DE2063841A1 - Film and fiber-forming linear polyesters with improved whiteness - Google Patents

Description

Cologne, December 21, 1970 Ke / Ax

Fiber Industries, Inc., Charlotte, North Carolina (USA ),

Film and fiber forming linear polyester rr.it improved V / egg 3 ton

The invention relates to film- and fiber-forming linear synthetic polyesters with improved whiteness.

Linear synthetic polyesters, especially polyethylene terephthalate, are known to have found their way into technology and consumers to a large extent. However, numerous attempts have been made to use modified polyesters, especially modified polyethylene terephthalate, with improved properties to manufacture »to the benefit and inclusion of the linear synthetic Polyester continues to increase among consumers. Are representative of these improved properties improved thermal stability, substantial removal of diglycol, improved dyeability with dyes of various types and improved shade of white.

The whiteness of polymers is particularly important when the linear synthetic polyesters are made into threads and fibers for fabrics and clothing. For these end uses, white filaments and fibers are both Outwardly desirable for both aesthetic and practical reasons. An improved shade of white results in both

109827/1982

Fabrics al3 also with items of clothing are white goods Consumers are finding their way to a greater extent. This factor is important enough for a separate whitening to justify fabrics made from yarns with an impure shade of white. Even if the yarn is called If fabric is to be dyed, a high degree of whiteness or shade of white is desirable because yarns that have an impure color show, lead to dyed goods with impure color. White yarns thus greatly simplify quality control and adjusting the coloration or mimicking of the tone in dyed goods while those above called bleaching is required for yarns that are not pure white in color. Fibers also contribute unclean white fabrics made of polyester or polyester / cotton a streaky (reeded out) or faulty processed (underconstructed) appearance.

Below the whiteness or whiteness of polymers is the degree of whiteness of that polymer (or fabric) in comparison to. to understand a ceramic tile as a reference sample. In practice this comparison is made with the help of an instrument (e.g. with a Hunterlab reflectometer " for white tone »model D-4Q) made the reflection of the sample and the reference sample. A quantitative expression is determined from the determined values, the indicates the degree of whiteness or the whiteness of the sample. The method is used elsewhere in this section described in detail. Preferably the products according to the invention have a whiteness of at least 70, measured with a Hunterlab reflector meter for White shade, model D-40, described elsewhere in this specification.

Various techniques have been used to improve the whiteness of linear synthetic polyesters. What stands out from these methods is the incorporation of additives to which copolymerizing

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"Bare monomers belong in the polyester. Frequently, however, was in cases in which an improvement in the whiteness has been achieved, another property, e.g. lightfastness, worsened.

The invention relates to modified polyesters After processing into fibers and fabrics, an improved shade of white without deterioration of the desired properties which contain unmodified polyester »

The invention also includes a method of making the modified polyesters having improved whiteness.

It has now surprisingly been found that an increase in the whiteness of linear synthetic polyesters in the range of $ 6 to $ 41 based on the unmodified polyester is achieved if a low Amount of a difunctional compound from the group 1,3-bis (2-hydroxyethoxy) benzene, 3- (2-hydroxyethoxy) phenol, lower alkyl esters of adipic acid, lower alkyl esters of suberic acid, lower alkyl esters of azelaic acid and lower alkyl esters of sebacic acid into which polyester is incorporated. Under "lower alkyl" are to understand aliphatic radicals with about 1 to 6 carbon atoms. Preferred of the above compounds 1,3-bis (2-hydroxyethoxy) benzene, bis (2-hydroxyethyl) azelate " and dimethyl azelate are used. Below a small amount of the compounds according to the invention are less than 5% by weight, based on the weight of the dicarboxylic acid or its bialkyl ester. Preferably be the compounds in an amount of 3 wt .-? 6 added. Generally, the addition occurs before a substantial one Polycondensation has taken place. The polyesters can be produced by direct esterification or by ester interchange will. If the production is by ester interchange, ester interchange catalysts are used Salts of transition metals of groups HB, VIIB and VIII of periods 4 and 5 of the periodic system ver-109827/1982

-A-

applies, with salts of manganese and cobalt being preferred.

