JP6241380B2 - 1,4-butanediol, method for producing polyester using 1,4-butanediol, and method for storing 1,4-butanediol - Google Patents

Description

  The present invention can obtain a polyester having excellent color tone and has little quality deterioration even when stored in an oxygen-containing atmosphere, and a method for producing a polyester using the 1,4-butanediol And a method for storing the 1,4-butanediol.

1,4-butanediol (hereinafter sometimes abbreviated as “BG”) is known to be an extremely useful substance used as a raw material for various solvents and derivatives. As an example, polyesters obtained by using BG as a diol component raw material, dicarboxylic acid, esterification reaction and / or transesterification reaction, and polycondensation reaction are used in various applications.
In particular, polybutylene terephthalate and polybutylene succinate have been widely used in recent years.

  Among them, polybutylene terephthalate (hereinafter sometimes abbreviated as “PBT”) using terephthalic acid as the main component of the dicarboxylic acid component has excellent mechanical properties, heat resistance, moldability and recyclability. Because of its high strength and excellent chemical resistance, it is widely used as a material for industrial molded products such as connectors, relays and switches for automobiles and electrical / electronic equipment. Furthermore, it is widely used for films, sheets, fibers, and the like, and accordingly, PBT having a good color tone has been demanded.

  Various methods for industrially producing BG have been developed. Among them, a method is known in which allyl alcohol is obtained via oxidation or acetoxylation of propylene, and this is oxo-reacted and hydrogenated to obtain BG (for example, see Patent Document 1).

  Further, Patent Documents 2 and 3 have a description of BG containing a trace that cyclic acetal cannot be quantitatively analyzed.

JP-A-6-234679 JP-A-6-305997 JP-A-6-305998

However, the polyester obtained using BG obtained by the method of Patent Document 1 sometimes has a poor color tone. Moreover, after storing this BG for a long period of time, the color tone of the polyester obtained using this BG may be further deteriorated.
And the color tone of the polyester obtained using BG of patent document 2 or 3 may worsen further.

Accordingly, an object of the present invention is to provide a BG that can obtain a polyester having excellent color tone and has little quality deterioration even when stored and stored in an oxygen-containing atmosphere.
Furthermore, the objective of this invention is providing the method which can manufacture efficiently PBT with favorable color tone.

The gist of the present invention is 1,4-butanediol (BG) containing 2-methyl-1,3-propanediol, which contains 1,4-ppm and 50-ppm by weight of a cyclic acetal compound. Butanediol. The BG preferably has a Σ carbonyl value of 0.50 mgKOH / g or less as measured by potentiometric titration.
The gist of the present invention is a method for producing a polyester using BG as a main component of a diol component. The polyester is preferably polybutylene terephthalate.
Furthermore, the gist of the present invention is a method for storing the BG in an oxygen-containing atmosphere, wherein the oxygen concentration in the atmosphere is from 0.1% by volume to 10% by volume.

  According to the present invention, even when stored in an oxygen-containing atmosphere, BG with little quality deterioration can be obtained, and furthermore, polyester with good color tone can be obtained by using BG with little quality deterioration. Moreover, quality deterioration is less under specific storage conditions.

FIG. 1 is an explanatory diagram of an example of an esterification reaction step employed in the present invention. FIG. 2 is an explanatory diagram of an example of a polycondensation reaction step employed in the present invention.

Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. Moreover, the lower limit value or the upper limit value in this specification means a range including the value of the lower limit value or the upper limit value.

  BG is produced by combining or combining either a petrochemical method and a biomass resource-derived fermentation process. For example, an acetoxylation reaction is performed using raw material butadiene, acetic acid and oxygen to obtain diacetoxybutene as an intermediate, and BG obtained by hydrogenating and hydrolyzing the diacetoxybutene; maleic acid, succinic acid, BG obtained by hydrogenating maleic anhydride and / or fumaric acid as raw materials; BG obtained by hydrogenating butynediol obtained by contacting acetylene with a formaldehyde aqueous solution as raw material; oxidation or acetoxylation of propylene BG obtained by obtaining allyl alcohol via oxo reaction and hydrogenation via BG; BG obtained by hydrogenating succinic acid obtained by fermentation method; BG obtained by direct fermentation from biomass such as sugar; .

<BG>
The BG of the present invention contains 2-methyl-1,3-propanediol and a cyclic acetal as impurities. These impurities are often contained in the BG of the production method via allyl alcohol. In the BG obtained by this production method, an acetal compound and a carbonyl compound can be produced by the presence of alcoholic OH and aldehyde during the production reaction.

  Depending on the method for producing BG, for example, when butadiene is used as the raw material, 2-methyl-1,3-propanediol in BG may not be detected (contained), but this BG is stored in an oxygen atmosphere. Quality degradation may be significant.

The lower limit of the content of 2-methyl-1,3-propanediol in the BG of the present invention is usually 1 ppm by weight, preferably 2 ppm by weight. To make it lower than the lower limit, it is too expensive for purification.
The upper limit of the content of 2-methyl-1,3-propanediol in BG is usually 500 ppm by weight, preferably 400 ppm by weight. If the upper limit is exceeded, the color tone of the polyester produced using this BG tends to deteriorate.

In the present invention, the upper limit of the content of the cyclic acetal compound in BG is 50 ppm by weight, preferably 40 ppm by weight. The lower limit is 1 ppm by weight from the viewpoint of purification efficiency, but is preferably 3 ppm by weight, more preferably 5 ppm by weight. If it is less than 1 ppm by weight, the component in which the acetal compound is polymerized and the component not counted in the following Σ carbonyl value increase, which is not preferable.
The upper limit of the Σcarbonyl value measured by potentiometric titration is preferably 0.50 mgKOH / g, more preferably 0.40 mgKOH / g. The lower limit is usually 0.01 mgKOH / g from the viewpoint of purification efficiency.

The method for measuring the Σcarbonyl value is described in the Examples. In addition, compounds such as acetals, aldehydes, and ketones quantified as carbonyl components by this method may be collectively referred to as Σcarbonyl compounds.
When the content of the cyclic acetal compound and the Σ carbonyl value are in the above ranges, even if BG is stored in an oxygen-containing atmosphere, there is little quality deterioration such as an increase in the carbonyl compound and the acetal compound, and the color tone of the polyester using this is There is a tendency not to get worse.

The content of 2-methyl-1,3-propanediol, the cyclic acetal compound and the Σ carbonyl value in the BG of the present invention can be adjusted by, for example, purification conditions including hydrogenation and distillation.
The content of 2-methyl-1,3-propanediol in BG of the present invention can be adjusted by strengthening the purification process of BG. That is, the content of 2-methyl-1,3-propanediol in BG can be adjusted by strengthening distillation conditions such as increasing the reflux amount and increasing the amount of light-boiling components extracted during distillation purification of BG. is there. Considering the production efficiency, it is not preferable to completely separate and remove it because it imposes a burden on distillation and separation, which is disadvantageous industrially.

