DE2030365A1 - Process for the production of polyethylene terephthalate - Google Patents

Description

B? Io? Itätt 19.6.1969

The invention is directed to a manufacturing process Polyethylene terephthalic acid directly from icrephthalic acid and ethylene

The result is particularly a process for the production of polyethylene terephthalate directly, terephthalic acid and ethylene glycol, which is then carried out when terephthalic acid, ethylene glycol and a catalytic amount of antimony pentoxide are heated to a moderate level of temperature. the pressure on tmteratinosphärisehen pressure verringertf wherein one of at least 260 ⁰ O maintains the temperature of j and separating Polyäthylenterephthalst ,.

The Äntimonpentoxidkatalysötorea of the present invention contemplate also, the radioactive isotopes of antimony and the "radio = active isotopes of oxygen, the Halbv / ertzeiten of less than 35 minutes besitaen ₀

Before that, polyethylene terephthalate would normally not go through direct esterification of 1thyXenglykol Bit ierephthalaöiare her " rather than being estersed by transesterification of terephthalate

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lower aliphatic alcohols (usually dei * Diaie thy! ester) by means of ethylene glycol,

Polyethylene terephthalate is manufactured in the manner by a abließen Bsteraustauachreaktion between dimethyl terephthalate and Ithylenglykol * piping preparation is carried out in two stages, The first stage consists of a Esteraustauschreaktion "wipe .and ethylene glycol dimethyl terephthalate" wherein Kis-FSS hydroxyätbyl} ~ terephthalate sad methanol arises _n Then, in the second stage _5, the polymerization stage _? the bis (ß-hydroxyethyl) terephthalate polymerizes with elimination of ethylene glycol, which under these conditions volatilizes and is removed from the system.

The aim of the invention is to provide a straightforward method for rapid Manufacture of polyethylene terephthalate aas terephthalic acid and ethylene glycol.,

It is another object of the invention to provide a catalyst for the production of Polyäthylentereplitliaiat aa sehaffen, der hydrolytically stable, soluble in ethylene glycol and highly reactive »· is capable of nationals "

Ea has unexpectedly been found Magi ~ * äass ₅ when the reaction see Katalytic of ithylenglykol and terephthalic acid at a temperature above 26o ° C and under xunächst aberatmosphärischea pressure and then under sub-atmospheric pressure in the presence of an amount of antimony pentoxide is executed, a continuous process but rapid .Polymerization of ethylene terephthalic acid can be realized>

One advantage of the method according to the invention results from the discovery9 that the presence of antimony pentoxide in Polymerization system allows continuous operation «, which brings fewer AHfreepreservation problems with it .. One The advantage of the invention is that it operates continuously

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wherein the EBteraustajAsch _ß the polymer! sation product of the dee Esteraustausche and the subsequent production of fibers or films running fcoatinuierlieh wirdW

The catalyst according to the invention is soluble in catalytic amounts in ethylene glycol * that is, in amounts up to "1 ^ based on the weight of the terephthalic acid-> The catalyst according to the invention is soluble ^{in hot ethylene glycol at temperatures up to 20O 0 C. The catalyst according to the invention is} generally referred to as a homogeneous catalyst> because it is soluble in ethylene glycol and thus results in a homogeneous system * which is in contrast to a heterogeneous system in which the catalyst is not * soluble in ethylene glycol

_S when terephthalic acid visionaries with Ithylenglykol under öberatmosphäri · "but reacted pressure at the normal boiling point of ethylene glycol then a Yeresterungspro- 'obtained domestic product having the properties for the subsequent polycondensation reaction gewönsehten" The catalyst of the invention is Torliegenden hydrolytically stable "the , can be given before the reaction of ethylene glycol with terephthalic acid. The polyester beige produced thereby have a better color and a higher softening point and contain a smaller amount of polyglycol ether units than if the reaction is carried out without the catalyst according to the invention * .- ^: - "\ - .. * ■ .- ■■. ■■■ -

The terephthalic acid / jithyleneglycol heat is used with the subsequent polycondensation that occurs at a higher temperature running is "integrated" and in fact there are none Ethylene glycol terephthalate ester separated or purified ο The integration of the esterification and the polycondensation has the consequence, that the purity of the used in the invention Terephthalic acid is important

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The direct esterification of the present invention is carried out at dadnreh "that one in. ' a reaction vessel-? In which the reactants can be stirred - like water from the roakt: Sotisgeffilsch can be separated from 1 to 1 mole of glycetylteol per mole of terephthalic acid, a highly purified terephthalic acid, ano a catalytic . © Antiaonpentoxid einbringt- the .Luft is removed, for example by flushing with nitrogen or with ¹ eineiß other sauerstoffreiän inerten- {ras Before EraitsiMig to reaction "temperst κι" is a inertea sa ".erstof free G-as _i; vorisuigsweise Nitrogen ... up to a pressure of; I to 10 at * ^: - introduced-, The mixture of glycol, trephthalgic and catalyst is then brought to a temperature above the level of the temperature Ethyl onglycol and iswar before a agswei.se. 50 to 100 ⁰ O above the normal boiling point τοα Ithylenglykal- heated ,.

In the part of the reaction is carried out at the pressure _v iiberstmospLi & risohera ,, karm the temperature .of about 285 · 260TbIs ungeführ ⁿ C vary, it is - understood, -dasß temperatures up to 385 ⁰ O au used in the Hochdruokstüife can be ,, if entapr-echend high. Thicknesses are suitable - In the preferred temperature range mentioned, the preferred pressure is about! 5 _r '5 ab.- Higher pressures can also be used, in general the pressure will be: ■ kept as low as possible as it appears with the desired temperature agree läast. The applied part is direct response ^ hei de "high pressure xvirä _s under an atmosphere -inerten executed" nitrogen and other inert Öaae serve as suitable inert Atmosphtlrtm ·. -

I> ae MoJverholtniß of ethylene glycol to terephthalic acid can in the range of;.: J to 15: t. At a given temperature, a limgevi reaction is usually used with a low (rlvkoJverhSltn.tB geöi'beifcet> ura the removal of excess igen Gljkol after the HoeMrücfcainife

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■ BATH "

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avoid "It's usually more economical." with a

"to work In the present continuous process, the by-products ^ water and some Ithyleaglykol removed during the course of the reaction Ό The removal of the water kaan continuously or intermittently The Indian high pressure stage erfolgenο product formed is the new inventive catalyst polymerisiertο directly without Eeinigung by the ttbliehen methods causes “Whether it is added now before or after the high pressure stage _? a catalysis of the polymerisation during the low back pressure. The separation of water from the esterification reaction mixture can take place via a laterally connected sensor and a receptacle, both of which are kept under the heating pressure, for example 3 _e 5 at.,

During the BAW at low pressure _e at vacuum ausgefÖhrten portion of the reaction "ie during the polymerization" - the pressure is stufet reduced in the autoclave, and ethylene glycol is separated ^ has been until a polymer with the desired molecular weight obtained '"■ The temperature can be raised during the polymerization in order to increase the rate of polymerization and to maintain a molten system. Temperatures in the range of 260 to 300 ° C and drafts below 10 mm Hg are suitable. It is preferred in the polymerization _f Temperaturein of about 280 ⁰ O and water to a vacuum of less than 5 ram Hg

.If for optimal results. That 'polymerization * · reaction generally at a pressure of less than 1 mm Hg and usually from O ₉ 5 mm Hg executed verriagerte The pressure forces, "m the free Äthyleaglykol formed during the Polymerisationereaktion remove _Λ is Ithylenglykol volatilized under these conditions and removed from the system, In general, the lower the temperature, the longer the time the bia. ssur termination of the polymörieatioa required iat. ..- ■ · .- ■■. . ■ ^; '. ■, /. ■■

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In. a continuous V-erfaferen gives the solid product of direct esterification of an acceptable f aserbildendeji and film forming polyester of light Parbe ₈ when erhitst 760 on Hg to 100 on Hg * while "worn whose ■ non-umgesetstee diol in bucket temperature -normal - Si © «- -. depunkt the diol to below the temperat _lis in the Polykon""densation to be executed is -abdestilliert, the Tem ~ temperature _s in the Btieht-mBgeeet & te diol distilled off 'is wirdρ not critical, ? but it should result in as quick * separation -, - of the diol as possible without excess foaming, and without entrainment of foam in the vapors * -. It will be before "; In addition, you increase the pressure and gradually reduce the pressure, so that during the removal of the diol the equipment can be heated to the conditions of polycondensation. Is it advantageous? use an inert, oxygen-free purge gas % u ; at- . playing, by maa nitrogen, the mixture hinäurchbla * »- een _c wherein at least part of the non-umgesetsten diol estfermt wird- If fortaehreitety.dann the polycondensation, the mixture becomes more and more viakoee _o Therefore, should the Hlihren the viscous mixtures violently .erfolgen - ₉ to the separation of the cleaved diol facilitate au, Ea is also beneficial _tf dlinne Pilme the viscous mixtures-s * u-.erhitzen * "to ensure the rapid diffusion of the diol by more and more vis · = -.. expectant kose Plössigkeit If the polyester has reached the desired viscosity / then the polyester can be extruded j) quenched and cut into Sehnit & el or extruded through spinnerets or through a film-making nozzle.

A light polyester, such as a white polyester, for example -, can be obtained by not converting it Diol removed from the helsseu direct esterification product, This can be done laterally in the same reaction vessel connected condenser or in a separate container - It is desirable to use the hot esterification product -keep in an oxygen-free atmosphere while doing this

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one removes water \ m <i non-irradiating diol-:

When erf indungsgemässen kontimii he borrowed X'olyiaerisationsYer · "take the time sur" producing Polyäthyleate "rephthaXat iet needed is '', substantially less than that _for the for those separation by EsteratistauscEver-drive required IAT The Hoehdracfcfcondensation requires generally, about 60 minutes while the Hiederäruckpolymerisation _g in approximately 2 to 3 Standen -attend e _"f Although the anmeldungBgemässe method is particularly useful in to continual-Wichen Darchführungsweißes but the" -Verfahren- can werden- interrupted at any stage, and continued later the retracts, is flexibel- 2war dictate the operating conditions a Höohdruckzyfcrliis- and a NiederdruckEyklus, but the condensate "■ organization '." ad polymerization do not have to individually ausgeführt.wex'den ^, that _is? it is not necessary that a step finished iet ₉ before the next one is begun, - as - this is the case with procedures of the Pal,} with those, an ester branch also he »follows-

Polymers produced by the ar-fxndangageraasse process can be converted into molded objects using conventional spinning and gritting processes, such as films, ribbons, fibers, bristles and the like Usual way of making ions>woven; and non-woven fabrics _? Paperea <_; Leather equipment -Ilen and other structures can be used-

The following examples illustrate the present invention and its advantages.- It should be noted, that this Example © is to be understood as illustrative and not restrictive Unless otherwise stated, all refer to ■ Details of parts and percentages on the weight.

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EXAMPLE ·. ^.

This example illustrates the direct process βατ production of polyethylene terephthalate from terephthalic acid and ethylene glycol. At the high pressure stage, 20 _? O grams of terephthalic acid and 22.0 grams of ethylene glycol la a gerttbr *. th autoclave introduced the warο immersed ia an oil bath at a temperature of 256 ⁰ C. The autogenous pressure of the system was 5 _C 3 at "consisted The atmosphere aas nitrogen ·," The Ölbadtemperatür was in paragraphs for a period of 60 minutes to 204 ⁰ G. - The water formed during the reaction and the excess "&ly-teol" were continuously distilled off under atmospheric pressure.

The produced in this way were in the presence of Gljkolester OpOi grams Antiraonpentoxiö at 282 * · 0 MilllBieter under a vacuum of approximately O _V .1O Hg for a period of l min iO ^r _f polycondensed to Poiyäthylente · * rephthaiat herzustelleüs having a TiskositMt, Saehl von -O ₉ "14 and an ecrli color showed. The fiber obtained had a good cold-stretchability-v

EXAMPLE 2

The procedure of Example ϊ was repeated "with the difference that the feed to the reactor consisted of 20 ^ 0 grams of terephthalic acid and 22 ^ 0 grams of ethylene glycol. After the water formed during the esterification had been separated off, the reactor Q supplied etat "010 grams of antimony pentoxide, the temperature of the oil bath was initially 258 ⁰ C during the condensation reaction and · was then increased to 28O ⁰ C, -The in the system during the Glykolkondenaation present autogenous pressure draw-3 ₁ .5'at ν and the polycondensation of Ithylenglykolterephthalat was stirred under vacuum toe O / LO mm Hg for 150 carried out at 280 ⁰ C for min ,. '.A from the' product produced Polyäthyleaterephthalatfaser the aeigte

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. - ■■■■■■

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Viscosity from OsTO ₉ after grinding an ecru color and good clay

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Claims (1)

ίο -. : Patent claims 1, - Process aar Manufacture iron. "Folyätbjplenterephthalat directly from terephthalic acid and ethylene glycol * characterized by the fact that maia terephthalic acid and itfaylene glycol in the presence of a catalytic oleosage of antimony pentophthalate * allowed above atmospheric pressure to a temperature of at least . _:: - "'. 2 & Λΐ heated; Deia pressure-on lanter atmospheric pressure lowers a while aaa maintains the temperature of "at least" ... 260 ⁰ C and polyethylene terephthalate gains0 2 η process kut production of high polymerism Polyäthy «·" lenterephthalat »äadaroh g3kennseiehne.t ₉ that uerephthalic acid. _ * Is reacted with ethylene glycol mad the resalting ethylene-» lenglykolterephthalat in the presence of a catalytic amount ■: Antimony pentoxide is polymerized.,; 3η method for producing a fadem- and filwbii-! - denden polyethylene terephthalate ■, thereby gekennas-elohne.t '».. that ethylene glycol tiater ester interchange conditions with Terephthalic acid is converted and the resulting lthy *> lenglycol terephthalate in the presence of a catalytic amount Antimony pentoxide is polymerized " 4. Experienced for the production of a fiber-forming polyethylene terephthalate5 by this means that the condensate is heated to a temperature between about 220 and 300 ⁰ C and under a pressure of about 500 mm Hg in the presence of a catalytic amount of antiriron pentosM ₄ that is obtained through rhitaen for at least about 15 minutes of a mixture of ethylene glycol and - 'terephthalic acid in an oil ratio of glycol-Bu acid of about -Xsl to. 15: 1 at a temperature between: approx. £ 30 βηα. '? 85 ° 0 under a pressure. Which is at least autogenous _f , has been obtained., / 011 Q MMIM.H. NNCnLMPlHN *. H. · ΟΗ « BAD ORfGJNAL