CN110987716B - Method for measuring concentration of boric acid in iodine polarizing film processing tank liquid - Google Patents

Method for measuring concentration of boric acid in iodine polarizing film processing tank liquid Download PDF

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CN110987716B
CN110987716B CN201911301532.8A CN201911301532A CN110987716B CN 110987716 B CN110987716 B CN 110987716B CN 201911301532 A CN201911301532 A CN 201911301532A CN 110987716 B CN110987716 B CN 110987716B
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邓崇浩
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Winda Opto Electronic Co ltd
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    • G01N5/04Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by removing a component, e.g. by evaporation, and weighing the remainder
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract

The invention discloses a method for measuring the concentration of boric acid in iodine polarizing film processing tank liquor, which comprises the following steps: s1, pretreating a sample to be detected, namely filtering the sample to be detected, adding carbon tetrachloride, extracting and leaving a water phase; s2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0; s3, moving 5-10 mL of the preprocessed sample to be detected in a crucible by using a transfer pipette, and recording the volume of the sample as V; s4, covering the crucible, putting the crucible into heating equipment for heating, raising the temperature to 600-1000 ℃, and preserving the heat for 10-40 min; s5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1; and S6, calculating the concentration of the boric acid according to M0, M1 and V. The method for measuring the concentration of the boric acid in the iodine polarizing film processing tank solution has the characteristics of simple operation, easy realization, less iodine interference, no need of large instruments, low cost and convenient popularization.

