JP2007126680A - Process for producing polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing, at good productivity, a polyester resin with an acetoaldehyde content being reduced thereby giving no effect on the taste, flavor and the like of the content in a bottle formed of the resin. <P>SOLUTION: The production process of the polyester resin comprises esterifying a dicarboxylic acid component containing terephthalic acid or an ester thereof as a main ingredient and a diol component containing ethylene glycol as a main ingredient to produce a polyester, wherein polycondensation is conducted in the presence of (1) at least one selected from titanium elements belonging to the group 4A in the periodic table (0.02 to 0.2 mol), (2) at least one selected from elements belonging to the groups 1A and 2A in the periodic table, manganese, iron and cobalt (0.04 to 0.6 mol) and (3) a phosphor compound (0.02 to 0.4 mol). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a polyester resin that is suitably used for molding bottles of food and drink, etc., by eliminating the influence on the flavor, aroma, etc. of the contents by being able to reduce the acetaldehyde content as a molded body, In particular, the present invention relates to a production method with improved polycondensation properties.

  Conventionally, polyester resins such as polyethylene terephthalate resins are excellent in mechanical strength, chemical stability, gas barrier properties, fragrance retention, hygiene, etc., and are relatively inexpensive and lightweight. In particular, bottles imparted with high gas barrier properties and the like by stretching and heat-setting have been rapidly expanded. These bottles are produced, for example, by injection molding a bottomed tubular preform, reheating and softening the preform, followed by stretch blow molding. At that time, the blow mold is heated. In this way, the bottle is heat-set, and the oriented crystals of the molecular chains are stretched by stretching to develop high gas barrier properties and the like.

  However, the polyethylene terephthalate resin used in the field of packaging containers for these foods and beverages is a polyethylene terephthalate resin using a polycondensation catalyst as an antimony compound frequently used for general-purpose bottles. There are concerns about problems such as elution from the container at a high temperature and a slight shift to the contents of food and drink. In addition, in the polyethylene terephthalate resin using a germanium compound frequently used for heat-resistant bottles as a polycondensation catalyst, germanium is used. Since the compounds are expensive, economic disadvantages are unavoidable, and the emergence of polycondensation catalysts instead of them is strongly desired.

  On the other hand, many polyethylene terephthalate resins using a titanium compound as a polycondensation catalyst have been proposed, but a large amount of acetaldehyde and cyclic trimers are by-produced during polycondensation and melt molding, and used as bottles. However, for example, JP-A-8-73581 discloses a titanium compound, a cobalt compound, and phosphoric acid, phosphorous acid and / or phosphone. A method for producing a polyethylene terephthalate resin excellent in achromatic transparency by using a limited amount of a complexing agent comprising an acid or a derivative thereof is disclosed. However, according to the study by the present inventors, it has been found that the polyethylene terephthalate resin obtained by this method cannot provide a solution to the above-described problems of deterioration in flavor, aroma and the like.

Furthermore, European Patent Publication No. 1013692 discloses a polycondensation catalyst by using a specific amount of a titanium atom and a metal atom such as magnesium so as to have a specific quantitative ratio. JP-A-2000-339919, which is an application by the present applicant, discloses that a by-product of acetaldehyde at the time of molding can be suppressed, and includes (1) a titanium compound and (2) 1A of the periodic table. In the polycondensation in the presence of at least one element selected from the group consisting of group III metal elements, group 2A elements of the periodic table, manganese, and (3) phosphorus compounds, (1), A method for producing a polyester resin in which the order of addition of each compound of (2) and (3) to the reaction system is (3), then (2), and then (1) is disclosed. However, according to the study by the present inventors, these methods are certainly effective for reducing by-products, but the disclosed method may have room for improvement in terms of polycondensability. found.
JP-A-8-73581 European Patent Publication No. 1013692 JP 2000-339919 A

  The present invention has been made in view of the above-described prior art, and can reduce the content of acetaldehyde as a molded body, thereby eliminating the influence on the flavor, aroma, etc. of the contents when used in a bottle or the like It is an object of the present invention to provide a method for producing a resin with improved polycondensability and improved productivity.

  The present invention has been made to achieve the above object, that is, the present invention is a dicarboxylic acid component mainly composed of terephthalic acid or an ester-forming derivative thereof, and a diol component mainly composed of ethylene glycol. Through an esterification reaction or transesterification reaction, (1) a compound of at least one element selected from the group consisting of titanium group elements of group 4A of the periodic table, and (2) metal of group 1A of the periodic table A polyester resin is obtained by polycondensation in the presence of an element, a group 2A element of the periodic table, a compound of at least one element selected from the group consisting of manganese, iron, and cobalt, and (3) a phosphorus compound. In the production, the amount of each compound of (1), (2), and (3) is 0.02 to 0 as the total amount (T) of atoms of the compound of (1) per ton of theoretical yield of the polyester resin. .2 moles of (2) Polyester having an amount of 0.04 to 0.6 mol as the total amount of atoms (M) of the product and 0.02 to 0.4 mol as the total amount of atoms (P) of the compound (3) The gist of the resin production method.

  According to the present invention, it is possible to reduce the content of acetaldehyde as a molded product, thereby producing a polyester resin that has no influence on the flavor, aroma, etc. of the contents when used in bottles, etc., with improved polycondensation properties It is possible to provide a method for manufacturing with improved properties.

  The method for producing a polyester resin according to the present invention comprises a dicarboxylic acid component having terephthalic acid or an ester-forming derivative thereof as a main component and a diol component having ethylene glycol as a main component through an esterification reaction or a transesterification reaction. It is produced by condensation.

