DE1905188A1 - Process for the preparation of polyalkylene terephthalates and modified polyesters - Google Patents

Description

1905138

KANEGAFUCHI BObEKI KABUSHIKI KAISHA

TOKYO / JAPAN

Process for the preparation of polyalkylene terephthalates and modified polyesters

The invention relates to a process for the preparation of polyalkylene terephthalates and modified polyesters mainly consist of polyalkylene terephthalate »

An example of a process for the preparation of polyalkylene reactants consists of terephthalic acid or its nieaarjn aliphatic t ^ ter with an AlKylunglycol of the general

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formula

In which η 2 or series integer »the greater than 2 Jst> Means, converted to bls {hydroxyalkyl) terephthalate and then polyalkylene terephthalate therefrom manufactures. The reaction is thus carried out in two stages, where in the first the bis (Hydroxyaikyl) tere'phthdldt and In the second by polycondensation of bis (Hyaroxyaikyl) terthdläts the polyalkylene terephthalate is produced. In both Various catalysts are used in stages.

The invention relates to a catalyst for aie polycondensation the second stage.

There are already many publications on the catalyst for polycondensation. For example, describes the brlt. Patent Specification 74Ü 381 antimony compounds, aie are soluble in a reaction system. The nieaerl. Patent specification 97 Ö3b discloses cobalt compounds. The Japan. Patent 288 887 and British Patent 793 111 mention titanium compounds. However, the known catalysts are unsatisfactory with regard to the color shade and various physical properties of the polyesters obtained.

The object of the invention is therefore to provide a method to ask, which is colorless polyester with excellent physical properties using a suitable catalyst Properties supplies.

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This object is achieved according to the invention in that one as Catalyst used for polycondensation metallic titanium.

Until now, the main catalysts for polycondensation have been organic ^ titanium compounds proposed. These connections are usually soluble and possess in the neat solution high catalytic activity. Jeaoch are the ones that have been preserved Polymers colored yellow or brown, bo da.3 these compounds In can only be used with difficulty in practice.

It has now surprisingly been found that aa3 is metallic Titanium is catalytically effective, the activity being very high and the polymer obtained is not colored at all. When comparing with antimony oxide it results that when using the known catalyst, the resulting polymers discolored yellow-green while titanium is a completely colorless and transparent one Polymer supplies. It has also been shown that with regard to on the other physical properties, i.e. the Number of carboxyl groups, the melting point associated with titanium obtained polymers are far superior.

Investigations were carried out with metallic titanium that in the form of finely divided particles, coarser particles and of other small moldings, such as blocks, flakes, L-chips, shavings, ribbons, nets composed of fine wires, small balls or fine granules. As a result, has it has been shown that aa3 all these forms are suitable as catalysts.

Various experiments were also carried out, in which the reaction vessel or at least part of its accessories, aer came into contact with aena reaction mixture, made of metallic titanium

9 0 9 8 A UI 1 7 S 9

or an alloy composed primarily of this metal was made. The polycondensation takes place through the catalytic Effect of the reaction vessels or the accessories, whereby it was found that a permanent and uniform polycondensation took place.

First of all, the use of fine titanium powder, which is one of the represents the most favorable embodiments of the present invention, are explained in more detail.

When using metallic titanium as a catalyst it is expedient, the titanium to increase the contact area to the more uniform Dispersion in the reaction system in the form of a fine to use distributed powder. The results of various experiments show that the ability of the catalyst to accelerate the polymerization varies with the particle size of the powder. The catalyst used in the polycondensation of the polyester Generally remains in the polymer and becomes in the subsequent ones Process steps not removed so that he is in the threads remains after spinning. Thus, there are certain limitations on the shape, particle size and amount of the as Powder that can be used as a catalyst.

It has been found that with an average particle size of metallic titanium of less than 100 # u the desired Results can be obtained and that the use of powders having a maximum of 3O / U is preferable. Furthermore, when the average particle size is set to 3 / U or less can be what by appropriate selection of the manufacturing conditions of the powder, by sieving and, if necessary,

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This particle sizes can be done by further auxiliary measures in terms of catalytic power and quality of the polymer obtained and the threads are particularly preferable.

