JP2008115243A - Titanium compound catalyst and method for producing polyester using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for polyester production, easy to handle with no occurrence of precipitation, deposition and aggregation at the bottom of relevant vessel and/or apparatus owing to having such a property as to float near on the glycol solvent surface after prepared without containing any dissolving auxiliary or the like other than a titanium compound and a phosphorus compound as a stabilizer. <P>SOLUTION: The catalyst for polyester production comprises a reaction product of a titanium compound and a phosphorus compound of the general formula (1) (wherein, R<SB>1</SB>and R<SB>2</SB>are each a 1-18C alkyl or 6-12C aryl). A method for producing a polyester obtained by polycondensation between terephthalic acid and ethylene glycol using the catalyst is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a catalyst for the production of polyester.

  Polyester is excellent in mechanical strength, heat resistance, transparency, and gas barrier properties, and is suitably used as a material for films, sheets, fibers, etc., as well as materials for beverage filling containers such as juices, soft drinks, and carbonated beverages. ing.

  Such a polyester is usually produced using a dicarboxylic acid such as terephthalic acid and an aliphatic diol such as ethylene glycol as raw materials. Specifically, first, a low-order condensate (ester low polymer) is formed by an esterification reaction of an aromatic dicarboxylic acid and an aliphatic diol, and then this low-order condensate is formed in the presence of a polycondensation catalyst. It is deglycolized (liquid phase polycondensation) to increase the molecular weight. In some cases, solid state polycondensation is performed to further increase the molecular weight.

  In the polyester production method, an antimony compound, a germanium compound, or the like is conventionally used as a polycondensation catalyst. However, polyethylene terephthalate produced using an antimony compound as a catalyst is inferior to polyethylene terephthalate produced using a germanium compound as a catalyst in terms of transparency and heat resistance. Moreover, since the germanium compound is quite expensive, there is a problem that the production cost of the polyester is increased. For this reason, in order to reduce the production cost, a process of recovering and reusing the germanium compound scattered during the polycondensation has been studied.

  By the way, titanium is known to be an element having an action of promoting ester polycondensation reaction, and titanium alkoxide, titanium tetrachloride, titanyl oxalate, orthotitanic acid and the like are known as polycondensation catalysts. Many studies have been made to use a novel titanium compound as a polycondensation catalyst. By using a reaction product of a titanium compound and a monoalkyl phosphate as a catalyst, the quality of the product polymer is a disadvantage of conventional titanium catalyst-based polymers. A technique that substantially overcomes the above has been reported (see, for example, Patent Document 1).

  However, when a conventional titanium-based catalyst is used as a polycondensation catalyst, it is more active than antimony compounds and germanium compounds, but its solubility in solvents is poor. There is a problem that it is easy to do.

  Regarding the insolubility of the titanium catalyst in the solvent and the sedimentation property of the catalyst particles, the solid titanium catalyst obtained by hydrolysis of the titanium compound is dissolved in ethylene glycol, a solubilizing agent such as glycerin, and an acid such as sulfuric acid. A method for obtaining an ethylene glycol solution having a concentration of 3000 to 10000 ppm in terms of titanium atom by adding components and heating and dissolving at 120 to 200 ° C. is described (for example, see Patent Document 2). However, this method requires a very cumbersome processing step such as hydrolysis and dehydration drying to prepare a solid titanium catalyst, and also requires extra additives such as a dissolution aid and an acid component. When producing polyethylene terephthalate resin for beverage filling containers, there are concerns about the adverse effects on elution into flavored beverages and flavor properties.

  Further, an aqueous solution of sodium hydroxide is added to a mixed solution of titanium butoxide and ethylene glycol to obtain a yellow transparent solution (see Patent Document 3). However, it is widely known that the presence of alkali metal salt and alkaline earth metal salt adversely affects the hue of the polyester resin. In fact, the hue of polyethylene terephthalate obtained in Patent Document 2 is at least 3. 7 is extremely strong in yellow and is particularly inappropriate as a molding material for beverage filling containers.

