JP5790246B2 - Polyester manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a polyester, and more specifically, when producing a polyester using heated 1,4-butanediol as a raw material, the amount of by-produced tetrahydrofuran (hereinafter sometimes referred to as THF) is reduced, The present invention relates to a method for producing polyester that is efficient, stable and of good quality.

  Polyesters obtained by using an esterification reaction and / or transesterification reaction and a polycondensation reaction using a dicarboxylic acid component and a diol component as raw materials are used in various applications. Polybutylene terephthalate, polybutylene succinate, etc. using 1,4-butanediol (hereinafter sometimes referred to as 1,4-BG) as the main component of the diol are useful as engineering plastics and biodegradable polymers. ing.

A polycondensation reaction, particularly a melt polycondensation reaction, is usually carried out at a high temperature and under reduced pressure. This vacuum addition device has a vapor ejector, and it is known that 1,4-BG vapor is used as the vapor (patent). Reference 1).
However, in our study, an ejector using 1,4-BG vapor is used as a decompression addition device, 1,4-BG vapor used in the ejector is condensed and used as a polycondensation reaction raw material for a long period of operation. Then, the thermal stability of 1,4-BG is reduced, and by-produced tetrahydrofuran, the basic unit of 1,4-BG is deteriorated, the degree of reduced pressure is deteriorated, and the quality of the obtained polyester is deteriorated. It turns out that there is a tendency.

International Publication No. 2004/026938 Pamphlet

  The present invention relates to a polyester production method that requires a vacuum addition device equipped with a 1,4-BG vapor ejector to suppress the production of 1,4-BG from THF by heating, and to reduce the basic unit and the degree of vacuum. An object of the present invention is to obtain a polyester having good quality by stably performing a polycondensation reaction of polyester for a long period of time without causing deterioration.

As a result of intensive studies on the above-mentioned problems, the present inventors have adjusted the pH of 1,4-BG and the amount of nitrogen compounds when heating 1,4-BG to generate steam. , 4-BG was suppressed from the production of THF, and a stable operation method of the reduced pressure addition apparatus was found and the present invention was reached.
That is, the gist of the present invention resides in the following [1] to [4].
[1] In a method of continuously producing a polyester by subjecting a diol component mainly composed of 1,4-butanediol and a dicarboxylic acid component to an esterification reaction and / or a transesterification reaction, and a polycondensation reaction,
(A) performing a polycondensation reaction under reduced pressure;
(B) The reduced pressure addition device comprises a 1,4-butanediol vapor ejector,
(C) 1,4-butanediol used in the steam ejector is condensed and then used as a diol component, and (d) 1,4-butanediol is supplied to a steam generator for driving the steam ejector. pH is 7.0 or more and 11.0 or less,
A process for producing polyester, characterized in that
[2] The 1,4-butanediol supplied to the steam generator for driving the steam ejector contains a nitrogen compound of 0.1 to 150 ppm by weight as a nitrogen atom [1] ] The manufacturing method of description.
[3] The 1,4-butanediol supplied to the steam generator for driving the steam ejector contains a nitrogen compound, and the nitrogen compound is an amine compound and / or an amino alcohol compound. The production method according to [1] or [2].
[4] The production method according to [1] to [3], wherein the 1,4-butanediol is derived from a biomass resource.

  According to the present invention, when a polyester having 1,4-BG as a main component of diol is produced using a vacuum addition apparatus equipped with a 1,4-BG vapor ejector, the 1,4-BG is heated from 1,4-BG. It is possible to stably produce a polyester for a long period of time without producing deterioration in THF, causing deterioration of the basic unit and the degree of reduced pressure, and producing a good quality polyester.

It is explanatory drawing of an example of the esterification reaction process employ | adopted by this invention. It is explanatory drawing of an example of the polycondensation reaction process employ | adopted by this invention. It is explanatory drawing of an example of the pressure reduction addition apparatus employ | adopted by this invention.

<Polyester raw material>
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of constituent elements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.
The polyester in the present invention is a polymer having a structure in which a dicarboxylic acid component and a diol component are ester-bonded. Specific examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 4, Aromatic dicarboxylic acids such as 4′-diphenyl ether dicarboxylic acid, 4,4′-benzophenone dicarboxylic acid, 4,4′-diphenoxyethane dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, and 2,6-naphthalenedicarboxylic acid Cycloaliphatic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, malonic acid, succinic acid,
Examples include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc., from the viewpoint of mechanical properties, wide range of uses, availability of raw materials, etc. Among aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, and among aliphatic dicarboxylic acids, succinic acid and adipic acid are preferable.

  These dicarboxylic acid components can be subjected to the reaction as a dicarboxylic acid, as a dicarboxylic acid anhydride, or as an alkyl ester of a dicarboxylic acid, preferably as a dialkyl ester, and may be a mixture of a dicarboxylic acid and a dicarboxylic acid alkyl ester. There are no particular restrictions on the alkyl group of the dicarboxylic acid alkyl ester, but if the alkyl group is long, the boiling point of the alkyl alcohol produced during the transesterification reaction will increase, and the reaction solution will not volatilize, resulting in polymerization as a terminator. In view of this, an alkyl group having 4 or less carbon atoms is preferable, and a methyl group is particularly preferable.

In particular, (1) the main component of the dicarboxylic acid component is preferably terephthalic acid or an ester derivative thereof, or (2) succinic acid or an anhydride thereof. In the present specification, the main component means the largest amount of components in terms of mole among components (dicarboxylic acid component or diol component) containing the main component.

In the present invention, the main component of the diol component is 1,4-BG. Components other than 1,4-BG include ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, and 1,5-pentane. Diol, neopentyl glycol, aliphatic diol such as 1,6-hexanediol, 1,8-octanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4 -Arocyclic diols such as cyclohexane dimethylol, aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone,
Examples include diols derived from plant materials such as isosorbide, isomannide, isoidet, and erythritan. Ethylene glycol, 1,3-propanediol, 1,4-BG, and the like can also be derived from plant materials. it can.

In all diol components, 1,4-BG is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 95 mol% or more.
In the present invention, a hydroxycarboxylic acid such as lactic acid, glycolic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acid, etc. Monofunctional components (components having one hydroxy group or carboxyl group) such as acid, stearyl alcohol, benzyl alcohol, stearic acid, benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, tricarballylic acid, trimellitic acid, trimesin Trifunctional or more polyfunctional components (components having 3 or more hydroxy components and / or carboxylic acid components) such as acid, pyromellitic acid, gallic acid, malic acid, trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, etc. As a copolymer component It can be used.

Among them, (1) 50 mol% or more of dicarboxylic acid units, preferably 80 mol% or more, particularly preferably 95 mol% or more consists of terephthalic acid units, and 70 mol% or more of diol units, preferably 80 mol% or more, Particularly preferably, 95 mol% or more of polybutylene terephthalate composed of 1,4-BG units or (2) 50 mol% or more, preferably 80 mol% or more, particularly preferably 95 mol% or more of dicarboxylic acid units are succinic acid. Comprising at least 70 mol% of the diol unit, preferably at least 80 mol%, particularly preferably at least 95 mol%.
In polybutylene succinate composed of 4-BG units, the production scale is large, and the effect of the present invention is great.