  Actually, 2-methyl-1,3-propanediol tends to exist as an impurity in BG. The pressure during distillation is preferably normal pressure or reduced pressure conditions, more preferably 0.01 kPa or more and 760 kPa or less, and particularly preferably 0.1 kPa or more and 400 kPa or less as an absolute pressure. If the pressure is too high, the temperature at the bottom of the column becomes too high, and tetrahydrofuran formation by decomposition of BG proceeds, which is not preferable in terms of the basic unit. On the other hand, if the pressure is too low, an advanced vacuum facility is required, which is very expensive and is not industrially preferable. The temperature of the liquid in the bottom of the distillation column in the present invention is preferably 80 ° C. or higher and 230 ° C. or lower, particularly preferably 100 ° C. or higher and 180 ° C. or lower. If the temperature at the bottom of the column becomes too high, tetrahydrofuran conversion due to decomposition of BG proceeds, which is not preferable in terms of basic unit. If the temperature at the bottom of the column is too low, the pressure in the column needs to be greatly reduced, and an advanced vacuum facility is required, which makes the facility very expensive and is not industrially preferable.

In the present invention, the content of the cyclic acetal compound in BG and the Σ carbonyl value can be adjusted by strengthening the hydrogenation reaction at the time of BG production and the purification step of BG after the hydrogenation reaction.
The hydrogenation reaction is carried out using a known hydrogenation catalyst such as Pd, Pt, Ni, Ru, etc. at a hydrogen partial pressure of 0.5 MPk to 2 MPa at 40 ° C. to 250 ° C., preferably 50 ° C. to 150 ° C. BG after hydrogenation is purified by distillation.

The content of the cyclic acetal compound in BG and the Σ carbonyl value can be adjusted by the hydrogenation conditions such as the pressure in the hydrogenation reaction, the temperature reaction time, the reflux ratio at the time of distillation, and the distillation conditions such as the amount of light boiling components extracted. Since the cyclic acetal compound and the Σcarbonyl compound have components close to the boiling point of BG, complete separation and removal imposes a burden on distillation separation, which is industrially disadvantageous. Therefore, when production efficiency is considered, in reality, the cyclic acetal compound and the Σcarbonyl compound exist as impurities.

  Depending on the method for producing BG, for example, when the raw material is butadiene, the cyclic acetal compound in BG may not be detected (does not contain), but the quality of BG may be greatly deteriorated by storage in an oxygen atmosphere.

  Specific examples of the cyclic acetal compound in the present invention include compounds represented by the following formula (I).

(In the above formula (I), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, and n is a natural number of 2 to 6).

  Examples of the compound represented by the formula (I) include 2-methyl-1,3-dioxolane, 2-ethyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 2-methyl-1,3. -Dioxane, 2-ethyl-1,3-dioxane, 2-propyl-1,3-dioxane, 2-methyl-1,3-dioxepane, 2-ethyl-1,3-dioxepane, 2-propyl-1,3 -Dioxepane, 2-ethyl-1,3-dioxocane, 2-propyl-1,3-dioxonan and the like.

  When the BG of the present invention is stored in an oxygen-containing atmosphere, the oxygen concentration in the atmosphere is preferably 0.1% to 10% by volume. More preferably, it is 0.1 volume% to 7 volume% or less, and it is especially preferable that it is 0.1 volume% to 5 volume% or less.

Next, the polyester produced in the present invention will be described.
In the present specification, the “structural unit” in the polyester refers to a structural unit derived from a specific monomer in the polyester.

Further, in this specification, “main component” refers to occupying 70 mol% or more of the component. For example, “a diol compound containing BG as a main component” means that 70 mol% or more of all diol components is BG.
In the present specification, a step of performing an esterification reaction and / or a transesterification reaction is referred to as an esterification reaction step.

[1] Polyester raw material The polyester in the present invention has a structure in which a structural unit derived from a dicarboxylic acid component and a structural unit derived from a diol component are ester-bonded. Here, the dicarboxylic acid component means dicarboxylic acid and / or an ester-forming derivative thereof as a raw material for producing polyester, and the diol component means diol and / or a derivative thereof as a raw material for producing polyester.

In the polyester of the present invention, a dicarboxylic acid component containing dicarboxylic acid and / or dicarboxylic acid alkyl ester as a main component and a diol component containing BG as a main component are esterified and / or transesterified, followed by polycondensation. It is obtained by reacting.
PBT is preferred as the polyester using the BG of the present invention.

<Diol component>
When the BG of the present invention is used for production of polyester, the proportion of BG in the total diol component is preferably 80 mol% or more, more preferably 90 mol% or more, and 99 mol% or more. Is particularly preferred. When the proportion of BG in the total diol component is equal to or more than the above lower limit value, from the point of crystallization when forming into an electrical component or the like, and from the point of oriented crystallization of molecular chains by stretching when forming into a film, fiber, etc. In addition, the mechanical strength, heat resistance, fragrance retention and the like of the molded body are likely to be good.

(Diol components other than BG)
When using BG of this invention for manufacture of polyester, diol components other than BG may be contained in the raw material diol component.
Examples of diol components other than BG include ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, 1,5-pentanediol, neo Linear aliphatic diols such as pentyl glycol, 1,6-hexanediol, 1,8-octanediol; 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4 Cycloaliphatic diols such as cyclohexane dimethylol; good examples such as xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone Family diol; isosorbide, can be cited isomannide, Isoidetto, etc. diol derived from a plant material such as Eritoritan. Ethylene glycol, 1,3-propanediol and the like can also be derived from biomass resources. From the viewpoint of the physical properties of the resulting polyester, the other diol component is preferably ethylene glycol, 1,3-propanediol, polytetramethylene glycol, or 1,4-cyclohexanedimethylol. These diol components can be used alone or as a mixture of two or more.

<Dicarboxylic acid component>
When the polyester is produced using the BG of the present invention, the dicarboxylic acid component may be a dicarboxylic acid and / or an ester-forming derivative thereof obtained by either a petrochemical method or a production method having a fermentation process derived from biomass resources. It may be manufactured by the combination. The ester-forming derivative of dicarboxylic acid is preferably an ester-forming derivative such as a lower alcohol ester of dicarboxylic acid as well as an acid anhydride or acid chloride. Here, the lower alcohol usually refers to a linear or branched alcohol having 1 to 4 carbon atoms. As the dicarboxylic acid component, the monomer component is not limited as long as this condition is satisfied. For example, specific examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, and 4,4′-diphenyl ether. Dicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, aromatic dicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, 1,2 -Cycloaliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, isophoronedicarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, Listed are aliphatic dicarboxylic acids such as azelaic acid and sebacic acid. Rukoto can. Among these, from the viewpoint of heat resistance and mechanical properties, alicyclic dicarboxylic acids and aromatic dicarboxylic acids are preferable, and aromatic dicarboxylic acids are particularly preferable. From the viewpoint of crystallinity and heat resistance, terephthalic acid is preferred.