  A reaction product of a phosphate compound having an ether bond in the side chain and a titanium compound (see, for example, Patent Document 4), and a reaction product of a phosphate compound having a hydroxyl group at the end of the side chain and a titanium compound (for example, Patent Document 4). Reference)) discloses a technique that has good polymerization activity and that the catalyst particles hardly settle in the liquid. However, these methods cannot completely suppress the sedimentation of the catalyst particles.

  It has been shown that a reaction product of titanium (IV) -2-ethylhexoxide and monoalkyl phosphate floats in an ethylene glycol solution, does not settle, has good dispersibility, and has good catalytic activity (for example, patents). However, since the volatility of 2-ethylhexanol by-produced when titanium (IV) -2-ethylhexoxide is reacted with monoalkyl phosphate is similar to that of ethylene glycol, this method is similar to ethylene glycol. While remaining in the catalyst solution, it is fed to the polymerization step and remains in ethylene glycol by-produced and distilled off in the polymerization reaction. Further, it is difficult to separate by distillation and may be concentrated in the recovered ethylene glycol as it is.

International Publication No. 03/008479 Pamphlet International Publication No. 02/016467 Pamphlet International Publication No. 00/071252 Pamphlet JP 2005-290289 A JP 2005-290290 A JP 2005-290291 A

  The problem of the present invention is that it does not contain a solubilizing agent other than a titanium compound or a phosphorus compound that is a stabilizer, and has a property of floating near the surface of a glycol solvent after preparation, so that it is precipitated at the bottom of the container and the apparatus. An object of the present invention is to provide a catalyst for polyester production that is easy to handle without being deposited or condensed.

［上記式中、Ｒ_１及びＲ_２は、それぞれ独立に１〜１８個の炭素原子を有するアルキル基又は６〜１２個の炭素原子を有するアリール基を表す。］
との反応生成物からなるポリエステル製造用触媒及びその触媒を用いてテレフタル酸とエチレングリコールを重縮合して得られるポリエステルの製造方法によって解決する事ができる。 In order to solve the above problems, the present inventor has intensively studied a polycondensation catalyst used in the production of polyester. As a polycondensation catalyst, a high catalyst is obtained by using a specific compound composed of a titanium atom and a phosphorus atom. It has been found that an active and excellent quality polyester can be produced, and the present invention has been completed. That is, the above-described problem is a titanium compound and a phosphorus compound represented by the following general formula (1):

[Wherein, R ₁ and R ₂ each independently represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]
This can be solved by a catalyst for producing a polyester comprising the reaction product of and a method for producing a polyester obtained by polycondensation of terephthalic acid and ethylene glycol using the catalyst.

  When the catalyst for polyester production according to the present invention is prepared in glycol, it floats near the surface of the glycol solvent after the catalyst preparation and does not accumulate or condense at the bottom of the container or the apparatus. Compared to a compound catalyst, it is easy to handle as a glycol dispersion. Therefore, polyester can be produced more efficiently. Furthermore, since the polyester produced with the catalyst of the present invention does not contain a solubilizing agent other than a titanium compound and a phosphorus compound as a stabilizer, it is useful as a material for a molded container for beverage-filled bottles.

Hereinafter, the present invention will be described in detail.
The catalyst for producing the polyester of the present invention can be obtained by a method in which a titanium compound and a phosphorus compound described later are mixed and reacted. However, in the case of obtaining the catalyst of the present invention, if the production method such as the compounding ratio of the titanium compound and the phosphorus compound, the reaction method, and the reaction conditions is not appropriate, the reaction does not occur sufficiently, and many unreacted titanium compounds and unreacted Reactive phosphorus compounds will be present.
Hereinafter, a production method for efficiently reacting the catalyst for producing the polyester of the present invention to obtain a high content will be described.