In addition, the finely divided powder is very high Displacement stability in glycol.

As already stated, this is the effect of the invention metallic titanium used in the polymer no undesirable Discoloration to yellow or brown, so that the amount added does not have to be limited as critically as when using Antimony compounds and the other known catalysts. If the amount exceeds a certain titanium content, it occurs however, a green-black color, as it has the catalyst itself on. It is therefore advisable to add more than 1 wt .-% to report and especially if a white Appearance is required to limit the amount to 0.1% by weight.

The aim now is to use a relatively coarser titanium according to a further embodiment of the method according to the invention explained.

The reaction leading to the formation of the polyester is an equilibrium reaction, so that in addition to the formation reaction, the reverse reaction, i.e. the depolymerization, can always take place. There the catalyst that accelerates the formation reaction, too ' at the same time catalyzes the reverse reaction, it is expedient to rapidly remove the catalyst from the polymer after the polycondensation has ended to remove in order to avoid decomposition reactions of the polymer.

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As conventional catalysts for the production of polyesters, substances soluble in the reaction system have been used. In some cases, insoluble fine particles can also be used. However, in any of these cases, the separation of the catalysts from the polymer is difficult, so that the catalysts remain in the polymer. Thus, when the polymer melts again during the subsequent spinning, the viscosity of the polymer is reduced due to the decomposition that takes place. In addition, undesirable discoloration occurs. These disadvantages pose great problems in the production of polyesters. Furthermore, when fine metal particles are used as catalysts, these are often incorporated into the spun thread, so that button formation and breakage of the thread can disadvantageously occur. When using relatively coarse metallic titanium, for example blocks, flakes, chips, shavings, ribbons, nets composed of fine wires, small spheres, fine or coarser granules, the catalyst can, however, be separated quickly from the polymer by simple filtration. In this V.eise polymers can be prepared which contain little or no more catalyst, the titanium catalyst hen as a coarse granules having a longitudinal diameter of more than 1OO, u is present, then most of the grains are filtered out by a method used in spinning filter, so that the disadvantages described above can be reduced considerably. In view of the filtration efficiency, larger particle sizes are more desirable, but in this case the useful surface area for the catalytic efficiency is reduced and the catalytic ability is reduced compared to the same amount of finer particles. In this context

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Various investigations have been carried out which have shown that since the catalyst effect can be increased by stronger stirring and by a larger proportion, it is quite appropriate, in view of the efficiency of the filtration, to use powders with a particle size of more than 200 / rev, if the quality of the polymer and the yarn are considered to be more important. With particle sizes above 500 , the filtration efficiency is sufficiently high.

The catalytic activity of metallic titanium is indeed so high that even coarse powders or blocks are catalytically effective.

Metallic titanium is usually very stable and is for the not harmful to human body.

It is naturally expedient to use metallic titanium of high purity, but the presence of small amounts of impurities and additives does not have any significant disadvantages. In the case of raw materials for synthetic fibers, however, if there are severe restrictions because of the discoloration of the polymer, it is preferable to use metallic titanium with a purity of more than 90%. at

titanium
Use of metallic / of lower purity must be expected to cause unexpected phenomena. Recently, a method for cleaning titanium has been developed to such an extent that aa3 high-purity titanium with a purity of more than 93% can be easily supplied. The use of such a metallic titanium is particularly recommended.

The metallic titanium catalyst can after the use of the Polymers are separated and remains in the reaction vessel

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return. There was no significant decrease in the catalytic Activity observed so that the catalyst can be used several times.

When using metallic titanium In lump form or as The catalyst can add granules after the polycondensation removed after the extrusion. This is the resulting polymer never discolored. The other various properties are also the same as those using the conventional ones Catalysts, e.g. antimony trioxide, are superior to manufactured polymers.

When using the titanium catalyst in relatively coarse form, such as coarse granules, flakes, schnitzels, shavings volumes, fine Wires, etc., the catalyst separates out so quickly on the bottom of the reaction vessel that the emptying of the Catalyst is likely to be insufficient. Therefore should be on good mechanical agitation must be ensured.

