This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, storage and transportation of industrial maleic anhydride products. This standard applies to industrial maleic anhydride produced by catalytic oxidation of benzene or petroleum carbon four fractions as raw materials. Its main uses are raw materials for unsaturated polyester resins, paints, pesticides and medicines. GB 3676-1992 Industrial maleic anhydride GB3676-1992 Standard download and decompression password: www.bzxz.net

National Standard of the People's Republic of China
Maleic anhydride for industrial use
Maleic anhydride for industrial use This standard refers to the international standard ISO13901977 "Test Method for Industrial Maleic Anhydride". Subject content and scope of application
GB3676--92
Replaces GB3676--83
This standard specifies the technical requirements, test methods, inspection rules and markings for industrial maleic anhydride products , packaging, storage and transportation, etc.
This standard applies to industrial maleic anhydride produced by catalytic oxidation of benzene or petroleum carbon four fractions as raw materials. Its main uses are raw materials for unsaturated polyester resins, paints, pesticides and medicines. Molecular formula: C,H.O3
Relative molecular mass: 98.058 (according to the 1987 international relative atomic mass) 2 reference standards
GB601
GB603
GB1250||tt ||GB3049
GB3143
GB6679
GB6682
GB7531
GB7533
GB8170
3 technical requirements||tt ||Chemical reagents
Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents Test methods Preparation limit values ??of preparations and products used in the method of expression and determination methods General method for determination of iron content in chemical products Phenoline Spectrophotometric Method for Color Determination of Liquid Chemical Products (Hazen Unit - Platinum-Diamond Color Number) General Rules for Sampling Solid Chemical Products
Laboratory Water Specifications
Determination of Ash Content of Organic Chemical Products||tt| |Numerical Rounding Rules for Test Methods for Crystallization Temperature of Organic Chemical Products
3.1 Appearance: white, yellowish block or flake crystals. 3.2 The quality of industrial maleic anhydride should meet the requirements in the table below. Head
Content (based on maleic anhydride), %
Melt color (platinum-cobalt), No.
Crystallization point, ℃
Ash content, %
Iron content (calculated as Fe), ppm
Superior product approved by the State Bureau of Technical Supervision on 1992-01-14
99.5
25
52.4| |tt||0.005
First-class product
99.0
50
52.0
0.005
Qualified product
98.5
100
51.5
Implemented on 1992-12-01
4 test methods
GB3676-92
The reagents used in this standard are Unless other requirements are noted, all reagents are of analytical grade. The water used in this standard should comply with the third-level water specifications of GB6682. The standard solutions, preparations and products used in this standard shall be prepared according to the methods specified in GB601 and GB603 unless other requirements are specified.
4.1 Determination of content
4.1.1 Principle
Titrate with sodium hydroxide standard titration solution and use phenolphthalein as indicator. 4.1.2 Reagents and solutions
4.1.2.1 Sodium hydroxide standard titration solution: c(NaOH)=0.5mol/L. 4.1.2.2 Phenolic indicator: 10g/L.
4.1.3 Analysis steps
Weigh 1g sample, accurate to 0.0002g. Place it in a 250mL stoppered Erlenmeyer flask, use a buret to add 35mL sodium hydroxide standard titration solution and 35mL newly boiled and cooled water, heat slightly until the sample is completely dissolved, cool to 20~30℃, add two drops of phenolphthalein to indicate agent, and then use sodium hydroxide standard titration solution to continue titrating until it is slightly red, and the end point is if it does not fade for 30 seconds. 4.1.4 Calculation of results
content is calculated according to formula (1):
where: —
V-
V : c× 0. 049 03 × 100| |tt||m
content (based on maleic anhydride), %; consumption volume of sodium hydroxide standard titration solution, mL; c - concentration of sodium hydroxide standard titration solution, mol/L; ·(1)
The mass of a sample, g;
m
is equivalent to 1.00mL sodium hydroxide standard titration solution [c(NaOH)=1.000mol/L) Mass of maleic anhydride expressed in grams.