(Terephthalic acid component)
When the BG of the present invention is used for the production of PBT, the terephthalic acid component (terephthalic acid and / or its ester-forming derivative) is obtained by a conventional petrification method or a fermentation method derived from biomass resources. In the present invention, the proportion of the terephthalic acid component in the total dicarboxylic acid component is preferably 80 mol% or more, and more preferably 90 mol% or more. When the proportion of the terephthalic acid component is equal to or more than the above lower limit, molding is performed from the viewpoint of crystallization when molding into an electrical component or the like, and from the point of oriented crystallization of molecular chains by stretching when molding into a film, fiber, etc. Mechanical strength, heat resistance, fragrance retention, etc. as a body tend to be good.

(Dicarboxylic acid components other than terephthalic acid components)
When using BG of this invention for manufacture of PBT, dicarboxylic acid components other than a terephthalic acid component may be contained in the raw material dicarboxylic acid component.
When the BG of the present invention is used for the production of PBT, examples of dicarboxylic acid components other than the terephthalic acid component that can be used include oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelain. Aliphatic chain dicarboxylic acids such as acid, sebacic acid, undecadicarboxylic acid, dodecanedicarboxylic acid and ester-forming derivatives thereof; alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid and ester-forming derivatives thereof Phthalic acid, isophthalic acid, dibromoisophthalic acid, sodium sulfoisophthalate, phenylenedioxydicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylketonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4 Aromatic dicarboxylic acids such as 4,4'-diphenylsulfone dicarboxylic acid and 2,6-naphthalenedicarboxylic acid and ester-forming derivatives thereof. The ester-forming derivative is preferably an anhydride such as succinic anhydride or an adipic anhydride or a lower alcohol ester thereof.

  Among them, from the viewpoint of the physical properties of the polyester obtained, as dicarboxylic acid components other than terephthalic acid, aromatic dicarboxylic acid components such as isophthalic acid and naphthalenedicarboxylic acid, aliphatics such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid A dicarboxylic acid component is preferred. These dicarboxylic acid components can be used alone or in admixture of two or more.

<Other copolymerizable components>
When using BG of this invention for manufacture of PBT, in addition to the said diol component and dicarboxylic acid component, you may use other copolymerizable components as a manufacturing raw material of polyester further. Examples of other copolymerizable components that can be used in the present invention include hydroxycarboxylic acids and alkoxycarboxylic acids such as glycolic acid, p-hydroxybenzoic acid, p-β-hydroxyethoxybenzoic acid; stearyl alcohol, heneicosanol, octacosanol, Monofunctional carboxylic acids such as benzyl alcohol, stearic acid, behenic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid; tricarbaric acid, trimellitic acid, trimesic acid, pyromellitic acid, naphthalenetetracarboxylic acid, gallic acid And trifunctional or higher polyfunctional carboxylic acids such as trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sugar ester, and the like. These other copolymerizable components can be used alone or in admixture of two or more.

<Catalyst and additive>
(Esterification reaction or transesterification catalyst)
When using BG of this invention for manufacture of polyester, a catalyst is used in esterification reaction or transesterification. Examples of the catalyst include antimony compounds such as diantimony trioxide; germanium compounds such as germanium dioxide and germanium tetroxide; titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. Titanium compounds such as dibutyltin oxide, methylphenyltin oxide, tetraethyltin, hexaethylditin oxide, cyclohexahexylditin oxide, didodecyltin oxide, triethyltin hydroxide, triphenyltin hydroxide, triisobutyltin acetate, Dibutyltin diacetate, diphenyltin dilaurate, monobutyltin trichloride, tributyltin chloride, di Tin compounds such as tiltin sulfide, butylhydroxytin oxide, methylstannic acid, ethylstannic acid, butylstannic acid; magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium alkoxide, magnesium hydrogen phosphate, etc. A long-period periodic table (hereinafter also simply referred to as “periodic table”) 2A of calcium compounds such as calcium acetate, calcium acetate, calcium carbonate, calcium carbonate, calcium oxide, calcium alkoxide, calcium hydrogen phosphate, etc. In addition to group metal compounds, manganese compounds, zinc compounds, and the like can be given. Of these, titanium compounds and tin compounds are preferable, and tetrabutyl titanate is particularly preferable. These catalysts can be used alone or in admixture of two or more.

  The amount of esterification reaction or transesterification catalyst used in the production of the polyester of the present invention is not particularly limited, but the metal concentration contained in the obtained polyester is usually 1 ppm by weight or more, preferably 5 ppm by weight. More preferably, it is 10 ppm by weight or more, particularly preferably 20 ppm by weight or more, and most preferably 30 ppm by weight or more. On the other hand, the upper limit of the amount of the catalyst used is usually 300 ppm by weight or less, preferably 200 ppm by weight or less, more preferably 150 ppm by weight or less, still more preferably 100 ppm by weight or less, particularly preferably as the metal concentration contained in the obtained polyester. Is 90 ppm by weight or less, most preferably 60 ppm by weight or less. If the amount of catalyst used is less than or equal to the above upper limit value, it is less likely to cause foreign matters, and there is a tendency that deterioration reaction and gas generation during the heat retention of the resulting polyester are less likely to occur. Tend to be less likely to occur.

(Polycondensation reaction catalyst)
When the BG of the present invention is used for producing a polyester, a catalyst is used in the polycondensation reaction. As the catalyst, a catalyst for esterification reaction or transesterification reaction may be used as it is as a polycondensation reaction catalyst, or the catalyst may be further added. The amount of the polycondensation reaction catalyst is not particularly limited, but for the same reason as the above esterification reaction or transesterification catalyst, the metal concentration contained in the obtained polyester is usually 0.5 ppm by weight or more, preferably 1 ppm by weight or more, more preferably 3 ppm by weight or more, particularly preferably 5 ppm by weight or more, and most preferably 10 ppm by weight or more. On the other hand, the upper limit of the amount of catalyst used is usually 300 ppm by weight or less, preferably 200 ppm by weight or less, more preferably 100 ppm by weight or less, particularly preferably 50 ppm by weight or less, most preferably as the metal concentration contained in the obtained polyester. Is 30 ppm by weight or less.

Further, when a titanium compound is used as a catalyst, the concentration of titanium metal contained in the finally obtained polyester is preferably 250 ppm by weight or less, and 100 ppm by weight or less from the viewpoint of suppressing foreign matter. Is more preferably 60 ppm by weight or less, and most preferably 50 ppm by weight or less.
The metal concentration (weight) of the polyester can be measured using an atomic emission, Induced Coupled Plasma (ICP) method, etc. after recovering the metal contained in the polyester by a method such as wet ashing.

