DE1939923A1 - Process for the production of high molecular weight polyesters - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG 1939923

Our reference: O.Z. 25 843 Möb / Stä 6700 Ludwigshafen, August 5, 1969

Process for the production of high molecular weight polyesters

The invention relates to a method for the production of high molecular weight linear polyesters using germanium compounds as polycondensation catalysts.

It is. known to produce linear high molecular weight polyesters by that dicarboxylic acids or suitable derivatives thereof are reacted with bifunctional alcohols. The technical production of the polyester is generally carried out in two stages. In the first stage, a suitable intermediate is first made produced, which is polycondensed in the second stage. For example, in the manufacture of polyethylene glycol terephthalate, which has achieved the greatest technical importance, in the first stage, dimethyl terephthalate with ethylene glycol to bis-hydroxyethyl terephthalate or its oligomeric precondensation products implemented. But it can also, provided that a terephthalic acid of sufficient purity is available, the dimethyl ester can be replaced by terephthalic acid. That so formed bis-hydroxy ^ äthyl-terephthalat is then in the second stage condenses to form high molecular weight polyethylene glycol terephthalate, using high temperatures and low pressure will. This polymer product is a valuable starting product for fibers, threads and films. To accelerate the polycondensation reaction it is necessary to apply a catalyst. Many catalysts have been proposed for this purpose, e.g. antimony compounds, zinc compounds or titanium compounds. However, they all have certain disadvantages. So z. B. when using antimony compounds in the course of the polycondensation a partial reduction to metallic antimony, so that the condensates have a gray tinge and may contain agglomerates that cause problems during spinning and stretching. This disadvantage becomes particularly significant in the case of polyester material which is used for photographic purposes, for example when using polyester films as a base for light-sensitive layers. In a catalysis

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with zinc compounds, the thermal stability generally suffers the polyester melt and decomposition reactions occur to a large extent on. The use of titanium compounds leads to yellowish colored products.

It has also been proposed to use germanium or certain germanium compounds as condensation catalysts. For example, US Pat. No. 2,578,660 describes the use of germanium or germanium oxide. In the Belgian patent specification 659 3 ^ 1 the use of amorphous germanium dioxide is claimed. The disadvantage here is that work has to be carried out in a heterogeneous phase. In the German patent specification 1 216 5 * 14 are used as fc catalysts germanium alkoxides, especially germanium tetraethylate, suggested. However, these germanium compounds are difficult to manufacture. The use of the mentioned germanium compounds It generally leads to products that have a better color quality than those made with antimony catalysts exhibit. However, the disadvantage is a low melting point and a reduced lightfastness of the condensates, which by a higher diglycol content in the polyester.

The object of the present invention is to provide a simple method for the production of colorless linear polyesters, which at the same time have improved lightfastness, the catalyst is in a homogeneous phase. These and other objects which follow from the P are achieved by the invention.

The invention relates to a method for producing linear Polyester by polycondensation of bis-glycol esters of organic Dicarboxylic acids or their low molecular weight precondensates using nitrogen-containing germanium compounds as Polycondensation catalysts, using germanium compounds are made by dissolving germanium dioxide in water under the action of volatile monoamines with aliphatic or cycloaliphatic radicals have been obtained.

The germanium compounds used according to the invention can be prepared as follows:.

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Generally, amorphous germanium dioxide is added to a mixture of water and volatile organic monoamine. With movement, such as stirring or shaking, the germanium dioxide dissolves. It has been shown that the crystalline germanium dioxide can also be dissolved in the mixture of water and amine without difficulty. The reaction temperature is generally between the solidification point and the boiling point of the mixture, preferably at temperatures between 0 and 100 ^° C., in particular between 20 and 100 ^° C. Occasionally, it can be advantageous to use higher temperatures at excess pressure.

The volatile monoamines with aliphatic or cycloaliphatic radicals on the nitrogen atom can be primary, secondary or tertiary amines. The radicals on the nitrogen atom can be identical or different. In particular, aliphatic straight-chain or branched radicals with 1 to 10, in particular 1 to 6 carbon atoms or cycloaliphatic radicals with 3 to 8, in particular 3 to 6 carbon atoms in the ring are suitable. The residues on the nitrogen can close together. Be connected to the ring. It is favorable if the monoamines have a boiling point which is below or near the boiling point of the glycols used for polyester production. In this way, removal of excess or liberated monoamines is readily possible during the polycondensation. In general, volatile monoamines are used up to a boiling point of approx. 250 ° C., in particular approx. 230 ° C., at 760 mm Hg ¹ . It goes without saying that bases are chosen which do not decompose with discoloration at the polycondensation temperatures used.

