DE1645394A1 - Process for the production of polyesters, in particular of linear polyethylene terephthalates - Google Patents

Description

Description "Process for the production of polyesters, in particular of linear polyethylene terephthalatesl '.

The invention relates to a process for the production of polyesters existing polymers, especially of polyethylene terephthalates, which are known in the production of, inter alia,

Synthetic fibers suitable for shirt and fleece fabrics are used. Also as starting materials for the production of films, tapes, pressed powders, as well as the compounds mentioned are known to other commercial products.

These polyesters are produced in particular in that a Glycol, which generally contains 4 to 10 carbon atoms, with derephthalic acid or one of their dialkyl esters is reacted under suitable conditions will. In particular, ethylene glycol is used to produce polyethylene terephthalate used that with terephthalic acid or preferably with dimethyl terephthalate implemented will. The reaction product of glycol and terephthalic acid or preferably their dialkyl ester (in which case the reaction is called transesterification), namely the bis (hydroxyalkyl) terephthalate, is usually not isolated, but polycondensed, d. H. right away to form the desired Polymerized.

It is for the subsequent spinning and transformation of this polyester required in spun threads and fibers with good mechanical and textile properties, that the polyester has special characteristics, such as viscosity, fluidity, tea color etc. as regards.

In particular, it is considered extremely important and essential that in the polymerizations to obtain polymers which are to a high degree colorless or white are, this feature during the spinning of the polymer to elementary and Filaments should be retained as it is for the best and full recovery of the threads for the production of the articles mentioned is necessary that they have a very light coloring, especially a very high degree of whiteness.

Numerous compounds, in particular phosphorus compounds, brought up the one proposed, the color of the implemented during the procedure Substances have a stabilizing effect against possible harmful discoloration, i.e. the appearance of undesirable, more or less yellow or dark colorations prevent, which are caused, for example, by metal compounds can, which are present as catalysts in the reaction mass, or by such side reactions occurring in the course of the process can be generated. The catalyst mentioned is used in the polymerization reactions leading to polyesters used to do the same within reasonable and economically acceptable times to be able to perform.

It has been shown, however, that it is generally known with these Means do not succeed in the case of the polymers produced in the manner described To achieve a degree of whiteness, which currently appears to be desirable in this area.

According to the invention, a group of organic stabilizing compounds has now been established determined which have the ability to a high degree, through the said To give the polymer obtained from polycondensation an extremely high degree of ice, the formation of undesirable discoloration, as is generally caused by metal compounds or at least caused by the side reactions mentioned and to maintain this whiteness in the phases following said polymerization. The invention thus makes it possible to obtain threads and yarns, which not only have the mentioned good mechanical and textile properties, but also are to a large extent white.

Besides these surprising advantages with regard to the degree of whiteness the polymer and the threads and yarns obtained from it make the connections according to the invention, as could be determined, also has the further advantage that when using them, the entire polymerization process (where under this term also includes the phase of the preferably carried out as described above Transesterification should be understood as included) in a noticeably shorter Time is allowable than it takes to complete the polymerization is when working without the compounds according to the invention.

This shortening of the time required is especially important then noticeable when in itself ineffective and long Response times polymerization catalysts such as zinc borate (Zn3 (B03)) are used will. In the latter case, the entire polymerization process extends without Addition of the new stabilizing compounds according to the invention over a period of time those for the economic viability of the industrial manufacturing process normally exceeds acceptable limits, so the process using this catalyst is practically difficult to carry out.

The addition of the new stabilizing compounds, however, allows to complete the process within an economically advantageous time.

The compounds determined according to the invention consist of alkali or alkaline earth salts of organic sulfonic acids of the formula R-SO H, in which R is an unsubstituted one or substituted alkyl or aryl radical. Preferably the rest R by one or more, esterified or unesterified hydroxyl or carboxyl groups substituted.

The compounds determined according to the invention can be used in very small amounts Proportions between 005 and 0.5 mol%, calculated with reference to those present Terephthalic radicals can be used. Preferably they are used in amounts of 0.1-0.2 Moles (calculated as set out above) are used. The invention is thus also possible recognized, the stabilizing compounds mentioned in surprisingly small amounts to be used, although these quantities permit, an extremely strong, unexpected one To achieve stabilizing effect.

The connections can @ at any stage of the establishment of the polymer, i.e. during the transesterification, at the start the polymerization and also during the latter, provided the polymerization is not driven beyond a certain hatred, i.e. the reaction mass has a basic viscosity from 0.25-0.30 (calculated by dissolving 0.5 g of the product in 100 cm3 of a solution of 60 parts of phenol and 40 parts of tetrachloroethane at 200C) is not exceeded Has.

When the stabilizing sulfone compound has no functional groups that make them suitable for participation in the polymerization, then they can regardless of the mass of the reacting products in the first stage of the polymerization process or added in the second stage, i.e. the actual polymerization stage provided that the above condition with regard to the viscosity is met.

