WO2018124294A1

WO2018124294A1 - Polyester, and production method therefor and molded article made therefrom

Info

Publication number: WO2018124294A1
Application number: PCT/JP2017/047333
Authority: WO
Inventors: 宗一郎田邉; 豪坂野
Original assignee: 株式会社クラレ
Priority date: 2016-12-29
Filing date: 2017-12-28
Publication date: 2018-07-05
Also published as: TWI754709B; JP7033553B2; JPWO2018124294A1; TW201835184A

Abstract

Provided is a polyester which contains at least 50 mol% of a terephthalic acid unit with respect to the sum total of dicarboxylic acid units, and which contains at least 50 mol% of an ethylene glycol unit with respect to the sum total of diol units, and which is obtained by polycondensation of a dicarboxylic acid and a diol in the presence of: a cobalt compound (M); at least one type of phosphorus compound (P) selected from the group consisting of phosphoric acid, phosphorous acid, organo-phosphonic acid, and esters thereof; and a poly-carboxylic acid (X) having an α,β-dicarboxylic acid unit, wherein the cobalt compound (M) is added in an amount of 0.0005-0.05 parts by mass in terms of cobalt element with respect to 100 parts by mass of the sum total of dicarboxylic acids, the molar ratio (P/M) of the phosphorus atoms in the phosphorus compound (P) with respect to the cobalt atoms in the cobalt compound (M) is 0.01-10, and the molar ratio (X/M) of the poly-carboxylic acid (X) with respect to the cobalt atoms in the cobalt compound (M) is 0.01-10. Such polyester exhibits a good color tone, and molded articles obtained using said polyester are highly transparent and exhibit excellent impact resistance.

Description

Polyester, method for producing the same, and molded article comprising the same

The present invention relates to a polyester having high transparency, good color tone and excellent impact resistance, a method for producing the same, and a molded product comprising the same.

Polyesters such as polyethylene terephthalate are excellent in properties such as transparency, mechanical properties, gas barrier properties, and flavor barrier properties. Furthermore, polyester has less concern about residual monomers and harmful additives when formed into molded articles, and is excellent in hygiene and safety. Therefore, polyester has been widely used in recent years as a hollow container for filling beverages, seasonings, oils, cosmetics, detergents, etc. as an alternative to the conventionally used vinyl chloride, taking advantage of these properties. .

As a molding method for producing a hollow molded product made of polyester, a resin melted and plasticized through a die orifice is extruded as a cylindrical parison, and the parison is sandwiched between molds while it is in a softened state. An extrusion blow molding method is known in which molding is performed by blowing a fluid. Compared with the injection blow molding method, this method is simpler and does not require advanced technology for the production and molding of the mold. Suitable for varieties and small volume production. In addition, there is an advantage that it is possible to manufacture a molded product having a complicated shape having a thin object, a deep object, a large object, a handle, and the like.

By the way, containers for cosmetics and oils are required to have excellent mechanical properties in order to prevent damage due to impact such as dropping in addition to excellent properties such as chemical resistance and gas barrier properties. It is done. Further, cosmetic containers and the like are required to have a glass-like texture and appearance. However, polyester is colored yellow during molding. For this reason, a blueing agent is often used to improve the color tone, and in particular, a deep blue cobalt compound or the like is used.

However, when a cobalt compound is added at the time of polymerization, there is a problem that foreign matter is generated in a molded product such as a film, a cup, or a sheet by aggregating in a polymerization tank and remaining in the polyester. Furthermore, since the yellowish color of the resin is canceled with the blue color derived from the cobalt compound, there is a problem that the transparency of the polyester is lowered.

In Patent Document 1, a polyester resin in which 50 to 95 mol% of the acid component constituting the polyester is terephthalic acid, 2 to 20 mol% is isophthalic acid, and 80 mol% or more of the glycol component is ethylene glycol. Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane is contained in an amount of 0.1 to 1.0% by mass, and the germanium compound is added to 1 mol of the acid component of the polyester resin. 5 × 10 ⁻⁵ mol to 3.0 × 10 ⁻⁴ mol, a cobalt compound containing 1 × 10 ⁻⁵ to 2.0 × 10 ⁻⁴ mol per mol of the acid component of the polyester resin, and an alkali metal compound Describes a polyester resin composition containing 1.0 × 10 ⁻⁴ to 1.0 × 10 ⁻³ mol per mol of the acid component of the polyester resin. And such a polyester resin composition is excellent in thermal stability without causing the problem of whitening due to drawdown or crystallization at the time of direct blow molding, and by using the polyester resin composition, the color tone, It is described that a direct blow molded article excellent in transparency can be obtained with high productivity. However, the polyester resin composition still has insufficient color tone and transparency of the obtained molded product, and may have insufficient impact resistance.

JP 2012-224836 A

The present invention has been made to solve the above problems, and provides a polyester capable of obtaining a molded article having high transparency, good color tone, and excellent impact resistance, and a method for producing the same. With the goal.

The above-mentioned problem is a polyester containing 50 mol% or more of terephthalic acid units with respect to the total of dicarboxylic acid units, and containing 50 mol% or more of ethylene glycol units with respect to the total of diol units, Polyhydric carboxylic acid having at least one phosphorus compound (P) selected from the group consisting of cobalt compound (M), phosphoric acid, phosphorous acid, organic phosphonic acid and esters thereof and α, β-dicarboxylic acid unit In the presence of (X), a polycarboxylic acid and a diol are polycondensed, and the addition amount of the cobalt compound (M) with respect to a total of 100 parts by mass of the dicarboxylic acid is 0.0005 to 0.05 mass in terms of cobalt element. The molar ratio (P / M) of the phosphorus atom in the phosphorus compound (P) to the cobalt atom in the cobalt compound (M) is 0. And having a molar ratio (X / M) of the polyvalent carboxylic acid (X) to the cobalt atom in the cobalt compound (M) of 0.01 to 10 to solve the problem. The

At this time, the phosphorus compound (P) is preferably at least one of phosphorous acid and phosphoric acid. It is also preferred that the polyvalent carboxylic acid (X) has a hydroxyl group. It is also preferred that the polyvalent carboxylic acid (X) is a tricarboxylic acid. It is particularly preferable that the polyvalent carboxylic acid (X) is citric acid.