Description

Method for measuring concentration of boric acid in iodine polarizing film processing tank liquid
Technical Field
The invention relates to the technical field of boric acid concentration detection, in particular to a method for determining boric acid concentration in iodine polarizing film processing tank liquor.
Background
The polarizer is an important optical component in the LCD display device, and functions as an optical switch in the LCD display device to determine the passage and closing of the light path. In the production and manufacturing process of the polarizer, the processing and processing procedure of the polarizing film is the most important procedure in the whole production process and is also the procedure with the largest difficulty coefficient. In the dyeing treatment process of the iodine polarizing film, iodine is used as a dyeing solution, boric acid is added as a cross-linking agent to perform cross-linking reaction with the polarizing film, iodine molecules are diffused and doped into the polarizing film in the reaction process, and are combined with the polarizing film through Van der Waals force to play a role in enhancing the dimensional stability of the polarizing film, and meanwhile, the iodine molecules are combined with hydrogen bonds of the boric acid to be beneficial to fixing the iodine molecules in the polarizing film to play a role in color fixation and improve the weather resistance of the polarizing film, so the boric acid determines the quality of the polarizing film to a certain extent, and how to effectively monitor the boric acid content in the bath solution in the processing process of the iodine polarizing film has very important significance in manufacturing high-quality polarizing film products.
At present, methods for testing the content of boric acid include instrumental analysis methods and chemical analysis methods, wherein the instrumental analysis methods include spectrophotometry, potentiometric titration and inductively coupled plasma emission spectrometry, the methods generally need to be subjected to derivatization before detection, and have the defects of many analysis interference factors, complex operation, high detection equipment input cost and the like, while the chemical analysis methods include neutralization titration, although the cost is relatively low, the man-made interference is large when titration end point judgment exists, and different analysis operators have deviation in judgment of indicator end points, so that the same group of samples and different analyzers obtain analysis results with large deviation. It is seen that improvements and enhancements in the prior art are needed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a method for testing the boric acid content in the dyeing process of an iodine polarizing film, and aims to overcome the defects that the existing method for testing the boric acid content of a dyeing solution with iodine is not available in the prior art, and the existing operation for testing the boric acid content is complex and not accurate enough.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for measuring the concentration of boric acid in iodine polarizing film processing bath solution, wherein the method comprises the following steps:
s1, pretreating a sample to be detected, namely filtering the sample to be detected, adding carbon tetrachloride, extracting and retaining a water phase;
s2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 5-10 mL of the preprocessed sample to be detected in a crucible by using a transfer pipette, and recording the volume of the sample as V;
s4, covering the crucible, putting the crucible into heating equipment for heating, raising the temperature to 600-1000 ℃, and preserving the heat for 10-20 min;
s5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
and S6, calculating the concentration of the boric acid according to M0, M1 and V.
In the method for measuring the concentration of boric acid in the iodine polarizing film processing tank solution, in the step S1, the volume ratio of the amount of carbon tetrachloride added to the solution to be measured is 1-3: 1.
In the method for measuring the concentration of boric acid in the iodine polarizing film processing tank solution, in the step S1, the extraction times of carbon tetrachloride are 1-3 times.
In the method for measuring the concentration of boric acid in the iodine-based polarizing film processing bath solution, in the step S4, the temperature rise rate is 50 to 80 ℃/min.
In the method for measuring the concentration of boric acid in the iodine-based polarizing film processing bath solution, in the step S4, when the temperature is raised to 180 ℃, the temperature is maintained for 3-5 min.
Has the advantages that:
the invention provides a method for measuring the concentration of boric acid in iodine polarizing film processing tank liquor, according to the principle that boric acid is easy to decompose when heated, the mass percent of the boric acid in the solution can be calculated and obtained by measuring the weight of the solution before decomposition and the weight of boron trioxide after decomposition.
Detailed Description
The present invention provides a method for measuring boric acid concentration in iodine polarizing film processing bath solution, and the present invention will be further described in detail by way of examples in order to make the purpose, technical scheme and effect of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a method for measuring the concentration of boric acid in iodine polarizing film processing bath solution, which comprises the following steps:
step S1, pretreating a sample to be detected, taking the sample to be detected, filtering to remove solid impurities, adding carbon tetrachloride with the volume being 1-3 times that of the solution, extracting for 1-3 times by using a separating funnel, and keeping a water phase for later use.
S2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 5-10 mL of the preprocessed sample to be detected into a crucible by a pipette, and recording the volume of the sample as V;
and S4, placing the weighed sample into heating equipment for heating and roasting, wherein the heating speed is 50-80 ℃/min, the temperature is kept at 180 ℃ for 3-5 min, then the temperature is raised to 600-1000 ℃, and the temperature is kept for 10-20 min.
S5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
and S6, calculating the content of the boric acid according to M0, M1 and V.
The method for measuring the concentration of the boric acid in the iodine polarizing film processing tank liquid mainly utilizes the chemical characteristic that the boric acid is decomposed by heat, one part of water is firstly lost to form the metaboric acid in the heating process of the boric acid, the heating is continued, and the metaboric acid is completely decomposed and converted into the diboron trioxide when the temperature exceeds 600 ℃, and the specific reaction formula is as follows:
Figure BDA0002321919030000041
and the decomposed boron trioxide is a relatively stable solid substance at high temperature, and after cooling, the amount of boric acid can be obtained by measuring the amount of boron trioxide, so that the content or concentration of boric acid in the bath solution can be obtained.
In the method for measuring the boric acid concentration in the iodine polarizing film processing tank liquid, the volume (V) of the boric acid solution before decomposition and the weight (M1-M0) of the boron trioxide after decomposition are measured, and the mass concentration (mg/mL) of the boric acid is obtained according to the mass relation of each compound in the reaction formula as follows:
Cboric acid=1.776*(M1-M0)/V
Specifically, in the method for measuring the boric acid concentration in the iodine-based polarizing film processing bath solution, since the bath solution contains fine impurity particles and fine film debris falling from the polarizing film in water, and some of these fine solids are difficult to decompose and gasify even at high temperature, and easily interfere with the weight of the final diboron trioxide, these solid impurities are removed by filtration in step S1.
Further, since the sample solution contains iodine, which may interfere with the analysis result, but iodine is a non-polar molecule and is easily soluble in a non-polar carbon tetrachloride solution, iodine is removed from the solution by extracting iodine through carbon tetrachloride in step S1. In the extraction process, need control appearance liquid and carbon tetrachloride's proportion, when the concentration of iodine is higher, the carbon tetrachloride volume of adding is some more, when the concentration of iodine is low, can add the less carbon tetrachloride of volume ratio, and the volume ratio of general control carbon tetrachloride and sample solution is 1 ~ 3: 1 hour, has better extraction effect, simultaneously, can pass many times extraction, more complete removal of iodine in the solution.
Specifically, in the method for measuring the boric acid concentration in the iodine-based polarizing film processing bath solution, in the step S3, the sample volume of the boric acid solution sample is 5 to 10 mL. The sampling amount of the boric acid solution sample cannot be too small, when the concentration of boric acid is low, the sampling amount is too small, large errors are easily generated in the weighing of boron trioxide, when the sampling amount is too large, the time consumption for heating decomposition is long, the time for analyzing the sample is prolonged, and when the sampling amount is 5-10 mL, the sample is representative and has proper analysis time. It should be noted that, when the detection results of the parallel samples are very different and the boric acid content is low, the samples are re-sampled and detected, and the sampling amount is adjusted to 8-10 mL.
Specifically, in the method for measuring the concentration of boric acid in the iodine polarizing film processing tank solution, in the step S4, the temperature rise rate is controlled to be 50 to 80 ℃/min, the temperature rise rate influences the evaporation of water, the water can be completely removed at a proper temperature rise rate, and when the temperature rises to 180 ℃, the temperature is kept for 3 to 5min, so that the water, organic substances and other easily decomposed substances can be well removed, and the boric acid loses one molecule of water, and the metaboric acid is obtained. When the temperature is increased to 600-1000 ℃, the metaboric acid is heated and decomposed to obtain boron trioxide, the temperature is kept for 10-20 min, the metaboric acid can be decomposed more thoroughly, and the measured value of the boric acid content is accurate.
In the method for measuring the boric acid concentration in the iodine-based polarizing film processing bath solution, the number of parallel samples is not less than 3, and the weight of the crucible is required to be constant in both step S2 and step S5.
Example 1
A method for measuring the concentration of boric acid in iodine polarizing film processing bath solution comprises the following steps:
s1, pretreating a sample to be detected, namely taking the sample to be detected, filtering to remove solid impurities, adding carbon tetrachloride with the volume being 1 time that of the solution, extracting for 1 time by using a separating funnel, and keeping a water phase for later use.
S2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 10mL of the pretreated sample to be detected into a crucible by using a pipette, and recording the volume of the sample as V;
and S4, putting the weighed sample into heating equipment for roasting, wherein the heating rate is 80 ℃/min, keeping the temperature at 180 ℃ for 3min, then heating to 600 ℃, and keeping the temperature for 10 min.
S5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
and S6, calculating the content of the boric acid according to M0, M1 and V.
Example 2
A method for measuring the concentration of boric acid in iodine polarizing film processing bath solution comprises the following steps:
s1, pretreating a sample to be detected, taking the sample to be detected, filtering to remove solid impurities, adding carbon tetrachloride with 2 times of the volume of the solution, extracting for 2 times by using a separating funnel, and keeping a water phase for later use.
S2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 8mL of the pretreated sample to be detected into a crucible by using a pipette, and recording the volume of the sample as V;
and S4, putting the weighed sample into heating equipment for roasting, wherein the heating speed is 70 ℃/min, keeping the temperature at 180 ℃ for 4min, then heating to 800 ℃, and keeping the temperature for 15 min.
S5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
and S6, calculating the content of the boric acid according to M0, M1 and V.
Example 3
A method for determining the concentration of boric acid in an iodine based polarizing film processing bath, said method comprising the steps of:
s1, pretreating a sample to be detected, namely taking the sample to be detected, filtering to remove solid impurities, adding carbon tetrachloride with the volume being 3 times that of the solution, extracting for 3 times by using a separating funnel, and keeping a water phase for later use.
S2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 5mL of the pretreated sample to be detected into a crucible by using a pipette, and recording the volume of the sample as V;
and S4, putting the weighed sample into heating equipment for roasting, wherein the heating speed is 50 ℃/min, keeping the temperature at 180 ℃ for 5min, then heating to 1000 ℃, and keeping the temperature for 20 min.
S5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
and S6, calculating the content of the boric acid according to M0, M1 and V.
The method described in examples 1-3 above was used to test boric acid of known concentration, and the neutralization titration method and instrumental analysis method were used to compare the results, as shown in the following table:
Figure BDA0002321919030000071
the comparison of the data in the table shows that the boric acid content obtained by the method of the embodiments 1 to 3 of the invention is the closest to the real boric acid content value of the sample, and the deviation is the smallest, compared with a neutralization titration method and an instrument analysis method, the method has the characteristics of accurate data, less man-made interference, simple pretreatment, no need of large instruments, wide application in the measurement of the boric acid content, and better practicability.
It should be understood that equivalents and modifications of the technical solution and inventive concept thereof may occur to those skilled in the art, and all such modifications and alterations should fall within the scope of the appended claims.

