DE1025142B - Process and apparatus for accelerating the formation of high polymer esters - Google Patents

Description

GERMAN

The preparation of condensation polymers with high molecular weights from glycols of the series OH (CH ₂ ) "OH, where η can be an integer from 2 to 10, and aliphatic or aromatic dicarboxylic acids and their derivatives has already been described several times (British patents 578 079, 604 073 and Austrian patent specification 166 247). For example, the process according to Austrian patent specification 166 247 is characterized in that terephthalic acid esters of glycols of the series OH (CH ₂ ) OH are heated above the melting point, with the exclusion of oxygen in an inert gas atmosphere or in a vacuum with the addition of inert ones Gases through a capillary tube, the melting point and the viscosity of the mass gradually increasing in such a way that a state is reached in which threads obtained from the melt have the property of being cold-drawn into firm, flexible threads. The heating of the ester to convert it into the highly polymeric state can also take place in the presence of suitable catalysts, for which Li, Na, K, Ca, Mg, Cd etc. are indicated. Corresponding measures are also to be taken according to US Pat. No. 2,465,319 to obtain the same preparations.

These publications show that the polycondensation takes place in an inert gas atmosphere is to be carried out under normal pressure and / or in the further course of the same under vacuum. According to the previous method, it is practical to work without the aid of a good vacuum from about 1 to 3 mm Hg impossible, since reaction times of well over 100 hours at normal pressure are needed. Working in a vacuum is, however, in view of possible leaks on the Apparatus is associated with some inconveniences, because exposure to air leads to discoloration and ultimately to a deterioration in the quality of the end product or the products made from it Structures such as threads, films, ribbons. In this regard, reference should be made in particular to the French patent specification 943 361 referenced, which expressly speaks of a cream-colored end product.

Another shortcoming of the previous production method is the extremely long reaction time or Condensation time. In the previously mentioned US Pat. No. 2,465,319, reaction times of 80 hours and 19 1/2 hours (Example 11) without a catalyst and 13 hours with catalyst called.

Another method is the condensation of aromatic dicarboxylic acids and diols or esters of these substances carried out in the solid phase in the fluidized bed process. Here, too, must expected with relatively long reaction times

Method and device

to accelerate education

of high polymer esters

Applicant:

VEB Thuringian synthetic fiber factory
"Wilhelm Pieck" Schwarza, Rudolstadt

Dr. Wolfgang Griehl, Teltow,
and Heinrich Krieger, Rudolstadt,
have been named as inventors

will. In addition, the glycol molecules that are split off and need to be expelled cannot diffuse out as well like from the liquid melt. Working in a fixed phase is also unfavorable in that as a condensation of aliphatic polyesters, the melting point of which is mostly below 100 °, and mixed polyesters using the fluidized bed process is not conceivable.

The present invention relates to a process for accelerating the formation of high polymers Esters preferably from glycols and aliphatic and aromatic dicarboxylic acids or their derivatives and to achieve colorless reaction products by condensation of the starting materials in the liquid phase without the application of vacuum. The condensation takes place by heating the reactant to higher temperatures in the presence of inert gases. The procedure after of the invention is that the inert gases in a fine or very fine distribution under pressure through the liquid reaction mass are passed. It is advisable to stir to give the inert gas an opportunity to always look for new ways through the crowd. This effect can also be applied to any other This can be done in a way, for example by rotating the organ that feeds the gas leaves without the mass itself being circulated. A slight overpressure in the reaction chamber is advantageous, to prevent the ingress of atmospheric oxygen under all circumstances.

The introduction of as strong a gas flow as possible in finely divided form facilitates the polycondensation necessary splitting off and removal of the dialcohol is essential. This is how it works also to shorten the reaction time of the overall process considerably.

709 907/440

To carry out this process, a device has been developed that consists of a heatable Reaction vessel of any design, in which the monomeric or weakly condensed ester from the dicarboxylic acid in question and a glycol is condensed, and in which there is a stirrer located whose shaft is hollow. The inert gas is introduced and passed through this hollow shaft the holes of the impeller, which are also hollow, are blown into the reaction mass.

An embodiment of the device is shown in Fig. 1 of the drawing. 1 denotes the Port through which the monomeric ester is poured into the vessel; 2 the mass to be condensed,

The number of pipe sections can be chosen arbitrarily, depending on how they are used for the reaction appears cheapest. In the drawing, the pipe sections are arranged side by side; is just as good any other arrangement, e.g. B. one above the other, conceivable. The operation of the arrangement shown is the following: The monomeric or weakly fused-on ester of the dicarboxylic acid in question and the Glycol is dispensed with a suitable metering device ίο from the storage container 17 into the first pipe section introduced and polycondensed therein, the inert gas through the feed unit 11 in the mass is blown into it. The still fairly liquid mass flows into the second pipe section,