The term "linear synthetic polyester" used here As a preferred class, it comprises polyesters based on terephthalic acid or its dialkyl esters. Stronger Preference is given to polyesters made from terephthalic acid or its dialkyl esters and a polymethylene glycol formula

HO (CH ₂ ) _n OH,

in which η is an integer from 2 to about 8 will. The polyester, polyethylene terephthalate, which is particularly preferred by this last-mentioned class, is obtained when η has a value of 2. In the context of the invention, the production of the polyester can be both by direct esterification of a dicarboxylic acid with a diol and subsequent polycondensation as well as by Ester exchange of a dicarboxylic acid dialkyl ester with a diol and subsequent polycondensation take place, however the latter process is preferred for the preparation of linear synthetic polyesters.

In the preferred method, i.e. for the ester exchange of a dialkyl dicarboxylate with a diol followed by polycondensation, is usually an ester interchange catalyst required to bring the ester interchange step to completion within a reasonable time. Surprisingly, it has been found that the Esterausta.uschkatalysator used the compounds according to of the invention in terms of improving the whiteness of the linear synthetic polyesters can. Accordingly, salts of transition metals of groups HB, VIIB and are used as ester exchange catalysts VIII of periods 4 and 5 of the Periodic Table (Robert C. Weast, "Handbook of Chemistry and Physics", 49th Edition, The Chemical Rubber Company, Cleveland, Ohio, 1968, page B-3) was used. Examples of such catalysts

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gates are manganese acetate, iron (III) acetate, iron (III) stearate, Iron (II) carbonate, cobalt acetate, cobalt formate, Lead acetate, lead oxide, zinc thioantimonate, zinc acetate, zinc cyanide, cadmium acetate and cadmium cyanide. Preferably salts of manganese and cobalt, in particular manganese and cobalt salts of aliphatic monocarboxylic acids with up to 6 carbon atoms used as ester exchange catalysts.

Apart from the reaction components, the abovementioned compounds according to the invention and an ester interchange catalyst various other materials can be present. For example, polymerization catalysts are common such as antimony trioxide, antimonic acid, germanium dioxide, tin (II) oxalate, organotin compounds and the like available. Antimony trioxide and antimonic acid are preferably used as polymerization catalysts. Furthermore, inhibitors that prevent discoloration, e.g. alkyl or aryl phosphate esters and alkyl or aryl phosphite esters, be used. You can also use pigments, matting agents such as titanium dioxide and other additives to be available. Preferably, the linear synthetic polyesters according to the invention are matted to the get the most out of the invention.

The fibers or threads produced according to the invention in endless form or as staple fibers are suitable for usual textile applications. You can work or Weaving of all kinds of products as well as for the production of fleece-like and felt-like products according to known ones Procedures are used. The physical properties of the modified fibers and threads are close with their corresponding unmodified polyester yarns. However, the modified yarns are different of the unmodified yarns with an increased shade of white,

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Example 1 . Preparation of the prepolymer

In a jacketed 18.9 l autoclave, which is heated with the aid of a Dowtherm steam system (heat transfer medium from Dow Chemical Comp, Midland, Michigan) and is provided with a stirrer and cooler, 13.6 kg of dimethyl terephthalate, 9 heated Xthylenglykol 8 kg and 5 _f 44 g cobalt acetate given The mixture v / ith at normal pressure under reflux. The temperature of the mixture is about 187 ° C when methanol begins to transfer. The methanol is completely distilled off after about 2.5 hours. At this time, the temperature has risen to about 22O ⁰ C. The mixture is extruded, cooled, ground and packaged. It is hereinafter referred to as cobalt prepolymer.

Manufacture of the polymer

750 g of cobalt prepolymer, 2.0 g of titanium dioxide, 0.54 g of a 50% solution of Trimethyl phosphite in ethylene glycol, 0.23 g of antimonic acid and 17.1 g of bis (2-hydroxyethyl) azelate are added. The autoclave is flushed with nitrogen and ^{heated to about 230 °} C. before the evacuation is started. After the end of the evacuation, which requires about 75 minutes, the batch is ^{polymerized for 70 minutes at 280 °} C. and 0.7 mm Hg. The batch is extruded in water. The polymer obtained has an intrinsic viscosity (Intrinsic Viscosity) of 0.562 dl / g and a melting point of 255 ⁰ C as determined by differential thermal analysis.