4.1.5 Allowable difference
The difference between the results of two parallel measurements shall not be greater than 0.2%, and the arithmetic mean shall be taken as the measurement result. 4.2 Determination of melt colorimetry
4.2.1 Analysis steps
According to the method specified in GB3143, take an appropriate amount of sample and place it in a 50mL colorimetric tube, and heat it in a water bath at 65±2℃ (Avoid water vapor intrusion). Immediately after the sample is melted, adjust the sample volume to the scale and visually inspect the axial direction. When there is white precipitate in the molten sample that affects the colorimetry, the supernatant can be poured into another 50mL colorimetric tube and brought to the mark, and then the colorimetry can be performed again. This operation is only suitable for qualified products. 4.3 Determination of crystallization point
shall be carried out according to the method specified in GB7533.
4.3.1 The length of the crystallizer tube is 130mm; the length of the protection tube is 110mm. 4.3.2 The main thermometer has a range of 40~70℃ and a length of 30~35cm. 4.3.3 Heating bath: 65±2℃ constant temperature water bath. 4.3.4 Cooling bath: air cooling.
4.3.5 Weigh the sample to about 35g. bzxz.net
4.4 Determination of ash content
According to the method specified in GB7531.
GB3676—92
Weighing sample size is 50g, accurate to 1g. The burning temperature is 650±25℃. Retain the residue A in the crucible for iron content determination. 4.5 Determination of iron content
shall be carried out according to the method specified in GB3049. || tt | Transfer to a 100mL volumetric flask. The following operations are carried out in accordance with the regulations of GB3049. 4.5.2 Calculation of results
The iron content is calculated according to formula (2).
m
2
m2
where: 2 iron content, Ppm
m, detected iron content, ug
m2—The mass of the sample taken when measuring ash content, g. 4.5.3 Allowable difference
The relative difference between the results of two parallel measurements shall not be greater than 20%, and the arithmetic mean shall be taken as the measurement result. 5 Inspection Rules
·(2)
5.1 This product shall be inspected by the quality supervision and inspection department of the manufacturer. The manufacturer shall ensure that all indicators of the manufactured product meet the requirements of this standard.
5.2 The user has the right to inspect and accept the industrial maleic anhydride received in accordance with the technical conditions, inspection rules, and inspection methods specified in this standard.
5.3 Sampling shall be carried out in accordance with the provisions of GB6679, and the weight of each batch shall not exceed 30t. For block products, the maximum size of each block should not exceed 10cm. 5.4 When taking samples, use a clean and dry sampler to go deep into the upper, middle and lower layers of the packaging bag to take evenly. The sampling amount shall not be less than 500g. After mixing evenly, put them into two clean, dry, brown grinding wide-mouth bottles. Seal it with polytetrafluoroethylene, attach a label, indicate the product name, batch number and sampling date. One bottle will be inspected, and the other bottle will be kept as a sample and stored for three months. 5.5 The sample measurement should be carried out within one week after sampling. During the measurement, the sample should be ground quickly in a dry mortar and mixed evenly to avoid water vapor intrusion.
5.6 If any of the inspection results does not meet the requirements of this standard, samples should be re-selected from twice the amount of packaging for re-inspection. If even one indicator does not meet the requirements of this standard, the entire batch of products will be deemed unqualified. 5.7 When a dispute arises between the supply and demand parties over product quality, the arbitration unit can be selected by both parties through negotiation and conduct re-inspection in accordance with the provisions of this standard. 5.8 The judgment of the inspection results shall be carried out according to the rounding value comparison method in GB1250, and the rounding shall be carried out according to GB8170. 6 Packaging, marking, storage and transportation
6.1 Industrial maleic anhydride product packaging should be packed in large iron barrels, wooden barrels or woven bags, lined with polyethylene plastic bags, and the bag mouth should be heat-sealed or tied with rope. Each package has a net weight of 25kg or 50kg. There is a registered trademark printed on the outside of the package. 6.2 Each batch of products should be accompanied by a certificate indicating the name of the manufacturer, batch number, grade and net weight. 6.3. Industrial maleic anhydride is stored in a dry and ventilated warehouse, protected from fire, moisture, rain and sunlight. The storage period is three months from the date of leaving the factory.
6.4 During storage and transportation, do not mix with acids and alkalis or come into contact with oxidizing and corrosive substances to avoid product deterioration. Be careful when transporting to prevent damage to the packaging bag.
Additional notes:
GB3676-92
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of the Beijing Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard is drafted by Tianjin Zhonghe Chemical Plant. The main technical indicators of this standard refer to the American Society for Testing and Materials standard ASTMD3504-82 "Specification Standard Maleic Anhydride".
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