CS267536B1 - Method set! mixture! retarders burned! - Google Patents

Abstract

A mixture of aryl phosphate type flame retardants and phenolic phosphite antioxidants is analyzed by separation liquid chromatography with selective detection of aryl phosphates at 250 nm and phenolic phosphite antioxidants at 280 nm. The choice of separation system is guided by the nature of the phosphite antioxidant used in the mixture. For alkyl substituted phenyl phosphites, a non-polar (reverse) phase is used for separation, for aryl substituted phenyl phosphites, a polar (normal) phase.

Description

The invention relates to the analytical determination of a mixture of a flame retardant and a ryl phosphate type in a mixture of a phenolic phosphite antioxidant, in particular in polyaryl ethers.

Polyaryl ethers as a demanding construction material are treated for use in the automotive and electrical industries by the addition of phenolic and phosphite antioxidants to increase thermooxidative stability and by the addition of flame retardant type tri and ryl phosphate to reduce flammability during application.

Tests commonly used to determine the thermo-oxidative stability of polymers.

The commonly used methodology for rapid control of additive dosing - UV spectrophotometry - encounters the fact that the absorption bands of all additives lie in a relatively narrow range of 260 to 280 nm and to such an extent that they make evaluation impossible. In addition, the UV spectrum of the mixture is complicated by the presence of varying amounts of phenolic impurities. Similar problems, resulting from the multicomponent nature of the additives used, prevent 1 use of spekt-spectrophotometry.

The solution to the problem is the separation of the individual components of the mixture by a suitable chromatographic method. The separation of isomeric isopropylphenyl phosphates is described, which serves to control the reaction mixture in the process of production of flame retardants by gas chromatography. However, this methodology is not suitable for the determination of most phosphite antioxidants, as they decompose at elevated temperatures and do not provide reproducible results. The same is true for some of the higher molecular weight types of phenolic antioxidants. In these cases, high performance liquid chromatography (HPLC, hereinafter only liquid chromatography) is used. This methodology was also applied to isopropylene phenyl phosphates in order to preparatively separate the components of non-integral mixtures with the same number of isopropyl groups in the molecule.

For its universal applicability and gentleness, liquid chromatography was also chosen for the separation and determination of flame retardants and phosphite antioxidants in plastics.

In this case, however, the situation is complicated by two problems:

The three-component additive mixture analyzed contains on average up to 75 parts of flame retardant, but only 2-5 parts of phenolic antioxidant, the requirement not to exceed the limit of sufficient accuracy for its determination. In addition, aryl phosphate flame retardants are mixtures of 5-9 components with varying proportions of isopropylphenyl groups. With their retention times, these components rank among the weak peaks of the components of phenolic and phosphite antioxidants. Chromatogran becomes confusing in terms of the correct assignment of the separated components to the individual additives and the weak peaks of phenolic and phosphite antioxidants The peaks of the aryl phosphates are disturbed.

In order to be able to use liquid chromatography also for the analysis of said mixture of additives, it was necessary to optimize the separation with respect to the sensitive determination of the phenolic antioxidant and to ensure unambiguous assignment of the separated components to the individual additives.

The present invention relates to a process for the determination of a mixture of triaryl phosphate flame retardants and phenolic and phosphite antioxidants by liquid chromatography with UV detection, in which the polarity of the separation system follows the polarity of the fostite antioxidant and the flame retardants are detected by a UV detector at 250 nm and phenolic antioxidants. 280 nm.

In particular, the invention relates to a process for the determination of a mixture of flame retardants and antioxidants, in which a non-polar (reverse) phase is used for separating a mixture containing alkyl-substituted phenylphosphites and an alcohol with 3 to 10% by volume of water is used as the mobile phase and polar / normal / phase a As mobile phase -hexanes or -heptanes with 0.2 to 2% by weight of isopropanol.

In optimizing the separation conditions, a detailed investigation found that the control role and the nature of the phosphite antioxidant present:

In case the phenyl group of the phosphite is substituted by linear or branched alkyl, optimal partitioning is achieved by using a non-polar (reverse) phase with a mobile phase with a low water content (2 to 10% by volume) in ethyl alcohol or methyl alcohol. This separation system will provide optimal separation of the mixture with phosphite antioxidants such as: tris / 4-nonylphenyl / phosphite and tris / 2,4-di-tert. butyl-phenyl / phosphite.

For aryl-substituted phenylphosphites, for example tris (2,4- (1'-phenylethyl) phenyl) phosphite, on the other hand, an optimal resolution is achieved on the polar (normal) phase with a mobile phase of n-hexane or low-content n-heptane (up to 2% by volume). isopropyl alcohol. This method allows the determination of all components of the phosphite antioxidant, including the proportion of aryl-substituted phenols.