<Manufacture of polyester>
In the following description of the polyester production method, the production of polybutylene terephthalate (hereinafter sometimes referred to as PBT) using terephthalic acid as the dicarboxylic acid and 1,4-BG as the diol will be described as an example. However, the method for producing the polyester is not limited thereto.

  The production of PBT can be based on a known production method except that a vapor ejector using 1,4-BG having a specific pH range is used as a pressure reduction addition method in the polycondensation reaction. These known methods are roughly classified into a so-called direct polymerization method using terephthalic acid as a main raw material and a transesterification method using terephthalic acid dialkyl ester as a main raw material. The former has the difference that water is produced in the initial esterification reaction, and the latter produces alcohol in the initial transesterification reaction, but the availability of raw materials, ease of distillate treatment, The direct polymerization method is preferred from the viewpoint of height and the improvement effect of the present invention.

  As an example of the direct polymerization method, terephthalic acid and 1,4-BG are charged in a molar ratio of 1,4-BG to terephthalic acid of 1.0 to 2.5, preferably 1.1 to 2.0. The temperature is 180 to 260 ° C., preferably 200 to 250 ° C., particularly preferably 210 to 245 ° C., and the pressure is 10 to 133 kPa using an esterification reaction catalyst in a single or multi-stage esterification reaction tank. , Preferably 13 to 101 kPa, particularly preferably 50 to 90 kPa, the reaction time is 0.5 to 5 hours, preferably 1 to 3 hours, and the resulting esterification reaction product is continuously esterified. The oligomer is transferred to a polycondensation reaction tank, and continuously in a multistage polycondensation reaction tank using a polycondensation reaction catalyst, the temperature is 210 to 260 ° C, preferably 220 to 250 ° C, particularly preferably 220 to 245 ° C., pressure of 27 kPa or less, preferably 20 kPa or less, particularly preferably 13 kPa or less, and in particular at least one polycondensation reaction tank, preferably 2 kPa or less under reduced pressure, with stirring for 2 to 12 hours, preferably The method of making polycondensation reaction in 2 to 10 hours is mentioned.

  On the other hand, as an example of the transesterification method, dimethyl terephthalate and 1,4-BG are heated in a single or multi-stage esterification reaction tank in the presence of a transesterification reaction catalyst at a temperature of 110 to 260 ° C. Preferably it is 140-245 degreeC, Most preferably, it is 180-220 degreeC, Moreover, a pressure is 10-133 kPa, Preferably it is 13-101 kPa, Most preferably, it is 60-90 kPa, Reaction time is 0.5-5 hours, Preferably it is 1- In 3 hours, the ester exchange reaction is continuously carried out, and the resulting oligomer as the ester exchange reaction product is transferred to the polycondensation reaction tank, and in the presence of the polycondensation reaction catalyst in the multi-stage polycondensation reaction tank. Continuously, the temperature is 210 to 260 ° C, preferably 220 to 250 ° C, particularly preferably 220 to 245 ° C, and the pressure is 27 kPa or less, preferably 20 kPa or less. Particularly preferred is a method in which a polycondensation reaction is carried out under agitation for 2 to 12 hours, preferably for 2 to 10 hours under stirring, preferably under a reduced pressure of 13 kPa or less, in particular at least one polycondensation reaction tank, preferably under a reduced pressure of 2 kPa or less. .

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

  Examples of the esterification reaction or transesterification catalyst in the present invention include antimony compounds such as diantimony trioxide, germanium compounds such as germanium dioxide and germanium tetroxide, tetramethyl titanate, tetraisopropyl titanate, and tetra-n-butyl titanate. Titanium compounds such as titanium alcoholates, titanium phenolates such as tetraphenyl titanate, etc., 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, Tin compounds such as nobutyltin trichloride, tributyltin chloride, dibutyltin sulfide, butylhydroxytin oxide, methylstannic acid, ethylstannic acid, butylstannic acid, magnesium acetate, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium In addition to calcium compounds such as magnesium compounds such as alkoxide and magnesium hydrogen phosphate, calcium acetate, calcium hydroxide, calcium carbonate, calcium oxide, calcium alkoxide and calcium hydrogen phosphate, manganese compounds, zinc compounds, etc. Of these, titanium compounds and tin compounds are preferable from the viewpoint of catalytic activity, and tetra-n-butyl titanate and tetraisopropyl titanate are particularly preferable.

The amount of the catalyst used is not particularly limited, but if it is too much, not only will it cause foreign substances, but it will tend to cause deterioration reaction and heat generation of PBT, and if it is too little, the main reaction rate will decrease. Since side reactions tend to occur, the metal concentration in the PBT is usually 1 to 300 ppm by weight, preferably 5 to 200 ppm by weight, more preferably 5 to 150 ppm by weight, and particularly preferably 10 to 100 ppm by weight. ppm, particularly 20 to 90 ppm by weight is preferred, and 30 to 60 ppm by weight is most preferred.

  Further, as the polycondensation reaction catalyst, a catalyst added during the esterification reaction or transesterification reaction may be used as a polycondensation reaction catalyst, and a new catalyst may not be added. May be. Although there is no restriction | limiting in particular in the usage-amount of a polycondensation reaction catalyst, For the same reason as the above when too much, as a metal concentration in PBT, 300 weight ppm or less, Preferably it is 200 weight ppm or less, More preferably, it is 100 weight ppm or less Particularly preferred is 50 ppm by weight or less, and most preferred is 30 ppm by weight or less.

  In the case of using an organic titanium compound as a catalyst, from the viewpoint of suppressing foreign matter, the titanium metal concentration in the PBT is preferably 250 ppm by weight or less, more preferably 100 ppm by weight or less. Preferably it is 60 weight ppm or less, Most preferably, it is 50 weight ppm or less. These metal concentrations can be measured using atomic emission, Induced Coupled Plasma (ICP), etc. after recovering the metal in the PBT by a method such as wet ashing.

  Further, in the esterification reaction, transesterification reaction, and polycondensation reaction, besides the catalyst, orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, and phosphorus compounds such as esters and metal salts thereof, hydroxylation Reaction aids such as alkali metals or alkaline earth metal compounds such as sodium, sodium benzoate, lithium acetate, potassium hydroxide, potassium acetate, magnesium acetate, calcium acetate, 2,6-di-t-butyl-4-octylphenol , Pentaerythrityl-tetrakis [3- (3 ′, 5′-t-butyl-4′-hydroxyphenyl) propionate] and the like, dilauryl-3,3′-thiodipropionate, pentaerythrityl-tetrakis Thioether compounds such as (3-laurylthiodipropionate), triphenyl phosphite , Antioxidants such as phosphorus compounds such as tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, paraffin wax, microcrystalline wax, polyethylene wax, montanic acid and montanic acid ester A long-chain fatty acid represented by (1) and its ester, a release agent such as silicone oil, and the like may be added.