3 the stirring device, through the hollow shaft 4 of which the 15 is also charged with inert gas. The inert gas introduced and through its perforated, now more viscous mass, finally passes into the wing 5, the gas blown into the reaction mass into the third pipe section. This is in the drawing. At 6, the inert gas escapes and is supplied to a voltage for generating a gas vortex with a collecting container which is not shown in the drawing and which, as already described, is provided with a stirrer. The container is provided at the bottom with a hollow shaft and a hollow, perforated stirrer and an opening 7 through which the finished poly wing has, through which the gas is released into the mass and is blown around the spinning device. Below the agitator blades, it can be supplied directly or via the storage container. Tube a degassing zone 18 is provided in which the particularly advantageous is a continuous in the mass remaining gas bubbles upwards mode of operation, in which the polyester continuously rise condensate so that the spinning mass is bubble-free in the siert and then spun. To this end, the spinning device 19 has reached. The finished polycondensate proved necessary for the condensation of the
monomeric or weakly condensed ester
of the dicarboxylic acid in question and the glycol one after the other in a continuous and interrelated manner
to carry out binding subsections,
whereby a mixing of the individual subsections
is avoided. For this purpose one uses
as a reaction vessel z. B. several according to the principle

of the communicating tubes are connected to each other for 4 hours while passing through finely divided bonded tubes, each of which can best be heated to the temperature required for the flow of nitrogen while stirring at the same time
is the most favorable reaction section in question.
Before the finished polyester exits into the
In the spinning device, a completely colorless polycondensate zone created in this way is expediently switched on, in which the spinning mass is freed from the gas bubbles which have remained very viscous from the melting point 254 to 256 °.

The inert gas required for the reaction is separated into each pipe section, expediently from below blown in, for which one can use any arbitrary feeding device which the gas is whirled into the reaction mass.

This arrangement is shown in Fig. 2 of the drawing
shown schematically. The interconnected 50 after which the ester exchange reaction, in which the teredens, each with a heating jacket surrounded pipes 8, phthalic acid dimethyl ester in glycol terephthalate over-9 and 10 are in their lower part with a feed, is practically ended. The resulting guide device 11, 12, 13 equipped, through the monomeric glycol terephthalate then vrird under gedas inert gas, e.g. B. nitrogen, hydrogen, carbon ring overpressure of about 40 mm water column so acidic, introduced into the reaction mass under pressure 55 heated to 280 ° until practically no ethylene is. The gas supply can be distilled over by a common glycol. Then, it is by seed supply container for each pipe section guided done of a strong, but finely divided nitrogen Separated and is expediently flow throughput with simultaneous stirring further 3 ¹ Zt Stungeführt that the gas by means of compressor by heating the to 280 °. The resulting product was individual feed units in the reaction mass 60 now a completely white, is pressed up at 256 ° to a and after leaving the reaction viscous liquid melting polymer, from the vessel at 14, 15, 16 via separators and coolers, not shown, those contained in the gas
Condense glycol vapors, which are fed back to the storage vessel, for example a gasometer. 65
You can also use the gas in series
Way to the individual condensation pipes,
by z. B. the last pipe is loaded first,
where the gas is still with relatively little
Glycol vapor loads, from there the penultimate, etc. 70

Λ. \ ~ J V- * \ ~ J * - 'Λ. ■ *

The esterified and degassed ester is then continuously spun into the desired shape.

example 1

100 g terephthalic acid and 200 g ethylene glycol are heated on the reflux condenser until solution occurs. The resulting glycol terephthalate is sucked off, washed with water, dried and about

heated to 280 °. The nitrogen that is passed through escapes into the atmosphere through a pressure relief valve, which is set at about ¹ Z ₂₀ Atm. Blows off excess pressure. That on

the threads drawn from the melt were easily cold-stretchable.

Example 2

100 g of dimethyl terephthalate, 100 g of ethylene glycol and 0.04 g of lithium metal are slowly heated from 150 to 195 ° in a stream of nitrogen. About 30 g of methyl alcohol distill off in about ^{3 A to 1 hour,}

a stretchable thread with good textile properties could be drawn.

Claims (4)

PATENT CLAIMS: 1. Process for accelerating the formation of high polymer esters from polyalcohols, such as Glycols, and aliphatic and aromatic dicarboxylic acids or their derivatives by heat to higher temperatures in the presence of inert gases, as well as to form uncolored ones Reaction products, characterized in that the inert gases are finely or finely distributed are passed under pressure through the reaction mass. 2. A method for the continuous production of high polymer esters according to claim 1, characterized characterized in that the condensation of the monomeric or weakly condensed ester from the dicarboxylic acid in question and the glycol one after the other in consecutive and in one another related subsections is carried out without mixing the contents the sections, after which the finished polyester is optionally passed through a degassing zone and then fed continuously to the spinning device. 3. Apparatus for performing the method according to claim 1, characterized by a stirring device, which is located in a heatable reaction vessel of any design, whose shaft for introducing the inert gases is hollow and whose agitator blades are also hollow are provided with holes through which the gases are blown into the reaction mass. 4. Device for the continuous implementation of the method according to claim 1 and 2, characterized by several interconnected according to the principle of communicating tubes Pipe sections, which are each equipped with an arrangement through which the inert Gas enters the reaction mass in finely divided form under pressure, and of which the last Pipe section or part of the last pipe section is a degassing zone for the polymer contains. Considered publications:
Chemical engineering technology, 1952, No. 2. 1 sheet of drawings © 709 907/440 2.