It has also been found that even then a steady and uniform Reaction takes place when one part of the reaction vessel which comes into contact with the reaction mixture or at least some of the accessories, for example the stirrer made of metallic titanium or one mainly composed of titanium Alloy manufactures. However, the reaction can already take place sufficiently when the part of the system that is in contact with the reaction mixture, in whole or in part is coated with titanium or an alloy containing titanium. this can be achieved, for example, by cladding, plating or gluing. This also applies to projections, grooves, folds, Projections, etc. to which on the inner wall of the vessel and the

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ORJGlNAL INSPECTED

Il I I

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Inner parts, such as pipes, grids, perforated plates, nets, Partition walls, multi-level panels, etc. are provided. The * designation "accessories" includes stirrers, small plates, chains, Rings, fine wires and nets, etc. provided on the stirrer rotate together with it. The same applies Screws or washers used in devices for continuous Find polycondensation use. This embodiment is particularly for a continuous polycondensation process suitable.

Lately there is an increasing interest in a continuous Pciykondensatlonsverfahren emerged and there have already been carried out a large number of investigations. One of the most important problems is the difficulty of adding and distributing the catalyst uniformly. In the above-described embodiment of the present According to the invention, the reaction vessel itself acts as a catalyst, so that the separate addition of a catalyst is unnecessary. This liquid reaction mixture is used during the entire reaction, at which the polycondensation is completed, circulated uniformly and is in contact with the inner surface of the reaction vessel, which acts as a catalyst. So the above step does not have the disadvantages described above, so that a polymer having high uniformity can be obtained. The catalytic effect the titanium alloy varies according to the conditions in the Polycondensation, for example according to the contact area and the stirring speed. The higher the titanium content the greater the catalytic effect, so that in general alloys containing more than 75% by weight of titanium are preferred.

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Holyesters which can be produced by the method of the invention, are, for example, polyesters made from dicarboxylic acids or their derivatives and dihydroxy compounds or their derivatives. Examples for this purpose polyalkylene terephthalates, such as polyethylene terephthalate, Polypropylene terephthalate, polytetramethylene terephthalate, polyhexamethylene terephthalate and modified polyesters obtained by copolycondensation of more than 75 mol% of those described above Obtained polymers with less than 25 mol% of further components with at least one ester-forming functional group will.

Such modified polyesters are, for example, polyesters with at least one aliphatic diol (excluding an alkylene glycol a main component of polyalkylene terephthalate), such as ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, Hexamethylene glycol,; Polyethylene glycol, such as diethylene glycol, Triethylene glycol; aromatic diol, such as catechol, Resorcinol, hydroquinone; alicyclic DIoI, such as cyclohexanedlmethanol, Cyclohexanedol; aliphatic D! carboxylic acid, such as Adipic acid, sebacic acid, decanedicarboxylic acidj aromatic Dicarboxylic acids, such as phthalic acid, isophthalic acid, sodium sulfo-isophthalic acid, Sodium sulfoterephthalic acid, naphthalenedicarboxylic acid; al! cyclic dicarboxylic acids, such as hexahydrolsophthalic acid, Hexahydroterephthalic acid and its derivatives copolymerized are.

The presence of titanium oxide as a matting agent, pigment, dye, Fluorescent brightener and other additives generally used in polyester has an impact on the process the invention has no influence.

The invention is illustrated in the examples. In these examples Unless otherwise specified, "parts" mean parts by weight.

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- 11 Example 1

In a reaction vessel equipped with a stirrer, an inlet for Nitrogen gas and an outlet for nitrogen gas and by-products was provided, 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, O.O15 parts of zinc formate and 0.017 parts TrläthyIphosphat entered. The resulting mixture was under Passing in gaseous nitrogen heated rapidly to 170 ° C. 30 minutes after the temperature reached 170 ° C the stirrer was turned on at a stirring speed of 60 rpm. The temperature of the jacket of the reaction vessel was then determined increased by 10 ° C every hour. The ester interchange reaction was stopped after 7 hours at 240 ° C. The course of the Reaction was determined by determining the amount of methanol distilled off. At the end of the reaction, the ester interchange was reached 96%.

