DE1023885B - Process for the preparation of high polymer polymethylene terephthalates - Google Patents

Description

GERMAN

The invention relates to an improved process for the preparation of high polymer polymethylene terephthalates and in particular of polyethylene terephthalate.

The high-polymer polymethylene terephthalates are linear polyesters, which are used as fiber and film-forming substances are very important. They are going through a polycondensation reaction by heating a derivative of terephthalic acid that is capable of working with itself to carry out a condensation reaction, for example prepared from bis (hydroxyalkyl) terephthalate. The derivative of terephthalic acid can be prepared by any known method, e.g. B. by reacting a glycol with terephthalic acid or by an ester interchange reaction using of a glycol and an ester of terephthalic acid or by reacting an alkylene oxide with terephthalic acid.

Of the high-polymer polymethylene terephthalates, which are derived from ethylene glycol and terephthalic acid, Polyethylene terephthalate is best known in the trade as a fiber and film-forming substance. at is the manufacturing process commonly used to make polyethylene terephthalate the first stage is an ester exchange reaction between ethylene glycol and dimethyl terephthalate, whereby bis (/ S-hydroxyethyl) terephthalate is formed. This compound is then subjected to polycondensation under reduced pressure and at a high temperature. Another method of making polyethylene terephthalate is that of ethylene oxide and terephthalic acid is assumed. Bis - (/? - hydroxyethyl) terephthalate is also formed here, and this is subjected to polycondensation.

In order to carry out the production of these linear polyesters in a useful time, it is necessary to have one Apply catalyst. Many catalysts have been proposed for this purpose, but have been found that those which result in high manufacturing speed also high speed bring about polymer degradation. Another disadvantage is that many of the known Catalysts produce a polymer that has a yellowish color or a cloudy appearance. In the preparation of of fibers it is desirable to have a coloration as close as possible to white, and in the case of the Making films requires a clear light-colored polycondensate.

The invention now relates to an improved process for the production of high-polymer polymethylene terephthalates, whereby bis (hydroxyalkyl) terephthalates are polycondensed and that is characterized is that the polycondensation reaction is carried out with an antimony compound as a catalyst, which is soluble in the reaction mixture. In particular, the invention relates to such a method of manufacturing

for the production of high polymers
Polymethylene terephthalates

Applicant:

Imperial Chemical Industries Limited,
London

Representative: Dipl.-Ing. A. Bohr, Munich 5,

Dr.-Ing. H. Fincke, Berlin-Lichterfelde, Drakestr. 51,

and Dipl.-Ing. H. Bohr, Munich 5, patent attorneys

Claimed priority:
Great Britain February 27, 1953 and February 10, 1954

Norman Fletcher, Blackley, Manchester

(Great Britain),
has been named as the inventor

position of polyethylene terephthalate from bis (j8-hydroxyethyl) terephthalate.

Antimony compounds which can be used in the process forming the subject of the invention, include: salts of antimony and inorganic or organic acids, double salts such as potassium antimonyl tartrate, and salts of antimonic acids such as potassium pyroantimonate. An antimony salt, which is excellent Acetate is obtained by reacting antimony trioxide with acetic acid. In practice it was found that it is not necessary to separate the salt as the mixture is dissolved in acetic acid in glycol and can then be added directly to the reaction vessel prior to the polycondensation reaction. Antimony oxide can also be used as a catalyst in the process forming the subject of the invention, however special care must be taken when using this catalyst because this substance is not as soluble as the one given above and he can separate himself.

The antimony compound to be used should be one that does not attack the reaction vessel. So it is preferred Do not use salts of strong acids, such as sulfuric, nitric and hydrochloric acid, as in this case through Hydrolysis of these salts can liberate acid and this easily attacks the reaction vessel. This disadvantage exists less if the acid produced by hydrolysis is volatile, as is the case with hydrochloric acid. If further-

7OS 878/293

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added salts of non-volatile strong acids (by heating 0.0153 parts of Sb ₂ O ₃ with 0.016, the presence of acid ions in the re-parts of acetic anhydride, 0.5 part of ethylene glycol action mixture are added to the course of the polycondensation and boiling until a reaction is affected. For this reason, it is preferred to obtain a clear solution) instead of antimony tri-antimony salts of acids that contain an ionic fluoride. The reaction time at 280 ° and less than sationskonstante of not more than 10 have ^1, as 1mm pressure is 3 ¹ Z ₃ hours. It becomes a clear hydrofluoric or acetic acid. light-colored polymer with an intrinsic viscosity of 0.77