The term "size viscosity" used here is a Measure of the degree of polymerization of the polyester and can can be defined as

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"''' ¹ S ¹ ! ¹ ""Ί;*" fi ■'"■! ■■■ .'-. '. 1'! Il '■ 5 · ■ ■ ■: ■..„.,

^{1 ; 1} ί ■ '■: ■ »■■ ■■■' ■■■ ■■ ι?

- 7 -

(η - V

Limit as C approaches zero

Here \ is the viscosity of a dilute solution of the polyester in o-chlorophenol, ^ _{0 is} the viscosity of the pure solvent, measured in the same units and "at the same temperature as If, and C is the concentration of the polyester in g / 100 ml of solvent. The intrinsic viscosity is thus expressed in dl / g.

The melting points of the polymers mentioned in this example and in the following examples can easily be determined through thermal differential analysis (TDA), a well-known and widely used method, determine. A thermal differential analyzer, model 900, from duPont is used as the measuring apparatus. the Melting points are determined using a glass macro-sampling tube with a ceramic sleeve, with nitrogen being passed through in an amount of 1 l / minute and at a rate of 20 ° 0 / minute is heated ”. Glass beads serve as a reference sample.

The polymer becomes a yarn based on 36 Er.ulot "" "den mit a titer of 70 -den processed and knitted into a stocking. The knitted fabric has a Hunter D-40 shade of white of 51.2.

Hunter D-40 whiteness is the value determined with a Hunterlab whiteness reflectometer, Model D-40 (manufactured by Hunter Associates Laboratory, Inc., Fairfax, Virginia). This instrument is a reflectometer specially designed to measure white tone. A light source C of the International Commission on Illumination (CIE) serves as the light source. ¹ between the light source and the sample a rotating UV-filter is disposed. The wavelengths in the ultraviolet range can either be filtered out or up to

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get to the sample. The instrument is covered with ceramic tiles calibrated as a reference sample. The reflection values are determined by zeroing a galvanometer with a calibrated potentiometer, the scale of which is graded in such a way that the percentage reflections from the instrument can be read. The following sizes are measured? 1) Green reflection excluding the incident ultraviolet light, designated as G (B), 2) blue reflection excluding the incident ultraviolet light, designated as B (E), and 3) blue reflection including incident ultraviolet light as B (I). The following quantities are calculated: Percentage of blue reflectance due to fluorescent Materials such as optical brighteners are due in or on the sample, calculated according to the equation (1), and the white goal of the sample, calculated according to equation (2).

#BR = B (I) ~ B (E) (1)

W = 4B (I) - 3G (E) (2)

A more detailed explanation of the theory and operation of the instrument including the rationale for the preferred use of equation (2) can be found in the article "New Refleetometer and Its Use for Whiteness Measurement "by Richard S. Hunter in" Journal of the Optical Society of America ", 5Ό, issue 1 (January 1960), pp. 44-48.

For comparison, the polymerization described in Example 1 is carried out using the cobalt prepolymer repeated except that bis (2-hydroxyethyl) azelate is not used. The polymer obtained has an intrinsic viscosity of 0.640 dl / g and a TDA melting point of 261 C. The polymer is processed into a 36-thread yarn of 70 denier and knitted into a stocking ·. 7 for that Knitted fabric is determined to have a Hunter white shade of 44.6,

1038 2 7/1982

Since the whiteness of any given sample is meaningful only when compared to a control sample is It is useful to also display the shade of white of any given sample as a percentage improvement over the control sample to express. This is done simply with the help of equation (3):

Percentage improvement =

Sample White Tone - Control Sample White Tone _inn

White shade of the control sample ^{x IUU}

Accordingly, the polymer produced according to Example 1, after processing into a knitted fabric, is 15 $ better White shade as a polymer that under the same conditions, but without the addition of bis (2-hydroxyethyl) azelate has been made. This is a huge improvement.