  As the esterification reaction tank or transesterification reaction tank, known ones can be used, and any of types such as a vertical stirring complete mixing tank, a vertical heat convection mixing tank, a tower type continuous reaction tank, etc. Also, a single tank or a plurality of tanks of the same type or different types in series may be used. Among them, a reaction tank having a stirrer is preferable. As a stirrer, in addition to a normal type including a power unit, 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, etc. 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 liquid in the reaction tank is directly stirred from the top, bottom, side, etc. of the reaction tank, a part of the reaction liquid is piped outside the reaction tank, etc. It is possible to take a method of circulating the reaction liquid by taking it out with a line mixer and 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.

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 the reaction rate. Lowering and increasing the surface renewability is advantageous in order to achieve the object of the present invention. One or more horizontal agitation with a thin film evaporation function excellent in surface renewability, plug flow property and self-cleaning property It is preferable to select a polymerization machine.
The PBT obtained by the production method of the present invention can be subsequently subjected to solid phase polycondensation by a known method to increase the molecular weight.

Hereinafter, a preferred embodiment of the polyester production method of the present invention will be described with reference to the accompanying drawings, taking PBT as an example. 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 1,4-butanediol in a raw material mixing tank (not shown), and supplied to the reaction tank (A) in the form of slurry from the raw material supply line (1). The The catalyst of the present invention is preferably supplied from a catalyst supply line (3) after making a 1,4-butanediol solution in a catalyst adjusting tank (not shown). FIG. 1 shows a mode in which a catalyst supply line (3) is connected to a recycle line (2) for recycle 1,4-butanediol, and both are mixed and then supplied to the liquid phase part of the reaction tank (A). It was.

The gas distilled from the 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 1,4-butanediol, 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) and partly circulated from the recirculation line (2) to the reaction tank (A) via the pump (D). , 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 component separated in the rectification column (C) is extracted from the gas extraction line (9), condensed in the condenser (G), and passed through the condenser condensate line (10) to the tank (F). It is temporarily stored. 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 within the 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. Moreover, the raw material supply line (1) may be connected to the liquid phase part of the reaction vessel (A).
A compound of at least one metal selected from Group 1 and Group 2 of the periodic table is prepared to a predetermined concentration in a preparation tank (not shown), and then passes through line (L7) in FIG. After being further diluted with 1,4-butanediol, it is supplied to the oligomer extraction line (4) shown in FIG.

Next, the oligomer supplied to the first polycondensation reaction tank (a) is polycondensed under reduced pressure to form a prepolymer, and then passes through the extraction gear pump (c) and the extraction line (L1). It supplies to a double condensation reaction tank (d). 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 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 polycondensation here, and then the extraction gear pump (m ) And the extraction line (L5), and is 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.

<Ejector>
Here, in the present invention, the reduced pressure addition to the polycondensation reaction tank is performed by a 1,4-BG steam ejector.
Steam obtained by supplying 1,4-BG to the steam generator is used as ejector driving steam. The ejector uses a combination of a condenser installed at the downstream part of the ejector and a hot well tank connected to the condenser via an atmospheric leg. Using this method, it is possible to condense the organic components contained in the suction gas into 1,4-BG, which is the sealing liquid of the condenser. It can be used as a diol component.

  In the present invention, 1,4-BG used as a diol component of polyester or as an ejector driving vapor can be obtained by a conventionally known production method. For example, 1,4-BG obtained by obtaining diacetoxybutene which is an intermediate obtained by performing an acetoxylation reaction using raw material butadiene, acetic acid and oxygen, and hydrogenating and hydrolyzing the diacetoxybutene, Hydrogenation of butynediol obtained by contacting maleic acid, succinic acid, maleic anhydride and / or fumaric acid as raw materials, 1,4-BG obtained by hydrogenating them, and acetylene as raw materials and contacting with formaldehyde aqueous solution Crude 1,4-BG obtained, 1,4-BG obtained via oxidation of propylene, 1,4-BG hydrogenated succinic acid obtained by fermentation method, obtained from biomass such as sugar by direct fermentation 1,4-BG and the like.

<Biomass resource-derived 1,4-BG>
The diol component used for the production of the PBT of the present invention is preferably derived from biomass resources from the viewpoint of environmental protection.
Biomass resources are those that are stored by converting the light energy of the sun into forms such as starch and cellulose by the photosynthetic action of plants, animals that grow by eating plants, and plants and animals that are processed. Products that can be produced. Specifically, wood, rice straw, rice husk, rice bran, old rice, corn, sugar cane, cassava, sago palm, okara, corn cob, tapioca casserole, bagasse, vegetable oil residue, persimmon, buckwheat, soybean, oil, waste paper, paper residue, marine products Residues, livestock excrement, sewage sludge, food waste and the like. Among them, plant resources such as wood, rice straw, rice husk, rice bran, old rice, corn, sugarcane, cassava, sago palm, okara, corn cob, tapioca casserole, bagasse, vegetable oil residue, rice cake, buckwheat, soybean, oil, waste paper, paper residue More preferred are wood, rice straw, rice husk, old rice, corn, sugar cane, cassava, sago palm, straw, oil, waste paper, papermaking residue, and most preferred are corn, sugar cane, cassava, sago palm.

Biomass resources generally contain many alkali metals and alkaline earth metals such as elemental nitrogen, Na, K, Mg, and Ca.
The method of these biomass resources is not particularly limited. For example, the biomass resources are subjected to known pretreatment and saccharification steps such as chemical treatment with acids and alkalis, biological treatment using microorganisms, physical treatment, and the like. Induced to carbon source. The process often includes a refinement process by pretreatment such as chipping, scraping, or crushing biomass resources, and further includes a grinding process by a grinder or a mill as necessary. The refined biomass resources are usually guided to a carbon source through further pretreatment and saccharification steps. Specific methods include chemical methods such as acid treatment with strong acids such as sulfuric acid, nitric acid, hydrochloric acid and phosphoric acid, alkali treatment, ammonia freeze steaming explosion method, solvent extraction, supercritical fluid treatment, oxidant treatment, etc .; And physical methods such as steam explosion method, microwave treatment and electron beam irradiation; biological treatment such as hydrolysis by microorganisms and enzyme treatment.

  Carbon sources derived from the above biomass resources usually include hexoses such as glucose, mannose, galactose, fructose, sorbose, tagatose; pentoses such as arabinose, xylose, ribose, xylulose, ribulose; pentose, saccharose, starch, cellulose Disaccharides and polysaccharides such as butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, monoctinic acid, arachidic acid, eicosene Fats and oils such as acid, arachidonic acid, behenic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, lignoceric acid and ceracolonic acid; fermentation of polyalcohols such as glycerin, mannitol, xylitol and ribitol Sugar is used. Of these, hexoses such as glucose, fructose, and xylose or pentose are preferable, and glucose is particularly preferable. As a carbon source derived from a broader plant resource, cellulose which is a main component of paper is also preferable.

Usually, using these carbon sources, diols can be obtained by fermentation using microbial conversion, chemical conversion methods including reaction steps such as hydrolysis, dehydration, hydration, and oxidation, and combinations of these fermentation and chemical conversion methods. Is synthesized. Among these, the fermentation method by microbial conversion is preferable.
The diol used for producing the PBT of the present invention may be produced directly from a carbon source such as glucose by a fermentation method, or succinic acid, succinic anhydride, succinic acid ester, etc. obtained by the fermentation method May be hydrogenated with a reducing catalyst to be converted into a diol compound, or 1,4-butanediol may be produced from 1,3-butadiene obtained by fermentation.