(Reaction aid)
In the esterification reaction, transesterification reaction and polycondensation reaction described later, in addition to the above catalyst, phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid and esters and metal salts thereof; sodium hydroxide, acetic acid Compounds of Group 1A metal elements such as sodium compounds such as sodium and sodium benzoate, potassium compounds such as lithium acetate, potassium hydroxide and potassium acetate; metals of Group 2A of the periodic table such as magnesium acetate and calcium acetate Elemental compounds can be added as reaction aids.

(Other additives)
In the esterification reaction, transesterification reaction, and polycondensation reaction described later, 2,6-di-t-butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3 ′, 5′-t-butyl- 4′-hydroxyphenyl) propionate]; thioether compounds such as dilauryl-3,3′-thiodipropionate, pentaerythrityl-tetrakis (3-laurylthiodipropionate); triphenyl phosphite, tris Antioxidants such as phosphorus compounds such as (nonylphenyl) phosphite and tris (2,4-di-t-butylphenyl) phosphite; representative of paraffin wax, microcrystalline wax, polyethylene wax, montanic acid and montanic acid ester Long chain fatty acids and esters thereof; A release agent such as Ile can also be used.

[2] Method for Producing Polyester When the BG of the present invention is used for producing a polyester, it contains 2-methyl-1,3-propanediol, contains 1 to 50 ppm by weight of a cyclic acetal compound, and There is no particular limitation except that BG having a Σcarbonyl value measured by potentiometric titration is 0.50 mgKOH / g or less, and a known polyester production method can be used. Although the example of the manufacturing method is demonstrated below, the manufacturing method of polyester in this invention is not limited to this.
Hereinafter, PBT will be described as an example of polyester.

<Manufacturing process>
PBT production methods are broadly classified into so-called direct polymerization methods in which terephthalic acid is used as the main raw material and transesterification methods in which a dialkyl ester of terephthalic acid is used as the main raw material. . In the former, water is produced in the initial esterification reaction, and in the latter, alcohol is produced in the initial transesterification reaction. However, there are differences in the availability of raw materials, the ease of distillate treatment, and the basic unit of raw materials. The direct polymerization method is preferred from the viewpoint of the height of the polymer and the improvement effect of the present invention.

  In the direct polymerization method, terephthalic acid and BG are esterified using an esterification reaction catalyst in a single-stage or multiple-stage esterification reaction tank, and the obtained oligomer as an esterification reaction product is overlapped. Examples thereof include a method of transferring to a condensation reaction tank and performing a polycondensation reaction using a polycondensation reaction catalyst in a multistage polycondensation reaction tank.

  On the other hand, as a transesterification method, a terephthalic acid dialkyl ester such as dimethyl terephthalate and BG are subjected to a transesterification reaction using a transesterification catalyst in a single-stage or multi-stage esterification reaction tank, and the obtained ester Examples include a method in which an oligomer as an exchange reaction product is transferred to a polycondensation reaction tank and subjected to a polycondensation reaction using a polycondensation reaction catalyst in a multistage polycondensation reaction tank.

(Esterification reaction conditions)
As an example of the esterification reaction, the temperature is usually 180 ° C. or higher, preferably 200 ° C. or higher, particularly preferably 210 ° C. or higher, and usually 260 ° C. or lower, preferably 250 ° C. or lower, particularly preferably 245 ° C. or lower. is there. The pressure of the esterification reaction is usually 10 kPa or more, preferably 13 kPa or more, and usually 120 kPa or less, preferably 110 kPa or less.

The time required for the esterification reaction is adjusted so as to make the range constant by measuring the esterification rate of the oligomer to be obtained, but it is usually 0.5 hours or more, preferably 1 hour or more, usually 5 It is less than time, preferably less than 3 hours. The esterification reaction rate is usually adjusted to 92% or more. When the esterification step is carried out continuously, the average residence time in the esterification reaction tank is regarded as the time required for the esterification reaction. In this way, an oligomer as an esterification reaction product is produced. The esterification reaction can be carried out either batchwise or continuously.
Subsequently, the oligomer obtained by the esterification reaction is transferred to a polycondensation reaction tank, and a polycondensation reaction is performed in the presence of a polycondensation reaction catalyst.

(Transesterification reaction conditions)
As an example of the transesterification reaction, the temperature is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly preferably 180 ° C. or higher, usually 260 ° C. or lower, preferably 245 ° C. or lower, particularly preferably 220 ° C. or lower. . Further, the pressure is usually 10 kPa or more, preferably 13 kPa or more, particularly preferably 60 kPa or more, and is usually 133 kPa or less, preferably 120 kPa or less, particularly preferably 110 kPa or less.

The time required for the transesterification reaction is adjusted by, for example, the amount of distillate during the transesterification reaction, and is usually 0.5 hours or more, preferably 1 hour or more, and usually 5 hours or less, preferably 3 hours. It is as follows. When the transesterification process is performed continuously, the average residence time in the transesterification reaction tank is regarded as the time required for the transesterification reaction. In this way, an oligomer as a transesterification product is produced. The transesterification reaction can be carried out either batchwise or continuously.
Subsequently, the oligomer obtained by the transesterification reaction is transferred to a polycondensation reaction tank, and a polycondensation reaction is performed in the presence of a polycondensation reaction catalyst.

(Esterification Reactor / Transesterification Reactor)
As the esterification reaction tank or transesterification reaction tank, known ones can be used, and any of the vertical stirring complete mixing tank, vertical heat convection mixing tank, tower type continuous reaction tank, etc. Moreover, it is good also as a multiple tank which connected the tank of the same kind or different kind in series as a single tank. Among them, a reaction tank having a stirrer is preferable. As a stirrer, in addition to a normal type including a power unit and a bearing, a shaft, and a stirring blade, a turbine stator type high-speed rotating stirrer, a disk mill type stirrer, a rotor mill type stirrer, and the like The type that rotates at a high speed can also be used.

There is no limitation on the form of stirring, and in addition to the normal stirring method in which the reaction solution in the reaction tank is directly stirred from the top, bottom, side, etc. of the reaction tank, a part of the reaction solution is piped outside the reactor, etc. The reaction solution can be circulated by taking it out and stirring with a line mixer or the like.
Known types of stirring blades can be selected, and specific examples include propeller blades, screw blades, turbine blades, fan turbine blades, disk turbine blades, fouller blades, full zone blades, Max blend blades, and the like.

(Polycondensation reaction conditions)
The polycondensation reaction can be carried out either batchwise or continuously.
As an example of the polycondensation reaction, the temperature is usually 210 ° C. or higher, preferably 220 ° C. or higher, usually 260 ° C. or lower, preferably 250 ° C. or lower, particularly preferably 245 ° C. or lower. The pressure of the polycondensation reaction is usually 27 kPa or less, preferably 20 kPa or less, more preferably 13 kPa or less, and in particular at least one polycondensation reaction tank is preferably under a reduced pressure of 2 kPa or less. The polycondensation reaction is carried out with stirring. The time required for the polycondensation reaction is adjusted so as to make the range constant by measuring the melt viscosity and intrinsic viscosity of the polyester obtained, but is usually 2 to 12 hours, preferably 2 to 10 hours. When the polycondensation reaction is carried out continuously, the average residence time in the polycondensation reaction tank is regarded as the time required for the polycondensation reaction.