  Here, examples of the ester-forming derivative of terephthalic acid include alkyl esters having about 1 to 4 carbon atoms and halides. Examples of dicarboxylic acid components other than terephthalic acid or its ester-forming derivatives include, for example, phthalic acid, isophthalic acid, dibromoisophthalic acid, sodium sulfoisophthalic acid, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, Fragrances such as 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenyl ketone dicarboxylic acid, 4,4′-diphenoxyethane dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, etc. Alicyclic dicarboxylic acids such as aromatic dicarboxylic acids, hexahydroterephthalic acid, hexahydroisophthalic acid, and succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodeca Aliphatic dicar such as dicarboxylic acid Phosphate, as well as the alkyl esters having about 1 to 4 carbon atoms, and halides, and the like. Among them, in the present invention, isophthalic acid or an ester-forming derivative thereof is preferable.

  Examples of diol components other than ethylene glycol include diethylene glycol by-produced in the reaction system. Examples of other diol components include trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and octamethylene. Glycol, decamethylene glycol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, polyethylene glycol, polytetramethylene ether glycol and other aliphatic diols, 1,2-cyclohexanediol, 1,4- Cycloaliphatic diols such as cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,5-norbornane dimethylol, and xylylene glycol, 4,4 -Dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β- Examples thereof include aromatic diols such as hydroxyethoxyphenyl) sulfonic acid, and ethylene oxide adducts or propylene oxide adducts of 2,2-bis (4′-hydroxyphenyl) propane.

  Furthermore, as a copolymer component other than the diol component and the dicarboxylic acid component, for example, glycolic acid, p-hydroxybenzoic acid, hydroxycarboxylic acid such as p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acid, and stearyl alcohol, Monofunctional components such as heneicosanol, octacosanol, benzyl alcohol, stearic acid, behenic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetetracarboxylic acid Trifunctional or higher functional components such as gallic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sugar ester, and the like may be used.

  The method for producing a polyester resin of the present invention comprises, during polycondensation, (1) a compound of at least one element selected from the group consisting of titanium group elements of Group 4A of the periodic table, and (2) group 1A of periodic table. The amount of each compound of a metal element, a group 2A element of the periodic table, a compound of at least one element selected from the group consisting of manganese, iron, and cobalt, and (3) a phosphorus compound is calculated according to the theory of polyester resin. Per ton of yield, 0.02 to 0.2 mol as total amount of atoms (T) of compound (1), 0.04 to 0.6 mol as total amount (M) of atoms of compound (2), and The total amount of atoms (P) in the compound (3) is present in an amount of 0.02 to 0.4 mol.

  Here, (1) the compounds of Group 4A titanium group of the periodic table, that is, titanium, zirconium, hafnium, oxides, hydroxides, alkoxides, acetates, carbonates, oxalates of these elements, And halides. Of these elemental compounds, titanium compounds are preferable, and specific examples of the titanium compounds include tetra-n-propyl titanate, tetra-i-propyl titanate, tetra-n-butyl titanate, and tetra-n. -Titanium alkoxide such as butyl titanate tetramer, tetra-t-butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, tetrabenzyl titanate, titanium oxide obtained by hydrolysis of titanium alkoxide, titanium alkoxide and silicon alkoxide or zirconium alkoxide Titanium-silicon or zirconium composite oxide obtained by hydrolysis of the mixture, titanium acetate, titanium oxalate, potassium titanium oxalate, sodium titanium oxalate, potassium titanate, sodium titanate , Titanium titanate-aluminum hydroxide mixture, titanium chloride, titanium chloride-aluminum chloride mixture, titanium bromide, titanium fluoride, potassium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, six Examples thereof include ammonium fluorinated titanate and titanium acetylacetonate. Among them, titanium alkoxides such as tetra-n-propyl titanate, tetra-i-propyl titanate, and tetra-n-butyl titanate, titanium oxalate, and potassium potassium oxalate are included. Tetra-n-butyl titanate is preferred and particularly preferred.

  In addition, (2) a compound of at least one element selected from the group consisting of Group 1A metal elements of the periodic table, Group 2A elements of the periodic table, manganese, iron, and cobalt includes, for example, lithium, sodium, Potassium, magnesium, calcium, manganese, iron, cobalt, etc., oxides, hydroxides, alkoxides, acetates, carbonates, oxalates, halides, etc., specifically, for example, lithium acetate, sodium acetate, Potassium acetate, magnesium oxide, magnesium hydroxide, magnesium alkoxide, magnesium acetate, magnesium carbonate, calcium oxide, calcium hydroxide, calcium acetate, calcium carbonate, manganese oxide, manganese hydroxide, manganese acetate, ferric acetate, cobalt formate, Cobalt acetate, cobalt oxalate, cobalt carbonate, cobalt bromide, co Belt acetylacetonate, and the like. Among these, a magnesium compound is preferable, and magnesium acetate is particularly preferable.

  (3) Specific examples of phosphorus compounds include orthophosphoric acid, polyphosphoric acid, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate. , Trivalent (triethylene glycol) phosphate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, pentavalent phosphorus such as phosphate ester such as triethylene glycol acid phosphate Compounds, and phosphorous acid, hypophosphorous acid, and trimethyl phosphite, diethyl phosphite, triethyl phosphite, trisdodecyl phosphite, Examples thereof include phosphorous esters such as lisnonyl decyl phosphite, ethyl diethyl phosphonoacetate and triphenyl phosphite, and trivalent phosphorus compounds such as metal salts such as lithium, sodium and potassium. Phosphoric esters of the compounds are preferred, and trimethyl phosphate and ethyl acid phosphate are particularly preferred.

