JP2016020482A - Method for manufacturing polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin which has low haze of a molded article, reduces the amount of cyclic trimer in the polyester resin and has small increase of the cyclic trimer during molding even with low inherent viscosity for reducing filling time in injection molding.SOLUTION: There is provided a method for manufacturing a polyester resin including obtaining a prepolymer by a melting polycondensation step using a catalyst for polyester polycondensation obtained by an esterification reaction step or an ester exchange reaction step of a dicarboxylic acid component mainly containing terephthalic acid or ester formative derivative thereof and a diol component mainly containing ethylene glycol and then mixing three components of specific compounds in advance, and further conducting a solid polycondensation step, which provides a polyester resin having an intrinsic viscosity IVof 0.68 dL/g to 0.77 dL/g inclusive and a terminal carboxyl group amount of 12 eq/t or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polyester resin, which has a good moldability but reduces the amount of cyclic trimer and has a small increase in cyclic trimer during molding.

  Polyester resins typified by polyethylene terephthalate are excellent in chemical and physical properties, and thus are widely used in various applications such as containers such as beverage bottles, films, sheets, and fibers. In general, a polyester resin is produced by subjecting a dicarboxylic acid and a diol to an esterification reaction or a transesterification reaction, and a melt polycondensation reaction and, if necessary, a solid phase polycondensation reaction.

  In particular, when these polyester resins are used in containers such as beverage bottles, a method for obtaining containers by stretch blow molding after injection molding a pellet-shaped polyester resin to obtain a preform called a preform Is common. However, it is desired to shorten the injection molding cycle by further shortening the filling time of the molten resin into the mold during the injection molding.

  Usually, it is conceivable to increase the fluidity of the molten resin and shorten the filling time of the mold during injection molding by increasing the molding temperature during injection molding. However, in general, when the resin temperature at the time of melting of the polyester resin increases, the amount of aldehyde generated as a by-product from the diol increases. For this reason, there is a problem that the flavor deteriorates when a beverage is filled in a bottle obtained through stretch blow molding, and a polyester resin having good fluidity has been desired without changing the molding temperature.

  In order to improve the fluidity, it is considered effective to reduce the intrinsic viscosity of the polyester resin. However, the haze of the preform at the time of injection molding is likely to deteriorate, and there is a problem that the appearance of the bottle is poor or the formability in stretch blow molding is deteriorated. Consideration has been made. In particular, it has been clarified that the haze generation of the preform during injection molding is strongly related to the type and amount of the catalyst contained in the polyester resin, and many studies have been made.

  In general, in the production of a polyester resin, compounds such as antimony, germanium, aluminum, and titanium are used as a catalyst for polyester polycondensation. Depending on the type, amount and method of addition of these polycondensation catalysts, not only the activity during the production of the polyester resin, but also various properties of the resulting polyester resin, such as the color tone and the amount of foreign matter derived from the catalyst residue, and further molding It is known to strongly affect the by-products of body haze and molding.

  Of the above compounds, antimony compounds have been most commonly used as polyester polycondensation catalysts, but antimony compounds tend to precipitate in the form of fine particles in the melt polycondensation process, which becomes crystal nuclei, It is known that crystallization of a molded body is promoted during injection molding and haze tends to increase. In particular, when the intrinsic viscosity of the polyester resin as described above is lowered, the effect becomes remarkable, and the haze of the molded body using the antimony compound is not satisfactory.

Therefore, germanium compounds, aluminum compounds, titanium compounds and the like have been studied as polyester polycondensation catalysts instead of antimony compounds. In particular, titanium compounds are inexpensive, have no concern for safety and health, and have high activity, so that the amount of addition required for the polycondensation reaction can be reduced. Many crystal nuclei have not been generated, and many studies have been made.

  Patent Document 1 shows that by using a catalyst in which a titanium compound, a magnesium compound and a phosphorus compound are mixed in advance, the haze of the preform and the bottle is improved while improving the color tone of the polyester resin. However, all of these polyester resins have high intrinsic viscosities, and it takes time to fill the mold during injection molding, which is insufficient from the viewpoint of shortening the molding cycle.

Moreover, in patent document 2, the polyester resin with low intrinsic viscosity obtained using the catalyst which mixed the titanium compound, the magnesium compound, and the phosphorus compound previously is obtained. However, in recent years, the required strength has increased with the thinning of the bottle, and when this polyester resin is used, the intrinsic viscosity is too low and the mechanical strength is insufficient.
Furthermore, the amount of cyclic trimer produced as a by-product cannot be ignored simply by examining the conditions for solid-phase polycondensation and controlling the intrinsic viscosity to a suitable range. The cyclic trimer is mainly generated by an equilibrium reaction with a polymer, and when the amount is large, adhesion to the molding die frequently occurs, and as a result, haze is likely to occur in the molded body.

Patent Document 3 shows that the amount of cyclic trimer in a polyester resin can be reduced by adding a titanium compound, a magnesium compound, and a phosphorus compound separately and reducing the amount of terminal carboxyl groups. However, this production method does not satisfy the haze of the molded body.
Furthermore, in patent document 4, although the intrinsic viscosity and cyclic trimer amount of the polyester resin obtained using the catalyst which mixed the titanium compound, the magnesium compound, and the phosphorus compound previously have obtained the suitable thing, It was necessary to lengthen the solid phase polycondensation time, and the productivity was low.

