DE1770495A1 - Stabilized polyethylene glycol terephthalates - Google Patents

Description

FA-RBENFABRIk-JiiN Dai BK AG L EVER KU S EN-Bayerwerk Pttent-AbteUunf Reu / Ws Z Tt. ΜβΙ 1968 Stabilized polyethylene glycol terephthalates

The invention relates to stabilized high molecular weight Polyethylene glycol terephthalates, which are stabilized against thermal degradation by carbodiimides.

Due to the heat sensitivity of polyethylene glycol terephthalates, it is necessary for this high molecular weight, linear Stabilize polyester. During thermal degradation, the polyester molecules are first attached to the ester group Formation of a carboxyl group and a vinyl ester cleaved. The rate of degradation is mainly determined by the temperature and the nature and amount of the pole; ^ ondrensationskatalysators influenced. Metal salts such as Zinc, calcium, antimony, germanium or manganese salts.

The thermal resistance can be increased by adding precipitants or complexing agents such as phosphoric acid, o-phenanthroline, Phthalocyanines improve the degradation effect of the catalysts srerhindere · A number of other stabilizers are suggested been. Phosphorus compounds such as triaryl phosphites, triaryl phosphates, polymeric esters of phosphoric acid or phosphoric acid with polyols, as well as metal alkyl phosphates as Stabilizers for high molecular weight, linear polyesters known. It is also the stabilizing effect of small amounts of an alkali metal or other metals such as nickel, copper, aluminum *, manganese or iron.

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Attempts have also been made to use phosphinic acid esters as a stabilizer have free carboxyl groups by esterification into the polyester molecule to be built in. Also azo compounds and pyromellitimide derivatives have been proposed as stabilizers for high molecular weight linear polyesters.

However, it has been shown that with increased heat loading of gt formed structures from polyethylene glycol terephthalates, such as threads or fibers, in particular from tire cord, the stabilizing The effect of these known stabilizer compounds is insufficient is.

It has now been found that carbodiimides are excellent stabilizers for the roll stabilization of high molecular weight polyethylene glycol terephthalates. The following carbodiimides are preferably used for this purpose as a stabilizer: Aliphatic, aromatic, cycloaliphatic mono- or polycarbodiimides, for example N, -Methyl-II ^| ! 4ert. ~ Butylcarbodiimide, NjN'-dicyclohexyl-carbodiimide, N.H'-diphenylcarbodiimide, I, H ^r -di-p-tolylcarbodiimide, NjH'-Bi
diimide and H, N'-bis- (2,2'-6,6'-

diimid. Particularly effective: have polycarbodiimides proven, for example hexamethylene-Cu ^ ca'-bie-cyolohexylcarbodiimide, and aromatic polycarbodiimides of molded ice

R R

wherein R is hydrogen or a Cj-bie-C.-Alkylreet and η is a number from 2 to 20 .

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The production of such polycarbodiimides, among other things, the substituted Diphenylmethanpolycarbodiiinide is known (German patent specification T 156 401).

It is known that carbodiimides can be used as anti-aging agents against the effects of heat and moisture in polyester-isocyanate plastics. However, it could not be concluded from this that this effect is also effective with polyethylene glycol terephthalates, since it was to be expected that the presence of metal salts, which serve as polycondensation catalysts, would render the carbodiimides ineffective as stabilizers. Carbodiimides namely form isoureas under the catalysis of metal salts with compounds containing hydroxyl groups - as are present in the reaction mixture in the form of glycol- or hydroxyl-containing terephthalic acid esters. Carbodiimides are the Polyäthylenglykolterephthalaten added in an amount of 0.1 to 20 wt. #, Preferably in an amount of 5 wt Ibis. I 'after the transesterification, wherein the polycondensation is carried out in known manner at temperatures of 250 to 28O ⁰ C, it does not matter whether the polycondensation is carried out batchwise or continuously. A precondensate can also be produced from terephthalic acid and ethylene glycol in a known manner and the carbodiimides can be added to this before the polycondensation. .

The further processing of the stabilized PoT-ethylenglykolterephthalate «U threads and fibers can pass through in the usual way Spinning and drawing geeohthen.

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The good stabilizing effect of the carbodiimides against the thermal For example, degradation of polyethylene glycol terephthalatin is evident that the degradation of the polyethylene glycol terephthalates, measured by the change in melt viscosity, is much slower than with known stabilizers stabilized polyethylene glycol terephthalates. Depending on the added amount of the carbodiimide, the degradation of the polyethylene glycol terephthalate will be considerably delayed, or practically completely prevented if the amount added is sufficiently large.

