CN102565230B - Detection method of free chlorine ions in polyisobutylene - Google Patents

Abstract

The invention discloses a detection method of free chlorine ions in polyisobutylene, which is also applicable to the detection of other polyolefin free chlorine ions, and adopts a dissolution-precipitation method to separate and extract the free chlorine ions in the polyisobutylene and measures the chlorine ion content in the absorption liquid though the chlorine ion quantitative analysis method as the ion chromatography. The technical scheme is simple and reliable to operate, requires no special device, is particularly applicable to the detection of the free chlorine ions in the polyisobutylene, and has high detection accuracy. The detection method of the free chlorine ions in the polyisobutylene adopting the ion chromatography with the detection lower limit being ppb level is convenient and reliable.

Description

A kind of detection method of free chlorine ions in polyisobutylene

Technical field

The present invention relates to a kind of detection method of high molecular polymer free chlorine ion, be specifically related to a kind of detection method of free chlorine ions in polyisobutylene, belong to chemical technology field.

Background technology

Polyisobutylene is a class industrialization polyolefin, is widely used in all many-sides such as lubricating oil, rubber, bonding agent, plastifier, softening agent, electrically insulating material, encapsulant, gasoline cleaning agent and chewing gum base glue.Polyisobutylene is to be made through cationic polymerization process by the monomer isobutylene, generally adopts lewis acid (Lewis) as cationic polymerization initiators, as AlCl ₃, SnCl ₄, TiCl ₄and BF ₃deng.Catalyzer in polymerizate removes by alkali cleaning and water elution.For specific inductive capacity, electrical insulating property, the thermal stability that does not affect the polyisobutylene product, the polyisobutylene of medical grade and food stage particularly, need to control the chloride ion content in product, such as, BASF Aktiengesellschaft requires to be less than 5ppm to the chloride ion content in the polyisobutylene product of the relevant trade mark.Therefore the content detection of chloride ions in polyisobutylene proposed to very high requirement.

Detection method for chlorion mostly concentrates on chlorion detection in aqueous solution.As Cl ~-Monitoring in boiler water, in potable water, chlorion detects, in sewage chlorion detect, Cl ~-Monitoring etc. in lime slurry.Testing sample is aqueous solution, can directly measure chlorine ion concentration.In organism, the detection of chlorion also has patent report, as chlorion in organic amine detects, and chlorion detection etc. in smooth liquid.Patent documentation CN101587093 provides the wet-leveling liquid chlorine ion content determination method.This chlorine ion content determination has adopted the method for calcining, makes the organic amine material carbonization of constraint chlorion, forms the inorganics of solubility, makes chlorion dissociate out, utilizes potentiometric titration to record.Patent documentation CN102253101A discloses a kind of method for detecting chloride ions in polyisobutylene method and has mainly comprised the steps: (1) polyisobutylene pre-service.Polyisobutylene sample low temperature brittleness in liquid nitrogen, and sample is ground into to the particle of particle diameter 100～200 μ m; (2) sample is burning containing oxygenation in the oxygen Molotov cocktail of absorption liquid, and chlorion is absorbed liquid and fully absorbs; (3) with the chloride ion content in the potentiometric determination absorption liquid; (4) calculate the content of chloride ions in polyisobutylene.The present invention adopts the liquid nitrogen quenching method, makes polyisobutylene become brittle solid, and is treated to very little granularity, utilizes combustion method, and the chlorine element in polyisobutylene is effectively separated out, thereby detects content of Cl element in the polyisobutylene polymkeric substance.

For the trace impurity in polymkeric substance (as chlorion), because be covered by organic polymer, can't direct-detection, need the pre-service through sample.At present, mainly adopt ashing method for the preprocess method of polyisobutylene, if any high temperature furnace dry ashing, plasma oxygen low temperature dry ashing, oxygen bomb (oxygen bottle) firing method.These methods all need special device, the condition harshness.Adopt the free chloro ion in dissolving precipitated method separation and Extraction polyisobutylene, utilize the ion chromatography electric conductivity detector to detect, by calculating chlorion chromatogram peak area, determine chloride ion content, the method has no report.