A method for directly producing a diol from a carbon source by a fermentation method may be performed, for example, by the method described in JP-T 2010-521182. A method of hydrogenating succinic acid, succinic anhydride, succinic acid ester, etc. with a reduction catalyst to convert it into a diol compound may be carried out, for example, by the method described in JP-A-2008-101143.
Examples of the catalyst for hydrogenating succinic acid include Pd, Ru, Re, Rh, Ni, Cu, Co and compounds thereof. Specifically, Pd / Ag / Re, Ru / Ni / Co / ZnO, Cu / Zn oxide, Cu / Zn / Cr oxide, Ru / Re, Re / C, Ru / Sn, Ru / Pt / Sn , Pt / Re / alkali, Pt / Re, Pd / Co / Re, Cu / Si, Cu / Cr / Mn, ReO / CuO / ZnO, CuO / CrO, Pd / Re, Ni / Co, Pd / CuO / CrO ₃ , phosphoric acid Ru, Ni / Co, Co / Ru / Mn, Cu / Pd / KOH, Cu / Cr / Zn, and the like. Among these, Ru / Sn or Ru / Pt / Sn is preferable in terms of catalytic activity.

  Furthermore, a method for producing 1,4-BG from biomass resources by a combination with a known organic chemical catalytic reaction is also used. For example, when pentose is used as a biomass resource, a diol such as butanediol can be easily produced by a combination of a known dehydration reaction and catalytic reaction.

In the present invention, the pH of 1,4-BG supplied to the steam generator is 7.0 or more , and the lower limit is preferably 7.5, more preferably 8.0. The upper limit is preferably 11.0, more preferably 10.5. When the pH is less than the lower limit, the amount of THF in the condensate increases and the decompressor's ability to add reduced pressure tends to decrease. If it exceeds the upper limit, the color tone of the polyester using this condensate as a diol component tends to deteriorate. When the pH is within the range of the present application, even if the system is operated for a long period of time, it can be stably operated with little decrease in the ability to add reduced pressure, and a polyester having good quality can be obtained.

The pH of 1,4-BG supplied to the steam generator is adjusted by a method of adding an amine compound or amino alcohol to 1,4-BG, a method of passing 1,4-BG through an anion exchange resin, or a fermentation method. It can be performed by a method using the obtained 1,4-BG. The pH of 1,4-BG by fermentation is, for example, when hydrogenated succinic acid obtained by fermentation of biomass resources to obtain BG, its fermentation conditions, neutralization conditions with ammonia, and succinic acid crystallization conditions The amount of 1,4-BG obtained by hydrogenating succinic acid can be adjusted by the purification conditions including distillation. Also, when 1,4-BG is obtained directly by fermentation of biomass resources, it can be adjusted by the fermentation conditions, neutralization conditions with ammonia, purification conditions including distillation of the obtained 1,4-BG, and the like.

Examples of amine compounds include primary amines, secondary amines, and tertiary amines. Specifically, octylamine, nonylamine, 1-aminodecane, aniline, phenethylamine, dipentylamine, dihexylamine, diheptylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, dibutylamine, tributylamine, N
-Methylaniline, tributylamine, tripentylamine, N, N-dimethylaniline, dicyclohexylamine, 1,3-propanediamine, N, N-dimethyl-1,6-hexanediamine, N-butylpyrrole, N-butyl- 2,3-dihydropyrrole, N-butylpyrrolidine, 4-dimethylaminopyridine, 1,2,3,4-tetrahydroquinoline, 2,3-dihydro-1H-indole, 4-aminomethylpiperidine, 4-amino-5 , 6-Dihydro-2-methylpyrimidine, 2,3,5,6-tetramethylpyrazine, 3,6
-Dimethylpyridazine, among which tributylamine and N-butylpyrrolidine are preferably used.

Examples of amino alcohols include 4-amino-1-butanol, 2-amino-1-butanol, prolinol, ethanolamine, diethanolamine, triethanolamine, and prolinol. Among them, 4-amino-1-butanol and prolinol are preferable. Preferably used.
The anion exchange resin used in the present invention is not particularly limited, and those having a low degree of crosslinking and those having a high degree of crosslinking can be used. Moreover, any form of a gel type, a porous type, and a high porous type may be sufficient. Specifically, commercially available Diaion SA-10A, SA-12A, SA-11A, NSA100, SA-20A, SA-21A, PA306S, PA308, PA312, PA316, PA318L, PA408, PA412, PA418, HPA25 (Mitsubishi Chemical Co., Ltd.), or other grades of these products, but are not limited to these.

  The amount of nitrogen atoms contained in 1,4-BG is preferably 0.1 ppm to 150 ppm by weight, more preferably 0.1 ppm to 120 ppm, and still more preferably 0.8 ppm. 5 ppm to 100 ppm by weight. If the nitrogen atom is less than the lower limit, the amount of THF in the condensate increases and the decompressor's ability to add reduced pressure tends to decrease. If it exceeds the upper limit, the color tone of the polyester produced using this condensate as a diol component tends to deteriorate.

1,4-BG used as ejector driving steam can be prepared separately from 1,4-BG as a diol component of polyester, or a part of 1,4-BG as a diol component of polyester can be prepared. It can also be used as ejector driving steam.
FIG. 3 is an explanatory diagram of an example of the pressure reducing device.
In this description, an example in which there are three polycondensation reaction tanks from the first to the third tank will be described. The pressure in each of the polycondensation reaction tanks (a, d, k) is controlled by using the reduced pressure addition apparatus shown in FIG. In FIG. 3, 1,4-BG is continuously supplied to the 1,4-BG steam generator (K) for driving the ejector through an external supply line (19), and is generated by heating to 240 ° C. 1,4-BG vapor is fed through the supply line (20) to each ejector (for the first polycondensation reaction tank: A
1, A3, for second polycondensation reaction tank: B1, B3, B5, for third polycondensation reaction tank: C1, C3, C5).