  Preferable examples of the titanium compound used in the synthesis of the catalyst include titanium tetraalkoxide and its condensates, and other organic titanium complex compounds. Specifically, titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetranormal propoxide, titanium tetrabutoxide, titanium tetraphenolate, hexamethyl dititanate, octamethyl trititanate, hexaethyl dititanate, Octaethyl trititanate, hexaisopropyl dititanate, octaisopropyl trititanate, hexanormal propyl dititanate, octanormal propyl trititanate, hexabutyl dititanate, octabutyl trititanate, hexaphenyl dititanate, octaphenyl trititanate, titanium tetrakisacetyl Acetonate complex, titanium tetrakis (2,4-hexanedionate) complex, titanium tetrakis (3,5-heptanedionate Complex, titanium dimethoxybisacetylacetonate complex, titanium diethoxybisacetylacetonate complex, titanium diisopropoxybisacetylacetonate complex, titanium dinormalpropoxybisacetylacetonate complex, titanium dibutoxybisacetylacetonate complex, titanium dihydroxy Bisglycolate, titanium dihydroxybislactate, titanium dihydroxybis (2-hydroxypropionate), titanium lactate, titanium octanediolate, titanium dimethoxybistriethanolamate, titanium diethoxybistriethanolamate, titanium dibutoxybistriethanolamin Preferred examples include nates. Among these, titanium tetrabutoxide, titanium tetraisosodium are less likely to be concentrated in the polymerization system by reacting with a phosphorus compound to prepare the catalyst compound of the present invention, and are inexpensive and economically advantageous. More preferred are propoxide, titanium tetranormal propoxide and their condensates, ie hexaisopropyl dititanate, octaisopropyl trititanate, hexanormal propyl dititanate, octanormal propyl trititanate, hexabutyl dititanate, octabutyl trititanate.

［上記式中、Ｒ_１及びＲ_２は、それぞれ独立に１〜１８個の炭素原子を有するアルキル基又は６〜１２個の炭素原子を有するアリール基を表す。］ Furthermore, in the catalyst for polyester production of the present invention, it is necessary to react this titanium compound with a phosphorus compound represented by the following general formula (1).

[Wherein, R ₁ and R ₂ each independently represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

  That is, the dialkyl phosphate or diaryl phosphate represented by the general formula (1) is preferable. Specifically, dimethyl phosphate, diethyl phosphate, diisopropyl phosphate, dinormal propyl phosphate, dibutyl phosphate, dipentyl phosphate, dihexyl phosphate, diheptyl phosphate, dioctyl phosphate, dinonyl phosphate, didecyl phosphate, diundecyl phosphate, didodecyl phosphate, Ditridecyl phosphate, ditetradecyl phosphate, dipentadecyl phosphate, dihexadecyl phosphate, diheptadecyl phosphate, dioctadecyl phosphate, diphenyl phosphate, bis (methylphenyl) phosphate, bis (ethylphenyl) phosphate, bis (isopropylphenyl) Phosphate, bis (normal propylphenyl) phos Bis (butylphenyl) phosphate, bis (pentylphenyl) phosphate, bis (hexylphenyl) phosphate, bis (dimethylphenyl) phosphate, bis (diethylphenyl) phosphate, bis (diisopropylphenyl) phosphate, bis (dinormalpropylphenyl) ) Phosphate, bis (trimethylphenyl) phosphate, bis (triethylphenyl) phosphate, bis (dimethylmonoethylphenyl) phosphate, bis (monomethyldiethylphenyl) phosphate, dinaphthyl phosphate, bis (methylnaphthyl) phosphate, bis (ethylnaphthyl) Mention may be made of phosphate and bis (dimethylnaphthyl) phosphate.

  These may be used alone or in a mixture, and examples thereof include a combination of a mixture of a dialkyl phosphate and a diaryl phosphate. In practice, dibutyl phosphate is particularly preferred from the viewpoint of economy and stability.

  The catalyst of the present invention is preferably produced by heating a titanium compound and a phosphorus compound using glycol as a medium. In this case, the reaction product is obtained as a suspension in glycol.