JP 2006-342320 A JP 2006-199870 A Japanese Patent Laying-Open No. 2005-87741 JP 2004-224858 A

  The object of the present invention is to reduce the haze of a molded product even if the intrinsic viscosity is lowered in order to shorten the filling time in injection molding, reduce the amount of cyclic trimer in the polyester resin, and cyclic trimer during molding. It is to provide a polyester resin with less body increase.

The gist of the present invention is that 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 are subjected to an esterification reaction step or a transesterification step and then cycled. A compound <I> containing at least one selected from the group consisting of titanium group elements of Table 4A Group, at least one selected from the group consisting of Group 1A, Group 2A, manganese, iron and cobalt of the periodic table Group 1A, 2A Using a polyester polycondensation catalyst obtained by premixing the three components of the compound <II> and the phosphorus compound <III>, a prepolymer is obtained through a melt polycondensation step, and further through a solid phase polycondensation step. In the polyester resin production method, the intrinsic viscosity IV ₁ of the obtained polyester resin is 0.68 dL / g or more and 0.77 dL. / G or less and the amount of terminal carboxyl groups of the obtained polyester resin is 12 eq / t or less.

  By using the polyester resin obtained by this invention, the haze of a molded object can be kept favorable, shortening a molding cycle by shortening the filling time to the metal mold | die at the time of injection molding. And by reducing the amount of cyclic trimer in the polyester resin and reducing the amount of cyclic trimer increased during molding without post-treatment, dirt on the mold is suppressed, and further productivity is improved. It leads to improvement.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail below. However, the description of the constituent elements described below is a representative example of the embodiment of the present invention, and the present invention is limited to these contents. It is not a thing. In the present specification, “ppm” representing the content means “mass ppm” unless “mol” or the like is specified.
In the present invention, the compound <I> containing at least one selected from the group consisting of titanium group elements of Group 4A of the Periodic Table, from the group consisting of Group 1A, Group 2A, Manganese, Iron, and Cobalt of Periodic Table 1 It is preferable to use a polyester polycondensation catalyst obtained by previously mixing three components of the compound <II> containing at least one selected compound and the phosphorus compound <III>.

  The titanium group elements of Group 4A of the periodic table are titanium, zirconium, hafnium, and the like. Examples of the compound <I> of these elements specifically used in the present invention include oxides, hydroxides, alkoxides, acetates, carbonates, oxalates and halides of these elements. 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, titanium Sodium, titanic acid-aluminum hydroxide mixture, titanium chloride, titanium chloride-aluminum chloride mixture, titanium bromide, titanium fluoride, potassium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, six Examples 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 preferred, and tetra-n-butyl titanate is particularly preferred.

Compound <II> used in the present invention is at least one selected from the group consisting of a metal element of Group 1A of the periodic table, an element of Group 2A of the periodic table, manganese, iron and cobalt, which is a promoter metal. It is a compound containing. Examples of the Group 1A metal element and the Group 2A element of the periodic table include lithium, sodium, potassium, magnesium, and calcium. Examples of the compound <II> used in the present invention include oxides, hydroxides, alkoxides, acetates, carbonates, oxalates, and halides of these elements. 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, Examples include cobalt formate, cobalt acetate, cobalt oxalate, cobalt carbonate, cobalt bromide, and cobalt acetylacetonate. Of these, magnesium acetate or a hydrate thereof is particularly preferable because of its high solubility in glycol and easy preparation of a liquid catalyst.

  Furthermore, specific examples of the phosphorus compound <III> used in the present invention include orthophosphoric acid, polyphosphoric acid, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl. Phosphate, tricresyl phosphate, tris (triethylene glycol) phosphate, ethyl diethyl phosphonoacetate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate, triethylene glycol Pentavalent phosphorus compounds such as acid phosphate, phosphorous acid, hypophosphorous acid, diethyl phosphite, trisdodecyl phosphate , Tris nonyl decyl phosphite, trivalent phosphorus compounds such as triphenyl phosphite and the like. Among them, orthophosphoric acid, tris (triethylene glycol) phosphate, trimethyl acid phosphate, ethyl diethyl phosphonoacetate, ethyl acid phosphate, triethylene glycol acid phosphate and phosphorous acid are preferred. Tris (triethylene glycol) phosphate, methyl acid phosphate, ethyl diethyl phosphonoacetate, ethyl acid phosphate, butyl acid phosphate and triethylene glycol acid phosphate are particularly preferred.

The polyester polycondensation catalyst used in the present invention preferably does not contain a solid compound that is insoluble in a solvent such as alcohol, in terms of the brightness of the resulting polyester and the reduction of foreign matters derived from catalyst residues and polycondensation activity.
The polyester polycondensation catalyst used in the present invention may contain components such as a solvent, various stabilizers or additives.

The polyester polycondensation catalyst used in the present invention contains a phosphorus compound in terms of the color tone of the resulting polyester resin, reduction of by-products such as acetaldehyde and cyclic trimer, and improvement of thermal stability during molding. It is necessary. Accordingly, the polyester resin obtained by the present invention contains phosphorus.
In the polyester polycondensation catalyst used in the present invention, compound <I>, compound <II> and phosphorus compound <III> are mixed and added in advance, so that the haze of the preform during injection molding is further reduced. Therefore, it is preferable.