Claims (5)

1. A method for measuring the concentration of boric acid in iodine polarizing film processing bath solution, characterized in that the method comprises the steps of:
s1, pretreating a sample to be detected, namely filtering the sample to be detected, adding carbon tetrachloride, extracting and retaining a water phase;
s2, accurately weighing the weight of the clean crucible with the cover by using an electronic balance, and recording the weight as M0;
s3, moving 5-10 mL of the pretreated sample to be detected into a crucible by using a pipette, and recording the volume of the sample as V;
s4, covering the crucible, putting the crucible into heating equipment for heating, raising the temperature to 600-1000 ℃, and preserving the heat for 10-20 min;
s5, after baking and sintering, cooling to room temperature, taking out the crucible, keeping constant weight, and weighing the crucible by using an electronic balance, wherein the weight is marked as M1;
s6, calculating the concentration of the boric acid according to M0, M1 and V, wherein the calculation formula of the concentration of the boric acid is as follows: cBoric acid=1.776*(M1-M0)/V。
2. The method for measuring the concentration of boric acid in iodine based polarizing film processing bath according to claim 1, wherein in step S1, the volume ratio of the amount of carbon tetrachloride added to the solution to be measured is 1-3: 1.
3. The method of claim 2, wherein the number of carbon tetrachloride extractions in step S1 is 1 to 3.
4. The method of claim 1, wherein the temperature increase rate in step S4 is 50-80 ℃/min.
5. The method of claim 1, wherein the temperature is maintained at 180 ℃ for 3-5 min in step S4.
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