This standard specifies the determination method of easily saponifiable chlorine in epoxy resins, glycidyl esters and 1-chloro-2,3-epoxypropane. The values ​​obtained represent the concentration of easily saponifiable chlorine in the chlorohydrin groups in these compounds. GB/T 4618-1984 Determination of easily saponifiable chlorine in epoxy resins and related materials GB/T4618-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Epoxide resins and related materialsDetermination of easily saponifiable chloriteUDC 678.68:546
GB 4618-84
This standard is equivalent to ISO4583-1978 "Plastics-Epoxy resins and related materials-Determination of easily saponifiable chlorite". 1 Scope of application
This standard specifies the determination method for easily saponifiable chlorite in epoxy resins, glycidyl esters and 1-chloro-2,3-propylene oxide. The values ​​obtained represent the concentration of easily saponifiable chlorine in the chlorohydrin group of these compounds. 2 References
GB4613-84 "Determination of inorganic chlorine in epoxy resins and glycidyl esters". 3 Principle
For epoxy resins, the sample is reacted with a solution of sodium hydroxide in 2-butoxyethanol at room temperature for 2 hours, or with a solution of sodium hydroxide in methanol at 50°C for glycidyl esters and epichlorohydrin. The mixture is acidified and the chloride ions generated by saponification are titrated potentiometrically with a standard silver nitrate titrant. The inorganic chlorine content of the sample is corrected according to the method specified in GB4613-84 "Determination of inorganic chlorine in epoxy resins and glycidyl esters". , Reagents
Only analytical reagents (unless otherwise specified) and only distilled water or water of equivalent purity are used in the analysis. 4.1 Glacial acetic acid: density 1.05 g/ml. 4.22 Butoxyethanol (ethylene glycol monobutyl ether), if used in industrial grade, needs to be refined. The refining method is as follows: add 15 g of sodium hydroxide to 1 liter of industrial grade 2-butoxyethanol and reflux the solution for 4 hours. Distill 2-butoxyethanol at a rate of 5 ml/min. Collect the fractions with boiling point above 165℃. Discard the last 100 ml of fraction. Store 2-butoxyethanol in a brown bottle filled with nitrogen in the dark.
Note: 2-Butoxyethanol is toxic. Avoid inhaling its vapor and prevent contact with skin and eyes. It should be refined in a fume hood or a well-ventilated place. The limit value is 50ppm.
4.3 Butanone (methyl ethyl ketone).
4.4 Sodium hydroxide: 120 g/L 2→butoxyethanol solution. Dissolve 120 g of sodium hydroxide in 75 ml of water, cool and dilute to 1 liter with 2-butoxyethanol. 4.5 Hydrochloric acid: 0.4% (mass/mass) solution. Mix 9 ml of concentrated hydrochloric acid with a density of approximately 1.19 g/ml with water and dilute to 1 liter. 4.6 Silver nitrate: 0.01N standard titrant. 4.6.1 Preparation
Dissolve 1.70 g of silver nitrate in water and dilute to 1 liter. 4.6.2 Calibration|| tt||Weigh 20-25 mg of standard sodium fluoride (accurate to 0.1 mg) pre-dried at 120℃, put it into a 250 ml conical flask, and dissolve it in 50 ml of water t1. Titrate with silver nitrate solution according to 6.1.4. Issued by the National Bureau of Standards on July 30, 1984
Implementation on May 1, 1985
4.6.3 Calculation of concentration
The equivalent concentration N is calculated according to formula (1):bzxZ.net
Where: m-the mass of sodium fluoride used, mg, GB4618-84
V-the volume of silver nitrate consumed in titration, ml, 58.45-the milligram equivalent of sodium chloride.
4.6.4 Storage
Store the solution in a dark place.
5 Instrument
（ 1)
5.1 Microburette: 10 ml capacity, minimum scale of 0.02 or 0.05 ml, with a capillary tip extending about 120 mm below the piston.