It is preferable that the polyester further contains 0.1 to 20 mol% of a unit derived from a bisphenol A ethylene oxide adduct based on the total of the diol units. It is also preferable that the polyester further contains 0.1 to 45 mol% of cyclohexanedimethanol units with respect to the total of the diol units. The polyester preferably further contains 0.1 to 20 mol% of isophthalic acid units based on the total of the dicarboxylic acid units.

A molded product formed by extruding the polyester is a preferred embodiment of the present invention. A container made of the molded product is a more preferred embodiment of the present invention. Moreover, the film or sheet which consists of the said molded article is also a more suitable embodiment of this invention, and the thermoformed article formed by thermoforming the said film or sheet is a more suitable embodiment.

A molded product obtained by thermoforming the polyester is also a preferred embodiment of the present invention.

The above-mentioned problem can also be solved by providing a method for producing the polyester, in which a dicarboxylic acid and a diol are polycondensed in the presence of a cobalt compound (M), a phosphorus compound (P) and a polyvalent carboxylic acid (X).

Since the cobalt compound (M) in the polyester of the present invention is uniformly dispersed and has few coarse aggregates, the polyester has a good color tone, and a molded product obtained using such a polyester is transparent. High impact resistance. According to the production method of the present invention, such a polyester can be produced easily.

It is a figure which shows distribution of the particle diameter in polyester obtained in Example 2 and Comparative Example 1.

The polyester of the present invention is a polyester containing 50 mol% or more of terephthalic acid units with respect to the total of dicarboxylic acid units and containing 50 mol% or more of ethylene glycol units with respect to the total of diol units; Is a polyvalent compound having at least one phosphorus compound (P) selected from the group consisting of a cobalt compound (M), phosphoric acid, phosphorous acid, organic phosphonic acid and esters thereof and an α, β-dicarboxylic acid unit. This is formed by polycondensation of dicarboxylic acid and diol in the presence of carboxylic acid (X); the amount of cobalt compound (M) added to 100 parts by mass of dicarboxylic acid is 0.0005-0. The molar ratio of the phosphorus atom in the phosphorus compound (P) to the cobalt atom in the cobalt compound (M) ( P / M) is 0.01 to 10; and the molar ratio (X / M) of the polyvalent carboxylic acid (X) to the cobalt atom in the cobalt compound (M) is 0.01 to 10. .

The polyester contains terephthalic acid (TA) units in an amount of 50 mol% or more based on the total of dicarboxylic acid units. Here, the total of dicarboxylic acid units is the total of dicarboxylic acid units having no α, β-dicarboxylic acid units in the polyester. When the polyester contains terephthalic acid units in an amount of 50 mol% or more, the melt viscosity becomes appropriate and the impact resistance of the obtained molded article is improved. Furthermore, the thermal stability during molding is improved. The content of terephthalic acid units is preferably 80 mol% or more.

The polyester contains 50 mol% or more of ethylene glycol units with respect to the total of diol units. Thereby, when manufacturing the said polyester, since solid phase polymerization can be performed at high temperature, while improving productivity, a molded article with a more favorable color tone comes to be obtained. The content of ethylene glycol units is preferably 75 mol% or more. Usually, a polyester obtained using ethylene glycol as a raw material diol contains 1 to 5 mol% of diethylene glycol units, which are by-products in the condensation polymerization reaction, based on the total of diol units.

The structural unit contained in the polyester may be only a unit derived from a polyvalent carboxylic acid (X) having a terephthalic acid unit, an ethylene glycol unit, a diethylene glycol unit and an α, β-dicarboxylic acid unit, The polyester preferably further contains 0.1 to 20 mol% of isophthalic acid (IPA) units based on the total of the dicarboxylic acid units. Here, the total of dicarboxylic acid units is the total of dicarboxylic acid units having no α, β-dicarboxylic acid units in the polyester. When the content of the isophthalic acid unit is 0.1 mol% or more, the chemical resistance is further improved. The content is more preferably 2 mol% or more. On the other hand, when the content of the isophthalic acid unit exceeds 20 mol%, when solid phase polymerization is performed, sticking due to softening of the resin is likely to occur, and therefore the solid phase polymerization temperature cannot be increased, and thus productivity may be reduced. There is. The content of isophthalic acid units is more preferably 15 mol% or less.

It is also preferable that the polyester further contains 0.1 to 20 mol% of units derived from bisphenol A ethylene oxide adduct (EOBPA) based on the total of the diol units. Thereby, the drawdown resistance at the time of extruding the polyester is further improved. The bisphenol A ethylene oxide adduct is obtained by adding at least one ethylene oxide to each hydroxyl group of bisphenol A. The addition amount of ethylene oxide is usually 2 to 4 mol with respect to 1 mol of bisphenol A.

In view of obtaining the above-described effects, the content of the unit derived from the bisphenol A ethylene oxide adduct in the polyester is more preferably 0.5 mol% or more, and further preferably 2 mol% or more. On the other hand, when the content is 20 mol% or less, the melt viscosity of the polyester becomes appropriate, and the impact resistance of the obtained molded product is further improved. The content is more preferably 15 mol% or less, further preferably 10 mol% or less, and particularly preferably 8 mol% or less.

The polyester preferably further contains cyclohexanedimethanol (CHDM) units in an amount of 0.1 to 45 mol% based on the total of the diol units. The cyclohexanedimethanol unit in the polyester may be at least one divalent unit selected from 1,2-cyclohexanedimethanol unit, 1,3-cyclohexanedimethanol unit and 1,4-cyclohexanedimethanol unit. . Among these, cyclohexanedimethanol is easy to obtain, easy to make the polyester crystalline, difficult to cause sticking between pellets during solid phase polymerization, and further improves the impact resistance of the resulting molded product. The unit is preferably 1,4-cyclohexanedimethanol unit.

There are cis and trans isomers in the cyclohexanedimethanol unit, but the ratio of the cis and trans isomers in the cyclohexanedimethanol unit in the polyester is not particularly limited. In particular, in the cyclohexanedimethanol unit in the polyester, the ratio of cis isomer: trans isomer is in the range of 0: 100 to 50:50, which makes it easy to make the polyester crystalline. This is preferable from the viewpoint that sticking between the pellets hardly occurs and the impact resistance of the obtained molded product is further improved.