Summary of the invention

For the deficiencies in the prior art, the present invention aims to provide a kind of detection method of free chlorine ions in polyisobutylene.

The present invention is achieved through the following technical solutions:

Terminological interpretation

The chromatography of ions: chromatography of ions is according to ion exchange principle, and the difference of moving on ion exchange column based on different ions is carried out the component in sample separation, and by galvanochemistry or fluorescence detector detected components.Chlorion is different from other negative ion to the relative affinity of low capacity strongly basic anionic resin (separating column), so chlorion has specific retention time.Chlorion is when the strong acidic ion resin of flowing through (suppressed column), be converted into the acid type that high electricity is led, carbonate-supercarbonate becomes the carbonic acid that light current is led, the chlorion that detector measures is converted into corresponding acid type is led in electricity consumption, compare with standard, according to chromatography of ions peak height or peak area, quantitatively calculate ion concentration.

Chemical titration: the chlorion chemical titration is that the silver nitrate standard solution of known accurate concentration is added drop-wise in the aqueous solution of chloride ion-containing, to add, amount and the chlorion of silver nitrate react completely just by stoichiometric relationship, make indicator with potassium chromate, the AgNO of excessive dropping ₃solution will with chromate ion (CrO ₄ ^2-) generation Ag ₂crO ₄brick-red precipitation, the indication titration end-point.Then according to the concentration of added silver nitrate standard solution and the volume consumed, calculate the content of chlorion.

Potentiometric titration: the ultimate principle of potentiometric titration is similar to chemical titration, and its difference is that the definite of terminal is to determine titration end-point by the hop of electrode potential.Before and after the chlorion titration end-point, the concentration of silver ions in liquid to be measured often changes several orders of magnitude, causes the hop of current potential, and the titration end-point judgement easily, accurately.The content of tested chlorion calculates by the amount that consumes the silver nitrate standard solution.

A kind of detection method of free chlorine ions in polyisobutylene, step is as follows:

(1) dissolving of polyisobutylene: take the 0.1-2.0g polyisobutylene and be dissolved in the 50-120mL solvent, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the water of 100-150mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, incline and supernatant liquid; 10mL water washing 1-2 time for polyisobutylene by separating out, merge supernatant liquid and wash solution, and boil off solvent and the water extracted in solution; Add 10mL water logging elution to get chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall the absorption liquid standing over night;

(3) measure chloride ion content in absorption liquid with the chlorion quantitative analysis method;

The mass content W of chlorion _clby formula (1), calculate:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6---\left(1\right)$

In formula,

W _clmean chloride ion content in the polyisobutylene sample, the μ g/g of unit (ppm);

C _clthe concentration that means chlorion in absorption liquid, the g/L of unit;

V means the volume of absorption liquid, the L of unit;

M means the quality of polyisobutylene sample, the g of unit.

It is preferred according to the present invention,

Solvent described in step (1), step (2) is tetrahydrofuran.

Water described in step (2) is ultrapure water.

High speed centrifugation described in step (2), the time is 15-20 minute, rotating speed 4500-4800rpm.

Chlorion quantitative analysis method described in step (3) is selected from the chromatography of ions, chemical titration or potentiometric titration, the preferred ion chromatography.

Excellent results of the present invention is as follows:

1, the technical program adopts the free chloro ion in dissolving precipitated method separation and Extraction polyisobutylene sample, and simple to operate, cost is low, does not need special device.

2, the technical program adopts the chlorion quantitative analysis method mensuration chloride ion contents such as the chromatography of ions.Wherein, the sulfate by ion chromatography precision is high, highly sensitive, and analyst coverage is extremely hundreds of mg/L of μ g/L, and the chlorion detection limit is less than 10 μ g/L, is the convenient and reliable method of chlorine detection ion concentration.