  As a method for obtaining a polyester polycondensation catalyst used in the present invention, alcohol, compound <I>, compound <II> and phosphorus compound <III> can be mixed and the mixture can be concentrated. Moreover, you may add what dissolved compound <I>, compound <II>, and phosphorus compound <III> directly in diol. In addition, when mixing compound <I>, compound <II>, and phosphorus compound <III>, when mixing in the order of compound <II>, phosphorus compound <III>, and compound <I> in alcohol or diol The precipitation of the compound <I> component is suppressed, which is more preferable.

In the present invention, the content (T) of titanium group atoms contained per ton of polyester resin is preferably 0.002 to 3.0 mol, and more preferably 0.002 to 1.0 mol. Preferably, it is 0.002-0.2 mol.
Moreover, as content (P) of the phosphorus atom contained per ton of polyester resin, it is preferable that it is 0.02-4.0 mol, and it is more preferable that it is 0.02-2.0 mol.

Furthermore, the total content (M) of metal atoms derived from the promoter metal compound per ton of polyester resin is preferably 0.1 to 3.0 mol, and preferably 0.3 to 1.0 mol. Is more preferable.
The amount of the compound <I>, compound <II>, or phosphorus compound <III> is the same as that of the titanium group atom (T) of the compound <I>, phosphorus atom (P) of the phosphorus compound <III>, compound <II>> The total amount of metal atoms (M) satisfying the molar amount in the above range, the molar ratio [P / T] of phosphorus atom (P) to titanium group atom (T) is 0.5 to 50, and Is preferably from 0.5 to 10, in particular from 1 to 3. Further, the molar ratio [M / T] of the total (M) of metal atoms to the titanium group atom (T) is preferably 0.1 to 20, more preferably 0.5 to 10, and particularly preferably 1 to 6. . Further, the molar ratio [P / M] of the phosphorus atom (P) to the total (M) of metal atoms is 0.01 to 10, more preferably 0.05 to 5, and particularly preferably 0.1 to 2. preferable.

  When the molar ratio [P / T] and the molar ratio [P / M] are less than the lower limit, and the molar ratio [M / T] is less than the lower limit or exceeds the upper limit, The color tone of the obtained polyester resin becomes yellowish. On the other hand, when the molar ratio [P / T] and the molar ratio [P / M] exceed the upper limit, and the molar ratio [M / T] is less than the lower limit, the polycondensability is present. There is a tendency to decrease.

  The polyester resin production method of the present invention uses a catalyst obtained by mixing three kinds of components in advance, sets the intrinsic viscosity of the polyester resin after solid-phase polycondensation to a specific range, and after the solid-phase polycondensation polyester resin Except for making the amount of the terminal carboxyl group below a certain value, post-treatment such as hot water treatment is not necessary, and basically a conventional method for producing a polyester resin can be used.

  A dicarboxylic acid component containing terephthalic acid or its ester-forming derivative as a main component and a diol component containing ethylene glycol as a main component are esterified in an esterification reaction tank, or transesterified using a transesterification catalyst. After the reaction, the polyester low molecular weight product which is the esterification reaction product or transesterification product obtained is transferred to a polycondensation tank, and the polyester polycondensation catalyst obtained by mixing in advance is used. Then, a melt polycondensation reaction is performed to obtain a prepolymer. After that, solid phase polycondensation reaction is performed using the obtained prepolymer. Further, any of these production methods may be a continuous type or a batch type, and is not particularly limited.

  The starting material used is preferably 90 mol% or more, more preferably 96 mol% or more of the proportion of terephthalic acid or its ester-forming derivative in the dicarboxylic acid component, and the proportion of ethylene glycol in the diol component is 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 97 mol% or more. If the proportion of terephthalic acid or its ester-forming derivative in the dicarboxylic acid component and the proportion of ethylene glycol in the diol component are less than the above ranges, the mechanical strength of the resulting polyester molded product tends to decrease.

Examples of ester-forming derivatives of terephthalic acid include esters having an alkyl group having about 1 to 4 carbon atoms. Examples of dicarboxylic acid components other than terephthalic acid include phthalic acid, isophthalic acid, sodium sulfoisophthalate, phenylene dioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4, Aromatic dicarboxylic acids such as 4′-diphenyl ketone dicarboxylic acid, 4,4′-diphenoxyethane dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, hexahydro Alicyclic dicarboxylic acids such as isophthalic acid, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecadicarboxylic acid, dodecadicarboxylic acid, and the like Having an alkyl group of about 1 to 4 carbon atoms That esters, and halides, one or more kinds may be used as a copolymerization component and the like.

  Examples of the diol component other than ethylene glycol include diethylene glycol. The proportion of diethylene glycol in the diol component is preferably 5 mol% or less, more preferably 1.5 mol% or more and 2.5 mol% or less, including the amount of by-products generated in the reaction system. Examples of other diol components include trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, 2-ethyl-2-butyl-1,3- Aliphatic diols such as propanediol, polyethylene glycol, polytetramethylene ether glycol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,5 -Alicyclic diols such as norbornane dimethylol, and xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4'-hydroxyphenyl) propane, 2,2-bis (4 -Β-hydroxyethoxyphenyl) propane, aromatic diols such as bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, and 2,2-bis (4′-hydroxyphenyl) propane One or two or more of ethylene oxide adduct or propylene oxide adduct may be used as a copolymerization component.