Examples of suitable monoamines are those with straight-chain or branched alkyl radicals with 1 to 10, in particular 1 to 6, carbon atoms, or with cycloalkyl radicals having 3 to 8, in particular 3 to 6 carbon atoms in the ring, or monoamines in which the aliphatic radicals on the nitrogen atom with one another to form a ring, for example a five- or six-membered ring, if appropriate via oxygen. Examples include: methylamine, ethylamine, iso-propylamine, n-butylamine, diethylamine, Trimethylamine, triethylamine, diisopropylamine, diisobutylamine, n-hexylamine, n-octylamine, cyclohexylamine, cyclooctylamine, Ν, Ν-dimethylcyclohexylamine, dicyclohexylamine, also

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BAa ORlGINAL

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"Pyrrolidine, piperidine or morpholine. Mixtures can also be used of bases in question.

The amount of organic base required to dissolve the germanium dioxide depends on the type of basic nitrogen compound used and can easily be determined by simple preliminary tests. The dissolution of the initially sparingly soluble germanium dioxide in the aqueous reaction medium can easily be followed. An excess of base can be used without further ado: If the base is poorly soluble in water, the excess can easily be separated off after the reaction, otherwise an excess of base can be removed during the subsequent polycondensation with the ψ glycol released. In general, the molar ratio of base to germanium dioxide is between 0.3 and 100, in particular between 0.4 and 10.

The proportion of germanium dioxide to water is generally between 10:90 and 50:50 it is possible to use solubilizers, for example such glycols as are used for the production of linear polyesters, to use for the conversion of organic base with germanium dioxide in addition to water. In general, it may be appropriate to to 50 wt.? of the water can be replaced by the solubilizers.

If the concentrated aqueous solutions of Germaniumverbin- obtained w fertilize a, one obtains colorless salt-like germanium compounds, which can then be redissolved in water or glycols. The ratio of nitrogen to germanium content indicates that salts of germanium acids or germanitun polyacids with the bases used are present here.

As bis-glycol esters of organic dicarboxylic acids to be polycondensed For example, those of aliphatic dicarboxylic acids with up to 20 carbon atoms, cycloaliphatic with in particular 4 to 6 carbon atoms in the ring or, in particular, aromatic ones with 1 or 2 aromatic rings. Examples of suitable ones Dicarboxylic acids are succinic acid, adipic acid, sebacic acid, cyclobutane-l ^ -dicarboxylic acid, cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, ρ, ρ'-sulfonylphenyldicarboxylic acid, ρ, ρ'-dicarboxydiphenylethane, 2,6- or 2,7-naphthalenedicarboxylic acid or 2,5-thio-

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phendicarboxylic acid, especially terephthalic acid.

The bis-glycol esters are formed as glycol components in particular aliphatic or cycloaliphatic glycols having 2 to 10, advantageously 2 to 8 carbon atoms, such as Propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol or 1,4-bis-hydroxymethyl-cyclohexane, especially ethylene glycol. A particularly preferred bis-glycol ester is diethylene glycol terephthalate.

The bis-glycol esters to be polycondensed according to the invention can be prepared by direct esterification of the acids with the glycols or epoxides or by transesterification in the usual way. For example, the transesterification of dimethyl terephthalate is with Ethylene glycol in the presence of transesterification catalysts such as zinc or manganese acetate. It is common to use the To inactivate transesterification catalysts with phosphorus compounds, such as triphenyl phosphite, before the polycondensation. the Glycol esters can contain low molecular weight precondensates.

The polycondensation of the bis-glycol esters can, after the addition of the germanium compounds according to the invention, be carried out in one or, preferably, in multiple stages. The germanium compounds can be added to the bis-glycol ester melt in isolated form, as a mixture with glycol or in an aqueous solution as they are produced. The polycondensation is generally carried out at temperatures from 220 to 300 ^° C. at a pressure from 760 torr down to 0.1 torr. Any water introduced with the germanium compounds is quickly removed at the high temperatures used and at the low pressures, so that saponification of the bis-glycol esters or the precondensates is not to be feared. Often it is useful up to relative

Viscosities of the polyester obtained from 1.3 ** to 1.46, in particular of at least 1.39> to condense.

The amount of germanium compounds added is generally from 0.005 to 0.1, in particular from 0.005 to 0.03, by weight, calculated as germanium dioxide and based on finished polyester.

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But it is also possible to use the germanium compounds during the production of the bis-glycol esters, for example during transesterification of dimethyl terephthalate with ethylene glycol to be added.

In the production of the polyester, customary additives, such as Pigments, such as TiOp, antistatic agents or dyes, can be incorporated before, during or after the condensation.

The polyester obtained according to the invention can be used directly or after their conversion into schnitzel or the like via their melt further processed, for example into fibers, threads or ^ films. The fibers, threads or films obtained in this way show good results ™. technological properties. Also processing into injection molded articles is possible.

The polyesters obtained according to the invention are distinguished above all by a very good color quality: they have practically no color of their own. This is all the more surprising since it has hitherto been the opinion that the presence of basic nitrogen compounds during the polycondensation increases. discoloration of the polyester. Compared to polyesters obtained with the germanium compounds customary hitherto, those obtained according to the invention are distinguished by a higher melting point and better lightfastness, which is probably due to a lower content of difc glycol. Since the germanium compounds used are soluble in the polycondensation mixture or in the finished polyester, the result is an increased polycondensation rate and good filterability of the finished polyester.

Germanium catalysts are used in the invention, from the readily accessible by germanium _y simple reaction conveniently and economically obtained, wherein both the amorphous and the crystalline germanium can be used as described. A further advantage is that concentrated solutions of the germanium catalysts according to the invention can also be obtained. By adding concentrated catalyst solutions, the reaction mixture ζ is less consumed in polyester production. thins.

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The parts and percentages given in the example are based on weight.

example

a) Production of diethylene glycol terephthalate or its precondensates:

970 parts of dimethyl terephthalate, 775 parts of ethylene glycol and 0.2. Parts of zinc acetate are placed in a stainless steel vessel Melted nitrogen atmosphere at 150 ° C and stirring in the course of 3 to i? Hours heated to 22O ° C, initially Methanol and finally also ethylene glycol distilled off.

b) Manufacture of germanium catalysts:

Type I: amorphous germanium dioxide in solid form; Type II: solution obtained by heating 1 part of germanium dioxide in 99 parts of ethylene glycol to reflux temperature; Lösungi obtained from 1 part of germanium dioxide in a mixture of M parts of water and 1.1 parts of trimethylamine at 20 ⁰ C: Type IIIa

Type IHb: isolated by evaporating the solution obtained according to IHa Germanium compound;

Type IIIcj glycolic 1 percent solution of the isolated according to IHb Germanium compound;

Type IV: solution obtained from 1 part of germanium dioxide in a mixture of Ί parts of water and 0.97 parts of diisopropylamine at 20 ° C; Type V: solution obtained from 1 part of germanium dioxide in a mixture of k parts of water and 0.62 parts of diisobutylamine at 20 ^° C .; Type VI: solution obtained from 1 part of germanium dioxide in a mixture of 4 parts of water and 0.86 part of dicyclohexylamine; Type VII: solution of 1 part of germanium dioxide in a mixture of H parts of water and 0.45 parts of piperidine; Type VIII: solution obtained from 1 part of germanium dioxide in a mixture of M parts of water and 0.4 parts of morpholine.

Served for the production of the catalyst types I to VIII amorphous germanium dioxide.

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c) Polycondensation:

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A transesterification product prepared according to a) is mixed with 0.4 parts of triphenyl phosphite each and with such an amount of catalyst I to VIII that, converted to finished polyethylene terephthalate, 0.01 or 0.02 % GeO ₂ is obtained. The mixture is brought ^{to 245 ° C. with stirring.} The pressure is reduced from 760 torr to 0.5 torr over the course of 2 hours and the temperature is increased to 275 ° C. at the same time. Under these conditions, nsation takes place for 3 hours. The finished polycondensate is pressed out under nitrogen, granulated after passing through a water bath and dried.

The table shows relative viscosities, melting points and diglycol contents of the polyethylene terephthalates obtained. The relative viscosities were measured in the form of 0.5 percent solutions at 25 ° C. in a phenol-o-dichlorobenzene mixture 3: 2 with the aid an Ubbelohde viscometer and the melting points determined by means of a polarizing microscope.

Tabel

catalyst
Type additive
of germanium
Connection % relative
viscosity hue Melting point
⁰ C 5 I (compar
attempt) 0.01 1,348 colorless 257, II (compar
attempt) 0.01 1,385 colorless 257 IHa 0.01 1,367 color go 260 5 HIb 0.01 1,381 colorless 260. HIc 0.01 1,416 colorless 260 IV 0.01 1,388 colorless 262 V 0.01 1,372 colorless 261 5 VI 0.01
00981 1,379
9/1850 colorless 262.
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Catalyst additive relative hue ScnrtiexzpanKi

type of germanium viscosity o "

Connection %

VII
VIII

0 , 020 1 .435 colorless 259 , 5 0 , 01 1 .346 colorless 260 0 , 01 1 .366 colorless 261

The increased melting point of using the inventive The polyethylene terephthalates obtained from catalyst types III to VIII can be readily recognized.

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Claims (2)

Claims 1. "Process for the production of linear polyesters by polycondensation of bis-glycol esters of organic dicarboxylic acids or their low molecular weight precondensates using germanium compounds as polycondensation catalysts, characterized in that germanium compounds are used which are obtained by dissolving germanium dioxide in water under the action of volatile monoamines aliphatic or cycloaliphatic radicals have been obtained. 2. Process for the production of linear polyester according to claim 1, characterized in that 0.005 to 0.1 wt. Germanium compounds, calculated as germanium dioxide on polyester, are used. Badische Anilin- & Soda-Fabrik AG 009819/1850