Example 2

Using the cobalt prepolymer, the polymerization described in Example 1 is repeated with the difference that instead of bis (2-hydroxyethyl) azelate an equal amount of 3- (2-hydroxyethoxy) phenol is used. When comparing one from the obtained Polymer made yarn with the control sample described in Example 1 will give similar results as obtained in example 1.

Example 3

Using the cobalt prepolymer, the polymerization described in Example 1 is repeated with the difference that instead of bis (2-hydroxyethyl) azelate an equal amount of dimethyl adipate is used. When comparing one of the obtained polymer produced yarn with that described in Example 1 Control sample results similar to those in Example 1 are obtained,

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Example 4

Using the cobalt prepolymer, the in The polymerization described in Example 1 is repeated with the difference that instead of bis (2-hydroxyethyl) azelate an equal amount of dimethyl sebacate is used. When comparing one of the obtained polymer Yarn made with the control sample described in Example 1 will give results similar to those in Example 1 received.

Example 5

In an electrically heated 2 1 autoclave from non-! stainless steel, which is provided with Rührar _s thermocouple, condenser with adjustable condensate decrease and apparatus for operating under reduced pressure, 600 g of dimethyl ^{terephthalate;} + J2 g of ethylene glycol and 0.21 g of cobalt acetate were added. The autoclave is charged with nitrogen ^·: fabric rinsed and heated. Methanol begins to over-. go when the temperature of the approach is 175 ° C. The distillation of the methanol is continued first with 50 $ decrease and finally with 20 $ decrease for a time of about 5 hours "After this time, the mixture has a temperature of about 220 C ₀ In order to ensure that the methanol was distilled off completely, , the distillate decrease is increased to $ 90 and ethylene glycol is distilled off for about 20 minutes. The temperature of the batch is now 23O ⁰ C. The condenser is removed from the autoclave in the 2.1 g of titanium dioxide, 0.24 g of antimony acid, 0.30 g of a 50 $ aqueous solution of trimethyl phosphite in ethylene glycol and 18.0 g of 1 _f 3-bis (2-hydroxyethoxy) benzene are given. A concentrator (narrowing condenser) with a vacuum adapter is attached to the autoclave, after which the autoclave is flushed with nitrogen. Then the evacuation begins, which takes about 45 minutes. The batch is polymerized for 2 hours at 280 ^° C. and 0.6 mm Hg. The polymer obtained is in

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Spun water. It has an intrinsic viscosity of 0.593 dl / g and a TDA-melting point of 252 ⁰ C.

The polymer becomes a 36-ply 70 denier yarn processed and knitted into a stocking. A Hunter white shade of 72.1 is determined for the knitted fabric.

To prepare a comparative sample, the experiment described in Example 3 is repeated with the difference that no 1,3-bis (2-hydroxyethoxy) benzene is used. The polymer obtained has a Grenzvisko- i intensity of 0.564 and a melting point of TDA ~ 258 G. It is the processed into a 36-filamentous yarn from 70th The yarn is knitted into a stocking. The knitted fabric has a Hunter whiteness of 67.5.

Example 6

The experiment described in Example 5 is repeated with the difference that an equal amount of bis (2-hydroxyethyl) aze- λ lat is used instead of 1,3-bis (2-hydroxyethoxy) benzene. The polymer obtained has an intrinsic viscosity of 0.581 dl / g and an IDA melting point of 256 ° C.

The polymer becomes a 36-ply 70 denier yarn processed, which is knitted into a stocking for which a Hunter white shade of 71.4 is determined. The polymer this example has a white tone that is increased by $ 6 compared to the polymer, which does not contain bis (2-hydroxyethyl) azelate was added. The comparative sample of Example 5 has a Hunter whiteness of 67.5.

7 1Qft?

- 1 ? -

2G63841 "

Example 7

The experiment described in Example 5 is repeated with the difference that instead of 1,3-bis (2-hydroxyethoxy) benzene an equal amount of dimethyl azelate is used. The polymer obtained has an intrinsic viscosity of 0.529 dl / g and a TDA melting point of 254 ° C.