  Furthermore, for example, hydroxycarboxylic acids and alkoxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, p-β-hydroxyethoxybenzoic acid, and stearyl alcohol, heneicosanol, octacosanol, benzyl alcohol, stearic acid, behenic acid, benzoic acid Monofunctional components such as acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarballylic acid, trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetetracarboxylic acid, gallic acid, trimethylolethane, trimethylolpropane, glycerol, Further, one or two or more multifunctional components such as pentaerythritol and the like may be used as a copolymerization component.

  The raw material may be derived from fossil fuel, but may be derived from a plant and obtained through a fermentation method or the like. As plant-derived raw materials, ethylene glycol and terephthalic acid are known. In particular, plant-derived ethylene glycol is easily available and can be suitably used. In addition, it is preferable to use ethylene glycol from which impurities are sufficiently removed through distillation, activated carbon filtration or the like, and the purity is 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and particularly preferably. When it is 99% by mass or more, the color tone and polycondensation activity of the polyester resin are improved.

In the case of a transesterification reaction, it is generally necessary to use a large amount of the promoter metal compound as a transesterification catalyst. Therefore, as a method for producing a polyester resin in the present invention, dicarboxylic acid is used as a raw material, A method of producing via a chemical reaction is preferred.
In the esterification reaction, for example, using a multi-stage reaction apparatus in which a single esterification reaction tank or a plurality of esterification reaction tanks are connected in series, water generated in the reaction and excess ethylene glycol are removed from the system. On the other hand, the esterification reaction rate (the ratio of the esterified by reacting with the diol component among all the carboxyl groups of the raw material dicarboxylic acid component) is usually 90% or more, preferably 93% or more. Moreover, it is preferable that the number average molecular weights of the polyester low molecular weight body as an esterification reaction product obtained are 500-5,000.

As reaction conditions in the esterification reaction, when a single esterification reaction vessel is used, the temperature is usually about 200 to 280 ° C., usually about 0 to 400 kPaG (G represents a relative pressure with respect to atmospheric pressure), In general, the reaction time is about 1 to 10 hours under stirring. Moreover, when using a some esterification reaction tank, it reacts at the following reaction temperature and reaction pressure. The lower limit of the reaction temperature in the first stage esterification reaction tank is usually 240 ° C., preferably 245 ° C., the upper limit is usually 270 ° C., preferably 265 ° C., and the reaction pressure is usually 5 kPaG, preferably 10 kPaG, and the upper limit is Usually 300 kPaG, preferably 200 kPaG. Furthermore, the lower limit of the reaction temperature in the final stage is usually 250 ° C., preferably 255 ° C., the upper limit is usually 280 ° C., preferably 275 ° C., and the reaction pressure is usually 0-150 kPaG, preferably 0-130 kPaG.

  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 step is performed using the polyester polycondensation catalyst in the present invention.
Examples of the melt polycondensation step include a single melt polycondensation tank or a plurality of melt polycondensation tanks connected in series, for example, a fully mixed reactor in which the first stage includes a stirring blade, Examples include a method in which the ethylene glycol produced is distilled out of the system under reduced pressure using a multistage reaction apparatus comprising a horizontal plug flow reactor in which the second and third stages are equipped with stirring blades. .

  As an example of the reaction conditions in the melt polycondensation step, when a single polycondensation tank is used, the temperature is usually about 250 to 290 ° C., and gradually reduced from normal pressure to about 1.3 to 0.013 kPaG finally. In general, the reaction time is about 1 to 20 hours under stirring. Moreover, the following method is mentioned as an example in the case of using a some polycondensation tank. The lower limit of the reaction temperature in the first stage polycondensation tank is usually 250 ° C., preferably 260 ° C., the upper limit is usually 290 ° C., preferably 280 ° C., the reaction pressure is the upper limit usually −36 kPaG, preferably −75 kPaG, The lower limit is usually −100 kPaG, preferably −99 kPaG. Furthermore, the reaction temperature in the final stage is usually 265 ° C., preferably 270 ° C., the upper limit is usually 300 ° C., preferably 295 ° C., the reaction pressure is usually -100.0 kPaG, preferably -100.6 kPaG, The lower limit is usually −101.29 kPaG, preferably −101.24 kPaG. Furthermore, as the reaction conditions when using the intermediate stage, an intermediate condition between the first stage and the final stage is selected. For example, as an example of the reaction conditions for the second stage in a three-stage reactor, the reaction temperature is usually 265 ° C., preferably 270 ° C., the upper limit is usually 295 ° C., preferably 285 ° C., and the reaction pressure is usually higher. The method includes −94.8 kPaG, preferably −97.3 PaG, and the lower limit is usually −101.17 kPaG, preferably −101.03 kPaG.