  In the present invention, (1) a compound of at least one element selected from the group consisting of titanium group elements of Group 4A of the periodic table is used in a total amount (T) of those atoms of 0.02 to 0.2 mol. It is essential to be present in an amount that makes the content of, and is preferably an amount that makes the content of 0.04 to 0.15 mol. When the total amount (T) of these atoms is less than the above range, both melt polycondensation and solid phase polycondensation described later are decreased. On the other hand, when the total amount exceeds the above range, the content of acetaldehyde as a molded product of the obtained resin is reduced. Reduction becomes difficult.

  Further, (2) a compound of at least one element selected from the group consisting of Group 1A metal elements of the periodic table, Group 2A elements of the periodic table, manganese, iron, and cobalt is added to the total amount of atoms (M ), It is essential to be present in an amount of 0.04 to 0.6 mol, and preferably 0.05 to 0.4 mol. It is more preferable to set the amount to be a molar content. If the total amount (M) of these atoms is less than the above range, both the melt polycondensation property and solid phase polycondensation property described later will be reduced, while if exceeding the above range, the solid phase polycondensation property described later will be reduced.

  Further, it is essential that the (3) phosphorus compound is present in an amount of 0.02 to 0.4 mol as the total amount (P) of atoms per ton of theoretical yield of the polyester resin. It is preferable to set it as the quantity used as content of 1-0.3 mol. If the total amount (P) of these atoms is less than the above range, it is difficult to reduce the content of acetaldehyde in the resulting resin. On the other hand, if it exceeds the above range, the solid-phase polycondensability described later will be reduced.

  And (1) a compound of at least one element selected from the group consisting of Group 4A titanium group elements of the periodic table, (2) Group 1A metal element of the periodic table, Group 2A element of the periodic table, The amount of each compound of the compound of at least one element selected from the group consisting of manganese, iron, and cobalt, and (3) the phosphorus compound is the total amount (T) of atoms of the compound of (1), (2 The above-mentioned range is satisfied as the total amount of atoms (M) of the compound of (1) and the total amount of atoms (P) of the compound of (3). The ratio (P / T) of the total amount (P) of atoms of the compound of (1) is preferably 0.1 to 10, more preferably 1 to 7, and particularly preferably 2 to 5. If this ratio (P / T) is less than the above range, the resulting resin tends to be yellowish and the color tone tends to deteriorate. On the other hand, if it exceeds the above range, both the melt polycondensation property and the solid phase polycondensation property described later are reduced. Tend to.

  The ratio (M / T) of the total amount (M) of atoms of the compound (2) to the total amount (T) of atoms of the compound (1) is preferably 0.1-10, 7 is more preferable, and 3 to 5 is particularly preferable. When this ratio (M / T) is less than the above range, both melt polycondensation and solid-phase polycondensation described later tend to decrease, and it is difficult to reduce the acetaldehyde content as a molded product of the obtained resin. On the other hand, if the range is exceeded, the solid-phase polycondensation property described later tends to decrease.

  In the present invention, at the time of polycondensation, a metal compound other than the above-mentioned compounds may further be present within a range not impairing the effects of the present invention. In this case, the metal compound includes aluminum, chromium, nickel, copper , Zinc, germanium, molybdenum, silver, tin, lanthanum, cerium, tungsten, gold and other oxides, hydroxides, alkoxides, carbonates, phosphates, carboxylates, halides and the like. In addition, it is preferable that each said compound and the said other compound are soluble in diols, such as ethylene glycol, and water.

  The method for producing a polyester resin of the present invention comprises an esterification reaction or a transesterification reaction between a dicarboxylic acid component mainly composed of the terephthalic acid or an ester-forming derivative thereof and a diol component mainly composed of ethylene glycol. (1) a compound of at least one element selected from the group consisting of Group 4A titanium group elements of the periodic table, (2) group 1A metal element of the periodic table, group 2A element of the periodic table, manganese In the presence of at least one elemental compound selected from the group consisting of iron, cobalt, and (3) a phosphorus compound. Basically, conventional production of polyester resins Depending on the method. That is, the dicarboxylic acid component mainly composed of the terephthalic acid or its ester-forming derivative and the diol component mainly composed of ethylene glycol are put into a slurry preparation tank together with a copolymer component used as necessary. It is obtained after mixing with stirring to form a raw material slurry, causing an esterification reaction in an esterification reaction tank at normal pressure to under pressure, under heating, or by performing an ester exchange reaction in the presence of a transesterification catalyst. The polyester low molecular weight product as an esterification reaction product or transesterification reaction product is transferred to a polycondensation tank, and in the presence of the compound, melt polycondensation is carried out under heating from normal pressure to gradually reduced pressure. Let

  In the case of performing an ester exchange reaction using an ester-forming derivative of terephthalic acid as a dicarboxylic acid component, it is usually necessary to use an ester exchange catalyst such as a titanium compound, a magnesium compound, a calcium compound, a manganese compound, or a zinc compound. Since it is necessary to use a large amount of the transesterification catalyst, in the present invention, a method of producing it through an esterification reaction using terephthalic acid as a dicarboxylic acid component is preferable.

  Here, in the case of the esterification reaction, the preparation of the raw material slurry includes a carboxylic acid component containing terephthalic acid as a main component, a diol component containing ethylene glycol as a main component, and a copolymer component used as necessary. The molar ratio of the diol component to the dicarboxylic acid component is preferably 1.02 to 2.0, more preferably 1.03 to 1.7.