When the polyester contains 0.1 mol% or more of cyclohexanedimethanol units, the resulting molded article has further improved impact resistance at room temperature and low temperature, and further improved transparency. The content is more preferably 2 mol% or more, further preferably 4 mol% or more, and particularly preferably 6 mol% or more. On the other hand, when the content of the cyclohexanedimethanol unit is 45 mol% or less, a polyester having a high degree of polymerization is obtained. The content is more preferably 30 mol% or less. And it is further more preferable that the said content is 15 mol% or less. By subjecting polyester having a content of 15 mol% or less to a pre-crystallization treatment, drying at a temperature higher than the glass transition temperature becomes possible, and the moisture content can be reduced, resulting in a decrease in intrinsic viscosity due to hydrolysis during molding. Can be suppressed.

The total content of terephthalic acid units and ethylene glycol units in the polyester is 50 mol% or more based on the total of all structural units in the polyester. Thereby, when manufacturing the said polyester by solid-phase polymerization, since the sticking by softening of resin is suppressed, a polymerization degree can be raised easily. The content is preferably 75 mol% or more, more preferably 85 mol% or more, and further preferably 90 mol% or more.

If necessary, the polyester may be a polyvalent compound having a terephthalic acid unit, an ethylene glycol unit, a diethylene glycol unit, an isophthalic acid unit, a cyclohexanedimethanol unit, a unit derived from a bisphenol A ethylene oxide adduct and an α, β-dicarboxylic acid unit. You may contain other comonomer units other than the unit derived from carboxylic acid (X).

The other comonomer unit preferably has 5 or more carbon atoms. When the number of carbon atoms is less than 5, the comonomer boiling point of the raw material is lowered and volatilizes during the condensation polymerization reaction, so that it may be difficult to recover ethylene glycol. The upper limit of the carbon number is not particularly limited, but is usually 50 or less. The other comonomer unit contained in the polyester may be one type or two or more types.

Bifunctional compound units are mainly used as other comonomer units. The content of other bifunctional compound units (the total when two or more units are included) is preferably 20 mol% or less with respect to the total of all structural units constituting the polyester. It is more preferably at most mol%, further preferably at most 5 mol%. Other bifunctional compound units that can be contained in the polyester include terephthalic acid units, ethylene glycol units, diethylene glycol units, isophthalic acid units, cyclohexane dimethanol units, units derived from bisphenol A ethylene oxide adducts and α, Other than dicarboxylic acids having β-dicarboxylic acid units. If the other bifunctional compound unit is a dicarboxylic acid unit, a diol unit, or a hydroxycarboxylic acid unit, an aliphatic bifunctional compound unit, an alicyclic bifunctional compound unit, or an aromatic bifunctional compound unit Any of these may be used.

Aromatic dicarboxylic acid units used as other comonomer units include furandicarboxylic acid (FDCA), phthalic acid, 5- (alkali metal) sulfoisophthalic acid, diphenic acid, 1,3-naphthalenedicarboxylic acid, 1,4 -Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-biphenylsulfonedicarboxylic acid, 4, Mention may be made of units derived from aromatic dicarboxylic acids such as 4′-biphenyl ether dicarboxylic acid, pamoic acid, anthracene dicarboxylic acid or their ester-forming derivatives.

Examples of aliphatic dicarboxylic acid units used as other comonomer units include dimer acid, hydrogenated dimer acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, Undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosanedioic acid, docosanedioic acid, fumaric acid, itaconic acid, etc. Aliphatic dicarboxylic acid, 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,1-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, , 3-Cyclohexanedicarboxylic acid, decahydronaphthalene List units derived from aliphatic dicarboxylic acids such as rubonic acid (decalin dicarboxylic acid), tetralin dicarboxylic acid, cyclobutene dicarboxylic acid, tricyclodecane dicarboxylic acid, norbornane dicarboxylic acid, adamantane dicarboxylic acid or their ester-forming derivatives. Can do.

Examples of aliphatic diol units used as other comonomer units include triethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, isosorbide, , 2-propanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 3-methyl-1,5-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, tetra Examples thereof include units derived from aliphatic diols such as methylcyclobutanediol, 1,9-nonanediol, dimer diol having 36 carbon atoms, and dimer diol having 44 carbon atoms, or ester-forming derivatives thereof.

Hydroxycarboxylic acids used as other comonomer units include aliphatic hydroxycarboxylic acids such as 10-hydroxyoctadecanoic acid or ester-forming derivatives thereof; hydroxymethylcyclohexanecarboxylic acid, hydroxymethylnorbornenecarboxylic acid, hydroxymethyltricyclohexane Alicyclic hydroxycarboxylic acids such as decanecarboxylic acid or ester-forming derivatives thereof; hydroxybenzoic acid, hydroxytoluic acid, hydroxynaphthoic acid, 3- (hydroxyphenyl) propionic acid, hydroxyphenylacetic acid, 3-hydroxy-3- Aromatic hydroxycarboxylic acids such as phenylpropionic acid and their ester-forming derivatives.

The polyester has a carboxyl group, a hydroxyl group, in addition to a unit derived from a polyvalent carboxylic acid (X) having an α, β-dicarboxylic acid unit as another comonomer unit, as long as the effects of the present invention are not impaired. And / or a polyfunctional compound unit derived from a polyfunctional compound having three or more ester-forming groups thereof can be used. When the polyester contains such a polyfunctional compound unit, inflation moldability is improved. The content of other polyfunctional compound units (the total when two or more units are included) is preferably 0.00005 to 1 mol% based on the total of the structural units of the polyester. The amount is more preferably 0.0015 to 0.8 mol%, and further preferably 0.00025 to 0.4 mol%. Among other polyfunctional compound units, trifunctional compound units and tetrafunctional compound units are preferred. Other polyfunctional compound units are preferably polyvalent carboxylic acid units derived from trimellitic acid, trimesic acid and the like; polyhydric alcohol units derived from trimethylolpropane, glycerin and the like.

Examples of the polyfunctional compound unit include a carboxylic acid ester of a trivalent or higher polyol, wherein the carboxylic acid is derived from a polyvalent ester having a hindered phenol group. Examples of the polyvalent ester include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris [2- [3- (3,5-di- -Tert-butyl-4-hydroxyphenyl) propanoyloxy] ethyl] hexahydro-1,3,5-triazine-2,4,6-trione and the like.