  In the present invention, the polyester polycondensation catalyst is added to the reaction system at any stage of mixing and preparing the dicarboxylic acid component and diol component, any stage of the esterification process, or the initial stage of the melt polycondensation process. There may be. However, in order to produce a polyester excellent in color tone and transparency at a high reaction rate, the addition of the polyester polycondensation catalyst of the present invention to the reaction system is performed after the stage where the esterification reaction rate becomes 90% or more. As an example of a specific process, it is preferable to add to the final stage esterification reaction tank in the multistage reaction apparatus or the polyester low molecular weight body in the transfer stage from the esterification tank to the melt polycondensation process. Among these, it is more preferable to add to the low molecular weight polyester in the transfer stage from the esterification tank to the melt polycondensation process.

The intrinsic viscosity IV ₂ of the prepolymer obtained through the melt polycondensation step is obtained as a value measured at 30 ° C. using a mixed solution of phenol / tetrachloroethane (mass ratio 1/1) as a solvent. The lower limit is preferably 0.55 dL / g, more preferably 0.57 dL / g. The upper limit is preferably 0.67 dL / g, more preferably 0.65 dL / g. Is less than the intrinsic viscosity IV ₂ 0.55, when withdrawn from the polycondensation tank, which will be described later, because they tend to or become or becomes difficult pelletizing, requires long solid phase polycondensation reaction, productivity Decreases. On the other hand, if it exceeds 0.67, the reduction of the cyclic trimer in the solid phase polycondensation process becomes insufficient, and the mold becomes easily soiled during stretch blow molding, so that the haze of the bottle is deteriorated.

  The amount of terminal carboxyl groups of the prepolymer obtained through the melt polycondensation step is preferably 15 eq / t or less, more preferably 12 eq / t or less, and particularly preferably 10 eq / t or less. If the amount of the terminal carboxyl group is more than this value, the reduction of the cyclic trimer in the solid phase polycondensation step tends to be insufficient, and the mold tends to become dirty during stretch blow molding, so that the haze of the bottle tends to deteriorate.

The prepolymer obtained by the melt polycondensation step is usually extracted in a strand form from an extraction port provided at the bottom of the polycondensation tank, and then the strand-shaped prepolymer is cooled with water or after water cooling with a cutter. Cut into pellets or chips. Furthermore, in order to reduce acetaldehyde and a cyclic trimer contained in the chip, it is necessary to subject to a solid phase polycondensation reaction. The solid phase polycondensation reaction can be carried out by a conventionally known method, for example, the method described in paragraphs [0057] to [0065] of JP-A No. 2004-292803. The intrinsic viscosity IV ₁ of the polyester resin obtained by the present invention is 0.68 to 0.77 dL / g, more preferably 0.68 to 0.75 dL / g, and still more preferably 0.68 to 0.00. 74 dL / g. If it is less than 0.68, the molded body after injection molding tends to become cloudy due to crystallization. If it exceeds 0.77, the fluidity of the polyester resin in the molten state is lowered, and the time during which the polyester resin is filled in the mold during injection molding tends to be longer.

  The prepolymer granules may be pre-crystallized at a temperature lower than the solid phase polycondensation temperature before being subjected to the solid phase polycondensation step. For example, the granular material may be heated in a dry state at 120 to 200 ° C., preferably 130 to 190 ° C., particularly preferably 150 to 170 ° C. for about 1 minute to 4 hours. Further, the polyester resin obtained through the solid phase polycondensation step does not require any special post-treatment.

The acetaldehyde content in the polyester resin obtained by the present invention is preferably 10 ppm or less, and more preferably 5 ppm or less. If the acetaldehyde content exceeds the above upper limit, the flavor of the beverage tends to be impaired particularly when it is formed into a beverage bottle.
The content of the cyclic trimer in the polyester resin obtained by the present invention is preferably 8000 ppm or less, and more preferably 6000 ppm or less. When the content of the cyclic trimer exceeds the above upper limit, the mold surface is soiled at the time of bottle molding, causing haze due to unevenness on the wall surface of the resulting bottle.

  In the polyester resin obtained by the present invention, the cyclic trimer content after 10 minutes at 290 ° C. is preferably 9000 ppm or less, and more preferably 7500 ppm or less. When the above upper limit is exceeded, when the production of the bottle is repeated, the fine powder derived from the cyclic trimer will adhere to the molding die, and the haze of the bottle tends to deteriorate.

The polyester resin obtained by the present invention has a terminal carboxyl group amount of 12 eq / t or less, more preferably 10 eq / t or less, and particularly preferably 8 eq / t or less. If the amount of terminal carboxyl groups is larger than this, the reduction of the cyclic trimer becomes insufficient, and the haze of the bottle tends to deteriorate.
Intrinsic viscosity IV ₂ of the prepolymer obtained by the present invention can be controlled by the reaction pressure, reaction temperature and reaction time.

The amount of terminal carboxyl groups of the polyester resin obtained by the present invention can be controlled by adjusting the addition amount of the diol component in the esterification reaction step, the reaction pressure, the reaction temperature, or the molar ratio of the diol component to the dicarboxylic acid component. .
Intrinsic viscosity IV ₁ of the polyester resin obtained by the present invention, a prepolymer having an intrinsic viscosity IV _2-prepolymer gas flow or vacuum chip size reactor, the reaction temperature, reaction time and reactor gas composition, etc. Can be controlled by.