In order to achieve that an almost white polymer is obtained which is used for the production of thin films or for hold, the amount of the catalyst used should be suitable for textile processing. be such that the final polyester is less than 0.05 io
Contains percent by weight of antimony metal. Example 3

If the first stage in the production of the high poly- 100 parts of dimethyl terephthalate and 70 parts of ethylene

meren polymethylene terephthalate an ester exchange glycol are used under oxygen-free conditions, i. H. reaction is, d. H. when the polyethylene terephthalate is melted under a nitrogen atmosphere. At a from glycol and dimethyl terephthalate as starting materials J-5 at a temperature of 150 °, 0.08 parts of calcium acetate are obtained it is preferred that in addition to and 0.02 part of antimony trichloride added in 1 part the antimony compound still has an ester interchange catalyst ethylene glycol dissolved.

is used. Such catalysts are widely known in the ester interchange is known within a temperature range, but it has been found that in the range of 160-215 ³ at atmospheric pressure application of calcium acetate along with the anti-20 is carried out. Methanol is distilled off and the Remo compound polyester having a good color corresponds action is completed in about 3 _^3/4 hour, standing while zinc acetate is particularly useful when the resulting bis (hydroxyethyl) terephthalate

bright clear polymers are to be produced. Although in a stainless steel made of poly-antimony compounds per se no ester interchange cata- merization vessel, as described in example 1, overlysers represent, they can generally already run 25, 0.5 parts of titanium with dispersed in ethylene glycol the ester exchange catalysts, if desired, dioxide are added, and the mass is in the im can be added. Care must be taken with antimony salts, polycondensed in the manner described in Example 1, that the acid radical is not the ester interchange catalyst In this case the polycondensation occurs at 1 mm

fails. If during the production of polyethylene tere- pressure and a temperature of 285 ^{C for} 2 hours phthalate bis (/ 3-hydroxyethyl) terephthalate carried out as starting 30. The intrinsic viscosity of the delustered polymer material used, the antimony compound was 0.66. This product was particularly suitable for being added to the molten bis (/ S-hydroxyethyl) terephthalate in order to obtain such webs via melt spinning. It is often advantageous to add the antimony catalysts, which are suitable for the production of textile yarns, to a solution in a glycol. . .

In the following examples, parts are parts by weight. 35 ice cream pie

. The procedure described in Example 3 was

Example 1 repeated with the exception that 0.03 part of antimonyl

100 parts of bis-hydroxyethyl terephthalate are used under potassium tartrate instead of antimony trichloride non-oxidizing conditions, d. H. were under one stick, and the implementation was in a larger one Substance atmosphere, melted and on a 5 liter 40 scale using a 350 liter Stainless steel vessel entered, carried out with a receptacle. The ester interchange took place in a 7 hour stirrer is equipped and the two connections take the 40 minutes. The polycondensation was at one of which was carried out at the top with a vacuum of 280 °, and the total conversion time was pump is connected and the other on the floor is 7 hours from the first application of the vacuum is closed. The melted mass is at 24 to 45 and 15 minutes. The de-glossed product had an inner one run stirred per minute and 0.0187 parts antimony viscosity of 0.70. trifluoride added, whereupon the temperature so quickly. .

is increased as possible. Glycol distilled over and becomes Example 5

collected. When the temperature reaches 245 °, the procedure of Example 3 was followed

The vacuum pump is activated and the pressure is reduced with 50 of 0.015 parts of zinc acetate and 0.035 parts of potassium at such a rate that a pressure of pyroantimonate instead of calcium acetate and antimony of 1 mm is achieved when the temperature repeats 270 to trichloride. In this case, no titanium 275 ° was reached. The reaction is then continued at 278 °, added dioxide. The ester exchange was after 3 ^{1 2} ₄ hours and a pressure of less than 1 mm is ended for 2 ¹ _{2 3} hours. The polycondensation time is maintained at a temperature, whereupon the stirrer is set to a temperature of 275 ^: and a pressure of less than 1 mm, the vacuum pump is switched off and it was 3 ³ Z ₄ hours. A clear, pale polymer headspace was obtained above the molten polymer with an intrinsic viscosity of 0.79, which is filled with pressurized nitrogen. When opening, making a thin film or for spinning to the bottom outlet, the melted polymer is made of fine fibers which was suitable for textile processes. squeezed out the nitrogen pressure, quenched in water, 60
dried and cut into chips. Example 6