The polymer becomes a 36-ply 70 denier yarn which is knitted into a stocking exhibiting a Hunter whiteness of 84.0. This matches with an improvement of $ 24 over that in Example 5 described comparative sample to which no dimethyl azelate was added and which had a Hunter whiteness of 67.5 Has.

Example 8

The experiment described in Example 5 is repeated with the difference that, instead of cobalt acetate, an equal amount of manganese acetate is used as ester exchange catalyst. The polymer obtained has an intrinsic viscosity of 0.574 and a TDA-melting point of 244 ⁰ C

The polymer is processed into a 36-ply 70 denier yarn that is knitted into a stocking. For the Knitted fabric is determined to have a Hunter white shade of 56.9 »

For comparison, the experiment described in Example 6 is repeated with the difference that no 1,3-bis (2-hydroxyethoxy) benzene is added. The polymer obtained has an intrinsic viscosity of 0.564 dl / g and a TDA-melting point of 257 ⁰ C. The polymer is the processed into a 36-filamentous yarn 70 that is knitted into a sock, of a Hunter whiteness of 47, 6 has. By adding 1,3 ~ bis (2-hydroxyethoxy) -benzene to the polyester, an improvement in the whiteness of 20% is achieved.

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Example 9

The experiment described in Example 6 is repeated with the difference that instead of cobalt acetate
an equal amount of manganese acetate is used as the ester interchange catalyst. The polymer obtained has an intrinsic viscosity of 0.644 and a TDA-melting point of 252 ⁰ C.

The polymer is processed into a 36-ply 70 denier yarn, which is knitted into a stocking, the
has a Hunter whiteness of 67.1. This corresponds to an improvement of $ 41 compared to the example 8 (

written comparison sample, which contains no bis (2-hydroxyethyl) azelate and a Hunter whiteness of 47.6 Has,

Example 10

The experiment described in Example 7 is repeated with the difference that, instead of cobalt acetate, an equal amount of manganese acetate is used as the ester exchange catalyst. The polymer obtained has a
Intrinsic viscosity of 0.565 dl / g and a TDA-melting point of 256 ⁰ C.

The polymer is processed into a 36-thread yarn of 70 denier f, which is knitted into a stocking. That
Knitted knitted fabric has a Hunter whiteness of 6510, an improvement of $ 37 over the comparative sample described in Example 8, which does not contain dimetbylazelate and has a Hunter whiteness of 47.6.

As already mentioned, certain ester interchange catalysts have an adverse effect on the effectiveness of the compounds according to the invention, the whiteness of
linear synthetic polyesters. This effect is illustrated by Examples 11, 12 and 13.

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Example 11

The experiment described in Example 5 "is repeated with the difference that instead of cobalt acetate, an equal amount of magnesium carbonate is used as Esteraustauschkatalysator. The polymer obtained has an intrinsic viscosity of 0.554 dl / g and a TDA-melting point of 248 ⁰ C.

The polymer is processed into a 36-thread yarn of 70 denier, which is knitted into a stocking, the one Hunter whiteness of 54.8.

To prepare a comparative sample, the experiment described in Example 11 is repeated with the difference that no 1,3-bis (2-hydroxyethoxy) benzene is used. The polymer obtained has an intrinsic viscosity of 0.518 dl / g and a melting point TM of 261 ⁰ C. The polymer is processed into the 36-filamentous yarn 70 that is knitted into a sock. The knitted fabric has a Hunter whiteness of 65.0 »The polymer produced using magnesium carbonate as a catalyst, which contains 1,3-bis (2-hydroxyethoxy) benzene, has a whiteness that is 16 $ lower than the comparative polymer, the no 1,3-bis (2-hydroxyethoxy) benzene was added,

Example 12

The experiment described in Example 6 is repeated with the difference that, instead of cobalt acetate, an equal amount of magnesium carbonate is used as the ester exchange catalyst. The polymer obtained has a Grenzviakosität of 0.635 dl / g and a TDA-melting point of 255 ⁰ C

The polymer becomes a 36-ply 70 denier yarn processed, da.3 is knitted into a stocking. The knitted fabric has a Hunter white shade of 55.0 which is around $ 15

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is worse than the white shade of the comparison sample described in Example 11, which does not contain bis (2-hydroxyethyl) azelate and has a Hunter whiteness of 65.0.

Example 13

The experiment described in Example 7 is repeated with the difference that, instead of cobalt acetate, an equal amount of magnesium carbonate is used as the ester exchange catalyst. The polymer obtained has an intrinsic viscosity of 0.606 and a TDA-melting point of 257 ⁰ C

The polymer is processed into a 36-ply 70 denier yarn, which is knitted into a stocking. That Knitted fabric has a Hunter whiteness of 44 »0 that is around $ 33 is worse than the white shade of the comparison sample described in Example 11, which does not contain dimethyl azelate and has a Hunter whiteness of 65.0.

The degree to which each procedure provides 7: improvement the whiteness of polymers (and thus the whiteness of products made from this improved polymer) is valuable depends on the duration of the improvement in whiteness achieved. That by using the Compounds according to the invention are resistant to effects achieved is illustrated by Example 14.

Example 14

The hosiery samples of Examples 8-13 are bleached and heat set, whereupon the Hunter whiteness values for the treated knitted fabric determined v / ground. The results are shown in Table 1 below.

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Additive Table I. White tone Improvement, $ Stocking test Ester interchange
catalyst 75.2 Comparison
sample of
Example 8 1,3-bis (2-hydroxy-
ethoxy) benzene Manganese acetate ^: 83.1 11 Example 8 Bis (2-hydroxyethyl) -
azelät Manganese acetate 109.1 45 Example 9 Dimethyl azelate Manganese acetate 91.2 21st Example 10 Manganese acetate

Comparative sample from Example 11

Example 11

Example 12

I, 3-bis (2-hydroxyethoxy) benzene

Bis (2-hydroxyethyl) ■ azelat

Magnesium carbonate 105.4

Magnesium carbonate 91.5 Magnesium carbonate 94.0

Example 13 Dimethyl azelate

Magnesium carbonate

49.4

The values in Table I show that by bleaching and heat setting, the relative whiteness of the samples in general was not changed, although by bleaching the whiteness of each sample compared to the untreated one Knitted fabrics was improved.

Since the products according to the invention are suitable for the manufacture of dyed fabrics and garments, the properties of the dyed articles made from these products are important. The most important property of a dyed product is its lightfastness. The lightfastness of a textile product is usually determined with the aid of the ™ Fadeometer (manufactured by Atlas Electric Devices Company, Chicago, Illinois), an independent, electrically operated apparatus for testing the resistance of dyed articles to daylight. In principle, in this device the sample is simply exposed to light generated by a carbon arc for a given time. The irradiated sample is visually rated with a number on a scale from 1 to 5, the number 1 signifying the complete loss of color and the number 5 no change in color. It should be noted that the values determined using a particular apparatus i

are not necessarily comparable with values that were determined with a second similar apparatus, because the intensity of the light source differs from one device to another. Generally indicates a rating number of 3 or more after 20 hours is satisfactory Lightfastness for the usual textile end uses, exclusively for use in carpets at. It follows that the products according to the invention have satisfactory light fastness after dyeing Example 15.

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Example 15

The stocking samples of Examples 5 to 13 are separated with the disperse dye Eastman Blue GBLP such as
Dyed as follows: The dye liquor consists of an aqueous solution of $ 1 Eastman Blue GBLP, which per liter
2 g monosodium phosphate, 3 g "Carrolid ELFC", one
Biphenyl type carrier, and 0.5 g of a surfactant ("Tanapon X-70"). The knitted fabric is kept in the boiling dye liquor for 1 hour, then
rinsed, washed and dried. The dyed knitted fabric is then treated in the fadeometer for 24 hours, after which the irradiated knitted fabric is visually assessed. The results are given in Table II below.