(Polycondensation reactor)
Usually, a polycondensation reaction tank that performs a polycondensation reaction is equipped with a heat medium jacket for controlling the temperature. However, in order to facilitate temperature control, a heat medium coil is provided inside the polycondensation reaction tank. May be. The polycondensation reaction tank usually includes a stirring device having a vertical or horizontal direction as a center line. As a stirring blade, in the case of a stirrer having a center line in the vertical direction, anchor blades, paddle blades, fouller blades, and the like, in the case of a stirring device having a center line in the horizontal direction, such as a spectacle blade and a wheel blade, respectively. Can be used.

  Examples of the polycondensation reaction tank include known ones such as a vertical stirring polymerization tank, a horizontal stirring polymerization tank, and a thin-film evaporation polymerization tank. In the latter stage of the polycondensation where the viscosity of the reaction solution increases, mass transfer tends to be the controlling factor of molecular weight increase rather than reaction rate. It is advantageous to achieve the object of the present invention by lowering the surface and increasing the surface renewability, and one or more horizontal agitation polymerizations having a thin film evaporation function excellent in surface renewability, plug flow property and self-cleaning property It is preferable to select a machine.

(PBT granules)
The PBT obtained by the above polycondensation reaction is usually transferred from the bottom of the polycondensation reaction tank to a polymer extraction die and extracted into a strand shape, and cooled with water or after water cooling and then cut with a cutter to form pellets or chips. A granular material. The obtained granular material can be subsequently subjected to solid phase polycondensation by a known method or the like to increase its intrinsic viscosity.

(Example of manufacturing process)
Hereinafter, preferred embodiments of a method for producing a PBT of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example of an esterification reaction step employed in the present invention, and FIG. 2 is an explanatory diagram of an example of a polycondensation step employed in the present invention.
In FIG. 1, terephthalic acid as a raw material is usually mixed with BG in a raw material mixing tank (not shown) and supplied to the esterification reaction tank (A) in the form of slurry from a raw material supply line (1).
The catalyst of the present invention is preferably supplied from a catalyst supply line (3) after being made into a BG solution in a catalyst adjusting tank (not shown). FIG. 1 shows a mode in which the catalyst supply line (3) is connected to the recirculation line (2) of the recirculation BG, both are mixed, and then supplied to the liquid phase part of the esterification reaction tank (A).

The gas distilled from the esterification reaction tank (A) is separated into a high-boiling component and a low-boiling component in the rectifying column (C) through the distillation line (5). Usually, the main component of the high boiling component is BG, and the main components of the low boiling component are water and THF.
The high-boiling components separated in the rectification column (C) are extracted from the extraction line (6), passed through the pump (D), and partly from the recirculation line (2) to the esterification reaction tank (A). It is circulated and part is returned from the circulation line (7) to the rectification column (C). Further, the surplus is extracted outside from the extraction line (8). On the other hand, the light boiling components separated in the rectification column (C) are extracted from the gas extraction line (9), condensed in the condenser (G), and temporarily passed through the condensate line (10) to the tank (F). Accumulated. A part of the light boiling components collected in the tank (F) is returned to the rectification column (C) through the extraction line (11), the pump (E) and the circulation line (12), and the remainder is extracted. It is extracted outside through the line (13). The condenser (G) is connected to an exhaust device (not shown) via a vent line (14). The oligomer produced | generated in the esterification reaction tank (A) is extracted through a extraction pump (B) and the oligomer extraction line (4).

In the process shown in FIG. 1, the catalyst supply line (3) is connected to the recirculation line (2), but both may be independent. The raw material supply line (1) is an esterification reactor (
It may be connected to the liquid phase part of A).
Next, in FIG. 2, the oligomer supplied to the first polycondensation reaction tank (a) through the oligomer extraction line (4) is polycondensed under reduced pressure to become a prepolymer, and then the extraction gear pump ( c) and the second polycondensation reaction tank (d) through the extraction line (L1). In the second polycondensation reaction tank (d), polycondensation usually proceeds at a lower pressure than that of the first polycondensation reaction tank (a) to become a polymer. The obtained polymer is supplied to the third polycondensation reaction tank (k) through the extraction gear pump (e) and the extraction line (L3). The third polycondensation reaction tank (k) is a horizontal reaction tank composed of a plurality of stirring blade blocks and equipped with a biaxial self-cleaning type stirring blade. The polymer introduced into the third polycondensation reaction tank (k) from the second polycondensation reaction tank (d) through the extraction line (L3) is further subjected to a polycondensation reaction here, and then the extraction gear pump ( m) and a polymer extraction line (L5), and are extracted from the die head (g) in the form of a melted strand, cooled with water, and then cut with a rotary cutter (h) to form pellets. Reference numerals (L2), (L4), and (L6) denote vent lines of the first polycondensation reaction tank (a), the second polycondensation reaction tank (d), and the third polycondensation reaction tank (k), respectively. . The filters (R), (S), (T), and (U) are not necessarily all installed, and can be appropriately installed in consideration of the foreign matter removing effect and the operation stability.

[3] Physical properties of PBT Preferred physical properties of PBT when the BG of the present invention is used for the production of PBT will be described below.

(Intrinsic viscosity)
The intrinsic viscosity is not particularly limited, but is preferably 0.50 dL / g or more, more preferably 0.70 dL / g or more from the viewpoint of mechanical properties, pelletization stability, and moldability. When the intrinsic viscosity of the PBT of the present invention is equal to or higher than the lower limit value, there is a tendency that it is preferable in terms of mechanical properties of the molded product. On the other hand, the intrinsic viscosity of PBT is preferably 1.50 dL / g or less, more preferably 1.35 dL / g or less. If the intrinsic viscosity of the PBT is less than or equal to the upper limit, there is a tendency to be preferable in terms of moldability.
The intrinsic viscosity of the PBT of the present invention can be measured by the method described in the Examples section below.

(Color tone b value)
The color tone is displayed as a b value in the L, a, b color system. Although there is no restriction | limiting in particular in the said b value, The minimum is normally -5.0 or more, and it is preferable that it is -3.0 or more. On the other hand, the upper limit is usually 5.0 or less, and preferably 3.0 or less.
The color tone of the PBT of the present invention can be measured with a colorimetric difference meter, as described in the Examples section below.

[4] Composition of PBT If necessary, the following various additives and resins other than PBT are added to the PBT obtained when the BG of the present invention is used for the production of PBT to form a PBT composition. Can do. Moreover, it can be set as a molded object using this composition.