Further, if necessary, the polyester has a monofunctional compound unit derived from at least one monofunctional compound of monocarboxylic acid, monoalcohol and ester-forming derivatives thereof as another comonomer unit. It may be. The monofunctional compound unit functions as a sealing compound unit and seals molecular chain end groups and / or branched chain end groups in the polyester, thereby preventing excessive crosslinking and gel generation in the polyester. When the polyester has such a monofunctional compound unit, the content of the monofunctional compound unit (the total when there are two or more units) is based on the total of all the structural units of the polyester. It is preferably 1 mol% or less, and more preferably 0.5 mol% or less. When content of the monofunctional compound unit in the said polyester exceeds 1 mol%, the polymerization rate at the time of manufacturing the said polyester will become slow, and productivity will fall easily. Examples of the monofunctional compound unit include units derived from a monofunctional compound selected from benzoic acid, 2,4,6-trimethoxybenzoic acid, 2-naphthoic acid, stearic acid and stearyl alcohol.

The polyester has at least one phosphorus compound (P) selected from the group consisting of a cobalt compound (M), phosphoric acid, phosphorous acid, organic phosphonic acid, and esters thereof, and an α, β-dicarboxylic acid unit. A product obtained by polycondensation of a dicarboxylic acid and a diol in the presence of the polyvalent carboxylic acid (X). Here, the dicarboxylic acid as a raw material monomer does not have an α, β-dicarboxylic acid unit.

Thus, at the time of polycondensation, together with the cobalt compound (M), at least one phosphorus compound (P) selected from the group consisting of phosphoric acid, phosphorous acid, organic phosphonic acid and esters thereof and α, β- By using the polyvalent carboxylic acid (X) having a dicarboxylic acid unit, a polyester having a good color tone can be obtained. Further, by using the polyester, a molded product having high transparency and excellent impact resistance can be obtained. It is considered that the dispersibility of the cobalt compound (M) is improved by using the phosphorus compound (P) and the polyvalent carboxylic acid (X). And since a cobalt compound (M) disperse | distributes uniformly in the said polyester, while the color tone improvement effect by a cobalt compound (M) is show | played efficiently, the fall of the transparency by a cobalt compound (M) is also suppressed. It is thought that. Moreover, it is thought that the impact resistance of the obtained molded article is improved by suppressing the generation of coarse aggregates of the cobalt compound (M). Further, conventionally, aggregates of cobalt compounds generated during polycondensation have been removed with a filter. And the said filter produced clogging in a short time, and was reducing productivity. On the other hand, since the polyester of the present invention has few coarse aggregates of the cobalt compound (M), the filter replacement interval becomes longer, and the productivity is improved.

Examples of the cobalt compound (M) used in the present invention include cobalt salts of organic acids such as cobalt acetate, cobalt oxide and the like. Among these, acetic acid is soluble in alcohol and easy to handle during production. Cobalt is preferred. The added amount of the cobalt compound (M) is 0.0005 to 0.05 parts by mass in terms of cobalt element with respect to 100 parts by mass of the total dicarboxylic acid. Here, the total of dicarboxylic acid units is the total of dicarboxylic acid units having no α, β-dicarboxylic acid units in the polyester. At the time of polymerization, by adding 0.0005 parts by mass or more of the cobalt compound (M) to 100 parts by mass of the total dicarboxylic acid, the color tone of the obtained polyester is improved, and a molded product obtained using the polyester Improves impact resistance. 0.001 mass part or more is preferable and, as for the addition amount of a cobalt compound (M), 0.002 mass part or more is more preferable. On the other hand, when the addition amount of the cobalt compound (M) is 0.05 parts by mass or less with respect to a total of 100 parts by mass of the dicarboxylic acid during the polymerization, the polymerization reaction is not inhibited. The addition amount of the cobalt compound (M) is preferably 0.02 parts by mass or less.

In the present invention, a polyvalent carboxylic acid (X) having an α, β-dicarboxylic acid unit is used together with the cobalt compound (M) during polycondensation. The polyvalent carboxylic acid (X) having an α, β-dicarboxylic acid unit is considered to easily interact with the cobalt compound (M), which is one factor for improving the dispersibility of the cobalt compound (M). it is conceivable that. From the viewpoint of further improving the dispersibility of the cobalt compound (M), the polyvalent carboxylic acid (X) preferably has a hydroxyl group. From the same viewpoint, the polycarboxylic acid (X) is preferably a tricarboxylic acid. Examples of the polyvalent carboxylic acid (X) having an α, β-dicarboxylic acid unit include citric acid, tartaric acid, succinic acid, fumaric acid, maleic acid and the like. Among these, citric acid, tartaric acid and succinic acid are preferable. Acid and succinic acid are more preferable, and citric acid is more preferable. At least a part of the polyvalent carboxylic acid (X) having an α, β-dicarboxylic acid unit or a decomposition product thereof may be contained in the main chain, branched chain or terminal of the polyester.

In polycondensation, the amount of polyvalent carboxylic acid (X) added so that the molar ratio (X / M) of polyvalent carboxylic acid (X) to cobalt atoms in cobalt compound (M) is 0.01 to 10 Adjust. When the molar ratio (X / M) is 0.01 or more, the dispersibility of the cobalt compound (M) in the polyester is improved. The molar ratio (X / M) is preferably 0.1 or more, more preferably 0.5 or more, and still more preferably 1 or more. On the other hand, when the molar ratio (X / M) is 10 or less, the polymerization reaction is not inhibited, and the hue of the resin and the transparency of the molded product are excellent. The molar ratio (X / M) is preferably 5 or less.

In the present invention, at the time of polycondensation, at least one phosphorus compound (P) selected from the group consisting of phosphoric acid, phosphorous acid, organic phosphonic acid and esters thereof is used together with the cobalt compound (M). The phosphoric acid used as the phosphorus compound (P) may be orthophosphoric acid or polyphosphoric acid such as pyrophosphoric acid. The phosphoric acid ester used as the phosphorous compound (P) is preferably a monoester or diester of phosphoric acid and an aliphatic monoalcohol having 1 to 20 carbon atoms, such as dibutyl phosphate, diethyl phosphate, dimethyl phosphate. It is more preferable that The phosphite used as the phosphorus compound (P) is preferably a monoester of phosphorous acid and an aliphatic monoalcohol having 1 to 20 carbon atoms. The organic phosphonic acid used as the phosphorus compound (P) is preferably an alkyl phosphonic acid. In the alkylphosphonic acid, the alkyl group directly bonded to the phosphorus atom preferably has 1 to 20 carbon atoms. The organic phosphonic acid ester used as the phosphorus compound (P) is preferably a monoester of the organic phosphonic acid and an aliphatic monoalcohol having 1 to 20 carbon atoms. Especially, it is preferable that the phosphorus compound (P) used for this invention is at least 1 sort (s) of phosphorous acid or phosphoric acid, and it is more preferable that it is phosphorous acid.