  The polyester resin obtained by this invention can obtain a preform and various molded objects by a conventional injection molding method. The filling time of the mold during injection molding is shorter as the pressure applied to the resin by a hydraulic cylinder (resin pressure) is higher. However, the load on the hydraulic motor is large and the energy loss is large, so the resin is as low as possible. Molding with pressure is desired. On the other hand, if the resin pressure is too low, the appearance of the resin such as the surface of the resin being solidified at the time of filling into the mold and undulating will occur. As a preferred example, when a 50.5 g molded body is injection molded at a cylinder temperature of 280 ° C., a mold temperature of 21 ° C., and a resin pressure of 30 MPaG, the filling time into the mold is 3.5 seconds or less. Is preferably 3.0 seconds or less, more preferably 2.5 seconds or less, and particularly preferably 2.0 seconds or less.

The polyester resin obtained by the present invention is suitable for obtaining various bottles by subjecting a preform obtained by injection molding to re-heating and then blow molding. In particular, when a bottle having a high draw ratio is obtained, according to the polyester resin of the present invention, since crystal nuclei causing haze are reduced, the whitening of the bottle due to overdrawing hardly occurs.
In addition, as a haze evaluation method of the polyester resin in the present invention, Tc2 (crystallization heat generation temperature during temperature drop) was adopted. This is because the crystallized polyester resin was heated and melted and then rapidly cooled to an amorphous state, then the temperature was raised and crystallized again to continue heating and melting, and the temperature was slowly lowered. It refers to the crystallization exotherm temperature. It is known that this crystallization temperature has a correlation with the haze of the bottle. If Tc2 is high, crystallization is likely to occur before injection molding and cooling after injection molding.

  The polyester resin obtained by the present invention can be molded into various molded products such as sheets, stretched films, bottles, fibers, etc. by a conventional method, but in particular, pressure resistance and heat resistance are not required, but at a high stretch ratio. It is preferably used for aseptic filling beverage bottles that are subjected to blow molding.

Examples The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In addition, the measurement of the physical property in an Example was performed by the following.
<Esterification reaction rate>
A polyester low molecular weight sample is pulverized in a mortar, 1.0 g of the sample is precisely weighed in a beaker, 40 mL of dimethylformamide is added thereto, and dissolved by heating at 180 ° C. for 20 minutes with stirring, and then dimethyl at 180 ° C. The beaker wall was washed with 10 mL formamide and cooled to room temperature. This solution was titrated with a 0.1 NKOH methanol solution using a complex pH electrode “EA-120” with a potentiograph “E-536 type” automatic titrator manufactured by Metrohm. The titration amount [A (mL)] obtained from the inflection point of the obtained titration curve, the factor [f ₁ ] of 0.1N KOH methanol solution prepared and standardized by the method of JIS K8006, and the sample mass [W (G)], the amount of free terminal carboxyl group [AV (meq / g)] was determined by the following formula.

AV (meq / g) = {A × f ₁ × (1/10)} / W
Next, 0.3 g of a sample pulverized in a mortar is precisely weighed into an Erlenmeyer flask, and 20 mL of 0.5NKOH ethanol solution is added with a whole pipette to this, and further 10 mL of pure water is added, a reflux condenser is set, and the surface temperature is set to 200. The sample was hydrolyzed by heating at reflux for 2 hours on a plate heater at 0 ° C. with occasional stirring. After allowing to cool, titration was performed with a 0.5N aqueous hydrochloric acid solution using phenolphthalein as an indicator. Here, 0.5N KOH ethanol solution and 0.5N
A hydrochloric acid aqueous solution was prepared and standardized by the method of JIS K8006. Moreover, 1 g of phenolphthalein was dissolved in 90 mL of ethanol, and a constant volume of 100 mL with pure water was used. Moreover, it titrated also in the blank state which does not put a sample on the same conditions. At that time, the sample titer [V _s (mL)], the blank titer [V _b (mL)], the factor of 0.5N hydrochloric acid aqueous solution [f ₂ ], and the sample mass [W (g)] From the following formula, the amount of carboxyl groups derived from all carboxylic acids [SV (meq / g)] was determined.
SV (meq / g) = {(V _b −V _s ) × f ₂ × (1/2)} / W
Next, the esterification reaction rate (%) was determined from the obtained AV (meq / g) and SV (meq / g) by the following formula.
Esterification reaction rate (%) = {(SV-AV) / SV} × 100

<Measurement of intrinsic viscosities IV ₁ and IV ₂ >
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solution of phenol / tetrachloroethane (mass ratio 1/1) as a solvent, a sample was dissolved at 110 ° C. for 30 minutes, and then at 30 ° C., a polyester resin solution having a concentration of 1.0 g / dL and The number of seconds for dropping only the solvent was measured and determined from the following formula.
Intrinsic viscosity (dL / g) = ((1 + 4K _H η _SP ) ^0.5 −1) / (2K _H C)
(Where η _SP = η / η ₀ −1, η is the number of seconds that the polymer solution falls, η ₀ is the number of seconds that the solvent is dropped, C is the concentration of the polymer solution (g / dL), and K _H is the Huggins constant. is .K _H adopted the 0.33 in.)