Embodiment

Below in conjunction with embodiment, the present invention is described further, but be not limited to this.Following reagent does not have the conventional commercially available prod that is of special instruction.

Embodiment 1

(1) dissolving of polyisobutylene: take 0.328g polyisobutylene (sample 1, weight-average molecular weight M _w=10.0 ten thousand) be dissolved in the 50mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 100mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 15min, rotating speed 4500rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) use the chloride ion content of ion-chromatographic determination absorption liquid; Wherein, leacheate: 3.5mmolL ^-1na ₂cO ₃and 1.0mmolL ^-1naHCO ₃mixed solution; Pump pressure: 1.4MPa; Leacheate flow velocity: 1.20mLmin ^-1; Sample feeding amount: 25 μ L; The results are shown in Table 1.

Table 1

In polyisobutylene sample 1, chloride ion content is calculated as follows:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6=\frac{3\×{10}^{-3}\×0.01}{0.328}\×{10}^6=91.4\mathrm{\μg}/g.$

Embodiment 2

(1) dissolving of polyisobutylene: take 0.791g polyisobutylene (sample 2, weight-average molecular weight M _w=6.7 ten thousand) be dissolved in the 50mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 100mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 20min, rotating speed 4600rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) use the chloride ion content of ion-chromatographic determination absorption liquid; Wherein, leacheate: 3.5mmolL ^-1na ₂cO ₃and 1.0mmolL ^-1naHCO ₃mixed solution; Pump pressure: 1.4MPa; Leacheate flow velocity: 1.20mLmin ^-1; Sample feeding amount: 25 μ L; The results are shown in Table 2.

Table 2

In polyisobutylene sample 2, chloride ion content calculates:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6=\frac{6\×{10}^{-3}\×0.01}{0.791}\×{10}^6=75.8\mathrm{\μg}/g.$

Embodiment 3

(1) dissolving of polyisobutylene: take 0.324g polyisobutylene (sample 3, weight-average molecular weight M _w=14.9 ten thousand) be dissolved in the 50mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 100mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 20min, rotating speed 4600rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) use the chloride ion content of ion-chromatographic determination absorption liquid; Wherein, leacheate: 3.5mmolL ^-1na ₂cO ₃and 1.0mmolL ^-1naHCO ₃mixed solution; Pump pressure: 1.4MPa; Leacheate flow velocity: 1.20mLmin ^-1; Sample feeding amount: 25 μ L; The results are shown in Table 3.

Table 3

In polyisobutylene sample 3, chloride ion content calculates:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6=\frac{4.8\×{10}^{-3}\×0.01}{0.324}\×{10}^6=148.1\mathrm{\μg}/g.$

Embodiment 4

(1) dissolving of polyisobutylene: take 1.755g polyisobutylene (sample 2, weight-average molecular weight M _w=6.7 ten thousand) be dissolved in the 120mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 200mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 20min, rotating speed 4600rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) with the chloride ion content of chemical titration absorption liquid: the 10mL absorption liquid is placed in to clean conical flask, separately gets a conical flask and do blank test with distilled water.Accurately add 0.1mL 5%K with transfer pipet ₂crO ₄solution, constantly shaking lower use 1.0 * 10 ^-3mol/L AgNO ₃standard solution is titrated to and brick-red precipitation occurs, and record consumes AgNO ₃the volume of standard solution, the concentration of chlorine in the calculating absorption liquid.Press above-mentioned steps parallel 3 times.The results are shown in Table 4.

Table 4

In polyisobutylene sample 2, chloride ion content calculates:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6=\frac{15.3\×{10}^{-3}\×0.01}{1.755}\×{10}^6=87.2\mathrm{\μg}/g$

Compare with the ion-chromatographic determination result, adopt the chloride ion content in the chemical titration sample, the sample expense is large, and result error is large.