The amount of phosphorus compound (P) added so that the molar ratio (P / M) of the phosphorus atom in the phosphorus compound (P) to the cobalt atom in the cobalt compound (M) is 0.01 to 10 during the polycondensation Adjust. When the molar ratio (P / M) is 0.01 or more, the color tone of the obtained polyester is improved. Moreover, the thermal stability of the molded article obtained using the said polyester improves by the antioxidant effect of a phosphorus compound (P). The molar ratio (P / M) is preferably 0.1 or more, more preferably 1 or more, and further preferably 1.5 or more. On the other hand, when the molar ratio (P / M) is 10 or less, the polymerization reaction is not inhibited. The molar ratio (P / M) is preferably 5 or less.

In the presence of the cobalt compound (M), the phosphorus compound (P) and the polyvalent carboxylic acid (X), a method of polycondensing a dicarboxylic acid (a dicarboxylic acid having no α, β-dicarboxylic acid unit) and a diol is particularly preferable. Without limitation, esterification reaction or ester using terephthalic acid, ethylene glycol or ester-forming derivatives thereof, and optionally using cyclohexanedimethanol, bisphenol A ethylene oxide adduct, isophthalic acid, or other comonomer After the exchange reaction, a method of melt polycondensation of the obtained polyester oligomer can be mentioned. The timing of adding the cobalt compound (M), the phosphorus compound (P) and the polyvalent carboxylic acid (X) is not particularly limited, and may be added before the esterification reaction or transesterification reaction. Although it may be added after the reaction, the former is preferred. Further, the cobalt compound (M), the phosphorus compound (P) and the polyvalent carboxylic acid (X) may be added separately, or the cobalt compound (M), the phosphorus compound (P) and the polyvalent carboxylic acid (X). ), At least two of them may be mixed in advance, and the resulting mixture may be added to other raw materials.

Further, the polyvalent ester may be added before the esterification reaction or transesterification reaction, or may be added after the reaction. Further, other raw materials and polymerization catalyst can be appropriately added before the esterification reaction or transesterification reaction, or after these reactions have been performed.

The above esterification reaction or transesterification reaction is carried out by adding a cobalt compound (M), a phosphorus compound (P), a polyvalent carboxylic acid (X), a raw material monomer, a polymerization catalyst, and other additives described later as required. It is preferably carried out while distilling off the produced water or alcohol at a temperature of 160 to 280 ° C. under a pressure of about 0.5 MPa or less in absolute pressure or at normal pressure.

The melt polycondensation reaction following the esterification reaction or transesterification reaction is carried out by subjecting the obtained polyester oligomer to a cobalt compound (M), a phosphorus compound (P), a polyvalent carboxylic acid (X), a raw material monomer, It is preferable to add a polycondensation catalyst and other additives described later, under a reduced pressure of 1 kPa or less, at a temperature of 260 to 290 ° C. until a polyester having a desired viscosity is obtained. When the reaction temperature of the melt polycondensation reaction is less than 260 ° C., the polymerization activity of the polymerization catalyst is low, and there is a possibility that a polyester having a target degree of polymerization cannot be obtained. On the other hand, when the reaction temperature of the melt polymerization reaction exceeds 290 ° C., the decomposition reaction easily proceeds, and as a result, there is a possibility that a polyester having a target degree of polymerization cannot be obtained. The melt polycondensation reaction can be performed using, for example, a tank-type batch polycondensation apparatus or a continuous polycondensation apparatus including a biaxial rotating horizontal reactor.

As the polymerization catalyst used for the condensation polymerization, any catalyst that can be used for the production of polyester can be selected, but a compound containing a germanium element or an antimony element is preferable. Of these, germanium dioxide and antimony trioxide are preferable from the viewpoint of polymerization catalyst activity, physical properties of the resulting polyester, and cost, and the former is more preferable from the viewpoint of transparency and color tone. When a polycondensation catalyst is used, the amount added is within the range of 0.002 to 0.8 mass% based on the mass of the dicarboxylic acid (dicarboxylic acid having no α, β-dicarboxylic acid unit) component. Is preferred.

The intrinsic viscosity of the polyester obtained by melt polycondensation is preferably 0.4 dl / g or more. Thereby, the handleability is improved and, when the polyester obtained by melt polycondensation is further solid-phase polymerized, the molecular weight can be increased in a short time, so that productivity is improved. The intrinsic viscosity is more preferably 0.55 dl / g or more, and still more preferably 0.65 dl / g or more. On the other hand, the intrinsic viscosity is preferably 0.9 dl / g or less, more preferably 0.85 dl / g or less, from the viewpoint that polyester can be easily taken out from the reactor and coloring due to thermal deterioration is suppressed. More preferably, it is 0.8 dl / g or less.

The polyester thus obtained is suitably used as a raw material for extrusion molding. It is also preferred to further solid-phase polymerize the polyester obtained by melt polycondensation. The solid phase polymerization will be described below.

The polyester obtained as described above is extruded into a strand shape, a sheet shape, and the like, cooled, and then cut with a strand cutter, a sheet cutter, or the like to have a shape such as a column shape, an elliptical column shape, a disk shape, or a die shape. Intermediate pellets are produced. The above-described cooling after extrusion can be performed by, for example, a water cooling method using a water tank, a method using a cooling drum, an air cooling method, or the like.

In order to further increase the degree of polymerization of the intermediate pellets thus obtained, solid phase polymerization is performed. It is preferable to crystallize a part of the polyester by heating before solid phase polymerization. By doing so, it is possible to prevent the pellets from sticking during solid phase polymerization. The crystallization temperature is preferably 100 to 180 ° C. As a crystallization method, crystallization may be performed in a vacuum tumbler, or crystallization may be performed by heating in an air circulation type heating apparatus. When heating in an air circulation heating device, the internal temperature is preferably 100 to 160 ° C. When heating using an air circulation type heating device, compared with crystallization using a vacuum tumbler, heat conduction is good, so the time required for crystallization can be shortened and the device is also inexpensive. The time required for crystallization is not particularly limited, but is usually about 30 minutes to 24 hours. It is also preferred to dry the pellets at a temperature below 100 ° C. prior to crystallization.