In both cases, the stated separation conditions satisfy the requirement that the retention time of the minor component of the mixture - the phenolic antioxidant - be as small as possible within the optimal resolution of all components.

Another requirement, the unambiguous assignment of differentiated plaques to the individual additives and the simultaneous sufficient sensitivity of the determination of the minor component of the mixture have been solved by the method of component detection.

The method of selective UV detection in the assay of the present invention utilizes the difference in spectral characteristics in the UV region. Aryl phosphates have a maximum absorption at 260 nm, phosphite antioxidants at 270 nm and phenolic antioxidants at 280 nm. Phenolic antioxidants as a minor component of the mixture are detected at 280 nm, i.e. with full sensitivity. The sensitivity of phosphite antioxidants is somewhat suppressed at this wavelength, approximately to the extent corresponding to their greater proportion in the mixture. The main component of the mixture - eryl phosphates - are suppressed at this wavelength to such an extent that their peaks do not exceed the noise of the baseline of the recording too much and can be eliminated by setting the integrator. Thus, a wavelength of 280 nm is selective for the determination of phenolic and phosphite antioxidant. Aryl phosphates, on the other hand, can be determined selectively at a wavelength of 250 nm, when the detection of antioxidants is completely suppressed and the detection of aryl phosphates is sufficiently sensitive.

This method of detection eliminates the possibility of a gross error in the assignment of plaques and thus allows the determination of additives side by side. In addition, it increases the accuracy of the determination of low antioxidant contents.

The advantages of determining a mixture of additives using the process of the present invention are:

1. Achieving optimal efficiency of separation of said additives using separation conditions depending on the type of phosphite antioxidants.

2. Possibility to determine all additives in the extract in a simple way next to each other.

3. Simple and unambiguous detection of additives

4. Increased accuracy of determination of additives, especially phenolic antioxidants, which are in the lowest concentration.

The content of individual additives is evaluated from the sum of all relevant components by the method of external calibration. The concentration range of the determined additives can be influenced by the size of the extracted sample. The method is suitable for the operationally used concentration range of percentage units of flame retardants and tenths to hundredths of percent of phosphite and phenolic antioxidants.

The additives are isolated from the polymer before analysis by extraction with a suitable solvent mixture, preferably under reflux, optionally with stirring. The extract is freed of dissolved polymer fractions by cooling, concentrated and the addition of mobile phase is made up to the measured volume. For analysis, it is injected at 250 nm to determine the flame retardant components, and at 280 nm the phenolic and fostite antioxidant are determined. Said selective detection method is of general application for mixtures of different commercial antioxidant products and triaryl phosphate flame retardants. Depending on the type of phosphite antioxidants, a chromatographic system is chosen and the mobile phase is adjusted as shown in the examples.

CS 267536 B1 3

The content is evaluated by an external calibration method using the sum of all components of each adltlva. phenolic antioxidants are one-component, so their evaluation is clear. Phosphite antioxidants may contain small amounts (1 to 5% by weight) of hydrolysis products which need not be considered for analysis. In the case of tris [2,4- (1'-phenylethyl) phenyl] phosphite, which contains a considerable amount. accompanying isomeric arylphenols, its content is evaluated from the sum of the areas of all components, the areas of phenolic impurities being multiplied by the phenol - phosphltin response conversion coefficient obtained for the detector used. Aryl phosphate flame retardants are multicomponent additives. A detailed survey revealed that although the proportions of the individual 1-isopropylphenyl phosphates in the various production batches of Ears, the sum of all their areas corresponds very well to the amount sprayed. This fact makes it possible to perform a relatively very accurate determination of the flame retardant content without evaluating the content of the individual isopropylphenyl phosphates.

The invention is illustrated by the following examples: The examples show the results of analyzes of artificially prepared solutions of mixtures of additives in commonly used concentration meters and the application of the procedure for the analysis of these additives in structural plastics. In the examples, for clarity, adltlva are listed under trade names. Their chemical composition is given in the list of additives used. For each example, the separation system used is given, the choice of which is determined primarily by the type of phosphite antioxidant. The UV detector used was a Model 655A Merck Hitachi. Plot assignment is performed for the flame retardant at 250 na and for the antioxidants at 280 nm by injecting a standard solution which is used simultaneously as an external calibration. The estimate of the relative standard deviation, in X, was calculated from the range of two parallel determinations, X without denomination are by weight.