Table II

A. Before heat set after dyeing Esteraus-
exchange-
catalysis
gate Apply
tion stocking
sample Additive cobalt
acetate 3 ■ comparison
sample of
Example 5 dto. 3-4 ". Example 5 1,3-bis (2-hydroxyethoxy) -
benzene dto. 3-4 Example 6 Bis (2-hydroxyethyl) azelate dto. 3-4 ⁺ Example 7 Dirnethylazelate B. After heat set after dyeing cobalt
acetate 3-4 Comparison
sample of
Example 5 dto, 3-4. Example 5 1,3-bis (2-hydroxyethoxy) -
benzene dto. 4th Example 6 Bis (2-hydroxyethyl) azelate dto. 4th Example 7 Dimethyl azelate

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C. Bleached and hot-fixated before dyeing

Stocking test

Additive

Ester equipment evaluation catalyst \

comparative
sample of
Example 8 8th 11 1,3-bis (2-hydroxy-
ethoxy) benzene manganese
aeetat 3 ⁺ example 9 12th Bis (2-hydroxyethyl) -
azelat dto. 3 ⁺ example 10 13th Dimethyl azelate dto. 4th example Comparative
sample of
Example 11 - dto. 3 ⁺ example 1,3-bis (2-hydroxy-
ethoxy) benzene Magnesium-
carbonate 3 ⁺ example Bis (2-hydroxyethyl) -
azelat dto. 3-4 example Dimethyl azelate dto. 3 dto.

The products according to the invention thus enable the production of dyed fabrics which, in their ^ ichtfastness Equivalent or superior to the colored fabrics made from the unmodified polymer are. This effect is independent of the effect of the compounds according to the invention on the white tone of the polymers.

It is known that the color of polymers is closely related with catalyst residues, although the exact nature of these catalyst residues is not always known is. For example, in the case of lead salts, polymers with a yellow color are obtained, while in the case of Germanium relatively white polymers can be obtained. It is not intended to be bound by any theory, however it is assumed that the ester interchange catalyst interacts with the compounds according to the invention

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kung occurs and here either the amount of coloring Reduced catalyst residues or changed the nature of these residues and thereby the strength of the in the polymer the discoloration caused.

It is therefore preferable to add the compounds according to the invention before the polycondensation, so that the desired color-reducing interaction can occur before the system is subjected to the strict conditions of the polycondensation. A loss of the compounds according to the invention from the system during the polycondensation is generally keiji problem, as the glycol component of the polyester usually has a lower boiling point than the compounds according to the invention. The addition of the compounds according to the invention at the beginning of the ester exchange reaction is of course possible and lies within the scope of the invention.

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Claims (5)

Claims 1) Film and fiber-forming linear synthetic polyesters with an improved shade of white, characterized by a low content of 1,3-bis (2-hydroxyethoxy) benzene, 3- (2-hydroxyethoxy) phenol, lower alkyl esters of adipic acid, lower alkyl esters of suberic acid, lower alkyl esters of azelaic acid or lower alkyl esters of sebacic acid as a ¹ I difunctional compounds. 2) polyester according to claim 1, characterized by one under 5 wt .- ^, based on the used for polyester condensation Dicarboxylic acid or its dialkyl ester, preferably containing a difunctional compound 1,3-bis (2-hydroxyethoxy) benzene, bis (2-hydroxyethyl) azelate or dimethyl azelate. 3) Process for the production of film- and fiber-forming linear synthetic polyesters with improved whiteness according to claim 1 and 2 by direct esterification or | by ester exchange, characterized in that one one of the difunctional compounds mentioned in claim 1 is added before a substantial polycondensation has taken place. 4) Process according to claim 3j, characterized in that salts of transition metals of groups HB, VIIB and VIII of periods K and 5 of the Periodic Table, in particular manganese or cobalt salts, are used as Esteraustaur.chkatalysatoren in the preparation by ester exchange. 109827/1982 5) Process according to claim 5 and 4, characterized in that dialkyl terephthalates and glycols of the formula HO (CH ₂ ) OH, in which η is an integer of ? up to about 10, and this in the presence of manganese or cobalt salts of aliphatic monocarboxylic acids with up to about 6 carbon atoms as ester exchange catalysts and, before a substantial polycondensation, up to about 5 wt .- ^, based on the terephthalic acid dialkyl ester, 1,3 - Adds bis (2-hydroxyethoxy) benzene, bis (2-hydroxyethyl) azelate or dirnethylazelate. 109 8 2t / 19 8 1