The temperature of solid phase polymerization is preferably 170 to 250 ° C. When the temperature of the solid phase polymerization is lower than 170 ° C., the time for the solid phase polymerization becomes long and the productivity may be lowered. The temperature of solid phase polymerization is more preferably 175 ° C. or higher, and further preferably 180 ° C. or higher. On the other hand, when the temperature of the solid phase polymerization exceeds 250 ° C., the pellets may be stuck. The temperature of the solid phase polymerization is more preferably 240 ° C. or lower, and further preferably 230 ° C. or lower. The time for solid phase polymerization is usually about 5 to 70 hours.

Further, the solid phase polymerization is preferably performed under reduced pressure or in an inert gas such as nitrogen gas. Further, it is preferable to perform solid-state polymerization while moving the pellets by an appropriate method such as a rolling method or a gas fluidized bed method so that no sticking occurs between the pellets. The pressure when solid-state polymerization is performed under reduced pressure is preferably 1 kPa or less.

Thus, the polyester obtained by solid phase polymerization is suitably used as a raw material for extrusion molding, particularly extrusion blow molding.

The polyester obtained as described above may contain other additives as long as the effects of the present invention are not impaired. For example, stabilizers such as antioxidants and ultraviolet absorbers, and antistatic agents. , Flame retardants, flame retardant aids, lubricants, plasticizers, inorganic fillers and the like. The content of these additives in the polyester is preferably 10% by mass or less, and more preferably 5% by mass or less.

The intrinsic viscosity of the polyester obtained by solid phase polymerization is preferably 0.9 dl / g or more. Thereby, the drawdown resistance at the time of carrying out extrusion blow molding of the said polyester further improves. The intrinsic viscosity is more preferably 1.0 dl / g or more, and still more preferably 1.05 dl / g or more. On the other hand, the intrinsic viscosity is preferably 1.5 dl / g or less, more preferably 1.4 l / g or less, and further preferably 1.3 l / g or less.

Various molded products can be obtained by melt-molding the obtained polyester. A molded product obtained by melt molding the polyester of the present invention has good color tone, high transparency, and high impact strength.

The intrinsic viscosity of the polyester subjected to melt molding is not particularly limited, but is 0.55 dl / g or more from the viewpoint of further improving the strength, impact resistance, melt moldability, and production stability of the obtained molded product. Is preferable, and 0.65 dl / g or more is more preferable. On the other hand, from the viewpoint of further improving melt moldability and productivity, the intrinsic viscosity is preferably 1.5 dl / g or less, more preferably 1.4 dl / g or less, and further preferably 1.3 dl / g or less. The total light transmittance of the molded product is preferably 90.3% or more, more preferably 90.5% or more, and further preferably 90.7% or more. By using the polyester, a molded article having excellent transparency can be obtained. The melt-molded product can be further subjected to secondary processing to obtain a molded product.

The molding method is not particularly limited, but an extrusion molding method is preferably employed. A molded product obtained by extrusion molding of the polyester is a preferred embodiment of the present invention. A film or sheet obtained by extruding the polyester is a more preferred embodiment of the present invention. A container formed by extrusion molding the polyester is also a more preferred embodiment of the present invention. The polyester is suitable for extrusion molding because of its high viscosity during melt molding. The temperature of the resin composition at the time of extrusion molding is preferably a temperature within the range of (polyester melting point + 10 ° C.) to (polyester melting point + 70 ° C.), and (polyester melting point + 10 ° C.) to (polyester melting point + 40). It is more preferable to set the temperature within the range of ° C. By extruding at a temperature relatively close to the melting point, drawdown can be suppressed.

For example, when a sheet or film is produced using the polyester by extrusion molding such as a T-die method or an inflation method, a highly transparent, high-quality sheet or film can be produced with high productivity. When secondary processing such as thermoforming is performed using the sheet or film thus obtained, when forming a deep-drawn molded product or a large molded product, The degree of crystallization of the molded product can be adjusted by adjusting the temperature of the mold. In addition, when the film is biaxially stretched, the crystallinity is improved, so that the strength of the stretched film can be improved. Such a biaxially stretched film, a sheet or a thermoformed product formed by thermoforming a film, particularly a container formed by thermoforming the sheet or film is a preferred embodiment of the present invention.

Of the extrusion molding, it is extrusion blow molding that is particularly suitable for using the polyester. The method of extrusion blow molding is not particularly limited, and can be performed in the same manner as conventionally known extrusion blow molding methods. For example, the polyester is melt-extruded to form a cylindrical parison, which is sandwiched between blow molds while the parison is in a softened state, and a gas such as air is blown to conform the parison to the mold cavity shape. It can be performed by a method of expanding into a predetermined hollow shape. When the polyester is used, a foreign matter in which the cobalt compound is aggregated is hardly generated, so that a molded product can be produced with a high yield.

Thus, a molded product obtained by extrusion blow molding of the polyester is also a preferred embodiment of the present invention. The molded article has good transparency, color tone, and impact resistance. Therefore, the molded product can be used for various applications. A container made of the molded product is a preferred embodiment of the molded product. Such a container is suitably used as a container for cosmetics or oil. Moreover, it can also be set as the molded article which has the laminated structure of the said polyester, another thermoplastic resin, etc.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.

(1) Composition of polyester The ratio of monomer units constituting the polyester was evaluated by ¹ H-NMR spectrum (apparatus: “JNM-GX-500 type” manufactured by JEOL Ltd., solvent: deuterated trifluoroacetic acid). .
(2) Intrinsic viscosity (IV)
The intrinsic viscosity of the polyester after the melt polymerization and the polyester after the solid phase polymerization were measured at a temperature of 30 ° C. using an equal mass mixture of phenol and 1,1,2,2-tetrachloroethane as a solvent.

(3) Particle size distribution In 500 g of an equal-mass mixture of phenol and 1,1,2,2-tetrachloroethane filtered through a 1 micron opening filter, 0.4 g of crystal pellets after solid-phase polymerization were added at 100 ° C. And then returned to room temperature and allowed to stand for 1 day. 50 mL (65 g) of the solution was passed through an in-liquid particle counter (Accurizer 780SIS manufactured by Particle Sizing Systems), and the number of particles contained in the pellet was measured by logarithmically dividing the range of 0.5 to 500 μm into 128. The distribution was determined. The measurement was performed 3 times and the average value was used. As an example of the particle size distribution in the polyester, the particle size distribution in the polyester obtained in Example 2 and Comparative Example 1 is shown in FIG. The number of particles having a particle diameter of 5 μm or more contained in 1 g of the pellets thus measured was used as an index of the dispersibility of the cobalt compound (M).
(4) Number of foreign matters in the film After drying the solid phase polymerization pellets at 120 ° C overnight, using a 20φ single screw extruder (cylinder temperature: 280-290 ° C, cooling roll temperature: 80 ° C), A polyester resin is extruded from a T-die onto a cooling roll to form a film having a thickness of 400 μm, and by a sheet defect detector (manufactured by Frontier System, ZD-CMAP), the number of foreign matters from 20 μm to less than 60 μm and 60 μm or more The number of foreign objects was measured respectively.

(5) Total light transmittance A sample (3 cm in length, 3 cm in width, 0.8 mm in thickness) was cut out from the body of the molded transparent bottle, and all light was transmitted using a haze meter (manufactured by Murakami Color Research Laboratory, HR-100). The rate was measured.

(6) IZOD impact strength After solid-phase polymerization pellets were dried at 120 ° C overnight, test pieces of length 80mm, width 10mm, and thickness 4mm were prepared by injection molding, and 10 samples were each notched. went. After the specimen was stored at 23 ° C. for 48 hours, the IZOD impact strength was measured at a lifting angle of 150 degrees using a hammer with a nominal pendulum energy of 0.5 J. The average value of 10 test results for each sample was defined as IZOD impact strength, and the impact resistance was evaluated.

(7) Bottle drop strength Water (water temperature 20 to 25 ° C.) is poured into a bottle immediately after molding so that the total weight is 263 g ± 0.5 g, and then passed through a vertically installed cylinder 10 cm in diameter. From a height of 125 cm, it was dropped alternately on a horizontal concrete surface and a concrete surface inclined 45 degrees. The number of cycles until the bottle was cracked or cracked (the bottle was dropped twice in total, once on the horizontal surface and once on the 45 ° slope) was measured. Up to 20 cycles were repeated. A drop test of five bottles was performed per composition, and the average value was defined as the bottle drop strength. It was used as an index of impact resistance of the molded product.

(8) Hue The hue (b value) of the polyester resin pellets was measured using a colorimetric color difference meter “ZE-2000” manufactured by Nippon Denshoku Industries Co., Ltd. according to ASTM-D2244 (color scale system 2).

Example 1
(1) Melt polycondensation 100 parts by mass of terephthalic acid (TA), 42.6 parts by mass of ethylene glycol (EG), 9.5 parts by mass of bisphenol A ethylene oxide 2-mol adduct (EOBPA), germanium dioxide (GeO ₂ ) 0123 parts by mass, 0.0123 parts by mass of phosphorous acid as the phosphorus compound (P), 0.0130 parts by mass of cobalt acetate tetrahydrate (0.0031 parts by mass in terms of cobalt element) as the cobalt compound (M), many A slurry composed of 0.0109 parts by mass of citric acid / monohydrate as a monovalent carboxylic acid (X) is prepared and heated to a temperature of 250 ° C. under pressure (gauge pressure of 0.25 MPa) to carry out an esterification reaction to form an oligomer. Manufactured. The obtained oligomer was transferred to a polycondensation tank and subjected to melt polycondensation at 260 ° C. to 280 ° C. for 80 minutes under 0.1 kPa to produce a polyester having an intrinsic viscosity of 0.7 dL / g. The obtained polyester was extruded into a strand form from a nozzle and cooled with water, and then cut into a cylindrical shape (diameter: about 2.5 mm, length: about 2.5 mm) to obtain an amorphous pellet of polyester.
(2) Precrystallization of amorphous pellets The obtained polyester amorphous pellets were put into a rolling vacuum solid-phase polymerization apparatus, and precrystallization was performed at 120 ° C for 2 hours under 0.1 kPa.

(3) Solid Phase Polymerization After the preliminary crystallization, the temperature was increased and solid phase polymerization was performed at 190 to 200 ° C. under 0.1 kPa for 40 hours to obtain crystal pellets. When the ratio of monomer components constituting the polyester was confirmed by ¹ H-NMR spectrum (apparatus: “JNM-GX-500 type” manufactured by JEOL Ltd., solvent: deuterated trifluoroacetic acid), TA unit: EG unit: EOBPA unit: diethylene glycol (DEG) unit = 100: 93: 5: 2 (molar ratio). The intrinsic viscosity of the obtained polyester resin was 1.2 dL / g, and the b value of the obtained polyester resin was −2.0. Further, the number of particles of 5 μm or more contained in 1 g of the obtained polyester was measured by an in-liquid particle counter and found to be 229 particles / g. When the number of foreign matters in the film was measured, the number of foreign matters of 20 μm or more and less than 60 μm was 190 / m ² , and the number of foreign matters of 60 μm or more was 10 / m ² . The IZOD impact strength was 4.5 kJ / m ² .

(4) Production of bottle After the obtained pellets were dried at 120 ° C. for 24 hours with a dehumidifying dryer, a transparent bottle having a volume of 220 mL (“MSE-40E type” manufactured by Tahara Co., Ltd.) was used. 27g) was molded. At this time, the cylinder temperature was graded from 280 ° C. to 240 ° C., the die temperature was 240 to 250 ° C., the molding cycle was 10 seconds, the screw rotation speed was 24 rpm, and the mold temperature was 20 ° C. When the drop strength of the obtained bottle was examined, the bottle drop strength was 14. The total light transmittance of the molded product was 91.0%.

Example 2
A polyester was produced and evaluated in the same manner as in Example 1 except that the amount of citric acid / monohydrate added was changed to 0.0154 parts by mass. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 3
A polyester resin was produced and evaluated in the same manner as in Example 1 except that the amount of citric acid / monohydrate added was changed to 0.0861 parts by mass. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 4
A polyester resin was produced and evaluated in the same manner as in Example 1 except that the amount of citric acid / monohydrate added was changed to 0.0006 parts by mass. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 5
A polyester resin was produced and evaluated in the same manner as in Example 2 except that 0.0144 parts by mass of phosphoric acid was added instead of phosphorous acid. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 6
The raw material slurry was 86 parts by mass of terephthalic acid, 14 parts by mass of isophthalic acid (IPA), 44.8 parts by mass of ethylene glycol, 0.0123 parts by mass of germanium dioxide, 0.0123 parts by mass of phosphorous acid, cobalt acetate / tetrahydrous. Example 1 was repeated except that the slurry was changed to 0.0130 parts by mass, 0.0154 parts by mass of citric acid / monohydrate, and the solid phase polymerization temperature was changed to 180 to 190 ° C. To produce a polyester. The polyester obtained in the same manner as in Example 1 was evaluated except that the molding cycle during bottle molding was changed to 7 seconds. The monomer component constituting the polyester was TA unit: IPA unit: EG unit: DEG unit = 86: 14: 98: 2 (molar ratio). The results are summarized in Table 1.