  Examples of the glycol here include ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, and cyclohexanedimethanol. The glycol used for the production of the catalyst is preferably the same glycol as the polyester produced using the catalyst.

  Since the reaction temperature at the time of producing the catalyst is room temperature, there is a problem that the reaction is insufficient or the reaction requires an excessive amount of time. Therefore, the reaction is usually preferably performed at a temperature of 50 ° C. to 200 ° C., and the reaction time is It is preferably completed in 1 minute to 4 hours.

  For example, when ethylene glycol is used as glycol, 50 ° C. to 150 ° C. is preferable, and when hexamethylene glycol is used, 100 ° C. to 200 ° C. is a preferable range, and the reaction time is more preferably 30 minutes to 2 hours. Become. If the reaction temperature is too high or the time is too long, the catalyst will deteriorate, which is not preferable.

  In addition, when the present catalyst is reacted, the blending ratio with the phosphorus compound is preferably 1.7 or more and less than 2.5 as the molar ratio of phosphorus atom to titanium atom, and more preferably 1.9 or more and less than 2.1. It is preferable that If it is less than 1.7, unreacted titanium compound is present and problems such as deterioration of polymer hue occur. Conversely, if it is 2.5 or more, excessive unreacted phosphorus compound is present and polymerization activity is lowered. .

  In the production of the polyester using the catalyst of the present invention, it is preferably used as a catalyst in an amount of 1 to 50 ppm in terms of titanium metal atom in the finally obtained polyester, and in an amount of 5 to 30 ppm. More preferably it is used. And as a metal atom in the polyester obtained, metal atoms other than titanium and phosphorus are preferably 10 ppm or less, more preferably 5 ppm or less in terms of metal element concentration.

  In addition, the said reaction product should just exist at the time of a polycondensation reaction. Therefore, the catalyst may be added in any step such as a raw material slurry preparation step, an esterification step, a liquid phase polycondensation step. Further, the entire amount of the catalyst may be added at once, or may be added in a plurality of times.

Next, the manufacturing method of polyester using the catalyst of this invention is demonstrated.
A polyester can be produced by polycondensation of an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic glycol using the catalyst of the present invention.

(material)
In the present invention, terephthalic acid and ethylene glycol are mainly used, but a small amount, for example, 20 mol% or less of a copolymer component may be included with respect to the total dicarboxylic acid component or the total glycol component. Examples of such copolymer components include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid or The ester-forming derivative can be used. Examples of the aliphatic glycol include trimethylene glycol, 1,2-propylene glycol, tetramethylene glycol, neopentyl glycol, hexanemethylene glycol, dodecamethylene glycol, diethylene glycol, bis (trimethylene) glycol, and bis (tetramethylene) glycol. be able to.

  Starting with terephthalic acid and the above aromatic dicarboxylic acids, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, or ester-forming derivatives thereof Aromatic glycols such as cyclohexanedimethanol, bisphenol, hydroquinone, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, and ethylene glycol and the above aliphatic diols. Diols can be used as raw materials. Furthermore, polyfunctional compounds such as trimesic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, and pentaerythritol can be used as raw materials.

(Esterification process)
First, when manufacturing polyester, aromatic dicarboxylic acid and aliphatic glycol are esterified. Specifically, a slurry containing an aromatic dicarboxylic acid and an aliphatic glycol is prepared. Such a slurry usually contains 1.1 to 1.6 mol, preferably 1.2 to 1.4 mol, of aliphatic glycol per mol of aromatic dicarboxylic acid. This slurry is continuously supplied to the esterification reaction step.

  The esterification reaction is preferably carried out in a single stage because the reactants are not self-circulated, or a method in which two or more esterification reactors are connected in series, both under conditions where the aliphatic glycol is refluxed. The water produced by the reaction is removed from the system with a rectification column.