If, on the other hand, the stabilizing sulfone compound has functional groups which could take part in the polymerization, then the addition of the Compounds according to the invention preferably during transesterification, for example at the start of the same or at least before the start of the actual polymerisation. Although the experiments carried out so far did not allow us to see exactly The form in which the compounds mentioned are present in the polymer can still be seen Assume that there is the addition of the stabilizer if it is before the start of the actual polymerization occurs, the stabilizer allowed to work together to polymerize with the monomer, i.e. with the bis (p-hydroxyalkyl) terephthalate and to give mixed polymers, graft polymers, etc., which are extremely white.

The stabilizing effect of the functional groups mentioned containing compounds is also very good and durable if they are used during the actual polymerization are introduced into the reaction chamber, provided the basic viscosity has not exceeded the value of 0.25-0.30.

The invention and its purposes are explained below with the aid of some non-limiting examples explained in more detail.

Example 1 A mixture of 60 parts of dimethyl terephthalate, 70 parts Ethylene glycol, 0.030 part of zinc acetate and 0.030 part of antimony trioxide is in introduced into a polymerization apparatus equipped with a distillation column.

At the same time 0.12 g of 3,5-dicarbomethoxybenzenesulfonate are added to the reaction mixture (corresponding to 0.124 moles per 100 moles of dimethyl terephthalate that were incorporated).

The heating then begins in a nitrogen atmosphere, the temperature gradually increasing from 1600 to 180 ° C over 3 hours and over 1 hour is increased from 1800 to 2200C until the result of the ester interchange reaction Methanol is completely distilled. Then the temperature becomes gradual in 30 minutes increased to 2750C and the ethylene glycol <1 excess distilled off. The apparatus is now placed under vacuum, the pressure gradually being reduced to 1 mm and the product is left to react at 2750 for 4 hours.

At the end of the polycondensation, the polymer is in a molten state practically colorless. Owns in solid condition it is an excellent dazzling white color.

The polymer obtained also has the following characteristics: intrinsic viscosity = 0.63 (calculated in a phenol-tetrachloroethane solution (60/40) in one concentration of 0.5 / 100 om3 at 2000) Melting point = 25800 Melt index = 0.68g / 10 minutes (in which one at 2700C with a spinneret of 0.5 mm diameter under a weight of 2160 g works) number of COOH equivalents (based on 106 g polymer) = 56.

The product can easily be converted into fibers by conventional methods the good mechanical and textile properties on the outside are excellent are white in color.

For comparison, an experiment analogous to the one described is carried out, merely omitting the addition of the sulfonate and the duration of the treatment at 27500 is extended to 5 hours under high vacuum.

The polymer obtained in this way has a characteristic in the molten state honey-yellow color that obviously remains even after solidification. It also has the following features that are comparable to the features given above Basic viscosity = 0.65 Schielzpunkt = 2609C melt index = 0.60 g / 10 minutes the COOh equivalents of 106g polymer = 63.

BoiPieSl 2 Regarding the apparatus used, the Reaction mixture and the working conditions of the same experiment how carried out described in Example 1, only that the 3, 5-dicarbomethoxybenzenesulfonate (in an amount of 0.124 mol% based on the dimethyl terephthalate) in the form of a 5% solution in Aethylengl @ kol at 1000C after 30 minutes of the reaction mixture the system was brought to the maximum vacuum (1 mm Hg), i.e. practically after already used polycondensation with a basic viscosity of the reacting one Product of 0.2 is added. The polycondensation is then described in the Way continued.

The polyester obtained is compared to that obtained according to Example 1 becomes, a little less white, but compared to that, under the same conditions without Standard polyester obtained with any addition is decidedly whiter.

The other characteristics of the polymer obtained are as follows: intrinsic viscosity = 0.62 Melting point = 256 ° C Melt index = 0.77 g / 10 minutes Number of COOH equivalents of 106 g of polymer = 66 / example 3 In a polymerization provided with a distillation column Glass jars are introduced 30 parts of dimethyl terephthalate and 35 parts of ethylene glycol 0.015 part zinc acetate 0.015 part antimony trioxide 0.0405 part (0.125 mol./100 mol Methyl terephthalate) p-toluene potassium sulfonate The mixture is under nitrogen 3 Heated for hours, the temperature gradually increasing from 160 ° to 220 ° C will.

During this period of time, that which arises from the ester exchange develops Methanol.

The pressure is then gradually reduced to 1 mm Hg and the temperature increased to 275 ° C. Under these conditions, the reaction mass lasts for 4 hours left.

The polymer obtained has a good white color with a slight gray Stitch, but without any trace of the distinctive yellow color of the same Working conditions, however, obtained without the addition of polyester. It also has the following characteristics basic viscosity = 0.66 melting point = 2580C melt index = 0.58g / 10 Minutes number of COOH equivalents / 106g polymer = 48.

Example 4 An experiment is carried out using the same apparatus, the same respondents and under the same working conditions as in Example 3 carried out, except that the compound 1-hydroxypropane-3-sodium sulfonate in an amount corresponding to 1 mole per 1000 moles of the introduced dimethyl terephthalate is used.