Example 7
The raw material slurry was made of 100 parts by mass of terephthalic acid, 12.2 parts by mass of 1,4-cyclohexanedimethanol (CHDM), 38.5 parts by mass of ethylene glycol, 0.0123 parts by mass of germanium dioxide (GeO ₂ ), phosphorous acid The slurry was changed to 0.0123 parts by mass, cobalt acetate tetrahydrate 0.0130 parts by mass (0.0031 parts by mass in terms of cobalt element), citric acid monohydrate 0.0154 parts by mass, A polyester was produced and evaluated in the same manner as in Example 1 except that the solid-state polymerization temperature was changed to 180 to 190 ° C. The monomer component constituting the polyester was TA unit: EG unit: CHDM unit: DEG unit = 100: 84: 14: 2 (molar ratio). The results are summarized in Table 1.

Example 8
A polyester was produced and evaluated in the same manner as in Example 1 except that 0.0086 parts by mass of succinic acid was added instead of citric acid / monohydrate. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 9
A polyester was produced and evaluated in the same manner as in Example 1 except that 0.0065 parts by mass of tartaric acid was added instead of the addition amount of citric acid / monohydrate. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 10
Except that the addition amount of cobalt acetate tetrahydrate was changed to 0.0026 parts by mass (0.0006 parts by mass in terms of cobalt element), and the addition amount of phosphorous acid was changed to 0.0062 parts by mass. Polyester was produced and evaluated in the same manner as in 2. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 11
Except that the addition amount of cobalt acetate tetrahydrate was changed to 0.0615 parts by mass (0.0146 parts by mass in terms of cobalt element), and the addition amount of phosphorous acid was changed to 0.0246 parts by mass. Polyester was produced and evaluated in the same manner as in 2. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 12
A polyester was produced and evaluated in the same manner as in Example 2 except that the amount of phosphorous acid added was changed to 0.0062 parts by mass. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Example 13
A polyester was produced and evaluated in the same manner as in Example 2 except that 0.0615 parts by mass of dibutyl phosphate was added instead of phosphorous acid. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 1.

Comparative Example 1
A polyester was produced and evaluated in the same manner as in Example 1 except that citric acid monohydrate was not added. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 2
A polyester was produced and evaluated in the same manner as in Example 1 except that the amount of citric acid / monohydrate added was changed to 0.00006 parts by mass. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 3
A polyester was produced and evaluated in the same manner as in Example 1 except that the amount of citric acid / monohydrate added was changed to 0.369 parts by mass and the solid phase polymerization time was 100 hours. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 4
A polyester was produced and evaluated in the same manner as in Example 2 except that phosphorous acid was not added. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 5
A polyester was produced and evaluated in the same manner as in Example 6 except that citric acid / monohydrate was not added. The monomer component constituting the polyester was TA unit: IPA unit: EG unit: DEG unit = 86: 14: 98: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 6
A polyester was produced and evaluated in the same manner as in Example 7 except that citric acid / monohydrate was not added. The monomer component constituting the polyester was TA unit: EG unit: CHDM unit: DEG unit = 100: 84: 14: 2 (molar ratio). The results are summarized in Table 2.

Comparative Example 7
A polyester was produced and evaluated in the same manner as in Example 1 except that 0.0065 parts by mass of lactic acid was added instead of citric acid / monohydrate. The monomer component constituting the polyester was TA unit: EG unit: EOBPA unit: DEG unit = 100: 93: 5: 2 (molar ratio). The results are summarized in Table 2.

Claims

A polyester containing 50 mol% or more of terephthalic acid units with respect to the total of dicarboxylic acid units and 50 mol% or more of ethylene glycol units with respect to the total of diol units,
The polyester has at least one phosphorus compound (P) selected from the group consisting of a cobalt compound (M), phosphoric acid, phosphorous acid, organic phosphonic acid and esters thereof, and an α, β-dicarboxylic acid unit. In the presence of the polyvalent carboxylic acid (X), a dicarboxylic acid and a diol are polycondensed,
The addition amount of the cobalt compound (M) with respect to 100 parts by mass of the dicarboxylic acid is 0.0005 to 0.05 parts by mass in terms of cobalt element,
The molar ratio (P / M) of the phosphorus atom in the phosphorus compound (P) to the cobalt atom in the cobalt compound (M) is 0.01 to 10, and the polyvalent carboxylic to the cobalt atom in the cobalt compound (M) Polyester having a molar ratio (X / M) of acid (X) of 0.01 to 10.
The polyester according to claim 1, wherein the phosphorus compound (P) is at least one of phosphorous acid and phosphoric acid.
The polyester according to claim 1 or 2, wherein the polyvalent carboxylic acid (X) has a hydroxyl group.
The polyester according to any one of claims 1 to 3, wherein the polyvalent carboxylic acid (X) is a tricarboxylic acid.
The polyester according to any one of claims 1 to 4, wherein the polyvalent carboxylic acid (X) is citric acid.
The polyester according to any one of claims 1 to 5, further comprising 0.1 to 20 mol% of a unit derived from a bisphenol A ethylene oxide adduct based on a total of the diol units.
The polyester according to any one of claims 1 to 6, further comprising a cyclohexanedimethanol unit in an amount of 0.1 to 45 mol% based on the total of the diol units.
The polyester according to any one of claims 1 to 7, further comprising 0.1 to 20 mol% of isophthalic acid units based on the total of the dicarboxylic acid units.
A molded product obtained by extruding the polyester according to any one of claims 1 to 8.
A film or sheet comprising the molded product according to claim 9.
A thermoformed product obtained by thermoforming the film or sheet according to claim 10.
A container comprising the molded product according to claim 9.
The method for producing a polyester according to any one of claims 1 to 8, wherein the dicarboxylic acid and the diol are polycondensed in the presence of the cobalt compound (M), the phosphorus compound (P) and the polyvalent carboxylic acid (X).