A gas mainly composed of tetrahydrofuran and water distilled from the first polycondensation reaction tank (a) is introduced into the ejector (A1) via the line (21), and at this time, the gas discharged from the ejector (A1) 1, The 4-BG vapor is condensed in the barometric condenser (A2), and the condensate is collected in the hot well tank (H2) through the atmospheric leg (25). On the other hand, the component that is not condensed by the barometric condenser (A2) is sent to the second-stage ejector (A3), and the condensed liquid is collected in the hot well tank (H3) through the atmospheric leg (26). As in the first stage, components not condensed by the barometric condenser (A4) are discharged out of the system from the line (24) using the vacuum pump (A5). Lines (22, 23) are 1,4-BG supply lines, and the entire amount is circulated and supplied from hot well tanks (H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the second polycondensation reaction tank (d) is introduced into the ejector (B1) through the line (31), and is discharged from the ejector (B1) at this time. The 4-BG vapor is condensed in the barometric condenser (B2), and the condensate is collected in the hot well tank (H1) through the atmospheric leg (36). On the other hand, the components that are not condensed by the barometric condenser (B2) are sent to the second-stage ejector (B3), and the condensate is collected in the hot well tank (H2) through the atmospheric legs (37). In the same manner as in the first stage, the components not condensed by the barometric condenser (B4) were sent to the third stage ejector (B5), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (38). . As in the second stage, components not condensed by the barometric condenser (B6) were discharged out of the system from the line (35) using the vacuum pump (B7). The lines (32, 33, 34) are 1,4-BG supply lines, and the entire amount is circulated and supplied from the hot well tanks (H1, H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the third polycondensation reaction tank (k) is introduced into the ejector (C1) through the line (41), and is discharged from the ejector (C1) at this time. The 4-BG vapor is condensed in the barometric condenser (C2), and the condensate is collected in the hot well tank (H1) through the atmospheric leg (46). On the other hand, the component that has not been condensed by the barometric condenser (C2) is sent to the second-stage ejector (C3), and the condensed liquid is collected in the hot well tank (H2) through the atmospheric leg (47). As in the first stage, the components that have not been condensed by the barometric condenser (C4) are sent to the third stage ejector (C5), and the condensate is collected in the hot well tank (H3) through the atmospheric leg (48). As in the second stage, components not condensed by the barometric condenser (C6) are discharged out of the system from the line (45) using the vacuum pump (C7). Lines (42, 43, 44) are 1,4-BG supply lines, and the entire amount is circulated and supplied from hot well tanks (H1, H2, H3) (not shown).

The liquid consisting mainly of 1,4-BG collected in the hot well tanks (H1, H2, H3) is sent to the buffer tank (H5) through the line (54) and the pump (H4), and the whole amount is pumped. (H6), transferred to raw material slurry preparation tank as unpurified through line (55) and made part of polyester raw material diol. Lines (51, 52, 53) are supply lines from the outside of 1,4-BG to the hot well tanks (H1, H2, H3). In addition, the supply of 1,4-BG from the outside when the operation of the continuous polycondensation process is stable is only the line (19) and the lines (51, 52, 53), and each is set to a constant flow rate.

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 measurement method of the physical property and evaluation item which were employ | adopted in the following examples is as follows.
<THF generation amount in vacuum generator>
The 1,4-BG vapor vaporized in the vapor 1,4-BG supply line (20) to the ejector is collected in a SUS cylinder, cooled and condensed, and then used with a Shimadzu capillary gas chromatograph (GC-2025). The amount of THF generated was calculated. The column used was DB-1 from J & W (inner diameter: 0.25 mm, length: 30 m, membrane pressure: 1.0 μm). The temperature of the injection section and detector was 240 ° C., the column temperature was maintained at 50 ° C. for 7 minutes, and then the temperature was increased to 230 ° C. at 10 ° C./min. Nitrogen (100 kPa) was used as the carrier gas. As a method of quantitative analysis, a calibration curve was prepared in advance with an aqueous THF solution, and the amount of THF in 1,4-BG was derived from the Area value at the time of GC measurement.

<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), at 30 ° C., a concentration of 1.0 g / dL in the case of polybutylene terephthalate, and 0.5 g / in the case of polybutylene succinate. The falling seconds of only the dL polymer solution and the solvent were measured and determined from the following formula (1).

IV = ((1 + 4K _H η _sp ) ^0.5 −1) / (2K _H C) (1)
(Where η _SP = η / η ₀ −1, η is the polymer solution falling seconds, η ₀ is the solvent dropping seconds, C is the polymer solution concentration (g / dL), and K _H is the Huggins constant. is .K _H adopted the 0.33 in.)
<Terminal carboxyl group concentration>
After pulverizing the sample, the sample was dried at 140 ° C. for 15 minutes in the case of polybutylene terephthalate in a hot air dryer, 30 minutes at 60 ° C. in the case of polybutylene succinate, and cooled to room temperature in a desiccator. 0.1 g was precisely weighed and collected in a test tube, 3 ml of benzyl alcohol was added, dissolved in 195 ° C. for 3 minutes while blowing dry nitrogen gas, and then 5 ml of chloroform was gradually added and cooled to room temperature. One to two drops of phenol red indicator were added to this solution, and titrated with a 0.1N sodium hydroxide benzyl alcohol solution with stirring while blowing dry nitrogen gas, and the procedure was terminated when the color changed from yellow to red. Moreover, the same operation was implemented as a blank, without melt | dissolving a polyester resin sample, and the terminal carboxyl group amount (acid value) was computed by the following formula | equation (2).

Terminal carboxyl content (equivalent / ton) = (ab) × 0.1 × f / w (2)
(Where a is the amount of 0.1N sodium hydroxide in benzyl alcohol solution required for titration (μl), b is the amount of 0.1N sodium hydroxide in benzyl alcohol solution required for titration with a blank. The amount (μl), w is the amount of the polyester resin sample (g), and f is the titer of 0.1N sodium hydroxide in benzyl alcohol.)
In addition, the titer (f) of the benzyl alcohol solution of 0.1N sodium hydroxide was calculated | required with the following method. Collect 5 ml of methanol in a test tube, add 1 to 2 drops as an indicator of an ethanol solution of phenol red, titrate with 0.4 ml of 0.1 N sodium hydroxide in benzyl alcohol, then titrate to 0 with a known titer. 0.1 mL of 1N hydrochloric acid aqueous solution as a standard solution was collected and added, and again titrated with 0.1N sodium hydroxide in benzyl alcohol to the discoloration point (the above operation was performed while blowing dry nitrogen gas) .) The titer (f) was calculated by the following formula (3).

Titer (f) = Titer of 0.1N aqueous hydrochloric acid × Amount of collected 0.1N aqueous hydrochloric acid (μl) / Titration of 0.1N sodium hydroxide in benzyl alcohol (μl) (3)
<Pellet color>
A pellet-shaped polyester is filled in a cylindrical powder measuring 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 b value by the color coordinate of Hunter's color difference formula in the Lab display system described in Reference Example 1 of 0 was obtained as a simple average value of values measured by rotating the measurement cell by 90 degrees by the reflection method. .

<Solution haze>
After dissolving 2.70 g of PBT in 20 mL of a mixed solvent of phenol / tetrachloroethane = 3/2 (weight ratio) at 110 ° C. for 30 minutes, it was cooled in a constant temperature water bath at 30 ° C. for 15 minutes, and made by Nippon Denshoku Co., Ltd. The measurement was performed with a cell length of 10 mm using a dynamometer (NDH-300A). It shows that transparency is so favorable that a value is low.

<PH of 1,4-BG>
50 mL of 1,4-BG was sampled in a beaker and measured by immersing the pH electrode in the atmosphere using a pH-meter (HM-25R) manufactured by Toa DKK.
<Measurement method of nitrogen atom content (mass ppm) in 1,4-BG>
A sample of 15 mg was taken into a quartz boat, and the sample was burned using a trace total nitrogen analyzer (“TN-10 type” manufactured by Dia Instruments Co., Ltd.) and quantified by a combustion / chemiluminescence method. Moreover, the standard sample used in that case melt | dissolved aniline in toluene, and produced and used 0, 0.5, 1.0, 2.0 microgram / mL in conversion of nitrogen.