  The reaction conditions in the case of carrying out esterification continuously in one stage without allowing the reactants to circulate are usually a reaction temperature of 240 to 280 ° C., preferably 250 to 270 ° C., and a reaction pressure of normal pressure to 0.00. The reaction is carried out under the condition of 3 MPa, and the reaction is desirably carried out until the esterification rate is usually 90% or more, preferably 95% or more.

By this esterification step, an esterification reaction product (oligomer) of aromatic dicarboxylic acid and aliphatic glycol is obtained, and the degree of polymerization of this oligomer is about 4-10.
The oligomer obtained in the esterification step as described above is then supplied to a polycondensation (liquid phase polycondensation) step.

(Liquid phase polycondensation process)
Next, in the liquid phase polycondensation step, in the presence of the polycondensation catalyst, the oligomer obtained in the esterification step is heated under reduced pressure to a temperature not lower than the melting point of the polyester (usually 240 to 280 ° C.). To polycondensate. This polycondensation reaction is desirably carried out while distilling off unreacted aliphatic glycol and aliphatic glycol generated by polycondensation outside the reaction system.

  The polycondensation reaction may be performed in one tank or may be performed in a plurality of tanks. For example, when the polycondensation reaction is performed in two stages, the polycondensation reaction in the first tank has a reaction temperature of 245 to 290 ° C., preferably 260 to 280 ° C., and a pressure of 100 to 1 kPa, preferably 50 to The polycondensation reaction is carried out under the condition of 2 kPa, and the polycondensation reaction in the final second tank is a reaction temperature of 265 to 300 ° C., preferably 270 to 290 ° C., and a reaction pressure of usually 1000 to 10 Pa, preferably 500 to 30 Pa. Done under. The fact that the desired degree of polymerization has been achieved can be detected, for example, by monitoring the stirring power energy (load) applied to the stirring blade by increasing the melt viscosity of the polyester. This confirms that the desired degree of polymerization (or average molecular weight, intrinsic viscosity) has been achieved. In this way, a polyester can be produced using the catalyst of the present invention. The polyester obtained in this polycondensation step is usually extruded in a molten state and cooled to obtain a granular (chip-shaped) one. The intrinsic viscosity IV of the obtained polyester is 0.40 to 0.80 dL / g, preferably 0.50 to 0.70 dL / g. If necessary, solid phase polymerization may be performed thereafter according to a known method.

  Therefore, the above-described method according to the present invention is easy to handle because the titanium catalyst does not precipitate and coagulate in the glycol solvent, and is very useful because it can produce polyethylene terephthalate simply and efficiently.

Hereinafter, the present invention will be described in more detail with reference to examples. In each example and comparative example, the physical properties were evaluated as follows.
○ Titanium atom and phosphorus atom concentration in the catalyst Set the dried catalyst sample on a scanning electron microscope (S570, manufactured by Hitachi Instrument Service Co., Ltd.) and connect it to an energy dispersive X-ray microanalyzer (XMA, Inc.) The catalyst's titanium atom and phosphorus atom concentrations were determined using Horiba Seisakusho EMAX-7000).
○ Intrinsic viscosity (IV)
After 0.6 g of polyester was dissolved by heating in 50 cc of o-chlorophenol, it was once cooled, and the solution was calculated from the solution viscosity measured at 35 ° C. using an Ubbelohde viscometer.
○ Hue (Col)
The granular polymer sample was heat-treated in a dryer at 160 ° C. for 90 minutes for crystallization, and then measured with a CM-7500 color machine manufactured by Color Machine Co., Ltd.
Diethylene glycol (DEG) content Samples were decomposed with hydrazine and measured by gas chromatography (GC).
○ Number of terminal carboxyl (COOH) The polymer sample was pulverized and precisely weighed, then dissolved in benzyl alcohol, and determined by neutralization titration with potassium hydroxide. It was converted into a numerical value per unit weight of polyester.