  In addition, the esterification reaction can be carried out by using a single esterification reaction tank or a multistage reaction apparatus in which a plurality of esterification reaction tanks are connected in series under reflux of ethylene glycol and excess water and water produced by the reaction. While removing ethylene glycol out of the system, the esterification rate (the ratio of the esterified by reacting with the diol component out of the total carboxyl groups of the raw dicarboxylic acid component) is usually 90% or more, preferably 93% or more Done until it reaches. Moreover, it is preferable that the number average molecular weight of the polyester low molecular weight body as an esterification reaction product obtained is 500-5,000.

As reaction conditions in the esterification reaction, in the case of a single esterification reaction tank, the temperature is usually about 240 to 280 ° C., and the relative pressure to atmospheric pressure is usually about 0 to 400 kPa (0 to 4 kg / cm ² G). The reaction time is about 1 to 10 hours under stirring. In the case of a plurality of esterification reaction tanks, the reaction temperature in the first stage esterification reaction tank is usually 240 to 270 ° C., preferably 245 to 265 ° C., and the relative pressure to atmospheric pressure is usually 5 to 300 kPa. (0.05 to 3 kg / cm ² G), preferably 10 to 200 kPa (0.1 to ² kg / cm ² G), and the reaction temperature in the final stage is usually 250 to 280 ° C., preferably 255 to 275 ° C., The relative pressure with respect to atmospheric pressure is usually 0 to 150 kPa (0 to 1.5 kg / cm ² G), preferably 0 to 130 kPa (0 to 1.3 kg / cm ² G). In addition, it is preferable to make the increase amount equal in the esterification rate in each stage.

  In the esterification reaction, for example, tertiary amines such as triethylamine, tri-n-butylamine, and benzyldimethylamine, hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, and trimethylbenzylammonium hydroxide are used. By adding a small amount of a basic compound such as quaternary ammonium, lithium carbonate, sodium carbonate, potassium carbonate, or sodium acetate, by-production of diethylene glycol from ethylene glycol can be suppressed.

  The melt polycondensation is performed by connecting a single melt polycondensation tank or a plurality of melt polycondensation tanks in series, for example, a fully mixed reactor in which the first stage is equipped with a stirring blade, The stage and the third stage are carried out by distilling the produced ethylene glycol out of the system under reduced pressure by using a multistage reactor comprising a horizontal plug flow reactor equipped with a stirring blade.

  As reaction conditions in the melt polycondensation, in the case of a single polycondensation tank, the temperature is usually about 250 to 290 ° C. The pressure is gradually reduced from normal pressure, and finally the absolute pressure is usually 1.3 to 0.013 kPa. (10 to 0.1 Torr) and a reaction time of about 1 to 20 hours with stirring. In the case of a plurality of polycondensation tanks, the reaction temperature in the first stage polycondensation tank is usually 250 to 290 ° C., preferably 260 to 280 ° C., and the absolute pressure is usually 65 to 1.3 kPa (500 to 10 Torr), preferably 26 to 2 kPa (200 to 15 Torr), the reaction temperature in the final stage is usually 265 to 300 ° C., preferably 270 to 295 ° C., and the absolute pressure is usually 1.3 to 0.013 kPa (10 to 10 Torr). 0.1 Torr), preferably 0.65 to 0.065 kPa (5 to 0.5 Torr). As reaction conditions in the intermediate stage, those intermediate conditions are selected. For example, in a three-stage reactor, the reaction temperature in the second stage is usually 265 to 295 ° C., preferably 270 to 285 ° C., and the absolute pressure is Usually, it is 6.5 to 0.13 kPa (50 to 1 Torr), preferably 4 to 0.26 kPa (30 to 2 Torr).

  Further, at the time of polycondensation, (1) a compound of at least one element selected from the group consisting of titanium group elements of group 1A of the periodic table, (2) metal element of group 1A of the periodic table, periodic table The addition timing of the compound of at least one element selected from the group consisting of Group 2A elements, manganese, iron and cobalt, and (3) phosphorus compound to the reaction system is the slurry preparation step, esterification reaction or It may be any stage of the transesterification reaction process, or an early stage of the melt polycondensation process, but the compounds of (1) and (2) are used in the esterification reaction or transesterification reaction process, or It is preferably added at the stage of transfer to the melt polycondensation process, and is preferably added when the esterification rate of the esterification reaction or transesterification reaction product is 90% or more, and (1) After the compound (2) Preferably added. The compound (3) is preferably added at a stage where the esterification rate of the esterification reaction or transesterification reaction product is less than 90%.

  As a specific addition process of each compound, for example, the compound of (1) is produced in the esterification reaction tank in the final stage in the multistage reaction apparatus or the esterification reaction or transesterification reaction in the transfer stage to the melt polycondensation process. The compound (2) is preferably added to the final stage esterification reactor in the multistage reactor. The compound (3) is preferably added to the slurry preparation tank or the first stage esterification reaction tank, and particularly preferably added to the slurry preparation tank. That is, in the present invention, the order of adding the compounds (1), (2), and (3) to the reaction system is preferably (3), then (2), and then (3).

  By adding the addition timing and addition order of each compound of (1), (2), and (3) to the reaction system as described above, the thermal stability of the resin is improved, and acetaldehyde at the time of melt molding, etc. The by-product of diethylene glycol in the reaction system that causes the by-product of is also suppressed, and the effect of improving the melt polycondensation property and the solid-phase polycondensation property can be effectively exhibited.

  In addition, the addition of the compounds (1), (2), and (3) to the reaction system during the polycondensation is preferably performed as a solution of alcohol such as ethylene glycol or water. In the case of using the titanium compound as the compound of 1), the ethylene glycol solution has a titanium atom concentration of 0.01 to 0.3% by weight and a water concentration of 0.1 to 1% by weight. This is preferable from the viewpoint of improving the dispersibility of the titanium compound in the system and the resulting melt polycondensation property and solid phase polycondensation property.