(Stabilizer)
Various stabilizers can be added as needed. Examples of the stabilizer include 2,6-di-t-butyl-4-octylphenol, pentaerythrityl-tetrakis [3- (3 ′, 5′-t-butyl-4′-hydroxyphenyl) propionate] and the like. Phenol compounds; thioether compounds such as dilauryl-3,3′-thiodipropionate, pentaerythrityl-tetrakis (3-laurylthiodipropionate); triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2 , 4-di-t-butylphenyl) phosphite, and other antioxidants. These stabilizers may be used individually by 1 type, and may be used in combination of 2 or more type. In order to obtain the effect of adding a stabilizer, the stabilizer is preferably added in an amount of 0.01 parts by weight or more, more preferably 0.05 parts by weight or more with respect to 100 parts by weight of PBT. On the other hand, from the viewpoint of economy, it is preferable to add 1 part by weight or less of the stabilizer to 100 parts by weight of PBT.

(Release agent)
Various mold release agents can be added as necessary. Examples of the release agent include paraffin wax, microcrystalline wax, polyethylene wax, long-chain fatty acids typified by montanic acid and montanic acid ester, release agents such as silicone oil, and the like. One of these release agents may be used alone, or two or more thereof may be used in combination. In order to obtain the effect of adding a release agent, it is preferable to add 0.01 parts by weight or more, and more preferably 0.05 or more, with respect to 100 parts by weight of PBT. On the other hand, from the viewpoint of economy, it is preferable to add 1 part by weight or less of the release agent with respect to 100 parts by weight of PBT.

(Filler)
Reinforcing fillers can be blended. The reinforcing filler is not particularly limited, but examples thereof include glass fibers, carbon fibers, silica / alumina fibers, zirconia fibers, boron fibers, boron nitride fibers, silicon nitride potassium titanate fibers, metal fibers and other inorganic fibers, aromatics Examples thereof include organic fibers such as polyamide fibers and fluororesin fibers. These reinforcing fillers may be used alone or in combination of two or more. Among the above reinforcing fillers, inorganic fillers are preferable, and glass fibers are particularly preferably used.

  When the reinforcing filler is an inorganic fiber or an organic fiber, the average fiber diameter is not particularly limited, but is usually 1 to 100 μm, preferably 2 to 50 μm, more preferably 3 to 30 μm, and particularly preferably 5 to 20 μm. . The average fiber length is not particularly limited, but is usually 0.1 to 20 mm, preferably 1 to 10 mm.

  The reinforcing filler is preferably used after being surface-treated with a sizing agent or a surface treatment agent in order to improve the interfacial adhesion with the PBT. Examples of the sizing agent or surface treatment agent include functional compounds such as epoxy compounds, acrylic compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type. The reinforcing filler can be surface-treated with a sizing agent or a surface treatment agent in advance, or can be surface-treated by adding a sizing agent or a surface treatment agent during the preparation of the PBT composition. The addition amount of the reinforcing filler is usually 150 parts by weight or less, preferably 5 to 100 parts by weight with respect to 100 parts by weight of PBT.

  Other fillers can be blended with the reinforcing filler. Other fillers to be blended include, for example, plate-like inorganic fillers, ceramic beads, asbestos, wollastonite, talc, clay, mica, zeolite, kaolin, potassium titanate, barium sulfate, titanium oxide, silicon oxide, oxidation Aluminum, magnesium hydroxide, etc. are mentioned. These fillers may be used individually by 1 type, and may be used in combination of 2 or more type. By blending the plate-like inorganic filler, the anisotropy and warpage of the molded product can be reduced. Examples of the plate-like inorganic filler include glass flakes, mica, and metal foil. Among these, glass flakes are preferably used. The amount of other filler added is usually 150 parts by weight or less, preferably 5 to 100 parts by weight, and more preferably 10 to 70 parts by weight or less with respect to 100 parts by weight of PBT.

(Flame retardants)
A flame retardant can be blended to impart flame retardancy. The flame retardant is not particularly limited, and specific examples include organic halogen compounds, antimony compounds, phosphorus compounds, other organic flame retardants, and inorganic flame retardants. Examples of the organic halogen compound include brominated polycarbonate, brominated epoxy resin, brominated phenoxy resin, brominated polyphenylene ether resin, brominated polystyrene resin, brominated bisphenol A, polypentabromobenzyl acrylate and the like. Examples of the antimony compound include antimony trioxide, antimony pentoxide, sodium antimonate, and the like. As a phosphorus compound, phosphate ester, polyphosphoric acid, ammonium polyphosphate, red phosphorus etc. are mentioned, for example. Examples of other organic flame retardants include nitrogen compounds such as melamine and cyanuric acid. Examples of other inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, silicon compound, and boron compound. These flame retardants may be used individually by 1 type, and may be used in combination of 2 or more type. The addition amount of the flame retardant is usually 50 parts by weight or less, preferably 10 to 40 parts by weight with respect to 100 parts by weight of PBT.

(Other additives)
If necessary, other conventional additives and the like can be blended. Such additives are not particularly limited and include, for example, stabilizers such as antioxidants and heat stabilizers, lubricants, catalyst deactivators, crystal nucleating agents, and crystallization accelerators. These additives can be added during the polymerization or after the polymerization. In addition, in order to give PBT the desired performance, UV absorbers, stabilizers such as weather resistance stabilizers, colorants such as dyes and pigments, antistatic agents, foaming agents, plasticizers, impact resistance improvers, etc. can do. These additives may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of other additives added is usually 5 parts by weight or less, preferably 0.05 to 2 parts by weight with respect to 100 parts by weight of PBT.

(Resin other than PBT)
Resins other than PBT can be blended as necessary. Examples of resins other than PBT include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polymethacrylic acid ester, ABS resin, polycarbonate, polyamide, polyphenylene sulfide, liquid crystal polyester, polyacetal, polyphenylene oxide, and other thermoplastic resins, phenol resins, and melamine Examples thereof include thermosetting resins such as resins, silicone resins, and epoxy resins. These thermoplastic resins and thermosetting resins can be used in combination of two or more. The amount of resin other than PBT is usually 90 parts by weight or less, preferably 1 to 70 parts by weight, and more preferably 3 to 50 parts by weight or less with respect to 100 parts by weight of PBT.

(Formulation method)
The method of blending the various additives and resins is not particularly limited, but a method of using a uniaxial or biaxial extruder having equipment capable of devolatilization from the vent port as a kneader is preferable. Each component including the additional components can be supplied to the kneader in a lump or can be supplied sequentially. In addition, two or more kinds of components selected from each component, including additional components, can be mixed in advance.

(Molding method)
The PBT obtained by using the BG of the present invention for the production of PBT and its composition are molding methods generally used for thermoplastic resins, that is, molding methods such as injection molding, hollow molding, extrusion molding, and press molding. It can be set as a molded object.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example at all unless the summary is exceeded. In addition, the measuring method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.

<Analysis method>
(1) Content of 2-methyl-1,3-propanediol and cyclic acetal compound in BG In a gas chromatographic analyzer (GC-2025 manufactured by Shimadzu Corporation), a polar column ("DB-WAX manufactured by J &W")"), A non-polar column (" DB-1 "manufactured by J & W) was used to determine the content of each peak component contained in BG by the modified area percentage method calculated from the effective carbon coefficient. Since the amount of the cyclic acetal component was very small, the sample was injected into the gas chromatograph without diluting the sample with a solvent.