To prepare the catalyst for the polycondensation, metallic titanium with a purity of 99.9 % was ground with 4 times the amount of ethylene glycol in a porcelain bowl for 72 hours. It was then diluted with ethylene glycol to such an extent that a 5% dispersion was obtained. This was left to stand in a cylindrical vessel for 24 hours. The coarse particles deposited at the bottom of the cylindrical chamber were carefully separated from the dispersion containing fine particles, and the concentration of titanium in the dispersion was determined. The dispersion was then diluted to one percent by weight titanium with ethylene glycol. The size distribution in the dispersion was determined after starting phases. The average particle size was 2.4 aj.

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A certain amount of the titanium dispersion prepared for this catfish was added to the ester interchange reactant product described above. The temperature of the jacket of the reaction vessel was then increased to 280 ° C. in the course of one hour. It was stirred and nitrogen gas introduced. The gases in the reaction vessel were then sucked off by means of a vacuum pump lower the pressure in the reaction vessel to 0.3 mm Hg. In this state, the polycondensation reaction was continued. at As the reaction proceeded, the viscosity of the reaction product increased and the electrical required to operate the stirrer Energy on. The electrical energy was both in size and the shape of the vessel and the stirrer, as well as the viscosity. The relationship between the Stirrer required electrical energy and the viscosity the content has already been determined in advance. When the electric power reached a predetermined value, the stirring stopped interrupted and the operation of the vacuum pump stopped. To the To terminate the reaction, nitrogen gas was introduced. (The time required from reaching the vacuum of 0.3 mm Hg to to stop the reaction is called "polycondensation time im Vacuum ".) The reaction product was from the bottom of the Removed from the vessel and cut into small pieces.

By changing the amount of titanium dieperslon added a series of tests was carried out. The time of polycondensation was measured. Furthermore, the properties of the polymers obtained were determined and compared with those of when used compared products obtained from antimony trioxide as a catalyst. These results are shown in Table I.

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The viscosity of the polymer is expressed as the intrinsic viscosity in a solvent mixture of ethane tetrachloride and phenol (40/60% by weight) at 25 ° C. This results from the the following formula:

Mm η -1

ι

O * o C

in which π is the relative viscosity at a polymer concentration of C (g) / 100 cm means.

The number of carboxyl groups is given as:

Carboxyl group equivalents / 10 g of the polymer

specified. This size was determined by titration of the polymer in Benzyl alcohol determined with potassium hydroxide.

The melting point was determined on a hot bench. He gives the

at
Temperature at / at which half of the sample has melted.

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I Λ Λ ti

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Table I.

Catal
gate crowd
Wt% Polycondens
sation time
in a vacuum
(H) Intrinsic
Viscosity Carboxyl
groups-
number
Equivalent ./
10 ° g Enamel color of the
point poly-
⁰ C mers colorless catalyst O, OO25 4th 0.65 20.2 261.5 Il 0.005 2 1/2 0.63 13.4 263.0 low
Gray coloring 0.03 1 1/4 0.66 19.3 262.5 easy
Gray coloring Metallic 0.1 1 0.73 25.6 262.5 Gray coloring titanium 1.0 1 0.82 20.0 261.0 Easy
Yellow grey-
coloring 0.03 3 0.69 29.7 259.5 Antimony-
trioxide

From Table I it can be seen that da.3 is the catalyst of the invention a very good one compared to conventional catalytic converters possesses catalytic activity. The polymers obtained therewith possess excellent physical properties and show no disadvantageous yellowing.

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Il ψ Ψ 9 9 · Ψ Vt ·· t ·

rf « tr t trf

f rt τ t ff r * »

• for · rt »

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The catalyst showed even when the titanium dispersion the mixture of the starting materials prior to the start of the ester interchange reaction was added, the same activity. Here too, polymers with the same properties as in Table I obtained.