[Example 1]
While mixing and stirring 525.6 parts by weight of ethylene glycol and 6.0 parts by weight of dibutyl phosphate, 68.4 parts by weight of an ethylene glycol solution of titanium tetrabutoxide (1% by weight at a titanium atom concentration, acetic acid as a stabilizer). Was added slowly, and the mixture was gradually heated to 100 ° C. and stirred for 1 hour. The resulting suspension was allowed to cool to room temperature (hereinafter, this solution was referred to as “TD2 catalyst”). Liquid ”). As a result of analysis by the above-described method, the molar ratio of phosphorus atoms to titanium atoms in the catalyst in the TD2 catalyst solution was 2.0. Even when 100 mL of this solution was collected in a 100 mL graduated cylinder and allowed to stand for 240 hours, the catalyst particles remained floating and dispersed in the solution, and no precipitation or condensation occurred at the bottom. From these changes in the situation, it was judged that titanium tetrabutoxide and dibutyl phosphate reacted to form another product. Hereinafter, the solution containing the titanium / phosphorus reaction compound is referred to as a TD2 catalyst solution.

[Comparative Example 1]
While mixing and stirring 175.7 parts by weight of ethylene glycol and 1.5 parts by weight of monobutyl phosphate, 22.8 parts by weight of titanium tetrabutoxide (concentration of titanium atom: 1% by weight) was slowly added and gradually increased. After warming and holding at 100 ° C. for 1 hour with stirring, the resulting suspension was allowed to cool to room temperature. When 100 mL of this solution was collected in a 100 mL graduated cylinder and allowed to stand for 120 hours, a supernatant was generated in the 95 mL volume portion from the liquid surface, and catalyst particles were precipitated and condensed in the 5 mL volume portion. However, this condensate did not disperse again.

[Example 2]
179 parts of high-purity terephthalic acid and 95 parts of ethylene glycol were mixed in a reactor in which 225 parts of the polyester oligomer had been retained in advance under a condition of being maintained at 255 ° C. and normal pressure in a nitrogen atmosphere under stirring. The slurry prepared in this manner was supplied at a constant rate, and the esterification reaction was completed for 4 hours while water and ethylene glycol generated in the reaction were distilled out of the system to complete the reaction. The esterification rate at this time was 98% or more, and the polymerization degree of the produced polyester oligomer was about 5 to 7.

  225 parts of the oligomer obtained by this esterification reaction was transferred to a polycondensation reaction tank, and 1.8 parts of the TD2 catalyst solution prepared in Example 1 was added as a polycondensation catalyst. Subsequently, the polycondensation reaction is carried out while the reaction temperature in the system is raised and reduced in steps from 250 to 275 ° C. and the reaction pressure is raised from normal pressure to 60 Pa, respectively, and water and ethylene glycol generated in the reaction are removed from the system. went.

  The progress of the polycondensation reaction was confirmed without monitoring the load on the stirring blades in the system, and the reaction was terminated when the desired degree of polymerization was reached. Thereafter, the reaction product in the system was continuously extruded in a strand form from the discharge part, cooled and cut to obtain a granular pellet of about 3 mm. The polycondensation reaction time at this time was 124 minutes. The obtained polyethylene terephthalate had an IV of 0.509 dL / g, a DEG content of 1.20 wt%, a Col-L value of 84, a b value of 0.6, and a terminal COOH number of 23 eq / t. .

  When the catalyst for polyester production according to the present invention is prepared in glycol, it floats near the surface of the glycol solvent after the catalyst preparation and does not accumulate or condense at the bottom of the container or the apparatus. Compared with a compound catalyst, since it is easy to handle as a glycol dispersion, a polyester can be produced more efficiently. Furthermore, since the polyester produced with the catalyst of the present invention does not contain a solubilizing agent other than a titanium compound and a phosphorus compound as a stabilizer, it is useful as a material for a molded container for beverage-filled bottles.

Claims (2)

Titanium compound and phosphorus compound represented by the following general formula (1):

[Wherein, R ₁ and R ₂ each independently represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]
A catalyst for producing polyester comprising a reaction product of   A process for producing a polyester obtained by polycondensation of terephthalic acid and ethylene glycol using the catalyst according to claim 1.