List of additives used

phenol i c t - 211211Í2 21Z business name 1. octadecyl-3- / 3 *, 5'-di-tert. butyl -4 * -hydroxy phenyl / propioná t Irganox 1076 2. tetrakis fmethylene-S, / 3 ', 5' -di-tert. butyl / -4’-hydro- Irganox 1010 xy phenyl propionate / J methane Fenozan 23 3. 1,3,5-trimethyl-2,4,6-tris / 3 *, 5 * -diter. lonox 330 butyl-4 * hydroxybenzyl / benzene * Antioxidant 330 £ 22í112Ϊž_2Q112ňlá2QlX 1. tris (4-nonylphenyl) phosphite Irgafos TNP Weston TNPP 2. Tris (2,4-di-tert-butylphenyl) phosphite Irgafos 168 3. tris / 2,4 - / 1 '- phenylethyl / phenyl] foafite Antioxidant 6

Flame retardants: tricresyl phosphate Disflamo 11 TKP mixture of isopropylphenyl phosphates Retar 131

Example 1 '

Analysis of a model mixture of Retar 131, Antioxidant 6 and Irganox 1010 in a ratio of 50: 20: 1.

A solution of the additive mixture was prepared by weighing 95.0 mg Retar 131, 33.8 mg Antioxidant 6 and 2.2 mg Irganox 1010 and dissolving in 50 ml benzene-ethanol azeotrope. The separation of the components was performed on a Li Chrosorb CN5 column with a mobile phase of 1 X by volume of isopropyl alcohol in n 4 CS 267536 B1

- heptane at a flow rate of 60 ml / h. For analysis, 25 [mu] l of the mixture was injected when the detector 250 was set and 25 [mu] l of the Retar 131 standard solution was calibrated. 93.2 mg of Retar 131 (98% of theory, v = 5 X rel./) were found. mixtures and for calibration of 25 μl of standard solutions of Antioxidant 6 and Irganox 1010. 32.4 mg of Antioxidant 6 (96% of theory, v = 4 X relative) and 2.0 mg of Irganox 1010/90% of theory, v = 8 X were found. relative/

Example 2

Control of the content of additives in the granulate with the required content of 3.27% Retar 131, 0.93 X Antioxidant 1010.

Extraction of 1 g of granulate azeotrope with ethanol: benzene / 32.4; 67.6 vol. (Reflux) and stirring for 4 hours. After cooling to 5-10 [deg.] C., the extract was centrifuged, evaporated to dryness (at a maximum temperature of 50 [deg.] C.), the residue dissolved in 2 ml of dichloromethane and made up to volume. up to 5 ml mobile phase. Separation, detection and evaluation were performed in the same manner as in Example 1. 3.15% Retar .131 (v 9.5 X relative), 0.50 X Antioxidant 6 / v = 4.5 X relative) was found. .11 X Irganox 1010 (v = 6.0 X relative).

Example 3

Analysis of a model mixture of Retar 131, Irgafos 168 and Irganox 1076 in a ratio of 50: 20: 1.

The additive mixture solution contained 98.5 mg Retar 131, 40.2 mg Irganox 1076 in 50 ml ethyl alcohol. The components were separated on a LIChrosorb RP-18 reverse phase packed column; the mobile phase was 93 X ethyl alcohol. Detection, calibration and evaluation of Retar 131 content was performed in the same way as in Example 1. Antioxidants were detected in the mixture at 280 nm, external calibration was performed by injecting standard solutions of Irgafos 168 and Irganox 1076. Detection at 250 nm found 99.2 mg Retar 131/101 X theory, v = 4 X relative /, 38.0 mg Irgafos 168/95 X theory, v 7 X relative / and 2.2 mg Irganox 1076/92 X theory, v = 8 X relative /

Example 4 ..

Analysis of a model mixture of Disflamol TP, Weston TNPP and lonox 330 in a ratio of 50 with 20; 1.

The additive mixture solution contained 87.9 mg Dísflamol TP, 37.6 mg Weston TNPP and 1.73 mg lonox 330 in 50 ml ethyl alcohol. The components were separated on a Li Chrosorb RP-8 column with a mobile phase of 93% vol. Ethyl alcohols. Detection at 250 nm found 89.1 mg Disflamol TP (101 X theory, v = 5 X relative), detection at 280 nm 34.9 mg Weston TNPP (93 X theory, v = 6 X relative) and 1.58 mg lonox 330/91 X theory, v = 8 X relative /

Claims (3)

A process for the determination of a mixture of arylphosphate-type retarders and phenotic 1 phosphite antioxidants by liquid chromatography with UV detection, characterized in that the polarity of the partition system is controlled by the polarity of phosphorus antioxidant and flame retardants are detected by UV detector at 250 nm and phenolic and phosphine antioxidants. 2. The determination method according to claim 1, characterized in that a reverse solid, i.e. non-polar phase and an alcohol with 3 to 10% by weight of water are used as the mobile phase for the separation of the mixtures containing alkyl-substituted phenyl phosphites. 3. The method of determination according to item 1, characterized in that a normal i.e. polar phase and hexanes or heptanes with 0.2 to 2% by weight of isopropanol are used as the mobile phase for the separation of the mixture containing aryl-substituted phenylphosphites.