Example 2

Sponge-shaped metallic titanium (with a purity of 99.2%) was coarsely ground and then in a porcelain ball mill with 4 times the amount by weight of ethylene glycol specified in the following Grinding times indicated in the table. Then was with ethylene glycol diluted to form dispersions with a titanium content of 1% by weight. The average particle size in the dispersions was determined according to the start-up phase. 0.5 parts of the individual dispersions (which corresponds to an amount of titanium of 0.005% by weight, based on the polymer, corresponds) were weighed and added to the ester exchange reaction product obtained according to Example 1. After that it was the polycondensation carried out according to Example 1.

It was found that the smaller the particle size, the smaller it was the time required for the polycondensation was shorter, so that Side reactions and thermal decomposition practically do not occur and obtain polymers with better physical properties could become.

When the average particle size was 121 / U, the catalyst fell in the reaction mixture, so that it was necessary to Increase the speed of rotation of the stirrer to three times the normal value. The results of these tests are summarized in Table II It.

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Table II 12th 24 48 72 72
(sifted) 121.4 86.2 38.7 22.5 2.4 Grinding
tent h 11 1/2 8 1/4 6 3/4 4 1/6 2 1/2 average
Particle size / U 180 60 60 60 60 Polycondensation
time in vacuum, h 0.53 0.61 0.60 0.70 0.63 Stirring speed
kelt rpm 28.6 20.4 25.1 18.7 13.4 Intrinsic viscose
activity Carboxy group

number, equivalents / iO ^D g

Melting point, ⁰ C 260.0 261.5 260.5 262.5 263.0

Color of the poly- light very very colorless colorless

meren yellow slightly light

yellow yellow

Example 3

In the reaction vessel according to Example 1, 85 parts of methyl terephthalate, 15 parts of dimethyl isophthalate, 70 parts of ethylene glycol, 0.015 part of zinc acetate, 0.02 part triphenyl phosphite and 0.4 part titanium oxide introduced as a matting agent. Then, as in Example 1, an ester interchange reaction was carried out performed. The percentage ester exchange, calculated from the amount of distilled methanol was 85%.

The catalyst was prepared by dissolving crushed titanium into a ball mill was ground with ethylene glycol for 72 hours. Then was the milled titanium with ethylene glycol to a dispersion with 5 wt .-% titanium diluted. After allowing the coarse particles to settle for 24 hours, they became separated from the fine particle dispersion and removed.

The titanium dispersion obtained in this way was in the form shown in Table III amounts shown were added to the ester interchange reaction product just mentioned. The polycondensation was then carried out in accordance with Example 1. the

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required reaction time and the characteristic properties of the obtained Polymers were compared with the corresponding values when using antimony trioxide as a catalyst. It turned out that even if the amount of catalyst used was less than that of the conventional catalyst, the reaction was completed in a shorter time using the catalyst of the invention. It was also found that according to the invention produced polymers with regard to their physical properties and its hue was superior to conventionally produced polymers. The results are shown in Table III.

Catal Tabel III Carboxyl - Enamel hue goal crowd, groups- Point of the poly catalyst Wt .-% / Polycon Intrinsic number, aqui- ⁰ C meren Polymer densa- sic- vaLente / functional Viscose 10 ° g 0.005 time in Va si did 15.6 221.0 white3 0.025 kuum, h 18.2 221.0 White Metallic 0.04 2 1/4 0.61 27.2 220.5 easy titanium 1 1/2 0.65 Gray 0.04 1 1/4 0.71 24.8 220.5 easy yellow Antimony- 3 0.72 trl oxide Example 4

Into a stainless steel autoclave equipped with a stirrer, an inlet for nitrogen gas and an outlet for nitrogen gas and by-products, which in turn was connected to a fractionating column, were charged 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, 0.015 part of zinc formate and 0.017 part TriethyIphosphat entered. The whole was heated while blowing nitrogen gas. 30 minutes after the temperature had reached 170 ° C., the stirrer was started at a stirring speed of 60 rpm. Then the temperature of the autoclave jacket was increased by 10 ° C. every hour. The ester exchange reaction was stopped after 7 hours at 240 ° C., the ester exchange, calculated from the amount of methanol distilled off, was 97.5%. ,

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Λ Β M *

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Further, the polycondensation catalyst was prepared by roughly crushing spongy titanium metal blocks having a purity of 99.5% and sieving the crushed titanium to obtain coarse particles having a particle size of 100 µm - 3 mm .