The cyclic acetal compound can be detected by GC-MS and can be distinguished from other components contained in BG. Representative cyclic acetal compounds used for analysis are shown below, but it is not necessary to assign all fragments and signals.
2-ethyl-1,3-dioxepane (cyclic acetal)
GC-MS (EI): 71, 83, 101, 102

  Furthermore, a representative method for calculating the concentration of 2-ethyl-1,3-dioxepane using a gas chromatographic analyzer is shown. First, from the measurement using a polar column (condition 1), the concentration of 2-methyl-1,3-propanediol and 2-ethyl-1,3-dioxepane is determined from the peak area with a retention time of 38 minutes ( Because the peaks of the two substances overlap). Next, the concentration of 2-methyl-1,3-propanediol alone is determined from the peak area with a retention time of 14 minutes by measurement using a nonpolar column (condition 2). From the combined concentration of 2-methyl-1,3-propanediol and 2-ethyl-1,3-dioxepane minus the concentration of 2-methyl-1,3-propanediol, 2-ethyl-1, The concentration of 3-dioxepane was determined.

Details of the GC condition are as follows.
Condition 1 (polar column)
Analytical column: J & W DB-WAX, 60 m × 0.320 mmid, df = 0.5 μ
m
-Column flow rate: 1 mL / min
・ Split ratio: 1/90
・ Oven temperature: 70 ° C. (15 min) → 10 ° C./min→150° C., 175 ° C. × 45 min
・ Sample chamber, detector temperature: 240 ℃
・ Injection volume: 1 μL
・ Carrier gas: Nitrogen Condition 2 (Non-polar column)
Column: J & W DB-1, 60 m × 0.25 mmid, df = 1 μm
Column temperature: 50 ° C. (7 min) → 10 ° C./min→250° C. (20 min)
・ Inlet mode: Split (1/100)
・ Sample chamber, detector temperature: 240 ℃
・ Injection volume: 0.8μL
・ Carrier gas: Nitrogen

  The content of the cyclic acetal compound was calculated from the ratio between the area value of BG and the area value of the cyclic acetal compound, without correcting the effective carbon coefficient.

(2) Method for measuring Σcarbonyl value Σcarbonyl value is obtained by heating BG under acidic conditions to hydrolyze the acetal compound in BG to carbonyl component, then reacting with hydroxylamine hydrochloride, and potentiometric titration of the resulting hydrochloric acid It is a value indicating the total amount of carbonyl components in the sample, determined by measurement by the method.

  BG sample was precisely weighed in a 100 mL conical beaker, 10 mL of hydroxylamine hydrochloride solution (hydroxylamine hydrochloride (reagent grade) 50 g) was dissolved in 100 mL of water in each sample and blank beaker, 8.5 mL of hydrochloric acid was added, and ethyl was added. A solution (alcohol (reagent special grade) added to make the total volume 1 L)) was accurately added with a whole pipette, covered with a cooling tube, and heated in an oil bath at 60 ° C. for 2 hours. Then, after cooling to room temperature, 40 mL of methanol was added with a graduated cylinder, and titrated using an automatic titrator (“AUT-501” manufactured by Toa DKK) with stirring. As the titrant, a 0.1N methanolic potassium hydroxide solution was used. After completion of the titration, the Σ carbonyl value was calculated using the following formula (2).

  Σcarbonyl value = (A1-B1) × f × 5.6 / S1 (mgKOH / g) (2) (where A1 is a titration amount of 0.1 N potassium hydroxide required for titration (mL ), B1 is a titration amount (mL) of 0.1N potassium hydroxide required for titration with a blank, S1 is a sample amount (g), and f is a factor of 0.1N potassium hydroxide.)

(3) Intrinsic viscosity (IV)
It calculated | required in the following way using the Ubbelohde type viscometer. That is, using a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) and measuring the number of seconds of dropping only the polymer solution having a concentration of 1.0 g / dL and the solvent at 30 ° C., the following formula (4) I asked more.
IV = ((1 + 4KHη ^sp ) 0.5-1) / (2KHC) (4)
(Where η ^SP = η / η ⁰ −1, where η is the polymer solution drop seconds, η ⁰ is the solvent drop seconds, C is the polymer solution concentration (g / dL), and KH is the Huggins constant. (KH adopted 0.33.)

(4) Terminal carboxyl group concentration of PBT (equivalent / ton)
PBT 0.5g was melt | dissolved in benzyl alcohol 25mL, and it titrated using the 0.01 mol / L benzyl alcohol solution of sodium hydroxide, and computed with the following formula.
Terminal carboxyl group concentration = (A−B) × 0.1 × f / W (equivalent / ton)
However, A is the amount (μL) of 0.01N sodium benzyl alcohol solution required for titration, and B is 0.01 mol / L sodium benzyl alcohol solution required for titration with a blank. Amount (μL), W is the amount of PBT sample (g), and f is the titer of 0.01 mol / L sodium hydroxide.

(5) Pellet color tone Pellet-like polyester is filled into a cylindrical powder measurement cell having an inner diameter of 30 mm and a depth of 12 mm, and a colorimetric color difference meter Z300A (manufactured by Nippon Denshoku Industries Co., Ltd.) is used. The simple average value of values obtained by rotating the measurement cell by 90 degrees by the reflection method and measuring the b value by the color coordinate of Hunter's color difference formula in the Lab display system described in Reference Example 1 of Z8730 (1980). As sought.

(Reference example)
1000 parts by weight of BG produced by the allyl alcohol method was subjected to simple distillation at a pressure of 0.2 kPa and a temperature in the flask of 102 ° C. After distilling 500 parts by weight of the first distillate component-1 and 200 parts by weight of the first distillate component-2, 250 parts by weight of a component was obtained as a middle distillate component. 50 parts by weight of the residual component was obtained.
The obtained middle distillate component was further subjected to simple distillation to cut 175 parts by weight of the initial distillate component, and then 62.5 parts by weight of the middle distillate component was obtained.
Here, each of the obtained fractions and residue was analyzed and determined as follows. The quality is shown in Table 1.
BG produced by the allyl alcohol method is “BG-C”, the first fraction component-1 is “BG-D”, the first fraction component-2 is “BG-E”, the middle distillate component is “BG-A”, the kettle The remaining component is “BG-F”, and the middle distillate component obtained by simple distillation of the middle distillate component is “BG-B”.