<Quantification of cyclic trimer>
After freeze-pulverizing the polyester resin after the solid-phase polycondensation reaction, 4.0 ± 0.5 mg of the sample was weighed, dissolved in 2 mL of hexafluoroisopropanol and confirmed to be completely dissolved, and then 38 ml of chloroform was added. Diluted. The amount of cyclic trimer in this solution was quantified by liquid chromatography (“Separations Module 2695” manufactured by Waters) and expressed in ppm per polyester resin.

<Quantification of cyclic trimer after holding at 290 ° C.>
After freeze-grinding the polyester resin after the solid-phase polycondensation reaction, about 1.0 g of the sample was weighed, sealed in a treaded branch tube, purged with nitrogen, and vacuum dried at 160 ° C. for 2 hours. . Thereafter, the pressure is restored by nitrogen, melting is performed in a constant temperature bath at 290 ° C. in a nitrogen atmosphere, and after a predetermined time has elapsed, the polyester resin is extracted from the lower part of the test tube, and the amount of cyclic trimer is determined by the method described in [0065]. The measurement of was carried out.

<Crystalline exothermic temperature Tc2 during temperature drop>
The polyester resin 10.0 ± 1.0 mg was precisely weighed and measured with DSC (differential scanning calorimeter). As measurement conditions, the temperature was raised from 20 ° C. to 285 ° C. at 20 ° C./min, held at 285 ° C. for 3 minutes, and then rapidly cooled. The temperature was raised again from 20 ° C. to 285 ° C. at 20 ° C./min, held at 285 ° C. for 3 minutes, and further lowered to 50 ° C. at 10 ° C./min. The crystallization exothermic peak temperature at this temperature fall was Tc2 (° C.). did.

<Quantification of the amount of terminal carboxyl groups>
350.0 ± 50.0 mg of polyester resin was precisely weighed, 10 mL of benzyl alcohol was added, and the mixture was stirred and dissolved at 195 ° C. for 9 minutes. Thereafter, 2 mL of ethanol was added, and titration was performed with an ethanolic potassium hydroxide solution 0.01 mol / L to determine the amount of terminal carboxyl groups per ton of resin, that is, the number of moles of terminal carboxyl groups (eq / t).

Example 1
<Preparation of catalyst solution A>
116.6 g of magnesium acetate tetrahydrate was put into a 500 mL glass eggplant-shaped flask equipped with a stirrer, and 250 g of absolute ethanol (purity 99% by mass or more) was further added. Further, 71.6 g of ethyl acid phosphate (mixing mass ratio of monoester and diester was 1: 1.22) was added and stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved after 20 minutes, 75.0 g of tetra-n-butyl titanate was added. Stirring was further continued for 10 minutes to obtain a uniform mixed solution. This mixed solution was transferred to a 1 L eggplant-shaped flask, and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After about 2 hours, most of the ethanol was distilled off, leaving a translucent viscous liquid. Next, 205.5 g of ethylene glycol was added so that the internal volume was 422 g, and low boiling point substances were further distilled off at 80 ° C. and a relative pressure of 0.050 kPaG over 2 hours. Solution A was obtained.

<Synthesis of low molecular weight polyester>
Using a batch production apparatus consisting of one stage of slurry preparation tank, one stage of esterification reaction tank and one stage of polycondensation reaction tank, 26 parts by mass of terephthalic acid and 12 parts by mass of ethylene glycol (molar ratio 1:
1.2) The slurry prepared by stirring in a slurry preparation tank under nitrogen gas was charged in advance with an esterification reaction product of 26 parts by mass of terephthalic acid and 12 parts by mass of ethylene glycol, and the temperature was 260 ° C. and the pressure was atmospheric pressure. The esterification reaction was carried out by supplying the esterification reaction tank held under a pressure of 1.0 × 10 ⁵ Pa (about 1 kgf / cm ² ) relative pressure to the esterification reaction product. A polyester low molecular weight product was obtained.

<Melt polycondensation process>
Subsequently, 104 parts by mass of the polyester low molecular weight product obtained above was weighed, transferred to a polycondensation reactor equipped with a stirrer with a torque meter, and the system was replaced with nitrogen. Polyester low molecular weight was dissolved for a minute. Hereinafter, the time is expressed with the polyester low molecular weight substance dissolution start time as 0 minutes. In this reactor, a catalyst solution A for polyester polycondensation prepared in advance was prepared as an ethylene glycol solution so that the solution was 8 ppm as titanium atoms with respect to the theoretical yield of the resulting polyester resin. .11 parts by mass was added. After an additional 65 minutes, 2.22 parts by mass of ethylene glycol was added. After 70 minutes, the pressure reduction was started, and after 130 minutes, the pressure was reduced to 2 Torr. The depressurization operation was performed so that the logarithmic value of the pressure was inversely proportional to time. The polycondensation temperature is raised from 260 ° C. to 280 ° C. at a constant rate during 70 to 150 minutes, and the melt polycondensation reaction is carried out so that the intrinsic viscosity IV ₂ is 0.62 to 0.66 dL / g. went. The polycondensation start time was set as the pressure reduction start time.