To the Esteraustauschreaktionsprodukt the amounts indicated in Table IV were added. The temperature of the autoclave jacket was then increased to 280 ° C. within one hour. During this, nitrogen gas was introduced. In this case, the stirrer was operated at a stirring speed of 150 rpm in order to prevent the separation of titanium particles. After the temperature had reached 280 ° C., the autoclave pressure was reduced from atmospheric pressure to 0.3 mm Hg within one hour by means of a vacuum pump. After the viscosity had risen so much that the precipitation of the catalyst was prevented, the stirring speed was reduced to 60 rpm and the polycondensation reaction was stopped when the viscosity had almost reached the desired value. The viscosity of the reaction product was estimated from the electric power consumed in the stirring motor. The operation of the vacuum pump and the rotation of the stirrer were interrupted. Nitrogen gas was introduced into the autoclave, and the reaction product was extruded from the bottom of the autoclave under nitrogen gas pressure in the form of a string. The extruded string was cut into chips. When the polymer was extruded, the titanium particles were removed through a filter provided at the bottom of the reaction vessel.

The results obtained are summarized in Table IV.

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Table IV

Catalyst Catalyst- Polykon- Intrln- Carboxyl-

gate amount, the- siegroup-

Wt .-% / tfons- visco number, equivalent

Polymeric time in vacuum vatente / kuum, h 10 g

Melting hue point of the poly

meren

Metallic
titanium

0.5 1.0 3.0 5.0 10.0

6th 1/2 0.65 29.3 260, 5 slightly yellow 4th 3/4 0.61 22.5 260, 0 colorless 2 1/4 0.60 16.1 260, 5 H 1 5/6 0.60 13.4 262, 5 Il 0.63 12.0 262, 0 H

Antlmontrioxide

0.03

0.65

27.3

260.0

slightly yellow-green

From Table IV it can be seen that the catalyst of the invention is polymeric with very good properties. In particular, the polymers obtained are excellent in terms of coloration, which is due to the absence of the polycondensation catalyst is due. In addition, the Catalyst separated from the polymer and remaining in the reaction vessel can be used repeatedly.

Example 5

A titanium plate made of high-purity titanium with a purity of over 99.5% was cut into strips of metallic titanium using an electric drill, all strips had an average width of 4 mm as well a thickness of 0.3-0.5 mm. They have been suitably tailored so that its longest section was no larger than 5 mm. To the glad example 4 obtained ester interchange reaction products became those in the following Table V added amounts of this catalyst and then carried out the polycondensation reaction. In this case it was fraud In the primary polycondensation stage, the stirring speed is 150 rpm, until the viscosity of the reaction product became so high that the deposition of the catalyst was avoided. After the viscosity has reached this value

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enough, the stirring speed was reduced to 60 rpm. At the Extruding the polymer, the catalyst was made from it through a bottom of the reaction vessel provided filter removed.

The results obtained are shown in Table V.

Table V

Catalyst polycondens

amount, wt .-% / sation time Polymer in vacuum,

Intrinsic carboxyl viscosity group

number, equivalents / 10 g

Melting hue point of the poly

meren

1.0

3.0

5.0

10.0

6th 1/4 0.67 31.0 259.5 very easy
te yellow color
exercise 4th 3/4 0.65 26.3 261.0 colorless 3 0.69 18.8 260.5 M. 1 1/2 0.68 14.1 260.0 M.

Example 6

The autoclave ACCORDING: 3 Example 1 was repeated with 90 parts of D methylterephtalat, 10 parts Dimethyllsophtalat, 70 parts of ethylene glycol, 0.015 part of zinc acetate and 0.02 parts Trlphenylphosphlt charged!. An ester exchange reaction was then carried out under the same conditions as in Example 4. In this case, the t-star exchange, calculated from the amount of methanol distilled off, was 97%.

The pieces of metallic titanium tape used in Example 5 were added to the ester interchange reaction product in the amounts shown in Table VI admitted. Under the same conditions as In In Example 4, a polycondensation reaction was carried out. In Table VI the analytical data for the polymer chips obtained are compiled.