[Example 1]
<Manufacture of polybutylene terephthalate>
Polybutylene terephthalate was produced as follows using the esterification step shown in FIG. 1, the polycondensation step shown in FIG. 2, and the reduced pressure addition apparatus shown in FIG. 3.
First, a 60 ° C. slurry mixed at a ratio of 1.80 moles of 1,4-butanediol with respect to 1.00 moles of terephthalic acid is passed through a raw material supply line (1) from a slurry preparation tank in advance with an esterification rate of 99. % Was continuously fed to an esterification reaction tank (A) having a screw type stirrer filled with low molecular weight oligomers at a rate of 40 kg / h. At the same time, the bottom component of the rectification column (C) at 185 ° C. (98% by weight or more is 1,4-butanediol) is supplied at 13.2 kg / h from the recirculation line (2), and the recirculation line (2 The catalyst solution at 60 ° C. prepared in 3.0 wt% 1,4-butanediol solution was fed at 345 g / h from the catalyst feed line (3) connected to Tetra-n-butoxy titanate was used as the catalyst.

  The internal temperature of the reaction vessel (A) is 230 ° C., the pressure is 70 kPa, and the produced water, tetrahydrofuran and excess 1,4-butanediol are distilled from the distillation line (5), and the rectification column (C) It separated into a high boiling component and a low boiling component. The high-boiling component at the bottom of the column after the system has been stabilized is 98% by weight or more of 1,4-butanediol, and the extraction line (8) so that the liquid level of the rectifying column (C) is constant. A part of it was extracted outside. On the other hand, a low boiling component mainly composed of water and THF is extracted in the form of gas from the top of the column, condensed by a condenser (G), and an extraction line (13) so that the liquid level of the tank (F) becomes constant. More extracted outside.

  A certain amount of oligomer generated in the reaction tank (A) is extracted from the oligomer extraction line (4) using the extraction pump (B), and the average liquid in the reaction tank (A) in terms of terephthalic acid units. The liquid level was controlled so that the residence time was 3 hours. The oligomer extracted from the oligomer extraction line (4) was continuously supplied to the first polycondensation reaction tank (a). After the system was stabilized, the esterification rate of the oligomer collected at the outlet of the reaction vessel (A) was 97.5%.

  The internal temperature of the first polycondensation reaction tank (a) was 246 ° C., the pressure was 2.4 kPa, and the liquid level was controlled so that the residence time was 120 minutes. An initial polycondensation reaction was performed while extracting water, tetrahydrofuran, and 1,4-butanediol from a vent line (L2) connected to a decompressor (not shown). The extracted reaction liquid was continuously supplied to the second polycondensation reaction tank (d).

  The internal temperature of the second polycondensation reaction tank (d) was 239 ° C., the pressure was 150 Pa, the liquid level was controlled so that the residence time was 90 minutes, and a vent line (L4) connected to a decompressor (not shown). ), Polycondensation reaction was further carried out while extracting water, tetrahydrofuran and 1,4-butanediol. The obtained polymer was continuously supplied to the third polycondensation reaction tank (k) via the extraction line (L3) by the extraction gear pump (e). The internal temperature of the third polycondensation reaction tank (k) was 238 ° C., the pressure was 130 Pa, the residence time was 60 minutes, and the polycondensation reaction was further advanced. The obtained polymer was continuously extracted in a strand form from the die head (g) via the filter (U), and was cut with a rotary cutter (h). In addition, the pressure of each polycondensation reaction tank (a, d, k) was controlled using the reduced pressure addition apparatus shown in FIG.

  1,4-butanediol (pH = 9.3) prepared by adding 4-amino-1-butanol to 20 ppm by weight was used as the vapor for driving the ejector. The 1,4-butanediol is continuously supplied to a 1,4-butanediol steam generator (K) for driving an ejector through a supply line (19) and heated to 240 ° C. to generate 1,4-butane. Through the supply line (20), each ejector (for the first polycondensation reaction tank: A1, A3, for the second polycondensation reaction tank: B1, B3, B5, for the third polycondensation reaction tank: C1, C3)・ Supplied to C5). At this time, the amount of THF generated in the steam generator (K) was 2300 ppm by weight.

A gas mainly composed of tetrahydrofuran and water distilled from the first polycondensation reaction tank (a) is introduced into the ejector (A1) via the line (21), and at this time, the gas discharged from the ejector (A1) 1, 4-Butanediol vapor was condensed in a barometric condenser (A2), and the condensate was collected in a hot well tank (H2) through an atmospheric leg (25). On the other hand, the components that were not condensed by the barometric condenser (A2) were sent to the second-stage ejector (A3), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (26). As in the first stage, components not condensed by the barometric condenser (A4) were discharged out of the system from the line (24) using the vacuum pump (A5). Lines (22, 23) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the second polycondensation reaction tank (d) is introduced into the ejector (B1) through the line (31), and is discharged from the ejector (B1) at this time. 4-Butanediol vapor was condensed in a barometric condenser (B2), and the condensate was collected in a hot well tank (H1) through an atmospheric leg (36). On the other hand, the component that was not condensed by the barometric condenser (B2) was sent to the second-stage ejector (B3), and the condensate was collected in the hot well tank (H2) through the atmospheric leg (37). In the same manner as in the first stage, the components not condensed by the barometric condenser (B4) were sent to the third stage ejector (B5), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (38). . As in the second stage, components not condensed by the barometric condenser (B6) were discharged out of the system from the line (35) using the vacuum pump (B7). Lines (32, 33, 34) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H1, H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the third polycondensation reaction tank (k) is introduced into the ejector (C1) through the line (41), and is discharged from the ejector (C1) at this time. 4-Butanediol vapor was condensed in a barometric condenser (C2), and the condensate was collected in a hot well tank (H1) through an atmospheric leg (46). On the other hand, the component that was not condensed by the barometric condenser (C2) was sent to the second-stage ejector (C3), and the condensate was collected in the hot well tank (H2) through the atmospheric leg (47). As in the first stage, the components not condensed by the barometric condenser (C4) were sent to the third stage ejector (C5), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (48). . As in the second stage, components not condensed by the barometric condenser (C6) were discharged out of the system from the line (45) using the vacuum pump (C7). Lines (42, 43, 44) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H1, H2, H3) (not shown).

The liquid mainly composed of 1,4-butanediol collected in the hot well tanks (H1, H2, H3) is sent to the buffer tank (H5) through the line (54) and the pump (H4). Through the pump (H6) and the line (55), the raw material slurry was transferred to the raw material slurry preparation tank as it was unrefined and used as part of the polyester raw material diol.
Lines (51, 52, 53) are supply lines from the outside of 1,4-butanediol to the hot well tanks (H1, H2, H3), and 1 containing 20 mass ppm of 4-amino-1-butanol. , 4-butanediol solution was fed. In addition, the supply of the 1,4-butanediol solution from the outside at the time of stable operation of the continuous polycondensation process was the line (19) and the lines (51, 52, 53), and each was set to a constant flow rate.

Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.
[Example 2]
As in Example 1, except that 1,4-butanediol (pH = 10.8) prepared by adding 4-amino-1-butanol to 100 ppm by weight was used as the vapor for driving the ejector. Went to. The amount of THF generated in the steam generator (K) was 2300 ppm by weight, and the color tone of the polymer was good. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Example 3]
The same procedure as in Example 1 was performed except that 1,4-butanediol (pH = 8.9) prepared by adding tributylamine to 20 ppm by weight was used as the ejector driving vapor. The amount of THF generated in the steam generator (K) was 2600 ppm by weight, and the color tone of the polymer was good. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Example 4]
The same procedure as in Example 1 was performed except that 1,4-butanediol (pH = 10.7) prepared by adding tributylamine to 1000 ppm by weight was used as the ejector driving steam. The amount of THF generated in the steam generator (K) was 2100 ppm by weight. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Example 5]
The same procedure as in Example 1 was performed except that 1,4-butanediol (pH = 9.3) prepared by adding 2-prolinol to 20 ppm by weight was used as the ejector driving steam. . The amount of THF generated in the steam generator (K) was 2200 ppm by weight, and the color tone of the polymer was good. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that a commercially available 1,4-butanediol (pH = 5.2) was used as the ejector driving vapor. The amount of THF generated in the steam generator (K) was as high as 4900 ppm by weight. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Comparative Example 2]
As in Example 1, except that 1,4-butanediol (pH = 11.9) prepared by adding 4-amino-1-butanol to 1000 ppm by weight was used as the vapor for driving the ejector. Went to. The amount of THF generated in the steam generator (K) was as small as 2100 ppm by weight, but the color of the polymer deteriorated. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Comparative Example 3]
The same procedure as in Example 1 was performed except that 1,4-butanediol (pH = 5.5) prepared by adding 2-pyrrolidone to 20 ppm by weight was used as the ejector driving vapor. The amount of THF generated in the steam generator (K) was 3800 ppm by weight, but the color tone of the polymer deteriorated. Table 1 shows the quality evaluation results of the polyester pellets one week after the start of operation.

[Example 6]
<Preparation of polymerization catalyst>
Into a glass eggplant-shaped flask equipped with a stirrer, 100 parts by mass of magnesium acetate tetrahydrate was added, and 1500 parts by mass of absolute ethanol (purity 99% by mass or more) was further added. Furthermore, 65.3 parts by mass of ethyl acid phosphate (mixing mass ratio of monoester and diester was 45:55) was added and stirred at 23 ° C. After confirming that magnesium acetate was completely dissolved after 15 minutes, 122 parts by mass of tetra-n-butyl titanate was added. Stirring was further continued for 10 minutes to obtain a uniform mixed solution. This mixed solution was transferred to an eggplant-shaped flask and concentrated under reduced pressure by an evaporator in an oil bath at 60 ° C. After 1 hour, most of ethanol was distilled off to obtain a translucent viscous liquid. The temperature of the oil bath was further raised to 80 ° C., and further concentrated under a reduced pressure of 5 Torr to obtain a viscous liquid. This liquid catalyst was dissolved in 1,4-butanediol to prepare a titanium atom content of 3.36% by mass. The storage stability of this catalyst solution in 1,4-butanediol was good, and no precipitate was observed in the catalyst solution stored at 40 ° C. in a nitrogen atmosphere for at least 40 days. The catalyst solution had a pH of 6.3.

<Production of polybutylene succinate>
A polybutylene succinate was produced in the following manner using the esterification step shown in FIG. 1, the polycondensation step shown in FIG. 2, and the reduced pressure addition apparatus shown in FIG. First, with respect to 1.00 mol of succinic acid containing 0.18% by weight of malic acid, 1.30 mol of 1,4-butanediol and malic acid were mixed at a total amount of 0.0033 mol. An esterification reaction tank having a stirrer filled with a low molecular weight oligomer having an esterification rate of 99% by weight in a nitrogen atmosphere in advance from a slurry preparation tank (not shown) through a raw material supply line (1). A) was continuously supplied to 45.5 kg / h.

  The esterification reaction tank (A) is set to an internal temperature of 230 ° C. and a pressure of 101 kPa, and water, tetrahydrofuran and excess 1,4-butanediol produced are distilled from the distillation line (5), and a rectifying column (C) It separated into a high boiling component and a low boiling component. A part of the high-boiling component at the bottom of the column after the system was stabilized was extracted to the outside through an extraction line (8) so that the liquid level of the rectification column (C) was constant. On the other hand, a low boiling component mainly composed of water and tetrahydrofuran is extracted from the top of the tower in the form of gas, condensed in a condenser (G), and the extraction line (13) so that the liquid level in the tank (F) becomes constant. ) Extracted outside. At the same time, the total amount of the bottom component (98% by weight or more of 1,4-butanediol) of the rectification column (C) at 100 ° C. from the recirculation line (2) is esterified from the catalyst supply line (3). Tetrahydrofuran generated in the reaction tank and equimolar 1,4-butanediol were supplied together, and the molar ratio of 1,4-butanediol to succinic acid in the esterification reaction tank was adjusted to 1.30. The supply amount of the recirculation line (2) and the catalyst supply line (3) was 3.8 kg / h.

  The esterification reaction product produced in the esterification reaction tank (A) is continuously extracted from the esterification reaction product extraction line (4) using the pump (B), and the liquid in the esterification reaction tank (A). The liquid level was controlled so that the average residence time in terms of succinic acid unit was 3 hours. The esterification reaction product extracted from the extraction line (4) was continuously supplied to the first polycondensation reaction tank (a). After the system was stabilized, the esterification rate of the esterification reaction product collected at the outlet of the esterification reaction tank (A) was 92.4%, and the terminal carboxyl concentration was 884 equivalents / ton.

  After preparing the catalyst solution prepared in advance by the above-mentioned method in a catalyst preparation tank so that the concentration as titanium atoms is 0.12 wt%, the catalyst solution is diluted with 1,4-butanediol, Through L8), the esterification reaction product was continuously fed to the extraction line (4) at 1.4 kg / h (the catalyst was added to the liquid phase of the reaction solution). The supply was stable during the operation period.

  The internal temperature of the first polycondensation reaction tank (a) was 240 ° C., the pressure was 2.7 kPa, and the liquid level was controlled so that the residence time was 120 minutes. An initial polycondensation reaction was performed while extracting water, tetrahydrofuran, and 1,4-butanediol from a vent line (L2) connected to a decompressor (not shown). The extracted reaction liquid was continuously supplied to the second polycondensation reaction tank (d).

  The second polycondensation reaction tank (d) has an internal temperature of 245 ° C., a pressure of 400 Pa, liquid level control so that the residence time is 150 minutes, and a vent line (not shown) connected to a decompressor (not shown). The polycondensation reaction was further advanced while extracting water, tetrahydrofuran and 1,4-butanediol from L4). The obtained polyester was continuously supplied to the third polycondensation reaction tank (k) via the extraction line (L3) by the extraction gear pump (e). The internal temperature of the third polycondensation reaction tank (k) was 245 ° C., the pressure was 130 Pa, the residence time was 180 minutes, and the polycondensation reaction was further advanced. The obtained polyester was continuously extracted in the form of a strand from the die head (g) and cut with a rotary cutter (h) to obtain pellets.