After completion of the melt polycondensation, stirring was stopped and the pressure was replaced with normal pressure with nitrogen, and the polycondensation reactor was taken out of the oil bath. After removing the polycondensation reactor from the oil bath, quickly evacuate the outlet of the reactor, extract the contents by slightly pressurizing the system with nitrogen, and water-cool and solidify the strand-shaped prepolymer Got. The prepolymer obtained was cut into chips, intrinsic viscosity IV ₂ was 0.644dL / g.

<Solid phase polycondensation process>
Subsequently, the prepolymer chip obtained by melt polycondensation was dried at 160 ° C. for 2 hours in an IPHH-201 type inert oven manufactured by ESPEC under a nitrogen flow of 30 L / min. Heating for 75 hours, solid phase polycondensation was performed to obtain a polyester resin.
Evaluation of the obtained polyester resin was performed by the method mentioned above.
These results are shown in Table 1.

(Example 2)
Evaluation was performed in the same manner as in Example 1 except that the prepolymer chip obtained in Example 1 was subjected to solid phase polycondensation at 210 ° C. for 5 hours. These results are shown in Table 1.

(Comparative Example 1)
Evaluation was performed in the same manner as in Example 1 except that the prepolymer chip obtained in the same manner as in Example 1 was subjected to solid phase polycondensation at 210 ° C. for 1 hour. These results are shown in Table 1.
When the intrinsic viscosity IV ₁ is low, Tc2 becomes high, as described above, the haze is increased is suggested.

(Comparative Example 2)
<Melt polycondensation process>
Using the low molecular weight polyester obtained in Example 1, the ethylene glycol solution of ethyl acid phosphate was added after 60 minutes, the ethylene glycol solution of magnesium acetate tetrahydrate was added after 65 minutes, and the ethylene of tetra-n-butyl titanate. The same procedure as in Example 1 was performed except that the glycol solution was added after 70 minutes.
An ethylene glycol solution of tetrabutyl-n-titanate was prepared according to the method described in Japanese Patent Application Laid-Open No. 2004-189921.

<Solid phase polycondensation process>
Subsequently, the prepolymer chip obtained in the melt polycondensation step was dried at 160 ° C. for 2 hours in an IPHH-201 type inert oven manufactured by ESPEC under a nitrogen stream of 30 L / min, and then at 210 ° C. for 5 hours. Heating and solid phase polycondensation were performed to obtain a polyester resin.
The obtained polyester resin was evaluated by the method described above, and these results are shown in Table 1.
It can be seen that, compared with Example 2 where the intrinsic viscosity IV ₁ is almost the same, Comparative Example 2 has a large increase in cyclic trimer after 10 minutes at 290 ° C. melting. Moreover, Tc2 was also high, suggesting that haze increases when the catalyst is added in portions.

(Comparative Example 3)
In Example 2, after carrying out similarly to Example 2 except not adding ethylene glycol and increasing the amount of terminal carboxyl groups 65 minutes afterward, the result obtained is shown in Table 1. It was found that when the amount of terminal carboxyl group is large, the amount of cyclic trimer is extremely increased.

(Comparative Example 4)
In the melt polycondensation step of Example 1, 0.48 parts by mass of an ethylene glycol solution of phosphoric acid was added after 60 minutes so that the phosphorus atom content was 15 ppm, so that the antimony atom content was 250 ppm. The same procedure as in Example 1 was performed except that 2.99 parts by mass of an ethylene glycol solution of antimony trioxide was added 65 minutes later, and the results obtained are shown in Table 1. Despite the high intrinsic viscosity IV _1, Tc2 is very high as compared with the embodiment, the haze may be increased is suggested.

  The polyester resin obtained by the present invention can shorten the mold filling at the time of injection molding, has a low haze of the injection molded body, and has a small amount of cyclic trimer, so that it can be used for manufacturing various beverage bottles, particularly aseptic filling beverage bottles. It can be used suitably.

Claims (5)

A dicarboxylic acid component mainly composed of terephthalic acid or an ester-forming derivative thereof and a diol component mainly composed of ethylene glycol are subjected to an esterification reaction step or a transesterification reaction step, and then a titanium of Group 4A of the periodic table. Compound <I> containing at least one selected from the group consisting of Group elements <I>, Compound <II> containing at least one selected from the group consisting of Group 1A, Group 2A, manganese, iron and cobalt of the periodic table And a polyester resin obtained by preliminarily obtaining a prepolymer through a melt polycondensation step using a polyester polycondensation catalyst obtained by mixing three components of the phosphorus compound <III> in advance, and further through a solid phase polycondensation step In the production method, the intrinsic viscosity IV ₁ of the obtained polyester resin is 0.68 dL / g or more and 0.77 dL / g or less. And the manufacturing method of the polyester resin whose terminal carboxyl group amount of the obtained polyester resin is 12 eq / t or less. Intrinsic viscosity IV ₂ prepolymers, method for producing a polyester resin according to claim 1 is 0.55 to 0.67.   The method for producing a polyester resin according to claim 1, wherein the amount of terminal carboxyl groups of the prepolymer is 15 eq / t or less.   The method for producing a polyester resin according to claim 1, wherein the compound <I> is a titanium compound.   The method for producing a polyester resin according to claim 1, wherein the compound <II> is a magnesium compound.