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_t t ft · · *

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Catal Tabel VI Intrinsic 0.64 Carboxy I - Enamel hue goal crowd, sic- 0.62 groups- Point of the poly catalyst Qew. -% / Polycon V i sko- 0.65 number, equi ⁵ C meren Polymer densa- time im visity 0.66 valente / functional kuum, h 10 ° g 1.0 5 1/6 28.8 240.5 slightly yellow 5.0 2 3/4 19.0 241.0 colorless Metallic 10.0 1 1/4 12.1 241.0 Il titanium 0.03 4th 25.3 240.5 easy yellow-green Antimony- trioxide Example 7

L> sponge-shaped titanium blocks were crushed to a powder. This

was sieved and divided into 4 particle size classes: Less than 100

100 - 200 / Uj 200 - 500, uj and greater than 500 / U. The one prepared according to Example 4 Ester interchange reaction product was added with each powder of the classes described above. This was followed by the polycondensation reaction carried out. The polymer obtained was shaped into chips, dried and made into threads of 60 denier. spun. These were four times the original Length heh3 stretched and wound on a weft spool. The drawn thread was drawn up in the device described below examines the number of yarn knots.

Two small lightweight rollers which were made of stainless steel have been so placed previously by a preselected contact pressure In BerUh tion that these formed a gap. One of the rollers was rotated in a fixed position. The other could be shifted easily as it rotated along the normal to the surface of the nip of the two rolls. When a thread passed between the two V-rollers, the position of the second roller was shifted if the thread had irregular buttons. This shift is due to the variation in the diameter of the thread as the buttons pass through the nip. This variation was recorded by a voltmeter. In this way could be determined in the yarn, the number of buttons.

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It was found that when using titanium particles with less than 100 / rev, the number of irregular buttons on the polyester thread was 135 / 10,000 m. The corresponding number was 28 for a particle size of 100-200 / U; at 200 - 500 , u 11 and at particle sizes above 500, u 3.

Example 8

100 parts of dimethyl terephthalate, 64 parts of ethylene glycol, 0.015 part Calcium acetate and 0.035 part of triphenyl phosphite were placed in a reaction vessel. The resulting mixture was heated to 170 ° C. The temperature was increased from 170 ° C to 230 ° C over 3 hours. The reaction was continued at this temperature for 2 hours with stirring to the To undertake ester exchange reaction. The ester exchange was calculated from the amount of methanol distilled off, 97.8%.

This ester exchange reaction product was transferred to a second reaction vessel connected to the first reaction vessel 3 through a pipe was. The polycondensation was then carried out.

In the polycondensation reaction vessel, that was made of stainless steel produced inner surface of the autoclave by explosion welding with connected to a plate made of pure metallic titanium. The stirrer was made from a round bar and a plate made of pure metallic titanium.

In this case was the calculated ratio of the polymer to the titanium surface area 1.14 g polymer / cm titanium surface.

The reaction temperature was 280 ° C and the stirring speed 60 rpm. The pressure was reduced to 0.3 mm Hg in 2 hours. With these Conditions, the reaction was continued for 4 1/2 hours and then stopped. The extruded polymer had an intrinsic viscosity LT | J of 0.64, a carboxyl group number of 23.5 and a melting point of 262.5 ° C. The polymer obtained was completely colorless.

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• f f r f I * f * · ■ * ■ '

\ \ <'tt ι f I »t

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This is done by polycondensation in a stainless steel autoclave Control polymer obtained in the presence of 0.04% antimony trioxide was dark-yellow-green colored.