5.2 Magnetic stirrer.
5.3 pH millivoltmeter: preferably compensated type. With regular glass electrode and silver electrode. 5.4 Titration beaker: 400 ml capacity. 6 Procedure
6.1 Epoxy resin
6.1.1 Weigh a sample containing not more than 1.78 mg of easily saponifiable fluorine in a beaker. Pipette 25 ml of 2-butoxyethanol into the beaker and start the magnetic stirrer to dissolve the sample, heating if necessary. Cool the solution to room temperature, pipette 25 ml of sodium hydroxide solution into the beaker, mix thoroughly, cover the beaker, and let react. The mixture should be placed at room temperature for 2 hours. 6.1.2 Pipette 100 ml of butanone and 25 ml of glacial acetic acid into the mixture while stirring, and stir for a few minutes until the precipitate generated when the glacial acetic acid is added is completely dissolved. The titration should be carried out as soon as possible, otherwise a low value may be obtained. 6.1.3 Before each titration, wash the glass electrode with butanone, rinse it with water, soak it in hydrochloric acid for at least 10 minutes, and then rinse it with water and butanone. Before each titration, polish the silver electrode with fine sandpaper (such as metallographic 003 sandpaper) and rinse it with water. When the same type of product is measured frequently, the electrode can be treated once a day.
6.1.4 Place the electrode and the microburette containing the silver nitrate solution in the appropriate position, immerse the tip of the microburette in the liquid for about 10 mm, and stir throughout the titration process. Add the silver nitrate solution carefully, and wait until the potential no longer changes each time. During the titration process, it is best to avoid strong light irradiating the beaker and the electrode, otherwise, a black silver oxide layer may form on the surface of the silver electrode and the electrode may not react correctly.
Record the readings of the microburette and the millivoltmeter, and quickly draw a graph. When the potential changes very little each time the silver nitrate solution is added, add a volume of solution as large as 0.5 ml. When the rate of potential change becomes greater than 10 mV/0.5 ml, use 0.1 ml increments. Add about 0.5 ml after the inflection point and stop the titration.
Note: If it is found that the silver nitrate solution required for the titration is less than 1 ml (the same is true for the blank test), add 1 ml of 0.01N potassium chloride solution to the solution before titration and repeat the test (the same is true for the blank test). Titrate immediately after adding the potassium chloride solution. 6.1.5 Perform a blank test at the same time as the determination, following the same steps and using the same reagents, but without adding the sample. 6.1.6 Determine the inorganic chlorine content of the sample according to the method specified in GB4613-84. 6.2 Glycidyl esters and 1-fluoro-2,3-epoxypropane Note: 1-chloro-2,3-epoxypropane is highly toxic, its toxicity is cumulative, and it is flammable. Avoid inhaling its fumes and prevent contact with skin and eyes. Work in a ventilated or well-ventilated area. It can cause explosive reactions with sulfuric acid, concentrated alkali, metals, hydroxides, and anhydrous metal halides, such as tetravalent tin and trivalent iron chloride. Therefore, wear safety goggles and surround the instrument with a protective plate. The limit value is 5ppm.
GB 4618--84
6.2.1 Weigh a sample containing not more than 1.78 mg of easily saponifiable chlorine in a beaker. Pipette 25 ml of sodium hydroxide methanol solution into the beaker and use a magnetic stirrer to dissolve the sample. Cover the beaker and allow the reaction mixture to stand at 50°C for 2 hours. 6.2.2 Perform the test according to 6.1.26.1.6.
1 Expression of results
The easily saponifiable chlorine content M (mass percentage) is calculated according to formula (2): 35.5N(V - /)
10M.
Wherein: V. — Volume of silver nitrate solution used in blank test, ml, W,-
Volume of silver nitrate solution consumed in titration of sample, ml N—Equivalent concentration of silver nitrate solution calculated according to formula (1), M. —Mass of sample, g,
CInorganic chlorine content, mg/dry gram.
If the purity W of 1-chloro-2,3-epoxypropane sample needs to be expressed in weight percentage, it can be calculated according to formula (3): 92.5N(V- Vo)
The symbols in the formula have the same meaning as those in formula (2). 8 Test report
The test report shall include the following items:
Indicate according to this standard:
Full identification of the test material,
Inorganic chlorine content determined according to GB4613-84
Test results and the expression method used.
Additional remarks:
35.5×104
(3)
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is technically managed by the Chemical Method Branch of the National Technical Committee for Plastic Standardization. This standard was drafted by Shanghai Resin Factory. The main drafters of this standard are Li Boqing, Bao Limin and Wu Rongdong. 703
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