The product is a clear, light-colored polymer which The procedure of Example 3 was repeated and

has a softening point of 263 ° and an internal one using 0.015 parts of zinc acetate and Viscosity of 0.74 (determined in o-chlorophenol). This 0.0245 parts of antimony trifluoride instead of calcium product is particularly suitable for the production of acetate and antimony trichloride. In this case there was no thin films or spun threads for textile threads. Titanium dioxide added. The ester interchange was after

. . 3 ¹ Z ₄ hours ended. The polycondensation time was

eispie - k _e - 275 "and a pressure of less than 1 mm l ^B / ₆ hours

The procedure described in Example 1 is carried out under the. It became a clear light-colored polymer with an interior Applying 0.0275 parts of antimony acetate produced 70 viscosity of 0.74 obtained which is used to produce a

5 6

thin film or for spinning into fine fibers for catalyst. At the end of the ester interchange reaction were

Textile process was suitable. 0.5 parts of titanium dioxide dispersed in ethylene glycol

_. . placed before the monomer in the polymerization vessel

.Example / was transferred. After 2 ¹ Z ₂ hours of condensation

The procedure of Example 3 was repeated and 5 sized at 280 ° under a pressure of less than 1 mm although using 0.015 parts of zinc acetate and the mass was pressed. The product had a

0.0343 parts of antimony acetate, prepared as in Example 2, inherent viscosity of 0.65, but had a dirty color Place of calcium acetate and antimony trichloride. In cream color.

in this case no titanium dioxide was added. Of the .

Ester exchange was over after 3 ^{1 and} ₄ hours. The poly- io example l "

condensation time was at 275 ° and a pressure of. The procedure of Example 1 was followed

1 mm 2 hours. A clear, pale polymer was obtained with 0.0187 parts of antimony trioxide instead of antimony

Obtained an intrinsic viscosity of 0.68, which is dispersed in ethylene glycol to the hydrofluoride and 0.4 parts

formation of a thin film or for spinning into titanium dioxide repeated. The reaction time was

fine fibers was suitable for textile processes. 15 280 ° and under a pressure of less than 1 mm

ü. . , ο 2 ¹ I ₂ hours. It became a white delustered polymer

"with an intrinsic viscosity of 0.68, which in

The procedure of Example 3 was repeated, and fiber form is suitable for the manufacture of textiles.
although using 0.0215 parts of zinc antimonate.
instead of calcium acetate and antimony trichloride. In 20 example 1.5
in this case no titanium dioxide was added. The The process described in Example 3 was re-Esteraustausch was by 4 ¹ / ,; Hours ended. The poly obtained, with the exception that 0.02 parts of antimony trioxide, condensation time was at 278 ° and a pressure of dispersed in ethylene glycol, in place of antimony is less than 1 mm 3 _^5/12 hour. A clear trichloride was applied. The Esteraustausch.behelles polymer having an intrinsic viscosity of 0.74 ER-25 treatment carried out _{for 2} hours in 3 ¹ Z. The hold out, the existing polymerization vessel for the production of a thin film or stainless steel for spinning into fine fibers for textile processes was equipped with a stirrer, which was suitable for 40 revolutions. per minute. The vacuum polycondensation example 9 treatment took place at a pressure of less than 1 mm

30 within I ¹ Z ₂ hours. The white de-glossy polymer

The procedure of Example 3 was repeated and it had an inherent viscosity of 0.67.
although using 0.015 parts of zinc acetate and _. . .
0.0354 parts of antimony matrix fluoride. In this case example 14
no titanium dioxide was added. The ester interchange The procedure of Example 3 was repeated and was completed after 4 hours. The polycondensation time of 0.015 parts of zinc acetate and 0.02 parts at 275 ° and a pressure of less than 1 mm of antimony trioxide, which were dispersed in glycol, was 3 ^{2 and} ₃ hours. It became a clear pale polymer with a spot of calcium acetate and antimony trichloride. Obtained with an intrinsic viscosity of 0.73, no titanium dioxide was added for the preparation of this case. That of a thin film or ester interchange too fine for spinning was completed in 3 hours. The poly fibers were suitable for textile processes. The condensation time was 40 at a temperature of 275 °

. -I ₁ H ^{un (} ^ ^emem pressure less than 1 mm 2 ¹ Z ₂ hours. It

- Example IU became a clear polymer with an inherent viscosity

The procedure of Example 3 was repeated using the same procedure as described for the preparation of a thin film and

Use of 0.1 part calcium acetate and 0.02 part for spinning into fibers for textile processing

powdered antimony metal. 45 makes it suitable.

The ester interchange reaction was completed in 4 hours
ends, and at the end of this time the antimony metal remained essentially undissolved. The procedure of Example 3 is repeated with the

The resulting bis-2-hydroxyethyl terephthalate exception that 0.01 part of manganoacetate dissolved in ethylene was transferred to the stainless steel poly-glycol, and 0.01 part in ethylene glycol, and then transferred to the Antimony trioxide polymerized in place of calcium acetate and game 1 described manner. After 3 ³ Z ₄ stuntmon trichloride were used as catalysts. The vessel with a capacity of 275 to 280 ° C and an ester exchange was maintained after 7 ¹ Z ₃ hours in a 350 1 pressure of less than 1 mm, ended.

the mass was squeezed out. The product was water-clear, 55 No delustering agent was added, and the

however, the intrinsic viscosity was only 0.43. Polymerization took place at a temperature of 280 °

This example shows that when applying An it is within 7 ¹ Z ₂ hours of the first application

timonmetall versus soluble antimony compounds in the vacuum. The polymer was a clear light colored product,

according to the invention is not possible in a need- which has a softening point of 263.5 "and an internal one

time to obtain a polymer which had an intrinsic viscosity of 0.70.

Has viscosity that is high enough to get out of this. -I ₁ ^

To be able to manufacture product fibers and films, d. H. Example 16

an inherent viscosity greater than 0.60. The procedure of Example 11 was repeated, and

. -I ₁₁ using 0.02 parts of antimony trioxide

Example 11 _{6s to control the 002} parts of antimony metal. At the end of

This example illustrates the use of litharge ester interchange reaction; H. after 4 hours, it is

as a catalyst in contrast to the whole amount of the antimony trioxide according to the invention gone into solution,

applied catalysts. After a polymerization at 275 to 280 ° and one

The procedure of Example 4 was repeated, and pressure of less than 1 mm, extending over I ¹ Z ₄ hours

while extending than 70 using 0.017 parts of litharge, the mass was squeezed out. The product

had an inherent viscosity of 0.66, but had one pale gray tint.

The intrinsic viscosity η is determined in solution in o-chlorophenol at 25 ° and serves as a measure of the degree of polymerization. It is calculated using the formula

where n _{s is} the specific viscosity, ie

Outflow time of the solution Outflow time of o-chlorophenol

IO

1,

and c = concentration of the solution in g per 100 ecm.

It is advantageous that in a process with ester ¹ S, the catalyst exchange reaction soluble in the glycol. The salts and double salts of antimony are particularly suitable in such processes in which polyethylene terephthalate is to be produced, since they are readily soluble in ethylene glycol.

When in the production of high polymer polymethylene terephthalate from the bis (/? - hydroxyalkyl) terephthalate is assumed, the catalyst must in be soluble in the molten ester. Examples 1 and 2 illustrate the use of antimony salts for such a procedure.

When using the catalysts according to the invention, it has been found possible to use high polymer To produce polymethylene terephthalates with a high molecular weight and good coloration at times which are useful for industrial production.

The present invention relates to a method in which an antimony compound is used as a catalyst for the purpose of producing polymeric products with good coloration and high intrinsic viscosity. The antimony can be in the form of a salt or double salt. It is evident that there should be

The choice of the acid radical and also the choice of the other metal of the double salt should be done with care is to be used to avoid the inclusion of an acid radical or metal, which itself is the product to dye. It is well known that added nitrates easily discolor the products and that metal ions, such as Copper and iron, also cause discoloration.

Claims (5)

PATENT CLAIMS: 1. Process for the preparation of high polymer polymethylene terephthalates by polycondensation of bis (hydroxyalkyl) terephthalate, characterized in that an antimony compound is added to the reaction mixture added, which is soluble in the reaction mixture, the amount of added Antimony, based on the final mass, is optionally not more than 0.05 percent by weight. 2. The method according to claim 1, characterized in that the bis (hydroxyalkyl) terephthalate by ester interchange reaction in the presence of an ester interchange catalyst such as calcium or zinc acetate, is prepared and that the ester interchange catalyst during the polycondensation in the Reaction mixture remains. 3. The method according to claim 1 and 2, characterized in that the catalyst as a salt or double salt of antimony with an organic or inorganic acid whose ionization constant is less than 10 ^ ¹ , such as antimony acetate, antimonic acid, together with the exchange catalyst, dissolved in glycol , is added to the reaction mixture. 4. The method according to claim 1 to 3, characterized in that the antimony double salt is an alkali metal contains. 5. The method according to claim 1, characterized in that the catalyst is antimony trioxide. When the registration was announced, 1 priority document was displayed. © 709 878/293 1.58