The color tone of the polymer obtained in this example was that very much superior to the control polymer. In particular, this should Variation in which both polymers split into chips, thorough dried and then transferred to test tubes and placed under nitrogen for 2 hours gas were heated from atmospheric pressure to 280 C, must be observed. The polymer obtained when using antimony trioxide was after When heated considerably after having turned yellow. The intrinsic viscosity had been lowered from 0.66 to 0.54. The carboxyl group number was has been increased from 19.8 to 32.4. On the other hand, it was according to the invention obtained polymers, the intrinsic viscosity was only slightly lowered from 0.64 to 0.61. The number of carboxyl groups varied from $ 2.5 to 25.8 Finally, the polymer obtained was practically colorless. "

Example 9

The ester interchange reaction product of Example 8 was placed in an apparatus for continuous polycondensation, which consisted of a horizontal cylindrical reaction vessel made of metallic titanium and which was provided with a set of screws for stirring and circulating the polymer. The reaction vessel was heated to 290 ° C. The cooking in the reaction vessel was pulled off to create a vacuum and the screws were rotated. The feed rate of the Esteraustauschreaktlonsproaukteb and the decrease rate of the polymer was eingestelft so dad the Verweilzelt was 8 hours. The obtained polymer was formed into a string by a metering pump, cooled and then cut into chips.

The polymer had an intrinsic viscosity of 0.60 and a carboxyl group number from 19.2. It was colorless. According to the heat test according to Example 8, the polymer had a viscosity of 0.57 and a number of carboxyl groups from 23.4. It was colorless and had excellent heat resistance.

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Example 10

100 parts of methyl terephthalate, 65 parts of ethylene glycol, 0.02 part Zinc acetate and 0.03 part of tri-phenyl phosphite were in one with a Given a stirrer equipped glass reactor. The resulting mixture was heated under a nitrogen gas atmosphere to effect the ester interchange reaction to undertake. The temperature was increased from 170 ° C. to 230 ° C. over a period of 7 hours to distill off the methanol, and the ester interchange reaction was stopped. The ester exchange reaction was calculated from the distilled amount of methanol to 98.0%. Then a certain The amount of the ester interchange reaction product obtained was placed in a cylindrical glass reaction vessel equipped with a stirrer. The blade of the stirrer was made of a titanium alloy plate. The titanium: nickel ratio in the alloy was 80:20 in the plate was drilled with a large number of pores with a diameter of 4 mm. The whole was melted under nitrogen gas at 230 ° C, whereupon the temperature was increased to 280 ° C. with stirring. Then the Pressure decreased to 0.35 mm Hg within an hour. In this state, the reaction was continued in vacuo. After 3 3/4 hours the polycondensation reaction was complete. The polymer obtained was from a lower part of the reaction vessel is extruded under nitrogen pressure, to get samples. The polymer was practically colorless and transparent and had an intrinsic viscosity of 0.71 and a number of carboxyl groups of 25.7 and a melting point of 260.5 C.

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Claims (12)

Claims 1 . Process for the preparation of polyacrylic terephthalates and modified ones Polyesters consisting mainly of polyalkylene terephthalate, characterized in that metallic titanium is used as the catalyst for the polycondensation. 2. The method according to claim 1, characterized in that the metallic titanium is used in finely divided form with average particle sizes of less than 100 u . 3. The method according to claim 1, characterized in that that the titanium in finely divided form with average particle sizes used at a maximum of 30 / rev. 4. The method according to claim 1, characterized in that that the metallic titanium in finely divided form with average Particle sizes of at most 3 / U are used. 5. The method according to claim 1, characterized in that that the metallic titanium can be found in the form of blocks, plates, chips, Chips, ribbons, fine or coarse granules, fine wires, nets or small balls are used. 6. The method according to claim 1, characterized in that that the metallic titanium is used as coarse granules with an average particle size of not less than 100 / rev. 7. The method according to claim 1, characterized in that that the metallic titanium as coarse granules with an average Particle size of not less than 200 / U is used. 8. The method according to claim 1, characterized in that that the metallic titanium as coarse granules with an average Particle size of not less than 500, µ is used. 909844/1759 -26 - 9. The method according to any one of claims 5, 6, 7 and 8, characterized in that the catalyst of the polymer according to the polymerization separates. 10. The method according to claim 1, characterized in that that at least a part of the reaction vessel or the accessories that come with the reaction mixture come into contact, made of metallic titanium or an alloy consisting mainly of metallic titanium are. 11th Method according to Claim 1, characterized in that that the carbon number of the alkylene of the polyalkylene terephthalate is 2 to 6 amounts to. 12. The method according to claim 11, characterized in that that the polyacrylic terephthalate is polyethylene terephthalate. 909844/1759