In addition, there is the advantage that the melt viscosity is only slightly changed, or in some cases even increases slightly, which is important, for example, for the production of silk from polyethylene glycol terephthalates; the melting point remains practically unchanged good stabilizing effect in tire cord also polyethylene glycol terephthalate, which is exposed to considerable temperature loads during thermal pretreatment and vulcanization in the tires.
example 1

160 kg dimethyl terephthalate is transesterified with ethylene glycol HO kg 3 stood at 200 ⁰ C with the addition of 64 g zinc acetate. Anechlieaend the precondensation is carried out for 1 1/2 hours at a temperature of- 250 ⁰ C. For the final polycondensation, the melt is kept for 4 hours at 275 ⁰ C and at Ěîńęâŕ pressure of 1 Torr, in each case the stabilizers listed in the table in the amounts indicated

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can be added. For comparison, this is used as a stabilizer known trinonylphenyl phosphite has been used.

a) 160 g = 0.1 wt .- ^ I, 3 ^ -Triisopropylbenzol ^^ - polycarbodiimide

b) 480 g = 0.3% by weight of 1,3,5-triisopropylbenzene-2,4-polycarbodiimide

c) 800 g = 0.5 wt. # 1.3, S-triisopropylbenzene - ^^ - polycarbodiimide

d) 160 g = 0.1 wt. i "trinonylphenylphosphite

The chips produced with these stabilizers showed the following physical data

^a) ^ 280 ° = 235O / -4O% = ■ 24OO / -35 #

259 ⁰ C

Fp

Pp

Pp = 260 ⁰ C? _peI 1.61

Pp = 259 ⁰ C%. _el V56-

261 ⁰ C

means the rotational viscosity, measured ia-Rota1rione ~ viscometer according to Haake; %. _ψ ^ is the relative Lö * "etc. * sviekosität measured on a 1 #igen solution in m £ resol at 25 ° C.

These chips undergo a heat treatment at 170 C in a drying cabinet subjected to over 144 hours and after this time the Viscosity measured by the plate-cone method (W. Heinz, Adhäsion, Issue 6, 1957).

Initial viscosity 914 Viscosity according to
144 hours Dismantling
kosity i » the Outgoing vis- a) 980 445 48 D) 965
660 825 84 c)
d) 992 10 98
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Furthermore, the chips are made from the melt spinning process The stretched threads produced are subjected to a heat test:

The stabilized with ffemäß a) to c) show Polyäthylenglykolterephthalatfäden at a load of 2.7 g / d, at 145 ⁰ C after 40 - 50 hours yarn breakage. In contrast, the sample stabilized according to d) shows thread breakage after 10 hours under the same load.

A comparison with polyethylene glycol terephthalates, which contain 0.3 or 0.5 $> trinonylphenyl phosphite as a stabilizer, is not possible because the melt viscosities of such products are too low, since they cannot be spun and are therefore no longer usable, for example, for textile use.

The stabilizing effect of other organic phosphites and of metal phosphites of the Kupiere or Hangan ' or also of the copper iodide is of the same order of magnitude as that of trinonylphenyl phosphite.

A stabilizer effect similar to that of the 1,3 _f 5-triiaopropylbenzene-2,4-polycarbodiimide is achieved by adding equal amounts of 1-methyl-3,5-diethylbenzene-2,4- (or -2,6 -) ßolycarbodiimide and 3t5,3 ', 5 *, -Tetraethyldiphenylethan .- ^^' - polycarbadiimide.

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Example 2

The transesterification of dimethyl terephthalate with ethylene glycol is carried out as described in Example 1 and then to the precondensation in the polycondensation, each The stabilizers listed in the table were added in the amounts indicated ». · '· ...

a) 160 g = 0.1

b) 72Og = 0

N, N'-bis (2,6 diisopropylphenyl) carbodiinide , 6 diisopropylphenyl) carbodiimide

Those made with these stabilizers. Have schnitzel the following physical values:

Pp = 261.3 C Ρϊ = 25? ⁰ C

b) ^ _aQ a = 1985

These steps become a wax gate treatment. at 17O ⁰ C im

subjected to over 144 hours and after this

Time the viscosity measured by the plate-and-cone method.

Ausgangsvlskos i t ät

Viscosity according to. 144. hours

Decomposition to % of the initial viscosity

a) 592

b) 782

270, 390

45 49

Compared to Example Id, an improved stabilizer effect can be seen below. A stabilizing effect similar to that of the previously mentioned carbodiimide is achieved with the addition of equal amounts of M, H ^t -Bie- (2,2'-diä.thyldiphenyl) -carbodiimide, ^w _# I-di-p-tolylcarbadiim ± d. _r Hili'-di-cyclohexylcarbodiimide.

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Claims (4)

Patients' approval O 1. Use of carbodiimides as stabilizers against the thermal degradation of high molecular weight, linear PolyäthylenglykoIt erephthalat en. 2. Use of aromatic polycarbodiimides of the formula .N = C = N- n
in which R is hydrogen or a C, -bis-C-alkyl radical and η is an integer from 2 to 20 as stabilizers: against the thermal degradation of high molecular weight linear polyethylene glycol terephthalates. 3 · stabilized against thermal degradation Polyäthylenglvkal- terephthalate containing, as stabilizers, 0.1 to 20 wt # _{r is} preferably 1 to 5 wt $ -.. "Ines carbodiimides. 4. Tire cord consisting of polyethylene glycol terephthalate fibers containing 0.1 to 20 wt. #, Preferably 1 to 5 wt. # Of a carbodiimide. 5 · Process for the production of stabilized against thermal degradation Polyethylene glycol terephthalates by adding stabilizers to the polyethylene glycol terephthalate, d. g. That you have a terephthalic acid-ethylene glycol precondensate before the polycondensation 0.1 to 20 wt. ^, preferably 1 to 5 wt. # Of a carbodiimide is added and then the polycondensation performs in a known manner. 109846/1874 -8- Le A Π 505