Embodiment 5

(1) dissolving of polyisobutylene: take 0.787g polyisobutylene (sample 2, weight-average molecular weight M _w=6.7 ten thousand) be dissolved in the 50mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 120mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 20min, rotating speed 4600rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) with the chloride ion content of potentiometric determination absorption liquid: install titration apparatus, by silver nitrate standard solution (1.0 * 10 ^-3mol/L) add in buret.Put into magneton in absorption liquid, and be placed on stirrer.Regulate " terminal current potential " knob, set and display terminal potential value.After terminal current potential and pre-control point potential setting are good, " setting " switch is put to " measurement ".Electrode is inserted in detected solution, open stirrer, reconcile rotating speed, press " titration starts " button.Record liquid volume reading V (mL) and corresponding current potential E value in buret in titration process.While approaching terminal, often add 0.1mL silver nitrate standard solution, write down its corresponding E value, determine the silver nitrate standard solution that titration end-point consumes.Do parallel experiment and blank test with the same terms.The results are shown in Table 5.

Table 5

In polyisobutylene sample 2, chloride ion content calculates:

$W_{\mathrm{Cl}}=\frac{C_{\mathrm{Cl}}\×V}{m}\×{10}^6=\frac{5.7\×{10}^{-3}\×0.01}{0.787}\×{10}^6=72.4\mathrm{\μg}/g$ 。

Claims (5)

1. the detection method of a free chlorine ions in polyisobutylene, step is as follows:

(1) dissolving of polyisobutylene: take the 0.1-2.0g polyisobutylene and be dissolved in the 50-120mL solvent, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the water of 100-150mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, inclines and supernatant liquid; 10mL water washing 1-2 time for polyisobutylene by separating out, merge supernatant liquid and wash solution, and boil off solvent and the water extracted in solution; Add 10mL water logging elution to get chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall the absorption liquid standing over night;

(3) measure chloride ion content in absorption liquid with the chlorion quantitative analysis method;

The mass content W of chlorion _clby formula (1), calculate:

In formula,

W _clmean chloride ion content in the polyisobutylene sample, the μ g/g of unit (ppm);

C _clthe concentration that means chlorion in absorption liquid, the g/L of unit;

V means the volume of absorption liquid, the L of unit;

M means the quality of polyisobutylene sample, the g of unit;

Solvent described in step (1), step (2) is tetrahydrofuran; High speed centrifugation described in step (2), the time is 15-20 minute, rotating speed 4500-4800rpm.

2. detection method as claimed in claim 1, is characterized in that, the water described in step (2) is ultrapure water.

3. detection method as claimed in claim 1, is characterized in that, the chlorion quantitative analysis method described in step (3) is selected from the chromatography of ions, chemical titration or potentiometric titration.

4. detection method as claimed in claim 3, is characterized in that, the chlorion quantitative analysis method described in step (3) is the chromatography of ions.

5. detection method as claimed in claim 1, is characterized in that, step is as follows:

(1) dissolving of polyisobutylene: take the 0.328g polyisobutylene and be dissolved in the 50mL tetrahydrofuran, make homogeneous phase solution;

(2) extraction of chloride ions in polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is made slowly drops in the ultrapure water of 100mL, after treating that polyisobutylene is separated out from water, solution is carried out to the high speed centrifugation separation, time 15min, rotating speed 4500rpm; Incline and supernatant liquid; 10mL ultrapure water washing 2 times for polyisobutylene by separating out, merge supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in solution; Add the 10mL ultrapure water to embathe the extraction chlorion, repeatedly rock, make in the complete water-soluble solution of chlorion on container inner wall to obtain absorption liquid, standing over night;

(3) use the chloride ion content of ion-chromatographic determination absorption liquid;

In polyisobutylene sample 1, chloride ion content is calculated as follows: