CN102565230A - 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 polyisobutylene Free Chlorine ion

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 polyisobutylene Free Chlorine ion, belong to chemical technology field.

Background technology

Polyisobutylene is one type of industrialization polyolefin, is widely used in many aspects 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, like AlCl ₃, SnCl ₄, TiCl ₄And BF ₃Deng.Catalyzer in the polymerizate removes through alkali cleaning and water elution.For specific inductive capacity, electrical insulating property, the thermal stability that does not influence the polyisobutylene product; The polyisobutylene of medical grade and food-grade particularly; Need the chloride ion content in the control product; Such as, BASF Aktiengesellschaft requires less than 5ppm the chloride ion content in the polyisobutylene product of the relevant trade mark.Therefore the content detection to chlorion in the polyisobutylene has proposed very high requirement.

Detection method for chlorion mostly concentrates on chlorion detection in the WS.Like chlorion monitoring in the boiler water, chlorion detects in the potable water, in the sewage chlorion detect, chlorion monitoring etc. in the lime slurry.Testing sample is the WS, can directly measure chlorine ion concentration.The detection of chlorion also has patent report in the organism, detects chlorion detection etc. in the smooth liquid like chlorion in the organic amine.Patent documentation CN101587093 provides the wet-leveling liquid chlorine ion content determination method.This chlorine ion content determination has adopted calcining method, the organic amine material carbonization of feasible constraint chlorion, and the inorganics of formation solubility makes chlorion dissociate out, utilizes potentiometric titration to record.Patent documentation CN102253101A discloses that chlorion detection method method mainly comprises the steps: (1) polyisobutylene pre-service in a kind of polyisobutylene.Polyisobutylene sample low temperature brittleness in liquid nitrogen, and sample ground into the particle of particle diameter 100～200 μ m; (2) sample oxygenation burning in containing the oxygen Molotov cocktail of absorption liquid, chlorion is absorbed liquid and fully absorbs; (3) with the chloride ion content in the potentiometric determination absorption liquid; (4) content of chlorion in the calculating 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 the polyisobutylene is effectively separated out, thereby detects content of Cl element in the polyisobutylene polymkeric substance.

For the trace impurity in the polymkeric substance (like chlorion), because be covered by in the organic polymer, can't directly detect, need through The pretreatment.At present, the preprocess method that is used for polyisobutylene mainly adopts ashing method, 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, and condition is harsh.Adopt the free chloro ion in the dissolving precipitated method separation and Extraction polyisobutylene, utilize the ion chromatography electric conductivity detector to detect, through calculating chlorion chromatogram peak area, confirm chloride ion content, this method is not appeared in the newspapers.

Summary of the invention

To the deficiency of prior art, the present invention aims to provide a kind of detection method of polyisobutylene Free Chlorine ion.

The present invention realizes through following technical scheme:

Terminological interpretation

The chromatography of ions: chromatography of ions is according to ion exchange principle, comes the component in the sample separation based on the difference that different ions is moved on ion exchange column, and through galvanochemistry or fluorescence detector detected components.Chlorion is different with 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 then 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, compares with standard, comes the quantitative Analysis ion concentration according to chromatography of ions peak height or peak area.

Chemical titration: the chlorion chemical titration is that the silver nitrate standard solution with known accurate concentration is added drop-wise in the WS of chloride ion-containing; The amount and the chlorion of silver nitrate react completely by stoichiometric relationship just to add; Make indicator with potassium chromate, the AgNO of excessive dropping ₃Solution will with chromate ion (CrO ₄ ^2-) generation Ag ₂CrO ₄Brick-red deposition, the indication titration end-point.According to the concentration and the volume that is consumed of adding silver nitrate standard solution, calculate the content of chlorion then.

Potentiometric titration: the ultimate principle of potentiometric titration is similar with chemical titration, its difference be terminal point confirm confirm titration end-point through the hop of electrode potential.Before and after the chlorion titration end-point, the concentration of silver ions in the liquid to be measured often changes several magnitude, causes the hop of current potential, and it is easy, accurate that titration end-point is judged.The content of tested chlorion calculates through the amount that consumes the silver nitrate standard solution.

A kind of detection method of polyisobutylene Free Chlorine ion, step is following:

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is processed slowly drops in the water of 100-150mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates, inclining supernatant liquid; The polyisobutylene of separating out with 10mL water washing 1-2 time, is merged supernatant liquid and wash solution, and boil off solvent and the water that extracts in the solution; Add 10mL water logging elution and get chlorion, rock repeatedly, make in the complete water-soluble solution of chlorion on the container inner wall absorption liquid hold over night;

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

The mass content W of chlorion _ClCalculate by formula (1):

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

In the formula,

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

C _ClThe concentration of chlorion in the expression absorption liquid, the g/L of unit;

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

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

It is preferred according to the present invention,

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

Water described in the step (2) is ultrapure water.

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

Chlorion quantitative analysis method described in the 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 following:

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

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

Embodiment

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

Embodiment 1

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 100mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 15min, rotating speed 4500rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

(3) with 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 ^-1Sample feeding amount: 25 μ L; The result sees table 1.

Table 1

Chloride ion content calculates as follows in the polyisobutylene sample 1:

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

Embodiment 2

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 100mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 20min, rotating speed 4600rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

(3) with 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 ^-1Sample feeding amount: 25 μ L; The result sees table 2.

Table 2

Chloride ion content calculates in the polyisobutylene sample 2:

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

Embodiment 3

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 100mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 20min, rotating speed 4600rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

(3) with 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 ^-1Sample feeding amount: 25 μ L; The result sees table 3.

Table 3

Chloride ion content calculates in the polyisobutylene sample 3:

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

Embodiment 4

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 200mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 20min, rotating speed 4600rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

(3) with the chloride ion content of chemical titration absorption liquid: the 10mL absorption liquid is placed clean conical flask, and other gets a conical flask and does blank test with distilled water.Accurately add 0.1mL 5%K with transfer pipet ₂CrO ₄Solution is constantly shaking down with 1.0 * 10 ^-3Mol/L AgNO ₃Standard solution titration is to brick-red deposition occurring, 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 result sees table 4.

Table 4

Chloride ion content calculates in the polyisobutylene sample 2:

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

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

Embodiment 5

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 120mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 20min, rotating speed 4600rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

(3) with the chloride ion content of potentiometric determination absorption liquid: install titration apparatus, with silver nitrate standard solution (1.0 * 10 ^-3Mol/L) add in the buret.Put into magneton in the absorption liquid, and be placed on the stirrer.Regulate " terminal point current potential " knob, set demonstration terminal point potential value.After terminal point current potential and preparatory control point potential setting are good, " setting " switch is put " measurement ".Electrode is inserted in the detected solution, open stirrer, reconcile rotating speed, press " titration begins " button.Write down liquid volume reading V (mL) and corresponding current potential E value in the buret in the titration process.During near terminal point, every adding 0.1mL silver nitrate standard solution is write down its corresponding E value, confirms the silver nitrate standard solution that titration end-point consumes.Do parallel experiment and blank test with the same terms.The result sees table 5.

Table 5

Chloride ion content calculates in the polyisobutylene sample 2:

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

Claims (7)

1. the detection method of a polyisobutylene Free Chlorine ion, step is following:

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition, the homogeneous phase solution that step (1) is processed slowly drops in the water of 100-150mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates, inclining supernatant liquid; The polyisobutylene of separating out with 10mL water washing 1-2 time, is merged supernatant liquid and wash solution, and boil off solvent and the water that extracts in the solution; Add 10mL water logging elution and get chlorion, rock repeatedly, make in the complete water-soluble solution of chlorion on the container inner wall absorption liquid hold over night;

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

The mass content W of chlorion _ClCalculate by formula (1):

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

In the formula,

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

C _ClThe concentration of chlorion in the expression absorption liquid, the g/L of unit;

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

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

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

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

4. detection method as claimed in claim 1 is characterized in that, the high speed centrifugation described in the step (2), and the time is 15-20 minute, rotating speed 4500-4800rpm.

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

6. detection method as claimed in claim 5 is characterized in that, the chlorion quantitative analysis method described in the step (3) is the chromatography of ions.

7. detection method as claimed in claim 1 is characterized in that step is following:

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

(2) extraction of chlorion in the polyisobutylene: under stirring condition; The homogeneous phase solution that step (1) is processed slowly drops in the ultrapure water of 100mL, treat that polyisobutylene is separated out from water after, solution is carried out high speed centrifugation separates; Time 15min, rotating speed 4500rpm; Incline and supernatant liquid; The polyisobutylene of separating out with 10mL ultrapure water washing 2 times, is merged supernatant liquid and wash solution; Boil off the tetrahydrofuran and the water that extract in the solution; Add the 10mL ultrapure water and embathe the extraction chlorion, rock repeatedly, make and get absorption liquid, hold over night in the complete water-soluble solution of chlorion on the container inner wall;

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

Chloride ion content calculates as follows in the polyisobutylene sample 1:

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