The polymer obtained has a good degree of wisdom and possesses following characteristics basic viscosity = 0.60 melting point æ 253 ° C melt index = 0.66 g / 10 minutes.

Example 5 In a separate test polymerization vessel with 30 liters Capacity the following reactants are introduced 8000 g of dimethyl terephthalate (DMT) 6400 g ethylene glycol 0.015% by weight zinc acetate (based on DMT) 0.02% by weight Sb2O3 (based on DMT) 0.4% by weight TiO3 (matting agent) (based on DMT) and the following sulfonate additive: 2,5-dicarbomethoxybenzene sodium sulfonate, in one Amount corresponding to 0.10 mol% based on DMT.

The T @ ans esterification is carried out in 8 hours, during which Time the temperature is gradually increased from 1500 to 220 ° G.

The reaction mixture is then gradually placed under vacuum, that assumes values of <0.5 mm Hg residual pressure within 2 hours.

The polycondensation is then carried out while maintaining these vacuum values and the temperature of 2650C for 3+ hours.

The polymer obtained is excellent in white and has the following Characteristics Basic viscosity = 0.63 Melting point = 25500 Melt index = 0.54 g / 10 minutes Number of COOH equivalents / 106g polymer = 47.

Example 6 It is done using the same apparatus, the same Reaction participants and under the same conditions as in Example 5 an experiment carried out, but as an additive to prevent unwanted discoloration the compound p-carbomethoxybenzene calcium sulfonate in amounts corresponding to 0.950 mol is used per 1000 moles of DMT introduced.

The polymer obtained is excellent in white and has the following Characteristics Intrinsic viscosity = 0.60 melting point = 2530C melt index = 0.76 g / 10 minutes Number of COOH equivalents / 106 g polymer = 44 Example 7 A mixture of 8,000 g of dimethyl terephthalate and 6400 g of ethylene glycol is poured into the reaction vessel of the previous example together with zinc borate (0.03 wt.% Based on DMT) as Catalyst both the transesterification and the polycondensation, as well as with the compound 3,5-Dicarbomethoxybenzen-ka liumsulfonat (0.150 mol J based on DMT) introduced as a stabilizer against undesired colorations.

The procedure is the same as that described in Example 5 carried out only that the treatment was carried out in a high vacuum at 27500 for 4 hours will.

The polymer thus obtained is satisfactorily white and has the following characteristics: basic viscosity = 0.62 melting point = 2580C melt index = 0.65 g / 10 minutes number of COOH equivalents / 106 g polymer = 58.

This polymer can easily be made into fibers by conventional methods convert which the usual excellent mechanical properties of polyester and are also perfectly white.

The experiment is then repeated in the manner described, hhne that the sulfonate compound is added; The process requires a total of a time longer by 3 hours, namely the transesterification 2 hours and the Polycondensation 1 hour more.

The polymer obtained has an intense yellow color, while its other characteristics are comparable to those of the experiment described.

Claims (8)

PATENT CLAIMS Process for the production of polyesters, in particular of linear polyethylene terephthalates, with a light color and an excellent degree of whiteness, in this way it is noted that the reaction mixture becomes an arbitrary one Time of production of the polymer at which the intrinsic viscosity of the reactants has not exceeded the value 0.25-0.30, | compounds to prevent discoloration consisting of alkali or alkaline earth salts of organic sulfonic acids of the formula R-S0 H are added, in which the radical R 3 is a substituted or unsubstituted one Is alkyl or aryl. 2) Method according to claim 1, characterized in that g e k e n n n z e i c hn e t, that the radical R of the erabilizing compound consists of an alkyl or aryl from one or more, esterified or unesterified hydroxyl or carboxyl groups consists. 3) Method according to one of claims 1-2, characterized in that g e k e n nz e I assure that the stabilizing compounds are based on molar proportions of 0.05-0.5% to be added to the terephthalates present in the reaction mixture. 4) The method according to claim 3, characterized in that g e k e n n n z e i c hn e t, that the stabilizing compounds are based in molar proportions between 0.1% and 0.2% are added to the terephthalate residues present in the reaction mixture. 5) Method according to one or more of claims 1-4, characterized in that g e k e n n n e i n e t that the stabilizing compound 3, 5-dicarbomethoxybenzene sodium or potassium siffany is used. 6) Method according to claims 1-4, characterized in that p-toluene sodium or potassium sulbnate is used as the stabilizing compound. 7) Method according to claims 1-4, thereby g e k e n nz e i c h n e t that the stabilizing compound 1 ', 1-hydroxypropane-3-sodium or potassium sulfonate is used. 8) Method according to one or more of the preceding claims, in this way it is not indicated that a glycol is used in polyester production that contains 2-10 carbon atoms is used. g) method according to claim 8, by noting that ethylene glycol is used as the starting material and dimethyl terephthalate were used, 10) polymer products and threads or Yarns made using the method according to one or more of the claims 1-9 were obtained.