  The reaction time in the melt polycondensation is usually 3.5 hours or less. When the reaction time exceeds this, it tends to be difficult to reduce the acetaldehyde content in the resulting resin and the amount of acetaldehyde by-product during melt molding.

  The polyester resin obtained by the melt polycondensation has an intrinsic viscosity ([η1]) of 0.35 to 0 as a value measured at 30 ° C. in a mixed solvent solution of phenol / tetrachloroethane (weight ratio 1/1). It is preferably .75 dl / g, more preferably 0.50 to 0.60 dl / g. If the intrinsic viscosity ([η1]) is less than the above range, the later-described extractability from the polycondensation tank tends to be poor, whereas if it exceeds the above range, it is difficult to reduce the acetaldehyde content in the resulting resin. It becomes a trend. The melt polycondensation rate (V1) as a value obtained by dividing the intrinsic viscosity ([η1]) of the obtained polyester resin by the reaction time is preferably 0.15 dl / g / hr or more.

  The resin obtained by the melt polycondensation is usually extracted in a strand form from an outlet provided at the bottom of the polycondensation tank, and is cooled with water or after water cooling, and then cut with a cutter to form pellets, chips, etc. Further, the granular material after the melt polycondensation is usually 100 kPa (1 kg / cm2G) or less as a relative pressure with respect to the atmospheric pressure in an inert gas atmosphere such as nitrogen, carbon dioxide, and argon. Preferably under pressure of 20 kPa (0.2 kg / cm 2 G) or less, usually for about 5 to 30 hours, or as absolute pressure, usually 6.5 to 0.013 kPa (50 to 0.1 Torr), preferably 1.3 to It is heated at a temperature of usually about 190 to 230 ° C., preferably 195 to 225 ° C. under a reduced pressure of 0.065 kPa (10 to 0.5 Torr) for about 1 to 20 hours. It makes preferable to solid phase polycondensation. By this solid phase polycondensation, the degree of polymerization can be further increased, and the amount of by-products such as acetaldehyde can be reduced.

  At that time, prior to solid phase polycondensation, it is usually 120 to 200 ° C., preferably 130 to 190 ° C. for 1 minute to 4 in an inert gas atmosphere, or in a water vapor atmosphere or a water vapor-containing inert gas atmosphere. It is preferable to crystallize the resin granule surface by heating for about an hour.

  The polyester resin obtained by the solid phase polycondensation has an intrinsic viscosity ([η2]) of 0.70 as a value measured at 30 ° C. in a mixed solvent solution of phenol / tetrachloroethane (weight ratio 1/1). It is preferably 0.90 dl / g, more preferably 0.71 to 0.85 dl / g, and particularly preferably 0.72 to 0.80 dl / g. If the intrinsic viscosity ([η2]) is less than the above range, mechanical strength as a molded article such as a bottle tends to be insufficient. On the other hand, if it exceeds the above range, by-product such as acetaldehyde during melt molding may be suppressed. It becomes a difficult tendency. Also, the difference ([η2]-[η1]) between the intrinsic viscosity ([η2]) of the obtained solid phase polycondensation resin and the intrinsic viscosity ([η1]) of the melt polycondensation resin is divided by the reaction time. The solid phase polycondensation rate (V2) as a measured value is preferably 0.008 to 0.015 dl / g / hr. The ratio of the solid phase polycondensation rate to the melt polycondensation rate (V2 / V1) is preferably in the range of 0.04 to 0.07, and is preferably in the range of 0.05 to 0.07. Is more preferable.

  Furthermore, the resin obtained by melt polycondensation or solid phase polycondensation as described above is usually treated with water treated for 10 minutes or more in warm water of 40 ° C. or higher, or in water vapor or water vapor-containing gas of 60 ° C. or higher. Treatment such as steam treatment for 30 minutes or more, treatment with an organic solvent, treatment with an acidic aqueous solution such as various mineral acids, organic acids, phosphoric acid, or Group 1A metal, Group 2A metal, The catalyst used for polycondensation can be deactivated by treatment with an alkaline aqueous solution such as amine or an organic solvent solution.

  The polyester resin obtained by the production method of the present invention is a polycondensate in which the terephthalic acid component accounts for 97 mol% or more of the total dicarboxylic acid component, and the dicarboxylic acid component other than terephthalic acid is 3 mol% or less of the total dicarboxylic acid component. It is more preferable that isophthalic acid is a polycondensate occupying 0.1 to 3 mol% of the total dicarboxylic acid component, and isophthalic acid is a polycondensate occupying 1 to 2 mol%. Particularly preferred. When isophthalic acid is within this range, the solid-phase polycondensation rate tends to be high, and the acetaldehyde content as a molded product of the resulting resin tends to be easily reduced. The ethylene glycol component accounts for 97 mol% or more of the total diol component, and the diol component other than ethylene glycol is preferably a polycondensate of 3 mol% or less of the total diol component. A polycondensate of 3 mol% is particularly preferred. If diethylene glycol exceeds this range, problems such as a decrease in gas barrier properties when the resulting resin is formed into a molded article and difficulty in reducing the acetaldehyde content tend to occur. Further, copolymer components such as dicarboxylic acid components and diol components other than terephthalic acid and ethylene glycol are preferably 6 mol% or less, and 1.5 to 4.5 mol% with respect to the total dicarboxylic acid components. Is more preferable.

  As described above, the polyester resin obtained by the production method of the present invention comprises (1) a compound of at least one element selected from the group consisting of titanium group elements of Group 4A of the periodic table, and (2) periodic table. Polycondensation in the presence of a group 1A metal element, a group 2A element of the periodic table, a compound of at least one element selected from the group consisting of manganese, iron and cobalt, and (3) a phosphorus compound. As a result, each compound of (1), (2), and (3) is converted to 0.02 as the total amount (T) of atoms of the compound of (1) per ton of theoretical yield of the polyester resin. -0.2 mol, 0.04 to 0.6 mol as the total amount of atoms (M) of the compound (2), and 0.02 to 0.4 as the total amount (P) of atoms of the compound (3) Each of the compounds contained in the compound (3) with respect to the total amount (T) of atoms of the compound (1) It is also included that the ratio (P / T) of the total amount (P) of the child is 0.1 to 10 of the atoms of the compound (2) with respect to the total amount (T) of the atoms of the compound (1). The total amount (M) is preferably contained in an amount such that the ratio (M / T) is 0.1-10.

  In addition, the polyester resin obtained by the production method of the present invention preferably has an acetaldehyde content of 5.0 ppm or less, and more preferably 3.0 ppm or less. Further, the acetaldehyde content in the molded article after injection molding at 280 ° C. is preferably 20 ppm or less, more preferably 18 ppm or less, and particularly preferably 15 ppm or less. When the acetaldehyde content exceeds the above range, it tends to be difficult to eliminate the influence on the flavor, aroma and the like of the contents as a molded article such as a bottle.

  Further, the polyester resin obtained by the production method of the present invention preferably has a cyclic trimer content of 0.60% by weight or less, and more preferably 0.50% by weight or less. If the cyclic trimer content exceeds the above range, mold contamination is likely to occur during molding of bottles and the like, and the transparency of the molded product tends to deteriorate.

  As the color tone, the color coordinate b value of Hunter's color difference formula in the Lab color system described in Reference 1 of JIS Z8730 is preferably 4 or less, and more preferably 3 or less. When the b value exceeds the above range, the color tone of a molded body such as a bottle tends to be yellowish. In order to set the color coordinate b value within the above range, a so-called toning agent may be added. Examples of the toning agent include Solvent Blue 104, Solvent Red 135, Pigment Blue 29, and 15: 1, 15: 3, Pigment Red 187, 263, Pigment Violet 19, and the like.

  Further, the haze in a 5 mm-thick molded product after injection molding at 280 ° C. is preferably 10% or less, and more preferably 8% or less.

  The polyester resin obtained by the present invention can be molded into a bottle or the like by, for example, molding it into a preform by injection molding and then performing stretch blow molding or blow molding a parison molded by extrusion molding. After forming into a sheet by extrusion molding, it is molded into a tray or container by thermoforming, or the sheet is biaxially stretched to form a film or the like, which is particularly useful as a packaging material for food or drink. . Among them, it is suitable for forming a bottle by a blow molding method in which a preform obtained by injection molding is biaxially stretched. For example, liquid seasonings such as carbonated beverages, alcoholic beverages, soy sauce, sauces, mirin, and dressings Furthermore, it is suitably used as a container for beverages such as fruit juice beverages, vitamin beverages, flavor teas, mineral waters, etc.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded.

Example 1
A slurry is prepared by using a continuous polymerization apparatus comprising a slurry preparation tank, a two-stage esterification reaction tank connected in series to the slurry preparation tank, and a three-stage melt polycondensation tank connected in series to the second-stage esterification reaction tank. To the preparation tank, terephthalic acid and ethylene glycol were continuously fed at a weight ratio of 865: 485, and a 0.3 wt% ethylene glycol solution of ethyl acid phosphate was added with phosphorus atoms (P ) Is continuously added in such an amount that the content becomes 0.194 mol, and a slurry is prepared by stirring and mixing. The slurry is 260 ° C. and a relative pressure of 50 kPa (0.5 kg) in a nitrogen atmosphere. / cm ² G), the first stage esterification reaction tank set for an average retention time of 4 hours, then, 260 ° C. under a nitrogen atmosphere, relative pressure 5 kPa ( .05kg / cm ² G), and continuously transferred to the second stage esterification reaction tank set for an average residence time of 1.5 hours to an esterification reaction. At that time, the average esterification rate measured by the method shown below was 85% in the first stage and 95% in the second stage.

<Average esterification ratio> For a solution obtained by dissolving a sample in a mixed solvent of deuterated chloroform / hexafluoroisopropanol (weight ratio 7/3) at a concentration of 3% by weight, a nuclear magnetic resonance apparatus ("JNM-" manufactured by JEOL Ltd.) was used. EX270 type)), 1H-NMR was measured and each peak was assigned, and the amount of terminal carboxyl groups (A mol / ton of sample) was calculated from the integrated value of the peaks. The esterification rate (E%) as a proportion of the carboxyl group that was esterified was calculated.
Esterification rate (E) = [1-A / {(1000000 / 192.2) × 2}] × 100

  At that time, a 0.6 wt% ethylene glycol solution of magnesium acetate tetrahydrate is added through the upper pipe provided in the second stage so that the content as magnesium atoms (Mg) per ton of the produced polyester resin is 0. .. Continuously added in an amount of 247 moles.

  Subsequently, when the esterification reaction product obtained above is transferred to a melt polycondensation tank, tetrabutyl titanate is added to the esterification reaction product in the transfer pipe with a titanium atom concentration of 0.15% by weight, An ethylene glycol solution with a water concentration of 0.5% by weight was added continuously at an amount of 0.063 mol as a titanium atom (Ti) per ton of the produced polyester resin. A first stage melt polycondensation tank set at a pressure of 2.6 kPa (20 Torr), then a second stage melt polycondensation tank set at 278 ° C. and an absolute pressure of 0.5 kPa (4 Torr); The inherent viscosity ([η1]) of the polyester resin obtained by continuously transferring to a third stage melt polycondensation tank set at 280 ° C. and an absolute pressure of 0.3 kPa (2 Torr) is 0.00. The residence time in each polycondensation tank was adjusted to 6 dl / g and melt polycondensed in a total of 3.17 hours, extracted in a strand form from the outlet provided at the bottom of the polycondensation tank, and after water cooling, A polyester resin cut into a chip-like granule by cutting with a cutter was produced.

  Subsequently, after the polyester resin chip obtained above was crystallized by continuously supplying it into a stirring crystallization machine maintained at about 160 ° C. in a nitrogen atmosphere so that the residence time was about 60 minutes. The residence time is adjusted so that the intrinsic viscosity ([η2]) of the resulting polyester resin is 0.75 dl / g at 205 ° C. under a nitrogen atmosphere, continuously fed to a tower-type solid-phase polycondensation apparatus. Then, solid phase polycondensation was performed by heating for 19 hours. The intrinsic viscosity ([η1]) of the melt polycondensation resin and the intrinsic viscosity ([η2]) of the solid phase polycondensation resin were measured by the following methods.

  <Intrinsic Viscosity> 0.25 g of freeze-pulverized resin sample is mixed with phenol / tetrachloroethane (weight ratio 1/1) and the concentration (c) is 1.0 g / dl. After 30 minutes at 120 ° C., in the case of a solid phase polycondensation resin at 120 ° C. for 30 minutes, the relative viscosity (ηrel) with the stock solution is measured at 30 ° C. using an Ubbelohde capillary viscosity tube. The ratio (ηsp / c) between the specific viscosity (ηsp) and the concentration (c) determined from the relative viscosity (ηrel) -1 was determined, and the concentration (c) was also 0.5 g / dl, 0.2 g / dl, 0 Each ratio (ηsp / c) was also obtained when 0.1 g / dl, and the ratio (ηsp / c) when the concentration (c) was extrapolated to 0 was calculated from these values as the intrinsic viscosity [η] ( dl / g).

  Further, the melt polycondensation rate (V1) as a value obtained by dividing the intrinsic viscosity ([η1]) of the melt polycondensation resin by the melt polycondensation time, the intrinsic viscosity ([η2]) of the solid phase polycondensation resin, and The solid phase polycondensation rate (V2) as a value obtained by dividing the difference ([η2]-[η1]) from the intrinsic viscosity ([η1]) of the melt polycondensation resin by the solid phase polycondensation time; The ratio (V2 / V1) of the solid phase polycondensation rate (V2) to the condensation rate (V1) was calculated, and the results are shown in Table 1.

  Moreover, about the obtained solid-phase polycondensation resin chip, the titanium component, the magnesium component, and the phosphorus component per ton of resin are contained as titanium atoms (Ti), magnesium atoms (Mg), and phosphorus atoms (P). The amount was measured by the method shown below, and the results are shown in Table 1.

  <Metal atom content> A resin emission sample (2.5 g) was ashed with hydrogen peroxide in the presence of sulfuric acid in a conventional manner, completely decomposed, and then made up to 50 ml with distilled water. YVON ICP-AES “JY46P type”) was used for quantitative determination and converted to a molar amount in 1 ton of polyester resin.

  Further, with respect to the obtained solid phase polycondensation resin chip, diethylene glycol copolymerization amount, acetaldehyde content, cyclic trimer content, and color coordinate b value as color tone were measured by the following methods, and the results are shown in Table 1. It was shown to.

  <Content of copolymerization component> Regarding a solution obtained by dissolving a resin sample in a mixed solvent of deuterated chloroform / hexafluoroisopropanol (weight ratio 7/3) to a concentration of 3% by weight, a nuclear magnetic resonance apparatus (Japan) 1H-NMR was measured using “JNM-EX270 type” manufactured by Denshi Co., Ltd., and each peak was assigned, and the content of the copolymerization component was calculated from the integrated value of the peaks.

  <Acetaldehyde content> A resin sample of 5.0 g was precisely weighed, sealed in a 50 ml internal volume cylinder with 10 ml of pure water under a nitrogen seal, and subjected to heat extraction at 160 ° C. for 2 hours. Acetaldehyde in the extract The amount was quantified using gas chromatography (“GC-14A” manufactured by Shimadzu Corporation) with isobutyl alcohol as an internal standard.

  <Cyclic trimer content> 200 mg of a resin sample was precisely weighed and dissolved in 2 ml of a mixed solvent of chloroform / hexafluoroisopropanol (volume ratio 3/2), and further diluted by adding 20 ml of chloroform, and then 10 ml of methanol. And the filtrate obtained by filtration was evaporated to dryness, the residue was dissolved in 25 ml of dimethylformamide, and the amount of cyclic trimer (cyclotriethylene terephthalate) in the solution was measured by liquid chromatography ( It quantified using "LC-10A" made by Shimadzu Corporation.

  <Color tone> A resin sample is filled in a cylindrical powder colorimetric cell having an inner diameter of 30 mm and a depth of 12 mm, and JIS Z8730 is used with a colorimetric color difference meter (“ND-300A” manufactured by Nippon Denshoku Industries Co., Ltd.). The color coordinate b value of Hunter's color difference formula in the Lab color system described in Reference 1 was obtained as a simple average value of values measured at four locations by rotating the measurement cell 90 degrees by the reflection method.

Subsequently, the obtained resin was dried in an inert oven (“IPHH-201 type” manufactured by ESPEC Co., Ltd.) at 160 ° C. for 4 hours under a nitrogen stream of 40 liters / minute, and then an injection molding machine (Meiko Seisakusho). “M-70AII-DM”), cylinder temperature 280 ° C., back pressure 5 × 10 ⁵ Pa, injection rate 40 cc / second, holding pressure 35 × 10 ⁵ Pa, mold temperature 25 ° C., molding cycle about 75 seconds. 1, a stepped molding plate having a thickness of 50 mm, a width of 100 mm, and a thickness of 6 steps from 6 mm to 3.5 mm in the horizontal direction and having a step difference of 0.5 mm was injection-molded. , G is a gate portion.

About the obtained shaping | molding board, acetaldehyde content and haze were measured with the method shown below, and the result was shown in Table 1.
<Acetaldehyde content> Measurement was performed in the same manner as described above, using a sample cut into a 4 mm square from the rear end portion (B portion in FIG. 1) of the 3.5 mm thickness of the molded plate.
<Haze> The thickness of 5.0 mm part (C part in FIG. 1) of the molded plate was measured using a haze meter (“NDH-300A” manufactured by Nippon Denshoku Co., Ltd.).

Separately, the obtained polyester resin chip was dried in a vacuum dryer at 130 ° C. for 10 hours, and then in an injection molding machine (“FE-80S” manufactured by Nissei Plastic Industrial Co., Ltd.), the cylinder temperature was 280 ° C. and the back pressure was 5 × 10 ⁵ Pa, injection rate 45 cc / second, holding pressure 30 × 10 ⁵ Pa, mold temperature 20 ° C., molding cycle about 40 seconds, outer diameter 29.0 mm, height 165 mm, average wall thickness 3.7 mm, weight A 60 g test tubular preform (preform) was injection molded.

The obtained preform was heated in a near-infrared irradiation furnace equipped with a quartz heater for 70 seconds, left at room temperature for 25 seconds, charged into a blow mold set at 130 ° C. While stretching in the vertical direction, blow molding at 7 × 10 ⁵ Pa for 1 second, further blow molding at 30 × 10 ⁵ Pa for 5 seconds, heat setting, air cooling, outer diameter about 95mm, height about 305mm, barrel A bottle having an average thickness of about 0.35 mm, a weight of about 60 g, and an internal volume of about 1.5 liters was molded.

About the obtained bottle, the acetaldehyde odor was evaluated by the method shown below, and the results are shown in Table 1.
<Acetaldehyde odor of the bottle> The acetaldehyde odor after heating the bottle in an oven at 50 ° C. for 1 hour is subjected to a sensory test. evaluated.

Examples 2-9, Comparative Examples 1-9
Copolymerization component and amount thereof, addition amount and order of addition of phosphorus compound, magnesium compound and titanium compound, titanium atom concentration and water concentration in ethylene glycol solution of titanium compound, melt polycondensation time and solid phase polycondensation time A polyester resin chip was produced in the same manner as in Example 1 except that the values were changed as shown in Table 1, and were similarly evaluated. The results are shown in Table 1. In Comparative Example 7, phosphorous acid instead of ethyl acid phosphate, cobalt acetate tetrahydrate instead of magnesium acetate tetrahydrate, and titanium potassium oxalate instead of tetrabutyl titanate were used, respectively. , Cobalt acetate tetrahydrate, and phosphorous acid were added in this order. In Comparative Example 9, orthophosphoric acid was used instead of ethyl acid phosphate, and tetrabutyl titanate, magnesium acetate tetrahydrate, and orthophosphoric acid were added in this order. .

(A) of the step-shaped formation board for physical property evaluation shape | molded in the Example is a top view, (b) is a front view.

Claims (7)

  A dicarboxylic acid component containing terephthalic acid or an ester-forming derivative thereof as a main component and a diol component containing ethylene glycol as a main component are subjected to an esterification reaction or a transesterification reaction. A compound of at least one element selected from the group consisting of group elements, (2) at least selected from the group consisting of group 1A metal elements of the periodic table, group 2A elements of the periodic table, manganese, iron, cobalt In producing a polyester resin by polycondensation in the presence of a compound of one kind of element and (3) a phosphorus compound, the amount of each compound of (1), (2), and (3) is The theoretical yield of the polyester resin per ton is 0.02 to 0.2 mol as the total atom (T) of the compound (1), and 0.04 to 0.00 as the total atom (M) of the compound (2). 6 moles of the compound of (3) Process for producing a polyester resin, characterized by the amount corresponding to 0.02 to 0.4 moles of the content as the total amount (P) of the child.   The production of the polyester resin according to claim 1, wherein the ratio (P / T) of the total amount (P) of atoms of the compound (3) to the total amount (T) of atoms of the compound (1) is 0.1-10. Method.   The polyester resin according to claim 1 or 2, wherein the ratio (M / T) of the total amount (M) of atoms of the compound (2) to the total amount (T) of atoms of the compound (1) is 0.1-10. Manufacturing method.   The order of addition of each compound of (1), (2), and (3) to the reaction system is (3), then (2), and then (1). A method for producing a polyester resin.   The method for producing a polyester resin according to any one of claims 1 to 4, wherein the compound (1) is a titanium compound, the compound (2) is a magnesium compound, and the compound (3) is a phosphate ester.   The polyester resin according to claim 5, wherein the titanium compound is added to the reaction system as an ethylene glycol solution having a titanium atom concentration of 0.01 to 0.3 wt% and a water concentration of 0.1 to 1 wt%. Production method.   The manufacturing method of the polyester resin in any one of Claims 1 thru | or 6 using 0.1-3 mol% isophthalic acid or its ester-forming derivative with respect to all the dicarboxylic acid components.

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