 380~720nm Principle: Diffuse reflectance, d / 8°; SEC, UV 0% Cuvette: Height 50mm, Width 35mm, Depth 20mm Measurement spot: φ25mm Light source: Daylight D65 / 10 Standard: Black and white calibration

[0106] The sample was measured in pellet form. The cuvette was cleaned and filled to at least 85% of its maximum capacity. The sample was measured four times, using a new sample pellet for each measurement. The average value of all four measurements and the CIELab L*a*b* value were calculated using SPECTRA MAGIC software. The results are shown in Table 2.

[0107] [Table 2]

[0108] The results show that AlTi, BaTi, CaTi, ZnTi, and conventional antimony catalysts all cause yellowing (b* value greater than 0) in the final polymer. Favorably, when AlTi is used as a catalyst instead of conventional titanium alcohols (results not shown) in the condensation polymerization reaction, the yellowing of the final product is comparable to that of antimony-catalyzed PET. When BaTi, CaTi, or ZnTi are used as catalysts in the condensation polymerization reaction, the yellowing of the final product is slightly higher than that of antimony-catalyzed PET.

[0109] Example 3: The acetaldehyde content (AA) of processed PET was measured according to the following method: First, the sample was ground using a RETSCH ZM200 centrifugal mill with a 1 mm screen in the presence of liquid nitrogen. Approximately 0.1 g to 0.3 g of the ground sample was placed in a 22 ml sample bottle and sealed with a polytetrafluoroethylene seal. The sample bottle was controlled heating in a headspace oven (Perkin Elmer TurboMatrix-40 headspace autosampler) at 150 °C for 90 minutes, and then analyzed by gas chromatography using an external standard method (Perkin Elmer XL GC AutoSystem). Calibration curves were prepared by completely evaporating aqueous solutions of different AA concentrations.

[0110] The headspace autosampler conditions for acetaldehyde measurement are as follows: Oven temperature: 150℃ Needle temperature: 160℃ Transfer line temperature: 170℃ Holding time: 90 minutes Gas chromatograph conditions: Column: 1.8m x 1 / 8 inch stainless steel Filling material: Polapack Q, 80 / 100 mesh Carrier gas: Nitrogen, 30 ml / min Fuel gas: Hydrogen Air: Synthetic air Column temperature: 140℃ Detector temperature: 220℃

[0111] Table 3 shows the results of acetaldehyde content (AA) measurement. [Table 3]

[0112] It is remarkable that the acetaldehyde levels after PET treatment using AlTi, BaTi, or CaTi catalysts are equivalent to those of standard products using antimony catalysts. Importantly, this effect was achieved without the addition of phosphorus compounds (stabilizers) typically required for titanium catalysts. The conventional deactivation mechanism of titanium-based polycondensation catalysts is due to the formation of Ti-O-Ti bonds. This can be eliminated by fixing them within the crystalline lattice of the inorganic structure of AlTi, BaTi, or CaTi.

[0113] In summary, AlTi, BaTi, and CaTi were found to be excellent heterogeneous catalysts for PET polycondensation reactions. Discoloration during processing was controllable, and compared to antimony compounds, the acetaldehyde regeneration rate during the process was equivalent or lower, the polycondensation rate (molten phase) was improved or equivalent, and the polycondensation rate (SSP) was only slightly reduced. It was demonstrated that AlTi, BaTi, or CaTi can replace conventional antimony catalysts in polyester polycondensation reactions without adversely affecting the manufacturing process or the characteristics of the final product.

Claims

1. It comprises one or more catalysts, at least one polyacid, and at least one polyol. At least one catalyst is a titanate compound selected from aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and titanium zinc compounds, or a mixture of two, three, or four of the titanate compounds, wherein the aluminum titanate compound contains aluminum atoms, titanium atoms, and oxygen atoms; the barium titanate compound contains barium atoms, titanium atoms, and oxygen atoms; the calcium titanate compound contains calcium atoms, titanium atoms, and oxygen atoms; and the titanium zinc compound contains zinc, titanium, and oxygen atoms; and in the case of a mixture of two, three, or four of the titanate compounds, the mixture contains titanium atoms and oxygen atoms together with the respective atoms of aluminum, barium, calcium, and / or zinc; The titanate compound or the mixture of titanate compounds is in crystalline form. A composition for polyester polycondensation reaction.

2. The composition according to claim 1, wherein the amount of titanium in the composition as a crystalline titanate compound or a mixture of titanate compounds is 1 ppm to 100 ppm, preferably 4 ppm to 50 ppm, more preferably 8 ppm to 30 ppm, on a weight basis, based on the total weight of at least one polyacid and / or at least one polyol in the composition, or based on the polyester formed by the polyester polycondensation reaction.

3. The composition according to any one of the preceding claims, wherein the titanate compound or mixture of titanate compounds does not contain rare earth elements, and / or the titanate compound or mixture of titanate compounds does not contain organic groups.

4. The composition according to any one of the preceding claims, wherein one or more catalysts in the composition exclude a catalyst containing a rare earth element, and / or one or more catalysts in the composition exclude a catalyst containing an organic group.

5. The composition according to any one of the preceding claims, wherein the composition comprises an antimony compound in less than 200 ppm, preferably less than 100 ppm, and most preferably, the composition does not contain an antimony compound.