In addition, the pressure of each polycondensation reaction tank (a, d, k) was controlled using the reduced pressure addition apparatus shown in FIG.
1,4-butanediol (pH = 9.3) prepared by adding 4-amino-1-butanol to 20 ppm by weight was used as the vapor for driving the ejector. The 1,4-butanediol solution is continuously supplied through a supply line (19) to a 1,4-butanediol vapor generator (K) for driving the ejector, and heated to 240 ° C. to generate 1,4-butanediol. Butanediol vapor is fed through a supply line (20) to each ejector (for the first polycondensation reaction tank: A1, A3, for the second polycondensation reaction tank: B1, B3, B5, for the third polycondensation reaction tank: C1, C3 ・ C5
). At this time, the amount of THF generated in the steam generator (K) was 2300 ppm by weight.

A gas mainly composed of tetrahydrofuran and water distilled from the first polycondensation reaction tank (a) is introduced into the ejector (A1) via the line (21), and at this time, the gas discharged from the ejector (A1) 1, 4-Butanediol vapor was condensed in a barometric condenser (A2), and the condensate was collected in a hot well tank (H2) through an atmospheric leg (25). On the other hand, the components that were not condensed by the barometric condenser (A2) were sent to the second-stage ejector (A3), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (26). As in the first stage, components not condensed by the barometric condenser (A4) were discharged out of the system from the line (24) using the vacuum pump (A5). Lines (22, 23) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the second polycondensation reaction tank (d) is introduced into the ejector (B1) through the line (31), and is discharged from the ejector (B1) at this time. 4-Butanediol vapor was condensed in a barometric condenser (B2), and the condensate was collected in a hot well tank (H1) through an atmospheric leg (36). On the other hand, the component that was not condensed by the barometric condenser (B2) was sent to the second-stage ejector (B3), and the condensate was collected in the hot well tank (H2) through the atmospheric leg (37). In the same manner as in the first stage, the components not condensed by the barometric condenser (B4) were sent to the third stage ejector (B5), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (38). . As in the second stage, components not condensed by the barometric condenser (B6) were discharged out of the system from the line (35) using the vacuum pump (B7). Lines (32, 33, 34) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H1, H2, H3) (not shown).

A gas mainly composed of tetrahydrofuran and water distilled from the third polycondensation reaction tank (k) is introduced into the ejector (C1) through the line (41), and is discharged from the ejector (C1) at this time. 4-Butanediol vapor was condensed in a barometric condenser (C2), and the condensate was collected in a hot well tank (H1) through an atmospheric leg (46). On the other hand, the component that was not condensed by the barometric condenser (C2) was sent to the second-stage ejector (C3), and the condensate was collected in the hot well tank (H2) through the atmospheric leg (47). As in the first stage, the components not condensed by the barometric condenser (C4) were sent to the third stage ejector (C5), and the condensate was collected in the hot well tank (H3) through the atmospheric leg (48). . As in the second stage, components not condensed by the barometric condenser (C6) were discharged out of the system from the line (45) using the vacuum pump (C7). Lines (42, 43, 44) were 1,4-butanediol supply lines, and the entire amount was circulated and supplied from hot well tanks (H1, H2, H3) (not shown).

The liquid mainly composed of 1,4-butanediol collected in the hot well tanks (H1, H2, H3) is sent to the buffer tank (H5) through the line (54) and the pump (H4). Through the pump (H6) and the line (55), the raw material slurry was transferred to the raw material slurry preparation tank as it was unrefined and used as part of the polyester raw material diol.
Lines (51, 52, 53) are supply lines from the outside of 1,4-butanediol to hot well tanks (H1, H2, H3), and 1 containing 20 ppm by weight of 4-amino-1-butanol. , 4-butanediol solution was fed. In addition, the supply of the 1,4-butanediol solution from the outside at the time of stable operation of the continuous polycondensation process was only the line (19) and the lines (51, 52, 53), and each was set to a constant flow rate.

Table 2 shows the quality evaluation results of the polyester pellets one week after the start of operation.
[Comparative Example 4]
The same procedure as in Example 6 was performed except that a commercially available 1,4-butanediol (pH = 5.2) was used as the ejector driving vapor. The amount of THF generated in the steam generator (K) was as high as 4900 ppm by weight. Table 2 shows the quality evaluation results of the polyester pellets one week after the start of operation.

  The process for producing the polyester of the present invention is less efficient in conversion to THF. Moreover, the polyester obtained by the production method of the present invention has a good color tone, and further contributes to effective utilization of biomass resources.

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 Capacitor Condensate Line 11 Extraction Line 12 Circulation Line 13 Extraction line 14 Vent line 15 Catalyst supply line 16 Catalyst supply line 19, 51, 52, 53 External 1,4-butanediol supply line 20 Steam 1,4-BG supply line 21 to ejector 21 First Vent line 31 from the polycondensation reaction tank Vent line 41 from the second polycondensation reaction tank Vent lines 22, 23, 32, 33, 34, 42, 43, 44 1,4-BG from the third polycondensation reaction tank Supply lines 24, 35, 45 Discharge gas lines 25, 26, 36, 37, 38, 46, 47, 48 bar from the vacuum pump Metric condenser atmospheric leg 54 Extraction line of condensate from hot well tank to buffer tank 55 Supply line of 1,4-BG from buffer tank to raw slurry preparation tank 56 1,4 from buffer tank to distillation purification tower -BG supply line 57 Low-boiling component extraction line 58 1,4-BG supply line 59 from the distillation purification tower to the raw slurry preparation tank 59 High-boiling component extraction line A Reaction tank B Extraction pump C Rectification tower D , E Pump F Tank G Capacitors L1, L3 Extraction lines L2, L4, L6: Vent line L5 Polymer extraction line L8 1,4-butanediol supply line L7 Metal compound supply line a First first polycondensation reaction tank d Second Polycondensation reaction tank k Third polycondensation reaction tank c, e, m Gear pump for extraction g Die head h times Rolling cutter R, S, T, U Filter A1, A3, B1, B3, B5, C1, C3, C5 Ejector A2, A4, B2, B4, B6, C2, C4, C6 Barometric capacitors A5, B7, C7 Vacuum pump H1, H2, H3 Hot well tank H4, H6, J2, J4 Pump H5 Buffer tank J1 Distillation purification tower J3 Distillation purification tower reboiler K Ejector drive 1,4-butanediol steam generator

Claims (4)

In a method for continuously producing a polyester by subjecting a diol component mainly composed of 1,4-butanediol and a dicarboxylic acid component to an esterification reaction and / or a transesterification reaction, and a polycondensation reaction,
(A) performing a polycondensation reaction under reduced pressure;
(B) The reduced pressure addition device comprises a 1,4-butanediol vapor ejector,
(C) 1,4-butanediol used in the steam ejector is condensed and then used as a diol component, and (d) 1,4-butanediol is supplied to a steam generator for driving the steam ejector. pH is 7.0 or more and 11.0 or less,
A process for producing polyester, characterized in that   The 1,4-butanediol supplied to the steam generator for driving the steam ejector contains a nitrogen compound of 0.1 to 150 ppm by weight as a nitrogen atom. Manufacturing method.   The 1,4-butanediol supplied to the steam generator for driving the steam ejector contains a nitrogen compound, and the nitrogen compound is an amine compound and / or an amino alcohol compound. 2. The production method according to 2.   The method according to any one of claims 1 to 3, wherein the 1,4-butanediol is derived from a biomass resource.

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