Example 1
BG-A was stored under an oxygen-containing atmosphere.
That is, each BG is put into three stainless bottles so that the volume of the gas phase portion and the volume of the BG are the same, and nitrogen adjusted to a predetermined oxygen concentration is continuously circulated from the cylinder using an air displacement box, After replacing the gas phase part of the bottle with an oxygen concentration meter until a predetermined oxygen concentration was obtained, the bottle was sealed.
In this method, the gas phase parts were each 3% aerated nitrogen (oxygen concentration 0.63%), 5% aerated nitrogen (oxygen concentration 1.05%), 10% aerated nitrogen (oxygen concentration 2.1%) And the atmosphere. These were held at 60 ° C. for 10 days. The cyclic acetal content and Σ carbonyl value of each BG were measured. The results are shown in Table 1. Note that “%” of gas represents “volume%”.

(Example 2)
BG-B was stored in an oxygen-containing atmosphere as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
BG-C was stored in an atmosphere containing 1.05% oxygen as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
BG-D was stored in an atmosphere containing 1.05% oxygen as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
BG-E was stored in an atmosphere containing 1.05% oxygen as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
BG-F (the amount of the cyclic acetal compound “<1” means the measurement limit (less than 1 ppm by weight)) was stored in an atmosphere containing 1.05% oxygen in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In a reaction vessel equipped with a stirrer, a nitrogen inlet, a heating device, a thermometer, a distilling tube, and a vacuum outlet, 113 parts by weight of terephthalic acid, 183 parts by weight of BG-A, and tetra-n-butoxytitanium as a catalyst 0.7 parts by weight of a 6% by weight BG solution was charged, and the system was placed in a nitrogen atmosphere by nitrogen-reduced pressure substitution.

Next, the system was heated to 150 ° C. while stirring in the system, and then heated to 220 ° C. under atmospheric pressure over 1 hour, and an esterification reaction was carried out while distilling water produced for 2 hours.
Next, magnesium acetate tetrahydrate was dissolved in water, and then a BG solution prepared so that the magnesium acetate tetrahydrate was 1% by weight (magnesium acetate tetrahydrate, water, BG weight ratio 1: 2: 97) 1.3 parts by weight were added.

Next, after holding at 220 ° C. for 0.25 hour, it was held at 245 ° C. over 0.75 hour. On the other hand, the pressure was reduced to 0.07 kPa over 1.5 hours from the start of polymerization, and a polycondensation reaction was performed at the same degree of vacuum for 0.8 hours. Thereafter, nitrogen re-pressure was performed, the reaction system was returned to normal pressure, and polycondensation was completed.
The obtained PBT was extracted as a strand from the bottom of the reaction vessel, submerged in water at 10 ° C., and then the strand was cut with a cutter to obtain a pellet-like PBT.
The obtained PBT had an intrinsic viscosity of 0.83 dL / g, a terminal carboxyl group concentration of 6 equivalents / ton, and a color tone Co-b of 2.3, which were excellent in color tone. The results are shown in Table 2.

Example 4
In Example 3, BG-A was used, which was held at 60 ° C. for 10 days in a state where the gas phase part of the storage container was filled with 5% by volume of nitrogen aerated (oxygen concentration: 1.05% by volume). Except for the above, the same operation as in Example 3 was performed, and the obtained PBT had an intrinsic viscosity of 0.83 dL / g, a terminal carboxyl group concentration of 6 equivalents / ton, a color tone Co-b of 2.6, and an excellent color tone. It was. The results are shown in Table 2.

(Example 5)
In Example 3, the same operation as in Example 3 was performed except that BG-B was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 1.8, and the color tone was excellent. The b value results are shown in Table 2.

(Example 6)
In Example 4, the same operation as in Example 4 was performed except that BG-B was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, solution haze was 0.1%, color tone Co-b was 2.0, and the color tone was excellent. The b value results are shown in Table 2.

(Comparative Example 5)
In Example 3, the same operation as in Example 3 was performed except that BG-C was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 3.0. The b value results are shown in Table 2.

(Comparative Example 6)
In Example 4, the same operation as in Example 4 was performed except that BG-C was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 3.6. The b value results are shown in Table 2.

(Comparative Example 7)
In Example 3, the same operation as in Example 3 was performed except that BG-D was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 4.1. The b value results are shown in Table 2.

(Comparative Example 8)
In Example 4, the same operation as in Example 4 was performed except that BG-E was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 4.7. The b value results are shown in Table 2.

(Comparative Example 9)
In Example 3, the same operation as in Example 3 was performed except that BG-E was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 2.5. The b value results are shown in Table 2.

(Comparative Example 10)
In Example 4, the same operation as in Example 4 was performed except that BG-D was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 3.0. The b value results are shown in Table 2.

(Comparative Example 11)
In Example 3, the same operation as in Example 3 was performed except that BG-F was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 8.0. The b value results are shown in Table 2.

(Comparative Example 12)
In Example 4, the same operation as in Example 4 was performed except that BG-D was used instead of BG-A. The intrinsic viscosity of the obtained PBT was 0.83 dL / g, and the terminal carboxyl group concentration was 6. Equivalent / ton, color tone Co-b was 9.1. The b value results are shown in Table 2.

  From the results of Tables 1 and 2, Examples 1 and 2 clearly show the effects of suppressing the increase in cyclic acetal and Σcarbonyl value in comparison with Comparative Examples 1 and 2. Similarly, in Examples 4 and 6, compared with Comparative Examples 10 and 12, the effect of suppressing the increase in the b value of PBT is clear.

  According to the present invention, in the storage of BG, when it is difficult to completely replace the gas phase part with nitrogen, even if it is in contact with the remaining oxygen for a long time, BG with little quality deterioration can be obtained, and the color tone is good. Polyester can be obtained.

1: Raw material supply line 2: Recirculation line 3: Catalyst supply line 4: Oligomer extraction line 5: Distillation line 6: Extraction line 7: Circulation line 8: Extraction line 9: Gas extraction line 10: Condensation Liquid line 11: Extraction line 12: Circulation line 13: Extraction line 14: Vent line 15: Catalyst supply line 16: Catalyst supply line A: Esterification reaction tank B: Extraction pump C: Rectifier D, E: Pump F: Tank G: Capacitors L1, L3: Extraction lines L2, L4, L6: Vent line L5: Polymer extraction line L8: BG supply line L7: Metal compound supply line a: First polycondensation reaction tank c, e , M: extraction gear pump d: second polycondensation reaction tank k: third polycondensation reaction tank g: die head h: rotary cutter R, S, T, U: filter

Claims (5)

  1,4-butanediol containing 2-methyl-1,3-propanediol and containing 1 to 50 ppm by weight of a cyclic acetal compound.   The 1,4-butanediol according to claim 1, wherein the Σ carbonyl value measured by potentiometric titration is 0.50 mgKOH / g or less.   The manufacturing method of polyester which uses the 1, 4- butanediol of Claim 1 or Claim 2 as a main component of a diol component.   The method for producing a polyester according to claim 3, wherein the polyester is polybutylene terephthalate.   A method for storing the 1,4-butanediol according to claim 1 or 2 in an oxygen-containing atmosphere, wherein the oxygen concentration of the atmosphere is 0.1 vol% to 10 vol% -Method for storing butanediol.

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