6. A composition according to any one of the preceding claims, a) The aluminum titanate compound is a mixed oxide containing aluminum oxide, titanium dioxide, and optionally crystal water; or b) The aluminum titanate compound consists of aluminum atoms, titanium atoms, oxygen atoms, and optionally crystal water; or a) The barium titanate compound is a mixed oxide containing barium oxide, titanium dioxide, and optionally crystal water; or b) The barium titanate compound consists of barium atoms, titanium atoms, oxygen atoms, and optionally crystal water; or a) The calcium titanate compound is a mixed oxide containing calcium oxide, titanium dioxide, and optionally crystal water; or b) The calcium titanate compound consists of calcium atoms, titanium atoms, oxygen atoms, and optionally crystal water; or a) The zinc titanate compound is a mixed oxide containing zinc oxide, titanium dioxide, and optionally crystal water; or b) The zinc titanate compound consists of zinc atoms, titanium atoms, oxygen atoms, and optionally crystal water; or a) The titanate compound mixture is a mixture of two, three, or four of the aforementioned mixed oxides, optionally accompanied by crystal water; or b) The titanate compound mixture consists of titanium atoms and oxygen atoms, and atoms of aluminum, barium, calcium, and / or zinc, optionally accompanied by crystal water. composition.

7. A composition according to any one of the preceding claims, Aluminum titanate compounds, crystalline Al ２ O ３ and crystalline TiO ２ Prepared by sintering a mixture containing or consisting of these; or Barium titanate compounds, crystalline BaCO ３ and crystalline TiO ２ Prepared by sintering a mixture containing or consisting of these; or Calcium titanate compounds are crystalline CaCO3 ３ and crystalline TiO ２ Prepared by sintering a mixture containing or consisting of these; or Zinc titanate compounds are crystalline ZnO and crystalline TiO ２ Prepared by sintering a mixture containing or consisting of these; or A mixture of titanate compounds is prepared by sintering a mixture that contains, or consists of, two, three, or four of crystalline TiO ２ , crystalline Al ２ O ３ , crystalline BaCO ３ , crystalline CaCO ３ , and crystalline ZnO. Preferably, a composition comprising an aluminum titanate compound, a barium titanate compound, a calcium titanate compound, a zinc titanate compound, or a mixture of titanate compounds, wherein the average primary particle diameter measured according to the definitions described in the specification is in the range of 100 nm to 500 μm, preferably 300 nm to 100 μm, more preferably 400 nm to 50 μm, and most preferably 500 nm to 2000 nm.

8. A composition according to any one of the preceding claims, The aluminum titanate compound is prepared by a wet chemical process comprising the steps of reacting an aluminum compound with a titanium compound in a solvent, precipitating the reaction product, and calcining the precipitated reaction product, wherein the aluminum titanate compound has an average primary particle diameter of less than 100 nm, preferably less than 50 nm, and most preferably less than 25 nm, as measured according to the definition described in the specification; or The barium titanate compound is produced by a wet chemical process comprising the steps of reacting a barium compound with a titanium compound in a solvent, precipitating the reaction product, and calcining the precipitated reaction product, wherein the barium titanate compound has an average primary particle diameter of less than 100 nm, preferably less than 50 nm, and most preferably less than 25 nm, as measured according to the definition described in the specification; or The calcium titanate compound is produced by a wet chemical process comprising the steps of reacting a calcium compound with a titanium compound in a solvent, precipitating the reaction product, and calcining the precipitated reaction product, wherein the calcium titanate compound has an average primary particle diameter of less than 100 nm, preferably less than 50 nm, most preferably less than 25 nm, as measured according to the definition described in the specification, or A composition comprising a zinc titanate compound produced by a wet chemical process including the steps of reacting a zinc compound with a titanium compound in a solvent, precipitating the reaction product, and calcining the precipitated reaction product, wherein the zinc titanate compound preferably has an average primary particle diameter of less than 100 nm, preferably less than 50 nm, and most preferably less than 25 nm, as measured according to the definition described in the specification.

9. The composition according to any one of the preceding claims, wherein at least one polyacid is terephthalic acid and at least one polyol is ethylene glycol.

10. A method for manufacturing polyester, Using one or more catalysts, The aforementioned method, A step of supplying a reaction mixture containing at least one polyacid and at least one polyol; A step of esterifying at least one polyacid and at least one polyol in a reaction mixture in the presence of optionally one or more catalysts to produce monomers; The process includes a step of polymerizing monomers in a reaction mixture by polycondensation in the presence of one or more catalysts to form a polyester. At least one catalyst is an aluminum titanate compound containing aluminum, titanium, and oxygen atoms; or At least one catalyst is a barium titanate compound containing barium, titanium, and oxygen atoms; or At least one catalyst is a calcium titanate compound containing calcium, titanium, and oxygen atoms; or At least one catalyst is a zinc titanate compound containing zinc, titanium, and oxygen atoms; or At least one catalyst is a mixture of two, three, or four titanate compounds, each containing titanium atoms and oxygen atoms together with atoms of aluminum, barium, calcium, and / or zinc. A method for obtaining titanate compounds or mixtures of titanate compounds in crystalline form.

11. The method according to claim 10, further comprising the step of adding 10 to 100% by weight of recycled polyethylene terephthalate with respect to the total amount of at least one polyacid and at least one polyol provided, before or during the esterification step and / or before or during the polycondensation step.

12. The use of a crystalline titanate compound as a heterogeneous catalyst in a polyester polycondensation reaction, wherein the titanate compound is selected from the group consisting of aluminum titanate compounds, barium titanate compounds, calcium titanate compounds, and zinc titanate compounds, or the titanate compound is a mixture of two, three, or four of the titanate compounds.

Images